diff options
| author | Atsushi Nemoto <anemo@mba.ocn.ne.jp> | 2012-08-21 16:16:10 -0700 |
|---|---|---|
| committer | Ben Hutchings <ben@decadent.org.uk> | 2012-09-12 03:37:26 +0100 |
| commit | 05621c97f432220a529abd1356b4b902a8e3aecd (patch) | |
| tree | 5d6891a6eb67ea410c5204bd7044c79b2d86918d /drivers/rtc | |
| parent | 33da4c1e160850964ea658643ea4f06e508c0d2e (diff) | |
drivers/rtc/rtc-rs5c348.c: fix hour decoding in 12-hour mode
commit 7dbfb315b2aaef0a115765946bf3026d074c33a7 upstream.
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>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
Diffstat (limited to 'drivers/rtc')
| -rw-r--r-- | drivers/rtc/rtc-rs5c348.c | 7 |
1 files changed, 5 insertions, 2 deletions
diff --git a/drivers/rtc/rtc-rs5c348.c b/drivers/rtc/rtc-rs5c348.c index 971bc8e08da..11bcb2076a2 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); |