timekeeping: Introduce struct timekeeper

	now = get_clock();

	tod_to_timeval(now - TOD_UNIX_EPOCH, &xtime);

	clocksource_tod.cycle_last = now;

	clocksource_tod.raw_time = xtime;

	tod_to_timeval(sched_clock_base_cc - TOD_UNIX_EPOCH, &ts);

	set_normalized_timespec(&wall_to_monotonic, -ts.tv_sec, -ts.tv_nsec);

	write_sequnlock_irqrestore(&xtime_lock, flags);

 * @flags:		flags describing special properties

 * @vread:		vsyscall based read

 * @resume:		resume function for the clocksource, if necessary

 * @cycle_interval:	Used internally by timekeeping core, please ignore.

 * @xtime_interval:	Used internally by timekeeping core, please ignore.

 */

struct clocksource {

	/*

#define CLKSRC_FSYS_MMIO_SET(mmio, addr)      do { } while (0)

#endif

	/* timekeeping specific data, ignore */

	cycle_t cycle_interval;

	u64	xtime_interval;

	u32	raw_interval;

	/*

	 * Second part is written at each timer interrupt

	 * Keep it in a different cache line to dirty no

	 * more than one cache line.

	 */

	cycle_t cycle_last ____cacheline_aligned_in_smp;

	u64 xtime_nsec;

	s64 error;

	struct timespec raw_time;

#ifdef CONFIG_CLOCKSOURCE_WATCHDOG

	/* Watchdog related data, used by the framework */

#endif

};

extern struct clocksource *clock;	/* current clocksource */

/*

 * Clock source flags bits::

 */

}

/**

 * cyc2ns - converts clocksource cycles to nanoseconds

 * @cs:		Pointer to clocksource

 * @cycles:	Cycles

 * clocksource_cyc2ns - converts clocksource cycles to nanoseconds

 *

 * Uses the clocksource and ntp ajdustment to convert cycle_ts to nanoseconds.

 * Converts cycles to nanoseconds, using the given mult and shift.

 *

 * XXX - This could use some mult_lxl_ll() asm optimization

 */

static inline s64 cyc2ns(struct clocksource *cs, cycle_t cycles)

static inline s64 clocksource_cyc2ns(cycle_t cycles, u32 mult, u32 shift)

{

	u64 ret = (u64)cycles;

	ret = (ret * cs->mult) >> cs->shift;

	return ret;

}

/**

 * clocksource_calculate_interval - Calculates a clocksource interval struct

 *

 * @c:		Pointer to clocksource.

 * @length_nsec: Desired interval length in nanoseconds.

 *

 * Calculates a fixed cycle/nsec interval for a given clocksource/adjustment

 * pair and interval request.

 *

 * Unless you're the timekeeping code, you should not be using this!

 */

static inline void clocksource_calculate_interval(struct clocksource *c,

					  	  unsigned long length_nsec)

{

	u64 tmp;

	/* Do the ns -> cycle conversion first, using original mult */

	tmp = length_nsec;

	tmp <<= c->shift;

	tmp += c->mult_orig/2;

	do_div(tmp, c->mult_orig);

	c->cycle_interval = (cycle_t)tmp;

	if (c->cycle_interval == 0)

		c->cycle_interval = 1;

	/* Go back from cycles -> shifted ns, this time use ntp adjused mult */

	c->xtime_interval = (u64)c->cycle_interval * c->mult;

	c->raw_interval = ((u64)c->cycle_interval * c->mult_orig) >> c->shift;

	return ((u64) cycles * mult) >> shift;

}

		goto out;

	wdnow = watchdog->read(watchdog);

	wd_nsec = cyc2ns(watchdog, (wdnow - watchdog_last) & watchdog->mask);

	wd_nsec = clocksource_cyc2ns((wdnow - watchdog_last) & watchdog->mask,

				     watchdog->mult, watchdog->shift);

	watchdog_last = wdnow;

	list_for_each_entry(cs, &watchdog_list, wd_list) {

		}

		/* Check the deviation from the watchdog clocksource. */

		cs_nsec = cyc2ns(cs, (csnow - cs->wd_last) & cs->mask);

		cs_nsec = clocksource_cyc2ns((csnow - cs->wd_last) &

					     cs->mask, cs->mult, cs->shift);

		cs->wd_last = csnow;

		if (abs(cs_nsec - wd_nsec) > WATCHDOG_THRESHOLD) {

			clocksource_unstable(cs, cs_nsec - wd_nsec);

#include <linux/time.h>

#include <linux/tick.h>

/* Structure holding internal timekeeping values. */

struct timekeeper {

	/* Current clocksource used for timekeeping. */

	struct clocksource *clock;

	/* Number of clock cycles in one NTP interval. */

	cycle_t cycle_interval;

	/* Number of clock shifted nano seconds in one NTP interval. */

	u64	xtime_interval;

	/* Raw nano seconds accumulated per NTP interval. */

	u32	raw_interval;

	/* Clock shifted nano seconds remainder not stored in xtime.tv_nsec. */

	u64	xtime_nsec;

	/* Difference between accumulated time and NTP time in ntp

	 * shifted nano seconds. */

	s64	ntp_error;

};

struct timekeeper timekeeper;

/**

 * timekeeper_setup_internals - Set up internals to use clocksource clock.

 *

 * @clock:		Pointer to clocksource.

 *

 * Calculates a fixed cycle/nsec interval for a given clocksource/adjustment

 * pair and interval request.

 *

 * Unless you're the timekeeping code, you should not be using this!

 */

static void timekeeper_setup_internals(struct clocksource *clock)

{

	cycle_t interval;

	u64 tmp;

	timekeeper.clock = clock;

	clock->cycle_last = clock->read(clock);

	/* Do the ns -> cycle conversion first, using original mult */

	tmp = NTP_INTERVAL_LENGTH;

	tmp <<= clock->shift;

	tmp += clock->mult_orig/2;

	do_div(tmp, clock->mult_orig);

	if (tmp == 0)

		tmp = 1;

	interval = (cycle_t) tmp;

	timekeeper.cycle_interval = interval;

	/* Go back from cycles -> shifted ns */

	timekeeper.xtime_interval = (u64) interval * clock->mult;

	timekeeper.raw_interval =

		((u64) interval * clock->mult_orig) >> clock->shift;

	timekeeper.xtime_nsec = 0;

	timekeeper.ntp_error = 0;

}

/*

 * This read-write spinlock protects us from races in SMP while

struct timespec wall_to_monotonic __attribute__ ((aligned (16)));

static unsigned long total_sleep_time;		/* seconds */

/*

 * The raw monotonic time for the CLOCK_MONOTONIC_RAW posix clock.

 */

struct timespec raw_time;

/* flag for if timekeeping is suspended */

int __read_mostly timekeeping_suspended;

	timespec_add_ns(&xtime_cache, nsec);

}

struct clocksource *clock;

/* must hold xtime_lock */

void timekeeping_leap_insert(int leapsecond)

{

	xtime.tv_sec += leapsecond;

	wall_to_monotonic.tv_sec -= leapsecond;

	update_vsyscall(&xtime, clock);

	update_vsyscall(&xtime, timekeeper.clock);

}

#ifdef CONFIG_GENERIC_TIME

/**

 * clocksource_forward_now - update clock to the current time

 * timekeeping_forward_now - update clock to the current time

 *

 * Forward the current clock to update its state since the last call to

 * update_wall_time(). This is useful before significant clock changes,

 * as it avoids having to deal with this time offset explicitly.

 */

static void clocksource_forward_now(void)

static void timekeeping_forward_now(void)

{

	cycle_t cycle_now, cycle_delta;

	struct clocksource *clock;

	s64 nsec;

	clock = timekeeper.clock;

	cycle_now = clock->read(clock);

	cycle_delta = (cycle_now - clock->cycle_last) & clock->mask;

	clock->cycle_last = cycle_now;

	nsec = cyc2ns(clock, cycle_delta);

	nsec = clocksource_cyc2ns(cycle_delta, clock->mult, clock->shift);

	/* If arch requires, add in gettimeoffset() */

	nsec += arch_gettimeoffset();

	timespec_add_ns(&xtime, nsec);

	nsec = ((s64)cycle_delta * clock->mult_orig) >> clock->shift;

	clock->raw_time.tv_nsec += nsec;

	nsec = clocksource_cyc2ns(cycle_delta, clock->mult_orig, clock->shift);

	timespec_add_ns(&raw_time, nsec);

}

/**

void getnstimeofday(struct timespec *ts)

{

	cycle_t cycle_now, cycle_delta;

	struct clocksource *clock;

	unsigned long seq;

	s64 nsecs;

		*ts = xtime;

		/* read clocksource: */

		clock = timekeeper.clock;

		cycle_now = clock->read(clock);

		/* calculate the delta since the last update_wall_time: */

		cycle_delta = (cycle_now - clock->cycle_last) & clock->mask;

		/* convert to nanoseconds: */

		nsecs = cyc2ns(clock, cycle_delta);

		nsecs = clocksource_cyc2ns(cycle_delta, clock->mult,

					   clock->shift);

		/* If arch requires, add in gettimeoffset() */

		nsecs += arch_gettimeoffset();

ktime_t ktime_get(void)

{

	cycle_t cycle_now, cycle_delta;

	struct clocksource *clock;

	unsigned int seq;

	s64 secs, nsecs;

		nsecs = xtime.tv_nsec + wall_to_monotonic.tv_nsec;

		/* read clocksource: */

		clock = timekeeper.clock;

		cycle_now = clock->read(clock);

		/* calculate the delta since the last update_wall_time: */

		cycle_delta = (cycle_now - clock->cycle_last) & clock->mask;

		/* convert to nanoseconds: */

		nsecs += cyc2ns(clock, cycle_delta);

		nsecs += clocksource_cyc2ns(cycle_delta, clock->mult,

					    clock->shift);

	} while (read_seqretry(&xtime_lock, seq));

	/*

void ktime_get_ts(struct timespec *ts)

{

	cycle_t cycle_now, cycle_delta;

	struct clocksource *clock;

	struct timespec tomono;

	unsigned int seq;

	s64 nsecs;

		tomono = wall_to_monotonic;

		/* read clocksource: */

		clock = timekeeper.clock;

		cycle_now = clock->read(clock);

		/* calculate the delta since the last update_wall_time: */

		cycle_delta = (cycle_now - clock->cycle_last) & clock->mask;

		/* convert to nanoseconds: */

		nsecs = cyc2ns(clock, cycle_delta);

		nsecs = clocksource_cyc2ns(cycle_delta, clock->mult,

					   clock->shift);

	} while (read_seqretry(&xtime_lock, seq));

	write_seqlock_irqsave(&xtime_lock, flags);

	clocksource_forward_now();

	timekeeping_forward_now();

	ts_delta.tv_sec = tv->tv_sec - xtime.tv_sec;

	ts_delta.tv_nsec = tv->tv_nsec - xtime.tv_nsec;

	update_xtime_cache(0);

	clock->error = 0;

	timekeeper.ntp_error = 0;

	ntp_clear();

	update_vsyscall(&xtime, clock);

	update_vsyscall(&xtime, timekeeper.clock);

	write_sequnlock_irqrestore(&xtime_lock, flags);

	new = clocksource_get_next();

	if (!new || clock == new)

	if (!new || timekeeper.clock == new)

		return;

	clocksource_forward_now();

	timekeeping_forward_now();

	if (new->enable && !new->enable(new))

		return;

	 */

	new->mult_orig = new->mult;

	new->raw_time = clock->raw_time;

	old = clock;

	clock = new;

	old = timekeeper.clock;

	timekeeper_setup_internals(new);

	/*

	 * Save mult_orig in mult so that the value can be restored

	 * regardless if ->enable() updates the value of mult or not.

	if (old->disable)

		old->disable(old);

	clock->cycle_last = clock->read(clock);

	clock->error = 0;

	clock->xtime_nsec = 0;

	clocksource_calculate_interval(clock, NTP_INTERVAL_LENGTH);

	tick_clock_notify();

	/*

	 * We're holding xtime lock and waking up klogd would deadlock

	 * us on enqueue.  So no printing!

	printk(KERN_INFO "Time: %s clocksource has been installed.\n",

	       clock->name);

	 */

}

#else /* GENERIC_TIME */

static inline void clocksource_forward_now(void) { }

static inline void timekeeping_forward_now(void) { }

static inline void change_clocksource(void) { }

/**

	unsigned long seq;

	s64 nsecs;

	cycle_t cycle_now, cycle_delta;

	struct clocksource *clock;

	do {

		seq = read_seqbegin(&xtime_lock);

		/* read clocksource: */

		clock = timekeeper.clock;

		cycle_now = clock->read(clock);

		/* calculate the delta since the last update_wall_time: */

		cycle_delta = (cycle_now - clock->cycle_last) & clock->mask;

		/* convert to nanoseconds: */

		nsecs = ((s64)cycle_delta * clock->mult_orig) >> clock->shift;

		nsecs = clocksource_cyc2ns(cycle_delta, clock->mult_orig,

					   clock->shift);

		*ts = clock->raw_time;

		*ts = raw_time;

	} while (read_seqretry(&xtime_lock, seq));

	do {

		seq = read_seqbegin(&xtime_lock);

		ret = clock->flags & CLOCK_SOURCE_VALID_FOR_HRES;

		ret = timekeeper.clock->flags & CLOCK_SOURCE_VALID_FOR_HRES;

	} while (read_seqretry(&xtime_lock, seq));

 */

void __init timekeeping_init(void)

{

	struct clocksource *clock;

	unsigned long flags;

	unsigned long sec = read_persistent_clock();

		clock->enable(clock);

	/* set mult_orig on enable */

	clock->mult_orig = clock->mult;

	clocksource_calculate_interval(clock, NTP_INTERVAL_LENGTH);

	clock->cycle_last = clock->read(clock);

	timekeeper_setup_internals(clock);

	xtime.tv_sec = sec;

	xtime.tv_nsec = 0;

	raw_time.tv_sec = 0;

	raw_time.tv_nsec = 0;

	set_normalized_timespec(&wall_to_monotonic,

		-xtime.tv_sec, -xtime.tv_nsec);

	update_xtime_cache(0);

	}

	update_xtime_cache(0);

	/* re-base the last cycle value */

	clock->cycle_last = clock->read(clock);

	clock->error = 0;

	timekeeper.clock->cycle_last = timekeeper.clock->read(timekeeper.clock);

	timekeeper.ntp_error = 0;

	timekeeping_suspended = 0;

	write_sequnlock_irqrestore(&xtime_lock, flags);

	timekeeping_suspend_time = read_persistent_clock();

	write_seqlock_irqsave(&xtime_lock, flags);

	clocksource_forward_now();

	timekeeping_forward_now();

	timekeeping_suspended = 1;

	write_sequnlock_irqrestore(&xtime_lock, flags);

 * 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,

static __always_inline int timekeeping_bigadjust(s64 error, s64 *interval,

						 s64 *offset)

{

	s64 tick_error, i;

	 * here.  This is tuned so that an error of about 1 msec is adjusted

	 * within about 1 sec (or 2^20 nsec in 2^SHIFT_HZ ticks).

	 */

	error2 = clock->error >> (NTP_SCALE_SHIFT + 22 - 2 * SHIFT_HZ);

	error2 = timekeeper.ntp_error >> (NTP_SCALE_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 = tick_length >> (NTP_SCALE_SHIFT - clock->shift + 1);

	tick_error -= clock->xtime_interval >> 1;

	tick_error = tick_length >>

			(NTP_SCALE_SHIFT - timekeeper.clock->shift + 1);

	tick_error -= timekeeper.xtime_interval >> 1;

	error = ((error - tick_error) >> look_ahead) + tick_error;

	/* Finally calculate the adjustment shift 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(s64 offset)

static void timekeeping_adjust(s64 offset)

{

	s64 error, interval = clock->cycle_interval;

	s64 error, interval = timekeeper.cycle_interval;

	int adj;

	error = clock->error >> (NTP_SCALE_SHIFT - clock->shift - 1);

	error = timekeeper.ntp_error >>

		(NTP_SCALE_SHIFT - timekeeper.clock->shift - 1);

	if (error > interval) {

		error >>= 2;

		if (likely(error <= interval))

			adj = 1;

		else

			adj = clocksource_bigadjust(error, &interval, &offset);

			adj = timekeeping_bigadjust(error, &interval, &offset);

	} else if (error < -interval) {

		error >>= 2;

		if (likely(error >= -interval)) {

			interval = -interval;

			offset = -offset;

		} else

			adj = clocksource_bigadjust(error, &interval, &offset);

			adj = timekeeping_bigadjust(error, &interval, &offset);

	} else

		return;

	clock->mult += adj;

	clock->xtime_interval += interval;

	clock->xtime_nsec -= offset;

	clock->error -= (interval - offset) <<

			(NTP_SCALE_SHIFT - clock->shift);

	timekeeper.clock->mult += adj;

	timekeeper.xtime_interval += interval;

	timekeeper.xtime_nsec -= offset;

	timekeeper.ntp_error -= (interval - offset) <<

			(NTP_SCALE_SHIFT - timekeeper.clock->shift);

}

/**

 */

void update_wall_time(void)

{

	struct clocksource *clock;

	cycle_t offset;

	s64 nsecs;

	/* Make sure we're fully resumed: */

	if (unlikely(timekeeping_suspended))

		return;

	clock = timekeeper.clock;

#ifdef CONFIG_GENERIC_TIME

	offset = (clock->read(clock) - clock->cycle_last) & clock->mask;

#else

	offset = clock->cycle_interval;

	offset = timekeeper.cycle_interval;

#endif

	clock->xtime_nsec = (s64)xtime.tv_nsec << clock->shift;

	timekeeper.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) {

	while (offset >= timekeeper.cycle_interval) {

		u64 nsecps = (u64)NSEC_PER_SEC << clock->shift;

		/* accumulate one interval */

		offset -= clock->cycle_interval;

		clock->cycle_last += clock->cycle_interval;

		offset -= timekeeper.cycle_interval;

		clock->cycle_last += timekeeper.cycle_interval;

		clock->xtime_nsec += clock->xtime_interval;

		if (clock->xtime_nsec >= (u64)NSEC_PER_SEC << clock->shift) {

			clock->xtime_nsec -= (u64)NSEC_PER_SEC << clock->shift;

		timekeeper.xtime_nsec += timekeeper.xtime_interval;

		if (timekeeper.xtime_nsec >= nsecps) {

			timekeeper.xtime_nsec -= nsecps;

			xtime.tv_sec++;

			second_overflow();

		}

		clock->raw_time.tv_nsec += clock->raw_interval;

		if (clock->raw_time.tv_nsec >= NSEC_PER_SEC) {

			clock->raw_time.tv_nsec -= NSEC_PER_SEC;

			clock->raw_time.tv_sec++;

		raw_time.tv_nsec += timekeeper.raw_interval;

		if (raw_time.tv_nsec >= NSEC_PER_SEC) {

			raw_time.tv_nsec -= NSEC_PER_SEC;

			raw_time.tv_sec++;

		}

		/* accumulate error between NTP and clock interval */

		clock->error += tick_length;

		clock->error -= clock->xtime_interval << (NTP_SCALE_SHIFT - clock->shift);

		timekeeper.ntp_error += tick_length;

		timekeeper.ntp_error -= timekeeper.xtime_interval <<

					(NTP_SCALE_SHIFT - clock->shift);

	}

	/* correct the clock when NTP error is too big */

	clocksource_adjust(offset);

	timekeeping_adjust(offset);

	/*

	 * Since in the loop above, we accumulate any amount of time

	 * in xtime_nsec over a second into xtime.tv_sec, its possible for

	 * xtime_nsec to be fairly small after the loop. Further, if we're

	 * slightly speeding the clocksource up in clocksource_adjust(),

	 * slightly speeding the clocksource up in timekeeping_adjust(),

	 * its possible the required corrective factor to xtime_nsec could

	 * cause it to underflow.

	 *

	 * We'll correct this error next time through this function, when

	 * xtime_nsec is not as small.

	 */

	if (unlikely((s64)clock->xtime_nsec < 0)) {

		s64 neg = -(s64)clock->xtime_nsec;

		clock->xtime_nsec = 0;