rtc: pcf85363: Allow to wake up system without IRQ

When wakeup-source is set in the devicetree, set up the device for
using the output as interrupt instead of clock. This is similar to
how other RTC devices handle this.

This allows the clock chip to turn on the board when wired to do
so in hardware.

Signed-off-by: Mike Looijmans <mike.looijmans@topic.nl>
Link: https://lore.kernel.org/r/20230821072013.7072-1-mike.looijmans@topic.nl
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>

Author: MikeLooijmans

drivers/rtc/rtc-pcf85363.c

@@ -402,6 +402,7 @@ static int pcf85363_probe(struct i2c_client *client)
 		},
 	};
 	int ret, i, err;
+	bool wakeup_source;
 
 	if (data)
 		config = data;
@@ -431,25 +432,36 @@ static int pcf85363_probe(struct i2c_client *client)
 	pcf85363->rtc->ops = &rtc_ops;
 	pcf85363->rtc->range_min = RTC_TIMESTAMP_BEGIN_2000;
 	pcf85363->rtc->range_max = RTC_TIMESTAMP_END_2099;
-	clear_bit(RTC_FEATURE_ALARM, pcf85363->rtc->features);
+
+	wakeup_source = device_property_read_bool(&client->dev,
+						  "wakeup-source");
+	if (client->irq > 0 || wakeup_source) {
+		regmap_write(pcf85363->regmap, CTRL_FLAGS, 0);
+		regmap_update_bits(pcf85363->regmap, CTRL_PIN_IO,
+				   PIN_IO_INTA_OUT, PIN_IO_INTAPM);
+	}
 
 	if (client->irq > 0) {
 		unsigned long irqflags = IRQF_TRIGGER_LOW;
 
 		if (dev_fwnode(&client->dev))
 			irqflags = 0;
-
-		regmap_write(pcf85363->regmap, CTRL_FLAGS, 0);
-		regmap_update_bits(pcf85363->regmap, CTRL_PIN_IO,
-				   PIN_IO_INTA_OUT, PIN_IO_INTAPM);
 		ret = devm_request_threaded_irq(&client->dev, client->irq,
 						NULL, pcf85363_rtc_handle_irq,
 						irqflags | IRQF_ONESHOT,
 						"pcf85363", client);
-		if (ret)
-			dev_warn(&client->dev, "unable to request IRQ, alarms disabled\n");
-		else
-			set_bit(RTC_FEATURE_ALARM, pcf85363->rtc->features);
+		if (ret) {
+			dev_warn(&client->dev,
+				 "unable to request IRQ, alarms disabled\n");
+			client->irq = 0;
+		}
+	}
+
+	if (client->irq > 0 || wakeup_source) {
+		device_init_wakeup(&client->dev, true);
+		set_bit(RTC_FEATURE_ALARM, pcf85363->rtc->features);
+	} else {
+		clear_bit(RTC_FEATURE_ALARM, pcf85363->rtc->features);
 	}
 
 	ret = devm_rtc_register_device(pcf85363->rtc);