diff options
| author | Ingo Molnar <mingo@elte.hu> | 2008-10-12 15:05:39 +0200 |
|---|---|---|
| committer | Ingo Molnar <mingo@elte.hu> | 2008-10-12 15:05:39 +0200 |
| commit | a9b9e81c915e4a57ac3b21d1a7fa7ff184639780 (patch) | |
| tree | 98304395fbb5b9c74fca35b196cd414c1949f280 /Documentation/ABI/testing/sysfs-gpio | |
| parent | a8b71a2810386a5ac8f43d2095fe3355f0d8db37 (diff) | |
| parent | fd048088306656824958e7783ffcee27e241b361 (diff) | |
Merge branch 'linus' into x86/memory-corruption-check
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 00000000000..8aab8092ad3 --- /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) + |