[PATCH] sh: RTC fixes

From: Paul Mundt <lethal@linux-sh.org>

Re-read RTC registers if MSB of R64CNT was changed while reading them on SH-4
which has unreliable CF bit.

Patch from SUGIOKA Toshinobu and Masaki Saitoh.

diff --git a/arch/sh/kernel/cpu/rtc.c b/arch/sh/kernel/cpu/rtc.c
index 72b625e9ce073c49f2ffc2708382c90f60038fec..f8361f5e788bc81896f3635d268ebf7a40056974 100644 (file)
--- a/arch/sh/kernel/cpu/rtc.c
+++ b/arch/sh/kernel/cpu/rtc.c
@@ -23,10 +23,12 @@
 
 void sh_rtc_gettimeofday(struct timespec *ts)
 {
-       unsigned int sec128, sec, min, hr, wk, day, mon, yr, yr100;
+       unsigned int sec128, sec, sec2, min, hr, wk, day, mon, yr, yr100, cf_bit;
+       unsigned long flags;
 
  again:
        do {
+               local_irq_save(flags);
                ctrl_outb(0, RCR1);  /* Clear CF-bit */
                sec128 = ctrl_inb(R64CNT);
                sec = ctrl_inb(RSECCNT);
@@ -43,15 +45,10 @@ void sh_rtc_gettimeofday(struct timespec *ts)
                yr  = ctrl_inb(RYRCNT);
                yr100 = (yr == 0x99) ? 0x19 : 0x20;
 #endif
-       } while ((ctrl_inb(RCR1) & RCR1_CF) != 0);
-
-#if RTC_BIT_INVERTED != 0
-       /* Work around to avoid reading incorrect value. */
-       if (sec128 == RTC_BIT_INVERTED) {
-               schedule_timeout(1);
-               goto again;
-       }
-#endif
+               sec2 = ctrl_inb(R64CNT);
+               cf_bit = ctrl_inb(RCR1) & RCR1_CF;
+               local_irq_restore(flags);
+       } while (cf_bit != 0 || ((sec128 ^ sec2) & RTC_BIT_INVERTED) != 0);
 
        BCD_TO_BIN(yr100);
        BCD_TO_BIN(yr);
@@ -65,6 +62,7 @@ void sh_rtc_gettimeofday(struct timespec *ts)
            hr > 23 || min > 59 || sec > 59) {
                printk(KERN_ERR
                       "SH RTC: invalid value, resetting to 1 Jan 2000\n");
+               local_irq_save(flags);
                ctrl_outb(RCR2_RESET, RCR2);  /* Reset & Stop */
                ctrl_outb(0, RSECCNT);
                ctrl_outb(0, RMINCNT);
@@ -99,7 +97,9 @@ int sh_rtc_settimeofday(const time_t secs)
 {
        int retval = 0;
        int real_seconds, real_minutes, cmos_minutes;
+       unsigned long flags;
 
+       local_irq_save(flags);
        ctrl_outb(RCR2_RESET, RCR2);  /* Reset pre-scaler & stop RTC */
 
        cmos_minutes = ctrl_inb(RMINCNT);
@@ -130,6 +130,7 @@ int sh_rtc_settimeofday(const time_t secs)
        }
 
        ctrl_outb(RCR2_RTCEN|RCR2_START, RCR2);  /* Start RTC */
+       local_irq_restore(flags);
 
        return retval;
 }