doc: ti: add the K3 generation page

Texas Instrument's entire K3 generation of SoCs use much of the same
frameworks and boot flow, especially at the uboot level. Though there
are small differences introduced as each new K3 based SoC is developed
and as the K3 generation matures that will also need to be documented.

Rather than copying the same documentation, with the small differences
applicable to that specific SoC to a new page, introduce a new K3
page that can describe the general boot flow and design decisions for
the entire K3 generation of chips, leaving the specifics for that
particular SoC to a unique sub-page below this one.

Signed-off-by: Bryan Brattlof <bb@ti.com>
Signed-off-by: Heinrich Schuchardt <heinrich.schuchardt@canonical.com>

2 files changed, 276 insertions, 3 deletions

diff --git a/doc/board/ti/index.rst b/doc/board/ti/index.rst
index 250d924..89d537d 100644
--- a/doc/board/ti/index.rst
+++ b/doc/board/ti/index.rst
@@ -1,11 +1,10 @@
 .. SPDX-License-Identifier: GPL-2.0+
 
 Texas Instruments
-=================
+#################
 
 .. toctree::
    :maxdepth: 2
 
    am335x_evm
-   j721e_evm
-   am62x_sk
+   k3
diff --git a/doc/board/ti/k3.rst b/doc/board/ti/k3.rst
new file mode 100644
index 0000000..b49a60c
--- /dev/null
+++ b/doc/board/ti/k3.rst
@@ -0,0 +1,274 @@
+.. SPDX-License-Identifier: GPL-2.0+ OR BSD-3-Clause
+.. sectionauthor:: Bryan Brattlof <bb@ti.com>
+
+K3 Generation
+=============
+
+Summary
+-------
+
+Texas Instrument's K3 family of SoCs utilize a heterogeneous multicore
+and highly integrated device architecture targeted to maximize
+performance and power efficiency for a wide range of industrial,
+automotive and other broad market segments.
+
+Typically the processing cores and the peripherals for these devices are
+partitioned into three functional domains to provide ultra-low power
+modes as well as accommodating application and industrial safety systems
+on the same SoC.  These functional domains are typically called the:
+
+* Wakeup (WKUP) domain
+* Micro-controller (MCU) domain
+* Main domain
+
+For a more detailed view of what peripherals are attached to each
+domain, consult the device specific documentation.
+
+K3 Based SoCs
+-------------
+
+.. toctree::
+   :maxdepth: 1
+
+   j721e_evm
+   am62x_sk
+
+Boot Flow Overview
+------------------
+
+For all K3 SoCs the first core started will be inside the Security
+Management Subsystem (SMS) which will secure the device and start a core
+in the wakeup domain to run the ROM code. ROM will then initialize the
+boot media needed to load the binaries packaged inside `tiboot3.bin`,
+including a 32bit U-Boot SPL, (called the wakup SPL) that ROM will jump
+to after it has finished loading everything into internal SRAM.
+
+.. code-block:: text
+
+   |  WKUP Domain
+    ROM -> WKUP SPL ->
+
+The wakeup SPL, running on a wakeup domain core, will initialize DDR and
+any peripherals needed load the larger binaries inside the `tispl.bin`
+into DDR.  Once loaded the wakeup SPL will start one of the 'big'
+application cores inside the main domain to initialize the main domain,
+starting with ARM Trusted Firmware (ATF), before moving on to start
+OPTEE and the main domain's U-Boot SPL.
+
+.. code-block:: text
+
+   |  WKUP Domain   | Main Domain ->
+    ROM -> WKUP SPL -> ATF -> OPTEE -> Main SPL
+
+The main domain's SPL, running on a 64bit application core, has
+virtually unlimited space (billions of bytes now that DDR is working) to
+initialize even more peripherals needed to load in the `u-boot.img`
+which loads more firmware into the micro-controller & wakeup domains and
+finally prepare the main domain to run Linux.
+
+.. code-block:: text
+
+   |  WKUP Domain   | Main Domain ->
+    ROM -> WKUP SPL -> ATF -> OPTEE -> Main SPL -> UBoot -> Linux
+
+This is the typical boot flow for all K3 based SoCs, however this flow
+offers quite a lot in the terms of flexibility, especially on High
+Security (HS) SoCs.
+
+Boot Flow Variations
+^^^^^^^^^^^^^^^^^^^^
+
+All K3 SoCs will generally use the above boot flow with two main
+differences depending on the capabilities of the boot ROM and the number
+of cores inside the device. These differences split the bootflow into
+essentially 4 unique but very similar flows:
+
+* Split binary with a combined firmware: (eg: AM65)
+* Combined binary with a combined firmware: (eg: AM64)
+* Split binary with a split firmware: (eg: J721E)
+* Combined binary with a split firmware: (eg: AM62)
+
+For devices that utilize the split binary approach, ROM is not capable
+of loading the firmware into the SoC requiring the wakeup domain's
+U-Boot SPL to load the firmware.
+
+Devices with a split firmware will have two firmwares loaded into the
+device at different times during the bootup process. TI's Foundational
+Security (TIFS), needed to operate the Security Management Subsystem,
+will either be loaded by ROM or the WKUP U-Boot SPL, then once the
+wakeup U-Boot SPL has completed, the second Device Management (DM)
+firmware can be loaded on the now free core in the wakeup domain.
+
+For more information on the bootup process of your SoC, consult the
+device specific boot flow documentation.
+
+Software Sources
+----------------
+
+All scripts and code needed to build the `tiboot3.bin`, `tispl.bin` and
+`u-boot.img` for all K3 SoCs can be located at the following places
+online
+
+* **Das U-Boot**
+
+  | **source:** https://source.denx.de/u-boot/u-boot.git
+  | **branch:** master
+
+* **K3 Image Gen**
+
+  | **source:** https://git.ti.com/git/k3-image-gen/k3-image-gen.git
+  | **branch:** master
+
+* **ARM Trusted Firmware (ATF)**
+
+  | **source:** https://github.com/ARM-software/arm-trusted-firmware.git
+  | **branch:** master
+
+* **Open Portable Trusted Execution Environment (OPTEE)**
+
+  | **source:** https://github.com/OP-TEE/optee_os.git
+  | **branch:** master
+
+* **TI Firmware (TIFS, DM, DSMC)**
+
+  | **source:** https://git.ti.com/git/processor-firmware/ti-linux-firmware.git
+  | **branch:** ti-linux-firmware
+
+* **TI's Security Development Tools**
+
+  | **source:** https://git.ti.com/git/security-development-tools/core-secdev-k3.git
+  | **branch:** master
+
+Build Procedure
+---------------
+
+Depending on the specifics of your device, you will need three or more
+binaries to boot your SoC.
+
+* `tiboot3.bin` (bootloader for the wakeup domain)
+* `tispl.bin` (bootloader for the main domain)
+* `u-boot.img`
+
+During the bootup process, both the 32bit wakeup domain and the 64bit
+main domains will be involved. This means everything inside the
+`tiboot3.bin` running in the wakeup domain will need to be compiled for
+32bit cores and most binaries in the `tispl.bin` will need to be
+compiled for 64bit main domain CPU cores.
+
+All of that to say you will need both a 32bit and 64bit cross compiler
+(assuming you're using an x86 desktop)
+
+.. code-block:: bash
+
+   export CC32=arm-linux-gnueabihf-
+   export CC64=aarch64-linux-gnu-
+
+Building tiboot3.bin
+^^^^^^^^^^^^^^^^^^^^^
+
+1. To generate the U-Boot SPL for the wakeup domain, use the following
+   commands, substituting :code:`{SOC}` for the name of your device (eg:
+   am62x)
+
+.. code-block:: bash
+
+   # inside u-boot source
+   make ARCH=arm O=build/wkup CROSS_COMPILE=$CC32 {SOC}_evm_r5_defconfig
+   make ARCH=arm O=build/wkup CROSS_COMPILE=$CC32
+
+2. Next we will use the K3 Image Gen scripts to package the various
+   firmware and the wakeup UBoot SPL into the final `tiboot3.bin`
+   binary. (or the `sysfw.itb` if your device uses the split binary
+   flow)
+
+.. code-block:: bash
+
+   # inside k3-image-gen source
+   make CROSS_COMPILE=$CC32 SOC={SOC} SOC_TYPE={hs,gp} \
+        TI_SECURE_DEV_PKG=<path/to/securit-development-tools> \
+        SYSFW_PATH=<path/to/ti-sysfw/ti-fs-firmware-{SOC}-{hs|gp}.bin> \
+        SYSFW_HS_INNER_CERT_PATH=<path/to/ti-sysfw/ti-fs-firmware-{SOC}-hs-cert.bin
+
+For devices that use the *combined binary flow*, you will also need to
+supply the location of the SPL we created in step 1 above, so it can be
+packaged into the final `tiboot3.bin`.
+
+.. code-block:: bash
+
+   SBL=<path/to/wakeup/u-boot-spl.bin>
+
+At this point you should have all the needed binaries to boot the wakeup
+domain of your K3 SoC.
+
+**Combined Binary Boot Flow** (eg: am62x, am64x, ... )
+
+   `k3-image-gen/tiboot3-{SOC}-{hs,gp}-evm.bin`
+
+**Split Binary Boot Flow** (eg: j721e, am65x)
+
+   | `u-boot/build/wkup/tiboot3.bin`
+   | `k3-image-gen/sysfw-{SOC}-evm.bin`
+
+.. note ::
+
+   It's important to rename the generated `tiboot3.bin` and `sysfw.itb`
+   to match exactly `tiboot3.bin` and `sysfw.itb` as ROM and the wakeup
+   UBoot SPL will only look for and load the files with these names.
+
+Building tispl.bin
+^^^^^^^^^^^^^^^^^^^
+
+The `tispl.bin` is a standard fitImage combining the firmware need for
+the main domain to function properly as well as Device Management (DM)
+firmware if your device using a split firmware.
+
+3. We will first need ATF, as it's the first thing to run on the 'big'
+   application cores on the main domain.
+
+.. code-block:: bash
+
+   # inside arm-trusted-firmware source
+   make CROSS_COMPILE=$CC64 ARCH=aarch64 PLAT=k3 \
+        TARGET_BOARD={lite|generic} \
+        SPD=opteed \
+
+Typically all `j7*` devices will use `TARGET_BOARD=generic` while all
+Sitara (`am6*`) devices use the `lite` option.
+
+4. The Open Portable Trusted Execution Environment (OPTEE) is designed
+   to run as a companion to a non-secure Linux kernel for Cortex-A cores
+   using the TrustZone technology built into the core.
+
+.. code-block:: bash
+
+   # inside optee_os source
+   make CROSS_COMPILE=$CC32 CROSS_COMPILE64=$CC64 \
+        PLATFORM=k3 CFG_ARM64_core=y
+
+5. Finally, after ATF has initialized the main domain and OPTEE has
+   finished, we can jump back into U-Boot again, this time running on a
+   64bit core in the main domain.
+
+.. code-block:: bash
+
+   # inside u-boot source
+   make ARCH=arm O=build/main CROSS_COMPILE=$CC64 {SOC}_evm_a{53,72}_defconfig
+   make ARCH=arm O=build/main CROSS_COMPILE=$CC64 \
+        ATF=<path/to/atf/bl31.bin \
+        TEE=<path/to/optee/tee-pager_v2.bin
+
+If your device uses a split firmware, you will also need to supply the
+path to the Device Management (DM) Firmware to be included in the final
+`tispl.bin` binary
+
+.. code-block:: bash
+
+   DM=<path/to/ti-linux-firmware/ti-dm/ipc_echo_testb_mcu1_0_release_strip.xer5f>
+
+At this point you should have every binary needed initialize both the
+wakeup and main domain and to boot to the U-Boot prompt
+
+**Main Domain Bootloader**
+
+   | `u-boot/build/main/tispl.bin`
+   | `u-boot/build/main/u-boot.img`