1 /********************************************* 1
2 *
3 * Copyright (c) David L. Mills 1993
4 *
5 * Permission to use, copy, modify, and distri
6 * documentation for any purpose and without f
7 * that the above copyright notice appears in
8 * copyright notice and this permission notice
9 * documentation, and that the name University
10 * advertising or publicity pertaining to dist
11 * without specific, written prior permission.
12 * makes no representations about the suitabil
13 * purpose. It is provided "as is" without ex
14 *
15 *********************************************
16
17 /*
18 * Modification history timex.h
19 *
20 * 29 Dec 97 Russell King
21 * Moved CLOCK_TICK_RATE, CLOCK_TICK_FACT
22 * for ARM machines
23 *
24 * 9 Jan 97 Adrian Sun
25 * Shifted LATCH define to allow access t
26 *
27 * 26 Sep 94 David L. Mills
28 * Added defines for hybrid phase/frequen
29 *
30 * 19 Mar 94 David L. Mills
31 * Moved defines from kernel routines to
32 * defines for PPS phase-lock loop.
33 *
34 * 20 Feb 94 David L. Mills
35 * Revised status codes and structures fo
36 * signal discipline.
37 *
38 * 28 Nov 93 David L. Mills
39 * Adjusted parameters to improve stabili
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
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 <uapi/linux/timex.h>
57
58 #define ADJ_ADJTIME 0x8000 /* swi
59 #define ADJ_OFFSET_SINGLESHOT 0x0001 /* old
60 #define ADJ_OFFSET_READONLY 0x2000 /* rea
61 #include <linux/compiler.h>
62 #include <linux/types.h>
63 #include <linux/param.h>
64
65 unsigned long random_get_entropy_fallback(void
66
67 #include <asm/timex.h>
68
69 #ifndef random_get_entropy
70 /*
71 * The random_get_entropy() function is used b
72 * in order to extract entropy via the relativ
73 * when an interrupt takes places versus a hig
74 * timing source or cycle counter. Since it w
75 * single interrupt, it must have a very low c
76 *
77 * By default we use get_cycles() for this pur
78 * architectures may override this in their as
79 * If a given arch does not have get_cycles(),
80 * using random_get_entropy_fallback().
81 */
82 #ifdef get_cycles
83 #define random_get_entropy() ((unsigned lon
84 #else
85 #define random_get_entropy() random_get_ent
86 #endif
87 #endif
88
89 /*
90 * SHIFT_PLL is used as a dampening factor to
91 * adjust the frequency correction for a given
92 * It also used in dampening the offset correc
93 * much of the current value in time_offset we
94 * second. Changing this value changes the sti
95 * adjustment code. A lower value makes it mor
96 * NTP convergence time. A higher value makes
97 * convergence time, but making the clock more
98 *
99 * In David Mills' nanokernel reference implem
100 * However this seems to increase convergence
101 *
102 * https://lists.ntp.org/pipermail/hackers/200
103 *
104 * In the above mailing list discussion, it se
105 * was appropriate for other Unix systems with
106 * SHIFT_PLL should be decreased as HZ increas
107 * clock steering implementation is HZ indepen
108 *
109 * Through experimentation, a SHIFT_PLL value
110 * for fast convergence (very similar to the N
111 * v2.6.19), with good clock stability.
112 *
113 *
114 * SHIFT_FLL is used as a dampening factor to
115 * adjust the frequency correction for a given
116 * In David Mills' nanokernel reference implem
117 *
118 * MAXTC establishes the maximum time constant
119 */
120 #define SHIFT_PLL 2 /* PLL frequen
121 #define SHIFT_FLL 2 /* FLL frequen
122 #define MAXTC 10 /* maximum tim
123
124 /*
125 * SHIFT_USEC defines the scaling (shift) of t
126 * time_tolerance variables, which represent t
127 * offset and maximum frequency tolerance.
128 */
129 #define SHIFT_USEC 16 /* frequency o
130 #define PPM_SCALE ((s64)NSEC_PER_USEC << (NTP_
131 #define PPM_SCALE_INV_SHIFT 19
132 #define PPM_SCALE_INV ((1LL << (PPM_SCALE_INV_
133 PPM_SCALE + 1)
134
135 #define MAXPHASE 500000000L /* max phase e
136 #define MAXFREQ 500000 /* max frequen
137 #define MAXFREQ_SCALED ((s64)MAXFREQ << NTP_SC
138 #define MINSEC 256 /* min interva
139 #define MAXSEC 2048 /* max interva
140 #define NTP_PHASE_LIMIT ((MAXPHASE / NSEC_PER_
141
142 /*
143 * kernel variables
144 * Note: maximum error = NTP sync distance = d
145 * estimated error = NTP dispersion.
146 */
147 extern unsigned long tick_usec; /* USE
148 extern unsigned long tick_nsec; /* SHI
149
150 /* Required to safely shift negative values */
151 #define shift_right(x, s) ({ \
152 __typeof__(x) __x = (x); \
153 __typeof__(s) __s = (s); \
154 __x < 0 ? -(-__x >> __s) : __x >> __s;
155 })
156
157 #define NTP_SCALE_SHIFT 32
158
159 #define NTP_INTERVAL_FREQ (HZ)
160 #define NTP_INTERVAL_LENGTH (NSEC_PER_SEC/NTP_
161
162 extern int do_adjtimex(struct __kernel_timex *
163 extern int do_clock_adjtime(const clockid_t wh
164
165 extern void hardpps(const struct timespec64 *,
166
167 int read_current_timer(unsigned long *timer_va
168
169 /* The clock frequency of the i8253/i8254 PIT
170 #define PIT_TICK_RATE 1193182ul
171
172 #endif /* LINUX_TIMEX_H */
173
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