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/time.h>
  57
  58 #define NTP_API         4       /* NTP API version */
  59
  60 /*
  61  * syscall interface - used (mainly by NTP daemon)
  62  * to discipline kernel clock oscillator
  63  */
  64 struct timex {
  65         unsigned int modes;     /* mode selector */
  66         long offset;            /* time offset (usec) */
  67         long freq;              /* frequency offset (scaled ppm) */
  68         long maxerror;          /* maximum error (usec) */
  69         long esterror;          /* estimated error (usec) */
  70         int status;             /* clock command/status */
  71         long constant;          /* pll time constant */
  72         long precision;         /* clock precision (usec) (read only) */
  73         long tolerance;         /* clock frequency tolerance (ppm)
  74                                  * (read only)
  75                                  */
  76         struct timeval time;    /* (read only) */
  77         long tick;              /* (modified) usecs between clock ticks */
  78
  79         long ppsfreq;           /* pps frequency (scaled ppm) (ro) */
  80         long jitter;            /* pps jitter (us) (ro) */
  81         int shift;              /* interval duration (s) (shift) (ro) */
  82         long stabil;            /* pps stability (scaled ppm) (ro) */
  83         long jitcnt;            /* jitter limit exceeded (ro) */
  84         long calcnt;            /* calibration intervals (ro) */
  85         long errcnt;            /* calibration errors (ro) */
  86         long stbcnt;            /* stability limit exceeded (ro) */
  87
  88         int tai;                /* TAI offset (ro) */
  89
  90         int  :32; int  :32; int  :32; int  :32;
  91         int  :32; int  :32; int  :32; int  :32;
  92         int  :32; int  :32; int  :32;
  93 };
  94
  95 /*
  96  * Mode codes (timex.mode)
  97  */
  98 #define ADJ_OFFSET              0x0001  /* time offset */
  99 #define ADJ_FREQUENCY           0x0002  /* frequency offset */
 100 #define ADJ_MAXERROR            0x0004  /* maximum time error */
 101 #define ADJ_ESTERROR            0x0008  /* estimated time error */
 102 #define ADJ_STATUS              0x0010  /* clock status */
 103 #define ADJ_TIMECONST           0x0020  /* pll time constant */
 104 #define ADJ_TAI                 0x0080  /* set TAI offset */
 105 #define ADJ_MICRO               0x1000  /* select microsecond resolution */
 106 #define ADJ_NANO                0x2000  /* select nanosecond resolution */
 107 #define ADJ_TICK                0x4000  /* tick value */
 108
 109 #ifdef __KERNEL__
 110 #define ADJ_ADJTIME             0x8000  /* switch between adjtime/adjtimex modes */
 111 #define ADJ_OFFSET_SINGLESHOT   0x0001  /* old-fashioned adjtime */
 112 #define ADJ_OFFSET_READONLY     0x2000  /* read-only adjtime */
 113 #else
 114 #define ADJ_OFFSET_SINGLESHOT   0x8001  /* old-fashioned adjtime */
 115 #define ADJ_OFFSET_SS_READ      0xa001  /* read-only adjtime */
 116 #endif
 117
 118 /* xntp 3.4 compatibility names */
 119 #define MOD_OFFSET      ADJ_OFFSET
 120 #define MOD_FREQUENCY   ADJ_FREQUENCY
 121 #define MOD_MAXERROR    ADJ_MAXERROR
 122 #define MOD_ESTERROR    ADJ_ESTERROR
 123 #define MOD_STATUS      ADJ_STATUS
 124 #define MOD_TIMECONST   ADJ_TIMECONST
 125
 126
 127 /*
 128  * Status codes (timex.status)
 129  */
 130 #define STA_PLL         0x0001  /* enable PLL updates (rw) */
 131 #define STA_PPSFREQ     0x0002  /* enable PPS freq discipline (rw) */
 132 #define STA_PPSTIME     0x0004  /* enable PPS time discipline (rw) */
 133 #define STA_FLL         0x0008  /* select frequency-lock mode (rw) */
 134
 135 #define STA_INS         0x0010  /* insert leap (rw) */
 136 #define STA_DEL         0x0020  /* delete leap (rw) */
 137 #define STA_UNSYNC      0x0040  /* clock unsynchronized (rw) */
 138 #define STA_FREQHOLD    0x0080  /* hold frequency (rw) */
 139
 140 #define STA_PPSSIGNAL   0x0100  /* PPS signal present (ro) */
 141 #define STA_PPSJITTER   0x0200  /* PPS signal jitter exceeded (ro) */
 142 #define STA_PPSWANDER   0x0400  /* PPS signal wander exceeded (ro) */
 143 #define STA_PPSERROR    0x0800  /* PPS signal calibration error (ro) */
 144
 145 #define STA_CLOCKERR    0x1000  /* clock hardware fault (ro) */
 146 #define STA_NANO        0x2000  /* resolution (0 = us, 1 = ns) (ro) */
 147 #define STA_MODE        0x4000  /* mode (0 = PLL, 1 = FLL) (ro) */
 148 #define STA_CLK         0x8000  /* clock source (0 = A, 1 = B) (ro) */
 149
 150 /* read-only bits */
 151 #define STA_RONLY (STA_PPSSIGNAL | STA_PPSJITTER | STA_PPSWANDER | \
 152         STA_PPSERROR | STA_CLOCKERR | STA_NANO | STA_MODE | STA_CLK)
 153
 154 /*
 155  * Clock states (time_state)
 156  */
 157 #define TIME_OK         0       /* clock synchronized, no leap second */
 158 #define TIME_INS        1       /* insert leap second */
 159 #define TIME_DEL        2       /* delete leap second */
 160 #define TIME_OOP        3       /* leap second in progress */
 161 #define TIME_WAIT       4       /* leap second has occurred */
 162 #define TIME_ERROR      5       /* clock not synchronized */
 163 #define TIME_BAD        TIME_ERROR /* bw compat */
 164
 165 #ifdef __KERNEL__
 166 #include <linux/compiler.h>
 167 #include <linux/types.h>
 168 #include <linux/param.h>
 169
 170 #include <asm/timex.h>
 171
 172 /*
 173  * SHIFT_KG and SHIFT_KF establish the damping of the PLL and are chosen
 174  * for a slightly underdamped convergence characteristic. SHIFT_KH
 175  * establishes the damping of the FLL and is chosen by wisdom and black
 176  * art.
 177  *
 178  * MAXTC establishes the maximum time constant of the PLL. With the
 179  * SHIFT_KG and SHIFT_KF values given and a time constant range from
 180  * zero to MAXTC, the PLL will converge in 15 minutes to 16 hours,
 181  * respectively.
 182  */
 183 #define SHIFT_PLL       4       /* PLL frequency factor (shift) */
 184 #define SHIFT_FLL       2       /* FLL frequency factor (shift) */
 185 #define MAXTC           10      /* maximum time constant (shift) */
 186
 187 /*
 188  * SHIFT_USEC defines the scaling (shift) of the time_freq and
 189  * time_tolerance variables, which represent the current frequency
 190  * offset and maximum frequency tolerance.
 191  */
 192 #define SHIFT_USEC 16           /* frequency offset scale (shift) */
 193 #define PPM_SCALE ((s64)NSEC_PER_USEC << (NTP_SCALE_SHIFT - SHIFT_USEC))
 194 #define PPM_SCALE_INV_SHIFT 19
 195 #define PPM_SCALE_INV ((1ll << (PPM_SCALE_INV_SHIFT + NTP_SCALE_SHIFT)) / \
 196                        PPM_SCALE + 1)
 197
 198 #define MAXPHASE 500000000l     /* max phase error (ns) */
 199 #define MAXFREQ 500000          /* max frequency error (ns/s) */
 200 #define MAXFREQ_SCALED ((s64)MAXFREQ << NTP_SCALE_SHIFT)
 201 #define MINSEC 256              /* min interval between updates (s) */
 202 #define MAXSEC 2048             /* max interval between updates (s) */
 203 #define NTP_PHASE_LIMIT ((MAXPHASE / NSEC_PER_USEC) << 5) /* beyond max. dispersion */
 204
 205 /*
 206  * kernel variables
 207  * Note: maximum error = NTP synch distance = dispersion + delay / 2;
 208  * estimated error = NTP dispersion.
 209  */
 210 extern unsigned long tick_usec;         /* USER_HZ period (usec) */
 211 extern unsigned long tick_nsec;         /* ACTHZ          period (nsec) */
 212 extern int tickadj;                     /* amount of adjustment per tick */
 213
 214 /*
 215  * phase-lock loop variables
 216  */
 217 extern int time_status;         /* clock synchronization status bits */
 218 extern long time_maxerror;      /* maximum error */
 219 extern long time_esterror;      /* estimated error */
 220
 221 extern long time_adjust;        /* The amount of adjtime left */
 222
 223 extern void ntp_init(void);
 224 extern void ntp_clear(void);
 225
 226 /**
 227  * ntp_synced - Returns 1 if the NTP status is not UNSYNC
 228  *
 229  */
 230 static inline int ntp_synced(void)
 231 {
 232         return !(time_status & STA_UNSYNC);
 233 }
 234
 235 /* Required to safely shift negative values */
 236 #define shift_right(x, s) ({    \
 237         __typeof__(x) __x = (x);        \
 238         __typeof__(s) __s = (s);        \
 239         __x < 0 ? -(-__x >> __s) : __x >> __s;  \
 240 })
 241
 242 #define NTP_SCALE_SHIFT         32
 243
 244 #ifdef CONFIG_NO_HZ
 245 #define NTP_INTERVAL_FREQ  (2)
 246 #else
 247 #define NTP_INTERVAL_FREQ  (HZ)
 248 #endif
 249 #define NTP_INTERVAL_LENGTH (NSEC_PER_SEC/NTP_INTERVAL_FREQ)
 250
 251 /* Returns how long ticks are at present, in ns / 2^NTP_SCALE_SHIFT. */
 252 extern u64 tick_length;
 253
 254 extern void second_overflow(void);
 255 extern void update_ntp_one_tick(void);
 256 extern int do_adjtimex(struct timex *);
 257
 258 /* Don't use! Compatibility define for existing users. */
 259 #define tickadj (500/HZ ? : 1)
 260
 261 int read_current_timer(unsigned long *timer_val);
 262
 263 #endif /* KERNEL */
 264
 265 #endif /* LINUX_TIMEX_H */