1/**
2 * Program to exercise CPU frequency switching via sysfs.
3 * You probably want to turn on userspace switching and disable
4 * powernowd/cpuspeed/powersaved programs.
5 */
6
7/*
8 * Copyright (C) 2003-2006 IBM
9 *
10 * This program is free software; you can redistribute it and/or
11 * modify it under the terms of the GNU General Public License as
12 * published by the Free Software Foundation; either version 2 of the
13 * License, or (at your option) any later version.
14 *
15 * This program is distributed in the hope that it will be useful, but
16 * WITHOUT ANY WARRANTY; without even the implied warranty of
17 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
18 * General Public License for more details.
19 *
20 * You should have received a copy of the GNU General Public License
21 * along with this program; if not, write to the Free Software
22 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
23 * 02111-1307, USA.
24 */
25
26#include <stdio.h>
27#include <unistd.h>
28#include <sys/stat.h>
29#include <sys/types.h>
30#include <fcntl.h>
31#include <stdlib.h>
32
33static unsigned int cpunum = 0;
34
35static int check_writable(const char *fname)
36{
37	int fd;
38
39	fd = open(fname, O_WRONLY);
40	if (fd >= 0)
41		close(fd);
42
43	return fd >= 0;
44}
45
46static int seed_random(void)
47{
48	int fp;
49	long seed;
50
51	fp = open("/dev/urandom", O_RDONLY);
52	if (fp < 0) {
53		perror("/dev/urandom");
54		return 0;
55	}
56
57	if (read(fp, &seed, sizeof(seed)) != sizeof(seed)) {
58		perror("read random seed");
59		return 0;
60	}
61
62	close(fp);
63	srand(seed);
64
65	return 1;
66}
67
68static unsigned int get_randnum(unsigned int max)
69{
70	return (unsigned int)((float)max * (rand() / (RAND_MAX + 1.0)));
71}
72
73static int set_cpuspeed(const char *ctrlfile, unsigned int speed)
74{
75	int fd, x;
76	unsigned int y;
77	char buf[256];
78
79	/* First try to write a new speed. */
80	fd = open(ctrlfile, O_WRONLY);
81	if (fd < 0) {
82		perror(ctrlfile);
83		return 0;
84	}
85
86	printf("CPU %d speed set to %u kHz.\n", cpunum, speed);
87	fflush(stdout);
88
89	x = snprintf(buf, 256, "%u\n", speed);
90	x = write(fd, buf, x);
91
92	if (x == 0) {
93		perror("Setting new speed");
94		close(fd);
95		return 0;
96	}
97	close(fd);
98
99	/* Sleep for a while */
100	usleep(500000);
101
102	/* Now try to read the speed */
103	fd = open(ctrlfile, O_RDONLY);
104	if (fd < 0) {
105		perror(ctrlfile);
106		return 0;
107	}
108
109	x = read(fd, buf, 256);
110	if (x == 0) {
111		perror("Reading speed");
112		close(fd);
113		return 0;
114	}
115	close(fd);
116
117	y = atoi(buf);
118	if (y != speed) {
119		printf("ERROR: Set CPU %d speed to %u but speed is now %u!\n",
120		       cpunum, speed, y);
121		fflush(stdout);
122		return -1;
123	}
124
125	return 1;
126}
127
128int main(int argc, char *argv[])
129{
130	const char *ctrl;
131	unsigned int rounds;
132	unsigned int *frequencies;
133	int y;
134	unsigned int x, num_freqs;
135	int ret = 0;
136
137	/* Usage: cpufreq control_file rounds [frequencies...] */
138	if (argc < 6) {
139		printf
140		    ("Usage: %s control_file rounds cpunum [frequencies...]\n",
141		     argv[0]);
142		ret = 1;
143		goto out;
144	}
145
146	/* copy command line args */
147	ctrl = argv[1];
148	if (!check_writable(ctrl)) {
149		perror(ctrl);
150		ret = 2;
151		goto out;
152	}
153
154	rounds = atoi(argv[2]);
155	cpunum = atoi(argv[3]);
156
157	num_freqs = argc - 4;
158	frequencies = calloc(num_freqs, sizeof(unsigned int));
159	if (frequencies == NULL) {
160		perror("Error allocating memory");
161		ret = 3;
162		goto out;
163	}
164
165	for (x = 4; x < argc; x++) {
166		frequencies[x - 4] = atoi(argv[x]);
167	}
168
169	/* Now run program. */
170	printf("Running %u loops with these %d frequencies:\n", rounds,
171	       num_freqs);
172	for (x = 0; x < num_freqs; x++) {
173		printf("%u KHz\n", frequencies[x]);
174	}
175
176	fflush(stdout);
177
178	seed_random();
179
180	for (x = rounds; x > 0; x--) {
181		y = get_randnum(num_freqs);
182		y = set_cpuspeed(ctrl, frequencies[y]);
183		if (y != 1) {
184			ret = 4;
185			goto out;
186		}
187	}
188
189out:
190	printf("Exiting with return code %d.\n", ret);
191	fflush(stdout);
192	return ret;
193}
194