[PATCH 01/12] timekeeping: create kernel/time/timekeeping.c

Daniel Walker
2007-01-23T05:53:48Z

[-- Attachment #1: timekeeping_move_out_of_timer_c.patch --]
[-- Type: text/plain, Size: 38400 bytes --]

Move the generic timekeeping code from kernel/timer.c to
kernel/time/timekeeping.c . This requires some glue code which is
added to the include/linux/timekeeping.h header.

Signed-Off-By: Daniel Walker <dwalker@mvista.com>

---
include/linux/clocksource.h | 3
include/linux/timekeeping.h | 19 +
kernel/time/Makefile | 2
kernel/time/clocksource.c | 3
kernel/time/timekeeping.c | 639 ++++++++++++++++++++++++++++++++++++++++++++
kernel/timer.c | 630 -------------------------------------------
6 files changed, 663 insertions(+), 633 deletions(-)

Index: linux-2.6.19/include/linux/clocksource.h
===================================================================
--- linux-2.6.19.orig/include/linux/clocksource.h
+++ linux-2.6.19/include/linux/clocksource.h
@@ -18,6 +18,9 @@
/* clocksource cycle base type */
typedef u64 cycle_t;

+/* XXX - Would like a better way for initializing curr_clocksource */
+extern struct clocksource clocksource_jiffies;
+
/**
* struct clocksource - hardware abstraction for a free running counter
* Provides mostly state-free accessors to the underlying hardware.
Index: linux-2.6.19/include/linux/timekeeping.h
===================================================================
--- /dev/null
+++ linux-2.6.19/include/linux/timekeeping.h
@@ -0,0 +1,19 @@
+#ifndef _LINUX_TIMEKEEPING_H
+#define _LINUX_TIMEKEEPING_H
+
+#include <linux/clocksource.h>
+
+extern void update_wall_time(void);
+
+#ifdef CONFIG_GENERIC_TIME
+
+extern struct clocksource *clock;
+
+#else /* CONFIG_GENERIC_TIME */
+static inline int change_clocksource(void)
+{
+ return 0;
+}
+#endif /* !CONFIG_GENERIC_TIME */
+
+#endif /* _LINUX_TIMEKEEPING_H */
Index: linux-2.6.19/kernel/time/Makefile
===================================================================
--- linux-2.6.19.orig/kernel/time/Makefile
+++ linux-2.6.19/kernel/time/Makefile
@@ -1,4 +1,4 @@
-obj-y += ntp.o clocksource.o jiffies.o timer_list.o
+obj-y += ntp.o clocksource.o jiffies.o timer_list.o timekeeping.o

obj-$(CONFIG_GENERIC_CLOCKEVENTS) += clockevents.o
obj-$(CONFIG_TIMER_STATS) += timer_stats.o
Index: linux-2.6.19/kernel/time/clocksource.c
===================================================================
--- linux-2.6.19.orig/kernel/time/clocksource.c
+++ linux-2.6.19/kernel/time/clocksource.c
@@ -29,9 +29,6 @@
#include <linux/init.h>
#include <linux/module.h>

-/* XXX - Would like a better way for initializing curr_clocksource */
-extern struct clocksource clocksource_jiffies;
-
/*[Clocksource internal variables]---------
* curr_clocksource:
* currently selected clocksource. Initialized to clocksource_jiffies.
Index: linux-2.6.19/kernel/time/timekeeping.c
===================================================================
--- /dev/null
+++ linux-2.6.19/kernel/time/timekeeping.c
@@ -0,0 +1,639 @@
+
+
+#include <linux/module.h>
+#include <linux/timekeeping.h>
+#include <linux/time.h>
+#include <linux/hrtimer.h>
+
+/*
+ * flag for if timekeeping is suspended
+ */
+static int timekeeping_suspended;
+
+/*
+ * time in seconds when suspend began
+ */
+static unsigned long timekeeping_suspend_time;
+
+/*
+ * Clock used for timekeeping
+ */
+struct clocksource *clock = &clocksource_jiffies;
+
+/*
+ * The current time
+ * wall_to_monotonic is what we need to add to xtime (or xtime corrected
+ * for sub jiffie times) to get to monotonic time. Monotonic is pegged
+ * at zero at system boot time, so wall_to_monotonic will be negative,
+ * however, we will ALWAYS keep the tv_nsec part positive so we can use
+ * the usual normalization.
+ */
+struct timespec xtime __attribute__ ((aligned (16)));
+struct timespec wall_to_monotonic __attribute__ ((aligned (16)));
+
+EXPORT_SYMBOL(xtime);
+
+#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 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);
+
+ clock->error = 0;
+ 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;
+}
+
+/**
+ * timeofday_is_continuous - check to see if timekeeping is free running
+ */
+int timekeeping_is_continuous(void)
+{
+ unsigned long seq;
+ int ret;
+
+ do {
+ seq = read_seqbegin(&xtime_lock);
+
+ ret = clock->is_continuous;
+
+ } while (read_seqretry(&xtime_lock, seq));
+
+ return ret;
+}
+#endif /* CONFIG_GENERIC_TIME */
+
+/**
+ * read_persistent_clock - Return time in seconds from the persistent clock.
+ *
+ * Weak dummy function for arches that do not yet support it.
+ * Returns seconds from epoch using the battery backed persistent clock.
+ * Returns zero if unsupported.
+ *
+ * XXX - Do be sure to remove it once all arches implement it.
+ */
+unsigned long __attribute__((weak)) read_persistent_clock(void)
+{
+ return 0;
+}
+
+/*
+ * timekeeping_init - Initializes the clocksource and common timekeeping values
+ */
+void __init timekeeping_init(void)
+{
+ unsigned long flags;
+ unsigned long sec = read_persistent_clock();
+
+ write_seqlock_irqsave(&xtime_lock, flags);
+
+ ntp_clear();
+
+ clock = clocksource_get_next();
+ clocksource_calculate_interval(clock, tick_nsec);
+ clock->cycle_last = clocksource_read(clock);
+
+ xtime.tv_sec = sec;
+ xtime.tv_nsec = 0;
+ set_normalized_timespec(&wall_to_monotonic,
+ -xtime.tv_sec, -xtime.tv_nsec);
+
+ write_sequnlock_irqrestore(&xtime_lock, flags);
+}
+
+
+/* flag for if timekeeping is suspended */
+static int timekeeping_suspended;
+/* time in seconds when suspend began */
+static unsigned long timekeeping_suspend_time;
+
+/**
+ * timekeeping_resume - Resumes the generic timekeeping subsystem.
+ * @dev: unused
+ *
+ * This is for the generic clocksource timekeeping.
+ * xtime/wall_to_monotonic/jiffies/etc are
+ * still managed by arch specific suspend/resume code.
+ */
+static int timekeeping_resume(struct sys_device *dev)
+{
+ unsigned long flags;
+ unsigned long now = read_persistent_clock();
+
+ write_seqlock_irqsave(&xtime_lock, flags);
+
+ if (now && (now > timekeeping_suspend_time)) {
+ unsigned long sleep_length = now - timekeeping_suspend_time;
+ xtime.tv_sec += sleep_length;
+ jiffies_64 += (u64)sleep_length * HZ;
+ }
+ /* re-base the last cycle value */
+ clock->cycle_last = clocksource_read(clock);
+ clock->error = 0;
+ timekeeping_suspended = 0;
+ write_sequnlock_irqrestore(&xtime_lock, flags);
+
+ hrtimer_notify_resume();
+
+ return 0;
+}
+
+static int timekeeping_suspend(struct sys_device *dev, pm_message_t state)
+{
+ unsigned long flags;
+
+ write_seqlock_irqsave(&xtime_lock, flags);
+ timekeeping_suspended = 1;
+ timekeeping_suspend_time = read_persistent_clock();
+ write_sequnlock_irqrestore(&xtime_lock, flags);
+ return 0;
+}
+
+/* sysfs resume/suspend bits for timekeeping */
+static struct sysdev_class timekeeping_sysclass = {
+ .resume = timekeeping_resume,
+ .suspend = timekeeping_suspend,
+ 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 even further
+ * to compensate for late or lost adjustments.
+ */
+static __always_inline int clocksource_bigadjust(s64 error, s64 *interval,
+ s64 *offset)
+{
+ s64 tick_error, i;
+ u32 look_ahead, adj;
+ s32 error2, mult;
+
+ /*
+ * Use the current error value to determine how much to look ahead.
+ * The larger the error the slower we adjust for it to avoid problems
+ * with losing too many ticks, otherwise we would overadjust and
+ * produce an even larger error. The smaller the adjustment the
+ * faster we try to adjust for it, as lost ticks can do less harm
+ * here. This is tuned so that an error of about 1 msec is adusted
+ * within about 1 sec (or 2^20 nsec in 2^SHIFT_HZ ticks).
+ */
+ error2 = clock->error >> (TICK_LENGTH_SHIFT + 22 - 2 * SHIFT_HZ);
+ error2 = abs(error2);
+ for (look_ahead = 0; error2 > 0; look_ahead++)
+ error2 >>= 2;
+
+ /*
+ * Now calculate the error in (1 << look_ahead) ticks, but first
+ * remove the single look ahead already included in the error.
+ */
+ tick_error = current_tick_length() >>
+ (TICK_LENGTH_SHIFT - clock->shift + 1);
+ tick_error -= clock->xtime_interval >> 1;
+ error = ((error - tick_error) >> look_ahead) + tick_error;
+
+ /* Finally calculate the adjustment shift value. */
+ i = *interval;
+ mult = 1;
+ if (error < 0) {
+ error = -error;
+ *interval = -*interval;
+ *offset = -*offset;
+ mult = -1;
+ }
+ for (adj = 0; error > i; adj++)
+ error >>= 1;
+
+ *interval <<= adj;
+ *offset <<= adj;
+ return mult << 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) {
+ error >>= 2;
+ if (likely(error <= interval))
+ adj = 1;
+ else
+ adj = clocksource_bigadjust(error, &interval, &offset);
+ } else if (error < -interval) {
+ error >>= 2;
+ if (likely(error >= -interval)) {
+ adj = -1;
+ interval = -interval;
+ offset = -offset;
+ } else
+ adj = clocksource_bigadjust(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.
+ */
+void update_wall_time(void)
+{
+ cycle_t offset;
+
+ /* Make sure we're fully resumed: */
+ if (unlikely(timekeeping_suspended))
+ return;
+
+#ifdef CONFIG_GENERIC_TIME
+ offset = (clocksource_read(clock) - clock->cycle_last) & clock->mask;
+#else
+ offset = clock->cycle_interval;
+#endif
+ clock->xtime_nsec += (s64)xtime.tv_nsec << clock->shift;
+
+ /* 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();
+ }
+
+ /* interpolator bits */
+ time_interpolator_update(clock->xtime_interval
+ >> clock->shift);
+
+ /* 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 = (s64)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;
+ hrtimer_clock_notify();
+ clocksource_calculate_interval(clock, tick_nsec);
+ }
+ update_vsyscall(&xtime, clock);
+}
+
+#ifdef CONFIG_TIME_INTERPOLATION
+
+struct time_interpolator *time_interpolator __read_mostly;
+static struct time_interpolator *time_interpolator_list __read_mostly;
+static DEFINE_SPINLOCK(time_interpolator_lock);
+
+static inline cycles_t time_interpolator_get_cycles(unsigned int src)
+{
+ unsigned long (*x)(void);
+
+ switch (src)
+ {
+ case TIME_SOURCE_FUNCTION:
+ x = time_interpolator->addr;
+ return x();
+
+ case TIME_SOURCE_MMIO64 :
+ return readq_relaxed((void __iomem *)time_interpolator->addr);
+
+ case TIME_SOURCE_MMIO32 :
+ return readl_relaxed((void __iomem *)time_interpolator->addr);
+
+ default: return get_cycles();
+ }
+}
+
+static inline u64 time_interpolator_get_counter(int writelock)
+{
+ unsigned int src = time_interpolator->source;
+
+ if (time_interpolator->jitter)
+ {
+ cycles_t lcycle;
+ cycles_t now;
+
+ do {
+ lcycle = time_interpolator->last_cycle;
+ now = time_interpolator_get_cycles(src);
+ if (lcycle && time_after(lcycle, now))
+ return lcycle;
+
+ /* When holding the xtime write lock, there's no need
+ * to add the overhead of the cmpxchg. Readers are
+ * force to retry until the write lock is released.
+ */
+ if (writelock) {
+ time_interpolator->last_cycle = now;
+ return now;
+ }
+ /* Keep track of the last timer value returned. The use of cmpxchg here
+ * will cause contention in an SMP environment.
+ */
+ } while (unlikely(cmpxchg(&time_interpolator->last_cycle, lcycle, now) != lcycle));
+ return now;
+ }
+ else
+ return time_interpolator_get_cycles(src);
+}
+
+void time_interpolator_reset(void)
+{
+ time_interpolator->offset = 0;
+ time_interpolator->last_counter = time_interpolator_get_counter(1);
+}
+
+#define GET_TI_NSECS(count,i) (((((count) - i->last_counter) & (i)->mask) * (i)->nsec_per_cyc) >> (i)->shift)
+
+unsigned long time_interpolator_get_offset(void)
+{
+ /* If we do not have a time interpolator set up then just return zero */
+ if (!time_interpolator)
+ return 0;
+
+ return time_interpolator->offset +
+ GET_TI_NSECS(time_interpolator_get_counter(0), time_interpolator);
+}
+
+#define INTERPOLATOR_ADJUST 65536
+#define INTERPOLATOR_MAX_SKIP 10*INTERPOLATOR_ADJUST
+
+void time_interpolator_update(long delta_nsec)
+{
+ u64 counter;
+ unsigned long offset;
+
+ /* If there is no time interpolator set up then do nothing */
+ if (!time_interpolator)
+ return;
+
+ /*
+ * The interpolator compensates for late ticks by accumulating the late
+ * time in time_interpolator->offset. A tick earlier than expected will
+ * lead to a reset of the offset and a corresponding jump of the clock
+ * forward. Again this only works if the interpolator clock is running
+ * slightly slower than the regular clock and the tuning logic insures
+ * that.
+ */
+
+ counter = time_interpolator_get_counter(1);
+ offset = time_interpolator->offset +
+ GET_TI_NSECS(counter, time_interpolator);
+
+ if (delta_nsec < 0 || (unsigned long) delta_nsec < offset)
+ time_interpolator->offset = offset - delta_nsec;
+ else {
+ time_interpolator->skips++;
+ time_interpolator->ns_skipped += delta_nsec - offset;
+ time_interpolator->offset = 0;
+ }
+ time_interpolator->last_counter = counter;
+
+ /* Tuning logic for time interpolator invoked every minute or so.
+ * Decrease interpolator clock speed if no skips occurred and an offset is carried.
+ * Increase interpolator clock speed if we skip too much time.
+ */
+ if (jiffies % INTERPOLATOR_ADJUST == 0)
+ {
+ if (time_interpolator->skips == 0 && time_interpolator->offset > tick_nsec)
+ time_interpolator->nsec_per_cyc--;
+ if (time_interpolator->ns_skipped > INTERPOLATOR_MAX_SKIP && time_interpolator->offset == 0)
+ time_interpolator->nsec_per_cyc++;
+ time_interpolator->skips = 0;
+ time_interpolator->ns_skipped = 0;
+ }
+}
+
+static inline int
+is_better_time_interpolator(struct time_interpolator *new)
+{
+ if (!time_interpolator)
+ return 1;
+ return new->frequency > 2*time_interpolator->frequency ||
+ (unsigned long)new->drift < (unsigned long)time_interpolator->drift;
+}
+
+void
+register_time_interpolator(struct time_interpolator *ti)
+{
+ unsigned long flags;
+
+ /* Sanity check */
+ BUG_ON(ti->frequency == 0 || ti->mask == 0);
+
+ ti->nsec_per_cyc = ((u64)NSEC_PER_SEC << ti->shift) / ti->frequency;
+ spin_lock(&time_interpolator_lock);
+ write_seqlock_irqsave(&xtime_lock, flags);
+ if (is_better_time_interpolator(ti)) {
+ time_interpolator = ti;
+ time_interpolator_reset();
+ }
+ write_sequnlock_irqrestore(&xtime_lock, flags);
+
+ ti->next = time_interpolator_list;
+ time_interpolator_list = ti;
+ spin_unlock(&time_interpolator_lock);
+}
+
+void
+unregister_time_interpolator(struct time_interpolator *ti)
+{
+ struct time_interpolator *curr, **prev;
+ unsigned long flags;
+
+ spin_lock(&time_interpolator_lock);
+ prev = &time_interpolator_list;
+ for (curr = *prev; curr; curr = curr->next) {
+ if (curr == ti) {
+ *prev = curr->next;
+ break;
+ }
+ prev = &curr->next;
+ }
+
+ write_seqlock_irqsave(&xtime_lock, flags);
+ if (ti == time_interpolator) {
+ /* we lost the best time-interpolator: */
+ time_interpolator = NULL;
+ /* find the next-best interpolator */
+ for (curr = time_interpolator_list; curr; curr = curr->next)
+ if (is_better_time_interpolator(curr))
+ time_interpolator = curr;
+ time_interpolator_reset();
+ }
+ write_sequnlock_irqrestore(&xtime_lock, flags);
+ spin_unlock(&time_interpolator_lock);
+}
+#endif /* CONFIG_TIME_INTERPOLATION */
+
Index: linux-2.6.19/kernel/timer.c
===================================================================
--- linux-2.6.19.orig/kernel/timer.c
+++ linux-2.6.19/kernel/timer.c
@@ -35,6 +35,7 @@
#include <linux/syscalls.h>
#include <linux/delay.h>
#include <linux/kallsyms.h>
+#include <linux/timekeeping.h>

#include <asm/uaccess.h>
#include <asm/unistd.h>
@@ -761,447 +762,6 @@ unsigned long next_timer_interrupt(void)

#endif

-/******************************************************************/
-
-/*
- * The current time
- * wall_to_monotonic is what we need to add to xtime (or xtime corrected
- * for sub jiffie times) to get to monotonic time. Monotonic is pegged
- * at zero at system boot time, so wall_to_monotonic will be negative,
- * however, we will ALWAYS keep the tv_nsec part positive so we can use
- * the usual normalization.
- */
-struct timespec xtime __attribute__ ((aligned (16)));
-struct timespec wall_to_monotonic __attribute__ ((aligned (16)));
-
-EXPORT_SYMBOL(xtime);
-
-
-/* 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 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);
-
- clock->error = 0;
- 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
-static inline int change_clocksource(void)
-{
- return 0;
-}
-#endif
-
-/**
- * timeofday_is_continuous - check to see if timekeeping is free running
- */
-int timekeeping_is_continuous(void)
-{
- unsigned long seq;
- int ret;
-
- do {
- seq = read_seqbegin(&xtime_lock);
-
- ret = clock->is_continuous;
-
- } while (read_seqretry(&xtime_lock, seq));
-
- return ret;
-}
-
-/**
- * read_persistent_clock - Return time in seconds from the persistent clock.
- *
- * Weak dummy function for arches that do not yet support it.
- * Returns seconds from epoch using the battery backed persistent clock.
- * Returns zero if unsupported.
- *
- * XXX - Do be sure to remove it once all arches implement it.
- */
-unsigned long __attribute__((weak)) read_persistent_clock(void)
-{
- return 0;
-}
-
-/*
- * timekeeping_init - Initializes the clocksource and common timekeeping values
- */
-void __init timekeeping_init(void)
-{
- unsigned long flags;
- unsigned long sec = read_persistent_clock();
-
- write_seqlock_irqsave(&xtime_lock, flags);
-
- ntp_clear();
-
- clock = clocksource_get_next();
- clocksource_calculate_interval(clock, tick_nsec);
- clock->cycle_last = clocksource_read(clock);
-
- xtime.tv_sec = sec;
- xtime.tv_nsec = 0;
- set_normalized_timespec(&wall_to_monotonic,
- -xtime.tv_sec, -xtime.tv_nsec);
-
- write_sequnlock_irqrestore(&xtime_lock, flags);
-}
-
-
-/* flag for if timekeeping is suspended */
-static int timekeeping_suspended;
-/* time in seconds when suspend began */
-static unsigned long timekeeping_suspend_time;
-
-/**
- * timekeeping_resume - Resumes the generic timekeeping subsystem.
- * @dev: unused
- *
- * This is for the generic clocksource timekeeping.
- * xtime/wall_to_monotonic/jiffies/etc are
- * still managed by arch specific suspend/resume code.
- */
-static int timekeeping_resume(struct sys_device *dev)
-{
- unsigned long flags;
- unsigned long now = read_persistent_clock();
-
- write_seqlock_irqsave(&xtime_lock, flags);
-
- if (now && (now > timekeeping_suspend_time)) {
- unsigned long sleep_length = now - timekeeping_suspend_time;
- xtime.tv_sec += sleep_length;
- jiffies_64 += (u64)sleep_length * HZ;
- }
- /* re-base the last cycle value */
- clock->cycle_last = clocksource_read(clock);
- clock->error = 0;
- timekeeping_suspended = 0;
- write_sequnlock_irqrestore(&xtime_lock, flags);
-
- hrtimer_notify_resume();
-
- return 0;
-}
-
-static int timekeeping_suspend(struct sys_device *dev, pm_message_t state)
-{
- unsigned long flags;
-
- write_seqlock_irqsave(&xtime_lock, flags);
- timekeeping_suspended = 1;
- timekeeping_suspend_time = read_persistent_clock();
- write_sequnlock_irqrestore(&xtime_lock, flags);
- return 0;
-}
-
-/* sysfs resume/suspend bits for timekeeping */
-static struct sysdev_class timekeeping_sysclass = {
- .resume = timekeeping_resume,
- .suspend = timekeeping_suspend,
- 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 even further
- * to compensate for late or lost adjustments.
- */
-static __always_inline int clocksource_bigadjust(s64 error, s64 *interval,
- s64 *offset)
-{
- s64 tick_error, i;
- u32 look_ahead, adj;
- s32 error2, mult;
-
- /*
- * Use the current error value to determine how much to look ahead.
- * The larger the error the slower we adjust for it to avoid problems
- * with losing too many ticks, otherwise we would overadjust and
- * produce an even larger error. The smaller the adjustment the
- * faster we try to adjust for it, as lost ticks can do less harm
- * here. This is tuned so that an error of about 1 msec is adusted
- * within about 1 sec (or 2^20 nsec in 2^SHIFT_HZ ticks).
- */
- error2 = clock->error >> (TICK_LENGTH_SHIFT + 22 - 2 * SHIFT_HZ);
- error2 = abs(error2);
- for (look_ahead = 0; error2 > 0; look_ahead++)
- error2 >>= 2;
-
- /*
- * Now calculate the error in (1 << look_ahead) ticks, but first
- * remove the single look ahead already included in the error.
- */
- tick_error = current_tick_length() >>
- (TICK_LENGTH_SHIFT - clock->shift + 1);
- tick_error -= clock->xtime_interval >> 1;
- error = ((error - tick_error) >> look_ahead) + tick_error;
-
- /* Finally calculate the adjustment shift value. */
- i = *interval;
- mult = 1;
- if (error < 0) {
- error = -error;
- *interval = -*interval;
- *offset = -*offset;
- mult = -1;
- }
- for (adj = 0; error > i; adj++)
- error >>= 1;
-
- *interval <<= adj;
- *offset <<= adj;
- return mult << 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) {
- error >>= 2;
- if (likely(error <= interval))
- adj = 1;
- else
- adj = clocksource_bigadjust(error, &interval, &offset);
- } else if (error < -interval) {
- error >>= 2;
- if (likely(error >= -interval)) {
- adj = -1;
- interval = -interval;
- offset = -offset;
- } else
- adj = clocksource_bigadjust(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;
-
- /* Make sure we're fully resumed: */
- if (unlikely(timekeeping_suspended))
- return;
-
-#ifdef CONFIG_GENERIC_TIME
- offset = (clocksource_read(clock) - clock->cycle_last) & clock->mask;
-#else
- offset = clock->cycle_interval;
-#endif
- clock->xtime_nsec += (s64)xtime.tv_nsec << clock->shift;
-
- /* 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();
- }
-
- /* interpolator bits */
- time_interpolator_update(clock->xtime_interval
- >> clock->shift);
-
- /* 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 = (s64)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;
- hrtimer_clock_notify();
- clocksource_calculate_interval(clock, tick_nsec);
- }
- update_vsyscall(&xtime, clock);
-}
-
/*
* Called from the timer interrupt handler to charge one tick to the current
* process. user_tick is 1 if the tick is user time, 0 for system.
@@ -1733,194 +1293,6 @@ void __init init_timers(void)
open_softirq(TIMER_SOFTIRQ, run_timer_softirq, NULL);
}

-#ifdef CONFIG_TIME_INTERPOLATION
-
-struct time_interpolator *time_interpolator __read_mostly;
-static struct time_interpolator *time_interpolator_list __read_mostly;
-static DEFINE_SPINLOCK(time_interpolator_lock);
-
-static inline cycles_t time_interpolator_get_cycles(unsigned int src)
-{
- unsigned long (*x)(void);
-
- switch (src)
- {
- case TIME_SOURCE_FUNCTION:
- x = time_interpolator->addr;
- return x();
-
- case TIME_SOURCE_MMIO64 :
- return readq_relaxed((void __iomem *)time_interpolator->addr);
-
- case TIME_SOURCE_MMIO32 :
- return readl_relaxed((void __iomem *)time_interpolator->addr);
-
- default: return get_cycles();
- }
-}
-
-static inline u64 time_interpolator_get_counter(int writelock)
-{
- unsigned int src = time_interpolator->source;
-
- if (time_interpolator->jitter)
- {
- cycles_t lcycle;
- cycles_t now;
-
- do {
- lcycle = time_interpolator->last_cycle;
- now = time_interpolator_get_cycles(src);
- if (lcycle && time_after(lcycle, now))
- return lcycle;
-
- /* When holding the xtime write lock, there's no need
- * to add the overhead of the cmpxchg. Readers are
- * force to retry until the write lock is released.
- */
- if (writelock) {
- time_interpolator->last_cycle = now;
- return now;
- }
- /* Keep track of the last timer value returned. The use of cmpxchg here
- * will cause contention in an SMP environment.
- */
- } while (unlikely(cmpxchg(&time_interpolator->last_cycle, lcycle, now) != lcycle));
- return now;
- }
- else
- return time_interpolator_get_cycles(src);
-}
-
-void time_interpolator_reset(void)
-{
- time_interpolator->offset = 0;
- time_interpolator->last_counter = time_interpolator_get_counter(1);
-}
-
-#define GET_TI_NSECS(count,i) (((((count) - i->last_counter) & (i)->mask) * (i)->nsec_per_cyc) >> (i)->shift)
-
-unsigned long time_interpolator_get_offset(void)
-{
- /* If we do not have a time interpolator set up then just return zero */
- if (!time_interpolator)
- return 0;
-
- return time_interpolator->offset +
- GET_TI_NSECS(time_interpolator_get_counter(0), time_interpolator);
-}
-
-#define INTERPOLATOR_ADJUST 65536
-#define INTERPOLATOR_MAX_SKIP 10*INTERPOLATOR_ADJUST
-
-void time_interpolator_update(long delta_nsec)
-{
- u64 counter;
- unsigned long offset;
-
- /* If there is no time interpolator set up then do nothing */
- if (!time_interpolator)
- return;
-
- /*
- * The interpolator compensates for late ticks by accumulating the late
- * time in time_interpolator->offset. A tick earlier than expected will
- * lead to a reset of the offset and a corresponding jump of the clock
- * forward. Again this only works if the interpolator clock is running
- * slightly slower than the regular clock and the tuning logic insures
- * that.
- */
-
- counter = time_interpolator_get_counter(1);
- offset = time_interpolator->offset +
- GET_TI_NSECS(counter, time_interpolator);
-
- if (delta_nsec < 0 || (unsigned long) delta_nsec < offset)
- time_interpolator->offset = offset - delta_nsec;
- else {
- time_interpolator->skips++;
- time_interpolator->ns_skipped += delta_nsec - offset;
- time_interpolator->offset = 0;
- }
- time_interpolator->last_counter = counter;
-
- /* Tuning logic for time interpolator invoked every minute or so.
- * Decrease interpolator clock speed if no skips occurred and an offset is carried.
- * Increase interpolator clock speed if we skip too much time.
- */
- if (jiffies % INTERPOLATOR_ADJUST == 0)
- {
- if (time_interpolator->skips == 0 && time_interpolator->offset > tick_nsec)
- time_interpolator->nsec_per_cyc--;
- if (time_interpolator->ns_skipped > INTERPOLATOR_MAX_SKIP && time_interpolator->offset == 0)
- time_interpolator->nsec_per_cyc++;
- time_interpolator->skips = 0;
- time_interpolator->ns_skipped = 0;
- }
-}
-
-static inline int
-is_better_time_interpolator(struct time_interpolator *new)
-{
- if (!time_interpolator)
- return 1;
- return new->frequency > 2*time_interpolator->frequency ||
- (unsigned long)new->drift < (unsigned long)time_interpolator->drift;
-}
-
-void
-register_time_interpolator(struct time_interpolator *ti)
-{
- unsigned long flags;
-
- /* Sanity check */
- BUG_ON(ti->frequency == 0 || ti->mask == 0);
-
- ti->nsec_per_cyc = ((u64)NSEC_PER_SEC << ti->shift) / ti->frequency;
- spin_lock(&time_interpolator_lock);
- write_seqlock_irqsave(&xtime_lock, flags);
- if (is_better_time_interpolator(ti)) {
- time_interpolator = ti;
- time_interpolator_reset();
- }
- write_sequnlock_irqrestore(&xtime_lock, flags);
-
- ti->next = time_interpolator_list;
- time_interpolator_list = ti;
- spin_unlock(&time_interpolator_lock);
-}
-
-void
-unregister_time_interpolator(struct time_interpolator *ti)
-{
- struct time_interpolator *curr, **prev;
- unsigned long flags;
-
- spin_lock(&time_interpolator_lock);
- prev = &time_interpolator_list;
- for (curr = *prev; curr; curr = curr->next) {
- if (curr == ti) {
- *prev = curr->next;
- break;
- }
- prev = &curr->next;
- }
-
- write_seqlock_irqsave(&xtime_lock, flags);
- if (ti == time_interpolator) {
- /* we lost the best time-interpolator: */
- time_interpolator = NULL;
- /* find the next-best interpolator */
- for (curr = time_interpolator_list; curr; curr = curr->next)
- if (is_better_time_interpolator(curr))
- time_interpolator = curr;
- time_interpolator_reset();
- }
- write_sequnlock_irqrestore(&xtime_lock, flags);
- spin_unlock(&time_interpolator_lock);
-}
-#endif /* CONFIG_TIME_INTERPOLATION */
-
/**
* msleep - sleep safely even with waitqueue interruptions
* @msecs: Time in milliseconds to sleep for

--