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@xxxxxxxxxxxxxx>
Reviewed-by: Guenter Roeck <linux@xxxxxxxxxxxx>
---
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;
--
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