2 * (C) 2004-2009 Dominik Brodowski <linux@dominikbrodowski.de>
3 * (C) 2011 Thomas Renninger <trenn@novell.com> Novell Inc.
5 * Licensed under the terms of the GNU GPL License version 2.
12 #include <sys/types.h>
17 #include "helpers/sysfs.h"
19 unsigned int sysfs_read_file(const char *path, char *buf, size_t buflen)
24 fd = open(path, O_RDONLY);
28 numread = read(fd, buf, buflen - 1);
37 return (unsigned int) numread;
41 * Detect whether a CPU is online
44 * 1 -> if CPU is online
45 * 0 -> if CPU is offline
46 * negative errno values in error case
48 int sysfs_is_cpu_online(unsigned int cpu)
50 char path[SYSFS_PATH_MAX];
53 unsigned long long value;
54 char linebuf[MAX_LINE_LEN];
58 snprintf(path, sizeof(path), PATH_TO_CPU "cpu%u", cpu);
60 if (stat(path, &statbuf) != 0)
64 * kernel without CONFIG_HOTPLUG_CPU
65 * -> cpuX directory exists, but not cpuX/online file
67 snprintf(path, sizeof(path), PATH_TO_CPU "cpu%u/online", cpu);
68 if (stat(path, &statbuf) != 0)
71 fd = open(path, O_RDONLY);
75 numread = read(fd, linebuf, MAX_LINE_LEN - 1);
80 linebuf[numread] = '\0';
83 value = strtoull(linebuf, &endp, 0);
90 /* CPUidle idlestate specific /sys/devices/system/cpu/cpuX/cpuidle/ access */
93 /* CPUidle idlestate specific /sys/devices/system/cpu/cpuX/cpuidle/ access */
96 * helper function to check whether a file under "../cpuX/cpuidle/stateX/" dir
98 * For example the functionality to disable c-states was introduced in later
99 * kernel versions, this function can be used to explicitly check for this
102 * returns 1 if the file exists, 0 otherwise.
104 unsigned int sysfs_idlestate_file_exists(unsigned int cpu,
105 unsigned int idlestate,
108 char path[SYSFS_PATH_MAX];
112 snprintf(path, sizeof(path), PATH_TO_CPU "cpu%u/cpuidle/state%u/%s",
113 cpu, idlestate, fname);
114 if (stat(path, &statbuf) != 0)
120 * helper function to read file from /sys into given buffer
121 * fname is a relative path under "cpuX/cpuidle/stateX/" dir
122 * cstates starting with 0, C0 is not counted as cstate.
123 * This means if you want C1 info, pass 0 as idlestate param
125 unsigned int sysfs_idlestate_read_file(unsigned int cpu, unsigned int idlestate,
126 const char *fname, char *buf, size_t buflen)
128 char path[SYSFS_PATH_MAX];
132 snprintf(path, sizeof(path), PATH_TO_CPU "cpu%u/cpuidle/state%u/%s",
133 cpu, idlestate, fname);
135 fd = open(path, O_RDONLY);
139 numread = read(fd, buf, buflen - 1);
148 return (unsigned int) numread;
152 * helper function to write a new value to a /sys file
153 * fname is a relative path under "../cpuX/cpuidle/cstateY/" dir
155 * Returns the number of bytes written or 0 on error
158 unsigned int sysfs_idlestate_write_file(unsigned int cpu,
159 unsigned int idlestate,
161 const char *value, size_t len)
163 char path[SYSFS_PATH_MAX];
167 snprintf(path, sizeof(path), PATH_TO_CPU "cpu%u/cpuidle/state%u/%s",
168 cpu, idlestate, fname);
170 fd = open(path, O_WRONLY);
174 numwrite = write(fd, value, len);
182 return (unsigned int) numwrite;
185 /* read access to files which contain one numeric value */
187 enum idlestate_value {
193 MAX_IDLESTATE_VALUE_FILES
196 static const char *idlestate_value_files[MAX_IDLESTATE_VALUE_FILES] = {
197 [IDLESTATE_USAGE] = "usage",
198 [IDLESTATE_POWER] = "power",
199 [IDLESTATE_LATENCY] = "latency",
200 [IDLESTATE_TIME] = "time",
201 [IDLESTATE_DISABLE] = "disable",
204 static unsigned long long sysfs_idlestate_get_one_value(unsigned int cpu,
205 unsigned int idlestate,
206 enum idlestate_value which)
208 unsigned long long value;
210 char linebuf[MAX_LINE_LEN];
213 if (which >= MAX_IDLESTATE_VALUE_FILES)
216 len = sysfs_idlestate_read_file(cpu, idlestate,
217 idlestate_value_files[which],
218 linebuf, sizeof(linebuf));
222 value = strtoull(linebuf, &endp, 0);
224 if (endp == linebuf || errno == ERANGE)
230 /* read access to files which contain one string */
232 enum idlestate_string {
235 MAX_IDLESTATE_STRING_FILES
238 static const char *idlestate_string_files[MAX_IDLESTATE_STRING_FILES] = {
239 [IDLESTATE_DESC] = "desc",
240 [IDLESTATE_NAME] = "name",
244 static char *sysfs_idlestate_get_one_string(unsigned int cpu,
245 unsigned int idlestate,
246 enum idlestate_string which)
248 char linebuf[MAX_LINE_LEN];
252 if (which >= MAX_IDLESTATE_STRING_FILES)
255 len = sysfs_idlestate_read_file(cpu, idlestate,
256 idlestate_string_files[which],
257 linebuf, sizeof(linebuf));
261 result = strdup(linebuf);
265 if (result[strlen(result) - 1] == '\n')
266 result[strlen(result) - 1] = '\0';
275 * -1 if idlestate is not available
276 * -2 if disabling is not supported by the kernel
278 int sysfs_is_idlestate_disabled(unsigned int cpu,
279 unsigned int idlestate)
281 if (sysfs_get_idlestate_count(cpu) <= idlestate)
284 if (!sysfs_idlestate_file_exists(cpu, idlestate,
285 idlestate_value_files[IDLESTATE_DISABLE]))
287 return sysfs_idlestate_get_one_value(cpu, idlestate, IDLESTATE_DISABLE);
291 * Pass 1 as last argument to disable or 0 to enable the state
294 * negative values on error, for example:
295 * -1 if idlestate is not available
296 * -2 if disabling is not supported by the kernel
297 * -3 No write access to disable/enable C-states
299 int sysfs_idlestate_disable(unsigned int cpu,
300 unsigned int idlestate,
301 unsigned int disable)
303 char value[SYSFS_PATH_MAX];
306 if (sysfs_get_idlestate_count(cpu) <= idlestate)
309 if (!sysfs_idlestate_file_exists(cpu, idlestate,
310 idlestate_value_files[IDLESTATE_DISABLE]))
313 snprintf(value, SYSFS_PATH_MAX, "%u", disable);
315 bytes_written = sysfs_idlestate_write_file(cpu, idlestate, "disable",
316 value, sizeof(disable));
322 unsigned long sysfs_get_idlestate_latency(unsigned int cpu,
323 unsigned int idlestate)
325 return sysfs_idlestate_get_one_value(cpu, idlestate, IDLESTATE_LATENCY);
328 unsigned long sysfs_get_idlestate_usage(unsigned int cpu,
329 unsigned int idlestate)
331 return sysfs_idlestate_get_one_value(cpu, idlestate, IDLESTATE_USAGE);
334 unsigned long long sysfs_get_idlestate_time(unsigned int cpu,
335 unsigned int idlestate)
337 return sysfs_idlestate_get_one_value(cpu, idlestate, IDLESTATE_TIME);
340 char *sysfs_get_idlestate_name(unsigned int cpu, unsigned int idlestate)
342 return sysfs_idlestate_get_one_string(cpu, idlestate, IDLESTATE_NAME);
345 char *sysfs_get_idlestate_desc(unsigned int cpu, unsigned int idlestate)
347 return sysfs_idlestate_get_one_string(cpu, idlestate, IDLESTATE_DESC);
351 * Returns number of supported C-states of CPU core cpu
352 * Negativ in error case
353 * Zero if cpuidle does not export any C-states
355 unsigned int sysfs_get_idlestate_count(unsigned int cpu)
357 char file[SYSFS_PATH_MAX];
362 snprintf(file, SYSFS_PATH_MAX, PATH_TO_CPU "cpuidle");
363 if (stat(file, &statbuf) != 0 || !S_ISDIR(statbuf.st_mode))
366 snprintf(file, SYSFS_PATH_MAX, PATH_TO_CPU "cpu%u/cpuidle/state0", cpu);
367 if (stat(file, &statbuf) != 0 || !S_ISDIR(statbuf.st_mode))
370 while (stat(file, &statbuf) == 0 && S_ISDIR(statbuf.st_mode)) {
371 snprintf(file, SYSFS_PATH_MAX, PATH_TO_CPU
372 "cpu%u/cpuidle/state%d", cpu, idlestates);
379 /* CPUidle general /sys/devices/system/cpu/cpuidle/ sysfs access ********/
382 * helper function to read file from /sys into given buffer
383 * fname is a relative path under "cpu/cpuidle/" dir
385 static unsigned int sysfs_cpuidle_read_file(const char *fname, char *buf,
388 char path[SYSFS_PATH_MAX];
390 snprintf(path, sizeof(path), PATH_TO_CPU "cpuidle/%s", fname);
392 return sysfs_read_file(path, buf, buflen);
397 /* read access to files which contain one string */
399 enum cpuidle_string {
403 MAX_CPUIDLE_STRING_FILES
406 static const char *cpuidle_string_files[MAX_CPUIDLE_STRING_FILES] = {
407 [CPUIDLE_GOVERNOR] = "current_governor",
408 [CPUIDLE_GOVERNOR_RO] = "current_governor_ro",
409 [CPUIDLE_DRIVER] = "current_driver",
413 static char *sysfs_cpuidle_get_one_string(enum cpuidle_string which)
415 char linebuf[MAX_LINE_LEN];
419 if (which >= MAX_CPUIDLE_STRING_FILES)
422 len = sysfs_cpuidle_read_file(cpuidle_string_files[which],
423 linebuf, sizeof(linebuf));
427 result = strdup(linebuf);
431 if (result[strlen(result) - 1] == '\n')
432 result[strlen(result) - 1] = '\0';
437 char *sysfs_get_cpuidle_governor(void)
439 char *tmp = sysfs_cpuidle_get_one_string(CPUIDLE_GOVERNOR_RO);
441 return sysfs_cpuidle_get_one_string(CPUIDLE_GOVERNOR);
446 char *sysfs_get_cpuidle_driver(void)
448 return sysfs_cpuidle_get_one_string(CPUIDLE_DRIVER);
450 /* CPUidle idlestate specific /sys/devices/system/cpu/cpuX/cpuidle/ access */
453 * Get sched_mc or sched_smt settings
454 * Pass "mc" or "smt" as argument
456 * Returns negative value on failure
458 int sysfs_get_sched(const char *smt_mc)
464 * Get sched_mc or sched_smt settings
465 * Pass "mc" or "smt" as argument
467 * Returns negative value on failure
469 int sysfs_set_sched(const char *smt_mc, int val)