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: Linus Walleij <linus.walleij@linaro.org>

diff --git a/Documentation/ABI/testing/gpio-cdev b/Documentation/ABI/testing/gpio-cdev
new file mode 100644 (file)
index 0000000..7b265fb
--- /dev/null
+++ b/Documentation/ABI/testing/gpio-cdev
@@ -0,0 +1,26 @@
+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

diff --git a/MAINTAINERS b/MAINTAINERS
index 4d3d1b8178730ee7a5ae8c447a43171778f41049..a85cd6dcb5de511d5bdab71c26ea11771810d7e3 100644 (file)
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -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