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kern_clock.c revision 1.114.2.1
      1 /*	$NetBSD: kern_clock.c,v 1.114.2.1 2007/12/26 19:57:07 ad Exp $	*/
      2 
      3 /*-
      4  * Copyright (c) 2000, 2004, 2006, 2007 The NetBSD Foundation, Inc.
      5  * All rights reserved.
      6  *
      7  * This code is derived from software contributed to The NetBSD Foundation
      8  * by Jason R. Thorpe of the Numerical Aerospace Simulation Facility,
      9  * NASA Ames Research Center.
     10  * This code is derived from software contributed to The NetBSD Foundation
     11  * by Charles M. Hannum.
     12  *
     13  * Redistribution and use in source and binary forms, with or without
     14  * modification, are permitted provided that the following conditions
     15  * are met:
     16  * 1. Redistributions of source code must retain the above copyright
     17  *    notice, this list of conditions and the following disclaimer.
     18  * 2. Redistributions in binary form must reproduce the above copyright
     19  *    notice, this list of conditions and the following disclaimer in the
     20  *    documentation and/or other materials provided with the distribution.
     21  * 3. All advertising materials mentioning features or use of this software
     22  *    must display the following acknowledgement:
     23  *	This product includes software developed by the NetBSD
     24  *	Foundation, Inc. and its contributors.
     25  * 4. Neither the name of The NetBSD Foundation nor the names of its
     26  *    contributors may be used to endorse or promote products derived
     27  *    from this software without specific prior written permission.
     28  *
     29  * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
     30  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
     31  * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
     32  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
     33  * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
     34  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
     35  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
     36  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
     37  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
     38  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
     39  * POSSIBILITY OF SUCH DAMAGE.
     40  */
     41 
     42 /*-
     43  * Copyright (c) 1982, 1986, 1991, 1993
     44  *	The Regents of the University of California.  All rights reserved.
     45  * (c) UNIX System Laboratories, Inc.
     46  * All or some portions of this file are derived from material licensed
     47  * to the University of California by American Telephone and Telegraph
     48  * Co. or Unix System Laboratories, Inc. and are reproduced herein with
     49  * the permission of UNIX System Laboratories, Inc.
     50  *
     51  * Redistribution and use in source and binary forms, with or without
     52  * modification, are permitted provided that the following conditions
     53  * are met:
     54  * 1. Redistributions of source code must retain the above copyright
     55  *    notice, this list of conditions and the following disclaimer.
     56  * 2. Redistributions in binary form must reproduce the above copyright
     57  *    notice, this list of conditions and the following disclaimer in the
     58  *    documentation and/or other materials provided with the distribution.
     59  * 3. Neither the name of the University nor the names of its contributors
     60  *    may be used to endorse or promote products derived from this software
     61  *    without specific prior written permission.
     62  *
     63  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
     64  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     65  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     66  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
     67  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     68  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     69  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     70  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     71  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     72  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     73  * SUCH DAMAGE.
     74  *
     75  *	@(#)kern_clock.c	8.5 (Berkeley) 1/21/94
     76  */
     77 
     78 #include <sys/cdefs.h>
     79 __KERNEL_RCSID(0, "$NetBSD: kern_clock.c,v 1.114.2.1 2007/12/26 19:57:07 ad Exp $");
     80 
     81 #include "opt_ntp.h"
     82 #include "opt_multiprocessor.h"
     83 #include "opt_perfctrs.h"
     84 
     85 #include <sys/param.h>
     86 #include <sys/systm.h>
     87 #include <sys/callout.h>
     88 #include <sys/kernel.h>
     89 #include <sys/proc.h>
     90 #include <sys/resourcevar.h>
     91 #include <sys/signalvar.h>
     92 #include <sys/sysctl.h>
     93 #include <sys/timex.h>
     94 #include <sys/sched.h>
     95 #include <sys/time.h>
     96 #include <sys/timetc.h>
     97 #include <sys/cpu.h>
     98 
     99 #ifdef GPROF
    100 #include <sys/gmon.h>
    101 #endif
    102 
    103 /*
    104  * Clock handling routines.
    105  *
    106  * This code is written to operate with two timers that run independently of
    107  * each other.  The main clock, running hz times per second, is used to keep
    108  * track of real time.  The second timer handles kernel and user profiling,
    109  * and does resource use estimation.  If the second timer is programmable,
    110  * it is randomized to avoid aliasing between the two clocks.  For example,
    111  * the randomization prevents an adversary from always giving up the CPU
    112  * just before its quantum expires.  Otherwise, it would never accumulate
    113  * CPU ticks.  The mean frequency of the second timer is stathz.
    114  *
    115  * If no second timer exists, stathz will be zero; in this case we drive
    116  * profiling and statistics off the main clock.  This WILL NOT be accurate;
    117  * do not do it unless absolutely necessary.
    118  *
    119  * The statistics clock may (or may not) be run at a higher rate while
    120  * profiling.  This profile clock runs at profhz.  We require that profhz
    121  * be an integral multiple of stathz.
    122  *
    123  * If the statistics clock is running fast, it must be divided by the ratio
    124  * profhz/stathz for statistics.  (For profiling, every tick counts.)
    125  */
    126 
    127 #ifndef __HAVE_TIMECOUNTER
    128 #ifdef NTP	/* NTP phase-locked loop in kernel */
    129 /*
    130  * Phase/frequency-lock loop (PLL/FLL) definitions
    131  *
    132  * The following variables are read and set by the ntp_adjtime() system
    133  * call.
    134  *
    135  * time_state shows the state of the system clock, with values defined
    136  * in the timex.h header file.
    137  *
    138  * time_status shows the status of the system clock, with bits defined
    139  * in the timex.h header file.
    140  *
    141  * time_offset is used by the PLL/FLL to adjust the system time in small
    142  * increments.
    143  *
    144  * time_constant determines the bandwidth or "stiffness" of the PLL.
    145  *
    146  * time_tolerance determines maximum frequency error or tolerance of the
    147  * CPU clock oscillator and is a property of the architecture; however,
    148  * in principle it could change as result of the presence of external
    149  * discipline signals, for instance.
    150  *
    151  * time_precision is usually equal to the kernel tick variable; however,
    152  * in cases where a precision clock counter or external clock is
    153  * available, the resolution can be much less than this and depend on
    154  * whether the external clock is working or not.
    155  *
    156  * time_maxerror is initialized by a ntp_adjtime() call and increased by
    157  * the kernel once each second to reflect the maximum error bound
    158  * growth.
    159  *
    160  * time_esterror is set and read by the ntp_adjtime() call, but
    161  * otherwise not used by the kernel.
    162  */
    163 int time_state = TIME_OK;	/* clock state */
    164 int time_status = STA_UNSYNC;	/* clock status bits */
    165 long time_offset = 0;		/* time offset (us) */
    166 long time_constant = 0;		/* pll time constant */
    167 long time_tolerance = MAXFREQ;	/* frequency tolerance (scaled ppm) */
    168 long time_precision = 1;	/* clock precision (us) */
    169 long time_maxerror = MAXPHASE;	/* maximum error (us) */
    170 long time_esterror = MAXPHASE;	/* estimated error (us) */
    171 
    172 /*
    173  * The following variables establish the state of the PLL/FLL and the
    174  * residual time and frequency offset of the local clock. The scale
    175  * factors are defined in the timex.h header file.
    176  *
    177  * time_phase and time_freq are the phase increment and the frequency
    178  * increment, respectively, of the kernel time variable.
    179  *
    180  * time_freq is set via ntp_adjtime() from a value stored in a file when
    181  * the synchronization daemon is first started. Its value is retrieved
    182  * via ntp_adjtime() and written to the file about once per hour by the
    183  * daemon.
    184  *
    185  * time_adj is the adjustment added to the value of tick at each timer
    186  * interrupt and is recomputed from time_phase and time_freq at each
    187  * seconds rollover.
    188  *
    189  * time_reftime is the second's portion of the system time at the last
    190  * call to ntp_adjtime(). It is used to adjust the time_freq variable
    191  * and to increase the time_maxerror as the time since last update
    192  * increases.
    193  */
    194 long time_phase = 0;		/* phase offset (scaled us) */
    195 long time_freq = 0;		/* frequency offset (scaled ppm) */
    196 long time_adj = 0;		/* tick adjust (scaled 1 / hz) */
    197 long time_reftime = 0;		/* time at last adjustment (s) */
    198 
    199 #ifdef PPS_SYNC
    200 /*
    201  * The following variables are used only if the kernel PPS discipline
    202  * code is configured (PPS_SYNC). The scale factors are defined in the
    203  * timex.h header file.
    204  *
    205  * pps_time contains the time at each calibration interval, as read by
    206  * microtime(). pps_count counts the seconds of the calibration
    207  * interval, the duration of which is nominally pps_shift in powers of
    208  * two.
    209  *
    210  * pps_offset is the time offset produced by the time median filter
    211  * pps_tf[], while pps_jitter is the dispersion (jitter) measured by
    212  * this filter.
    213  *
    214  * pps_freq is the frequency offset produced by the frequency median
    215  * filter pps_ff[], while pps_stabil is the dispersion (wander) measured
    216  * by this filter.
    217  *
    218  * pps_usec is latched from a high resolution counter or external clock
    219  * at pps_time. Here we want the hardware counter contents only, not the
    220  * contents plus the time_tv.usec as usual.
    221  *
    222  * pps_valid counts the number of seconds since the last PPS update. It
    223  * is used as a watchdog timer to disable the PPS discipline should the
    224  * PPS signal be lost.
    225  *
    226  * pps_glitch counts the number of seconds since the beginning of an
    227  * offset burst more than tick/2 from current nominal offset. It is used
    228  * mainly to suppress error bursts due to priority conflicts between the
    229  * PPS interrupt and timer interrupt.
    230  *
    231  * pps_intcnt counts the calibration intervals for use in the interval-
    232  * adaptation algorithm. It's just too complicated for words.
    233  *
    234  * pps_kc_hardpps_source contains an arbitrary value that uniquely
    235  * identifies the currently bound source of the PPS signal, or NULL
    236  * if no source is bound.
    237  *
    238  * pps_kc_hardpps_mode indicates which transitions, if any, of the PPS
    239  * signal should be reported.
    240  */
    241 struct timeval pps_time;	/* kernel time at last interval */
    242 long pps_tf[] = {0, 0, 0};	/* pps time offset median filter (us) */
    243 long pps_offset = 0;		/* pps time offset (us) */
    244 long pps_jitter = MAXTIME;	/* time dispersion (jitter) (us) */
    245 long pps_ff[] = {0, 0, 0};	/* pps frequency offset median filter */
    246 long pps_freq = 0;		/* frequency offset (scaled ppm) */
    247 long pps_stabil = MAXFREQ;	/* frequency dispersion (scaled ppm) */
    248 long pps_usec = 0;		/* microsec counter at last interval */
    249 long pps_valid = PPS_VALID;	/* pps signal watchdog counter */
    250 int pps_glitch = 0;		/* pps signal glitch counter */
    251 int pps_count = 0;		/* calibration interval counter (s) */
    252 int pps_shift = PPS_SHIFT;	/* interval duration (s) (shift) */
    253 int pps_intcnt = 0;		/* intervals at current duration */
    254 void *pps_kc_hardpps_source = NULL; /* current PPS supplier's identifier */
    255 int pps_kc_hardpps_mode = 0;	/* interesting edges of PPS signal */
    256 
    257 /*
    258  * PPS signal quality monitors
    259  *
    260  * pps_jitcnt counts the seconds that have been discarded because the
    261  * jitter measured by the time median filter exceeds the limit MAXTIME
    262  * (100 us).
    263  *
    264  * pps_calcnt counts the frequency calibration intervals, which are
    265  * variable from 4 s to 256 s.
    266  *
    267  * pps_errcnt counts the calibration intervals which have been discarded
    268  * because the wander exceeds the limit MAXFREQ (100 ppm) or where the
    269  * calibration interval jitter exceeds two ticks.
    270  *
    271  * pps_stbcnt counts the calibration intervals that have been discarded
    272  * because the frequency wander exceeds the limit MAXFREQ / 4 (25 us).
    273  */
    274 long pps_jitcnt = 0;		/* jitter limit exceeded */
    275 long pps_calcnt = 0;		/* calibration intervals */
    276 long pps_errcnt = 0;		/* calibration errors */
    277 long pps_stbcnt = 0;		/* stability limit exceeded */
    278 #endif /* PPS_SYNC */
    279 
    280 #ifdef EXT_CLOCK
    281 /*
    282  * External clock definitions
    283  *
    284  * The following definitions and declarations are used only if an
    285  * external clock is configured on the system.
    286  */
    287 #define CLOCK_INTERVAL 30	/* CPU clock update interval (s) */
    288 
    289 /*
    290  * The clock_count variable is set to CLOCK_INTERVAL at each PPS
    291  * interrupt and decremented once each second.
    292  */
    293 int clock_count = 0;		/* CPU clock counter */
    294 
    295 #endif /* EXT_CLOCK */
    296 #endif /* NTP */
    297 
    298 /*
    299  * Bump a timeval by a small number of usec's.
    300  */
    301 #define BUMPTIME(t, usec) { \
    302 	volatile struct timeval *tp = (t); \
    303 	long us; \
    304  \
    305 	tp->tv_usec = us = tp->tv_usec + (usec); \
    306 	if (us >= 1000000) { \
    307 		tp->tv_usec = us - 1000000; \
    308 		tp->tv_sec++; \
    309 	} \
    310 }
    311 #endif /* !__HAVE_TIMECOUNTER */
    312 
    313 int	stathz;
    314 int	profhz;
    315 int	profsrc;
    316 int	schedhz;
    317 int	profprocs;
    318 int	hardclock_ticks;
    319 static int hardscheddiv; /* hard => sched divider (used if schedhz == 0) */
    320 static int psdiv;			/* prof => stat divider */
    321 int	psratio;			/* ratio: prof / stat */
    322 #ifndef __HAVE_TIMECOUNTER
    323 int	tickfix, tickfixinterval;	/* used if tick not really integral */
    324 #ifndef NTP
    325 static int tickfixcnt;			/* accumulated fractional error */
    326 #else
    327 int	fixtick;			/* used by NTP for same */
    328 int	shifthz;
    329 #endif
    330 
    331 /*
    332  * We might want ldd to load the both words from time at once.
    333  * To succeed we need to be quadword aligned.
    334  * The sparc already does that, and that it has worked so far is a fluke.
    335  */
    336 volatile struct	timeval time  __attribute__((__aligned__(__alignof__(quad_t))));
    337 volatile struct	timeval mono_time;
    338 #endif /* !__HAVE_TIMECOUNTER */
    339 
    340 #ifdef __HAVE_TIMECOUNTER
    341 static u_int get_intr_timecount(struct timecounter *);
    342 
    343 static struct timecounter intr_timecounter = {
    344 	get_intr_timecount,	/* get_timecount */
    345 	0,			/* no poll_pps */
    346 	~0u,			/* counter_mask */
    347 	0,		        /* frequency */
    348 	"clockinterrupt",	/* name */
    349 	0,			/* quality - minimum implementation level for a clock */
    350 	NULL,			/* prev */
    351 	NULL,			/* next */
    352 };
    353 
    354 static u_int
    355 get_intr_timecount(struct timecounter *tc)
    356 {
    357 
    358 	return (u_int)hardclock_ticks;
    359 }
    360 #endif
    361 
    362 /*
    363  * Initialize clock frequencies and start both clocks running.
    364  */
    365 void
    366 initclocks(void)
    367 {
    368 	int i;
    369 
    370 	/*
    371 	 * Set divisors to 1 (normal case) and let the machine-specific
    372 	 * code do its bit.
    373 	 */
    374 	psdiv = 1;
    375 #ifdef __HAVE_TIMECOUNTER
    376 	/*
    377 	 * provide minimum default time counter
    378 	 * will only run at interrupt resolution
    379 	 */
    380 	intr_timecounter.tc_frequency = hz;
    381 	tc_init(&intr_timecounter);
    382 #endif
    383 	cpu_initclocks();
    384 
    385 	/*
    386 	 * Compute profhz and stathz, fix profhz if needed.
    387 	 */
    388 	i = stathz ? stathz : hz;
    389 	if (profhz == 0)
    390 		profhz = i;
    391 	psratio = profhz / i;
    392 	if (schedhz == 0) {
    393 		/* 16Hz is best */
    394 		hardscheddiv = hz / 16;
    395 		if (hardscheddiv <= 0)
    396 			panic("hardscheddiv");
    397 	}
    398 
    399 #ifndef __HAVE_TIMECOUNTER
    400 #ifdef NTP
    401 	switch (hz) {
    402 	case 1:
    403 		shifthz = SHIFT_SCALE - 0;
    404 		break;
    405 	case 2:
    406 		shifthz = SHIFT_SCALE - 1;
    407 		break;
    408 	case 4:
    409 		shifthz = SHIFT_SCALE - 2;
    410 		break;
    411 	case 8:
    412 		shifthz = SHIFT_SCALE - 3;
    413 		break;
    414 	case 16:
    415 		shifthz = SHIFT_SCALE - 4;
    416 		break;
    417 	case 32:
    418 		shifthz = SHIFT_SCALE - 5;
    419 		break;
    420 	case 50:
    421 	case 60:
    422 	case 64:
    423 		shifthz = SHIFT_SCALE - 6;
    424 		break;
    425 	case 96:
    426 	case 100:
    427 	case 128:
    428 		shifthz = SHIFT_SCALE - 7;
    429 		break;
    430 	case 256:
    431 		shifthz = SHIFT_SCALE - 8;
    432 		break;
    433 	case 512:
    434 		shifthz = SHIFT_SCALE - 9;
    435 		break;
    436 	case 1000:
    437 	case 1024:
    438 		shifthz = SHIFT_SCALE - 10;
    439 		break;
    440 	case 1200:
    441 	case 2048:
    442 		shifthz = SHIFT_SCALE - 11;
    443 		break;
    444 	case 4096:
    445 		shifthz = SHIFT_SCALE - 12;
    446 		break;
    447 	case 8192:
    448 		shifthz = SHIFT_SCALE - 13;
    449 		break;
    450 	case 16384:
    451 		shifthz = SHIFT_SCALE - 14;
    452 		break;
    453 	case 32768:
    454 		shifthz = SHIFT_SCALE - 15;
    455 		break;
    456 	case 65536:
    457 		shifthz = SHIFT_SCALE - 16;
    458 		break;
    459 	default:
    460 		panic("weird hz");
    461 	}
    462 	if (fixtick == 0) {
    463 		/*
    464 		 * Give MD code a chance to set this to a better
    465 		 * value; but, if it doesn't, we should.
    466 		 */
    467 		fixtick = (1000000 - (hz*tick));
    468 	}
    469 #endif /* NTP */
    470 #endif /* !__HAVE_TIMECOUNTER */
    471 }
    472 
    473 /*
    474  * The real-time timer, interrupting hz times per second.
    475  */
    476 void
    477 hardclock(struct clockframe *frame)
    478 {
    479 	struct lwp *l;
    480 	struct proc *p;
    481 	struct cpu_info *ci = curcpu();
    482 	struct ptimer *pt;
    483 #ifndef __HAVE_TIMECOUNTER
    484 	int delta;
    485 	extern int tickdelta;
    486 	extern long timedelta;
    487 #ifdef NTP
    488 	int time_update;
    489 	int ltemp;
    490 #endif /* NTP */
    491 #endif /* __HAVE_TIMECOUNTER */
    492 
    493 	l = ci->ci_data.cpu_onproc;
    494 	if (!CURCPU_IDLE_P()) {
    495 		p = l->l_proc;
    496 		/*
    497 		 * Run current process's virtual and profile time, as needed.
    498 		 */
    499 		if (CLKF_USERMODE(frame) && p->p_timers &&
    500 		    (pt = LIST_FIRST(&p->p_timers->pts_virtual)) != NULL)
    501 			if (itimerdecr(pt, tick) == 0)
    502 				itimerfire(pt);
    503 		if (p->p_timers &&
    504 		    (pt = LIST_FIRST(&p->p_timers->pts_prof)) != NULL)
    505 			if (itimerdecr(pt, tick) == 0)
    506 				itimerfire(pt);
    507 	}
    508 
    509 	/*
    510 	 * If no separate statistics clock is available, run it from here.
    511 	 */
    512 	if (stathz == 0)
    513 		statclock(frame);
    514 	/*
    515 	 * If no separate schedclock is provided, call it here
    516 	 * at about 16 Hz.
    517 	 */
    518 	if (schedhz == 0) {
    519 		if ((int)(--ci->ci_schedstate.spc_schedticks) <= 0) {
    520 			schedclock(l);
    521 			ci->ci_schedstate.spc_schedticks = hardscheddiv;
    522 		}
    523 	}
    524 	if ((--ci->ci_schedstate.spc_ticks) <= 0)
    525 		sched_tick(ci);
    526 
    527 #if defined(MULTIPROCESSOR)
    528 	/*
    529 	 * If we are not the primary CPU, we're not allowed to do
    530 	 * any more work.
    531 	 */
    532 	if (CPU_IS_PRIMARY(ci) == 0)
    533 		return;
    534 #endif
    535 
    536 	hardclock_ticks++;
    537 
    538 #ifdef __HAVE_TIMECOUNTER
    539 	tc_ticktock();
    540 #else /* __HAVE_TIMECOUNTER */
    541 	/*
    542 	 * Increment the time-of-day.  The increment is normally just
    543 	 * ``tick''.  If the machine is one which has a clock frequency
    544 	 * such that ``hz'' would not divide the second evenly into
    545 	 * milliseconds, a periodic adjustment must be applied.  Finally,
    546 	 * if we are still adjusting the time (see adjtime()),
    547 	 * ``tickdelta'' may also be added in.
    548 	 */
    549 	delta = tick;
    550 
    551 #ifndef NTP
    552 	if (tickfix) {
    553 		tickfixcnt += tickfix;
    554 		if (tickfixcnt >= tickfixinterval) {
    555 			delta++;
    556 			tickfixcnt -= tickfixinterval;
    557 		}
    558 	}
    559 #endif /* !NTP */
    560 	/* Imprecise 4bsd adjtime() handling */
    561 	if (timedelta != 0) {
    562 		delta += tickdelta;
    563 		timedelta -= tickdelta;
    564 	}
    565 
    566 #ifdef notyet
    567 	microset();
    568 #endif
    569 
    570 #ifndef NTP
    571 	BUMPTIME(&time, delta);		/* XXX Now done using NTP code below */
    572 #endif
    573 	BUMPTIME(&mono_time, delta);
    574 
    575 #ifdef NTP
    576 	time_update = delta;
    577 
    578 	/*
    579 	 * Compute the phase adjustment. If the low-order bits
    580 	 * (time_phase) of the update overflow, bump the high-order bits
    581 	 * (time_update).
    582 	 */
    583 	time_phase += time_adj;
    584 	if (time_phase <= -FINEUSEC) {
    585 		ltemp = -time_phase >> SHIFT_SCALE;
    586 		time_phase += ltemp << SHIFT_SCALE;
    587 		time_update -= ltemp;
    588 	} else if (time_phase >= FINEUSEC) {
    589 		ltemp = time_phase >> SHIFT_SCALE;
    590 		time_phase -= ltemp << SHIFT_SCALE;
    591 		time_update += ltemp;
    592 	}
    593 	time.tv_usec += time_update;
    594 
    595 	/*
    596 	 * On rollover of the second the phase adjustment to be used for
    597 	 * the next second is calculated. Also, the maximum error is
    598 	 * increased by the tolerance. If the PPS frequency discipline
    599 	 * code is present, the phase is increased to compensate for the
    600 	 * CPU clock oscillator frequency error.
    601 	 *
    602  	 * On a 32-bit machine and given parameters in the timex.h
    603 	 * header file, the maximum phase adjustment is +-512 ms and
    604 	 * maximum frequency offset is a tad less than) +-512 ppm. On a
    605 	 * 64-bit machine, you shouldn't need to ask.
    606 	 */
    607 	if (time.tv_usec >= 1000000) {
    608 		time.tv_usec -= 1000000;
    609 		time.tv_sec++;
    610 		time_maxerror += time_tolerance >> SHIFT_USEC;
    611 
    612 		/*
    613 		 * Leap second processing. If in leap-insert state at
    614 		 * the end of the day, the system clock is set back one
    615 		 * second; if in leap-delete state, the system clock is
    616 		 * set ahead one second. The microtime() routine or
    617 		 * external clock driver will insure that reported time
    618 		 * is always monotonic. The ugly divides should be
    619 		 * replaced.
    620 		 */
    621 		switch (time_state) {
    622 		case TIME_OK:
    623 			if (time_status & STA_INS)
    624 				time_state = TIME_INS;
    625 			else if (time_status & STA_DEL)
    626 				time_state = TIME_DEL;
    627 			break;
    628 
    629 		case TIME_INS:
    630 			if (time.tv_sec % 86400 == 0) {
    631 				time.tv_sec--;
    632 				time_state = TIME_OOP;
    633 			}
    634 			break;
    635 
    636 		case TIME_DEL:
    637 			if ((time.tv_sec + 1) % 86400 == 0) {
    638 				time.tv_sec++;
    639 				time_state = TIME_WAIT;
    640 			}
    641 			break;
    642 
    643 		case TIME_OOP:
    644 			time_state = TIME_WAIT;
    645 			break;
    646 
    647 		case TIME_WAIT:
    648 			if (!(time_status & (STA_INS | STA_DEL)))
    649 				time_state = TIME_OK;
    650 			break;
    651 		}
    652 
    653 		/*
    654 		 * Compute the phase adjustment for the next second. In
    655 		 * PLL mode, the offset is reduced by a fixed factor
    656 		 * times the time constant. In FLL mode the offset is
    657 		 * used directly. In either mode, the maximum phase
    658 		 * adjustment for each second is clamped so as to spread
    659 		 * the adjustment over not more than the number of
    660 		 * seconds between updates.
    661 		 */
    662 		if (time_offset < 0) {
    663 			ltemp = -time_offset;
    664 			if (!(time_status & STA_FLL))
    665 				ltemp >>= SHIFT_KG + time_constant;
    666 			if (ltemp > (MAXPHASE / MINSEC) << SHIFT_UPDATE)
    667 				ltemp = (MAXPHASE / MINSEC) <<
    668 				    SHIFT_UPDATE;
    669 			time_offset += ltemp;
    670 			time_adj = -ltemp << (shifthz - SHIFT_UPDATE);
    671 		} else if (time_offset > 0) {
    672 			ltemp = time_offset;
    673 			if (!(time_status & STA_FLL))
    674 				ltemp >>= SHIFT_KG + time_constant;
    675 			if (ltemp > (MAXPHASE / MINSEC) << SHIFT_UPDATE)
    676 				ltemp = (MAXPHASE / MINSEC) <<
    677 				    SHIFT_UPDATE;
    678 			time_offset -= ltemp;
    679 			time_adj = ltemp << (shifthz - SHIFT_UPDATE);
    680 		} else
    681 			time_adj = 0;
    682 
    683 		/*
    684 		 * Compute the frequency estimate and additional phase
    685 		 * adjustment due to frequency error for the next
    686 		 * second. When the PPS signal is engaged, gnaw on the
    687 		 * watchdog counter and update the frequency computed by
    688 		 * the pll and the PPS signal.
    689 		 */
    690 #ifdef PPS_SYNC
    691 		pps_valid++;
    692 		if (pps_valid == PPS_VALID) {
    693 			pps_jitter = MAXTIME;
    694 			pps_stabil = MAXFREQ;
    695 			time_status &= ~(STA_PPSSIGNAL | STA_PPSJITTER |
    696 			    STA_PPSWANDER | STA_PPSERROR);
    697 		}
    698 		ltemp = time_freq + pps_freq;
    699 #else
    700 		ltemp = time_freq;
    701 #endif /* PPS_SYNC */
    702 
    703 		if (ltemp < 0)
    704 			time_adj -= -ltemp >> (SHIFT_USEC - shifthz);
    705 		else
    706 			time_adj += ltemp >> (SHIFT_USEC - shifthz);
    707 		time_adj += (long)fixtick << shifthz;
    708 
    709 		/*
    710 		 * When the CPU clock oscillator frequency is not a
    711 		 * power of 2 in Hz, shifthz is only an approximate
    712 		 * scale factor.
    713 		 *
    714 		 * To determine the adjustment, you can do the following:
    715 		 *   bc -q
    716 		 *   scale=24
    717 		 *   obase=2
    718 		 *   idealhz/realhz
    719 		 * where `idealhz' is the next higher power of 2, and `realhz'
    720 		 * is the actual value.  You may need to factor this result
    721 		 * into a sequence of 2 multipliers to get better precision.
    722 		 *
    723 		 * Likewise, the error can be calculated with (e.g. for 100Hz):
    724 		 *   bc -q
    725 		 *   scale=24
    726 		 *   ((1+2^-2+2^-5)*(1-2^-10)*realhz-idealhz)/idealhz
    727 		 * (and then multiply by 1000000 to get ppm).
    728 		 */
    729 		switch (hz) {
    730 		case 60:
    731 			/* A factor of 1.000100010001 gives about 15ppm
    732 			   error. */
    733 			if (time_adj < 0) {
    734 				time_adj -= (-time_adj >> 4);
    735 				time_adj -= (-time_adj >> 8);
    736 			} else {
    737 				time_adj += (time_adj >> 4);
    738 				time_adj += (time_adj >> 8);
    739 			}
    740 			break;
    741 
    742 		case 96:
    743 			/* A factor of 1.0101010101 gives about 244ppm error. */
    744 			if (time_adj < 0) {
    745 				time_adj -= (-time_adj >> 2);
    746 				time_adj -= (-time_adj >> 4) + (-time_adj >> 8);
    747 			} else {
    748 				time_adj += (time_adj >> 2);
    749 				time_adj += (time_adj >> 4) + (time_adj >> 8);
    750 			}
    751 			break;
    752 
    753 		case 50:
    754 		case 100:
    755 			/* A factor of 1.010001111010111 gives about 1ppm
    756 			   error. */
    757 			if (time_adj < 0) {
    758 				time_adj -= (-time_adj >> 2) + (-time_adj >> 5);
    759 				time_adj += (-time_adj >> 10);
    760 			} else {
    761 				time_adj += (time_adj >> 2) + (time_adj >> 5);
    762 				time_adj -= (time_adj >> 10);
    763 			}
    764 			break;
    765 
    766 		case 1000:
    767 			/* A factor of 1.000001100010100001 gives about 50ppm
    768 			   error. */
    769 			if (time_adj < 0) {
    770 				time_adj -= (-time_adj >> 6) + (-time_adj >> 11);
    771 				time_adj -= (-time_adj >> 7);
    772 			} else {
    773 				time_adj += (time_adj >> 6) + (time_adj >> 11);
    774 				time_adj += (time_adj >> 7);
    775 			}
    776 			break;
    777 
    778 		case 1200:
    779 			/* A factor of 1.1011010011100001 gives about 64ppm
    780 			   error. */
    781 			if (time_adj < 0) {
    782 				time_adj -= (-time_adj >> 1) + (-time_adj >> 6);
    783 				time_adj -= (-time_adj >> 3) + (-time_adj >> 10);
    784 			} else {
    785 				time_adj += (time_adj >> 1) + (time_adj >> 6);
    786 				time_adj += (time_adj >> 3) + (time_adj >> 10);
    787 			}
    788 			break;
    789 		}
    790 
    791 #ifdef EXT_CLOCK
    792 		/*
    793 		 * If an external clock is present, it is necessary to
    794 		 * discipline the kernel time variable anyway, since not
    795 		 * all system components use the microtime() interface.
    796 		 * Here, the time offset between the external clock and
    797 		 * kernel time variable is computed every so often.
    798 		 */
    799 		clock_count++;
    800 		if (clock_count > CLOCK_INTERVAL) {
    801 			clock_count = 0;
    802 			microtime(&clock_ext);
    803 			delta.tv_sec = clock_ext.tv_sec - time.tv_sec;
    804 			delta.tv_usec = clock_ext.tv_usec -
    805 			    time.tv_usec;
    806 			if (delta.tv_usec < 0)
    807 				delta.tv_sec--;
    808 			if (delta.tv_usec >= 500000) {
    809 				delta.tv_usec -= 1000000;
    810 				delta.tv_sec++;
    811 			}
    812 			if (delta.tv_usec < -500000) {
    813 				delta.tv_usec += 1000000;
    814 				delta.tv_sec--;
    815 			}
    816 			if (delta.tv_sec > 0 || (delta.tv_sec == 0 &&
    817 			    delta.tv_usec > MAXPHASE) ||
    818 			    delta.tv_sec < -1 || (delta.tv_sec == -1 &&
    819 			    delta.tv_usec < -MAXPHASE)) {
    820 				time = clock_ext;
    821 				delta.tv_sec = 0;
    822 				delta.tv_usec = 0;
    823 			}
    824 			hardupdate(delta.tv_usec);
    825 		}
    826 #endif /* EXT_CLOCK */
    827 	}
    828 
    829 #endif /* NTP */
    830 #endif /* !__HAVE_TIMECOUNTER */
    831 
    832 	/*
    833 	 * Update real-time timeout queue.  Callouts are processed at a
    834 	 * very low CPU priority, so we don't keep the relatively high
    835 	 * clock interrupt priority any longer than necessary.
    836 	 */
    837 	callout_hardclock();
    838 }
    839 
    840 /*
    841  * Start profiling on a process.
    842  *
    843  * Kernel profiling passes proc0 which never exits and hence
    844  * keeps the profile clock running constantly.
    845  */
    846 void
    847 startprofclock(struct proc *p)
    848 {
    849 
    850 	KASSERT(mutex_owned(&p->p_stmutex));
    851 
    852 	if ((p->p_stflag & PST_PROFIL) == 0) {
    853 		p->p_stflag |= PST_PROFIL;
    854 		/*
    855 		 * This is only necessary if using the clock as the
    856 		 * profiling source.
    857 		 */
    858 		if (++profprocs == 1 && stathz != 0)
    859 			psdiv = psratio;
    860 	}
    861 }
    862 
    863 /*
    864  * Stop profiling on a process.
    865  */
    866 void
    867 stopprofclock(struct proc *p)
    868 {
    869 
    870 	KASSERT(mutex_owned(&p->p_stmutex));
    871 
    872 	if (p->p_stflag & PST_PROFIL) {
    873 		p->p_stflag &= ~PST_PROFIL;
    874 		/*
    875 		 * This is only necessary if using the clock as the
    876 		 * profiling source.
    877 		 */
    878 		if (--profprocs == 0 && stathz != 0)
    879 			psdiv = 1;
    880 	}
    881 }
    882 
    883 #if defined(PERFCTRS)
    884 /*
    885  * Independent profiling "tick" in case we're using a separate
    886  * clock or profiling event source.  Currently, that's just
    887  * performance counters--hence the wrapper.
    888  */
    889 void
    890 proftick(struct clockframe *frame)
    891 {
    892 #ifdef GPROF
    893         struct gmonparam *g;
    894         intptr_t i;
    895 #endif
    896 	struct lwp *l;
    897 	struct proc *p;
    898 
    899 	l = curcpu()->ci_data.cpu_onproc;
    900 	p = (l ? l->l_proc : NULL);
    901 	if (CLKF_USERMODE(frame)) {
    902 		mutex_spin_enter(&p->p_stmutex);
    903 		if (p->p_stflag & PST_PROFIL)
    904 			addupc_intr(l, CLKF_PC(frame));
    905 		mutex_spin_exit(&p->p_stmutex);
    906 	} else {
    907 #ifdef GPROF
    908 		g = &_gmonparam;
    909 		if (g->state == GMON_PROF_ON) {
    910 			i = CLKF_PC(frame) - g->lowpc;
    911 			if (i < g->textsize) {
    912 				i /= HISTFRACTION * sizeof(*g->kcount);
    913 				g->kcount[i]++;
    914 			}
    915 		}
    916 #endif
    917 #ifdef LWP_PC
    918 		if (p != NULL && (p->p_stflag & PST_PROFIL) != 0)
    919 			addupc_intr(l, LWP_PC(l));
    920 #endif
    921 	}
    922 }
    923 #endif
    924 
    925 void
    926 schedclock(struct lwp *l)
    927 {
    928 
    929 	if ((l->l_flag & LW_IDLE) != 0)
    930 		return;
    931 
    932 	sched_schedclock(l);
    933 }
    934 
    935 /*
    936  * Statistics clock.  Grab profile sample, and if divider reaches 0,
    937  * do process and kernel statistics.
    938  */
    939 void
    940 statclock(struct clockframe *frame)
    941 {
    942 #ifdef GPROF
    943 	struct gmonparam *g;
    944 	intptr_t i;
    945 #endif
    946 	struct cpu_info *ci = curcpu();
    947 	struct schedstate_percpu *spc = &ci->ci_schedstate;
    948 	struct proc *p;
    949 	struct lwp *l;
    950 
    951 	/*
    952 	 * Notice changes in divisor frequency, and adjust clock
    953 	 * frequency accordingly.
    954 	 */
    955 	if (spc->spc_psdiv != psdiv) {
    956 		spc->spc_psdiv = psdiv;
    957 		spc->spc_pscnt = psdiv;
    958 		if (psdiv == 1) {
    959 			setstatclockrate(stathz);
    960 		} else {
    961 			setstatclockrate(profhz);
    962 		}
    963 	}
    964 	l = ci->ci_data.cpu_onproc;
    965 	if ((l->l_flag & LW_IDLE) != 0) {
    966 		/*
    967 		 * don't account idle lwps as swapper.
    968 		 */
    969 		p = NULL;
    970 	} else {
    971 		p = l->l_proc;
    972 		mutex_spin_enter(&p->p_stmutex);
    973 	}
    974 
    975 	if (CLKF_USERMODE(frame)) {
    976 		if ((p->p_stflag & PST_PROFIL) && profsrc == PROFSRC_CLOCK)
    977 			addupc_intr(l, CLKF_PC(frame));
    978 		if (--spc->spc_pscnt > 0) {
    979 			mutex_spin_exit(&p->p_stmutex);
    980 			return;
    981 		}
    982 
    983 		/*
    984 		 * Came from user mode; CPU was in user state.
    985 		 * If this process is being profiled record the tick.
    986 		 */
    987 		p->p_uticks++;
    988 		if (p->p_nice > NZERO)
    989 			spc->spc_cp_time[CP_NICE]++;
    990 		else
    991 			spc->spc_cp_time[CP_USER]++;
    992 	} else {
    993 #ifdef GPROF
    994 		/*
    995 		 * Kernel statistics are just like addupc_intr, only easier.
    996 		 */
    997 		g = &_gmonparam;
    998 		if (profsrc == PROFSRC_CLOCK && g->state == GMON_PROF_ON) {
    999 			i = CLKF_PC(frame) - g->lowpc;
   1000 			if (i < g->textsize) {
   1001 				i /= HISTFRACTION * sizeof(*g->kcount);
   1002 				g->kcount[i]++;
   1003 			}
   1004 		}
   1005 #endif
   1006 #ifdef LWP_PC
   1007 		if (p != NULL && profsrc == PROFSRC_CLOCK &&
   1008 		    (p->p_stflag & PST_PROFIL)) {
   1009 			addupc_intr(l, LWP_PC(l));
   1010 		}
   1011 #endif
   1012 		if (--spc->spc_pscnt > 0) {
   1013 			if (p != NULL)
   1014 				mutex_spin_exit(&p->p_stmutex);
   1015 			return;
   1016 		}
   1017 		/*
   1018 		 * Came from kernel mode, so we were:
   1019 		 * - handling an interrupt,
   1020 		 * - doing syscall or trap work on behalf of the current
   1021 		 *   user process, or
   1022 		 * - spinning in the idle loop.
   1023 		 * Whichever it is, charge the time as appropriate.
   1024 		 * Note that we charge interrupts to the current process,
   1025 		 * regardless of whether they are ``for'' that process,
   1026 		 * so that we know how much of its real time was spent
   1027 		 * in ``non-process'' (i.e., interrupt) work.
   1028 		 */
   1029 		if (CLKF_INTR(frame) || (curlwp->l_pflag & LP_INTR) != 0) {
   1030 			if (p != NULL) {
   1031 				p->p_iticks++;
   1032 			}
   1033 			spc->spc_cp_time[CP_INTR]++;
   1034 		} else if (p != NULL) {
   1035 			p->p_sticks++;
   1036 			spc->spc_cp_time[CP_SYS]++;
   1037 		} else {
   1038 			spc->spc_cp_time[CP_IDLE]++;
   1039 		}
   1040 	}
   1041 	spc->spc_pscnt = psdiv;
   1042 
   1043 	if (p != NULL) {
   1044 		++l->l_cpticks;
   1045 		mutex_spin_exit(&p->p_stmutex);
   1046 	}
   1047 }
   1048 
   1049 #ifndef __HAVE_TIMECOUNTER
   1050 #ifdef NTP	/* NTP phase-locked loop in kernel */
   1051 /*
   1052  * hardupdate() - local clock update
   1053  *
   1054  * This routine is called by ntp_adjtime() to update the local clock
   1055  * phase and frequency. The implementation is of an adaptive-parameter,
   1056  * hybrid phase/frequency-lock loop (PLL/FLL). The routine computes new
   1057  * time and frequency offset estimates for each call. If the kernel PPS
   1058  * discipline code is configured (PPS_SYNC), the PPS signal itself
   1059  * determines the new time offset, instead of the calling argument.
   1060  * Presumably, calls to ntp_adjtime() occur only when the caller
   1061  * believes the local clock is valid within some bound (+-128 ms with
   1062  * NTP). If the caller's time is far different than the PPS time, an
   1063  * argument will ensue, and it's not clear who will lose.
   1064  *
   1065  * For uncompensated quartz crystal oscillatores and nominal update
   1066  * intervals less than 1024 s, operation should be in phase-lock mode
   1067  * (STA_FLL = 0), where the loop is disciplined to phase. For update
   1068  * intervals greater than thiss, operation should be in frequency-lock
   1069  * mode (STA_FLL = 1), where the loop is disciplined to frequency.
   1070  *
   1071  * Note: splclock() is in effect.
   1072  */
   1073 void
   1074 hardupdate(long offset)
   1075 {
   1076 	long ltemp, mtemp;
   1077 
   1078 	if (!(time_status & STA_PLL) && !(time_status & STA_PPSTIME))
   1079 		return;
   1080 	ltemp = offset;
   1081 #ifdef PPS_SYNC
   1082 	if (time_status & STA_PPSTIME && time_status & STA_PPSSIGNAL)
   1083 		ltemp = pps_offset;
   1084 #endif /* PPS_SYNC */
   1085 
   1086 	/*
   1087 	 * Scale the phase adjustment and clamp to the operating range.
   1088 	 */
   1089 	if (ltemp > MAXPHASE)
   1090 		time_offset = MAXPHASE << SHIFT_UPDATE;
   1091 	else if (ltemp < -MAXPHASE)
   1092 		time_offset = -(MAXPHASE << SHIFT_UPDATE);
   1093 	else
   1094 		time_offset = ltemp << SHIFT_UPDATE;
   1095 
   1096 	/*
   1097 	 * Select whether the frequency is to be controlled and in which
   1098 	 * mode (PLL or FLL). Clamp to the operating range. Ugly
   1099 	 * multiply/divide should be replaced someday.
   1100 	 */
   1101 	if (time_status & STA_FREQHOLD || time_reftime == 0)
   1102 		time_reftime = time.tv_sec;
   1103 	mtemp = time.tv_sec - time_reftime;
   1104 	time_reftime = time.tv_sec;
   1105 	if (time_status & STA_FLL) {
   1106 		if (mtemp >= MINSEC) {
   1107 			ltemp = ((time_offset / mtemp) << (SHIFT_USEC -
   1108 			    SHIFT_UPDATE));
   1109 			if (ltemp < 0)
   1110 				time_freq -= -ltemp >> SHIFT_KH;
   1111 			else
   1112 				time_freq += ltemp >> SHIFT_KH;
   1113 		}
   1114 	} else {
   1115 		if (mtemp < MAXSEC) {
   1116 			ltemp *= mtemp;
   1117 			if (ltemp < 0)
   1118 				time_freq -= -ltemp >> (time_constant +
   1119 				    time_constant + SHIFT_KF -
   1120 				    SHIFT_USEC);
   1121 			else
   1122 				time_freq += ltemp >> (time_constant +
   1123 				    time_constant + SHIFT_KF -
   1124 				    SHIFT_USEC);
   1125 		}
   1126 	}
   1127 	if (time_freq > time_tolerance)
   1128 		time_freq = time_tolerance;
   1129 	else if (time_freq < -time_tolerance)
   1130 		time_freq = -time_tolerance;
   1131 }
   1132 
   1133 #ifdef PPS_SYNC
   1134 /*
   1135  * hardpps() - discipline CPU clock oscillator to external PPS signal
   1136  *
   1137  * This routine is called at each PPS interrupt in order to discipline
   1138  * the CPU clock oscillator to the PPS signal. It measures the PPS phase
   1139  * and leaves it in a handy spot for the hardclock() routine. It
   1140  * integrates successive PPS phase differences and calculates the
   1141  * frequency offset. This is used in hardclock() to discipline the CPU
   1142  * clock oscillator so that intrinsic frequency error is cancelled out.
   1143  * The code requires the caller to capture the time and hardware counter
   1144  * value at the on-time PPS signal transition.
   1145  *
   1146  * Note that, on some Unix systems, this routine runs at an interrupt
   1147  * priority level higher than the timer interrupt routine hardclock().
   1148  * Therefore, the variables used are distinct from the hardclock()
   1149  * variables, except for certain exceptions: The PPS frequency pps_freq
   1150  * and phase pps_offset variables are determined by this routine and
   1151  * updated atomically. The time_tolerance variable can be considered a
   1152  * constant, since it is infrequently changed, and then only when the
   1153  * PPS signal is disabled. The watchdog counter pps_valid is updated
   1154  * once per second by hardclock() and is atomically cleared in this
   1155  * routine.
   1156  */
   1157 void
   1158 hardpps(struct timeval *tvp,		/* time at PPS */
   1159 	long usec			/* hardware counter at PPS */)
   1160 {
   1161 	long u_usec, v_usec, bigtick;
   1162 	long cal_sec, cal_usec;
   1163 
   1164 	/*
   1165 	 * An occasional glitch can be produced when the PPS interrupt
   1166 	 * occurs in the hardclock() routine before the time variable is
   1167 	 * updated. Here the offset is discarded when the difference
   1168 	 * between it and the last one is greater than tick/2, but not
   1169 	 * if the interval since the first discard exceeds 30 s.
   1170 	 */
   1171 	time_status |= STA_PPSSIGNAL;
   1172 	time_status &= ~(STA_PPSJITTER | STA_PPSWANDER | STA_PPSERROR);
   1173 	pps_valid = 0;
   1174 	u_usec = -tvp->tv_usec;
   1175 	if (u_usec < -500000)
   1176 		u_usec += 1000000;
   1177 	v_usec = pps_offset - u_usec;
   1178 	if (v_usec < 0)
   1179 		v_usec = -v_usec;
   1180 	if (v_usec > (tick >> 1)) {
   1181 		if (pps_glitch > MAXGLITCH) {
   1182 			pps_glitch = 0;
   1183 			pps_tf[2] = u_usec;
   1184 			pps_tf[1] = u_usec;
   1185 		} else {
   1186 			pps_glitch++;
   1187 			u_usec = pps_offset;
   1188 		}
   1189 	} else
   1190 		pps_glitch = 0;
   1191 
   1192 	/*
   1193 	 * A three-stage median filter is used to help deglitch the pps
   1194 	 * time. The median sample becomes the time offset estimate; the
   1195 	 * difference between the other two samples becomes the time
   1196 	 * dispersion (jitter) estimate.
   1197 	 */
   1198 	pps_tf[2] = pps_tf[1];
   1199 	pps_tf[1] = pps_tf[0];
   1200 	pps_tf[0] = u_usec;
   1201 	if (pps_tf[0] > pps_tf[1]) {
   1202 		if (pps_tf[1] > pps_tf[2]) {
   1203 			pps_offset = pps_tf[1];		/* 0 1 2 */
   1204 			v_usec = pps_tf[0] - pps_tf[2];
   1205 		} else if (pps_tf[2] > pps_tf[0]) {
   1206 			pps_offset = pps_tf[0];		/* 2 0 1 */
   1207 			v_usec = pps_tf[2] - pps_tf[1];
   1208 		} else {
   1209 			pps_offset = pps_tf[2];		/* 0 2 1 */
   1210 			v_usec = pps_tf[0] - pps_tf[1];
   1211 		}
   1212 	} else {
   1213 		if (pps_tf[1] < pps_tf[2]) {
   1214 			pps_offset = pps_tf[1];		/* 2 1 0 */
   1215 			v_usec = pps_tf[2] - pps_tf[0];
   1216 		} else  if (pps_tf[2] < pps_tf[0]) {
   1217 			pps_offset = pps_tf[0];		/* 1 0 2 */
   1218 			v_usec = pps_tf[1] - pps_tf[2];
   1219 		} else {
   1220 			pps_offset = pps_tf[2];		/* 1 2 0 */
   1221 			v_usec = pps_tf[1] - pps_tf[0];
   1222 		}
   1223 	}
   1224 	if (v_usec > MAXTIME)
   1225 		pps_jitcnt++;
   1226 	v_usec = (v_usec << PPS_AVG) - pps_jitter;
   1227 	if (v_usec < 0)
   1228 		pps_jitter -= -v_usec >> PPS_AVG;
   1229 	else
   1230 		pps_jitter += v_usec >> PPS_AVG;
   1231 	if (pps_jitter > (MAXTIME >> 1))
   1232 		time_status |= STA_PPSJITTER;
   1233 
   1234 	/*
   1235 	 * During the calibration interval adjust the starting time when
   1236 	 * the tick overflows. At the end of the interval compute the
   1237 	 * duration of the interval and the difference of the hardware
   1238 	 * counters at the beginning and end of the interval. This code
   1239 	 * is deliciously complicated by the fact valid differences may
   1240 	 * exceed the value of tick when using long calibration
   1241 	 * intervals and small ticks. Note that the counter can be
   1242 	 * greater than tick if caught at just the wrong instant, but
   1243 	 * the values returned and used here are correct.
   1244 	 */
   1245 	bigtick = (long)tick << SHIFT_USEC;
   1246 	pps_usec -= pps_freq;
   1247 	if (pps_usec >= bigtick)
   1248 		pps_usec -= bigtick;
   1249 	if (pps_usec < 0)
   1250 		pps_usec += bigtick;
   1251 	pps_time.tv_sec++;
   1252 	pps_count++;
   1253 	if (pps_count < (1 << pps_shift))
   1254 		return;
   1255 	pps_count = 0;
   1256 	pps_calcnt++;
   1257 	u_usec = usec << SHIFT_USEC;
   1258 	v_usec = pps_usec - u_usec;
   1259 	if (v_usec >= bigtick >> 1)
   1260 		v_usec -= bigtick;
   1261 	if (v_usec < -(bigtick >> 1))
   1262 		v_usec += bigtick;
   1263 	if (v_usec < 0)
   1264 		v_usec = -(-v_usec >> pps_shift);
   1265 	else
   1266 		v_usec = v_usec >> pps_shift;
   1267 	pps_usec = u_usec;
   1268 	cal_sec = tvp->tv_sec;
   1269 	cal_usec = tvp->tv_usec;
   1270 	cal_sec -= pps_time.tv_sec;
   1271 	cal_usec -= pps_time.tv_usec;
   1272 	if (cal_usec < 0) {
   1273 		cal_usec += 1000000;
   1274 		cal_sec--;
   1275 	}
   1276 	pps_time = *tvp;
   1277 
   1278 	/*
   1279 	 * Check for lost interrupts, noise, excessive jitter and
   1280 	 * excessive frequency error. The number of timer ticks during
   1281 	 * the interval may vary +-1 tick. Add to this a margin of one
   1282 	 * tick for the PPS signal jitter and maximum frequency
   1283 	 * deviation. If the limits are exceeded, the calibration
   1284 	 * interval is reset to the minimum and we start over.
   1285 	 */
   1286 	u_usec = (long)tick << 1;
   1287 	if (!((cal_sec == -1 && cal_usec > (1000000 - u_usec))
   1288 	    || (cal_sec == 0 && cal_usec < u_usec))
   1289 	    || v_usec > time_tolerance || v_usec < -time_tolerance) {
   1290 		pps_errcnt++;
   1291 		pps_shift = PPS_SHIFT;
   1292 		pps_intcnt = 0;
   1293 		time_status |= STA_PPSERROR;
   1294 		return;
   1295 	}
   1296 
   1297 	/*
   1298 	 * A three-stage median filter is used to help deglitch the pps
   1299 	 * frequency. The median sample becomes the frequency offset
   1300 	 * estimate; the difference between the other two samples
   1301 	 * becomes the frequency dispersion (stability) estimate.
   1302 	 */
   1303 	pps_ff[2] = pps_ff[1];
   1304 	pps_ff[1] = pps_ff[0];
   1305 	pps_ff[0] = v_usec;
   1306 	if (pps_ff[0] > pps_ff[1]) {
   1307 		if (pps_ff[1] > pps_ff[2]) {
   1308 			u_usec = pps_ff[1];		/* 0 1 2 */
   1309 			v_usec = pps_ff[0] - pps_ff[2];
   1310 		} else if (pps_ff[2] > pps_ff[0]) {
   1311 			u_usec = pps_ff[0];		/* 2 0 1 */
   1312 			v_usec = pps_ff[2] - pps_ff[1];
   1313 		} else {
   1314 			u_usec = pps_ff[2];		/* 0 2 1 */
   1315 			v_usec = pps_ff[0] - pps_ff[1];
   1316 		}
   1317 	} else {
   1318 		if (pps_ff[1] < pps_ff[2]) {
   1319 			u_usec = pps_ff[1];		/* 2 1 0 */
   1320 			v_usec = pps_ff[2] - pps_ff[0];
   1321 		} else  if (pps_ff[2] < pps_ff[0]) {
   1322 			u_usec = pps_ff[0];		/* 1 0 2 */
   1323 			v_usec = pps_ff[1] - pps_ff[2];
   1324 		} else {
   1325 			u_usec = pps_ff[2];		/* 1 2 0 */
   1326 			v_usec = pps_ff[1] - pps_ff[0];
   1327 		}
   1328 	}
   1329 
   1330 	/*
   1331 	 * Here the frequency dispersion (stability) is updated. If it
   1332 	 * is less than one-fourth the maximum (MAXFREQ), the frequency
   1333 	 * offset is updated as well, but clamped to the tolerance. It
   1334 	 * will be processed later by the hardclock() routine.
   1335 	 */
   1336 	v_usec = (v_usec >> 1) - pps_stabil;
   1337 	if (v_usec < 0)
   1338 		pps_stabil -= -v_usec >> PPS_AVG;
   1339 	else
   1340 		pps_stabil += v_usec >> PPS_AVG;
   1341 	if (pps_stabil > MAXFREQ >> 2) {
   1342 		pps_stbcnt++;
   1343 		time_status |= STA_PPSWANDER;
   1344 		return;
   1345 	}
   1346 	if (time_status & STA_PPSFREQ) {
   1347 		if (u_usec < 0) {
   1348 			pps_freq -= -u_usec >> PPS_AVG;
   1349 			if (pps_freq < -time_tolerance)
   1350 				pps_freq = -time_tolerance;
   1351 			u_usec = -u_usec;
   1352 		} else {
   1353 			pps_freq += u_usec >> PPS_AVG;
   1354 			if (pps_freq > time_tolerance)
   1355 				pps_freq = time_tolerance;
   1356 		}
   1357 	}
   1358 
   1359 	/*
   1360 	 * Here the calibration interval is adjusted. If the maximum
   1361 	 * time difference is greater than tick / 4, reduce the interval
   1362 	 * by half. If this is not the case for four consecutive
   1363 	 * intervals, double the interval.
   1364 	 */
   1365 	if (u_usec << pps_shift > bigtick >> 2) {
   1366 		pps_intcnt = 0;
   1367 		if (pps_shift > PPS_SHIFT)
   1368 			pps_shift--;
   1369 	} else if (pps_intcnt >= 4) {
   1370 		pps_intcnt = 0;
   1371 		if (pps_shift < PPS_SHIFTMAX)
   1372 			pps_shift++;
   1373 	} else
   1374 		pps_intcnt++;
   1375 }
   1376 #endif /* PPS_SYNC */
   1377 #endif /* NTP  */
   1378 
   1379 /* timecounter compat functions */
   1380 void
   1381 binuptime(struct bintime *bt)
   1382 {
   1383 	struct timeval tv;
   1384 
   1385 	microuptime(&tv);
   1386 	timeval2bintime(&tv, bt);
   1387 }
   1388 
   1389 void
   1390 nanouptime(struct timespec *tsp)
   1391 {
   1392 	struct timeval tv;
   1393 
   1394 	microuptime(&tv);
   1395 	TIMEVAL_TO_TIMESPEC(&mono_time, tsp);
   1396 }
   1397 
   1398 void
   1399 microuptime(struct timeval *tv)
   1400 {
   1401 	struct timeval t;
   1402 	int s;
   1403 
   1404 	/* microtime + time - mono_time */
   1405 	microtime(&t);
   1406 	s = splclock();
   1407 	timeradd(&t, &time, &t);
   1408 	timersub(&t, &mono_time, &t);
   1409 	splx(s);
   1410 }
   1411 
   1412 void
   1413 bintime(struct bintime *bt)
   1414 {
   1415 	struct timeval tv;
   1416 
   1417 	microtime(&tv);
   1418 	timeval2bintime(&tv, bt);
   1419 }
   1420 
   1421 void
   1422 nanotime(struct timespec *ts)
   1423 {
   1424 	struct timeval tv;
   1425 
   1426 	microtime(&tv);
   1427 	TIMEVAL_TO_TIMESPEC(&tv, ts);
   1428 }
   1429 
   1430 void
   1431 getbinuptime(struct bintime *bt)
   1432 {
   1433 	int s;
   1434 
   1435 	s = splclock();
   1436 	timeval2bintime(__UNVOLATILE(&mono_time), bt);
   1437 	splx(s);
   1438 }
   1439 
   1440 void
   1441 getnanouptime(struct timespec *tsp)
   1442 {
   1443 	int s;
   1444 
   1445 	s = splclock();
   1446 	TIMEVAL_TO_TIMESPEC(&mono_time, tsp);
   1447 	splx(s);
   1448 }
   1449 
   1450 void
   1451 getmicrouptime(struct timeval *tvp)
   1452 {
   1453 	int s;
   1454 
   1455 	s = splclock();
   1456 	*tvp = mono_time;
   1457 	splx(s);
   1458 }
   1459 
   1460 void
   1461 getbintime(struct bintime *bt)
   1462 {
   1463 	int s;
   1464 
   1465 	s = splclock();
   1466 	timeval2bintime(__UNVOLATILE(&time), bt);
   1467 	splx(s);
   1468 }
   1469 
   1470 void
   1471 getnanotime(struct timespec *tsp)
   1472 {
   1473 	int s;
   1474 
   1475 	s = splclock();
   1476 	TIMEVAL_TO_TIMESPEC(&time, tsp);
   1477 	splx(s);
   1478 }
   1479 
   1480 void
   1481 getmicrotime(struct timeval *tvp)
   1482 {
   1483 	int s;
   1484 
   1485 	s = splclock();
   1486 	*tvp = time;
   1487 	splx(s);
   1488 }
   1489 
   1490 u_int64_t
   1491 tc_getfrequency(void)
   1492 {
   1493 	return hz;
   1494 }
   1495 
   1496 void
   1497 tc_setclock(struct timespec *ts)
   1498 {
   1499 	struct timeval tv;
   1500 
   1501 	TIMESPEC_TO_TIMEVAL(&tv, ts);
   1502 	time = tv;
   1503 }
   1504 #endif /* !__HAVE_TIMECOUNTER */
   1505