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/*-

 ***********************************************************************

 *								       *

 * Copyright (c) David L. Mills 1993-2001			       *

 *								       *

 * Permission to use, copy, modify, and distribute this software and   *

 * its documentation for any purpose and without fee is hereby	       *

 * granted, provided that the above copyright notice appears in all    *

 * copies and that both the copyright notice and this permission       *

 * notice appear in supporting documentation, and that the name	       *

 * University of Delaware not be used in advertising or publicity      *

 * pertaining to distribution of the software without specific,	       *

 * written prior permission. The University of Delaware makes no       *

 * representations about the suitability this software for any	       *

 * purpose. It is provided "as is" without express or implied	       *

 * warranty.							       *

 *								       *

 **********************************************************************/

/*

 * Adapted from the original sources for FreeBSD and timecounters by:

 * Poul-Henning Kamp <phk@FreeBSD.org>.

 *

 * The 32bit version of the "LP" macros seems a bit past its "sell by" 

 * date so I have retained only the 64bit version and included it directly

 * in this file.

 *

 * Only minor changes done to interface with the timecounters over in

 * sys/kern/kern_clock.c.   Some of the comments below may be (even more)

 * confusing and/or plain wrong in that context.

 */

#include <sys/cdefs.h>

__FBSDID("$FreeBSD: src/sys/kern/kern_ntptime.c,v 1.59 2005/05/28 14:34:41 rwatson Exp $");

#include "opt_ntp.h"

#include <sys/param.h>

#include <sys/systm.h>

#include <sys/sysproto.h>

#include <sys/jail.h>

#include <sys/kernel.h>

#include <sys/proc.h>

#include <sys/lock.h>

#include <sys/mutex.h>

#include <sys/time.h>

#include <sys/timex.h>

#include <sys/timetc.h>

#include <sys/timepps.h>

#include <sys/syscallsubr.h>

#include <sys/sysctl.h>

/*

 * Single-precision macros for 64-bit machines

 */

typedef int64_t l_fp;

#define L_ADD(v, u)	((v) += (u))

#define L_SUB(v, u)	((v) -= (u))

#define L_ADDHI(v, a)	((v) += (int64_t)(a) << 32)

#define L_NEG(v)	((v) = -(v))

#define L_RSHIFT(v, n) \

	do { \

		if ((v) < 0) \

			(v) = -(-(v) >> (n)); \

		else \

			(v) = (v) >> (n); \

	} while (0)

#define L_MPY(v, a)	((v) *= (a))

#define L_CLR(v)	((v) = 0)

#define L_ISNEG(v)	((v) < 0)

#define L_LINT(v, a)	((v) = (int64_t)(a) << 32)

#define L_GINT(v)	((v) < 0 ? -(-(v) >> 32) : (v) >> 32)

/*

 * Generic NTP kernel interface

 *

 * These routines constitute the Network Time Protocol (NTP) interfaces

 * for user and daemon application programs. The ntp_gettime() routine

 * provides the time, maximum error (synch distance) and estimated error

 * (dispersion) to client user application programs. The ntp_adjtime()

 * routine is used by the NTP daemon to adjust the system clock to an

 * externally derived time. The time offset and related variables set by

 * this routine are used by other routines in this module to adjust the

 * phase and frequency of the clock discipline loop which controls the

 * system clock.

 *

 * When the kernel time is reckoned directly in nanoseconds (NTP_NANO

 * defined), the time at each tick interrupt is derived directly from

 * the kernel time variable. When the kernel time is reckoned in

 * microseconds, (NTP_NANO undefined), the time is derived from the

 * kernel time variable together with a variable representing the

 * leftover nanoseconds at the last tick interrupt. In either case, the

 * current nanosecond time is reckoned from these values plus an

 * interpolated value derived by the clock routines in another

 * architecture-specific module. The interpolation can use either a

 * dedicated counter or a processor cycle counter (PCC) implemented in

 * some architectures.

 *

 * Note that all routines must run at priority splclock or higher.

 */

/*

 * Phase/frequency-lock loop (PLL/FLL) definitions

 *

 * The nanosecond clock discipline uses two variable types, time

 * variables and frequency variables. Both types are represented as 64-

 * bit fixed-point quantities with the decimal point between two 32-bit

 * halves. On a 32-bit machine, each half is represented as a single

 * word and mathematical operations are done using multiple-precision

 * arithmetic. On a 64-bit machine, ordinary computer arithmetic is

 * used.

 *

 * A time variable is a signed 64-bit fixed-point number in ns and

 * fraction. It represents the remaining time offset to be amortized

 * over succeeding tick interrupts. The maximum time offset is about

 * 0.5 s and the resolution is about 2.3e-10 ns.

 *

 *			1 1 1 1 1 1 1 1 1 1 2 2 2 2 2 2 2 2 2 2 3 3

 *  0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1

 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

 * |s s s|			 ns				   |

 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

 * |			    fraction				   |

 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

 *

 * A frequency variable is a signed 64-bit fixed-point number in ns/s

 * and fraction. It represents the ns and fraction to be added to the

 * kernel time variable at each second. The maximum frequency offset is

 * about +-500000 ns/s and the resolution is about 2.3e-10 ns/s.

 *

 *			1 1 1 1 1 1 1 1 1 1 2 2 2 2 2 2 2 2 2 2 3 3

 *  0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1

 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

 * |s s s s s s s s s s s s s|	          ns/s			   |

 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

 * |			    fraction				   |

 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

 */

/*

 * The following variables establish the state of the PLL/FLL and the

 * residual time and frequency offset of the local clock.

 */

#define SHIFT_PLL	4		/* PLL loop gain (shift) */

#define SHIFT_FLL	2		/* FLL loop gain (shift) */

static int time_state = TIME_OK;	/* clock state */

static int time_status = STA_UNSYNC;	/* clock status bits */

static long time_tai;			/* TAI offset (s) */

static long time_monitor;		/* last time offset scaled (ns) */

static long time_constant;		/* poll interval (shift) (s) */

static long time_precision = 1;		/* clock precision (ns) */

static long time_maxerror = MAXPHASE / 1000; /* maximum error (us) */

static long time_esterror = MAXPHASE / 1000; /* estimated error (us) */

static long time_reftime;		/* time at last adjustment (s) */

static l_fp time_offset;		/* time offset (ns) */

static l_fp time_freq;			/* frequency offset (ns/s) */

static l_fp time_adj;			/* tick adjust (ns/s) */

static int64_t time_adjtime;		/* correction from adjtime(2) (usec) */

#ifdef PPS_SYNC

/*

 * The following variables are used when a pulse-per-second (PPS) signal

 * is available and connected via a modem control lead. They establish

 * the engineering parameters of the clock discipline loop when

 * controlled by the PPS signal.

 */

#define PPS_FAVG	2		/* min freq avg interval (s) (shift) */

#define PPS_FAVGDEF	8		/* default freq avg int (s) (shift) */

#define PPS_FAVGMAX	15		/* max freq avg interval (s) (shift) */

#define PPS_PAVG	4		/* phase avg interval (s) (shift) */

#define PPS_VALID	120		/* PPS signal watchdog max (s) */

#define PPS_MAXWANDER	100000		/* max PPS wander (ns/s) */

#define PPS_POPCORN	2		/* popcorn spike threshold (shift) */

static struct timespec pps_tf[3];	/* phase median filter */

static l_fp pps_freq;			/* scaled frequency offset (ns/s) */

static long pps_fcount;			/* frequency accumulator */

static long pps_jitter;			/* nominal jitter (ns) */

static long pps_stabil;			/* nominal stability (scaled ns/s) */

static long pps_lastsec;		/* time at last calibration (s) */

static int pps_valid;			/* signal watchdog counter */

static int pps_shift = PPS_FAVG;	/* interval duration (s) (shift) */

static int pps_shiftmax = PPS_FAVGDEF;	/* max interval duration (s) (shift) */

static int pps_intcnt;			/* wander counter */

/*

 * PPS signal quality monitors

 */

static long pps_calcnt;			/* calibration intervals */

static long pps_jitcnt;			/* jitter limit exceeded */

static long pps_stbcnt;			/* stability limit exceeded */

static long pps_errcnt;			/* calibration errors */

#endif /* PPS_SYNC */

/*

 * End of phase/frequency-lock loop (PLL/FLL) definitions

 */

static void ntp_init(void);

static void hardupdate(long offset);

static void ntp_gettime1(struct ntptimeval *ntvp);

static int cf_useradjtime;

static int cf_jailadjtime;

SYSCTL_INT(_kern, OID_AUTO, useradjtime, CTLFLAG_RW, &cf_useradjtime, 0,

    "Non-root is allowed to adjust system time");

SYSCTL_INT(_kern, OID_AUTO, jailadjtime, CTLFLAG_RW, &cf_jailadjtime, 0,

    "System time is allowed to be adjusted from jail");

static void

ntp_gettime1(struct ntptimeval *ntvp)

{

	struct timespec atv;	/* nanosecond time */

	GIANT_REQUIRED;

	nanotime(&atv);

	ntvp->time.tv_sec = atv.tv_sec;

	ntvp->time.tv_nsec = atv.tv_nsec;

	ntvp->maxerror = time_maxerror;

	ntvp->esterror = time_esterror;

	ntvp->tai = time_tai;

	ntvp->time_state = time_state;

	/*

	 * Status word error decode. If any of these conditions occur,

	 * an error is returned, instead of the status word. Most

	 * applications will care only about the fact the system clock

	 * may not be trusted, not about the details.

	 *

	 * Hardware or software error

	 */

	if ((time_status & (STA_UNSYNC | STA_CLOCKERR)) ||

	/*

	 * PPS signal lost when either time or frequency synchronization

	 * requested

	 */

	    (time_status & (STA_PPSFREQ | STA_PPSTIME) &&

	    !(time_status & STA_PPSSIGNAL)) ||

	/*

	 * PPS jitter exceeded when time synchronization requested

	 */

	    (time_status & STA_PPSTIME &&

	    time_status & STA_PPSJITTER) ||

	/*

	 * PPS wander exceeded or calibration error when frequency

	 * synchronization requested

	 */

	    (time_status & STA_PPSFREQ &&

	    time_status & (STA_PPSWANDER | STA_PPSERROR)))

		ntvp->time_state = TIME_ERROR;

}

/*

 * ntp_gettime() - NTP user application interface

 *

 * See the timex.h header file for synopsis and API description. Note

 * that the TAI offset is returned in the ntvtimeval.tai structure

 * member.

 */

#ifndef _SYS_SYSPROTO_H_

struct ntp_gettime_args {

	struct ntptimeval *ntvp;

};

#endif

/* ARGSUSED */

int

ntp_gettime(struct thread *td, struct ntp_gettime_args *uap)

{	

	struct ntptimeval ntv;

	mtx_lock(&Giant);

	ntp_gettime1(&ntv);

	mtx_unlock(&Giant);

	return (copyout(&ntv, uap->ntvp, sizeof(ntv)));

}

static int

ntp_sysctl(SYSCTL_HANDLER_ARGS)

{

	struct ntptimeval ntv;	/* temporary structure */

	ntp_gettime1(&ntv);

	return (sysctl_handle_opaque(oidp, &ntv, sizeof(ntv), req));

}

SYSCTL_NODE(_kern, OID_AUTO, ntp_pll, CTLFLAG_RW, 0, "");

SYSCTL_PROC(_kern_ntp_pll, OID_AUTO, gettime, CTLTYPE_OPAQUE|CTLFLAG_RD,

	0, sizeof(struct ntptimeval) , ntp_sysctl, "S,ntptimeval", "");

#ifdef PPS_SYNC

SYSCTL_INT(_kern_ntp_pll, OID_AUTO, pps_shiftmax, CTLFLAG_RW, &pps_shiftmax, 0, "");

SYSCTL_INT(_kern_ntp_pll, OID_AUTO, pps_shift, CTLFLAG_RW, &pps_shift, 0, "");

SYSCTL_INT(_kern_ntp_pll, OID_AUTO, time_monitor, CTLFLAG_RD, &time_monitor, 0, "");

SYSCTL_OPAQUE(_kern_ntp_pll, OID_AUTO, pps_freq, CTLFLAG_RD, &pps_freq, sizeof(pps_freq), "I", "");

SYSCTL_OPAQUE(_kern_ntp_pll, OID_AUTO, time_freq, CTLFLAG_RD, &time_freq, sizeof(time_freq), "I", "");

#endif

/*

 * ntp_adjtime() - NTP daemon application interface

 *

 * See the timex.h header file for synopsis and API description. Note

 * that the timex.constant structure member has a dual purpose to set

 * the time constant and to set the TAI offset.

 */

#ifndef _SYS_SYSPROTO_H_

struct ntp_adjtime_args {

	struct timex *tp;

};

#endif

/*

 * MPSAFE

 */

int

ntp_adjtime(struct thread *td, struct ntp_adjtime_args *uap)

{

	struct timex ntv;	/* temporary structure */

	long freq;		/* frequency ns/s) */

	int modes;		/* mode bits from structure */

	int s;			/* caller priority */

	int error;

	error = copyin((caddr_t)uap->tp, (caddr_t)&ntv, sizeof(ntv));

	if (error)

		return(error);

	/*

	 * Update selected clock variables - only the superuser can

	 * change anything. Note that there is no error checking here on

	 * the assumption the superuser should know what it is doing.

	 * Note that either the time constant or TAI offset are loaded

	 * from the ntv.constant member, depending on the mode bits. If

	 * the STA_PLL bit in the status word is cleared, the state and

	 * status words are reset to the initial values at boot.

	 */

	mtx_lock(&Giant);

	modes = ntv.modes;

	if (modes) {  /* XXX really check suser sometimes only? */

#ifdef MAC

		error = mac_check_system_settime(td->td_ucred);

		if (error)

			goto done2;

#endif

		if (!cf_jailadjtime && jailed(td->td_ucred)) {

			error = EPERM;

			goto done2;

		}

		if (!cf_useradjtime && 

		    (error = suser_cred(td->td_ucred, SUSER_ALLOWJAIL)) != 0)

			goto done2;            /* jail is already checked at this point */

	}

	s = splclock();

	if (modes & MOD_MAXERROR)

		time_maxerror = ntv.maxerror;

	if (modes & MOD_ESTERROR)

		time_esterror = ntv.esterror;

	if (modes & MOD_STATUS) {

		if (time_status & STA_PLL && !(ntv.status & STA_PLL)) {

			time_state = TIME_OK;

			time_status = STA_UNSYNC;

#ifdef PPS_SYNC

			pps_shift = PPS_FAVG;

#endif /* PPS_SYNC */

		}

		time_status &= STA_RONLY;

		time_status |= ntv.status & ~STA_RONLY;

	}

	if (modes & MOD_TIMECONST) {

		if (ntv.constant < 0)

			time_constant = 0;

		else if (ntv.constant > MAXTC)

			time_constant = MAXTC;

		else

			time_constant = ntv.constant;

	}

	if (modes & MOD_TAI) {

		if (ntv.constant > 0) /* XXX zero & negative numbers ? */

			time_tai = ntv.constant;

	}

#ifdef PPS_SYNC

	if (modes & MOD_PPSMAX) {

		if (ntv.shift < PPS_FAVG)

			pps_shiftmax = PPS_FAVG;

		else if (ntv.shift > PPS_FAVGMAX)

			pps_shiftmax = PPS_FAVGMAX;

		else

			pps_shiftmax = ntv.shift;

	}

#endif /* PPS_SYNC */

	if (modes & MOD_NANO)

		time_status |= STA_NANO;

	if (modes & MOD_MICRO)

		time_status &= ~STA_NANO;

	if (modes & MOD_CLKB)

		time_status |= STA_CLK;

	if (modes & MOD_CLKA)

		time_status &= ~STA_CLK;

	if (modes & MOD_FREQUENCY) {

		freq = (ntv.freq * 1000LL) >> 16;

		if (freq > MAXFREQ)

			L_LINT(time_freq, MAXFREQ);

		else if (freq < -MAXFREQ)

			L_LINT(time_freq, -MAXFREQ);

		else {

			/*

			 * ntv.freq is [PPM * 2^16] = [us/s * 2^16]

			 * time_freq is [ns/s * 2^32]

			 */

			time_freq = ntv.freq * 1000LL * 65536LL;

		}

#ifdef PPS_SYNC

		pps_freq = time_freq;

#endif /* PPS_SYNC */

	}

	if (modes & MOD_OFFSET) {

		if (time_status & STA_NANO)

			hardupdate(ntv.offset);

		else

			hardupdate(ntv.offset * 1000);

	}

	/*

	 * Retrieve all clock variables. Note that the TAI offset is

	 * returned only by ntp_gettime();

	 */

	if (time_status & STA_NANO)

		ntv.offset = L_GINT(time_offset);

	else

		ntv.offset = L_GINT(time_offset) / 1000; /* XXX rounding ? */

	ntv.freq = L_GINT((time_freq / 1000LL) << 16);

	ntv.maxerror = time_maxerror;

	ntv.esterror = time_esterror;

	ntv.status = time_status;

	ntv.constant = time_constant;

	if (time_status & STA_NANO)

		ntv.precision = time_precision;

	else

		ntv.precision = time_precision / 1000;

	ntv.tolerance = MAXFREQ * SCALE_PPM;

#ifdef PPS_SYNC

	ntv.shift = pps_shift;

	ntv.ppsfreq = L_GINT((pps_freq / 1000LL) << 16);

	if (time_status & STA_NANO)

		ntv.jitter = pps_jitter;

	else

		ntv.jitter = pps_jitter / 1000;

	ntv.stabil = pps_stabil;

	ntv.calcnt = pps_calcnt;

	ntv.errcnt = pps_errcnt;

	ntv.jitcnt = pps_jitcnt;

	ntv.stbcnt = pps_stbcnt;

#endif /* PPS_SYNC */

	splx(s);

	error = copyout((caddr_t)&ntv, (caddr_t)uap->tp, sizeof(ntv));

	if (error)

		goto done2;

	/*

	 * Status word error decode. See comments in

	 * ntp_gettime() routine.

	 */

	if ((time_status & (STA_UNSYNC | STA_CLOCKERR)) ||

	    (time_status & (STA_PPSFREQ | STA_PPSTIME) &&

	    !(time_status & STA_PPSSIGNAL)) ||

	    (time_status & STA_PPSTIME &&

	    time_status & STA_PPSJITTER) ||

	    (time_status & STA_PPSFREQ &&

	    time_status & (STA_PPSWANDER | STA_PPSERROR))) {

		td->td_retval[0] = TIME_ERROR;

	} else {

		td->td_retval[0] = time_state;

	}

done2:

	mtx_unlock(&Giant);

	return (error);

}

/*

 * second_overflow() - called after ntp_tick_adjust()

 *

 * This routine is ordinarily called immediately following the above

 * routine ntp_tick_adjust(). While these two routines are normally

 * combined, they are separated here only for the purposes of

 * simulation.

 */

void

ntp_update_second(int64_t *adjustment, time_t *newsec)

{

	int tickrate;

	l_fp ftemp;		/* 32/64-bit temporary */

	/*

	 * On rollover of the second both the nanosecond and microsecond

	 * clocks are updated and the state machine cranked as

	 * necessary. The phase adjustment to be used for the next

	 * second is calculated and the maximum error is increased by

	 * the tolerance.

	 */

	time_maxerror += MAXFREQ / 1000;

	/*

	 * 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 nano_time() routine or

	 * external clock driver will insure that reported time

	 * is always monotonic.

	 */

	switch (time_state) {

		/*

		 * No warning.

		 */

		case TIME_OK:

		if (time_status & STA_INS)

			time_state = TIME_INS;

		else if (time_status & STA_DEL)

			time_state = TIME_DEL;

		break;

		/*

		 * Insert second 23:59:60 following second

		 * 23:59:59.

		 */

		case TIME_INS:

		if (!(time_status & STA_INS))

			time_state = TIME_OK;

		else if ((*newsec) % 86400 == 0) {

			(*newsec)--;

			time_state = TIME_OOP;

			time_tai++;

		}

		break;

		/*

		 * Delete second 23:59:59.

		 */

		case TIME_DEL:

		if (!(time_status & STA_DEL))

			time_state = TIME_OK;

		else if (((*newsec) + 1) % 86400 == 0) {

			(*newsec)++;

			time_tai--;

			time_state = TIME_WAIT;

		}

		break;

		/*

		 * Insert second in progress.

		 */

		case TIME_OOP:

			time_state = TIME_WAIT;

		break;

		/*

		 * Wait for status bits to clear.

		 */

		case TIME_WAIT:

		if (!(time_status & (STA_INS | STA_DEL)))

			time_state = TIME_OK;

	}

	/*

	 * Compute the total time adjustment for the next second

	 * in ns. The offset is reduced by a factor depending on

	 * whether the PPS signal is operating. Note that the

	 * value is in effect scaled by the clock frequency,

	 * since the adjustment is added at each tick interrupt.

	 */

	ftemp = time_offset;

#ifdef PPS_SYNC

	/* XXX even if PPS signal dies we should finish adjustment ? */

	if (time_status & STA_PPSTIME && time_status &

	    STA_PPSSIGNAL)

		L_RSHIFT(ftemp, pps_shift);

	else

		L_RSHIFT(ftemp, SHIFT_PLL + time_constant);

#else

		L_RSHIFT(ftemp, SHIFT_PLL + time_constant);

#endif /* PPS_SYNC */

	time_adj = ftemp;

	L_SUB(time_offset, ftemp);

	L_ADD(time_adj, time_freq);

	/*

	 * Apply any correction from adjtime(2).  If more than one second

	 * off we slew at a rate of 5ms/s (5000 PPM) else 500us/s (500PPM)

	 * until the last second is slewed the final < 500 usecs.

	 */

	if (time_adjtime != 0) {

		if (time_adjtime > 1000000)

			tickrate = 5000;

		else if (time_adjtime < -1000000)

			tickrate = -5000;

		else if (time_adjtime > 500)

			tickrate = 500;

		else if (time_adjtime < -500)

			tickrate = -500;

		else

			tickrate = time_adjtime;

		time_adjtime -= tickrate;

		L_LINT(ftemp, tickrate * 1000);

		L_ADD(time_adj, ftemp);

	}

	*adjustment = time_adj;

#ifdef PPS_SYNC

	if (pps_valid > 0)

		pps_valid--;

	else

		time_status &= ~STA_PPSSIGNAL;

#endif /* PPS_SYNC */

}

/*

 * ntp_init() - initialize variables and structures

 *

 * This routine must be called after the kernel variables hz and tick

 * are set or changed and before the next tick interrupt. In this

 * particular implementation, these values are assumed set elsewhere in

 * the kernel. The design allows the clock frequency and tick interval

 * to be changed while the system is running. So, this routine should

 * probably be integrated with the code that does that.

 */

static void

ntp_init()

{

	/*

	 * The following variables are initialized only at startup. Only

	 * those structures not cleared by the compiler need to be

	 * initialized, and these only in the simulator. In the actual

	 * kernel, any nonzero values here will quickly evaporate.

	 */

	L_CLR(time_offset);

	L_CLR(time_freq);

#ifdef PPS_SYNC

	pps_tf[0].tv_sec = pps_tf[0].tv_nsec = 0;

	pps_tf[1].tv_sec = pps_tf[1].tv_nsec = 0;

	pps_tf[2].tv_sec = pps_tf[2].tv_nsec = 0;

	pps_fcount = 0;

	L_CLR(pps_freq);

#endif /* PPS_SYNC */	   

}

SYSINIT(ntpclocks, SI_SUB_CLOCKS, SI_ORDER_MIDDLE, ntp_init, NULL)

/*

 * hardupdate() - local clock update

 *

 * This routine is called by ntp_adjtime() to update the local clock

 * phase and frequency. The implementation is of an adaptive-parameter,

 * hybrid phase/frequency-lock loop (PLL/FLL). The routine computes new

 * time and frequency offset estimates for each call. If the kernel PPS

 * discipline code is configured (PPS_SYNC), the PPS signal itself

 * determines the new time offset, instead of the calling argument.

 * Presumably, calls to ntp_adjtime() occur only when the caller

 * believes the local clock is valid within some bound (+-128 ms with

 * NTP). If the caller's time is far different than the PPS time, an

 * argument will ensue, and it's not clear who will lose.

 *

 * For uncompensated quartz crystal oscillators and nominal update

 * intervals less than 256 s, operation should be in phase-lock mode,

 * where the loop is disciplined to phase. For update intervals greater

 * than 1024 s, operation should be in frequency-lock mode, where the

 * loop is disciplined to frequency. Between 256 s and 1024 s, the mode

 * is selected by the STA_MODE status bit.

 */

static void

hardupdate(offset)

	long offset;		/* clock offset (ns) */

{

	long mtemp;

	l_fp ftemp;

	/*

	 * Select how the phase is to be controlled and from which

	 * source. If the PPS signal is present and enabled to

	 * discipline the time, the PPS offset is used; otherwise, the

	 * argument offset is used.

	 */

	if (!(time_status & STA_PLL))

		return;

	if (!(time_status & STA_PPSTIME && time_status &

	    STA_PPSSIGNAL)) {

		if (offset > MAXPHASE)

			time_monitor = MAXPHASE;

		else if (offset < -MAXPHASE)

			time_monitor = -MAXPHASE;

		else

			time_monitor = offset;

		L_LINT(time_offset, time_monitor);

	}

	/*

	 * Select how the frequency is to be controlled and in which

	 * mode (PLL or FLL). If the PPS signal is present and enabled

	 * to discipline the frequency, the PPS frequency is used;

	 * otherwise, the argument offset is used to compute it.

	 */

	if (time_status & STA_PPSFREQ && time_status & STA_PPSSIGNAL) {

		time_reftime = time_second;

		return;

	}

	if (time_status & STA_FREQHOLD || time_reftime == 0)

		time_reftime = time_second;

	mtemp = time_second - time_reftime;

	L_LINT(ftemp, time_monitor);

	L_RSHIFT(ftemp, (SHIFT_PLL + 2 + time_constant) << 1);

	L_MPY(ftemp, mtemp);

	L_ADD(time_freq, ftemp);

	time_status &= ~STA_MODE;

	if (mtemp >= MINSEC && (time_status & STA_FLL || mtemp >

	    MAXSEC)) {

		L_LINT(ftemp, (time_monitor << 4) / mtemp);

		L_RSHIFT(ftemp, SHIFT_FLL + 4);

		L_ADD(time_freq, ftemp);

		time_status |= STA_MODE;

	}

	time_reftime = time_second;

	if (L_GINT(time_freq) > MAXFREQ)

		L_LINT(time_freq, MAXFREQ);

	else if (L_GINT(time_freq) < -MAXFREQ)

		L_LINT(time_freq, -MAXFREQ);

}

#ifdef PPS_SYNC

/*

 * hardpps() - discipline CPU clock oscillator to external PPS signal

 *

 * This routine is called at each PPS interrupt in order to discipline

 * the CPU clock oscillator to the PPS signal. There are two independent

 * first-order feedback loops, one for the phase, the other for the

 * frequency. The phase loop measures and grooms the PPS phase offset

 * and leaves it in a handy spot for the seconds overflow routine. The

 * frequency loop averages successive PPS phase differences and

 * calculates the PPS frequency offset, which is also processed by the

 * seconds overflow routine. The code requires the caller to capture the

 * time and architecture-dependent hardware counter values in

 * nanoseconds at the on-time PPS signal transition.

 *

 * Note that, on some Unix systems this routine runs at an interrupt

 * priority level higher than the timer interrupt routine hardclock().

 * Therefore, the variables used are distinct from the hardclock()

 * variables, except for the actual time and frequency variables, which

 * are determined by this routine and updated atomically.

 */

void

hardpps(tsp, nsec)

	struct timespec *tsp;	/* time at PPS */

	long nsec;		/* hardware counter at PPS */

{

	long u_sec, u_nsec, v_nsec; /* temps */

	l_fp ftemp;

	/*

	 * The signal is first processed by a range gate and frequency

	 * discriminator. The range gate rejects noise spikes outside

	 * the range +-500 us. The frequency discriminator rejects input

	 * signals with apparent frequency outside the range 1 +-500

	 * PPM. If two hits occur in the same second, we ignore the

	 * later hit; if not and a hit occurs outside the range gate,

	 * keep the later hit for later comparison, but do not process

	 * it.

	 */

	time_status |= STA_PPSSIGNAL | STA_PPSJITTER;

	time_status &= ~(STA_PPSWANDER | STA_PPSERROR);

	pps_valid = PPS_VALID;

	u_sec = tsp->tv_sec;

	u_nsec = tsp->tv_nsec;

	if (u_nsec >= (NANOSECOND >> 1)) {

		u_nsec -= NANOSECOND;

		u_sec++;

	}

	v_nsec = u_nsec - pps_tf[0].tv_nsec;

	if (u_sec == pps_tf[0].tv_sec && v_nsec < NANOSECOND -

	    MAXFREQ)

		return;

	pps_tf[2] = pps_tf[1];

	pps_tf[1] = pps_tf[0];

	pps_tf[0].tv_sec = u_sec;

	pps_tf[0].tv_nsec = u_nsec;

	/*

	 * Compute the difference between the current and previous

	 * counter values. If the difference exceeds 0.5 s, assume it

	 * has wrapped around, so correct 1.0 s. If the result exceeds

	 * the tick interval, the sample point has crossed a tick

	 * boundary during the last second, so correct the tick. Very

	 * intricate.

	 */

	u_nsec = nsec;

	if (u_nsec > (NANOSECOND >> 1))

		u_nsec -= NANOSECOND;

	else if (u_nsec < -(NANOSECOND >> 1))

		u_nsec += NANOSECOND;

	pps_fcount += u_nsec;

	if (v_nsec > MAXFREQ || v_nsec < -MAXFREQ)

		return;

	time_status &= ~STA_PPSJITTER;

	/*

	 * A three-stage median filter is used to help denoise the PPS

	 * time. The median sample becomes the time offset estimate; the

	 * difference between the other two samples becomes the time

	 * dispersion (jitter) estimate.

	 */

	if (pps_tf[0].tv_nsec > pps_tf[1].tv_nsec) {

		if (pps_tf[1].tv_nsec > pps_tf[2].tv_nsec) {

			v_nsec = pps_tf[1].tv_nsec;	/* 0 1 2 */

			u_nsec = pps_tf[0].tv_nsec - pps_tf[2].tv_nsec;

		} else if (pps_tf[2].tv_nsec > pps_tf[0].tv_nsec) {

			v_nsec = pps_tf[0].tv_nsec;	/* 2 0 1 */

			u_nsec = pps_tf[2].tv_nsec - pps_tf[1].tv_nsec;

		} else {

			v_nsec = pps_tf[2].tv_nsec;	/* 0 2 1 */

			u_nsec = pps_tf[0].tv_nsec - pps_tf[1].tv_nsec;

		}

	} else {

		if (pps_tf[1].tv_nsec < pps_tf[2].tv_nsec) {

			v_nsec = pps_tf[1].tv_nsec;	/* 2 1 0 */

			u_nsec = pps_tf[2].tv_nsec - pps_tf[0].tv_nsec;

		} else if (pps_tf[2].tv_nsec < pps_tf[0].tv_nsec) {

			v_nsec = pps_tf[0].tv_nsec;	/* 1 0 2 */

			u_nsec = pps_tf[1].tv_nsec - pps_tf[2].tv_nsec;

		} else {

			v_nsec = pps_tf[2].tv_nsec;	/* 1 2 0 */

			u_nsec = pps_tf[1].tv_nsec - pps_tf[0].tv_nsec;

		}

	}

	/*

	 * Nominal jitter is due to PPS signal noise and interrupt

	 * latency. If it exceeds the popcorn threshold, the sample is

	 * discarded. otherwise, if so enabled, the time offset is

	 * updated. We can tolerate a modest loss of data here without

	 * much degrading time accuracy.

	 */

	if (u_nsec > (pps_jitter << PPS_POPCORN)) {

		time_status |= STA_PPSJITTER;

		pps_jitcnt++;

	} else if (time_status & STA_PPSTIME) {

		time_monitor = -v_nsec;

		L_LINT(time_offset, time_monitor);

	}

	pps_jitter += (u_nsec - pps_jitter) >> PPS_FAVG;

	u_sec = pps_tf[0].tv_sec - pps_lastsec;

	if (u_sec < (1 << pps_shift))

		return;

	/*

	 * At the end of the calibration interval the difference between

	 * the first and last counter values becomes the scaled

	 * frequency. It will later be divided by the length of the

	 * interval to determine the frequency update. If the frequency

	 * exceeds a sanity threshold, or if the actual calibration

	 * interval is not equal to the expected length, the data are

	 * discarded. We can tolerate a modest loss of data here without

	 * much degrading frequency accuracy.

	 */

	pps_calcnt++;

	v_nsec = -pps_fcount;

	pps_lastsec = pps_tf[0].tv_sec;

	pps_fcount = 0;

	u_nsec = MAXFREQ << pps_shift;

	if (v_nsec > u_nsec || v_nsec < -u_nsec || u_sec != (1 <<

	    pps_shift)) {

		time_status |= STA_PPSERROR;

		pps_errcnt++;

		return;

	}

	/*

	 * Here the raw frequency offset and wander (stability) is

	 * calculated. If the wander is less than the wander threshold

	 * for four consecutive averaging intervals, the interval is

	 * doubled; if it is greater than the threshold for four

	 * consecutive intervals, the interval is halved. The scaled

	 * frequency offset is converted to frequency offset. The

	 * stability metric is calculated as the average of recent

	 * frequency changes, but is used only for performance

	 * monitoring.

	 */

	L_LINT(ftemp, v_nsec);

	L_RSHIFT(ftemp, pps_shift);

	L_SUB(ftemp, pps_freq);

	u_nsec = L_GINT(ftemp);

	if (u_nsec > PPS_MAXWANDER) {

		L_LINT(ftemp, PPS_MAXWANDER);

		pps_intcnt--;

		time_status |= STA_PPSWANDER;

		pps_stbcnt++;

	} else if (u_nsec < -PPS_MAXWANDER) {

		L_LINT(ftemp, -PPS_MAXWANDER);

		pps_intcnt--;

		time_status |= STA_PPSWANDER;

		pps_stbcnt++;

	} else {

		pps_intcnt++;

	}

	if (pps_intcnt >= 4) {

		pps_intcnt = 4;

		if (pps_shift < pps_shiftmax) {

			pps_shift++;

			pps_intcnt = 0;

		}

	} else if (pps_intcnt <= -4 || pps_shift > pps_shiftmax) {

		pps_intcnt = -4;

		if (pps_shift > PPS_FAVG) {

			pps_shift--;

			pps_intcnt = 0;

		}

	}

	if (u_nsec < 0)

		u_nsec = -u_nsec;

	pps_stabil += (u_nsec * SCALE_PPM - pps_stabil) >> PPS_FAVG;

	/*

	 * The PPS frequency is recalculated and clamped to the maximum

	 * MAXFREQ. If enabled, the system clock frequency is updated as

	 * well.

	 */

	L_ADD(pps_freq, ftemp);

	u_nsec = L_GINT(pps_freq);

	if (u_nsec > MAXFREQ)

		L_LINT(pps_freq, MAXFREQ);

	else if (u_nsec < -MAXFREQ)

		L_LINT(pps_freq, -MAXFREQ);

	if (time_status & STA_PPSFREQ)

		time_freq = pps_freq;

}

#endif /* PPS_SYNC */

#ifndef _SYS_SYSPROTO_H_

struct adjtime_args {

	struct timeval *delta;

	struct timeval *olddelta;

};

#endif

/*

 * MPSAFE

 */

/* ARGSUSED */

int

adjtime(struct thread *td, struct adjtime_args *uap)

{

	struct timeval delta, olddelta, *deltap;

	int error;

	if (uap->delta) {

		error = copyin(uap->delta, &delta, sizeof(delta));

		if (error)

			return (error);

		deltap = δ

	} else

		deltap = NULL;

	error = kern_adjtime(td, deltap, &olddelta);

	if (uap->olddelta && error == 0)

		error = copyout(&olddelta, uap->olddelta, sizeof(olddelta));

	return (error);

}

int

kern_adjtime(struct thread *td, struct timeval *delta, struct timeval *olddelta)

{

	struct timeval atv;

	int error = 0;

#ifdef MAC

	error = mac_check_system_settime(td->td_ucred);

	if (error)

		return (error);

#endif

	if (!cf_jailadjtime && jailed(td->td_ucred))

		return (EPERM);

	if (!cf_useradjtime && (error = suser_cred(td->td_ucred, SUSER_ALLOWJAIL)) != 0)

		return (error);                          /* jail is already checked */

	mtx_lock(&Giant);

	if (olddelta) {

		atv.tv_sec = time_adjtime / 1000000;

		atv.tv_usec = time_adjtime % 1000000;

		if (atv.tv_usec < 0) {

			atv.tv_usec += 1000000;

			atv.tv_sec--;

		}

		*olddelta = atv;

	}

	if (delta)

		time_adjtime = (int64_t)delta->tv_sec * 1000000 +

		    delta->tv_usec;

	mtx_unlock(&Giant);

	return (error);

}