1 /*****************************************************************************
2 * *
3 * Copyright (c) David L. Mills 1993 *
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 * 29 Dec 97 Russell King
21 * Moved CLOCK_TICK_RATE, CLOCK_TICK_FACTOR and FINETUNE to asm/timex.h
22 * for ARM machines
23 *
24 * 9 Jan 97 Adrian Sun
25 * Shifted LATCH define to allow access to alpha machines.
26 *
27 * 26 Sep 94 David L. Mills
28 * Added defines for hybrid phase/frequency-lock loop.
29 *
30 * 19 Mar 94 David L. Mills
31 * Moved defines from kernel routines to header file and added new
32 * defines for PPS phase-lock loop.
33 *
34 * 20 Feb 94 David L. Mills
35 * Revised status codes and structures for external clock and PPS
36 * signal discipline.
37 *
38 * 28 Nov 93 David L. Mills
39 * Adjusted parameters to improve stability and increase poll
40 * interval.
41 *
42 * 17 Sep 93 David L. Mills
43 * Created file $NTP/include/sys/timex.h
44 * 07 Oct 93 Torsten Duwe
45 * Derived linux/timex.h
46 * 1995-08-13 Torsten Duwe
47 * kernel PLL updated to 1994-12-13 specs (rfc-1589)
48 * 1997-08-30 Ulrich Windl
49 * Added new constant NTP_PHASE_LIMIT
50 * 2004-08-12 Christoph Lameter
51 * Reworked time interpolation logic
52 */
53 #ifndef _LINUX_TIMEX_H
54 #define _LINUX_TIMEX_H
55
56 #include <linux/compiler.h>
57 #include <linux/time.h>
58
59 #include <asm/param.h>
60
61 /*
62 * SHIFT_KG and SHIFT_KF establish the damping of the PLL and are chosen
63 * for a slightly underdamped convergence characteristic. SHIFT_KH
64 * establishes the damping of the FLL and is chosen by wisdom and black
65 * art.
66 *
67 * MAXTC establishes the maximum time constant of the PLL. With the
68 * SHIFT_KG and SHIFT_KF values given and a time constant range from
69 * zero to MAXTC, the PLL will converge in 15 minutes to 16 hours,
70 * respectively.
71 */
72 #define SHIFT_KG 6 /* phase factor (shift) */
73 #define SHIFT_KF 16 /* PLL frequency factor (shift) */
74 #define SHIFT_KH 2 /* FLL frequency factor (shift) */
75 #define MAXTC 6 /* maximum time constant (shift) */
76
77 /*
78 * The SHIFT_SCALE define establishes the decimal point of the time_phase
79 * variable which serves as an extension to the low-order bits of the
80 * system clock variable. The SHIFT_UPDATE define establishes the decimal
81 * point of the time_offset variable which represents the current offset
82 * with respect to standard time. The FINENSEC define represents 1 nsec in
83 * scaled units.
84 *
85 * SHIFT_USEC defines the scaling (shift) of the time_freq and
86 * time_tolerance variables, which represent the current frequency
87 * offset and maximum frequency tolerance.
88 *
89 * FINENSEC is 1 ns in SHIFT_UPDATE units of the time_phase variable.
90 */
91 #define SHIFT_SCALE 22 /* phase scale (shift) */
92 #define SHIFT_UPDATE (SHIFT_KG + MAXTC) /* time offset scale (shift) */
93 #define SHIFT_USEC 16 /* frequency offset scale (shift) */
94 #define FINENSEC (1L << (SHIFT_SCALE - 10)) /* ~1 ns in phase units */
95
96 #define MAXPHASE 512000L /* max phase error (us) */
97 #define MAXFREQ (512L << SHIFT_USEC) /* max frequency error (ppm) */
98 #define MINSEC 16L /* min interval between updates (s) */
99 #define MAXSEC 1200L /* max interval between updates (s) */
100 #define NTP_PHASE_LIMIT (MAXPHASE << 5) /* beyond max. dispersion */
101
102 /*
103 * syscall interface - used (mainly by NTP daemon)
104 * to discipline kernel clock oscillator
105 */
106 struct timex {
107 unsigned int modes; /* mode selector */
108 long offset; /* time offset (usec) */
109 long freq; /* frequency offset (scaled ppm) */
110 long maxerror; /* maximum error (usec) */
111 long esterror; /* estimated error (usec) */
112 int status; /* clock command/status */
113 long constant; /* pll time constant */
114 long precision; /* clock precision (usec) (read only) */
115 long tolerance; /* clock frequency tolerance (ppm)
116 * (read only)
117 */
118 struct timeval time; /* (read only) */
119 long tick; /* (modified) usecs between clock ticks */
120
121 long ppsfreq; /* pps frequency (scaled ppm) (ro) */
122 long jitter; /* pps jitter (us) (ro) */
123 int shift; /* interval duration (s) (shift) (ro) */
124 long stabil; /* pps stability (scaled ppm) (ro) */
125 long jitcnt; /* jitter limit exceeded (ro) */
126 long calcnt; /* calibration intervals (ro) */
127 long errcnt; /* calibration errors (ro) */
128 long stbcnt; /* stability limit exceeded (ro) */
129
130 int :32; int :32; int :32; int :32;
131 int :32; int :32; int :32; int :32;
132 int :32; int :32; int :32; int :32;
133 };
134
135 /*
136 * Mode codes (timex.mode)
137 */
138 #define ADJ_OFFSET 0x0001 /* time offset */
139 #define ADJ_FREQUENCY 0x0002 /* frequency offset */
140 #define ADJ_MAXERROR 0x0004 /* maximum time error */
141 #define ADJ_ESTERROR 0x0008 /* estimated time error */
142 #define ADJ_STATUS 0x0010 /* clock status */
143 #define ADJ_TIMECONST 0x0020 /* pll time constant */
144 #define ADJ_TICK 0x4000 /* tick value */
145 #define ADJ_OFFSET_SINGLESHOT 0x8001 /* old-fashioned adjtime */
146
147 /* xntp 3.4 compatibility names */
148 #define MOD_OFFSET ADJ_OFFSET
149 #define MOD_FREQUENCY ADJ_FREQUENCY
150 #define MOD_MAXERROR ADJ_MAXERROR
151 #define MOD_ESTERROR ADJ_ESTERROR
152 #define MOD_STATUS ADJ_STATUS
153 #define MOD_TIMECONST ADJ_TIMECONST
154 #define MOD_CLKB ADJ_TICK
155 #define MOD_CLKA ADJ_OFFSET_SINGLESHOT /* 0x8000 in original */
156
157
158 /*
159 * Status codes (timex.status)
160 */
161 #define STA_PLL 0x0001 /* enable PLL updates (rw) */
162 #define STA_PPSFREQ 0x0002 /* enable PPS freq discipline (rw) */
163 #define STA_PPSTIME 0x0004 /* enable PPS time discipline (rw) */
164 #define STA_FLL 0x0008 /* select frequency-lock mode (rw) */
165
166 #define STA_INS 0x0010 /* insert leap (rw) */
167 #define STA_DEL 0x0020 /* delete leap (rw) */
168 #define STA_UNSYNC 0x0040 /* clock unsynchronized (rw) */
169 #define STA_FREQHOLD 0x0080 /* hold frequency (rw) */
170
171 #define STA_PPSSIGNAL 0x0100 /* PPS signal present (ro) */
172 #define STA_PPSJITTER 0x0200 /* PPS signal jitter exceeded (ro) */
173 #define STA_PPSWANDER 0x0400 /* PPS signal wander exceeded (ro) */
174 #define STA_PPSERROR 0x0800 /* PPS signal calibration error (ro) */
175
176 #define STA_CLOCKERR 0x1000 /* clock hardware fault (ro) */
177
178 #define STA_RONLY (STA_PPSSIGNAL | STA_PPSJITTER | STA_PPSWANDER | \
179 STA_PPSERROR | STA_CLOCKERR) /* read-only bits */
180
181 /*
182 * Clock states (time_state)
183 */
184 #define TIME_OK 0 /* clock synchronized, no leap second */
185 #define TIME_INS 1 /* insert leap second */
186 #define TIME_DEL 2 /* delete leap second */
187 #define TIME_OOP 3 /* leap second in progress */
188 #define TIME_WAIT 4 /* leap second has occurred */
189 #define TIME_ERROR 5 /* clock not synchronized */
190 #define TIME_BAD TIME_ERROR /* bw compat */
191
192 #ifdef __KERNEL__
193 #include <asm/timex.h>
194
195 /*
196 * kernel variables
197 * Note: maximum error = NTP synch distance = dispersion + delay / 2;
198 * estimated error = NTP dispersion.
199 */
200 extern unsigned long tick_usec; /* USER_HZ period (usec) */
201 extern unsigned long tick_nsec; /* ACTHZ period (nsec) */
202 extern int tickadj; /* amount of adjustment per tick */
203
204 /*
205 * phase-lock loop variables
206 */
207 extern int time_state; /* clock status */
208 extern int time_status; /* clock synchronization status bits */
209 extern long time_offset; /* time adjustment (us) */
210 extern long time_constant; /* pll time constant */
211 extern long time_tolerance; /* frequency tolerance (ppm) */
212 extern long time_precision; /* clock precision (us) */
213 extern long time_maxerror; /* maximum error */
214 extern long time_esterror; /* estimated error */
215
216 extern long time_freq; /* frequency offset (scaled ppm) */
217 extern long time_reftime; /* time at last adjustment (s) */
218
219 extern long time_adjust; /* The amount of adjtime left */
220 extern long time_next_adjust; /* Value for time_adjust at next tick */
221
222 /**
223 * ntp_clear - Clears the NTP state variables
224 *
225 * Must be called while holding a write on the xtime_lock
226 */
ntp_clear(void)227 static inline void ntp_clear(void)
228 {
229 time_adjust = 0; /* stop active adjtime() */
230 time_status |= STA_UNSYNC;
231 time_maxerror = NTP_PHASE_LIMIT;
232 time_esterror = NTP_PHASE_LIMIT;
233 }
234
235 /**
236 * ntp_synced - Returns 1 if the NTP status is not UNSYNC
237 *
238 */
ntp_synced(void)239 static inline int ntp_synced(void)
240 {
241 return !(time_status & STA_UNSYNC);
242 }
243
244 /* Required to safely shift negative values */
245 #define shift_right(x, s) ({ \
246 __typeof__(x) __x = (x); \
247 __typeof__(s) __s = (s); \
248 __x < 0 ? -(-__x >> __s) : __x >> __s; \
249 })
250
251
252 #ifdef CONFIG_TIME_INTERPOLATION
253
254 #define TIME_SOURCE_CPU 0
255 #define TIME_SOURCE_MMIO64 1
256 #define TIME_SOURCE_MMIO32 2
257 #define TIME_SOURCE_FUNCTION 3
258
259 /* For proper operations time_interpolator clocks must run slightly slower
260 * than the standard clock since the interpolator may only correct by having
261 * time jump forward during a tick. A slower clock is usually a side effect
262 * of the integer divide of the nanoseconds in a second by the frequency.
263 * The accuracy of the division can be increased by specifying a shift.
264 * However, this may cause the clock not to be slow enough.
265 * The interpolator will self-tune the clock by slowing down if no
266 * resets occur or speeding up if the time jumps per analysis cycle
267 * become too high.
268 *
269 * Setting jitter compensates for a fluctuating timesource by comparing
270 * to the last value read from the timesource to insure that an earlier value
271 * is not returned by a later call. The price to pay
272 * for the compensation is that the timer routines are not as scalable anymore.
273 */
274
275 struct time_interpolator {
276 u16 source; /* time source flags */
277 u8 shift; /* increases accuracy of multiply by shifting. */
278 /* Note that bits may be lost if shift is set too high */
279 u8 jitter; /* if set compensate for fluctuations */
280 u32 nsec_per_cyc; /* set by register_time_interpolator() */
281 void *addr; /* address of counter or function */
282 u64 mask; /* mask the valid bits of the counter */
283 unsigned long offset; /* nsec offset at last update of interpolator */
284 u64 last_counter; /* counter value in units of the counter at last update */
285 u64 last_cycle; /* Last timer value if TIME_SOURCE_JITTER is set */
286 u64 frequency; /* frequency in counts/second */
287 long drift; /* drift in parts-per-million (or -1) */
288 unsigned long skips; /* skips forward */
289 unsigned long ns_skipped; /* nanoseconds skipped */
290 struct time_interpolator *next;
291 };
292
293 extern void register_time_interpolator(struct time_interpolator *);
294 extern void unregister_time_interpolator(struct time_interpolator *);
295 extern void time_interpolator_reset(void);
296 extern unsigned long time_interpolator_get_offset(void);
297
298 #else /* !CONFIG_TIME_INTERPOLATION */
299
300 static inline void
time_interpolator_reset(void)301 time_interpolator_reset(void)
302 {
303 }
304
305 #endif /* !CONFIG_TIME_INTERPOLATION */
306
307 #define TICK_LENGTH_SHIFT 32
308
309 /* Returns how long ticks are at present, in ns / 2^(SHIFT_SCALE-10). */
310 extern u64 current_tick_length(void);
311
312 extern int do_adjtimex(struct timex *);
313
314 #endif /* KERNEL */
315
316 #endif /* LINUX_TIMEX_H */
317