[PATCH v6 06/17] rtc: rzn1: Disable alarm interrupt before reprogramming alarm registers

[Prabhakar]

From: Lad Prabhakar <prabhakar.mahadev-lad.rj@xxxxxxxxxxxxxx>

rzn1_rtc_set_alarm() updates RZN1_RTC_ALM, RZN1_RTC_ALH and
RZN1_RTC_ALW using separate MMIO writes without first disabling the
alarm interrupt. If a previous alarm is still enabled, the interrupt
can fire while the alarm registers contain a mixture of old and newly
written values.

Fix this by disabling the alarm interrupt before reprogramming ALM, ALH
and ALW with a call to rzn1_rtc_alarm_irq_enable().

Fixes: b5ad1bf00d2c4 ("rtc: rzn1: Add alarm support")
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@xxxxxxxxxxxxxx>
Reviewed-by: Wolfram Sang <wsa+renesas@xxxxxxxxxxxxxxxxxxxx>
Tested-by: Wolfram Sang <wsa+renesas@xxxxxxxxxxxxxxxxxxxx>
---
v5->v6:
- Added Reviewed-by and Tested-by tags from Wolfram.

v4->v5:
- New patch
---
 drivers/rtc/rtc-rzn1.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/drivers/rtc/rtc-rzn1.c b/drivers/rtc/rtc-rzn1.c
index f3268655fd37..42e57bf0b4aa 100644
--- a/drivers/rtc/rtc-rzn1.c
+++ b/drivers/rtc/rtc-rzn1.c
@@ -281,6 +281,11 @@ static int rzn1_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alrm)
 	if (alarm > farest)
 		return -ERANGE;
 
+	/* Disable alarm interrupts before reprogramming the alarm. */
+	ret = rzn1_rtc_alarm_irq_enable(dev, 0);
+	if (ret)
+		return ret;
+
 	writel(bin2bcd(tm->tm_min), rtc->base + RZN1_RTC_ALM);
 	writel(bin2bcd(tm->tm_hour), rtc->base + RZN1_RTC_ALH);
 	writel(BIT(tm->tm_wday), rtc->base + RZN1_RTC_ALW);
-- 
2.43.0