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| author | Russell King <rmk@dyn-67.arm.linux.org.uk> | 2008-10-09 21:33:05 +0100 |
|---|---|---|
| committer | Russell King <rmk+kernel@arm.linux.org.uk> | 2008-10-09 21:33:05 +0100 |
| commit | c97f68145e8067b3ac4b126a6faebf90f9ffc302 (patch) | |
| tree | eb2060681552a00e9efa98224b95f69a3dc84390 /Documentation/ABI/testing/sysfs-gpio | |
| parent | b1add0480a95b6ceaece5caf6c50614771eae9b2 (diff) | |
| parent | 7bff3c4ce44ea48f50dc47a5994454984bd08c59 (diff) | |
Merge branch 'for-rmk' of git://source.mvista.com/git/linux-davinci-2.6.git
Merge branch 'davinci' into devel
Diffstat (limited to 'Documentation/ABI/testing/sysfs-gpio')
| -rw-r--r-- | Documentation/ABI/testing/sysfs-gpio | 26 |
1 files changed, 26 insertions, 0 deletions
diff --git a/Documentation/ABI/testing/sysfs-gpio b/Documentation/ABI/testing/sysfs-gpio new file mode 100644 index 000000000000..8aab8092ad35 --- /dev/null +++ b/Documentation/ABI/testing/sysfs-gpio @@ -0,0 +1,26 @@ +What: /sys/class/gpio/ +Date: July 2008 +KernelVersion: 2.6.27 +Contact: David Brownell <dbrownell@users.sourceforge.net> +Description: + + As a Kconfig option, individual GPIO signals may be accessed from + userspace. GPIOs are only made available to userspace by an explicit + "export" operation. If a given GPIO is not claimed for use by + kernel code, it may be exported by userspace (and unexported later). + Kernel code may export it for complete or partial access. + + GPIOs are identified as they are inside the kernel, using integers in + the range 0..INT_MAX. See Documentation/gpio.txt for more information. + + /sys/class/gpio + /export ... asks the kernel to export a GPIO to userspace + /unexport ... to return a GPIO to the kernel + /gpioN ... for each exported GPIO #N + /value ... always readable, writes fail for input GPIOs + /direction ... r/w as: in, out (default low); write: high, low + /gpiochipN ... for each gpiochip; #N is its first GPIO + /base ... (r/o) same as N + /label ... (r/o) descriptive, not necessarily unique + /ngpio ... (r/o) number of GPIOs; numbered N to N + (ngpio - 1) + |