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