[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>

1 files changed, 11 insertions, 36 deletions

diff --git a/arch/mips/dec/time.c b/arch/mips/dec/time.c
index f17d3378e9a6..74cb055d4bf6 100644
--- a/arch/mips/dec/time.c
+++ b/arch/mips/dec/time.c
@@ -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);