.\"	$OpenBSD: wdog_register.9,v 1.5 2007/05/31 19:20:01 jmc Exp $
.\"
.\" Copyright (c) 2004 Michael Knudsen <mk@openbsd.org>
.\"
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.Dd $Mdocdate: May 31 2007 $
.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 .