rtc: tps65910: allow using RTC without alarm interrupt

If tps65910 INT1 pin (IRQ output) is not wired to any IRQ controller,
then it can't be used as system wakeup/alarm source,
but it is still possible to read/write time from/to RTC.
Signed-off-by: Andrey Skvortsov <andrej.skvortzov@gmail.com>
Link: https://lore.kernel.org/r/20191116203748.27166-1-andrej.skvortzov@gmail.comSigned-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>

drivers/rtc/rtc-tps65910.c

@@ -361,6 +361,13 @@ static const struct rtc_class_ops tps65910_rtc_ops = {
 	.set_offset	= tps65910_set_offset,
 };
 
+static const struct rtc_class_ops tps65910_rtc_ops_noirq = {
+	.read_time	= tps65910_rtc_read_time,
+	.set_time	= tps65910_rtc_set_time,
+	.read_offset	= tps65910_read_offset,
+	.set_offset	= tps65910_set_offset,
+};
+
 static int tps65910_rtc_probe(struct platform_device *pdev)
 {
 	struct tps65910 *tps65910 = NULL;
@@ -414,14 +421,16 @@ static int tps65910_rtc_probe(struct platform_device *pdev)
 	ret = devm_request_threaded_irq(&pdev->dev, irq, NULL,
 		tps65910_rtc_interrupt, IRQF_TRIGGER_LOW,
 		dev_name(&pdev->dev), &pdev->dev);
-	if (ret < 0) {
-		dev_err(&pdev->dev, "IRQ is not free.\n");
-		return ret;
-	}
+	if (ret < 0)
+		irq = -1;
+
 	tps_rtc->irq = irq;
+	if (irq != -1) {
 		device_set_wakeup_capable(&pdev->dev, 1);
-
 		tps_rtc->rtc->ops = &tps65910_rtc_ops;
+	} else
+		tps_rtc->rtc->ops = &tps65910_rtc_ops_noirq;
+
 	tps_rtc->rtc->range_min = RTC_TIMESTAMP_BEGIN_2000;
 	tps_rtc->rtc->range_max = RTC_TIMESTAMP_END_2099;