| 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 | |