1What: /sys/class/gpio/ 2Date: July 2008 3KernelVersion: 2.6.27 4Contact: Linus Walleij <linusw@kernel.org> 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/admin-guide/gpio for more information. 15 16 :: 17 18 /sys/class/gpio 19 /export ... asks the kernel to export a GPIO to userspace 20 /unexport ... to return a GPIO to the kernel 21 /gpioN ... for each exported GPIO #N OR 22 /<LINE-NAME> ... for a properly named GPIO line 23 /value ... always readable, writes fail for input GPIOs 24 /direction ... r/w as: in, out (default low); write: high, low 25 /edge ... r/w as: none, falling, rising, both 26 /gpiochipN ... for each gpiochip; #N is its first GPIO 27 /base ... (r/o) same as N 28 /label ... (r/o) descriptive, not necessarily unique 29 /ngpio ... (r/o) number of GPIOs; numbered N to N + (ngpio - 1) 30 31 This ABI is obsoleted by Documentation/ABI/testing/gpio-cdev and will be 32 removed after 2020. 33