88 lines
2.8 KiB
Groff
88 lines
2.8 KiB
Groff
.\"-
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.\" SPDX-License-Identifier: BSD-2-Clause
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.\"
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.\" Copyright (c) 2019 Ian Lepore <ian@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. 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 January 1, 2020
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.Dt IIC_GPIOMUX 4
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.Os
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.Sh NAME
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.Nm iic_gpiomux
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.Nd driver for I2C mux hardware controlled via GPIO
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.Sh SYNOPSIS
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To compile this driver into the kernel,
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place the following line in your
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kernel configuration file:
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.Bd -ragged -offset indent
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.Cd "device iic_gpiomux"
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.Ed
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.Pp
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Alternatively, to load the driver as a
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module at boot time, place the following line in
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.Xr loader.conf 5 :
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.Bd -literal -offset indent
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iic_gpiomux_load="YES"
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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 supports any type of I2C bus multiplexer (mux) hardware that
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is controlled by manipulating the state of one or more GPIO pins.
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It automatically connects an upstream I2C bus to one of the downstream
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buses as needed when slave devices on the downstream buses initiate I/O.
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More information on the automatic switching behavior is available in
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.Xr iicmux 4 .
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.Sh FDT CONFIGURATION
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On an
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.Xr fdt 4
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based system, an
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.Nm
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device node may be defined as a child node of any arbitrary bus
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in the FDT data.
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The
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.Va i2c-parent
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property indicates the connection to the upstream I2C bus.
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The children of the
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.Nm
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node are additional i2c buses, which will have their own i2c slave
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devices described in their child nodes.
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.Pp
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The
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.Nm
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driver conforms to the standard
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.Bk -words
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.Li i2c/i2c-mux-gpio.txt
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.Ek
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bindings document.
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.Sh SEE ALSO
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.Xr iicbus 4 ,
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.Xr iicmux 4
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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 13.0 .
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