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/include/linux/timex.h

https://github.com/airy09/android_kernel_sony_apq8064
C Header | 266 lines | 121 code | 33 blank | 112 comment | 0 complexity | 1dc2177ab4600497f085e5a97b56dcaf MD5 | raw file
  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/time.h>
 57
 58#define NTP_API		4	/* NTP API version */
 59
 60/*
 61 * syscall interface - used (mainly by NTP daemon)
 62 * to discipline kernel clock oscillator
 63 */
 64struct timex {
 65	unsigned int modes;	/* mode selector */
 66	long offset;		/* time offset (usec) */
 67	long freq;		/* frequency offset (scaled ppm) */
 68	long maxerror;		/* maximum error (usec) */
 69	long esterror;		/* estimated error (usec) */
 70	int status;		/* clock command/status */
 71	long constant;		/* pll time constant */
 72	long precision;		/* clock precision (usec) (read only) */
 73	long tolerance;		/* clock frequency tolerance (ppm)
 74				 * (read only)
 75				 */
 76	struct timeval time;	/* (read only, except for ADJ_SETOFFSET) */
 77	long tick;		/* (modified) usecs between clock ticks */
 78
 79	long ppsfreq;           /* pps frequency (scaled ppm) (ro) */
 80	long jitter;            /* pps jitter (us) (ro) */
 81	int shift;              /* interval duration (s) (shift) (ro) */
 82	long stabil;            /* pps stability (scaled ppm) (ro) */
 83	long jitcnt;            /* jitter limit exceeded (ro) */
 84	long calcnt;            /* calibration intervals (ro) */
 85	long errcnt;            /* calibration errors (ro) */
 86	long stbcnt;            /* stability limit exceeded (ro) */
 87
 88	int tai;		/* TAI offset (ro) */
 89
 90	int  :32; int  :32; int  :32; int  :32;
 91	int  :32; int  :32; int  :32; int  :32;
 92	int  :32; int  :32; int  :32;
 93};
 94
 95/*
 96 * Mode codes (timex.mode)
 97 */
 98#define ADJ_OFFSET		0x0001	/* time offset */
 99#define ADJ_FREQUENCY		0x0002	/* frequency offset */
100#define ADJ_MAXERROR		0x0004	/* maximum time error */
101#define ADJ_ESTERROR		0x0008	/* estimated time error */
102#define ADJ_STATUS		0x0010	/* clock status */
103#define ADJ_TIMECONST		0x0020	/* pll time constant */
104#define ADJ_TAI			0x0080	/* set TAI offset */
105#define ADJ_SETOFFSET		0x0100  /* add 'time' to current time */
106#define ADJ_MICRO		0x1000	/* select microsecond resolution */
107#define ADJ_NANO		0x2000	/* select nanosecond resolution */
108#define ADJ_TICK		0x4000	/* tick value */
109
110#ifdef __KERNEL__
111#define ADJ_ADJTIME		0x8000	/* switch between adjtime/adjtimex modes */
112#define ADJ_OFFSET_SINGLESHOT	0x0001	/* old-fashioned adjtime */
113#define ADJ_OFFSET_READONLY	0x2000	/* read-only adjtime */
114#else
115#define ADJ_OFFSET_SINGLESHOT	0x8001	/* old-fashioned adjtime */
116#define ADJ_OFFSET_SS_READ	0xa001	/* read-only adjtime */
117#endif
118
119/* NTP userland likes the MOD_ prefix better */
120#define MOD_OFFSET	ADJ_OFFSET
121#define MOD_FREQUENCY	ADJ_FREQUENCY
122#define MOD_MAXERROR	ADJ_MAXERROR
123#define MOD_ESTERROR	ADJ_ESTERROR
124#define MOD_STATUS	ADJ_STATUS
125#define MOD_TIMECONST	ADJ_TIMECONST
126#define MOD_TAI	ADJ_TAI
127#define MOD_MICRO	ADJ_MICRO
128#define MOD_NANO	ADJ_NANO
129
130
131/*
132 * Status codes (timex.status)
133 */
134#define STA_PLL		0x0001	/* enable PLL updates (rw) */
135#define STA_PPSFREQ	0x0002	/* enable PPS freq discipline (rw) */
136#define STA_PPSTIME	0x0004	/* enable PPS time discipline (rw) */
137#define STA_FLL		0x0008	/* select frequency-lock mode (rw) */
138
139#define STA_INS		0x0010	/* insert leap (rw) */
140#define STA_DEL		0x0020	/* delete leap (rw) */
141#define STA_UNSYNC	0x0040	/* clock unsynchronized (rw) */
142#define STA_FREQHOLD	0x0080	/* hold frequency (rw) */
143
144#define STA_PPSSIGNAL	0x0100	/* PPS signal present (ro) */
145#define STA_PPSJITTER	0x0200	/* PPS signal jitter exceeded (ro) */
146#define STA_PPSWANDER	0x0400	/* PPS signal wander exceeded (ro) */
147#define STA_PPSERROR	0x0800	/* PPS signal calibration error (ro) */
148
149#define STA_CLOCKERR	0x1000	/* clock hardware fault (ro) */
150#define STA_NANO	0x2000	/* resolution (0 = us, 1 = ns) (ro) */
151#define STA_MODE	0x4000	/* mode (0 = PLL, 1 = FLL) (ro) */
152#define STA_CLK		0x8000	/* clock source (0 = A, 1 = B) (ro) */
153
154/* read-only bits */
155#define STA_RONLY (STA_PPSSIGNAL | STA_PPSJITTER | STA_PPSWANDER | \
156	STA_PPSERROR | STA_CLOCKERR | STA_NANO | STA_MODE | STA_CLK)
157
158/*
159 * Clock states (time_state)
160 */
161#define TIME_OK		0	/* clock synchronized, no leap second */
162#define TIME_INS	1	/* insert leap second */
163#define TIME_DEL	2	/* delete leap second */
164#define TIME_OOP	3	/* leap second in progress */
165#define TIME_WAIT	4	/* leap second has occurred */
166#define TIME_ERROR	5	/* clock not synchronized */
167#define TIME_BAD	TIME_ERROR /* bw compat */
168
169#ifdef __KERNEL__
170#include <linux/compiler.h>
171#include <linux/types.h>
172#include <linux/param.h>
173
174#include <asm/timex.h>
175
176/*
177 * SHIFT_PLL is used as a dampening factor to define how much we
178 * adjust the frequency correction for a given offset in PLL mode.
179 * It also used in dampening the offset correction, to define how
180 * much of the current value in time_offset we correct for each
181 * second. Changing this value changes the stiffness of the ntp
182 * adjustment code. A lower value makes it more flexible, reducing
183 * NTP convergence time. A higher value makes it stiffer, increasing
184 * convergence time, but making the clock more stable.
185 *
186 * In David Mills' nanokernel reference implementation SHIFT_PLL is 4.
187 * However this seems to increase convergence time much too long.
188 *
189 * https://lists.ntp.org/pipermail/hackers/2008-January/003487.html
190 *
191 * In the above mailing list discussion, it seems the value of 4
192 * was appropriate for other Unix systems with HZ=100, and that
193 * SHIFT_PLL should be decreased as HZ increases. However, Linux's
194 * clock steering implementation is HZ independent.
195 *
196 * Through experimentation, a SHIFT_PLL value of 2 was found to allow
197 * for fast convergence (very similar to the NTPv3 code used prior to
198 * v2.6.19), with good clock stability.
199 *
200 *
201 * SHIFT_FLL is used as a dampening factor to define how much we
202 * adjust the frequency correction for a given offset in FLL mode.
203 * In David Mills' nanokernel reference implementation SHIFT_FLL is 2.
204 *
205 * MAXTC establishes the maximum time constant of the PLL.
206 */
207#define SHIFT_PLL	2	/* PLL frequency factor (shift) */
208#define SHIFT_FLL	2	/* FLL frequency factor (shift) */
209#define MAXTC		10	/* maximum time constant (shift) */
210
211/*
212 * SHIFT_USEC defines the scaling (shift) of the time_freq and
213 * time_tolerance variables, which represent the current frequency
214 * offset and maximum frequency tolerance.
215 */
216#define SHIFT_USEC 16		/* frequency offset scale (shift) */
217#define PPM_SCALE ((s64)NSEC_PER_USEC << (NTP_SCALE_SHIFT - SHIFT_USEC))
218#define PPM_SCALE_INV_SHIFT 19
219#define PPM_SCALE_INV ((1LL << (PPM_SCALE_INV_SHIFT + NTP_SCALE_SHIFT)) / \
220		       PPM_SCALE + 1)
221
222#define MAXPHASE 500000000L	/* max phase error (ns) */
223#define MAXFREQ 500000		/* max frequency error (ns/s) */
224#define MAXFREQ_SCALED ((s64)MAXFREQ << NTP_SCALE_SHIFT)
225#define MINSEC 256		/* min interval between updates (s) */
226#define MAXSEC 2048		/* max interval between updates (s) */
227#define NTP_PHASE_LIMIT ((MAXPHASE / NSEC_PER_USEC) << 5) /* beyond max. dispersion */
228
229/*
230 * kernel variables
231 * Note: maximum error = NTP synch distance = dispersion + delay / 2;
232 * estimated error = NTP dispersion.
233 */
234extern unsigned long tick_usec;		/* USER_HZ period (usec) */
235extern unsigned long tick_nsec;		/* ACTHZ          period (nsec) */
236
237extern void ntp_init(void);
238extern void ntp_clear(void);
239
240/* Required to safely shift negative values */
241#define shift_right(x, s) ({	\
242	__typeof__(x) __x = (x);	\
243	__typeof__(s) __s = (s);	\
244	__x < 0 ? -(-__x >> __s) : __x >> __s;	\
245})
246
247#define NTP_SCALE_SHIFT		32
248
249#define NTP_INTERVAL_FREQ  (HZ)
250#define NTP_INTERVAL_LENGTH (NSEC_PER_SEC/NTP_INTERVAL_FREQ)
251
252/* Returns how long ticks are at present, in ns / 2^NTP_SCALE_SHIFT. */
253extern u64 ntp_tick_length(void);
254
255extern int second_overflow(unsigned long secs);
256extern int do_adjtimex(struct timex *);
257extern void hardpps(const struct timespec *, const struct timespec *);
258
259int read_current_timer(unsigned long *timer_val);
260
261/* The clock frequency of the i8253/i8254 PIT */
262#define PIT_TICK_RATE 1193182ul
263
264#endif /* KERNEL */
265
266#endif /* LINUX_TIMEX_H */