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>
diff --git a/arch/mips/dec/time.c b/arch/mips/dec/time.c
index dc7091c..1748223 100644
--- a/arch/mips/dec/time.c
+++ b/arch/mips/dec/time.c
@@ -37,10 +37,25 @@
#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
@@ -49,11 +64,12 @@
*/
/* 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 (dec_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 (!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);
@@ -77,6 +93,7 @@
* 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);
@@ -95,6 +112,8 @@
int real_seconds, real_minutes, cmos_minutes;
unsigned char save_control, save_freq_select;
+ /* irq are locally disabled here */
+ spin_lock(&rtc_lock);
/* tell the clock it's being set */
save_control = CMOS_READ(RTC_CONTROL);
CMOS_WRITE((save_control | RTC_SET), RTC_CONTROL);
@@ -141,6 +160,7 @@
*/
CMOS_WRITE(save_control, RTC_CONTROL);
CMOS_WRITE(save_freq_select, RTC_FREQ_SELECT);
+ spin_unlock(&rtc_lock);
return retval;
}