summaryrefslogtreecommitdiffstats
path: root/tools/power/cpupower/utils/helpers/sysfs.c
blob: e13ff38329a0e1fb21920233600ef69ab651e926 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
// SPDX-License-Identifier: GPL-2.0-only
/*
 *  (C) 2004-2009  Dominik Brodowski <linux@dominikbrodowski.de>
 *  (C) 2011       Thomas Renninger <trenn@novell.com> Novell Inc.
 */

#include <stdio.h>
#include <errno.h>
#include <stdlib.h>
#include <string.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <unistd.h>

#include "helpers/sysfs.h"

unsigned int sysfs_read_file(const char *path, char *buf, size_t buflen)
{
	int fd;
	ssize_t numread;

	fd = open(path, O_RDONLY);
	if (fd == -1)
		return 0;

	numread = read(fd, buf, buflen - 1);
	if (numread < 1) {
		close(fd);
		return 0;
	}

	buf[numread] = '\0';
	close(fd);

	return (unsigned int) numread;
}

/*
 * Detect whether a CPU is online
 *
 * Returns:
 *     1 -> if CPU is online
 *     0 -> if CPU is offline
 *     negative errno values in error case
 */
int sysfs_is_cpu_online(unsigned int cpu)
{
	char path[SYSFS_PATH_MAX];
	int fd;
	ssize_t numread;
	unsigned long long value;
	char linebuf[MAX_LINE_LEN];
	char *endp;
	struct stat statbuf;

	snprintf(path, sizeof(path), PATH_TO_CPU "cpu%u", cpu);

	if (stat(path, &statbuf) != 0)
		return 0;

	/*
	 * kernel without CONFIG_HOTPLUG_CPU
	 * -> cpuX directory exists, but not cpuX/online file
	 */
	snprintf(path, sizeof(path), PATH_TO_CPU "cpu%u/online", cpu);
	if (stat(path, &statbuf) != 0)
		return 1;

	fd = open(path, O_RDONLY);
	if (fd == -1)
		return -errno;

	numread = read(fd, linebuf, MAX_LINE_LEN - 1);
	if (numread < 1) {
		close(fd);
		return -EIO;
	}
	linebuf[numread] = '\0';
	close(fd);

	value = strtoull(linebuf, &endp, 0);
	if (value > 1)
		return -EINVAL;

	return value;
}

/* CPUidle idlestate specific /sys/devices/system/cpu/cpuX/cpuidle/ access */


/* CPUidle idlestate specific /sys/devices/system/cpu/cpuX/cpuidle/ access */

/*
 * helper function to check whether a file under "../cpuX/cpuidle/stateX/" dir
 * exists.
 * For example the functionality to disable c-states was introduced in later
 * kernel versions, this function can be used to explicitly check for this
 * feature.
 *
 * returns 1 if the file exists, 0 otherwise.
 */
unsigned int sysfs_idlestate_file_exists(unsigned int cpu,
					 unsigned int idlestate,
					 const char *fname)
{
	char path[SYSFS_PATH_MAX];
	struct stat statbuf;


	snprintf(path, sizeof(path), PATH_TO_CPU "cpu%u/cpuidle/state%u/%s",
		 cpu, idlestate, fname);
	if (stat(path, &statbuf) != 0)
		return 0;
	return 1;
}

/*
 * helper function to read file from /sys into given buffer
 * fname is a relative path under "cpuX/cpuidle/stateX/" dir
 * cstates starting with 0, C0 is not counted as cstate.
 * This means if you want C1 info, pass 0 as idlestate param
 */
unsigned int sysfs_idlestate_read_file(unsigned int cpu, unsigned int idlestate,
			     const char *fname, char *buf, size_t buflen)
{
	char path[SYSFS_PATH_MAX];
	int fd;
	ssize_t numread;

	snprintf(path, sizeof(path), PATH_TO_CPU "cpu%u/cpuidle/state%u/%s",
		 cpu, idlestate, fname);

	fd = open(path, O_RDONLY);
	if (fd == -1)
		return 0;

	numread = read(fd, buf, buflen - 1);
	if (numread < 1) {
		close(fd);
		return 0;
	}

	buf[numread] = '\0';
	close(fd);

	return (unsigned int) numread;
}

/* 
 * helper function to write a new value to a /sys file
 * fname is a relative path under "../cpuX/cpuidle/cstateY/" dir
 *
 * Returns the number of bytes written or 0 on error
 */
static
unsigned int sysfs_idlestate_write_file(unsigned int cpu,
					unsigned int idlestate,
					const char *fname,
					const char *value, size_t len)
{
	char path[SYSFS_PATH_MAX];
	int fd;
	ssize_t numwrite;

	snprintf(path, sizeof(path), PATH_TO_CPU "cpu%u/cpuidle/state%u/%s",
		 cpu, idlestate, fname);

	fd = open(path, O_WRONLY);
	if (fd == -1)
		return 0;

	numwrite = write(fd, value, len);
	if (numwrite < 1) {
		close(fd);
		return 0;
	}

	close(fd);

	return (unsigned int) numwrite;
}

/* read access to files which contain one numeric value */

enum idlestate_value {
	IDLESTATE_USAGE,
	IDLESTATE_POWER,
	IDLESTATE_LATENCY,
	IDLESTATE_TIME,
	IDLESTATE_DISABLE,
	MAX_IDLESTATE_VALUE_FILES
};

static const char *idlestate_value_files[MAX_IDLESTATE_VALUE_FILES] = {
	[IDLESTATE_USAGE] = "usage",
	[IDLESTATE_POWER] = "power",
	[IDLESTATE_LATENCY] = "latency",
	[IDLESTATE_TIME]  = "time",
	[IDLESTATE_DISABLE]  = "disable",
};

static unsigned long long sysfs_idlestate_get_one_value(unsigned int cpu,
						     unsigned int idlestate,
						     enum idlestate_value which)
{
	unsigned long long value;
	unsigned int len;
	char linebuf[MAX_LINE_LEN];
	char *endp;

	if (which >= MAX_IDLESTATE_VALUE_FILES)
		return 0;

	len = sysfs_idlestate_read_file(cpu, idlestate,
					idlestate_value_files[which],
					linebuf, sizeof(linebuf));
	if (len == 0)
		return 0;

	value = strtoull(linebuf, &endp, 0);

	if (endp == linebuf || errno == ERANGE)
		return 0;

	return value;
}

/* read access to files which contain one string */

enum idlestate_string {
	IDLESTATE_DESC,
	IDLESTATE_NAME,
	MAX_IDLESTATE_STRING_FILES
};

static const char *idlestate_string_files[MAX_IDLESTATE_STRING_FILES] = {
	[IDLESTATE_DESC] = "desc",
	[IDLESTATE_NAME] = "name",
};


static char *sysfs_idlestate_get_one_string(unsigned int cpu,
					unsigned int idlestate,
					enum idlestate_string which)
{
	char linebuf[MAX_LINE_LEN];
	char *result;
	unsigned int len;

	if (which >= MAX_IDLESTATE_STRING_FILES)
		return NULL;

	len = sysfs_idlestate_read_file(cpu, idlestate,
					idlestate_string_files[which],
					linebuf, sizeof(linebuf));
	if (len == 0)
		return NULL;

	result = strdup(linebuf);
	if (result == NULL)
		return NULL;

	if (result[strlen(result) - 1] == '\n')
		result[strlen(result) - 1] = '\0';

	return result;
}

/*
 * Returns:
 *    1  if disabled
 *    0  if enabled
 *    -1 if idlestate is not available
 *    -2 if disabling is not supported by the kernel
 */
int sysfs_is_idlestate_disabled(unsigned int cpu,
				unsigned int idlestate)
{
	if (sysfs_get_idlestate_count(cpu) <= idlestate)
		return -1;

	if (!sysfs_idlestate_file_exists(cpu, idlestate,
				 idlestate_value_files[IDLESTATE_DISABLE]))
		return -2;
	return sysfs_idlestate_get_one_value(cpu, idlestate, IDLESTATE_DISABLE);
}

/*
 * Pass 1 as last argument to disable or 0 to enable the state
 * Returns:
 *    0  on success
 *    negative values on error, for example:
 *      -1 if idlestate is not available
 *      -2 if disabling is not supported by the kernel
 *      -3 No write access to disable/enable C-states
 */
int sysfs_idlestate_disable(unsigned int cpu,
			    unsigned int idlestate,
			    unsigned int disable)
{
	char value[SYSFS_PATH_MAX];
	int bytes_written;

	if (sysfs_get_idlestate_count(cpu) <= idlestate)
		return -1;

	if (!sysfs_idlestate_file_exists(cpu, idlestate,
				 idlestate_value_files[IDLESTATE_DISABLE]))
		return -2;

	snprintf(value, SYSFS_PATH_MAX, "%u", disable);

	bytes_written = sysfs_idlestate_write_file(cpu, idlestate, "disable",
						   value, sizeof(disable));
	if (bytes_written)
		return 0;
	return -3;
}

unsigned long sysfs_get_idlestate_latency(unsigned int cpu,
					  unsigned int idlestate)
{
	return sysfs_idlestate_get_one_value(cpu, idlestate, IDLESTATE_LATENCY);
}

unsigned long sysfs_get_idlestate_usage(unsigned int cpu,
					unsigned int idlestate)
{
	return sysfs_idlestate_get_one_value(cpu, idlestate, IDLESTATE_USAGE);
}

unsigned long long sysfs_get_idlestate_time(unsigned int cpu,
					unsigned int idlestate)
{
	return sysfs_idlestate_get_one_value(cpu, idlestate, IDLESTATE_TIME);
}

char *sysfs_get_idlestate_name(unsigned int cpu, unsigned int idlestate)
{
	return sysfs_idlestate_get_one_string(cpu, idlestate, IDLESTATE_NAME);
}

char *sysfs_get_idlestate_desc(unsigned int cpu, unsigned int idlestate)
{
	return sysfs_idlestate_get_one_string(cpu, idlestate, IDLESTATE_DESC);
}

/*
 * Returns number of supported C-states of CPU core cpu
 * Negativ in error case
 * Zero if cpuidle does not export any C-states
 */
unsigned int sysfs_get_idlestate_count(unsigned int cpu)
{
	char file[SYSFS_PATH_MAX];
	struct stat statbuf;
	int idlestates = 1;


	snprintf(file, SYSFS_PATH_MAX, PATH_TO_CPU "cpuidle");
	if (stat(file, &statbuf) != 0 || !S_ISDIR(statbuf.st_mode))
		return 0;

	snprintf(file, SYSFS_PATH_MAX, PATH_TO_CPU "cpu%u/cpuidle/state0", cpu);
	if (stat(file, &statbuf) != 0 || !S_ISDIR(statbuf.st_mode))
		return 0;

	while (stat(file, &statbuf) == 0 && S_ISDIR(statbuf.st_mode)) {
		snprintf(file, SYSFS_PATH_MAX, PATH_TO_CPU
			 "cpu%u/cpuidle/state%d", cpu, idlestates);
		idlestates++;
	}
	idlestates--;
	return idlestates;
}

/* CPUidle general /sys/devices/system/cpu/cpuidle/ sysfs access ********/

/*
 * helper function to read file from /sys into given buffer
 * fname is a relative path under "cpu/cpuidle/" dir
 */
static unsigned int sysfs_cpuidle_read_file(const char *fname, char *buf,
					    size_t buflen)
{
	char path[SYSFS_PATH_MAX];

	snprintf(path, sizeof(path), PATH_TO_CPU "cpuidle/%s", fname);

	return sysfs_read_file(path, buf, buflen);
}



/* read access to files which contain one string */

enum cpuidle_string {
	CPUIDLE_GOVERNOR,
	CPUIDLE_GOVERNOR_RO,
	CPUIDLE_DRIVER,
	MAX_CPUIDLE_STRING_FILES
};

static const char *cpuidle_string_files[MAX_CPUIDLE_STRING_FILES] = {
	[CPUIDLE_GOVERNOR]	= "current_governor",
	[CPUIDLE_GOVERNOR_RO]	= "current_governor_ro",
	[CPUIDLE_DRIVER]	= "current_driver",
};


static char *sysfs_cpuidle_get_one_string(enum cpuidle_string which)
{
	char linebuf[MAX_LINE_LEN];
	char *result;
	unsigned int len;

	if (which >= MAX_CPUIDLE_STRING_FILES)
		return NULL;

	len = sysfs_cpuidle_read_file(cpuidle_string_files[which],
				linebuf, sizeof(linebuf));
	if (len == 0)
		return NULL;

	result = strdup(linebuf);
	if (result == NULL)
		return NULL;

	if (result[strlen(result) - 1] == '\n')
		result[strlen(result) - 1] = '\0';

	return result;
}

char *sysfs_get_cpuidle_governor(void)
{
	char *tmp = sysfs_cpuidle_get_one_string(CPUIDLE_GOVERNOR_RO);
	if (!tmp)
		return sysfs_cpuidle_get_one_string(CPUIDLE_GOVERNOR);
	else
		return tmp;
}

char *sysfs_get_cpuidle_driver(void)
{
	return sysfs_cpuidle_get_one_string(CPUIDLE_DRIVER);
}
/* CPUidle idlestate specific /sys/devices/system/cpu/cpuX/cpuidle/ access */

/*
 * Get sched_mc or sched_smt settings
 * Pass "mc" or "smt" as argument
 *
 * Returns negative value on failure
 */
int sysfs_get_sched(const char *smt_mc)
{
	return -ENODEV;
}

/*
 * Get sched_mc or sched_smt settings
 * Pass "mc" or "smt" as argument
 *
 * Returns negative value on failure
 */
int sysfs_set_sched(const char *smt_mc, int val)
{
	return -ENODEV;
}