.\"	$OpenBSD: wdog_register.9,v 1.4 2006/09/25 04:41:10 mk Exp $
.\"
.\" Copyright (c) 2004 Michael Knudsen <mk@openbsd.org>
.\"
.\" Permission to use, copy, modify, and distribute this software for any
.\" purpose with or without fee is hereby granted, provided that the above
.\" copyright notice and this permission notice appear in all copies.
.\"
.\" THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
.\" WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
.\" MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
.\" ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
.\" WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
.\" ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
.\" OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
.\"
.Dd December 17, 2004
.Dt WDOG_REGISTER 9
.Os
.Sh NAME
.Nm wdog_register
.Nd kernel watchdog interface
.Sh SYNOPSIS
.In sys/systm.h
.Ft void
.Fn wdog_register "void *cb_arg" "int (*cb)(void *cb_arg, int period)"
.Sh DESCRIPTION
The kernel watchdog interface is used by hardware watchdog drivers and
should be used for all future drivers.
.Pp
.Fn wdog_register
is called by the hardware driver after configuring the hardware watchdog
device.
The
.Fa cb_arg
argument is a pointer to the hardware device control structure.
The
.Fa cb
argument is a pointer to a function supplied by the driver which sets
the timeout in the hardware device.
.Pp
The
.Fa cb_arg
parameter given to
.Fa cb
is a pointer to the device control structure.
The
.Fa period
parameter supplies the desired timeout value in seconds.
A
.Fa period
value of zero disables the watchdog.
Setting the timeout to a nonzero value after disabling the watchdog
will update the timeout value and enable the watchdog.
.Sh CODE REFERENCES
The framework is implemented in the file
.Pa sys/kern/kern_watchdog.c .
.Sh SEE ALSO
.Xr watchdog 4 ,
.Xr sysctl_int 9 ,
.Xr timeout 9
.Sh HISTORY
The watchdog timer framework was written by
.An Markus Friedl Aq markus@openbsd.org
and first appeared in
.Ox 3.3 .