Linux v2.6.13-rc3

[pohmelfs.git] / include / linux / timex.h

/*****************************************************************************
 *                                                                           *
 * Copyright (c) David L. Mills 1993                                         *
 *                                                                           *
 * Permission to use, copy, modify, and distribute this software and its     *
 * documentation for any purpose and without fee is hereby granted, provided *
 * that the above copyright notice appears in all copies and that both the   *
 * copyright notice and this permission notice appear in supporting          *
 * documentation, and that the name University of Delaware not be used in    *
 * advertising or publicity pertaining to distribution of the software       *
 * without specific, written prior permission.  The University of Delaware   *
 * makes no representations about the suitability this software for any      *
 * purpose.  It is provided "as is" without express or implied warranty.     *
 *                                                                           *
 *****************************************************************************/

/*
 * Modification history timex.h
 *
 * 29 Dec 97    Russell King
 *      Moved CLOCK_TICK_RATE, CLOCK_TICK_FACTOR and FINETUNE to asm/timex.h
 *      for ARM machines
 *
 *  9 Jan 97    Adrian Sun
 *      Shifted LATCH define to allow access to alpha machines.
 *
 * 26 Sep 94    David L. Mills
 *      Added defines for hybrid phase/frequency-lock loop.
 *
 * 19 Mar 94    David L. Mills
 *      Moved defines from kernel routines to header file and added new
 *      defines for PPS phase-lock loop.
 *
 * 20 Feb 94    David L. Mills
 *      Revised status codes and structures for external clock and PPS
 *      signal discipline.
 *
 * 28 Nov 93    David L. Mills
 *      Adjusted parameters to improve stability and increase poll
 *      interval.
 *
 * 17 Sep 93    David L. Mills
 *      Created file $NTP/include/sys/timex.h
 * 07 Oct 93    Torsten Duwe
 *      Derived linux/timex.h
 * 1995-08-13    Torsten Duwe
 *      kernel PLL updated to 1994-12-13 specs (rfc-1589)
 * 1997-08-30    Ulrich Windl
 *      Added new constant NTP_PHASE_LIMIT
 * 2004-08-12    Christoph Lameter
 *      Reworked time interpolation logic
 */
#ifndef _LINUX_TIMEX_H
#define _LINUX_TIMEX_H

#include <linux/config.h>
#include <linux/compiler.h>
#include <linux/time.h>

#include <asm/param.h>
#include <asm/timex.h>

/*
 * SHIFT_KG and SHIFT_KF establish the damping of the PLL and are chosen
 * for a slightly underdamped convergence characteristic. SHIFT_KH
 * establishes the damping of the FLL and is chosen by wisdom and black
 * art.
 *
 * MAXTC establishes the maximum time constant of the PLL. With the
 * SHIFT_KG and SHIFT_KF values given and a time constant range from
 * zero to MAXTC, the PLL will converge in 15 minutes to 16 hours,
 * respectively.
 */
#define SHIFT_KG 6              /* phase factor (shift) */
#define SHIFT_KF 16             /* PLL frequency factor (shift) */
#define SHIFT_KH 2              /* FLL frequency factor (shift) */
#define MAXTC 6                 /* maximum time constant (shift) */

/*
 * The SHIFT_SCALE define establishes the decimal point of the time_phase
 * variable which serves as an extension to the low-order bits of the
 * system clock variable. The SHIFT_UPDATE define establishes the decimal
 * point of the time_offset variable which represents the current offset
 * with respect to standard time. The FINENSEC define represents 1 nsec in
 * scaled units.
 *
 * SHIFT_USEC defines the scaling (shift) of the time_freq and
 * time_tolerance variables, which represent the current frequency
 * offset and maximum frequency tolerance.
 *
 * FINENSEC is 1 ns in SHIFT_UPDATE units of the time_phase variable.
 */
#define SHIFT_SCALE 22          /* phase scale (shift) */
#define SHIFT_UPDATE (SHIFT_KG + MAXTC) /* time offset scale (shift) */
#define SHIFT_USEC 16           /* frequency offset scale (shift) */
#define FINENSEC (1L << (SHIFT_SCALE - 10)) /* ~1 ns in phase units */

#define MAXPHASE 512000L        /* max phase error (us) */
#define MAXFREQ (512L << SHIFT_USEC)  /* max frequency error (ppm) */
#define MAXTIME (200L << PPS_AVG) /* max PPS error (jitter) (200 us) */
#define MINSEC 16L              /* min interval between updates (s) */
#define MAXSEC 1200L            /* max interval between updates (s) */
#define NTP_PHASE_LIMIT (MAXPHASE << 5) /* beyond max. dispersion */

/*
 * The following defines are used only if a pulse-per-second (PPS)
 * signal is available and connected via a modem control lead, such as
 * produced by the optional ppsclock feature incorporated in the Sun
 * asynch driver. They establish the design parameters of the frequency-
 * lock loop used to discipline the CPU clock oscillator to the PPS
 * signal.
 *
 * PPS_AVG is the averaging factor for the frequency loop, as well as
 * the time and frequency dispersion.
 *
 * PPS_SHIFT and PPS_SHIFTMAX specify the minimum and maximum
 * calibration intervals, respectively, in seconds as a power of two.
 *
 * PPS_VALID is the maximum interval before the PPS signal is considered
 * invalid and protocol updates used directly instead.
 *
 * MAXGLITCH is the maximum interval before a time offset of more than
 * MAXTIME is believed.
 */
#define PPS_AVG 2               /* pps averaging constant (shift) */
#define PPS_SHIFT 2             /* min interval duration (s) (shift) */
#define PPS_SHIFTMAX 8          /* max interval duration (s) (shift) */
#define PPS_VALID 120           /* pps signal watchdog max (s) */
#define MAXGLITCH 30            /* pps signal glitch max (s) */

/*
 * syscall interface - used (mainly by NTP daemon)
 * to discipline kernel clock oscillator
 */
struct timex {
        unsigned int modes;     /* mode selector */
        long offset;            /* time offset (usec) */
        long freq;              /* frequency offset (scaled ppm) */
        long maxerror;          /* maximum error (usec) */
        long esterror;          /* estimated error (usec) */
        int status;             /* clock command/status */
        long constant;          /* pll time constant */
        long precision;         /* clock precision (usec) (read only) */
        long tolerance;         /* clock frequency tolerance (ppm)
                                 * (read only)
                                 */
        struct timeval time;    /* (read only) */
        long tick;              /* (modified) usecs between clock ticks */

        long ppsfreq;           /* pps frequency (scaled ppm) (ro) */
        long jitter;            /* pps jitter (us) (ro) */
        int shift;              /* interval duration (s) (shift) (ro) */
        long stabil;            /* pps stability (scaled ppm) (ro) */
        long jitcnt;            /* jitter limit exceeded (ro) */
        long calcnt;            /* calibration intervals (ro) */
        long errcnt;            /* calibration errors (ro) */
        long stbcnt;            /* stability limit exceeded (ro) */

        int  :32; int  :32; int  :32; int  :32;
        int  :32; int  :32; int  :32; int  :32;
        int  :32; int  :32; int  :32; int  :32;
};

/*
 * Mode codes (timex.mode)
 */
#define ADJ_OFFSET              0x0001  /* time offset */
#define ADJ_FREQUENCY           0x0002  /* frequency offset */
#define ADJ_MAXERROR            0x0004  /* maximum time error */
#define ADJ_ESTERROR            0x0008  /* estimated time error */
#define ADJ_STATUS              0x0010  /* clock status */
#define ADJ_TIMECONST           0x0020  /* pll time constant */
#define ADJ_TICK                0x4000  /* tick value */
#define ADJ_OFFSET_SINGLESHOT   0x8001  /* old-fashioned adjtime */

/* xntp 3.4 compatibility names */
#define MOD_OFFSET      ADJ_OFFSET
#define MOD_FREQUENCY   ADJ_FREQUENCY
#define MOD_MAXERROR    ADJ_MAXERROR
#define MOD_ESTERROR    ADJ_ESTERROR
#define MOD_STATUS      ADJ_STATUS
#define MOD_TIMECONST   ADJ_TIMECONST
#define MOD_CLKB        ADJ_TICK
#define MOD_CLKA        ADJ_OFFSET_SINGLESHOT /* 0x8000 in original */


/*
 * Status codes (timex.status)
 */
#define STA_PLL         0x0001  /* enable PLL updates (rw) */
#define STA_PPSFREQ     0x0002  /* enable PPS freq discipline (rw) */
#define STA_PPSTIME     0x0004  /* enable PPS time discipline (rw) */
#define STA_FLL         0x0008  /* select frequency-lock mode (rw) */

#define STA_INS         0x0010  /* insert leap (rw) */
#define STA_DEL         0x0020  /* delete leap (rw) */
#define STA_UNSYNC      0x0040  /* clock unsynchronized (rw) */
#define STA_FREQHOLD    0x0080  /* hold frequency (rw) */

#define STA_PPSSIGNAL   0x0100  /* PPS signal present (ro) */
#define STA_PPSJITTER   0x0200  /* PPS signal jitter exceeded (ro) */
#define STA_PPSWANDER   0x0400  /* PPS signal wander exceeded (ro) */
#define STA_PPSERROR    0x0800  /* PPS signal calibration error (ro) */

#define STA_CLOCKERR    0x1000  /* clock hardware fault (ro) */

#define STA_RONLY (STA_PPSSIGNAL | STA_PPSJITTER | STA_PPSWANDER | \
    STA_PPSERROR | STA_CLOCKERR) /* read-only bits */

/*
 * Clock states (time_state)
 */
#define TIME_OK         0       /* clock synchronized, no leap second */
#define TIME_INS        1       /* insert leap second */
#define TIME_DEL        2       /* delete leap second */
#define TIME_OOP        3       /* leap second in progress */
#define TIME_WAIT       4       /* leap second has occurred */
#define TIME_ERROR      5       /* clock not synchronized */
#define TIME_BAD        TIME_ERROR /* bw compat */

#ifdef __KERNEL__
/*
 * kernel variables
 * Note: maximum error = NTP synch distance = dispersion + delay / 2;
 * estimated error = NTP dispersion.
 */
extern unsigned long tick_usec;         /* USER_HZ period (usec) */
extern unsigned long tick_nsec;         /* ACTHZ          period (nsec) */
extern int tickadj;                     /* amount of adjustment per tick */

/*
 * phase-lock loop variables
 */
extern int time_state;          /* clock status */
extern int time_status;         /* clock synchronization status bits */
extern long time_offset;        /* time adjustment (us) */
extern long time_constant;      /* pll time constant */
extern long time_tolerance;     /* frequency tolerance (ppm) */
extern long time_precision;     /* clock precision (us) */
extern long time_maxerror;      /* maximum error */
extern long time_esterror;      /* estimated error */

extern long time_freq;          /* frequency offset (scaled ppm) */
extern long time_reftime;       /* time at last adjustment (s) */

extern long time_adjust;        /* The amount of adjtime left */
extern long time_next_adjust;   /* Value for time_adjust at next tick */

/* interface variables pps->timer interrupt */
extern long pps_offset;         /* pps time offset (us) */
extern long pps_jitter;         /* time dispersion (jitter) (us) */
extern long pps_freq;           /* frequency offset (scaled ppm) */
extern long pps_stabil;         /* frequency dispersion (scaled ppm) */
extern long pps_valid;          /* pps signal watchdog counter */

/* interface variables pps->adjtimex */
extern int pps_shift;           /* interval duration (s) (shift) */
extern long pps_jitcnt;         /* jitter limit exceeded */
extern long pps_calcnt;         /* calibration intervals */
extern long pps_errcnt;         /* calibration errors */
extern long pps_stbcnt;         /* stability limit exceeded */

#ifdef CONFIG_TIME_INTERPOLATION

#define TIME_SOURCE_CPU 0
#define TIME_SOURCE_MMIO64 1
#define TIME_SOURCE_MMIO32 2
#define TIME_SOURCE_FUNCTION 3

/* For proper operations time_interpolator clocks must run slightly slower
 * than the standard clock since the interpolator may only correct by having
 * time jump forward during a tick. A slower clock is usually a side effect
 * of the integer divide of the nanoseconds in a second by the frequency.
 * The accuracy of the division can be increased by specifying a shift.
 * However, this may cause the clock not to be slow enough.
 * The interpolator will self-tune the clock by slowing down if no
 * resets occur or speeding up if the time jumps per analysis cycle
 * become too high.
 *
 * Setting jitter compensates for a fluctuating timesource by comparing
 * to the last value read from the timesource to insure that an earlier value
 * is not returned by a later call. The price to pay
 * for the compensation is that the timer routines are not as scalable anymore.
 */

struct time_interpolator {
        u16 source;                     /* time source flags */
        u8 shift;                       /* increases accuracy of multiply by shifting. */
                                /* Note that bits may be lost if shift is set too high */
        u8 jitter;                      /* if set compensate for fluctuations */
        u32 nsec_per_cyc;               /* set by register_time_interpolator() */
        void *addr;                     /* address of counter or function */
        u64 mask;                       /* mask the valid bits of the counter */
        unsigned long offset;           /* nsec offset at last update of interpolator */
        u64 last_counter;               /* counter value in units of the counter at last update */
        u64 last_cycle;                 /* Last timer value if TIME_SOURCE_JITTER is set */
        u64 frequency;                  /* frequency in counts/second */
        long drift;                     /* drift in parts-per-million (or -1) */
        unsigned long skips;            /* skips forward */
        unsigned long ns_skipped;       /* nanoseconds skipped */
        struct time_interpolator *next;
};

extern void register_time_interpolator(struct time_interpolator *);
extern void unregister_time_interpolator(struct time_interpolator *);
extern void time_interpolator_reset(void);
extern unsigned long time_interpolator_get_offset(void);

#else /* !CONFIG_TIME_INTERPOLATION */

static inline void
time_interpolator_reset(void)
{
}

#endif /* !CONFIG_TIME_INTERPOLATION */

#endif /* KERNEL */

#endif /* LINUX_TIMEX_H */