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Commit | Line | Data |
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4c7ee8de JS |
1 | /* |
2 | * linux/kernel/time/ntp.c | |
3 | * | |
4 | * NTP state machine interfaces and logic. | |
5 | * | |
6 | * This code was mainly moved from kernel/timer.c and kernel/time.c | |
7 | * Please see those files for relevant copyright info and historical | |
8 | * changelogs. | |
9 | */ | |
10 | ||
11 | #include <linux/mm.h> | |
12 | #include <linux/time.h> | |
82644459 | 13 | #include <linux/timer.h> |
4c7ee8de | 14 | #include <linux/timex.h> |
e8edc6e0 AD |
15 | #include <linux/jiffies.h> |
16 | #include <linux/hrtimer.h> | |
aa0ac365 | 17 | #include <linux/capability.h> |
4c7ee8de JS |
18 | #include <asm/div64.h> |
19 | #include <asm/timex.h> | |
20 | ||
b0ee7556 RZ |
21 | /* |
22 | * Timekeeping variables | |
23 | */ | |
24 | unsigned long tick_usec = TICK_USEC; /* USER_HZ period (usec) */ | |
25 | unsigned long tick_nsec; /* ACTHZ period (nsec) */ | |
26 | static u64 tick_length, tick_length_base; | |
27 | ||
8f807f8d RZ |
28 | #define MAX_TICKADJ 500 /* microsecs */ |
29 | #define MAX_TICKADJ_SCALED (((u64)(MAX_TICKADJ * NSEC_PER_USEC) << \ | |
f4304ab2 | 30 | TICK_LENGTH_SHIFT) / NTP_INTERVAL_FREQ) |
4c7ee8de JS |
31 | |
32 | /* | |
33 | * phase-lock loop variables | |
34 | */ | |
35 | /* TIME_ERROR prevents overwriting the CMOS clock */ | |
70bc42f9 | 36 | static int time_state = TIME_OK; /* clock synchronization status */ |
4c7ee8de | 37 | int time_status = STA_UNSYNC; /* clock status bits */ |
d62ac21a | 38 | static s64 time_offset; /* time adjustment (ns) */ |
70bc42f9 | 39 | static long time_constant = 2; /* pll time constant */ |
4c7ee8de JS |
40 | long time_maxerror = NTP_PHASE_LIMIT; /* maximum error (us) */ |
41 | long time_esterror = NTP_PHASE_LIMIT; /* estimated error (us) */ | |
dc6a43e4 | 42 | long time_freq; /* frequency offset (scaled ppm)*/ |
70bc42f9 | 43 | static long time_reftime; /* time at last adjustment (s) */ |
4c7ee8de | 44 | long time_adjust; |
4c7ee8de | 45 | |
70bc42f9 AB |
46 | #define CLOCK_TICK_OVERFLOW (LATCH * HZ - CLOCK_TICK_RATE) |
47 | #define CLOCK_TICK_ADJUST (((s64)CLOCK_TICK_OVERFLOW * NSEC_PER_SEC) / \ | |
48 | (s64)CLOCK_TICK_RATE) | |
49 | ||
50 | static void ntp_update_frequency(void) | |
51 | { | |
f4304ab2 JS |
52 | u64 second_length = (u64)(tick_usec * NSEC_PER_USEC * USER_HZ) |
53 | << TICK_LENGTH_SHIFT; | |
54 | second_length += (s64)CLOCK_TICK_ADJUST << TICK_LENGTH_SHIFT; | |
55 | second_length += (s64)time_freq << (TICK_LENGTH_SHIFT - SHIFT_NSEC); | |
70bc42f9 | 56 | |
f4304ab2 | 57 | tick_length_base = second_length; |
70bc42f9 | 58 | |
f4304ab2 JS |
59 | do_div(second_length, HZ); |
60 | tick_nsec = second_length >> TICK_LENGTH_SHIFT; | |
61 | ||
62 | do_div(tick_length_base, NTP_INTERVAL_FREQ); | |
70bc42f9 AB |
63 | } |
64 | ||
b0ee7556 RZ |
65 | /** |
66 | * ntp_clear - Clears the NTP state variables | |
67 | * | |
68 | * Must be called while holding a write on the xtime_lock | |
69 | */ | |
70 | void ntp_clear(void) | |
71 | { | |
72 | time_adjust = 0; /* stop active adjtime() */ | |
73 | time_status |= STA_UNSYNC; | |
74 | time_maxerror = NTP_PHASE_LIMIT; | |
75 | time_esterror = NTP_PHASE_LIMIT; | |
76 | ||
77 | ntp_update_frequency(); | |
78 | ||
79 | tick_length = tick_length_base; | |
3d3675cc | 80 | time_offset = 0; |
b0ee7556 RZ |
81 | } |
82 | ||
4c7ee8de JS |
83 | /* |
84 | * this routine handles the overflow of the microsecond field | |
85 | * | |
86 | * The tricky bits of code to handle the accurate clock support | |
87 | * were provided by Dave Mills (Mills@UDEL.EDU) of NTP fame. | |
88 | * They were originally developed for SUN and DEC kernels. | |
89 | * All the kudos should go to Dave for this stuff. | |
90 | */ | |
91 | void second_overflow(void) | |
92 | { | |
3d3675cc | 93 | long time_adj; |
4c7ee8de JS |
94 | |
95 | /* Bump the maxerror field */ | |
97eebe13 | 96 | time_maxerror += MAXFREQ >> SHIFT_USEC; |
4c7ee8de JS |
97 | if (time_maxerror > NTP_PHASE_LIMIT) { |
98 | time_maxerror = NTP_PHASE_LIMIT; | |
99 | time_status |= STA_UNSYNC; | |
100 | } | |
101 | ||
102 | /* | |
103 | * Leap second processing. If in leap-insert state at the end of the | |
104 | * day, the system clock is set back one second; if in leap-delete | |
105 | * state, the system clock is set ahead one second. The microtime() | |
106 | * routine or external clock driver will insure that reported time is | |
107 | * always monotonic. The ugly divides should be replaced. | |
108 | */ | |
109 | switch (time_state) { | |
110 | case TIME_OK: | |
111 | if (time_status & STA_INS) | |
112 | time_state = TIME_INS; | |
113 | else if (time_status & STA_DEL) | |
114 | time_state = TIME_DEL; | |
115 | break; | |
116 | case TIME_INS: | |
117 | if (xtime.tv_sec % 86400 == 0) { | |
118 | xtime.tv_sec--; | |
119 | wall_to_monotonic.tv_sec++; | |
4c7ee8de | 120 | time_state = TIME_OOP; |
4c7ee8de JS |
121 | printk(KERN_NOTICE "Clock: inserting leap second " |
122 | "23:59:60 UTC\n"); | |
123 | } | |
124 | break; | |
125 | case TIME_DEL: | |
126 | if ((xtime.tv_sec + 1) % 86400 == 0) { | |
127 | xtime.tv_sec++; | |
128 | wall_to_monotonic.tv_sec--; | |
4c7ee8de | 129 | time_state = TIME_WAIT; |
4c7ee8de JS |
130 | printk(KERN_NOTICE "Clock: deleting leap second " |
131 | "23:59:59 UTC\n"); | |
132 | } | |
133 | break; | |
134 | case TIME_OOP: | |
135 | time_state = TIME_WAIT; | |
136 | break; | |
137 | case TIME_WAIT: | |
138 | if (!(time_status & (STA_INS | STA_DEL))) | |
139 | time_state = TIME_OK; | |
140 | } | |
141 | ||
142 | /* | |
f1992393 RZ |
143 | * Compute the phase adjustment for the next second. The offset is |
144 | * reduced by a fixed factor times the time constant. | |
4c7ee8de | 145 | */ |
b0ee7556 | 146 | tick_length = tick_length_base; |
f1992393 | 147 | time_adj = shift_right(time_offset, SHIFT_PLL + time_constant); |
3d3675cc RZ |
148 | time_offset -= time_adj; |
149 | tick_length += (s64)time_adj << (TICK_LENGTH_SHIFT - SHIFT_UPDATE); | |
4c7ee8de | 150 | |
8f807f8d RZ |
151 | if (unlikely(time_adjust)) { |
152 | if (time_adjust > MAX_TICKADJ) { | |
153 | time_adjust -= MAX_TICKADJ; | |
154 | tick_length += MAX_TICKADJ_SCALED; | |
155 | } else if (time_adjust < -MAX_TICKADJ) { | |
156 | time_adjust += MAX_TICKADJ; | |
157 | tick_length -= MAX_TICKADJ_SCALED; | |
158 | } else { | |
8f807f8d | 159 | tick_length += (s64)(time_adjust * NSEC_PER_USEC / |
f4304ab2 | 160 | NTP_INTERVAL_FREQ) << TICK_LENGTH_SHIFT; |
bb1d8605 | 161 | time_adjust = 0; |
8f807f8d | 162 | } |
4c7ee8de JS |
163 | } |
164 | } | |
165 | ||
166 | /* | |
167 | * Return how long ticks are at the moment, that is, how much time | |
168 | * update_wall_time_one_tick will add to xtime next time we call it | |
169 | * (assuming no calls to do_adjtimex in the meantime). | |
170 | * The return value is in fixed-point nanoseconds shifted by the | |
171 | * specified number of bits to the right of the binary point. | |
172 | * This function has no side-effects. | |
173 | */ | |
174 | u64 current_tick_length(void) | |
175 | { | |
8f807f8d | 176 | return tick_length; |
4c7ee8de JS |
177 | } |
178 | ||
82644459 | 179 | #ifdef CONFIG_GENERIC_CMOS_UPDATE |
4c7ee8de | 180 | |
82644459 TG |
181 | /* Disable the cmos update - used by virtualization and embedded */ |
182 | int no_sync_cmos_clock __read_mostly; | |
183 | ||
184 | static void sync_cmos_clock(unsigned long dummy); | |
185 | ||
186 | static DEFINE_TIMER(sync_cmos_timer, sync_cmos_clock, 0, 0); | |
187 | ||
188 | static void sync_cmos_clock(unsigned long dummy) | |
189 | { | |
190 | struct timespec now, next; | |
191 | int fail = 1; | |
192 | ||
193 | /* | |
194 | * If we have an externally synchronized Linux clock, then update | |
195 | * CMOS clock accordingly every ~11 minutes. Set_rtc_mmss() has to be | |
196 | * called as close as possible to 500 ms before the new second starts. | |
197 | * This code is run on a timer. If the clock is set, that timer | |
198 | * may not expire at the correct time. Thus, we adjust... | |
199 | */ | |
200 | if (!ntp_synced()) | |
201 | /* | |
202 | * Not synced, exit, do not restart a timer (if one is | |
203 | * running, let it run out). | |
204 | */ | |
205 | return; | |
206 | ||
207 | getnstimeofday(&now); | |
208 | if (abs(xtime.tv_nsec - (NSEC_PER_SEC / 2)) <= tick_nsec / 2) | |
209 | fail = update_persistent_clock(now); | |
210 | ||
211 | next.tv_nsec = (NSEC_PER_SEC / 2) - now.tv_nsec; | |
212 | if (next.tv_nsec <= 0) | |
213 | next.tv_nsec += NSEC_PER_SEC; | |
214 | ||
215 | if (!fail) | |
216 | next.tv_sec = 659; | |
217 | else | |
218 | next.tv_sec = 0; | |
219 | ||
220 | if (next.tv_nsec >= NSEC_PER_SEC) { | |
221 | next.tv_sec++; | |
222 | next.tv_nsec -= NSEC_PER_SEC; | |
223 | } | |
224 | mod_timer(&sync_cmos_timer, jiffies + timespec_to_jiffies(&next)); | |
225 | } | |
226 | ||
227 | static void notify_cmos_timer(void) | |
4c7ee8de | 228 | { |
298a5df4 | 229 | if (!no_sync_cmos_clock) |
82644459 | 230 | mod_timer(&sync_cmos_timer, jiffies + 1); |
4c7ee8de JS |
231 | } |
232 | ||
82644459 TG |
233 | #else |
234 | static inline void notify_cmos_timer(void) { } | |
235 | #endif | |
236 | ||
4c7ee8de JS |
237 | /* adjtimex mainly allows reading (and writing, if superuser) of |
238 | * kernel time-keeping variables. used by xntpd. | |
239 | */ | |
240 | int do_adjtimex(struct timex *txc) | |
241 | { | |
d62ac21a | 242 | long mtemp, save_adjust, rem; |
f1992393 | 243 | s64 freq_adj, temp64; |
4c7ee8de JS |
244 | int result; |
245 | ||
246 | /* In order to modify anything, you gotta be super-user! */ | |
247 | if (txc->modes && !capable(CAP_SYS_TIME)) | |
248 | return -EPERM; | |
249 | ||
250 | /* Now we validate the data before disabling interrupts */ | |
251 | ||
252 | if ((txc->modes & ADJ_OFFSET_SINGLESHOT) == ADJ_OFFSET_SINGLESHOT) | |
253 | /* singleshot must not be used with any other mode bits */ | |
254 | if (txc->modes != ADJ_OFFSET_SINGLESHOT) | |
255 | return -EINVAL; | |
256 | ||
257 | if (txc->modes != ADJ_OFFSET_SINGLESHOT && (txc->modes & ADJ_OFFSET)) | |
258 | /* adjustment Offset limited to +- .512 seconds */ | |
259 | if (txc->offset <= - MAXPHASE || txc->offset >= MAXPHASE ) | |
260 | return -EINVAL; | |
261 | ||
262 | /* if the quartz is off by more than 10% something is VERY wrong ! */ | |
263 | if (txc->modes & ADJ_TICK) | |
264 | if (txc->tick < 900000/USER_HZ || | |
265 | txc->tick > 1100000/USER_HZ) | |
266 | return -EINVAL; | |
267 | ||
268 | write_seqlock_irq(&xtime_lock); | |
269 | result = time_state; /* mostly `TIME_OK' */ | |
270 | ||
271 | /* Save for later - semantics of adjtime is to return old value */ | |
8f807f8d | 272 | save_adjust = time_adjust; |
4c7ee8de JS |
273 | |
274 | #if 0 /* STA_CLOCKERR is never set yet */ | |
275 | time_status &= ~STA_CLOCKERR; /* reset STA_CLOCKERR */ | |
276 | #endif | |
277 | /* If there are input parameters, then process them */ | |
278 | if (txc->modes) | |
279 | { | |
280 | if (txc->modes & ADJ_STATUS) /* only set allowed bits */ | |
281 | time_status = (txc->status & ~STA_RONLY) | | |
282 | (time_status & STA_RONLY); | |
283 | ||
284 | if (txc->modes & ADJ_FREQUENCY) { /* p. 22 */ | |
285 | if (txc->freq > MAXFREQ || txc->freq < -MAXFREQ) { | |
286 | result = -EINVAL; | |
287 | goto leave; | |
288 | } | |
f4304ab2 JS |
289 | time_freq = ((s64)txc->freq * NSEC_PER_USEC) |
290 | >> (SHIFT_USEC - SHIFT_NSEC); | |
4c7ee8de JS |
291 | } |
292 | ||
293 | if (txc->modes & ADJ_MAXERROR) { | |
294 | if (txc->maxerror < 0 || txc->maxerror >= NTP_PHASE_LIMIT) { | |
295 | result = -EINVAL; | |
296 | goto leave; | |
297 | } | |
298 | time_maxerror = txc->maxerror; | |
299 | } | |
300 | ||
301 | if (txc->modes & ADJ_ESTERROR) { | |
302 | if (txc->esterror < 0 || txc->esterror >= NTP_PHASE_LIMIT) { | |
303 | result = -EINVAL; | |
304 | goto leave; | |
305 | } | |
306 | time_esterror = txc->esterror; | |
307 | } | |
308 | ||
309 | if (txc->modes & ADJ_TIMECONST) { /* p. 24 */ | |
310 | if (txc->constant < 0) { /* NTP v4 uses values > 6 */ | |
311 | result = -EINVAL; | |
312 | goto leave; | |
313 | } | |
f1992393 | 314 | time_constant = min(txc->constant + 4, (long)MAXTC); |
4c7ee8de JS |
315 | } |
316 | ||
317 | if (txc->modes & ADJ_OFFSET) { /* values checked earlier */ | |
318 | if (txc->modes == ADJ_OFFSET_SINGLESHOT) { | |
319 | /* adjtime() is independent from ntp_adjtime() */ | |
8f807f8d | 320 | time_adjust = txc->offset; |
4c7ee8de JS |
321 | } |
322 | else if (time_status & STA_PLL) { | |
d62ac21a | 323 | time_offset = txc->offset * NSEC_PER_USEC; |
4c7ee8de JS |
324 | |
325 | /* | |
326 | * Scale the phase adjustment and | |
327 | * clamp to the operating range. | |
328 | */ | |
d62ac21a JS |
329 | time_offset = min(time_offset, (s64)MAXPHASE * NSEC_PER_USEC); |
330 | time_offset = max(time_offset, (s64)-MAXPHASE * NSEC_PER_USEC); | |
4c7ee8de JS |
331 | |
332 | /* | |
333 | * Select whether the frequency is to be controlled | |
334 | * and in which mode (PLL or FLL). Clamp to the operating | |
335 | * range. Ugly multiply/divide should be replaced someday. | |
336 | */ | |
337 | ||
338 | if (time_status & STA_FREQHOLD || time_reftime == 0) | |
339 | time_reftime = xtime.tv_sec; | |
340 | mtemp = xtime.tv_sec - time_reftime; | |
341 | time_reftime = xtime.tv_sec; | |
f1992393 | 342 | |
d62ac21a | 343 | freq_adj = time_offset * mtemp; |
f1992393 RZ |
344 | freq_adj = shift_right(freq_adj, time_constant * 2 + |
345 | (SHIFT_PLL + 2) * 2 - SHIFT_NSEC); | |
346 | if (mtemp >= MINSEC && (time_status & STA_FLL || mtemp > MAXSEC)) { | |
d62ac21a | 347 | temp64 = time_offset << (SHIFT_NSEC - SHIFT_FLL); |
f1992393 RZ |
348 | if (time_offset < 0) { |
349 | temp64 = -temp64; | |
350 | do_div(temp64, mtemp); | |
351 | freq_adj -= temp64; | |
352 | } else { | |
353 | do_div(temp64, mtemp); | |
354 | freq_adj += temp64; | |
355 | } | |
4c7ee8de | 356 | } |
04b617e7 RZ |
357 | freq_adj += time_freq; |
358 | freq_adj = min(freq_adj, (s64)MAXFREQ_NSEC); | |
359 | time_freq = max(freq_adj, (s64)-MAXFREQ_NSEC); | |
d62ac21a JS |
360 | time_offset = div_long_long_rem_signed(time_offset, |
361 | NTP_INTERVAL_FREQ, | |
362 | &rem); | |
363 | time_offset <<= SHIFT_UPDATE; | |
4c7ee8de JS |
364 | } /* STA_PLL */ |
365 | } /* txc->modes & ADJ_OFFSET */ | |
b0ee7556 | 366 | if (txc->modes & ADJ_TICK) |
4c7ee8de | 367 | tick_usec = txc->tick; |
b0ee7556 | 368 | |
dc6a43e4 | 369 | if (txc->modes & (ADJ_TICK|ADJ_FREQUENCY|ADJ_OFFSET)) |
b0ee7556 | 370 | ntp_update_frequency(); |
4c7ee8de JS |
371 | } /* txc->modes */ |
372 | leave: if ((time_status & (STA_UNSYNC|STA_CLOCKERR)) != 0) | |
373 | result = TIME_ERROR; | |
374 | ||
375 | if ((txc->modes & ADJ_OFFSET_SINGLESHOT) == ADJ_OFFSET_SINGLESHOT) | |
d62ac21a | 376 | txc->offset = save_adjust; |
3d3675cc | 377 | else |
d62ac21a JS |
378 | txc->offset = ((long)shift_right(time_offset, SHIFT_UPDATE)) * |
379 | NTP_INTERVAL_FREQ / 1000; | |
380 | txc->freq = (time_freq / NSEC_PER_USEC) << | |
381 | (SHIFT_USEC - SHIFT_NSEC); | |
4c7ee8de JS |
382 | txc->maxerror = time_maxerror; |
383 | txc->esterror = time_esterror; | |
384 | txc->status = time_status; | |
385 | txc->constant = time_constant; | |
70bc42f9 | 386 | txc->precision = 1; |
97eebe13 | 387 | txc->tolerance = MAXFREQ; |
4c7ee8de JS |
388 | txc->tick = tick_usec; |
389 | ||
390 | /* PPS is not implemented, so these are zero */ | |
391 | txc->ppsfreq = 0; | |
392 | txc->jitter = 0; | |
393 | txc->shift = 0; | |
394 | txc->stabil = 0; | |
395 | txc->jitcnt = 0; | |
396 | txc->calcnt = 0; | |
397 | txc->errcnt = 0; | |
398 | txc->stbcnt = 0; | |
399 | write_sequnlock_irq(&xtime_lock); | |
400 | do_gettimeofday(&txc->time); | |
82644459 | 401 | notify_cmos_timer(); |
4c7ee8de JS |
402 | return(result); |
403 | } |