Re: [RFC PATCH 1/5] watchdog: Add API to trigger reboots

[Guenter Roeck]

On 05/02/2014 03:01 AM, Will Deacon wrote:
> Hi Guenter,
>
> This looks pretty sensible to me (and the arm/arm64 bits look fine too), but
> I have one question below...
>
> On Thu, May 01, 2014 at 04:41:29PM +0100, Guenter Roeck wrote:
> > Some hardware implements reboot through its watchdog hardware,
> > for example by triggering a watchdog timeout. Platform specific
> > code starts to spread into watchdog drivers, typically by setting
> > pointers to a callback functions which is then called from the
> > platform reset handler.
> >
> > To simplify code and provide a unified API to trigger reboots by
> > watchdog drivers, provide a single API to trigger such reboots
> > through the watchdog subsystem.
> >
> > Signed-off-by: Guenter Roeck <linux@xxxxxxxxxxxx>
> > ---
> >   drivers/watchdog/watchdog_core.c |   17 +++++++++++++++++
> >   include/linux/watchdog.h         |   11 +++++++++++
> >   2 files changed, 28 insertions(+)
> >
> > diff --git a/drivers/watchdog/watchdog_core.c b/drivers/watchdog/watchdog_core.c
> > index cec9b55..4ec6e2f 100644
> > --- a/drivers/watchdog/watchdog_core.c
> > +++ b/drivers/watchdog/watchdog_core.c
> > @@ -43,6 +43,17 @@
> >   static DEFINE_IDA(watchdog_ida);
> >   static struct class *watchdog_class;
> >
> > +static struct watchdog_device *wdd_reboot_dev;
> > +
> > +void watchdog_do_reboot(enum reboot_mode mode, const char *cmd)
> > +{
> > +	if (wdd_reboot_dev) {
> > +		if (wdd_reboot_dev->ops->reboot)
> > +			wdd_reboot_dev->ops->reboot(wdd_reboot_dev, mode, cmd);
> > +	}
> > +}
>
> What reboot_mode values would you expect a watchdog to support other than
> REBOOT_HARD? Also, is the cmd even useful here?

Answer is "I don't know" in both cases. I thought about dropping the parameters,
but then I thought it does not hurt to have them around either. I am open to
suggestions and to dropping the parameters if everyone agrees that they are
useless.

Guenter

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