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Commit ddcabb4f authored by Matt Mackall's avatar Matt Mackall Committed by Linus Torvalds
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[PATCH] RTC: Remove RTC UIP synchronization on MIPS-based DEC 



Move real_year inside the read loop and move the spinlock up as well

Signed-off-by: default avatarMatt Mackall <mpm@selenic.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Alessandro Zummo <a.zummo@towertech.it>
Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
parent da2468b6

arch/mips/dec/time.c

+11 −36
Original line number Diff line number Diff line
@@ -36,41 +36,13 @@ 
#include <asm/dec/ioasic_addrs.h>

#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

	 * RTC registers show the second which has precisely just started.

	 * Let's hope other operating systems interpret the RTC the same way.

	 */

	/* read RTC exactly on falling edge of update flag */

	for (i = 0; i < 1000000; i++)	/* may take up to 1 second... */

		if (dec_rtc_is_updating())

			break;

	for (i = 0; i < 1000000; i++)	/* must try at least 2.228 ms */

		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);

		min = CMOS_READ(RTC_MINUTES);
@@ -78,7 +50,16 @@ static unsigned long dec_rtc_get_time(void) 
		day = CMOS_READ(RTC_DAY_OF_MONTH);

		mon = CMOS_READ(RTC_MONTH);

		year = CMOS_READ(RTC_YEAR);

		/*

		 * The PROM will reset the year to either '72 or '73.

		 * Therefore we store the real year separately, in one

		 * of unused BBU RAM locations.

		 */

		real_year = CMOS_READ(RTC_DEC_YEAR);

	} while (sec != CMOS_READ(RTC_SECONDS));



	spin_unlock_irqrestore(&rtc_lock, flags);



	if (!(CMOS_READ(RTC_CONTROL) & RTC_DM_BINARY) || RTC_ALWAYS_BCD) {

		sec = BCD2BIN(sec);

		min = BCD2BIN(min);
@@ -87,13 +68,7 @@ static unsigned long dec_rtc_get_time(void) 
		mon = BCD2BIN(mon);

		year = BCD2BIN(year);

	}

	/*

	 * The PROM will reset the year to either '72 or '73.

	 * Therefore we store the real year separately, in one

	 * 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);