xref: /freebsd/share/man/man4/owc.4 (revision f0cfa1b168014f56c02b83e5f28412cc5f78d117)
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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/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