Messages in this thread | | | Subject | Re: [PATCH 3/3] watchdog: bcm2835_wdt: set WDOG_HW_RUNNING bit when appropriate | From | Guenter Roeck <> | Date | Fri, 15 Jul 2016 06:46:29 -0700 |
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On 07/15/2016 01:15 AM, Rasmus Villemoes wrote: > A bootloader may start the watchdog device before handing control to > the kernel - in that case, we should tell the kernel about it so the > watchdog framework can keep it alive until userspace opens > /dev/watchdog0. >
Separate note: The maximum timeout for this watchdog is 15 seconds. Given that, it might be useful to set max_hw_heartbeat_ms instead of max_timeout. Separate patch, though.
> Signed-off-by: Rasmus Villemoes <rasmus.villemoes@prevas.dk> > --- > drivers/watchdog/bcm2835_wdt.c | 22 ++++++++++++++++++++++ > 1 file changed, 22 insertions(+) > > diff --git a/drivers/watchdog/bcm2835_wdt.c b/drivers/watchdog/bcm2835_wdt.c > index 4dddd82..9a08334 100644 > --- a/drivers/watchdog/bcm2835_wdt.c > +++ b/drivers/watchdog/bcm2835_wdt.c > @@ -55,6 +55,15 @@ struct bcm2835_wdt { > static unsigned int heartbeat; > static bool nowayout = WATCHDOG_NOWAYOUT; > > +static bool bcm2835_wdt_is_running(struct bcm2835_wdt *wdt) > +{ > + uint32_t cur; > + > + cur = readl(wdt->base + PM_RSTC); > + > + return !!(cur & PM_RSTC_WRCFG_FULL_RESET); > +} > + > static int bcm2835_wdt_start(struct watchdog_device *wdog) > { > struct bcm2835_wdt *wdt = watchdog_get_drvdata(wdog); > @@ -70,6 +79,7 @@ static int bcm2835_wdt_start(struct watchdog_device *wdog) > PM_RSTC_WRCFG_FULL_RESET, wdt->base + PM_RSTC); > > spin_unlock_irqrestore(&wdt->lock, flags); > + set_bit(WDOG_HW_RUNNING, &wdog->status); > You don't need to set this bit here unless the watchdog can not be stopped.
> return 0; > } > @@ -79,6 +89,7 @@ static int bcm2835_wdt_stop(struct watchdog_device *wdog) > struct bcm2835_wdt *wdt = watchdog_get_drvdata(wdog); > > writel_relaxed(PM_PASSWORD | PM_RSTC_RESET, wdt->base + PM_RSTC); > + clear_bit(WDOG_HW_RUNNING, &wdog->status);
... and since you clear the bit, it can be stopped. Both setting and resetting the bit is therefore not necessary.
> return 0; > } > > @@ -181,6 +192,17 @@ static int bcm2835_wdt_probe(struct platform_device *pdev) > watchdog_init_timeout(&bcm2835_wdt_wdd, heartbeat, dev); > watchdog_set_nowayout(&bcm2835_wdt_wdd, nowayout); > bcm2835_wdt_wdd.parent = &pdev->dev; > + if (bcm2835_wdt_is_running(wdt)) { > + /* > + * The currently active timeout value (set by the > + * bootloader) may be different from the module > + * heartbeat parameter or the value in device > + * tree. But we just need to set WDOG_HW_RUNNING, > + * because then the framework will "immediately" ping > + * the device, updating the timeout. > + */ > + set_bit(WDOG_HW_RUNNING, &bcm2835_wdt_wdd.status); > + } > err = watchdog_register_device(&bcm2835_wdt_wdd); > if (err) { > dev_err(dev, "Failed to register watchdog device"); >
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