rtc: opal: set range

It is a BCD RTC with 4 digits for the year.
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
Link: https://lore.kernel.org/r/20210110224606.1414307-1-alexandre.belloni@bootlin.com

drivers/rtc/rtc-opal.c

@@ -233,6 +233,10 @@ static int opal_rtc_probe(struct platform_device *pdev)
 {
 	struct rtc_device *rtc;
 
+	rtc = devm_rtc_allocate_device(&pdev->dev);
+	if (IS_ERR(rtc))
+		return PTR_ERR(rtc);
+
 	if (pdev->dev.of_node &&
 	    (of_property_read_bool(pdev->dev.of_node, "wakeup-source") ||
 	     of_property_read_bool(pdev->dev.of_node, "has-tpo")/* legacy */)) {
@@ -242,14 +246,12 @@ static int opal_rtc_probe(struct platform_device *pdev)
 		opal_rtc_ops.alarm_irq_enable = opal_tpo_alarm_irq_enable;
 	}
 
-	rtc = devm_rtc_device_register(&pdev->dev, DRVNAME, &opal_rtc_ops,
-				       THIS_MODULE);
-	if (IS_ERR(rtc))
-		return PTR_ERR(rtc);
-
+	rtc->ops = &opal_rtc_ops;
+	rtc->range_min = RTC_TIMESTAMP_BEGIN_0000;
+	rtc->range_max = RTC_TIMESTAMP_END_9999;
 	rtc->uie_unsupported = 1;
 
-	return 0;
+	return devm_rtc_register_device(rtc);
 }
 
 static const struct of_device_id opal_rtc_match[] = {