freebsd-dev/share/man/man4/owc.4
Warner Losh f86e60008b Regularize my copyright notice
o Remove All Rights Reserved from my notices
o imp@FreeBSD.org everywhere
o regularize punctiation, eliminate date ranges
o Make sure that it's clear that I don't claim All Rights reserved by listing
  All Rights Reserved on same line as other copyright holders (but not
  me). Other such holders are also listed last where it's clear.
2019-12-04 16:56:11 +00:00

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.\"
.\" Copyright (c) 2015 M. Warner Losh <imp@FreeBSD.org>
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.\" $FreeBSD$
.\"
.Dd June 26, 2019
.Dt OWC 4
.Os
.Sh NAME
.Nm owc
.Nd Dallas Semiconductor 1-Wire Controller
.Sh SYNOPSIS
.Cd device owc
.Sh DESCRIPTION
The
.Nm
module implements Dallas Semiconductor 1-Wire signaling.
It attaches the
.Xr ow 4
driver 1-Wire bus protocol.
The
.Nm
device implements the Link Layer of the 1-Wire bus protocol stack.
.Pp
Bit banging a pin on a
.Xr gpiobus 4
is the only supported controller.
Both standard and overdrive transfer timings are implemented.
Strong pull-up functionality needed to support parasitic mode is not
implemented.
.Pp
To enable 1-Wire for FDT systems requires modifying the DTS for your
board to add something like:
.Bd -literal
/ {
...
onewire {
compatible = "w1-gpio";
gpios = <&gpio 4 1>;
};
...
};
.Ed
.Pp
The gpios property describes the GPIO pin the 1-Wire bus is connected
to.
For more details about the
.Va gpios
property, please consult
.Pa /usr/src/sys/dts/bindings-gpio.txt .
.Pp
On a
.Xr device.hints 5
based system these values are required for the
.Nm :
.Bl -tag -width ".Va hint.owc.%d.atXXX"
.It Va hint.owc.%d.at
The
.Nm gpiobus
you are attaching to.
.It Va hint.owc.%d.pins
This is a bitmask that defines a pin on the
.Nm gpiobus
that is to be used for the 1-Wire bus.
For instance, to configure pin 10, use the bitmask of 0x400.
Please note that this mask should have only one bit set
(any other bits - i.e., pins - will be ignored).
.El
.Sh SEE ALSO
.Xr gpiobus 4 ,
.Xr ow 4 ,
.Xr ow_temp 4 ,
.Xr owll 9 ,
.Xr own 9
.Sh LEGAL
.Tn 1-Wire
is a registered trademark of Maxim Integrated Products, Inc.
.Sh HISTORY
The
.Nm
driver first appeared in
.Fx 11.0 .
.Sh AUTHORS
The
.Nm
device driver and this manual page were written by
.An Warner Losh .
.Sh CAVEATS
The gpio driver implements timing by busy waiting, which can cause a
high load on slower systems.
.Sh BUGS
Overdrive mode has not actually been tested.