1 Last Reviewed: 10/05/2007
3 WDT Watchdog Timer Interfaces For The Linux Operating System
4 Alan Cox <alan@lxorguk.ukuu.org.uk>
7 ICS WDT501-P (no fan tachometer)
10 All the interfaces provide /dev/watchdog, which when open must be written
11 to within a timeout or the machine will reboot. Each write delays the reboot
12 time another timeout. In the case of the software watchdog the ability to
13 reboot will depend on the state of the machines and interrupts. The hardware
14 boards physically pull the machine down off their own onboard timers and
15 will reboot from almost anything.
17 A second temperature monitoring interface is available on the WDT501P cards
18 This provides /dev/temperature. This is the machine internal temperature in
19 degrees Fahrenheit. Each read returns a single byte giving the temperature.
21 The third interface logs kernel messages on additional alert events.
23 The wdt card cannot be safely probed for. Instead you need to pass
24 wdt=ioaddr,irq as a boot parameter - eg "wdt=0x240,11".
38 The external event interfaces on the WDT boards are not currently supported.
39 Minor numbers are however allocated for it.
42 Example Watchdog Driver: see Documentation/watchdog/src/watchdog-simple.c