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Commit 4dc12ec7 authored by Matt Mackall's avatar Matt Mackall Committed by Linus Torvalds
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[PATCH] RTC: Remove RTC UIP synchronization on CHRP (arch/powerpc) 



Signed-off-by: default avatarMatt Mackall <mpm@selenic.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.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 59937bcd

arch/powerpc/platforms/chrp/time.c

+2 −20
Original line number Diff line number Diff line
@@ -120,33 +120,15 @@ int chrp_set_rtc_time(struct rtc_time *tmarg) 
void chrp_get_rtc_time(struct rtc_time *tm)

{

	unsigned int year, mon, day, hour, min, sec;

	int uip, i;



	/* The Linux interpretation of the CMOS 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.

	 */



	/* Since the UIP flag is set for about 2.2 ms and the clock

	 * is typically written with a precision of 1 jiffy, trying

	 * to obtain a precision better than a few milliseconds is

	 * an illusion. Only consistency is interesting, this also

	 * allows to use the routine for /dev/rtc without a potential

	 * 1 second kernel busy loop triggered by any reader of /dev/rtc.

	 */



	for ( i = 0; i<1000000; i++) {

		uip = chrp_cmos_clock_read(RTC_FREQ_SELECT);

	do {

		sec = chrp_cmos_clock_read(RTC_SECONDS);

		min = chrp_cmos_clock_read(RTC_MINUTES);

		hour = chrp_cmos_clock_read(RTC_HOURS);

		day = chrp_cmos_clock_read(RTC_DAY_OF_MONTH);

		mon = chrp_cmos_clock_read(RTC_MONTH);

		year = chrp_cmos_clock_read(RTC_YEAR);

		uip |= chrp_cmos_clock_read(RTC_FREQ_SELECT);

		if ((uip & RTC_UIP)==0) break;

	}

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



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

		BCD_TO_BIN(sec);