184 lines
3.7 KiB
Groff
184 lines
3.7 KiB
Groff
.\" $NetBSD: gpioctl.8,v 1.4 2008/01/09 15:56:27 xtraeme Exp $
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.\" $OpenBSD: gpioctl.8,v 1.5 2004/12/02 05:11:40 grange Exp $
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.\"
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.\" Copyright (c) 2004 Alexander Yurchenko <grange@openbsd.org>
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.\"
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.\" Permission to use, copy, modify, and distribute this software for any
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.\" purpose with or without fee is hereby granted, provided that the above
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.\" copyright notice and this permission notice appear in all copies.
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.\"
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.\" THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
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.\" WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
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.\" MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
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.\" ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
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.\" WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
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.\" ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
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.\" OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
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.\"
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.Dd January 9, 2008
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.Dt GPIOCTL 8
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.Os
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.Sh NAME
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.Nm gpioctl
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.Nd control GPIO devices
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.Sh SYNOPSIS
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.Nm
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.Op Fl hq
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.Op Fl d Ar device
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.Op Ar pin
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.Op Ar 0 | 1 | 2
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.Nm
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.Op Fl hq
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.Op Fl d Ar device
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.Fl c
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.Ar pin
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.Op Ar flags
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.Sh DESCRIPTION
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The
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.Nm
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program allows manipulation of
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.Tn GPIO
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(General Purpose Input/Output) device pins.
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Such devices can be either part of the chipset or embedded
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.Tn CPU ,
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or a separate chip.
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The usual way of using
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.Tn GPIO
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is to connect some simple devices such as LEDs, 1-wire thermal sensors,
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etc., to its pins.
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.Pp
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Each
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.Tn GPIO
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device has an associated device file in the
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.Pa /dev
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directory.
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By default
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.Nm
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uses
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.Pa /dev/gpio0 ,
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which corresponds to the first found
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.Tn GPIO
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device in the system.
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If more than one
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.Tn GPIO
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device is present, an alternative device file can be specified with the
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.Fl d
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option in order to access a particular
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.Tn GPIO
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device.
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.Pp
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When executed without any arguments,
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.Nm
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reads information about the
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.Tn GPIO
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device and displays it.
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.Pp
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.Tn GPIO
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pins can be either
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.Dq read
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or
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.Dq written
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with the values of logical 0 or 1.
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If only a
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.Ar pin
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number is specified on the command line, the pin state will be read
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from the
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.Tn GPIO
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controller and displayed.
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To write to a pin, a value must be specified after the
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.Ar pin
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number.
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Values can be either 0 or 1.
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A value of 2 has a special meaning: it
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.Dq toggles
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the pin, i.e. changes its state to the opposite.
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.Pp
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Each pin can be configured with different flags with the
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.Fl c
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option.
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The following configuration flags are supported by the
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.Tn GPIO
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framework:
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.Pp
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.Bl -tag -width XXXXXXX -offset indent -compact
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.It in
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input direction
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.It out
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output direction
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.It inout
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bi-directional
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.It od
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open-drain output
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.It pp
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push-pull output
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.It tri
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tri-state (output disabled)
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.It pu
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internal pull-up enabled
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.It pd
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internal pull-down enabled
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.It iin
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invert input
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.It iout
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invert output
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.El
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.Pp
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Note that not all the flags can be supported by the particular
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.Tn GPIO
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controller.
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The list of supported flags is always displayed when executing
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.Nm
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with the
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.Fl c
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option.
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If only a
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.Ar pin
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number is specified on the command line, the current pin flags will be
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displayed.
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To change pin flags, a new flags set separated by spaces must be
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specified after the
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.Ar pin
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number.
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.Pp
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The
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.Fl q
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option causes
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.Nm
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to operate quietly i.e. nothing is printed to stdout.
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The
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.Fl h
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option displays a usage summary.
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.Sh FILES
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.Bl -tag -width "/dev/gpiou" -compact
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.It /dev/gpio Ns Ar u
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GPIO device unit
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.Ar u
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file.
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.El
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.Sh EXAMPLES
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Configure pin 20 to have push-pull output:
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.Pp
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.Dl # gpioctl -c 20 out pp
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.Pp
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Write logical 1 to pin 20:
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.Pp
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.Dl # gpioctl 20 1
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.Sh SEE ALSO
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.Xr elansc 4 ,
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.Xr gcscpcib 4 ,
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.Xr gpio 4 ,
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.Xr gscpcib 4 ,
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.Xr nsclpcsio 4
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.Sh HISTORY
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The
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.Nm
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command first appeared in
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.Ox 3.6
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and
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.Nx 4.0 .
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.Sh AUTHORS
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The
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.Nm
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program was written by
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.An Alexander Yurchenko Aq grange@openbsd.org .
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