2 * Copyright (c) 2011 The University of Melbourne
5 * This software was developed by Julien Ridoux at the University of Melbourne
6 * under sponsorship from the FreeBSD Foundation.
8 * Redistribution and use in source and binary forms, with or without
9 * modification, are permitted provided that the following conditions
11 * 1. Redistributions of source code must retain the above copyright
12 * notice, this list of conditions and the following disclaimer.
13 * 2. Redistributions in binary form must reproduce the above copyright
14 * notice, this list of conditions and the following disclaimer in the
15 * documentation and/or other materials provided with the distribution.
17 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
18 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
19 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
20 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
21 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
22 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
23 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
24 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
25 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
26 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
32 #ifndef _SYS_TIMEFF_H_
33 #define _SYS_TIMEFF_H_
35 #include <sys/_ffcounter.h>
38 * Feed-forward clock estimate
39 * Holds time mark as a ffcounter and conversion to bintime based on current
40 * timecounter period and offset estimate passed by the synchronization daemon.
41 * Provides time of last daemon update, clock status and bound on error.
43 struct ffclock_estimate {
44 struct bintime update_time; /* Time of last estimates update. */
45 ffcounter update_ffcount; /* Counter value at last update. */
46 ffcounter leapsec_next; /* Counter value of next leap second. */
47 uint64_t period; /* Estimate of counter period. */
48 uint32_t errb_abs; /* Bound on absolute clock error [ns]. */
49 uint32_t errb_rate; /* Bound on counter rate error [ps/s]. */
50 uint32_t status; /* Clock status. */
51 int16_t leapsec_total; /* All leap seconds seen so far. */
52 int8_t leapsec; /* Next leap second (in {-1,0,1}). */
59 * Index into the sysclocks array for obtaining the ASCII name of a particular
62 #define SYSCLOCK_FBCK 0
63 #define SYSCLOCK_FFWD 1
66 * Parameters of counter characterisation required by feed-forward algorithms.
68 #define FFCLOCK_SKM_SCALE 1024
71 * Feed-forward clock status
73 #define FFCLOCK_STA_UNSYNC 1
74 #define FFCLOCK_STA_WARMUP 2
77 * Clock flags to select how the feed-forward counter is converted to absolute
78 * time by ffclock_convert_abs().
79 * FAST: do not read the hardware counter, return feed-forward clock time
80 * at last tick. The time returned has the resolution of the kernel
82 * LERP: linear interpolation of ffclock time to guarantee monotonic time.
83 * LEAPSEC: include leap seconds.
84 * UPTIME: removes time of boot.
86 #define FFCLOCK_FAST 1
87 #define FFCLOCK_LERP 2
88 #define FFCLOCK_LEAPSEC 4
89 #define FFCLOCK_UPTIME 8
91 /* Resets feed-forward clock from RTC */
92 void ffclock_reset_clock(struct timespec *ts);
95 * Return the current value of the feed-forward clock counter. Essential to
96 * measure time interval in counter units. If a fast timecounter is used by the
97 * system, may also allow fast but accurate timestamping.
99 void ffclock_read_counter(ffcounter *ffcount);
102 * Retrieve feed-forward counter value and time of last kernel tick. This
103 * accepts the FFCLOCK_LERP flag.
105 void ffclock_last_tick(ffcounter *ffcount, struct bintime *bt, uint32_t flags);
108 * Low level routines to convert a counter timestamp into absolute time and a
109 * counter timestamp interval into an interval in seconds. The absolute time
110 * conversion accepts the FFCLOCK_LERP flag.
112 void ffclock_convert_abs(ffcounter ffcount, struct bintime *bt, uint32_t flags);
113 void ffclock_convert_diff(ffcounter ffdelta, struct bintime *bt);
116 * Feed-forward clock routines.
118 * These functions rely on the timecounters and ffclock_estimates stored in
119 * fftimehands. Note that the error_bound parameter is not the error of the
120 * clock but an upper bound on the error of the absolute time or time interval
123 * ffclock_abstime(): retrieves current time as counter value and convert this
124 * timestamp in seconds. The value (in seconds) of the converted timestamp
125 * depends on the flags passed: for a given counter value, different
126 * conversions are possible. Different clock models can be selected by
127 * combining flags (for example (FFCLOCK_LERP|FFCLOCK_UPTIME) produces
128 * linearly interpolated uptime).
129 * ffclock_difftime(): computes a time interval in seconds based on an interval
130 * measured in ffcounter units. This should be the preferred way to measure
131 * small time intervals very accurately.
133 void ffclock_abstime(ffcounter *ffcount, struct bintime *bt,
134 struct bintime *error_bound, uint32_t flags);
135 void ffclock_difftime(ffcounter ffdelta, struct bintime *bt,
136 struct bintime *error_bound);
139 * Wrapper routines to return current absolute time using the feed-forward
140 * clock. These functions are named after those defined in <sys/time.h>, which
141 * contains a description of the original ones.
143 void ffclock_bintime(struct bintime *bt);
144 void ffclock_nanotime(struct timespec *tsp);
145 void ffclock_microtime(struct timeval *tvp);
147 void ffclock_getbintime(struct bintime *bt);
148 void ffclock_getnanotime(struct timespec *tsp);
149 void ffclock_getmicrotime(struct timeval *tvp);
151 void ffclock_binuptime(struct bintime *bt);
152 void ffclock_nanouptime(struct timespec *tsp);
153 void ffclock_microuptime(struct timeval *tvp);
155 void ffclock_getbinuptime(struct bintime *bt);
156 void ffclock_getnanouptime(struct timespec *tsp);
157 void ffclock_getmicrouptime(struct timeval *tvp);
160 * Wrapper routines to convert a time interval specified in ffcounter units into
161 * seconds using the current feed-forward clock estimates.
163 void ffclock_bindifftime(ffcounter ffdelta, struct bintime *bt);
164 void ffclock_nanodifftime(ffcounter ffdelta, struct timespec *tsp);
165 void ffclock_microdifftime(ffcounter ffdelta, struct timeval *tvp);
169 /* Feed-Forward Clock system calls. */
171 int ffclock_getcounter(ffcounter *ffcount);
172 int ffclock_getestimate(struct ffclock_estimate *cest);
173 int ffclock_setestimate(struct ffclock_estimate *cest);
177 #endif /* __BSD_VISIBLE */
178 #endif /* _SYS_TIMEFF_H_ */