watchdog: mtk_wdt: add suspend/resume support

add mediatek watchdog driver suspend/resume support
Signed-off-by: Greta Zhang <greta.zhang@mediatek.com>
Signed-off-by: Roger Lu <roger.lu@mediatek.com>
Signed-off-by: Eddie Huang <eddie.huang@mediatek.com>
Acked-by: Matthias Brugger <matthias.bgg@gmail.com>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Wim Van Sebroeck <wim@iguana.be>

drivers/watchdog/mtk_wdt.c

@@ -221,17 +221,47 @@ static int mtk_wdt_remove(struct platform_device *pdev)
 	return 0;
 }
 
+#ifdef CONFIG_PM_SLEEP
+static int mtk_wdt_suspend(struct device *dev)
+{
+	struct mtk_wdt_dev *mtk_wdt = dev_get_drvdata(dev);
+
+	if (watchdog_active(&mtk_wdt->wdt_dev))
+		mtk_wdt_stop(&mtk_wdt->wdt_dev);
+
+	return 0;
+}
+
+static int mtk_wdt_resume(struct device *dev)
+{
+	struct mtk_wdt_dev *mtk_wdt = dev_get_drvdata(dev);
+
+	if (watchdog_active(&mtk_wdt->wdt_dev)) {
+		mtk_wdt_start(&mtk_wdt->wdt_dev);
+		mtk_wdt_ping(&mtk_wdt->wdt_dev);
+	}
+
+	return 0;
+}
+#endif
+
 static const struct of_device_id mtk_wdt_dt_ids[] = {
 	{ .compatible = "mediatek,mt6589-wdt" },
 	{ /* sentinel */ }
 };
 MODULE_DEVICE_TABLE(of, mtk_wdt_dt_ids);
 
+static const struct dev_pm_ops mtk_wdt_pm_ops = {
+	SET_SYSTEM_SLEEP_PM_OPS(mtk_wdt_suspend,
+				mtk_wdt_resume)
+};
+
 static struct platform_driver mtk_wdt_driver = {
 	.probe		= mtk_wdt_probe,
 	.remove		= mtk_wdt_remove,
 	.driver		= {
 		.name		= DRV_NAME,
+		.pm		= &mtk_wdt_pm_ops,
 		.of_match_table	= mtk_wdt_dt_ids,
 	},
 };