rtc: fix ds1388 time corruption

commit 96fc3a45ea073136566f3c2676cad52f8b39a7df upstream.

The ds1307 driver misreads the ds1388 registers when checking for 12 or 24
hour mode.  Instead of checking the hour register it reads the minute
register.  Therefore the driver thinks minutes >= 40 has the 12HR bit set
and resets the minute register by zeroing the high bits.  This results in
minutes are reset to 0-9, jumping back in time 40 or 50 minutes.  The time
jump is also written back to the RTC.

Signed-off-by: Joakim Tjernlund <Joakim.Tjernlund@transmode.se>
Cc: Wan ZongShun <mcuos.com@gmail.com>
Cc: Alessandro Zummo <a.zummo@towertech.it>
Cc: Paul Gortmaker <p_gortmaker@yahoo.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

diff --git a/drivers/rtc/rtc-ds1307.c b/drivers/rtc/rtc-ds1307.c
index eb99ee4fa0f5778a39e4faddd892766b06d0f078..861d91d012e053a4c4907015a93e67ea436318b3 100644 (file)
--- a/drivers/rtc/rtc-ds1307.c
+++ b/drivers/rtc/rtc-ds1307.c
@@ -775,7 +775,7 @@ static int __devinit ds1307_probe(struct i2c_client *client,
 
 read_rtc:
        /* read RTC registers */
-       tmp = ds1307->read_block_data(ds1307->client, 0, 8, buf);
+       tmp = ds1307->read_block_data(ds1307->client, ds1307->offset, 8, buf);
        if (tmp != 8) {
                pr_debug("read error %d\n", tmp);
                err = -EIO;
@@ -860,7 +860,7 @@ read_rtc:
                if (ds1307->regs[DS1307_REG_HOUR] & DS1307_BIT_PM)
                        tmp += 12;
                i2c_smbus_write_byte_data(client,
-                               DS1307_REG_HOUR,
+                               ds1307->offset + DS1307_REG_HOUR,
                                bin2bcd(tmp));
        }