vrtc: change its year offset from 1960 to 1972
Subsystems (2)
PATCH 1/1 vrtc: change its year offset from 1960 to 1972
From: Feng Tang <[email protected]>
Real world year equals the value in vrtc YEAR register plus an offset. We used 1960 for original developepment 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. Devices use 1972 instead to fix this issue.
Updated patch which adds a sanity check suggested by Mathias
Signed-off-by Feng Tang <[email protected]>
Signed-off-by Alan Cox <[email protected]>
---
arch/x86/platform/mrst/vrtc.c | 4 ++-- drivers/rtc/rtc-mrst.c | 19 +++++++++++-------- 2 files changed, 13 insertions(+), 10 deletions(-)
arch/x86/platform/mrst/vrtc.c +2 -2
@@ -71,8 +71,8 @@ unsigned long vrtc_get_time(void) mon =vrtc_cmos_read (RTC_MONTH ); year =vrtc_cmos_read (RTC_YEAR ); -/* 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);
drivers/rtc/rtc-mrst.c +11 -8
@@ -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);