[mirror_ubuntu-jammy-kernel.git] / kernel / time / ntp.c

/*
 * linux/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/mm.h>
#include <linux/time.h>
#include <linux/timex.h>
#include <linux/jiffies.h>
#include <linux/hrtimer.h>
#include <linux/capability.h>
#include <linux/math64.h>
#include <linux/clocksource.h>
#include <linux/workqueue.h>
#include <asm/timex.h>

/*
 * Timekeeping variables
 */
unsigned long tick_usec = TICK_USEC; 		/* USER_HZ period (usec) */
unsigned long tick_nsec;			/* ACTHZ period (nsec) */
u64 tick_length;
static u64 tick_length_base;

static struct hrtimer leap_timer;

#define MAX_TICKADJ		500		/* microsecs */
#define MAX_TICKADJ_SCALED	(((u64)(MAX_TICKADJ * NSEC_PER_USEC) << \
				  NTP_SCALE_SHIFT) / NTP_INTERVAL_FREQ)

/*
 * phase-lock loop variables
 */
/* TIME_ERROR prevents overwriting the CMOS clock */
static int time_state = TIME_OK;	/* clock synchronization status	*/
int time_status = STA_UNSYNC;		/* clock status bits		*/
static long time_tai;			/* TAI offset (s)		*/
static s64 time_offset;			/* time adjustment (ns)		*/
static long time_constant = 2;		/* pll time constant		*/
long time_maxerror = NTP_PHASE_LIMIT;	/* maximum error (us)		*/
long time_esterror = NTP_PHASE_LIMIT;	/* estimated error (us)		*/
static s64 time_freq;			/* frequency offset (scaled ns/s)*/
static long time_reftime;		/* time at last adjustment (s)	*/
long time_adjust;
static long ntp_tick_adj;

static void ntp_update_frequency(void)
{
	u64 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_length_base = second_length;

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

static void ntp_update_offset(long offset)
{
	long mtemp;
	s64 freq_adj;

	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;
	mtemp = xtime.tv_sec - time_reftime;
	time_reftime = xtime.tv_sec;

	freq_adj = (s64)offset * mtemp;
	freq_adj <<= NTP_SCALE_SHIFT - 2 * (SHIFT_PLL + 2 + time_constant);
	time_status &= ~STA_MODE;
	if (mtemp >= MINSEC && (time_status & STA_FLL || mtemp > MAXSEC)) {
		freq_adj += div_s64((s64)offset << (NTP_SCALE_SHIFT - SHIFT_FLL),
				    mtemp);
		time_status |= STA_MODE;
	}
	freq_adj += time_freq;
	freq_adj = min(freq_adj, MAXFREQ_SCALED);
	time_freq = max(freq_adj, -MAXFREQ_SCALED);

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