gpio: Add GPIO Aggregator
GPIO controllers are exported to userspace using /dev/gpiochip*
character devices. Access control to these devices is provided by
standard UNIX file system permissions, on an all-or-nothing basis:
either a GPIO controller is accessible for a user, or it is not.
Currently no mechanism exists to control access to individual GPIOs.
Hence add a GPIO driver to aggregate existing GPIOs, and expose them as
a new gpiochip.
This supports the following use cases:
- Aggregating GPIOs using Sysfs
This is useful for implementing access control, and assigning a set
of GPIOs to a specific user or virtual machine.
- Generic GPIO Driver
This is useful for industrial control, where it can provide
userspace access to a simple GPIO-operated device described in DT,
cfr. e.g. spidev for SPI-operated devices.
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Tested-by: Eugeniu Rosca <erosca@de.adit-jv.com>
Reviewed-by: Eugeniu Rosca <erosca@de.adit-jv.com>
Link: https://lore.kernel.org/r/20200511145257.22970-5-geert+renesas@glider.be
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
diff --git a/drivers/gpio/Kconfig b/drivers/gpio/Kconfig
index 1b96169..cf45dfa 100644
--- a/drivers/gpio/Kconfig
+++ b/drivers/gpio/Kconfig
@@ -1541,6 +1541,18 @@
endmenu
+config GPIO_AGGREGATOR
+ tristate "GPIO Aggregator"
+ help
+ Say yes here to enable the GPIO Aggregator, which provides a way to
+ aggregate existing GPIO lines into a new virtual GPIO chip.
+ This can serve the following purposes:
+ - Assign permissions for a collection of GPIO lines to a user,
+ - Export a collection of GPIO lines to a virtual machine,
+ - Provide a generic driver for a GPIO-operated device in an
+ industrial control context, to be operated from userspace using
+ the GPIO chardev interface.
+
config GPIO_MOCKUP
tristate "GPIO Testing Driver"
select IRQ_SIM