Re: [PATCH 6/8] [WATCHDOG] mpc8xxx_wdt: add support for MPC8xx watchdogs

Hi Anton,

The mpc8xxx_wdt driver is using two registers: SWSRR to push magic
numbers, and SWCRR to control the watchdog. Both registers are available
on the MPC8xx, and seem to have the same offsets and semantics as in
MPC83xx/MPC86xx watchdogs. The only difference is prescale value. So this
driver should simply work on the MPC8xx CPUs.

MPC823 seem to be the first CPU in MPC8xx line, so we use fsl,mpc823-wdt
compatible matching.

Though, this patch was only build-tested and okay to drop from this
series until tested or corrected to work on the actual hardware.

Signed-off-by: Anton Vorontsov <redacted>

Tested-by: Jochen Friedrich <jochen@scram.de>

The driver works OK on MPC823.

One nit however ist the late initialisation of the wdt timer. I had to add
two hardcoded wdt resets in the board setup, one in setup_arch and one in
arch_initcall, to prevent a reset until mpc8xxx_wdt kicks in. However, IMHO
this is acceptable as it only hits the 8xx series with the small prescale.

Some time ago in http://patchwork.ozlabs.org/linuxppc/patch?person=1023&id=16189,
i tried a different aproach to the problem (mainly a port of the old ARC=ppc
stuff), but the code became very ugly and the wdt maintainers didn't like it
very much.

So the only thing left for full 8xx support is a refactoring / cleanup of
http://patchwork.ozlabs.org/linuxppc/patch?person=1023&id=16262.

Thanks,
Jochen