FreeBSD/Linux Kernel Cross Reference
sys/sys/timex.h
1 /******************************************************************************
2 * *
3 * Copyright (c) David L. Mills 1993, 1994 *
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 * 26 Sep 94 David L. Mills
21 * Added defines for hybrid phase/frequency-lock loop.
22 *
23 * 19 Mar 94 David L. Mills
24 * Moved defines from kernel routines to header file and added new
25 * defines for PPS phase-lock loop.
26 *
27 * 20 Feb 94 David L. Mills
28 * Revised status codes and structures for external clock and PPS
29 * signal discipline.
30 *
31 * 28 Nov 93 David L. Mills
32 * Adjusted parameters to improve stability and increase poll
33 * interval.
34 *
35 * 17 Sep 93 David L. Mills
36 * Created file
37 */
38 /*
39 * This header file defines the Network Time Protocol (NTP) interfaces
40 * for user and daemon application programs. These are implemented using
41 * private syscalls and data structures and require specific kernel
42 * support.
43 *
44 * NAME
45 * ntp_gettime - NTP user application interface
46 *
47 * SYNOPSIS
48 * #include <sys/timex.h>
49 *
50 * int syscall(SYS_ntp_gettime, tptr)
51 *
52 * int SYS_ntp_gettime defined in syscall.h header file
53 * struct ntptimeval *tptr pointer to ntptimeval structure
54 *
55 * NAME
56 * ntp_adjtime - NTP daemon application interface
57 *
58 * SYNOPSIS
59 * #include <sys/timex.h>
60 *
61 * int syscall(SYS_ntp_adjtime, mode, tptr)
62 *
63 * int SYS_ntp_adjtime defined in syscall.h header file
64 * struct timex *tptr pointer to timex structure
65 *
66 */
67 #ifndef _SYS_TIMEX_H_
68 #define _SYS_TIMEX_H_ 1
69
70 #ifndef MSDOS /* Microsoft specific */
71 #include <sys/syscall.h>
72 #endif /* MSDOS */
73
74 /*
75 * The following defines establish the engineering parameters of the
76 * phase-lock loop (PLL) model used in the kernel implementation. These
77 * parameters have been carefully chosen by analysis for good stability
78 * and wide dynamic range.
79 *
80 * The hz variable is defined in the kernel build environment. It
81 * establishes the timer interrupt frequency, 100 Hz for the SunOS
82 * kernel, 256 Hz for the Ultrix kernel and 1024 Hz for the OSF/1
83 * kernel. SHIFT_HZ expresses the same value as the nearest power of two
84 * in order to avoid hardware multiply operations.
85 *
86 * SHIFT_KG and SHIFT_KF establish the damping of the PLL and are chosen
87 * for a slightly underdamped convergence characteristic. SHIFT_KH
88 * establishes the damping of the FLL and is chosen by wisdom and black
89 * art.
90 *
91 * MAXTC establishes the maximum time constant of the PLL. With the
92 * SHIFT_KG and SHIFT_KF values given and a time constant range from
93 * zero to MAXTC, the PLL will converge in 15 minutes to 16 hours,
94 * respectively.
95 */
96 #define SHIFT_HZ 7 /* log2(hz) */
97 #define SHIFT_KG 6 /* phase factor (shift) */
98 #define SHIFT_KF 16 /* PLL frequency factor (shift) */
99 #define SHIFT_KH 2 /* FLL frequency factor (shift) */
100 #define MAXTC 6 /* maximum time constant (shift) */
101
102 /*
103 * The following defines establish the scaling of the various variables
104 * used by the PLL. They are chosen to allow the greatest precision
105 * possible without overflow of a 32-bit word.
106 *
107 * SHIFT_SCALE defines the scaling (shift) of the time_phase variable,
108 * which serves as a an extension to the low-order bits of the system
109 * clock variable time.tv_usec.
110 *
111 * SHIFT_UPDATE defines the scaling (shift) of the time_offset variable,
112 * which represents the current time offset with respect to standard
113 * time.
114 *
115 * SHIFT_USEC defines the scaling (shift) of the time_freq and
116 * time_tolerance variables, which represent the current frequency
117 * offset and maximum frequency tolerance.
118 *
119 * FINEUSEC is 1 us in SHIFT_UPDATE units of the time_phase variable.
120 */
121 #define SHIFT_SCALE 22 /* phase scale (shift) */
122 #define SHIFT_UPDATE (SHIFT_KG + MAXTC) /* time offset scale (shift) */
123 #define SHIFT_USEC 16 /* frequency offset scale (shift) */
124 #define FINEUSEC (1L << SHIFT_SCALE) /* 1 us in phase units */
125
126 /*
127 * The following defines establish the performance envelope of the PLL.
128 * They insure it operates within predefined limits, in order to satisfy
129 * correctness assertions. An excursion which exceeds these bounds is
130 * clamped to the bound and operation proceeds accordingly. In practice,
131 * this can occur only if something has failed or is operating out of
132 * tolerance, but otherwise the PLL continues to operate in a stable
133 * mode.
134 *
135 * MAXPHASE must be set greater than or equal to CLOCK.MAX (128 ms), as
136 * defined in the NTP specification. CLOCK.MAX establishes the maximum
137 * time offset allowed before the system time is reset, rather than
138 * incrementally adjusted. Here, the maximum offset is clamped to
139 * MAXPHASE only in order to prevent overflow errors due to defective
140 * protocol implementations.
141 *
142 * MAXFREQ is the maximum frequency tolerance of the CPU clock
143 * oscillator plus the maximum slew rate allowed by the protocol. It
144 * should be set to at least the frequency tolerance of the oscillator
145 * plus 100 ppm for vernier frequency adjustments. If the kernel
146 * PPS discipline code is configured (PPS_SYNC), the oscillator time and
147 * frequency are disciplined to an external source, presumably with
148 * negligible time and frequency error relative to UTC, and MAXFREQ can
149 * be reduced.
150 *
151 * MAXTIME is the maximum jitter tolerance of the PPS signal if the
152 * kernel PPS discipline code is configured (PPS_SYNC).
153 *
154 * MINSEC and MAXSEC define the lower and upper bounds on the interval
155 * between protocol updates.
156 */
157 #define MAXPHASE 512000L /* max phase error (us) */
158 #ifdef PPS_SYNC
159 #define MAXFREQ (512L << SHIFT_USEC) /* max freq error (100 ppm) */
160 #define MAXTIME (200L << PPS_AVG) /* max PPS error (jitter) (200 us) */
161 #else
162 #define MAXFREQ (512L << SHIFT_USEC) /* max freq error (200 ppm) */
163 #endif /* PPS_SYNC */
164 #define MINSEC 16L /* min interval between updates (s) */
165 #define MAXSEC 1200L /* max interval between updates (s) */
166
167 #ifdef PPS_SYNC
168 /*
169 * The following defines are used only if a pulse-per-second (PPS)
170 * signal is available and connected via a modem control lead, such as
171 * produced by the optional ppsclock feature incorporated in the Sun
172 * asynch driver. They establish the design parameters of the frequency-
173 * lock loop used to discipline the CPU clock oscillator to the PPS
174 * signal.
175 *
176 * PPS_AVG is the averaging factor for the frequency loop, as well as
177 * the time and frequency dispersion.
178 *
179 * PPS_SHIFT and PPS_SHIFTMAX specify the minimum and maximum
180 * calibration intervals, respectively, in seconds as a power of two.
181 *
182 * PPS_VALID is the maximum interval before the PPS signal is considered
183 * invalid and protocol updates used directly instead.
184 *
185 * MAXGLITCH is the maximum interval before a time offset of more than
186 * MAXTIME is believed.
187 */
188 #define PPS_AVG 2 /* pps averaging constant (shift) */
189 #define PPS_SHIFT 2 /* min interval duration (s) (shift) */
190 #define PPS_SHIFTMAX 8 /* max interval duration (s) (shift) */
191 #define PPS_VALID 120 /* pps signal watchdog max (s) */
192 #define MAXGLITCH 30 /* pps signal glitch max (s) */
193 #endif /* PPS_SYNC */
194
195 /*
196 * The following defines and structures define the user interface for
197 * the ntp_gettime() and ntp_adjtime() system calls.
198 *
199 * Control mode codes (timex.modes)
200 */
201 #define MOD_OFFSET 0x0001 /* set time offset */
202 #define MOD_FREQUENCY 0x0002 /* set frequency offset */
203 #define MOD_MAXERROR 0x0004 /* set maximum time error */
204 #define MOD_ESTERROR 0x0008 /* set estimated time error */
205 #define MOD_STATUS 0x0010 /* set clock status bits */
206 #define MOD_TIMECONST 0x0020 /* set pll time constant */
207 #define MOD_CLKB 0x4000 /* set clock B */
208 #define MOD_CLKA 0x8000 /* set clock A */
209
210 /*
211 * Status codes (timex.status)
212 */
213 #define STA_PLL 0x0001 /* enable PLL updates (rw) */
214 #define STA_PPSFREQ 0x0002 /* enable PPS freq discipline (rw) */
215 #define STA_PPSTIME 0x0004 /* enable PPS time discipline (rw) */
216 #define STA_FLL 0x0008 /* select frequency-lock mode (rw) */
217
218 #define STA_INS 0x0010 /* insert leap (rw) */
219 #define STA_DEL 0x0020 /* delete leap (rw) */
220 #define STA_UNSYNC 0x0040 /* clock unsynchronized (rw) */
221 #define STA_FREQHOLD 0x0080 /* hold frequency (rw) */
222
223 #define STA_PPSSIGNAL 0x0100 /* PPS signal present (ro) */
224 #define STA_PPSJITTER 0x0200 /* PPS signal jitter exceeded (ro) */
225 #define STA_PPSWANDER 0x0400 /* PPS signal wander exceeded (ro) */
226 #define STA_PPSERROR 0x0800 /* PPS signal calibration error (ro) */
227
228 #define STA_CLOCKERR 0x1000 /* clock hardware fault (ro) */
229
230 #define STA_RONLY (STA_PPSSIGNAL | STA_PPSJITTER | STA_PPSWANDER | \
231 STA_PPSERROR | STA_CLOCKERR) /* read-only bits */
232
233 /*
234 * Clock states (time_state)
235 */
236 #define TIME_OK 0 /* no leap second warning */
237 #define TIME_INS 1 /* insert leap second warning */
238 #define TIME_DEL 2 /* delete leap second warning */
239 #define TIME_OOP 3 /* leap second in progress */
240 #define TIME_WAIT 4 /* leap second has occured */
241 #define TIME_ERROR 5 /* clock not synchronized */
242
243 /*
244 * NTP user interface (ntp_gettime()) - used to read kernel clock values
245 *
246 * Note: maximum error = NTP synch distance = dispersion + delay / 2;
247 * estimated error = NTP dispersion.
248 */
249 struct ntptimeval {
250 struct timeval time; /* current time (ro) */
251 long maxerror; /* maximum error (us) (ro) */
252 long esterror; /* estimated error (us) (ro) */
253 int time_state; /* what ntp_gettime returns */
254 };
255
256 /*
257 * NTP daemon interface - (ntp_adjtime()) used to discipline CPU clock
258 * oscillator
259 */
260 struct timex {
261 unsigned int modes; /* clock mode bits (wo) */
262 long offset; /* time offset (us) (rw) */
263 long freq; /* frequency offset (scaled ppm) (rw) */
264 long maxerror; /* maximum error (us) (rw) */
265 long esterror; /* estimated error (us) (rw) */
266 int status; /* clock status bits (rw) */
267 long constant; /* pll time constant (rw) */
268 long precision; /* clock precision (us) (ro) */
269 long tolerance; /* clock frequency tolerance (scaled
270 * ppm) (ro) */
271 /*
272 * The following read-only structure members are implemented
273 * only if the PPS signal discipline is configured in the
274 * kernel.
275 */
276 long ppsfreq; /* pps frequency (scaled ppm) (ro) */
277 long jitter; /* pps jitter (us) (ro) */
278 int shift; /* interval duration (s) (shift) (ro) */
279 long stabil; /* pps stability (scaled ppm) (ro) */
280 long jitcnt; /* jitter limit exceeded (ro) */
281 long calcnt; /* calibration intervals (ro) */
282 long errcnt; /* calibration errors (ro) */
283 long stbcnt; /* stability limit exceeded (ro) */
284
285 };
286 #ifdef __FreeBSD__
287
288 /*
289 * sysctl identifiers underneath kern.ntp_pll
290 */
291 #define NTP_PLL_GETTIME 1 /* used by ntp_gettime() */
292 #define NTP_PLL_MAXID 2 /* number of valid ids */
293
294 #define NTP_PLL_NAMES { \
295 { 0, 0 }, \
296 { "gettime", CTLTYPE_STRUCT }, \
297 }
298
299 #ifndef KERNEL
300 #include <sys/cdefs.h>
301
302 __BEGIN_DECLS
303 extern int ntp_gettime __P((struct ntptimeval *));
304 extern int ntp_adjtime __P((struct timex *));
305 __END_DECLS
306
307 #endif /* not KERNEL */
308
309 #endif /* __FreeBSD__ */
310 #endif /* _SYS_TIMEX_H_ */
Cache object: 62717b75974a4f3a25c93f20f2cd913f
|