include/linux/timex.h

   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 /*
  18  * Modification history timex.h
  19  *
  20  * 29 Dec 97    Russell King
  21  *      Moved CLOCK_TICK_RATE, CLOCK_TICK_FACTOR and FINETUNE to asm/timex.h
  22  *      for ARM machines
  23  *
  24  *  9 Jan 97    Adrian Sun
  25  *      Shifted LATCH define to allow access to alpha machines.
  26  *
  27  * 26 Sep 94    David L. Mills
  28  *      Added defines for hybrid phase/frequency-lock loop.
  29  *
  30  * 19 Mar 94    David L. Mills
  31  *      Moved defines from kernel routines to header file and added new
  32  *      defines for PPS phase-lock loop.
  33  *
  34  * 20 Feb 94    David L. Mills
  35  *      Revised status codes and structures for external clock and PPS
  36  *      signal discipline.
  37  *
  38  * 28 Nov 93    David L. Mills
  39  *      Adjusted parameters to improve stability and increase poll
  40  *      interval.
  41  *
  42  * 17 Sep 93    David L. Mills
  43  *      Created file $NTP/include/sys/timex.h
  44  * 07 Oct 93    Torsten Duwe
  45  *      Derived linux/timex.h
  46  * 1995-08-13    Torsten Duwe
  47  *      kernel PLL updated to 1994-12-13 specs (rfc-1589)
  48  * 1997-08-30    Ulrich Windl
  49  *      Added new constant NTP_PHASE_LIMIT
  50  * 2004-08-12    Christoph Lameter
  51  *      Reworked time interpolation logic
  52  */
  53 #ifndef _LINUX_TIMEX_H
  54 #define _LINUX_TIMEX_H
  55
  56 #include <linux/compiler.h>
  57 #include <linux/time.h>
  58
  59 #include <asm/param.h>
  60
  61 /*
  62  * SHIFT_KG and SHIFT_KF establish the damping of the PLL and are chosen
  63  * for a slightly underdamped convergence characteristic. SHIFT_KH
  64  * establishes the damping of the FLL and is chosen by wisdom and black
  65  * art.
  66  *
  67  * MAXTC establishes the maximum time constant of the PLL. With the
  68  * SHIFT_KG and SHIFT_KF values given and a time constant range from
  69  * zero to MAXTC, the PLL will converge in 15 minutes to 16 hours,
  70  * respectively.
  71  */
  72 #define SHIFT_PLL       4       /* PLL frequency factor (shift) */
  73 #define SHIFT_FLL       2       /* FLL frequency factor (shift) */
  74 #define MAXTC           10      /* maximum time constant (shift) */
  75
  76 /*
  77  * The SHIFT_UPDATE define establishes the decimal point of the
  78  * time_offset variable which represents the current offset with
  79  * respect to standard time.
  80  *
  81  * SHIFT_USEC defines the scaling (shift) of the time_freq and
  82  * time_tolerance variables, which represent the current frequency
  83  * offset and maximum frequency tolerance.
  84  */
  85 #define SHIFT_UPDATE (SHIFT_HZ + 1) /* time offset scale (shift) */
  86 #define SHIFT_USEC 16           /* frequency offset scale (shift) */
  87 #define SHIFT_NSEC 12           /* kernel frequency offset scale */
  88
  89 #define MAXPHASE 512000L        /* max phase error (us) */
  90 #define MAXFREQ (512L << SHIFT_USEC)  /* max frequency error (ppm) */
  91 #define MAXFREQ_NSEC (512000L << SHIFT_NSEC) /* max frequency error (ppb) */
  92 #define MINSEC 256              /* min interval between updates (s) */
  93 #define MAXSEC 2048             /* max interval between updates (s) */
  94 #define NTP_PHASE_LIMIT (MAXPHASE << 5) /* beyond max. dispersion */
  95
  96 /*
  97  * syscall interface - used (mainly by NTP daemon)
  98  * to discipline kernel clock oscillator
  99  */
 100 struct timex {
 101         unsigned int modes;     /* mode selector */
 102         long offset;            /* time offset (usec) */
 103         long freq;              /* frequency offset (scaled ppm) */
 104         long maxerror;          /* maximum error (usec) */
 105         long esterror;          /* estimated error (usec) */
 106         int status;             /* clock command/status */
 107         long constant;          /* pll time constant */
 108         long precision;         /* clock precision (usec) (read only) */
 109         long tolerance;         /* clock frequency tolerance (ppm)
 110                                  * (read only)
 111                                  */
 112         struct timeval time;    /* (read only) */
 113         long tick;              /* (modified) usecs between clock ticks */
 114
 115         long ppsfreq;           /* pps frequency (scaled ppm) (ro) */
 116         long jitter;            /* pps jitter (us) (ro) */
 117         int shift;              /* interval duration (s) (shift) (ro) */
 118         long stabil;            /* pps stability (scaled ppm) (ro) */
 119         long jitcnt;            /* jitter limit exceeded (ro) */
 120         long calcnt;            /* calibration intervals (ro) */
 121         long errcnt;            /* calibration errors (ro) */
 122         long stbcnt;            /* stability limit exceeded (ro) */
 123
 124         int  :32; int  :32; int  :32; int  :32;
 125         int  :32; int  :32; int  :32; int  :32;
 126         int  :32; int  :32; int  :32; int  :32;
 127 };
 128
 129 /*
 130  * Mode codes (timex.mode)
 131  */
 132 #define ADJ_OFFSET              0x0001  /* time offset */
 133 #define ADJ_FREQUENCY           0x0002  /* frequency offset */
 134 #define ADJ_MAXERROR            0x0004  /* maximum time error */
 135 #define ADJ_ESTERROR            0x0008  /* estimated time error */
 136 #define ADJ_STATUS              0x0010  /* clock status */
 137 #define ADJ_TIMECONST           0x0020  /* pll time constant */
 138 #define ADJ_TICK                0x4000  /* tick value */
 139 #define ADJ_OFFSET_SINGLESHOT   0x8001  /* old-fashioned adjtime */
 140
 141 /* xntp 3.4 compatibility names */
 142 #define MOD_OFFSET      ADJ_OFFSET
 143 #define MOD_FREQUENCY   ADJ_FREQUENCY
 144 #define MOD_MAXERROR    ADJ_MAXERROR
 145 #define MOD_ESTERROR    ADJ_ESTERROR
 146 #define MOD_STATUS      ADJ_STATUS
 147 #define MOD_TIMECONST   ADJ_TIMECONST
 148 #define MOD_CLKB        ADJ_TICK
 149 #define MOD_CLKA        ADJ_OFFSET_SINGLESHOT /* 0x8000 in original */
 150
 151
 152 /*
 153  * Status codes (timex.status)
 154  */
 155 #define STA_PLL         0x0001  /* enable PLL updates (rw) */
 156 #define STA_PPSFREQ     0x0002  /* enable PPS freq discipline (rw) */
 157 #define STA_PPSTIME     0x0004  /* enable PPS time discipline (rw) */
 158 #define STA_FLL         0x0008  /* select frequency-lock mode (rw) */
 159
 160 #define STA_INS         0x0010  /* insert leap (rw) */
 161 #define STA_DEL         0x0020  /* delete leap (rw) */
 162 #define STA_UNSYNC      0x0040  /* clock unsynchronized (rw) */
 163 #define STA_FREQHOLD    0x0080  /* hold frequency (rw) */
 164
 165 #define STA_PPSSIGNAL   0x0100  /* PPS signal present (ro) */
 166 #define STA_PPSJITTER   0x0200  /* PPS signal jitter exceeded (ro) */
 167 #define STA_PPSWANDER   0x0400  /* PPS signal wander exceeded (ro) */
 168 #define STA_PPSERROR    0x0800  /* PPS signal calibration error (ro) */
 169
 170 #define STA_CLOCKERR    0x1000  /* clock hardware fault (ro) */
 171
 172 #define STA_RONLY (STA_PPSSIGNAL | STA_PPSJITTER | STA_PPSWANDER | \
 173     STA_PPSERROR | STA_CLOCKERR) /* read-only bits */
 174
 175 /*
 176  * Clock states (time_state)
 177  */
 178 #define TIME_OK         0       /* clock synchronized, no leap second */
 179 #define TIME_INS        1       /* insert leap second */
 180 #define TIME_DEL        2       /* delete leap second */
 181 #define TIME_OOP        3       /* leap second in progress */
 182 #define TIME_WAIT       4       /* leap second has occurred */
 183 #define TIME_ERROR      5       /* clock not synchronized */
 184 #define TIME_BAD        TIME_ERROR /* bw compat */
 185
 186 #ifdef __KERNEL__
 187 #include <asm/timex.h>
 188
 189 /*
 190  * kernel variables
 191  * Note: maximum error = NTP synch distance = dispersion + delay / 2;
 192  * estimated error = NTP dispersion.
 193  */
 194 extern unsigned long tick_usec;         /* USER_HZ period (usec) */
 195 extern unsigned long tick_nsec;         /* ACTHZ          period (nsec) */
 196 extern int tickadj;                     /* amount of adjustment per tick */
 197
 198 /*
 199  * phase-lock loop variables
 200  */
 201 extern int time_status;         /* clock synchronization status bits */
 202 extern long time_maxerror;      /* maximum error */
 203 extern long time_esterror;      /* estimated error */
 204
 205 extern long time_freq;          /* frequency offset (scaled ppm) */
 206
 207 extern long time_adjust;        /* The amount of adjtime left */
 208
 209 extern void ntp_clear(void);
 210
 211 /**
 212  * ntp_synced - Returns 1 if the NTP status is not UNSYNC
 213  *
 214  */
 215 static inline int ntp_synced(void)
 216 {
 217         return !(time_status & STA_UNSYNC);
 218 }
 219
 220 /* Required to safely shift negative values */
 221 #define shift_right(x, s) ({    \
 222         __typeof__(x) __x = (x);        \
 223         __typeof__(s) __s = (s);        \
 224         __x < 0 ? -(-__x >> __s) : __x >> __s;  \
 225 })
 226
 227
 228 #ifdef CONFIG_TIME_INTERPOLATION
 229
 230 #define TIME_SOURCE_CPU 0
 231 #define TIME_SOURCE_MMIO64 1
 232 #define TIME_SOURCE_MMIO32 2
 233 #define TIME_SOURCE_FUNCTION 3
 234
 235 /* For proper operations time_interpolator clocks must run slightly slower
 236  * than the standard clock since the interpolator may only correct by having
 237  * time jump forward during a tick. A slower clock is usually a side effect
 238  * of the integer divide of the nanoseconds in a second by the frequency.
 239  * The accuracy of the division can be increased by specifying a shift.
 240  * However, this may cause the clock not to be slow enough.
 241  * The interpolator will self-tune the clock by slowing down if no
 242  * resets occur or speeding up if the time jumps per analysis cycle
 243  * become too high.
 244  *
 245  * Setting jitter compensates for a fluctuating timesource by comparing
 246  * to the last value read from the timesource to insure that an earlier value
 247  * is not returned by a later call. The price to pay
 248  * for the compensation is that the timer routines are not as scalable anymore.
 249  */
 250
 251 struct time_interpolator {
 252         u16 source;                     /* time source flags */
 253         u8 shift;                       /* increases accuracy of multiply by shifting. */
 254                                 /* Note that bits may be lost if shift is set too high */
 255         u8 jitter;                      /* if set compensate for fluctuations */
 256         u32 nsec_per_cyc;               /* set by register_time_interpolator() */
 257         void *addr;                     /* address of counter or function */
 258         u64 mask;                       /* mask the valid bits of the counter */
 259         unsigned long offset;           /* nsec offset at last update of interpolator */
 260         u64 last_counter;               /* counter value in units of the counter at last update */
 261         u64 last_cycle;                 /* Last timer value if TIME_SOURCE_JITTER is set */
 262         u64 frequency;                  /* frequency in counts/second */
 263         long drift;                     /* drift in parts-per-million (or -1) */
 264         unsigned long skips;            /* skips forward */
 265         unsigned long ns_skipped;       /* nanoseconds skipped */
 266         struct time_interpolator *next;
 267 };
 268
 269 extern void register_time_interpolator(struct time_interpolator *);
 270 extern void unregister_time_interpolator(struct time_interpolator *);
 271 extern void time_interpolator_reset(void);
 272 extern unsigned long time_interpolator_get_offset(void);
 273 extern void time_interpolator_update(long delta_nsec);
 274
 275 #else /* !CONFIG_TIME_INTERPOLATION */
 276
 277 static inline void time_interpolator_reset(void)
 278 {
 279 }
 280
 281 static inline void time_interpolator_update(long delta_nsec)
 282 {
 283 }
 284
 285 #endif /* !CONFIG_TIME_INTERPOLATION */
 286
 287 #define TICK_LENGTH_SHIFT       32
 288
 289 /* Returns how long ticks are at present, in ns / 2^(SHIFT_SCALE-10). */
 290 extern u64 current_tick_length(void);
 291
 292 extern void second_overflow(void);
 293 extern void update_ntp_one_tick(void);
 294 extern int do_adjtimex(struct timex *);
 295
 296 /* Don't use! Compatibility define for existing users. */
 297 #define tickadj (500/HZ ? : 1)
 298
 299 #endif /* KERNEL */
 300
 301 #endif /* LINUX_TIMEX_H */