[deliverable/linux.git] / kernel / time / ntp.c

/*
 * NTP state machine interfaces and logic.
 *
 * This code was mainly moved from kernel/timer.c and kernel/time.c
 * Please see those files for relevant copyright info and historical
 * changelogs.
 */
#include <linux/capability.h>
#include <linux/clocksource.h>
#include <linux/workqueue.h>
#include <linux/hrtimer.h>
#include <linux/jiffies.h>
#include <linux/math64.h>
#include <linux/timex.h>
#include <linux/time.h>
#include <linux/mm.h>

/*
 * NTP timekeeping variables:
 */

/* USER_HZ period (usecs): */
unsigned long			tick_usec = TICK_USEC;

/* ACTHZ period (nsecs): */
unsigned long			tick_nsec;

u64				tick_length;
static u64			tick_length_base;

static struct hrtimer		leap_timer;

#define MAX_TICKADJ		500LL		/* usecs */
#define MAX_TICKADJ_SCALED \
	(((MAX_TICKADJ * NSEC_PER_USEC) << NTP_SCALE_SHIFT) / NTP_INTERVAL_FREQ)

/*
 * phase-lock loop variables
 */

/*
 * clock synchronization status
 *
 * (TIME_ERROR prevents overwriting the CMOS clock)
 */
static int			time_state = TIME_OK;

/* clock status bits:							*/
int				time_status = STA_UNSYNC;

/* TAI offset (secs):							*/
static long			time_tai;

/* time adjustment (nsecs):						*/
static s64			time_offset;

/* pll time constant:							*/
static long			time_constant = 2;

/* maximum error (usecs):						*/
long				time_maxerror = NTP_PHASE_LIMIT;

/* estimated error (usecs):						*/
long				time_esterror = NTP_PHASE_LIMIT;

/* frequency offset (scaled nsecs/secs):				*/
static s64			time_freq;

/* time at last adjustment (secs):					*/
static long			time_reftime;

long				time_adjust;

static long			ntp_tick_adj;

/*
 * NTP methods:
 */

/*
 * Update (tick_length, tick_length_base, tick_nsec), based
 * on (tick_usec, ntp_tick_adj, time_freq):
 */
static void ntp_update_frequency(void)
{
	u64 second_length;
	u64 new_base;

	second_length		 = (u64)(tick_usec * NSEC_PER_USEC * USER_HZ)
						<< NTP_SCALE_SHIFT;

	second_length		+= (s64)ntp_tick_adj << NTP_SCALE_SHIFT;
	second_length		+= time_freq;

	tick_nsec		 = div_u64(second_length, HZ) >> NTP_SCALE_SHIFT;
	new_base		 = div_u64(second_length, NTP_INTERVAL_FREQ);

	/*
	 * Don't wait for the next second_overflow, apply
	 * the change to the tick length immediately:
	 */
	tick_length		+= new_base - tick_length_base;
	tick_length_base	 = new_base;
}

static inline s64 ntp_update_offset_fll(s64 freq_adj, s64 offset64, long secs)
{
	time_status &= ~STA_MODE;

	if (secs < MINSEC)
		return freq_adj;

	if (!(time_status & STA_FLL) && (secs <= MAXSEC))
		return freq_adj;

	freq_adj += div_s64(offset64 << (NTP_SCALE_SHIFT - SHIFT_FLL), secs);
	time_status |= STA_MODE;

	return freq_adj;
}

static void ntp_update_offset(long offset)
{
	s64 freq_adj;
	s64 offset64;
	long secs;

	if (!(time_status & STA_PLL))
		return;

	if (!(time_status & STA_NANO))
		offset *= NSEC_PER_USEC;

	/*
	 * Scale the phase adjustment and
	 * clamp to the operating range.
	 */
	offset = min(offset, MAXPHASE);
	offset = max(offset, -MAXPHASE);

	/*
	 * Select how the frequency is to be controlled
	 * and in which mode (PLL or FLL).
	 */
	if (time_status & STA_FREQHOLD || time_reftime == 0)
		time_reftime = xtime.tv_sec;

	secs = xtime.tv_sec - time_reftime;
	time_reftime = xtime.tv_sec;

	offset64    = offset;
	freq_adj    = (offset64 * secs) <<
			(NTP_SCALE_SHIFT - 2 * (SHIFT_PLL + 2 + time_constant));

	freq_adj    = ntp_update_offset_fll(freq_adj, offset64, secs);

	freq_adj    = min(freq_adj + time_freq, MAXFREQ_SCALED);

	time_freq   = max(freq_adj, -MAXFREQ_SCALED);

	time_offset = div_s64(offset64 << NTP_SCALE_SHIFT, NTP_INTERVAL_FREQ);
}

/**
 * ntp_clear - Clears the NTP state variables
 *
 * Must be called while holding a write on the xtime_lock
 */
void ntp_clear(void)
{
	time_adjust	= 0;		/* stop active adjtime() */
	time_status	|= STA_UNSYNC;
	time_maxerror	= NTP_PHASE_LIMIT;
	time_esterror	= NTP_PHASE_LIMIT;

	ntp_update_frequency();

	tick_length	= tick_length_base;
	time_offset	= 0;
}

/*
 * Leap second processing. If in leap-insert state at the end of the
 * day, the system clock is set back one second; if in leap-delete
 * state, the system clock is set ahead one second.
 */
static enum hrtimer_restart ntp_leap_second(struct hrtimer *timer)
{
	enum hrtimer_restart res = HRTIMER_NORESTART;

	write_seqlock(&xtime_lock);

	switch (time_state) {
	case TIME_OK:
		break;
	case TIME_INS:
		xtime.tv_sec--;
		wall_to_monotonic.tv_sec++;
		time_state = TIME_OOP;
		printk(KERN_NOTICE
			"Clock: inserting leap second 23:59:60 UTC\n");
		hrtimer_add_expires_ns(&leap_timer, NSEC_PER_SEC);
		res = HRTIMER_RESTART;
		break;
	case TIME_DEL:
		xtime.tv_sec++;
		time_tai--;
		wall_to_monotonic.tv_sec--;
		time_state = TIME_WAIT;
		printk(KERN_NOTICE
			"Clock: deleting leap second 23:59:59 UTC\n");
		break;
	case TIME_OOP:
		time_tai++;
		time_state = TIME_WAIT;
		/* fall through */
	case TIME_WAIT:
		if (!(time_status & (STA_INS | STA_DEL)))
			time_state = TIME_OK;
		break;
	}
	update_vsyscall(&xtime, clock);

	write_sequnlock(&xtime_lock);

	return res;
}

/*
 * this routine handles the overflow of the microsecond field
 *
 * The tricky bits of code to handle the accurate clock support
 * were provided by Dave Mills (Mills@UDEL.EDU) of NTP fame.
 * They were originally developed for SUN and DEC kernels.
 * All the kudos should go to Dave for this stuff.
 */
void second_overflow(void)
{
	s64 time_adj;

	/* Bump the maxerror field */
	time_maxerror += MAXFREQ / NSEC_PER_USEC;
	if (time_maxerror > NTP_PHASE_LIMIT) {
		time_maxerror = NTP_PHASE_LIMIT;
		time_status |= STA_UNSYNC;
	}

	/*
	 * Compute the phase adjustment for the next second. The offset is
	 * reduced by a fixed factor times the time constant.
	 */
	tick_length	= tick_length_base;
	time_adj	= shift_right(time_offset, SHIFT_PLL + time_constant);
	time_offset	-= time_adj;
	tick_length	+= time_adj;

	if (!time_adjust)
		return;

	if (time_adjust > MAX_TICKADJ) {
		time_adjust -= MAX_TICKADJ;
		tick_length += MAX_TICKADJ_SCALED;
		return;
	}

	if (time_adjust < -MAX_TICKADJ) {
		time_adjust += MAX_TICKADJ;
		tick_length -= MAX_TICKADJ_SCALED;
		return;
	}

	tick_length += (s64)(time_adjust * NSEC_PER_USEC / NTP_INTERVAL_FREQ)
							 << NTP_SCALE_SHIFT;
	time_adjust = 0;
}

#ifdef CONFIG_GENERIC_CMOS_UPDATE

/* Disable the cmos update - used by virtualization and embedded */
int no_sync_cmos_clock  __read_mostly;

static void sync_cmos_clock(struct work_struct *work);

static DECLARE_DELAYED_WORK(sync_cmos_work, sync_cmos_clock);

static void sync_cmos_clock(struct work_struct *work)
{
	struct timespec now, next;
	int fail = 1;

	/*
	 * If we have an externally synchronized Linux clock, then update
	 * CMOS clock accordingly every ~11 minutes. Set_rtc_mmss() has to be
	 * called as close as possible to 500 ms before the new second starts.
	 * This code is run on a timer.  If the clock is set, that timer
	 * may not expire at the correct time.  Thus, we adjust...
	 */
	if (!ntp_synced()) {
		/*
		 * Not synced, exit, do not restart a timer (if one is
		 * running, let it run out).
		 */
		return;
	}

	getnstimeofday(&now);
	if (abs(now.tv_nsec - (NSEC_PER_SEC / 2)) <= tick_nsec / 2)
		fail = update_persistent_clock(now);

	next.tv_nsec = (NSEC_PER_SEC / 2) - now.tv_nsec - (TICK_NSEC / 2);
	if (next.tv_nsec <= 0)
		next.tv_nsec += NSEC_PER_SEC;

	if (!fail)
		next.tv_sec = 659;
	else
		next.tv_sec = 0;

	if (next.tv_nsec >= NSEC_PER_SEC) {
		next.tv_sec++;
		next.tv_nsec -= NSEC_PER_SEC;
	}
	schedule_delayed_work(&sync_cmos_work, timespec_to_jiffies(&next));
}

static void notify_cmos_timer(void)
{
	if (!no_sync_cmos_clock)
		schedule_delayed_work(&sync_cmos_work, 0);
}

#else
static inline void notify_cmos_timer(void) { }
#endif

/*
 * adjtimex mainly allows reading (and writing, if superuser) of
 * kernel time-keeping variables. used by xntpd.
 */
int do_adjtimex(struct timex *txc)
{
	struct timespec ts;
	int result;

	/* Validate the data before disabling interrupts */
	if (txc->modes & ADJ_ADJTIME) {
		/* singleshot must not be used with any other mode bits */
		if (!(txc->modes & ADJ_OFFSET_SINGLESHOT))
			return -EINVAL;
		if (!(txc->modes & ADJ_OFFSET_READONLY) &&
		    !capable(CAP_SYS_TIME))
			return -EPERM;
	} else {
		/* In order to modify anything, you gotta be super-user! */
		 if (txc->modes && !capable(CAP_SYS_TIME))
			return -EPERM;

		/*
		 * if the quartz is off by more than 10% then
		 * something is VERY wrong!
		 */
		if (txc->modes & ADJ_TICK &&
		    (txc->tick <  900000/USER_HZ ||
		     txc->tick > 1100000/USER_HZ))
				return -EINVAL;

		if (txc->modes & ADJ_STATUS && time_state != TIME_OK)
			hrtimer_cancel(&leap_timer);
	}

	getnstimeofday(&ts);

	write_seqlock_irq(&xtime_lock);

	/* If there are input parameters, then process them */
	if (txc->modes & ADJ_ADJTIME) {
		long save_adjust = time_adjust;

		if (!(txc->modes & ADJ_OFFSET_READONLY)) {
			/* adjtime() is independent from ntp_adjtime() */
			time_adjust = txc->offset;
			ntp_update_frequency();
		}
		txc->offset = save_adjust;
		goto adj_done;
	}
	if (txc->modes) {
		long sec;

		if (txc->modes & ADJ_STATUS) {
			if ((time_status & STA_PLL) &&
			    !(txc->status & STA_PLL)) {
				time_state = TIME_OK;
				time_status = STA_UNSYNC;
			}
			/* only set allowed bits */
			time_status &= STA_RONLY;
			time_status |= txc->status & ~STA_RONLY;

			switch (time_state) {
			case TIME_OK:
			start_timer:
				sec = ts.tv_sec;
				if (time_status & STA_INS) {
					time_state = TIME_INS;
					sec += 86400 - sec % 86400;
					hrtimer_start(&leap_timer, ktime_set(sec, 0), HRTIMER_MODE_ABS);
				} else if (time_status & STA_DEL) {
					time_state = TIME_DEL;
					sec += 86400 - (sec + 1) % 86400;
					hrtimer_start(&leap_timer, ktime_set(sec, 0), HRTIMER_MODE_ABS);
				}
				break;
			case TIME_INS:
			case TIME_DEL:
				time_state = TIME_OK;
				goto start_timer;
				break;
			case TIME_WAIT:
				if (!(time_status & (STA_INS | STA_DEL)))
					time_state = TIME_OK;
				break;
			case TIME_OOP:
				hrtimer_restart(&leap_timer);
				break;
			}
		}

		if (txc->modes & ADJ_NANO)
			time_status |= STA_NANO;
		if (txc->modes & ADJ_MICRO)
			time_status &= ~STA_NANO;

		if (txc->modes & ADJ_FREQUENCY) {
			time_freq = (s64)txc->freq * PPM_SCALE;
			time_freq = min(time_freq, MAXFREQ_SCALED);
			time_freq = max(time_freq, -MAXFREQ_SCALED);
		}

		if (txc->modes & ADJ_MAXERROR)
			time_maxerror = txc->maxerror;
		if (txc->modes & ADJ_ESTERROR)
			time_esterror = txc->esterror;

		if (txc->modes & ADJ_TIMECONST) {
			time_constant = txc->constant;
			if (!(time_status & STA_NANO))
				time_constant += 4;
			time_constant = min(time_constant, (long)MAXTC);
			time_constant = max(time_constant, 0l);
		}

		if (txc->modes & ADJ_TAI && txc->constant > 0)
			time_tai = txc->constant;

		if (txc->modes & ADJ_OFFSET)
			ntp_update_offset(txc->offset);
		if (txc->modes & ADJ_TICK)
			tick_usec = txc->tick;

		if (txc->modes & (ADJ_TICK|ADJ_FREQUENCY|ADJ_OFFSET))
			ntp_update_frequency();
	}

	txc->offset = shift_right(time_offset * NTP_INTERVAL_FREQ,
				  NTP_SCALE_SHIFT);
	if (!(time_status & STA_NANO))
		txc->offset /= NSEC_PER_USEC;

adj_done:
	result = time_state;	/* mostly `TIME_OK' */
	if (time_status & (STA_UNSYNC|STA_CLOCKERR))
		result = TIME_ERROR;

	txc->freq	   = shift_right((time_freq >> PPM_SCALE_INV_SHIFT) *
					 (s64)PPM_SCALE_INV, NTP_SCALE_SHIFT);
	txc->maxerror	   = time_maxerror;
	txc->esterror	   = time_esterror;
	txc->status	   = time_status;
	txc->constant	   = time_constant;
	txc->precision	   = 1;
	txc->tolerance	   = MAXFREQ_SCALED / PPM_SCALE;
	txc->tick	   = tick_usec;
	txc->tai	   = time_tai;

	/* PPS is not implemented, so these are zero */
	txc->ppsfreq	   = 0;
	txc->jitter	   = 0;
	txc->shift	   = 0;
	txc->stabil	   = 0;
	txc->jitcnt	   = 0;
	txc->calcnt	   = 0;
	txc->errcnt	   = 0;
	txc->stbcnt	   = 0;
	write_sequnlock_irq(&xtime_lock);

	txc->time.tv_sec = ts.tv_sec;
	txc->time.tv_usec = ts.tv_nsec;
	if (!(time_status & STA_NANO))
		txc->time.tv_usec /= NSEC_PER_USEC;

	notify_cmos_timer();

	return result;
}

static int __init ntp_tick_adj_setup(char *str)
{
	ntp_tick_adj = simple_strtol(str, NULL, 0);
	return 1;
}

__setup("ntp_tick_adj=", ntp_tick_adj_setup);

void __init ntp_init(void)
{
	ntp_clear();
	hrtimer_init(&leap_timer, CLOCK_REALTIME, HRTIMER_MODE_ABS);
	leap_timer.function = ntp_leap_second;
}
Commit	Line	Data
4c7ee8de	1	/*
4c7ee8de	2	* NTP state machine interfaces and logic.
	3	*
	4	* This code was mainly moved from kernel/timer.c and kernel/time.c
	5	* Please see those files for relevant copyright info and historical
	6	* changelogs.
	7	*/
aa0ac365	8	#include <linux/capability.h>
7dffa3c6	9	#include <linux/clocksource.h>
eb3f938f	10	#include <linux/workqueue.h>
53bbfa9e IM	11	#include <linux/hrtimer.h>
	12	#include <linux/jiffies.h>
	13	#include <linux/math64.h>
	14	#include <linux/timex.h>
	15	#include <linux/time.h>
	16	#include <linux/mm.h>
4c7ee8de	17
b0ee7556	18	/*
53bbfa9e	19	* NTP timekeeping variables:
b0ee7556	20	*/
b0ee7556	21
53bbfa9e IM	22	/* USER_HZ period (usecs): */
	23	unsigned long tick_usec = TICK_USEC;
	24
	25	/* ACTHZ period (nsecs): */
	26	unsigned long tick_nsec;
7dffa3c6	27
53bbfa9e IM	28	u64 tick_length;
	29	static u64 tick_length_base;
	30
	31	static struct hrtimer leap_timer;
	32
bbd12676	33	#define MAX_TICKADJ 500LL /* usecs */
53bbfa9e	34	#define MAX_TICKADJ_SCALED \
bbd12676	35	(((MAX_TICKADJ * NSEC_PER_USEC) << NTP_SCALE_SHIFT) / NTP_INTERVAL_FREQ)
4c7ee8de	36
	37	/*
	38	* phase-lock loop variables
	39	*/
53bbfa9e IM	40
	41	/*
	42	* clock synchronization status
	43	*
	44	* (TIME_ERROR prevents overwriting the CMOS clock)
	45	*/
	46	static int time_state = TIME_OK;
	47
	48	/* clock status bits: */
	49	int time_status = STA_UNSYNC;
	50
	51	/* TAI offset (secs): */
	52	static long time_tai;
	53
	54	/* time adjustment (nsecs): */
	55	static s64 time_offset;
	56
	57	/* pll time constant: */
	58	static long time_constant = 2;
	59
	60	/* maximum error (usecs): */
	61	long time_maxerror = NTP_PHASE_LIMIT;
	62
	63	/* estimated error (usecs): */
	64	long time_esterror = NTP_PHASE_LIMIT;
	65
	66	/* frequency offset (scaled nsecs/secs): */
	67	static s64 time_freq;
	68
	69	/* time at last adjustment (secs): */
	70	static long time_reftime;
	71
	72	long time_adjust;
	73
	74	static long ntp_tick_adj;
	75
	76	/*
	77	* NTP methods:
	78	*/
4c7ee8de	79
9ce616aa IM	80	/*
	81	* Update (tick_length, tick_length_base, tick_nsec), based
	82	* on (tick_usec, ntp_tick_adj, time_freq):
	83	*/
70bc42f9 AB	84	static void ntp_update_frequency(void)
70bc42f9 AB	85	{
9ce616aa	86	u64 second_length;
bc26c31d	87	u64 new_base;
9ce616aa IM	88
	89	second_length = (u64)(tick_usec * NSEC_PER_USEC * USER_HZ)
	90	<< NTP_SCALE_SHIFT;
	91
	92	second_length += (s64)ntp_tick_adj << NTP_SCALE_SHIFT;
	93	second_length += time_freq;
70bc42f9	94
9ce616aa	95	tick_nsec = div_u64(second_length, HZ) >> NTP_SCALE_SHIFT;
bc26c31d	96	new_base = div_u64(second_length, NTP_INTERVAL_FREQ);
fdcedf7b	97
	98	/*
	99	* Don't wait for the next second_overflow, apply
bc26c31d	100	* the change to the tick length immediately:
fdcedf7b	101	*/
bc26c31d IM	102	tick_length += new_base - tick_length_base;
bc26c31d IM	103	tick_length_base = new_base;
70bc42f9 AB	104	}
70bc42f9 AB	105
f939890b IM	106	static inline s64 ntp_update_offset_fll(s64 freq_adj, s64 offset64, long secs)
	107	{
	108	time_status &= ~STA_MODE;
	109
	110	if (secs < MINSEC)
	111	return freq_adj;
	112
	113	if (!(time_status & STA_FLL) && (secs <= MAXSEC))
	114	return freq_adj;
	115
	116	freq_adj += div_s64(offset64 << (NTP_SCALE_SHIFT - SHIFT_FLL), secs);
	117	time_status \|= STA_MODE;
	118
	119	return freq_adj;
	120	}
	121
ee9851b2 RZ	122	static void ntp_update_offset(long offset)
ee9851b2 RZ	123	{
ee9851b2	124	s64 freq_adj;
f939890b IM	125	s64 offset64;
f939890b IM	126	long secs;
ee9851b2 RZ	127
	128	if (!(time_status & STA_PLL))
	129	return;
	130
eea83d89	131	if (!(time_status & STA_NANO))
9f14f669	132	offset *= NSEC_PER_USEC;
ee9851b2 RZ	133
	134	/*
	135	* Scale the phase adjustment and
	136	* clamp to the operating range.
	137	*/
9f14f669 RZ	138	offset = min(offset, MAXPHASE);
9f14f669 RZ	139	offset = max(offset, -MAXPHASE);
ee9851b2 RZ	140
	141	/*
	142	* Select how the frequency is to be controlled
	143	* and in which mode (PLL or FLL).
	144	*/
	145	if (time_status & STA_FREQHOLD \|\| time_reftime == 0)
	146	time_reftime = xtime.tv_sec;
f939890b IM	147
f939890b IM	148	secs = xtime.tv_sec - time_reftime;
ee9851b2 RZ	149	time_reftime = xtime.tv_sec;
ee9851b2 RZ	150
f939890b IM	151	offset64 = offset;
	152	freq_adj = (offset64 * secs) <<
	153	(NTP_SCALE_SHIFT - 2 * (SHIFT_PLL + 2 + time_constant));
	154
	155	freq_adj = ntp_update_offset_fll(freq_adj, offset64, secs);
	156
	157	freq_adj = min(freq_adj + time_freq, MAXFREQ_SCALED);
	158
	159	time_freq = max(freq_adj, -MAXFREQ_SCALED);
	160
	161	time_offset = div_s64(offset64 << NTP_SCALE_SHIFT, NTP_INTERVAL_FREQ);
ee9851b2 RZ	162	}
ee9851b2 RZ	163
b0ee7556 RZ	164	/**
	165	* ntp_clear - Clears the NTP state variables
	166	*
	167	* Must be called while holding a write on the xtime_lock
	168	*/
	169	void ntp_clear(void)
	170	{
53bbfa9e IM	171	time_adjust = 0; /* stop active adjtime() */
	172	time_status \|= STA_UNSYNC;
	173	time_maxerror = NTP_PHASE_LIMIT;
	174	time_esterror = NTP_PHASE_LIMIT;
b0ee7556 RZ	175
	176	ntp_update_frequency();
	177
53bbfa9e IM	178	tick_length = tick_length_base;
53bbfa9e IM	179	time_offset = 0;
b0ee7556 RZ	180	}
b0ee7556 RZ	181
4c7ee8de	182	/*
7dffa3c6 RZ	183	* Leap second processing. If in leap-insert state at the end of the
	184	* day, the system clock is set back one second; if in leap-delete
	185	* state, the system clock is set ahead one second.
4c7ee8de	186	*/
7dffa3c6	187	static enum hrtimer_restart ntp_leap_second(struct hrtimer *timer)
4c7ee8de	188	{
7dffa3c6	189	enum hrtimer_restart res = HRTIMER_NORESTART;
4c7ee8de	190
ca109491	191	write_seqlock(&xtime_lock);
4c7ee8de	192
4c7ee8de	193	switch (time_state) {
4c7ee8de	194	case TIME_OK:
4c7ee8de	195	break;
4c7ee8de	196	case TIME_INS:
7dffa3c6 RZ	197	xtime.tv_sec--;
	198	wall_to_monotonic.tv_sec++;
	199	time_state = TIME_OOP;
53bbfa9e IM	200	printk(KERN_NOTICE
53bbfa9e IM	201	"Clock: inserting leap second 23:59:60 UTC\n");
cc584b21	202	hrtimer_add_expires_ns(&leap_timer, NSEC_PER_SEC);
7dffa3c6	203	res = HRTIMER_RESTART;
4c7ee8de	204	break;
4c7ee8de	205	case TIME_DEL:
7dffa3c6 RZ	206	xtime.tv_sec++;
	207	time_tai--;
	208	wall_to_monotonic.tv_sec--;
	209	time_state = TIME_WAIT;
53bbfa9e IM	210	printk(KERN_NOTICE
53bbfa9e IM	211	"Clock: deleting leap second 23:59:59 UTC\n");
4c7ee8de	212	break;
4c7ee8de	213	case TIME_OOP:
153b5d05	214	time_tai++;
4c7ee8de	215	time_state = TIME_WAIT;
7dffa3c6	216	/* fall through */
4c7ee8de	217	case TIME_WAIT:
4c7ee8de	218	if (!(time_status & (STA_INS \| STA_DEL)))
ee9851b2	219	time_state = TIME_OK;
7dffa3c6 RZ	220	break;
	221	}
	222	update_vsyscall(&xtime, clock);
	223
ca109491	224	write_sequnlock(&xtime_lock);
7dffa3c6 RZ	225
	226	return res;
	227	}
	228
	229	/*
	230	* this routine handles the overflow of the microsecond field
	231	*
	232	* The tricky bits of code to handle the accurate clock support
	233	* were provided by Dave Mills (Mills@UDEL.EDU) of NTP fame.
	234	* They were originally developed for SUN and DEC kernels.
	235	* All the kudos should go to Dave for this stuff.
	236	*/
	237	void second_overflow(void)
	238	{
	239	s64 time_adj;
	240
	241	/* Bump the maxerror field */
	242	time_maxerror += MAXFREQ / NSEC_PER_USEC;
	243	if (time_maxerror > NTP_PHASE_LIMIT) {
	244	time_maxerror = NTP_PHASE_LIMIT;
	245	time_status \|= STA_UNSYNC;
4c7ee8de	246	}
	247
	248	/*
f1992393 RZ	249	* Compute the phase adjustment for the next second. The offset is
f1992393 RZ	250	* reduced by a fixed factor times the time constant.
4c7ee8de	251	*/
53bbfa9e IM	252	tick_length = tick_length_base;
	253	time_adj = shift_right(time_offset, SHIFT_PLL + time_constant);
	254	time_offset -= time_adj;
	255	tick_length += time_adj;
4c7ee8de	256
3c972c24 IM	257	if (!time_adjust)
	258	return;
	259
	260	if (time_adjust > MAX_TICKADJ) {
	261	time_adjust -= MAX_TICKADJ;
	262	tick_length += MAX_TICKADJ_SCALED;
	263	return;
4c7ee8de	264	}
3c972c24 IM	265
	266	if (time_adjust < -MAX_TICKADJ) {
	267	time_adjust += MAX_TICKADJ;
	268	tick_length -= MAX_TICKADJ_SCALED;
	269	return;
	270	}
	271
	272	tick_length += (s64)(time_adjust * NSEC_PER_USEC / NTP_INTERVAL_FREQ)
	273	<< NTP_SCALE_SHIFT;
	274	time_adjust = 0;
4c7ee8de	275	}
4c7ee8de	276
82644459	277	#ifdef CONFIG_GENERIC_CMOS_UPDATE
4c7ee8de	278
82644459 TG	279	/* Disable the cmos update - used by virtualization and embedded */
	280	int no_sync_cmos_clock __read_mostly;
	281
eb3f938f	282	static void sync_cmos_clock(struct work_struct *work);
82644459	283
eb3f938f	284	static DECLARE_DELAYED_WORK(sync_cmos_work, sync_cmos_clock);
82644459	285
eb3f938f	286	static void sync_cmos_clock(struct work_struct *work)
82644459 TG	287	{
	288	struct timespec now, next;
	289	int fail = 1;
	290
	291	/*
	292	* If we have an externally synchronized Linux clock, then update
	293	* CMOS clock accordingly every ~11 minutes. Set_rtc_mmss() has to be
	294	* called as close as possible to 500 ms before the new second starts.
	295	* This code is run on a timer. If the clock is set, that timer
	296	* may not expire at the correct time. Thus, we adjust...
	297	*/
53bbfa9e	298	if (!ntp_synced()) {
82644459 TG	299	/*
	300	* Not synced, exit, do not restart a timer (if one is
	301	* running, let it run out).
	302	*/
	303	return;
53bbfa9e	304	}
82644459 TG	305
82644459 TG	306	getnstimeofday(&now);
fa6a1a55	307	if (abs(now.tv_nsec - (NSEC_PER_SEC / 2)) <= tick_nsec / 2)
82644459 TG	308	fail = update_persistent_clock(now);
82644459 TG	309
4ff4b9e1	310	next.tv_nsec = (NSEC_PER_SEC / 2) - now.tv_nsec - (TICK_NSEC / 2);
82644459 TG	311	if (next.tv_nsec <= 0)
	312	next.tv_nsec += NSEC_PER_SEC;
	313
	314	if (!fail)
	315	next.tv_sec = 659;
	316	else
	317	next.tv_sec = 0;
	318
	319	if (next.tv_nsec >= NSEC_PER_SEC) {
	320	next.tv_sec++;
	321	next.tv_nsec -= NSEC_PER_SEC;
	322	}
eb3f938f	323	schedule_delayed_work(&sync_cmos_work, timespec_to_jiffies(&next));
82644459 TG	324	}
	325
	326	static void notify_cmos_timer(void)
4c7ee8de	327	{
298a5df4	328	if (!no_sync_cmos_clock)
eb3f938f	329	schedule_delayed_work(&sync_cmos_work, 0);
4c7ee8de	330	}
4c7ee8de	331
82644459 TG	332	#else
	333	static inline void notify_cmos_timer(void) { }
	334	#endif
	335
53bbfa9e IM	336	/*
53bbfa9e IM	337	* adjtimex mainly allows reading (and writing, if superuser) of
4c7ee8de	338	* kernel time-keeping variables. used by xntpd.
	339	*/
	340	int do_adjtimex(struct timex *txc)
	341	{
eea83d89	342	struct timespec ts;
4c7ee8de	343	int result;
4c7ee8de	344
916c7a85 RZ	345	/* Validate the data before disabling interrupts */
916c7a85 RZ	346	if (txc->modes & ADJ_ADJTIME) {
eea83d89	347	/* singleshot must not be used with any other mode bits */
916c7a85	348	if (!(txc->modes & ADJ_OFFSET_SINGLESHOT))
4c7ee8de	349	return -EINVAL;
916c7a85 RZ	350	if (!(txc->modes & ADJ_OFFSET_READONLY) &&
	351	!capable(CAP_SYS_TIME))
	352	return -EPERM;
	353	} else {
	354	/* In order to modify anything, you gotta be super-user! */
	355	if (txc->modes && !capable(CAP_SYS_TIME))
	356	return -EPERM;
	357
53bbfa9e IM	358	/*
	359	* if the quartz is off by more than 10% then
	360	* something is VERY wrong!
	361	*/
916c7a85 RZ	362	if (txc->modes & ADJ_TICK &&
	363	(txc->tick < 900000/USER_HZ \|\|
	364	txc->tick > 1100000/USER_HZ))
	365	return -EINVAL;
	366
	367	if (txc->modes & ADJ_STATUS && time_state != TIME_OK)
	368	hrtimer_cancel(&leap_timer);
52bfb360	369	}
4c7ee8de	370
7dffa3c6 RZ	371	getnstimeofday(&ts);
7dffa3c6 RZ	372
4c7ee8de	373	write_seqlock_irq(&xtime_lock);
4c7ee8de	374
4c7ee8de	375	/* If there are input parameters, then process them */
916c7a85 RZ	376	if (txc->modes & ADJ_ADJTIME) {
	377	long save_adjust = time_adjust;
	378
	379	if (!(txc->modes & ADJ_OFFSET_READONLY)) {
	380	/* adjtime() is independent from ntp_adjtime() */
	381	time_adjust = txc->offset;
	382	ntp_update_frequency();
	383	}
	384	txc->offset = save_adjust;
	385	goto adj_done;
	386	}
ee9851b2	387	if (txc->modes) {
916c7a85 RZ	388	long sec;
916c7a85 RZ	389
eea83d89 RZ	390	if (txc->modes & ADJ_STATUS) {
	391	if ((time_status & STA_PLL) &&
	392	!(txc->status & STA_PLL)) {
	393	time_state = TIME_OK;
	394	time_status = STA_UNSYNC;
	395	}
	396	/* only set allowed bits */
	397	time_status &= STA_RONLY;
	398	time_status \|= txc->status & ~STA_RONLY;
7dffa3c6 RZ	399
	400	switch (time_state) {
	401	case TIME_OK:
	402	start_timer:
	403	sec = ts.tv_sec;
	404	if (time_status & STA_INS) {
	405	time_state = TIME_INS;
	406	sec += 86400 - sec % 86400;
	407	hrtimer_start(&leap_timer, ktime_set(sec, 0), HRTIMER_MODE_ABS);
	408	} else if (time_status & STA_DEL) {
	409	time_state = TIME_DEL;
	410	sec += 86400 - (sec + 1) % 86400;
	411	hrtimer_start(&leap_timer, ktime_set(sec, 0), HRTIMER_MODE_ABS);
	412	}
	413	break;
	414	case TIME_INS:
	415	case TIME_DEL:
	416	time_state = TIME_OK;
	417	goto start_timer;
	418	break;
	419	case TIME_WAIT:
	420	if (!(time_status & (STA_INS \| STA_DEL)))
	421	time_state = TIME_OK;
	422	break;
	423	case TIME_OOP:
	424	hrtimer_restart(&leap_timer);
	425	break;
	426	}
eea83d89 RZ	427	}
	428
	429	if (txc->modes & ADJ_NANO)
	430	time_status \|= STA_NANO;
	431	if (txc->modes & ADJ_MICRO)
	432	time_status &= ~STA_NANO;
ee9851b2 RZ	433
ee9851b2 RZ	434	if (txc->modes & ADJ_FREQUENCY) {
074b3b87 RZ	435	time_freq = (s64)txc->freq * PPM_SCALE;
	436	time_freq = min(time_freq, MAXFREQ_SCALED);
	437	time_freq = max(time_freq, -MAXFREQ_SCALED);
4c7ee8de	438	}
ee9851b2	439
eea83d89	440	if (txc->modes & ADJ_MAXERROR)
ee9851b2	441	time_maxerror = txc->maxerror;
eea83d89	442	if (txc->modes & ADJ_ESTERROR)
ee9851b2	443	time_esterror = txc->esterror;
4c7ee8de	444
ee9851b2	445	if (txc->modes & ADJ_TIMECONST) {
eea83d89 RZ	446	time_constant = txc->constant;
	447	if (!(time_status & STA_NANO))
	448	time_constant += 4;
	449	time_constant = min(time_constant, (long)MAXTC);
	450	time_constant = max(time_constant, 0l);
4c7ee8de	451	}
4c7ee8de	452
153b5d05 RZ	453	if (txc->modes & ADJ_TAI && txc->constant > 0)
	454	time_tai = txc->constant;
	455
916c7a85 RZ	456	if (txc->modes & ADJ_OFFSET)
916c7a85 RZ	457	ntp_update_offset(txc->offset);
ee9851b2 RZ	458	if (txc->modes & ADJ_TICK)
	459	tick_usec = txc->tick;
	460
	461	if (txc->modes & (ADJ_TICK\|ADJ_FREQUENCY\|ADJ_OFFSET))
	462	ntp_update_frequency();
	463	}
eea83d89	464
916c7a85 RZ	465	txc->offset = shift_right(time_offset * NTP_INTERVAL_FREQ,
	466	NTP_SCALE_SHIFT);
	467	if (!(time_status & STA_NANO))
	468	txc->offset /= NSEC_PER_USEC;
	469
	470	adj_done:
eea83d89	471	result = time_state; /* mostly `TIME_OK' */
ee9851b2	472	if (time_status & (STA_UNSYNC\|STA_CLOCKERR))
4c7ee8de	473	result = TIME_ERROR;
4c7ee8de	474
d40e944c RZ	475	txc->freq = shift_right((time_freq >> PPM_SCALE_INV_SHIFT) *
d40e944c RZ	476	(s64)PPM_SCALE_INV, NTP_SCALE_SHIFT);
4c7ee8de	477	txc->maxerror = time_maxerror;
	478	txc->esterror = time_esterror;
	479	txc->status = time_status;
	480	txc->constant = time_constant;
70bc42f9	481	txc->precision = 1;
074b3b87	482	txc->tolerance = MAXFREQ_SCALED / PPM_SCALE;
4c7ee8de	483	txc->tick = tick_usec;
153b5d05	484	txc->tai = time_tai;
4c7ee8de	485
	486	/* PPS is not implemented, so these are zero */
	487	txc->ppsfreq = 0;
	488	txc->jitter = 0;
	489	txc->shift = 0;
	490	txc->stabil = 0;
	491	txc->jitcnt = 0;
	492	txc->calcnt = 0;
	493	txc->errcnt = 0;
	494	txc->stbcnt = 0;
	495	write_sequnlock_irq(&xtime_lock);
ee9851b2	496
eea83d89 RZ	497	txc->time.tv_sec = ts.tv_sec;
	498	txc->time.tv_usec = ts.tv_nsec;
	499	if (!(time_status & STA_NANO))
	500	txc->time.tv_usec /= NSEC_PER_USEC;
ee9851b2	501
82644459	502	notify_cmos_timer();
ee9851b2 RZ	503
ee9851b2 RZ	504	return result;
4c7ee8de	505	}
10a398d0 RZ	506
	507	static int __init ntp_tick_adj_setup(char *str)
	508	{
	509	ntp_tick_adj = simple_strtol(str, NULL, 0);
	510	return 1;
	511	}
	512
	513	__setup("ntp_tick_adj=", ntp_tick_adj_setup);
7dffa3c6 RZ	514
	515	void __init ntp_init(void)
	516	{
	517	ntp_clear();
	518	hrtimer_init(&leap_timer, CLOCK_REALTIME, HRTIMER_MODE_ABS);
	519	leap_timer.function = ntp_leap_second;
	520	}