Merge commit 'v2.6.30-rc1' into sched/urgent

Merge reason: update to latest upstream to queue up fix

Signed-off-by: Ingo Molnar <mingo@elte.hu>

5 files changed, 553 insertions, 180 deletions

diff --git a/kernel/time/Makefile b/kernel/time/Makefile
index 905b0b50792..0b0a6366c9d 100644
--- a/kernel/time/Makefile
+++ b/kernel/time/Makefile
@@ -1,4 +1,4 @@
-obj-y += timekeeping.o ntp.o clocksource.o jiffies.o timer_list.o
+obj-y += timekeeping.o ntp.o clocksource.o jiffies.o timer_list.o timecompare.o
 
 obj-$(CONFIG_GENERIC_CLOCKEVENTS_BUILD)		+= clockevents.o
 obj-$(CONFIG_GENERIC_CLOCKEVENTS)		+= tick-common.o
diff --git a/kernel/time/clockevents.c b/kernel/time/clockevents.c
index ea2f48af83c..d13be216a79 100644
--- a/kernel/time/clockevents.c
+++ b/kernel/time/clockevents.c
@@ -68,6 +68,17 @@ void clockevents_set_mode(struct clock_event_device *dev,
 	if (dev->mode != mode) {
 		dev->set_mode(mode, dev);
 		dev->mode = mode;
+
+		/*
+		 * A nsec2cyc multiplicator of 0 is invalid and we'd crash
+		 * on it, so fix it up and emit a warning:
+		 */
+		if (mode == CLOCK_EVT_MODE_ONESHOT) {
+			if (unlikely(!dev->mult)) {
+				dev->mult = 1;
+				WARN_ON(1);
+			}
+		}
 	}
 }
 
@@ -168,15 +179,6 @@ void clockevents_register_device(struct clock_event_device *dev)
 	BUG_ON(dev->mode != CLOCK_EVT_MODE_UNUSED);
 	BUG_ON(!dev->cpumask);
 
-	/*
-	 * A nsec2cyc multiplicator of 0 is invalid and we'd crash
-	 * on it, so fix it up and emit a warning:
-	 */
-	if (unlikely(!dev->mult)) {
-		dev->mult = 1;
-		WARN_ON(1);
-	}
-
 	spin_lock(&clockevents_lock);
 
 	list_add(&dev->list, &clockevent_devices);
diff --git a/kernel/time/clocksource.c b/kernel/time/clocksource.c
index ca89e1593f0..c46c931a7fe 100644
--- a/kernel/time/clocksource.c
+++ b/kernel/time/clocksource.c
@@ -31,6 +31,82 @@
 #include <linux/sched.h> /* for spin_unlock_irq() using preempt_count() m68k */
 #include <linux/tick.h>
 
+void timecounter_init(struct timecounter *tc,
+		      const struct cyclecounter *cc,
+		      u64 start_tstamp)
+{
+	tc->cc = cc;
+	tc->cycle_last = cc->read(cc);
+	tc->nsec = start_tstamp;
+}
+EXPORT_SYMBOL(timecounter_init);
+
+/**
+ * timecounter_read_delta - get nanoseconds since last call of this function
+ * @tc:         Pointer to time counter
+ *
+ * When the underlying cycle counter runs over, this will be handled
+ * correctly as long as it does not run over more than once between
+ * calls.
+ *
+ * The first call to this function for a new time counter initializes
+ * the time tracking and returns an undefined result.
+ */
+static u64 timecounter_read_delta(struct timecounter *tc)
+{
+	cycle_t cycle_now, cycle_delta;
+	u64 ns_offset;
+
+	/* read cycle counter: */
+	cycle_now = tc->cc->read(tc->cc);
+
+	/* calculate the delta since the last timecounter_read_delta(): */
+	cycle_delta = (cycle_now - tc->cycle_last) & tc->cc->mask;
+
+	/* convert to nanoseconds: */
+	ns_offset = cyclecounter_cyc2ns(tc->cc, cycle_delta);
+
+	/* update time stamp of timecounter_read_delta() call: */
+	tc->cycle_last = cycle_now;
+
+	return ns_offset;
+}
+
+u64 timecounter_read(struct timecounter *tc)
+{
+	u64 nsec;
+
+	/* increment time by nanoseconds since last call */
+	nsec = timecounter_read_delta(tc);
+	nsec += tc->nsec;
+	tc->nsec = nsec;
+
+	return nsec;
+}
+EXPORT_SYMBOL(timecounter_read);
+
+u64 timecounter_cyc2time(struct timecounter *tc,
+			 cycle_t cycle_tstamp)
+{
+	u64 cycle_delta = (cycle_tstamp - tc->cycle_last) & tc->cc->mask;
+	u64 nsec;
+
+	/*
+	 * Instead of always treating cycle_tstamp as more recent
+	 * than tc->cycle_last, detect when it is too far in the
+	 * future and treat it as old time stamp instead.
+	 */
+	if (cycle_delta > tc->cc->mask / 2) {
+		cycle_delta = (tc->cycle_last - cycle_tstamp) & tc->cc->mask;
+		nsec = tc->nsec - cyclecounter_cyc2ns(tc->cc, cycle_delta);
+	} else {
+		nsec = cyclecounter_cyc2ns(tc->cc, cycle_delta) + tc->nsec;
+	}
+
+	return nsec;
+}
+EXPORT_SYMBOL(timecounter_cyc2time);
+
 /* XXX - Would like a better way for initializing curr_clocksource */
 extern struct clocksource clocksource_jiffies;
 
diff --git a/kernel/time/ntp.c b/kernel/time/ntp.c
index f5f793d9241..7fc64375ff4 100644
--- a/kernel/time/ntp.c
+++ b/kernel/time/ntp.c
@@ -1,71 +1,129 @@
 /*
- * linux/kernel/time/ntp.c
- *
  * NTP state machine interfaces and logic.
  *
  * This code was mainly moved from kernel/timer.c and kernel/time.c
  * Please see those files for relevant copyright info and historical
  * changelogs.
  */
-
-#include <linux/mm.h>
-#include <linux/time.h>
-#include <linux/timex.h>
-#include <linux/jiffies.h>
-#include <linux/hrtimer.h>
 #include <linux/capability.h>
-#include <linux/math64.h>
 #include <linux/clocksource.h>
 #include <linux/workqueue.h>
-#include <asm/timex.h>
+#include <linux/hrtimer.h>
+#include <linux/jiffies.h>
+#include <linux/math64.h>
+#include <linux/timex.h>
+#include <linux/time.h>
+#include <linux/mm.h>
 
 /*
- * Timekeeping variables
+ * NTP timekeeping variables:
  */
-unsigned long tick_usec = TICK_USEC; 		/* USER_HZ period (usec) */
-unsigned long tick_nsec;			/* ACTHZ period (nsec) */
-u64 tick_length;
-static u64 tick_length_base;
 
-static struct hrtimer leap_timer;
+/* USER_HZ period (usecs): */
+unsigned long			tick_usec = TICK_USEC;
 
-#define MAX_TICKADJ		500		/* microsecs */
-#define MAX_TICKADJ_SCALED	(((u64)(MAX_TICKADJ * NSEC_PER_USEC) << \
-				  NTP_SCALE_SHIFT) / NTP_INTERVAL_FREQ)
+/* ACTHZ period (nsecs): */
+unsigned long			tick_nsec;
+
+u64				tick_length;
+static u64			tick_length_base;
+
+static struct hrtimer		leap_timer;
+
+#define MAX_TICKADJ		500LL		/* usecs */
+#define MAX_TICKADJ_SCALED \
+	(((MAX_TICKADJ * NSEC_PER_USEC) << NTP_SCALE_SHIFT) / NTP_INTERVAL_FREQ)
 
 /*
  * phase-lock loop variables
  */
-/* TIME_ERROR prevents overwriting the CMOS clock */
-static int time_state = TIME_OK;	/* clock synchronization status	*/
-int time_status = STA_UNSYNC;		/* clock status bits		*/
-static long time_tai;			/* TAI offset (s)		*/
-static s64 time_offset;			/* time adjustment (ns)		*/
-static long time_constant = 2;		/* pll time constant		*/
-long time_maxerror = NTP_PHASE_LIMIT;	/* maximum error (us)		*/
-long time_esterror = NTP_PHASE_LIMIT;	/* estimated error (us)		*/
-static s64 time_freq;			/* frequency offset (scaled ns/s)*/
-static long time_reftime;		/* time at last adjustment (s)	*/
-long time_adjust;
-static long ntp_tick_adj;
 
+/*
+ * clock synchronization status
+ *
+ * (TIME_ERROR prevents overwriting the CMOS clock)
+ */
+static int			time_state = TIME_OK;
+
+/* clock status bits:							*/
+int				time_status = STA_UNSYNC;
+
+/* TAI offset (secs):							*/
+static long			time_tai;
+
+/* time adjustment (nsecs):						*/
+static s64			time_offset;
+
+/* pll time constant:							*/
+static long			time_constant = 2;
+
+/* maximum error (usecs):						*/
+long				time_maxerror = NTP_PHASE_LIMIT;
+
+/* estimated error (usecs):						*/
+long				time_esterror = NTP_PHASE_LIMIT;
+
+/* frequency offset (scaled nsecs/secs):				*/
+static s64			time_freq;
+
+/* time at last adjustment (secs):					*/
+static long			time_reftime;
+
+long				time_adjust;
+
+/* constant (boot-param configurable) NTP tick adjustment (upscaled)	*/
+static s64			ntp_tick_adj;
+
+/*
+ * NTP methods:
+ */
+
+/*
+ * Update (tick_length, tick_length_base, tick_nsec), based
+ * on (tick_usec, ntp_tick_adj, time_freq):
+ */
 static void ntp_update_frequency(void)
 {
-	u64 second_length = (u64)(tick_usec * NSEC_PER_USEC * USER_HZ)
-				<< NTP_SCALE_SHIFT;
-	second_length += (s64)ntp_tick_adj << NTP_SCALE_SHIFT;
-	second_length += time_freq;
+	u64 second_length;
+	u64 new_base;
+
+	second_length		 = (u64)(tick_usec * NSEC_PER_USEC * USER_HZ)
+						<< NTP_SCALE_SHIFT;
+
+	second_length		+= ntp_tick_adj;
+	second_length		+= time_freq;
 
-	tick_length_base = second_length;
+	tick_nsec		 = div_u64(second_length, HZ) >> NTP_SCALE_SHIFT;
+	new_base		 = div_u64(second_length, NTP_INTERVAL_FREQ);
 
-	tick_nsec = div_u64(second_length, HZ) >> NTP_SCALE_SHIFT;
-	tick_length_base = div_u64(tick_length_base, NTP_INTERVAL_FREQ);
+	/*
+	 * Don't wait for the next second_overflow, apply
+	 * the change to the tick length immediately:
+	 */
+	tick_length		+= new_base - tick_length_base;
+	tick_length_base	 = new_base;
+}
+
+static inline s64 ntp_update_offset_fll(s64 offset64, long secs)
+{
+	time_status &= ~STA_MODE;
+
+	if (secs < MINSEC)
+		return 0;
+
+	if (!(time_status & STA_FLL) && (secs <= MAXSEC))
+		return 0;
+
+	time_status |= STA_MODE;
+
+	return div_s64(offset64 << (NTP_SCALE_SHIFT - SHIFT_FLL), secs);
 }
 
 static void ntp_update_offset(long offset)
 {
-	long mtemp;
 	s64 freq_adj;
+	s64 offset64;
+	long secs;
 
 	if (!(time_status & STA_PLL))
 		return;
@@ -84,24 +142,23 @@ static void ntp_update_offset(long offset)
 	 * Select how the frequency is to be controlled
 	 * and in which mode (PLL or FLL).
 	 */
-	if (time_status & STA_FREQHOLD || time_reftime == 0)
-		time_reftime = xtime.tv_sec;
-	mtemp = xtime.tv_sec - time_reftime;
+	secs = xtime.tv_sec - time_reftime;
+	if (unlikely(time_status & STA_FREQHOLD))
+		secs = 0;
+
 	time_reftime = xtime.tv_sec;
 
-	freq_adj = (s64)offset * mtemp;
-	freq_adj <<= NTP_SCALE_SHIFT - 2 * (SHIFT_PLL + 2 + time_constant);
-	time_status &= ~STA_MODE;
-	if (mtemp >= MINSEC && (time_status & STA_FLL || mtemp > MAXSEC)) {
-		freq_adj += div_s64((s64)offset << (NTP_SCALE_SHIFT - SHIFT_FLL),
-				    mtemp);
-		time_status |= STA_MODE;
-	}
-	freq_adj += time_freq;
-	freq_adj = min(freq_adj, MAXFREQ_SCALED);
-	time_freq = max(freq_adj, -MAXFREQ_SCALED);
+	offset64    = offset;
+	freq_adj    = (offset64 * secs) <<
+			(NTP_SCALE_SHIFT - 2 * (SHIFT_PLL + 2 + time_constant));
 
-	time_offset = div_s64((s64)offset << NTP_SCALE_SHIFT, NTP_INTERVAL_FREQ);
+	freq_adj    += ntp_update_offset_fll(offset64, secs);
+
+	freq_adj    = min(freq_adj + time_freq, MAXFREQ_SCALED);
+
+	time_freq   = max(freq_adj, -MAXFREQ_SCALED);
+
+	time_offset = div_s64(offset64 << NTP_SCALE_SHIFT, NTP_INTERVAL_FREQ);
 }
 
 /**
@@ -111,15 +168,15 @@ static void ntp_update_offset(long offset)
  */
 void ntp_clear(void)
 {
-	time_adjust = 0;		/* stop active adjtime() */
-	time_status |= STA_UNSYNC;
-	time_maxerror = NTP_PHASE_LIMIT;
-	time_esterror = NTP_PHASE_LIMIT;
+	time_adjust	= 0;		/* stop active adjtime() */
+	time_status	|= STA_UNSYNC;
+	time_maxerror	= NTP_PHASE_LIMIT;
+	time_esterror	= NTP_PHASE_LIMIT;
 
 	ntp_update_frequency();
 
-	tick_length = tick_length_base;
-	time_offset = 0;
+	tick_length	= tick_length_base;
+	time_offset	= 0;
 }
 
 /*
@@ -140,8 +197,8 @@ static enum hrtimer_restart ntp_leap_second(struct hrtimer *timer)
 		xtime.tv_sec--;
 		wall_to_monotonic.tv_sec++;
 		time_state = TIME_OOP;
-		printk(KERN_NOTICE "Clock: "
-		       "inserting leap second 23:59:60 UTC\n");
+		printk(KERN_NOTICE
+			"Clock: inserting leap second 23:59:60 UTC\n");
 		hrtimer_add_expires_ns(&leap_timer, NSEC_PER_SEC);
 		res = HRTIMER_RESTART;
 		break;
@@ -150,8 +207,8 @@ static enum hrtimer_restart ntp_leap_second(struct hrtimer *timer)
 		time_tai--;
 		wall_to_monotonic.tv_sec--;
 		time_state = TIME_WAIT;
-		printk(KERN_NOTICE "Clock: "
-		       "deleting leap second 23:59:59 UTC\n");
+		printk(KERN_NOTICE
+			"Clock: deleting leap second 23:59:59 UTC\n");
 		break;
 	case TIME_OOP:
 		time_tai++;
@@ -179,7 +236,7 @@ static enum hrtimer_restart ntp_leap_second(struct hrtimer *timer)
  */
 void second_overflow(void)
 {
-	s64 time_adj;
+	s64 delta;
 
 	/* Bump the maxerror field */
 	time_maxerror += MAXFREQ / NSEC_PER_USEC;
@@ -192,24 +249,30 @@ void second_overflow(void)
 	 * Compute the phase adjustment for the next second. The offset is
 	 * reduced by a fixed factor times the time constant.
 	 */
-	tick_length = tick_length_base;
-	time_adj = shift_right(time_offset, SHIFT_PLL + time_constant);
-	time_offset -= time_adj;
-	tick_length += time_adj;
-
-	if (unlikely(time_adjust)) {
-		if (time_adjust > MAX_TICKADJ) {
-			time_adjust -= MAX_TICKADJ;
-			tick_length += MAX_TICKADJ_SCALED;
-		} else if (time_adjust < -MAX_TICKADJ) {
-			time_adjust += MAX_TICKADJ;
-			tick_length -= MAX_TICKADJ_SCALED;
-		} else {
-			tick_length += (s64)(time_adjust * NSEC_PER_USEC /
-					NTP_INTERVAL_FREQ) << NTP_SCALE_SHIFT;
-			time_adjust = 0;
-		}
+	tick_length	 = tick_length_base;
+
+	delta		 = shift_right(time_offset, SHIFT_PLL + time_constant);
+	time_offset	-= delta;
+	tick_length	+= delta;
+
+	if (!time_adjust)
+		return;
+
+	if (time_adjust > MAX_TICKADJ) {
+		time_adjust -= MAX_TICKADJ;
+		tick_length += MAX_TICKADJ_SCALED;
+		return;
 	}
+
+	if (time_adjust < -MAX_TICKADJ) {
+		time_adjust += MAX_TICKADJ;
+		tick_length -= MAX_TICKADJ_SCALED;
+		return;
+	}
+
+	tick_length += (s64)(time_adjust * NSEC_PER_USEC / NTP_INTERVAL_FREQ)
+							 << NTP_SCALE_SHIFT;
+	time_adjust = 0;
 }
 
 #ifdef CONFIG_GENERIC_CMOS_UPDATE
@@ -233,12 +296,13 @@ static void sync_cmos_clock(struct work_struct *work)
 	 * This code is run on a timer.  If the clock is set, that timer
 	 * may not expire at the correct time.  Thus, we adjust...
 	 */
-	if (!ntp_synced())
+	if (!ntp_synced()) {
 		/*
 		 * Not synced, exit, do not restart a timer (if one is
 		 * running, let it run out).
 		 */
 		return;
+	}
 
 	getnstimeofday(&now);
 	if (abs(now.tv_nsec - (NSEC_PER_SEC / 2)) <= tick_nsec / 2)
@@ -270,7 +334,116 @@ static void notify_cmos_timer(void)
 static inline void notify_cmos_timer(void) { }
 #endif
 
-/* adjtimex mainly allows reading (and writing, if superuser) of
+/*
+ * Start the leap seconds timer:
+ */
+static inline void ntp_start_leap_timer(struct timespec *ts)
+{
+	long now = ts->tv_sec;
+
+	if (time_status & STA_INS) {
+		time_state = TIME_INS;
+		now += 86400 - now % 86400;
+		hrtimer_start(&leap_timer, ktime_set(now, 0), HRTIMER_MODE_ABS);
+
+		return;
+	}
+
+	if (time_status & STA_DEL) {
+		time_state = TIME_DEL;
+		now += 86400 - (now + 1) % 86400;
+		hrtimer_start(&leap_timer, ktime_set(now, 0), HRTIMER_MODE_ABS);
+	}
+}
+
+/*
+ * Propagate a new txc->status value into the NTP state:
+ */
+static inline void process_adj_status(struct timex *txc, struct timespec *ts)
+{
+	if ((time_status & STA_PLL) && !(txc->status & STA_PLL)) {
+		time_state = TIME_OK;
+		time_status = STA_UNSYNC;
+	}
+
+	/*
+	 * If we turn on PLL adjustments then reset the
+	 * reference time to current time.
+	 */
+	if (!(time_status & STA_PLL) && (txc->status & STA_PLL))
+		time_reftime = xtime.tv_sec;
+
+	/* only set allowed bits */
+	time_status &= STA_RONLY;
+	time_status |= txc->status & ~STA_RONLY;
+
+	switch (time_state) {
+	case TIME_OK:
+		ntp_start_leap_timer(ts);
+		break;
+	case TIME_INS:
+	case TIME_DEL:
+		time_state = TIME_OK;
+		ntp_start_leap_timer(ts);
+	case TIME_WAIT:
+		if (!(time_status & (STA_INS | STA_DEL)))
+			time_state = TIME_OK;
+		break;
+	case TIME_OOP:
+		hrtimer_restart(&leap_timer);
+		break;
+	}
+}
+/*
+ * Called with the xtime lock held, so we can access and modify
+ * all the global NTP state:
+ */
+static inline void process_adjtimex_modes(struct timex *txc, struct timespec *ts)
+{
+	if (txc->modes & ADJ_STATUS)
+		process_adj_status(txc, ts);
+
+	if (txc->modes & ADJ_NANO)
+		time_status |= STA_NANO;
+
+	if (txc->modes & ADJ_MICRO)
+		time_status &= ~STA_NANO;
+
+	if (txc->modes & ADJ_FREQUENCY) {
+		time_freq = txc->freq * PPM_SCALE;
+		time_freq = min(time_freq, MAXFREQ_SCALED);
+		time_freq = max(time_freq, -MAXFREQ_SCALED);
+	}
+
+	if (txc->modes & ADJ_MAXERROR)
+		time_maxerror = txc->maxerror;
+
+	if (txc->modes & ADJ_ESTERROR)
+		time_esterror = txc->esterror;
+
+	if (txc->modes & ADJ_TIMECONST) {
+		time_constant = txc->constant;
+		if (!(time_status & STA_NANO))
+			time_constant += 4;
+		time_constant = min(time_constant, (long)MAXTC);
+		time_constant = max(time_constant, 0l);
+	}
+
+	if (txc->modes & ADJ_TAI && txc->constant > 0)
+		time_tai = txc->constant;
+
+	if (txc->modes & ADJ_OFFSET)
+		ntp_update_offset(txc->offset);
+
+	if (txc->modes & ADJ_TICK)
+		tick_usec = txc->tick;
+
+	if (txc->modes & (ADJ_TICK|ADJ_FREQUENCY|ADJ_OFFSET))
+		ntp_update_frequency();
+}
+
+/*
+ * adjtimex mainly allows reading (and writing, if superuser) of
  * kernel time-keeping variables. used by xntpd.
  */
 int do_adjtimex(struct timex *txc)
@@ -291,11 +464,14 @@ int do_adjtimex(struct timex *txc)
 		 if (txc->modes && !capable(CAP_SYS_TIME))
 			return -EPERM;
 
-		/* if the quartz is off by more than 10% something is VERY wrong! */
+		/*
+		 * if the quartz is off by more than 10% then
+		 * something is VERY wrong!
+		 */
 		if (txc->modes & ADJ_TICK &&
 		    (txc->tick <  900000/USER_HZ ||
 		     txc->tick > 1100000/USER_HZ))
-				return -EINVAL;
+			return -EINVAL;
 
 		if (txc->modes & ADJ_STATUS && time_state != TIME_OK)
 			hrtimer_cancel(&leap_timer);
@@ -305,7 +481,6 @@ int do_adjtimex(struct timex *txc)
 
 	write_seqlock_irq(&xtime_lock);
 
-	/* If there are input parameters, then process them */
 	if (txc->modes & ADJ_ADJTIME) {
 		long save_adjust = time_adjust;
 
@@ -315,98 +490,24 @@ int do_adjtimex(struct timex *txc)
 			ntp_update_frequency();
 		}
 		txc->offset = save_adjust;
-		goto adj_done;
-	}
-	if (txc->modes) {
-		long sec;
-
-		if (txc->modes & ADJ_STATUS) {
-			if ((time_status & STA_PLL) &&
-			    !(txc->status & STA_PLL)) {
-				time_state = TIME_OK;
-				time_status = STA_UNSYNC;
-			}
-			/* only set allowed bits */
-			time_status &= STA_RONLY;
-			time_status |= txc->status & ~STA_RONLY;
-
-			switch (time_state) {
-			case TIME_OK:
-			start_timer:
-				sec = ts.tv_sec;
-				if (time_status & STA_INS) {
-					time_state = TIME_INS;
-					sec += 86400 - sec % 86400;
-					hrtimer_start(&leap_timer, ktime_set(sec, 0), HRTIMER_MODE_ABS);
-				} else if (time_status & STA_DEL) {
-					time_state = TIME_DEL;
-					sec += 86400 - (sec + 1) % 86400;
-					hrtimer_start(&leap_timer, ktime_set(sec, 0), HRTIMER_MODE_ABS);
-				}
-				break;
-			case TIME_INS:
-			case TIME_DEL:
-				time_state = TIME_OK;
-				goto start_timer;
-				break;
-			case TIME_WAIT:
-				if (!(time_status & (STA_INS | STA_DEL)))
-					time_state = TIME_OK;
-				break;
-			case TIME_OOP:
-				hrtimer_restart(&leap_timer);
-				break;
-			}
-		}
-
-		if (txc->modes & ADJ_NANO)
-			time_status |= STA_NANO;
-		if (txc->modes & ADJ_MICRO)
-			time_status &= ~STA_NANO;
-
-		if (txc->modes & ADJ_FREQUENCY) {
-			time_freq = (s64)txc->freq * PPM_SCALE;
-			time_freq = min(time_freq, MAXFREQ_SCALED);
-			time_freq = max(time_freq, -MAXFREQ_SCALED);
-		}
-
-		if (txc->modes & ADJ_MAXERROR)
-			time_maxerror = txc->maxerror;
-		if (txc->modes & ADJ_ESTERROR)
-			time_esterror = txc->esterror;
-
-		if (txc->modes & ADJ_TIMECONST) {
-			time_constant = txc->constant;
-			if (!(time_status & STA_NANO))
-				time_constant += 4;
-			time_constant = min(time_constant, (long)MAXTC);
-			time_constant = max(time_constant, 0l);
-		}
-
-		if (txc->modes & ADJ_TAI && txc->constant > 0)
-			time_tai = txc->constant;
-
-		if (txc->modes & ADJ_OFFSET)
-			ntp_update_offset(txc->offset);
-		if (txc->modes & ADJ_TICK)
-			tick_usec = txc->tick;
+	} else {
 
-		if (txc->modes & (ADJ_TICK|ADJ_FREQUENCY|ADJ_OFFSET))
-			ntp_update_frequency();
-	}
+		/* If there are input parameters, then process them: */
+		if (txc->modes)
+			process_adjtimex_modes(txc, &ts);
 
-	txc->offset = shift_right(time_offset * NTP_INTERVAL_FREQ,
+		txc->offset = shift_right(time_offset * NTP_INTERVAL_FREQ,
 				  NTP_SCALE_SHIFT);
-	if (!(time_status & STA_NANO))
-		txc->offset /= NSEC_PER_USEC;
+		if (!(time_status & STA_NANO))
+			txc->offset /= NSEC_PER_USEC;
+	}
 
-adj_done:
 	result = time_state;	/* mostly `TIME_OK' */
 	if (time_status & (STA_UNSYNC|STA_CLOCKERR))
 		result = TIME_ERROR;
 
 	txc->freq	   = shift_right((time_freq >> PPM_SCALE_INV_SHIFT) *
-					 (s64)PPM_SCALE_INV, NTP_SCALE_SHIFT);
+					 PPM_SCALE_INV, NTP_SCALE_SHIFT);
 	txc->maxerror	   = time_maxerror;
 	txc->esterror	   = time_esterror;
 	txc->status	   = time_status;
@@ -425,6 +526,7 @@ adj_done:
 	txc->calcnt	   = 0;
 	txc->errcnt	   = 0;
 	txc->stbcnt	   = 0;
+
 	write_sequnlock_irq(&xtime_lock);
 
 	txc->time.tv_sec = ts.tv_sec;
@@ -440,6 +542,8 @@ adj_done:
 static int __init ntp_tick_adj_setup(char *str)
 {
 	ntp_tick_adj = simple_strtol(str, NULL, 0);
+	ntp_tick_adj <<= NTP_SCALE_SHIFT;
+
 	return 1;
 }
 
diff --git a/kernel/time/timecompare.c b/kernel/time/timecompare.c
new file mode 100644
index 00000000000..71e7f1a1915
--- /dev/null
+++ b/kernel/time/timecompare.c
@@ -0,0 +1,191 @@
+/*
+ * Copyright (C) 2009 Intel Corporation.
+ * Author: Patrick Ohly <patrick.ohly@intel.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+ */
+
+#include <linux/timecompare.h>
+#include <linux/module.h>
+#include <linux/math64.h>
+
+/*
+ * fixed point arithmetic scale factor for skew
+ *
+ * Usually one would measure skew in ppb (parts per billion, 1e9), but
+ * using a factor of 2 simplifies the math.
+ */
+#define TIMECOMPARE_SKEW_RESOLUTION (((s64)1)<<30)
+
+ktime_t timecompare_transform(struct timecompare *sync,
+			      u64 source_tstamp)
+{
+	u64 nsec;
+
+	nsec = source_tstamp + sync->offset;
+	nsec += (s64)(source_tstamp - sync->last_update) * sync->skew /
+		TIMECOMPARE_SKEW_RESOLUTION;
+
+	return ns_to_ktime(nsec);
+}
+EXPORT_SYMBOL(timecompare_transform);
+
+int timecompare_offset(struct timecompare *sync,
+		       s64 *offset,
+		       u64 *source_tstamp)
+{
+	u64 start_source = 0, end_source = 0;
+	struct {
+		s64 offset;
+		s64 duration_target;
+	} buffer[10], sample, *samples;
+	int counter = 0, i;
+	int used;
+	int index;
+	int num_samples = sync->num_samples;
+
+	if (num_samples > sizeof(buffer)/sizeof(buffer[0])) {
+		samples = kmalloc(sizeof(*samples) * num_samples, GFP_ATOMIC);
+		if (!samples) {
+			samples = buffer;
+			num_samples = sizeof(buffer)/sizeof(buffer[0]);
+		}
+	} else {
+		samples = buffer;
+	}
+
+	/* run until we have enough valid samples, but do not try forever */
+	i = 0;
+	counter = 0;
+	while (1) {
+		u64 ts;
+		ktime_t start, end;
+
+		start = sync->target();
+		ts = timecounter_read(sync->source);
+		end = sync->target();
+
+		if (!i)
+			start_source = ts;
+
+		/* ignore negative durations */
+		sample.duration_target = ktime_to_ns(ktime_sub(end, start));
+		if (sample.duration_target >= 0) {
+			/*
+			 * assume symetric delay to and from source:
+			 * average target time corresponds to measured
+			 * source time
+			 */
+			sample.offset =
+				ktime_to_ns(ktime_add(end, start)) / 2 -
+				ts;
+
+			/* simple insertion sort based on duration */
+			index = counter - 1;
+			while (index >= 0) {
+				if (samples[index].duration_target <
+				    sample.duration_target)
+					break;
+				samples[index + 1] = samples[index];
+				index--;
+			}
+			samples[index + 1] = sample;
+			counter++;
+		}
+
+		i++;
+		if (counter >= num_samples || i >= 100000) {
+			end_source = ts;
+			break;
+		}
+	}
+
+	*source_tstamp = (end_source + start_source) / 2;
+
+	/* remove outliers by only using 75% of the samples */
+	used = counter * 3 / 4;
+	if (!used)
+		used = counter;
+	if (used) {
+		/* calculate average */
+		s64 off = 0;
+		for (index = 0; index < used; index++)
+			off += samples[index].offset;
+		*offset = div_s64(off, used);
+	}
+
+	if (samples && samples != buffer)
+		kfree(samples);
+
+	return used;
+}
+EXPORT_SYMBOL(timecompare_offset);
+
+void __timecompare_update(struct timecompare *sync,
+			  u64 source_tstamp)
+{
+	s64 offset;
+	u64 average_time;
+
+	if (!timecompare_offset(sync, &offset, &average_time))
+		return;
+
+	if (!sync->last_update) {
+		sync->last_update = average_time;
+		sync->offset = offset;
+		sync->skew = 0;
+	} else {
+		s64 delta_nsec = average_time - sync->last_update;
+
+		/* avoid division by negative or small deltas */
+		if (delta_nsec >= 10000) {
+			s64 delta_offset_nsec = offset - sync->offset;
+			s64 skew; /* delta_offset_nsec *
+				     TIMECOMPARE_SKEW_RESOLUTION /
+				     delta_nsec */
+			u64 divisor;
+
+			/* div_s64() is limited to 32 bit divisor */
+			skew = delta_offset_nsec * TIMECOMPARE_SKEW_RESOLUTION;
+			divisor = delta_nsec;
+			while (unlikely(divisor >= ((s64)1) << 32)) {
+				/* divide both by 2; beware, right shift
+				   of negative value has undefined
+				   behavior and can only be used for
+				   the positive divisor */
+				skew = div_s64(skew, 2);
+				divisor >>= 1;
+			}
+			skew = div_s64(skew, divisor);
+
+			/*
+			 * Calculate new overall skew as 4/16 the
+			 * old value and 12/16 the new one. This is
+			 * a rather arbitrary tradeoff between
+			 * only using the latest measurement (0/16 and
+			 * 16/16) and even more weight on past measurements.
+			 */
+#define TIMECOMPARE_NEW_SKEW_PER_16 12
+			sync->skew =
+				div_s64((16 - TIMECOMPARE_NEW_SKEW_PER_16) *
+					sync->skew +
+					TIMECOMPARE_NEW_SKEW_PER_16 * skew,
+					16);
+			sync->last_update = average_time;
+			sync->offset = offset;
+		}
+	}
+}
+EXPORT_SYMBOL(__timecompare_update);