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  */
  51 #ifndef _LINUX_TIMEX_H
  52 #define _LINUX_TIMEX_H
  53
  54 #include <asm/param.h>
  55
  56 /*
  57  * The following defines establish the engineering parameters of the PLL
  58  * model. The HZ variable establishes the timer interrupt frequency, 100 Hz
  59  * for the SunOS kernel, 256 Hz for the Ultrix kernel and 1024 Hz for the
  60  * OSF/1 kernel. The SHIFT_HZ define expresses the same value as the
  61  * nearest power of two in order to avoid hardware multiply operations.
  62  */
  63 #if HZ >= 24 && HZ < 48
  64 # define SHIFT_HZ       5
  65 #elif HZ >= 48 && HZ < 96
  66 # define SHIFT_HZ       6
  67 #elif HZ >= 96 && HZ < 192
  68 # define SHIFT_HZ       7
  69 #elif HZ >= 192 && HZ < 384
  70 # define SHIFT_HZ       8
  71 #elif HZ >= 384 && HZ < 768
  72 # define SHIFT_HZ       9
  73 #elif HZ >= 768 && HZ < 1536
  74 # define SHIFT_HZ       10
  75 #else
  76 # error You lose.
  77 #endif
  78
  79 /*
  80  * SHIFT_KG and SHIFT_KF establish the damping of the PLL and are chosen
  81  * for a slightly underdamped convergence characteristic. SHIFT_KH
  82  * establishes the damping of the FLL and is chosen by wisdom and black
  83  * art.
  84  *
  85  * MAXTC establishes the maximum time constant of the PLL. With the
  86  * SHIFT_KG and SHIFT_KF values given and a time constant range from
  87  * zero to MAXTC, the PLL will converge in 15 minutes to 16 hours,
  88  * respectively.
  89  */
  90 #define SHIFT_KG 6              /* phase factor (shift) */
  91 #define SHIFT_KF 16             /* PLL frequency factor (shift) */
  92 #define SHIFT_KH 2              /* FLL frequency factor (shift) */
  93 #define MAXTC 6                 /* maximum time constant (shift) */
  94
  95 /*
  96  * The SHIFT_SCALE define establishes the decimal point of the time_phase
  97  * variable which serves as an extension to the low-order bits of the
  98  * system clock variable. The SHIFT_UPDATE define establishes the decimal
  99  * point of the time_offset variable which represents the current offset
 100  * with respect to standard time. The FINEUSEC define represents 1 usec in
 101  * scaled units.
 102  *
 103  * SHIFT_USEC defines the scaling (shift) of the time_freq and
 104  * time_tolerance variables, which represent the current frequency
 105  * offset and maximum frequency tolerance.
 106  *
 107  * FINEUSEC is 1 us in SHIFT_UPDATE units of the time_phase variable.
 108  */
 109 #define SHIFT_SCALE 22          /* phase scale (shift) */
 110 #define SHIFT_UPDATE (SHIFT_KG + MAXTC) /* time offset scale (shift) */
 111 #define SHIFT_USEC 16           /* frequency offset scale (shift) */
 112 #define FINEUSEC (1L << SHIFT_SCALE) /* 1 us in phase units */
 113
 114 #define MAXPHASE 512000L        /* max phase error (us) */
 115 #define MAXFREQ (512L << SHIFT_USEC)  /* max frequency error (ppm) */
 116 #define MAXTIME (200L << PPS_AVG) /* max PPS error (jitter) (200 us) */
 117 #define MINSEC 16L              /* min interval between updates (s) */
 118 #define MAXSEC 1200L            /* max interval between updates (s) */
 119 #define NTP_PHASE_LIMIT (MAXPHASE << 5) /* beyond max. dispersion */
 120
 121 /*
 122  * The following defines are used only if a pulse-per-second (PPS)
 123  * signal is available and connected via a modem control lead, such as
 124  * produced by the optional ppsclock feature incorporated in the Sun
 125  * asynch driver. They establish the design parameters of the frequency-
 126  * lock loop used to discipline the CPU clock oscillator to the PPS
 127  * signal.
 128  *
 129  * PPS_AVG is the averaging factor for the frequency loop, as well as
 130  * the time and frequency dispersion.
 131  *
 132  * PPS_SHIFT and PPS_SHIFTMAX specify the minimum and maximum
 133  * calibration intervals, respectively, in seconds as a power of two.
 134  *
 135  * PPS_VALID is the maximum interval before the PPS signal is considered
 136  * invalid and protocol updates used directly instead.
 137  *
 138  * MAXGLITCH is the maximum interval before a time offset of more than
 139  * MAXTIME is believed.
 140  */
 141 #define PPS_AVG 2               /* pps averaging constant (shift) */
 142 #define PPS_SHIFT 2             /* min interval duration (s) (shift) */
 143 #define PPS_SHIFTMAX 8          /* max interval duration (s) (shift) */
 144 #define PPS_VALID 120           /* pps signal watchdog max (s) */
 145 #define MAXGLITCH 30            /* pps signal glitch max (s) */
 146
 147 /*
 148  * Pick up the architecture specific timex specifications
 149  */
 150 #include <asm/timex.h>
 151
 152 /* LATCH is used in the interval timer and ftape setup. */
 153 #define LATCH  ((CLOCK_TICK_RATE + HZ/2) / HZ)  /* For divider */
 154
 155 /*
 156  * syscall interface - used (mainly by NTP daemon)
 157  * to discipline kernel clock oscillator
 158  */
 159 struct timex {
 160         unsigned int modes;     /* mode selector */
 161         long offset;            /* time offset (usec) */
 162         long freq;              /* frequency offset (scaled ppm) */
 163         long maxerror;          /* maximum error (usec) */
 164         long esterror;          /* estimated error (usec) */
 165         int status;             /* clock command/status */
 166         long constant;          /* pll time constant */
 167         long precision;         /* clock precision (usec) (read only) */
 168         long tolerance;         /* clock frequency tolerance (ppm)
 169                                  * (read only)
 170                                  */
 171         struct timeval time;    /* (read only) */
 172         long tick;              /* (modified) usecs between clock ticks */
 173
 174         long ppsfreq;           /* pps frequency (scaled ppm) (ro) */
 175         long jitter;            /* pps jitter (us) (ro) */
 176         int shift;              /* interval duration (s) (shift) (ro) */
 177         long stabil;            /* pps stability (scaled ppm) (ro) */
 178         long jitcnt;            /* jitter limit exceeded (ro) */
 179         long calcnt;            /* calibration intervals (ro) */
 180         long errcnt;            /* calibration errors (ro) */
 181         long stbcnt;            /* stability limit exceeded (ro) */
 182
 183         int  :32; int  :32; int  :32; int  :32;
 184         int  :32; int  :32; int  :32; int  :32;
 185         int  :32; int  :32; int  :32; int  :32;
 186 };
 187
 188 /*
 189  * Mode codes (timex.mode)
 190  */
 191 #define ADJ_OFFSET              0x0001  /* time offset */
 192 #define ADJ_FREQUENCY           0x0002  /* frequency offset */
 193 #define ADJ_MAXERROR            0x0004  /* maximum time error */
 194 #define ADJ_ESTERROR            0x0008  /* estimated time error */
 195 #define ADJ_STATUS              0x0010  /* clock status */
 196 #define ADJ_TIMECONST           0x0020  /* pll time constant */
 197 #define ADJ_TICK                0x4000  /* tick value */
 198 #define ADJ_OFFSET_SINGLESHOT   0x8001  /* old-fashioned adjtime */
 199
 200 /* xntp 3.4 compatibility names */
 201 #define MOD_OFFSET      ADJ_OFFSET
 202 #define MOD_FREQUENCY   ADJ_FREQUENCY
 203 #define MOD_MAXERROR    ADJ_MAXERROR
 204 #define MOD_ESTERROR    ADJ_ESTERROR
 205 #define MOD_STATUS      ADJ_STATUS
 206 #define MOD_TIMECONST   ADJ_TIMECONST
 207 #define MOD_CLKB        ADJ_TICK
 208 #define MOD_CLKA        ADJ_OFFSET_SINGLESHOT /* 0x8000 in original */
 209
 210
 211 /*
 212  * Status codes (timex.status)
 213  */
 214 #define STA_PLL         0x0001  /* enable PLL updates (rw) */
 215 #define STA_PPSFREQ     0x0002  /* enable PPS freq discipline (rw) */
 216 #define STA_PPSTIME     0x0004  /* enable PPS time discipline (rw) */
 217 #define STA_FLL         0x0008  /* select frequency-lock mode (rw) */
 218
 219 #define STA_INS         0x0010  /* insert leap (rw) */
 220 #define STA_DEL         0x0020  /* delete leap (rw) */
 221 #define STA_UNSYNC      0x0040  /* clock unsynchronized (rw) */
 222 #define STA_FREQHOLD    0x0080  /* hold frequency (rw) */
 223
 224 #define STA_PPSSIGNAL   0x0100  /* PPS signal present (ro) */
 225 #define STA_PPSJITTER   0x0200  /* PPS signal jitter exceeded (ro) */
 226 #define STA_PPSWANDER   0x0400  /* PPS signal wander exceeded (ro) */
 227 #define STA_PPSERROR    0x0800  /* PPS signal calibration error (ro) */
 228
 229 #define STA_CLOCKERR    0x1000  /* clock hardware fault (ro) */
 230
 231 #define STA_RONLY (STA_PPSSIGNAL | STA_PPSJITTER | STA_PPSWANDER | \
 232     STA_PPSERROR | STA_CLOCKERR) /* read-only bits */
 233
 234 /*
 235  * Clock states (time_state)
 236  */
 237 #define TIME_OK         0       /* clock synchronized, no leap second */
 238 #define TIME_INS        1       /* insert leap second */
 239 #define TIME_DEL        2       /* delete leap second */
 240 #define TIME_OOP        3       /* leap second in progress */
 241 #define TIME_WAIT       4       /* leap second has occurred */
 242 #define TIME_ERROR      5       /* clock not synchronized */
 243 #define TIME_BAD        TIME_ERROR /* bw compat */
 244
 245 #ifdef __KERNEL__
 246 /*
 247  * kernel variables
 248  * Note: maximum error = NTP synch distance = dispersion + delay / 2;
 249  * estimated error = NTP dispersion.
 250  */
 251 extern long tick;                      /* timer interrupt period */
 252 extern int tickadj;                     /* amount of adjustment per tick */
 253
 254 /*
 255  * phase-lock loop variables
 256  */
 257 extern int time_state;          /* clock status */
 258 extern int time_status;         /* clock synchronization status bits */
 259 extern long time_offset;        /* time adjustment (us) */
 260 extern long time_constant;      /* pll time constant */
 261 extern long time_tolerance;     /* frequency tolerance (ppm) */
 262 extern long time_precision;     /* clock precision (us) */
 263 extern long time_maxerror;      /* maximum error */
 264 extern long time_esterror;      /* estimated error */
 265
 266 extern long time_phase;         /* phase offset (scaled us) */
 267 extern long time_freq;          /* frequency offset (scaled ppm) */
 268 extern long time_adj;           /* tick adjust (scaled 1 / HZ) */
 269 extern long time_reftime;       /* time at last adjustment (s) */
 270
 271 extern long time_adjust;        /* The amount of adjtime left */
 272
 273 /* interface variables pps->timer interrupt */
 274 extern long pps_offset;         /* pps time offset (us) */
 275 extern long pps_jitter;         /* time dispersion (jitter) (us) */
 276 extern long pps_freq;           /* frequency offset (scaled ppm) */
 277 extern long pps_stabil;         /* frequency dispersion (scaled ppm) */
 278 extern long pps_valid;          /* pps signal watchdog counter */
 279
 280 /* interface variables pps->adjtimex */
 281 extern int pps_shift;           /* interval duration (s) (shift) */
 282 extern long pps_jitcnt;         /* jitter limit exceeded */
 283 extern long pps_calcnt;         /* calibration intervals */
 284 extern long pps_errcnt;         /* calibration errors */
 285 extern long pps_stbcnt;         /* stability limit exceeded */
 286
 287 #endif /* KERNEL */
 288
 289 #endif /* LINUX_TIMEX_H */