1 | /* $NetBSD: kern_tc.c,v 1.46 2013/09/14 20:52:43 martin Exp $ */ |
2 | |
3 | /*- |
4 | * Copyright (c) 2008, 2009 The NetBSD Foundation, Inc. |
5 | * All rights reserved. |
6 | * |
7 | * This code is derived from software contributed to The NetBSD Foundation |
8 | * by Andrew Doran. |
9 | * |
10 | * Redistribution and use in source and binary forms, with or without |
11 | * modification, are permitted provided that the following conditions |
12 | * are met: |
13 | * 1. Redistributions of source code must retain the above copyright |
14 | * notice, this list of conditions and the following disclaimer. |
15 | * 2. Redistributions in binary form must reproduce the above copyright |
16 | * notice, this list of conditions and the following disclaimer in the |
17 | * documentation and/or other materials provided with the distribution. |
18 | * |
19 | * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS |
20 | * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED |
21 | * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR |
22 | * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS |
23 | * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR |
24 | * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF |
25 | * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS |
26 | * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN |
27 | * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) |
28 | * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE |
29 | * POSSIBILITY OF SUCH DAMAGE. |
30 | */ |
31 | |
32 | /*- |
33 | * ---------------------------------------------------------------------------- |
34 | * "THE BEER-WARE LICENSE" (Revision 42): |
35 | * <phk@FreeBSD.ORG> wrote this file. As long as you retain this notice you |
36 | * can do whatever you want with this stuff. If we meet some day, and you think |
37 | * this stuff is worth it, you can buy me a beer in return. Poul-Henning Kamp |
38 | * --------------------------------------------------------------------------- |
39 | */ |
40 | |
41 | #include <sys/cdefs.h> |
42 | /* __FBSDID("$FreeBSD: src/sys/kern/kern_tc.c,v 1.166 2005/09/19 22:16:31 andre Exp $"); */ |
43 | __KERNEL_RCSID(0, "$NetBSD: kern_tc.c,v 1.46 2013/09/14 20:52:43 martin Exp $" ); |
44 | |
45 | #ifdef _KERNEL_OPT |
46 | #include "opt_ntp.h" |
47 | #endif |
48 | |
49 | #include <sys/param.h> |
50 | #include <sys/kernel.h> |
51 | #include <sys/reboot.h> /* XXX just to get AB_VERBOSE */ |
52 | #include <sys/sysctl.h> |
53 | #include <sys/syslog.h> |
54 | #include <sys/systm.h> |
55 | #include <sys/timepps.h> |
56 | #include <sys/timetc.h> |
57 | #include <sys/timex.h> |
58 | #include <sys/evcnt.h> |
59 | #include <sys/kauth.h> |
60 | #include <sys/mutex.h> |
61 | #include <sys/atomic.h> |
62 | #include <sys/xcall.h> |
63 | |
64 | /* |
65 | * A large step happens on boot. This constant detects such steps. |
66 | * It is relatively small so that ntp_update_second gets called enough |
67 | * in the typical 'missed a couple of seconds' case, but doesn't loop |
68 | * forever when the time step is large. |
69 | */ |
70 | #define LARGE_STEP 200 |
71 | |
72 | /* |
73 | * Implement a dummy timecounter which we can use until we get a real one |
74 | * in the air. This allows the console and other early stuff to use |
75 | * time services. |
76 | */ |
77 | |
78 | static u_int |
79 | dummy_get_timecount(struct timecounter *tc) |
80 | { |
81 | static u_int now; |
82 | |
83 | return (++now); |
84 | } |
85 | |
86 | static struct timecounter dummy_timecounter = { |
87 | dummy_get_timecount, 0, ~0u, 1000000, "dummy" , -1000000, NULL, NULL, |
88 | }; |
89 | |
90 | struct timehands { |
91 | /* These fields must be initialized by the driver. */ |
92 | struct timecounter *th_counter; /* active timecounter */ |
93 | int64_t th_adjustment; /* frequency adjustment */ |
94 | /* (NTP/adjtime) */ |
95 | u_int64_t th_scale; /* scale factor (counter */ |
96 | /* tick->time) */ |
97 | u_int64_t th_offset_count; /* offset at last time */ |
98 | /* update (tc_windup()) */ |
99 | struct bintime th_offset; /* bin (up)time at windup */ |
100 | struct timeval th_microtime; /* cached microtime */ |
101 | struct timespec th_nanotime; /* cached nanotime */ |
102 | /* Fields not to be copied in tc_windup start with th_generation. */ |
103 | volatile u_int th_generation; /* current genration */ |
104 | struct timehands *th_next; /* next timehand */ |
105 | }; |
106 | |
107 | static struct timehands th0; |
108 | static struct timehands th9 = { .th_next = &th0, }; |
109 | static struct timehands th8 = { .th_next = &th9, }; |
110 | static struct timehands th7 = { .th_next = &th8, }; |
111 | static struct timehands th6 = { .th_next = &th7, }; |
112 | static struct timehands th5 = { .th_next = &th6, }; |
113 | static struct timehands th4 = { .th_next = &th5, }; |
114 | static struct timehands th3 = { .th_next = &th4, }; |
115 | static struct timehands th2 = { .th_next = &th3, }; |
116 | static struct timehands th1 = { .th_next = &th2, }; |
117 | static struct timehands th0 = { |
118 | .th_counter = &dummy_timecounter, |
119 | .th_scale = (uint64_t)-1 / 1000000, |
120 | .th_offset = { .sec = 1, .frac = 0 }, |
121 | .th_generation = 1, |
122 | .th_next = &th1, |
123 | }; |
124 | |
125 | static struct timehands *volatile timehands = &th0; |
126 | struct timecounter *timecounter = &dummy_timecounter; |
127 | static struct timecounter *timecounters = &dummy_timecounter; |
128 | |
129 | volatile time_t time_second = 1; |
130 | volatile time_t time_uptime = 1; |
131 | |
132 | static struct bintime timebasebin; |
133 | |
134 | static int timestepwarnings; |
135 | |
136 | kmutex_t timecounter_lock; |
137 | static u_int timecounter_mods; |
138 | static volatile int timecounter_removals = 1; |
139 | static u_int timecounter_bad; |
140 | |
141 | #ifdef __FreeBSD__ |
142 | SYSCTL_INT(_kern_timecounter, OID_AUTO, stepwarnings, CTLFLAG_RW, |
143 | ×tepwarnings, 0, "" ); |
144 | #endif /* __FreeBSD__ */ |
145 | |
146 | /* |
147 | * sysctl helper routine for kern.timercounter.hardware |
148 | */ |
149 | static int |
150 | sysctl_kern_timecounter_hardware(SYSCTLFN_ARGS) |
151 | { |
152 | struct sysctlnode node; |
153 | int error; |
154 | char newname[MAX_TCNAMELEN]; |
155 | struct timecounter *newtc, *tc; |
156 | |
157 | tc = timecounter; |
158 | |
159 | strlcpy(newname, tc->tc_name, sizeof(newname)); |
160 | |
161 | node = *rnode; |
162 | node.sysctl_data = newname; |
163 | node.sysctl_size = sizeof(newname); |
164 | |
165 | error = sysctl_lookup(SYSCTLFN_CALL(&node)); |
166 | |
167 | if (error || |
168 | newp == NULL || |
169 | strncmp(newname, tc->tc_name, sizeof(newname)) == 0) |
170 | return error; |
171 | |
172 | if (l != NULL && (error = kauth_authorize_system(l->l_cred, |
173 | KAUTH_SYSTEM_TIME, KAUTH_REQ_SYSTEM_TIME_TIMECOUNTERS, newname, |
174 | NULL, NULL)) != 0) |
175 | return (error); |
176 | |
177 | if (!cold) |
178 | mutex_spin_enter(&timecounter_lock); |
179 | error = EINVAL; |
180 | for (newtc = timecounters; newtc != NULL; newtc = newtc->tc_next) { |
181 | if (strcmp(newname, newtc->tc_name) != 0) |
182 | continue; |
183 | /* Warm up new timecounter. */ |
184 | (void)newtc->tc_get_timecount(newtc); |
185 | (void)newtc->tc_get_timecount(newtc); |
186 | timecounter = newtc; |
187 | error = 0; |
188 | break; |
189 | } |
190 | if (!cold) |
191 | mutex_spin_exit(&timecounter_lock); |
192 | return error; |
193 | } |
194 | |
195 | static int |
196 | sysctl_kern_timecounter_choice(SYSCTLFN_ARGS) |
197 | { |
198 | char buf[MAX_TCNAMELEN+48]; |
199 | char *where; |
200 | const char *spc; |
201 | struct timecounter *tc; |
202 | size_t needed, left, slen; |
203 | int error, mods; |
204 | |
205 | if (newp != NULL) |
206 | return (EPERM); |
207 | if (namelen != 0) |
208 | return (EINVAL); |
209 | |
210 | mutex_spin_enter(&timecounter_lock); |
211 | retry: |
212 | spc = "" ; |
213 | error = 0; |
214 | needed = 0; |
215 | left = *oldlenp; |
216 | where = oldp; |
217 | for (tc = timecounters; error == 0 && tc != NULL; tc = tc->tc_next) { |
218 | if (where == NULL) { |
219 | needed += sizeof(buf); /* be conservative */ |
220 | } else { |
221 | slen = snprintf(buf, sizeof(buf), "%s%s(q=%d, f=%" PRId64 |
222 | " Hz)" , spc, tc->tc_name, tc->tc_quality, |
223 | tc->tc_frequency); |
224 | if (left < slen + 1) |
225 | break; |
226 | mods = timecounter_mods; |
227 | mutex_spin_exit(&timecounter_lock); |
228 | error = copyout(buf, where, slen + 1); |
229 | mutex_spin_enter(&timecounter_lock); |
230 | if (mods != timecounter_mods) { |
231 | goto retry; |
232 | } |
233 | spc = " " ; |
234 | where += slen; |
235 | needed += slen; |
236 | left -= slen; |
237 | } |
238 | } |
239 | mutex_spin_exit(&timecounter_lock); |
240 | |
241 | *oldlenp = needed; |
242 | return (error); |
243 | } |
244 | |
245 | SYSCTL_SETUP(sysctl_timecounter_setup, "sysctl timecounter setup" ) |
246 | { |
247 | const struct sysctlnode *node; |
248 | |
249 | sysctl_createv(clog, 0, NULL, &node, |
250 | CTLFLAG_PERMANENT, |
251 | CTLTYPE_NODE, "timecounter" , |
252 | SYSCTL_DESCR("time counter information" ), |
253 | NULL, 0, NULL, 0, |
254 | CTL_KERN, CTL_CREATE, CTL_EOL); |
255 | |
256 | if (node != NULL) { |
257 | sysctl_createv(clog, 0, NULL, NULL, |
258 | CTLFLAG_PERMANENT, |
259 | CTLTYPE_STRING, "choice" , |
260 | SYSCTL_DESCR("available counters" ), |
261 | sysctl_kern_timecounter_choice, 0, NULL, 0, |
262 | CTL_KERN, node->sysctl_num, CTL_CREATE, CTL_EOL); |
263 | |
264 | sysctl_createv(clog, 0, NULL, NULL, |
265 | CTLFLAG_PERMANENT|CTLFLAG_READWRITE, |
266 | CTLTYPE_STRING, "hardware" , |
267 | SYSCTL_DESCR("currently active time counter" ), |
268 | sysctl_kern_timecounter_hardware, 0, NULL, MAX_TCNAMELEN, |
269 | CTL_KERN, node->sysctl_num, CTL_CREATE, CTL_EOL); |
270 | |
271 | sysctl_createv(clog, 0, NULL, NULL, |
272 | CTLFLAG_PERMANENT|CTLFLAG_READWRITE, |
273 | CTLTYPE_INT, "timestepwarnings" , |
274 | SYSCTL_DESCR("log time steps" ), |
275 | NULL, 0, ×tepwarnings, 0, |
276 | CTL_KERN, node->sysctl_num, CTL_CREATE, CTL_EOL); |
277 | } |
278 | } |
279 | |
280 | #ifdef TC_COUNTERS |
281 | #define TC_STATS(name) \ |
282 | static struct evcnt n##name = \ |
283 | EVCNT_INITIALIZER(EVCNT_TYPE_MISC, NULL, "timecounter", #name); \ |
284 | EVCNT_ATTACH_STATIC(n##name) |
285 | TC_STATS(binuptime); TC_STATS(nanouptime); TC_STATS(microuptime); |
286 | TC_STATS(bintime); TC_STATS(nanotime); TC_STATS(microtime); |
287 | TC_STATS(getbinuptime); TC_STATS(getnanouptime); TC_STATS(getmicrouptime); |
288 | TC_STATS(getbintime); TC_STATS(getnanotime); TC_STATS(getmicrotime); |
289 | TC_STATS(setclock); |
290 | #define TC_COUNT(var) var.ev_count++ |
291 | #undef TC_STATS |
292 | #else |
293 | #define TC_COUNT(var) /* nothing */ |
294 | #endif /* TC_COUNTERS */ |
295 | |
296 | static void tc_windup(void); |
297 | |
298 | /* |
299 | * Return the difference between the timehands' counter value now and what |
300 | * was when we copied it to the timehands' offset_count. |
301 | */ |
302 | static inline u_int |
303 | tc_delta(struct timehands *th) |
304 | { |
305 | struct timecounter *tc; |
306 | |
307 | tc = th->th_counter; |
308 | return ((tc->tc_get_timecount(tc) - |
309 | th->th_offset_count) & tc->tc_counter_mask); |
310 | } |
311 | |
312 | /* |
313 | * Functions for reading the time. We have to loop until we are sure that |
314 | * the timehands that we operated on was not updated under our feet. See |
315 | * the comment in <sys/timevar.h> for a description of these 12 functions. |
316 | */ |
317 | |
318 | void |
319 | binuptime(struct bintime *bt) |
320 | { |
321 | struct timehands *th; |
322 | lwp_t *l; |
323 | u_int lgen, gen; |
324 | |
325 | TC_COUNT(nbinuptime); |
326 | |
327 | /* |
328 | * Provide exclusion against tc_detach(). |
329 | * |
330 | * We record the number of timecounter removals before accessing |
331 | * timecounter state. Note that the LWP can be using multiple |
332 | * "generations" at once, due to interrupts (interrupted while in |
333 | * this function). Hardware interrupts will borrow the interrupted |
334 | * LWP's l_tcgen value for this purpose, and can themselves be |
335 | * interrupted by higher priority interrupts. In this case we need |
336 | * to ensure that the oldest generation in use is recorded. |
337 | * |
338 | * splsched() is too expensive to use, so we take care to structure |
339 | * this code in such a way that it is not required. Likewise, we |
340 | * do not disable preemption. |
341 | * |
342 | * Memory barriers are also too expensive to use for such a |
343 | * performance critical function. The good news is that we do not |
344 | * need memory barriers for this type of exclusion, as the thread |
345 | * updating timecounter_removals will issue a broadcast cross call |
346 | * before inspecting our l_tcgen value (this elides memory ordering |
347 | * issues). |
348 | */ |
349 | l = curlwp; |
350 | lgen = l->l_tcgen; |
351 | if (__predict_true(lgen == 0)) { |
352 | l->l_tcgen = timecounter_removals; |
353 | } |
354 | __insn_barrier(); |
355 | |
356 | do { |
357 | th = timehands; |
358 | gen = th->th_generation; |
359 | *bt = th->th_offset; |
360 | bintime_addx(bt, th->th_scale * tc_delta(th)); |
361 | } while (gen == 0 || gen != th->th_generation); |
362 | |
363 | __insn_barrier(); |
364 | l->l_tcgen = lgen; |
365 | } |
366 | |
367 | void |
368 | nanouptime(struct timespec *tsp) |
369 | { |
370 | struct bintime bt; |
371 | |
372 | TC_COUNT(nnanouptime); |
373 | binuptime(&bt); |
374 | bintime2timespec(&bt, tsp); |
375 | } |
376 | |
377 | void |
378 | microuptime(struct timeval *tvp) |
379 | { |
380 | struct bintime bt; |
381 | |
382 | TC_COUNT(nmicrouptime); |
383 | binuptime(&bt); |
384 | bintime2timeval(&bt, tvp); |
385 | } |
386 | |
387 | void |
388 | bintime(struct bintime *bt) |
389 | { |
390 | |
391 | TC_COUNT(nbintime); |
392 | binuptime(bt); |
393 | bintime_add(bt, &timebasebin); |
394 | } |
395 | |
396 | void |
397 | nanotime(struct timespec *tsp) |
398 | { |
399 | struct bintime bt; |
400 | |
401 | TC_COUNT(nnanotime); |
402 | bintime(&bt); |
403 | bintime2timespec(&bt, tsp); |
404 | } |
405 | |
406 | void |
407 | microtime(struct timeval *tvp) |
408 | { |
409 | struct bintime bt; |
410 | |
411 | TC_COUNT(nmicrotime); |
412 | bintime(&bt); |
413 | bintime2timeval(&bt, tvp); |
414 | } |
415 | |
416 | void |
417 | getbinuptime(struct bintime *bt) |
418 | { |
419 | struct timehands *th; |
420 | u_int gen; |
421 | |
422 | TC_COUNT(ngetbinuptime); |
423 | do { |
424 | th = timehands; |
425 | gen = th->th_generation; |
426 | *bt = th->th_offset; |
427 | } while (gen == 0 || gen != th->th_generation); |
428 | } |
429 | |
430 | void |
431 | getnanouptime(struct timespec *tsp) |
432 | { |
433 | struct timehands *th; |
434 | u_int gen; |
435 | |
436 | TC_COUNT(ngetnanouptime); |
437 | do { |
438 | th = timehands; |
439 | gen = th->th_generation; |
440 | bintime2timespec(&th->th_offset, tsp); |
441 | } while (gen == 0 || gen != th->th_generation); |
442 | } |
443 | |
444 | void |
445 | getmicrouptime(struct timeval *tvp) |
446 | { |
447 | struct timehands *th; |
448 | u_int gen; |
449 | |
450 | TC_COUNT(ngetmicrouptime); |
451 | do { |
452 | th = timehands; |
453 | gen = th->th_generation; |
454 | bintime2timeval(&th->th_offset, tvp); |
455 | } while (gen == 0 || gen != th->th_generation); |
456 | } |
457 | |
458 | void |
459 | getbintime(struct bintime *bt) |
460 | { |
461 | struct timehands *th; |
462 | u_int gen; |
463 | |
464 | TC_COUNT(ngetbintime); |
465 | do { |
466 | th = timehands; |
467 | gen = th->th_generation; |
468 | *bt = th->th_offset; |
469 | } while (gen == 0 || gen != th->th_generation); |
470 | bintime_add(bt, &timebasebin); |
471 | } |
472 | |
473 | void |
474 | getnanotime(struct timespec *tsp) |
475 | { |
476 | struct timehands *th; |
477 | u_int gen; |
478 | |
479 | TC_COUNT(ngetnanotime); |
480 | do { |
481 | th = timehands; |
482 | gen = th->th_generation; |
483 | *tsp = th->th_nanotime; |
484 | } while (gen == 0 || gen != th->th_generation); |
485 | } |
486 | |
487 | void |
488 | getmicrotime(struct timeval *tvp) |
489 | { |
490 | struct timehands *th; |
491 | u_int gen; |
492 | |
493 | TC_COUNT(ngetmicrotime); |
494 | do { |
495 | th = timehands; |
496 | gen = th->th_generation; |
497 | *tvp = th->th_microtime; |
498 | } while (gen == 0 || gen != th->th_generation); |
499 | } |
500 | |
501 | /* |
502 | * Initialize a new timecounter and possibly use it. |
503 | */ |
504 | void |
505 | tc_init(struct timecounter *tc) |
506 | { |
507 | u_int u; |
508 | |
509 | u = tc->tc_frequency / tc->tc_counter_mask; |
510 | /* XXX: We need some margin here, 10% is a guess */ |
511 | u *= 11; |
512 | u /= 10; |
513 | if (u > hz && tc->tc_quality >= 0) { |
514 | tc->tc_quality = -2000; |
515 | aprint_verbose( |
516 | "timecounter: Timecounter \"%s\" frequency %ju Hz" , |
517 | tc->tc_name, (uintmax_t)tc->tc_frequency); |
518 | aprint_verbose(" -- Insufficient hz, needs at least %u\n" , u); |
519 | } else if (tc->tc_quality >= 0 || bootverbose) { |
520 | aprint_verbose( |
521 | "timecounter: Timecounter \"%s\" frequency %ju Hz " |
522 | "quality %d\n" , tc->tc_name, (uintmax_t)tc->tc_frequency, |
523 | tc->tc_quality); |
524 | } |
525 | |
526 | mutex_spin_enter(&timecounter_lock); |
527 | tc->tc_next = timecounters; |
528 | timecounters = tc; |
529 | timecounter_mods++; |
530 | /* |
531 | * Never automatically use a timecounter with negative quality. |
532 | * Even though we run on the dummy counter, switching here may be |
533 | * worse since this timecounter may not be monotonous. |
534 | */ |
535 | if (tc->tc_quality >= 0 && (tc->tc_quality > timecounter->tc_quality || |
536 | (tc->tc_quality == timecounter->tc_quality && |
537 | tc->tc_frequency > timecounter->tc_frequency))) { |
538 | (void)tc->tc_get_timecount(tc); |
539 | (void)tc->tc_get_timecount(tc); |
540 | timecounter = tc; |
541 | tc_windup(); |
542 | } |
543 | mutex_spin_exit(&timecounter_lock); |
544 | } |
545 | |
546 | /* |
547 | * Pick a new timecounter due to the existing counter going bad. |
548 | */ |
549 | static void |
550 | tc_pick(void) |
551 | { |
552 | struct timecounter *best, *tc; |
553 | |
554 | KASSERT(mutex_owned(&timecounter_lock)); |
555 | |
556 | for (best = tc = timecounters; tc != NULL; tc = tc->tc_next) { |
557 | if (tc->tc_quality > best->tc_quality) |
558 | best = tc; |
559 | else if (tc->tc_quality < best->tc_quality) |
560 | continue; |
561 | else if (tc->tc_frequency > best->tc_frequency) |
562 | best = tc; |
563 | } |
564 | (void)best->tc_get_timecount(best); |
565 | (void)best->tc_get_timecount(best); |
566 | timecounter = best; |
567 | } |
568 | |
569 | /* |
570 | * A timecounter has gone bad, arrange to pick a new one at the next |
571 | * clock tick. |
572 | */ |
573 | void |
574 | tc_gonebad(struct timecounter *tc) |
575 | { |
576 | |
577 | tc->tc_quality = -100; |
578 | membar_producer(); |
579 | atomic_inc_uint(&timecounter_bad); |
580 | } |
581 | |
582 | /* |
583 | * Stop using a timecounter and remove it from the timecounters list. |
584 | */ |
585 | int |
586 | tc_detach(struct timecounter *target) |
587 | { |
588 | struct timecounter *tc; |
589 | struct timecounter **tcp = NULL; |
590 | int removals; |
591 | uint64_t where; |
592 | lwp_t *l; |
593 | |
594 | /* First, find the timecounter. */ |
595 | mutex_spin_enter(&timecounter_lock); |
596 | for (tcp = &timecounters, tc = timecounters; |
597 | tc != NULL; |
598 | tcp = &tc->tc_next, tc = tc->tc_next) { |
599 | if (tc == target) |
600 | break; |
601 | } |
602 | if (tc == NULL) { |
603 | mutex_spin_exit(&timecounter_lock); |
604 | return ESRCH; |
605 | } |
606 | |
607 | /* And now, remove it. */ |
608 | *tcp = tc->tc_next; |
609 | if (timecounter == target) { |
610 | tc_pick(); |
611 | tc_windup(); |
612 | } |
613 | timecounter_mods++; |
614 | removals = timecounter_removals++; |
615 | mutex_spin_exit(&timecounter_lock); |
616 | |
617 | /* |
618 | * We now have to determine if any threads in the system are still |
619 | * making use of this timecounter. |
620 | * |
621 | * We issue a broadcast cross call to elide memory ordering issues, |
622 | * then scan all LWPs in the system looking at each's timecounter |
623 | * generation number. We need to see a value of zero (not actively |
624 | * using a timecounter) or a value greater than our removal value. |
625 | * |
626 | * We may race with threads that read `timecounter_removals' and |
627 | * and then get preempted before updating `l_tcgen'. This is not |
628 | * a problem, since it means that these threads have not yet started |
629 | * accessing timecounter state. All we do need is one clean |
630 | * snapshot of the system where every thread appears not to be using |
631 | * old timecounter state. |
632 | */ |
633 | for (;;) { |
634 | where = xc_broadcast(0, (xcfunc_t)nullop, NULL, NULL); |
635 | xc_wait(where); |
636 | |
637 | mutex_enter(proc_lock); |
638 | LIST_FOREACH(l, &alllwp, l_list) { |
639 | if (l->l_tcgen == 0 || l->l_tcgen > removals) { |
640 | /* |
641 | * Not using timecounter or old timecounter |
642 | * state at time of our xcall or later. |
643 | */ |
644 | continue; |
645 | } |
646 | break; |
647 | } |
648 | mutex_exit(proc_lock); |
649 | |
650 | /* |
651 | * If the timecounter is still in use, wait at least 10ms |
652 | * before retrying. |
653 | */ |
654 | if (l == NULL) { |
655 | return 0; |
656 | } |
657 | (void)kpause("tcdetach" , false, mstohz(10), NULL); |
658 | } |
659 | } |
660 | |
661 | /* Report the frequency of the current timecounter. */ |
662 | u_int64_t |
663 | tc_getfrequency(void) |
664 | { |
665 | |
666 | return (timehands->th_counter->tc_frequency); |
667 | } |
668 | |
669 | /* |
670 | * Step our concept of UTC. This is done by modifying our estimate of |
671 | * when we booted. |
672 | */ |
673 | void |
674 | tc_setclock(const struct timespec *ts) |
675 | { |
676 | struct timespec ts2; |
677 | struct bintime bt, bt2; |
678 | |
679 | mutex_spin_enter(&timecounter_lock); |
680 | TC_COUNT(nsetclock); |
681 | binuptime(&bt2); |
682 | timespec2bintime(ts, &bt); |
683 | bintime_sub(&bt, &bt2); |
684 | bintime_add(&bt2, &timebasebin); |
685 | timebasebin = bt; |
686 | tc_windup(); |
687 | mutex_spin_exit(&timecounter_lock); |
688 | |
689 | if (timestepwarnings) { |
690 | bintime2timespec(&bt2, &ts2); |
691 | log(LOG_INFO, |
692 | "Time stepped from %lld.%09ld to %lld.%09ld\n" , |
693 | (long long)ts2.tv_sec, ts2.tv_nsec, |
694 | (long long)ts->tv_sec, ts->tv_nsec); |
695 | } |
696 | } |
697 | |
698 | /* |
699 | * Initialize the next struct timehands in the ring and make |
700 | * it the active timehands. Along the way we might switch to a different |
701 | * timecounter and/or do seconds processing in NTP. Slightly magic. |
702 | */ |
703 | static void |
704 | tc_windup(void) |
705 | { |
706 | struct bintime bt; |
707 | struct timehands *th, *tho; |
708 | u_int64_t scale; |
709 | u_int delta, ncount, ogen; |
710 | int i, s_update; |
711 | time_t t; |
712 | |
713 | KASSERT(mutex_owned(&timecounter_lock)); |
714 | |
715 | s_update = 0; |
716 | |
717 | /* |
718 | * Make the next timehands a copy of the current one, but do not |
719 | * overwrite the generation or next pointer. While we update |
720 | * the contents, the generation must be zero. Ensure global |
721 | * visibility of the generation before proceeding. |
722 | */ |
723 | tho = timehands; |
724 | th = tho->th_next; |
725 | ogen = th->th_generation; |
726 | th->th_generation = 0; |
727 | membar_producer(); |
728 | bcopy(tho, th, offsetof(struct timehands, th_generation)); |
729 | |
730 | /* |
731 | * Capture a timecounter delta on the current timecounter and if |
732 | * changing timecounters, a counter value from the new timecounter. |
733 | * Update the offset fields accordingly. |
734 | */ |
735 | delta = tc_delta(th); |
736 | if (th->th_counter != timecounter) |
737 | ncount = timecounter->tc_get_timecount(timecounter); |
738 | else |
739 | ncount = 0; |
740 | th->th_offset_count += delta; |
741 | bintime_addx(&th->th_offset, th->th_scale * delta); |
742 | |
743 | /* |
744 | * Hardware latching timecounters may not generate interrupts on |
745 | * PPS events, so instead we poll them. There is a finite risk that |
746 | * the hardware might capture a count which is later than the one we |
747 | * got above, and therefore possibly in the next NTP second which might |
748 | * have a different rate than the current NTP second. It doesn't |
749 | * matter in practice. |
750 | */ |
751 | if (tho->th_counter->tc_poll_pps) |
752 | tho->th_counter->tc_poll_pps(tho->th_counter); |
753 | |
754 | /* |
755 | * Deal with NTP second processing. The for loop normally |
756 | * iterates at most once, but in extreme situations it might |
757 | * keep NTP sane if timeouts are not run for several seconds. |
758 | * At boot, the time step can be large when the TOD hardware |
759 | * has been read, so on really large steps, we call |
760 | * ntp_update_second only twice. We need to call it twice in |
761 | * case we missed a leap second. |
762 | * If NTP is not compiled in ntp_update_second still calculates |
763 | * the adjustment resulting from adjtime() calls. |
764 | */ |
765 | bt = th->th_offset; |
766 | bintime_add(&bt, &timebasebin); |
767 | i = bt.sec - tho->th_microtime.tv_sec; |
768 | if (i > LARGE_STEP) |
769 | i = 2; |
770 | for (; i > 0; i--) { |
771 | t = bt.sec; |
772 | ntp_update_second(&th->th_adjustment, &bt.sec); |
773 | s_update = 1; |
774 | if (bt.sec != t) |
775 | timebasebin.sec += bt.sec - t; |
776 | } |
777 | |
778 | /* Update the UTC timestamps used by the get*() functions. */ |
779 | /* XXX shouldn't do this here. Should force non-`get' versions. */ |
780 | bintime2timeval(&bt, &th->th_microtime); |
781 | bintime2timespec(&bt, &th->th_nanotime); |
782 | /* Now is a good time to change timecounters. */ |
783 | if (th->th_counter != timecounter) { |
784 | th->th_counter = timecounter; |
785 | th->th_offset_count = ncount; |
786 | s_update = 1; |
787 | } |
788 | |
789 | /*- |
790 | * Recalculate the scaling factor. We want the number of 1/2^64 |
791 | * fractions of a second per period of the hardware counter, taking |
792 | * into account the th_adjustment factor which the NTP PLL/adjtime(2) |
793 | * processing provides us with. |
794 | * |
795 | * The th_adjustment is nanoseconds per second with 32 bit binary |
796 | * fraction and we want 64 bit binary fraction of second: |
797 | * |
798 | * x = a * 2^32 / 10^9 = a * 4.294967296 |
799 | * |
800 | * The range of th_adjustment is +/- 5000PPM so inside a 64bit int |
801 | * we can only multiply by about 850 without overflowing, but that |
802 | * leaves suitably precise fractions for multiply before divide. |
803 | * |
804 | * Divide before multiply with a fraction of 2199/512 results in a |
805 | * systematic undercompensation of 10PPM of th_adjustment. On a |
806 | * 5000PPM adjustment this is a 0.05PPM error. This is acceptable. |
807 | * |
808 | * We happily sacrifice the lowest of the 64 bits of our result |
809 | * to the goddess of code clarity. |
810 | * |
811 | */ |
812 | if (s_update) { |
813 | scale = (u_int64_t)1 << 63; |
814 | scale += (th->th_adjustment / 1024) * 2199; |
815 | scale /= th->th_counter->tc_frequency; |
816 | th->th_scale = scale * 2; |
817 | } |
818 | /* |
819 | * Now that the struct timehands is again consistent, set the new |
820 | * generation number, making sure to not make it zero. Ensure |
821 | * changes are globally visible before changing. |
822 | */ |
823 | if (++ogen == 0) |
824 | ogen = 1; |
825 | membar_producer(); |
826 | th->th_generation = ogen; |
827 | |
828 | /* |
829 | * Go live with the new struct timehands. Ensure changes are |
830 | * globally visible before changing. |
831 | */ |
832 | time_second = th->th_microtime.tv_sec; |
833 | time_uptime = th->th_offset.sec; |
834 | membar_producer(); |
835 | timehands = th; |
836 | |
837 | /* |
838 | * Force users of the old timehand to move on. This is |
839 | * necessary for MP systems; we need to ensure that the |
840 | * consumers will move away from the old timehand before |
841 | * we begin updating it again when we eventually wrap |
842 | * around. |
843 | */ |
844 | if (++tho->th_generation == 0) |
845 | tho->th_generation = 1; |
846 | } |
847 | |
848 | /* |
849 | * RFC 2783 PPS-API implementation. |
850 | */ |
851 | |
852 | int |
853 | pps_ioctl(u_long cmd, void *data, struct pps_state *pps) |
854 | { |
855 | pps_params_t *app; |
856 | pps_info_t *pipi; |
857 | #ifdef PPS_SYNC |
858 | int *epi; |
859 | #endif |
860 | |
861 | KASSERT(mutex_owned(&timecounter_lock)); |
862 | |
863 | KASSERT(pps != NULL); |
864 | |
865 | switch (cmd) { |
866 | case PPS_IOC_CREATE: |
867 | return (0); |
868 | case PPS_IOC_DESTROY: |
869 | return (0); |
870 | case PPS_IOC_SETPARAMS: |
871 | app = (pps_params_t *)data; |
872 | if (app->mode & ~pps->ppscap) |
873 | return (EINVAL); |
874 | pps->ppsparam = *app; |
875 | return (0); |
876 | case PPS_IOC_GETPARAMS: |
877 | app = (pps_params_t *)data; |
878 | *app = pps->ppsparam; |
879 | app->api_version = PPS_API_VERS_1; |
880 | return (0); |
881 | case PPS_IOC_GETCAP: |
882 | *(int*)data = pps->ppscap; |
883 | return (0); |
884 | case PPS_IOC_FETCH: |
885 | pipi = (pps_info_t *)data; |
886 | pps->ppsinfo.current_mode = pps->ppsparam.mode; |
887 | *pipi = pps->ppsinfo; |
888 | return (0); |
889 | case PPS_IOC_KCBIND: |
890 | #ifdef PPS_SYNC |
891 | epi = (int *)data; |
892 | /* XXX Only root should be able to do this */ |
893 | if (*epi & ~pps->ppscap) |
894 | return (EINVAL); |
895 | pps->kcmode = *epi; |
896 | return (0); |
897 | #else |
898 | return (EOPNOTSUPP); |
899 | #endif |
900 | default: |
901 | return (EPASSTHROUGH); |
902 | } |
903 | } |
904 | |
905 | void |
906 | pps_init(struct pps_state *pps) |
907 | { |
908 | |
909 | KASSERT(mutex_owned(&timecounter_lock)); |
910 | |
911 | pps->ppscap |= PPS_TSFMT_TSPEC; |
912 | if (pps->ppscap & PPS_CAPTUREASSERT) |
913 | pps->ppscap |= PPS_OFFSETASSERT; |
914 | if (pps->ppscap & PPS_CAPTURECLEAR) |
915 | pps->ppscap |= PPS_OFFSETCLEAR; |
916 | } |
917 | |
918 | /* |
919 | * capture a timetamp in the pps structure |
920 | */ |
921 | void |
922 | pps_capture(struct pps_state *pps) |
923 | { |
924 | struct timehands *th; |
925 | |
926 | KASSERT(mutex_owned(&timecounter_lock)); |
927 | KASSERT(pps != NULL); |
928 | |
929 | th = timehands; |
930 | pps->capgen = th->th_generation; |
931 | pps->capth = th; |
932 | pps->capcount = (u_int64_t)tc_delta(th) + th->th_offset_count; |
933 | if (pps->capgen != th->th_generation) |
934 | pps->capgen = 0; |
935 | } |
936 | |
937 | #ifdef PPS_DEBUG |
938 | int ppsdebug = 0; |
939 | #endif |
940 | |
941 | /* |
942 | * process a pps_capture()ed event |
943 | */ |
944 | void |
945 | pps_event(struct pps_state *pps, int event) |
946 | { |
947 | pps_ref_event(pps, event, NULL, PPS_REFEVNT_PPS|PPS_REFEVNT_CAPTURE); |
948 | } |
949 | |
950 | /* |
951 | * extended pps api / kernel pll/fll entry point |
952 | * |
953 | * feed reference time stamps to PPS engine |
954 | * |
955 | * will simulate a PPS event and feed |
956 | * the NTP PLL/FLL if requested. |
957 | * |
958 | * the ref time stamps should be roughly once |
959 | * a second but do not need to be exactly in phase |
960 | * with the UTC second but should be close to it. |
961 | * this relaxation of requirements allows callout |
962 | * driven timestamping mechanisms to feed to pps |
963 | * capture/kernel pll logic. |
964 | * |
965 | * calling pattern is: |
966 | * pps_capture() (for PPS_REFEVNT_{CAPTURE|CAPCUR}) |
967 | * read timestamp from reference source |
968 | * pps_ref_event() |
969 | * |
970 | * supported refmodes: |
971 | * PPS_REFEVNT_CAPTURE |
972 | * use system timestamp of pps_capture() |
973 | * PPS_REFEVNT_CURRENT |
974 | * use system timestamp of this call |
975 | * PPS_REFEVNT_CAPCUR |
976 | * use average of read capture and current system time stamp |
977 | * PPS_REFEVNT_PPS |
978 | * assume timestamp on second mark - ref_ts is ignored |
979 | * |
980 | */ |
981 | |
982 | void |
983 | pps_ref_event(struct pps_state *pps, |
984 | int event, |
985 | struct bintime *ref_ts, |
986 | int refmode |
987 | ) |
988 | { |
989 | struct bintime bt; /* current time */ |
990 | struct bintime btd; /* time difference */ |
991 | struct bintime bt_ref; /* reference time */ |
992 | struct timespec ts, *tsp, *osp; |
993 | struct timehands *th; |
994 | u_int64_t tcount, acount, dcount, *pcount; |
995 | int foff, gen; |
996 | #ifdef PPS_SYNC |
997 | int fhard; |
998 | #endif |
999 | pps_seq_t *pseq; |
1000 | |
1001 | KASSERT(mutex_owned(&timecounter_lock)); |
1002 | |
1003 | KASSERT(pps != NULL); |
1004 | |
1005 | /* pick up current time stamp if needed */ |
1006 | if (refmode & (PPS_REFEVNT_CURRENT|PPS_REFEVNT_CAPCUR)) { |
1007 | /* pick up current time stamp */ |
1008 | th = timehands; |
1009 | gen = th->th_generation; |
1010 | tcount = (u_int64_t)tc_delta(th) + th->th_offset_count; |
1011 | if (gen != th->th_generation) |
1012 | gen = 0; |
1013 | |
1014 | /* If the timecounter was wound up underneath us, bail out. */ |
1015 | if (pps->capgen == 0 || |
1016 | pps->capgen != pps->capth->th_generation || |
1017 | gen == 0 || |
1018 | gen != pps->capgen) { |
1019 | #ifdef PPS_DEBUG |
1020 | if (ppsdebug & 0x1) { |
1021 | log(LOG_DEBUG, |
1022 | "pps_ref_event(pps=%p, event=%d, ...): DROP (wind-up)\n" , |
1023 | pps, event); |
1024 | } |
1025 | #endif |
1026 | return; |
1027 | } |
1028 | } else { |
1029 | tcount = 0; /* keep GCC happy */ |
1030 | } |
1031 | |
1032 | #ifdef PPS_DEBUG |
1033 | if (ppsdebug & 0x1) { |
1034 | struct timespec tmsp; |
1035 | |
1036 | if (ref_ts == NULL) { |
1037 | tmsp.tv_sec = 0; |
1038 | tmsp.tv_nsec = 0; |
1039 | } else { |
1040 | bintime2timespec(ref_ts, &tmsp); |
1041 | } |
1042 | |
1043 | log(LOG_DEBUG, |
1044 | "pps_ref_event(pps=%p, event=%d, ref_ts=%" PRIi64 |
1045 | ".%09" PRIi32", refmode=0x%1x)\n" , |
1046 | pps, event, tmsp.tv_sec, (int32_t)tmsp.tv_nsec, refmode); |
1047 | } |
1048 | #endif |
1049 | |
1050 | /* setup correct event references */ |
1051 | if (event == PPS_CAPTUREASSERT) { |
1052 | tsp = &pps->ppsinfo.assert_timestamp; |
1053 | osp = &pps->ppsparam.assert_offset; |
1054 | foff = pps->ppsparam.mode & PPS_OFFSETASSERT; |
1055 | #ifdef PPS_SYNC |
1056 | fhard = pps->kcmode & PPS_CAPTUREASSERT; |
1057 | #endif |
1058 | pcount = &pps->ppscount[0]; |
1059 | pseq = &pps->ppsinfo.assert_sequence; |
1060 | } else { |
1061 | tsp = &pps->ppsinfo.clear_timestamp; |
1062 | osp = &pps->ppsparam.clear_offset; |
1063 | foff = pps->ppsparam.mode & PPS_OFFSETCLEAR; |
1064 | #ifdef PPS_SYNC |
1065 | fhard = pps->kcmode & PPS_CAPTURECLEAR; |
1066 | #endif |
1067 | pcount = &pps->ppscount[1]; |
1068 | pseq = &pps->ppsinfo.clear_sequence; |
1069 | } |
1070 | |
1071 | /* determine system time stamp according to refmode */ |
1072 | dcount = 0; /* keep GCC happy */ |
1073 | switch (refmode & PPS_REFEVNT_RMASK) { |
1074 | case PPS_REFEVNT_CAPTURE: |
1075 | acount = pps->capcount; /* use capture timestamp */ |
1076 | break; |
1077 | |
1078 | case PPS_REFEVNT_CURRENT: |
1079 | acount = tcount; /* use current timestamp */ |
1080 | break; |
1081 | |
1082 | case PPS_REFEVNT_CAPCUR: |
1083 | /* |
1084 | * calculate counter value between pps_capture() and |
1085 | * pps_ref_event() |
1086 | */ |
1087 | dcount = tcount - pps->capcount; |
1088 | acount = (dcount / 2) + pps->capcount; |
1089 | break; |
1090 | |
1091 | default: /* ignore call error silently */ |
1092 | return; |
1093 | } |
1094 | |
1095 | /* |
1096 | * If the timecounter changed, we cannot compare the count values, so |
1097 | * we have to drop the rest of the PPS-stuff until the next event. |
1098 | */ |
1099 | if (pps->ppstc != pps->capth->th_counter) { |
1100 | pps->ppstc = pps->capth->th_counter; |
1101 | pps->capcount = acount; |
1102 | *pcount = acount; |
1103 | pps->ppscount[2] = acount; |
1104 | #ifdef PPS_DEBUG |
1105 | if (ppsdebug & 0x1) { |
1106 | log(LOG_DEBUG, |
1107 | "pps_ref_event(pps=%p, event=%d, ...): DROP (time-counter change)\n" , |
1108 | pps, event); |
1109 | } |
1110 | #endif |
1111 | return; |
1112 | } |
1113 | |
1114 | pps->capcount = acount; |
1115 | |
1116 | /* Convert the count to a bintime. */ |
1117 | bt = pps->capth->th_offset; |
1118 | bintime_addx(&bt, pps->capth->th_scale * (acount - pps->capth->th_offset_count)); |
1119 | bintime_add(&bt, &timebasebin); |
1120 | |
1121 | if ((refmode & PPS_REFEVNT_PPS) == 0) { |
1122 | /* determine difference to reference time stamp */ |
1123 | bt_ref = *ref_ts; |
1124 | |
1125 | btd = bt; |
1126 | bintime_sub(&btd, &bt_ref); |
1127 | |
1128 | /* |
1129 | * simulate a PPS timestamp by dropping the fraction |
1130 | * and applying the offset |
1131 | */ |
1132 | if (bt.frac >= (uint64_t)1<<63) /* skip to nearest second */ |
1133 | bt.sec++; |
1134 | bt.frac = 0; |
1135 | bintime_add(&bt, &btd); |
1136 | } else { |
1137 | /* |
1138 | * create ref_ts from current time - |
1139 | * we are supposed to be called on |
1140 | * the second mark |
1141 | */ |
1142 | bt_ref = bt; |
1143 | if (bt_ref.frac >= (uint64_t)1<<63) /* skip to nearest second */ |
1144 | bt_ref.sec++; |
1145 | bt_ref.frac = 0; |
1146 | } |
1147 | |
1148 | /* convert bintime to timestamp */ |
1149 | bintime2timespec(&bt, &ts); |
1150 | |
1151 | /* If the timecounter was wound up underneath us, bail out. */ |
1152 | if (pps->capgen != pps->capth->th_generation) |
1153 | return; |
1154 | |
1155 | /* store time stamp */ |
1156 | *pcount = pps->capcount; |
1157 | (*pseq)++; |
1158 | *tsp = ts; |
1159 | |
1160 | /* add offset correction */ |
1161 | if (foff) { |
1162 | timespecadd(tsp, osp, tsp); |
1163 | if (tsp->tv_nsec < 0) { |
1164 | tsp->tv_nsec += 1000000000; |
1165 | tsp->tv_sec -= 1; |
1166 | } |
1167 | } |
1168 | |
1169 | #ifdef PPS_DEBUG |
1170 | if (ppsdebug & 0x2) { |
1171 | struct timespec ts2; |
1172 | struct timespec ts3; |
1173 | |
1174 | bintime2timespec(&bt_ref, &ts2); |
1175 | |
1176 | bt.sec = 0; |
1177 | bt.frac = 0; |
1178 | |
1179 | if (refmode & PPS_REFEVNT_CAPCUR) { |
1180 | bintime_addx(&bt, pps->capth->th_scale * dcount); |
1181 | } |
1182 | bintime2timespec(&bt, &ts3); |
1183 | |
1184 | log(LOG_DEBUG, "ref_ts=%" PRIi64".%09" PRIi32 |
1185 | ", ts=%" PRIi64".%09" PRIi32", read latency=%" PRIi64" ns\n" , |
1186 | ts2.tv_sec, (int32_t)ts2.tv_nsec, |
1187 | tsp->tv_sec, (int32_t)tsp->tv_nsec, |
1188 | timespec2ns(&ts3)); |
1189 | } |
1190 | #endif |
1191 | |
1192 | #ifdef PPS_SYNC |
1193 | if (fhard) { |
1194 | uint64_t scale; |
1195 | uint64_t div; |
1196 | |
1197 | /* |
1198 | * Feed the NTP PLL/FLL. |
1199 | * The FLL wants to know how many (hardware) nanoseconds |
1200 | * elapsed since the previous event (mod 1 second) thus |
1201 | * we are actually looking at the frequency difference scaled |
1202 | * in nsec. |
1203 | * As the counter time stamps are not truly at 1Hz |
1204 | * we need to scale the count by the elapsed |
1205 | * reference time. |
1206 | * valid sampling interval: [0.5..2[ sec |
1207 | */ |
1208 | |
1209 | /* calculate elapsed raw count */ |
1210 | tcount = pps->capcount - pps->ppscount[2]; |
1211 | pps->ppscount[2] = pps->capcount; |
1212 | tcount &= pps->capth->th_counter->tc_counter_mask; |
1213 | |
1214 | /* calculate elapsed ref time */ |
1215 | btd = bt_ref; |
1216 | bintime_sub(&btd, &pps->ref_time); |
1217 | pps->ref_time = bt_ref; |
1218 | |
1219 | /* check that we stay below 2 sec */ |
1220 | if (btd.sec < 0 || btd.sec > 1) |
1221 | return; |
1222 | |
1223 | /* we want at least 0.5 sec between samples */ |
1224 | if (btd.sec == 0 && btd.frac < (uint64_t)1<<63) |
1225 | return; |
1226 | |
1227 | /* |
1228 | * calculate cycles per period by multiplying |
1229 | * the frequency with the elapsed period |
1230 | * we pick a fraction of 30 bits |
1231 | * ~1ns resolution for elapsed time |
1232 | */ |
1233 | div = (uint64_t)btd.sec << 30; |
1234 | div |= (btd.frac >> 34) & (((uint64_t)1 << 30) - 1); |
1235 | div *= pps->capth->th_counter->tc_frequency; |
1236 | div >>= 30; |
1237 | |
1238 | if (div == 0) /* safeguard */ |
1239 | return; |
1240 | |
1241 | scale = (uint64_t)1 << 63; |
1242 | scale /= div; |
1243 | scale *= 2; |
1244 | |
1245 | bt.sec = 0; |
1246 | bt.frac = 0; |
1247 | bintime_addx(&bt, scale * tcount); |
1248 | bintime2timespec(&bt, &ts); |
1249 | |
1250 | #ifdef PPS_DEBUG |
1251 | if (ppsdebug & 0x4) { |
1252 | struct timespec ts2; |
1253 | int64_t df; |
1254 | |
1255 | bintime2timespec(&bt_ref, &ts2); |
1256 | df = timespec2ns(&ts); |
1257 | if (df > 500000000) |
1258 | df -= 1000000000; |
1259 | log(LOG_DEBUG, "hardpps: ref_ts=%" PRIi64 |
1260 | ".%09" PRIi32", ts=%" PRIi64".%09" PRIi32 |
1261 | ", freqdiff=%" PRIi64" ns/s\n" , |
1262 | ts2.tv_sec, (int32_t)ts2.tv_nsec, |
1263 | tsp->tv_sec, (int32_t)tsp->tv_nsec, |
1264 | df); |
1265 | } |
1266 | #endif |
1267 | |
1268 | hardpps(tsp, timespec2ns(&ts)); |
1269 | } |
1270 | #endif |
1271 | } |
1272 | |
1273 | /* |
1274 | * Timecounters need to be updated every so often to prevent the hardware |
1275 | * counter from overflowing. Updating also recalculates the cached values |
1276 | * used by the get*() family of functions, so their precision depends on |
1277 | * the update frequency. |
1278 | */ |
1279 | |
1280 | static int tc_tick; |
1281 | |
1282 | void |
1283 | tc_ticktock(void) |
1284 | { |
1285 | static int count; |
1286 | |
1287 | if (++count < tc_tick) |
1288 | return; |
1289 | count = 0; |
1290 | mutex_spin_enter(&timecounter_lock); |
1291 | if (timecounter_bad != 0) { |
1292 | /* An existing timecounter has gone bad, pick a new one. */ |
1293 | (void)atomic_swap_uint(&timecounter_bad, 0); |
1294 | if (timecounter->tc_quality < 0) { |
1295 | tc_pick(); |
1296 | } |
1297 | } |
1298 | tc_windup(); |
1299 | mutex_spin_exit(&timecounter_lock); |
1300 | } |
1301 | |
1302 | void |
1303 | inittimecounter(void) |
1304 | { |
1305 | u_int p; |
1306 | |
1307 | mutex_init(&timecounter_lock, MUTEX_DEFAULT, IPL_HIGH); |
1308 | |
1309 | /* |
1310 | * Set the initial timeout to |
1311 | * max(1, <approx. number of hardclock ticks in a millisecond>). |
1312 | * People should probably not use the sysctl to set the timeout |
1313 | * to smaller than its inital value, since that value is the |
1314 | * smallest reasonable one. If they want better timestamps they |
1315 | * should use the non-"get"* functions. |
1316 | */ |
1317 | if (hz > 1000) |
1318 | tc_tick = (hz + 500) / 1000; |
1319 | else |
1320 | tc_tick = 1; |
1321 | p = (tc_tick * 1000000) / hz; |
1322 | aprint_verbose("timecounter: Timecounters tick every %d.%03u msec\n" , |
1323 | p / 1000, p % 1000); |
1324 | |
1325 | /* warm up new timecounter (again) and get rolling. */ |
1326 | (void)timecounter->tc_get_timecount(timecounter); |
1327 | (void)timecounter->tc_get_timecount(timecounter); |
1328 | } |
1329 | |