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-rw-r--r--kernel/time/ntp.c444
1 files changed, 274 insertions, 170 deletions
diff --git a/kernel/time/ntp.c b/kernel/time/ntp.c
index f5f793d9241..7fc64375ff4 100644
--- a/kernel/time/ntp.c
+++ b/kernel/time/ntp.c
@@ -1,71 +1,129 @@
1/* 1/*
2 * linux/kernel/time/ntp.c
3 *
4 * NTP state machine interfaces and logic. 2 * NTP state machine interfaces and logic.
5 * 3 *
6 * This code was mainly moved from kernel/timer.c and kernel/time.c 4 * This code was mainly moved from kernel/timer.c and kernel/time.c
7 * Please see those files for relevant copyright info and historical 5 * Please see those files for relevant copyright info and historical
8 * changelogs. 6 * changelogs.
9 */ 7 */
10
11#include <linux/mm.h>
12#include <linux/time.h>
13#include <linux/timex.h>
14#include <linux/jiffies.h>
15#include <linux/hrtimer.h>
16#include <linux/capability.h> 8#include <linux/capability.h>
17#include <linux/math64.h>
18#include <linux/clocksource.h> 9#include <linux/clocksource.h>
19#include <linux/workqueue.h> 10#include <linux/workqueue.h>
20#include <asm/timex.h> 11#include <linux/hrtimer.h>
12#include <linux/jiffies.h>
13#include <linux/math64.h>
14#include <linux/timex.h>
15#include <linux/time.h>
16#include <linux/mm.h>
21 17
22/* 18/*
23 * Timekeeping variables 19 * NTP timekeeping variables:
24 */ 20 */
25unsigned long tick_usec = TICK_USEC; /* USER_HZ period (usec) */
26unsigned long tick_nsec; /* ACTHZ period (nsec) */
27u64 tick_length;
28static u64 tick_length_base;
29 21
30static struct hrtimer leap_timer; 22/* USER_HZ period (usecs): */
23unsigned long tick_usec = TICK_USEC;
31 24
32#define MAX_TICKADJ 500 /* microsecs */ 25/* ACTHZ period (nsecs): */
33#define MAX_TICKADJ_SCALED (((u64)(MAX_TICKADJ * NSEC_PER_USEC) << \ 26unsigned long tick_nsec;
34 NTP_SCALE_SHIFT) / NTP_INTERVAL_FREQ) 27
28u64 tick_length;
29static u64 tick_length_base;
30
31static struct hrtimer leap_timer;
32
33#define MAX_TICKADJ 500LL /* usecs */
34#define MAX_TICKADJ_SCALED \
35 (((MAX_TICKADJ * NSEC_PER_USEC) << NTP_SCALE_SHIFT) / NTP_INTERVAL_FREQ)
35 36
36/* 37/*
37 * phase-lock loop variables 38 * phase-lock loop variables
38 */ 39 */
39/* TIME_ERROR prevents overwriting the CMOS clock */
40static int time_state = TIME_OK; /* clock synchronization status */
41int time_status = STA_UNSYNC; /* clock status bits */
42static long time_tai; /* TAI offset (s) */
43static s64 time_offset; /* time adjustment (ns) */
44static long time_constant = 2; /* pll time constant */
45long time_maxerror = NTP_PHASE_LIMIT; /* maximum error (us) */
46long time_esterror = NTP_PHASE_LIMIT; /* estimated error (us) */
47static s64 time_freq; /* frequency offset (scaled ns/s)*/
48static long time_reftime; /* time at last adjustment (s) */
49long time_adjust;
50static long ntp_tick_adj;
51 40
41/*
42 * clock synchronization status
43 *
44 * (TIME_ERROR prevents overwriting the CMOS clock)
45 */
46static int time_state = TIME_OK;
47
48/* clock status bits: */
49int time_status = STA_UNSYNC;
50
51/* TAI offset (secs): */
52static long time_tai;
53
54/* time adjustment (nsecs): */
55static s64 time_offset;
56
57/* pll time constant: */
58static long time_constant = 2;
59
60/* maximum error (usecs): */
61long time_maxerror = NTP_PHASE_LIMIT;
62
63/* estimated error (usecs): */
64long time_esterror = NTP_PHASE_LIMIT;
65
66/* frequency offset (scaled nsecs/secs): */
67static s64 time_freq;
68
69/* time at last adjustment (secs): */
70static long time_reftime;
71
72long time_adjust;
73
74/* constant (boot-param configurable) NTP tick adjustment (upscaled) */
75static s64 ntp_tick_adj;
76
77/*
78 * NTP methods:
79 */
80
81/*
82 * Update (tick_length, tick_length_base, tick_nsec), based
83 * on (tick_usec, ntp_tick_adj, time_freq):
84 */
52static void ntp_update_frequency(void) 85static void ntp_update_frequency(void)
53{ 86{
54 u64 second_length = (u64)(tick_usec * NSEC_PER_USEC * USER_HZ) 87 u64 second_length;
55 << NTP_SCALE_SHIFT; 88 u64 new_base;
56 second_length += (s64)ntp_tick_adj << NTP_SCALE_SHIFT; 89
57 second_length += time_freq; 90 second_length = (u64)(tick_usec * NSEC_PER_USEC * USER_HZ)
91 << NTP_SCALE_SHIFT;
92
93 second_length += ntp_tick_adj;
94 second_length += time_freq;
58 95
59 tick_length_base = second_length; 96 tick_nsec = div_u64(second_length, HZ) >> NTP_SCALE_SHIFT;
97 new_base = div_u64(second_length, NTP_INTERVAL_FREQ);
60 98
61 tick_nsec = div_u64(second_length, HZ) >> NTP_SCALE_SHIFT; 99 /*
62 tick_length_base = div_u64(tick_length_base, NTP_INTERVAL_FREQ); 100 * Don't wait for the next second_overflow, apply
101 * the change to the tick length immediately:
102 */
103 tick_length += new_base - tick_length_base;
104 tick_length_base = new_base;
105}
106
107static inline s64 ntp_update_offset_fll(s64 offset64, long secs)
108{
109 time_status &= ~STA_MODE;
110
111 if (secs < MINSEC)
112 return 0;
113
114 if (!(time_status & STA_FLL) && (secs <= MAXSEC))
115 return 0;
116
117 time_status |= STA_MODE;
118
119 return div_s64(offset64 << (NTP_SCALE_SHIFT - SHIFT_FLL), secs);
63} 120}
64 121
65static void ntp_update_offset(long offset) 122static void ntp_update_offset(long offset)
66{ 123{
67 long mtemp;
68 s64 freq_adj; 124 s64 freq_adj;
125 s64 offset64;
126 long secs;
69 127
70 if (!(time_status & STA_PLL)) 128 if (!(time_status & STA_PLL))
71 return; 129 return;
@@ -84,24 +142,23 @@ static void ntp_update_offset(long offset)
84 * Select how the frequency is to be controlled 142 * Select how the frequency is to be controlled
85 * and in which mode (PLL or FLL). 143 * and in which mode (PLL or FLL).
86 */ 144 */
87 if (time_status & STA_FREQHOLD || time_reftime == 0) 145 secs = xtime.tv_sec - time_reftime;
88 time_reftime = xtime.tv_sec; 146 if (unlikely(time_status & STA_FREQHOLD))
89 mtemp = xtime.tv_sec - time_reftime; 147 secs = 0;
148
90 time_reftime = xtime.tv_sec; 149 time_reftime = xtime.tv_sec;
91 150
92 freq_adj = (s64)offset * mtemp; 151 offset64 = offset;
93 freq_adj <<= NTP_SCALE_SHIFT - 2 * (SHIFT_PLL + 2 + time_constant); 152 freq_adj = (offset64 * secs) <<
94 time_status &= ~STA_MODE; 153 (NTP_SCALE_SHIFT - 2 * (SHIFT_PLL + 2 + time_constant));
95 if (mtemp >= MINSEC && (time_status & STA_FLL || mtemp > MAXSEC)) {
96 freq_adj += div_s64((s64)offset << (NTP_SCALE_SHIFT - SHIFT_FLL),
97 mtemp);
98 time_status |= STA_MODE;
99 }
100 freq_adj += time_freq;
101 freq_adj = min(freq_adj, MAXFREQ_SCALED);
102 time_freq = max(freq_adj, -MAXFREQ_SCALED);
103 154
104 time_offset = div_s64((s64)offset << NTP_SCALE_SHIFT, NTP_INTERVAL_FREQ); 155 freq_adj += ntp_update_offset_fll(offset64, secs);
156
157 freq_adj = min(freq_adj + time_freq, MAXFREQ_SCALED);
158
159 time_freq = max(freq_adj, -MAXFREQ_SCALED);
160
161 time_offset = div_s64(offset64 << NTP_SCALE_SHIFT, NTP_INTERVAL_FREQ);
105} 162}
106 163