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 #define NTP_API         4       /* NTP API version */
  62
  63 /*
  64  * SHIFT_KG and SHIFT_KF establish the damping of the PLL and are chosen
  65  * for a slightly underdamped convergence characteristic. SHIFT_KH
  66  * establishes the damping of the FLL and is chosen by wisdom and black
  67  * art.
  68  *
  69  * MAXTC establishes the maximum time constant of the PLL. With the
  70  * SHIFT_KG and SHIFT_KF values given and a time constant range from
  71  * zero to MAXTC, the PLL will converge in 15 minutes to 16 hours,
  72  * respectively.
  73  */
  74 #define SHIFT_PLL       4       /* PLL frequency factor (shift) */
  75 #define SHIFT_FLL       2       /* FLL frequency factor (shift) */
  76 #define MAXTC           10      /* maximum time constant (shift) */
  77
  78 /*
  79  * SHIFT_USEC defines the scaling (shift) of the time_freq and
  80  * time_tolerance variables, which represent the current frequency
  81  * offset and maximum frequency tolerance.
  82  */
  83 #define SHIFT_USEC 16           /* frequency offset scale (shift) */
  84 #define PPM_SCALE (NSEC_PER_USEC << (NTP_SCALE_SHIFT - SHIFT_USEC))
  85 #define PPM_SCALE_INV_SHIFT 20
  86 #define PPM_SCALE_INV ((1ll << (PPM_SCALE_INV_SHIFT + NTP_SCALE_SHIFT)) / \
  87                        PPM_SCALE + 1)
  88
  89 #define MAXPHASE 500000000l     /* max phase error (ns) */
  90 #define MAXFREQ 500000          /* max frequency error (ns/s) */
  91 #define MAXFREQ_SCALED ((s64)MAXFREQ << NTP_SCALE_SHIFT)
  92 #define MINSEC 256              /* min interval between updates (s) */
  93 #define MAXSEC 2048             /* max interval between updates (s) */
  94 #define NTP_PHASE_LIMIT ((MAXPHASE / NSEC_PER_USEC) << 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 tai;                /* TAI offset (ro) */
 125
 126         int  :32; int  :32; int  :32; int  :32;
 127         int  :32; int  :32; int  :32; int  :32;
 128         int  :32; int  :32; int  :32;
 129 };
 130
 131 /*
 132  * Mode codes (timex.mode)
 133  */
 134 #define ADJ_OFFSET              0x0001  /* time offset */
 135 #define ADJ_FREQUENCY           0x0002  /* frequency offset */
 136 #define ADJ_MAXERROR            0x0004  /* maximum time error */
 137 #define ADJ_ESTERROR            0x0008  /* estimated time error */
 138 #define ADJ_STATUS              0x0010  /* clock status */
 139 #define ADJ_TIMECONST           0x0020  /* pll time constant */
 140 #define ADJ_TAI                 0x0080  /* set TAI offset */
 141 #define ADJ_MICRO               0x1000  /* select microsecond resolution */
 142 #define ADJ_NANO                0x2000  /* select nanosecond resolution */
 143 #define ADJ_TICK                0x4000  /* tick value */
 144 #define ADJ_OFFSET_SINGLESHOT   0x8001  /* old-fashioned adjtime */
 145 #define ADJ_OFFSET_SS_READ      0xa001  /* read-only adjtime */
 146
 147 /* xntp 3.4 compatibility names */
 148 #define MOD_OFFSET      ADJ_OFFSET
 149 #define MOD_FREQUENCY   ADJ_FREQUENCY
 150 #define MOD_MAXERROR    ADJ_MAXERROR
 151 #define MOD_ESTERROR    ADJ_ESTERROR
 152 #define MOD_STATUS      ADJ_STATUS
 153 #define MOD_TIMECONST   ADJ_TIMECONST
 154
 155
 156 /*
 157  * Status codes (timex.status)
 158  */
 159 #define STA_PLL         0x0001  /* enable PLL updates (rw) */
 160 #define STA_PPSFREQ     0x0002  /* enable PPS freq discipline (rw) */
 161 #define STA_PPSTIME     0x0004  /* enable PPS time discipline (rw) */
 162 #define STA_FLL         0x0008  /* select frequency-lock mode (rw) */
 163
 164 #define STA_INS         0x0010  /* insert leap (rw) */
 165 #define STA_DEL         0x0020  /* delete leap (rw) */
 166 #define STA_UNSYNC      0x0040  /* clock unsynchronized (rw) */
 167 #define STA_FREQHOLD    0x0080  /* hold frequency (rw) */
 168
 169 #define STA_PPSSIGNAL   0x0100  /* PPS signal present (ro) */
 170 #define STA_PPSJITTER   0x0200  /* PPS signal jitter exceeded (ro) */
 171 #define STA_PPSWANDER   0x0400  /* PPS signal wander exceeded (ro) */
 172 #define STA_PPSERROR    0x0800  /* PPS signal calibration error (ro) */
 173
 174 #define STA_CLOCKERR    0x1000  /* clock hardware fault (ro) */
 175 #define STA_NANO        0x2000  /* resolution (0 = us, 1 = ns) (ro) */
 176 #define STA_MODE        0x4000  /* mode (0 = PLL, 1 = FLL) (ro) */
 177 #define STA_CLK         0x8000  /* clock source (0 = A, 1 = B) (ro) */
 178
 179 /* read-only bits */
 180 #define STA_RONLY (STA_PPSSIGNAL | STA_PPSJITTER | STA_PPSWANDER | \
 181         STA_PPSERROR | STA_CLOCKERR | STA_NANO | STA_MODE | STA_CLK)
 182
 183 /*
 184  * Clock states (time_state)
 185  */
 186 #define TIME_OK         0       /* clock synchronized, no leap second */
 187 #define TIME_INS        1       /* insert leap second */
 188 #define TIME_DEL        2       /* delete leap second */
 189 #define TIME_OOP        3       /* leap second in progress */
 190 #define TIME_WAIT       4       /* leap second has occurred */
 191 #define TIME_ERROR      5       /* clock not synchronized */
 192 #define TIME_BAD        TIME_ERROR /* bw compat */
 193
 194 #ifdef __KERNEL__
 195 #include <asm/timex.h>
 196
 197 /*
 198  * kernel variables
 199  * Note: maximum error = NTP synch distance = dispersion + delay / 2;
 200  * estimated error = NTP dispersion.
 201  */
 202 extern unsigned long tick_usec;         /* USER_HZ period (usec) */
 203 extern unsigned long tick_nsec;         /* ACTHZ          period (nsec) */
 204 extern int tickadj;                     /* amount of adjustment per tick */
 205
 206 /*
 207  * phase-lock loop variables
 208  */
 209 extern int time_status;         /* clock synchronization status bits */
 210 extern long time_maxerror;      /* maximum error */
 211 extern long time_esterror;      /* estimated error */
 212
 213 extern long time_adjust;        /* The amount of adjtime left */
 214
 215 extern void ntp_init(void);
 216 extern void ntp_clear(void);
 217
 218 /**
 219  * ntp_synced - Returns 1 if the NTP status is not UNSYNC
 220  *
 221  */
 222 static inline int ntp_synced(void)
 223 {
 224         return !(time_status & STA_UNSYNC);
 225 }
 226
 227 /* Required to safely shift negative values */
 228 #define shift_right(x, s) ({    \
 229         __typeof__(x) __x = (x);        \
 230         __typeof__(s) __s = (s);        \
 231         __x < 0 ? -(-__x >> __s) : __x >> __s;  \
 232 })
 233
 234 #define NTP_SCALE_SHIFT         32
 235
 236 #ifdef CONFIG_NO_HZ
 237 #define NTP_INTERVAL_FREQ  (2)
 238 #else
 239 #define NTP_INTERVAL_FREQ  (HZ)
 240 #endif
 241 #define NTP_INTERVAL_LENGTH (NSEC_PER_SEC/NTP_INTERVAL_FREQ)
 242
 243 /* Returns how long ticks are at present, in ns / 2^NTP_SCALE_SHIFT. */
 244 extern u64 tick_length;
 245
 246 extern void second_overflow(void);
 247 extern void update_ntp_one_tick(void);
 248 extern int do_adjtimex(struct timex *);
 249
 250 /* Don't use! Compatibility define for existing users. */
 251 #define tickadj (500/HZ ? : 1)
 252
 253 int read_current_timer(unsigned long *timer_val);
 254
 255 #endif /* KERNEL */
 256
 257 #endif /* LINUX_TIMEX_H */