Fu Wei wrote:

Actually I am taking your suggestion to avoid touching WCV in
interrupt routine.
So even we have pre-timeout support , it is useless for this
panic-on-half-timeout feature,
because pre-timeout  == timeout / 2 (always).

So maybe I misunderstand your suggestion,
could you let me know : why we want pre-timeout here?

Maybe I'm confused.

For pre-timeout, I think the SBSA watchdog driver should support only 
half-timeout.  That is, the user cannot configure the length of the 
pre-timeout with this driver.  He can only enable it, and it is 
automatically set to 1/2 timeout.

So when pre-timeout occurs, the interrupt handler calls panic() or 
whatever it's supposed to do.

So "pre-timeout  == timeout / 2 (always)" is exactly what we want.