path: root/kernel/time/timekeeping.c

/*
 *  linux/kernel/time/timekeeping.c
 *
 *  Kernel timekeeping code and accessor functions
 *
 *  This code was moved from linux/kernel/timer.c.
 *  Please see that file for copyright and history logs.
 *
 */

#include <linux/timekeeper_internal.h>
#include <linux/module.h>
#include <linux/interrupt.h>
#include <linux/percpu.h>
#include <linux/init.h>
#include <linux/mm.h>
#include <linux/sched.h>
#include <linux/syscore_ops.h>
#include <linux/clocksource.h>
#include <linux/jiffies.h>
#include <linux/time.h>
#include <linux/tick.h>
#include <linux/stop_machine.h>


static struct timekeeper timekeeper;

/*
 * This read-write spinlock protects us from races in SMP while
 * playing with xtime.
 */
__cacheline_aligned_in_smp DEFINE_SEQLOCK(xtime_lock);

/* flag for if timekeeping is suspended */
int __read_mostly timekeeping_suspended;

static inline void tk_normalize_xtime(struct timekeeper *tk)
{
	while (tk->xtime_nsec >= ((u64)NSEC_PER_SEC << tk->shift)) {
		tk->xtime_nsec -= (u64)NSEC_PER_SEC << tk->shift;
		tk->xtime_sec++;
	}
}

static struct timespec tk_xtime(struct timekeeper *tk)
{
	struct timespec ts;

	ts.tv_sec = tk->xtime_sec;
	ts.tv_nsec = (long)(tk->xtime_nsec >> tk->shift);
	return ts;
}

static void tk_set_xtime(struct timekeeper *tk, const struct timespec *ts)
{
	tk->xtime_sec = ts->tv_sec;
	tk->xtime_nsec = (u64)ts->tv_nsec << tk->shift;
}

static void tk_xtime_add(struct timekeeper *tk, const struct timespec *ts)
{
	tk->xtime_sec += ts->tv_sec;
	tk->xtime_nsec += (u64)ts->tv_nsec << tk->shift;