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authorIngo Molnar <mingo@elte.hu>2008-10-13 05:05:51 -0400
committerIngo Molnar <mingo@elte.hu>2008-10-13 05:05:51 -0400
commitaccba5f3965d6a9d1bf7c1e1a7995d17e9d521b6 (patch)
tree8fb40782e79472ed882ff2098d4dd295557278ee /Documentation/ABI/testing/sysfs-gpio
parent6852fd9b86d05063c6ef49d2e12e061cc7f6a105 (diff)
parent4480f15b3306f43bbb0310d461142b4e897ca45b (diff)
Merge branch 'linus' into oprofile-v2
Conflicts: arch/x86/kernel/apic_32.c arch/x86/oprofile/nmi_int.c include/linux/pci_ids.h
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1What: /sys/class/gpio/
2Date: July 2008
3KernelVersion: 2.6.27
4Contact: David Brownell <dbrownell@users.sourceforge.net>
5Description:
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 /gpiochipN ... for each gpiochip; #N is its first GPIO
23 /base ... (r/o) same as N
24 /label ... (r/o) descriptive, not necessarily unique
25 /ngpio ... (r/o) number of GPIOs; numbered N to N + (ngpio - 1)
26