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Commit 40c159b7 authored by Linus Walleij's avatar Linus Walleij
Browse files

gpio: add a userspace character device ABI



Put in some documentation for the new character device ABI
so we can properly etch it in stone.

Signed-off-by: default avatarLinus Walleij <linus.walleij@linaro.org>
parent 6d591c46
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What:		/dev/gpiochip[0-9]+
Date:		November 2015
KernelVersion:	4.4
Contact:	linux-gpio@vger.kernel.org
Description:
		The character device files /dev/gpiochip* are the interface
		between GPIO chips and userspace.

		The ioctl(2)-based ABI is defined and documented in
		[include/uapi]<linux/gpio.h>.

		The following file operations are supported:

		open(2)
		Currently the only useful flags are O_RDWR.

		ioctl(2)
		Initiate various actions.
		See the inline documentation in [include/uapi]<linux/gpio.h>
		for descriptions of all ioctls.

		close(2)
		Stops and free up the I/O contexts that was associated
		with the file descriptor.

Users:		TBD
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@@ -4815,6 +4815,7 @@ L: linux-gpio@vger.kernel.org
T:	git git://git.kernel.org/pub/scm/linux/kernel/git/linusw/linux-gpio.git
S:	Maintained
F:	Documentation/gpio/
F:	Documentation/ABI/testing/gpio-cdev
F:	drivers/gpio/
F:	include/linux/gpio/
F:	include/linux/gpio.h