[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;
	if (!(time_status & STA_NANO))
		time_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);
	time_status &= ~STA_MODE;
	if (mtemp >= MINSEC && (time_status & STA_FLL || mtemp > MAXSEC)) {
		freq_adj += div_s64(time_offset << (SHIFT_NSEC - SHIFT_FLL), mtemp);
		time_status |= STA_MODE;
	}
	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)
{
	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 = min(txc->freq, MAXFREQ);
			time_freq = min(time_freq, -MAXFREQ);
			time_freq = ((s64)time_freq * NSEC_PER_USEC)
					>> (SHIFT_USEC - SHIFT_NSEC);
		}

		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 = ((long)shift_right(time_offset, SHIFT_UPDATE)) *
	    			NTP_INTERVAL_FREQ;
		if (!(time_status & STA_NANO))
			txc->offset /= NSEC_PER_USEC;
	}
	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);

	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 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
eea83d89 RZ	68	time_offset = offset;
	69	if (!(time_status & STA_NANO))
	70	time_offset *= NSEC_PER_USEC;
ee9851b2 RZ	71
	72	/*
	73	* Scale the phase adjustment and
	74	* clamp to the operating range.
	75	*/
	76	time_offset = min(time_offset, (s64)MAXPHASE * NSEC_PER_USEC);
	77	time_offset = max(time_offset, (s64)-MAXPHASE * NSEC_PER_USEC);
	78
	79	/*
	80	* Select how the frequency is to be controlled
	81	* and in which mode (PLL or FLL).
	82	*/
	83	if (time_status & STA_FREQHOLD \|\| time_reftime == 0)
	84	time_reftime = xtime.tv_sec;
	85	mtemp = xtime.tv_sec - time_reftime;
	86	time_reftime = xtime.tv_sec;
	87
	88	freq_adj = time_offset * mtemp;
	89	freq_adj = shift_right(freq_adj, time_constant * 2 +
	90	(SHIFT_PLL + 2) * 2 - SHIFT_NSEC);
eea83d89 RZ	91	time_status &= ~STA_MODE;
eea83d89 RZ	92	if (mtemp >= MINSEC && (time_status & STA_FLL \|\| mtemp > MAXSEC)) {
ee9851b2	93	freq_adj += div_s64(time_offset << (SHIFT_NSEC - SHIFT_FLL), mtemp);
eea83d89 RZ	94	time_status \|= STA_MODE;
eea83d89 RZ	95	}
ee9851b2 RZ	96	freq_adj += time_freq;
	97	freq_adj = min(freq_adj, (s64)MAXFREQ_NSEC);
	98	time_freq = max(freq_adj, (s64)-MAXFREQ_NSEC);
	99	time_offset = div_s64(time_offset, NTP_INTERVAL_FREQ);
	100	time_offset <<= SHIFT_UPDATE;
	101	}
	102
b0ee7556 RZ	103	/**
	104	* ntp_clear - Clears the NTP state variables
	105	*
	106	* Must be called while holding a write on the xtime_lock
	107	*/
	108	void ntp_clear(void)
	109	{
	110	time_adjust = 0; /* stop active adjtime() */
	111	time_status \|= STA_UNSYNC;
	112	time_maxerror = NTP_PHASE_LIMIT;
	113	time_esterror = NTP_PHASE_LIMIT;
	114
	115	ntp_update_frequency();
	116
	117	tick_length = tick_length_base;
3d3675cc	118	time_offset = 0;
b0ee7556 RZ	119	}
b0ee7556 RZ	120
4c7ee8de JS	121	/*
	122	* this routine handles the overflow of the microsecond field
	123	*
	124	* The tricky bits of code to handle the accurate clock support
	125	* were provided by Dave Mills (Mills@UDEL.EDU) of NTP fame.
	126	* They were originally developed for SUN and DEC kernels.
	127	* All the kudos should go to Dave for this stuff.
	128	*/
	129	void second_overflow(void)
	130	{
3d3675cc	131	long time_adj;
4c7ee8de JS	132
4c7ee8de JS	133	/* Bump the maxerror field */
97eebe13	134	time_maxerror += MAXFREQ >> SHIFT_USEC;
4c7ee8de JS	135	if (time_maxerror > NTP_PHASE_LIMIT) {
	136	time_maxerror = NTP_PHASE_LIMIT;
	137	time_status \|= STA_UNSYNC;
	138	}
	139
	140	/*
	141	* Leap second processing. If in leap-insert state at the end of the
	142	* day, the system clock is set back one second; if in leap-delete
	143	* state, the system clock is set ahead one second. The microtime()
	144	* routine or external clock driver will insure that reported time is
	145	* always monotonic. The ugly divides should be replaced.
	146	*/
	147	switch (time_state) {
	148	case TIME_OK:
	149	if (time_status & STA_INS)
	150	time_state = TIME_INS;
	151	else if (time_status & STA_DEL)
	152	time_state = TIME_DEL;
	153	break;
	154	case TIME_INS:
	155	if (xtime.tv_sec % 86400 == 0) {
	156	xtime.tv_sec--;
	157	wall_to_monotonic.tv_sec++;
4c7ee8de	158	time_state = TIME_OOP;
4c7ee8de JS	159	printk(KERN_NOTICE "Clock: inserting leap second "
	160	"23:59:60 UTC\n");
	161	}
	162	break;
	163	case TIME_DEL:
	164	if ((xtime.tv_sec + 1) % 86400 == 0) {
	165	xtime.tv_sec++;
	166	wall_to_monotonic.tv_sec--;
4c7ee8de	167	time_state = TIME_WAIT;
4c7ee8de JS	168	printk(KERN_NOTICE "Clock: deleting leap second "
	169	"23:59:59 UTC\n");
	170	}
	171	break;
	172	case TIME_OOP:
	173	time_state = TIME_WAIT;
	174	break;
	175	case TIME_WAIT:
	176	if (!(time_status & (STA_INS \| STA_DEL)))
ee9851b2	177	time_state = TIME_OK;
4c7ee8de JS	178	}
	179
	180	/*
f1992393 RZ	181	* Compute the phase adjustment for the next second. The offset is
f1992393 RZ	182	* reduced by a fixed factor times the time constant.
4c7ee8de	183	*/
b0ee7556	184	tick_length = tick_length_base;
f1992393	185	time_adj = shift_right(time_offset, SHIFT_PLL + time_constant);
3d3675cc RZ	186	time_offset -= time_adj;
3d3675cc RZ	187	tick_length += (s64)time_adj << (TICK_LENGTH_SHIFT - SHIFT_UPDATE);
4c7ee8de	188
8f807f8d RZ	189	if (unlikely(time_adjust)) {
	190	if (time_adjust > MAX_TICKADJ) {
	191	time_adjust -= MAX_TICKADJ;
	192	tick_length += MAX_TICKADJ_SCALED;
	193	} else if (time_adjust < -MAX_TICKADJ) {
	194	time_adjust += MAX_TICKADJ;
	195	tick_length -= MAX_TICKADJ_SCALED;
	196	} else {
8f807f8d	197	tick_length += (s64)(time_adjust * NSEC_PER_USEC /
f4304ab2	198	NTP_INTERVAL_FREQ) << TICK_LENGTH_SHIFT;
bb1d8605	199	time_adjust = 0;
8f807f8d	200	}
4c7ee8de JS	201	}
	202	}
	203
	204	/*
	205	* Return how long ticks are at the moment, that is, how much time
	206	* update_wall_time_one_tick will add to xtime next time we call it
	207	* (assuming no calls to do_adjtimex in the meantime).
	208	* The return value is in fixed-point nanoseconds shifted by the
	209	* specified number of bits to the right of the binary point.
	210	* This function has no side-effects.
	211	*/
	212	u64 current_tick_length(void)
	213	{
8f807f8d	214	return tick_length;
4c7ee8de JS	215	}
4c7ee8de JS	216
82644459	217	#ifdef CONFIG_GENERIC_CMOS_UPDATE
4c7ee8de	218
82644459 TG	219	/* Disable the cmos update - used by virtualization and embedded */
	220	int no_sync_cmos_clock __read_mostly;
	221
	222	static void sync_cmos_clock(unsigned long dummy);
	223
	224	static DEFINE_TIMER(sync_cmos_timer, sync_cmos_clock, 0, 0);
	225
	226	static void sync_cmos_clock(unsigned long dummy)
	227	{
	228	struct timespec now, next;
	229	int fail = 1;
	230
	231	/*
	232	* If we have an externally synchronized Linux clock, then update
	233	* CMOS clock accordingly every ~11 minutes. Set_rtc_mmss() has to be
	234	* called as close as possible to 500 ms before the new second starts.
	235	* This code is run on a timer. If the clock is set, that timer
	236	* may not expire at the correct time. Thus, we adjust...
	237	*/
	238	if (!ntp_synced())
	239	/*
	240	* Not synced, exit, do not restart a timer (if one is
	241	* running, let it run out).
	242	*/
	243	return;
	244
	245	getnstimeofday(&now);
fa6a1a55	246	if (abs(now.tv_nsec - (NSEC_PER_SEC / 2)) <= tick_nsec / 2)
82644459 TG	247	fail = update_persistent_clock(now);
	248
	249	next.tv_nsec = (NSEC_PER_SEC / 2) - now.tv_nsec;
	250	if (next.tv_nsec <= 0)
	251	next.tv_nsec += NSEC_PER_SEC;
	252
	253	if (!fail)
	254	next.tv_sec = 659;
	255	else
	256	next.tv_sec = 0;
	257
	258	if (next.tv_nsec >= NSEC_PER_SEC) {
	259	next.tv_sec++;
	260	next.tv_nsec -= NSEC_PER_SEC;
	261	}
	262	mod_timer(&sync_cmos_timer, jiffies + timespec_to_jiffies(&next));
	263	}
	264
	265	static void notify_cmos_timer(void)
4c7ee8de	266	{
298a5df4	267	if (!no_sync_cmos_clock)
82644459	268	mod_timer(&sync_cmos_timer, jiffies + 1);
4c7ee8de JS	269	}
4c7ee8de JS	270
82644459 TG	271	#else
	272	static inline void notify_cmos_timer(void) { }
	273	#endif
	274
4c7ee8de JS	275	/* adjtimex mainly allows reading (and writing, if superuser) of
	276	* kernel time-keeping variables. used by xntpd.
	277	*/
	278	int do_adjtimex(struct timex *txc)
	279	{
eea83d89	280	struct timespec ts;
ee9851b2	281	long save_adjust;
4c7ee8de JS	282	int result;
	283
	284	/* In order to modify anything, you gotta be super-user! */
	285	if (txc->modes && !capable(CAP_SYS_TIME))
	286	return -EPERM;
	287
	288	/* Now we validate the data before disabling interrupts */
	289
52bfb360	290	if ((txc->modes & ADJ_OFFSET_SINGLESHOT) == ADJ_OFFSET_SINGLESHOT) {
eea83d89 RZ	291	/* singleshot must not be used with any other mode bits */
eea83d89 RZ	292	if (txc->modes & ~ADJ_OFFSET_SS_READ)
4c7ee8de	293	return -EINVAL;
52bfb360	294	}
4c7ee8de	295
4c7ee8de JS	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);
4c7ee8de JS	303
4c7ee8de JS	304	/* Save for later - semantics of adjtime is to return old value */
8f807f8d	305	save_adjust = time_adjust;
4c7ee8de	306
4c7ee8de	307	/* If there are input parameters, then process them */
ee9851b2	308	if (txc->modes) {
eea83d89 RZ	309	if (txc->modes & ADJ_STATUS) {
	310	if ((time_status & STA_PLL) &&
	311	!(txc->status & STA_PLL)) {
	312	time_state = TIME_OK;
	313	time_status = STA_UNSYNC;
	314	}
	315	/* only set allowed bits */
	316	time_status &= STA_RONLY;
	317	time_status \|= txc->status & ~STA_RONLY;
	318	}
	319
	320	if (txc->modes & ADJ_NANO)
	321	time_status \|= STA_NANO;
	322	if (txc->modes & ADJ_MICRO)
	323	time_status &= ~STA_NANO;
ee9851b2 RZ	324
ee9851b2 RZ	325	if (txc->modes & ADJ_FREQUENCY) {
eea83d89 RZ	326	time_freq = min(txc->freq, MAXFREQ);
	327	time_freq = min(time_freq, -MAXFREQ);
	328	time_freq = ((s64)time_freq * NSEC_PER_USEC)
ee9851b2	329	>> (SHIFT_USEC - SHIFT_NSEC);
4c7ee8de	330	}
ee9851b2	331
eea83d89	332	if (txc->modes & ADJ_MAXERROR)
ee9851b2	333	time_maxerror = txc->maxerror;
eea83d89	334	if (txc->modes & ADJ_ESTERROR)
ee9851b2	335	time_esterror = txc->esterror;
4c7ee8de	336
ee9851b2	337	if (txc->modes & ADJ_TIMECONST) {
eea83d89 RZ	338	time_constant = txc->constant;
	339	if (!(time_status & STA_NANO))
	340	time_constant += 4;
	341	time_constant = min(time_constant, (long)MAXTC);
	342	time_constant = max(time_constant, 0l);
4c7ee8de	343	}
4c7ee8de	344
ee9851b2 RZ	345	if (txc->modes & ADJ_OFFSET) {
	346	if (txc->modes == ADJ_OFFSET_SINGLESHOT)
	347	/* adjtime() is independent from ntp_adjtime() */
	348	time_adjust = txc->offset;
	349	else
	350	ntp_update_offset(txc->offset);
4c7ee8de	351	}
ee9851b2 RZ	352	if (txc->modes & ADJ_TICK)
	353	tick_usec = txc->tick;
	354
	355	if (txc->modes & (ADJ_TICK\|ADJ_FREQUENCY\|ADJ_OFFSET))
	356	ntp_update_frequency();
	357	}
eea83d89 RZ	358
eea83d89 RZ	359	result = time_state; /* mostly `TIME_OK' */
ee9851b2	360	if (time_status & (STA_UNSYNC\|STA_CLOCKERR))
4c7ee8de JS	361	result = TIME_ERROR;
4c7ee8de JS	362
52bfb360	363	if ((txc->modes == ADJ_OFFSET_SINGLESHOT) \|\|
ee9851b2	364	(txc->modes == ADJ_OFFSET_SS_READ))
d62ac21a	365	txc->offset = save_adjust;
eea83d89	366	else {
d62ac21a	367	txc->offset = ((long)shift_right(time_offset, SHIFT_UPDATE)) *
eea83d89 RZ	368	NTP_INTERVAL_FREQ;
	369	if (!(time_status & STA_NANO))
	370	txc->offset /= NSEC_PER_USEC;
	371	}
d62ac21a JS	372	txc->freq = (time_freq / NSEC_PER_USEC) <<
d62ac21a JS	373	(SHIFT_USEC - SHIFT_NSEC);
4c7ee8de JS	374	txc->maxerror = time_maxerror;
	375	txc->esterror = time_esterror;
	376	txc->status = time_status;
	377	txc->constant = time_constant;
70bc42f9	378	txc->precision = 1;
97eebe13	379	txc->tolerance = MAXFREQ;
4c7ee8de JS	380	txc->tick = tick_usec;
	381
	382	/* PPS is not implemented, so these are zero */
	383	txc->ppsfreq = 0;
	384	txc->jitter = 0;
	385	txc->shift = 0;
	386	txc->stabil = 0;
	387	txc->jitcnt = 0;
	388	txc->calcnt = 0;
	389	txc->errcnt = 0;
	390	txc->stbcnt = 0;
	391	write_sequnlock_irq(&xtime_lock);
ee9851b2	392
eea83d89 RZ	393	getnstimeofday(&ts);
	394	txc->time.tv_sec = ts.tv_sec;
	395	txc->time.tv_usec = ts.tv_nsec;
	396	if (!(time_status & STA_NANO))
	397	txc->time.tv_usec /= NSEC_PER_USEC;
ee9851b2	398
82644459	399	notify_cmos_timer();
ee9851b2 RZ	400
ee9851b2 RZ	401	return result;
4c7ee8de	402	}
10a398d0 RZ	403
	404	static int __init ntp_tick_adj_setup(char *str)
	405	{
	406	ntp_tick_adj = simple_strtol(str, NULL, 0);
	407	return 1;
	408	}
	409
	410	__setup("ntp_tick_adj=", ntp_tick_adj_setup);