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