[mirror_ubuntu-hirsute-kernel.git] / Documentation / ABI / obsolete / sysfs-gpio

What:		/sys/class/gpio/
Date:		July 2008
KernelVersion:	2.6.27
Contact:	Linus Walleij <linusw@kernel.org>
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/admin-guide/gpio 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 OR
	/<LINE-NAME> ... for a properly named GPIO line
	    /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)

  This ABI is deprecated and will be removed after 2020. It is
  replaced with the GPIO character device.
Commit	Line	Data
9f986a8c DB	1	What: /sys/class/gpio/
	2	Date: July 2008
	3	KernelVersion: 2.6.27
fe95046e	4	Contact: Linus Walleij <linusw@kernel.org>
9f986a8c DB	5	Description:
	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
c2746a1e	14	the range 0..INT_MAX. See Documentation/admin-guide/gpio for more information.
9f986a8c	15
7832dea7 MCC	16	::
7832dea7 MCC	17
9f986a8c DB	18	/sys/class/gpio
	19	/export ... asks the kernel to export a GPIO to userspace
	20	/unexport ... to return a GPIO to the kernel
77a775b7 LW	21	/gpioN ... for each exported GPIO #N OR
77a775b7 LW	22	/<LINE-NAME> ... for a properly named GPIO line
9f986a8c DB	23	/value ... always readable, writes fail for input GPIOs
9f986a8c DB	24	/direction ... r/w as: in, out (default low); write: high, low
ff77c352	25	/edge ... r/w as: none, falling, rising, both
9f986a8c DB	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
fe95046e LW	31	This ABI is deprecated and will be removed after 2020. It is
fe95046e LW	32	replaced with the GPIO character device.