1 files changed, 363 insertions, 37 deletions

diff --git a/kernel/timer.c b/kernel/timer.c
index eb97371b87d8..5a8960253063 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) {
@@ -780,36 +766,378 @@ static void update_wall_time_one_tick(void)
  * Return how long ticks are at the moment, that is, how much time
  * update_wall_time_one_tick will add to xtime next time we call it
  * (assuming no calls to do_adjtimex in the meantime).
- * The return value is in fixed-point nanoseconds with SHIFT_SCALE-10
- * bits to the right of the binary point.
+ * The return value is in fixed-point nanoseconds shifted by the
+ * specified number of bits to the right of the binary point.
  * This function has no side-effects.
  */
 u64 current_tick_length(void)
 {
         long delta_nsec;
+        u64 ret;
 
+        /* calculate the finest interval NTP will allow.
+         *    ie: nanosecond value shifted by (SHIFT_SCALE - 10)
+         */
         delta_nsec = tick_nsec + adjtime_adjustment() * 1000;
-        return ((u64) delta_nsec << (SHIFT_SCALE - 10)) + time_adj;
+        ret = (u64)delta_nsec << TICK_LENGTH_SHIFT;
+        ret += (s64)time_adj << (TICK_LENGTH_SHIFT - (SHIFT_SCALE - 10));
+
+        return ret;
 }
 
-/*
- * Using a loop looks inefficient, but "ticks" is
- * usually just one (we shouldn't be losing ticks,
- * we're doing this this way mainly for interrupt
- * latency reasons, not because we think we'll
- * have lots of lost timer ticks
+/* XXX - all of this timekeeping code should be later moved to time.c */
+#include <linux/clocksource.h>
+static struct clocksource *clock; /* pointer to current clocksource */
+
+#ifdef CONFIG_GENERIC_TIME
+/**
+ * __get_nsec_offset - Returns nanoseconds since last call to periodic_hook
+ *
+ * private function, must hold xtime_lock lock when being
+ * called. Returns the number of nanoseconds since the
+ * last call to update_wall_time() (adjusted by NTP scaling)
+ */
+static inline s64 __get_nsec_offset(void)
+{
+        cycle_t cycle_now, cycle_delta;
+        s64 ns_offset;
+
+        /* read clocksource: */
+        cycle_now = clocksource_read(clock);
+
+        /* calculate the delta since the last update_wall_time: */
+        cycle_delta = (cycle_now - clock->cycle_last) & clock->mask;
+
+        /* convert to nanoseconds: */
+        ns_offset = cyc2ns(clock, cycle_delta);
+
+        return ns_offset;
+}
+
+/**
+ * __get_realtime_clock_ts - Returns the time of day in a timespec
+ * @ts:         pointer to the timespec to be set
+ *
+ * Returns the time of day in a timespec. Used by
+ * do_gettimeofday() and get_realtime_clock_ts().
  */
-static void update_wall_time(unsigned long ticks)
+static inline void __get_realtime_clock_ts(struct timespec *ts)
 {
+        unsigned long seq;
+        s64 nsecs;
+
+        do {
+                seq = read_seqbegin(&xtime_lock);
+
+                *ts = xtime;
+                nsecs = __get_nsec_offset();
+
+        } while (read_seqretry(&xtime_lock, seq));
+
+        timespec_add_ns(ts, nsecs);
+}
+
+/**
+ * getnstimeofday - Returns the time of day in a timespec
+ * @ts:         pointer to the timespec to be set
+ *
+ * Returns the time of day in a timespec.
+ */
+void getnstimeofday(struct timespec *ts)
+{
+        __get_realtime_clock_ts(ts);
+}
+
+EXPORT_SYMBOL(getnstimeofday);
+
+/**
+ * do_gettimeofday - Returns the time of day in a timeval
+ * @tv:         pointer to the timeval to be set
+ *
+ * NOTE: Users should be converted to using get_realtime_clock_ts()
+ */
+void do_gettimeofday(struct timeval *tv)
+{
+        struct timespec now;
+
+        __get_realtime_clock_ts(&now);
+        tv->tv_sec = now.tv_sec;
+        tv->tv_usec = now.tv_nsec/1000;
+}
+
+EXPORT_SYMBOL(do_gettimeofday);
+/**
+ * do_settimeofday - Sets the time of day
+ * @tv:         pointer to the timespec variable containing the new time
+ *
+ * Sets the time of day to the new time and update NTP and notify hrtimers
+ */
+int do_settimeofday(struct timespec *tv)
+{
+        unsigned long flags;
+        time_t wtm_sec, sec = tv->tv_sec;
+        long wtm_nsec, nsec = tv->tv_nsec;
+
+        if ((unsigned long)tv->tv_nsec >= NSEC_PER_SEC)
+                return -EINVAL;
+
+        write_seqlock_irqsave(&xtime_lock, flags);
+
+        nsec -= __get_nsec_offset();
+
+        wtm_sec  = wall_to_monotonic.tv_sec + (xtime.tv_sec - sec);
+        wtm_nsec = wall_to_monotonic.tv_nsec + (xtime.tv_nsec - nsec);
+
+        set_normalized_timespec(&xtime, sec, nsec);
+        set_normalized_timespec(&wall_to_monotonic, wtm_sec, wtm_nsec);
+
+        ntp_clear();
+
+        write_sequnlock_irqrestore(&xtime_lock, flags);
+
+        /* signal hrtimers about time change */
+        clock_was_set();
+
+        return 0;
+}
+
+EXPORT_SYMBOL(do_settimeofday);
+
+/**
+ * change_clocksource - Swaps clocksources if a new one is available
+ *
+ * Accumulates current time interval and initializes new clocksource
+ */
+static int change_clocksource(void)
+{
+        struct clocksource *new;
+        cycle_t now;
+        u64 nsec;
+        new = clocksource_get_next();
+        if (clock != new) {
+                now = clocksource_read(new);
+                nsec =  __get_nsec_offset();
+                timespec_add_ns(&xtime, nsec);
+
+                clock = new;
+                clock->cycle_last = now;
+                printk(KERN_INFO "Time: %s clocksource has been installed.\n",
+                                        clock->name);
+                return 1;
+        } else if (clock->update_callback) {
+                return clock->update_callback();
+        }
+        return 0;
+}
+#else
+#define change_clocksource() (0)
+#endif
+
+/**
+ * timeofday_is_continuous - check to see if timekeeping is free running
+ */
+int timekeeping_is_continuous(void)
+{
+        unsigned long seq;
+        int ret;
+
         do {
-                ticks--;
-                update_wall_time_one_tick();
-                if (xtime.tv_nsec >= 1000000000) {
-                        xtime.tv_nsec -= 1000000000;
+                seq = read_seqbegin(&xtime_lock);
+
+                ret = clock->is_continuous;
+
+        } while (read_seqretry(&xtime_lock, seq));
+
+        return ret;
+}
+
+/*
+ * timekeeping_init - Initializes the clocksource and common timekeeping values
+ */
+void __init timekeeping_init(void)
+{
+        unsigned long flags;
+
+        write_seqlock_irqsave(&xtime_lock, flags);
+        clock = clocksource_get_next();
+        clocksource_calculate_interval(clock, tick_nsec);
+        clock->cycle_last = clocksource_read(clock);
+        ntp_clear();
+        write_sequnlock_irqrestore(&xtime_lock, flags);
+}
+
+
+/*
+ * timekeeping_resume - Resumes the generic timekeeping subsystem.
+ * @dev:        unused
+ *
+ * This is for the generic clocksource timekeeping.
+ * xtime/wall_to_monotonic/jiffies/wall_jiffies/etc are
+ * still managed by arch specific suspend/resume code.
+ */
+static int timekeeping_resume(struct sys_device *dev)
+{
+        unsigned long flags;
+
+        write_seqlock_irqsave(&xtime_lock, flags);
+        /* restart the last cycle value */
+        clock->cycle_last = clocksource_read(clock);
+        write_sequnlock_irqrestore(&xtime_lock, flags);
+        return 0;
+}
+
+/* sysfs resume/suspend bits for timekeeping */
+static struct sysdev_class timekeeping_sysclass = {
+        .resume         = timekeeping_resume,
+        set_kset_name("timekeeping"),
+};
+
+static struct sys_device device_timer = {
+        .id             = 0,
+        .cls            = &timekeeping_sysclass,
+};
+
+static int __init timekeeping_init_device(void)
+{
+        int error = sysdev_class_register(&timekeeping_sysclass);
+        if (!error)
+                error = sysdev_register(&device_timer);
+        return error;
+}
+
+device_initcall(timekeeping_init_device);
+
+/*
+ * If the error is already larger, we look ahead another tick,
+ * to compensate for late or lost adjustments.
+ */
+static __always_inline int clocksource_bigadjust(int sign, s64 error, s64 *interval, s64 *offset)
+{
+        int adj;
+
+        /*
+         * As soon as the machine is synchronized to the external time
+         * source this should be the common case.
+         */
+        error >>= 2;
+        if (likely(sign > 0 ? error <= *interval : error >= *interval))
+                return sign;
+
+        /*
+         * An extra look ahead dampens the effect of the current error,
+         * which can grow quite large with continously late updates, as
+         * it would dominate the adjustment value and can lead to
+         * oscillation.
+         */
+        error += current_tick_length() >> (TICK_LENGTH_SHIFT - clock->shift + 1);
+        error -= clock->xtime_interval >> 1;
+
+        adj = 0;
+        while (1) {
+                error >>= 1;
+                if (sign > 0 ? error <= *interval : error >= *interval)
+                        break;
+                adj++;
+        }
+
+        /*
+         * Add the current adjustments to the error and take the offset
+         * into account, the latter can cause the error to be hardly
+         * reduced at the next tick. Check the error again if there's
+         * room for another adjustment, thus further reducing the error
+         * which otherwise had to be corrected at the next update.
+         */
+        error = (error << 1) - *interval + *offset;
+        if (sign > 0 ? error > *interval : error < *interval)
+                adj++;
+
+        *interval <<= adj;
+        *offset <<= adj;
+        return sign << adj;
+}
+
+/*
+ * Adjust the multiplier to reduce the error value,
+ * this is optimized for the most common adjustments of -1,0,1,
+ * for other values we can do a bit more work.
+ */
+static void clocksource_adjust(struct clocksource *clock, s64 offset)
+{
+        s64 error, interval = clock->cycle_interval;
+        int adj;
+
+        error = clock->error >> (TICK_LENGTH_SHIFT - clock->shift - 1);
+        if (error > interval) {
+                adj = clocksource_bigadjust(1, error, &interval, &offset);
+        } else if (error < -interval) {
+                interval = -interval;
+                offset = -offset;
+                adj = clocksource_bigadjust(-1, error, &interval, &offset);
+        } else
+                return;
+
+        clock->mult += adj;
+        clock->xtime_interval += interval;
+        clock->xtime_nsec -= offset;
+        clock->error -= (interval - offset) << (TICK_LENGTH_SHIFT - clock->shift);
+}
+
+/*
+ * update_wall_time - Uses the current clocksource to increment the wall time
+ *
+ * Called from the timer interrupt, must hold a write on xtime_lock.
+ */
+static void update_wall_time(void)
+{
+        cycle_t offset;
+
+        clock->xtime_nsec += (s64)xtime.tv_nsec << clock->shift;
+
+#ifdef CONFIG_GENERIC_TIME
+        offset = (clocksource_read(clock) - clock->cycle_last) & clock->mask;
+#else
+        offset = clock->cycle_interval;
+#endif
+
+        /* normally this loop will run just once, however in the
+         * case of lost or late ticks, it will accumulate correctly.
+         */
+        while (offset >= clock->cycle_interval) {
+                /* accumulate one interval */
+                clock->xtime_nsec += clock->xtime_interval;
+                clock->cycle_last += clock->cycle_interval;
+                offset -= clock->cycle_interval;
+
+                if (clock->xtime_nsec >= (u64)NSEC_PER_SEC << clock->shift) {
+                        clock->xtime_nsec -= (u64)NSEC_PER_SEC << clock->shift;
                         xtime.tv_sec++;
                         second_overflow();
                 }
-        } while (ticks);
+
+                /* interpolator bits */
+                time_interpolator_update(clock->xtime_interval
+                                                >> clock->shift);
+                /* increment the NTP state machine */
+                update_ntp_one_tick();
+
+                /* accumulate error between NTP and clock interval */
+                clock->error += current_tick_length();
+                clock->error -= clock->xtime_interval << (TICK_LENGTH_SHIFT - clock->shift);
+        }
+
+        /* correct the clock when NTP error is too big */
+        clocksource_adjust(clock, offset);
+
+        /* store full nanoseconds into xtime */
+        xtime.tv_nsec = clock->xtime_nsec >> clock->shift;
+        clock->xtime_nsec -= (s64)xtime.tv_nsec << clock->shift;
+
+        /* check to see if there is a new clocksource to use */
+        if (change_clocksource()) {
+                clock->error = 0;
+                clock->xtime_nsec = 0;
+                clocksource_calculate_interval(clock, tick_nsec);
+        }
 }
 
 /*
@@ -915,10 +1243,8 @@ static inline void update_times(void)
         unsigned long ticks;
 
         ticks = jiffies - wall_jiffies;
-        if (ticks) {
-                wall_jiffies += ticks;
-                update_wall_time(ticks);
-        }
+        wall_jiffies += ticks;
+        update_wall_time();
         calc_load(ticks);
 }
   
@@ -1326,7 +1652,7 @@ static void __devinit migrate_timers(int cpu)
 }
 #endif /* CONFIG_HOTPLUG_CPU */
 
-static int timer_cpu_notify(struct notifier_block *self,
+static int __devinit timer_cpu_notify(struct notifier_block *self,
                                 unsigned long action, void *hcpu)
 {
         long cpu = (long)hcpu;
@@ -1346,7 +1672,7 @@ static int timer_cpu_notify(struct notifier_block *self,
         return NOTIFY_OK;
 }
 
-static struct notifier_block timers_nb = {
+static struct notifier_block __devinitdata timers_nb = {
         .notifier_call  = timer_cpu_notify,
 };