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Subject[PATCH 9/14] RTC: Remove RTC UIP synchronization on MIPS-based DEC
Date
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>

Index: rtc/arch/mips/dec/time.c
===================================================================
--- rtc.orig/arch/mips/dec/time.c 2006-03-16 16:47:15.000000000 -0600
+++ rtc/arch/mips/dec/time.c 2006-03-16 17:32:21.000000000 -0600
@@ -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(vo
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(vo
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);
-
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