sysfs-gpio 1.3 KB

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  1. What: /sys/class/gpio/
  2. Date: July 2008
  3. KernelVersion: 2.6.27
  4. Contact: Linus Walleij <linusw@kernel.org>
  5. Description:
  6. As a Kconfig option, individual GPIO signals may be accessed from
  7. userspace. GPIOs are only made available to userspace by an explicit
  8. "export" operation. If a given GPIO is not claimed for use by
  9. kernel code, it may be exported by userspace (and unexported later).
  10. Kernel code may export it for complete or partial access.
  11. GPIOs are identified as they are inside the kernel, using integers in
  12. the range 0..INT_MAX. See Documentation/admin-guide/gpio for more information.
  13. ::
  14. /sys/class/gpio
  15. /export ... asks the kernel to export a GPIO to userspace
  16. /unexport ... to return a GPIO to the kernel
  17. /gpioN ... for each exported GPIO #N OR
  18. /<LINE-NAME> ... for a properly named GPIO line
  19. /value ... always readable, writes fail for input GPIOs
  20. /direction ... r/w as: in, out (default low); write: high, low
  21. /edge ... r/w as: none, falling, rising, both
  22. /gpiochipN ... for each gpiochip; #N is its first GPIO
  23. /base ... (r/o) same as N
  24. /label ... (r/o) descriptive, not necessarily unique
  25. /ngpio ... (r/o) number of GPIOs; numbered N to N + (ngpio - 1)
  26. This ABI is deprecated and will be removed after 2020. It is
  27. replaced with the GPIO character device.