Input: egalax_ts - add system wakeup support

This patch adds wakeup function support for egalax touch
screen, if "wakeup-source" is added to device tree's egalax
touch screen node, the wakeup function will be enabled, and
egalax touch screen will be able to wakeup system from suspend.
Signed-off-by: Anson Huang <Anson.Huang@nxp.com>
Reviewed-by: Fabio Estevam <fabio.estevam@nxp.com>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>

drivers/input/touchscreen/egalax_ts.c

@@ -241,6 +241,9 @@ static int __maybe_unused egalax_ts_suspend(struct device *dev)
 	struct i2c_client *client = to_i2c_client(dev);
 	int ret;
 
+	if (device_may_wakeup(dev))
+		return enable_irq_wake(client->irq);
+
 	ret = i2c_master_send(client, suspend_cmd, MAX_I2C_DATA_LEN);
 	return ret > 0 ? 0 : ret;
 }
@@ -249,6 +252,9 @@ static int __maybe_unused egalax_ts_resume(struct device *dev)
 {
 	struct i2c_client *client = to_i2c_client(dev);
 
+	if (device_may_wakeup(dev))
+		return disable_irq_wake(client->irq);
+
 	return egalax_wake_up_device(client);
 }