| Message ID | 2dc54244e755eeacf8265a484819e0c2e2393221.1411667144.git.joshc@codeaurora.org (mailing list archive) |
|---|---|
| State | Superseded, archived |
| Headers | show |
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 <joshc@codeaurora.org> > --- > 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 > -- 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
On Thu, Sep 25, 2014 at 11:41:49AM -0700, Guenter Roeck wrote: > 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 <joshc@codeaurora.org> > > --- > > 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. That was my intent, but apparently I fail at the alphabet :). Normally instead of thinking I pipe the #include list through 'sort'. Not sure why I didn't do so this time around. Thanks, Josh
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> #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;
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(+)