GPIOCTL(8)              OpenBSD System Manager's Manual             GPIOCTL(8)

NAME
     gpioctl - control GPIO devices

SYNOPSIS
     gpioctl [-q] device attach device offset mask
     gpioctl [-q] device detach device
     gpioctl [-q] device pin [0 | 1 | 2]
     gpioctl [-q] device pin [on | off | toggle]
     gpioctl [-q] device pin set [flags] [name]
     gpioctl [-q] device pin unset

DESCRIPTION
     The gpioctl program allows manipulation of GPIO (General Purpose In-
     put/Output) device pins.  Such devices can be either part of the chipset
     or embedded CPU, or a separate chip.  The usual way of using GPIO is to
     connect some simple devices such as LEDs and 1-wire thermal sensors to
     its pins.

     Each GPIO device has an associated device file in the /dev directory.
     device can be specified with or without the /dev prefix.  For example,
     /dev/gpio0 or gpio0.

     GPIO pins can be either ``read'' or ``written'' with the values of logi-
     cal 0 or 1.  If only a pin number is specified on the command line, the
     pin state will be read from the GPIO controller and displayed.  To write
     to a pin, a value must be specified after the pin number.  Values can be
     either 0 or 1.  A value of 2 has a special meaning: it ``toggles'' the
     pin, i.e. changes its state to the opposite.  Instead of the numerical
     values, the word on, off, or toggle can be used.

     Only pins that have been configured at securelevel 0, typically during
     system startup, are accessible once the securelevel has been raised.
     Pins can be given symbolic names for easier use.  Besides using individu-
     al pins, device drivers that use GPIO pins can be attached to a gpio(4)
     device using the gpioctl command.

     The following configuration flags are supported by the GPIO framework:

           in      input direction
           out     output direction
           inout   bi-directional
           od      open-drain output
           pp      push-pull output
           tri     tri-state (output disabled)
           pu      internal pull-up enabled
           pd      internal pull-down enabled
           iin     invert input
           iout    invert output

     Note that not all the flags can be supported by the particular GPIO con-
     troller.

     When executed with only the gpio(4) device name as argument, gpioctl
     reads information about the GPIO device and displays it.  At securelevel
     0 the number of physically available pins is displayed, at higher se-
     curelevels the number of configured (set) pins is displayed.

     The options are as follows:

     -q      Operate quietly i.e. nothing is printed to stdout.

FILES
     /dev/gpiou  GPIO device unit u file.

EXAMPLES
     Configure pin 20 to have push-pull output:

           # gpioctl gpio0 20 set out pp

     Write logical 1 to pin 20:

           # gpioctl gpio0 20 1

     Attach a onewire(4) bus on a gpioow(4) device on pin 4:

           # gpioctl gpio0 attach gpioow 4 0x01

     Detach the gpioow0 device:

           # gpioctl gpio0 detach gpioow0

     Configure pin 5 as output and name it error_led:

           # gpioctl gpio0 5 set out error_led

     Toggle the error_led:

           # gpioctl gpio0 error_led 2

SEE ALSO
     gpio(4)

HISTORY
     The gpioctl command first appeared in OpenBSD 3.6.

AUTHORS
     The gpioctl program was written by Alexander Yurchenko
     <grange@openbsd.org>.  Device attachment was added by
     Marc Balmer <mbalmer@openbsd.org>.

OpenBSD 4.7                    December 5, 2008                              2
