159 lines
3.8 KiB
Groff
159 lines
3.8 KiB
Groff
.\" Copyright (c) 2013, Luiz Otavio O Souza <loos@FreeBSD.org>
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.\" All rights reserved.
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice, this list of conditions and the following disclaimer.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
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.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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.\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
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.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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.\" SUCH DAMAGE.
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.\"
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.\" $FreeBSD$
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.\"
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.Dd July 30, 2016
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.Dt GPIOLED 4
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.Os
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.Sh NAME
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.Nm gpioled
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.Nd GPIO LED generic device driver
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.Sh SYNOPSIS
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To compile this driver into the kernel,
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place the following lines in your
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kernel configuration file:
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.Bd -ragged -offset indent
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.Cd "device gpio"
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.Cd "device gpioled"
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.Ed
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.Sh DESCRIPTION
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The
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.Nm
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driver provides glue to attach a
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.Xr led 4
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compatible device to a GPIO pin.
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Each LED in the system has a
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.Pa name
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which is used to export a device as
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.Pa /dev/led/<name> .
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The GPIO pin can then be controlled by writing to this device as described
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in
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.Xr led 4 .
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.Pp
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On a
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.Xr device.hints 5
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based system, like
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.Li MIPS ,
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these values are configurable for
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.Nm :
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.Bl -tag -width ".Va hint.gpioiic.%d.atXXX"
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.It Va hint.gpioled.%d.at
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The gpiobus you are attaching to.
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Normally assigned to gpiobus0.
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.It Va hint.gpioled.%d.name
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Arbitrary name of device in
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.Pa /dev/led/
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to create for
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.Xr led 4 .
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.It Va hint.gpioled.%d.pins
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Which pin on the GPIO interface to map to this instance.
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Please note that this mask should only ever have one bit set
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(any other bits - i.e., pins - will be ignored).
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.It Va hint.gpioled.%d.invert
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If set to 1, the pin will be set to 0 to light the LED, and 1 to clear it.
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.El
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.Pp
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On a
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.Xr FDT 4
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based system, like
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.Li ARM ,
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the DTS part for a
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.Nm gpioled
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device usually looks like:
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.Bd -literal
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gpio: gpio {
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gpio-controller;
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...
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led0 {
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compatible = "gpioled";
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gpios = <&gpio 16 2 0>; /* GPIO pin 16. */
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name = "ok";
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};
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led1 {
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compatible = "gpioled";
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gpios = <&gpio 17 2 0>; /* GPIO pin 17. */
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name = "user-led1";
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};
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};
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.Ed
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.Pp
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Optionally, you can choose to combine all the LEDs under a single
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.Dq gpio-leds
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compatible node:
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.Bd -literal
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simplebus0 {
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...
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leds {
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compatible = "gpio-leds";
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led0 {
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gpios = <&gpio 16 2 0>;
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name = "ok"
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};
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led1 {
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gpios = <&gpio 17 2 0>;
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name = "user-led1"
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};
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};
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};
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.Ed
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.Pp
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Both methods are equally supported and it is possible to have the LEDs
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defined with any sort of mix between the methods.
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The only restriction is that a GPIO pin cannot be mapped by two different
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(gpio)leds.
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.Pp
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For more details about the
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.Va gpios
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property, please consult
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.Pa /usr/src/sys/boot/fdt/dts/bindings-gpio.txt .
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.Pp
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The property
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.Va name
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is the arbitrary name of the device in
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.Pa /dev/led/
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to create for
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.Xr led 4 .
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.Sh SEE ALSO
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.Xr fdt 4 ,
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.Xr gpio 4 ,
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.Xr gpioiic 4 ,
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.Xr led 4
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.Sh HISTORY
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The
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.Nm
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manual page first appeared in
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.Fx 10.1 .
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.Sh AUTHORS
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This
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manual page was written by
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.An Luiz Otavio O Souza .
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