rtc: ds1307: fix alarm reading at probe time

With the actual code, read_alarm() always returns -EINVAL when called
during the RTC device registration. This prevents from retrieving an
already configured alarm in hardware.

This patch fixes the issue by moving the HAS_ALARM bit configuration
(if supported by the hardware) above the rtc_device_register() call.
Signed-off-by: Simon Guinot <simon.guinot@sequanux.org>
Signed-off-by: Alexandre Belloni <alexandre.belloni@free-electrons.com>

drivers/rtc/rtc-ds1307.c

@@ -1134,7 +1134,10 @@ static int ds1307_probe(struct i2c_client *client,
 				bin2bcd(tmp));
 	}
 
-	device_set_wakeup_capable(&client->dev, want_irq);
+	if (want_irq) {
+		device_set_wakeup_capable(&client->dev, true);
+		set_bit(HAS_ALARM, &ds1307->flags);
+	}
 	ds1307->rtc = devm_rtc_device_register(&client->dev, client->name,
 				rtc_ops, THIS_MODULE);
 	if (IS_ERR(ds1307->rtc)) {
@@ -1148,13 +1151,12 @@ static int ds1307_probe(struct i2c_client *client,
 						ds1307->rtc->name, client);
 		if (err) {
 			client->irq = 0;
+			device_set_wakeup_capable(&client->dev, false);
+			clear_bit(HAS_ALARM, &ds1307->flags);
 			dev_err(&client->dev, "unable to request IRQ!\n");
-		} else {
-
-			set_bit(HAS_ALARM, &ds1307->flags);
+		} else
 			dev_dbg(&client->dev, "got IRQ %d\n", client->irq);
 	}
-	}
 
 	if (chip->nvram_size) {