Commit | Line | Data |
---|---|---|
4c7ee8de | 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 | 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 | 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 | 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; |
10a398d0 | 45 | static long ntp_tick_adj; |
4c7ee8de | 46 | |
70bc42f9 AB |
47 | static void ntp_update_frequency(void) |
48 | { | |
f4304ab2 | 49 | u64 second_length = (u64)(tick_usec * NSEC_PER_USEC * USER_HZ) |
50 | << TICK_LENGTH_SHIFT; | |
10a398d0 | 51 | second_length += (s64)ntp_tick_adj << TICK_LENGTH_SHIFT; |
f4304ab2 | 52 | second_length += (s64)time_freq << (TICK_LENGTH_SHIFT - SHIFT_NSEC); |
70bc42f9 | 53 | |
f4304ab2 | 54 | tick_length_base = second_length; |
70bc42f9 | 55 | |
f4304ab2 | 56 | do_div(second_length, HZ); |
57 | tick_nsec = second_length >> TICK_LENGTH_SHIFT; | |
58 | ||
59 | do_div(tick_length_base, NTP_INTERVAL_FREQ); | |
70bc42f9 AB |
60 | } |
61 | ||
b0ee7556 RZ |
62 | /** |
63 | * ntp_clear - Clears the NTP state variables | |
64 | * | |
65 | * Must be called while holding a write on the xtime_lock | |
66 | */ | |
67 | void ntp_clear(void) | |
68 | { | |
69 | time_adjust = 0; /* stop active adjtime() */ | |
70 | time_status |= STA_UNSYNC; | |
71 | time_maxerror = NTP_PHASE_LIMIT; | |
72 | time_esterror = NTP_PHASE_LIMIT; | |
73 | ||
74 | ntp_update_frequency(); | |
75 | ||
76 | tick_length = tick_length_base; | |
3d3675cc | 77 | time_offset = 0; |
b0ee7556 RZ |
78 | } |
79 | ||
4c7ee8de | 80 | /* |
81 | * this routine handles the overflow of the microsecond field | |
82 | * | |
83 | * The tricky bits of code to handle the accurate clock support | |
84 | * were provided by Dave Mills (Mills@UDEL.EDU) of NTP fame. | |
85 | * They were originally developed for SUN and DEC kernels. | |
86 | * All the kudos should go to Dave for this stuff. | |
87 | */ | |
88 | void second_overflow(void) | |
89 | { | |
3d3675cc | 90 | long time_adj; |
4c7ee8de | 91 | |
92 | /* Bump the maxerror field */ | |
97eebe13 | 93 | time_maxerror += MAXFREQ >> SHIFT_USEC; |
4c7ee8de | 94 | if (time_maxerror > NTP_PHASE_LIMIT) { |
95 | time_maxerror = NTP_PHASE_LIMIT; | |
96 | time_status |= STA_UNSYNC; | |
97 | } | |
98 | ||
99 | /* | |
100 | * Leap second processing. If in leap-insert state at the end of the | |
101 | * day, the system clock is set back one second; if in leap-delete | |
102 | * state, the system clock is set ahead one second. The microtime() | |
103 | * routine or external clock driver will insure that reported time is | |
104 | * always monotonic. The ugly divides should be replaced. | |
105 | */ | |
106 | switch (time_state) { | |
107 | case TIME_OK: | |
108 | if (time_status & STA_INS) | |
109 | time_state = TIME_INS; | |
110 | else if (time_status & STA_DEL) | |
111 | time_state = TIME_DEL; | |
112 | break; | |
113 | case TIME_INS: | |
114 | if (xtime.tv_sec % 86400 == 0) { | |
115 | xtime.tv_sec--; | |
116 | wall_to_monotonic.tv_sec++; | |
4c7ee8de | 117 | time_state = TIME_OOP; |
4c7ee8de | 118 | printk(KERN_NOTICE "Clock: inserting leap second " |
119 | "23:59:60 UTC\n"); | |
120 | } | |
121 | break; | |
122 | case TIME_DEL: | |
123 | if ((xtime.tv_sec + 1) % 86400 == 0) { | |
124 | xtime.tv_sec++; | |
125 | wall_to_monotonic.tv_sec--; | |
4c7ee8de | 126 | time_state = TIME_WAIT; |
4c7ee8de | 127 | printk(KERN_NOTICE "Clock: deleting leap second " |
128 | "23:59:59 UTC\n"); | |
129 | } | |
130 | break; | |
131 | case TIME_OOP: | |
132 | time_state = TIME_WAIT; | |
133 | break; | |
134 | case TIME_WAIT: | |
135 | if (!(time_status & (STA_INS | STA_DEL))) | |
136 | time_state = TIME_OK; | |
137 | } | |
138 | ||
139 | /* | |
f1992393 RZ |
140 | * Compute the phase adjustment for the next second. The offset is |
141 | * reduced by a fixed factor times the time constant. | |
4c7ee8de | 142 | */ |
b0ee7556 | 143 | tick_length = tick_length_base; |
f1992393 | 144 | time_adj = shift_right(time_offset, SHIFT_PLL + time_constant); |
3d3675cc RZ |
145 | time_offset -= time_adj; |
146 | tick_length += (s64)time_adj << (TICK_LENGTH_SHIFT - SHIFT_UPDATE); | |
4c7ee8de | 147 | |
8f807f8d RZ |
148 | if (unlikely(time_adjust)) { |
149 | if (time_adjust > MAX_TICKADJ) { | |
150 | time_adjust -= MAX_TICKADJ; | |
151 | tick_length += MAX_TICKADJ_SCALED; | |
152 | } else if (time_adjust < -MAX_TICKADJ) { | |
153 | time_adjust += MAX_TICKADJ; | |
154 | tick_length -= MAX_TICKADJ_SCALED; | |
155 | } else { | |
8f807f8d | 156 | tick_length += (s64)(time_adjust * NSEC_PER_USEC / |
f4304ab2 | 157 | NTP_INTERVAL_FREQ) << TICK_LENGTH_SHIFT; |
bb1d8605 | 158 | time_adjust = 0; |
8f807f8d | 159 | } |
4c7ee8de | 160 | } |
161 | } | |
162 | ||
163 | /* | |
164 | * Return how long ticks are at the moment, that is, how much time | |
165 | * update_wall_time_one_tick will add to xtime next time we call it | |
166 | * (assuming no calls to do_adjtimex in the meantime). | |
167 | * The return value is in fixed-point nanoseconds shifted by the | |
168 | * specified number of bits to the right of the binary point. | |
169 | * This function has no side-effects. | |
170 | */ | |
171 | u64 current_tick_length(void) | |
172 | { | |
8f807f8d | 173 | return tick_length; |
4c7ee8de | 174 | } |
175 | ||
82644459 | 176 | #ifdef CONFIG_GENERIC_CMOS_UPDATE |
4c7ee8de | 177 | |
82644459 TG |
178 | /* Disable the cmos update - used by virtualization and embedded */ |
179 | int no_sync_cmos_clock __read_mostly; | |
180 | ||
181 | static void sync_cmos_clock(unsigned long dummy); | |
182 | ||
183 | static DEFINE_TIMER(sync_cmos_timer, sync_cmos_clock, 0, 0); | |
184 | ||
185 | static void sync_cmos_clock(unsigned long dummy) | |
186 | { | |
187 | struct timespec now, next; | |
188 | int fail = 1; | |
189 | ||
190 | /* | |
191 | * If we have an externally synchronized Linux clock, then update | |
192 | * CMOS clock accordingly every ~11 minutes. Set_rtc_mmss() has to be | |
193 | * called as close as possible to 500 ms before the new second starts. | |
194 | * This code is run on a timer. If the clock is set, that timer | |
195 | * may not expire at the correct time. Thus, we adjust... | |
196 | */ | |
197 | if (!ntp_synced()) | |
198 | /* | |
199 | * Not synced, exit, do not restart a timer (if one is | |
200 | * running, let it run out). | |
201 | */ | |
202 | return; | |
203 | ||
204 | getnstimeofday(&now); | |
fa6a1a55 | 205 | if (abs(now.tv_nsec - (NSEC_PER_SEC / 2)) <= tick_nsec / 2) |
82644459 TG |
206 | fail = update_persistent_clock(now); |
207 | ||
208 | next.tv_nsec = (NSEC_PER_SEC / 2) - now.tv_nsec; | |
209 | if (next.tv_nsec <= 0) | |
210 | next.tv_nsec += NSEC_PER_SEC; | |
211 | ||
212 | if (!fail) | |
213 | next.tv_sec = 659; | |
214 | else | |
215 | next.tv_sec = 0; | |
216 | ||
217 | if (next.tv_nsec >= NSEC_PER_SEC) { | |
218 | next.tv_sec++; | |
219 | next.tv_nsec -= NSEC_PER_SEC; | |
220 | } | |
221 | mod_timer(&sync_cmos_timer, jiffies + timespec_to_jiffies(&next)); | |
222 | } | |
223 | ||
224 | static void notify_cmos_timer(void) | |
4c7ee8de | 225 | { |
298a5df4 | 226 | if (!no_sync_cmos_clock) |
82644459 | 227 | mod_timer(&sync_cmos_timer, jiffies + 1); |
4c7ee8de | 228 | } |
229 | ||
82644459 TG |
230 | #else |
231 | static inline void notify_cmos_timer(void) { } | |
232 | #endif | |
233 | ||
4c7ee8de | 234 | /* adjtimex mainly allows reading (and writing, if superuser) of |
235 | * kernel time-keeping variables. used by xntpd. | |
236 | */ | |
237 | int do_adjtimex(struct timex *txc) | |
238 | { | |
d62ac21a | 239 | long mtemp, save_adjust, rem; |
f1992393 | 240 | s64 freq_adj, temp64; |
4c7ee8de | 241 | int result; |
242 | ||
243 | /* In order to modify anything, you gotta be super-user! */ | |
244 | if (txc->modes && !capable(CAP_SYS_TIME)) | |
245 | return -EPERM; | |
246 | ||
247 | /* Now we validate the data before disabling interrupts */ | |
248 | ||
52bfb360 | 249 | if ((txc->modes & ADJ_OFFSET_SINGLESHOT) == ADJ_OFFSET_SINGLESHOT) { |
4c7ee8de | 250 | /* singleshot must not be used with any other mode bits */ |
52bfb360 JS |
251 | if (txc->modes != ADJ_OFFSET_SINGLESHOT && |
252 | txc->modes != ADJ_OFFSET_SS_READ) | |
4c7ee8de | 253 | return -EINVAL; |
52bfb360 | 254 | } |
4c7ee8de | 255 | |
256 | if (txc->modes != ADJ_OFFSET_SINGLESHOT && (txc->modes & ADJ_OFFSET)) | |
257 | /* adjustment Offset limited to +- .512 seconds */ | |
258 | if (txc->offset <= - MAXPHASE || txc->offset >= MAXPHASE ) | |
259 | return -EINVAL; | |
260 | ||
261 | /* if the quartz is off by more than 10% something is VERY wrong ! */ | |
262 | if (txc->modes & ADJ_TICK) | |
263 | if (txc->tick < 900000/USER_HZ || | |
264 | txc->tick > 1100000/USER_HZ) | |
265 | return -EINVAL; | |
266 | ||
267 | write_seqlock_irq(&xtime_lock); | |
268 | result = time_state; /* mostly `TIME_OK' */ | |
269 | ||
270 | /* Save for later - semantics of adjtime is to return old value */ | |
8f807f8d | 271 | save_adjust = time_adjust; |
4c7ee8de | 272 | |
273 | #if 0 /* STA_CLOCKERR is never set yet */ | |
274 | time_status &= ~STA_CLOCKERR; /* reset STA_CLOCKERR */ | |
275 | #endif | |
276 | /* If there are input parameters, then process them */ | |
277 | if (txc->modes) | |
278 | { | |
279 | if (txc->modes & ADJ_STATUS) /* only set allowed bits */ | |
280 | time_status = (txc->status & ~STA_RONLY) | | |
281 | (time_status & STA_RONLY); | |
282 | ||
283 | if (txc->modes & ADJ_FREQUENCY) { /* p. 22 */ | |
284 | if (txc->freq > MAXFREQ || txc->freq < -MAXFREQ) { | |
285 | result = -EINVAL; | |
286 | goto leave; | |
287 | } | |
f4304ab2 | 288 | time_freq = ((s64)txc->freq * NSEC_PER_USEC) |
289 | >> (SHIFT_USEC - SHIFT_NSEC); | |
4c7ee8de | 290 | } |
291 | ||
292 | if (txc->modes & ADJ_MAXERROR) { | |
293 | if (txc->maxerror < 0 || txc->maxerror >= NTP_PHASE_LIMIT) { | |
294 | result = -EINVAL; | |
295 | goto leave; | |
296 | } | |
297 | time_maxerror = txc->maxerror; | |
298 | } | |
299 | ||
300 | if (txc->modes & ADJ_ESTERROR) { | |
301 | if (txc->esterror < 0 || txc->esterror >= NTP_PHASE_LIMIT) { | |
302 | result = -EINVAL; | |
303 | goto leave; | |
304 | } | |
305 | time_esterror = txc->esterror; | |
306 | } | |
307 | ||
308 | if (txc->modes & ADJ_TIMECONST) { /* p. 24 */ | |
309 | if (txc->constant < 0) { /* NTP v4 uses values > 6 */ | |
310 | result = -EINVAL; | |
311 | goto leave; | |
312 | } | |
f1992393 | 313 | time_constant = min(txc->constant + 4, (long)MAXTC); |
4c7ee8de | 314 | } |
315 | ||
316 | if (txc->modes & ADJ_OFFSET) { /* values checked earlier */ | |
317 | if (txc->modes == ADJ_OFFSET_SINGLESHOT) { | |
318 | /* adjtime() is independent from ntp_adjtime() */ | |
8f807f8d | 319 | time_adjust = txc->offset; |
4c7ee8de | 320 | } |
321 | else if (time_status & STA_PLL) { | |
d62ac21a | 322 | time_offset = txc->offset * NSEC_PER_USEC; |
4c7ee8de | 323 | |
324 | /* | |
325 | * Scale the phase adjustment and | |
326 | * clamp to the operating range. | |
327 | */ | |
d62ac21a | 328 | time_offset = min(time_offset, (s64)MAXPHASE * NSEC_PER_USEC); |
329 | time_offset = max(time_offset, (s64)-MAXPHASE * NSEC_PER_USEC); | |
4c7ee8de | 330 | |
331 | /* | |
332 | * Select whether the frequency is to be controlled | |
333 | * and in which mode (PLL or FLL). Clamp to the operating | |
334 | * range. Ugly multiply/divide should be replaced someday. | |
335 | */ | |
336 | ||
337 | if (time_status & STA_FREQHOLD || time_reftime == 0) | |
338 | time_reftime = xtime.tv_sec; | |
339 | mtemp = xtime.tv_sec - time_reftime; | |
340 | time_reftime = xtime.tv_sec; | |
f1992393 | 341 | |
d62ac21a | 342 | freq_adj = time_offset * mtemp; |
f1992393 RZ |
343 | freq_adj = shift_right(freq_adj, time_constant * 2 + |
344 | (SHIFT_PLL + 2) * 2 - SHIFT_NSEC); | |
345 | if (mtemp >= MINSEC && (time_status & STA_FLL || mtemp > MAXSEC)) { | |
e48af19f | 346 | u64 utemp64; |
d62ac21a | 347 | temp64 = time_offset << (SHIFT_NSEC - SHIFT_FLL); |
f1992393 | 348 | if (time_offset < 0) { |
e48af19f DH |
349 | utemp64 = -temp64; |
350 | do_div(utemp64, mtemp); | |
351 | freq_adj -= utemp64; | |
f1992393 | 352 | } else { |
e48af19f DH |
353 | utemp64 = temp64; |
354 | do_div(utemp64, mtemp); | |
355 | freq_adj += utemp64; | |
f1992393 | 356 | } |
4c7ee8de | 357 | } |
04b617e7 RZ |
358 | freq_adj += time_freq; |
359 | freq_adj = min(freq_adj, (s64)MAXFREQ_NSEC); | |
360 | time_freq = max(freq_adj, (s64)-MAXFREQ_NSEC); | |
d62ac21a | 361 | time_offset = div_long_long_rem_signed(time_offset, |
362 | NTP_INTERVAL_FREQ, | |
363 | &rem); | |
364 | time_offset <<= SHIFT_UPDATE; | |
4c7ee8de | 365 | } /* STA_PLL */ |
366 | } /* txc->modes & ADJ_OFFSET */ | |
b0ee7556 | 367 | if (txc->modes & ADJ_TICK) |
4c7ee8de | 368 | tick_usec = txc->tick; |
b0ee7556 | 369 | |
dc6a43e4 | 370 | if (txc->modes & (ADJ_TICK|ADJ_FREQUENCY|ADJ_OFFSET)) |
b0ee7556 | 371 | ntp_update_frequency(); |
4c7ee8de | 372 | } /* txc->modes */ |
373 | leave: if ((time_status & (STA_UNSYNC|STA_CLOCKERR)) != 0) | |
374 | result = TIME_ERROR; | |
375 | ||
52bfb360 JS |
376 | if ((txc->modes == ADJ_OFFSET_SINGLESHOT) || |
377 | (txc->modes == ADJ_OFFSET_SS_READ)) | |
d62ac21a | 378 | txc->offset = save_adjust; |
3d3675cc | 379 | else |
d62ac21a | 380 | txc->offset = ((long)shift_right(time_offset, SHIFT_UPDATE)) * |
381 | NTP_INTERVAL_FREQ / 1000; | |
382 | txc->freq = (time_freq / NSEC_PER_USEC) << | |
383 | (SHIFT_USEC - SHIFT_NSEC); | |
4c7ee8de | 384 | txc->maxerror = time_maxerror; |
385 | txc->esterror = time_esterror; | |
386 | txc->status = time_status; | |
387 | txc->constant = time_constant; | |
70bc42f9 | 388 | txc->precision = 1; |
97eebe13 | 389 | txc->tolerance = MAXFREQ; |
4c7ee8de | 390 | txc->tick = tick_usec; |
391 | ||
392 | /* PPS is not implemented, so these are zero */ | |
393 | txc->ppsfreq = 0; | |
394 | txc->jitter = 0; | |
395 | txc->shift = 0; | |
396 | txc->stabil = 0; | |
397 | txc->jitcnt = 0; | |
398 | txc->calcnt = 0; | |
399 | txc->errcnt = 0; | |
400 | txc->stbcnt = 0; | |
401 | write_sequnlock_irq(&xtime_lock); | |
402 | do_gettimeofday(&txc->time); | |
82644459 | 403 | notify_cmos_timer(); |
4c7ee8de | 404 | return(result); |
405 | } | |
10a398d0 RZ |
406 | |
407 | static int __init ntp_tick_adj_setup(char *str) | |
408 | { | |
409 | ntp_tick_adj = simple_strtol(str, NULL, 0); | |
410 | return 1; | |
411 | } | |
412 | ||
413 | __setup("ntp_tick_adj=", ntp_tick_adj_setup); |