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Based on kernel version 3.15.4. Page generated on 2014-07-07 08:59 EST.

1	What:		/sys/class/gpio/
2	Date:		July 2008
3	KernelVersion:	2.6.27
4	Contact:	David Brownell <dbrownell@users.sourceforge.net>
5	Description:
6	
7	  As a Kconfig option, individual GPIO signals may be accessed from
8	  userspace.  GPIOs are only made available to userspace by an explicit
9	  "export" operation.  If a given GPIO is not claimed for use by
10	  kernel code, it may be exported by userspace (and unexported later).
11	  Kernel code may export it for complete or partial access.
12	
13	  GPIOs are identified as they are inside the kernel, using integers in
14	  the range 0..INT_MAX.  See Documentation/gpio.txt for more information.
15	
16	    /sys/class/gpio
17		/export ... asks the kernel to export a GPIO to userspace
18		/unexport ... to return a GPIO to the kernel
19		/gpioN ... for each exported GPIO #N
20		    /value ... always readable, writes fail for input GPIOs
21		    /direction ... r/w as: in, out (default low); write: high, low
22		    /edge ... r/w as: none, falling, rising, both
23		/gpiochipN ... for each gpiochip; #N is its first GPIO
24		    /base ... (r/o) same as N
25		    /label ... (r/o) descriptive, not necessarily unique
26		    /ngpio ... (r/o) number of GPIOs; numbered N to N + (ngpio - 1)
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