timex.h 11 KB

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  1. /*****************************************************************************
  2. * *
  3. * Copyright (c) David L. Mills 1993 *
  4. * *
  5. * Permission to use, copy, modify, and distribute this software and its *
  6. * documentation for any purpose and without fee is hereby granted, provided *
  7. * that the above copyright notice appears in all copies and that both the *
  8. * copyright notice and this permission notice appear in supporting *
  9. * documentation, and that the name University of Delaware not be used in *
  10. * advertising or publicity pertaining to distribution of the software *
  11. * without specific, written prior permission. The University of Delaware *
  12. * makes no representations about the suitability this software for any *
  13. * purpose. It is provided "as is" without express or implied warranty. *
  14. * *
  15. *****************************************************************************/
  16. /*
  17. * Modification history timex.h
  18. *
  19. * 29 Dec 97 Russell King
  20. * Moved CLOCK_TICK_RATE, CLOCK_TICK_FACTOR and FINETUNE to asm/timex.h
  21. * for ARM machines
  22. *
  23. * 9 Jan 97 Adrian Sun
  24. * Shifted LATCH define to allow access to alpha machines.
  25. *
  26. * 26 Sep 94 David L. Mills
  27. * Added defines for hybrid phase/frequency-lock loop.
  28. *
  29. * 19 Mar 94 David L. Mills
  30. * Moved defines from kernel routines to header file and added new
  31. * defines for PPS phase-lock loop.
  32. *
  33. * 20 Feb 94 David L. Mills
  34. * Revised status codes and structures for external clock and PPS
  35. * signal discipline.
  36. *
  37. * 28 Nov 93 David L. Mills
  38. * Adjusted parameters to improve stability and increase poll
  39. * interval.
  40. *
  41. * 17 Sep 93 David L. Mills
  42. * Created file $NTP/include/sys/timex.h
  43. * 07 Oct 93 Torsten Duwe
  44. * Derived linux/timex.h
  45. * 1995-08-13 Torsten Duwe
  46. * kernel PLL updated to 1994-12-13 specs (rfc-1589)
  47. * 1997-08-30 Ulrich Windl
  48. * Added new constant NTP_PHASE_LIMIT
  49. * 2004-08-12 Christoph Lameter
  50. * Reworked time interpolation logic
  51. */
  52. #ifndef _LINUX_TIMEX_H
  53. #define _LINUX_TIMEX_H
  54. #include <linux/compiler.h>
  55. #include <linux/time.h>
  56. #include <asm/param.h>
  57. /*
  58. * SHIFT_KG and SHIFT_KF establish the damping of the PLL and are chosen
  59. * for a slightly underdamped convergence characteristic. SHIFT_KH
  60. * establishes the damping of the FLL and is chosen by wisdom and black
  61. * art.
  62. *
  63. * MAXTC establishes the maximum time constant of the PLL. With the
  64. * SHIFT_KG and SHIFT_KF values given and a time constant range from
  65. * zero to MAXTC, the PLL will converge in 15 minutes to 16 hours,
  66. * respectively.
  67. */
  68. #define SHIFT_PLL 4 /* PLL frequency factor (shift) */
  69. #define SHIFT_FLL 2 /* FLL frequency factor (shift) */
  70. #define MAXTC 10 /* maximum time constant (shift) */
  71. /*
  72. * The SHIFT_UPDATE define establishes the decimal point of the
  73. * time_offset variable which represents the current offset with
  74. * respect to standard time.
  75. *
  76. * SHIFT_USEC defines the scaling (shift) of the time_freq and
  77. * time_tolerance variables, which represent the current frequency
  78. * offset and maximum frequency tolerance.
  79. */
  80. #define SHIFT_UPDATE (SHIFT_HZ + 1) /* time offset scale (shift) */
  81. #define SHIFT_USEC 16 /* frequency offset scale (shift) */
  82. #define SHIFT_NSEC 12 /* kernel frequency offset scale */
  83. #define MAXPHASE 512000L /* max phase error (us) */
  84. #define MAXFREQ (512L << SHIFT_USEC) /* max frequency error (ppm) */
  85. #define MAXFREQ_NSEC (512000L << SHIFT_NSEC) /* max frequency error (ppb) */
  86. #define MINSEC 256 /* min interval between updates (s) */
  87. #define MAXSEC 2048 /* max interval between updates (s) */
  88. #define NTP_PHASE_LIMIT (MAXPHASE << 5) /* beyond max. dispersion */
  89. /*
  90. * syscall interface - used (mainly by NTP daemon)
  91. * to discipline kernel clock oscillator
  92. */
  93. struct timex {
  94. unsigned int modes; /* mode selector */
  95. long offset; /* time offset (usec) */
  96. long freq; /* frequency offset (scaled ppm) */
  97. long maxerror; /* maximum error (usec) */
  98. long esterror; /* estimated error (usec) */
  99. int status; /* clock command/status */
  100. long constant; /* pll time constant */
  101. long precision; /* clock precision (usec) (read only) */
  102. long tolerance; /* clock frequency tolerance (ppm)
  103. * (read only)
  104. */
  105. struct timeval time; /* (read only) */
  106. long tick; /* (modified) usecs between clock ticks */
  107. long ppsfreq; /* pps frequency (scaled ppm) (ro) */
  108. long jitter; /* pps jitter (us) (ro) */
  109. int shift; /* interval duration (s) (shift) (ro) */
  110. long stabil; /* pps stability (scaled ppm) (ro) */
  111. long jitcnt; /* jitter limit exceeded (ro) */
  112. long calcnt; /* calibration intervals (ro) */
  113. long errcnt; /* calibration errors (ro) */
  114. long stbcnt; /* stability limit exceeded (ro) */
  115. int :32; int :32; int :32; int :32;
  116. int :32; int :32; int :32; int :32;
  117. int :32; int :32; int :32; int :32;
  118. };
  119. /*
  120. * Mode codes (timex.mode)
  121. */
  122. #define ADJ_OFFSET 0x0001 /* time offset */
  123. #define ADJ_FREQUENCY 0x0002 /* frequency offset */
  124. #define ADJ_MAXERROR 0x0004 /* maximum time error */
  125. #define ADJ_ESTERROR 0x0008 /* estimated time error */
  126. #define ADJ_STATUS 0x0010 /* clock status */
  127. #define ADJ_TIMECONST 0x0020 /* pll time constant */
  128. #define ADJ_TICK 0x4000 /* tick value */
  129. #define ADJ_OFFSET_SINGLESHOT 0x8001 /* old-fashioned adjtime */
  130. /* xntp 3.4 compatibility names */
  131. #define MOD_OFFSET ADJ_OFFSET
  132. #define MOD_FREQUENCY ADJ_FREQUENCY
  133. #define MOD_MAXERROR ADJ_MAXERROR
  134. #define MOD_ESTERROR ADJ_ESTERROR
  135. #define MOD_STATUS ADJ_STATUS
  136. #define MOD_TIMECONST ADJ_TIMECONST
  137. #define MOD_CLKB ADJ_TICK
  138. #define MOD_CLKA ADJ_OFFSET_SINGLESHOT /* 0x8000 in original */
  139. /*
  140. * Status codes (timex.status)
  141. */
  142. #define STA_PLL 0x0001 /* enable PLL updates (rw) */
  143. #define STA_PPSFREQ 0x0002 /* enable PPS freq discipline (rw) */
  144. #define STA_PPSTIME 0x0004 /* enable PPS time discipline (rw) */
  145. #define STA_FLL 0x0008 /* select frequency-lock mode (rw) */
  146. #define STA_INS 0x0010 /* insert leap (rw) */
  147. #define STA_DEL 0x0020 /* delete leap (rw) */
  148. #define STA_UNSYNC 0x0040 /* clock unsynchronized (rw) */
  149. #define STA_FREQHOLD 0x0080 /* hold frequency (rw) */
  150. #define STA_PPSSIGNAL 0x0100 /* PPS signal present (ro) */
  151. #define STA_PPSJITTER 0x0200 /* PPS signal jitter exceeded (ro) */
  152. #define STA_PPSWANDER 0x0400 /* PPS signal wander exceeded (ro) */
  153. #define STA_PPSERROR 0x0800 /* PPS signal calibration error (ro) */
  154. #define STA_CLOCKERR 0x1000 /* clock hardware fault (ro) */
  155. #define STA_RONLY (STA_PPSSIGNAL | STA_PPSJITTER | STA_PPSWANDER | \
  156. STA_PPSERROR | STA_CLOCKERR) /* read-only bits */
  157. /*
  158. * Clock states (time_state)
  159. */
  160. #define TIME_OK 0 /* clock synchronized, no leap second */
  161. #define TIME_INS 1 /* insert leap second */
  162. #define TIME_DEL 2 /* delete leap second */
  163. #define TIME_OOP 3 /* leap second in progress */
  164. #define TIME_WAIT 4 /* leap second has occurred */
  165. #define TIME_ERROR 5 /* clock not synchronized */
  166. #define TIME_BAD TIME_ERROR /* bw compat */
  167. #ifdef __KERNEL__
  168. #include <asm/timex.h>
  169. /*
  170. * kernel variables
  171. * Note: maximum error = NTP synch distance = dispersion + delay / 2;
  172. * estimated error = NTP dispersion.
  173. */
  174. extern unsigned long tick_usec; /* USER_HZ period (usec) */
  175. extern unsigned long tick_nsec; /* ACTHZ period (nsec) */
  176. extern int tickadj; /* amount of adjustment per tick */
  177. /*
  178. * phase-lock loop variables
  179. */
  180. extern int time_status; /* clock synchronization status bits */
  181. extern long time_maxerror; /* maximum error */
  182. extern long time_esterror; /* estimated error */
  183. extern long time_freq; /* frequency offset (scaled ppm) */
  184. extern long time_adjust; /* The amount of adjtime left */
  185. extern void ntp_clear(void);
  186. /**
  187. * ntp_synced - Returns 1 if the NTP status is not UNSYNC
  188. *
  189. */
  190. static inline int ntp_synced(void)
  191. {
  192. return !(time_status & STA_UNSYNC);
  193. }
  194. /* Required to safely shift negative values */
  195. #define shift_right(x, s) ({ \
  196. __typeof__(x) __x = (x); \
  197. __typeof__(s) __s = (s); \
  198. __x < 0 ? -(-__x >> __s) : __x >> __s; \
  199. })
  200. #ifdef CONFIG_TIME_INTERPOLATION
  201. #define TIME_SOURCE_CPU 0
  202. #define TIME_SOURCE_MMIO64 1
  203. #define TIME_SOURCE_MMIO32 2
  204. #define TIME_SOURCE_FUNCTION 3
  205. /* For proper operations time_interpolator clocks must run slightly slower
  206. * than the standard clock since the interpolator may only correct by having
  207. * time jump forward during a tick. A slower clock is usually a side effect
  208. * of the integer divide of the nanoseconds in a second by the frequency.
  209. * The accuracy of the division can be increased by specifying a shift.
  210. * However, this may cause the clock not to be slow enough.
  211. * The interpolator will self-tune the clock by slowing down if no
  212. * resets occur or speeding up if the time jumps per analysis cycle
  213. * become too high.
  214. *
  215. * Setting jitter compensates for a fluctuating timesource by comparing
  216. * to the last value read from the timesource to insure that an earlier value
  217. * is not returned by a later call. The price to pay
  218. * for the compensation is that the timer routines are not as scalable anymore.
  219. */
  220. struct time_interpolator {
  221. u16 source; /* time source flags */
  222. u8 shift; /* increases accuracy of multiply by shifting. */
  223. /* Note that bits may be lost if shift is set too high */
  224. u8 jitter; /* if set compensate for fluctuations */
  225. u32 nsec_per_cyc; /* set by register_time_interpolator() */
  226. void *addr; /* address of counter or function */
  227. cycles_t mask; /* mask the valid bits of the counter */
  228. unsigned long offset; /* nsec offset at last update of interpolator */
  229. u64 last_counter; /* counter value in units of the counter at last update */
  230. cycles_t last_cycle; /* Last timer value if TIME_SOURCE_JITTER is set */
  231. u64 frequency; /* frequency in counts/second */
  232. long drift; /* drift in parts-per-million (or -1) */
  233. unsigned long skips; /* skips forward */
  234. unsigned long ns_skipped; /* nanoseconds skipped */
  235. struct time_interpolator *next;
  236. };
  237. extern void register_time_interpolator(struct time_interpolator *);
  238. extern void unregister_time_interpolator(struct time_interpolator *);
  239. extern void time_interpolator_reset(void);
  240. extern unsigned long time_interpolator_get_offset(void);
  241. extern void time_interpolator_update(long delta_nsec);
  242. #else /* !CONFIG_TIME_INTERPOLATION */
  243. static inline void time_interpolator_reset(void)
  244. {
  245. }
  246. static inline void time_interpolator_update(long delta_nsec)
  247. {
  248. }
  249. #endif /* !CONFIG_TIME_INTERPOLATION */
  250. #define TICK_LENGTH_SHIFT 32
  251. #ifdef CONFIG_NO_HZ
  252. #define NTP_INTERVAL_FREQ (2)
  253. #else
  254. #define NTP_INTERVAL_FREQ (HZ)
  255. #endif
  256. #define NTP_INTERVAL_LENGTH (NSEC_PER_SEC/NTP_INTERVAL_FREQ)
  257. /* Returns how long ticks are at present, in ns / 2^(SHIFT_SCALE-10). */
  258. extern u64 current_tick_length(void);
  259. extern void second_overflow(void);
  260. extern void update_ntp_one_tick(void);
  261. extern int do_adjtimex(struct timex *);
  262. /* Don't use! Compatibility define for existing users. */
  263. #define tickadj (500/HZ ? : 1)
  264. #endif /* KERNEL */
  265. #endif /* LINUX_TIMEX_H */