xref: /netbsd/usr.sbin/gpioctl/gpioctl.8 (revision b1f2ec74)

.\" $NetBSD: gpioctl.8,v 1.24 2019/10/20 17:45:08 wiz Exp $
.\"
.\" Copyright (c) 2009, 2010, 2011, 2013 Marc Balmer <marc@msys.ch>
.\" 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 October 20, 2019
.Dt GPIOCTL 8
.Os
.Sh NAME
.Nm gpioctl
.Nd control GPIO devices
.Sh SYNOPSIS
.Nm gpioctl
.Op Fl qs
.Ar device
.Nm gpioctl
.Op Fl q
.Ar device
.Cm attach
.Ar device
.Ar offset
.Ar mask
.Op Ar flag
.Nm gpioctl
.Op Fl qs
.Ar device
.Ar pin
.Op Ar 0 | 1 | 2
.Nm gpioctl
.Op Fl qs
.Ar device
.Ar pin
.Op Ar 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
.Ar list
.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 0 or 1.
A value of 2
.Dq toggles
the pin, i.e. changes its state to the opposite.
Instead of the numerical values, the word
.Ar on ,
.Ar off ,
or
.Ar 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.
Such drivers can be detached at runtime using the
.Xr drvctl 8
command.
.Pp
The following configuration
.Ar flags
are supported by the GPIO framework:
.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
.It pulsate
pulsate output at a hardware-defined frequency and duty cycle
.It alt0 - alt7
select alternate pin function 0 to 7
.El
.Pp
Note that not all the flags may be supported by the particular GPIO controller.
.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 (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.
.It Fl s
Only output a single number on stdout, representing either the state of the
pin or the number of available pins if no pin number was passed as argument.
This option is useful e.g. when
.Nm
is used in shell scripts to query the state of a pin.
.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 # drvctl -d  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
.Pp
Enumerate all pins and display their symbolic names:
.Pp
.Dl # gpioctl gpio0 list
.Sh SEE ALSO
.Xr gpio 4 ,
.Xr drvctl 8
.Sh HISTORY
The
.Nm
command first appeared in
.Ox 3.6
and
.Nx 4.0 .
.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 marc@msys.ch .