[lm-sensors] w83792d watchdog

[r.marek@sh.cvut.cz (Rudolf Marek)]

Hello all,

I begun to work on the watchdog support for w83792d. I have several questions about the watchdog device in w83792d. Please can
yuou forward them to responsible person?

I'm using ver 1.0 of datasheet

There are 4 watchdog regs:

CR01 handles the unlock codes
CR02 "Watch Dog Enable" -> this should be more likely called "Watch Dog Enable Status" - because this regs are RO only
CR03 is quite mystery for me
      the "WDT stage" is not described in datasheet at all, I assume this has someting to do with hard mode of watchdog


the HARD_TO and SOFT_TO have following commnents:

HARD_TO: 1: a hard timeout occurs. This bit will be cleared while reading.

What I know:

1) this bit is not cleared on reading
2) I think the sentece should be: "a hard timeoud had occured"
     because this is set when there was a timeout/reset it seems

This is so far to datasheet, now to real funcs:

1) What will happen if I enable hard and soft watchdog same time? (i'm disabling the hard watchdog timer in first place so
it should not be an issue but you never know)
2) I tried many ways to reset the watchdog timer but only seems to work is to write 0xAA to CR1 and then 0x55 to re-enable it.
     This seems bit strange because the computer can fail just in between of this two writes Yes I know this is not probable, but
     the best method is just to re-write the timeout value or rewrite the enable (0x55) - as others might do. Were there
     some strange reason for this design?

And last thing, It seems that the device registers survive system power cycle. Maybe I was just too fast and the caps powered
the chip. I will investigate...

I hope you can understand my thought because I'm quite tired now.

regards
Rudolf