[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>

1 files changed, 2 insertions, 22 deletions

diff --git a/arch/powerpc/platforms/maple/time.c b/arch/powerpc/platforms/maple/time.c
index 5e6981d17379..b9a2b3d4bf33 100644
--- a/arch/powerpc/platforms/maple/time.c
+++ b/arch/powerpc/platforms/maple/time.c
@@ -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) {