1fe95046eSLinus WalleijWhat:		/sys/class/gpio/
2fe95046eSLinus WalleijDate:		July 2008
3fe95046eSLinus WalleijKernelVersion:	2.6.27
4fe95046eSLinus WalleijContact:	Linus Walleij <linusw@kernel.org>
5fe95046eSLinus WalleijDescription:
6fe95046eSLinus Walleij
7fe95046eSLinus Walleij  As a Kconfig option, individual GPIO signals may be accessed from
8fe95046eSLinus Walleij  userspace.  GPIOs are only made available to userspace by an explicit
9fe95046eSLinus Walleij  "export" operation.  If a given GPIO is not claimed for use by
10fe95046eSLinus Walleij  kernel code, it may be exported by userspace (and unexported later).
11fe95046eSLinus Walleij  Kernel code may export it for complete or partial access.
12fe95046eSLinus Walleij
13fe95046eSLinus Walleij  GPIOs are identified as they are inside the kernel, using integers in
14c2746a1eSMauro Carvalho Chehab  the range 0..INT_MAX.  See Documentation/admin-guide/gpio for more information.
15fe95046eSLinus Walleij
167832dea7SMauro Carvalho Chehab  ::
177832dea7SMauro Carvalho Chehab
18fe95046eSLinus Walleij    /sys/class/gpio
19fe95046eSLinus Walleij	/export ... asks the kernel to export a GPIO to userspace
20fe95046eSLinus Walleij	/unexport ... to return a GPIO to the kernel
21fe95046eSLinus Walleij	/gpioN ... for each exported GPIO #N OR
22fe95046eSLinus Walleij	/<LINE-NAME> ... for a properly named GPIO line
23fe95046eSLinus Walleij	    /value ... always readable, writes fail for input GPIOs
24fe95046eSLinus Walleij	    /direction ... r/w as: in, out (default low); write: high, low
25fe95046eSLinus Walleij	    /edge ... r/w as: none, falling, rising, both
26fe95046eSLinus Walleij	/gpiochipN ... for each gpiochip; #N is its first GPIO
27fe95046eSLinus Walleij	    /base ... (r/o) same as N
28fe95046eSLinus Walleij	    /label ... (r/o) descriptive, not necessarily unique
29fe95046eSLinus Walleij	    /ngpio ... (r/o) number of GPIOs; numbered N to N + (ngpio - 1)
30fe95046eSLinus Walleij
31fe95046eSLinus Walleij  This ABI is deprecated and will be removed after 2020. It is
32fe95046eSLinus Walleij  replaced with the GPIO character device.
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