[PATCH 4.9 70/71] rtc: m41t80: Correct alarm month range with RTC reads

[Greg Kroah-Hartman]

4.9-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Maciej W. Rozycki <macro@xxxxxxxxxxxxxx>

commit 3cc9ffbb1f51eb4320575a48e4805a8f52e0e26b upstream.

Add the missing adjustment of the month range on alarm reads from the
RTC, correcting an issue coming from commit 9c6dfed92c3e ("rtc: m41t80:
add alarm functionality").  The range is 1-12 for hardware and 0-11 for
`struct rtc_time', and is already correctly handled on alarm writes to
the RTC.

It was correct up until commit 48e9766726eb ("drivers/rtc/rtc-m41t80.c:
remove disabled alarm functionality") too, which removed the previous
implementation of alarm support.

Signed-off-by: Maciej W. Rozycki <macro@xxxxxxxxxxxxxx>
Fixes: 9c6dfed92c3e ("rtc: m41t80: add alarm functionality")
References: 48e9766726eb ("drivers/rtc/rtc-m41t80.c: remove disabled alarm functionality")
Cc: stable@xxxxxxxxxxxxxxx # 4.7+
Signed-off-by: Alexandre Belloni <alexandre.belloni@xxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 drivers/rtc/rtc-m41t80.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/drivers/rtc/rtc-m41t80.c
+++ b/drivers/rtc/rtc-m41t80.c
@@ -333,7 +333,7 @@ static int m41t80_read_alarm(struct devi
 	alrm->time.tm_min  = bcd2bin(alarmvals[3] & 0x7f);
 	alrm->time.tm_hour = bcd2bin(alarmvals[2] & 0x3f);
 	alrm->time.tm_mday = bcd2bin(alarmvals[1] & 0x3f);
-	alrm->time.tm_mon  = bcd2bin(alarmvals[0] & 0x3f);
+	alrm->time.tm_mon  = bcd2bin(alarmvals[0] & 0x3f) - 1;
 
 	alrm->enabled = !!(alarmvals[0] & M41T80_ALMON_AFE);
 	alrm->pending = (flags & M41T80_FLAGS_AF) && alrm->enabled;