text: /*-
   * ----------------------------------------------------------------------------
   * "THE BEER-WARE LICENSE" (Revision 42):
   * <phk@FreeBSD.ORG> wrote this file.  As long as you retain this notice you
   * can do whatever you want with this stuff. If we meet some day, and you think
   * this stuff is worth it, you can buy me a beer in return.   Poul-Henning Kamp
   * ----------------------------------------------------------------------------
   */
  
  #include <sys/cdefs.h>
  __FBSDID("$FreeBSD: releng/9.3/sys/kern/kern_tc.c 248085 2013-03-09 02:36:32Z marius $");
  
  #include "opt_compat.h"
  #include "opt_ntp.h"
  
  #include <sys/param.h>
  #include <sys/kernel.h>
  #include <sys/sysctl.h>
  #include <sys/syslog.h>
  #include <sys/systm.h>
  #include <sys/timepps.h>
  #include <sys/timetc.h>
  #include <sys/timex.h>
  #include <sys/vdso.h>
  
  /*
   * A large step happens on boot.  This constant detects such steps.
   * It is relatively small so that ntp_update_second gets called enough
   * in the typical 'missed a couple of seconds' case, but doesn't loop
   * forever when the time step is large.
   */
  #define LARGE_STEP	200
  
  /*
   * Implement a dummy timecounter which we can use until we get a real one
   * in the air.  This allows the console and other early stuff to use
   * time services.
   */
  
  static u_int
  dummy_get_timecount(struct timecounter *tc)
  {
  	static u_int now;
  
  	return (++now);
  }
  
  static struct timecounter dummy_timecounter = {
  	dummy_get_timecount, 0, ~0u, 1000000, "dummy", -1000000
  };
  
  struct timehands {
  	/* These fields must be initialized by the driver. */
  	struct timecounter	*th_counter;
  	int64_t			th_adjustment;
  	uint64_t		th_scale;
  	u_int	 		th_offset_count;
  	struct bintime		th_offset;
  	struct timeval		th_microtime;
  	struct timespec		th_nanotime;
  	/* Fields not to be copied in tc_windup start with th_generation. */
  	volatile u_int		th_generation;
  	struct timehands	*th_next;
  };
  
  static struct timehands th0;
  static struct timehands th9 = { NULL, 0, 0, 0, {0, 0}, {0, 0}, {0, 0}, 0, &th0};
  static struct timehands th8 = { NULL, 0, 0, 0, {0, 0}, {0, 0}, {0, 0}, 0, &th9};
  static struct timehands th7 = { NULL, 0, 0, 0, {0, 0}, {0, 0}, {0, 0}, 0, &th8};
  static struct timehands th6 = { NULL, 0, 0, 0, {0, 0}, {0, 0}, {0, 0}, 0, &th7};
  static struct timehands th5 = { NULL, 0, 0, 0, {0, 0}, {0, 0}, {0, 0}, 0, &th6};
  static struct timehands th4 = { NULL, 0, 0, 0, {0, 0}, {0, 0}, {0, 0}, 0, &th5};
  static struct timehands th3 = { NULL, 0, 0, 0, {0, 0}, {0, 0}, {0, 0}, 0, &th4};
  static struct timehands th2 = { NULL, 0, 0, 0, {0, 0}, {0, 0}, {0, 0}, 0, &th3};
  static struct timehands th1 = { NULL, 0, 0, 0, {0, 0}, {0, 0}, {0, 0}, 0, &th2};
  static struct timehands th0 = {
  	&dummy_timecounter,
  	0,
  	(uint64_t)-1 / 1000000,
  	0,
  	{1, 0},
  	{0, 0},
  	{0, 0},
  	1,
  	&th1
  };
  
  static struct timehands *volatile timehands = &th0;
  struct timecounter *timecounter = &dummy_timecounter;
  static struct timecounter *timecounters = &dummy_timecounter;
  
  int tc_min_ticktock_freq = 1;
  
  volatile time_t time_second = 1;
  volatile time_t time_uptime = 1;
  
  struct bintime boottimebin;
  struct timeval boottime;
  static int sysctl_kern_boottime(SYSCTL_HANDLER_ARGS);
  SYSCTL_PROC(_kern, KERN_BOOTTIME, boottime, CTLTYPE_STRUCT|CTLFLAG_RD,
      NULL, 0, sysctl_kern_boottime, "S,timeval", "System boottime");
  
  SYSCTL_NODE(_kern, OID_AUTO, timecounter, CTLFLAG_RW, 0, "");
  static SYSCTL_NODE(_kern_timecounter, OID_AUTO, tc, CTLFLAG_RW, 0, "");
  
  static int timestepwarnings;
  SYSCTL_INT(_kern_timecounter, OID_AUTO, stepwarnings, CTLFLAG_RW,
      &timestepwarnings, 0, "Log time steps");
  
  static void tc_windup(void);
  static void cpu_tick_calibrate(int);
  
  void dtrace_getnanotime(struct timespec *tsp);
  
  static int
  sysctl_kern_boottime(SYSCTL_HANDLER_ARGS)
  {
  #ifdef SCTL_MASK32
  	int tv[2];
  
  	if (req->flags & SCTL_MASK32) {
  		tv[0] = boottime.tv_sec;
  		tv[1] = boottime.tv_usec;
  		return SYSCTL_OUT(req, tv, sizeof(tv));
  	} else
  #endif
  		return SYSCTL_OUT(req, &boottime, sizeof(boottime));
  }
  
  static int
  sysctl_kern_timecounter_get(SYSCTL_HANDLER_ARGS)
  {
  	u_int ncount;
  	struct timecounter *tc = arg1;
  
  	ncount = tc->tc_get_timecount(tc);
  	return sysctl_handle_int(oidp, &ncount, 0, req);
  }
  
  static int
  sysctl_kern_timecounter_freq(SYSCTL_HANDLER_ARGS)
  {
  	uint64_t freq;
  	struct timecounter *tc = arg1;
  
  	freq = tc->tc_frequency;
  	return sysctl_handle_64(oidp, &freq, 0, req);
  }
  
  /*
   * Return the difference between the timehands' counter value now and what
   * was when we copied it to the timehands' offset_count.
   */
  static __inline u_int
  tc_delta(struct timehands *th)
  {
  	struct timecounter *tc;
  
  	tc = th->th_counter;
  	return ((tc->tc_get_timecount(tc) - th->th_offset_count) &
  	    tc->tc_counter_mask);
  }
  
  /*
   * Functions for reading the time.  We have to loop until we are sure that
   * the timehands that we operated on was not updated under our feet.  See
   * the comment in <sys/time.h> for a description of these 12 functions.
   */
  
  void
  binuptime(struct bintime *bt)
  {
  	struct timehands *th;
  	u_int gen;
  
  	do {
  		th = timehands;
  		gen = th->th_generation;
  		*bt = th->th_offset;
  		bintime_addx(bt, th->th_scale * tc_delta(th));
  	} while (gen == 0 || gen != th->th_generation);
  }
  
  void
  nanouptime(struct timespec *tsp)
  {
  	struct bintime bt;
  
  	binuptime(&bt);
  	bintime2timespec(&bt, tsp);
  }
  
  void
  microuptime(struct timeval *tvp)
  {
  	struct bintime bt;
  
  	binuptime(&bt);
  	bintime2timeval(&bt, tvp);
  }
  
  void
  bintime(struct bintime *bt)
  {
  
  	binuptime(bt);
  	bintime_add(bt, &boottimebin);
  }
  
  void
  nanotime(struct timespec *tsp)
  {
  	struct bintime bt;
  
  	bintime(&bt);
  	bintime2timespec(&bt, tsp);
  }
  
  void
  microtime(struct timeval *tvp)
  {
  	struct bintime bt;
  
  	bintime(&bt);
  	bintime2timeval(&bt, tvp);
  }
  
  void
  getbinuptime(struct bintime *bt)
  {
  	struct timehands *th;
  	u_int gen;
  
  	do {
  		th = timehands;
  		gen = th->th_generation;
  		*bt = th->th_offset;
  	} while (gen == 0 || gen != th->th_generation);
  }
  
  void
  getnanouptime(struct timespec *tsp)
  {
  	struct timehands *th;
  	u_int gen;
  
  	do {
  		th = timehands;
  		gen = th->th_generation;
  		bintime2timespec(&th->th_offset, tsp);
  	} while (gen == 0 || gen != th->th_generation);
  }
  
  void
  getmicrouptime(struct timeval *tvp)
  {
  	struct timehands *th;
  	u_int gen;
  
  	do {
  		th = timehands;
  		gen = th->th_generation;
  		bintime2timeval(&th->th_offset, tvp);
  	} while (gen == 0 || gen != th->th_generation);
  }
  
  void
  getbintime(struct bintime *bt)
  {
  	struct timehands *th;
  	u_int gen;
  
  	do {
  		th = timehands;
  		gen = th->th_generation;
  		*bt = th->th_offset;
  	} while (gen == 0 || gen != th->th_generation);
  	bintime_add(bt, &boottimebin);
  }
  
  void
  getnanotime(struct timespec *tsp)
  {
  	struct timehands *th;
  	u_int gen;
  
  	do {
  		th = timehands;
  		gen = th->th_generation;
  		*tsp = th->th_nanotime;
  	} while (gen == 0 || gen != th->th_generation);
  }
  
  void
  getmicrotime(struct timeval *tvp)
  {
  	struct timehands *th;
  	u_int gen;
  
  	do {
  		th = timehands;
  		gen = th->th_generation;
  		*tvp = th->th_microtime;
  	} while (gen == 0 || gen != th->th_generation);
  }
  
  /*
   * This is a clone of getnanotime and used for walltimestamps.
   * The dtrace_ prefix prevents fbt from creating probes for
   * it so walltimestamp can be safely used in all fbt probes.
   */
  void
  dtrace_getnanotime(struct timespec *tsp)
  {
  	struct timehands *th;
  	u_int gen;
  
  	do {
  		th = timehands;
  		gen = th->th_generation;
  		*tsp = th->th_nanotime;
  	} while (gen == 0 || gen != th->th_generation);
  }
  
  /*
   * Initialize a new timecounter and possibly use it.
   */
  void
  tc_init(struct timecounter *tc)
  {
  	u_int u;
  	struct sysctl_oid *tc_root;
  
  	u = tc->tc_frequency / tc->tc_counter_mask;
  	/* XXX: We need some margin here, 10% is a guess */
  	u *= 11;
  	u /= 10;
  	if (u > hz && tc->tc_quality >= 0) {
  		tc->tc_quality = -2000;
  		if (bootverbose) {
  			printf("Timecounter \"%s\" frequency %ju Hz",
  			    tc->tc_name, (uintmax_t)tc->tc_frequency);
  			printf(" -- Insufficient hz, needs at least %u\n", u);
  		}
  	} else if (tc->tc_quality >= 0 || bootverbose) {
  		printf("Timecounter \"%s\" frequency %ju Hz quality %d\n",
  		    tc->tc_name, (uintmax_t)tc->tc_frequency,
  		    tc->tc_quality);
  	}
  
  	tc->tc_next = timecounters;
  	timecounters = tc;
  	/*
  	 * Set up sysctl tree for this counter.
  	 */
  	tc_root = SYSCTL_ADD_NODE(NULL,
  	    SYSCTL_STATIC_CHILDREN(_kern_timecounter_tc), OID_AUTO, tc->tc_name,
  	    CTLFLAG_RW, 0, "timecounter description");
  	SYSCTL_ADD_UINT(NULL, SYSCTL_CHILDREN(tc_root), OID_AUTO,
  	    "mask", CTLFLAG_RD, &(tc->tc_counter_mask), 0,
  	    "mask for implemented bits");
  	SYSCTL_ADD_PROC(NULL, SYSCTL_CHILDREN(tc_root), OID_AUTO,
  	    "counter", CTLTYPE_UINT | CTLFLAG_RD, tc, sizeof(*tc),
  	    sysctl_kern_timecounter_get, "IU", "current timecounter value");
  	SYSCTL_ADD_PROC(NULL, SYSCTL_CHILDREN(tc_root), OID_AUTO,
  	    "frequency", CTLTYPE_U64 | CTLFLAG_RD, tc, sizeof(*tc),
  	     sysctl_kern_timecounter_freq, "QU", "timecounter frequency");
  	SYSCTL_ADD_INT(NULL, SYSCTL_CHILDREN(tc_root), OID_AUTO,
  	    "quality", CTLFLAG_RD, &(tc->tc_quality), 0,
  	    "goodness of time counter");
  	/*
  	 * Never automatically use a timecounter with negative quality.
  	 * Even though we run on the dummy counter, switching here may be
  	 * worse since this timecounter may not be monotonous.
  	 */
  	if (tc->tc_quality < 0)
  		return;
  	if (tc->tc_quality < timecounter->tc_quality)
  		return;
  	if (tc->tc_quality == timecounter->tc_quality &&
  	    tc->tc_frequency < timecounter->tc_frequency)
  		return;
  	(void)tc->tc_get_timecount(tc);
  	(void)tc->tc_get_timecount(tc);
  	timecounter = tc;
  }
  
  /* Report the frequency of the current timecounter. */
  uint64_t
  tc_getfrequency(void)
  {
  
  	return (timehands->th_counter->tc_frequency);
  }
  
  /*
   * Step our concept of UTC.  This is done by modifying our estimate of
   * when we booted.
   * XXX: not locked.
   */
  void
  tc_setclock(struct timespec *ts)
  {
  	struct timespec tbef, taft;
  	struct bintime bt, bt2;
  
  	cpu_tick_calibrate(1);
  	nanotime(&tbef);
  	timespec2bintime(ts, &bt);
  	binuptime(&bt2);
  	bintime_sub(&bt, &bt2);
  	bintime_add(&bt2, &boottimebin);
  	boottimebin = bt;
  	bintime2timeval(&bt, &boottime);
  
  	/* XXX fiddle all the little crinkly bits around the fiords... */
  	tc_windup();
  	nanotime(&taft);
  	if (timestepwarnings) {
  		log(LOG_INFO,
  		    "Time stepped from %jd.%09ld to %jd.%09ld (%jd.%09ld)\n",
  		    (intmax_t)tbef.tv_sec, tbef.tv_nsec,
  		    (intmax_t)taft.tv_sec, taft.tv_nsec,
  		    (intmax_t)ts->tv_sec, ts->tv_nsec);
  	}
  	cpu_tick_calibrate(1);
  }
  
  /*
   * Initialize the next struct timehands in the ring and make
   * it the active timehands.  Along the way we might switch to a different
   * timecounter and/or do seconds processing in NTP.  Slightly magic.
   */
  static void
  tc_windup(void)
  {
  	struct bintime bt;
  	struct timehands *th, *tho;
  	uint64_t scale;
  	u_int delta, ncount, ogen;
  	int i;
  	time_t t;
  
  	/*
  	 * Make the next timehands a copy of the current one, but do not
  	 * overwrite the generation or next pointer.  While we update
  	 * the contents, the generation must be zero.
  	 */
  	tho = timehands;
  	th = tho->th_next;
  	ogen = th->th_generation;
  	th->th_generation = 0;
  	bcopy(tho, th, offsetof(struct timehands, th_generation));
  
  	/*
  	 * Capture a timecounter delta on the current timecounter and if
  	 * changing timecounters, a counter value from the new timecounter.
  	 * Update the offset fields accordingly.
  	 */
  	delta = tc_delta(th);
  	if (th->th_counter != timecounter)
  		ncount = timecounter->tc_get_timecount(timecounter);
  	else
  		ncount = 0;
  	th->th_offset_count += delta;
  	th->th_offset_count &= th->th_counter->tc_counter_mask;
  	while (delta > th->th_counter->tc_frequency) {
  		/* Eat complete unadjusted seconds. */
  		delta -= th->th_counter->tc_frequency;
  		th->th_offset.sec++;
  	}
  	if ((delta > th->th_counter->tc_frequency / 2) &&
  	    (th->th_scale * delta < ((uint64_t)1 << 63))) {
  		/* The product th_scale * delta just barely overflows. */
  		th->th_offset.sec++;
  	}
  	bintime_addx(&th->th_offset, th->th_scale * delta);
  
  	/*
  	 * Hardware latching timecounters may not generate interrupts on
  	 * PPS events, so instead we poll them.  There is a finite risk that
  	 * the hardware might capture a count which is later than the one we
  	 * got above, and therefore possibly in the next NTP second which might
  	 * have a different rate than the current NTP second.  It doesn't
  	 * matter in practice.
  	 */
  	if (tho->th_counter->tc_poll_pps)
  		tho->th_counter->tc_poll_pps(tho->th_counter);
  
  	/*
  	 * Deal with NTP second processing.  The for loop normally
  	 * iterates at most once, but in extreme situations it might
  	 * keep NTP sane if timeouts are not run for several seconds.
  	 * At boot, the time step can be large when the TOD hardware
  	 * has been read, so on really large steps, we call
  	 * ntp_update_second only twice.  We need to call it twice in
  	 * case we missed a leap second.
  	 */
  	bt = th->th_offset;
  	bintime_add(&bt, &boottimebin);
  	i = bt.sec - tho->th_microtime.tv_sec;
  	if (i > LARGE_STEP)
  		i = 2;
  	for (; i > 0; i--) {
  		t = bt.sec;
  		ntp_update_second(&th->th_adjustment, &bt.sec);
  		if (bt.sec != t)
  			boottimebin.sec += bt.sec - t;
  	}
  	/* Update the UTC timestamps used by the get*() functions. */
  	/* XXX shouldn't do this here.  Should force non-`get' versions. */
  	bintime2timeval(&bt, &th->th_microtime);
  	bintime2timespec(&bt, &th->th_nanotime);
  
  	/* Now is a good time to change timecounters. */
  	if (th->th_counter != timecounter) {
  #ifndef __arm__
  		if ((timecounter->tc_flags & TC_FLAGS_C3STOP) != 0)
  			cpu_disable_deep_sleep++;
  		if ((th->th_counter->tc_flags & TC_FLAGS_C3STOP) != 0)
  			cpu_disable_deep_sleep--;
  #endif
  		th->th_counter = timecounter;
  		th->th_offset_count = ncount;
  		tc_min_ticktock_freq = max(1, timecounter->tc_frequency /
  		    (((uint64_t)timecounter->tc_counter_mask + 1) / 3));
  	}
  
  	/*-
  	 * Recalculate the scaling factor.  We want the number of 1/2^64
  	 * fractions of a second per period of the hardware counter, taking
  	 * into account the th_adjustment factor which the NTP PLL/adjtime(2)
  	 * processing provides us with.
  	 *
  	 * The th_adjustment is nanoseconds per second with 32 bit binary
  	 * fraction and we want 64 bit binary fraction of second:
  	 *
  	 *	 x = a * 2^32 / 10^9 = a * 4.294967296
  	 *
  	 * The range of th_adjustment is +/- 5000PPM so inside a 64bit int
  	 * we can only multiply by about 850 without overflowing, that
  	 * leaves no suitably precise fractions for multiply before divide.
  	 *
  	 * Divide before multiply with a fraction of 2199/512 results in a
  	 * systematic undercompensation of 10PPM of th_adjustment.  On a
  	 * 5000PPM adjustment this is a 0.05PPM error.  This is acceptable.
   	 *
  	 * We happily sacrifice the lowest of the 64 bits of our result
  	 * to the goddess of code clarity.
  	 *
  	 */
  	scale = (uint64_t)1 << 63;
  	scale += (th->th_adjustment / 1024) * 2199;
  	scale /= th->th_counter->tc_frequency;
  	th->th_scale = scale * 2;
  
  	/*
  	 * Now that the struct timehands is again consistent, set the new
  	 * generation number, making sure to not make it zero.
  	 */
  	if (++ogen == 0)
  		ogen = 1;
  	th->th_generation = ogen;
  
  	/* Go live with the new struct timehands. */
  	time_second = th->th_microtime.tv_sec;
  	time_uptime = th->th_offset.sec;
  	timehands = th;
  	timekeep_push_vdso();
  }
  
  /* Report or change the active timecounter hardware. */
  static int
  sysctl_kern_timecounter_hardware(SYSCTL_HANDLER_ARGS)
  {
  	char newname[32];
  	struct timecounter *newtc, *tc;
  	int error;
  
  	tc = timecounter;
  	strlcpy(newname, tc->tc_name, sizeof(newname));
  
  	error = sysctl_handle_string(oidp, &newname[0], sizeof(newname), req);
  	if (error != 0 || req->newptr == NULL ||
  	    strcmp(newname, tc->tc_name) == 0)
  		return (error);
  	for (newtc = timecounters; newtc != NULL; newtc = newtc->tc_next) {
  		if (strcmp(newname, newtc->tc_name) != 0)
  			continue;
  
  		/* Warm up new timecounter. */
  		(void)newtc->tc_get_timecount(newtc);
  		(void)newtc->tc_get_timecount(newtc);
  
  		timecounter = newtc;
  		timekeep_push_vdso();
  		return (0);
  	}
  	return (EINVAL);
  }
  
  SYSCTL_PROC(_kern_timecounter, OID_AUTO, hardware, CTLTYPE_STRING | CTLFLAG_RW,
      0, 0, sysctl_kern_timecounter_hardware, "A",
      "Timecounter hardware selected");
  
  
  /* Report or change the active timecounter hardware. */
  static int
  sysctl_kern_timecounter_choice(SYSCTL_HANDLER_ARGS)
  {
  	char buf[32], *spc;
  	struct timecounter *tc;
  	int error;
  
  	spc = "";
  	error = 0;
  	for (tc = timecounters; error == 0 && tc != NULL; tc = tc->tc_next) {
  		sprintf(buf, "%s%s(%d)",
  		    spc, tc->tc_name, tc->tc_quality);
  		error = SYSCTL_OUT(req, buf, strlen(buf));
  		spc = " ";
  	}
  	return (error);
  }
  
  SYSCTL_PROC(_kern_timecounter, OID_AUTO, choice, CTLTYPE_STRING | CTLFLAG_RD,
      0, 0, sysctl_kern_timecounter_choice, "A", "Timecounter hardware detected");
  
  /*
   * RFC 2783 PPS-API implementation.
   */
  
  int
  pps_ioctl(u_long cmd, caddr_t data, struct pps_state *pps)
  {
  	pps_params_t *app;
  	struct pps_fetch_args *fapi;
  #ifdef PPS_SYNC
  	struct pps_kcbind_args *kapi;
  #endif
  
  	KASSERT(pps != NULL, ("NULL pps pointer in pps_ioctl"));
  	switch (cmd) {
  	case PPS_IOC_CREATE:
  		return (0);
  	case PPS_IOC_DESTROY:
  		return (0);
  	case PPS_IOC_SETPARAMS:
  		app = (pps_params_t *)data;
  		if (app->mode & ~pps->ppscap)
  			return (EINVAL);
  		pps->ppsparam = *app;
  		return (0);
  	case PPS_IOC_GETPARAMS:
  		app = (pps_params_t *)data;
  		*app = pps->ppsparam;
  		app->api_version = PPS_API_VERS_1;
  		return (0);
  	case PPS_IOC_GETCAP:
  		*(int*)data = pps->ppscap;
  		return (0);
  	case PPS_IOC_FETCH:
  		fapi = (struct pps_fetch_args *)data;
  		if (fapi->tsformat && fapi->tsformat != PPS_TSFMT_TSPEC)
  			return (EINVAL);
  		if (fapi->timeout.tv_sec || fapi->timeout.tv_nsec)
  			return (EOPNOTSUPP);
  		pps->ppsinfo.current_mode = pps->ppsparam.mode;
  		fapi->pps_info_buf = pps->ppsinfo;
  		return (0);
  	case PPS_IOC_KCBIND:
  #ifdef PPS_SYNC
  		kapi = (struct pps_kcbind_args *)data;
  		/* XXX Only root should be able to do this */
  		if (kapi->tsformat && kapi->tsformat != PPS_TSFMT_TSPEC)
  			return (EINVAL);
  		if (kapi->kernel_consumer != PPS_KC_HARDPPS)
  			return (EINVAL);
  		if (kapi->edge & ~pps->ppscap)
  			return (EINVAL);
  		pps->kcmode = kapi->edge;
  		return (0);
  #else
  		return (EOPNOTSUPP);
  #endif
  	default:
  		return (ENOIOCTL);
  	}
  }
  
  void
  pps_init(struct pps_state *pps)
  {
  	pps->ppscap |= PPS_TSFMT_TSPEC;
  	if (pps->ppscap & PPS_CAPTUREASSERT)
  		pps->ppscap |= PPS_OFFSETASSERT;
  	if (pps->ppscap & PPS_CAPTURECLEAR)
  		pps->ppscap |= PPS_OFFSETCLEAR;
  }
  
  void
  pps_capture(struct pps_state *pps)
  {
  	struct timehands *th;
  
  	KASSERT(pps != NULL, ("NULL pps pointer in pps_capture"));
  	th = timehands;
  	pps->capgen = th->th_generation;
  	pps->capth = th;
  	pps->capcount = th->th_counter->tc_get_timecount(th->th_counter);
  	if (pps->capgen != th->th_generation)
  		pps->capgen = 0;
  }
  
  void
  pps_event(struct pps_state *pps, int event)
  {
  	struct bintime bt;
  	struct timespec ts, *tsp, *osp;
  	u_int tcount, *pcount;
  	int foff, fhard;
  	pps_seq_t *pseq;
  
  	KASSERT(pps != NULL, ("NULL pps pointer in pps_event"));
  	/* If the timecounter was wound up underneath us, bail out. */
  	if (pps->capgen == 0 || pps->capgen != pps->capth->th_generation)
  		return;
  
  	/* Things would be easier with arrays. */
  	if (event == PPS_CAPTUREASSERT) {
  		tsp = &pps->ppsinfo.assert_timestamp;
  		osp = &pps->ppsparam.assert_offset;
  		foff = pps->ppsparam.mode & PPS_OFFSETASSERT;
  		fhard = pps->kcmode & PPS_CAPTUREASSERT;
  		pcount = &pps->ppscount[0];
  		pseq = &pps->ppsinfo.assert_sequence;
  	} else {
  		tsp = &pps->ppsinfo.clear_timestamp;
  		osp = &pps->ppsparam.clear_offset;
  		foff = pps->ppsparam.mode & PPS_OFFSETCLEAR;
  		fhard = pps->kcmode & PPS_CAPTURECLEAR;
  		pcount = &pps->ppscount[1];
  		pseq = &pps->ppsinfo.clear_sequence;
  	}
  
  	/*
  	 * If the timecounter changed, we cannot compare the count values, so
  	 * we have to drop the rest of the PPS-stuff until the next event.
  	 */
  	if (pps->ppstc != pps->capth->th_counter) {
  		pps->ppstc = pps->capth->th_counter;
  		*pcount = pps->capcount;
  		pps->ppscount[2] = pps->capcount;
  		return;
  	}
  
  	/* Convert the count to a timespec. */
  	tcount = pps->capcount - pps->capth->th_offset_count;
  	tcount &= pps->capth->th_counter->tc_counter_mask;
  	bt = pps->capth->th_offset;
  	bintime_addx(&bt, pps->capth->th_scale * tcount);
  	bintime_add(&bt, &boottimebin);
  	bintime2timespec(&bt, &ts);
  
  	/* If the timecounter was wound up underneath us, bail out. */
  	if (pps->capgen != pps->capth->th_generation)
  		return;
  
  	*pcount = pps->capcount;
  	(*pseq)++;
  	*tsp = ts;
  
  	if (foff) {
  		timespecadd(tsp, osp);
  		if (tsp->tv_nsec < 0) {
  			tsp->tv_nsec += 1000000000;
  			tsp->tv_sec -= 1;
  		}
  	}
  #ifdef PPS_SYNC
  	if (fhard) {
  		uint64_t scale;
  
  		/*
  		 * Feed the NTP PLL/FLL.
  		 * The FLL wants to know how many (hardware) nanoseconds
  		 * elapsed since the previous event.
  		 */
  		tcount = pps->capcount - pps->ppscount[2];
  		pps->ppscount[2] = pps->capcount;
  		tcount &= pps->capth->th_counter->tc_counter_mask;
  		scale = (uint64_t)1 << 63;
  		scale /= pps->capth->th_counter->tc_frequency;
  		scale *= 2;
  		bt.sec = 0;
  		bt.frac = 0;
  		bintime_addx(&bt, scale * tcount);
  		bintime2timespec(&bt, &ts);
  		hardpps(tsp, ts.tv_nsec + 1000000000 * ts.tv_sec);
  	}
  #endif
  }
  
  /*
   * Timecounters need to be updated every so often to prevent the hardware
   * counter from overflowing.  Updating also recalculates the cached values
   * used by the get*() family of functions, so their precision depends on
   * the update frequency.
   */
  
  static int tc_tick;
  SYSCTL_INT(_kern_timecounter, OID_AUTO, tick, CTLFLAG_RD, &tc_tick, 0,
      "Approximate number of hardclock ticks in a millisecond");
  
  void
  tc_ticktock(int cnt)
  {
  	static int count;
  
  	count += cnt;
  	if (count < tc_tick)
  		return;
  	count = 0;
  	tc_windup();
  }
  
  static void
  inittimecounter(void *dummy)
  {
  	u_int p;
  
  	/*
  	 * Set the initial timeout to
  	 * max(1, <approx. number of hardclock ticks in a millisecond>).
  	 * People should probably not use the sysctl to set the timeout
  	 * to smaller than its inital value, since that value is the
  	 * smallest reasonable one.  If they want better timestamps they
  	 * should use the non-"get"* functions.
  	 */
  	if (hz > 1000)
  		tc_tick = (hz + 500) / 1000;
  	else
  		tc_tick = 1;
  	p = (tc_tick * 1000000) / hz;
  	printf("Timecounters tick every %d.%03u msec\n", p / 1000, p % 1000);
  
  	/* warm up new timecounter (again) and get rolling. */
  	(void)timecounter->tc_get_timecount(timecounter);
  	(void)timecounter->tc_get_timecount(timecounter);
  	tc_windup();
  }
  
  SYSINIT(timecounter, SI_SUB_CLOCKS, SI_ORDER_SECOND, inittimecounter, NULL);
  
  /* Cpu tick handling -------------------------------------------------*/
  
  static int cpu_tick_variable;
  static uint64_t	cpu_tick_frequency;
  
  static uint64_t
  tc_cpu_ticks(void)
  {
  	static uint64_t base;
  	static unsigned last;
  	unsigned u;
  	struct timecounter *tc;
  
  	tc = timehands->th_counter;
  	u = tc->tc_get_timecount(tc) & tc->tc_counter_mask;
  	if (u < last)
  		base += (uint64_t)tc->tc_counter_mask + 1;
  	last = u;
  	return (u + base);
  }
  
  void
  cpu_tick_calibration(void)
  {
  	static time_t last_calib;
  
  	if (time_uptime != last_calib && !(time_uptime & 0xf)) {
  		cpu_tick_calibrate(0);
  		last_calib = time_uptime;
  	}
  }
  
  /*
   * This function gets called every 16 seconds on only one designated
   * CPU in the system from hardclock() via cpu_tick_calibration()().
   *
   * Whenever the real time clock is stepped we get called with reset=1
   * to make sure we handle suspend/resume and similar events correctly.
   */
  
  static void
  cpu_tick_calibrate(int reset)
  {
  	static uint64_t c_last;
  	uint64_t c_this, c_delta;
  	static struct bintime  t_last;
  	struct bintime t_this, t_delta;
  	uint32_t divi;
  
  	if (reset) {
  		/* The clock was stepped, abort & reset */
  		t_last.sec = 0;
  		return;
  	}
  
  	/* we don't calibrate fixed rate cputicks */
  	if (!cpu_tick_variable)
  		return;
  
  	getbinuptime(&t_this);
  	c_this = cpu_ticks();
  	if (t_last.sec != 0) {
  		c_delta = c_this - c_last;
  		t_delta = t_this;
  		bintime_sub(&t_delta, &t_last);
  		/*
  		 * Headroom:
  		 * 	2^(64-20) / 16[s] =
  		 * 	2^(44) / 16[s] =
  		 * 	17.592.186.044.416 / 16 =
  		 * 	1.099.511.627.776 [Hz]
  		 */
  		divi = t_delta.sec << 20;
  		divi |= t_delta.frac >> (64 - 20);
  		c_delta <<= 20;
  		c_delta /= divi;
  		if (c_delta > cpu_tick_frequency) {
  			if (0 && bootverbose)
  				printf("cpu_tick increased to %ju Hz\n",
  				    c_delta);
  			cpu_tick_frequency = c_delta;
  		}
  	}
  	c_last = c_this;
  	t_last = t_this;
  }
  
  void
  set_cputicker(cpu_tick_f *func, uint64_t freq, unsigned var)
  {
  
  	if (func == NULL) {
  		cpu_ticks = tc_cpu_ticks;
  	} else {
  		cpu_tick_frequency = freq;
  		cpu_tick_variable = var;
  		cpu_ticks = func;
  	}
  }
  
  uint64_t
  cpu_tickrate(void)
  {
  
  	if (cpu_ticks == tc_cpu_ticks) 
  		return (tc_getfrequency());
  	return (cpu_tick_frequency);
  }
  
  /*
   * We need to be slightly careful converting cputicks to microseconds.
   * There is plenty of margin in 64 bits of microseconds (half a million
   * years) and in 64 bits at 4 GHz (146 years), but if we do a multiply
   * before divide conversion (to retain precision) we find that the
   * margin shrinks to 1.5 hours (one millionth of 146y).
   * With a three prong approach we never lose significant bits, no
   * matter what the cputick rate and length of timeinterval is.
   */
  
  uint64_t
  cputick2usec(uint64_t tick)
  {
  
  	if (tick > 18446744073709551LL)		/* floor(2^64 / 1000) */
  		return (tick / (cpu_tickrate() / 1000000LL));
  	else if (tick > 18446744073709LL)	/* floor(2^64 / 1000000) */
  		return ((tick * 1000LL) / (cpu_tickrate() / 1000LL));
  	else
  		return ((tick * 1000000LL) / cpu_tickrate());
  }
  
  cpu_tick_f	*cpu_ticks = tc_cpu_ticks;
  
  static int vdso_th_enable = 1;
  static int
  sysctl_fast_gettime(SYSCTL_HANDLER_ARGS)
  {
  	int old_vdso_th_enable, error;
  
  	old_vdso_th_enable = vdso_th_enable;
  	error = sysctl_handle_int(oidp, &old_vdso_th_enable, 0, req);
  	if (error != 0)
  		return (error);
  	vdso_th_enable = old_vdso_th_enable;
  	timekeep_push_vdso();
  	return (0);
  }
  SYSCTL_PROC(_kern_timecounter, OID_AUTO, fast_gettime,
      CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_MPSAFE,
      NULL, 0, sysctl_fast_gettime, "I", "Enable fast time of day");
  
  uint32_t
  tc_fill_vdso_timehands(struct vdso_timehands *vdso_th)
  {
  	struct timehands *th;
  	uint32_t enabled;
  
  	th = timehands;
  	vdso_th->th_algo = VDSO_TH_ALGO_1;
  	vdso_th->th_scale = th->th_scale;
  	vdso_th->th_offset_count = th->th_offset_count;
  	vdso_th->th_counter_mask = th->th_counter->tc_counter_mask;
  	vdso_th->th_offset = th->th_offset;
  	vdso_th->th_boottime = boottimebin;
  	enabled = cpu_fill_vdso_timehands(vdso_th);
  	if (!vdso_th_enable)
  		enabled = 0;
  	return (enabled);
  }
  
  #ifdef COMPAT_FREEBSD32
  uint32_t
  tc_fill_vdso_timehands32(struct vdso_timehands32 *vdso_th32)
  {
  	struct timehands *th;
  	uint32_t enabled;
  
  	th = timehands;
  	vdso_th32->th_algo = VDSO_TH_ALGO_1;
  	*(uint64_t *)&vdso_th32->th_scale[0] = th->th_scale;
  	vdso_th32->th_offset_count = th->th_offset_count;
  	vdso_th32->th_counter_mask = th->th_counter->tc_counter_mask;
  	vdso_th32->th_offset.sec = th->th_offset.sec;
  	*(uint64_t *)&vdso_th32->th_offset.frac[0] = th->th_offset.frac;
  	vdso_th32->th_boottime.sec = boottimebin.sec;
  	*(uint64_t *)&vdso_th32->th_boottime.frac[0] = boottimebin.frac;
  	enabled = cpu_fill_vdso_timehands32(vdso_th32);
  	if (!vdso_th_enable)
  		enabled = 0;
  	return (enabled);
  }
  #endif
  