On Wed, Jan 12, 2011 at 01:36:37PM +0100, Tobias Klauser wrote:
[...]
> > > +static long altera_wdt_ioctl(struct file *file, unsigned int cmd,
> > > + unsigned long arg)
> > > +{
> > > + struct altera_wdt_dev *wdev = file->private_data;
> > > + void __user *argp = (void __user *) arg;
> > > +
> > > + switch (cmd) {
> > > + case WDIOC_GETSUPPORT:
> > > + return copy_to_user(argp, &altera_wdt_info, sizeof(altera_wdt_info));
> > > + case WDIOC_KEEPALIVE:
> > > + altera_wdt_ping(wdev);
> > > + return 0;
> > > + default:
> > > + return -ENOTTY;
> > > + }
> > > +}
> >
> > Can you set/get the timeout period on this watchdog? Even if you can't
> > set it then it would be good to allow the user to read the constant
> > timeout that the watchdog uses so it knows how often to kick it. If you
> > use the software timeout heartbeat then in the future you could emulate
> > longer timeouts.
>
> This is a very primitive watchdog timer which does only allow the
> timeout period to be set when instantiating the timer in the FPGA, so
> from a software point-of-view the timer has a fixed timeout. It doesn't
> even allow to read the timeout value directly from the "hardware".
>
> But we could use the additional information (including the timeout value
> among a lot of other configurable values) generated when building the
> FPGA firmware and store that in the device tree (support for device tree
> was recently added to the Nios2 Linux port). So we could get it (and
> the base address) from there in the altera_wdt driver. Does that sound
> reasonable?
That sounds like a very good idea to me. I can see that allowing
userspace to know the timeout period would be useful.
Jamie
--
To unsubscribe from this list: send the line "unsubscribe linux-watchdog" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
