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[PATCH] RTC: Remove RTC UIP synchronization on MIPS MC146818 

Signed-off-by: Matt Mackall <mpm@selenic.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Alessandro Zummo <a.zummo@towertech.it>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
This commit is contained in:
Matt Mackall 2006-03-28 01:56:05 -08:00 committed by Linus Torvalds
parent 4af6ec46c6
commit da2468b6a8
1 changed files with 2 additions and 31 deletions
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33
include/asm-mips/mc146818-time.h
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@ -86,43 +86,14 @@ static inline int mc146818_set_rtc_mmss(unsigned long nowtime)
return retval;
}
/*
* Returns true if a clock update is in progress
*/
static inline unsigned char rtc_is_updating(void)
{
unsigned char uip;
unsigned long flags;
spin_lock_irqsave(&rtc_lock, flags);
uip = (CMOS_READ(RTC_FREQ_SELECT) & RTC_UIP);
spin_unlock_irqrestore(&rtc_lock, flags);
return uip;
}
static inline unsigned long mc146818_get_cmos_time(void)
{
unsigned int year, mon, day, hour, min, sec;
int i;
unsigned long flags;
/*
* The Linux interpretation of the CMOS clock register contents:
* When the Update-In-Progress (UIP) flag goes from 1 to 0, the
* RTC registers show the second which has precisely just started.
* Let's hope other operating systems interpret the RTC the same way.
*/
/* read RTC exactly on falling edge of update flag */
for (i = 0 ; i < 1000000 ; i++) /* may take up to 1 second... */
if (rtc_is_updating())
break;
for (i = 0 ; i < 1000000 ; i++) /* must try at least 2.228 ms */
if (!rtc_is_updating())
break;
spin_lock_irqsave(&rtc_lock, flags);
do { /* Isn't this overkill ? UIP above should guarantee consistency */
do {
sec = CMOS_READ(RTC_SECONDS);
min = CMOS_READ(RTC_MINUTES);
hour = CMOS_READ(RTC_HOURS);