watchdog: qcom_wdt: set WDOG_HW_RUNNING bit when appropriate

If the watchdog hardware is enabled/running during boot, e.g.
due to a boot loader configuring it, we must tell the
watchdog framework about this fact so that it can ping the
watchdog until userspace opens the device and takes over
control.

Do so using the WDOG_HW_RUNNING flag that exists for exactly
that use-case.

Signed-off-by: Robert Marko <[email protected]>
Cc: Luka Perkov <[email protected]>
Reviewed-by: Guenter Roeck <[email protected]>
Reviewed-by: Bjorn Andersson <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Guenter Roeck <[email protected]>
Signed-off-by: Wim Van Sebroeck <[email protected]>

1 files changed, 18 insertions, 0 deletions

diff --git a/drivers/watchdog/qcom-wdt.c b/drivers/watchdog/qcom-wdt.c
index ab7465d186fd..07d399c4edc4 100644
--- a/drivers/watchdog/qcom-wdt.c
+++ b/drivers/watchdog/qcom-wdt.c
@@ -152,6 +152,13 @@ static int qcom_wdt_restart(struct watchdog_device *wdd, unsigned long action,
 	return 0;
 }
 
+static int qcom_wdt_is_running(struct watchdog_device *wdd)
+{
+	struct qcom_wdt *wdt = to_qcom_wdt(wdd);
+
+	return (readl(wdt_addr(wdt, WDT_EN)) & QCOM_WDT_ENABLE);
+}
+
 static const struct watchdog_ops qcom_wdt_ops = {
 	.start		= qcom_wdt_start,
 	.stop		= qcom_wdt_stop,
@@ -294,6 +301,17 @@ static int qcom_wdt_probe(struct platform_device *pdev)
 	wdt->wdd.timeout = min(wdt->wdd.max_timeout, 30U);
 	watchdog_init_timeout(&wdt->wdd, 0, dev);
 
+	/*
+	 * If WDT is already running, call WDT start which
+	 * will stop the WDT, set timeouts as bootloader
+	 * might use different ones and set running bit
+	 * to inform the WDT subsystem to ping the WDT
+	 */
+	if (qcom_wdt_is_running(&wdt->wdd)) {
+		qcom_wdt_start(&wdt->wdd);
+		set_bit(WDOG_HW_RUNNING, &wdt->wdd.status);
+	}
+
 	ret = devm_watchdog_register_device(dev, &wdt->wdd);
 	if (ret)
 		return ret;