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authorLinus Walleij <linusw@kernel.org>2026-06-30 18:05:56 +0100
committerRussell King <rmk+kernel@armlinux.org.uk>2026-08-05 16:48:11 +0100
commitbb3b2cfeb206f5b10b859e134651b54120e3f530 (patch)
tree6717fcea088ba5c5f15002a48101fa2537135bf2 /Documentation/ABI/testing/gpio-cdev
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ARM: 9480/1: entry: expand comment in __switch_tografted
As per discussion between the developers in the mail thread linked, expand the comment in __switch_to so that readers of the code understand what is going on. Suggested-by: Mark Rutland <mark.rutland@arm.com> Acked-by: Mark Rutland <mark.rutland@arm.com> Signed-off-by: Linus Walleij <linusw@kernel.org>> Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
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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 in
+ [include/uapi]<linux/gpio.h> and documented in
+ Documentation/userspace-api/gpio/chardev.rst.
+
+ The following file operations are supported:
+
+ open(2)
+ Currently the only useful flags are O_RDWR.
+
+ ioctl(2)
+ Initiate various actions.
+
+ See Documentation/userspace-api/gpio/chardev.rst
+ for a description of all ioctls.
+
+ close(2)
+ Stops and free up the I/O contexts that was associated
+ with the file descriptor.
+
+Users: TBD