AM335x watchdog does not work

Question

I am currently working on TI AM335x board (Starter Kit) and I would like to get the OMAP watchdog working...

As far as I know the platform automatically enables the watchdog during boot and I think it is confirmed by the following messages printed out at boot:

[    1.510192] OMAP Watchdog Timer Rev 0x01: initial timeout 60 sec

If I am not wrong at this point if I issue the following command:

echo 0 > /dev/watchdog

the board should reboot in 60 seconds, isn't it? Instead after 60 seconds nothing happens... why? Am I missing something relevant about that? Can anybody help me?

Answer 1

Ok, I've found the solution on my own.

As clearly told here, the file /dev/watchdog must be kept open for allowing the watchdog to fire... then the right command for causing the watchdog fire is:

cat > /dev/watchdog

and then type 0: after 60 seconds the board will reboot.

Answer 2

It's not necessarily to keep /dev/watchdog open, if you push-on "disable watchdog timer support" (avaliable in Device Drivers->Watchdog Timer Support->...) feature on kernel menuconfig.