1.\"- 2.\" SPDX-License-Identifier: BSD-2-Clause 3.\" 4.\" Copyright (c) 2019 Ian Lepore <ian@freebsd.org> 5.\" 6.\" Redistribution and use in source and binary forms, with or without 7.\" modification, are permitted provided that the following conditions 8.\" are met: 9.\" 1. Redistributions of source code must retain the above copyright 10.\" notice, this list of conditions and the following disclaimer. 11.\" 2. Redistributions in binary form must reproduce the above copyright 12.\" notice, this list of conditions and the following disclaimer in the 13.\" documentation and/or other materials provided with the distribution. 14.\" 15.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 16.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 17.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 18.\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 19.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 20.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 21.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 22.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 23.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 24.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 25.\" SUCH DAMAGE. 26.\" 27.\" $FreeBSD$ 28.\" 29.Dd January 1, 2020 30.Dt IIC_GPIOMUX 4 31.Os 32.Sh NAME 33.Nm iic_gpiomux 34.Nd driver for I2C mux hardware controlled via GPIO 35.Sh SYNOPSIS 36To compile this driver into the kernel, 37place the following line in your 38kernel configuration file: 39.Bd -ragged -offset indent 40.Cd "device iic_gpiomux" 41.Ed 42.Pp 43Alternatively, to load the driver as a 44module at boot time, place the following line in 45.Xr loader.conf 5 : 46.Bd -literal -offset indent 47iic_gpiomux_load="YES" 48.Ed 49.Sh DESCRIPTION 50The 51.Nm 52driver supports any type of I2C bus multiplexer (mux) hardware that 53is controlled by manipulating the state of one or more GPIO pins. 54It automatically connects an upstream I2C bus to one of the downstream 55buses as needed when slave devices on the downstream buses initiate I/O. 56More information on the automatic switching behavior is available in 57.Xr iicmux 4 . 58.Pp 59.Sh FDT CONFIGURATION 60On an 61.Xr fdt 4 62based system, an 63.Nm 64device node may be defined as a child node of any arbitrary bus 65in the FDT data. 66The 67.Va i2c-parent 68property indicates the connection to the upstream I2C bus. 69The children of the 70.Nm 71node are additional i2c buses, which will have their own i2c slave 72devices described in their child nodes. 73.Pp 74The 75.Nm 76driver conforms to the standard 77.Bk -words 78.Li i2c/i2c-mux-gpio.txt 79.Ek 80bindings document. 81.Sh SEE ALSO 82.Xr iicbus 4 , 83.Xr iicmux 4 , 84.Sh HISTORY 85The 86.Nm 87driver first appeared in 88.Fx 13.0 . 89