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authorFeng Tang <feng.tang@intel.com>2011-11-10 13:23:39 +0000
committerLinus Torvalds <torvalds@linux-foundation.org>2011-11-11 23:58:58 -0200
commit57e6319dd61d5ca10fe8dd57bcce8c0e2c480799 (patch)
tree906c40cec199f96f657a1e782fdc4dfcfdc81ade
parentf2ee442115c9b6219083c019939a9cc0c9abb2f8 (diff)
downloadlinux-linaro-stable-57e6319dd61d5ca10fe8dd57bcce8c0e2c480799.tar.gz
vrtc: change its year offset from 1960 to 1972
Real world year equals the value in vrtc YEAR register plus an offset. We used 1960 as the offset to make leap year consistent, but for a device's first use, its YEAR register is 0 and the system year will be parsed as 1960 which is not a valid UNIX time and will cause many applications to fail mysteriously. So we use 1972 instead to fix this issue. Updated patch which adds a sanity check suggested by Mathias This isn't a change in behaviour for systems, because 1972 is the one we actually use. It's the old version in upstream which is out of sync with all devices. Signed-off-by: Feng Tang <feng.tang@intel.com> Signed-off-by: Alan Cox <alan@linux.intel.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-rw-r--r--arch/x86/platform/mrst/vrtc.c4
-rw-r--r--drivers/rtc/rtc-mrst.c19
2 files changed, 13 insertions, 10 deletions
diff --git a/arch/x86/platform/mrst/vrtc.c b/arch/x86/platform/mrst/vrtc.c
index a8ac6f1eb66d..225bd0f0f675 100644
--- a/arch/x86/platform/mrst/vrtc.c
+++ b/arch/x86/platform/mrst/vrtc.c
@@ -76,8 +76,8 @@ unsigned long vrtc_get_time(void)
spin_unlock_irqrestore(&rtc_lock, flags);
- /* vRTC YEAR reg contains the offset to 1960 */
- year += 1960;
+ /* vRTC YEAR reg contains the offset to 1972 */
+ year += 1972;
printk(KERN_INFO "vRTC: sec: %d min: %d hour: %d day: %d "
"mon: %d year: %d\n", sec, min, hour, mday, mon, year);
diff --git a/drivers/rtc/rtc-mrst.c b/drivers/rtc/rtc-mrst.c
index d33544802a2e..bb21f443fb70 100644
--- a/drivers/rtc/rtc-mrst.c
+++ b/drivers/rtc/rtc-mrst.c
@@ -76,12 +76,15 @@ static inline unsigned char vrtc_is_updating(void)
/*
* rtc_time's year contains the increment over 1900, but vRTC's YEAR
* register can't be programmed to value larger than 0x64, so vRTC
- * driver chose to use 1960 (1970 is UNIX time start point) as the base,
+ * driver chose to use 1972 (1970 is UNIX time start point) as the base,
* and does the translation at read/write time.
*
- * Why not just use 1970 as the offset? it's because using 1960 will
+ * Why not just use 1970 as the offset? it's because using 1972 will
* make it consistent in leap year setting for both vrtc and low-level
- * physical rtc devices.
+ * physical rtc devices. Then why not use 1960 as the offset? If we use
+ * 1960, for a device's first use, its YEAR register is 0 and the system
+ * year will be parsed as 1960 which is not a valid UNIX time and will
+ * cause many applications to fail mysteriously.
*/
static int mrst_read_time(struct device *dev, struct rtc_time *time)
{
@@ -99,10 +102,10 @@ static int mrst_read_time(struct device *dev, struct rtc_time *time)
time->tm_year = vrtc_cmos_read(RTC_YEAR);
spin_unlock_irqrestore(&rtc_lock, flags);
- /* Adjust for the 1960/1900 */
- time->tm_year += 60;
+ /* Adjust for the 1972/1900 */
+ time->tm_year += 72;
time->tm_mon--;
- return RTC_24H;
+ return rtc_valid_tm(time);
}
static int mrst_set_time(struct device *dev, struct rtc_time *time)
@@ -119,9 +122,9 @@ static int mrst_set_time(struct device *dev, struct rtc_time *time)
min = time->tm_min;
sec = time->tm_sec;
- if (yrs < 70 || yrs > 138)
+ if (yrs < 72 || yrs > 138)
return -EINVAL;
- yrs -= 60;
+ yrs -= 72;
spin_lock_irqsave(&rtc_lock, flags);