From 57e6319dd61d5ca10fe8dd57bcce8c0e2c480799 Mon Sep 17 00:00:00 2001 From: Feng Tang Date: Thu, 10 Nov 2011 13:23:39 +0000 Subject: 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 Signed-off-by: Alan Cox Signed-off-by: Linus Torvalds --- drivers/rtc/rtc-mrst.c | 19 +++++++++++-------- 1 file changed, 11 insertions(+), 8 deletions(-) (limited to 'drivers/rtc') 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); -- cgit v1.2.1