[PATCH 4.14 28/75] rtc: sh: Fix invalid alarm warning for non-enabled alarm

From: Greg Kroah-Hartman
Date: Mon May 06 2019 - 10:45:15 EST

[ Upstream commit 15d82d22498784966df8e4696174a16b02cc1052 ]

When no alarm has been programmed on RSK-RZA1, an error message is
printed during boot:

rtc rtc0: invalid alarm value: 2019-03-14T255:255:255

sh_rtc_read_alarm_value() returns 0xff when querying a hardware alarm
field that is not enabled. __rtc_read_alarm() validates the received
alarm values, and fills in missing fields when needed.
While 0xff is handled fine for the year, month, and day fields, and
corrected as considered being out-of-range, this is not the case for the
hour, minute, and second fields, where -1 is expected for missing

Fix this by returning -1 instead, as this value is handled fine for all

Signed-off-by: Geert Uytterhoeven <geert+renesas@xxxxxxxxx>
Signed-off-by: Alexandre Belloni <alexandre.belloni@xxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
drivers/rtc/rtc-sh.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/rtc/rtc-sh.c b/drivers/rtc/rtc-sh.c
index 6c2d3989f967..9b6a927149a4 100644
--- a/drivers/rtc/rtc-sh.c
+++ b/drivers/rtc/rtc-sh.c
@@ -462,7 +462,7 @@ static int sh_rtc_set_time(struct device *dev, struct rtc_time *tm)
static inline int sh_rtc_read_alarm_value(struct sh_rtc *rtc, int reg_off)
unsigned int byte;
- int value = 0xff; /* return 0xff for ignored values */
+ int value = -1; /* return -1 for ignored values */

byte = readb(rtc->regbase + reg_off);
if (byte & AR_ENB) {