RTEMS: cpukit/include/sys/timeffc.h Source File

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timeffc.h
1/*-
2 * Copyright (c) 2011 The University of Melbourne
3 * All rights reserved.
4 *
5 * This software was developed by Julien Ridoux at the University of Melbourne
6 * under sponsorship from the FreeBSD Foundation.
7 *
8 * Redistribution and use in source and binary forms, with or without
9 * modification, are permitted provided that the following conditions
10 * are met:
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.
16 *
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
27 * SUCH DAMAGE.
28 *
29 * $FreeBSD: head/sys/sys/timeffc.h 228856 2011-12-24 01:32:01Z lstewart $
30 */
31
32#ifndef _SYS_TIMEFF_H_
33#define _SYS_TIMEFF_H_
34
35#include <sys/_ffcounter.h>
36
37/*
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.
42 */
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}). */
53};
54
55#if __BSD_VISIBLE
56#ifdef _KERNEL
57
58#ifndef __rtems__
59/* Define the kern.sysclock sysctl tree. */
60SYSCTL_DECL(_kern_sysclock);
61
62/* Define the kern.sysclock.ffclock sysctl tree. */
63SYSCTL_DECL(_kern_sysclock_ffclock);
64#endif /* __rtems__ */
65
66/*
67 * Index into the sysclocks array for obtaining the ASCII name of a particular
68 * sysclock.
69 */
70#define SYSCLOCK_FBCK 0
71#define SYSCLOCK_FFWD 1
72extern int sysclock_active;
73
74/*
75 * Parameters of counter characterisation required by feed-forward algorithms.
76 */
77#define FFCLOCK_SKM_SCALE 1024
78
79/*
80 * Feed-forward clock status
81 */
82#define FFCLOCK_STA_UNSYNC 1
83#define FFCLOCK_STA_WARMUP 2
84
85/*
86 * Flags for use by sysclock_snap2bintime() and various ffclock_ functions to
87 * control how the timecounter hardware is read and how the hardware snapshot is
88 * converted into absolute time.
89 * {FB|FF}CLOCK_FAST: Do not read the hardware counter, instead using the
90 * value at last tick. The time returned has a resolution
91 * of the kernel tick timer (1/hz [s]).
92 * FFCLOCK_LERP: Linear interpolation of ffclock time to guarantee
93 * monotonic time.
94 * FFCLOCK_LEAPSEC: Include leap seconds.
95 * {FB|FF}CLOCK_UPTIME: Time stamp should be relative to system boot, not epoch.
96 */
97#define FFCLOCK_FAST 0x00000001
98#define FFCLOCK_LERP 0x00000002
99#define FFCLOCK_LEAPSEC 0x00000004
100#define FFCLOCK_UPTIME 0x00000008
101#define FFCLOCK_MASK 0x0000ffff
102
103#define FBCLOCK_FAST 0x00010000 /* Currently unused. */
104#define FBCLOCK_UPTIME 0x00020000
105#define FBCLOCK_MASK 0xffff0000
106
107/*
108 * Feedback clock specific info structure. The feedback clock's estimation of
109 * clock error is an absolute figure determined by the NTP algorithm. The status
110 * is determined by the userland daemon.
111 */
112struct fbclock_info {
113 struct bintime error;
114 struct bintime tick_time;
115 uint64_t th_scale;
116 int status;
117};
118
119/*
120 * Feed-forward clock specific info structure. The feed-forward clock's
121 * estimation of clock error is an upper bound, which although potentially
122 * looser than the feedback clock equivalent, is much more reliable. The status
123 * is determined by the userland daemon.
124 */
125struct ffclock_info {
126 struct bintime error;
127 struct bintime tick_time;
128 struct bintime tick_time_lerp;
129 uint64_t period;
130 uint64_t period_lerp;
131 int leapsec_adjustment;
132 int status;
133};
134
135/*
136 * Snapshot of system clocks and related information. Holds time read from each
137 * clock based on a single read of the active hardware timecounter, as well as
138 * respective clock information such as error estimates and the ffcounter value
139 * at the time of the read.
140 */
141struct sysclock_snap {
142 struct fbclock_info fb_info;
143 struct ffclock_info ff_info;
144 ffcounter ffcount;
145 unsigned int delta;
146 int sysclock_active;
147};
148
149/* Take a snapshot of the system clocks and related information. */
150void sysclock_getsnapshot(struct sysclock_snap *clock_snap, int fast);
151
152/* Convert a timestamp from the selected system clock into bintime. */
153int sysclock_snap2bintime(struct sysclock_snap *cs, struct bintime *bt,
154 int whichclock, uint32_t flags);
155
156/* Resets feed-forward clock from RTC */
157void ffclock_reset_clock(struct timespec *ts);
158
159/*
160 * Return the current value of the feed-forward clock counter. Essential to
161 * measure time interval in counter units. If a fast timecounter is used by the
162 * system, may also allow fast but accurate timestamping.
163 */
164void ffclock_read_counter(ffcounter *ffcount);
165
166/*
167 * Retrieve feed-forward counter value and time of last kernel tick. This
168 * accepts the FFCLOCK_LERP flag.
169 */
170void ffclock_last_tick(ffcounter *ffcount, struct bintime *bt, uint32_t flags);
171
172/*
173 * Low level routines to convert a counter timestamp into absolute time and a
174 * counter timestamp interval into an interval in seconds. The absolute time
175 * conversion accepts the FFCLOCK_LERP flag.
176 */
177void ffclock_convert_abs(ffcounter ffcount, struct bintime *bt, uint32_t flags);
178void ffclock_convert_diff(ffcounter ffdelta, struct bintime *bt);
179
180/*
181 * Feed-forward clock routines.
182 *
183 * These functions rely on the timecounters and ffclock_estimates stored in
184 * fftimehands. Note that the error_bound parameter is not the error of the
185 * clock but an upper bound on the error of the absolute time or time interval
186 * returned.
187 *
188 * ffclock_abstime(): retrieves current time as counter value and convert this
189 * timestamp in seconds. The value (in seconds) of the converted timestamp
190 * depends on the flags passed: for a given counter value, different
191 * conversions are possible. Different clock models can be selected by
192 * combining flags (for example (FFCLOCK_LERP|FFCLOCK_UPTIME) produces
193 * linearly interpolated uptime).
194 * ffclock_difftime(): computes a time interval in seconds based on an interval
195 * measured in ffcounter units. This should be the preferred way to measure
196 * small time intervals very accurately.
197 */
198void ffclock_abstime(ffcounter *ffcount, struct bintime *bt,
199 struct bintime *error_bound, uint32_t flags);
200void ffclock_difftime(ffcounter ffdelta, struct bintime *bt,
201 struct bintime *error_bound);
202
203/*
204 * Wrapper routines to return current absolute time using the feed-forward
205 * clock. These functions are named after those defined in <sys/time.h>, which
206 * contains a description of the original ones.
207 */
208void ffclock_bintime(struct bintime *bt);
209void ffclock_nanotime(struct timespec *tsp);
210void ffclock_microtime(struct timeval *tvp);
211
212void ffclock_getbintime(struct bintime *bt);
213void ffclock_getnanotime(struct timespec *tsp);
214void ffclock_getmicrotime(struct timeval *tvp);
215
216void ffclock_binuptime(struct bintime *bt);
217void ffclock_nanouptime(struct timespec *tsp);
218void ffclock_microuptime(struct timeval *tvp);
219
220void ffclock_getbinuptime(struct bintime *bt);
221void ffclock_getnanouptime(struct timespec *tsp);
222void ffclock_getmicrouptime(struct timeval *tvp);
223
224/*
225 * Wrapper routines to convert a time interval specified in ffcounter units into
226 * seconds using the current feed-forward clock estimates.
227 */
228void ffclock_bindifftime(ffcounter ffdelta, struct bintime *bt);
229void ffclock_nanodifftime(ffcounter ffdelta, struct timespec *tsp);
230void ffclock_microdifftime(ffcounter ffdelta, struct timeval *tvp);
231
232/*
233 * When FFCLOCK is enabled in the kernel, [get]{bin,nano,micro}[up]time() become
234 * wrappers around equivalent feedback or feed-forward functions. Provide access
235 * outside of kern_tc.c to the feedback clock equivalent functions for
236 * specialised use i.e. these are not for general consumption.
237 */
238void fbclock_bintime(struct bintime *bt);
239void fbclock_nanotime(struct timespec *tsp);
240void fbclock_microtime(struct timeval *tvp);
241
242void fbclock_getbintime(struct bintime *bt);
243void fbclock_getnanotime(struct timespec *tsp);
244void fbclock_getmicrotime(struct timeval *tvp);
245
246void fbclock_binuptime(struct bintime *bt);
247void fbclock_nanouptime(struct timespec *tsp);
248void fbclock_microuptime(struct timeval *tvp);
249
250void fbclock_getbinuptime(struct bintime *bt);
251void fbclock_getnanouptime(struct timespec *tsp);
252void fbclock_getmicrouptime(struct timeval *tvp);
253
254/*
255 * Public system clock wrapper API which allows consumers to select which clock
256 * to obtain time from, independent of the current default system clock. These
257 * wrappers should be used instead of directly calling the underlying fbclock_
258 * or ffclock_ functions.
259 */
260static inline void
261bintime_fromclock(struct bintime *bt, int whichclock)
262{
263
264 if (whichclock == SYSCLOCK_FFWD)
265 ffclock_bintime(bt);
266 else
267 fbclock_bintime(bt);
268}
269
270static inline void
271nanotime_fromclock(struct timespec *tsp, int whichclock)
272{
273
274 if (whichclock == SYSCLOCK_FFWD)
275 ffclock_nanotime(tsp);
276 else
277 fbclock_nanotime(tsp);
278}
279
280static inline void
281microtime_fromclock(struct timeval *tvp, int whichclock)
282{
283
284 if (whichclock == SYSCLOCK_FFWD)
285 ffclock_microtime(tvp);
286 else
287 fbclock_microtime(tvp);
288}
289
290static inline void
291getbintime_fromclock(struct bintime *bt, int whichclock)
292{
293
294 if (whichclock == SYSCLOCK_FFWD)
295 ffclock_getbintime(bt);
296 else
297 fbclock_getbintime(bt);
298}
299
300static inline void
301getnanotime_fromclock(struct timespec *tsp, int whichclock)
302{
303
304 if (whichclock == SYSCLOCK_FFWD)
305 ffclock_getnanotime(tsp);
306 else
307 fbclock_getnanotime(tsp);
308}
309
310static inline void
311getmicrotime_fromclock(struct timeval *tvp, int whichclock)
312{
313
314 if (whichclock == SYSCLOCK_FFWD)
315 ffclock_getmicrotime(tvp);
316 else
317 fbclock_getmicrotime(tvp);
318}
319
320static inline void
321binuptime_fromclock(struct bintime *bt, int whichclock)
322{
323
324 if (whichclock == SYSCLOCK_FFWD)
325 ffclock_binuptime(bt);
326 else
327 fbclock_binuptime(bt);
328}
329
330static inline void
331nanouptime_fromclock(struct timespec *tsp, int whichclock)
332{
333
334 if (whichclock == SYSCLOCK_FFWD)
335 ffclock_nanouptime(tsp);
336 else
337 fbclock_nanouptime(tsp);
338}
339
340static inline void
341microuptime_fromclock(struct timeval *tvp, int whichclock)
342{
343
344 if (whichclock == SYSCLOCK_FFWD)
345 ffclock_microuptime(tvp);
346 else
347 fbclock_microuptime(tvp);
348}
349
350static inline void
351getbinuptime_fromclock(struct bintime *bt, int whichclock)
352{
353
354 if (whichclock == SYSCLOCK_FFWD)
355 ffclock_getbinuptime(bt);
356 else
357 fbclock_getbinuptime(bt);
358}
359
360static inline void
361getnanouptime_fromclock(struct timespec *tsp, int whichclock)
362{
363
364 if (whichclock == SYSCLOCK_FFWD)
365 ffclock_getnanouptime(tsp);
366 else
367 fbclock_getnanouptime(tsp);
368}
369
370static inline void
371getmicrouptime_fromclock(struct timeval *tvp, int whichclock)
372{
373
374 if (whichclock == SYSCLOCK_FFWD)
375 ffclock_getmicrouptime(tvp);
376 else
377 fbclock_getmicrouptime(tvp);
378}
379
380#else /* !_KERNEL */
381
382/* Feed-Forward Clock system calls. */
383__BEGIN_DECLS
384int ffclock_getcounter(ffcounter *ffcount);
385int ffclock_getestimate(struct ffclock_estimate *cest);
386int ffclock_setestimate(struct ffclock_estimate *cest);
387__END_DECLS
388
389#endif /* _KERNEL */
390#endif /* __BSD_VISIBLE */
391#endif /* _SYS_TIMEFF_H_ */
ffclock_estimate
Definition: timeffc.h:43