FreeBSD/Linux Kernel Cross Reference
sys/sys/timeffc.h

     /*-
      * Copyright (c) 2011 The University of Melbourne
      * All rights reserved.
      *
      * This software was developed by Julien Ridoux at the University of Melbourne
      * under sponsorship from the FreeBSD Foundation.
      *
      * Redistribution and use in source and binary forms, with or without
      * modification, are permitted provided that the following conditions
     * are met:
     * 1. Redistributions of source code must retain the above copyright
     *    notice, this list of conditions and the following disclaimer.
     * 2. Redistributions in binary form must reproduce the above copyright
     *    notice, this list of conditions and the following disclaimer in the
     *    documentation and/or other materials provided with the distribution.
     *
     * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
     * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
     * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     * SUCH DAMAGE.
     *
     * $FreeBSD: releng/11.0/sys/sys/timeffc.h 228856 2011-12-24 01:32:01Z lstewart $
     */
    
    #ifndef _SYS_TIMEFF_H_
    #define _SYS_TIMEFF_H_
    
    #include <sys/_ffcounter.h>
    
    /*
     * Feed-forward clock estimate
     * Holds time mark as a ffcounter and conversion to bintime based on current
     * timecounter period and offset estimate passed by the synchronization daemon.
     * Provides time of last daemon update, clock status and bound on error.
     */
    struct ffclock_estimate {
            struct bintime  update_time;    /* Time of last estimates update. */
            ffcounter       update_ffcount; /* Counter value at last update. */
            ffcounter       leapsec_next;   /* Counter value of next leap second. */
            uint64_t        period;         /* Estimate of counter period. */
            uint32_t        errb_abs;       /* Bound on absolute clock error [ns]. */
            uint32_t        errb_rate;      /* Bound on counter rate error [ps/s]. */
            uint32_t        status;         /* Clock status. */
            int16_t         leapsec_total;  /* All leap seconds seen so far. */
            int8_t          leapsec;        /* Next leap second (in {-1,0,1}). */
    };
    
    #if __BSD_VISIBLE
    #ifdef _KERNEL
    
    /* Define the kern.sysclock sysctl tree. */
    SYSCTL_DECL(_kern_sysclock);
    
    /* Define the kern.sysclock.ffclock sysctl tree. */
    SYSCTL_DECL(_kern_sysclock_ffclock);
    
    /*
     * Index into the sysclocks array for obtaining the ASCII name of a particular
     * sysclock.
     */
    #define SYSCLOCK_FBCK   0
    #define SYSCLOCK_FFWD   1
    extern int sysclock_active;
    
    /*
     * Parameters of counter characterisation required by feed-forward algorithms.
     */
    #define FFCLOCK_SKM_SCALE       1024
    
    /*
     * Feed-forward clock status
     */
    #define FFCLOCK_STA_UNSYNC      1
    #define FFCLOCK_STA_WARMUP      2
    
    /*
     * Flags for use by sysclock_snap2bintime() and various ffclock_ functions to
     * control how the timecounter hardware is read and how the hardware snapshot is
     * converted into absolute time.
     * {FB|FF}CLOCK_FAST:   Do not read the hardware counter, instead using the
     *                      value at last tick. The time returned has a resolution
     *                      of the kernel tick timer (1/hz [s]).
     * FFCLOCK_LERP:        Linear interpolation of ffclock time to guarantee
     *                      monotonic time.
     * FFCLOCK_LEAPSEC:     Include leap seconds.
     * {FB|FF}CLOCK_UPTIME: Time stamp should be relative to system boot, not epoch.
     */
    #define FFCLOCK_FAST            0x00000001
    #define FFCLOCK_LERP            0x00000002
    #define FFCLOCK_LEAPSEC         0x00000004
    #define FFCLOCK_UPTIME          0x00000008
    #define FFCLOCK_MASK            0x0000ffff
   
   #define FBCLOCK_FAST            0x00010000 /* Currently unused. */
   #define FBCLOCK_UPTIME          0x00020000
   #define FBCLOCK_MASK            0xffff0000
   
   /*
    * Feedback clock specific info structure. The feedback clock's estimation of
    * clock error is an absolute figure determined by the NTP algorithm. The status
    * is determined by the userland daemon.
    */
   struct fbclock_info {
           struct bintime          error;
           struct bintime          tick_time;
           uint64_t                th_scale;
           int                     status;
   };
   
   /*
    * Feed-forward clock specific info structure. The feed-forward clock's
    * estimation of clock error is an upper bound, which although potentially
    * looser than the feedback clock equivalent, is much more reliable. The status
    * is determined by the userland daemon.
    */
   struct ffclock_info {
           struct bintime          error;
           struct bintime          tick_time;
           struct bintime          tick_time_lerp;
           uint64_t                period;
           uint64_t                period_lerp;
           int                     leapsec_adjustment;
           int                     status;
   };
   
   /*
    * Snapshot of system clocks and related information. Holds time read from each
    * clock based on a single read of the active hardware timecounter, as well as
    * respective clock information such as error estimates and the ffcounter value
    * at the time of the read.
    */
   struct sysclock_snap {
           struct fbclock_info     fb_info;
           struct ffclock_info     ff_info;
           ffcounter               ffcount;
           unsigned int            delta;
           int                     sysclock_active;
   };
   
   /* Take a snapshot of the system clocks and related information. */
   void sysclock_getsnapshot(struct sysclock_snap *clock_snap, int fast);
   
   /* Convert a timestamp from the selected system clock into bintime. */
   int sysclock_snap2bintime(struct sysclock_snap *cs, struct bintime *bt,
       int whichclock, uint32_t flags);
   
   /* Resets feed-forward clock from RTC */
   void ffclock_reset_clock(struct timespec *ts);
   
   /*
    * Return the current value of the feed-forward clock counter. Essential to
    * measure time interval in counter units. If a fast timecounter is used by the
    * system, may also allow fast but accurate timestamping.
    */
   void ffclock_read_counter(ffcounter *ffcount);
   
   /*
    * Retrieve feed-forward counter value and time of last kernel tick. This
    * accepts the FFCLOCK_LERP flag.
    */
   void ffclock_last_tick(ffcounter *ffcount, struct bintime *bt, uint32_t flags);
   
   /*
    * Low level routines to convert a counter timestamp into absolute time and a
    * counter timestamp interval into an interval in seconds. The absolute time
    * conversion accepts the FFCLOCK_LERP flag.
    */
   void ffclock_convert_abs(ffcounter ffcount, struct bintime *bt, uint32_t flags);
   void ffclock_convert_diff(ffcounter ffdelta, struct bintime *bt);
   
   /*
    * Feed-forward clock routines.
    *
    * These functions rely on the timecounters and ffclock_estimates stored in
    * fftimehands. Note that the error_bound parameter is not the error of the
    * clock but an upper bound on the error of the absolute time or time interval
    * returned.
    *
    * ffclock_abstime(): retrieves current time as counter value and convert this
    *     timestamp in seconds. The value (in seconds) of the converted timestamp
    *     depends on the flags passed: for a given counter value, different
    *     conversions are possible. Different clock models can be selected by
    *     combining flags (for example (FFCLOCK_LERP|FFCLOCK_UPTIME) produces
    *     linearly interpolated uptime).
    * ffclock_difftime(): computes a time interval in seconds based on an interval
    *     measured in ffcounter units. This should be the preferred way to measure
    *     small time intervals very accurately.
    */
   void ffclock_abstime(ffcounter *ffcount, struct bintime *bt,
       struct bintime *error_bound, uint32_t flags);
   void ffclock_difftime(ffcounter ffdelta, struct bintime *bt,
       struct bintime *error_bound);
   
   /*
    * Wrapper routines to return current absolute time using the feed-forward
    * clock. These functions are named after those defined in <sys/time.h>, which
    * contains a description of the original ones.
    */
   void ffclock_bintime(struct bintime *bt);
   void ffclock_nanotime(struct timespec *tsp);
   void ffclock_microtime(struct timeval *tvp);
   
   void ffclock_getbintime(struct bintime *bt);
   void ffclock_getnanotime(struct timespec *tsp);
   void ffclock_getmicrotime(struct timeval *tvp);
   
   void ffclock_binuptime(struct bintime *bt);
   void ffclock_nanouptime(struct timespec *tsp);
   void ffclock_microuptime(struct timeval *tvp);
   
   void ffclock_getbinuptime(struct bintime *bt);
   void ffclock_getnanouptime(struct timespec *tsp);
   void ffclock_getmicrouptime(struct timeval *tvp);
   
   /*
    * Wrapper routines to convert a time interval specified in ffcounter units into
    * seconds using the current feed-forward clock estimates.
    */
   void ffclock_bindifftime(ffcounter ffdelta, struct bintime *bt);
   void ffclock_nanodifftime(ffcounter ffdelta, struct timespec *tsp);
   void ffclock_microdifftime(ffcounter ffdelta, struct timeval *tvp);
   
   /*
    * When FFCLOCK is enabled in the kernel, [get]{bin,nano,micro}[up]time() become
    * wrappers around equivalent feedback or feed-forward functions. Provide access
    * outside of kern_tc.c to the feedback clock equivalent functions for
    * specialised use i.e. these are not for general consumption.
    */
   void fbclock_bintime(struct bintime *bt);
   void fbclock_nanotime(struct timespec *tsp);
   void fbclock_microtime(struct timeval *tvp);
   
   void fbclock_getbintime(struct bintime *bt);
   void fbclock_getnanotime(struct timespec *tsp);
   void fbclock_getmicrotime(struct timeval *tvp);
   
   void fbclock_binuptime(struct bintime *bt);
   void fbclock_nanouptime(struct timespec *tsp);
   void fbclock_microuptime(struct timeval *tvp);
   
   void fbclock_getbinuptime(struct bintime *bt);
   void fbclock_getnanouptime(struct timespec *tsp);
   void fbclock_getmicrouptime(struct timeval *tvp);
   
   /*
    * Public system clock wrapper API which allows consumers to select which clock
    * to obtain time from, independent of the current default system clock. These
    * wrappers should be used instead of directly calling the underlying fbclock_
    * or ffclock_ functions.
    */
   static inline void
   bintime_fromclock(struct bintime *bt, int whichclock)
   {
   
           if (whichclock == SYSCLOCK_FFWD)
                   ffclock_bintime(bt);
           else
                   fbclock_bintime(bt);
   }
   
   static inline void
   nanotime_fromclock(struct timespec *tsp, int whichclock)
   {
   
           if (whichclock == SYSCLOCK_FFWD)
                   ffclock_nanotime(tsp);
           else
                   fbclock_nanotime(tsp);
   }
   
   static inline void
   microtime_fromclock(struct timeval *tvp, int whichclock)
   {
   
           if (whichclock == SYSCLOCK_FFWD)
                   ffclock_microtime(tvp);
           else
                   fbclock_microtime(tvp);
   }
   
   static inline void
   getbintime_fromclock(struct bintime *bt, int whichclock)
   {
   
           if (whichclock == SYSCLOCK_FFWD)
                   ffclock_getbintime(bt);
           else
                   fbclock_getbintime(bt);
   }
   
   static inline void
   getnanotime_fromclock(struct timespec *tsp, int whichclock)
   {
   
           if (whichclock == SYSCLOCK_FFWD)
                   ffclock_getnanotime(tsp);
           else
                   fbclock_getnanotime(tsp);
   }
   
   static inline void
   getmicrotime_fromclock(struct timeval *tvp, int whichclock)
   {
   
           if (whichclock == SYSCLOCK_FFWD)
                   ffclock_getmicrotime(tvp);
           else
                   fbclock_getmicrotime(tvp);
   }
   
   static inline void
   binuptime_fromclock(struct bintime *bt, int whichclock)
   {
   
           if (whichclock == SYSCLOCK_FFWD)
                   ffclock_binuptime(bt);
           else
                   fbclock_binuptime(bt);
   }
   
   static inline void
   nanouptime_fromclock(struct timespec *tsp, int whichclock)
   {
   
           if (whichclock == SYSCLOCK_FFWD)
                   ffclock_nanouptime(tsp);
           else
                   fbclock_nanouptime(tsp);
   }
   
   static inline void
   microuptime_fromclock(struct timeval *tvp, int whichclock)
   {
   
           if (whichclock == SYSCLOCK_FFWD)
                   ffclock_microuptime(tvp);
           else
                   fbclock_microuptime(tvp);
   }
   
   static inline void
   getbinuptime_fromclock(struct bintime *bt, int whichclock)
   {
   
           if (whichclock == SYSCLOCK_FFWD)
                   ffclock_getbinuptime(bt);
           else
                   fbclock_getbinuptime(bt);
   }
   
   static inline void
   getnanouptime_fromclock(struct timespec *tsp, int whichclock)
   {
   
           if (whichclock == SYSCLOCK_FFWD)
                   ffclock_getnanouptime(tsp);
           else
                   fbclock_getnanouptime(tsp);
   }
   
   static inline void
   getmicrouptime_fromclock(struct timeval *tvp, int whichclock)
   {
   
           if (whichclock == SYSCLOCK_FFWD)
                   ffclock_getmicrouptime(tvp);
           else
                   fbclock_getmicrouptime(tvp);
   }
   
   #else /* !_KERNEL */
   
   /* Feed-Forward Clock system calls. */
   __BEGIN_DECLS
   int ffclock_getcounter(ffcounter *ffcount);
   int ffclock_getestimate(struct ffclock_estimate *cest);
   int ffclock_setestimate(struct ffclock_estimate *cest);
   __END_DECLS
   
   #endif /* _KERNEL */
   #endif /* __BSD_VISIBLE */
   #endif /* _SYS_TIMEFF_H_ */

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