Re: [PATCH 3/3] watchdog: qcom: register a restart notifier

Pramod Gurav
2014-09-19T12:44:04Z

Hi Josh,

Tested this patch on IFC6410 by disabling pinctrl ps_hold reset
implementation and on top of Guenter's patchset for restart_notifier.

Tested-by: pramod.gurav@smartplayin.com

I picked up DT changes from bindings as they are from this patchset.

Thanks
Pramod
On Friday 19 September 2014 03:57 AM, Josh Cartwright wrote:
> The WDT's BITE_TIME warm-reset behavior can be leveraged as a last
> resort mechanism for triggering chip reset. Usually, other restart
> methods (such as PS_HOLD) are preferrable for issuing a more complete
> reset of the chip. As such, keep the priority of the watchdog notifier
> low.
>
> Signed-off-by: Josh Cartwright <joshc@codeaurora.org>
> ---
> drivers/watchdog/qcom-wdt.c | 31 +++++++++++++++++++++++++++++++
> 1 file changed, 31 insertions(+)
>
> diff --git a/drivers/watchdog/qcom-wdt.c b/drivers/watchdog/qcom-wdt.c
> index e9409f5..710ab43 100644
> --- a/drivers/watchdog/qcom-wdt.c
> +++ b/drivers/watchdog/qcom-wdt.c
> @@ -15,6 +15,7 @@
> #include <linux/module.h>
> #include <linux/of.h>
> #include <linux/platform_device.h>
> +#include <linux/reboot.h>
> #include <linux/watchdog.h>
>
> #define WDT_RST 0x0
> @@ -24,6 +25,7 @@
> struct qcom_wdt {
> struct watchdog_device wdd;
> unsigned long freq;
> + struct notifier_block restart_nb;
> void __iomem *base;
> };
>
> @@ -82,6 +84,24 @@ static const struct watchdog_info qcom_wdt_info = {
> .identity = KBUILD_MODNAME,
> };
>
> +static int qcom_wdt_restart(struct notifier_block *nb, unsigned long action,
> + void *data)
> +{
> + struct qcom_wdt *wdt = container_of(nb, struct qcom_wdt, restart_nb);
> +
> + /*
> + * Trigger watchdog bite:
> + * Setup BITE_TIME to be very low, and enable WDT.
> + */
> + mutex_lock(&wdt->wdd.lock);
> + writel_relaxed(0, wdt->base + WDT_EN);
> + writel_relaxed(1, wdt->base + WDT_RST);
> + writel_relaxed(0x31F3, wdt->base + WDT_BITE_TIME);
> + writel_relaxed(1, wdt->base + WDT_EN);
> + mutex_unlock(&wdt->wdd.lock);
> + return NOTIFY_DONE;
> +}
> +
> static int qcom_watchdog_probe(struct platform_device *pdev)
> {
> struct qcom_wdt *wdt;
> @@ -121,6 +141,17 @@ static int qcom_watchdog_probe(struct platform_device *pdev)
> return ret;
> }
>
> + /*
> + * WDT restart notifier has priority 0 (use as a last resort)
> + */
> + wdt->restart_nb.notifier_call = qcom_wdt_restart;
> + ret = register_restart_handler(&wdt->restart_nb);
> + if (ret) {
> + dev_err(&pdev->dev, "failed to setup restart handler\n");
> + watchdog_unregister_device(&wdt->wdd);
> + return ret;
> + }
> +
> return 0;
> }
>
>