1 files changed, 28 insertions, 19 deletions

diff --git a/kernel/timer.c b/kernel/timer.c
index 623f9ea198d8..6811436a031d 100644
--- a/kernel/timer.c
+++ b/kernel/timer.c
@@ -597,7 +597,6 @@ long time_tolerance = MAXFREQ;		/* frequency tolerance (ppm)	*/
 long time_precision = 1;                /* clock precision (us)         */
 long time_maxerror = NTP_PHASE_LIMIT;   /* maximum error (us)           */
 long time_esterror = NTP_PHASE_LIMIT;   /* estimated error (us)         */
-static long time_phase;                 /* phase offset (scaled us)     */
 long time_freq = (((NSEC_PER_SEC + HZ/2) % HZ - HZ/2) << SHIFT_USEC) / NSEC_PER_USEC;
                                         /* frequency offset (scaled ppm)*/
 static long time_adj;                   /* tick adjust (scaled 1 / HZ)  */
@@ -747,27 +746,14 @@ static long adjtime_adjustment(void)
 }
 
 /* in the NTP reference this is called "hardclock()" */
-static void update_wall_time_one_tick(void)
+static void update_ntp_one_tick(void)
 {
-        long time_adjust_step, delta_nsec;
+        long time_adjust_step;
 
         time_adjust_step = adjtime_adjustment();
         if (time_adjust_step)
                 /* Reduce by this step the amount of time left  */
                 time_adjust -= time_adjust_step;
-        delta_nsec = tick_nsec + time_adjust_step * 1000;
-        /*
-         * Advance the phase, once it gets to one microsecond, then
-         * advance the tick more.
-         */
-        time_phase += time_adj;
-        if ((time_phase >= FINENSEC) || (time_phase <= -FINENSEC)) {
-                long ltemp = shift_right(time_phase, (SHIFT_SCALE - 10));
-                time_phase -= ltemp << (SHIFT_SCALE - 10);
-                delta_nsec += ltemp;
-        }
-        xtime.tv_nsec += delta_nsec;
-        time_interpolator_update(delta_nsec);
 
         /* Changes by adjtime() do not take effect till next tick. */
         if (time_next_adjust != 0) {
@@ -872,8 +858,13 @@ device_initcall(timekeeping_init_device);
  */
 static void update_wall_time(void)
 {
+        static s64 remainder_snsecs, error;
+        s64 snsecs_per_sec;
         cycle_t now, offset;
 
+        snsecs_per_sec = (s64)NSEC_PER_SEC << clock->shift;
+        remainder_snsecs += (s64)xtime.tv_nsec << clock->shift;
+
         now = read_clocksource(clock);
         offset = (now - last_clock_cycle)&clock->mask;
 
@@ -881,17 +872,35 @@ static void update_wall_time(void)
          * case of lost or late ticks, it will accumulate correctly.
          */
         while (offset > clock->interval_cycles) {
+                /* get the ntp interval in clock shifted nanoseconds */
+                s64 ntp_snsecs  = current_tick_length(clock->shift);
+
                 /* accumulate one interval */
+                remainder_snsecs += clock->interval_snsecs;
                 last_clock_cycle += clock->interval_cycles;
                 offset -= clock->interval_cycles;
 
-                update_wall_time_one_tick();
-                if (xtime.tv_nsec >= 1000000000) {
-                        xtime.tv_nsec -= 1000000000;
+                /* interpolator bits */
+                time_interpolator_update(clock->interval_snsecs
+                                                >> clock->shift);
+                /* increment the NTP state machine */
+                update_ntp_one_tick();
+
+                /* accumulate error between NTP and clock interval */
+                error += (ntp_snsecs - (s64)clock->interval_snsecs);
+
+                /* correct the clock when NTP error is too big */
+                remainder_snsecs += make_ntp_adj(clock, offset, &error);
+
+                if (remainder_snsecs >= snsecs_per_sec) {
+                        remainder_snsecs -= snsecs_per_sec;
                         xtime.tv_sec++;
                         second_overflow();
                 }
         }
+        /* store full nanoseconds into xtime */
+        xtime.tv_nsec = remainder_snsecs >> clock->shift;
+        remainder_snsecs -= (s64)xtime.tv_nsec << clock->shift;
 }
 
 /*