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GPIO drivers want to be able to show if a pin is enabled for input, output,
or is being used by another function. Some drivers can easily find this
and the code is included in the driver. For some SoCs this is more complex.
Conceptually this should be handled by pinctrl rather than GPIO. Most
pinctrl drivers will have this feature anyway.
Add a method by which a GPIO driver can obtain the pin mux value given a
GPIO reference. This avoids repeating the code in two places.
Signed-off-by: Simon Glass <sjg@chromium.org>
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Add a function which produces a flags word from a few common PIN_CONFIG
settings. This is useful for simple pinctrl drivers that don't need to worry
about drive strength, etc.
Signed-off-by: Simon Glass <sjg@chromium.org>
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My original pinctrl patch operating using a peripheral ID enum. This was
shared between pinmux and clock and provides an easy way to specify a device
that needs to be controlled, even it is does not (yet) have a driver within
driver model.
Masahiro's new simple pinctrl gets around this by providing a
set_state_simple() pinctrl method. By passing a device to that call the
peripheral ID becomes unnecessary. If the driver needs it, it can calculate
it itself and use it internally.
However this does not solve the problem for peripheral clocks. The 'pure'
solution would be to pass a driver to the clock uclass also. But this
requires that all devices should have a driver, and a struct udevide. Also
a key optimisation of the clock uclass is allowing a peripheral clock to
be set even when there is no device for that clock.
There may be a better way to achive the same goal, but for now it seems
expedient to add in peripheral ID to the pinctrl uclass. Two methods are
added - one to get the peripheral ID and one to select it. The existing
set_state_simple() is effectively the union of these.
Signed-off-by: Simon Glass <sjg@chromium.org>
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This creates a new framework for handling of pin control devices,
i.e. devices that control different aspects of package pins.
This uclass handles pinmuxing and pin configuration; pinmuxing
controls switching among silicon blocks that share certain physical
pins, pin configuration handles electronic properties such as pin-
biasing, load capacitance etc.
This framework can support the same device tree bindings, but if you
do not need full interface support, you can disable some features to
reduce memory foot print. Typically around 1.5KB is necessary to
include full-featured uclass support on ARM board (CONFIG_PINCTRL +
CONFIG_PINCTRL_FULL + CONFIG_PINCTRL_GENERIC + CONFIG_PINCTRL_PINMUX),
for example.
We are often limited on code size for SPL. Besides, we still have
many boards that do not support device tree configuration. The full
pinctrl, which requires OF_CONTROL, does not make sense for those
boards. So, this framework also has a Do-It-Yourself (let's say
simple pinctrl) interface. With CONFIG_PINCTRL_FULL disabled, the
uclass itself provides no systematic mechanism for identifying the
peripheral device, applying pinctrl settings, etc. They must be
done in each low-level driver. In return, you can save much memory
footprint and it might be useful especially for SPL.
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Acked-by: Simon Glass <sjg@chromium.org>
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