watchdog: imx2_wdt: Add power management support.

Add power management operations(suspend and resume) as part of
dev_pm_ops for IMX2 watchdog driver.

Signed-off-by: Xiubo Li <Li.Xiubo@freescale.com>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Wim Van Sebroeck <wim@iguana.be>

drivers/watchdog/imx2_wdt.c

@@ -326,6 +326,52 @@ static void imx2_wdt_shutdown(struct platform_device *pdev)
 	}
 }
 
+#ifdef CONFIG_PM_SLEEP
+/* Disable watchdog if it is active during suspend */
+static int imx2_wdt_suspend(struct device *dev)
+{
+	struct watchdog_device *wdog = dev_get_drvdata(dev);
+	struct imx2_wdt_device *wdev = watchdog_get_drvdata(wdog);
+
+	imx2_wdt_set_timeout(wdog, IMX2_WDT_MAX_TIME);
+	imx2_wdt_ping(wdog);
+
+	/* Watchdog has been stopped but IP block is still running */
+	if (!watchdog_active(&wdog) && imx2_wdt_is_running(wdev))
+		del_timer_sync(&wdev->timer);
+
+	clk_disable_unprepare(wdev->clk);
+
+	return 0;
+}
+
+/* Enable watchdog and configure it if necessary */
+static int imx2_wdt_resume(struct device *dev)
+{
+	struct watchdog_device *wdog = dev_get_drvdata(dev);
+	struct imx2_wdt_device *wdev = watchdog_get_drvdata(wdog);
+
+	clk_prepare_enable(wdev->clk);
+
+	if (watchdog_active(wdog) && !imx2_wdt_is_running(wdev)) {
+		/* Resumes from deep sleep we need restart
+		 * the watchdog again.
+		 */
+		imx2_wdt_setup(wdog);
+		imx2_wdt_set_timeout(wdog, wdog->timeout);
+		imx2_wdt_ping(wdog);
+	} else if (imx2_wdt_is_running(wdev)) {
+		imx2_wdt_ping(wdog);
+		mod_timer(&wdev->timer, jiffies + wdog->timeout * HZ / 2);
+	}
+
+	return 0;
+}
+#endif
+
+static SIMPLE_DEV_PM_OPS(imx2_wdt_pm_ops, imx2_wdt_suspend,
+			 imx2_wdt_resume);
+
 static const struct of_device_id imx2_wdt_dt_ids[] = {
 	{ .compatible = "fsl,imx21-wdt", },
 	{ /* sentinel */ }
@@ -337,6 +383,7 @@ static struct platform_driver imx2_wdt_driver = {
 	.shutdown	= imx2_wdt_shutdown,
 	.driver		= {
 		.name	= DRIVER_NAME,
+		.pm     = &imx2_wdt_pm_ops,
 		.of_match_table = imx2_wdt_dt_ids,
 	},
 };