1.\" 2.\" Copyright (c) 2015 M. Warner Losh 3.\" All rights reserved. 4.\" 5.\" Redistribution and use in source and binary forms, with or without 6.\" modification, are permitted provided that the following conditions 7.\" are met: 8.\" 1. Redistributions of source code must retain the above copyright 9.\" notice, this list of conditions and the following disclaimer. 10.\" 2. The name of the author may not be used to endorse or promote products 11.\" derived from this software without specific prior written permission. 12.\" 13.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 14.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 15.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 16.\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 17.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 18.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 19.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 20.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 21.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 22.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 23.\" SUCH DAMAGE. 24.\" 25.\" $FreeBSD$ 26.\" 27.Dd July 20, 2015 28.Dt OWC 4 29.Os 30.Sh NAME 31.Nm owc 32.Nd Dallas Semiconductor 1-Wire Controller 33.Sh SYNOPSIS 34.Cd device owc 35.Sh DESCRIPTION 36The 37.Nm 38module implements Dallas Semiconductor 1-Wire signaling. 39It attaches the 40.Xr ow 4 41driver 1-Wire bus protocol. 42The 43.Nm 44device implements the Link Layer of the 1-Wire bus protocol stack. 45.Pp 46Bit banging a pin on a 47.Xr gpiobus 4 48is the only supported controller. 49Both standard and overdrive transfer timings are implemented. 50Strong pull-up functionality needed to support parasitic mode is not 51implemented. 52.Pp 53To enable 1-Wire for FDT systems requires modifying the DTS for your 54board to add something like: 55.Bd -literal 56/ { 57 ... 58 onewire { 59 compatible = "w1-gpio"; 60 gpios = <&gpio 4 1>; 61 }; 62 ... 63}; 64.Ed 65.Pp 66The gpios property describes the GPIO pin the 1-Wire bus is connected 67to. 68For more details about the 69.Va gpios 70property, please consult 71.Pa /usr/src/sys/boot/fdt/dts/bindings-gpio.txt . 72.Sh SEE ALSO 73.Xr gpiobus 4 , 74.Xr ow 4 , 75.Xr ow_temp 4 , 76.Xr owll 9 , 77.Xr own 9 78.Sh LEGAL 79.Tn 1-Wire 80is a registered trademark of Maxim Integrated Products, Inc. 81.Sh HISTORY 82The 83.Nm 84driver first appeared in 85.Fx 11.0 . 86.Sh AUTHORS 87The 88.Nm 89device driver and this manual page were written by 90.An Warner Losh . 91.Sh CAVEATS 92The gpio driver implements timing by busy waiting, which can cause a 93high load on slower systems. 94.Sh BUGS 95Overdrive mode has not actually been tested. 96