rtc: m41t80: add suspend handlers for alarm IRQ

Allow the alarm IRQ of RTC to be used as a wakeup source for the system
suspend.

Signed-off-by: Stefan Christ <s.christ@phytec.de>
Signed-off-by: Alexandre Belloni <alexandre.belloni@free-electrons.com>

drivers/rtc/rtc-m41t80.c

@@ -335,6 +335,30 @@ static struct rtc_class_ops m41t80_rtc_ops = {
 	.proc = m41t80_rtc_proc,
 };
 
+#ifdef CONFIG_PM_SLEEP
+static int m41t80_suspend(struct device *dev)
+{
+	struct i2c_client *client = to_i2c_client(dev);
+
+	if (client->irq >= 0 && device_may_wakeup(dev))
+		enable_irq_wake(client->irq);
+
+	return 0;
+}
+
+static int m41t80_resume(struct device *dev)
+{
+	struct i2c_client *client = to_i2c_client(dev);
+
+	if (client->irq >= 0 && device_may_wakeup(dev))
+		disable_irq_wake(client->irq);
+
+	return 0;
+}
+#endif
+
+static SIMPLE_DEV_PM_OPS(m41t80_pm, m41t80_suspend, m41t80_resume);
+
 static ssize_t flags_show(struct device *dev,
 			  struct device_attribute *attr, char *buf)
 {
@@ -870,6 +894,7 @@ static int m41t80_remove(struct i2c_client *client)
 static struct i2c_driver m41t80_driver = {
 	.driver = {
 		.name = "rtc-m41t80",
+		.pm = &m41t80_pm,
 	},
 	.probe = m41t80_probe,
 	.remove = m41t80_remove,