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6035519f JS |
1 | /* adjtimex() tick adjustment test |
2 | * by: John Stultz <john.stultz@linaro.org> | |
3 | * (C) Copyright Linaro Limited 2015 | |
4 | * Licensed under the GPLv2 | |
5 | * | |
6 | * To build: | |
7 | * $ gcc adjtick.c -o adjtick -lrt | |
8 | * | |
9 | * This program is free software: you can redistribute it and/or modify | |
10 | * it under the terms of the GNU General Public License as published by | |
11 | * the Free Software Foundation, either version 2 of the License, or | |
12 | * (at your option) any later version. | |
13 | * | |
14 | * This program is distributed in the hope that it will be useful, | |
15 | * but WITHOUT ANY WARRANTY; without even the implied warranty of | |
16 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
17 | * GNU General Public License for more details. | |
18 | */ | |
19 | #include <stdio.h> | |
20 | #include <unistd.h> | |
21 | #include <stdlib.h> | |
22 | #include <sys/time.h> | |
23 | #include <sys/timex.h> | |
24 | #include <time.h> | |
25 | ||
6035519f | 26 | #include "../kselftest.h" |
6035519f JS |
27 | |
28 | #define CLOCK_MONOTONIC_RAW 4 | |
29 | ||
30 | #define NSEC_PER_SEC 1000000000LL | |
31 | #define USEC_PER_SEC 1000000 | |
32 | ||
33 | #define MILLION 1000000 | |
34 | ||
35 | long systick; | |
36 | ||
37 | long long llabs(long long val) | |
38 | { | |
39 | if (val < 0) | |
40 | val = -val; | |
41 | return val; | |
42 | } | |
43 | ||
44 | unsigned long long ts_to_nsec(struct timespec ts) | |
45 | { | |
46 | return ts.tv_sec * NSEC_PER_SEC + ts.tv_nsec; | |
47 | } | |
48 | ||
49 | struct timespec nsec_to_ts(long long ns) | |
50 | { | |
51 | struct timespec ts; | |
52 | ||
53 | ts.tv_sec = ns/NSEC_PER_SEC; | |
54 | ts.tv_nsec = ns%NSEC_PER_SEC; | |
55 | ||
56 | return ts; | |
57 | } | |
58 | ||
59 | long long diff_timespec(struct timespec start, struct timespec end) | |
60 | { | |
61 | long long start_ns, end_ns; | |
62 | ||
63 | start_ns = ts_to_nsec(start); | |
64 | end_ns = ts_to_nsec(end); | |
65 | ||
66 | return end_ns - start_ns; | |
67 | } | |
68 | ||
69 | void get_monotonic_and_raw(struct timespec *mon, struct timespec *raw) | |
70 | { | |
71 | struct timespec start, mid, end; | |
72 | long long diff = 0, tmp; | |
73 | int i; | |
74 | ||
75 | clock_gettime(CLOCK_MONOTONIC, mon); | |
76 | clock_gettime(CLOCK_MONOTONIC_RAW, raw); | |
77 | ||
78 | /* Try to get a more tightly bound pairing */ | |
79 | for (i = 0; i < 3; i++) { | |
80 | long long newdiff; | |
81 | ||
82 | clock_gettime(CLOCK_MONOTONIC, &start); | |
83 | clock_gettime(CLOCK_MONOTONIC_RAW, &mid); | |
84 | clock_gettime(CLOCK_MONOTONIC, &end); | |
85 | ||
86 | newdiff = diff_timespec(start, end); | |
87 | if (diff == 0 || newdiff < diff) { | |
88 | diff = newdiff; | |
89 | *raw = mid; | |
90 | tmp = (ts_to_nsec(start) + ts_to_nsec(end))/2; | |
91 | *mon = nsec_to_ts(tmp); | |
92 | } | |
93 | } | |
94 | } | |
95 | ||
96 | long long get_ppm_drift(void) | |
97 | { | |
98 | struct timespec mon_start, raw_start, mon_end, raw_end; | |
99 | long long delta1, delta2, eppm; | |
100 | ||
101 | get_monotonic_and_raw(&mon_start, &raw_start); | |
102 | ||
103 | sleep(15); | |
104 | ||
105 | get_monotonic_and_raw(&mon_end, &raw_end); | |
106 | ||
107 | delta1 = diff_timespec(mon_start, mon_end); | |
108 | delta2 = diff_timespec(raw_start, raw_end); | |
109 | ||
110 | eppm = (delta1*MILLION)/delta2 - MILLION; | |
111 | ||
112 | return eppm; | |
113 | } | |
114 | ||
115 | int check_tick_adj(long tickval) | |
116 | { | |
117 | long long eppm, ppm; | |
118 | struct timex tx1; | |
119 | ||
120 | tx1.modes = ADJ_TICK; | |
121 | tx1.modes |= ADJ_OFFSET; | |
122 | tx1.modes |= ADJ_FREQUENCY; | |
123 | tx1.modes |= ADJ_STATUS; | |
124 | ||
125 | tx1.status = STA_PLL; | |
126 | tx1.offset = 0; | |
127 | tx1.freq = 0; | |
128 | tx1.tick = tickval; | |
129 | ||
130 | adjtimex(&tx1); | |
131 | ||
132 | sleep(1); | |
133 | ||
134 | ppm = ((long long)tickval * MILLION)/systick - MILLION; | |
135 | printf("Estimating tick (act: %ld usec, %lld ppm): ", tickval, ppm); | |
136 | ||
137 | eppm = get_ppm_drift(); | |
138 | printf("%lld usec, %lld ppm", systick + (systick * eppm / MILLION), eppm); | |
139 | ||
140 | tx1.modes = 0; | |
141 | adjtimex(&tx1); | |
142 | ||
143 | if (tx1.offset || tx1.freq || tx1.tick != tickval) { | |
144 | printf(" [ERROR]\n"); | |
145 | printf("\tUnexpected adjtimex return values, make sure ntpd is not running.\n"); | |
146 | return -1; | |
147 | } | |
148 | ||
149 | /* | |
150 | * Here we use 100ppm difference as an error bound. | |
151 | * We likely should see better, but some coarse clocksources | |
152 | * cannot match the HZ tick size accurately, so we have a | |
153 | * internal correction factor that doesn't scale exactly | |
154 | * with the adjustment, resulting in > 10ppm error during | |
155 | * a 10% adjustment. 100ppm also gives us more breathing | |
156 | * room for interruptions during the measurement. | |
157 | */ | |
158 | if (llabs(eppm - ppm) > 100) { | |
159 | printf(" [FAILED]\n"); | |
160 | return -1; | |
161 | } | |
162 | printf(" [OK]\n"); | |
163 | ||
164 | return 0; | |
165 | } | |
166 | ||
167 | int main(int argv, char **argc) | |
168 | { | |
169 | struct timespec raw; | |
170 | long tick, max, interval, err; | |
171 | struct timex tx1; | |
172 | ||
173 | err = 0; | |
174 | setbuf(stdout, NULL); | |
175 | ||
176 | if (clock_gettime(CLOCK_MONOTONIC_RAW, &raw)) { | |
177 | printf("ERR: NO CLOCK_MONOTONIC_RAW\n"); | |
178 | return -1; | |
179 | } | |
180 | ||
181 | printf("Each iteration takes about 15 seconds\n"); | |
182 | ||
183 | systick = sysconf(_SC_CLK_TCK); | |
184 | systick = USEC_PER_SEC/sysconf(_SC_CLK_TCK); | |
185 | max = systick/10; /* +/- 10% */ | |
186 | interval = max/4; /* in 4 steps each side */ | |
187 | ||
188 | for (tick = (systick - max); tick < (systick + max); tick += interval) { | |
189 | if (check_tick_adj(tick)) { | |
190 | err = 1; | |
191 | break; | |
192 | } | |
193 | } | |
194 | ||
195 | /* Reset things to zero */ | |
196 | tx1.modes = ADJ_TICK; | |
197 | tx1.modes |= ADJ_OFFSET; | |
198 | tx1.modes |= ADJ_FREQUENCY; | |
199 | ||
200 | tx1.offset = 0; | |
201 | tx1.freq = 0; | |
202 | tx1.tick = systick; | |
203 | ||
204 | adjtimex(&tx1); | |
205 | ||
206 | if (err) | |
207 | return ksft_exit_fail(); | |
208 | ||
209 | return ksft_exit_pass(); | |
210 | } |