[ECOS] watchdog - powerpc

Jonathan Larmour jifl@eCosCentric.com
Fri May 23 01:55:00 GMT 2003

Bob Koninckx wrote:
> Powerpc _enables_ the watchdog by default. According to the hardware
> manual you can only disable it out of reset but never re-enable it
> afterwards.
> from the spec ... SYPCR
> This register can be read at any time but can be written only once after
> system reset ...
> I do not think you want a watchdog in redboot. But then redboot needs to
> disable it, meaning you can not use it in the application afterwards
> either. On the other hand, leaving it enabled in redboot gives the
> application a chance to decide. But then you'll end up having problems
> in redboot if you do not start the application fast enough. Am I missing
> something ?

Have the HAL provide a default NO-OP watchdog exception handler that acks 
the watchdog (or whatever's required)? An application or watchdog device 
driver can then override as required just by overriding the exception.

Or arguably just write a standard watchdog device driver (as lives in 
devs/watchdog and uses io/watchdog) and include it in the RedBoot 
image.... and if CYGPKG_IO_WATCHDOG isn't defined in <pkgconf/system.h> 
just disable the watchdog entirely in SYPCR.

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