1 files changed, 50 insertions, 0 deletions
diff --git a/Documentation/watchdog/wdt.txt b/Documentation/watchdog/wdt.txt
new file mode 100644
index 000000000..ed2f0b860
--- /dev/null
+++ b/Documentation/watchdog/wdt.txt
@@ -0,0 +1,50 @@
+Last Reviewed: 10/05/2007
+
+	WDT Watchdog Timer Interfaces For The Linux Operating System
+		Alan Cox <alan@lxorguk.ukuu.org.uk>
+
+	ICS	WDT501-P
+	ICS	WDT501-P (no fan tachometer)
+	ICS	WDT500-P
+
+All the interfaces provide /dev/watchdog, which when open must be written
+to within a timeout or the machine will reboot. Each write delays the reboot
+time another timeout. In the case of the software watchdog the ability to
+reboot will depend on the state of the machines and interrupts. The hardware
+boards physically pull the machine down off their own onboard timers and
+will reboot from almost anything.
+
+A second temperature monitoring interface is available on the WDT501P cards.
+This provides /dev/temperature. This is the machine internal temperature in
+degrees Fahrenheit. Each read returns a single byte giving the temperature.
+
+The third interface logs kernel messages on additional alert events.
+
+The ICS ISA-bus wdt card cannot be safely probed for. Instead you need to
+pass IO address and IRQ boot parameters.  E.g.:
+	wdt.io=0x240 wdt.irq=11
+
+Other "wdt" driver parameters are:
+	heartbeat	Watchdog heartbeat in seconds (default 60)
+	nowayout	Watchdog cannot be stopped once started (kernel
+				build parameter)
+	tachometer	WDT501-P Fan Tachometer support (0=disable, default=0)
+	type		WDT501-P Card type (500 or 501, default=500)
+
+Features
+--------
+		WDT501P		WDT500P
+Reboot Timer	   X               X
+External Reboot	   X	           X
+I/O Port Monitor   o		   o
+Temperature	   X		   o
+Fan Speed          X		   o
+Power Under	   X               o
+Power Over         X               o
+Overheat           X               o
+
+The external event interfaces on the WDT boards are not currently supported.
+Minor numbers are however allocated for it.
+
+
+Example Watchdog Driver:  see samples/watchdog/watchdog-simple.c