diff --git a/drivers/rtc/rtc-cmos.c b/drivers/rtc/rtc-cmos.c
index df0c5776d49b..a5a19ff10535 100644
--- a/drivers/rtc/rtc-cmos.c
+++ b/drivers/rtc/rtc-cmos.c
@@ -257,6 +257,7 @@ static int cmos_read_alarm(struct device *dev, struct rtc_wkalrm *t)
 	struct cmos_rtc	*cmos = dev_get_drvdata(dev);
 	unsigned char	rtc_control;
 
+	/* This not only a rtc_op, but also called directly */
 	if (!is_valid_irq(cmos->irq))
 		return -EIO;
 
@@ -452,6 +453,7 @@ static int cmos_set_alarm(struct device *dev, struct rtc_wkalrm *t)
 	unsigned char mon, mday, hrs, min, sec, rtc_control;
 	int ret;
 
+	/* This not only a rtc_op, but also called directly */
 	if (!is_valid_irq(cmos->irq))
 		return -EIO;
 
@@ -516,9 +518,6 @@ static int cmos_alarm_irq_enable(struct device *dev, unsigned int enabled)
 	struct cmos_rtc	*cmos = dev_get_drvdata(dev);
 	unsigned long	flags;
 
-	if (!is_valid_irq(cmos->irq))
-		return -EINVAL;
-
 	spin_lock_irqsave(&rtc_lock, flags);
 
 	if (enabled)
@@ -579,6 +578,12 @@ static const struct rtc_class_ops cmos_rtc_ops = {
 	.alarm_irq_enable	= cmos_alarm_irq_enable,
 };
 
+static const struct rtc_class_ops cmos_rtc_ops_no_alarm = {
+	.read_time		= cmos_read_time,
+	.set_time		= cmos_set_time,
+	.proc			= cmos_procfs,
+};
+
 /*----------------------------------------------------------------*/
 
 /*
@@ -855,9 +860,12 @@ cmos_do_probe(struct device *dev, struct resource *ports, int rtc_irq)
 			dev_dbg(dev, "IRQ %d is already in use\n", rtc_irq);
 			goto cleanup1;
 		}
+
+		cmos_rtc.rtc->ops = &cmos_rtc_ops;
+	} else {
+		cmos_rtc.rtc->ops = &cmos_rtc_ops_no_alarm;
 	}
 
-	cmos_rtc.rtc->ops = &cmos_rtc_ops;
 	cmos_rtc.rtc->nvram_old_abi = true;
 	retval = rtc_register_device(cmos_rtc.rtc);
 	if (retval)