watchdog: da9062: Initialize timeout during probe

During probe try to set the timeout from device tree and fall back to
either the pre-configured timeout set by e.g. the bootloader in case the
watchdog is already running or the default value.

If the watchdog is already running make sure to update the timeout and
tell the framework about the running state to make sure the watchdog is
handled correctly until user space takes over. Updating the timeout also
removes the need for an additional manual ping so we can remove that as
well.

Signed-off-by: Stefan Riedmueller <s.riedmueller@phytec.de>
Reviewed-by: Adam Thomson <Adam.Thomson.Opensource@diasemi.com>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Link: https://lore.kernel.org/r/20200403130728.39260-1-s.riedmueller@phytec.de
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Wim Van Sebroeck <wim@linux-watchdog.org>

drivers/watchdog/da9062_wdt.c

@@ -35,6 +35,15 @@ struct da9062_watchdog {
 	bool use_sw_pm;
 };
 
+static unsigned int da9062_wdt_read_timeout(struct da9062_watchdog *wdt)
+{
+	unsigned int val;
+
+	regmap_read(wdt->hw->regmap, DA9062AA_CONTROL_D, &val);
+
+	return wdt_timeout[val & DA9062AA_TWDSCALE_MASK];
+}
+
 static unsigned int da9062_wdt_timeout_to_sel(unsigned int secs)
 {
 	unsigned int i;
@@ -183,7 +192,7 @@ MODULE_DEVICE_TABLE(of, da9062_compatible_id_table);
 static int da9062_wdt_probe(struct platform_device *pdev)
 {
 	struct device *dev = &pdev->dev;
-	int ret;
+	unsigned int timeout;
 	struct da9062 *chip;
 	struct da9062_watchdog *wdt;
 
@@ -213,11 +222,19 @@ static int da9062_wdt_probe(struct platform_device *pdev)
 	watchdog_set_drvdata(&wdt->wdtdev, wdt);
 	dev_set_drvdata(dev, &wdt->wdtdev);
 
-	ret = devm_watchdog_register_device(dev, &wdt->wdtdev);
-	if (ret < 0)
-		return ret;
+	timeout = da9062_wdt_read_timeout(wdt);
+	if (timeout)
+		wdt->wdtdev.timeout = timeout;
 
-	return da9062_wdt_ping(&wdt->wdtdev);
+	/* Set timeout from DT value if available */
+	watchdog_init_timeout(&wdt->wdtdev, 0, dev);
+
+	if (timeout) {
+		da9062_wdt_set_timeout(&wdt->wdtdev, wdt->wdtdev.timeout);
+		set_bit(WDOG_HW_RUNNING, &wdt->wdtdev.status);
+	}
+
+	return devm_watchdog_register_device(dev, &wdt->wdtdev);
 }
 
 static int __maybe_unused da9062_wdt_suspend(struct device *dev)