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Use rtc_lock to protect RTC operations

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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>
This commit is contained in:
Atsushi Nemoto
2005-11-03 01:01:15 +09:00
committed by Ralf Baechle
parent e329331aed
commit 53c2df2f4e
13 changed files with 111 additions and 4 deletions
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24
arch/mips/dec/time.c
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@@ -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 @@ static unsigned long dec_rtc_get_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 (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 @@ static unsigned long dec_rtc_get_time(void)
* 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 @@ static int dec_rtc_set_mmss(unsigned long nowtime)
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 @@ static int dec_rtc_set_mmss(unsigned long nowtime)
*/
CMOS_WRITE(save_control, RTC_CONTROL);
CMOS_WRITE(save_freq_select, RTC_FREQ_SELECT);
spin_unlock(&rtc_lock);
return retval;
}