[deliverable/linux.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 <asm/div64.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;

#define CLOCK_TICK_OVERFLOW	(LATCH * HZ - CLOCK_TICK_RATE)
#define CLOCK_TICK_ADJUST	(((s64)CLOCK_TICK_OVERFLOW * NSEC_PER_SEC) / \
					(s64)CLOCK_TICK_RATE)

static void ntp_update_frequency(void)
{
	u64 second_length = (u64)(tick_usec * NSEC_PER_USEC * USER_HZ)
				<< TICK_LENGTH_SHIFT;
	second_length += (s64)CLOCK_TICK_ADJUST << TICK_LENGTH_SHIFT;
	second_length += (s64)time_freq << (TICK_LENGTH_SHIFT - SHIFT_NSEC);

	tick_length_base = second_length;

	do_div(second_length, HZ);
	tick_nsec = second_length >> TICK_LENGTH_SHIFT;

	do_div(tick_length_base, 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;
}

/*
 * 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;
}


void __attribute__ ((weak)) notify_arch_cmos_timer(void)
{
	return;
}

/* adjtimex mainly allows reading (and writing, if superuser) of
 * kernel time-keeping variables. used by xntpd.
 */
int do_adjtimex(struct timex *txc)
{
	long mtemp, save_adjust, rem;
	s64 freq_adj, temp64;
	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)
			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) {	/* p. 22 */
		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) {	/* p. 24 */
		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) {	/* values checked earlier */
		if (txc->modes == ADJ_OFFSET_SINGLESHOT) {
		    /* adjtime() is independent from ntp_adjtime() */
		    time_adjust = txc->offset;
		}
		else if (time_status & STA_PLL) {
		    time_offset = txc->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 whether the frequency is to be controlled
		     * and in which mode (PLL or FLL). Clamp to the operating
		     * range. Ugly multiply/divide should be replaced someday.
		     */

		    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)) {
			temp64 = time_offset << (SHIFT_NSEC - SHIFT_FLL);
			if (time_offset < 0) {
			    temp64 = -temp64;
			    do_div(temp64, mtemp);
			    freq_adj -= temp64;
			} else {
			    do_div(temp64, mtemp);
			    freq_adj += temp64;
			}
		    }
		    freq_adj += time_freq;
		    freq_adj = min(freq_adj, (s64)MAXFREQ_NSEC);
		    time_freq = max(freq_adj, (s64)-MAXFREQ_NSEC);
		    time_offset = div_long_long_rem_signed(time_offset,
							   NTP_INTERVAL_FREQ,
							   &rem);
		    time_offset <<= SHIFT_UPDATE;
		} /* STA_PLL */
	    } /* txc->modes & ADJ_OFFSET */
	    if (txc->modes & ADJ_TICK)
		tick_usec = txc->tick;

	    if (txc->modes & (ADJ_TICK|ADJ_FREQUENCY|ADJ_OFFSET))
		    ntp_update_frequency();
	} /* txc->modes */
leave:	if ((time_status & (STA_UNSYNC|STA_CLOCKERR)) != 0)
		result = TIME_ERROR;

	if ((txc->modes & ADJ_OFFSET_SINGLESHOT) == ADJ_OFFSET_SINGLESHOT)
		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_arch_cmos_timer();
	return(result);
}
Commit	Line	Data
4c7ee8de	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>
e8edc6e0 AD	14	#include <linux/jiffies.h>
e8edc6e0 AD	15	#include <linux/hrtimer.h>
aa0ac365	16	#include <linux/capability.h>
4c7ee8de	17	#include <asm/div64.h>
	18	#include <asm/timex.h>
	19
b0ee7556 RZ	20	/*
	21	* Timekeeping variables
	22	*/
	23	unsigned long tick_usec = TICK_USEC; /* USER_HZ period (usec) */
	24	unsigned long tick_nsec; /* ACTHZ period (nsec) */
	25	static u64 tick_length, tick_length_base;
	26
8f807f8d RZ	27	#define MAX_TICKADJ 500 /* microsecs */
8f807f8d RZ	28	#define MAX_TICKADJ_SCALED (((u64)(MAX_TICKADJ * NSEC_PER_USEC) << \
f4304ab2	29	TICK_LENGTH_SHIFT) / NTP_INTERVAL_FREQ)
4c7ee8de	30
	31	/*
	32	* phase-lock loop variables
	33	*/
	34	/* TIME_ERROR prevents overwriting the CMOS clock */
70bc42f9	35	static int time_state = TIME_OK; /* clock synchronization status */
4c7ee8de	36	int time_status = STA_UNSYNC; /* clock status bits */
d62ac21a	37	static s64 time_offset; /* time adjustment (ns) */
70bc42f9	38	static long time_constant = 2; /* pll time constant */
4c7ee8de	39	long time_maxerror = NTP_PHASE_LIMIT; /* maximum error (us) */
4c7ee8de	40	long time_esterror = NTP_PHASE_LIMIT; /* estimated error (us) */
dc6a43e4	41	long time_freq; /* frequency offset (scaled ppm)*/
70bc42f9	42	static long time_reftime; /* time at last adjustment (s) */
4c7ee8de	43	long time_adjust;
4c7ee8de	44
70bc42f9 AB	45	#define CLOCK_TICK_OVERFLOW (LATCH * HZ - CLOCK_TICK_RATE)
	46	#define CLOCK_TICK_ADJUST (((s64)CLOCK_TICK_OVERFLOW * NSEC_PER_SEC) / \
	47	(s64)CLOCK_TICK_RATE)
	48
	49	static void ntp_update_frequency(void)
	50	{
f4304ab2	51	u64 second_length = (u64)(tick_usec * NSEC_PER_USEC * USER_HZ)
	52	<< TICK_LENGTH_SHIFT;
	53	second_length += (s64)CLOCK_TICK_ADJUST << TICK_LENGTH_SHIFT;
	54	second_length += (s64)time_freq << (TICK_LENGTH_SHIFT - SHIFT_NSEC);
70bc42f9	55
f4304ab2	56	tick_length_base = second_length;
70bc42f9	57
f4304ab2	58	do_div(second_length, HZ);
	59	tick_nsec = second_length >> TICK_LENGTH_SHIFT;
	60
	61	do_div(tick_length_base, NTP_INTERVAL_FREQ);
70bc42f9 AB	62	}
70bc42f9 AB	63
b0ee7556 RZ	64	/**
	65	* ntp_clear - Clears the NTP state variables
	66	*
	67	* Must be called while holding a write on the xtime_lock
	68	*/
	69	void ntp_clear(void)
	70	{
	71	time_adjust = 0; /* stop active adjtime() */
	72	time_status \|= STA_UNSYNC;
	73	time_maxerror = NTP_PHASE_LIMIT;
	74	time_esterror = NTP_PHASE_LIMIT;
	75
	76	ntp_update_frequency();
	77
	78	tick_length = tick_length_base;
3d3675cc	79	time_offset = 0;
b0ee7556 RZ	80	}
b0ee7556 RZ	81
4c7ee8de	82	/*
	83	* this routine handles the overflow of the microsecond field
	84	*
	85	* The tricky bits of code to handle the accurate clock support
	86	* were provided by Dave Mills (Mills@UDEL.EDU) of NTP fame.
	87	* They were originally developed for SUN and DEC kernels.
	88	* All the kudos should go to Dave for this stuff.
	89	*/
	90	void second_overflow(void)
	91	{
3d3675cc	92	long time_adj;
4c7ee8de	93
4c7ee8de	94	/* Bump the maxerror field */
97eebe13	95	time_maxerror += MAXFREQ >> SHIFT_USEC;
4c7ee8de	96	if (time_maxerror > NTP_PHASE_LIMIT) {
	97	time_maxerror = NTP_PHASE_LIMIT;
	98	time_status \|= STA_UNSYNC;
	99	}
	100
	101	/*
	102	* Leap second processing. If in leap-insert state at the end of the
	103	* day, the system clock is set back one second; if in leap-delete
	104	* state, the system clock is set ahead one second. The microtime()
	105	* routine or external clock driver will insure that reported time is
	106	* always monotonic. The ugly divides should be replaced.
	107	*/
	108	switch (time_state) {
	109	case TIME_OK:
	110	if (time_status & STA_INS)
	111	time_state = TIME_INS;
	112	else if (time_status & STA_DEL)
	113	time_state = TIME_DEL;
	114	break;
	115	case TIME_INS:
	116	if (xtime.tv_sec % 86400 == 0) {
	117	xtime.tv_sec--;
	118	wall_to_monotonic.tv_sec++;
4c7ee8de	119	time_state = TIME_OOP;
4c7ee8de	120	printk(KERN_NOTICE "Clock: inserting leap second "
	121	"23:59:60 UTC\n");
	122	}
	123	break;
	124	case TIME_DEL:
	125	if ((xtime.tv_sec + 1) % 86400 == 0) {
	126	xtime.tv_sec++;
	127	wall_to_monotonic.tv_sec--;
4c7ee8de	128	time_state = TIME_WAIT;
4c7ee8de	129	printk(KERN_NOTICE "Clock: deleting leap second "
	130	"23:59:59 UTC\n");
	131	}
	132	break;
	133	case TIME_OOP:
	134	time_state = TIME_WAIT;
	135	break;
	136	case TIME_WAIT:
	137	if (!(time_status & (STA_INS \| STA_DEL)))
	138	time_state = TIME_OK;
	139	}
	140
	141	/*
f1992393 RZ	142	* Compute the phase adjustment for the next second. The offset is
f1992393 RZ	143	* reduced by a fixed factor times the time constant.
4c7ee8de	144	*/
b0ee7556	145	tick_length = tick_length_base;
f1992393	146	time_adj = shift_right(time_offset, SHIFT_PLL + time_constant);
3d3675cc RZ	147	time_offset -= time_adj;
3d3675cc RZ	148	tick_length += (s64)time_adj << (TICK_LENGTH_SHIFT - SHIFT_UPDATE);
4c7ee8de	149
8f807f8d RZ	150	if (unlikely(time_adjust)) {
	151	if (time_adjust > MAX_TICKADJ) {
	152	time_adjust -= MAX_TICKADJ;
	153	tick_length += MAX_TICKADJ_SCALED;
	154	} else if (time_adjust < -MAX_TICKADJ) {
	155	time_adjust += MAX_TICKADJ;
	156	tick_length -= MAX_TICKADJ_SCALED;
	157	} else {
8f807f8d	158	tick_length += (s64)(time_adjust * NSEC_PER_USEC /
f4304ab2	159	NTP_INTERVAL_FREQ) << TICK_LENGTH_SHIFT;
bb1d8605	160	time_adjust = 0;
8f807f8d	161	}
4c7ee8de	162	}
	163	}
	164
	165	/*
	166	* Return how long ticks are at the moment, that is, how much time
	167	* update_wall_time_one_tick will add to xtime next time we call it
	168	* (assuming no calls to do_adjtimex in the meantime).
	169	* The return value is in fixed-point nanoseconds shifted by the
	170	* specified number of bits to the right of the binary point.
	171	* This function has no side-effects.
	172	*/
	173	u64 current_tick_length(void)
	174	{
8f807f8d	175	return tick_length;
4c7ee8de	176	}
	177
	178
	179	void __attribute__ ((weak)) notify_arch_cmos_timer(void)
	180	{
	181	return;
	182	}
	183
	184	/* adjtimex mainly allows reading (and writing, if superuser) of
	185	* kernel time-keeping variables. used by xntpd.
	186	*/
	187	int do_adjtimex(struct timex *txc)
	188	{
d62ac21a	189	long mtemp, save_adjust, rem;
f1992393	190	s64 freq_adj, temp64;
4c7ee8de	191	int result;
	192
	193	/* In order to modify anything, you gotta be super-user! */
	194	if (txc->modes && !capable(CAP_SYS_TIME))
	195	return -EPERM;
	196
	197	/* Now we validate the data before disabling interrupts */
	198
	199	if ((txc->modes & ADJ_OFFSET_SINGLESHOT) == ADJ_OFFSET_SINGLESHOT)
	200	/* singleshot must not be used with any other mode bits */
	201	if (txc->modes != ADJ_OFFSET_SINGLESHOT)
	202	return -EINVAL;
	203
	204	if (txc->modes != ADJ_OFFSET_SINGLESHOT && (txc->modes & ADJ_OFFSET))
	205	/* adjustment Offset limited to +- .512 seconds */
	206	if (txc->offset <= - MAXPHASE \|\| txc->offset >= MAXPHASE )
	207	return -EINVAL;
	208
	209	/* if the quartz is off by more than 10% something is VERY wrong ! */
	210	if (txc->modes & ADJ_TICK)
	211	if (txc->tick < 900000/USER_HZ \|\|
	212	txc->tick > 1100000/USER_HZ)
	213	return -EINVAL;
	214
	215	write_seqlock_irq(&xtime_lock);
	216	result = time_state; /* mostly `TIME_OK' */
	217
	218	/* Save for later - semantics of adjtime is to return old value */
8f807f8d	219	save_adjust = time_adjust;
4c7ee8de	220
	221	#if 0 /* STA_CLOCKERR is never set yet */
	222	time_status &= ~STA_CLOCKERR; /* reset STA_CLOCKERR */
	223	#endif
	224	/* If there are input parameters, then process them */
	225	if (txc->modes)
	226	{
	227	if (txc->modes & ADJ_STATUS) /* only set allowed bits */
	228	time_status = (txc->status & ~STA_RONLY) \|
	229	(time_status & STA_RONLY);
	230
	231	if (txc->modes & ADJ_FREQUENCY) { /* p. 22 */
	232	if (txc->freq > MAXFREQ \|\| txc->freq < -MAXFREQ) {
	233	result = -EINVAL;
	234	goto leave;
	235	}
f4304ab2	236	time_freq = ((s64)txc->freq * NSEC_PER_USEC)
f4304ab2	237	>> (SHIFT_USEC - SHIFT_NSEC);
4c7ee8de	238	}
	239
	240	if (txc->modes & ADJ_MAXERROR) {
	241	if (txc->maxerror < 0 \|\| txc->maxerror >= NTP_PHASE_LIMIT) {
	242	result = -EINVAL;
	243	goto leave;
	244	}
	245	time_maxerror = txc->maxerror;
	246	}
	247
	248	if (txc->modes & ADJ_ESTERROR) {
	249	if (txc->esterror < 0 \|\| txc->esterror >= NTP_PHASE_LIMIT) {
	250	result = -EINVAL;
	251	goto leave;
	252	}
	253	time_esterror = txc->esterror;
	254	}
	255
	256	if (txc->modes & ADJ_TIMECONST) { /* p. 24 */
	257	if (txc->constant < 0) { /* NTP v4 uses values > 6 */
	258	result = -EINVAL;
	259	goto leave;
	260	}
f1992393	261	time_constant = min(txc->constant + 4, (long)MAXTC);
4c7ee8de	262	}
	263
	264	if (txc->modes & ADJ_OFFSET) { /* values checked earlier */
	265	if (txc->modes == ADJ_OFFSET_SINGLESHOT) {
	266	/* adjtime() is independent from ntp_adjtime() */
8f807f8d	267	time_adjust = txc->offset;
4c7ee8de	268	}
4c7ee8de	269	else if (time_status & STA_PLL) {
d62ac21a	270	time_offset = txc->offset * NSEC_PER_USEC;
4c7ee8de	271
	272	/*
	273	* Scale the phase adjustment and
	274	* clamp to the operating range.
	275	*/
d62ac21a	276	time_offset = min(time_offset, (s64)MAXPHASE * NSEC_PER_USEC);
d62ac21a	277	time_offset = max(time_offset, (s64)-MAXPHASE * NSEC_PER_USEC);
4c7ee8de	278
	279	/*
	280	* Select whether the frequency is to be controlled
	281	* and in which mode (PLL or FLL). Clamp to the operating
	282	* range. Ugly multiply/divide should be replaced someday.
	283	*/
	284
	285	if (time_status & STA_FREQHOLD \|\| time_reftime == 0)
	286	time_reftime = xtime.tv_sec;
	287	mtemp = xtime.tv_sec - time_reftime;
	288	time_reftime = xtime.tv_sec;
f1992393	289
d62ac21a	290	freq_adj = time_offset * mtemp;
f1992393 RZ	291	freq_adj = shift_right(freq_adj, time_constant * 2 +
	292	(SHIFT_PLL + 2) * 2 - SHIFT_NSEC);
	293	if (mtemp >= MINSEC && (time_status & STA_FLL \|\| mtemp > MAXSEC)) {
d62ac21a	294	temp64 = time_offset << (SHIFT_NSEC - SHIFT_FLL);
f1992393 RZ	295	if (time_offset < 0) {
	296	temp64 = -temp64;
	297	do_div(temp64, mtemp);
	298	freq_adj -= temp64;
	299	} else {
	300	do_div(temp64, mtemp);
	301	freq_adj += temp64;
	302	}
4c7ee8de	303	}
04b617e7 RZ	304	freq_adj += time_freq;
	305	freq_adj = min(freq_adj, (s64)MAXFREQ_NSEC);
	306	time_freq = max(freq_adj, (s64)-MAXFREQ_NSEC);
d62ac21a	307	time_offset = div_long_long_rem_signed(time_offset,
	308	NTP_INTERVAL_FREQ,
	309	&rem);
	310	time_offset <<= SHIFT_UPDATE;
4c7ee8de	311	} /* STA_PLL */
4c7ee8de	312	} /* txc->modes & ADJ_OFFSET */
b0ee7556	313	if (txc->modes & ADJ_TICK)
4c7ee8de	314	tick_usec = txc->tick;
b0ee7556	315
dc6a43e4	316	if (txc->modes & (ADJ_TICK\|ADJ_FREQUENCY\|ADJ_OFFSET))
b0ee7556	317	ntp_update_frequency();
4c7ee8de	318	} /* txc->modes */
	319	leave: if ((time_status & (STA_UNSYNC\|STA_CLOCKERR)) != 0)
	320	result = TIME_ERROR;
	321
	322	if ((txc->modes & ADJ_OFFSET_SINGLESHOT) == ADJ_OFFSET_SINGLESHOT)
d62ac21a	323	txc->offset = save_adjust;
3d3675cc	324	else
d62ac21a	325	txc->offset = ((long)shift_right(time_offset, SHIFT_UPDATE)) *
	326	NTP_INTERVAL_FREQ / 1000;
	327	txc->freq = (time_freq / NSEC_PER_USEC) <<
	328	(SHIFT_USEC - SHIFT_NSEC);
4c7ee8de	329	txc->maxerror = time_maxerror;
	330	txc->esterror = time_esterror;
	331	txc->status = time_status;
	332	txc->constant = time_constant;
70bc42f9	333	txc->precision = 1;
97eebe13	334	txc->tolerance = MAXFREQ;
4c7ee8de	335	txc->tick = tick_usec;
	336
	337	/* PPS is not implemented, so these are zero */
	338	txc->ppsfreq = 0;
	339	txc->jitter = 0;
	340	txc->shift = 0;
	341	txc->stabil = 0;
	342	txc->jitcnt = 0;
	343	txc->calcnt = 0;
	344	txc->errcnt = 0;
	345	txc->stbcnt = 0;
	346	write_sequnlock_irq(&xtime_lock);
	347	do_gettimeofday(&txc->time);
	348	notify_arch_cmos_timer();
	349	return(result);
	350	}