Commit | Line | Data |
---|---|---|
4c7ee8de | 1 | /* |
4c7ee8de | 2 | * NTP state machine interfaces and logic. |
3 | * | |
4 | * This code was mainly moved from kernel/timer.c and kernel/time.c | |
5 | * Please see those files for relevant copyright info and historical | |
6 | * changelogs. | |
7 | */ | |
aa0ac365 | 8 | #include <linux/capability.h> |
7dffa3c6 | 9 | #include <linux/clocksource.h> |
eb3f938f | 10 | #include <linux/workqueue.h> |
53bbfa9e IM |
11 | #include <linux/hrtimer.h> |
12 | #include <linux/jiffies.h> | |
13 | #include <linux/math64.h> | |
14 | #include <linux/timex.h> | |
15 | #include <linux/time.h> | |
16 | #include <linux/mm.h> | |
4c7ee8de | 17 | |
b0ee7556 | 18 | /* |
53bbfa9e | 19 | * NTP timekeeping variables: |
b0ee7556 | 20 | */ |
b0ee7556 | 21 | |
53bbfa9e IM |
22 | /* USER_HZ period (usecs): */ |
23 | unsigned long tick_usec = TICK_USEC; | |
24 | ||
25 | /* ACTHZ period (nsecs): */ | |
26 | unsigned long tick_nsec; | |
7dffa3c6 | 27 | |
53bbfa9e IM |
28 | u64 tick_length; |
29 | static u64 tick_length_base; | |
30 | ||
31 | static struct hrtimer leap_timer; | |
32 | ||
bbd12676 | 33 | #define MAX_TICKADJ 500LL /* usecs */ |
53bbfa9e | 34 | #define MAX_TICKADJ_SCALED \ |
bbd12676 | 35 | (((MAX_TICKADJ * NSEC_PER_USEC) << NTP_SCALE_SHIFT) / NTP_INTERVAL_FREQ) |
4c7ee8de | 36 | |
37 | /* | |
38 | * phase-lock loop variables | |
39 | */ | |
53bbfa9e IM |
40 | |
41 | /* | |
42 | * clock synchronization status | |
43 | * | |
44 | * (TIME_ERROR prevents overwriting the CMOS clock) | |
45 | */ | |
46 | static int time_state = TIME_OK; | |
47 | ||
48 | /* clock status bits: */ | |
49 | int time_status = STA_UNSYNC; | |
50 | ||
51 | /* TAI offset (secs): */ | |
52 | static long time_tai; | |
53 | ||
54 | /* time adjustment (nsecs): */ | |
55 | static s64 time_offset; | |
56 | ||
57 | /* pll time constant: */ | |
58 | static long time_constant = 2; | |
59 | ||
60 | /* maximum error (usecs): */ | |
61 | long time_maxerror = NTP_PHASE_LIMIT; | |
62 | ||
63 | /* estimated error (usecs): */ | |
64 | long time_esterror = NTP_PHASE_LIMIT; | |
65 | ||
66 | /* frequency offset (scaled nsecs/secs): */ | |
67 | static s64 time_freq; | |
68 | ||
69 | /* time at last adjustment (secs): */ | |
70 | static long time_reftime; | |
71 | ||
72 | long time_adjust; | |
73 | ||
74 | static long ntp_tick_adj; | |
75 | ||
76 | /* | |
77 | * NTP methods: | |
78 | */ | |
4c7ee8de | 79 | |
9ce616aa IM |
80 | /* |
81 | * Update (tick_length, tick_length_base, tick_nsec), based | |
82 | * on (tick_usec, ntp_tick_adj, time_freq): | |
83 | */ | |
70bc42f9 AB |
84 | static void ntp_update_frequency(void) |
85 | { | |
9ce616aa IM |
86 | u64 prev_base; |
87 | u64 second_length; | |
88 | ||
89 | prev_base = tick_length_base; | |
90 | ||
91 | second_length = (u64)(tick_usec * NSEC_PER_USEC * USER_HZ) | |
92 | << NTP_SCALE_SHIFT; | |
93 | ||
94 | second_length += (s64)ntp_tick_adj << NTP_SCALE_SHIFT; | |
95 | second_length += time_freq; | |
70bc42f9 | 96 | |
9ce616aa | 97 | tick_length_base = second_length; |
70bc42f9 | 98 | |
9ce616aa IM |
99 | tick_nsec = div_u64(second_length, HZ) >> NTP_SCALE_SHIFT; |
100 | tick_length_base = div_u64(tick_length_base, NTP_INTERVAL_FREQ); | |
fdcedf7b | 101 | |
102 | /* | |
103 | * Don't wait for the next second_overflow, apply | |
104 | * the change to the tick length immediately | |
105 | */ | |
9ce616aa | 106 | tick_length += tick_length_base - prev_base; |
70bc42f9 AB |
107 | } |
108 | ||
ee9851b2 RZ |
109 | static void ntp_update_offset(long offset) |
110 | { | |
111 | long mtemp; | |
112 | s64 freq_adj; | |
113 | ||
114 | if (!(time_status & STA_PLL)) | |
115 | return; | |
116 | ||
eea83d89 | 117 | if (!(time_status & STA_NANO)) |
9f14f669 | 118 | offset *= NSEC_PER_USEC; |
ee9851b2 RZ |
119 | |
120 | /* | |
121 | * Scale the phase adjustment and | |
122 | * clamp to the operating range. | |
123 | */ | |
9f14f669 RZ |
124 | offset = min(offset, MAXPHASE); |
125 | offset = max(offset, -MAXPHASE); | |
ee9851b2 RZ |
126 | |
127 | /* | |
128 | * Select how the frequency is to be controlled | |
129 | * and in which mode (PLL or FLL). | |
130 | */ | |
131 | if (time_status & STA_FREQHOLD || time_reftime == 0) | |
132 | time_reftime = xtime.tv_sec; | |
133 | mtemp = xtime.tv_sec - time_reftime; | |
134 | time_reftime = xtime.tv_sec; | |
135 | ||
9f14f669 | 136 | freq_adj = (s64)offset * mtemp; |
7fc5c784 | 137 | freq_adj <<= NTP_SCALE_SHIFT - 2 * (SHIFT_PLL + 2 + time_constant); |
eea83d89 RZ |
138 | time_status &= ~STA_MODE; |
139 | if (mtemp >= MINSEC && (time_status & STA_FLL || mtemp > MAXSEC)) { | |
7fc5c784 | 140 | freq_adj += div_s64((s64)offset << (NTP_SCALE_SHIFT - SHIFT_FLL), |
074b3b87 | 141 | mtemp); |
eea83d89 RZ |
142 | time_status |= STA_MODE; |
143 | } | |
ee9851b2 | 144 | freq_adj += time_freq; |
074b3b87 RZ |
145 | freq_adj = min(freq_adj, MAXFREQ_SCALED); |
146 | time_freq = max(freq_adj, -MAXFREQ_SCALED); | |
9f14f669 | 147 | |
7fc5c784 | 148 | time_offset = div_s64((s64)offset << NTP_SCALE_SHIFT, NTP_INTERVAL_FREQ); |
ee9851b2 RZ |
149 | } |
150 | ||
b0ee7556 RZ |
151 | /** |
152 | * ntp_clear - Clears the NTP state variables | |
153 | * | |
154 | * Must be called while holding a write on the xtime_lock | |
155 | */ | |
156 | void ntp_clear(void) | |
157 | { | |
53bbfa9e IM |
158 | time_adjust = 0; /* stop active adjtime() */ |
159 | time_status |= STA_UNSYNC; | |
160 | time_maxerror = NTP_PHASE_LIMIT; | |
161 | time_esterror = NTP_PHASE_LIMIT; | |
b0ee7556 RZ |
162 | |
163 | ntp_update_frequency(); | |
164 | ||
53bbfa9e IM |
165 | tick_length = tick_length_base; |
166 | time_offset = 0; | |
b0ee7556 RZ |
167 | } |
168 | ||
4c7ee8de | 169 | /* |
7dffa3c6 RZ |
170 | * Leap second processing. If in leap-insert state at the end of the |
171 | * day, the system clock is set back one second; if in leap-delete | |
172 | * state, the system clock is set ahead one second. | |
4c7ee8de | 173 | */ |
7dffa3c6 | 174 | static enum hrtimer_restart ntp_leap_second(struct hrtimer *timer) |
4c7ee8de | 175 | { |
7dffa3c6 | 176 | enum hrtimer_restart res = HRTIMER_NORESTART; |
4c7ee8de | 177 | |
ca109491 | 178 | write_seqlock(&xtime_lock); |
4c7ee8de | 179 | |
4c7ee8de | 180 | switch (time_state) { |
181 | case TIME_OK: | |
4c7ee8de | 182 | break; |
183 | case TIME_INS: | |
7dffa3c6 RZ |
184 | xtime.tv_sec--; |
185 | wall_to_monotonic.tv_sec++; | |
186 | time_state = TIME_OOP; | |
53bbfa9e IM |
187 | printk(KERN_NOTICE |
188 | "Clock: inserting leap second 23:59:60 UTC\n"); | |
cc584b21 | 189 | hrtimer_add_expires_ns(&leap_timer, NSEC_PER_SEC); |
7dffa3c6 | 190 | res = HRTIMER_RESTART; |
4c7ee8de | 191 | break; |
192 | case TIME_DEL: | |
7dffa3c6 RZ |
193 | xtime.tv_sec++; |
194 | time_tai--; | |
195 | wall_to_monotonic.tv_sec--; | |
196 | time_state = TIME_WAIT; | |
53bbfa9e IM |
197 | printk(KERN_NOTICE |
198 | "Clock: deleting leap second 23:59:59 UTC\n"); | |
4c7ee8de | 199 | break; |
200 | case TIME_OOP: | |
153b5d05 | 201 | time_tai++; |
4c7ee8de | 202 | time_state = TIME_WAIT; |
7dffa3c6 | 203 | /* fall through */ |
4c7ee8de | 204 | case TIME_WAIT: |
205 | if (!(time_status & (STA_INS | STA_DEL))) | |
ee9851b2 | 206 | time_state = TIME_OK; |
7dffa3c6 RZ |
207 | break; |
208 | } | |
209 | update_vsyscall(&xtime, clock); | |
210 | ||
ca109491 | 211 | write_sequnlock(&xtime_lock); |
7dffa3c6 RZ |
212 | |
213 | return res; | |
214 | } | |
215 | ||
216 | /* | |
217 | * this routine handles the overflow of the microsecond field | |
218 | * | |
219 | * The tricky bits of code to handle the accurate clock support | |
220 | * were provided by Dave Mills (Mills@UDEL.EDU) of NTP fame. | |
221 | * They were originally developed for SUN and DEC kernels. | |
222 | * All the kudos should go to Dave for this stuff. | |
223 | */ | |
224 | void second_overflow(void) | |
225 | { | |
226 | s64 time_adj; | |
227 | ||
228 | /* Bump the maxerror field */ | |
229 | time_maxerror += MAXFREQ / NSEC_PER_USEC; | |
230 | if (time_maxerror > NTP_PHASE_LIMIT) { | |
231 | time_maxerror = NTP_PHASE_LIMIT; | |
232 | time_status |= STA_UNSYNC; | |
4c7ee8de | 233 | } |
234 | ||
235 | /* | |
f1992393 RZ |
236 | * Compute the phase adjustment for the next second. The offset is |
237 | * reduced by a fixed factor times the time constant. | |
4c7ee8de | 238 | */ |
53bbfa9e IM |
239 | tick_length = tick_length_base; |
240 | time_adj = shift_right(time_offset, SHIFT_PLL + time_constant); | |
241 | time_offset -= time_adj; | |
242 | tick_length += time_adj; | |
4c7ee8de | 243 | |
3c972c24 IM |
244 | if (!time_adjust) |
245 | return; | |
246 | ||
247 | if (time_adjust > MAX_TICKADJ) { | |
248 | time_adjust -= MAX_TICKADJ; | |
249 | tick_length += MAX_TICKADJ_SCALED; | |
250 | return; | |
4c7ee8de | 251 | } |
3c972c24 IM |
252 | |
253 | if (time_adjust < -MAX_TICKADJ) { | |
254 | time_adjust += MAX_TICKADJ; | |
255 | tick_length -= MAX_TICKADJ_SCALED; | |
256 | return; | |
257 | } | |
258 | ||
259 | tick_length += (s64)(time_adjust * NSEC_PER_USEC / NTP_INTERVAL_FREQ) | |
260 | << NTP_SCALE_SHIFT; | |
261 | time_adjust = 0; | |
4c7ee8de | 262 | } |
263 | ||
82644459 | 264 | #ifdef CONFIG_GENERIC_CMOS_UPDATE |
4c7ee8de | 265 | |
82644459 TG |
266 | /* Disable the cmos update - used by virtualization and embedded */ |
267 | int no_sync_cmos_clock __read_mostly; | |
268 | ||
eb3f938f | 269 | static void sync_cmos_clock(struct work_struct *work); |
82644459 | 270 | |
eb3f938f | 271 | static DECLARE_DELAYED_WORK(sync_cmos_work, sync_cmos_clock); |
82644459 | 272 | |
eb3f938f | 273 | static void sync_cmos_clock(struct work_struct *work) |
82644459 TG |
274 | { |
275 | struct timespec now, next; | |
276 | int fail = 1; | |
277 | ||
278 | /* | |
279 | * If we have an externally synchronized Linux clock, then update | |
280 | * CMOS clock accordingly every ~11 minutes. Set_rtc_mmss() has to be | |
281 | * called as close as possible to 500 ms before the new second starts. | |
282 | * This code is run on a timer. If the clock is set, that timer | |
283 | * may not expire at the correct time. Thus, we adjust... | |
284 | */ | |
53bbfa9e | 285 | if (!ntp_synced()) { |
82644459 TG |
286 | /* |
287 | * Not synced, exit, do not restart a timer (if one is | |
288 | * running, let it run out). | |
289 | */ | |
290 | return; | |
53bbfa9e | 291 | } |
82644459 TG |
292 | |
293 | getnstimeofday(&now); | |
fa6a1a55 | 294 | if (abs(now.tv_nsec - (NSEC_PER_SEC / 2)) <= tick_nsec / 2) |
82644459 TG |
295 | fail = update_persistent_clock(now); |
296 | ||
4ff4b9e1 | 297 | next.tv_nsec = (NSEC_PER_SEC / 2) - now.tv_nsec - (TICK_NSEC / 2); |
82644459 TG |
298 | if (next.tv_nsec <= 0) |
299 | next.tv_nsec += NSEC_PER_SEC; | |
300 | ||
301 | if (!fail) | |
302 | next.tv_sec = 659; | |
303 | else | |
304 | next.tv_sec = 0; | |
305 | ||
306 | if (next.tv_nsec >= NSEC_PER_SEC) { | |
307 | next.tv_sec++; | |
308 | next.tv_nsec -= NSEC_PER_SEC; | |
309 | } | |
eb3f938f | 310 | schedule_delayed_work(&sync_cmos_work, timespec_to_jiffies(&next)); |
82644459 TG |
311 | } |
312 | ||
313 | static void notify_cmos_timer(void) | |
4c7ee8de | 314 | { |
298a5df4 | 315 | if (!no_sync_cmos_clock) |
eb3f938f | 316 | schedule_delayed_work(&sync_cmos_work, 0); |
4c7ee8de | 317 | } |
318 | ||
82644459 TG |
319 | #else |
320 | static inline void notify_cmos_timer(void) { } | |
321 | #endif | |
322 | ||
53bbfa9e IM |
323 | /* |
324 | * adjtimex mainly allows reading (and writing, if superuser) of | |
4c7ee8de | 325 | * kernel time-keeping variables. used by xntpd. |
326 | */ | |
327 | int do_adjtimex(struct timex *txc) | |
328 | { | |
eea83d89 | 329 | struct timespec ts; |
4c7ee8de | 330 | int result; |
331 | ||
916c7a85 RZ |
332 | /* Validate the data before disabling interrupts */ |
333 | if (txc->modes & ADJ_ADJTIME) { | |
eea83d89 | 334 | /* singleshot must not be used with any other mode bits */ |
916c7a85 | 335 | if (!(txc->modes & ADJ_OFFSET_SINGLESHOT)) |
4c7ee8de | 336 | return -EINVAL; |
916c7a85 RZ |
337 | if (!(txc->modes & ADJ_OFFSET_READONLY) && |
338 | !capable(CAP_SYS_TIME)) | |
339 | return -EPERM; | |
340 | } else { | |
341 | /* In order to modify anything, you gotta be super-user! */ | |
342 | if (txc->modes && !capable(CAP_SYS_TIME)) | |
343 | return -EPERM; | |
344 | ||
53bbfa9e IM |
345 | /* |
346 | * if the quartz is off by more than 10% then | |
347 | * something is VERY wrong! | |
348 | */ | |
916c7a85 RZ |
349 | if (txc->modes & ADJ_TICK && |
350 | (txc->tick < 900000/USER_HZ || | |
351 | txc->tick > 1100000/USER_HZ)) | |
352 | return -EINVAL; | |
353 | ||
354 | if (txc->modes & ADJ_STATUS && time_state != TIME_OK) | |
355 | hrtimer_cancel(&leap_timer); | |
52bfb360 | 356 | } |
4c7ee8de | 357 | |
7dffa3c6 RZ |
358 | getnstimeofday(&ts); |
359 | ||
4c7ee8de | 360 | write_seqlock_irq(&xtime_lock); |
4c7ee8de | 361 | |
4c7ee8de | 362 | /* If there are input parameters, then process them */ |
916c7a85 RZ |
363 | if (txc->modes & ADJ_ADJTIME) { |
364 | long save_adjust = time_adjust; | |
365 | ||
366 | if (!(txc->modes & ADJ_OFFSET_READONLY)) { | |
367 | /* adjtime() is independent from ntp_adjtime() */ | |
368 | time_adjust = txc->offset; | |
369 | ntp_update_frequency(); | |
370 | } | |
371 | txc->offset = save_adjust; | |
372 | goto adj_done; | |
373 | } | |
ee9851b2 | 374 | if (txc->modes) { |
916c7a85 RZ |
375 | long sec; |
376 | ||
eea83d89 RZ |
377 | if (txc->modes & ADJ_STATUS) { |
378 | if ((time_status & STA_PLL) && | |
379 | !(txc->status & STA_PLL)) { | |
380 | time_state = TIME_OK; | |
381 | time_status = STA_UNSYNC; | |
382 | } | |
383 | /* only set allowed bits */ | |
384 | time_status &= STA_RONLY; | |
385 | time_status |= txc->status & ~STA_RONLY; | |
7dffa3c6 RZ |
386 | |
387 | switch (time_state) { | |
388 | case TIME_OK: | |
389 | start_timer: | |
390 | sec = ts.tv_sec; | |
391 | if (time_status & STA_INS) { | |
392 | time_state = TIME_INS; | |
393 | sec += 86400 - sec % 86400; | |
394 | hrtimer_start(&leap_timer, ktime_set(sec, 0), HRTIMER_MODE_ABS); | |
395 | } else if (time_status & STA_DEL) { | |
396 | time_state = TIME_DEL; | |
397 | sec += 86400 - (sec + 1) % 86400; | |
398 | hrtimer_start(&leap_timer, ktime_set(sec, 0), HRTIMER_MODE_ABS); | |
399 | } | |
400 | break; | |
401 | case TIME_INS: | |
402 | case TIME_DEL: | |
403 | time_state = TIME_OK; | |
404 | goto start_timer; | |
405 | break; | |
406 | case TIME_WAIT: | |
407 | if (!(time_status & (STA_INS | STA_DEL))) | |
408 | time_state = TIME_OK; | |
409 | break; | |
410 | case TIME_OOP: | |
411 | hrtimer_restart(&leap_timer); | |
412 | break; | |
413 | } | |
eea83d89 RZ |
414 | } |
415 | ||
416 | if (txc->modes & ADJ_NANO) | |
417 | time_status |= STA_NANO; | |
418 | if (txc->modes & ADJ_MICRO) | |
419 | time_status &= ~STA_NANO; | |
ee9851b2 RZ |
420 | |
421 | if (txc->modes & ADJ_FREQUENCY) { | |
074b3b87 RZ |
422 | time_freq = (s64)txc->freq * PPM_SCALE; |
423 | time_freq = min(time_freq, MAXFREQ_SCALED); | |
424 | time_freq = max(time_freq, -MAXFREQ_SCALED); | |
4c7ee8de | 425 | } |
ee9851b2 | 426 | |
eea83d89 | 427 | if (txc->modes & ADJ_MAXERROR) |
ee9851b2 | 428 | time_maxerror = txc->maxerror; |
eea83d89 | 429 | if (txc->modes & ADJ_ESTERROR) |
ee9851b2 | 430 | time_esterror = txc->esterror; |
4c7ee8de | 431 | |
ee9851b2 | 432 | if (txc->modes & ADJ_TIMECONST) { |
eea83d89 RZ |
433 | time_constant = txc->constant; |
434 | if (!(time_status & STA_NANO)) | |
435 | time_constant += 4; | |
436 | time_constant = min(time_constant, (long)MAXTC); | |
437 | time_constant = max(time_constant, 0l); | |
4c7ee8de | 438 | } |
4c7ee8de | 439 | |
153b5d05 RZ |
440 | if (txc->modes & ADJ_TAI && txc->constant > 0) |
441 | time_tai = txc->constant; | |
442 | ||
916c7a85 RZ |
443 | if (txc->modes & ADJ_OFFSET) |
444 | ntp_update_offset(txc->offset); | |
ee9851b2 RZ |
445 | if (txc->modes & ADJ_TICK) |
446 | tick_usec = txc->tick; | |
447 | ||
448 | if (txc->modes & (ADJ_TICK|ADJ_FREQUENCY|ADJ_OFFSET)) | |
449 | ntp_update_frequency(); | |
450 | } | |
eea83d89 | 451 | |
916c7a85 RZ |
452 | txc->offset = shift_right(time_offset * NTP_INTERVAL_FREQ, |
453 | NTP_SCALE_SHIFT); | |
454 | if (!(time_status & STA_NANO)) | |
455 | txc->offset /= NSEC_PER_USEC; | |
456 | ||
457 | adj_done: | |
eea83d89 | 458 | result = time_state; /* mostly `TIME_OK' */ |
ee9851b2 | 459 | if (time_status & (STA_UNSYNC|STA_CLOCKERR)) |
4c7ee8de | 460 | result = TIME_ERROR; |
461 | ||
d40e944c RZ |
462 | txc->freq = shift_right((time_freq >> PPM_SCALE_INV_SHIFT) * |
463 | (s64)PPM_SCALE_INV, NTP_SCALE_SHIFT); | |
4c7ee8de | 464 | txc->maxerror = time_maxerror; |
465 | txc->esterror = time_esterror; | |
466 | txc->status = time_status; | |
467 | txc->constant = time_constant; | |
70bc42f9 | 468 | txc->precision = 1; |
074b3b87 | 469 | txc->tolerance = MAXFREQ_SCALED / PPM_SCALE; |
4c7ee8de | 470 | txc->tick = tick_usec; |
153b5d05 | 471 | txc->tai = time_tai; |
4c7ee8de | 472 | |
473 | /* PPS is not implemented, so these are zero */ | |
474 | txc->ppsfreq = 0; | |
475 | txc->jitter = 0; | |
476 | txc->shift = 0; | |
477 | txc->stabil = 0; | |
478 | txc->jitcnt = 0; | |
479 | txc->calcnt = 0; | |
480 | txc->errcnt = 0; | |
481 | txc->stbcnt = 0; | |
482 | write_sequnlock_irq(&xtime_lock); | |
ee9851b2 | 483 | |
eea83d89 RZ |
484 | txc->time.tv_sec = ts.tv_sec; |
485 | txc->time.tv_usec = ts.tv_nsec; | |
486 | if (!(time_status & STA_NANO)) | |
487 | txc->time.tv_usec /= NSEC_PER_USEC; | |
ee9851b2 | 488 | |
82644459 | 489 | notify_cmos_timer(); |
ee9851b2 RZ |
490 | |
491 | return result; | |
4c7ee8de | 492 | } |
10a398d0 RZ |
493 | |
494 | static int __init ntp_tick_adj_setup(char *str) | |
495 | { | |
496 | ntp_tick_adj = simple_strtol(str, NULL, 0); | |
497 | return 1; | |
498 | } | |
499 | ||
500 | __setup("ntp_tick_adj=", ntp_tick_adj_setup); | |
7dffa3c6 RZ |
501 | |
502 | void __init ntp_init(void) | |
503 | { | |
504 | ntp_clear(); | |
505 | hrtimer_init(&leap_timer, CLOCK_REALTIME, HRTIMER_MODE_ABS); | |
506 | leap_timer.function = ntp_leap_second; | |
507 | } |