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
 26#include "../kselftest.h"
 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
 35long systick;
 36
 37long long llabs(long long val)
 38{
 39	if (val < 0)
 40		val = -val;
 41	return val;
 42}
 43
 44unsigned long long ts_to_nsec(struct timespec ts)
 45{
 46	return ts.tv_sec * NSEC_PER_SEC + ts.tv_nsec;
 47}
 48
 49struct 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
 59long 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
 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	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
 96long 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
115int 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	fflush(stdout);
140
141	tx1.modes = 0;
142	adjtimex(&tx1);
143
144	if (tx1.offset || tx1.freq || tx1.tick != tickval) {
145		printf("	[ERROR]\n");
146		printf("\tUnexpected adjtimex return values, make sure ntpd is not running.\n");
147		return -1;
148	}
149
150	/*
151	 * Here we use 100ppm difference as an error bound.
152	 * We likely should see better, but some coarse clocksources
153	 * cannot match the HZ tick size accurately, so we have a
154	 * internal correction factor that doesn't scale exactly
155	 * with the adjustment, resulting in > 10ppm error during
156	 * a 10% adjustment. 100ppm also gives us more breathing
157	 * room for interruptions during the measurement.
158	 */
159	if (llabs(eppm - ppm) > 100) {
160		printf("	[FAILED]\n");
161		return -1;
162	}
163	printf("	[OK]\n");
164
165	return  0;
166}
167
168int main(int argc, char **argv)
169{
170	struct timespec raw;
171	long tick, max, interval, err;
172	struct timex tx1;
173
174	err = 0;
175	setbuf(stdout, NULL);
176
177	if (clock_gettime(CLOCK_MONOTONIC_RAW, &raw)) {
178		printf("ERR: NO CLOCK_MONOTONIC_RAW\n");
179		return -1;
180	}
181
182	printf("Each iteration takes about 15 seconds\n");
183
184	systick = sysconf(_SC_CLK_TCK);
185	systick = USEC_PER_SEC/sysconf(_SC_CLK_TCK);
186	max = systick/10; /* +/- 10% */
187	interval = max/4; /* in 4 steps each side */
188
189	for (tick = (systick - max); tick < (systick + max); tick += interval) {
190		if (check_tick_adj(tick)) {
191			err = 1;
192			break;
193		}
194	}
195
196	/* Reset things to zero */
197	tx1.modes	 = ADJ_TICK;
198	tx1.modes	|= ADJ_OFFSET;
199	tx1.modes	|= ADJ_FREQUENCY;
200
201	tx1.offset	 = 0;
202	tx1.freq	 = 0;
203	tx1.tick	 = systick;
204
205	adjtimex(&tx1);
206
207	if (err)
208		return ksft_exit_fail();
209
210	return ksft_exit_pass();
211}