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[PATCH] RTC: Remove RTC UIP synchronization on PPC Maple 

Signed-off-by: Matt Mackall <mpm@selenic.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.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 01:56:04 -08:00 committed by Linus Torvalds
parent 4dc12ec7e2
commit 6f0d7bd6a1
1 changed files with 2 additions and 22 deletions
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24
arch/powerpc/platforms/maple/time.c
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@ -60,34 +60,14 @@ static void maple_clock_write(unsigned long val, int addr)
void maple_get_rtc_time(struct rtc_time *tm)
{
int uip, i;
/* 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.
*/
/* Since the UIP flag is set for about 2.2 ms and the clock
* is typically written with a precision of 1 jiffy, trying
* to obtain a precision better than a few milliseconds is
* an illusion. Only consistency is interesting, this also
* allows to use the routine for /dev/rtc without a potential
* 1 second kernel busy loop triggered by any reader of /dev/rtc.
*/
for (i = 0; i<1000000; i++) {
uip = maple_clock_read(RTC_FREQ_SELECT);
do {
tm->tm_sec = maple_clock_read(RTC_SECONDS);
tm->tm_min = maple_clock_read(RTC_MINUTES);
tm->tm_hour = maple_clock_read(RTC_HOURS);
tm->tm_mday = maple_clock_read(RTC_DAY_OF_MONTH);
tm->tm_mon = maple_clock_read(RTC_MONTH);
tm->tm_year = maple_clock_read(RTC_YEAR);
uip |= maple_clock_read(RTC_FREQ_SELECT);
if ((uip & RTC_UIP)==0)
break;
}
} while (tm->tm_sec != maple_clock_read(RTC_SECONDS));
if (!(maple_clock_read(RTC_CONTROL) & RTC_DM_BINARY)
|| RTC_ALWAYS_BCD) {