1/* CLOCK_MONOTONIC vs CLOCK_MONOTONIC_RAW skew test
2 *		by: john stultz (johnstul@us.ibm.com)
3 *		    John Stultz <john.stultz@linaro.org>
4 *		(C) Copyright IBM 2012
5 *		(C) Copyright Linaro Limited 2015
6 *		Licensed under the GPLv2
7 *
8 *  To build:
9 *	$ gcc raw_skew.c -o raw_skew -lrt
10 *
11 *   This program is free software: you can redistribute it and/or modify
12 *   it under the terms of the GNU General Public License as published by
13 *   the Free Software Foundation, either version 2 of the License, or
14 *   (at your option) any later version.
15 *
16 *   This program is distributed in the hope that it will be useful,
17 *   but WITHOUT ANY WARRANTY; without even the implied warranty of
18 *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
19 *   GNU General Public License for more details.
20 */
21
22#include <stdio.h>
23#include <unistd.h>
24#include <stdlib.h>
25#include <sys/time.h>
26#include <sys/timex.h>
27#include <time.h>
28#include "../kselftest.h"
29
30#define CLOCK_MONOTONIC_RAW		4
31#define NSEC_PER_SEC 1000000000LL
32
33#define shift_right(x, s) ({		\
34	__typeof__(x) __x = (x);	\
35	__typeof__(s) __s = (s);	\
36	__x < 0 ? -(-__x >> __s) : __x >> __s; \
37})
38
39long long llabs(long long val)
40{
41	if (val < 0)
42		val = -val;
43	return val;
44}
45
46unsigned long long ts_to_nsec(struct timespec ts)
47{
48	return ts.tv_sec * NSEC_PER_SEC + ts.tv_nsec;
49}
50
51struct timespec nsec_to_ts(long long ns)
52{
53	struct timespec ts;
54
55	ts.tv_sec = ns/NSEC_PER_SEC;
56	ts.tv_nsec = ns%NSEC_PER_SEC;
57	return ts;
58}
59
60long long diff_timespec(struct timespec start, struct timespec end)
61{
62	long long start_ns, end_ns;
63
64	start_ns = ts_to_nsec(start);
65	end_ns = ts_to_nsec(end);
66	return end_ns - start_ns;
67}
68
69void 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	for (i = 0; i < 3; i++) {
76		long long newdiff;
77
78		clock_gettime(CLOCK_MONOTONIC, &start);
79		clock_gettime(CLOCK_MONOTONIC_RAW, &mid);
80		clock_gettime(CLOCK_MONOTONIC, &end);
81
82		newdiff = diff_timespec(start, end);
83		if (diff == 0 || newdiff < diff) {
84			diff = newdiff;
85			*raw = mid;
86			tmp = (ts_to_nsec(start) + ts_to_nsec(end))/2;
87			*mon = nsec_to_ts(tmp);
88		}
89	}
90}
91
92int main(int argc, char **argv)
93{
94	struct timespec mon, raw, start, end;
95	long long delta1, delta2, interval, eppm, ppm;
96	struct timex tx1, tx2;
97
98	setbuf(stdout, NULL);
99
100	if (clock_gettime(CLOCK_MONOTONIC_RAW, &raw)) {
101		printf("ERR: NO CLOCK_MONOTONIC_RAW\n");
102		return -1;
103	}
104
105	tx1.modes = 0;
106	adjtimex(&tx1);
107	get_monotonic_and_raw(&mon, &raw);
108	start = mon;
109	delta1 = diff_timespec(mon, raw);
110
111	if (tx1.offset)
112		printf("WARNING: ADJ_OFFSET in progress, this will cause inaccurate results\n");
113
114	printf("Estimating clock drift: ");
115	fflush(stdout);
116	sleep(120);
117
118	get_monotonic_and_raw(&mon, &raw);
119	end = mon;
120	tx2.modes = 0;
121	adjtimex(&tx2);
122	delta2 = diff_timespec(mon, raw);
123
124	interval = diff_timespec(start, end);
125
126	/* calculate measured ppm between MONOTONIC and MONOTONIC_RAW */
127	eppm = ((delta2-delta1)*NSEC_PER_SEC)/interval;
128	eppm = -eppm;
129	printf("%lld.%i(est)", eppm/1000, abs((int)(eppm%1000)));
130
131	/* Avg the two actual freq samples adjtimex gave us */
132	ppm = (long long)(tx1.freq + tx2.freq) * 1000 / 2;
133	ppm = shift_right(ppm, 16);
134	printf(" %lld.%i(act)", ppm/1000, abs((int)(ppm%1000)));
135
136	if (llabs(eppm - ppm) > 1000) {
137		if (tx1.offset || tx2.offset ||
138		    tx1.freq != tx2.freq || tx1.tick != tx2.tick) {
139			printf("	[SKIP]\n");
140			return ksft_exit_skip("The clock was adjusted externally. Shutdown NTPd or other time sync daemons\n");
141		}
142		printf("	[FAILED]\n");
143		return ksft_exit_fail();
144	}
145	printf("	[OK]\n");
146	return  ksft_exit_pass();
147}
148