a476ba06d5
o Remove All Rights Reserved from my notices o imp@FreeBSD.org everywhere o regularize punctiation, eliminate date ranges o Make sure that it's clear that I don't claim All Rights reserved by listing All Rights Reserved on same line as other copyright holders (but not me). Other such holders are also listed last where it's clear.
113 lines
3.1 KiB
Groff
113 lines
3.1 KiB
Groff
.\"
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.\" Copyright (c) 2015 M. Warner Losh <imp@FreeBSD.org>
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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. The name of the author may not be used to endorse or promote products
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.\" derived from this software without specific prior written permission.
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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 June 26, 2019
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.Dt OWC 4
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.Os
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.Sh NAME
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.Nm owc
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.Nd Dallas Semiconductor 1-Wire Controller
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.Sh SYNOPSIS
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.Cd device owc
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.Sh DESCRIPTION
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The
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.Nm
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module implements Dallas Semiconductor 1-Wire signaling.
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It attaches the
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.Xr ow 4
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driver 1-Wire bus protocol.
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The
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.Nm
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device implements the Link Layer of the 1-Wire bus protocol stack.
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.Pp
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Bit banging a pin on a
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.Xr gpiobus 4
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is the only supported controller.
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Both standard and overdrive transfer timings are implemented.
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Strong pull-up functionality needed to support parasitic mode is not
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implemented.
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.Pp
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To enable 1-Wire for FDT systems requires modifying the DTS for your
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board to add something like:
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.Bd -literal
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/ {
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...
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onewire {
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compatible = "w1-gpio";
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gpios = <&gpio 4 1>;
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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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The gpios property describes the GPIO pin the 1-Wire bus is connected
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to.
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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/dts/bindings-gpio.txt .
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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 these values are required for the
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.Nm :
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.Bl -tag -width ".Va hint.owc.%d.atXXX"
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.It Va hint.owc.%d.at
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The
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.Nm gpiobus
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you are attaching to.
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.It Va hint.owc.%d.pins
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This is a bitmask that defines a pin on the
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.Nm gpiobus
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that is to be used for the 1-Wire bus.
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For instance, to configure pin 10, use the bitmask of 0x400.
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Please note that this mask should have only one bit set
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(any other bits - i.e., pins - will be ignored).
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.El
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.Sh SEE ALSO
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.Xr gpiobus 4 ,
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.Xr ow 4 ,
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.Xr ow_temp 4 ,
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.Xr owll 9 ,
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.Xr own 9
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.Sh LEGAL
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.Tn 1-Wire
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is a registered trademark of Maxim Integrated Products, Inc.
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.Sh HISTORY
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The
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.Nm
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driver first appeared in
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.Fx 11.0 .
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.Sh AUTHORS
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The
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.Nm
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device driver and this manual page were written by
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.An Warner Losh .
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.Sh CAVEATS
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The gpio driver implements timing by busy waiting, which can cause a
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high load on slower systems.
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.Sh BUGS
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Overdrive mode has not actually been tested.
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