watchdog: rzg2l_wdt: Add suspend/resume support

The RZ/G3S supports deep sleep states where power to most of the IP blocks
is cut off. To ensure proper working of the watchdog when resuming from
such states, the suspend function is stopping the watchdog and the resume
function is starting it. There is no need to configure the watchdog
in case the watchdog was stopped prior to starting suspend.
Signed-off-by: Claudiu Beznea <claudiu.beznea.uj@bp.renesas.com>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Link: https://lore.kernel.org/r/20240531065723.1085423-9-claudiu.beznea.uj@bp.renesas.comSigned-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Wim Van Sebroeck <wim@linux-watchdog.org>

drivers/watchdog/rzg2l_wdt.c

@@ -286,6 +286,7 @@ static int rzg2l_wdt_probe(struct platform_device *pdev)
 	priv->wdev.timeout = WDT_DEFAULT_TIMEOUT;
 
 	watchdog_set_drvdata(&priv->wdev, priv);
+	dev_set_drvdata(dev, priv);
 	ret = devm_add_action_or_reset(&pdev->dev, rzg2l_wdt_pm_disable, &priv->wdev);
 	if (ret)
 		return ret;
@@ -307,10 +308,35 @@ static const struct of_device_id rzg2l_wdt_ids[] = {
 };
 MODULE_DEVICE_TABLE(of, rzg2l_wdt_ids);
 
+static int rzg2l_wdt_suspend_late(struct device *dev)
+{
+	struct rzg2l_wdt_priv *priv = dev_get_drvdata(dev);
+
+	if (!watchdog_active(&priv->wdev))
+		return 0;
+
+	return rzg2l_wdt_stop(&priv->wdev);
+}
+
+static int rzg2l_wdt_resume_early(struct device *dev)
+{
+	struct rzg2l_wdt_priv *priv = dev_get_drvdata(dev);
+
+	if (!watchdog_active(&priv->wdev))
+		return 0;
+
+	return rzg2l_wdt_start(&priv->wdev);
+}
+
+static const struct dev_pm_ops rzg2l_wdt_pm_ops = {
+	LATE_SYSTEM_SLEEP_PM_OPS(rzg2l_wdt_suspend_late, rzg2l_wdt_resume_early)
+};
+
 static struct platform_driver rzg2l_wdt_driver = {
 	.driver = {
 		.name = "rzg2l_wdt",
 		.of_match_table = rzg2l_wdt_ids,
+		.pm = &rzg2l_wdt_pm_ops,
 	},
 	.probe = rzg2l_wdt_probe,
 };