[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/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)		*/
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)
				<< TICK_LENGTH_SHIFT;
	second_length += (s64)ntp_tick_adj << TICK_LENGTH_SHIFT;
	second_length += time_freq;

	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;

	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 <<= TICK_LENGTH_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 << (TICK_LENGTH_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 << TICK_LENGTH_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;
}

/*
 * 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;
	}

	/*
	 * 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 += 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) << 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)
{
	struct timespec ts;
	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_SS_READ)
			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);

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

	/* If there are input parameters, then process them */
	if (txc->modes) {
		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;
		}

		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_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();
	}

	result = time_state;	/* mostly `TIME_OK' */
	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 = shift_right(time_offset * NTP_INTERVAL_FREQ,
					  TICK_LENGTH_SHIFT);
		if (!(time_status & STA_NANO))
			txc->offset /= NSEC_PER_USEC;
	}
	txc->freq	   = shift_right((s32)(time_freq >> PPM_SCALE_INV_SHIFT) *
					 (s64)PPM_SCALE_INV,
					 TICK_LENGTH_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;

	/* 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);

	getnstimeofday(&ts);
	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);
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>
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	19	#include <asm/timex.h>
4c7ee8de	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	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	40	long time_maxerror = NTP_PHASE_LIMIT; /* maximum error (us) */
4c7ee8de	41	long time_esterror = NTP_PHASE_LIMIT; /* estimated error (us) */
074b3b87	42	static s64 time_freq; /* frequency offset (scaled ns/s)*/
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	49	u64 second_length = (u64)(tick_usec * NSEC_PER_USEC * USER_HZ)
f4304ab2	50	<< TICK_LENGTH_SHIFT;
10a398d0	51	second_length += (s64)ntp_tick_adj << TICK_LENGTH_SHIFT;
074b3b87	52	second_length += time_freq;
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
eea83d89	68	if (!(time_status & STA_NANO))
9f14f669	69	offset *= NSEC_PER_USEC;
ee9851b2 RZ	70
	71	/*
	72	* Scale the phase adjustment and
	73	* clamp to the operating range.
	74	*/
9f14f669 RZ	75	offset = min(offset, MAXPHASE);
9f14f669 RZ	76	offset = max(offset, -MAXPHASE);
ee9851b2 RZ	77
	78	/*
	79	* Select how the frequency is to be controlled
	80	* and in which mode (PLL or FLL).
	81	*/
	82	if (time_status & STA_FREQHOLD \|\| time_reftime == 0)
	83	time_reftime = xtime.tv_sec;
	84	mtemp = xtime.tv_sec - time_reftime;
	85	time_reftime = xtime.tv_sec;
	86
9f14f669	87	freq_adj = (s64)offset * mtemp;
074b3b87	88	freq_adj <<= TICK_LENGTH_SHIFT - 2 * (SHIFT_PLL + 2 + time_constant);
eea83d89 RZ	89	time_status &= ~STA_MODE;
eea83d89 RZ	90	if (mtemp >= MINSEC && (time_status & STA_FLL \|\| mtemp > MAXSEC)) {
9f14f669	91	freq_adj += div_s64((s64)offset << (TICK_LENGTH_SHIFT - SHIFT_FLL),
074b3b87	92	mtemp);
eea83d89 RZ	93	time_status \|= STA_MODE;
eea83d89 RZ	94	}
ee9851b2	95	freq_adj += time_freq;
074b3b87 RZ	96	freq_adj = min(freq_adj, MAXFREQ_SCALED);
074b3b87 RZ	97	time_freq = max(freq_adj, -MAXFREQ_SCALED);
9f14f669 RZ	98
9f14f669 RZ	99	time_offset = div_s64((s64)offset << TICK_LENGTH_SHIFT, NTP_INTERVAL_FREQ);
ee9851b2 RZ	100	}
ee9851b2 RZ	101
b0ee7556 RZ	102	/**
	103	* ntp_clear - Clears the NTP state variables
	104	*
	105	* Must be called while holding a write on the xtime_lock
	106	*/
	107	void ntp_clear(void)
	108	{
	109	time_adjust = 0; /* stop active adjtime() */
	110	time_status \|= STA_UNSYNC;
	111	time_maxerror = NTP_PHASE_LIMIT;
	112	time_esterror = NTP_PHASE_LIMIT;
	113
	114	ntp_update_frequency();
	115
	116	tick_length = tick_length_base;
3d3675cc	117	time_offset = 0;
b0ee7556 RZ	118	}
b0ee7556 RZ	119
4c7ee8de	120	/*
	121	* this routine handles the overflow of the microsecond field
	122	*
	123	* The tricky bits of code to handle the accurate clock support
	124	* were provided by Dave Mills (Mills@UDEL.EDU) of NTP fame.
	125	* They were originally developed for SUN and DEC kernels.
	126	* All the kudos should go to Dave for this stuff.
	127	*/
	128	void second_overflow(void)
	129	{
9f14f669	130	s64 time_adj;
4c7ee8de	131
4c7ee8de	132	/* Bump the maxerror field */
074b3b87	133	time_maxerror += MAXFREQ / NSEC_PER_USEC;
4c7ee8de	134	if (time_maxerror > NTP_PHASE_LIMIT) {
	135	time_maxerror = NTP_PHASE_LIMIT;
	136	time_status \|= STA_UNSYNC;
	137	}
	138
	139	/*
	140	* Leap second processing. If in leap-insert state at the end of the
	141	* day, the system clock is set back one second; if in leap-delete
	142	* state, the system clock is set ahead one second. The microtime()
	143	* routine or external clock driver will insure that reported time is
	144	* always monotonic. The ugly divides should be replaced.
	145	*/
	146	switch (time_state) {
	147	case TIME_OK:
	148	if (time_status & STA_INS)
	149	time_state = TIME_INS;
	150	else if (time_status & STA_DEL)
	151	time_state = TIME_DEL;
	152	break;
	153	case TIME_INS:
	154	if (xtime.tv_sec % 86400 == 0) {
	155	xtime.tv_sec--;
	156	wall_to_monotonic.tv_sec++;
4c7ee8de	157	time_state = TIME_OOP;
4c7ee8de	158	printk(KERN_NOTICE "Clock: inserting leap second "
	159	"23:59:60 UTC\n");
	160	}
	161	break;
	162	case TIME_DEL:
	163	if ((xtime.tv_sec + 1) % 86400 == 0) {
	164	xtime.tv_sec++;
	165	wall_to_monotonic.tv_sec--;
4c7ee8de	166	time_state = TIME_WAIT;
4c7ee8de	167	printk(KERN_NOTICE "Clock: deleting leap second "
	168	"23:59:59 UTC\n");
	169	}
	170	break;
	171	case TIME_OOP:
	172	time_state = TIME_WAIT;
	173	break;
	174	case TIME_WAIT:
	175	if (!(time_status & (STA_INS \| STA_DEL)))
ee9851b2	176	time_state = TIME_OK;
4c7ee8de	177	}
	178
	179	/*
f1992393 RZ	180	* Compute the phase adjustment for the next second. The offset is
f1992393 RZ	181	* reduced by a fixed factor times the time constant.
4c7ee8de	182	*/
b0ee7556	183	tick_length = tick_length_base;
f1992393	184	time_adj = shift_right(time_offset, SHIFT_PLL + time_constant);
3d3675cc	185	time_offset -= time_adj;
9f14f669	186	tick_length += time_adj;
4c7ee8de	187
8f807f8d RZ	188	if (unlikely(time_adjust)) {
	189	if (time_adjust > MAX_TICKADJ) {
	190	time_adjust -= MAX_TICKADJ;
	191	tick_length += MAX_TICKADJ_SCALED;
	192	} else if (time_adjust < -MAX_TICKADJ) {
	193	time_adjust += MAX_TICKADJ;
	194	tick_length -= MAX_TICKADJ_SCALED;
	195	} else {
8f807f8d	196	tick_length += (s64)(time_adjust * NSEC_PER_USEC /
f4304ab2	197	NTP_INTERVAL_FREQ) << TICK_LENGTH_SHIFT;
bb1d8605	198	time_adjust = 0;
8f807f8d	199	}
4c7ee8de	200	}
	201	}
	202
	203	/*
	204	* Return how long ticks are at the moment, that is, how much time
	205	* update_wall_time_one_tick will add to xtime next time we call it
	206	* (assuming no calls to do_adjtimex in the meantime).
	207	* The return value is in fixed-point nanoseconds shifted by the
	208	* specified number of bits to the right of the binary point.
	209	* This function has no side-effects.
	210	*/
	211	u64 current_tick_length(void)
	212	{
8f807f8d	213	return tick_length;
4c7ee8de	214	}
4c7ee8de	215
82644459	216	#ifdef CONFIG_GENERIC_CMOS_UPDATE
4c7ee8de	217
82644459 TG	218	/* Disable the cmos update - used by virtualization and embedded */
	219	int no_sync_cmos_clock __read_mostly;
	220
	221	static void sync_cmos_clock(unsigned long dummy);
	222
	223	static DEFINE_TIMER(sync_cmos_timer, sync_cmos_clock, 0, 0);
	224
	225	static void sync_cmos_clock(unsigned long dummy)
	226	{
	227	struct timespec now, next;
	228	int fail = 1;
	229
	230	/*
	231	* If we have an externally synchronized Linux clock, then update
	232	* CMOS clock accordingly every ~11 minutes. Set_rtc_mmss() has to be
	233	* called as close as possible to 500 ms before the new second starts.
	234	* This code is run on a timer. If the clock is set, that timer
	235	* may not expire at the correct time. Thus, we adjust...
	236	*/
	237	if (!ntp_synced())
	238	/*
	239	* Not synced, exit, do not restart a timer (if one is
	240	* running, let it run out).
	241	*/
	242	return;
	243
	244	getnstimeofday(&now);
fa6a1a55	245	if (abs(now.tv_nsec - (NSEC_PER_SEC / 2)) <= tick_nsec / 2)
82644459 TG	246	fail = update_persistent_clock(now);
	247
	248	next.tv_nsec = (NSEC_PER_SEC / 2) - now.tv_nsec;
	249	if (next.tv_nsec <= 0)
	250	next.tv_nsec += NSEC_PER_SEC;
	251
	252	if (!fail)
	253	next.tv_sec = 659;
	254	else
	255	next.tv_sec = 0;
	256
	257	if (next.tv_nsec >= NSEC_PER_SEC) {
	258	next.tv_sec++;
	259	next.tv_nsec -= NSEC_PER_SEC;
	260	}
	261	mod_timer(&sync_cmos_timer, jiffies + timespec_to_jiffies(&next));
	262	}
	263
	264	static void notify_cmos_timer(void)
4c7ee8de	265	{
298a5df4	266	if (!no_sync_cmos_clock)
82644459	267	mod_timer(&sync_cmos_timer, jiffies + 1);
4c7ee8de	268	}
4c7ee8de	269
82644459 TG	270	#else
	271	static inline void notify_cmos_timer(void) { }
	272	#endif
	273
4c7ee8de	274	/* adjtimex mainly allows reading (and writing, if superuser) of
	275	* kernel time-keeping variables. used by xntpd.
	276	*/
	277	int do_adjtimex(struct timex *txc)
	278	{
eea83d89	279	struct timespec ts;
ee9851b2	280	long save_adjust;
4c7ee8de	281	int result;
	282
	283	/* In order to modify anything, you gotta be super-user! */
	284	if (txc->modes && !capable(CAP_SYS_TIME))
	285	return -EPERM;
	286
	287	/* Now we validate the data before disabling interrupts */
	288
52bfb360	289	if ((txc->modes & ADJ_OFFSET_SINGLESHOT) == ADJ_OFFSET_SINGLESHOT) {
eea83d89 RZ	290	/* singleshot must not be used with any other mode bits */
eea83d89 RZ	291	if (txc->modes & ~ADJ_OFFSET_SS_READ)
4c7ee8de	292	return -EINVAL;
52bfb360	293	}
4c7ee8de	294
4c7ee8de	295	/* if the quartz is off by more than 10% something is VERY wrong ! */
	296	if (txc->modes & ADJ_TICK)
	297	if (txc->tick < 900000/USER_HZ \|\|
	298	txc->tick > 1100000/USER_HZ)
	299	return -EINVAL;
	300
	301	write_seqlock_irq(&xtime_lock);
4c7ee8de	302
4c7ee8de	303	/* Save for later - semantics of adjtime is to return old value */
8f807f8d	304	save_adjust = time_adjust;
4c7ee8de	305
4c7ee8de	306	/* If there are input parameters, then process them */
ee9851b2	307	if (txc->modes) {
eea83d89 RZ	308	if (txc->modes & ADJ_STATUS) {
	309	if ((time_status & STA_PLL) &&
	310	!(txc->status & STA_PLL)) {
	311	time_state = TIME_OK;
	312	time_status = STA_UNSYNC;
	313	}
	314	/* only set allowed bits */
	315	time_status &= STA_RONLY;
	316	time_status \|= txc->status & ~STA_RONLY;
	317	}
	318
	319	if (txc->modes & ADJ_NANO)
	320	time_status \|= STA_NANO;
	321	if (txc->modes & ADJ_MICRO)
	322	time_status &= ~STA_NANO;
ee9851b2 RZ	323
ee9851b2 RZ	324	if (txc->modes & ADJ_FREQUENCY) {
074b3b87 RZ	325	time_freq = (s64)txc->freq * PPM_SCALE;
	326	time_freq = min(time_freq, MAXFREQ_SCALED);
	327	time_freq = max(time_freq, -MAXFREQ_SCALED);
4c7ee8de	328	}
ee9851b2	329
eea83d89	330	if (txc->modes & ADJ_MAXERROR)
ee9851b2	331	time_maxerror = txc->maxerror;
eea83d89	332	if (txc->modes & ADJ_ESTERROR)
ee9851b2	333	time_esterror = txc->esterror;
4c7ee8de	334
ee9851b2	335	if (txc->modes & ADJ_TIMECONST) {
eea83d89 RZ	336	time_constant = txc->constant;
	337	if (!(time_status & STA_NANO))
	338	time_constant += 4;
	339	time_constant = min(time_constant, (long)MAXTC);
	340	time_constant = max(time_constant, 0l);
4c7ee8de	341	}
4c7ee8de	342
ee9851b2 RZ	343	if (txc->modes & ADJ_OFFSET) {
	344	if (txc->modes == ADJ_OFFSET_SINGLESHOT)
	345	/* adjtime() is independent from ntp_adjtime() */
	346	time_adjust = txc->offset;
	347	else
	348	ntp_update_offset(txc->offset);
4c7ee8de	349	}
ee9851b2 RZ	350	if (txc->modes & ADJ_TICK)
	351	tick_usec = txc->tick;
	352
	353	if (txc->modes & (ADJ_TICK\|ADJ_FREQUENCY\|ADJ_OFFSET))
	354	ntp_update_frequency();
	355	}
eea83d89 RZ	356
eea83d89 RZ	357	result = time_state; /* mostly `TIME_OK' */
ee9851b2	358	if (time_status & (STA_UNSYNC\|STA_CLOCKERR))
4c7ee8de	359	result = TIME_ERROR;
4c7ee8de	360
52bfb360	361	if ((txc->modes == ADJ_OFFSET_SINGLESHOT) \|\|
ee9851b2	362	(txc->modes == ADJ_OFFSET_SS_READ))
d62ac21a	363	txc->offset = save_adjust;
eea83d89	364	else {
9f14f669 RZ	365	txc->offset = shift_right(time_offset * NTP_INTERVAL_FREQ,
9f14f669 RZ	366	TICK_LENGTH_SHIFT);
eea83d89 RZ	367	if (!(time_status & STA_NANO))
	368	txc->offset /= NSEC_PER_USEC;
	369	}
074b3b87 RZ	370	txc->freq = shift_right((s32)(time_freq >> PPM_SCALE_INV_SHIFT) *
	371	(s64)PPM_SCALE_INV,
	372	TICK_LENGTH_SHIFT);
4c7ee8de	373	txc->maxerror = time_maxerror;
	374	txc->esterror = time_esterror;
	375	txc->status = time_status;
	376	txc->constant = time_constant;
70bc42f9	377	txc->precision = 1;
074b3b87	378	txc->tolerance = MAXFREQ_SCALED / PPM_SCALE;
4c7ee8de	379	txc->tick = tick_usec;
	380
	381	/* PPS is not implemented, so these are zero */
	382	txc->ppsfreq = 0;
	383	txc->jitter = 0;
	384	txc->shift = 0;
	385	txc->stabil = 0;
	386	txc->jitcnt = 0;
	387	txc->calcnt = 0;
	388	txc->errcnt = 0;
	389	txc->stbcnt = 0;
	390	write_sequnlock_irq(&xtime_lock);
ee9851b2	391
eea83d89 RZ	392	getnstimeofday(&ts);
	393	txc->time.tv_sec = ts.tv_sec;
	394	txc->time.tv_usec = ts.tv_nsec;
	395	if (!(time_status & STA_NANO))
	396	txc->time.tv_usec /= NSEC_PER_USEC;
ee9851b2	397
82644459	398	notify_cmos_timer();
ee9851b2 RZ	399
ee9851b2 RZ	400	return result;
4c7ee8de	401	}
10a398d0 RZ	402
	403	static int __init ntp_tick_adj_setup(char *str)
	404	{
	405	ntp_tick_adj = simple_strtol(str, NULL, 0);
	406	return 1;
	407	}
	408
	409	__setup("ntp_tick_adj=", ntp_tick_adj_setup);