On Thu, Sep 25, 2014 at 12:48:53PM -0500, 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 <[email protected]>
> ---
> drivers/watchdog/qcom-wdt.c | 38 ++++++++++++++++++++++++++++++++++++++
> 1 file changed, 38 insertions(+)
>
> diff --git a/drivers/watchdog/qcom-wdt.c b/drivers/watchdog/qcom-wdt.c
> index 0f56ca3..8ce339f 100644
> --- a/drivers/watchdog/qcom-wdt.c
> +++ b/drivers/watchdog/qcom-wdt.c
> @@ -10,12 +10,14 @@
> * GNU General Public License for more details.
> *
> */
> +#include <linux/delay.h>
Nitpick: Please keep alphabetical order of include files.
That makes it easier to identify include files later on.
> #include <linux/clk.h>
> #include <linux/io.h>
> #include <linux/kernel.h>
> #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
> @@ -26,6 +28,7 @@ struct qcom_wdt {
> struct watchdog_device wdd;
> struct clk *clk;
> unsigned long rate;
> + struct notifier_block restart_nb;
> void __iomem *base;
> };
>
> @@ -84,6 +87,32 @@ 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);
> + u32 timeout;
> +
> + /*
> + * Trigger watchdog bite:
> + * Setup BITE_TIME to be 128ms, and enable WDT.
> + */
> + timeout = 128 * wdt->rate / 1000;
> +
> + writel(0, wdt->base + WDT_EN);
> + writel(1, wdt->base + WDT_RST);
> + writel(timeout, wdt->base + WDT_BITE_TIME);
> + writel(1, wdt->base + WDT_EN);
> +
> + /*
> + * Actually make sure the above sequence hits hardware before sleeping.
> + */
> + wmb();
> +
> + msleep(150);
> + return NOTIFY_DONE;
> +}
> +
> static int qcom_wdt_probe(struct platform_device *pdev)
> {
> struct qcom_wdt *wdt;
> @@ -149,6 +178,14 @@ static int qcom_wdt_probe(struct platform_device *pdev)
> goto err_clk_unprepare;
> }
>
> + /*
> + * 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");
> +
> platform_set_drvdata(pdev, wdt);
> return 0;
>
> @@ -162,6 +199,7 @@ static int qcom_wdt_remove(struct platform_device *pdev)
> {
> struct qcom_wdt *wdt = platform_get_drvdata(pdev);
>
> + unregister_restart_handler(&wdt->restart_nb);
> watchdog_unregister_device(&wdt->wdd);
> clk_disable_unprepare(wdt->clk);
> return 0;
> --
> Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum,
> hosted by The Linux Foundation
>
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