 @@ -1,1328 +1,1344 @@
-/* $NetBSD: kern_tc.c,v 1.46 2013/09/14 20:52:43 martin Exp $ */
+/* $NetBSD: kern_tc.c,v 1.47 2017/06/09 01:16:33 chs Exp $ */
 /*-
  * Copyright (c) 2008, 2009 The NetBSD Foundation, Inc.
  * All rights reserved.
+ *
  * This code is derived from software contributed to The NetBSD Foundation
  * by Andrew Doran.
+ *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
  *    documentation and/or other materials provided with the distribution.
+ *
  * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
  * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
  * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
  * POSSIBILITY OF SUCH DAMAGE.
  */
 /*-
  * ----------------------------------------------------------------------------
  * "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: src/sys/kern/kern_tc.c,v 1.166 2005/09/19 22:16:31 andre Exp $"); */
-__KERNEL_RCSID(0, "$NetBSD: kern_tc.c,v 1.46 2013/09/14 20:52:43 martin Exp $");
+__KERNEL_RCSID(0, "$NetBSD: kern_tc.c,v 1.47 2017/06/09 01:16:33 chs Exp $");
 #ifdef _KERNEL_OPT
 #include "opt_ntp.h"
 #endif
 #include <sys/param.h>
 #include <sys/kernel.h>
 #include <sys/reboot.h>	/* XXX just to get AB_VERBOSE */
 #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/evcnt.h>
 #include <sys/kauth.h>
 #include <sys/mutex.h>
 #include <sys/atomic.h>
 #include <sys/xcall.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, NULL, NULL,
 };
 struct timehands {
 	/* These fields must be initialized by the driver. */
 	struct timecounter	*th_counter;     /* active timecounter */
 	int64_t			th_adjustment;   /* frequency adjustment */
 						 /* (NTP/adjtime) */
 	u_int64_t		th_scale;        /* scale factor (counter */
 						 /* tick->time) */
 	u_int64_t 		th_offset_count; /* offset at last time */
 						 /* update (tc_windup()) */
 	struct bintime		th_offset;       /* bin (up)time at windup */
 	struct timeval		th_microtime;    /* cached microtime */
 	struct timespec		th_nanotime;     /* cached nanotime */
 	/* Fields not to be copied in tc_windup start with th_generation. */
 	volatile u_int		th_generation;   /* current genration */
 	struct timehands	*th_next;        /* next timehand */
 };
 static struct timehands th0;
 static struct timehands th9 = { .th_next = &th0, };
 static struct timehands th8 = { .th_next = &th9, };
 static struct timehands th7 = { .th_next = &th8, };
 static struct timehands th6 = { .th_next = &th7, };
 static struct timehands th5 = { .th_next = &th6, };
 static struct timehands th4 = { .th_next = &th5, };
 static struct timehands th3 = { .th_next = &th4, };
 static struct timehands th2 = { .th_next = &th3, };
 static struct timehands th1 = { .th_next = &th2, };
 static struct timehands th0 = {
 	.th_counter = &dummy_timecounter,
 	.th_scale = (uint64_t)-1 / 1000000,
 	.th_offset = { .sec = 1, .frac = 0 },
 	.th_generation = 1,
 	.th_next = &th1,
 };
 static struct timehands *volatile timehands = &th0;
 struct timecounter *timecounter = &dummy_timecounter;
 static struct timecounter *timecounters = &dummy_timecounter;
 volatile time_t time_second = 1;
 volatile time_t time_uptime = 1;
 static struct bintime timebasebin;
 static int timestepwarnings;
 kmutex_t timecounter_lock;
 static u_int timecounter_mods;
 static volatile int timecounter_removals = 1;
 static u_int timecounter_bad;
 #ifdef __FreeBSD__
 SYSCTL_INT(_kern_timecounter, OID_AUTO, stepwarnings, CTLFLAG_RW,
     &timestepwarnings, 0, "");
 #endif /* __FreeBSD__ */
 /*
  * sysctl helper routine for kern.timercounter.hardware
  */
 static int
 sysctl_kern_timecounter_hardware(SYSCTLFN_ARGS)
+{
 	struct sysctlnode node;
 	int error;
 	char newname[MAX_TCNAMELEN];
 	struct timecounter *newtc, *tc;
 	tc = timecounter;
 	strlcpy(newname, tc->tc_name, sizeof(newname));
 	node = *rnode;
 	node.sysctl_data = newname;
 	node.sysctl_size = sizeof(newname);
 	error = sysctl_lookup(SYSCTLFN_CALL(&node));
 	if (error ||
 	    newp == NULL ||
 	    strncmp(newname, tc->tc_name, sizeof(newname)) == 0)
 		return error;
 	if (l != NULL && (error = kauth_authorize_system(l->l_cred,
 	    KAUTH_SYSTEM_TIME, KAUTH_REQ_SYSTEM_TIME_TIMECOUNTERS, newname,
 	    NULL, NULL)) != 0)
 		return (error);
 	if (!cold)
 		mutex_spin_enter(&timecounter_lock);
 	error = EINVAL;
 	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;
 		error = 0;
 		break;
+	}
 	if (!cold)
 		mutex_spin_exit(&timecounter_lock);
 	return error;
+}
 static int
 sysctl_kern_timecounter_choice(SYSCTLFN_ARGS)
+{
 	char buf[MAX_TCNAMELEN+48];
 	char *where;
 	const char *spc;
 	struct timecounter *tc;
 	size_t needed, left, slen;
 	int error, mods;
 	if (newp != NULL)
 		return (EPERM);
 	if (namelen != 0)
 		return (EINVAL);
 	mutex_spin_enter(&timecounter_lock);
  retry:
 	spc = "";
 	error = 0;
 	needed = 0;
 	left = *oldlenp;
 	where = oldp;
 	for (tc = timecounters; error == 0 && tc != NULL; tc = tc->tc_next) {
 		if (where == NULL) {
 			needed += sizeof(buf);  /* be conservative */
 		} else {
 			slen = snprintf(buf, sizeof(buf), "%s%s(q=%d, f=%" PRId64
 					" Hz)", spc, tc->tc_name, tc->tc_quality,
 					tc->tc_frequency);
 			if (left < slen + 1)
 				break;
 		 	mods = timecounter_mods;
 			mutex_spin_exit(&timecounter_lock);
 			error = copyout(buf, where, slen + 1);
 			mutex_spin_enter(&timecounter_lock);
 			if (mods != timecounter_mods) {
 				goto retry;
+			}
 			spc = " ";
 			where += slen;
 			needed += slen;
 			left -= slen;
+		}
+	}
 	mutex_spin_exit(&timecounter_lock);
 	*oldlenp = needed;
 	return (error);
+}
 SYSCTL_SETUP(sysctl_timecounter_setup, "sysctl timecounter setup")
+{
 	const struct sysctlnode *node;
 	sysctl_createv(clog, 0, NULL, &node,
 		       CTLFLAG_PERMANENT,
 		       CTLTYPE_NODE, "timecounter",
 		       SYSCTL_DESCR("time counter information"),
 		       NULL, 0, NULL, 0,
 		       CTL_KERN, CTL_CREATE, CTL_EOL);
 	if (node != NULL) {
 		sysctl_createv(clog, 0, NULL, NULL,
 			       CTLFLAG_PERMANENT,
 			       CTLTYPE_STRING, "choice",
 			       SYSCTL_DESCR("available counters"),
 			       sysctl_kern_timecounter_choice, 0, NULL, 0,
 			       CTL_KERN, node->sysctl_num, CTL_CREATE, CTL_EOL);
 		sysctl_createv(clog, 0, NULL, NULL,
 			       CTLFLAG_PERMANENT|CTLFLAG_READWRITE,
 			       CTLTYPE_STRING, "hardware",
 			       SYSCTL_DESCR("currently active time counter"),
 			       sysctl_kern_timecounter_hardware, 0, NULL, MAX_TCNAMELEN,
 			       CTL_KERN, node->sysctl_num, CTL_CREATE, CTL_EOL);
 		sysctl_createv(clog, 0, NULL, NULL,
 			       CTLFLAG_PERMANENT|CTLFLAG_READWRITE,
 			       CTLTYPE_INT, "timestepwarnings",
 			       SYSCTL_DESCR("log time steps"),
 			       NULL, 0, &timestepwarnings, 0,
 			       CTL_KERN, node->sysctl_num, CTL_CREATE, CTL_EOL);
+	}
+}
 #ifdef TC_COUNTERS
 #define	TC_STATS(name)							\
 static struct evcnt n##name =						\
     EVCNT_INITIALIZER(EVCNT_TYPE_MISC, NULL, "timecounter", #name);	\
 EVCNT_ATTACH_STATIC(n##name)
 TC_STATS(binuptime);    TC_STATS(nanouptime);    TC_STATS(microuptime);
 TC_STATS(bintime);      TC_STATS(nanotime);      TC_STATS(microtime);
 TC_STATS(getbinuptime); TC_STATS(getnanouptime); TC_STATS(getmicrouptime);
 TC_STATS(getbintime);   TC_STATS(getnanotime);   TC_STATS(getmicrotime);
 TC_STATS(setclock);
 #define	TC_COUNT(var)	var.ev_count++
 #undef TC_STATS
 #else
 #define	TC_COUNT(var)	/* nothing */
 #endif	/* TC_COUNTERS */
 static void tc_windup(void);
 /*
  * 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/timevar.h> for a description of these 12 functions.
  */
 void
 binuptime(struct bintime *bt)
+{
 	struct timehands *th;
 	lwp_t *l;
 	u_int lgen, gen;
 	TC_COUNT(nbinuptime);
 	/*
 	 * Provide exclusion against tc_detach().
+	 *
 	 * We record the number of timecounter removals before accessing
 	 * timecounter state.  Note that the LWP can be using multiple
 	 * "generations" at once, due to interrupts (interrupted while in
 	 * this function).  Hardware interrupts will borrow the interrupted
 	 * LWP's l_tcgen value for this purpose, and can themselves be
 	 * interrupted by higher priority interrupts.  In this case we need
 	 * to ensure that the oldest generation in use is recorded.
+	 *
 	 * splsched() is too expensive to use, so we take care to structure
 	 * this code in such a way that it is not required.  Likewise, we
 	 * do not disable preemption.
+	 *
 	 * Memory barriers are also too expensive to use for such a
 	 * performance critical function.  The good news is that we do not
 	 * need memory barriers for this type of exclusion, as the thread
 	 * updating timecounter_removals will issue a broadcast cross call
 	 * before inspecting our l_tcgen value (this elides memory ordering
 	 * issues).
 	 */
 	l = curlwp;
 	lgen = l->l_tcgen;
 	if (__predict_true(lgen == 0)) {
 		l->l_tcgen = timecounter_removals;
+	}
 	__insn_barrier();
 	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);
 	__insn_barrier();
 	l->l_tcgen = lgen;
+}
 void
 nanouptime(struct timespec *tsp)
+{
 	struct bintime bt;
 	TC_COUNT(nnanouptime);
 	binuptime(&bt);
 	bintime2timespec(&bt, tsp);
+}
 void
 microuptime(struct timeval *tvp)
+{
 	struct bintime bt;
 	TC_COUNT(nmicrouptime);
 	binuptime(&bt);
 	bintime2timeval(&bt, tvp);
+}
 void
 bintime(struct bintime *bt)
+{
 	TC_COUNT(nbintime);
 	binuptime(bt);
 	bintime_add(bt, &timebasebin);
+}
 void
 nanotime(struct timespec *tsp)
+{
 	struct bintime bt;
 	TC_COUNT(nnanotime);
 	bintime(&bt);
 	bintime2timespec(&bt, tsp);
+}
 void
 microtime(struct timeval *tvp)
+{
 	struct bintime bt;
 	TC_COUNT(nmicrotime);
 	bintime(&bt);
 	bintime2timeval(&bt, tvp);
+}
 void
 getbinuptime(struct bintime *bt)
+{
 	struct timehands *th;
 	u_int gen;
 	TC_COUNT(ngetbinuptime);
 	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;
 	TC_COUNT(ngetnanouptime);
 	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;
 	TC_COUNT(ngetmicrouptime);
 	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;
 	TC_COUNT(ngetbintime);
 	do {
 		th = timehands;
 		gen = th->th_generation;
 		*bt = th->th_offset;
 	} while (gen == 0 || gen != th->th_generation);
 	bintime_add(bt, &timebasebin);
+}
-void
+static inline void
-getnanotime(struct timespec *tsp)
+dogetnanotime(struct timespec *tsp)
+{
 	struct timehands *th;
 	u_int gen;
 	TC_COUNT(ngetnanotime);
 	do {
 		th = timehands;
 		gen = th->th_generation;
 		*tsp = th->th_nanotime;
 	} while (gen == 0 || gen != th->th_generation);
+}
 void
 getnanotime(struct timespec *tsp)
+{
 	dogetnanotime(tsp);
+}
 void dtrace_getnanotime(struct timespec *tsp);
 void
 dtrace_getnanotime(struct timespec *tsp)
+{
 	dogetnanotime(tsp);
+}
 void
 getmicrotime(struct timeval *tvp)
+{
 	struct timehands *th;
 	u_int gen;
 	TC_COUNT(ngetmicrotime);
 	do {
 		th = timehands;
 		gen = th->th_generation;
 		*tvp = th->th_microtime;
 	} while (gen == 0 || gen != th->th_generation);
+}
 /*
  * Initialize a new timecounter and possibly use it.
  */
 void
 tc_init(struct timecounter *tc)
+{
 	u_int u;
 	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;
 		aprint_verbose(
 		    "timecounter: Timecounter \"%s\" frequency %ju Hz",
 			    tc->tc_name, (uintmax_t)tc->tc_frequency);
 		aprint_verbose(" -- Insufficient hz, needs at least %u\n", u);
 	} else if (tc->tc_quality >= 0 || bootverbose) {
 		aprint_verbose(
 		    "timecounter: Timecounter \"%s\" frequency %ju Hz "
 		    "quality %d\n", tc->tc_name, (uintmax_t)tc->tc_frequency,
 		    tc->tc_quality);
+	}
 	mutex_spin_enter(&timecounter_lock);
 	tc->tc_next = timecounters;
 	timecounters = tc;
 	timecounter_mods++;
 	/*
 	 * 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 && (tc->tc_quality > timecounter->tc_quality ||
 	    (tc->tc_quality == timecounter->tc_quality &&
 	    tc->tc_frequency > timecounter->tc_frequency))) {
 		(void)tc->tc_get_timecount(tc);
 		(void)tc->tc_get_timecount(tc);
 		timecounter = tc;
 		tc_windup();
+	}
 	mutex_spin_exit(&timecounter_lock);
+}
 /*
  * Pick a new timecounter due to the existing counter going bad.
  */
 static void
 tc_pick(void)
+{
 	struct timecounter *best, *tc;
 	KASSERT(mutex_owned(&timecounter_lock));
 	for (best = tc = timecounters; tc != NULL; tc = tc->tc_next) {
 		if (tc->tc_quality > best->tc_quality)
 			best = tc;
 		else if (tc->tc_quality < best->tc_quality)
 			continue;
 		else if (tc->tc_frequency > best->tc_frequency)
 			best = tc;
+	}
 	(void)best->tc_get_timecount(best);
 	(void)best->tc_get_timecount(best);
 	timecounter = best;
+}
 /*
  * A timecounter has gone bad, arrange to pick a new one at the next
  * clock tick.
  */
 void
 tc_gonebad(struct timecounter *tc)
+{
 	tc->tc_quality = -100;
 	membar_producer();
 	atomic_inc_uint(&timecounter_bad);
+}
 /*
  * Stop using a timecounter and remove it from the timecounters list.
  */
 int
 tc_detach(struct timecounter *target)
+{
 	struct timecounter *tc;
 	struct timecounter **tcp = NULL;
 	int removals;
 	uint64_t where;
 	lwp_t *l;
 	/* First, find the timecounter. */
 	mutex_spin_enter(&timecounter_lock);
 	for (tcp = &timecounters, tc = timecounters;
 	     tc != NULL;
 	     tcp = &tc->tc_next, tc = tc->tc_next) {
 		if (tc == target)
 			break;
+	}
 	if (tc == NULL) {
 		mutex_spin_exit(&timecounter_lock);
 		return ESRCH;
+	}
 	/* And now, remove it. */
 	*tcp = tc->tc_next;
 	if (timecounter == target) {
 		tc_pick();
 		tc_windup();
+	}
 	timecounter_mods++;
 	removals = timecounter_removals++;
 	mutex_spin_exit(&timecounter_lock);
 	/*
 	 * We now have to determine if any threads in the system are still
 	 * making use of this timecounter.
+	 *
 	 * We issue a broadcast cross call to elide memory ordering issues,
 	 * then scan all LWPs in the system looking at each's timecounter
 	 * generation number.  We need to see a value of zero (not actively
 	 * using a timecounter) or a value greater than our removal value.
+	 *
 	 * We may race with threads that read `timecounter_removals' and
 	 * and then get preempted before updating `l_tcgen'.  This is not
 	 * a problem, since it means that these threads have not yet started
 	 * accessing timecounter state.  All we do need is one clean
 	 * snapshot of the system where every thread appears not to be using
 	 * old timecounter state.
 	 */
 	for (;;) {
 		where = xc_broadcast(0, (xcfunc_t)nullop, NULL, NULL);
 		xc_wait(where);
 		mutex_enter(proc_lock);
 		LIST_FOREACH(l, &alllwp, l_list) {
 			if (l->l_tcgen == 0 || l->l_tcgen > removals) {
 				/*
 				 * Not using timecounter or old timecounter
 				 * state at time of our xcall or later.
 				 */
 				continue;
+			}
 			break;
+		}
 		mutex_exit(proc_lock);
 		/*
 		 * If the timecounter is still in use, wait at least 10ms
 		 * before retrying.
 		 */
 		if (l == NULL) {
 			return 0;
+		}
 		(void)kpause("tcdetach", false, mstohz(10), NULL);
+	}
+}
 /* Report the frequency of the current timecounter. */
 u_int64_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.
  */
 void
 tc_setclock(const struct timespec *ts)
+{
 	struct timespec ts2;
 	struct bintime bt, bt2;
 	mutex_spin_enter(&timecounter_lock);
 	TC_COUNT(nsetclock);
 	binuptime(&bt2);
 	timespec2bintime(ts, &bt);
 	bintime_sub(&bt, &bt2);
 	bintime_add(&bt2, &timebasebin);
 	timebasebin = bt;
 	tc_windup();
 	mutex_spin_exit(&timecounter_lock);
 	if (timestepwarnings) {
 		bintime2timespec(&bt2, &ts2);
 		log(LOG_INFO,
 		    "Time stepped from %lld.%09ld to %lld.%09ld\n",
 		    (long long)ts2.tv_sec, ts2.tv_nsec,
 		    (long long)ts->tv_sec, ts->tv_nsec);
+	}
+}
 /*
  * 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;
 	u_int64_t scale;
 	u_int delta, ncount, ogen;
 	int i, s_update;
 	time_t t;
 	KASSERT(mutex_owned(&timecounter_lock));
 	s_update = 0;
 	/*
 	 * 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.  Ensure global
 	 * visibility of the generation before proceeding.
 	 */
 	tho = timehands;
 	th = tho->th_next;
 	ogen = th->th_generation;
 	th->th_generation = 0;
 	membar_producer();
 	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;
 	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.
 	 * If NTP is not compiled in ntp_update_second still calculates
 	 * the adjustment resulting from adjtime() calls.
 	 */
 	bt = th->th_offset;
 	bintime_add(&bt, &timebasebin);
 	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);
 		s_update = 1;
 		if (bt.sec != t)
 			timebasebin.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) {
 		th->th_counter = timecounter;
 		th->th_offset_count = ncount;
 		s_update = 1;
+	}
 	/*-
 	 * 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, but that
 	 * leaves 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.
+	 *
 	 */
 	if (s_update) {
 		scale = (u_int64_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.  Ensure
 	 * changes are globally visible before changing.
 	 */
 	if (++ogen == 0)
 		ogen = 1;
 	membar_producer();
 	th->th_generation = ogen;
 	/*
 	 * Go live with the new struct timehands.  Ensure changes are
 	 * globally visible before changing.
 	 */
 	time_second = th->th_microtime.tv_sec;
 	time_uptime = th->th_offset.sec;
 	membar_producer();
 	timehands = th;
 	/*
 	 * Force users of the old timehand to move on.  This is
 	 * necessary for MP systems; we need to ensure that the
 	 * consumers will move away from the old timehand before
 	 * we begin updating it again when we eventually wrap
 	 * around.
 	 */
 	if (++tho->th_generation == 0)
 		tho->th_generation = 1;
+}
 /*
  * RFC 2783 PPS-API implementation.
  */
 int
 pps_ioctl(u_long cmd, void *data, struct pps_state *pps)
+{
 	pps_params_t *app;
 	pps_info_t *pipi;
 #ifdef PPS_SYNC
 	int *epi;
 #endif
 	KASSERT(mutex_owned(&timecounter_lock));
 	KASSERT(pps != NULL);
 	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:
 		pipi = (pps_info_t *)data;
 		pps->ppsinfo.current_mode = pps->ppsparam.mode;
 		*pipi = pps->ppsinfo;
 		return (0);
 	case PPS_IOC_KCBIND:
 #ifdef PPS_SYNC
 		epi = (int *)data;
 		/* XXX Only root should be able to do this */
 		if (*epi & ~pps->ppscap)
 			return (EINVAL);
 		pps->kcmode = *epi;
 		return (0);
 #else
 		return (EOPNOTSUPP);
 #endif
 	default:
 		return (EPASSTHROUGH);
+	}
+}
 void
 pps_init(struct pps_state *pps)
+{
 	KASSERT(mutex_owned(&timecounter_lock));
 	pps->ppscap |= PPS_TSFMT_TSPEC;
 	if (pps->ppscap & PPS_CAPTUREASSERT)
 		pps->ppscap |= PPS_OFFSETASSERT;
 	if (pps->ppscap & PPS_CAPTURECLEAR)
 		pps->ppscap |= PPS_OFFSETCLEAR;
+}
 /*
  * capture a timetamp in the pps structure
  */
 void
 pps_capture(struct pps_state *pps)
+{
 	struct timehands *th;
 	KASSERT(mutex_owned(&timecounter_lock));
 	KASSERT(pps != NULL);
 	th = timehands;
 	pps->capgen = th->th_generation;
 	pps->capth = th;
 	pps->capcount = (u_int64_t)tc_delta(th) + th->th_offset_count;
 	if (pps->capgen != th->th_generation)
 		pps->capgen = 0;
+}
 #ifdef PPS_DEBUG
 int ppsdebug = 0;
 #endif
 /*
  * process a pps_capture()ed event
  */
 void
 pps_event(struct pps_state *pps, int event)
+{
 	pps_ref_event(pps, event, NULL, PPS_REFEVNT_PPS|PPS_REFEVNT_CAPTURE);
+}
 /*
  * extended pps api /  kernel pll/fll entry point
+ *
  * feed reference time stamps to PPS engine
+ *
  * will simulate a PPS event and feed
  * the NTP PLL/FLL if requested.
+ *
  * the ref time stamps should be roughly once
  * a second but do not need to be exactly in phase
  * with the UTC second but should be close to it.
  * this relaxation of requirements allows callout
  * driven timestamping mechanisms to feed to pps
  * capture/kernel pll logic.
+ *
  * calling pattern is:
  *  pps_capture() (for PPS_REFEVNT_{CAPTURE|CAPCUR})
  *  read timestamp from reference source
  *  pps_ref_event()
+ *
  * supported refmodes:
  *  PPS_REFEVNT_CAPTURE
  *    use system timestamp of pps_capture()
  *  PPS_REFEVNT_CURRENT
  *    use system timestamp of this call
  *  PPS_REFEVNT_CAPCUR
  *    use average of read capture and current system time stamp
  *  PPS_REFEVNT_PPS
  *    assume timestamp on second mark - ref_ts is ignored
+ *
  */
 void
 pps_ref_event(struct pps_state *pps,
 	      int event,
 	      struct bintime *ref_ts,
 	      int refmode
+	)
+{
 	struct bintime bt;	/* current time */
 	struct bintime btd;	/* time difference */
 	struct bintime bt_ref;	/* reference time */
 	struct timespec ts, *tsp, *osp;
 	struct timehands *th;
 	u_int64_t tcount, acount, dcount, *pcount;
 	int foff, gen;
 #ifdef PPS_SYNC
 	int fhard;
 #endif
 	pps_seq_t *pseq;
 	KASSERT(mutex_owned(&timecounter_lock));
 	KASSERT(pps != NULL);
         /* pick up current time stamp if needed */
 	if (refmode & (PPS_REFEVNT_CURRENT|PPS_REFEVNT_CAPCUR)) {
 		/* pick up current time stamp */
 		th = timehands;
 		gen = th->th_generation;
 		tcount = (u_int64_t)tc_delta(th) + th->th_offset_count;
 		if (gen != th->th_generation)
 			gen = 0;
 		/* If the timecounter was wound up underneath us, bail out. */
 		if (pps->capgen == 0 ||
 		    pps->capgen != pps->capth->th_generation ||
 		    gen == 0 ||
 		    gen != pps->capgen) {
 #ifdef PPS_DEBUG
 			if (ppsdebug & 0x1) {
 				log(LOG_DEBUG,
 				    "pps_ref_event(pps=%p, event=%d, ...): DROP (wind-up)\n",
 				    pps, event);
+			}
 #endif
 			return;
+		}
 	} else {
 		tcount = 0;	/* keep GCC happy */
+	}
 #ifdef PPS_DEBUG
 	if (ppsdebug & 0x1) {
 		struct timespec tmsp;
 		if (ref_ts == NULL) {
 			tmsp.tv_sec = 0;
 			tmsp.tv_nsec = 0;
 		} else {
 			bintime2timespec(ref_ts, &tmsp);
+		}
 		log(LOG_DEBUG,
 		    "pps_ref_event(pps=%p, event=%d, ref_ts=%"PRIi64
 		    ".%09"PRIi32", refmode=0x%1x)\n",
 		    pps, event, tmsp.tv_sec, (int32_t)tmsp.tv_nsec, refmode);
+	}
 #endif
 	/* setup correct event references */
 	if (event == PPS_CAPTUREASSERT) {
 		tsp = &pps->ppsinfo.assert_timestamp;
 		osp = &pps->ppsparam.assert_offset;
 		foff = pps->ppsparam.mode & PPS_OFFSETASSERT;
 #ifdef PPS_SYNC
 		fhard = pps->kcmode & PPS_CAPTUREASSERT;
 #endif
 		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;
 #ifdef PPS_SYNC
 		fhard = pps->kcmode & PPS_CAPTURECLEAR;
 #endif
 		pcount = &pps->ppscount[1];
 		pseq = &pps->ppsinfo.clear_sequence;
+	}
 	/* determine system time stamp according to refmode */
 	dcount = 0;		/* keep GCC happy */
 	switch (refmode & PPS_REFEVNT_RMASK) {
 	case PPS_REFEVNT_CAPTURE:
 		acount = pps->capcount;	/* use capture timestamp */
 		break;
 	case PPS_REFEVNT_CURRENT:
 		acount = tcount; /* use current timestamp */
 		break;
 	case PPS_REFEVNT_CAPCUR:
 		/*
 		 * calculate counter value between pps_capture() and
 		 * pps_ref_event()
 		 */
 		dcount = tcount - pps->capcount;
 		acount = (dcount / 2) + pps->capcount;
 		break;
 	default:		/* ignore call error silently */
 		return;
+	}
 	/*
 	 * 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;
 		pps->capcount = acount;
 		*pcount = acount;
 		pps->ppscount[2] = acount;
 #ifdef PPS_DEBUG
 		if (ppsdebug & 0x1) {
 			log(LOG_DEBUG,
 			    "pps_ref_event(pps=%p, event=%d, ...): DROP (time-counter change)\n",
 			    pps, event);
+		}
 #endif
 		return;
+	}
 	pps->capcount = acount;
 	/* Convert the count to a bintime. */
 	bt = pps->capth->th_offset;
 	bintime_addx(&bt, pps->capth->th_scale * (acount - pps->capth->th_offset_count));
 	bintime_add(&bt, &timebasebin);
 	if ((refmode & PPS_REFEVNT_PPS) == 0) {
 		/* determine difference to reference time stamp */
 		bt_ref = *ref_ts;
 		btd = bt;
 		bintime_sub(&btd, &bt_ref);
 		/*
 		 * simulate a PPS timestamp by dropping the fraction
 		 * and applying the offset
 		 */
 		if (bt.frac >= (uint64_t)1<<63)	/* skip to nearest second */
 			bt.sec++;
 		bt.frac = 0;
 		bintime_add(&bt, &btd);
 	} else {
 		/*
 		 * create ref_ts from current time -
 		 * we are supposed to be called on
 		 * the second mark
 		 */
 		bt_ref = bt;
 		if (bt_ref.frac >= (uint64_t)1<<63)	/* skip to nearest second */
 			bt_ref.sec++;
 		bt_ref.frac = 0;
+	}
 	/* convert bintime to timestamp */
 	bintime2timespec(&bt, &ts);
 	/* If the timecounter was wound up underneath us, bail out. */
 	if (pps->capgen != pps->capth->th_generation)
 		return;
 	/* store time stamp */
 	*pcount = pps->capcount;
 	(*pseq)++;
 	*tsp = ts;
 	/* add offset correction */
 	if (foff) {
 		timespecadd(tsp, osp, tsp);
 		if (tsp->tv_nsec < 0) {
 			tsp->tv_nsec += 1000000000;
 			tsp->tv_sec -= 1;
+		}
+	}
 #ifdef PPS_DEBUG
 	if (ppsdebug & 0x2) {
 		struct timespec ts2;
 		struct timespec ts3;
 		bintime2timespec(&bt_ref, &ts2);
 		bt.sec = 0;
 		bt.frac = 0;
 		if (refmode & PPS_REFEVNT_CAPCUR) {
 			    bintime_addx(&bt, pps->capth->th_scale * dcount);
+		}
 		bintime2timespec(&bt, &ts3);
 		log(LOG_DEBUG, "ref_ts=%"PRIi64".%09"PRIi32
 		    ", ts=%"PRIi64".%09"PRIi32", read latency=%"PRIi64" ns\n",
 		    ts2.tv_sec, (int32_t)ts2.tv_nsec,
 		    tsp->tv_sec, (int32_t)tsp->tv_nsec,
 		    timespec2ns(&ts3));
+	}
 #endif
 #ifdef PPS_SYNC
 	if (fhard) {
 		uint64_t scale;
 		uint64_t div;
 		/*
 		 * Feed the NTP PLL/FLL.
 		 * The FLL wants to know how many (hardware) nanoseconds
 		 * elapsed since the previous event (mod 1 second) thus
 		 * we are actually looking at the frequency difference scaled
 		 * in nsec.
 		 * As the counter time stamps are not truly at 1Hz
 		 * we need to scale the count by the elapsed
 		 * reference time.
 		 * valid sampling interval: [0.5..2[ sec
 		 */
 		/* calculate elapsed raw count */
 		tcount = pps->capcount - pps->ppscount[2];
 		pps->ppscount[2] = pps->capcount;
 		tcount &= pps->capth->th_counter->tc_counter_mask;
 		/* calculate elapsed ref time */
 		btd = bt_ref;
 		bintime_sub(&btd, &pps->ref_time);
 		pps->ref_time = bt_ref;
 		/* check that we stay below 2 sec */
 		if (btd.sec < 0 || btd.sec > 1)
 			return;
 		/* we want at least 0.5 sec between samples */
 		if (btd.sec == 0 && btd.frac < (uint64_t)1<<63)
 			return;
 		/*
 		 * calculate cycles per period by multiplying
 		 * the frequency with the elapsed period
 		 * we pick a fraction of 30 bits
 		 * ~1ns resolution for elapsed time
 		 */
 		div   = (uint64_t)btd.sec << 30;
 		div  |= (btd.frac >> 34) & (((uint64_t)1 << 30) - 1);
 		div  *= pps->capth->th_counter->tc_frequency;
 		div >>= 30;
 		if (div == 0)	/* safeguard */
 			return;
 		scale = (uint64_t)1 << 63;
 		scale /= div;
 		scale *= 2;
 		bt.sec = 0;
 		bt.frac = 0;
 		bintime_addx(&bt, scale * tcount);
 		bintime2timespec(&bt, &ts);
 #ifdef PPS_DEBUG
 		if (ppsdebug & 0x4) {
 			struct timespec ts2;
 			int64_t df;
 			bintime2timespec(&bt_ref, &ts2);
 			df = timespec2ns(&ts);
 			if (df > 500000000)
 				df -= 1000000000;
 			log(LOG_DEBUG, "hardpps: ref_ts=%"PRIi64
 			    ".%09"PRIi32", ts=%"PRIi64".%09"PRIi32
 			    ", freqdiff=%"PRIi64" ns/s\n",
 			    ts2.tv_sec, (int32_t)ts2.tv_nsec,
 			    tsp->tv_sec, (int32_t)tsp->tv_nsec,
 			    df);
+		}
 #endif
 		hardpps(tsp, timespec2ns(&ts));
+	}
 #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;
 void
 tc_ticktock(void)
+{
 	static int count;
 	if (++count < tc_tick)
 		return;
 	count = 0;
 	mutex_spin_enter(&timecounter_lock);
 	if (timecounter_bad != 0) {
 		/* An existing timecounter has gone bad, pick a new one. */
 		(void)atomic_swap_uint(&timecounter_bad, 0);
 		if (timecounter->tc_quality < 0) {
 			tc_pick();
+		}
+	}
 	tc_windup();
 	mutex_spin_exit(&timecounter_lock);
+}
 void
 inittimecounter(void)
+{
 	u_int p;
 	mutex_init(&timecounter_lock, MUTEX_DEFAULT, IPL_HIGH);
 	/*
 	 * 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;
 	aprint_verbose("timecounter: 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);
+}