.\"	$OpenBSD: gpioctl.8,v 1.25 2018/03/12 12:52:14 jmc Exp $
.\"
.\" Copyright (c) 2004 Alexander Yurchenko <grange@openbsd.org>
.\"
.\" Permission to use, copy, modify, and distribute this software for any
.\" purpose with or without fee is hereby granted, provided that the above
.\" copyright notice and this permission notice appear in all copies.
.\"
.\" THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
.\" WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
.\" MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
.\" ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
.\" WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
.\" ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
.\" OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
.\"
.Dd $Mdocdate: March 12 2018 $
.Dt GPIOCTL 8
.Os
.Sh NAME
.Nm gpioctl
.Nd control GPIO devices
.Sh SYNOPSIS
.Nm gpioctl
.Op Fl q
.Ar device
.Ar pin
.Op Cm 0 | 1 | 2 | on | off | toggle
.Nm gpioctl
.Op Fl q
.Ar device
.Ar pin
.Cm set
.Op Ar flags
.Op Ar name
.Nm gpioctl
.Op Fl q
.Ar device
.Ar pin
.Cm unset
.Nm gpioctl
.Op Fl q
.Ar device
.Cm attach
.Ar device
.Ar offset
.Ar mask
.Op Ar flag
.Nm gpioctl
.Op Fl q
.Ar device
.Cm detach
.Ar device
.Sh DESCRIPTION
The
.Nm
program allows manipulation of GPIO
(General Purpose Input/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.
.Pp
Each GPIO device has an associated device file in the
.Pa /dev
directory.
.Ar device
can be specified with or without the
.Pa /dev
prefix.
For example,
.Pa /dev/gpio0
or
.Pa gpio0 .
.Pp
GPIO pins can be either
.Dq read
or
.Dq written
with the values of logical 0 or 1.
If only a
.Ar 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
.Ar pin
number.
Values can be either
.Cm 0
or
.Cm 1 .
A value of
.Cm 2
has a special meaning: it
.Dq toggles
the pin, i.e. changes its state to the opposite.
Instead of the numerical values, the word
.Cm on ,
.Cm off ,
or
.Cm toggle
can be used.
.Pp
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 individual pins, device drivers that use GPIO pins can be
attached to a
.Xr gpio 4
device using the
.Nm
command.
.Pp
The following configuration
.Ar flags
are supported by the GPIO framework.
Note that not all the flags can be supported by the particular GPIO controller.
.Pp
.Bl -tag -width Ds -offset indent -compact
.It in
input direction
.It out
output direction
.It inout
bi-directional
.It od
open-drain output
.It pp
push-pull output
.It tri
tri-state (output disabled)
.It pu
internal pull-up enabled
.It pd
internal pull-down enabled
.It iin
invert input
.It iout
invert output
.El
.Pp
When attaching an I2C device,
if the
.Ar flag
argument is set to 1,
the order of the SDA and SCL signals is reversed
(see
.Xr gpioiic 4 ) .
.Pp
When executed with only the
.Xr gpio 4
device name as argument,
.Nm
reads information about the GPIO device and displays it.
At securelevel 0 the number of physically available pins is displayed,
at higher securelevels the number of configured
.Pq Cm set
pins is displayed.
.Pp
The options are as follows:
.Bl -tag -width Ds
.It Fl q
Operate quietly i.e. nothing is printed to stdout.
.El
.Sh FILES
.Bl -tag -width "/dev/gpiou" -compact
.It /dev/gpio Ns Ar u
GPIO device unit
.Ar u
file.
.El
.Sh EXAMPLES
Configure pin 20 to have push-pull output:
.Pp
.Dl # gpioctl gpio0 20 set out pp
.Pp
Write logical 1 to pin 20:
.Pp
.Dl # gpioctl gpio0 20 1
.Pp
Attach a
.Xr onewire 4
bus on a
.Xr gpioow 4
device on pin 4:
.Pp
.Dl # gpioctl gpio0 attach gpioow 4 0x01
.Pp
Detach the gpioow0 device:
.Pp
.Dl # gpioctl gpio0 detach gpioow0
.Pp
Configure pin 5 as output and name it error_led:
.Pp
.Dl # gpioctl gpio0 5 set out error_led
.Pp
Toggle the error_led:
.Pp
.Dl # gpioctl gpio0 error_led 2
.Sh SEE ALSO
.Xr gpio 4
.Sh HISTORY
The
.Nm
command first appeared in
.Ox 3.6 .
.Sh AUTHORS
.An -nosplit
The
.Nm
program was written by
.An Alexander Yurchenko Aq Mt grange@openbsd.org .
Device attachment was added by
.An Marc Balmer Aq Mt mbalmer@openbsd.org .