| Message ID | 1baf370c79a9bd7d57214c732863375374da2e0a.1411684967.git.joshc@codeaurora.org (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On 09/25/2014 03:51 PM, 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> Reviewed-by: Guenter Roeck <linux@roeck-us.net> > --- > 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 68db322..aa85618 100644 > --- a/drivers/watchdog/qcom-wdt.c > +++ b/drivers/watchdog/qcom-wdt.c > @@ -11,11 +11,13 @@ > * > */ > #include <linux/clk.h> > +#include <linux/delay.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; > @@ -147,6 +176,14 @@ 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; > > @@ -159,6 +196,7 @@ 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; > -- To unsubscribe from this list: send the line "unsubscribe linux-arm-msm" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/drivers/watchdog/qcom-wdt.c b/drivers/watchdog/qcom-wdt.c index 68db322..aa85618 100644 --- a/drivers/watchdog/qcom-wdt.c +++ b/drivers/watchdog/qcom-wdt.c @@ -11,11 +11,13 @@ * */ #include <linux/clk.h> +#include <linux/delay.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; @@ -147,6 +176,14 @@ 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; @@ -159,6 +196,7 @@ 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;
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 | 38 ++++++++++++++++++++++++++++++++++++++ 1 file changed, 38 insertions(+)