rtc: isl12057: enable support for the standard "wakeup-source" property

Though the isl12057 rtc driver should and will continue to support the
legacy "isil,irq2-can-wakeup-machine" property to enable RTC as the
wakeup source, we need to add support for the new standard property
"wakeup-source".

This patch adds support for "wakeup-source" property in addition to the
existing "isil,irq2-can-wakeup-machine" property.

Cc: Alessandro Zummo <a.zummo@towertech.it>
Cc: Alexandre Belloni <alexandre.belloni@free-electrons.com>
Cc: rtc-linux@googlegroups.com
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>
Signed-off-by: Alexandre Belloni <alexandre.belloni@free-electrons.com>

drivers/rtc/rtc-isl12057.c

@@ -466,9 +466,8 @@ static int isl12057_check_rtc_status(struct device *dev, struct regmap *regmap)
  * is for instance the case on ReadyNAS 102, 104 and 2120. On those
  * devices with no IRQ driectly connected to the SoC, the RTC chip
  * can be forced as a wakeup source by stating that explicitly in
- * the device's .dts file using the "isil,irq2-can-wakeup-machine"
+ * the device's .dts file using the "wakeup-source" boolean property.
- * boolean property. This will guarantee 'wakealarm' sysfs entry is
+ * This will guarantee 'wakealarm' sysfs entry is available on the device.
- * available on the device.
  *
  * The function below returns 1, i.e. the capability of the chip to
  * wakeup the device, based on IRQ availability or if the boolean
@@ -479,8 +478,9 @@ static bool isl12057_can_wakeup_machine(struct device *dev)
 {
 	struct isl12057_rtc_data *data = dev_get_drvdata(dev);
 
-	return (data->irq || of_property_read_bool(dev->of_node,
+	return data->irq || of_property_read_bool(dev->of_node, "wakeup-source")
-					      "isil,irq2-can-wakeup-machine"));
+		|| of_property_read_bool(dev->of_node, /* legacy */
+					 "isil,irq2-can-wakeup-machine");
 }
 #else
 static bool isl12057_can_wakeup_machine(struct device *dev)