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.Dd January 1, 2020 28.Dt IIC_GPIOMUX 4 29.Os 30.Sh NAME 31.Nm iic_gpiomux 32.Nd driver for I2C mux hardware controlled via GPIO 33.Sh SYNOPSIS 34To compile this driver into the kernel, 35place the following line in your 36kernel configuration file: 37.Bd -ragged -offset indent 38.Cd "device iic_gpiomux" 39.Ed 40.Pp 41Alternatively, to load the driver as a 42module at boot time, place the following line in 43.Xr loader.conf 5 : 44.Bd -literal -offset indent 45iic_gpiomux_load="YES" 46.Ed 47.Sh DESCRIPTION 48The 49.Nm 50driver supports any type of I2C bus multiplexer (mux) hardware that 51is controlled by manipulating the state of one or more GPIO pins. 52It automatically connects an upstream I2C bus to one of the downstream 53buses as needed when slave devices on the downstream buses initiate I/O. 54More information on the automatic switching behavior is available in 55.Xr iicmux 4 . 56.Sh FDT CONFIGURATION 57On an 58.Xr fdt 4 59based system, an 60.Nm 61device node may be defined as a child node of any arbitrary bus 62in the FDT data. 63The 64.Va i2c-parent 65property indicates the connection to the upstream I2C bus. 66The children of the 67.Nm 68node are additional i2c buses, which will have their own i2c slave 69devices described in their child nodes. 70.Pp 71The 72.Nm 73driver conforms to the standard 74.Bk -words 75.Li i2c/i2c-mux-gpio.txt 76.Ek 77bindings document. 78.Sh SEE ALSO 79.Xr iicbus 4 , 80.Xr iicmux 4 81.Sh HISTORY 82The 83.Nm 84driver first appeared in 85.Fx 13.0 . 86