From 53c2df2f4ebbc1d8231ca7cc13ac5381230888b1 Mon Sep 17 00:00:00 2001 From: Atsushi Nemoto Date: Thu, 3 Nov 2005 01:01:15 +0900 Subject: 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 Signed-off-by: Ralf Baechle --- include/asm-mips/mc146818-time.h | 24 ++++++++++++++++++++++-- 1 file changed, 22 insertions(+), 2 deletions(-) (limited to 'include/asm-mips/mc146818-time.h') 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); -- cgit v1.2.3