[U-Boot] Watchdog support for ppc4xx

[Chen Wen]

u-boot reset watchdog everywhere in u-boot code.
But linux reset watchdog only when you reset /dev/watchdog by ioctl.

You can try to  put "mtspr(SPRN_TSR, TSR_ENW|TSR_WIS);" in kernel main.c to
keep alive the watchdog.

On Sat, Jun 5, 2010 at 4:14 AM, Mark Maestas <maestas at aplabs.com> wrote:

> Thanks Wolfgang,
>
> The board is resetting within u-boot before Linux starts to load.  I
> added the WATCHDOG_RESET call in common/image.c before and after it is
> loading the device tree which is where it gets reset.  I figured that if
> I reset the watchdog before that process it will give me more time so
> that Linux can load and take over.  It seems like code was already there
> to handle the reset in memmove_wd but it does not seem to be working.
> The Linux watchdog code is working great.  If I remove watchdog from
> u-boot and just do it in Linux it works just fine.  I enable BookE
> driver in Linux and that works.  The other thing that is difficult is
> creating a /dev/watchdog node in the blob.  Currently I need to do that
> in a startup script.  I would like to have that in the blob.
>
> The watchdog_reset function is trying to prevent the interrupt from
> happening.  It does seem to do the correct thing based on the PPC440 UG.
>
> Thanks for the help.
>
> Mark
>
> -----Original Message-----
> From: Wolfgang Denk [mailto:wd at denx.de]
> Sent: Friday, June 04, 2010 12:47 PM
> To: Mark Maestas
> Cc: Detlev Zundel; Stefan Roese; u-boot at lists.denx.de
> Subject: Re: [U-Boot] Watchdog support for ppc4xx
>
> Dear "Mark Maestas",
>
> In message <B02FCC6065C3164C8228CF04AB049EAC0114CCDA at srv-01.aplabs.com>
> you wrote:
> >
> > I am not having luck with watchdog enabled on the ppc4xx target.  The
> > board is doing a reset before Linux gets a chance to load.  I have
> added
>
> Please define exactly what you mean by "before Linux gets a chance to
> load" - is it resetting in U-Boot, or after passsing control to the
> Linux kernel?
>
> > more WATCHDOG_RESET commands in the image file just to see if that
> helps
>
> What does "in the image file" mean?
>
> > and it does not seem to.  Even though the reset function gets called
> it
> > is still getting reset.  According to the ppc 440 documentation the
>
> By "reset function" you actually mean the code that is supposed to
> trigger the watchdog? Otherwise - the reset function is supposed to
> reset the system, so everthing would be OK then.
>
> > TSR[WIS] bit should get cleared to reset the timer and the code is
> doing
> > that.  I don't understand why the board keeps resetting.
>
> This depends on the hardware, and obviously on the code doing this
> (keep in mind that using I/O accessors is mandatory these days).
>
> Best regards,
>
> Wolfgang Denk
>
> --
> DENX Software Engineering GmbH,     MD: Wolfgang Denk & Detlev Zundel
> HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany
> Phone: (+49)-8142-66989-10 Fax: (+49)-8142-66989-80 Email: wd at denx.de
> I haven't lost my mind -- it's backed up on tape somewhere.
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