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