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[PATCH] RTC: Remove RTC UIP synchronization on MIPS-based DEC 

Move real_year inside the read loop and move the spinlock up as well

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 01:56:06 -08:00 committed by Linus Torvalds
parent da2468b6a8
commit ddcabb4fc7
1 changed files with 11 additions and 36 deletions
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47
arch/mips/dec/time.c
View File

@ -36,41 +36,13 @@
#include <asm/dec/ioasic_addrs.h>
#include <asm/dec/machtype.h>
/*
* Returns true if a clock update is in progress
*/
static inline unsigned char dec_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 unsigned long dec_rtc_get_time(void)
{
unsigned int year, mon, day, hour, min, sec, real_year;
int i;
unsigned long flags;
/* The Linux interpretation of the DS1287 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 (dec_rtc_is_updating())
break;
for (i = 0; i < 1000000; i++) /* must try at least 2.228 ms */
if (!dec_rtc_is_updating())
break;
spin_lock_irqsave(&rtc_lock, flags);
/* Isn't this overkill? UIP above should guarantee consistency */
do {
sec = CMOS_READ(RTC_SECONDS);
min = CMOS_READ(RTC_MINUTES);
@ -78,7 +50,16 @@ static unsigned long dec_rtc_get_time(void)
day = CMOS_READ(RTC_DAY_OF_MONTH);
mon = CMOS_READ(RTC_MONTH);
year = CMOS_READ(RTC_YEAR);
/*
* The PROM will reset the year to either '72 or '73.
* Therefore we store the real year separately, in one
* of unused BBU RAM locations.
*/
real_year = CMOS_READ(RTC_DEC_YEAR);
} while (sec != CMOS_READ(RTC_SECONDS));
spin_unlock_irqrestore(&rtc_lock, flags);
if (!(CMOS_READ(RTC_CONTROL) & RTC_DM_BINARY) || RTC_ALWAYS_BCD) {
sec = BCD2BIN(sec);
min = BCD2BIN(min);
@ -87,13 +68,7 @@ static unsigned long dec_rtc_get_time(void)
mon = BCD2BIN(mon);
year = BCD2BIN(year);
}
/*
* The PROM will reset the year to either '72 or '73.
* Therefore we store the real year separately, in one
* of unused BBU RAM locations.
*/
real_year = CMOS_READ(RTC_DEC_YEAR);
spin_unlock_irqrestore(&rtc_lock, flags);
year += real_year - 72 + 2000;
return mktime(year, mon, day, hour, min, sec);