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authorAtsushi Nemoto <anemo@mba.ocn.ne.jp>2012-08-21 16:16:10 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2012-08-21 16:45:03 -0700
commit7dbfb315b2aaef0a115765946bf3026d074c33a7 (patch)
treec3fe42971fbd713a1bc7bc263410a4eaec8521fc /drivers/rtc
parentb121186ab1b12e2a96a945d88eae0735b4542158 (diff)
drivers/rtc/rtc-rs5c348.c: fix hour decoding in 12-hour mode
Correct the offset by subtracting 20 from tm_hour before taking the modulo 12. [ "Why 20?" I hear you ask. Or at least I did. Here's the reason why: RS5C348_BIT_PM is 32, and is - stupidly - included in the RS5C348_HOURS_MASK define. So it's really subtracting out that bit to get "hour+12". But then because it does things modulo 12, it needs to add the 12 in again afterwards anyway. This code is confused. It would be much clearer if RS5C348_HOURS_MASK just didn't include the RS5C348_BIT_PM bit at all, then it wouldn't need to do the silly subtract either. Whatever. It's all just math, the end result is the same. - Linus ] Reported-by: James Nute <newten82@gmail.com> Tested-by: James Nute <newten82@gmail.com> Signed-off-by: Atsushi Nemoto <anemo@mba.ocn.ne.jp> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'drivers/rtc')
-rw-r--r--drivers/rtc/rtc-rs5c348.c7
1 files changed, 5 insertions, 2 deletions
diff --git a/drivers/rtc/rtc-rs5c348.c b/drivers/rtc/rtc-rs5c348.c
index 77074ccd2850..fd5c7af04ae5 100644
--- a/drivers/rtc/rtc-rs5c348.c
+++ b/drivers/rtc/rtc-rs5c348.c
@@ -122,9 +122,12 @@ rs5c348_rtc_read_time(struct device *dev, struct rtc_time *tm)
tm->tm_min = bcd2bin(rxbuf[RS5C348_REG_MINS] & RS5C348_MINS_MASK);
tm->tm_hour = bcd2bin(rxbuf[RS5C348_REG_HOURS] & RS5C348_HOURS_MASK);
if (!pdata->rtc_24h) {
- tm->tm_hour %= 12;
- if (rxbuf[RS5C348_REG_HOURS] & RS5C348_BIT_PM)
+ if (rxbuf[RS5C348_REG_HOURS] & RS5C348_BIT_PM) {
+ tm->tm_hour -= 20;
+ tm->tm_hour %= 12;
tm->tm_hour += 12;
+ } else
+ tm->tm_hour %= 12;
}
tm->tm_wday = bcd2bin(rxbuf[RS5C348_REG_WDAY] & RS5C348_WDAY_MASK);
tm->tm_mday = bcd2bin(rxbuf[RS5C348_REG_DAY] & RS5C348_DAY_MASK);