^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 1) ============================================================
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 2) WDT Watchdog Timer Interfaces For The Linux Operating System
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 3) ============================================================
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 4)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 5) Last Reviewed: 10/05/2007
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 6)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 7) Alan Cox <alan@lxorguk.ukuu.org.uk>
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 8)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 9) - ICS WDT501-P
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 10) - ICS WDT501-P (no fan tachometer)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 11) - ICS WDT500-P
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 12)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 13) All the interfaces provide /dev/watchdog, which when open must be written
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 14) to within a timeout or the machine will reboot. Each write delays the reboot
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 15) time another timeout. In the case of the software watchdog the ability to
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 16) reboot will depend on the state of the machines and interrupts. The hardware
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 17) boards physically pull the machine down off their own onboard timers and
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 18) will reboot from almost anything.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 19)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 20) A second temperature monitoring interface is available on the WDT501P cards.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 21) This provides /dev/temperature. This is the machine internal temperature in
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 22) degrees Fahrenheit. Each read returns a single byte giving the temperature.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 23)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 24) The third interface logs kernel messages on additional alert events.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 25)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 26) The ICS ISA-bus wdt card cannot be safely probed for. Instead you need to
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 27) pass IO address and IRQ boot parameters. E.g.::
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 28)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 29) wdt.io=0x240 wdt.irq=11
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 30)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 31) Other "wdt" driver parameters are:
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 32)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 33) =========== ======================================================
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 34) heartbeat Watchdog heartbeat in seconds (default 60)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 35) nowayout Watchdog cannot be stopped once started (kernel
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 36) build parameter)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 37) tachometer WDT501-P Fan Tachometer support (0=disable, default=0)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 38) type WDT501-P Card type (500 or 501, default=500)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 39) =========== ======================================================
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 40)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 41) Features
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 42) --------
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 43)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 44) ================ ======= =======
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 45) WDT501P WDT500P
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 46) ================ ======= =======
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 47) Reboot Timer X X
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 48) External Reboot X X
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 49) I/O Port Monitor o o
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 50) Temperature X o
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 51) Fan Speed X o
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 52) Power Under X o
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 53) Power Over X o
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 54) Overheat X o
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 55) ================ ======= =======
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 56)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 57) The external event interfaces on the WDT boards are not currently supported.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 58) Minor numbers are however allocated for it.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 59)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 60)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 61) Example Watchdog Driver:
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 62)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 63) see samples/watchdog/watchdog-simple.c
Orange Pi5 kernel
Deprecated Linux kernel 5.10.110 for OrangePi 5/5B/5+ boards
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