From 849369d6c66d3054688672f97d31fceb8e8230fb Mon Sep 17 00:00:00 2001 From: root Date: Fri, 25 Dec 2015 04:40:36 +0000 Subject: initial_commit --- Documentation/ABI/testing/sysfs-gpio | 27 +++++++++++++++++++++++++++ 1 file changed, 27 insertions(+) create mode 100644 Documentation/ABI/testing/sysfs-gpio (limited to 'Documentation/ABI/testing/sysfs-gpio') diff --git a/Documentation/ABI/testing/sysfs-gpio b/Documentation/ABI/testing/sysfs-gpio new file mode 100644 index 00000000..80f4c94c --- /dev/null +++ b/Documentation/ABI/testing/sysfs-gpio @@ -0,0 +1,27 @@ +What: /sys/class/gpio/ +Date: July 2008 +KernelVersion: 2.6.27 +Contact: David Brownell +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 + /edge ... r/w as: none, falling, rising, both + /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) + -- cgit v1.2.3