[mirror_ubuntu-zesty-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/timer.h>
#include <linux/timex.h>
#include <linux/jiffies.h>
#include <linux/hrtimer.h>
#include <linux/capability.h>
#include <linux/math64.h>
#include <asm/timex.h>

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

#define MAX_TICKADJ		500		/* microsecs */
#define MAX_TICKADJ_SCALED	(((u64)(MAX_TICKADJ * NSEC_PER_USEC) << \
				  TICK_LENGTH_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 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)		*/
long time_freq;				/* frequency offset (scaled ppm)*/
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)
				<< TICK_LENGTH_SHIFT;
	second_length += (s64)ntp_tick_adj << TICK_LENGTH_SHIFT;
	second_length += (s64)time_freq << (TICK_LENGTH_SHIFT - SHIFT_NSEC);

	tick_length_base = second_length;

	tick_nsec = div_u64(second_length, HZ) >> TICK_LENGTH_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;

	time_offset = offset * NSEC_PER_USEC;

	/*
	 * Scale the phase adjustment and
	 * clamp to the operating range.
	 */
	time_offset = min(time_offset, (s64)MAXPHASE * NSEC_PER_USEC);
	time_offset = max(time_offset, (s64)-MAXPHASE * NSEC_PER_USEC);

	/*
	 * 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 = time_offset * mtemp;
	freq_adj = shift_right(freq_adj, time_constant * 2 +
			   (SHIFT_PLL + 2) * 2 - SHIFT_NSEC);
	if (mtemp >= MINSEC && (time_status & STA_FLL || mtemp > MAXSEC))
		freq_adj += div_s64(time_offset << (SHIFT_NSEC - SHIFT_FLL), mtemp);
	freq_adj += time_freq;
	freq_adj = min(freq_adj, (s64)MAXFREQ_NSEC);
	time_freq = max(freq_adj, (s64)-MAXFREQ_NSEC);
	time_offset = div_s64(time_offset, NTP_INTERVAL_FREQ);
	time_offset <<= SHIFT_UPDATE;
}

/**
 * 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;
}

/*
 * 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)
{
	long time_adj;

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

	/*
	 * 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. The microtime()
	 * routine or external clock driver will insure that reported time is
	 * always monotonic. The ugly divides should be replaced.
	 */
	switch (time_state) {
	case TIME_OK:
		if (time_status & STA_INS)
			time_state = TIME_INS;
		else if (time_status & STA_DEL)
			time_state = TIME_DEL;
		break;
	case TIME_INS:
		if (xtime.tv_sec % 86400 == 0) {
			xtime.tv_sec--;
			wall_to_monotonic.tv_sec++;
			time_state = TIME_OOP;
			printk(KERN_NOTICE "Clock: inserting leap second "
					"23:59:60 UTC\n");
		}
		break;
	case TIME_DEL:
		if ((xtime.tv_sec + 1) % 86400 == 0) {
			xtime.tv_sec++;
			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_state = TIME_WAIT;
		break;
	case TIME_WAIT:
		if (!(time_status & (STA_INS | STA_DEL)))
			time_state = TIME_OK;
	}

	/*
	 * 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 += (s64)time_adj << (TICK_LENGTH_SHIFT - SHIFT_UPDATE);

	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) << TICK_LENGTH_SHIFT;
			time_adjust = 0;
		}
	}
}

/*
 * Return how long ticks are at the moment, that is, how much time
 * update_wall_time_one_tick will add to xtime next time we call it
 * (assuming no calls to do_adjtimex in the meantime).
 * The return value is in fixed-point nanoseconds shifted by the
 * specified number of bits to the right of the binary point.
 * This function has no side-effects.
 */
u64 current_tick_length(void)
{
	return tick_length;
}

#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(unsigned long dummy);

static DEFINE_TIMER(sync_cmos_timer, sync_cmos_clock, 0, 0);

static void sync_cmos_clock(unsigned long dummy)
{
	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;
	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;
	}
	mod_timer(&sync_cmos_timer, jiffies + timespec_to_jiffies(&next));
}

static void notify_cmos_timer(void)
{
	if (!no_sync_cmos_clock)
		mod_timer(&sync_cmos_timer, jiffies + 1);
}

#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)
{
	long save_adjust;
	int result;

	/* In order to modify anything, you gotta be super-user! */
	if (txc->modes && !capable(CAP_SYS_TIME))
		return -EPERM;

	/* Now we validate the data before disabling interrupts */

	if ((txc->modes & ADJ_OFFSET_SINGLESHOT) == ADJ_OFFSET_SINGLESHOT) {
	  /* singleshot must not be used with any other mode bits */
		if (txc->modes != ADJ_OFFSET_SINGLESHOT &&
					txc->modes != ADJ_OFFSET_SS_READ)
			return -EINVAL;
	}

	if (txc->modes != ADJ_OFFSET_SINGLESHOT && (txc->modes & ADJ_OFFSET))
	  /* adjustment Offset limited to +- .512 seconds */
		if (txc->offset <= - MAXPHASE || txc->offset >= MAXPHASE )
			return -EINVAL;

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

	write_seqlock_irq(&xtime_lock);
	result = time_state;	/* mostly `TIME_OK' */

	/* Save for later - semantics of adjtime is to return old value */
	save_adjust = time_adjust;

#if 0	/* STA_CLOCKERR is never set yet */
	time_status &= ~STA_CLOCKERR;		/* reset STA_CLOCKERR */
#endif
	/* If there are input parameters, then process them */
	if (txc->modes) {
		if (txc->modes & ADJ_STATUS)	/* only set allowed bits */
			time_status = (txc->status & ~STA_RONLY) |
				      (time_status & STA_RONLY);

		if (txc->modes & ADJ_FREQUENCY) {
			if (txc->freq > MAXFREQ || txc->freq < -MAXFREQ) {
				result = -EINVAL;
				goto leave;
			}
			time_freq = ((s64)txc->freq * NSEC_PER_USEC)
					>> (SHIFT_USEC - SHIFT_NSEC);
		}

		if (txc->modes & ADJ_MAXERROR) {
			if (txc->maxerror < 0 || txc->maxerror >= NTP_PHASE_LIMIT) {
				result = -EINVAL;
				goto leave;
			}
			time_maxerror = txc->maxerror;
		}

		if (txc->modes & ADJ_ESTERROR) {
			if (txc->esterror < 0 || txc->esterror >= NTP_PHASE_LIMIT) {
				result = -EINVAL;
				goto leave;
			}
			time_esterror = txc->esterror;
		}

		if (txc->modes & ADJ_TIMECONST) {
			if (txc->constant < 0) {	/* NTP v4 uses values > 6 */
				result = -EINVAL;
				goto leave;
			}
			time_constant = min(txc->constant + 4, (long)MAXTC);
		}

		if (txc->modes & ADJ_OFFSET) {
			if (txc->modes == ADJ_OFFSET_SINGLESHOT)
				/* adjtime() is independent from ntp_adjtime() */
				time_adjust = txc->offset;
			else
				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();
	}
leave:
	if (time_status & (STA_UNSYNC|STA_CLOCKERR))
		result = TIME_ERROR;

	if ((txc->modes == ADJ_OFFSET_SINGLESHOT) ||
	    (txc->modes == ADJ_OFFSET_SS_READ))
		txc->offset = save_adjust;
	else
		txc->offset = ((long)shift_right(time_offset, SHIFT_UPDATE)) *
	    			NTP_INTERVAL_FREQ / 1000;
	txc->freq	   = (time_freq / NSEC_PER_USEC) <<
				(SHIFT_USEC - SHIFT_NSEC);
	txc->maxerror	   = time_maxerror;
	txc->esterror	   = time_esterror;
	txc->status	   = time_status;
	txc->constant	   = time_constant;
	txc->precision	   = 1;
	txc->tolerance	   = MAXFREQ;
	txc->tick	   = tick_usec;

	/* 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);

	do_gettimeofday(&txc->time);

	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);
Commit	Line	Data
4c7ee8de JS	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>
82644459	13	#include <linux/timer.h>
4c7ee8de	14	#include <linux/timex.h>
e8edc6e0 AD	15	#include <linux/jiffies.h>
e8edc6e0 AD	16	#include <linux/hrtimer.h>
aa0ac365	17	#include <linux/capability.h>
71abb3af	18	#include <linux/math64.h>
4c7ee8de JS	19	#include <asm/timex.h>
4c7ee8de JS	20
b0ee7556 RZ	21	/*
	22	* Timekeeping variables
	23	*/
	24	unsigned long tick_usec = TICK_USEC; /* USER_HZ period (usec) */
	25	unsigned long tick_nsec; /* ACTHZ period (nsec) */
	26	static u64 tick_length, tick_length_base;
	27
8f807f8d RZ	28	#define MAX_TICKADJ 500 /* microsecs */
8f807f8d RZ	29	#define MAX_TICKADJ_SCALED (((u64)(MAX_TICKADJ * NSEC_PER_USEC) << \
f4304ab2	30	TICK_LENGTH_SHIFT) / NTP_INTERVAL_FREQ)
4c7ee8de JS	31
	32	/*
	33	* phase-lock loop variables
	34	*/
	35	/* TIME_ERROR prevents overwriting the CMOS clock */
70bc42f9	36	static int time_state = TIME_OK; /* clock synchronization status */
4c7ee8de	37	int time_status = STA_UNSYNC; /* clock status bits */
ee9851b2	38	static s64 time_offset; /* time adjustment (ns) */
70bc42f9	39	static long time_constant = 2; /* pll time constant */
4c7ee8de JS	40	long time_maxerror = NTP_PHASE_LIMIT; /* maximum error (us) */
4c7ee8de JS	41	long time_esterror = NTP_PHASE_LIMIT; /* estimated error (us) */
dc6a43e4	42	long time_freq; /* frequency offset (scaled ppm)*/
70bc42f9	43	static long time_reftime; /* time at last adjustment (s) */
4c7ee8de	44	long time_adjust;
10a398d0	45	static long ntp_tick_adj;
4c7ee8de	46
70bc42f9 AB	47	static void ntp_update_frequency(void)
70bc42f9 AB	48	{
f4304ab2 JS	49	u64 second_length = (u64)(tick_usec * NSEC_PER_USEC * USER_HZ)
f4304ab2 JS	50	<< TICK_LENGTH_SHIFT;
10a398d0	51	second_length += (s64)ntp_tick_adj << TICK_LENGTH_SHIFT;
f4304ab2	52	second_length += (s64)time_freq << (TICK_LENGTH_SHIFT - SHIFT_NSEC);
70bc42f9	53
f4304ab2	54	tick_length_base = second_length;
70bc42f9	55
71abb3af RZ	56	tick_nsec = div_u64(second_length, HZ) >> TICK_LENGTH_SHIFT;
71abb3af RZ	57	tick_length_base = div_u64(tick_length_base, NTP_INTERVAL_FREQ);
70bc42f9 AB	58	}
70bc42f9 AB	59
ee9851b2 RZ	60	static void ntp_update_offset(long offset)
	61	{
	62	long mtemp;
	63	s64 freq_adj;
	64
	65	if (!(time_status & STA_PLL))
	66	return;
	67
	68	time_offset = offset * NSEC_PER_USEC;
	69
	70	/*
	71	* Scale the phase adjustment and
	72	* clamp to the operating range.
	73	*/
	74	time_offset = min(time_offset, (s64)MAXPHASE * NSEC_PER_USEC);
	75	time_offset = max(time_offset, (s64)-MAXPHASE * NSEC_PER_USEC);
	76
	77	/*
	78	* Select how the frequency is to be controlled
	79	* and in which mode (PLL or FLL).
	80	*/
	81	if (time_status & STA_FREQHOLD \|\| time_reftime == 0)
	82	time_reftime = xtime.tv_sec;
	83	mtemp = xtime.tv_sec - time_reftime;
	84	time_reftime = xtime.tv_sec;
	85
	86	freq_adj = time_offset * mtemp;
	87	freq_adj = shift_right(freq_adj, time_constant * 2 +
	88	(SHIFT_PLL + 2) * 2 - SHIFT_NSEC);
	89	if (mtemp >= MINSEC && (time_status & STA_FLL \|\| mtemp > MAXSEC))
	90	freq_adj += div_s64(time_offset << (SHIFT_NSEC - SHIFT_FLL), mtemp);
	91	freq_adj += time_freq;
	92	freq_adj = min(freq_adj, (s64)MAXFREQ_NSEC);
	93	time_freq = max(freq_adj, (s64)-MAXFREQ_NSEC);
	94	time_offset = div_s64(time_offset, NTP_INTERVAL_FREQ);
	95	time_offset <<= SHIFT_UPDATE;
	96	}
	97
b0ee7556 RZ	98	/**
	99	* ntp_clear - Clears the NTP state variables
	100	*
	101	* Must be called while holding a write on the xtime_lock
	102	*/
	103	void ntp_clear(void)
	104	{
	105	time_adjust = 0; /* stop active adjtime() */
	106	time_status \|= STA_UNSYNC;
	107	time_maxerror = NTP_PHASE_LIMIT;
	108	time_esterror = NTP_PHASE_LIMIT;
	109
	110	ntp_update_frequency();
	111
	112	tick_length = tick_length_base;
3d3675cc	113	time_offset = 0;
b0ee7556 RZ	114	}
b0ee7556 RZ	115
4c7ee8de JS	116	/*
	117	* this routine handles the overflow of the microsecond field
	118	*
	119	* The tricky bits of code to handle the accurate clock support
	120	* were provided by Dave Mills (Mills@UDEL.EDU) of NTP fame.
	121	* They were originally developed for SUN and DEC kernels.
	122	* All the kudos should go to Dave for this stuff.
	123	*/
	124	void second_overflow(void)
	125	{
3d3675cc	126	long time_adj;
4c7ee8de JS	127
4c7ee8de JS	128	/* Bump the maxerror field */
97eebe13	129	time_maxerror += MAXFREQ >> SHIFT_USEC;
4c7ee8de JS	130	if (time_maxerror > NTP_PHASE_LIMIT) {
	131	time_maxerror = NTP_PHASE_LIMIT;
	132	time_status \|= STA_UNSYNC;
	133	}
	134
	135	/*
	136	* Leap second processing. If in leap-insert state at the end of the
	137	* day, the system clock is set back one second; if in leap-delete
	138	* state, the system clock is set ahead one second. The microtime()
	139	* routine or external clock driver will insure that reported time is
	140	* always monotonic. The ugly divides should be replaced.
	141	*/
	142	switch (time_state) {
	143	case TIME_OK:
	144	if (time_status & STA_INS)
	145	time_state = TIME_INS;
	146	else if (time_status & STA_DEL)
	147	time_state = TIME_DEL;
	148	break;
	149	case TIME_INS:
	150	if (xtime.tv_sec % 86400 == 0) {
	151	xtime.tv_sec--;
	152	wall_to_monotonic.tv_sec++;
4c7ee8de	153	time_state = TIME_OOP;
4c7ee8de JS	154	printk(KERN_NOTICE "Clock: inserting leap second "
	155	"23:59:60 UTC\n");
	156	}
	157	break;
	158	case TIME_DEL:
	159	if ((xtime.tv_sec + 1) % 86400 == 0) {
	160	xtime.tv_sec++;
	161	wall_to_monotonic.tv_sec--;
4c7ee8de	162	time_state = TIME_WAIT;
4c7ee8de JS	163	printk(KERN_NOTICE "Clock: deleting leap second "
	164	"23:59:59 UTC\n");
	165	}
	166	break;
	167	case TIME_OOP:
	168	time_state = TIME_WAIT;
	169	break;
	170	case TIME_WAIT:
	171	if (!(time_status & (STA_INS \| STA_DEL)))
ee9851b2	172	time_state = TIME_OK;
4c7ee8de JS	173	}
	174
	175	/*
f1992393 RZ	176	* Compute the phase adjustment for the next second. The offset is
f1992393 RZ	177	* reduced by a fixed factor times the time constant.
4c7ee8de	178	*/
b0ee7556	179	tick_length = tick_length_base;
f1992393	180	time_adj = shift_right(time_offset, SHIFT_PLL + time_constant);
3d3675cc RZ	181	time_offset -= time_adj;
3d3675cc RZ	182	tick_length += (s64)time_adj << (TICK_LENGTH_SHIFT - SHIFT_UPDATE);
4c7ee8de	183
8f807f8d RZ	184	if (unlikely(time_adjust)) {
	185	if (time_adjust > MAX_TICKADJ) {
	186	time_adjust -= MAX_TICKADJ;
	187	tick_length += MAX_TICKADJ_SCALED;
	188	} else if (time_adjust < -MAX_TICKADJ) {
	189	time_adjust += MAX_TICKADJ;
	190	tick_length -= MAX_TICKADJ_SCALED;
	191	} else {
8f807f8d	192	tick_length += (s64)(time_adjust * NSEC_PER_USEC /
f4304ab2	193	NTP_INTERVAL_FREQ) << TICK_LENGTH_SHIFT;
bb1d8605	194	time_adjust = 0;
8f807f8d	195	}
4c7ee8de JS	196	}
	197	}
	198
	199	/*
	200	* Return how long ticks are at the moment, that is, how much time
	201	* update_wall_time_one_tick will add to xtime next time we call it
	202	* (assuming no calls to do_adjtimex in the meantime).
	203	* The return value is in fixed-point nanoseconds shifted by the
	204	* specified number of bits to the right of the binary point.
	205	* This function has no side-effects.
	206	*/
	207	u64 current_tick_length(void)
	208	{
8f807f8d	209	return tick_length;
4c7ee8de JS	210	}
4c7ee8de JS	211
82644459	212	#ifdef CONFIG_GENERIC_CMOS_UPDATE
4c7ee8de	213
82644459 TG	214	/* Disable the cmos update - used by virtualization and embedded */
	215	int no_sync_cmos_clock __read_mostly;
	216
	217	static void sync_cmos_clock(unsigned long dummy);
	218
	219	static DEFINE_TIMER(sync_cmos_timer, sync_cmos_clock, 0, 0);
	220
	221	static void sync_cmos_clock(unsigned long dummy)
	222	{
	223	struct timespec now, next;
	224	int fail = 1;
	225
	226	/*
	227	* If we have an externally synchronized Linux clock, then update
	228	* CMOS clock accordingly every ~11 minutes. Set_rtc_mmss() has to be
	229	* called as close as possible to 500 ms before the new second starts.
	230	* This code is run on a timer. If the clock is set, that timer
	231	* may not expire at the correct time. Thus, we adjust...
	232	*/
	233	if (!ntp_synced())
	234	/*
	235	* Not synced, exit, do not restart a timer (if one is
	236	* running, let it run out).
	237	*/
	238	return;
	239
	240	getnstimeofday(&now);
fa6a1a55	241	if (abs(now.tv_nsec - (NSEC_PER_SEC / 2)) <= tick_nsec / 2)
82644459 TG	242	fail = update_persistent_clock(now);
	243
	244	next.tv_nsec = (NSEC_PER_SEC / 2) - now.tv_nsec;
	245	if (next.tv_nsec <= 0)
	246	next.tv_nsec += NSEC_PER_SEC;
	247
	248	if (!fail)
	249	next.tv_sec = 659;
	250	else
	251	next.tv_sec = 0;
	252
	253	if (next.tv_nsec >= NSEC_PER_SEC) {
	254	next.tv_sec++;
	255	next.tv_nsec -= NSEC_PER_SEC;
	256	}
	257	mod_timer(&sync_cmos_timer, jiffies + timespec_to_jiffies(&next));
	258	}
	259
	260	static void notify_cmos_timer(void)
4c7ee8de	261	{
298a5df4	262	if (!no_sync_cmos_clock)
82644459	263	mod_timer(&sync_cmos_timer, jiffies + 1);
4c7ee8de JS	264	}
4c7ee8de JS	265
82644459 TG	266	#else
	267	static inline void notify_cmos_timer(void) { }
	268	#endif
	269
4c7ee8de JS	270	/* adjtimex mainly allows reading (and writing, if superuser) of
	271	* kernel time-keeping variables. used by xntpd.
	272	*/
	273	int do_adjtimex(struct timex *txc)
	274	{
ee9851b2	275	long save_adjust;
4c7ee8de JS	276	int result;
	277
	278	/* In order to modify anything, you gotta be super-user! */
	279	if (txc->modes && !capable(CAP_SYS_TIME))
	280	return -EPERM;
	281
	282	/* Now we validate the data before disabling interrupts */
	283
52bfb360	284	if ((txc->modes & ADJ_OFFSET_SINGLESHOT) == ADJ_OFFSET_SINGLESHOT) {
4c7ee8de	285	/* singleshot must not be used with any other mode bits */
52bfb360 JS	286	if (txc->modes != ADJ_OFFSET_SINGLESHOT &&
52bfb360 JS	287	txc->modes != ADJ_OFFSET_SS_READ)
4c7ee8de	288	return -EINVAL;
52bfb360	289	}
4c7ee8de JS	290
	291	if (txc->modes != ADJ_OFFSET_SINGLESHOT && (txc->modes & ADJ_OFFSET))
	292	/* adjustment Offset limited to +- .512 seconds */
	293	if (txc->offset <= - MAXPHASE \|\| txc->offset >= MAXPHASE )
	294	return -EINVAL;
	295
	296	/* if the quartz is off by more than 10% something is VERY wrong ! */
	297	if (txc->modes & ADJ_TICK)
	298	if (txc->tick < 900000/USER_HZ \|\|
	299	txc->tick > 1100000/USER_HZ)
	300	return -EINVAL;
	301
	302	write_seqlock_irq(&xtime_lock);
	303	result = time_state; /* mostly `TIME_OK' */
	304
	305	/* Save for later - semantics of adjtime is to return old value */
8f807f8d	306	save_adjust = time_adjust;
4c7ee8de JS	307
	308	#if 0 /* STA_CLOCKERR is never set yet */
	309	time_status &= ~STA_CLOCKERR; /* reset STA_CLOCKERR */
	310	#endif
	311	/* If there are input parameters, then process them */
ee9851b2 RZ	312	if (txc->modes) {
	313	if (txc->modes & ADJ_STATUS) /* only set allowed bits */
	314	time_status = (txc->status & ~STA_RONLY) \|
	315	(time_status & STA_RONLY);
	316
	317	if (txc->modes & ADJ_FREQUENCY) {
	318	if (txc->freq > MAXFREQ \|\| txc->freq < -MAXFREQ) {
	319	result = -EINVAL;
	320	goto leave;
	321	}
	322	time_freq = ((s64)txc->freq * NSEC_PER_USEC)
	323	>> (SHIFT_USEC - SHIFT_NSEC);
4c7ee8de	324	}
ee9851b2 RZ	325
	326	if (txc->modes & ADJ_MAXERROR) {
	327	if (txc->maxerror < 0 \|\| txc->maxerror >= NTP_PHASE_LIMIT) {
	328	result = -EINVAL;
	329	goto leave;
	330	}
	331	time_maxerror = txc->maxerror;
4c7ee8de	332	}
4c7ee8de	333
ee9851b2 RZ	334	if (txc->modes & ADJ_ESTERROR) {
	335	if (txc->esterror < 0 \|\| txc->esterror >= NTP_PHASE_LIMIT) {
	336	result = -EINVAL;
	337	goto leave;
	338	}
	339	time_esterror = txc->esterror;
4c7ee8de	340	}
4c7ee8de	341
ee9851b2 RZ	342	if (txc->modes & ADJ_TIMECONST) {
	343	if (txc->constant < 0) { /* NTP v4 uses values > 6 */
	344	result = -EINVAL;
	345	goto leave;
	346	}
	347	time_constant = min(txc->constant + 4, (long)MAXTC);
4c7ee8de	348	}
4c7ee8de	349
ee9851b2 RZ	350	if (txc->modes & ADJ_OFFSET) {
	351	if (txc->modes == ADJ_OFFSET_SINGLESHOT)
	352	/* adjtime() is independent from ntp_adjtime() */
	353	time_adjust = txc->offset;
	354	else
	355	ntp_update_offset(txc->offset);
4c7ee8de	356	}
ee9851b2 RZ	357	if (txc->modes & ADJ_TICK)
	358	tick_usec = txc->tick;
	359
	360	if (txc->modes & (ADJ_TICK\|ADJ_FREQUENCY\|ADJ_OFFSET))
	361	ntp_update_frequency();
	362	}
	363	leave:
	364	if (time_status & (STA_UNSYNC\|STA_CLOCKERR))
4c7ee8de JS	365	result = TIME_ERROR;
4c7ee8de JS	366
52bfb360	367	if ((txc->modes == ADJ_OFFSET_SINGLESHOT) \|\|
ee9851b2	368	(txc->modes == ADJ_OFFSET_SS_READ))
d62ac21a	369	txc->offset = save_adjust;
3d3675cc	370	else
d62ac21a JS	371	txc->offset = ((long)shift_right(time_offset, SHIFT_UPDATE)) *
	372	NTP_INTERVAL_FREQ / 1000;
	373	txc->freq = (time_freq / NSEC_PER_USEC) <<
	374	(SHIFT_USEC - SHIFT_NSEC);
4c7ee8de JS	375	txc->maxerror = time_maxerror;
	376	txc->esterror = time_esterror;
	377	txc->status = time_status;
	378	txc->constant = time_constant;
70bc42f9	379	txc->precision = 1;
97eebe13	380	txc->tolerance = MAXFREQ;
4c7ee8de JS	381	txc->tick = tick_usec;
	382
	383	/* PPS is not implemented, so these are zero */
	384	txc->ppsfreq = 0;
	385	txc->jitter = 0;
	386	txc->shift = 0;
	387	txc->stabil = 0;
	388	txc->jitcnt = 0;
	389	txc->calcnt = 0;
	390	txc->errcnt = 0;
	391	txc->stbcnt = 0;
	392	write_sequnlock_irq(&xtime_lock);
ee9851b2	393
4c7ee8de	394	do_gettimeofday(&txc->time);
ee9851b2	395
82644459	396	notify_cmos_timer();
ee9851b2 RZ	397
ee9851b2 RZ	398	return result;
4c7ee8de	399	}
10a398d0 RZ	400
	401	static int __init ntp_tick_adj_setup(char *str)
	402	{
	403	ntp_tick_adj = simple_strtol(str, NULL, 0);
	404	return 1;
	405	}
	406
	407	__setup("ntp_tick_adj=", ntp_tick_adj_setup);