Use rtc_lock to protect RTC operations

    
Many RTC routines were not protected against each other, so there are
potential races, for example, ntp-update against /dev/rtc.  This patch
fixes them using rtc_lock.
    
Signed-off-by: Atsushi Nemoto <anemo@mba.ocn.ne.jp>
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

1 files changed, 22 insertions, 2 deletions

diff --git a/include/asm-mips/mc146818-time.h b/include/asm-mips/mc146818-time.h
index a2c2d2c2430..47214861093 100644
--- a/include/asm-mips/mc146818-time.h
+++ b/include/asm-mips/mc146818-time.h
@@ -33,7 +33,9 @@ static inline int mc146818_set_rtc_mmss(unsigned long nowtime)
 	int real_seconds, real_minutes, cmos_minutes;
 	unsigned char save_control, save_freq_select;
 	int retval = 0;
+	unsigned long flags;
 
+	spin_lock_irqsave(&rtc_lock, flags);
 	save_control = CMOS_READ(RTC_CONTROL); /* tell the clock it's being set */
 	CMOS_WRITE((save_control|RTC_SET), RTC_CONTROL);
 
@@ -79,14 +81,30 @@ static inline int mc146818_set_rtc_mmss(unsigned long nowtime)
 	 */
 	CMOS_WRITE(save_control, RTC_CONTROL);
 	CMOS_WRITE(save_freq_select, RTC_FREQ_SELECT);
+	spin_unlock_irqrestore(&rtc_lock, flags);
 
 	return retval;
 }
 
+/*
+ * Returns true if a clock update is in progress
+ */
+static inline unsigned char 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 inline unsigned long mc146818_get_cmos_time(void)
 {
 	unsigned int year, mon, day, hour, min, sec;
 	int i;
+	unsigned long flags;
 
 	/*
 	 * The Linux interpretation of the CMOS clock register contents:
@@ -97,12 +115,13 @@ static inline unsigned long mc146818_get_cmos_time(void)
 
 	/* read RTC exactly on falling edge of update flag */
 	for (i = 0 ; i < 1000000 ; i++)	/* may take up to 1 second... */
-		if (CMOS_READ(RTC_FREQ_SELECT) & RTC_UIP)
+		if (rtc_is_updating())
 			break;
 	for (i = 0 ; i < 1000000 ; i++)	/* must try at least 2.228 ms */
-		if (!(CMOS_READ(RTC_FREQ_SELECT) & RTC_UIP))
+		if (!rtc_is_updating())
 			break;
 
+	spin_lock_irqsave(&rtc_lock, flags);
 	do { /* Isn't this overkill ? UIP above should guarantee consistency */
 		sec = CMOS_READ(RTC_SECONDS);
 		min = CMOS_READ(RTC_MINUTES);
@@ -120,6 +139,7 @@ static inline unsigned long mc146818_get_cmos_time(void)
 		BCD_TO_BIN(mon);
 		BCD_TO_BIN(year);
 	}
+	spin_unlock_irqrestore(&rtc_lock, flags);
 	year = mc146818_decode_year(year);
 
 	return mktime(year, mon, day, hour, min, sec);