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authorPeter Maydell <peter.maydell@linaro.org>2022-02-08 15:59:10 +0000
committerPeter Maydell <peter.maydell@linaro.org>2022-02-21 13:30:20 +0000
commitb5bf5a53d1e02eb0c7fdc6271e10ebd0eda79813 (patch)
treeabe3652f5e015ed5ada772d544ad825bfc588752 /docs
parent92d6528dbb20c6aec4022dfd63c7ffee44f19f77 (diff)
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Kconfig: Add I2C_DEVICES device group
Currently there is no way for a board model's Kconfig stanza to say "I have an i2c bus which the user can plug an i2c device into, build all the free-standing i2c devices". The Kconfig mechanism for this is the "device group". Add an I2C_DEVICES group along the same lines as the existing PCI_DEVICES. Simple free-standing i2c devices which a user might plausibly want to be able to plug in on the QEMU commandline should have default y if I2C_DEVICES and board models which have an i2c bus that is user-accessible should use imply I2C_DEVICES to cause those pluggable devices to be built. In this commit we mark only a fairly conservative set of i2c devices as belonging to the I2C_DEVICES group: the simple sensors and RTCs (not including PMBus devices or devices which need GPIO lines to be connected). Signed-off-by: Peter Maydell <peter.maydell@linaro.org> Acked-by: Paolo Bonzini <pbonzini@redhat.com> Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org> Reviewed-by: Hao Wu <wuhaotsh@google.com> Message-id: 20220208155911.3408455-2-peter.maydell@linaro.org
Diffstat (limited to 'docs')
-rw-r--r--docs/devel/kconfig.rst8
1 files changed, 6 insertions, 2 deletions
diff --git a/docs/devel/kconfig.rst b/docs/devel/kconfig.rst
index a1cdbec..aa5042f 100644
--- a/docs/devel/kconfig.rst
+++ b/docs/devel/kconfig.rst
@@ -192,11 +192,15 @@ declares its dependencies in different ways:
no directive and are not used in the Makefile either; they only appear
as conditions for ``default y`` directives.
- QEMU currently has two device groups, ``PCI_DEVICES`` and
- ``TEST_DEVICES``. PCI devices usually have a ``default y if
+ QEMU currently has three device groups, ``PCI_DEVICES``, ``I2C_DEVICES``,
+ and ``TEST_DEVICES``. PCI devices usually have a ``default y if
PCI_DEVICES`` directive rather than just ``default y``. This lets
some boards (notably s390) easily support a subset of PCI devices,
for example only VFIO (passthrough) and virtio-pci devices.
+ ``I2C_DEVICES`` is similar to ``PCI_DEVICES``. It contains i2c devices
+ that users might reasonably want to plug in to an i2c bus on any
+ board (and not ones which are very board-specific or that need
+ to be wired up in a way that can't be done on the command line).
``TEST_DEVICES`` instead is used for devices that are rarely used on
production virtual machines, but provide useful hooks to test QEMU
or KVM.