rtc: pm8xxx: clear alarm register when alarm is not enabled

Clear alarm register when alarm is not enabled otherwise the consumer
may still start alarm timer if it find the alarm register is not zero.
Signed-off-by: hankecai <hankecai@vivo.com>
Link: https://lore.kernel.org/r/APoAZgAaCEiRpKG6PlzreaqE.1.1584791417367.Hmail.hankecai@vivo.comSigned-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>

drivers/rtc/rtc-pm8xxx.c

@@ -295,6 +295,7 @@ static int pm8xxx_rtc_alarm_irq_enable(struct device *dev, unsigned int enable)
 	struct pm8xxx_rtc *rtc_dd = dev_get_drvdata(dev);
 	const struct pm8xxx_rtc_regs *regs = rtc_dd->regs;
 	unsigned int ctrl_reg;
+	u8 value[NUM_8_BIT_RTC_REGS] = {0};
 
 	spin_lock_irqsave(&rtc_dd->ctrl_reg_lock, irq_flags);
 
@@ -313,6 +314,16 @@ static int pm8xxx_rtc_alarm_irq_enable(struct device *dev, unsigned int enable)
 		goto rtc_rw_fail;
 	}
 
+	/* Clear Alarm register */
+	if (!enable) {
+		rc = regmap_bulk_write(rtc_dd->regmap, regs->alarm_rw, value,
+				       sizeof(value));
+		if (rc) {
+			dev_err(dev, "Clear RTC ALARM register failed\n");
+			goto rtc_rw_fail;
+		}
+	}
+
 rtc_rw_fail:
 	spin_unlock_irqrestore(&rtc_dd->ctrl_reg_lock, irq_flags);
 	return rc;