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[PATCH] RTC: Remove RTC UIP synchronization on CHRP (arch/powerpc)

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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 01:56:03 -08:00 committed by Linus Torvalds
parent 59937bcdb2
commit 4dc12ec7e2
1 changed files with 2 additions and 20 deletions
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22
arch/powerpc/platforms/chrp/time.c
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@ -120,33 +120,15 @@ int chrp_set_rtc_time(struct rtc_time *tmarg)
void chrp_get_rtc_time(struct rtc_time *tm)
{
unsigned int year, mon, day, hour, min, sec;
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 = chrp_cmos_clock_read(RTC_FREQ_SELECT);
do {
sec = chrp_cmos_clock_read(RTC_SECONDS);
min = chrp_cmos_clock_read(RTC_MINUTES);
hour = chrp_cmos_clock_read(RTC_HOURS);
day = chrp_cmos_clock_read(RTC_DAY_OF_MONTH);
mon = chrp_cmos_clock_read(RTC_MONTH);
year = chrp_cmos_clock_read(RTC_YEAR);
uip |= chrp_cmos_clock_read(RTC_FREQ_SELECT);
if ((uip & RTC_UIP)==0) break;
}
} while (sec != chrp_cmos_clock_read(RTC_SECONDS));
if (!(chrp_cmos_clock_read(RTC_CONTROL) & RTC_DM_BINARY) || RTC_ALWAYS_BCD) {
BCD_TO_BIN(sec);