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 /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) 27 28