1.\" 2.\" Copyright (c) 2015 M. Warner Losh <imp@FreeBSD.org> 3.\" 4.\" Redistribution and use in source and binary forms, with or without 5.\" modification, are permitted provided that the following conditions 6.\" are met: 7.\" 1. Redistributions of source code must retain the above copyright 8.\" notice, this list of conditions and the following disclaimer. 9.\" 2. The name of the author may not be used to endorse or promote products 10.\" derived from this software without specific prior written permission. 11.\" 12.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 13.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 14.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 15.\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 16.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 17.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 18.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 19.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 20.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 21.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 22.\" SUCH DAMAGE. 23.\" 24.Dd June 26, 2019 25.Dt OWC 4 26.Os 27.Sh NAME 28.Nm owc 29.Nd Dallas Semiconductor 1-Wire Controller 30.Sh SYNOPSIS 31.Cd device owc 32.Sh DESCRIPTION 33The 34.Nm 35module implements Dallas Semiconductor 1-Wire signaling. 36It attaches the 37.Xr ow 4 38driver 1-Wire bus protocol. 39The 40.Nm 41device implements the Link Layer of the 1-Wire bus protocol stack. 42.Pp 43Bit banging a pin on a 44.Xr gpiobus 4 45is the only supported controller. 46Both standard and overdrive transfer timings are implemented. 47Strong pull-up functionality needed to support parasitic mode is not 48implemented. 49.Pp 50To enable 1-Wire for FDT systems requires modifying the DTS for your 51board to add something like: 52.Bd -literal 53/ { 54 ... 55 onewire { 56 compatible = "w1-gpio"; 57 gpios = <&gpio 4 1>; 58 }; 59 ... 60}; 61.Ed 62.Pp 63The gpios property describes the GPIO pin the 1-Wire bus is connected 64to. 65For more details about the 66.Va gpios 67property, please consult 68.Pa /usr/src/sys/dts/bindings-gpio.txt . 69.Pp 70On a 71.Xr device.hints 5 72based system these values are required for the 73.Nm : 74.Bl -tag -width ".Va hint.owc.%d.atXXX" 75.It Va hint.owc.%d.at 76The 77.Nm gpiobus 78you are attaching to. 79.It Va hint.owc.%d.pins 80This is a bitmask that defines a pin on the 81.Nm gpiobus 82that is to be used for the 1-Wire bus. 83For instance, to configure pin 10, use the bitmask of 0x400. 84Please note that this mask should have only one bit set 85(any other bits - i.e., pins - will be ignored). 86.El 87.Sh SEE ALSO 88.Xr gpiobus 4 , 89.Xr ow 4 , 90.Xr ow_temp 4 , 91.Xr owll 9 , 92.Xr own 9 93.Sh LEGAL 94.Tn 1-Wire 95is a registered trademark of Maxim Integrated Products, Inc. 96.Sh HISTORY 97The 98.Nm 99driver first appeared in 100.Fx 11.0 . 101.Sh AUTHORS 102The 103.Nm 104device driver and this manual page were written by 105.An Warner Losh . 106.Sh CAVEATS 107The gpio driver implements timing by busy waiting, which can cause a 108high load on slower systems. 109.Sh BUGS 110Overdrive mode has not actually been tested. 111