[mirror_ubuntu-bionic-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);
}

/**
 * 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 mtemp, save_adjust;
	s64 freq_adj;
	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) {	/* 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))
			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;
		} /* 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) ||
			(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 */
d62ac21a	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
b0ee7556 RZ	60	/**
	61	* ntp_clear - Clears the NTP state variables
	62	*
	63	* Must be called while holding a write on the xtime_lock
	64	*/
	65	void ntp_clear(void)
	66	{
	67	time_adjust = 0; /* stop active adjtime() */
	68	time_status \|= STA_UNSYNC;
	69	time_maxerror = NTP_PHASE_LIMIT;
	70	time_esterror = NTP_PHASE_LIMIT;
	71
	72	ntp_update_frequency();
	73
	74	tick_length = tick_length_base;
3d3675cc	75	time_offset = 0;
b0ee7556 RZ	76	}
b0ee7556 RZ	77
4c7ee8de JS	78	/*
	79	* this routine handles the overflow of the microsecond field
	80	*
	81	* The tricky bits of code to handle the accurate clock support
	82	* were provided by Dave Mills (Mills@UDEL.EDU) of NTP fame.
	83	* They were originally developed for SUN and DEC kernels.
	84	* All the kudos should go to Dave for this stuff.
	85	*/
	86	void second_overflow(void)
	87	{
3d3675cc	88	long time_adj;
4c7ee8de JS	89
4c7ee8de JS	90	/* Bump the maxerror field */
97eebe13	91	time_maxerror += MAXFREQ >> SHIFT_USEC;
4c7ee8de JS	92	if (time_maxerror > NTP_PHASE_LIMIT) {
	93	time_maxerror = NTP_PHASE_LIMIT;
	94	time_status \|= STA_UNSYNC;
	95	}
	96
	97	/*
	98	* Leap second processing. If in leap-insert state at the end of the
	99	* day, the system clock is set back one second; if in leap-delete
	100	* state, the system clock is set ahead one second. The microtime()
	101	* routine or external clock driver will insure that reported time is
	102	* always monotonic. The ugly divides should be replaced.
	103	*/
	104	switch (time_state) {
	105	case TIME_OK:
	106	if (time_status & STA_INS)
	107	time_state = TIME_INS;
	108	else if (time_status & STA_DEL)
	109	time_state = TIME_DEL;
	110	break;
	111	case TIME_INS:
	112	if (xtime.tv_sec % 86400 == 0) {
	113	xtime.tv_sec--;
	114	wall_to_monotonic.tv_sec++;
4c7ee8de	115	time_state = TIME_OOP;
4c7ee8de JS	116	printk(KERN_NOTICE "Clock: inserting leap second "
	117	"23:59:60 UTC\n");
	118	}
	119	break;
	120	case TIME_DEL:
	121	if ((xtime.tv_sec + 1) % 86400 == 0) {
	122	xtime.tv_sec++;
	123	wall_to_monotonic.tv_sec--;
4c7ee8de	124	time_state = TIME_WAIT;
4c7ee8de JS	125	printk(KERN_NOTICE "Clock: deleting leap second "
	126	"23:59:59 UTC\n");
	127	}
	128	break;
	129	case TIME_OOP:
	130	time_state = TIME_WAIT;
	131	break;
	132	case TIME_WAIT:
	133	if (!(time_status & (STA_INS \| STA_DEL)))
	134	time_state = TIME_OK;
	135	}
	136
	137	/*
f1992393 RZ	138	* Compute the phase adjustment for the next second. The offset is
f1992393 RZ	139	* reduced by a fixed factor times the time constant.
4c7ee8de	140	*/
b0ee7556	141	tick_length = tick_length_base;
f1992393	142	time_adj = shift_right(time_offset, SHIFT_PLL + time_constant);
3d3675cc RZ	143	time_offset -= time_adj;
3d3675cc RZ	144	tick_length += (s64)time_adj << (TICK_LENGTH_SHIFT - SHIFT_UPDATE);
4c7ee8de	145
8f807f8d RZ	146	if (unlikely(time_adjust)) {
	147	if (time_adjust > MAX_TICKADJ) {
	148	time_adjust -= MAX_TICKADJ;
	149	tick_length += MAX_TICKADJ_SCALED;
	150	} else if (time_adjust < -MAX_TICKADJ) {
	151	time_adjust += MAX_TICKADJ;
	152	tick_length -= MAX_TICKADJ_SCALED;
	153	} else {
8f807f8d	154	tick_length += (s64)(time_adjust * NSEC_PER_USEC /
f4304ab2	155	NTP_INTERVAL_FREQ) << TICK_LENGTH_SHIFT;
bb1d8605	156	time_adjust = 0;
8f807f8d	157	}
4c7ee8de JS	158	}
	159	}
	160
	161	/*
	162	* Return how long ticks are at the moment, that is, how much time
	163	* update_wall_time_one_tick will add to xtime next time we call it
	164	* (assuming no calls to do_adjtimex in the meantime).
	165	* The return value is in fixed-point nanoseconds shifted by the
	166	* specified number of bits to the right of the binary point.
	167	* This function has no side-effects.
	168	*/
	169	u64 current_tick_length(void)
	170	{
8f807f8d	171	return tick_length;
4c7ee8de JS	172	}
4c7ee8de JS	173
82644459	174	#ifdef CONFIG_GENERIC_CMOS_UPDATE
4c7ee8de	175
82644459 TG	176	/* Disable the cmos update - used by virtualization and embedded */
	177	int no_sync_cmos_clock __read_mostly;
	178
	179	static void sync_cmos_clock(unsigned long dummy);
	180
	181	static DEFINE_TIMER(sync_cmos_timer, sync_cmos_clock, 0, 0);
	182
	183	static void sync_cmos_clock(unsigned long dummy)
	184	{
	185	struct timespec now, next;
	186	int fail = 1;
	187
	188	/*
	189	* If we have an externally synchronized Linux clock, then update
	190	* CMOS clock accordingly every ~11 minutes. Set_rtc_mmss() has to be
	191	* called as close as possible to 500 ms before the new second starts.
	192	* This code is run on a timer. If the clock is set, that timer
	193	* may not expire at the correct time. Thus, we adjust...
	194	*/
	195	if (!ntp_synced())
	196	/*
	197	* Not synced, exit, do not restart a timer (if one is
	198	* running, let it run out).
	199	*/
	200	return;
	201
	202	getnstimeofday(&now);
fa6a1a55	203	if (abs(now.tv_nsec - (NSEC_PER_SEC / 2)) <= tick_nsec / 2)
82644459 TG	204	fail = update_persistent_clock(now);
	205
	206	next.tv_nsec = (NSEC_PER_SEC / 2) - now.tv_nsec;
	207	if (next.tv_nsec <= 0)
	208	next.tv_nsec += NSEC_PER_SEC;
	209
	210	if (!fail)
	211	next.tv_sec = 659;
	212	else
	213	next.tv_sec = 0;
	214
	215	if (next.tv_nsec >= NSEC_PER_SEC) {
	216	next.tv_sec++;
	217	next.tv_nsec -= NSEC_PER_SEC;
	218	}
	219	mod_timer(&sync_cmos_timer, jiffies + timespec_to_jiffies(&next));
	220	}
	221
	222	static void notify_cmos_timer(void)
4c7ee8de	223	{
298a5df4	224	if (!no_sync_cmos_clock)
82644459	225	mod_timer(&sync_cmos_timer, jiffies + 1);
4c7ee8de JS	226	}
4c7ee8de JS	227
82644459 TG	228	#else
	229	static inline void notify_cmos_timer(void) { }
	230	#endif
	231
4c7ee8de JS	232	/* adjtimex mainly allows reading (and writing, if superuser) of
	233	* kernel time-keeping variables. used by xntpd.
	234	*/
	235	int do_adjtimex(struct timex *txc)
	236	{
f8bd2258	237	long mtemp, save_adjust;
71abb3af	238	s64 freq_adj;
4c7ee8de JS	239	int result;
	240
	241	/* In order to modify anything, you gotta be super-user! */
	242	if (txc->modes && !capable(CAP_SYS_TIME))
	243	return -EPERM;
	244
	245	/* Now we validate the data before disabling interrupts */
	246
52bfb360	247	if ((txc->modes & ADJ_OFFSET_SINGLESHOT) == ADJ_OFFSET_SINGLESHOT) {
4c7ee8de	248	/* singleshot must not be used with any other mode bits */
52bfb360 JS	249	if (txc->modes != ADJ_OFFSET_SINGLESHOT &&
52bfb360 JS	250	txc->modes != ADJ_OFFSET_SS_READ)
4c7ee8de	251	return -EINVAL;
52bfb360	252	}
4c7ee8de JS	253
	254	if (txc->modes != ADJ_OFFSET_SINGLESHOT && (txc->modes & ADJ_OFFSET))
	255	/* adjustment Offset limited to +- .512 seconds */
	256	if (txc->offset <= - MAXPHASE \|\| txc->offset >= MAXPHASE )
	257	return -EINVAL;
	258
	259	/* if the quartz is off by more than 10% something is VERY wrong ! */
	260	if (txc->modes & ADJ_TICK)
	261	if (txc->tick < 900000/USER_HZ \|\|
	262	txc->tick > 1100000/USER_HZ)
	263	return -EINVAL;
	264
	265	write_seqlock_irq(&xtime_lock);
	266	result = time_state; /* mostly `TIME_OK' */
	267
	268	/* Save for later - semantics of adjtime is to return old value */
8f807f8d	269	save_adjust = time_adjust;
4c7ee8de JS	270
	271	#if 0 /* STA_CLOCKERR is never set yet */
	272	time_status &= ~STA_CLOCKERR; /* reset STA_CLOCKERR */
	273	#endif
	274	/* If there are input parameters, then process them */
	275	if (txc->modes)
	276	{
	277	if (txc->modes & ADJ_STATUS) /* only set allowed bits */
	278	time_status = (txc->status & ~STA_RONLY) \|
	279	(time_status & STA_RONLY);
	280
	281	if (txc->modes & ADJ_FREQUENCY) { /* p. 22 */
	282	if (txc->freq > MAXFREQ \|\| txc->freq < -MAXFREQ) {
	283	result = -EINVAL;
	284	goto leave;
	285	}
f4304ab2 JS	286	time_freq = ((s64)txc->freq * NSEC_PER_USEC)
f4304ab2 JS	287	>> (SHIFT_USEC - SHIFT_NSEC);
4c7ee8de JS	288	}
	289
	290	if (txc->modes & ADJ_MAXERROR) {
	291	if (txc->maxerror < 0 \|\| txc->maxerror >= NTP_PHASE_LIMIT) {
	292	result = -EINVAL;
	293	goto leave;
	294	}
	295	time_maxerror = txc->maxerror;
	296	}
	297
	298	if (txc->modes & ADJ_ESTERROR) {
	299	if (txc->esterror < 0 \|\| txc->esterror >= NTP_PHASE_LIMIT) {
	300	result = -EINVAL;
	301	goto leave;
	302	}
	303	time_esterror = txc->esterror;
	304	}
	305
	306	if (txc->modes & ADJ_TIMECONST) { /* p. 24 */
	307	if (txc->constant < 0) { /* NTP v4 uses values > 6 */
	308	result = -EINVAL;
	309	goto leave;
	310	}
f1992393	311	time_constant = min(txc->constant + 4, (long)MAXTC);
4c7ee8de JS	312	}
	313
	314	if (txc->modes & ADJ_OFFSET) { /* values checked earlier */
	315	if (txc->modes == ADJ_OFFSET_SINGLESHOT) {
	316	/* adjtime() is independent from ntp_adjtime() */
8f807f8d	317	time_adjust = txc->offset;
4c7ee8de JS	318	}
4c7ee8de JS	319	else if (time_status & STA_PLL) {
d62ac21a	320	time_offset = txc->offset * NSEC_PER_USEC;
4c7ee8de JS	321
	322	/*
	323	* Scale the phase adjustment and
	324	* clamp to the operating range.
	325	*/
d62ac21a JS	326	time_offset = min(time_offset, (s64)MAXPHASE * NSEC_PER_USEC);
d62ac21a JS	327	time_offset = max(time_offset, (s64)-MAXPHASE * NSEC_PER_USEC);
4c7ee8de JS	328
	329	/*
	330	* Select whether the frequency is to be controlled
	331	* and in which mode (PLL or FLL). Clamp to the operating
	332	* range. Ugly multiply/divide should be replaced someday.
	333	*/
	334
	335	if (time_status & STA_FREQHOLD \|\| time_reftime == 0)
	336	time_reftime = xtime.tv_sec;
	337	mtemp = xtime.tv_sec - time_reftime;
	338	time_reftime = xtime.tv_sec;
f1992393	339
d62ac21a	340	freq_adj = time_offset * mtemp;
f1992393 RZ	341	freq_adj = shift_right(freq_adj, time_constant * 2 +
f1992393 RZ	342	(SHIFT_PLL + 2) * 2 - SHIFT_NSEC);
71abb3af RZ	343	if (mtemp >= MINSEC && (time_status & STA_FLL \|\| mtemp > MAXSEC))
71abb3af RZ	344	freq_adj += div_s64(time_offset << (SHIFT_NSEC - SHIFT_FLL), mtemp);
04b617e7 RZ	345	freq_adj += time_freq;
	346	freq_adj = min(freq_adj, (s64)MAXFREQ_NSEC);
	347	time_freq = max(freq_adj, (s64)-MAXFREQ_NSEC);
f8bd2258	348	time_offset = div_s64(time_offset, NTP_INTERVAL_FREQ);
d62ac21a	349	time_offset <<= SHIFT_UPDATE;
4c7ee8de JS	350	} /* STA_PLL */
4c7ee8de JS	351	} /* txc->modes & ADJ_OFFSET */
b0ee7556	352	if (txc->modes & ADJ_TICK)
4c7ee8de	353	tick_usec = txc->tick;
b0ee7556	354
dc6a43e4	355	if (txc->modes & (ADJ_TICK\|ADJ_FREQUENCY\|ADJ_OFFSET))
b0ee7556	356	ntp_update_frequency();
4c7ee8de JS	357	} /* txc->modes */
	358	leave: if ((time_status & (STA_UNSYNC\|STA_CLOCKERR)) != 0)
	359	result = TIME_ERROR;
	360
52bfb360 JS	361	if ((txc->modes == ADJ_OFFSET_SINGLESHOT) \|\|
52bfb360 JS	362	(txc->modes == ADJ_OFFSET_SS_READ))
d62ac21a	363	txc->offset = save_adjust;
3d3675cc	364	else
d62ac21a JS	365	txc->offset = ((long)shift_right(time_offset, SHIFT_UPDATE)) *
	366	NTP_INTERVAL_FREQ / 1000;
	367	txc->freq = (time_freq / NSEC_PER_USEC) <<
	368	(SHIFT_USEC - SHIFT_NSEC);
4c7ee8de JS	369	txc->maxerror = time_maxerror;
	370	txc->esterror = time_esterror;
	371	txc->status = time_status;
	372	txc->constant = time_constant;
70bc42f9	373	txc->precision = 1;
97eebe13	374	txc->tolerance = MAXFREQ;
4c7ee8de JS	375	txc->tick = tick_usec;
	376
	377	/* PPS is not implemented, so these are zero */
	378	txc->ppsfreq = 0;
	379	txc->jitter = 0;
	380	txc->shift = 0;
	381	txc->stabil = 0;
	382	txc->jitcnt = 0;
	383	txc->calcnt = 0;
	384	txc->errcnt = 0;
	385	txc->stbcnt = 0;
	386	write_sequnlock_irq(&xtime_lock);
	387	do_gettimeofday(&txc->time);
82644459	388	notify_cmos_timer();
4c7ee8de JS	389	return(result);
4c7ee8de JS	390	}
10a398d0 RZ	391
	392	static int __init ntp_tick_adj_setup(char *str)
	393	{
	394	ntp_tick_adj = simple_strtol(str, NULL, 0);
	395	return 1;
	396	}
	397
	398	__setup("ntp_tick_adj=", ntp_tick_adj_setup);