PowerPC4xx Watchdog

Takeharu KATO takeharu1219 at ybb.ne.jp
Sat Feb 26 06:35:17 EST 2005

Hi Matt

> Are you looking for the old "ppc405 watchdog" driver that simply
> hooked into the generic PPC heartbeat facility? Or are you looking
> for a driver that utilizes the 4xx/booke hardware watchdog facility?
After all, I wrote watch dog driver for PowerPC 4xx using 4xx/book-e 
watchdog facility and generic PPC heartbeat mechanism.

On second thought, I found that these are almost same.
As far as I think generic PPC heartbeat mechanism is more preferable
for embedded systems from memory consumption view at least.

Using generic PPC heartbeat mechanism can make the driver simple and small.
And more, this approach can achieve following profits:

1) The approach may not need modification in low-exception handling routines
(in arch/ppc/kernel/head_XXX).
2) The approach can achieve compatibility with old-driver.

Any way, I attached current version of my patch.
Please take a look on the patch.

I found critical interrupt relevant trivial bug in 
CRITICAL_EXCEPTION macro in the file use transfer_to_handler_full and
IMHO, The correct code is that this macro should use 
crit_transfer_to_handler, ret_from_crit_exc instead, isn't it?


Takeharu KATO
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