--- /dev/null
+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 Documentation/watchdog/src/watchdog-simple.c
Code Review / kvmfornfv.git / blobdiff