diff options
author | Simon Glass <sjg@chromium.org> | 2021-03-18 20:25:12 +1300 |
---|---|---|
committer | Simon Glass <sjg@chromium.org> | 2021-03-26 17:03:10 +1300 |
commit | 5ce319133b2364e3283c3cde7a269681ff8431af (patch) | |
tree | 2badbcc08d4e19d9c1319deac066c54559e919c8 /doc/driver-model | |
parent | d1ceeeff6c2ee1e55b7140654c8d6de44b60dab6 (diff) | |
download | u-boot-5ce319133b2364e3283c3cde7a269681ff8431af.zip u-boot-5ce319133b2364e3283c3cde7a269681ff8431af.tar.gz u-boot-5ce319133b2364e3283c3cde7a269681ff8431af.tar.bz2 |
doc: Move driver model docs under develop/
These docs are useful for developers, not users. Move them under that
section.
Suggested-by: Heinrich Schuchardt <xypron.glpk@gmx.de>
Signed-off-by: Simon Glass <sjg@chromium.org>
Diffstat (limited to 'doc/driver-model')
-rw-r--r-- | doc/driver-model/bind.rst | 49 | ||||
-rw-r--r-- | doc/driver-model/debugging.rst | 62 | ||||
-rw-r--r-- | doc/driver-model/design.rst | 1016 | ||||
-rw-r--r-- | doc/driver-model/ethernet.rst | 321 | ||||
-rw-r--r-- | doc/driver-model/fdt-fixup.rst | 132 | ||||
-rw-r--r-- | doc/driver-model/fs_firmware_loader.rst | 154 | ||||
-rw-r--r-- | doc/driver-model/i2c-howto.rst | 56 | ||||
-rw-r--r-- | doc/driver-model/index.rst | 25 | ||||
-rw-r--r-- | doc/driver-model/livetree.rst | 286 | ||||
-rw-r--r-- | doc/driver-model/migration.rst | 101 | ||||
-rw-r--r-- | doc/driver-model/of-plat.rst | 913 | ||||
-rw-r--r-- | doc/driver-model/pci-info.rst | 172 | ||||
-rw-r--r-- | doc/driver-model/pmic-framework.rst | 143 | ||||
-rw-r--r-- | doc/driver-model/remoteproc-framework.rst | 169 | ||||
-rw-r--r-- | doc/driver-model/serial-howto.rst | 46 | ||||
-rw-r--r-- | doc/driver-model/soc-framework.rst | 68 | ||||
-rw-r--r-- | doc/driver-model/spi-howto.rst | 692 | ||||
-rw-r--r-- | doc/driver-model/usb-info.rst | 423 |
18 files changed, 0 insertions, 4828 deletions
diff --git a/doc/driver-model/bind.rst b/doc/driver-model/bind.rst deleted file mode 100644 index b19661b..0000000 --- a/doc/driver-model/bind.rst +++ /dev/null @@ -1,49 +0,0 @@ -.. SPDX-License-Identifier: GPL-2.0+ -.. sectionauthor:: Patrice Chotard <patrice.chotard@foss.st.com> - -Binding/unbinding a driver -========================== - -This document aims to describe the bind and unbind commands. - -For debugging purpose, it should be useful to bind or unbind a driver from -the U-boot command line. - -The unbind command calls the remove device driver callback and unbind the -device from its driver. - -The bind command binds a device to its driver. - -In some cases it can be useful to be able to bind a device to a driver from -the command line. -The obvious example is for versatile devices such as USB gadget. -Another use case is when the devices are not yet ready at startup and -require some setup before the drivers are bound (ex: FPGA which bitsream is -fetched from a mass storage or ethernet) - -usage: - -bind <node path> <driver> -bind <class> <index> <driver> - -unbind <node path> -unbind <class> <index> -unbind <class> <index> <driver> - -Where: - - <node path> is the node's device tree path - - <class> is one of the class available in the list given by the "dm uclass" - command or first column of "dm tree" command. - - <index> is the index of the parent's node (second column of "dm tree" output). - - <driver> is the driver name to bind given by the "dm drivers" command or the by - the fourth column of "dm tree" output. - -example: - -bind usb_dev_generic 0 usb_ether -unbind usb_dev_generic 0 usb_ether -or -unbind eth 1 - -bind /ocp/omap_dwc3@48380000/usb@48390000 usb_ether -unbind /ocp/omap_dwc3@48380000/usb@48390000 diff --git a/doc/driver-model/debugging.rst b/doc/driver-model/debugging.rst deleted file mode 100644 index bbb2794..0000000 --- a/doc/driver-model/debugging.rst +++ /dev/null @@ -1,62 +0,0 @@ -.. SPDX-License-Identifier: GPL-2.0+ -.. sectionauthor:: Simon Glass <sjg@chromium.org> - -Debugging driver model -====================== - -This document aims to provide help when you cannot work out why driver model is -not doing what you expect. - - -Useful techniques in general ----------------------------- - -Here are some useful debugging features generally. - - - If you are writing a new feature, consider doing it in sandbox instead of - on your board. Sandbox has no limits, allows easy debugging (e.g. gdb) and - you can write emulators for most common devices. - - Put '#define DEBUG' at the top of a file, to activate all the debug() and - log_debug() statements in that file. - - Where logging is used, change the logging level, e.g. in SPL with - CONFIG_SPL_LOG_MAX_LEVEL=7 (which is LOGL_DEBUG) and - CONFIG_LOG_DEFAULT_LEVEL=7 - - Where logging of return values is implemented with log_msg_ret(), set - CONFIG_LOG_ERROR_RETURN=y to see exactly where the error is happening - - Make sure you have a debug UART enabled - see CONFIG_DEBUG_UART. With this - you can get serial output (printf(), etc.) before the serial driver is - running. - - Use a JTAG emulator to set breakpoints and single-step through code - -Not that most of these increase code/data size somewhat when enabled. - - -Failure to locate a device --------------------------- - -Let's say you have uclass_first_device_err() and it is not finding anything. - -If it is returning an error, then that gives you a clue. Look up linux/errno.h -to see errors. Common ones are: - - - -ENOMEM which indicates that memory is short. If it happens in SPL or - before relocation in U-Boot, check CONFIG_SPL_SYS_MALLOC_F_LEN and - CONFIG_SYS_MALLOC_F_LEN as they may need to be larger. Add '#define DEBUG' - at the very top of malloc_simple.c to get an idea of where your memory is - going. - - -EINVAL which typically indicates that something was missing or wrong in - the device tree node. Check that everything is correct and look at the - of_to_plat() method in the driver. - -If there is no error, you should check if the device is actually bound. Call -dm_dump_all() just before you locate the device to make sure it exists. - -If it does not exist, check your device tree compatible strings match up with -what the driver expects (in the struct udevice_id array). - -If you are using of-platdata (e.g. CONFIG_SPL_OF_PLATDATA), check that the -driver name is the same as the first compatible string in the device tree (with -invalid-variable characters converted to underscore). - -If you are really stuck, putting '#define LOG_DEBUG' at the top of -drivers/core/lists.c should show you what is going on. diff --git a/doc/driver-model/design.rst b/doc/driver-model/design.rst deleted file mode 100644 index 4e5cecb..0000000 --- a/doc/driver-model/design.rst +++ /dev/null @@ -1,1016 +0,0 @@ -.. SPDX-License-Identifier: GPL-2.0+ -.. sectionauthor:: Simon Glass <sjg@chromium.org> - -Design Details -============== - -This README contains high-level information about driver model, a unified -way of declaring and accessing drivers in U-Boot. The original work was done -by: - - * Marek Vasut <marex@denx.de> - * Pavel Herrmann <morpheus.ibis@gmail.com> - * Viktor KÅ™ivák <viktor.krivak@gmail.com> - * Tomas Hlavacek <tmshlvck@gmail.com> - -This has been both simplified and extended into the current implementation -by: - - * Simon Glass <sjg@chromium.org> - - -Terminology ------------ - -Uclass - a group of devices which operate in the same way. A uclass provides - a way of accessing individual devices within the group, but always - using the same interface. For example a GPIO uclass provides - operations for get/set value. An I2C uclass may have 10 I2C ports, - 4 with one driver, and 6 with another. - -Driver - some code which talks to a peripheral and presents a higher-level - interface to it. - -Device - an instance of a driver, tied to a particular port or peripheral. - - -How to try it -------------- - -Build U-Boot sandbox and run it:: - - make sandbox_defconfig - make - ./u-boot -d u-boot.dtb - - (type 'reset' to exit U-Boot) - - -There is a uclass called 'demo'. This uclass handles -saying hello, and reporting its status. There are two drivers in this -uclass: - - - simple: Just prints a message for hello, doesn't implement status - - shape: Prints shapes and reports number of characters printed as status - -The demo class is pretty simple, but not trivial. The intention is that it -can be used for testing, so it will implement all driver model features and -provide good code coverage of them. It does have multiple drivers, it -handles parameter data and plat (data which tells the driver how -to operate on a particular platform) and it uses private driver data. - -To try it, see the example session below:: - - =>demo hello 1 - Hello '@' from 07981110: red 4 - =>demo status 2 - Status: 0 - =>demo hello 2 - g - r@ - e@@ - e@@@ - n@@@@ - g@@@@@ - =>demo status 2 - Status: 21 - =>demo hello 4 ^ - y^^^ - e^^^^^ - l^^^^^^^ - l^^^^^^^ - o^^^^^ - w^^^ - =>demo status 4 - Status: 36 - => - - -Running the tests ------------------ - -The intent with driver model is that the core portion has 100% test coverage -in sandbox, and every uclass has its own test. As a move towards this, tests -are provided in test/dm. To run them, try:: - - ./test/py/test.py --bd sandbox --build -k ut_dm -v - -You should see something like this:: - - (venv)$ ./test/py/test.py --bd sandbox --build -k ut_dm -v - +make O=/root/u-boot/build-sandbox -s sandbox_defconfig - +make O=/root/u-boot/build-sandbox -s -j8 - ============================= test session starts ============================== - platform linux2 -- Python 2.7.5, pytest-2.9.0, py-1.4.31, pluggy-0.3.1 -- /root/u-boot/venv/bin/python - cachedir: .cache - rootdir: /root/u-boot, inifile: - collected 199 items - - test/py/tests/test_ut.py::test_ut_dm_init PASSED - test/py/tests/test_ut.py::test_ut[ut_dm_adc_bind] PASSED - test/py/tests/test_ut.py::test_ut[ut_dm_adc_multi_channel_conversion] PASSED - test/py/tests/test_ut.py::test_ut[ut_dm_adc_multi_channel_shot] PASSED - test/py/tests/test_ut.py::test_ut[ut_dm_adc_single_channel_conversion] PASSED - test/py/tests/test_ut.py::test_ut[ut_dm_adc_single_channel_shot] PASSED - test/py/tests/test_ut.py::test_ut[ut_dm_adc_supply] PASSED - test/py/tests/test_ut.py::test_ut[ut_dm_adc_wrong_channel_selection] PASSED - test/py/tests/test_ut.py::test_ut[ut_dm_autobind] PASSED - test/py/tests/test_ut.py::test_ut[ut_dm_autobind_uclass_pdata_alloc] PASSED - test/py/tests/test_ut.py::test_ut[ut_dm_autobind_uclass_pdata_valid] PASSED - test/py/tests/test_ut.py::test_ut[ut_dm_autoprobe] PASSED - test/py/tests/test_ut.py::test_ut[ut_dm_bus_child_post_bind] PASSED - test/py/tests/test_ut.py::test_ut[ut_dm_bus_child_post_bind_uclass] PASSED - test/py/tests/test_ut.py::test_ut[ut_dm_bus_child_pre_probe_uclass] PASSED - test/py/tests/test_ut.py::test_ut[ut_dm_bus_children] PASSED - test/py/tests/test_ut.py::test_ut[ut_dm_bus_children_funcs] PASSED - test/py/tests/test_ut.py::test_ut[ut_dm_bus_children_iterators] PASSED - test/py/tests/test_ut.py::test_ut[ut_dm_bus_parent_data] PASSED - test/py/tests/test_ut.py::test_ut[ut_dm_bus_parent_data_uclass] PASSED - test/py/tests/test_ut.py::test_ut[ut_dm_bus_parent_ops] PASSED - test/py/tests/test_ut.py::test_ut[ut_dm_bus_parent_platdata] PASSED - test/py/tests/test_ut.py::test_ut[ut_dm_bus_parent_platdata_uclass] PASSED - test/py/tests/test_ut.py::test_ut[ut_dm_children] PASSED - test/py/tests/test_ut.py::test_ut[ut_dm_clk_base] PASSED - test/py/tests/test_ut.py::test_ut[ut_dm_clk_periph] PASSED - test/py/tests/test_ut.py::test_ut[ut_dm_device_get_uclass_id] PASSED - test/py/tests/test_ut.py::test_ut[ut_dm_eth] PASSED - test/py/tests/test_ut.py::test_ut[ut_dm_eth_act] PASSED - test/py/tests/test_ut.py::test_ut[ut_dm_eth_alias] PASSED - test/py/tests/test_ut.py::test_ut[ut_dm_eth_prime] PASSED - test/py/tests/test_ut.py::test_ut[ut_dm_eth_rotate] PASSED - test/py/tests/test_ut.py::test_ut[ut_dm_fdt] PASSED - test/py/tests/test_ut.py::test_ut[ut_dm_fdt_offset] PASSED - test/py/tests/test_ut.py::test_ut[ut_dm_fdt_pre_reloc] PASSED - test/py/tests/test_ut.py::test_ut[ut_dm_fdt_uclass_seq] PASSED - test/py/tests/test_ut.py::test_ut[ut_dm_gpio] PASSED - test/py/tests/test_ut.py::test_ut[ut_dm_gpio_anon] PASSED - test/py/tests/test_ut.py::test_ut[ut_dm_gpio_copy] PASSED - test/py/tests/test_ut.py::test_ut[ut_dm_gpio_leak] PASSED - test/py/tests/test_ut.py::test_ut[ut_dm_gpio_phandles] PASSED - test/py/tests/test_ut.py::test_ut[ut_dm_gpio_requestf] PASSED - test/py/tests/test_ut.py::test_ut[ut_dm_i2c_bytewise] PASSED - test/py/tests/test_ut.py::test_ut[ut_dm_i2c_find] PASSED - test/py/tests/test_ut.py::test_ut[ut_dm_i2c_offset] PASSED - test/py/tests/test_ut.py::test_ut[ut_dm_i2c_offset_len] PASSED - test/py/tests/test_ut.py::test_ut[ut_dm_i2c_probe_empty] PASSED - test/py/tests/test_ut.py::test_ut[ut_dm_i2c_read_write] PASSED - test/py/tests/test_ut.py::test_ut[ut_dm_i2c_speed] PASSED - test/py/tests/test_ut.py::test_ut[ut_dm_leak] PASSED - test/py/tests/test_ut.py::test_ut[ut_dm_led_base] PASSED - test/py/tests/test_ut.py::test_ut[ut_dm_led_gpio] PASSED - test/py/tests/test_ut.py::test_ut[ut_dm_led_label] PASSED - test/py/tests/test_ut.py::test_ut[ut_dm_lifecycle] PASSED - test/py/tests/test_ut.py::test_ut[ut_dm_mmc_base] PASSED - test/py/tests/test_ut.py::test_ut[ut_dm_net_retry] PASSED - test/py/tests/test_ut.py::test_ut[ut_dm_operations] PASSED - test/py/tests/test_ut.py::test_ut[ut_dm_ordering] PASSED - test/py/tests/test_ut.py::test_ut[ut_dm_pci_base] PASSED - test/py/tests/test_ut.py::test_ut[ut_dm_pci_busnum] PASSED - test/py/tests/test_ut.py::test_ut[ut_dm_pci_swapcase] PASSED - test/py/tests/test_ut.py::test_ut[ut_dm_platdata] PASSED - test/py/tests/test_ut.py::test_ut[ut_dm_power_pmic_get] PASSED - test/py/tests/test_ut.py::test_ut[ut_dm_power_pmic_io] PASSED - test/py/tests/test_ut.py::test_ut[ut_dm_power_regulator_autoset] PASSED - test/py/tests/test_ut.py::test_ut[ut_dm_power_regulator_autoset_list] PASSED - test/py/tests/test_ut.py::test_ut[ut_dm_power_regulator_get] PASSED - test/py/tests/test_ut.py::test_ut[ut_dm_power_regulator_set_get_current] PASSED - test/py/tests/test_ut.py::test_ut[ut_dm_power_regulator_set_get_enable] PASSED - test/py/tests/test_ut.py::test_ut[ut_dm_power_regulator_set_get_mode] PASSED - test/py/tests/test_ut.py::test_ut[ut_dm_power_regulator_set_get_voltage] PASSED - test/py/tests/test_ut.py::test_ut[ut_dm_pre_reloc] PASSED - test/py/tests/test_ut.py::test_ut[ut_dm_ram_base] PASSED - test/py/tests/test_ut.py::test_ut[ut_dm_regmap_base] PASSED - test/py/tests/test_ut.py::test_ut[ut_dm_regmap_syscon] PASSED - test/py/tests/test_ut.py::test_ut[ut_dm_remoteproc_base] PASSED - test/py/tests/test_ut.py::test_ut[ut_dm_remove] PASSED - test/py/tests/test_ut.py::test_ut[ut_dm_reset_base] PASSED - test/py/tests/test_ut.py::test_ut[ut_dm_reset_walk] PASSED - test/py/tests/test_ut.py::test_ut[ut_dm_rtc_base] PASSED - test/py/tests/test_ut.py::test_ut[ut_dm_rtc_dual] PASSED - test/py/tests/test_ut.py::test_ut[ut_dm_rtc_reset] PASSED - test/py/tests/test_ut.py::test_ut[ut_dm_rtc_set_get] PASSED - test/py/tests/test_ut.py::test_ut[ut_dm_spi_find] PASSED - test/py/tests/test_ut.py::test_ut[ut_dm_spi_flash] PASSED - test/py/tests/test_ut.py::test_ut[ut_dm_spi_xfer] PASSED - test/py/tests/test_ut.py::test_ut[ut_dm_syscon_base] PASSED - test/py/tests/test_ut.py::test_ut[ut_dm_syscon_by_driver_data] PASSED - test/py/tests/test_ut.py::test_ut[ut_dm_timer_base] PASSED - test/py/tests/test_ut.py::test_ut[ut_dm_uclass] PASSED - test/py/tests/test_ut.py::test_ut[ut_dm_uclass_before_ready] PASSED - test/py/tests/test_ut.py::test_ut[ut_dm_uclass_devices_find] PASSED - test/py/tests/test_ut.py::test_ut[ut_dm_uclass_devices_find_by_name] PASSED - test/py/tests/test_ut.py::test_ut[ut_dm_uclass_devices_get] PASSED - test/py/tests/test_ut.py::test_ut[ut_dm_uclass_devices_get_by_name] PASSED - test/py/tests/test_ut.py::test_ut[ut_dm_usb_base] PASSED - test/py/tests/test_ut.py::test_ut[ut_dm_usb_flash] PASSED - test/py/tests/test_ut.py::test_ut[ut_dm_usb_keyb] PASSED - test/py/tests/test_ut.py::test_ut[ut_dm_usb_multi] PASSED - test/py/tests/test_ut.py::test_ut[ut_dm_usb_remove] PASSED - test/py/tests/test_ut.py::test_ut[ut_dm_usb_tree] PASSED - test/py/tests/test_ut.py::test_ut[ut_dm_usb_tree_remove] PASSED - test/py/tests/test_ut.py::test_ut[ut_dm_usb_tree_reorder] PASSED - test/py/tests/test_ut.py::test_ut[ut_dm_video_base] PASSED - test/py/tests/test_ut.py::test_ut[ut_dm_video_bmp] PASSED - test/py/tests/test_ut.py::test_ut[ut_dm_video_bmp_comp] PASSED - test/py/tests/test_ut.py::test_ut[ut_dm_video_chars] PASSED - test/py/tests/test_ut.py::test_ut[ut_dm_video_context] PASSED - test/py/tests/test_ut.py::test_ut[ut_dm_video_rotation1] PASSED - test/py/tests/test_ut.py::test_ut[ut_dm_video_rotation2] PASSED - test/py/tests/test_ut.py::test_ut[ut_dm_video_rotation3] PASSED - test/py/tests/test_ut.py::test_ut[ut_dm_video_text] PASSED - test/py/tests/test_ut.py::test_ut[ut_dm_video_truetype] PASSED - test/py/tests/test_ut.py::test_ut[ut_dm_video_truetype_bs] PASSED - test/py/tests/test_ut.py::test_ut[ut_dm_video_truetype_scroll] PASSED - - ======================= 84 tests deselected by '-kut_dm' ======================= - ================== 115 passed, 84 deselected in 3.77 seconds =================== - -What is going on? ------------------ - -Let's start at the top. The demo command is in cmd/demo.c. It does -the usual command processing and then: - -.. code-block:: c - - struct udevice *demo_dev; - - ret = uclass_get_device(UCLASS_DEMO, devnum, &demo_dev); - -UCLASS_DEMO means the class of devices which implement 'demo'. Other -classes might be MMC, or GPIO, hashing or serial. The idea is that the -devices in the class all share a particular way of working. The class -presents a unified view of all these devices to U-Boot. - -This function looks up a device for the demo uclass. Given a device -number we can find the device because all devices have registered with -the UCLASS_DEMO uclass. - -The device is automatically activated ready for use by uclass_get_device(). - -Now that we have the device we can do things like: - -.. code-block:: c - - return demo_hello(demo_dev, ch); - -This function is in the demo uclass. It takes care of calling the 'hello' -method of the relevant driver. Bearing in mind that there are two drivers, -this particular device may use one or other of them. - -The code for demo_hello() is in drivers/demo/demo-uclass.c: - -.. code-block:: c - - int demo_hello(struct udevice *dev, int ch) - { - const struct demo_ops *ops = device_get_ops(dev); - - if (!ops->hello) - return -ENOSYS; - - return ops->hello(dev, ch); - } - -As you can see it just calls the relevant driver method. One of these is -in drivers/demo/demo-simple.c: - -.. code-block:: c - - static int simple_hello(struct udevice *dev, int ch) - { - const struct dm_demo_pdata *pdata = dev_get_plat(dev); - - printf("Hello from %08x: %s %d\n", map_to_sysmem(dev), - pdata->colour, pdata->sides); - - return 0; - } - - -So that is a trip from top (command execution) to bottom (driver action) -but it leaves a lot of topics to address. - - -Declaring Drivers ------------------ - -A driver declaration looks something like this (see -drivers/demo/demo-shape.c): - -.. code-block:: c - - static const struct demo_ops shape_ops = { - .hello = shape_hello, - .status = shape_status, - }; - - U_BOOT_DRIVER(demo_shape_drv) = { - .name = "demo_shape_drv", - .id = UCLASS_DEMO, - .ops = &shape_ops, - .priv_data_size = sizeof(struct shape_data), - }; - - -This driver has two methods (hello and status) and requires a bit of -private data (accessible through dev_get_priv(dev) once the driver has -been probed). It is a member of UCLASS_DEMO so will register itself -there. - -In U_BOOT_DRIVER it is also possible to specify special methods for bind -and unbind, and these are called at appropriate times. For many drivers -it is hoped that only 'probe' and 'remove' will be needed. - -The U_BOOT_DRIVER macro creates a data structure accessible from C, -so driver model can find the drivers that are available. - -The methods a device can provide are documented in the device.h header. -Briefly, they are: - - * bind - make the driver model aware of a device (bind it to its driver) - * unbind - make the driver model forget the device - * of_to_plat - convert device tree data to plat - see later - * probe - make a device ready for use - * remove - remove a device so it cannot be used until probed again - -The sequence to get a device to work is bind, of_to_plat (if using -device tree) and probe. - - -Platform Data -------------- - -Note: platform data is the old way of doing things. It is -basically a C structure which is passed to drivers to tell them about -platform-specific settings like the address of its registers, bus -speed, etc. Device tree is now the preferred way of handling this. -Unless you have a good reason not to use device tree (the main one -being you need serial support in SPL and don't have enough SRAM for -the cut-down device tree and libfdt libraries) you should stay away -from platform data. - -Platform data is like Linux platform data, if you are familiar with that. -It provides the board-specific information to start up a device. - -Why is this information not just stored in the device driver itself? The -idea is that the device driver is generic, and can in principle operate on -any board that has that type of device. For example, with modern -highly-complex SoCs it is common for the IP to come from an IP vendor, and -therefore (for example) the MMC controller may be the same on chips from -different vendors. It makes no sense to write independent drivers for the -MMC controller on each vendor's SoC, when they are all almost the same. -Similarly, we may have 6 UARTs in an SoC, all of which are mostly the same, -but lie at different addresses in the address space. - -Using the UART example, we have a single driver and it is instantiated 6 -times by supplying 6 lots of platform data. Each lot of platform data -gives the driver name and a pointer to a structure containing information -about this instance - e.g. the address of the register space. It may be that -one of the UARTS supports RS-485 operation - this can be added as a flag in -the platform data, which is set for this one port and clear for the rest. - -Think of your driver as a generic piece of code which knows how to talk to -a device, but needs to know where it is, any variant/option information and -so on. Platform data provides this link between the generic piece of code -and the specific way it is bound on a particular board. - -Examples of platform data include: - - - The base address of the IP block's register space - - Configuration options, like: - - the SPI polarity and maximum speed for a SPI controller - - the I2C speed to use for an I2C device - - the number of GPIOs available in a GPIO device - -Where does the platform data come from? It is either held in a structure -which is compiled into U-Boot, or it can be parsed from the Device Tree -(see 'Device Tree' below). - -For an example of how it can be compiled in, see demo-pdata.c which -sets up a table of driver names and their associated platform data. -The data can be interpreted by the drivers however they like - it is -basically a communication scheme between the board-specific code and -the generic drivers, which are intended to work on any board. - -Drivers can access their data via dev->info->plat. Here is -the declaration for the platform data, which would normally appear -in the board file. - -.. code-block:: c - - static const struct dm_demo_pdata red_square = { - .colour = "red", - .sides = 4. - }; - - static const struct driver_info info[] = { - { - .name = "demo_shape_drv", - .plat = &red_square, - }, - }; - - demo1 = driver_bind(root, &info[0]); - - -Device Tree ------------ - -While plat is useful, a more flexible way of providing device data is -by using device tree. In U-Boot you should use this where possible. Avoid -sending patches which make use of the U_BOOT_DRVINFO() macro unless strictly -necessary. - -With device tree we replace the above code with the following device tree -fragment: - -.. code-block:: c - - red-square { - compatible = "demo-shape"; - colour = "red"; - sides = <4>; - }; - -This means that instead of having lots of U_BOOT_DRVINFO() declarations in -the board file, we put these in the device tree. This approach allows a lot -more generality, since the same board file can support many types of boards -(e,g. with the same SoC) just by using different device trees. An added -benefit is that the Linux device tree can be used, thus further simplifying -the task of board-bring up either for U-Boot or Linux devs (whoever gets to -the board first!). - -The easiest way to make this work it to add a few members to the driver: - -.. code-block:: c - - .plat_auto = sizeof(struct dm_test_pdata), - .of_to_plat = testfdt_of_to_plat, - -The 'auto' feature allowed space for the plat to be allocated -and zeroed before the driver's of_to_plat() method is called. The -of_to_plat() method, which the driver write supplies, should parse -the device tree node for this device and place it in dev->plat. Thus -when the probe method is called later (to set up the device ready for use) -the platform data will be present. - -Note that both methods are optional. If you provide an of_to_plat -method then it will be called first (during activation). If you provide a -probe method it will be called next. See Driver Lifecycle below for more -details. - -If you don't want to have the plat automatically allocated then you -can leave out plat_auto. In this case you can use malloc -in your of_to_plat (or probe) method to allocate the required memory, -and you should free it in the remove method. - -The driver model tree is intended to mirror that of the device tree. The -root driver is at device tree offset 0 (the root node, '/'), and its -children are the children of the root node. - -In order for a device tree to be valid, the content must be correct with -respect to either device tree specification -(https://www.devicetree.org/specifications/) or the device tree bindings that -are found in the doc/device-tree-bindings directory. When not U-Boot specific -the bindings in this directory tend to come from the Linux Kernel. As such -certain design decisions may have been made already for us in terms of how -specific devices are described and bound. In most circumstances we wish to -retain compatibility without additional changes being made to the device tree -source files. - -Declaring Uclasses ------------------- - -The demo uclass is declared like this: - -.. code-block:: c - - UCLASS_DRIVER(demo) = { - .id = UCLASS_DEMO, - }; - -It is also possible to specify special methods for probe, etc. The uclass -numbering comes from include/dm/uclass-id.h. To add a new uclass, add to the -end of the enum there, then declare your uclass as above. - - -Device Sequence Numbers ------------------------ - -U-Boot numbers devices from 0 in many situations, such as in the command -line for I2C and SPI buses, and the device names for serial ports (serial0, -serial1, ...). Driver model supports this numbering and permits devices -to be locating by their 'sequence'. This numbering uniquely identifies a -device in its uclass, so no two devices within a particular uclass can have -the same sequence number. - -Sequence numbers start from 0 but gaps are permitted. For example, a board -may have I2C buses 1, 4, 5 but no 0, 2 or 3. The choice of how devices are -numbered is up to a particular board, and may be set by the SoC in some -cases. While it might be tempting to automatically renumber the devices -where there are gaps in the sequence, this can lead to confusion and is -not the way that U-Boot works. - -Where a device gets its sequence number is controlled by the DM_SEQ_ALIAS -Kconfig option, which can have a different value in U-Boot proper and SPL. -If this option is not set, aliases are ignored. - -Even if CONFIG_DM_SEQ_ALIAS is enabled, the uclass must still have the -DM_UC_FLAG_SEQ_ALIAS flag set, for its devices to be sequenced by aliases. - -With those options set, devices with an alias (e.g. "serial2") will get that -sequence number (e.g. 2). Other devices get the next available number after all -aliases and all existing numbers. This means that if there is just a single -alias "serial2", unaliased serial devices will be assigned 3 or more, with 0 and -1 being unused. - -If CONFIG_DM_SEQ_ALIAS or DM_UC_FLAG_SEQ_ALIAS are not set, all devices will get -sequence numbers in a simple ordering starting from 0. To find the next number -to allocate, driver model scans through to find the maximum existing number, -then uses the next one. It does not attempt to fill in gaps. - -.. code-block:: none - - aliases { - serial2 = "/serial@22230000"; - }; - -This indicates that in the uclass called "serial", the named node -("/serial@22230000") will be given sequence number 2. Any command or driver -which requests serial device 2 will obtain this device. - -More commonly you can use node references, which expand to the full path: - -.. code-block:: none - - aliases { - serial2 = &serial_2; - }; - ... - serial_2: serial@22230000 { - ... - }; - -The alias resolves to the same string in this case, but this version is -easier to read. - -Device sequence numbers are resolved when a device is bound and the number does -not change for the life of the device. - -There are some situations where the uclass must allocate sequence numbers, -since a strictly increase sequence (with devicetree nodes bound first) is not -suitable. An example of this is the PCI bus. In this case, you can set the -uclass DM_UC_FLAG_NO_AUTO_SEQ flag. With this flag set, only devices with an -alias will be assigned a number by driver model. The rest is left to the uclass -to sort out, e.g. when enumerating the bus. - -Note that changing the sequence number for a device (e.g. in a driver) is not -permitted. If it is felt to be necessary, ask on the mailing list. - -Bus Drivers ------------ - -A common use of driver model is to implement a bus, a device which provides -access to other devices. Example of buses include SPI and I2C. Typically -the bus provides some sort of transport or translation that makes it -possible to talk to the devices on the bus. - -Driver model provides some useful features to help with implementing buses. -Firstly, a bus can request that its children store some 'parent data' which -can be used to keep track of child state. Secondly, the bus can define -methods which are called when a child is probed or removed. This is similar -to the methods the uclass driver provides. Thirdly, per-child platform data -can be provided to specify things like the child's address on the bus. This -persists across child probe()/remove() cycles. - -For consistency and ease of implementation, the bus uclass can specify the -per-child platform data, so that it can be the same for all children of buses -in that uclass. There are also uclass methods which can be called when -children are bound and probed. - -Here an explanation of how a bus fits with a uclass may be useful. Consider -a USB bus with several devices attached to it, each from a different (made -up) uclass:: - - xhci_usb (UCLASS_USB) - eth (UCLASS_ETH) - camera (UCLASS_CAMERA) - flash (UCLASS_FLASH_STORAGE) - -Each of the devices is connected to a different address on the USB bus. -The bus device wants to store this address and some other information such -as the bus speed for each device. - -To achieve this, the bus device can use dev->parent_plat in each of its -three children. This can be auto-allocated if the bus driver (or bus uclass) -has a non-zero value for per_child_plat_auto. If not, then -the bus device or uclass can allocate the space itself before the child -device is probed. - -Also the bus driver can define the child_pre_probe() and child_post_remove() -methods to allow it to do some processing before the child is activated or -after it is deactivated. - -Similarly the bus uclass can define the child_post_bind() method to obtain -the per-child platform data from the device tree and set it up for the child. -The bus uclass can also provide a child_pre_probe() method. Very often it is -the bus uclass that controls these features, since it avoids each driver -having to do the same processing. Of course the driver can still tweak and -override these activities. - -Note that the information that controls this behaviour is in the bus's -driver, not the child's. In fact it is possible that child has no knowledge -that it is connected to a bus. The same child device may even be used on two -different bus types. As an example. the 'flash' device shown above may also -be connected on a SATA bus or standalone with no bus:: - - xhci_usb (UCLASS_USB) - flash (UCLASS_FLASH_STORAGE) - parent data/methods defined by USB bus - - sata (UCLASS_AHCI) - flash (UCLASS_FLASH_STORAGE) - parent data/methods defined by SATA bus - - flash (UCLASS_FLASH_STORAGE) - no parent data/methods (not on a bus) - -Above you can see that the driver for xhci_usb/sata controls the child's -bus methods. In the third example the device is not on a bus, and therefore -will not have these methods at all. Consider the case where the flash -device defines child methods. These would be used for *its* children, and -would be quite separate from the methods defined by the driver for the bus -that the flash device is connetced to. The act of attaching a device to a -parent device which is a bus, causes the device to start behaving like a -bus device, regardless of its own views on the matter. - -The uclass for the device can also contain data private to that uclass. -But note that each device on the bus may be a member of a different -uclass, and this data has nothing to do with the child data for each child -on the bus. It is the bus' uclass that controls the child with respect to -the bus. - - -Driver Lifecycle ----------------- - -Here are the stages that a device goes through in driver model. Note that all -methods mentioned here are optional - e.g. if there is no probe() method for -a device then it will not be called. A simple device may have very few -methods actually defined. - -Bind stage -^^^^^^^^^^ - -U-Boot discovers devices using one of these two methods: - -- Scan the U_BOOT_DRVINFO() definitions. U-Boot looks up the name specified - by each, to find the appropriate U_BOOT_DRIVER() definition. In this case, - there is no path by which driver_data may be provided, but the U_BOOT_DRVINFO() - may provide plat. - -- Scan through the device tree definitions. U-Boot looks at top-level - nodes in the the device tree. It looks at the compatible string in each node - and uses the of_match table of the U_BOOT_DRIVER() structure to find the - right driver for each node. In this case, the of_match table may provide a - driver_data value, but plat cannot be provided until later. - -For each device that is discovered, U-Boot then calls device_bind() to create a -new device, initializes various core fields of the device object such as name, -uclass & driver, initializes any optional fields of the device object that are -applicable such as of_offset, driver_data & plat, and finally calls the -driver's bind() method if one is defined. - -At this point all the devices are known, and bound to their drivers. There -is a 'struct udevice' allocated for all devices. However, nothing has been -activated (except for the root device). Each bound device that was created -from a U_BOOT_DRVINFO() declaration will hold the plat pointer specified -in that declaration. For a bound device created from the device tree, -plat will be NULL, but of_offset will be the offset of the device tree -node that caused the device to be created. The uclass is set correctly for -the device. - -The device's sequence number is assigned, either the requested one or the next -available one (after all aliases are processed) if nothing particular is -requested. - -The device's bind() method is permitted to perform simple actions, but -should not scan the device tree node, not initialise hardware, nor set up -structures or allocate memory. All of these tasks should be left for -the probe() method. - -Note that compared to Linux, U-Boot's driver model has a separate step of -probe/remove which is independent of bind/unbind. This is partly because in -U-Boot it may be expensive to probe devices and we don't want to do it until -they are needed, or perhaps until after relocation. - -Reading ofdata -^^^^^^^^^^^^^^ - -Most devices have data in the device tree which they can read to find out the -base address of hardware registers and parameters relating to driver -operation. This is called 'ofdata' (Open-Firmware data). - -The device's of_to_plat() implemnents allocation and reading of -plat. A parent's ofdata is always read before a child. - -The steps are: - - 1. If priv_auto is non-zero, then the device-private space - is allocated for the device and zeroed. It will be accessible as - dev->priv. The driver can put anything it likes in there, but should use - it for run-time information, not platform data (which should be static - and known before the device is probed). - - 2. If plat_auto is non-zero, then the platform data space - is allocated. This is only useful for device tree operation, since - otherwise you would have to specify the platform data in the - U_BOOT_DRVINFO() declaration. The space is allocated for the device and - zeroed. It will be accessible as dev->plat. - - 3. If the device's uclass specifies a non-zero per_device_auto, - then this space is allocated and zeroed also. It is allocated for and - stored in the device, but it is uclass data. owned by the uclass driver. - It is possible for the device to access it. - - 4. If the device's immediate parent specifies a per_child_auto - then this space is allocated. This is intended for use by the parent - device to keep track of things related to the child. For example a USB - flash stick attached to a USB host controller would likely use this - space. The controller can hold information about the USB state of each - of its children. - - 5. If the driver provides an of_to_plat() method, then this is - called to convert the device tree data into platform data. This should - do various calls like dev_read_u32(dev, ...) to access the node and store - the resulting information into dev->plat. After this point, the device - works the same way whether it was bound using a device tree node or - U_BOOT_DRVINFO() structure. In either case, the platform data is now stored - in the plat structure. Typically you will use the - plat_auto feature to specify the size of the platform data - structure, and U-Boot will automatically allocate and zero it for you before - entry to of_to_plat(). But if not, you can allocate it yourself in - of_to_plat(). Note that it is preferable to do all the device tree - decoding in of_to_plat() rather than in probe(). (Apart from the - ugliness of mixing configuration and run-time data, one day it is possible - that U-Boot will cache platform data for devices which are regularly - de/activated). - - 6. The device is marked 'plat valid'. - -Note that ofdata reading is always done (for a child and all its parents) -before probing starts. Thus devices go through two distinct states when -probing: reading platform data and actually touching the hardware to bring -the device up. - -Having probing separate from ofdata-reading helps deal with of-platdata, where -the probe() method is common to both DT/of-platdata operation, but the -of_to_plat() method is implemented differently. - -Another case has come up where this separate is useful. Generation of ACPI -tables uses the of-platdata but does not want to probe the device. Probing -would cause U-Boot to violate one of its design principles, viz that it -should only probe devices that are used. For ACPI we want to generate a -table for each device, even if U-Boot does not use it. In fact it may not -even be possible to probe the device - e.g. an SD card which is not -present will cause an error on probe, yet we still must tell Linux about -the SD card connector in case it is used while Linux is running. - -It is important that the of_to_plat() method does not actually probe -the device itself. However there are cases where other devices must be probed -in the of_to_plat() method. An example is where a device requires a -GPIO for it to operate. To select a GPIO obviously requires that the GPIO -device is probed. This is OK when used by common, core devices such as GPIO, -clock, interrupts, reset and the like. - -If your device relies on its parent setting up a suitable address space, so -that dev_read_addr() works correctly, then make sure that the parent device -has its setup code in of_to_plat(). If it has it in the probe method, -then you cannot call dev_read_addr() from the child device's -of_to_plat() method. Move it to probe() instead. Buses like PCI can -fall afoul of this rule. - -Activation/probe -^^^^^^^^^^^^^^^^ - -When a device needs to be used, U-Boot activates it, by first reading ofdata -as above and then following these steps (see device_probe()): - - 1. All parent devices are probed. It is not possible to activate a device - unless its predecessors (all the way up to the root device) are activated. - This means (for example) that an I2C driver will require that its bus - be activated. - - 2. The device's probe() method is called. This should do anything that - is required by the device to get it going. This could include checking - that the hardware is actually present, setting up clocks for the - hardware and setting up hardware registers to initial values. The code - in probe() can access: - - - platform data in dev->plat (for configuration) - - private data in dev->priv (for run-time state) - - uclass data in dev->uclass_priv (for things the uclass stores - about this device) - - Note: If you don't use priv_auto then you will need to - allocate the priv space here yourself. The same applies also to - plat_auto. Remember to free them in the remove() method. - - 3. The device is marked 'activated' - - 4. The uclass's post_probe() method is called, if one exists. This may - cause the uclass to do some housekeeping to record the device as - activated and 'known' by the uclass. - -Running stage -^^^^^^^^^^^^^ - -The device is now activated and can be used. From now until it is removed -all of the above structures are accessible. The device appears in the -uclass's list of devices (so if the device is in UCLASS_GPIO it will appear -as a device in the GPIO uclass). This is the 'running' state of the device. - -Removal stage -^^^^^^^^^^^^^ - -When the device is no-longer required, you can call device_remove() to -remove it. This performs the probe steps in reverse: - - 1. The uclass's pre_remove() method is called, if one exists. This may - cause the uclass to do some housekeeping to record the device as - deactivated and no-longer 'known' by the uclass. - - 2. All the device's children are removed. It is not permitted to have - an active child device with a non-active parent. This means that - device_remove() is called for all the children recursively at this point. - - 3. The device's remove() method is called. At this stage nothing has been - deallocated so platform data, private data and the uclass data will all - still be present. This is where the hardware can be shut down. It is - intended that the device be completely inactive at this point, For U-Boot - to be sure that no hardware is running, it should be enough to remove - all devices. - - 4. The device memory is freed (platform data, private data, uclass data, - parent data). - - Note: Because the platform data for a U_BOOT_DRVINFO() is defined with a - static pointer, it is not de-allocated during the remove() method. For - a device instantiated using the device tree data, the platform data will - be dynamically allocated, and thus needs to be deallocated during the - remove() method, either: - - - if the plat_auto is non-zero, the deallocation happens automatically - within the driver model core in the unbind stage; or - - - when plat_auto is 0, both the allocation (in probe() - or preferably of_to_plat()) and the deallocation in remove() - are the responsibility of the driver author. - - 5. The device is marked inactive. Note that it is still bound, so the - device structure itself is not freed at this point. Should the device be - activated again, then the cycle starts again at step 2 above. - -Unbind stage -^^^^^^^^^^^^ - -The device is unbound. This is the step that actually destroys the device. -If a parent has children these will be destroyed first. After this point -the device does not exist and its memory has be deallocated. - - -Special cases for removal -------------------------- - -Some devices need to do clean-up before the OS is called. For example, a USB -driver may want to stop the bus. This can be done in the remove() method. -Some special flags are used to determine whether to remove the device: - - DM_FLAG_OS_PREPARE - indicates that the device needs to get ready for OS - boot. The device will be removed just before the OS is booted - DM_REMOVE_ACTIVE_DMA - indicates that the device uses DMA. This is - effectively the same as DM_FLAG_OS_PREPARE, so the device is removed - before the OS is booted - DM_FLAG_VITAL - indicates that the device is 'vital' to the operation of - other devices. It is possible to remove this device after all regular - devices are removed. This is useful e.g. for a clock, which need to - be active during the device-removal phase. - -The dm_remove_devices_flags() function can be used to remove devices based on -their driver flags. - -Data Structures ---------------- - -Driver model uses a doubly-linked list as the basic data structure. Some -nodes have several lists running through them. Creating a more efficient -data structure might be worthwhile in some rare cases, once we understand -what the bottlenecks are. - - -Changes since v1 ----------------- - -For the record, this implementation uses a very similar approach to the -original patches, but makes at least the following changes: - -- Tried to aggressively remove boilerplate, so that for most drivers there - is little or no 'driver model' code to write. -- Moved some data from code into data structure - e.g. store a pointer to - the driver operations structure in the driver, rather than passing it - to the driver bind function. -- Rename some structures to make them more similar to Linux (struct udevice - instead of struct instance, struct plat, etc.) -- Change the name 'core' to 'uclass', meaning U-Boot class. It seems that - this concept relates to a class of drivers (or a subsystem). We shouldn't - use 'class' since it is a C++ reserved word, so U-Boot class (uclass) seems - better than 'core'. -- Remove 'struct driver_instance' and just use a single 'struct udevice'. - This removes a level of indirection that doesn't seem necessary. -- Built in device tree support, to avoid the need for plat -- Removed the concept of driver relocation, and just make it possible for - the new driver (created after relocation) to access the old driver data. - I feel that relocation is a very special case and will only apply to a few - drivers, many of which can/will just re-init anyway. So the overhead of - dealing with this might not be worth it. -- Implemented a GPIO system, trying to keep it simple - - -Pre-Relocation Support ----------------------- - -For pre-relocation we simply call the driver model init function. Only -drivers marked with DM_FLAG_PRE_RELOC or the device tree 'u-boot,dm-pre-reloc' -property are initialised prior to relocation. This helps to reduce the driver -model overhead. This flag applies to SPL and TPL as well, if device tree is -enabled (CONFIG_OF_CONTROL) there. - -Note when device tree is enabled, the device tree 'u-boot,dm-pre-reloc' -property can provide better control granularity on which device is bound -before relocation. While with DM_FLAG_PRE_RELOC flag of the driver all -devices with the same driver are bound, which requires allocation a large -amount of memory. When device tree is not used, DM_FLAG_PRE_RELOC is the -only way for statically declared devices via U_BOOT_DRVINFO() to be bound -prior to relocation. - -It is possible to limit this to specific relocation steps, by using -the more specialized 'u-boot,dm-spl' and 'u-boot,dm-tpl' flags -in the device tree node. For U-Boot proper you can use 'u-boot,dm-pre-proper' -which means that it will be processed (and a driver bound) in U-Boot proper -prior to relocation, but will not be available in SPL or TPL. - -To reduce the size of SPL and TPL, only the nodes with pre-relocation properties -('u-boot,dm-pre-reloc', 'u-boot,dm-spl' or 'u-boot,dm-tpl') are keept in their -device trees (see README.SPL for details); the remaining nodes are always bound. - -Then post relocation we throw that away and re-init driver model again. -For drivers which require some sort of continuity between pre- and -post-relocation devices, we can provide access to the pre-relocation -device pointers, but this is not currently implemented (the root device -pointer is saved but not made available through the driver model API). - - -SPL Support ------------ - -Driver model can operate in SPL. Its efficient implementation and small code -size provide for a small overhead which is acceptable for all but the most -constrained systems. - -To enable driver model in SPL, define CONFIG_SPL_DM. You might want to -consider the following option also. See the main README for more details. - - - CONFIG_SYS_MALLOC_SIMPLE - - CONFIG_DM_WARN - - CONFIG_DM_DEVICE_REMOVE - - CONFIG_DM_STDIO - - -Enabling Driver Model ---------------------- - -Driver model is being brought into U-Boot gradually. As each subsystems gets -support, a uclass is created and a CONFIG to enable use of driver model for -that subsystem. - -For example CONFIG_DM_SERIAL enables driver model for serial. With that -defined, the old serial support is not enabled, and your serial driver must -conform to driver model. With that undefined, the old serial support is -enabled and driver model is not available for serial. This means that when -you convert a driver, you must either convert all its boards, or provide for -the driver to be compiled both with and without driver model (generally this -is not very hard). - -See the main README for full details of the available driver model CONFIG -options. - - -Things to punt for later ------------------------- - -Uclasses are statically numbered at compile time. It would be possible to -change this to dynamic numbering, but then we would require some sort of -lookup service, perhaps searching by name. This is slightly less efficient -so has been left out for now. One small advantage of dynamic numbering might -be fewer merge conflicts in uclass-id.h. diff --git a/doc/driver-model/ethernet.rst b/doc/driver-model/ethernet.rst deleted file mode 100644 index cdbccca..0000000 --- a/doc/driver-model/ethernet.rst +++ /dev/null @@ -1,321 +0,0 @@ -Ethernet Driver Guide -======================= - -The networking stack in Das U-Boot is designed for multiple network devices -to be easily added and controlled at runtime. This guide is meant for people -who wish to review the net driver stack with an eye towards implementing your -own ethernet device driver. Here we will describe a new pseudo 'APE' driver. - -Most existing drivers do already - and new network driver MUST - use the -U-Boot core driver model. Generic information about this can be found in -doc/driver-model/design.rst, this document will thus focus on the network -specific code parts. -Some drivers are still using the old Ethernet interface, differences between -the two and hints about porting will be handled at the end. - -Driver framework ------------------- - -A network driver following the driver model must declare itself using -the UCLASS_ETH .id field in the U-Boot driver struct: - -.. code-block:: c - - U_BOOT_DRIVER(eth_ape) = { - .name = "eth_ape", - .id = UCLASS_ETH, - .of_match = eth_ape_ids, - .of_to_plat = eth_ape_of_to_plat, - .probe = eth_ape_probe, - .ops = ð_ape_ops, - .priv_auto = sizeof(struct eth_ape_priv), - .plat_auto = sizeof(struct eth_ape_pdata), - .flags = DM_FLAG_ALLOC_PRIV_DMA, - }; - -struct eth_ape_priv contains runtime per-instance data, like buffers, pointers -to current descriptors, current speed settings, pointers to PHY related data -(like struct mii_dev) and so on. Declaring its size in .priv_auto -will let the driver framework allocate it at the right time. -It can be retrieved using a dev_get_priv(dev) call. - -struct eth_ape_pdata contains static platform data, like the MMIO base address, -a hardware variant, the MAC address. ``struct eth_pdata eth_pdata`` -as the first member of this struct helps to avoid duplicated code. -If you don't need any more platform data beside the standard member, -just use sizeof(struct eth_pdata) for the plat_auto. - -PCI devices add a line pointing to supported vendor/device ID pairs: - -.. code-block:: c - - static struct pci_device_id supported[] = { - { PCI_DEVICE(PCI_VENDOR_ID_APE, 0x4223) }, - {} - }; - - U_BOOT_PCI_DEVICE(eth_ape, supported); - -It is also possible to declare support for a whole class of PCI devices:: - - { PCI_DEVICE_CLASS(PCI_CLASS_SYSTEM_SDHCI << 8, 0xffff00) }, - -Device probing and instantiation will be handled by the driver model framework, -so follow the guidelines there. The probe() function would initialise the -platform specific parts of the hardware, like clocks, resets, GPIOs, the MDIO -bus. Also it would take care of any special PHY setup (power rails, enable -bits for internal PHYs, etc.). - -Driver methods ----------------- - -The real work will be done in the driver method functions the driver provides -by defining the members of struct eth_ops: - -.. code-block:: c - - struct eth_ops { - int (*start)(struct udevice *dev); - int (*send)(struct udevice *dev, void *packet, int length); - int (*recv)(struct udevice *dev, int flags, uchar **packetp); - int (*free_pkt)(struct udevice *dev, uchar *packet, int length); - void (*stop)(struct udevice *dev); - int (*mcast)(struct udevice *dev, const u8 *enetaddr, int join); - int (*write_hwaddr)(struct udevice *dev); - int (*read_rom_hwaddr)(struct udevice *dev); - }; - -An up-to-date version of this struct together with more information can be -found in include/net.h. - -Only start, stop, send and recv are required, the rest are optional and are -handled by generic code or ignored if not provided. - -The **start** function initialises the hardware and gets it ready for send/recv -operations. You often do things here such as resetting the MAC -and/or PHY, and waiting for the link to autonegotiate. You should also take -the opportunity to program the device's MAC address with the enetaddr member -of the generic struct eth_pdata (which would be the first member of your -own plat struct). This allows the rest of U-Boot to dynamically change -the MAC address and have the new settings be respected. - -The **send** function does what you think -- transmit the specified packet -whose size is specified by length (in bytes). The packet buffer can (and -will!) be reused for subsequent calls to send(), so it must be no longer -used when the send() function returns. The easiest way to achieve this is -to wait until the transmission is complete. Alternatively, if supported by -the hardware, just waiting for the buffer to be consumed (by some DMA engine) -might be an option as well. -Another way of consuming the buffer could be to copy the data to be send, -then just queue the copied packet (for instance handing it over to a DMA -engine), and return immediately afterwards. -In any case you should leave the state such that the send function can be -called multiple times in a row. - -The **recv** function polls for availability of a new packet. If none is -available, it must return with -EAGAIN. -If a packet has been received, make sure it is accessible to the CPU -(invalidate caches if needed), then write its address to the packetp pointer, -and return the length. If there is an error (receive error, too short or too -long packet), return 0 if you require the packet to be cleaned up normally, -or a negative error code otherwise (cleanup not necessary or already done). -The U-Boot network stack will then process the packet. - -If **free_pkt** is defined, U-Boot will call it after a received packet has -been processed, so the packet buffer can be freed or recycled. Typically you -would hand it back to the hardware to acquire another packet. free_pkt() will -be called after recv(), for the same packet, so you don't necessarily need -to infer the buffer to free from the ``packet`` pointer, but can rely on that -being the last packet that recv() handled. -The common code sets up packet buffers for you already in the .bss -(net_rx_packets), so there should be no need to allocate your own. This doesn't -mean you must use the net_rx_packets array however; you're free to use any -buffer you wish. - -The **stop** function should turn off / disable the hardware and place it back -in its reset state. It can be called at any time (before any call to the -related start() function), so make sure it can handle this sort of thing. - -The (optional) **write_hwaddr** function should program the MAC address stored -in pdata->enetaddr into the Ethernet controller. - -So the call graph at this stage would look something like: - -.. code-block:: c - - (some net operation (ping / tftp / whatever...)) - eth_init() - ops->start() - eth_send() - ops->send() - eth_rx() - ops->recv() - (process packet) - if (ops->free_pkt) - ops->free_pkt() - eth_halt() - ops->stop() - - -CONFIG_PHYLIB / CONFIG_CMD_MII --------------------------------- - -If your device supports banging arbitrary values on the MII bus (pretty much -every device does), you should add support for the mii command. Doing so is -fairly trivial and makes debugging mii issues a lot easier at runtime. - -In your driver's ``probe()`` function, add a call to mdio_alloc() and -mdio_register() like so: - -.. code-block:: c - - bus = mdio_alloc(); - if (!bus) { - ... - return -ENOMEM; - } - - bus->read = ape_mii_read; - bus->write = ape_mii_write; - mdio_register(bus); - -And then define the mii_read and mii_write functions if you haven't already. -Their syntax is straightforward:: - - int mii_read(struct mii_dev *bus, int addr, int devad, int reg); - int mii_write(struct mii_dev *bus, int addr, int devad, int reg, - u16 val); - -The read function should read the register 'reg' from the phy at address 'addr' -and return the result to its caller. The implementation for the write function -should logically follow. - -................................................................ - -Legacy network drivers ------------------------- - -!!! WARNING !!! - -This section below describes the old way of doing things. No new Ethernet -drivers should be implemented this way. All new drivers should be written -against the U-Boot core driver model, as described above. - -The actual callback functions are fairly similar, the differences are: - -- ``start()`` is called ``init()`` -- ``stop()`` is called ``halt()`` -- The ``recv()`` function must loop until all packets have been received, for - each packet it must call the net_process_received_packet() function, - handing it over the pointer and the length. Afterwards it should free - the packet, before checking for new data. - -For porting an old driver to the new driver model, split the existing recv() -function into the actual new recv() function, just fetching **one** packet, -remove the call to net_process_received_packet(), then move the packet -cleanup into the ``free_pkt()`` function. - -Registering the driver and probing a device is handled very differently, -follow the recommendations in the driver model design documentation for -instructions on how to port this over. For the records, the old way of -initialising a network driver is as follows: - -Old network driver registration -~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ - -When U-Boot initializes, it will call the common function eth_initialize(). -This will in turn call the board-specific board_eth_init() (or if that fails, -the cpu-specific cpu_eth_init()). These board-specific functions can do random -system handling, but ultimately they will call the driver-specific register -function which in turn takes care of initializing that particular instance. - -Keep in mind that you should code the driver to avoid storing state in global -data as someone might want to hook up two of the same devices to one board. -Any such information that is specific to an interface should be stored in a -private, driver-defined data structure and pointed to by eth->priv (see below). - -So the call graph at this stage would look something like: - -.. code-block:: c - - board_init() - eth_initialize() - board_eth_init() / cpu_eth_init() - driver_register() - initialize eth_device - eth_register() - -At this point in time, the only thing you need to worry about is the driver's -register function. The pseudo code would look something like: - -.. code-block:: c - - int ape_register(struct bd_info *bis, int iobase) - { - struct ape_priv *priv; - struct eth_device *dev; - struct mii_dev *bus; - - priv = malloc(sizeof(*priv)); - if (priv == NULL) - return -ENOMEM; - - dev = malloc(sizeof(*dev)); - if (dev == NULL) { - free(priv); - return -ENOMEM; - } - - /* setup whatever private state you need */ - - memset(dev, 0, sizeof(*dev)); - sprintf(dev->name, "APE"); - - /* - * if your device has dedicated hardware storage for the - * MAC, read it and initialize dev->enetaddr with it - */ - ape_mac_read(dev->enetaddr); - - dev->iobase = iobase; - dev->priv = priv; - dev->init = ape_init; - dev->halt = ape_halt; - dev->send = ape_send; - dev->recv = ape_recv; - dev->write_hwaddr = ape_write_hwaddr; - - eth_register(dev); - - #ifdef CONFIG_PHYLIB - bus = mdio_alloc(); - if (!bus) { - free(priv); - free(dev); - return -ENOMEM; - } - - bus->read = ape_mii_read; - bus->write = ape_mii_write; - mdio_register(bus); - #endif - - return 1; - } - -The exact arguments needed to initialize your device are up to you. If you -need to pass more/less arguments, that's fine. You should also add the -prototype for your new register function to include/netdev.h. - -The return value for this function should be as follows: -< 0 - failure (hardware failure, not probe failure) ->=0 - number of interfaces detected - -You might notice that many drivers seem to use xxx_initialize() rather than -xxx_register(). This is the old naming convention and should be avoided as it -causes confusion with the driver-specific init function. - -Other than locating the MAC address in dedicated hardware storage, you should -not touch the hardware in anyway. That step is handled in the driver-specific -init function. Remember that we are only registering the device here, we are -not checking its state or doing random probing. diff --git a/doc/driver-model/fdt-fixup.rst b/doc/driver-model/fdt-fixup.rst deleted file mode 100644 index 974c090..0000000 --- a/doc/driver-model/fdt-fixup.rst +++ /dev/null @@ -1,132 +0,0 @@ -.. SPDX-License-Identifier: GPL-2.0+ -.. 2017-01-06, Mario Six <mario.six@gdsys.cc> - -Pre-relocation device tree manipulation -======================================= - -Purpose -------- - -In certain markets, it is beneficial for manufacturers of embedded devices to -offer certain ranges of products, where the functionality of the devices within -one series either don't differ greatly from another, or can be thought of as -"extensions" of each other, where one device only differs from another in the -addition of a small number of features (e.g. an additional output connector). - -To realize this in hardware, one method is to have a motherboard, and several -possible daughter boards that can be attached to this mother board. Different -daughter boards then either offer the slightly different functionality, or the -addition of the daughter board to the device realizes the "extension" of -functionality to the device described previously. - -For the software, we obviously want to reuse components for all these -variations of the device. This means that the software somehow needs to cope -with the situation that certain ICs may or may not be present on any given -system, depending on which daughter boards are connected to the motherboard. - -In the Linux kernel, one possible solution to this problem is to employ the -device tree overlay mechanism: There exists one "base" device tree, which -features only the components guaranteed to exist in all varieties of the -device. At the start of the kernel, the presence and type of the daughter -boards is then detected, and the corresponding device tree overlays are applied -to support the components on the daughter boards. - -Note that the components present on every variety of the board must, of course, -provide a way to find out if and which daughter boards are installed for this -mechanism to work. - -In the U-Boot boot loader, support for device tree overlays has recently been -integrated, and is used on some boards to alter the device tree that is later -passed to Linux. But since U-Boot's driver model, which is device tree-based as -well, is being used in more and more drivers, the same problem of altering the -device tree starts cropping up in U-Boot itself as well. - -An additional problem with the device tree in U-Boot is that it is read-only, -and the current mechanisms don't allow easy manipulation of the device tree -after the driver model has been initialized. While migrating to a live device -tree (at least after the relocation) would greatly simplify the solution of -this problem, it is a non-negligible task to implement it, an a interim -solution is needed to address the problem at least in the medium-term. - -Hence, we propose a solution to this problem by offering a board-specific -call-back function, which is passed a writeable pointer to the device tree. -This function is called before the device tree is relocated, and specifically -before the main U-Boot's driver model is instantiated, hence the main U-Boot -"sees" all modifications to the device tree made in this function. Furthermore, -we have the pre-relocation driver model at our disposal at this stage, which -means that we can query the hardware for the existence and variety of the -components easily. - -Implementation --------------- - -To take advantage of the pre-relocation device tree manipulation mechanism, -boards have to implement the function board_fix_fdt, which has the following -signature: - -.. code-block:: c - - int board_fix_fdt (void *rw_fdt_blob) - -The passed-in void pointer is a writeable pointer to the device tree, which can -be used to manipulate the device tree using e.g. functions from -include/fdt_support.h. The return value should either be 0 in case of -successful execution of the device tree manipulation or something else for a -failure. Note that returning a non-null value from the function will -unrecoverably halt the boot process, as with any function from init_sequence_f -(in common/board_f.c). - -Furthermore, the Kconfig option OF_BOARD_FIXUP has to be set for the function -to be called:: - - Device Tree Control - -> [*] Board-specific manipulation of Device Tree - -+----------------------------------------------------------+ -| WARNING: The actual manipulation of the device tree has | -| to be the _last_ set of operations in board_fix_fdt! | -| Since the pre-relocation driver model does not adapt to | -| changes made to the device tree either, its references | -| into the device tree will be invalid after manipulating | -| it, and unpredictable behavior might occur when | -| functions that rely on them are executed! | -+----------------------------------------------------------+ - -Hence, the recommended layout of the board_fixup_fdt call-back function is the -following: - -.. code-block:: c - - int board_fix_fdt(void *rw_fdt_blob) - { - /* - * Collect information about device's hardware and store - * them in e.g. local variables - */ - - /* Do device tree manipulation using the values previously collected */ - - /* Return 0 on successful manipulation and non-zero otherwise */ - } - -If this convention is kept, both an "additive" approach, meaning that nodes for -detected components are added to the device tree, as well as a "subtractive" -approach, meaning that nodes for absent components are removed from the tree, -as well as a combination of both approaches should work. - -Example -------- - -The controlcenterdc board (board/gdsys/a38x/controlcenterdc.c) features a -board_fix_fdt function, in which six GPIO expanders (which might be present or -not, since they are on daughter boards) on a I2C bus are queried for, and -subsequently deactivated in the device tree if they are not present. - -Note that the dm_i2c_simple_probe function does not use the device tree, hence -it is safe to call it after the tree has already been manipulated. - -Work to be done ---------------- - -* The application of device tree overlay should be possible in board_fixup_fdt, - but has not been tested at this stage. diff --git a/doc/driver-model/fs_firmware_loader.rst b/doc/driver-model/fs_firmware_loader.rst deleted file mode 100644 index a44708c..0000000 --- a/doc/driver-model/fs_firmware_loader.rst +++ /dev/null @@ -1,154 +0,0 @@ -.. SPDX-License-Identifier: GPL-2.0+ -.. Copyright (C) 2018-2019 Intel Corporation <www.intel.com> - -File System Firmware Loader -=========================== - -This is file system firmware loader for U-Boot framework, which has very close -to some Linux Firmware API. For the details of Linux Firmware API, you can refer -to https://01.org/linuxgraphics/gfx-docs/drm/driver-api/firmware/index.html. - -File system firmware loader can be used to load whatever(firmware, image, -and binary) from the storage device in file system format into target location -such as memory, then consumer driver such as FPGA driver can program FPGA image -from the target location into FPGA. - -To enable firmware loader, CONFIG_FS_LOADER need to be set at -<board_name>_defconfig such as "CONFIG_FS_LOADER=y". - -Firmware Loader API core features ---------------------------------- - -Firmware storage device described in device tree source -------------------------------------------------------- -For passing data like storage device phandle and partition where the -firmware loading from to the firmware loader driver, those data could be -defined in fs-loader node as shown in below: - -Example for block device:: - - fs_loader0: fs-loader { - u-boot,dm-pre-reloc; - compatible = "u-boot,fs-loader"; - phandlepart = <&mmc 1>; - }; - -<&mmc 1> means block storage device pointer and its partition. - -Above example is a description for block storage, but for UBI storage -device, it can be described in FDT as shown in below: - -Example for ubi:: - - fs_loader1: fs-loader { - u-boot,dm-pre-reloc; - compatible = "u-boot,fs-loader"; - mtdpart = "UBI", - ubivol = "ubi0"; - }; - -Then, firmware-loader property can be added with any device node, which -driver would use the firmware loader for loading. - -The value of the firmware-loader property should be set with phandle -of the fs-loader node. For example:: - - firmware-loader = <&fs_loader0>; - -If there are majority of devices using the same fs-loader node, then -firmware-loader property can be added under /chosen node instead of -adding to each of device node. - -For example:: - - /{ - chosen { - firmware-loader = <&fs_loader0>; - }; - }; - -In each respective driver of devices using firmware loader, the firmware -loaded instance should be created by DT phandle. - -For example of getting DT phandle from /chosen and creating instance: - -.. code-block:: c - - chosen_node = ofnode_path("/chosen"); - if (!ofnode_valid(chosen_node)) { - debug("/chosen node was not found.\n"); - return -ENOENT; - } - - phandle_p = ofnode_get_property(chosen_node, "firmware-loader", &size); - if (!phandle_p) { - debug("firmware-loader property was not found.\n"); - return -ENOENT; - } - - phandle = fdt32_to_cpu(*phandle_p); - ret = uclass_get_device_by_phandle_id(UCLASS_FS_FIRMWARE_LOADER, - phandle, &dev); - if (ret) - return ret; - -Firmware loader driver is also designed to support U-boot environment -variables, so all these data from FDT can be overwritten -through the U-boot environment variable during run time. - -For examples: - -storage_interface: - Storage interface, it can be "mmc", "usb", "sata" or "ubi". -fw_dev_part: - Block device number and its partition, it can be "0:1". -fw_ubi_mtdpart: - UBI device mtd partition, it can be "UBI". -fw_ubi_volume: - UBI volume, it can be "ubi0". - -When above environment variables are set, environment values would be -used instead of data from FDT. -The benefit of this design allows user to change storage attribute data -at run time through U-boot console and saving the setting as default -environment values in the storage for the next power cycle, so no -compilation is required for both driver and FDT. - -File system firmware Loader API -------------------------------- - -.. code-block:: c - - int request_firmware_into_buf(struct udevice *dev, - const char *name, - void *buf, size_t size, u32 offset) - -Load firmware into a previously allocated buffer - -Parameters: - -* struct udevice \*dev: An instance of a driver -* const char \*name: name of firmware file -* void \*buf: address of buffer to load firmware into -* size_t size: size of buffer -* u32 offset: offset of a file for start reading into buffer - -Returns: - size of total read - -ve when error - -Description: - The firmware is loaded directly into the buffer pointed to by buf - -Example of calling request_firmware_into_buf API after creating firmware loader -instance: - -.. code-block:: c - - ret = uclass_get_device_by_phandle_id(UCLASS_FS_FIRMWARE_LOADER, - phandle, &dev); - if (ret) - return ret; - - request_firmware_into_buf(dev, filename, buffer_location, buffer_size, - offset_ofreading); diff --git a/doc/driver-model/i2c-howto.rst b/doc/driver-model/i2c-howto.rst deleted file mode 100644 index 27e7440..0000000 --- a/doc/driver-model/i2c-howto.rst +++ /dev/null @@ -1,56 +0,0 @@ -.. SPDX-License-Identifier: GPL-2.0+ - -How to port an I2C driver to driver model -========================================= - -Over half of the I2C drivers have been converted as at November 2016. These -ones remain: - - * adi_i2c - * davinci_i2c - * fti2c010 - * ihs_i2c - * kona_i2c - * lpc32xx_i2c - * pca9564_i2c - * ppc4xx_i2c - * rcar_i2c - * sh_i2c - * soft_i2c - * zynq_i2c - -The deadline for this work is the end of June 2017. If no one steps -forward to convert these, at some point there may come a patch to remove them! - -Here is a suggested approach for converting your I2C driver over to driver -model. Please feel free to update this file with your ideas and suggestions. - -- #ifdef out all your own I2C driver code (#if !CONFIG_IS_ENABLED(DM_I2C)) -- Define CONFIG_DM_I2C for your board, vendor or architecture -- If the board does not already use driver model, you need CONFIG_DM also -- Your board should then build, but will not work fully since there will be - no I2C driver -- Add the U_BOOT_DRIVER piece at the end (e.g. copy tegra_i2c.c for example) -- Add a private struct for the driver data - avoid using static variables -- Implement each of the driver methods, perhaps by calling your old methods -- You may need to adjust the function parameters so that the old and new - implementations can share most of the existing code -- If you convert all existing users of the driver, remove the pre-driver-model - code - -In terms of patches a conversion series typically has these patches: -- clean up / prepare the driver for conversion -- add driver model code -- convert at least one existing board to use driver model serial -- (if no boards remain that don't use driver model) remove the old code - -This may be a good time to move your board to use device tree also. Mostly -this involves these steps: - -- define CONFIG_OF_CONTROL and CONFIG_OF_SEPARATE -- add your device tree files to arch/<arch>/dts -- update the Makefile there -- Add stdout-path to your /chosen device tree node if it is not already there -- build and get u-boot-dtb.bin so you can test it -- Your drivers can now use device tree -- For device tree in SPL, define CONFIG_SPL_OF_CONTROL diff --git a/doc/driver-model/index.rst b/doc/driver-model/index.rst deleted file mode 100644 index c9faf0a..0000000 --- a/doc/driver-model/index.rst +++ /dev/null @@ -1,25 +0,0 @@ -.. SPDX-License-Identifier: GPL-2.0+ - -Driver Model -============ - -.. toctree:: - :maxdepth: 2 - - bind - debugging - design - ethernet - fdt-fixup - fs_firmware_loader - i2c-howto - livetree - migration - of-plat - pci-info - pmic-framework - remoteproc-framework - serial-howto - soc-framework - spi-howto - usb-info diff --git a/doc/driver-model/livetree.rst b/doc/driver-model/livetree.rst deleted file mode 100644 index 9f654f3..0000000 --- a/doc/driver-model/livetree.rst +++ /dev/null @@ -1,286 +0,0 @@ -.. SPDX-License-Identifier: GPL-2.0+ -.. sectionauthor:: Simon Glass <sjg@chromium.org> - -Live Device Tree -================ - - -Introduction ------------- - -Traditionally U-Boot has used a 'flat' device tree. This means that it -reads directly from the device tree binary structure. It is called a flat -device tree because nodes are listed one after the other, with the -hierarchy detected by tags in the format. - -This document describes U-Boot's support for a 'live' device tree, meaning -that the tree is loaded into a hierarchical data structure within U-Boot. - - -Motivation ----------- - -The flat device tree has several advantages: - -- it is the format produced by the device tree compiler, so no translation - is needed - -- it is fairly compact (e.g. there is no need for pointers) - -- it is accessed by the libfdt library, which is well tested and stable - - -However the flat device tree does have some limitations. Adding new -properties can involve copying large amounts of data around to make room. -The overall tree has a fixed maximum size so sometimes the tree must be -rebuilt in a new location to create more space. Even if not adding new -properties or nodes, scanning the tree can be slow. For example, finding -the parent of a node is a slow process. Reading from nodes involves a -small amount parsing which takes a little time. - -Driver model scans the entire device tree sequentially on start-up which -avoids the worst of the flat tree's limitations. But if the tree is to be -modified at run-time, a live tree is much faster. Even if no modification -is necessary, parsing the tree once and using a live tree from then on -seems to save a little time. - - -Implementation --------------- - -In U-Boot a live device tree ('livetree') is currently supported only -after relocation. Therefore we need a mechanism to specify a device -tree node regardless of whether it is in the flat tree or livetree. - -The 'ofnode' type provides this. An ofnode can point to either a flat tree -node (when the live tree node is not yet set up) or a livetree node. The -caller of an ofnode function does not need to worry about these details. - -The main users of the information in a device tree are drivers. These have -a 'struct udevice \*' which is attached to a device tree node. Therefore it -makes sense to be able to read device tree properties using the -'struct udevice \*', rather than having to obtain the ofnode first. - -The 'dev_read\_...()' interface provides this. It allows properties to be -easily read from the device tree using only a device pointer. Under the -hood it uses ofnode so it works with both flat and live device trees. - - -Enabling livetree ------------------ - -CONFIG_OF_LIVE enables livetree. When this option is enabled, the flat -tree will be used in SPL and before relocation in U-Boot proper. Just -before relocation a livetree is built, and this is used for U-Boot proper -after relocation. - -Most checks for livetree use CONFIG_IS_ENABLED(OF_LIVE). This means that -for SPL, the CONFIG_SPL_OF_LIVE option is checked. At present this does -not exist, since SPL does not support livetree. - - -Porting drivers ---------------- - -Many existing drivers use the fdtdec interface to read device tree -properties. This only works with a flat device tree. The drivers should be -converted to use the dev_read_() interface. - -For example, the old code may be like this: - -.. code-block:: c - - struct udevice *bus; - const void *blob = gd->fdt_blob; - int node = dev_of_offset(bus); - - i2c_bus->regs = (struct i2c_ctlr *)devfdt_get_addr(dev); - plat->frequency = fdtdec_get_int(blob, node, "spi-max-frequency", 500000); - -The new code is: - -.. code-block:: c - - struct udevice *bus; - - i2c_bus->regs = (struct i2c_ctlr *)dev_read_addr(dev); - plat->frequency = dev_read_u32_default(bus, "spi-max-frequency", 500000); - -The dev_read\_...() interface is more convenient and works with both the -flat and live device trees. See include/dm/read.h for a list of functions. - -Where properties must be read from sub-nodes or other nodes, you must fall -back to using ofnode. For example, for old code like this: - -.. code-block:: c - - const void *blob = gd->fdt_blob; - int subnode; - - fdt_for_each_subnode(subnode, blob, dev_of_offset(dev)) { - freq = fdtdec_get_int(blob, node, "spi-max-frequency", 500000); - ... - } - -you should use: - -.. code-block:: c - - ofnode subnode; - - ofnode_for_each_subnode(subnode, dev_ofnode(dev)) { - freq = ofnode_read_u32(node, "spi-max-frequency", 500000); - ... - } - - -Useful ofnode functions ------------------------ - -The internal data structures of the livetree are defined in include/dm/of.h : - - :struct device_node: holds information about a device tree node - :struct property: holds information about a property within a node - -Nodes have pointers to their first property, their parent, their first child -and their sibling. This allows nodes to be linked together in a hierarchical -tree. - -Properties have pointers to the next property. This allows all properties of -a node to be linked together in a chain. - -It should not be necessary to use these data structures in normal code. In -particular, you should refrain from using functions which access the livetree -directly, such as of_read_u32(). Use ofnode functions instead, to allow your -code to work with a flat tree also. - -Some conversion functions are used internally. Generally these are not needed -for driver code. Note that they will not work if called in the wrong context. -For example it is invalid to call ofnode_to_no() when a flat tree is being -used. Similarly it is not possible to call ofnode_to_offset() on a livetree -node. - -ofnode_to_np(): - converts ofnode to struct device_node * -ofnode_to_offset(): - converts ofnode to offset - -no_to_ofnode(): - converts node pointer to ofnode -offset_to_ofnode(): - converts offset to ofnode - - -Other useful functions: - -of_live_active(): - returns true if livetree is in use, false if flat tree -ofnode_valid(): - return true if a given node is valid -ofnode_is_np(): - returns true if a given node is a livetree node -ofnode_equal(): - compares two ofnodes -ofnode_null(): - returns a null ofnode (for which ofnode_valid() returns false) - - -Phandles --------- - -There is full phandle support for live tree. All functions make use of -struct ofnode_phandle_args, which has an ofnode within it. This supports both -livetree and flat tree transparently. See for example -ofnode_parse_phandle_with_args(). - - -Reading addresses ------------------ - -You should use dev_read_addr() and friends to read addresses from device-tree -nodes. - - -fdtdec ------- - -The existing fdtdec interface will eventually be retired. Please try to avoid -using it in new code. - - -Modifying the livetree ----------------------- - -This is not currently supported. Once implemented it should provide a much -more efficient implementation for modification of the device tree than using -the flat tree. - - -Internal implementation ------------------------ - -The dev_read\_...() functions have two implementations. When -CONFIG_DM_DEV_READ_INLINE is enabled, these functions simply call the ofnode -functions directly. This is useful when livetree is not enabled. The ofnode -functions call ofnode_is_np(node) which will always return false if livetree -is disabled, just falling back to flat tree code. - -This optimisation means that without livetree enabled, the dev_read\_...() and -ofnode interfaces do not noticeably add to code size. - -The CONFIG_DM_DEV_READ_INLINE option defaults to enabled when livetree is -disabled. - -Most livetree code comes directly from Linux and is modified as little as -possible. This is deliberate since this code is fairly stable and does what -we want. Some features (such as get/put) are not supported. Internal macros -take care of removing these features silently. - -Within the of_access.c file there are pointers to the alias node, the chosen -node and the stdout-path alias. - - -Errors ------- - -With a flat device tree, libfdt errors are returned (e.g. -FDT_ERR_NOTFOUND). -For livetree normal 'errno' errors are returned (e.g. -ENOTFOUND). At present -the ofnode and dev_read\_...() functions return either one or other type of -error. This is clearly not desirable. Once tests are added for all the -functions this can be tidied up. - - -Adding new access functions ---------------------------- - -Adding a new function for device-tree access involves the following steps: - - - Add two dev_read() functions: - - inline version in the read.h header file, which calls an ofnode function - - standard version in the read.c file (or perhaps another file), which - also calls an ofnode function - - The implementations of these functions can be the same. The purpose - of the inline version is purely to reduce code size impact. - - - Add an ofnode function. This should call ofnode_is_np() to work out - whether a livetree or flat tree is used. For the livetree it should - call an of\_...() function. For the flat tree it should call an - fdt\_...() function. The livetree version will be optimised out at - compile time if livetree is not enabled. - - - Add an of\_...() function for the livetree implementation. If a similar - function is available in Linux, the implementation should be taken - from there and modified as little as possible (generally not at all). - - -Future work ------------ - -Live tree support was introduced in U-Boot 2017.07. There is still quite a bit -of work to do to flesh this out: - -- tests for all access functions -- support for livetree modification -- addition of more access functions as needed -- support for livetree in SPL and before relocation (if desired) diff --git a/doc/driver-model/migration.rst b/doc/driver-model/migration.rst deleted file mode 100644 index 2284e8a..0000000 --- a/doc/driver-model/migration.rst +++ /dev/null @@ -1,101 +0,0 @@ -.. SPDX-License-Identifier: GPL-2.0+ - -Migration Schedule -================== - -U-Boot has been migrating to a new driver model since its introduction in -2014. This file describes the schedule for deprecation of pre-driver-model -features. - -CONFIG_DM ---------- - -* Status: In progress -* Deadline: 2020.01 - -Starting with the 2010.01 release CONFIG_DM will be enabled for all boards. -This does not concern CONFIG_DM_SPL and CONFIG_DM_TPL. The conversion date for -these configuration items still needs to be defined. - -CONFIG_DM_MMC -------------- - -* Status: In progress -* Deadline: 2019.04 - -The subsystem itself has been converted and maintainers should submit patches -switching over to using CONFIG_DM_MMC and other base driver model options in -time for inclusion in the 2019.04 rerelease. - -CONFIG_DM_USB -------------- - -* Status: In progress -* Deadline: 2019.07 - -The subsystem itself has been converted along with many of the host controller -and maintainers should submit patches switching over to using CONFIG_DM_USB and -other base driver model options in time for inclusion in the 2019.07 rerelease. - -CONFIG_SATA ------------ - -* Status: In progress -* Deadline: 2019.07 - -The subsystem itself has been converted along with many of the host controller -and maintainers should submit patches switching over to using CONFIG_AHCI and -other base driver model options in time for inclusion in the 2019.07 rerelease. - -CONFIG_BLK ----------- - -* Status: In progress -* Deadline: 2019.07 - -In concert with maintainers migrating their block device usage to the -appropriate DM driver, CONFIG_BLK needs to be set as well. The final deadline -here coincides with the final deadline for migration of the various block -subsystems. At this point we will be able to audit and correct the logic in -Kconfig around using CONFIG_PARTITIONS and CONFIG_HAVE_BLOCK_DEVICE and make -use of CONFIG_BLK / CONFIG_SPL_BLK as needed. - -CONFIG_DM_SPI / CONFIG_DM_SPI_FLASH ------------------------------------ - -Board Maintainers should submit the patches for enabling DM_SPI and DM_SPI_FLASH -to move the migration with in the deadline. - -Partially converted:: - - drivers/spi/fsl_espi.c - drivers/spi/mxc_spi.c - drivers/spi/sh_qspi.c - -* Status: In progress -* Deadline: 2019.07 - -CONFIG_DM_PCI -------------- -Deadline: 2019.07 - -The PCI subsystem has supported driver model since mid 2015. Maintainers should -submit patches switching over to using CONFIG_DM_PCI and other base driver -model options in time for inclusion in the 2019.07 release. - - -CONFIG_DM_VIDEO ---------------- -Deadline: 2019.07 - -The video subsystem has supported driver model since early 2016. Maintainers -should submit patches switching over to using CONFIG_DM_VIDEO and other base -driver model options in time for inclusion in the 2019.07 release. - -CONFIG_DM_ETH -------------- -Deadline: 2020.07 - -The network subsystem has supported the driver model since early 2015. -Maintainers should submit patches switching over to using CONFIG_DM_ETH and -other base driver model options in time for inclusion in the 2020.07 release. diff --git a/doc/driver-model/of-plat.rst b/doc/driver-model/of-plat.rst deleted file mode 100644 index 74f1932..0000000 --- a/doc/driver-model/of-plat.rst +++ /dev/null @@ -1,913 +0,0 @@ -.. SPDX-License-Identifier: GPL-2.0+ - -Compiled-in Device Tree / Platform Data -======================================= - - -Introduction ------------- - -Device tree is the standard configuration method in U-Boot. It is used to -define what devices are in the system and provide configuration information -to these devices. - -The overhead of adding devicetree access to U-Boot is fairly modest, -approximately 3KB on Thumb 2 (plus the size of the DT itself). This means -that in most cases it is best to use devicetree for configuration. - -However there are some very constrained environments where U-Boot needs to -work. These include SPL with severe memory limitations. For example, some -SoCs require a 16KB SPL image which must include a full MMC stack. In this -case the overhead of devicetree access may be too great. - -It is possible to create platform data manually by defining C structures -for it, and reference that data in a `U_BOOT_DRVINFO()` declaration. This -bypasses the use of devicetree completely, effectively creating a parallel -configuration mechanism. But it is an available option for SPL. - -As an alternative, the 'of-platdata' feature is provided. This converts the -devicetree contents into C code which can be compiled into the SPL binary. -This saves the 3KB of code overhead and perhaps a few hundred more bytes due -to more efficient storage of the data. - - -How it works ------------- - -The feature is enabled by CONFIG OF_PLATDATA. This is only available in -SPL/TPL and should be tested with: - -.. code-block:: c - - #if CONFIG_IS_ENABLED(OF_PLATDATA) - -A tool called 'dtoc' converts a devicetree file either into a set of -struct declarations, one for each compatible node, and a set of -`U_BOOT_DRVINFO()` declarations along with the actual platform data for each -device. As an example, consider this MMC node: - -.. code-block:: none - - sdmmc: dwmmc@ff0c0000 { - compatible = "rockchip,rk3288-dw-mshc"; - clock-freq-min-max = <400000 150000000>; - clocks = <&cru HCLK_SDMMC>, <&cru SCLK_SDMMC>, - <&cru SCLK_SDMMC_DRV>, <&cru SCLK_SDMMC_SAMPLE>; - clock-names = "biu", "ciu", "ciu_drv", "ciu_sample"; - fifo-depth = <0x100>; - interrupts = <GIC_SPI 32 IRQ_TYPE_LEVEL_HIGH>; - reg = <0xff0c0000 0x4000>; - bus-width = <4>; - cap-mmc-highspeed; - cap-sd-highspeed; - card-detect-delay = <200>; - disable-wp; - num-slots = <1>; - pinctrl-names = "default"; - pinctrl-0 = <&sdmmc_clk>, <&sdmmc_cmd>, <&sdmmc_cd>, <&sdmmc_bus4>; - vmmc-supply = <&vcc_sd>; - status = "okay"; - u-boot,dm-pre-reloc; - }; - - -Some of these properties are dropped by U-Boot under control of the -CONFIG_OF_SPL_REMOVE_PROPS option. The rest are processed. This will produce -the following C struct declaration: - -.. code-block:: c - - struct dtd_rockchip_rk3288_dw_mshc { - fdt32_t bus_width; - bool cap_mmc_highspeed; - bool cap_sd_highspeed; - fdt32_t card_detect_delay; - fdt32_t clock_freq_min_max[2]; - struct phandle_1_arg clocks[4]; - bool disable_wp; - fdt32_t fifo_depth; - fdt32_t interrupts[3]; - fdt32_t num_slots; - fdt32_t reg[2]; - fdt32_t vmmc_supply; - }; - -and the following device declarations: - -.. code-block:: c - - /* Node /clock-controller@ff760000 index 0 */ - ... - - /* Node /dwmmc@ff0c0000 index 2 */ - static struct dtd_rockchip_rk3288_dw_mshc dtv_dwmmc_at_ff0c0000 = { - .fifo_depth = 0x100, - .cap_sd_highspeed = true, - .interrupts = {0x0, 0x20, 0x4}, - .clock_freq_min_max = {0x61a80, 0x8f0d180}, - .vmmc_supply = 0xb, - .num_slots = 0x1, - .clocks = {{0, 456}, - {0, 68}, - {0, 114}, - {0, 118}}, - .cap_mmc_highspeed = true, - .disable_wp = true, - .bus_width = 0x4, - .u_boot_dm_pre_reloc = true, - .reg = {0xff0c0000, 0x4000}, - .card_detect_delay = 0xc8, - }; - - U_BOOT_DRVINFO(dwmmc_at_ff0c0000) = { - .name = "rockchip_rk3288_dw_mshc", - .plat = &dtv_dwmmc_at_ff0c0000, - .plat_size = sizeof(dtv_dwmmc_at_ff0c0000), - .parent_idx = -1, - }; - -The device is then instantiated at run-time and the platform data can be -accessed using: - -.. code-block:: c - - struct udevice *dev; - struct dtd_rockchip_rk3288_dw_mshc *plat = dev_get_plat(dev); - -This avoids the code overhead of converting the devicetree data to -platform data in the driver. The `of_to_plat()` method should -therefore do nothing in such a driver. - -Note that for the platform data to be matched with a driver, the 'name' -property of the `U_BOOT_DRVINFO()` declaration has to match a driver declared -via `U_BOOT_DRIVER()`. This effectively means that a `U_BOOT_DRIVER()` with a -'name' corresponding to the devicetree 'compatible' string (after converting -it to a valid name for C) is needed, so a dedicated driver is required for -each 'compatible' string. - -In order to make this a bit more flexible, the `DM_DRIVER_ALIAS()` macro can be -used to declare an alias for a driver name, typically a 'compatible' string. -This macro produces no code, but is used by dtoc tool. It must be located in the -same file as its associated driver, ideally just after it. - -The parent_idx is the index of the parent `driver_info` structure within its -linker list (instantiated by the `U_BOOT_DRVINFO()` macro). This is used to -support `dev_get_parent()`. - -During the build process dtoc parses both `U_BOOT_DRIVER()` and -`DM_DRIVER_ALIAS()` to build a list of valid driver names and driver aliases. -If the 'compatible' string used for a device does not not match a valid driver -name, it will be checked against the list of driver aliases in order to get the -right driver name to use. If in this step there is no match found a warning is -issued to avoid run-time failures. - -Where a node has multiple compatible strings, dtoc generates a `#define` to -make them equivalent, e.g.: - -.. code-block:: c - - #define dtd_rockchip_rk3299_dw_mshc dtd_rockchip_rk3288_dw_mshc - - -Converting of-platdata to a useful form ---------------------------------------- - -Of course it would be possible to use the of-platdata directly in your driver -whenever configuration information is required. However this means that the -driver will not be able to support devicetree, since the of-platdata -structure is not available when devicetree is used. It would make no sense -to use this structure if devicetree were available, since the structure has -all the limitations metioned in caveats below. - -Therefore it is recommended that the of-platdata structure should be used -only in the `probe()` method of your driver. It cannot be used in the -`of_to_plat()` method since this is not called when platform data is -already present. - - -How to structure your driver ----------------------------- - -Drivers should always support devicetree as an option. The of-platdata -feature is intended as a add-on to existing drivers. - -Your driver should convert the plat struct in its `probe()` method. The -existing devicetree decoding logic should be kept in the -`of_to_plat()` method and wrapped with `#if`. - -For example: - -.. code-block:: c - - #include <dt-structs.h> - - struct mmc_plat { - #if CONFIG_IS_ENABLED(OF_PLATDATA) - /* Put this first since driver model will copy the data here */ - struct dtd_mmc dtplat; - #endif - /* - * Other fields can go here, to be filled in by decoding from - * the devicetree (or the C structures when of-platdata is used). - */ - int fifo_depth; - }; - - static int mmc_of_to_plat(struct udevice *dev) - { - #if !CONFIG_IS_ENABLED(OF_PLATDATA) - /* Decode the devicetree data */ - struct mmc_plat *plat = dev_get_plat(dev); - const void *blob = gd->fdt_blob; - int node = dev_of_offset(dev); - - plat->fifo_depth = fdtdec_get_int(blob, node, "fifo-depth", 0); - #endif - - return 0; - } - - static int mmc_probe(struct udevice *dev) - { - struct mmc_plat *plat = dev_get_plat(dev); - - #if CONFIG_IS_ENABLED(OF_PLATDATA) - /* Decode the of-platdata from the C structures */ - struct dtd_mmc *dtplat = &plat->dtplat; - - plat->fifo_depth = dtplat->fifo_depth; - #endif - /* Set up the device from the plat data */ - writel(plat->fifo_depth, ...) - } - - static const struct udevice_id mmc_ids[] = { - { .compatible = "vendor,mmc" }, - { } - }; - - U_BOOT_DRIVER(mmc_drv) = { - .name = "mmc_drv", - .id = UCLASS_MMC, - .of_match = mmc_ids, - .of_to_plat = mmc_of_to_plat, - .probe = mmc_probe, - .priv_auto = sizeof(struct mmc_priv), - .plat_auto = sizeof(struct mmc_plat), - }; - - DM_DRIVER_ALIAS(mmc_drv, vendor_mmc) /* matches compatible string */ - -Note that `struct mmc_plat` is defined in the C file, not in a header. This -is to avoid needing to include dt-structs.h in a header file. The idea is to -keep the use of each of-platdata struct to the smallest possible code area. -There is just one driver C file for each struct, that can convert from the -of-platdata struct to the standard one used by the driver. - -In the case where SPL_OF_PLATDATA is enabled, `plat_auto` is -still used to allocate space for the platform data. This is different from -the normal behaviour and is triggered by the use of of-platdata (strictly -speaking it is a non-zero `plat_size` which triggers this). - -The of-platdata struct contents is copied from the C structure data to the -start of the newly allocated area. In the case where devicetree is used, -the platform data is allocated, and starts zeroed. In this case the -`of_to_plat()` method should still set up the platform data (and the -of-platdata struct will not be present). - -SPL must use either of-platdata or devicetree. Drivers cannot use both at -the same time, but they must support devicetree. Supporting of-platdata is -optional. - -The devicetree becomes inaccessible when CONFIG_SPL_OF_PLATDATA is enabled, -since the devicetree access code is not compiled in. A corollary is that -a board can only move to using of-platdata if all the drivers it uses support -it. There would be little point in having some drivers require the device -tree data, since then libfdt would still be needed for those drivers and -there would be no code-size benefit. - - -Build-time instantiation ------------------------- - -Even with of-platdata there is a fair amount of code required in driver model. -It is possible to have U-Boot handle the instantiation of devices at build-time, -so avoiding the need for the `device_bind()` code and some parts of -`device_probe()`. - -The feature is enabled by CONFIG_OF_PLATDATA_INST. - -Here is an example device, as generated by dtoc:: - - /* - * Node /serial index 6 - * driver sandbox_serial parent root_driver - */ - - #include <asm/serial.h> - struct sandbox_serial_plat __attribute__ ((section (".priv_data"))) - _sandbox_serial_plat_serial = { - .dtplat = { - .sandbox_text_colour = "cyan", - }, - }; - #include <asm/serial.h> - u8 _sandbox_serial_priv_serial[sizeof(struct sandbox_serial_priv)] - __attribute__ ((section (".priv_data"))); - #include <serial.h> - u8 _sandbox_serial_uc_priv_serial[sizeof(struct serial_dev_priv)] - __attribute__ ((section (".priv_data"))); - - DM_DEVICE_INST(serial) = { - .driver = DM_DRIVER_REF(sandbox_serial), - .name = "sandbox_serial", - .plat_ = &_sandbox_serial_plat_serial, - .priv_ = _sandbox_serial_priv_serial, - .uclass = DM_UCLASS_REF(serial), - .uclass_priv_ = _sandbox_serial_uc_priv_serial, - .uclass_node = { - .prev = &DM_UCLASS_REF(serial)->dev_head, - .next = &DM_UCLASS_REF(serial)->dev_head, - }, - .child_head = { - .prev = &DM_DEVICE_REF(serial)->child_head, - .next = &DM_DEVICE_REF(serial)->child_head, - }, - .sibling_node = { - .prev = &DM_DEVICE_REF(i2c_at_0)->sibling_node, - .next = &DM_DEVICE_REF(spl_test)->sibling_node, - }, - .seq_ = 0, - }; - -Here is part of the driver, for reference:: - - static const struct udevice_id sandbox_serial_ids[] = { - { .compatible = "sandbox,serial" }, - { } - }; - - U_BOOT_DRIVER(sandbox_serial) = { - .name = "sandbox_serial", - .id = UCLASS_SERIAL, - .of_match = sandbox_serial_ids, - .of_to_plat = sandbox_serial_of_to_plat, - .plat_auto = sizeof(struct sandbox_serial_plat), - .priv_auto = sizeof(struct sandbox_serial_priv), - .probe = sandbox_serial_probe, - .remove = sandbox_serial_remove, - .ops = &sandbox_serial_ops, - .flags = DM_FLAG_PRE_RELOC, - }; - - -The `DM_DEVICE_INST()` macro declares a struct udevice so you can see that the -members are from that struct. The private data is declared immediately above, -as `_sandbox_serial_priv_serial`, so there is no need for run-time memory -allocation. The #include lines are generated as well, since dtoc searches the -U-Boot source code for the definition of `struct sandbox_serial_priv` and adds -the relevant header so that the code will compile without errors. - -The `plat_` member is set to the dtv data which is declared immediately above -the device. This is similar to how it would look without of-platdata-inst, but -node that the `dtplat` member inside is part of the wider -`_sandbox_serial_plat_serial` struct. This is because the driver declares its -own platform data, and the part generated by dtoc can only be a portion of it. -The `dtplat` part is always first in the struct. If the device has no -`.plat_auto` field, then a simple dtv struct can be used as with this example:: - - static struct dtd_sandbox_clk dtv_clk_sbox = { - .assigned_clock_rates = 0x141, - .assigned_clocks = {0x7, 0x3}, - }; - - #include <asm/clk.h> - u8 _sandbox_clk_priv_clk_sbox[sizeof(struct sandbox_clk_priv)] - __attribute__ ((section (".priv_data"))); - - DM_DEVICE_INST(clk_sbox) = { - .driver = DM_DRIVER_REF(sandbox_clk), - .name = "sandbox_clk", - .plat_ = &dtv_clk_sbox, - -Here is part of the driver, for reference:: - - static const struct udevice_id sandbox_clk_ids[] = { - { .compatible = "sandbox,clk" }, - { } - }; - - U_BOOT_DRIVER(sandbox_clk) = { - .name = "sandbox_clk", - .id = UCLASS_CLK, - .of_match = sandbox_clk_ids, - .ops = &sandbox_clk_ops, - .probe = sandbox_clk_probe, - .priv_auto = sizeof(struct sandbox_clk_priv), - }; - - -You can see that `dtv_clk_sbox` just has the devicetree contents and there is -no need for the `dtplat` separation, since the driver has no platform data of -its own, besides that provided by the devicetree (i.e. no `.plat_auto` field). - -The doubly linked lists are handled by explicitly declaring the value of each -node, as you can see with the `.prev` and `.next` values in the example above. -Since dtoc knows the order of devices it can link them into the appropriate -lists correctly. - -One of the features of driver model is the ability for a uclass to have a -small amount of private data for each device in that uclass. This is used to -provide a generic data structure that the uclass can use for all devices, thus -allowing generic features to be implemented in common code. An example is I2C, -which stores the bus speed there. - -Similarly, parent devices can have data associated with each of their children. -This is used to provide information common to all children of a particular bus. -For an I2C bus, this is used to store the I2C address of each child on the bus. - -This is all handled automatically by dtoc:: - - #include <asm/i2c.h> - u8 _sandbox_i2c_priv_i2c_at_0[sizeof(struct sandbox_i2c_priv)] - __attribute__ ((section (".priv_data"))); - #include <i2c.h> - u8 _sandbox_i2c_uc_priv_i2c_at_0[sizeof(struct dm_i2c_bus)] - __attribute__ ((section (".priv_data"))); - - DM_DEVICE_INST(i2c_at_0) = { - .driver = DM_DRIVER_REF(sandbox_i2c), - .name = "sandbox_i2c", - .plat_ = &dtv_i2c_at_0, - .priv_ = _sandbox_i2c_priv_i2c_at_0, - .uclass = DM_UCLASS_REF(i2c), - .uclass_priv_ = _sandbox_i2c_uc_priv_i2c_at_0, - ... - -Part of driver, for reference:: - - static const struct udevice_id sandbox_i2c_ids[] = { - { .compatible = "sandbox,i2c" }, - { } - }; - - U_BOOT_DRIVER(sandbox_i2c) = { - .name = "sandbox_i2c", - .id = UCLASS_I2C, - .of_match = sandbox_i2c_ids, - .ops = &sandbox_i2c_ops, - .priv_auto = sizeof(struct sandbox_i2c_priv), - }; - -Part of I2C uclass, for reference:: - - UCLASS_DRIVER(i2c) = { - .id = UCLASS_I2C, - .name = "i2c", - .flags = DM_UC_FLAG_SEQ_ALIAS, - .post_bind = i2c_post_bind, - .pre_probe = i2c_pre_probe, - .post_probe = i2c_post_probe, - .per_device_auto = sizeof(struct dm_i2c_bus), - .per_child_plat_auto = sizeof(struct dm_i2c_chip), - .child_post_bind = i2c_child_post_bind, - }; - -Here, `_sandbox_i2c_uc_priv_i2c_at_0` is required by the uclass but is declared -in the device, as required by driver model. The required header file is included -so that the code will compile without errors. A similar mechanism is used for -child devices, but is not shown by this example. - -It would not be that useful to avoid binding devices but still need to allocate -uclasses at runtime. So dtoc generates uclass instances as well:: - - struct list_head uclass_head = { - .prev = &DM_UCLASS_REF(serial)->sibling_node, - .next = &DM_UCLASS_REF(clk)->sibling_node, - }; - - DM_UCLASS_INST(clk) = { - .uc_drv = DM_UCLASS_DRIVER_REF(clk), - .sibling_node = { - .prev = &uclass_head, - .next = &DM_UCLASS_REF(i2c)->sibling_node, - }, - .dev_head = { - .prev = &DM_DEVICE_REF(clk_sbox)->uclass_node, - .next = &DM_DEVICE_REF(clk_fixed)->uclass_node, - }, - }; - -At the top is the list head. Driver model uses this on start-up, instead of -creating its own. - -Below that are a set of `DM_UCLASS_INST()` macros, each declaring a -`struct uclass`. The doubly linked lists work as for devices. - -All private data is placed into a `.priv_data` section so that it is contiguous -in the resulting output binary. - - -Indexes -------- - -U-Boot stores drivers, devices and many other things in linker_list structures. -These are sorted by name, so dtoc knows the order that they will appear when -the linker runs. Each driver_info / udevice is referenced by its index in the -linker_list array, called 'idx' in the code. - -When CONFIG_OF_PLATDATA_INST is enabled, idx is the udevice index, otherwise it -is the driver_info index. In either case, indexes are used to reference devices -using device_get_by_ofplat_idx(). This allows phandles to work as expected. - - -Phases ------- - -U-Boot operates in several phases, typically TPL, SPL and U-Boot proper. -The latter does not use dtoc. - -In some rare cases different drivers are used for two phases. For example, -in TPL it may not be necessary to use the full PCI subsystem, so a simple -driver can be used instead. - -This works in the build system simply by compiling in one driver or the -other (e.g. PCI driver + uclass for SPL; simple_bus for TPL). But dtoc has -no way of knowing which code is compiled in for which phase, since it does -not inspect Makefiles or dependency graphs. - -So to make this work for dtoc, we need to be able to explicitly mark -drivers with their phase. This is done by adding a macro to the driver:: - - /* code in tpl.c only compiled into TPL */ - U_BOOT_DRIVER(pci_x86) = { - .name = "pci_x86", - .id = UCLASS_SIMPLE_BUS, - .of_match = of_match_ptr(tpl_fake_pci_ids), - DM_PHASE(tpl) - }; - - - /* code in pci_x86.c compiled into SPL and U-Boot proper */ - U_BOOT_DRIVER(pci_x86) = { - .name = "pci_x86", - .id = UCLASS_PCI, - .of_match = pci_x86_ids, - .ops = &pci_x86_ops, - }; - - -Notice that the second driver has the same name but no DM_PHASE(), so it will be -used for SPL and U-Boot. - -Note also that this only affects the code generated by dtoc. You still need to -make sure that only the required driver is build into each phase. - - -Header files ------------- - -With OF_PLATDATA_INST, dtoc must include the correct header file in the -generated code for any structs that are used, so that the code will compile. -For example, if `struct ns16550_plat` is used, the code must include the -`ns16550.h` header file. - -Typically dtoc can detect the header file needed for a driver by looking -for the structs that it uses. For example, if a driver as a `.priv_auto` -that uses `struct ns16550_plat`, then dtoc can search header files for the -definition of that struct and use the file. - -In some cases, enums are used in drivers, typically with the `.data` field -of `struct udevice_id`. Since dtoc does not support searching for these, -you must use the `DM_HDR()` macro to tell dtoc which header to use. This works -as a macro included in the driver definition:: - - static const struct udevice_id apl_syscon_ids[] = { - { .compatible = "intel,apl-punit", .data = X86_SYSCON_PUNIT }, - { } - }; - - U_BOOT_DRIVER(intel_apl_punit) = { - .name = "intel_apl_punit", - .id = UCLASS_SYSCON, - .of_match = apl_syscon_ids, - .probe = apl_punit_probe, - DM_HEADER(<asm/cpu.h>) /* for X86_SYSCON_PUNIT */ - }; - - - -Caveats -------- - -There are various complications with this feature which mean it should only -be used when strictly necessary, i.e. in SPL with limited memory. Notable -caveats include: - - - Device tree does not describe data types. But the C code must define a - type for each property. These are guessed using heuristics which - are wrong in several fairly common cases. For example an 8-byte value - is considered to be a 2-item integer array, and is byte-swapped. A - boolean value that is not present means 'false', but cannot be - included in the structures since there is generally no mention of it - in the devicetree file. - - - Naming of nodes and properties is automatic. This means that they follow - the naming in the devicetree, which may result in C identifiers that - look a bit strange. - - - It is not possible to find a value given a property name. Code must use - the associated C member variable directly in the code. This makes - the code less robust in the face of devicetree changes. To avoid having - a second struct with similar members and names you need to explicitly - declare it as an alias with `DM_DRIVER_ALIAS()`. - - - The platform data is provided to drivers as a C structure. The driver - must use the same structure to access the data. Since a driver - normally also supports devicetree it must use `#ifdef` to separate - out this code, since the structures are only available in SPL. This could - be fixed fairly easily by making the structs available outside SPL, so - that `IS_ENABLED()` could be used. - - - With CONFIG_OF_PLATDATA_INST all binding happens at build-time, meaning - that (by default) it is not possible to call `device_bind()` from C code. - This means that all devices must have an associated devicetree node and - compatible string. For example if a GPIO device currently creates child - devices in its `bind()` method, it will not work with - CONFIG_OF_PLATDATA_INST. Arguably this is bad practice anyway and the - devicetree binding should be updated to declare compatible strings for - the child devices. It is possible to disable OF_PLATDATA_NO_BIND but this - is not recommended since it increases code size. - - -Internals ---------- - -Generated files -``````````````` - -When enabled, dtoc generates the following five files: - -include/generated/dt-decl.h (OF_PLATDATA_INST only) - Contains declarations for all drivers, devices and uclasses. This allows - any `struct udevice`, `struct driver` or `struct uclass` to be located by its - name - -include/generated/dt-structs-gen.h - Contains the struct definitions for the devicetree nodes that are used. This - is the same as without OF_PLATDATA_INST - -spl/dts/dt-plat.c (only with !OF_PLATDATA_INST) - Contains the `U_BOOT_DRVINFO()` declarations that U-Boot uses to bind devices - at start-up. See above for an example - -spl/dts/dt-device.c (only with OF_PLATDATA_INST) - Contains `DM_DEVICE_INST()` declarations for each device that can be used at - run-time. These are declared in the file along with any private/platform data - that they use. Every device has an idx, as above. Since each device must be - part of a double-linked list, the nodes are declared in the code as well. - -spl/dts/dt-uclass.c (only with OF_PLATDATA_INST) - Contains `DM_UCLASS_INST()` declarations for each uclass that can be used at - run-time. These are declared in the file along with any private data - associated with the uclass itself (the `.priv_auto` member). Since each - uclass must be part of a double-linked list, the nodes are declared in the - code as well. - -The dt-structs.h file includes the generated file -`(include/generated/dt-structs.h`) if CONFIG_SPL_OF_PLATDATA is enabled. -Otherwise (such as in U-Boot proper) these structs are not available. This -prevents them being used inadvertently. All usage must be bracketed with -`#if CONFIG_IS_ENABLED(OF_PLATDATA)`. - -The dt-plat.c file contains the device declarations and is is built in -spl/dt-plat.c. - - -CONFIG options -`````````````` - -Several CONFIG options are used to control the behaviour of of-platdata, all -available for both SPL and TPL: - -OF_PLATDATA - This is the main option which enables the of-platdata feature - -OF_PLATDATA_PARENT - This allows `device_get_parent()` to work. Without this, all devices exist as - direct children of the root node. This option is highly desirable (if not - always absolutely essential) for buses such as I2C. - -OF_PLATDATA_INST - This controls the instantiation of devices at build time. With it disabled, - only `U_BOOT_DRVINFO()` records are created, with U-Boot handling the binding - in `device_bind()` on start-up. With it enabled, only `DM_DEVICE_INST()` and - `DM_UCLASS_INST()` records are created, and `device_bind()` is not needed at - runtime. - -OF_PLATDATA_NO_BIND - This controls whether `device_bind()` is supported. It is enabled by default - with OF_PLATDATA_INST since code-size reduction is really the main point of - the feature. It can be disabled if needed but is not likely to be supported - in the long term. - -OF_PLATDATA_DRIVER_RT - This controls whether the `struct driver_rt` records are used by U-Boot. - Normally when a device is bound, U-Boot stores the device pointer in one of - these records. There is one for every `struct driver_info` in the system, - i.e. one for every device that is bound from those records. It provides a - way to locate a device in the code and is used by - `device_get_by_ofplat_idx()`. This option is always enabled with of-platdata, - provided OF_PLATDATA_INST is not. In that case the records are useless since - we don't have any `struct driver_info` records. - -OF_PLATDATA_RT - This controls whether the `struct udevice_rt` records are used by U-Boot. - It moves the updatable fields from `struct udevice` (currently only `flags`) - into a separate structure, allowing the records to be kept in read-only - memory. It is generally enabled if OF_PLATDATA_INST is enabled. This option - also controls whether the private data is used in situ, or first copied into - an allocated region. Again this is to allow the private data declared by - dtoc-generated code to be in read-only memory. Note that access to private - data must be done via accessor functions, such as `dev_get_priv()`, so that - the relocation is handled. - -READ_ONLY - This indicates that the data generated by dtoc should not be modified. Only - a few fields actually do get changed in U-Boot, such as device flags. This - option causes those to move into an allocated space (see OF_PLATDATA_RT). - Also, since updating doubly linked lists is generally impossible when some of - the nodes cannot be updated, OF_PLATDATA_NO_BIND is enabled. - -Data structures -``````````````` - -A few extra data structures are used with of-platdata: - -`struct udevice_rt` - Run-time information for devices. When OF_PLATDATA_RT is enabled, this holds - the flags for each device, so that `struct udevice` can remain unchanged by - U-Boot, and potentially reside in read-only memory. Access to flags is then - via functions like `dev_get_flags()` and `dev_or_flags()`. This data - structure is allocated on start-up, where the private data is also copied. - All flags values start at 0 and any changes are handled by `dev_or_flags()` - and `dev_bic_flags()`. It would be more correct for the flags to be set to - `DM_FLAG_BOUND`, or perhaps `DM_FLAG_BOUND | DM_FLAG_ALLOC_PDATA`, but since - there is no code to bind/unbind devices and no code to allocate/free - private data / platform data, it doesn't matter. - -`struct driver_rt` - Run-time information for `struct driver_info` records. When - OF_PLATDATA_DRIVER_RT is enabled, this holds a pointer to the device - created by each record. This is needed so that is it possible to locate a - device from C code. Specifically, the code can use `DM_DRVINFO_GET(name)` to - get a reference to a particular `struct driver_info`, with `name` being the - name of the devicetree node. This is very convenient. It is also fast, since - no searching or string comparison is needed. This data structure is - allocated on start-up, filled out by `device_bind()` and used by - `device_get_by_ofplat_idx()`. - -Other changes -````````````` - -Some other changes are made with of-platdata: - -Accessor functions - Accessing private / platform data via functions such as `dev_get_priv()` has - always been encouraged. With OF_PLATDATA_RT this is essential, since the - `priv_` and `plat_` (etc.) values point to the data generated by dtoc, not - the read-write copy that is sometimes made on start-up. Changing the - private / platform data pointers has always been discouraged (the API is - marked internal) but with OF_PLATDATA_RT this is not currently supported in - general, since it assumes that all such pointers point to the relocated data. - Note also that the renaming of struct members to have a trailing underscore - was partly done to make people aware that they should not be accessed - directly. - -`gd->uclass_root_s` - Normally U-Boot sets up the head of the uclass list here and makes - `gd->uclass_root` point to it. With OF_PLATDATA_INST, dtoc generates a - declaration of `uclass_head` in `dt-uclass.c` since it needs to link the - head node into the list. In that case, `gd->uclass_root_s` is not used and - U-Boot just makes `gd->uclass_root` point to `uclass_head`. - -`gd->dm_driver_rt` - This holds a pointer to a list of `struct driver_rt` records, one for each - `struct driver_info`. The list is in alphabetical order by the name used - in `U_BOOT_DRVINFO(name)` and indexed by idx, with the first record having - an index of 0. It is only used if OF_PLATDATA_INST is not enabled. This is - accessed via macros so that it can be used inside IS_ENABLED(), rather than - requiring #ifdefs in the C code when it is not present. - -`gd->dm_udevice_rt` - This holds a pointer to a list of `struct udevice_rt` records, one for each - `struct udevice`. The list is in alphabetical order by the name used - in `DM_DEVICE_INST(name)` (a C version of the devicetree node) and indexed by - idx, with the first record having an index of 0. It is only used if - OF_PLATDATA_INST is enabled. This is accessed via macros so that it can be - used inside `IS_ENABLED()`, rather than requiring #ifdefs in the C code when - it is not present. - -`gd->dm_priv_base` - When OF_PLATDATA_RT is enabled, the private/platform data for each device is - copied into an allocated region by U-Boot on start-up. This points to that - region. All calls to accessor functions (e.g. `dev_get_priv()`) then - translate from the pointer provided by the caller (assumed to lie between - `__priv_data_start` and `__priv_data_end`) to the new allocated region. This - member is accessed via macros so that it can be used inside IS_ENABLED(), - rather than required #ifdefs in the C code when it is not present. - -`struct udevice->flags_` - When OF_PLATDATA_RT is enabled, device flags are no-longer part of - `struct udevice`, but are instead kept in `struct udevice_rt`, as described - above. Flags are accessed via functions, such as `dev_get_flags()` and - `dev_or_flags()`. - -`struct udevice->node_` - When OF_PLATDATA is enabled, there is no devicetree at runtime, so no need - for this field. It is removed, just to save space. - -`DM_PHASE` - This macro is used to indicate which phase of U-Boot a driver is intended - for. See above for details. - -`DM_HDR` - This macro is used to indicate which header file dtoc should use to allow - a driver declaration to compile correctly. See above for details. - -`device_get_by_ofplat_idx()` - There used to be a function called `device_get_by_driver_info()` which - looked up a `struct driver_info` pointer and returned the `struct udevice` - that was created from it. It was only available for use with of-platdata. - This has been removed in favour of `device_get_by_ofplat_idx()` which uses - `idx`, the index of the `struct driver_info` or `struct udevice` in the - linker_list. Similarly, the `struct phandle_0_arg` (etc.) structs have been - updated to use this index instead of a pointer to `struct driver_info`. - -`DM_DRVINFO_GET` - This has been removed since we now use indexes to obtain a driver from - `struct phandle_0_arg` and the like. - -Two-pass binding - The original of-platdata tried to order `U_BOOT_DRVINFO()` in the generated - files so as to have parents declared ahead of children. This was convenient - as it avoided any special code in U-Boot. With OF_PLATDATA_INST this does - not work as the idx value relies on using alphabetical order for everything, - so that dtoc and U-Boot's linker_lists agree on the idx value. Devices are - then bound in order of idx, having no regard to parent/child relationships. - For this reason, device binding now hapens in multiple passes, with parents - being bound before their children. This is important so that children can - find their parents in the bind() method if needed. - -Root device - The root device is generally bound by U-Boot but with OF_PLATDATA_INST it - cannot be, since binding needs to be done at build time. So in this case - dtoc sets up a root device using `DM_DEVICE_INST()` in `dt-device.c` and - U-Boot makes use of that. When OF_PLATDATA_INST is not enabled, U-Boot - generally ignores the root node and does not create a `U_BOOT_DRVINFO()` - record for it. This means that the idx numbers used by `struct driver_info` - (when OF_PLATDATA_INST is disabled) and the idx numbers used by - `struct udevice` (when OF_PLATDATA_INST is enabled) differ, since one has a - root node and the other does not. This does not actually matter, since only - one of them is actually used for any particular build, but it is worth - keeping in mind if comparing index values and switching OF_PLATDATA_INST on - and off. - -`__priv_data_start` and `__priv_data_end` - The private/platform data declared by dtoc is all collected together in - a linker section and these symbols mark the start and end of it. This allows - U-Boot to relocate the area to a new location if needed (with - OF_PLATDATA_RT) - -`dm_priv_to_rw()` - This function converts a private- or platform-data pointer value generated by - dtoc into one that can be used by U-Boot. It is a NOP unless OF_PLATDATA_RT - is enabled, in which case it translates the address to the relocated - region. See above for more information. - -The dm_populate_phandle_data() function that was previous needed has now been -removed, since dtoc can address the drivers directly from dt-plat.c and does -not need to fix up things at runtime. - -The pylibfdt Python module is used to access the devicetree. - - -Credits -------- - -This is an implementation of an idea by Tom Rini <trini@konsulko.com>. - - -Future work ------------ -- Consider programmatically reading binding files instead of devicetree - contents -- Allow IS_ENABLED() to be used in the C code instead of #if - - -.. Simon Glass <sjg@chromium.org> -.. Google, Inc -.. 6/6/16 -.. Updated Independence Day 2016 -.. Updated 1st October 2020 -.. Updated 5th February 2021 diff --git a/doc/driver-model/pci-info.rst b/doc/driver-model/pci-info.rst deleted file mode 100644 index 251601a..0000000 --- a/doc/driver-model/pci-info.rst +++ /dev/null @@ -1,172 +0,0 @@ -.. SPDX-License-Identifier: GPL-2.0+ - -PCI with Driver Model -===================== - -How busses are scanned ----------------------- - -Any config read will end up at pci_read_config(). This uses -uclass_get_device_by_seq() to get the PCI bus for a particular bus number. -Bus number 0 will need to be requested first, and the alias in the device -tree file will point to the correct device:: - - aliases { - pci0 = &pcic; - }; - - pcic: pci@0 { - compatible = "sandbox,pci"; - ... - }; - - -If there is no alias the devices will be numbered sequentially in the device -tree. - -The call to uclass_get_device() will cause the PCI bus to be probed. -This does a scan of the bus to locate available devices. These devices are -bound to their appropriate driver if available. If there is no driver, then -they are bound to a generic PCI driver which does nothing. - -After probing a bus, the available devices will appear in the device tree -under that bus. - -Note that this is all done on a lazy basis, as needed, so until something is -touched on PCI (eg: a call to pci_find_devices()) it will not be probed. - -PCI devices can appear in the flattened device tree. If they do, their node -often contains extra information which cannot be derived from the PCI IDs or -PCI class of the device. Each PCI device node must have a <reg> property, as -defined by the IEEE Std 1275-1994 PCI bus binding document v2.1. Compatible -string list is optional and generally not needed, since PCI is discoverable -bus, albeit there are justified exceptions. If the compatible string is -present, matching on it takes precedence over PCI IDs and PCI classes. - -Note we must describe PCI devices with the same bus hierarchy as the -hardware, otherwise driver model cannot detect the correct parent/children -relationship during PCI bus enumeration thus PCI devices won't be bound to -their drivers accordingly. A working example like below:: - - pci { - #address-cells = <3>; - #size-cells = <2>; - compatible = "pci-x86"; - u-boot,dm-pre-reloc; - ranges = <0x02000000 0x0 0x40000000 0x40000000 0 0x80000000 - 0x42000000 0x0 0xc0000000 0xc0000000 0 0x20000000 - 0x01000000 0x0 0x2000 0x2000 0 0xe000>; - - pcie@17,0 { - #address-cells = <3>; - #size-cells = <2>; - compatible = "pci-bridge"; - u-boot,dm-pre-reloc; - reg = <0x0000b800 0x0 0x0 0x0 0x0>; - - topcliff@0,0 { - #address-cells = <3>; - #size-cells = <2>; - compatible = "pci-bridge"; - u-boot,dm-pre-reloc; - reg = <0x00010000 0x0 0x0 0x0 0x0>; - - pciuart0: uart@a,1 { - compatible = "pci8086,8811.00", - "pci8086,8811", - "pciclass,070002", - "pciclass,0700", - "x86-uart"; - u-boot,dm-pre-reloc; - reg = <0x00025100 0x0 0x0 0x0 0x0 - 0x01025110 0x0 0x0 0x0 0x0>; - ...... - }; - - ...... - }; - }; - - ...... - }; - -In this example, the root PCI bus node is the "/pci" which matches "pci-x86" -driver. It has a subnode "pcie@17,0" with driver "pci-bridge". "pcie@17,0" -also has subnode "topcliff@0,0" which is a "pci-bridge" too. Under that bridge, -a PCI UART device "uart@a,1" is described. This exactly reflects the hardware -bus hierarchy: on the root PCI bus, there is a PCIe root port which connects -to a downstream device Topcliff chipset. Inside Topcliff chipset, it has a -PCIe-to-PCI bridge and all the chipset integrated devices like the PCI UART -device are on the PCI bus. Like other devices in the device tree, if we want -to bind PCI devices before relocation, "u-boot,dm-pre-reloc" must be declared -in each of these nodes. - -If PCI devices are not listed in the device tree, U_BOOT_PCI_DEVICE can be used -to specify the driver to use for the device. The device tree takes precedence -over U_BOOT_PCI_DEVICE. Please note with U_BOOT_PCI_DEVICE, only drivers with -DM_FLAG_PRE_RELOC will be bound before relocation. If neither device tree nor -U_BOOT_PCI_DEVICE is provided, the built-in driver (either pci_bridge_drv or -pci_generic_drv) will be used. - - -Sandbox -------- - -With sandbox we need a device emulator for each device on the bus since there -is no real PCI bus. This works by looking in the device tree node for an -emulator driver. For example:: - - pci@1f,0 { - compatible = "pci-generic"; - reg = <0xf800 0 0 0 0>; - sandbox,emul = <&emul_1f>; - }; - pci-emul { - compatible = "sandbox,pci-emul-parent"; - emul_1f: emul@1f,0 { - compatible = "sandbox,swap-case"; - #emul-cells = <0>; - }; - }; - -This means that there is a 'sandbox,swap-case' driver at that bus position. -Note that the first cell in the 'reg' value is the bus/device/function. See -PCI_BDF() for the encoding (it is also specified in the IEEE Std 1275-1994 -PCI bus binding document, v2.1) - -The pci-emul node should go outside the pci bus node, since otherwise it will -be scanned as a PCI device, causing confusion. - -When this bus is scanned we will end up with something like this:: - - `- * pci@0 @ 05c660c8, 0 - `- pci@1f,0 @ 05c661c8, 63488 - `- emul@1f,0 @ 05c662c8 - -When accesses go to the pci@1f,0 device they are forwarded to its emulator. - -The sandbox PCI drivers also support dynamic driver binding, allowing device -driver to declare the driver binding information via U_BOOT_PCI_DEVICE(), -eliminating the need to provide any device tree node under the host controller -node. It is required a "sandbox,dev-info" property must be provided in the -host controller node for this functionality to work. - -.. code-block:: none - - pci1: pci@1 { - compatible = "sandbox,pci"; - ... - sandbox,dev-info = <0x08 0x00 0x1234 0x5678 - 0x0c 0x00 0x1234 0x5678>; - }; - -The "sandbox,dev-info" property specifies all dynamic PCI devices on this bus. -Each dynamic PCI device is encoded as 4 cells a group. The first and second -cells are PCI device number and function number respectively. The third and -fourth cells are PCI vendor ID and device ID respectively. - -When this bus is scanned we will end up with something like this:: - - pci [ + ] pci_sandbo |-- pci1 - pci_emul [ ] sandbox_sw | |-- sandbox_swap_case_emul - pci_emul [ ] sandbox_sw | `-- sandbox_swap_case_emul diff --git a/doc/driver-model/pmic-framework.rst b/doc/driver-model/pmic-framework.rst deleted file mode 100644 index d24a1ba..0000000 --- a/doc/driver-model/pmic-framework.rst +++ /dev/null @@ -1,143 +0,0 @@ -.. SPDX-License-Identifier: GPL-2.0+ -.. (C) Copyright 2014-2015 Samsung Electronics -.. sectionauthor:: Przemyslaw Marczak <p.marczak@samsung.com> - -PMIC framework based on Driver Model -==================================== - -Introduction ------------- -This is an introduction to driver-model multi uclass PMIC IC's support. -At present it's based on two uclass types: - -UCLASS_PMIC: - basic uclass type for PMIC I/O, which provides common - read/write interface. -UCLASS_REGULATOR: - additional uclass type for specific PMIC features, which are - Voltage/Current regulators. - -New files: - -UCLASS_PMIC: - - drivers/power/pmic/pmic-uclass.c - - include/power/pmic.h -UCLASS_REGULATOR: - - drivers/power/regulator/regulator-uclass.c - - include/power/regulator.h - -Commands: -- common/cmd_pmic.c -- common/cmd_regulator.c - -How doees it work ------------------ -The Power Management Integrated Circuits (PMIC) are used in embedded systems -to provide stable, precise and specific voltage power source with over-voltage -and thermal protection circuits. - -The single PMIC can provide various functions by single or multiple interfaces, -like in the example below:: - - -- SoC - | - | ______________________________________ - | BUS 0 | Multi interface PMIC IC |--> LDO out 1 - | e.g.I2C0 | |--> LDO out N - |-----------|---- PMIC device 0 (READ/WRITE ops) | - | or SPI0 | |_ REGULATOR device (ldo/... ops) |--> BUCK out 1 - | | |_ CHARGER device (charger ops) |--> BUCK out M - | | |_ MUIC device (microUSB con ops) | - | BUS 1 | |_ ... |---> BATTERY - | e.g.I2C1 | | - |-----------|---- PMIC device 1 (READ/WRITE ops) |---> USB in 1 - . or SPI1 | |_ RTC device (rtc ops) |---> USB in 2 - . |______________________________________|---> USB out - . - -Since U-Boot provides driver model features for I2C and SPI bus drivers, -the PMIC devices should also support this. By the pmic and regulator API's, -PMIC drivers can simply provide a common functions, for multi-interface and -and multi-instance device support. - -Basic design assumptions: - -- Common I/O API: - UCLASS_PMIC. For the multi-function PMIC devices, this can be used as - parent I/O device for each IC's interface. Then, each children uses the - same dev for read/write. - -- Common regulator API: - UCLASS_REGULATOR. For driving the regulator attributes, auto setting - function or command line interface, based on kernel-style regulator device - tree constraints. - -For simple implementations, regulator drivers are not required, so the code can -use pmic read/write directly. - -Pmic uclass ------------ -The basic information: - -* Uclass: 'UCLASS_PMIC' -* Header: 'include/power/pmic.h' -* Core: 'drivers/power/pmic/pmic-uclass.c' (config 'CONFIG_DM_PMIC') -* Command: 'common/cmd_pmic.c' (config 'CONFIG_CMD_PMIC') -* Example: 'drivers/power/pmic/max77686.c' - -For detailed API description, please refer to the header file. - -As an example of the pmic driver, please refer to the MAX77686 driver. - -Please pay attention for the driver's bind() method. Exactly the function call: -'pmic_bind_children()', which is used to bind the regulators by using the array -of regulator's node, compatible prefixes. - -The 'pmic; command also supports the new API. So the pmic command can be enabled -by adding CONFIG_CMD_PMIC. -The new pmic command allows to: -- list pmic devices -- choose the current device (like the mmc command) -- read or write the pmic register -- dump all pmic registers - -This command can use only UCLASS_PMIC devices, since this uclass is designed -for pmic I/O operations only. - -For more information, please refer to the core file. - -Regulator uclass ----------------- -The basic information: - -* Uclass: 'UCLASS_REGULATOR' - -* Header: 'include/power/regulator.h' - -* Core: 'drivers/power/regulator/regulator-uclass.c' - (config 'CONFIG_DM_REGULATOR') - -* Binding: 'doc/device-tree-bindings/regulator/regulator.txt' - -* Command: 'common/cmd_regulator.c' (config 'CONFIG_CMD_REGULATOR') - -* Example: 'drivers/power/regulator/max77686.c' - 'drivers/power/pmic/max77686.c' (required I/O driver for the above) - -* Example: 'drivers/power/regulator/fixed.c' - (config 'CONFIG_DM_REGULATOR_FIXED') - -For detailed API description, please refer to the header file. - -For the example regulator driver, please refer to the MAX77686 regulator driver, -but this driver can't operate without pmic's example driver, which provides an -I/O interface for MAX77686 regulator. - -The second example is a fixed Voltage/Current regulator for a common use. - -The 'regulator' command also supports the new API. The command allow: -- list regulator devices -- choose the current device (like the mmc command) -- do all regulator-specific operations - -For more information, please refer to the command file. diff --git a/doc/driver-model/remoteproc-framework.rst b/doc/driver-model/remoteproc-framework.rst deleted file mode 100644 index 566495a..0000000 --- a/doc/driver-model/remoteproc-framework.rst +++ /dev/null @@ -1,169 +0,0 @@ -.. SPDX-License-Identifier: GPL-2.0+ -.. (C) Copyright 2015 -.. Texas Instruments Incorporated - http://www.ti.com/ - -Remote Processor Framework -========================== - -Introduction ------------- - -This is an introduction to driver-model for Remote Processors found -on various System on Chip(SoCs). The term remote processor is used to -indicate that this is not the processor on which U-Boot is operating -on, instead is yet another processing entity that may be controlled by -the processor on which we are functional. - -The simplified model depends on a single UCLASS - UCLASS_REMOTEPROC - -UCLASS_REMOTEPROC: - - drivers/remoteproc/rproc-uclass.c - - include/remoteproc.h - -Commands: - - common/cmd_remoteproc.c - -Configuration: - - CONFIG_REMOTEPROC is selected by drivers as needed - - CONFIG_CMD_REMOTEPROC for the commands if required. - -How does it work - The driver ------------------------------ - -Overall, the driver statemachine transitions are typically as follows:: - - (entry) - +-------+ - +---+ init | - | | | <---------------------+ - | +-------+ | - | | - | | - | +--------+ | - Load| | reset | | - | | | <----------+ | - | +--------+ | | - | |Load | | - | | | | - | +----v----+ reset | | - +-> | | (opt) | | - | Loaded +-----------+ | - | | | - +----+----+ | - | Start | - +---v-----+ (opt) | - +->| Running | Stop | - Ping +- | +--------------------+ - (opt) +---------+ - -(is_running does not change state) -opt: Optional state transition implemented by driver. - -NOTE: It depends on the remote processor as to the exact behavior -of the statemachine, remoteproc core does not intent to implement -statemachine logic. Certain processors may allow start/stop without -reloading the image in the middle, certain other processors may only -allow us to start the processor(image from a EEPROM/OTP) etc. - -It is hence the responsibility of the driver to handle the requisite -state transitions of the device as necessary. - -Basic design assumptions: - -Remote processor can operate on a certain firmware that maybe loaded -and released from reset. - -The driver follows a standard UCLASS DM. - -in the bare minimum form: - -.. code-block:: c - - static const struct dm_rproc_ops sandbox_testproc_ops = { - .load = sandbox_testproc_load, - .start = sandbox_testproc_start, - }; - - static const struct udevice_id sandbox_ids[] = { - {.compatible = "sandbox,test-processor"}, - {} - }; - - U_BOOT_DRIVER(sandbox_testproc) = { - .name = "sandbox_test_proc", - .of_match = sandbox_ids, - .id = UCLASS_REMOTEPROC, - .ops = &sandbox_testproc_ops, - .probe = sandbox_testproc_probe, - }; - -This allows for the device to be probed as part of the "init" command -or invocation of 'rproc_init()' function as the system dependencies define. - -The driver is expected to maintain it's own statemachine which is -appropriate for the device it maintains. It must, at the very least -provide a load and start function. We assume here that the device -needs to be loaded and started, else, there is no real purpose of -using the remoteproc framework. - -Describing the device using platform data ------------------------------------------ - -*IMPORTANT* NOTE: THIS SUPPORT IS NOT MEANT FOR USE WITH NEWER PLATFORM -SUPPORT. THIS IS ONLY FOR LEGACY DEVICES. THIS MODE OF INITIALIZATION -*WILL* BE EVENTUALLY REMOVED ONCE ALL NECESSARY PLATFORMS HAVE MOVED -TO DM/FDT. - -Considering that many platforms are yet to move to device-tree model, -a simplified definition of a device is as follows: - -.. code-block:: c - - struct dm_rproc_uclass_pdata proc_3_test = { - .name = "proc_3_legacy", - .mem_type = RPROC_INTERNAL_MEMORY_MAPPED, - .driver_plat_data = &mydriver_data; - }; - - U_BOOT_DRVINFO(proc_3_demo) = { - .name = "sandbox_test_proc", - .plat = &proc_3_test, - }; - -There can be additional data that may be desired depending on the -remoteproc driver specific needs (for example: SoC integration -details such as clock handle or something similar). See appropriate -documentation for specific remoteproc driver for further details. -These are passed via driver_plat_data. - -Describing the device using device tree ---------------------------------------- - -.. code-block: none - - / { - ... - aliases { - ... - remoteproc0 = &rproc_1; - remoteproc1 = &rproc_2; - - }; - ... - - rproc_1: rproc@1 { - compatible = "sandbox,test-processor"; - remoteproc-name = "remoteproc-test-dev1"; - }; - - rproc_2: rproc@2 { - compatible = "sandbox,test-processor"; - internal-memory-mapped; - remoteproc-name = "remoteproc-test-dev2"; - }; - ... - }; - -aliases usage is optional, but it is usually recommended to ensure the -users have a consistent usage model for a platform. -the compatible string used here is specific to the remoteproc driver involved. diff --git a/doc/driver-model/serial-howto.rst b/doc/driver-model/serial-howto.rst deleted file mode 100644 index 1469131..0000000 --- a/doc/driver-model/serial-howto.rst +++ /dev/null @@ -1,46 +0,0 @@ -.. SPDX-License-Identifier: GPL-2.0+ - -How to port a serial driver to driver model -=========================================== - -Almost all of the serial drivers have been converted as at January 2016. These -ones remain: - - * serial_bfin.c - * serial_pxa.c - -The deadline for this work was the end of January 2016. If no one steps -forward to convert these, at some point there may come a patch to remove them! - -Here is a suggested approach for converting your serial driver over to driver -model. Please feel free to update this file with your ideas and suggestions. - -- #ifdef out all your own serial driver code (#ifndef CONFIG_DM_SERIAL) -- Define CONFIG_DM_SERIAL for your board, vendor or architecture -- If the board does not already use driver model, you need CONFIG_DM also -- Your board should then build, but will not boot since there will be no serial - driver -- Add the U_BOOT_DRIVER piece at the end (e.g. copy serial_s5p.c for example) -- Add a private struct for the driver data - avoid using static variables -- Implement each of the driver methods, perhaps by calling your old methods -- You may need to adjust the function parameters so that the old and new - implementations can share most of the existing code -- If you convert all existing users of the driver, remove the pre-driver-model - code - -In terms of patches a conversion series typically has these patches: -- clean up / prepare the driver for conversion -- add driver model code -- convert at least one existing board to use driver model serial -- (if no boards remain that don't use driver model) remove the old code - -This may be a good time to move your board to use device tree also. Mostly -this involves these steps: - -- define CONFIG_OF_CONTROL and CONFIG_OF_SEPARATE -- add your device tree files to arch/<arch>/dts -- update the Makefile there -- Add stdout-path to your /chosen device tree node if it is not already there -- build and get u-boot-dtb.bin so you can test it -- Your drivers can now use device tree -- For device tree in SPL, define CONFIG_SPL_OF_CONTROL diff --git a/doc/driver-model/soc-framework.rst b/doc/driver-model/soc-framework.rst deleted file mode 100644 index 2609fda..0000000 --- a/doc/driver-model/soc-framework.rst +++ /dev/null @@ -1,68 +0,0 @@ -.. SPDX-License-Identifier: GPL-2.0+ -.. (C) Copyright 2020 -.. Texas Instruments Incorporated - http://www.ti.com/ - -SOC ID Framework -================ - -Introduction ------------- - -The driver-model SOC ID framework is able to provide identification -information about a specific SoC in use at runtime, and also provide matching -from a set of identification information from an array. This can be useful for -enabling small quirks in drivers that exist between SoC variants that are -impractical to implement using device tree flags. It is based on UCLASS_SOC. - -UCLASS_SOC: - - drivers/soc/soc-uclass.c - - include/soc.h - -Configuration: - - CONFIG_SOC_DEVICE is selected by drivers as needed. - -Implementing a UCLASS_SOC provider ----------------------------------- - -The purpose of this framework is to allow UCLASS_SOC provider drivers to supply -identification information about the SoC in use at runtime. The framework -allows drivers to define soc_ops that return identification strings. All -soc_ops need not be defined and can be left as NULL, in which case the -framework will return -ENOSYS and not consider the value when doing an -soc_device_match. - -It is left to the driver implementor to decide how the information returned is -determined, but in general the same SOC should always return the same set of -identifying information. Information returned must be in the form of a NULL -terminated string. - -See include/soc.h for documentation of the available soc_ops and the intended -meaning of the values that can be returned. See drivers/soc/soc_sandbox.c for -an example UCLASS_SOC provider driver. - -Using a UCLASS_SOC driver -------------------------- - -The framework provides the ability to retrieve and use the identification -strings directly. It also has the ability to return a match from a list of -different sets of SoC data using soc_device_match. - -An array of 'struct soc_attr' can be defined, each containing ID information -for a specific SoC, and when passed to soc_device_match, the identifier values -for each entry in the list will be compared against the values provided by the -UCLASS_SOC driver that is in use. The first entry in the list that matches all -non-null values will be returned by soc_device_match. - -An example of various uses of the framework can be found at test/dm/soc.c. - -Describing the device using device tree ---------------------------------------- - -.. code-block:: none - - chipid: chipid { - compatible = "sandbox,soc"; - }; - -All that is required in a DT node is a compatible for a corresponding -UCLASS_SOC driver. diff --git a/doc/driver-model/spi-howto.rst b/doc/driver-model/spi-howto.rst deleted file mode 100644 index 97fbf75..0000000 --- a/doc/driver-model/spi-howto.rst +++ /dev/null @@ -1,692 +0,0 @@ -.. SPDX-License-Identifier: GPL-2.0+ - -How to port a SPI driver to driver model -======================================== - -Here is a rough step-by-step guide. It is based around converting the -exynos SPI driver to driver model (DM) and the example code is based -around U-Boot v2014.10-rc2 (commit be9f643). This has been updated for -v2015.04. - -It is quite long since it includes actual code examples. - -Before driver model, SPI drivers have their own private structure which -contains 'struct spi_slave'. With driver model, 'struct spi_slave' still -exists, but now it is 'per-child data' for the SPI bus. Each child of the -SPI bus is a SPI slave. The information that was stored in the -driver-specific slave structure can now be port in private data for the -SPI bus. - -For example, struct tegra_spi_slave looks like this: - -.. code-block:: c - - struct tegra_spi_slave { - struct spi_slave slave; - struct tegra_spi_ctrl *ctrl; - }; - -In this case 'slave' will be in per-child data, and 'ctrl' will be in the -SPI's buses private data. - - -How long does this take? ------------------------- - -You should be able to complete this within 2 hours, including testing but -excluding preparing the patches. The API is basically the same as before -with only minor changes: - -- methods to set speed and mode are separated out -- cs_info is used to get information on a chip select - - -Enable driver mode for SPI and SPI flash ----------------------------------------- - -Add these to your board config: - -* CONFIG_DM_SPI -* CONFIG_DM_SPI_FLASH - - -Add the skeleton ----------------- - -Put this code at the bottom of your existing driver file: - -.. code-block:: c - - struct spi_slave *spi_setup_slave(unsigned int busnum, unsigned int cs, - unsigned int max_hz, unsigned int mode) - { - return NULL; - } - - struct spi_slave *spi_setup_slave_fdt(const void *blob, int slave_node, - int spi_node) - { - return NULL; - } - - static int exynos_spi_of_to_plat(struct udevice *dev) - { - return -ENODEV; - } - - static int exynos_spi_probe(struct udevice *dev) - { - return -ENODEV; - } - - static int exynos_spi_remove(struct udevice *dev) - { - return -ENODEV; - } - - static int exynos_spi_claim_bus(struct udevice *dev) - { - - return -ENODEV; - } - - static int exynos_spi_release_bus(struct udevice *dev) - { - - return -ENODEV; - } - - static int exynos_spi_xfer(struct udevice *dev, unsigned int bitlen, - const void *dout, void *din, unsigned long flags) - { - - return -ENODEV; - } - - static int exynos_spi_set_speed(struct udevice *dev, uint speed) - { - return -ENODEV; - } - - static int exynos_spi_set_mode(struct udevice *dev, uint mode) - { - return -ENODEV; - } - - static int exynos_cs_info(struct udevice *bus, uint cs, - struct spi_cs_info *info) - { - return -EINVAL; - } - - static const struct dm_spi_ops exynos_spi_ops = { - .claim_bus = exynos_spi_claim_bus, - .release_bus = exynos_spi_release_bus, - .xfer = exynos_spi_xfer, - .set_speed = exynos_spi_set_speed, - .set_mode = exynos_spi_set_mode, - .cs_info = exynos_cs_info, - }; - - static const struct udevice_id exynos_spi_ids[] = { - { .compatible = "samsung,exynos-spi" }, - { } - }; - - U_BOOT_DRIVER(exynos_spi) = { - .name = "exynos_spi", - .id = UCLASS_SPI, - .of_match = exynos_spi_ids, - .ops = &exynos_spi_ops, - .of_to_plat = exynos_spi_of_to_plat, - .probe = exynos_spi_probe, - .remove = exynos_spi_remove, - }; - - -Replace 'exynos' in the above code with your driver name --------------------------------------------------------- - - -#ifdef out all of the code in your driver except for the above --------------------------------------------------------------- - -This will allow you to get it building, which means you can work -incrementally. Since all the methods return an error initially, there is -less chance that you will accidentally leave something in. - -Also, even though your conversion is basically a rewrite, it might help -reviewers if you leave functions in the same place in the file, -particularly for large drivers. - - -Add some includes ------------------ - -Add these includes to your driver: - -.. code-block:: c - - #include <dm.h> - #include <errno.h> - - -Build ------ - -At this point you should be able to build U-Boot for your board with the -empty SPI driver. You still have empty methods in your driver, but we will -write these one by one. - -Set up your platform data structure ------------------------------------ - -This will hold the information your driver to operate, like its hardware -address or maximum frequency. - -You may already have a struct like this, or you may need to create one -from some of the #defines or global variables in the driver. - -Note that this information is not the run-time information. It should not -include state that changes. It should be fixed throughout the live of -U-Boot. Run-time information comes later. - -Here is what was in the exynos spi driver: - -.. code-block:: c - - struct spi_bus { - enum periph_id periph_id; - s32 frequency; /* Default clock frequency, -1 for none */ - struct exynos_spi *regs; - int inited; /* 1 if this bus is ready for use */ - int node; - uint deactivate_delay_us; /* Delay to wait after deactivate */ - }; - -Of these, inited is handled by DM and node is the device tree node, which -DM tells you. The name is not quite right. So in this case we would use: - -.. code-block:: c - - struct exynos_spi_plat { - enum periph_id periph_id; - s32 frequency; /* Default clock frequency, -1 for none */ - struct exynos_spi *regs; - uint deactivate_delay_us; /* Delay to wait after deactivate */ - }; - - -Write of_to_plat() [for device tree only] -------------------------------------------------- - -This method will convert information in the device tree node into a C -structure in your driver (called platform data). If you are not using -device tree, go to 8b. - -DM will automatically allocate the struct for us when we are using device -tree, but we need to tell it the size: - -.. code-block:: c - - U_BOOT_DRIVER(spi_exynos) = { - ... - .plat_auto = sizeof(struct exynos_spi_plat), - - -Here is a sample function. It gets a pointer to the platform data and -fills in the fields from device tree. - -.. code-block:: c - - static int exynos_spi_of_to_plat(struct udevice *bus) - { - struct exynos_spi_plat *plat = bus->plat; - const void *blob = gd->fdt_blob; - int node = dev_of_offset(bus); - - plat->regs = (struct exynos_spi *)fdtdec_get_addr(blob, node, "reg"); - plat->periph_id = pinmux_decode_periph_id(blob, node); - - if (plat->periph_id == PERIPH_ID_NONE) { - debug("%s: Invalid peripheral ID %d\n", __func__, - plat->periph_id); - return -FDT_ERR_NOTFOUND; - } - - /* Use 500KHz as a suitable default */ - plat->frequency = fdtdec_get_int(blob, node, "spi-max-frequency", - 500000); - plat->deactivate_delay_us = fdtdec_get_int(blob, node, - "spi-deactivate-delay", 0); - debug("%s: regs=%p, periph_id=%d, max-frequency=%d, deactivate_delay=%d\n", - __func__, plat->regs, plat->periph_id, plat->frequency, - plat->deactivate_delay_us); - - return 0; - } - - -Add the platform data [non-device-tree only] --------------------------------------------- - -Specify this data in a U_BOOT_DRVINFO() declaration in your board file: - -.. code-block:: c - - struct exynos_spi_plat platdata_spi0 = { - .periph_id = ... - .frequency = ... - .regs = ... - .deactivate_delay_us = ... - }; - - U_BOOT_DRVINFO(board_spi0) = { - .name = "exynos_spi", - .plat = &platdata_spi0, - }; - -You will unfortunately need to put the struct definition into a header file -in this case so that your board file can use it. - - -Add the device private data ---------------------------- - -Most devices have some private data which they use to keep track of things -while active. This is the run-time information and needs to be stored in -a structure. There is probably a structure in the driver that includes a -'struct spi_slave', so you can use that. - -.. code-block:: c - - struct exynos_spi_slave { - struct spi_slave slave; - struct exynos_spi *regs; - unsigned int freq; /* Default frequency */ - unsigned int mode; - enum periph_id periph_id; /* Peripheral ID for this device */ - unsigned int fifo_size; - int skip_preamble; - struct spi_bus *bus; /* Pointer to our SPI bus info */ - ulong last_transaction_us; /* Time of last transaction end */ - }; - - -We should rename this to make its purpose more obvious, and get rid of -the slave structure, so we have: - -.. code-block:: c - - struct exynos_spi_priv { - struct exynos_spi *regs; - unsigned int freq; /* Default frequency */ - unsigned int mode; - enum periph_id periph_id; /* Peripheral ID for this device */ - unsigned int fifo_size; - int skip_preamble; - ulong last_transaction_us; /* Time of last transaction end */ - }; - - -DM can auto-allocate this also: - -.. code-block:: c - - U_BOOT_DRIVER(spi_exynos) = { - ... - .priv_auto = sizeof(struct exynos_spi_priv), - - -Note that this is created before the probe method is called, and destroyed -after the remove method is called. It will be zeroed when the probe -method is called. - - -Add the probe() and remove() methods ------------------------------------- - -Note: It's a good idea to build repeatedly as you are working, to avoid a -huge amount of work getting things compiling at the end. - -The probe method is supposed to set up the hardware. U-Boot used to use -spi_setup_slave() to do this. So take a look at this function and see -what you can copy out to set things up. - -.. code-block:: c - - static int exynos_spi_probe(struct udevice *bus) - { - struct exynos_spi_plat *plat = dev_get_plat(bus); - struct exynos_spi_priv *priv = dev_get_priv(bus); - - priv->regs = plat->regs; - if (plat->periph_id == PERIPH_ID_SPI1 || - plat->periph_id == PERIPH_ID_SPI2) - priv->fifo_size = 64; - else - priv->fifo_size = 256; - - priv->skip_preamble = 0; - priv->last_transaction_us = timer_get_us(); - priv->freq = plat->frequency; - priv->periph_id = plat->periph_id; - - return 0; - } - -This implementation doesn't actually touch the hardware, which is somewhat -unusual for a driver. In this case we will do that when the device is -claimed by something that wants to use the SPI bus. - -For remove we could shut down the clocks, but in this case there is -nothing to do. DM frees any memory that it allocated, so we can just -remove exynos_spi_remove() and its reference in U_BOOT_DRIVER. - - -Implement set_speed() ---------------------- - -This should set up clocks so that the SPI bus is running at the right -speed. With the old API spi_claim_bus() would normally do this and several -of the following functions, so let's look at that function: - -.. code-block:: c - - int spi_claim_bus(struct spi_slave *slave) - { - struct exynos_spi_slave *spi_slave = to_exynos_spi(slave); - struct exynos_spi *regs = spi_slave->regs; - u32 reg = 0; - int ret; - - ret = set_spi_clk(spi_slave->periph_id, - spi_slave->freq); - if (ret < 0) { - debug("%s: Failed to setup spi clock\n", __func__); - return ret; - } - - exynos_pinmux_config(spi_slave->periph_id, PINMUX_FLAG_NONE); - - spi_flush_fifo(slave); - - reg = readl(®s->ch_cfg); - reg &= ~(SPI_CH_CPHA_B | SPI_CH_CPOL_L); - - if (spi_slave->mode & SPI_CPHA) - reg |= SPI_CH_CPHA_B; - - if (spi_slave->mode & SPI_CPOL) - reg |= SPI_CH_CPOL_L; - - writel(reg, ®s->ch_cfg); - writel(SPI_FB_DELAY_180, ®s->fb_clk); - - return 0; - } - - -It sets up the speed, mode, pinmux, feedback delay and clears the FIFOs. -With DM these will happen in separate methods. - - -Here is an example for the speed part: - -.. code-block:: c - - static int exynos_spi_set_speed(struct udevice *bus, uint speed) - { - struct exynos_spi_plat *plat = bus->plat; - struct exynos_spi_priv *priv = dev_get_priv(bus); - int ret; - - if (speed > plat->frequency) - speed = plat->frequency; - ret = set_spi_clk(priv->periph_id, speed); - if (ret) - return ret; - priv->freq = speed; - debug("%s: regs=%p, speed=%d\n", __func__, priv->regs, priv->freq); - - return 0; - } - - -Implement set_mode() --------------------- - -This should adjust the SPI mode (polarity, etc.). Again this code probably -comes from the old spi_claim_bus(). Here is an example: - -.. code-block:: c - - static int exynos_spi_set_mode(struct udevice *bus, uint mode) - { - struct exynos_spi_priv *priv = dev_get_priv(bus); - uint32_t reg; - - reg = readl(&priv->regs->ch_cfg); - reg &= ~(SPI_CH_CPHA_B | SPI_CH_CPOL_L); - - if (mode & SPI_CPHA) - reg |= SPI_CH_CPHA_B; - - if (mode & SPI_CPOL) - reg |= SPI_CH_CPOL_L; - - writel(reg, &priv->regs->ch_cfg); - priv->mode = mode; - debug("%s: regs=%p, mode=%d\n", __func__, priv->regs, priv->mode); - - return 0; - } - - -Implement claim_bus() ---------------------- - -This is where a client wants to make use of the bus, so claims it first. -At this point we need to make sure everything is set up ready for data -transfer. Note that this function is wholly internal to the driver - at -present the SPI uclass never calls it. - -Here again we look at the old claim function and see some code that is -needed. It is anything unrelated to speed and mode: - -.. code-block:: c - - static int exynos_spi_claim_bus(struct udevice *bus) - { - struct exynos_spi_priv *priv = dev_get_priv(bus); - - exynos_pinmux_config(priv->periph_id, PINMUX_FLAG_NONE); - spi_flush_fifo(priv->regs); - - writel(SPI_FB_DELAY_180, &priv->regs->fb_clk); - - return 0; - } - -The spi_flush_fifo() function is in the removed part of the code, so we -need to expose it again (perhaps with an #endif before it and '#if 0' -after it). It only needs access to priv->regs which is why we have -passed that in: - -.. code-block:: c - - /** - * Flush spi tx, rx fifos and reset the SPI controller - * - * @param regs Pointer to SPI registers - */ - static void spi_flush_fifo(struct exynos_spi *regs) - { - clrsetbits_le32(®s->ch_cfg, SPI_CH_HS_EN, SPI_CH_RST); - clrbits_le32(®s->ch_cfg, SPI_CH_RST); - setbits_le32(®s->ch_cfg, SPI_TX_CH_ON | SPI_RX_CH_ON); - } - - -Implement release_bus() ------------------------ - -This releases the bus - in our example the old code in spi_release_bus() -is a call to spi_flush_fifo, so we add: - -.. code-block:: c - - static int exynos_spi_release_bus(struct udevice *bus) - { - struct exynos_spi_priv *priv = dev_get_priv(bus); - - spi_flush_fifo(priv->regs); - - return 0; - } - - -Implement xfer() ----------------- - -This is the final method that we need to create, and it is where all the -work happens. The method parameters are the same as the old spi_xfer() with -the addition of a 'struct udevice' so conversion is pretty easy. Start -by copying the contents of spi_xfer() to your new xfer() method and proceed -from there. - -If (flags & SPI_XFER_BEGIN) is non-zero then xfer() normally calls an -activate function, something like this: - -.. code-block:: c - - void spi_cs_activate(struct spi_slave *slave) - { - struct exynos_spi_slave *spi_slave = to_exynos_spi(slave); - - /* If it's too soon to do another transaction, wait */ - if (spi_slave->bus->deactivate_delay_us && - spi_slave->last_transaction_us) { - ulong delay_us; /* The delay completed so far */ - delay_us = timer_get_us() - spi_slave->last_transaction_us; - if (delay_us < spi_slave->bus->deactivate_delay_us) - udelay(spi_slave->bus->deactivate_delay_us - delay_us); - } - - clrbits_le32(&spi_slave->regs->cs_reg, SPI_SLAVE_SIG_INACT); - debug("Activate CS, bus %d\n", spi_slave->slave.bus); - spi_slave->skip_preamble = spi_slave->mode & SPI_PREAMBLE; - } - -The new version looks like this: - -.. code-block:: c - - static void spi_cs_activate(struct udevice *dev) - { - struct udevice *bus = dev->parent; - struct exynos_spi_plat *pdata = dev_get_plat(bus); - struct exynos_spi_priv *priv = dev_get_priv(bus); - - /* If it's too soon to do another transaction, wait */ - if (pdata->deactivate_delay_us && - priv->last_transaction_us) { - ulong delay_us; /* The delay completed so far */ - delay_us = timer_get_us() - priv->last_transaction_us; - if (delay_us < pdata->deactivate_delay_us) - udelay(pdata->deactivate_delay_us - delay_us); - } - - clrbits_le32(&priv->regs->cs_reg, SPI_SLAVE_SIG_INACT); - debug("Activate CS, bus '%s'\n", bus->name); - priv->skip_preamble = priv->mode & SPI_PREAMBLE; - } - -All we have really done here is change the pointers and print the device name -instead of the bus number. Other local static functions can be treated in -the same way. - - -Set up the per-child data and child pre-probe function ------------------------------------------------------- - -To minimise the pain and complexity of the SPI subsystem while the driver -model change-over is in place, struct spi_slave is used to reference a -SPI bus slave, even though that slave is actually a struct udevice. In fact -struct spi_slave is the device's child data. We need to make sure this space -is available. It is possible to allocate more space that struct spi_slave -needs, but this is the minimum. - -.. code-block:: c - - U_BOOT_DRIVER(exynos_spi) = { - ... - .per_child_auto = sizeof(struct spi_slave), - } - - -Optional: Set up cs_info() if you want it ------------------------------------------ - -Sometimes it is useful to know whether a SPI chip select is valid, but this -is not obvious from outside the driver. In this case you can provide a -method for cs_info() to deal with this. If you don't provide it, then the -device tree will be used to determine what chip selects are valid. - -Return -EINVAL if the supplied chip select is invalid, or 0 if it is valid. -If you don't provide the cs_info() method, 0 is assumed for all chip selects -that do not appear in the device tree. - - -Test it -------- - -Now that you have the code written and it compiles, try testing it using -the 'sf test' command. You may need to enable CONFIG_CMD_SF_TEST for your -board. - - -Prepare patches and send them to the mailing lists --------------------------------------------------- - -You can use 'tools/patman/patman' to prepare, check and send patches for -your work. See tools/patman/README for details. - -A little note about SPI uclass features ---------------------------------------- - -The SPI uclass keeps some information about each device 'dev' on the bus: - - struct dm_spi_slave_plat: - This is device_get_parent_plat(dev). - This is where the chip select number is stored, along with - the default bus speed and mode. It is automatically read - from the device tree in spi_child_post_bind(). It must not - be changed at run-time after being set up because platform - data is supposed to be immutable at run-time. - struct spi_slave: - This is device_get_parentdata(dev). - Already mentioned above. It holds run-time information about - the device. - -There are also some SPI uclass methods that get called behind the scenes: - - spi_post_bind(): - Called when a new bus is bound. - This scans the device tree for devices on the bus, and binds - each one. This in turn causes spi_child_post_bind() to be - called for each, which reads the device tree information - into the parent (per-child) platform data. - spi_child_post_bind(): - Called when a new child is bound. - As mentioned above this reads the device tree information - into the per-child platform data - spi_child_pre_probe(): - Called before a new child is probed. - This sets up the mode and speed in struct spi_slave by - copying it from the parent's platform data for this child. - It also sets the 'dev' pointer, needed to permit passing - 'struct spi_slave' around the place without needing a - separate 'struct udevice' pointer. - -The above housekeeping makes it easier to write your SPI driver. diff --git a/doc/driver-model/usb-info.rst b/doc/driver-model/usb-info.rst deleted file mode 100644 index 24d1e81..0000000 --- a/doc/driver-model/usb-info.rst +++ /dev/null @@ -1,423 +0,0 @@ -.. SPDX-License-Identifier: GPL-2.0+ - -How USB works with driver model -=============================== - -Introduction ------------- - -Driver model USB support makes use of existing features but changes how -drivers are found. This document provides some information intended to help -understand how things work with USB in U-Boot when driver model is enabled. - - -Enabling driver model for USB ------------------------------ - -A new CONFIG_DM_USB option is provided to enable driver model for USB. This -causes the USB uclass to be included, and drops the equivalent code in -usb.c. In particular the usb_init() function is then implemented by the -uclass. - - -Support for EHCI and XHCI -------------------------- - -So far OHCI is not supported. Both EHCI and XHCI drivers should be declared -as drivers in the USB uclass. For example: - -.. code-block:: c - - static const struct udevice_id ehci_usb_ids[] = { - { .compatible = "nvidia,tegra20-ehci", .data = USB_CTLR_T20 }, - { .compatible = "nvidia,tegra30-ehci", .data = USB_CTLR_T30 }, - { .compatible = "nvidia,tegra114-ehci", .data = USB_CTLR_T114 }, - { } - }; - - U_BOOT_DRIVER(usb_ehci) = { - .name = "ehci_tegra", - .id = UCLASS_USB, - .of_match = ehci_usb_ids, - .of_to_plat = ehci_usb_of_to_plat, - .probe = tegra_ehci_usb_probe, - .remove = tegra_ehci_usb_remove, - .ops = &ehci_usb_ops, - .plat_auto = sizeof(struct usb_plat), - .priv_auto = sizeof(struct fdt_usb), - .flags = DM_FLAG_ALLOC_PRIV_DMA, - }; - -Here ehci_usb_ids is used to list the controllers that the driver supports. -Each has its own data value. Controllers must be in the UCLASS_USB uclass. - -The of_to_plat() method allows the controller driver to grab any -necessary settings from the device tree. - -The ops here are ehci_usb_ops. All EHCI drivers will use these same ops in -most cases, since they are all EHCI-compatible. For EHCI there are also some -special operations that can be overridden when calling ehci_register(). - -The driver can use priv_auto to set the size of its private data. -This can hold run-time information needed by the driver for operation. It -exists when the device is probed (not when it is bound) and is removed when -the driver is removed. - -Note that usb_plat is currently only used to deal with setting up a bus -in USB device mode (OTG operation). It can be omitted if that is not -supported. - -The driver's probe() method should do the basic controller init and then -call ehci_register() to register itself as an EHCI device. It should call -ehci_deregister() in the remove() method. Registering a new EHCI device -does not by itself cause the bus to be scanned. - -The old ehci_hcd_init() function is no-longer used. Nor is it necessary to -set up the USB controllers from board init code. When 'usb start' is used, -each controller will be probed and its bus scanned. - -XHCI works in a similar way. - - -Data structures ---------------- - -The following primary data structures are in use: - -- struct usb_device: - This holds information about a device on the bus. All devices have - this structure, even the root hub. The controller itself does not - have this structure. You can access it for a device 'dev' with - dev_get_parent_priv(dev). It matches the old structure except that the - parent and child information is not present (since driver model - handles that). Once the device is set up, you can find the device - descriptor and current configuration descriptor in this structure. - -- struct usb_plat: - This holds platform data for a controller. So far this is only used - as a work-around for controllers which can act as USB devices in OTG - mode, since the gadget framework does not use driver model. - -- struct usb_dev_plat: - This holds platform data for a device. You can access it for a - device 'dev' with dev_get_parent_plat(dev). It holds the device - address and speed - anything that can be determined before the device - driver is actually set up. When probing the bus this structure is - used to provide essential information to the device driver. - -- struct usb_bus_priv: - This is private information for each controller, maintained by the - controller uclass. It is mostly used to keep track of the next - device address to use. - -Of these, only struct usb_device was used prior to driver model. - - -USB buses ---------- - -Given a controller, you know the bus - it is the one attached to the -controller. Each controller handles exactly one bus. Every controller has a -root hub attached to it. This hub, which is itself a USB device, can provide -one or more 'ports' to which additional devices can be attached. It is -possible to power up a hub and find out which of its ports have devices -attached. - -Devices are given addresses starting at 1. The root hub is always address 1, -and from there the devices are numbered in sequence. The USB uclass takes -care of this numbering automatically during enumeration. - -USB devices are enumerated by finding a device on a particular hub, and -setting its address to the next available address. The USB bus stretches out -in a tree structure, potentially with multiple hubs each with several ports -and perhaps other hubs. Some hubs will have their own power since otherwise -the 5V 500mA power supplied by the controller will not be sufficient to run -very many devices. - -Enumeration in U-Boot takes a long time since devices are probed one at a -time, and each is given sufficient time to wake up and announce itself. The -timeouts are set for the slowest device. - -Up to 127 devices can be on each bus. USB has four bus speeds: low -(1.5Mbps), full (12Mbps), high (480Mbps) which is only available with USB2 -and newer (EHCI), and super (5Gbps) which is only available with USB3 and -newer (XHCI). If you connect a super-speed device to a high-speed hub, you -will only get high-speed. - - -USB operations --------------- - -As before driver model, messages can be sent using submit_bulk_msg() and the -like. These are now implemented by the USB uclass and route through the -controller drivers. Note that messages are not sent to the driver of the -device itself - i.e. they don't pass down the stack to the controller. -U-Boot simply finds the controller to which the device is attached, and sends -the message there with an appropriate 'pipe' value so it can be addressed -properly. Having said that, the USB device which should receive the message -is passed in to the driver methods, for use by sandbox. This design decision -is open for review and the code impact of changing it is small since the -methods are typically implemented by the EHCI and XHCI stacks. - -Controller drivers (in UCLASS_USB) themselves provide methods for sending -each message type. For XHCI an additional alloc_device() method is provided -since XHCI needs to allocate a device context before it can even read the -device's descriptor. - -These methods use a 'pipe' which is a collection of bit fields used to -describe the type of message, direction of transfer and the intended -recipient (device number). - - -USB Devices ------------ - -USB devices are found using a simple algorithm which works through the -available hubs in a depth-first search. Devices can be in any uclass, but -are attached to a parent hub (or controller in the case of the root hub) and -so have parent data attached to them (this is struct usb_device). - -By the time the device's probe() method is called, it is enumerated and is -ready to talk to the host. - -The enumeration process needs to work out which driver to attach to each USB -device. It does this by examining the device class, interface class, vendor -ID, product ID, etc. See struct usb_driver_entry for how drivers are matched -with USB devices - you can use the USB_DEVICE() macro to declare a USB -driver. For example, usb_storage.c defines a USB_DEVICE() to handle storage -devices, and it will be used for all USB devices which match. - - - -Technical details on enumeration flow -------------------------------------- - -It is useful to understand precisely how a USB bus is enumerating to avoid -confusion when dealing with USB devices. - -Device initialisation happens roughly like this: - -- At some point the 'usb start' command is run -- This calls usb_init() which works through each controller in turn -- The controller is probed(). This does no enumeration. -- Then usb_scan_bus() is called. This calls usb_scan_device() to scan the - (only) device that is attached to the controller - a root hub -- usb_scan_device() sets up a fake struct usb_device and calls - usb_setup_device(), passing the port number to be scanned, in this case - port 0 -- usb_setup_device() first calls usb_prepare_device() to set the device - address, then usb_select_config() to select the first configuration -- at this point the device is enumerated but we do not have a real struct - udevice for it. But we do have the descriptor in struct usb_device so we can - use this to figure out what driver to use -- back in usb_scan_device(), we call usb_find_child() to try to find an - existing device which matches the one we just found on the bus. This can - happen if the device is mentioned in the device tree, or if we previously - scanned the bus and so the device was created before -- if usb_find_child() does not find an existing device, we call - usb_find_and_bind_driver() which tries to bind one -- usb_find_and_bind_driver() searches all available USB drivers (declared - with USB_DEVICE()). If it finds a match it binds that driver to create a - new device. -- If it does not, it binds a generic driver. A generic driver is good enough - to allow access to the device (sending it packets, etc.) but all - functionality will need to be implemented outside the driver model. -- in any case, when usb_find_child() and/or usb_find_and_bind_driver() are - done, we have a device with the correct uclass. At this point we want to - probe the device -- first we store basic information about the new device (address, port, - speed) in its parent platform data. We cannot store it its private data - since that will not exist until the device is probed. -- then we call device_probe() which probes the device -- the first probe step is actually the USB controller's (or USB hubs's) - child_pre_probe() method. This gets called before anything else and is - intended to set up a child device ready to be used with its parent bus. For - USB this calls usb_child_pre_probe() which grabs the information that was - stored in the parent platform data and stores it in the parent private data - (which is struct usb_device, a real one this time). It then calls - usb_select_config() again to make sure that everything about the device is - set up -- note that we have called usb_select_config() twice. This is inefficient - but the alternative is to store additional information in the platform data. - The time taken is minimal and this way is simpler -- at this point the device is set up and ready for use so far as the USB - subsystem is concerned -- the device's probe() method is then called. It can send messages and do - whatever else it wants to make the device work. - -Note that the first device is always a root hub, and this must be scanned to -find any devices. The above steps will have created a hub (UCLASS_USB_HUB), -given it address 1 and set the configuration. - -For hubs, the hub uclass has a post_probe() method. This means that after -any hub is probed, the uclass gets to do some processing. In this case -usb_hub_post_probe() is called, and the following steps take place: - -- usb_hub_post_probe() calls usb_hub_scan() to scan the hub, which in turn - calls usb_hub_configure() -- hub power is enabled -- we loop through each port on the hub, performing the same steps for each -- first, check if there is a device present. This happens in - usb_hub_port_connect_change(). If so, then usb_scan_device() is called to - scan the device, passing the appropriate port number. -- you will recognise usb_scan_device() from the steps above. It sets up the - device ready for use. If it is a hub, it will scan that hub before it - continues here (recursively, depth-first) -- once all hub ports are scanned in this way, the hub is ready for use and - all of its downstream devices also -- additional controllers are scanned in the same way - -The above method has some nice properties: - -- the bus enumeration happens by virtue of driver model's natural device flow -- most logic is in the USB controller and hub uclasses; the actual device - drivers do not need to know they are on a USB bus, at least so far as - enumeration goes -- hub scanning happens automatically after a hub is probed - - -Hubs ----- - -USB hubs are scanned as in the section above. While hubs have their own -uclass, they share some common elements with controllers: - -- they both attach private data to their children (struct usb_device, - accessible for a child with dev_get_parent_priv(child)) -- they both use usb_child_pre_probe() to set up their children as proper USB - devices - - -Example - Mass Storage ----------------------- - -As an example of a USB device driver, see usb_storage.c. It uses its own -uclass and declares itself as follows: - -.. code-block:: c - - U_BOOT_DRIVER(usb_mass_storage) = { - .name = "usb_mass_storage", - .id = UCLASS_MASS_STORAGE, - .of_match = usb_mass_storage_ids, - .probe = usb_mass_storage_probe, - }; - - static const struct usb_device_id mass_storage_id_table[] = { - { .match_flags = USB_DEVICE_ID_MATCH_INT_CLASS, - .bInterfaceClass = USB_CLASS_MASS_STORAGE}, - { } /* Terminating entry */ - }; - - USB_DEVICE(usb_mass_storage, mass_storage_id_table); - -The USB_DEVICE() macro attaches the given table of matching information to -the given driver. Note that the driver is declared in U_BOOT_DRIVER() as -'usb_mass_storage' and this must match the first parameter of USB_DEVICE. - -When usb_find_and_bind_driver() is called on a USB device with the -bInterfaceClass value of USB_CLASS_MASS_STORAGE, it will automatically find -this driver and use it. - - -Counter-example: USB Ethernet ------------------------------ - -As an example of the old way of doing things, see usb_ether.c. When the bus -is scanned, all Ethernet devices will be created as generic USB devices (in -uclass UCLASS_USB_DEV_GENERIC). Then, when the scan is completed, -usb_host_eth_scan() will be called. This looks through all the devices on -each bus and manually figures out which are Ethernet devices in the ways of -yore. - -In fact, usb_ether should be moved to driver model. Each USB Ethernet driver -(e.g drivers/usb/eth/asix.c) should include a USB_DEVICE() declaration, so -that it will be found as part of normal USB enumeration. Then, instead of a -generic USB driver, a real (driver-model-aware) driver will be used. Since -Ethernet now supports driver model, this should be fairly easy to achieve, -and then usb_ether.c and the usb_host_eth_scan() will melt away. - - -Sandbox -------- - -All driver model uclasses must have tests and USB is no exception. To -achieve this, a sandbox USB controller is provided. This can make use of -emulation drivers which pretend to be USB devices. Emulations are provided -for a hub and a flash stick. These are enough to create a pretend USB bus -(defined by the sandbox device tree sandbox.dts) which can be scanned and -used. - -Tests in test/dm/usb.c make use of this feature. It allows much of the USB -stack to be tested without real hardware being needed. - -Here is an example device tree fragment: - -.. code-block:: none - - usb@1 { - compatible = "sandbox,usb"; - hub { - compatible = "usb-hub"; - usb,device-class = <USB_CLASS_HUB>; - hub-emul { - compatible = "sandbox,usb-hub"; - #address-cells = <1>; - #size-cells = <0>; - flash-stick { - reg = <0>; - compatible = "sandbox,usb-flash"; - sandbox,filepath = "flash.bin"; - }; - }; - }; - }; - -This defines a single controller, containing a root hub (which is required). -The hub is emulated by a hub emulator, and the emulated hub has a single -flash stick to emulate on one of its ports. - -When 'usb start' is used, the following 'dm tree' output will be available:: - - usb [ + ] `-- usb@1 - usb_hub [ + ] `-- hub - usb_emul [ + ] |-- hub-emul - usb_emul [ + ] | `-- flash-stick - usb_mass_st [ + ] `-- usb_mass_storage - - -This may look confusing. Most of it mirrors the device tree, but the -'usb_mass_storage' device is not in the device tree. This is created by -usb_find_and_bind_driver() based on the USB_DRIVER in usb_storage.c. While -'flash-stick' is the emulation device, 'usb_mass_storage' is the real U-Boot -USB device driver that talks to it. - - -Future work ------------ - -It is pretty uncommon to have a large USB bus with lots of hubs on an -embedded system. In fact anything other than a root hub is uncommon. Still -it would be possible to speed up enumeration in two ways: - -- breadth-first search would allow devices to be reset and probed in - parallel to some extent -- enumeration could be lazy, in the sense that we could enumerate just the - root hub at first, then only progress to the next 'level' when a device is - used that we cannot find. This could be made easier if the devices were - statically declared in the device tree (which is acceptable for production - boards where the same, known, things are on each bus). - -But in common cases the current algorithm is sufficient. - -Other things that need doing: -- Convert usb_ether to use driver model as described above -- Test that keyboards work (and convert to driver model) -- Move the USB gadget framework to driver model -- Implement OHCI in driver model -- Implement USB PHYs in driver model -- Work out a clever way to provide lazy init for USB devices - - -.. Simon Glass <sjg@chromium.org> -.. 23-Mar-15 |