.\"-
.\" Copyright (c) 2012 Bjoern A. Zeeb <bz@FreeBSD.org>
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.Dd December 28, 2012
.Dt WBWD 4
.Os
.Sh NAME
.Nm wbwd
.Nd device driver for watchdog timer found on Winbond Super I/O chips
.Sh SYNOPSIS
To compile this driver into the kernel, place the following line in your
kernel configuration file:
.Bd -ragged -offset indent
.Cd "device wbwd"
.Ed
.Pp
Alternatively, to load the driver as a module at boot time, place the following
line in
.Xr loader.conf 5 :
.Bd -literal -offset indent
wbwd_load="YES"
.Ed
.Sh DESCRIPTION
The
.Nm
driver provides
.Xr watchdog 4
support for the watchdog interrupt timer present on at least the following
Winbond Super I/O chips:
.Pp
.Bl -bullet -compact
.It
83627HF/F/HG/G Rev. G
.It
83627HF/F/HG/G Rev. J
.It
83627HF/F/HG/G Rev. UD-A
.It
83627DHG IC ver. 5
.El
.Sh SYSCTL VARIABLES
The
.Nm
driver provides the following options as
.Xr sysctl 8
variables.
.Bl -tag -width "xxxxxx"
.It Va dev.wbwd.0.timeout_override
This variable allows to program the timer to a value independent on the one
provided by the
.Xr watchdog 4
framework while still relying on the regular updates from e.g.
.Xr watchdogd 8 .
This is particularly useful if your system provides multiple watchdogs and
you want them to fire in a special sequence to trigger an NMI after a shorter
period than the reset timeout for example.
The value set must not be lower than the sleep time of
.Xr watchdogd 8 .
A value of 0 disables this feature and the timeout value provided by
.Xr watchdog 4
will be used.
.It Va dev.wbwd.0.debug_verbose
If set this sysctl will tell the driver to log its current state before and
after the timer reset on each invocation from
.Xr watchdog 9
to the kernel message buffer for debugging.
.It Va dev.wbwd.0.debug
This read-only value gives the state of some registers on last update.
.El
.Pp
The
.Nm
driver also provides further sysctl options that are hidden by default.
See the source code for more information.
.Sh SEE ALSO
.Xr watchdog 4 ,
.Xr device.hints 5 ,
.Xr watchdog 8 ,
.Xr watchdogd 8 ,
.Xr watchdog 9
.Sh HISTORY
The
.Nm
driver first appeared in
.Fx 10.0 .
.Sh AUTHORS
.An -nosplit
This manual page was written by
.An Bjoern A. Zeeb Aq bz@FreeBSD.org .