1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 * (C) 2004-2009 Dominik Brodowski <linux@dominikbrodowski.de>
4 * (C) 2011 Thomas Renninger <trenn@novell.com> Novell Inc.
5 */
6
7 #include <stdio.h>
8 #include <errno.h>
9 #include <stdlib.h>
10 #include <string.h>
11 #include <sys/types.h>
12 #include <sys/stat.h>
13 #include <fcntl.h>
14 #include <unistd.h>
15
16 #include "cpuidle.h"
17 #include "cpupower_intern.h"
18
19 /*
20 * helper function to check whether a file under "../cpuX/cpuidle/stateX/" dir
21 * exists.
22 * For example the functionality to disable c-states was introduced in later
23 * kernel versions, this function can be used to explicitly check for this
24 * feature.
25 *
26 * returns 1 if the file exists, 0 otherwise.
27 */
28 static
cpuidle_state_file_exists(unsigned int cpu,unsigned int idlestate,const char * fname)29 unsigned int cpuidle_state_file_exists(unsigned int cpu,
30 unsigned int idlestate,
31 const char *fname)
32 {
33 char path[SYSFS_PATH_MAX];
34 struct stat statbuf;
35
36
37 snprintf(path, sizeof(path), PATH_TO_CPU "cpu%u/cpuidle/state%u/%s",
38 cpu, idlestate, fname);
39 if (stat(path, &statbuf) != 0)
40 return 0;
41 return 1;
42 }
43
44 /*
45 * helper function to read file from /sys into given buffer
46 * fname is a relative path under "cpuX/cpuidle/stateX/" dir
47 * cstates starting with 0, C0 is not counted as cstate.
48 * This means if you want C1 info, pass 0 as idlestate param
49 */
50 static
cpuidle_state_read_file(unsigned int cpu,unsigned int idlestate,const char * fname,char * buf,size_t buflen)51 unsigned int cpuidle_state_read_file(unsigned int cpu,
52 unsigned int idlestate,
53 const char *fname, char *buf,
54 size_t buflen)
55 {
56 char path[SYSFS_PATH_MAX];
57 int fd;
58 ssize_t numread;
59
60 snprintf(path, sizeof(path), PATH_TO_CPU "cpu%u/cpuidle/state%u/%s",
61 cpu, idlestate, fname);
62
63 fd = open(path, O_RDONLY);
64 if (fd == -1)
65 return 0;
66
67 numread = read(fd, buf, buflen - 1);
68 if (numread < 1) {
69 close(fd);
70 return 0;
71 }
72
73 buf[numread] = '\0';
74 close(fd);
75
76 return (unsigned int) numread;
77 }
78
79 /*
80 * helper function to write a new value to a /sys file
81 * fname is a relative path under "../cpuX/cpuidle/cstateY/" dir
82 *
83 * Returns the number of bytes written or 0 on error
84 */
85 static
cpuidle_state_write_file(unsigned int cpu,unsigned int idlestate,const char * fname,const char * value,size_t len)86 unsigned int cpuidle_state_write_file(unsigned int cpu,
87 unsigned int idlestate,
88 const char *fname,
89 const char *value, size_t len)
90 {
91 char path[SYSFS_PATH_MAX];
92 int fd;
93 ssize_t numwrite;
94
95 snprintf(path, sizeof(path), PATH_TO_CPU "cpu%u/cpuidle/state%u/%s",
96 cpu, idlestate, fname);
97
98 fd = open(path, O_WRONLY);
99 if (fd == -1)
100 return 0;
101
102 numwrite = write(fd, value, len);
103 if (numwrite < 1) {
104 close(fd);
105 return 0;
106 }
107
108 close(fd);
109
110 return (unsigned int) numwrite;
111 }
112
113 /* read access to files which contain one numeric value */
114
115 enum idlestate_value {
116 IDLESTATE_USAGE,
117 IDLESTATE_POWER,
118 IDLESTATE_LATENCY,
119 IDLESTATE_RESIDENCY,
120 IDLESTATE_TIME,
121 IDLESTATE_DISABLE,
122 MAX_IDLESTATE_VALUE_FILES
123 };
124
125 static const char *idlestate_value_files[MAX_IDLESTATE_VALUE_FILES] = {
126 [IDLESTATE_USAGE] = "usage",
127 [IDLESTATE_POWER] = "power",
128 [IDLESTATE_LATENCY] = "latency",
129 [IDLESTATE_RESIDENCY] = "residency",
130 [IDLESTATE_TIME] = "time",
131 [IDLESTATE_DISABLE] = "disable",
132 };
133
134 static
cpuidle_state_get_one_value(unsigned int cpu,unsigned int idlestate,enum idlestate_value which)135 unsigned long long cpuidle_state_get_one_value(unsigned int cpu,
136 unsigned int idlestate,
137 enum idlestate_value which)
138 {
139 unsigned long long value;
140 unsigned int len;
141 char linebuf[MAX_LINE_LEN];
142 char *endp;
143
144 if (which >= MAX_IDLESTATE_VALUE_FILES)
145 return 0;
146
147 len = cpuidle_state_read_file(cpu, idlestate,
148 idlestate_value_files[which],
149 linebuf, sizeof(linebuf));
150 if (len == 0)
151 return 0;
152
153 errno = 0;
154 value = strtoull(linebuf, &endp, 0);
155
156 if (endp == linebuf || errno == ERANGE)
157 return 0;
158
159 return value;
160 }
161
162 /* read access to files which contain one string */
163
164 enum idlestate_string {
165 IDLESTATE_DESC,
166 IDLESTATE_NAME,
167 MAX_IDLESTATE_STRING_FILES
168 };
169
170 static const char *idlestate_string_files[MAX_IDLESTATE_STRING_FILES] = {
171 [IDLESTATE_DESC] = "desc",
172 [IDLESTATE_NAME] = "name",
173 };
174
175
cpuidle_state_get_one_string(unsigned int cpu,unsigned int idlestate,enum idlestate_string which)176 static char *cpuidle_state_get_one_string(unsigned int cpu,
177 unsigned int idlestate,
178 enum idlestate_string which)
179 {
180 char linebuf[MAX_LINE_LEN];
181 char *result;
182 unsigned int len;
183
184 if (which >= MAX_IDLESTATE_STRING_FILES)
185 return NULL;
186
187 len = cpuidle_state_read_file(cpu, idlestate,
188 idlestate_string_files[which],
189 linebuf, sizeof(linebuf));
190 if (len == 0)
191 return NULL;
192
193 result = strdup(linebuf);
194 if (result == NULL)
195 return NULL;
196
197 result[strcspn(result, "\n")] = '\0';
198
199 return result;
200 }
201
202 /*
203 * Returns:
204 * 1 if disabled
205 * 0 if enabled
206 * -1 if idlestate is not available
207 * -2 if disabling is not supported by the kernel
208 */
cpuidle_is_state_disabled(unsigned int cpu,unsigned int idlestate)209 int cpuidle_is_state_disabled(unsigned int cpu,
210 unsigned int idlestate)
211 {
212 if (cpuidle_state_count(cpu) <= idlestate)
213 return -1;
214
215 if (!cpuidle_state_file_exists(cpu, idlestate,
216 idlestate_value_files[IDLESTATE_DISABLE]))
217 return -2;
218 return cpuidle_state_get_one_value(cpu, idlestate, IDLESTATE_DISABLE);
219 }
220
221 /*
222 * Pass 1 as last argument to disable or 0 to enable the state
223 * Returns:
224 * 0 on success
225 * negative values on error, for example:
226 * -1 if idlestate is not available
227 * -2 if disabling is not supported by the kernel
228 * -3 No write access to disable/enable C-states
229 */
cpuidle_state_disable(unsigned int cpu,unsigned int idlestate,unsigned int disable)230 int cpuidle_state_disable(unsigned int cpu,
231 unsigned int idlestate,
232 unsigned int disable)
233 {
234 char value[SYSFS_PATH_MAX];
235 int bytes_written;
236 int len;
237
238 if (cpuidle_state_count(cpu) <= idlestate)
239 return -1;
240
241 if (!cpuidle_state_file_exists(cpu, idlestate,
242 idlestate_value_files[IDLESTATE_DISABLE]))
243 return -2;
244
245 len = snprintf(value, SYSFS_PATH_MAX, "%u", disable);
246
247 bytes_written = cpuidle_state_write_file(cpu, idlestate, "disable",
248 value, len);
249 if (bytes_written)
250 return 0;
251 return -3;
252 }
253
cpuidle_state_latency(unsigned int cpu,unsigned int idlestate)254 unsigned long cpuidle_state_latency(unsigned int cpu,
255 unsigned int idlestate)
256 {
257 return cpuidle_state_get_one_value(cpu, idlestate, IDLESTATE_LATENCY);
258 }
259
cpuidle_state_residency(unsigned int cpu,unsigned int idlestate)260 unsigned long cpuidle_state_residency(unsigned int cpu,
261 unsigned int idlestate)
262 {
263 return cpuidle_state_get_one_value(cpu, idlestate, IDLESTATE_RESIDENCY);
264 }
265
cpuidle_state_usage(unsigned int cpu,unsigned int idlestate)266 unsigned long cpuidle_state_usage(unsigned int cpu,
267 unsigned int idlestate)
268 {
269 return cpuidle_state_get_one_value(cpu, idlestate, IDLESTATE_USAGE);
270 }
271
cpuidle_state_time(unsigned int cpu,unsigned int idlestate)272 unsigned long long cpuidle_state_time(unsigned int cpu,
273 unsigned int idlestate)
274 {
275 return cpuidle_state_get_one_value(cpu, idlestate, IDLESTATE_TIME);
276 }
277
cpuidle_state_name(unsigned int cpu,unsigned int idlestate)278 char *cpuidle_state_name(unsigned int cpu, unsigned int idlestate)
279 {
280 return cpuidle_state_get_one_string(cpu, idlestate, IDLESTATE_NAME);
281 }
282
cpuidle_state_desc(unsigned int cpu,unsigned int idlestate)283 char *cpuidle_state_desc(unsigned int cpu, unsigned int idlestate)
284 {
285 return cpuidle_state_get_one_string(cpu, idlestate, IDLESTATE_DESC);
286 }
287
288 /*
289 * Returns number of supported C-states of CPU core cpu
290 * Negativ in error case
291 * Zero if cpuidle does not export any C-states
292 */
cpuidle_state_count(unsigned int cpu)293 unsigned int cpuidle_state_count(unsigned int cpu)
294 {
295 char file[SYSFS_PATH_MAX];
296 struct stat statbuf;
297 int idlestates = 1;
298
299
300 snprintf(file, SYSFS_PATH_MAX, PATH_TO_CPU "cpuidle");
301 if (stat(file, &statbuf) != 0 || !S_ISDIR(statbuf.st_mode))
302 return 0;
303
304 snprintf(file, SYSFS_PATH_MAX, PATH_TO_CPU "cpu%u/cpuidle/state0", cpu);
305 if (stat(file, &statbuf) != 0 || !S_ISDIR(statbuf.st_mode))
306 return 0;
307
308 while (stat(file, &statbuf) == 0 && S_ISDIR(statbuf.st_mode)) {
309 snprintf(file, SYSFS_PATH_MAX, PATH_TO_CPU
310 "cpu%u/cpuidle/state%d", cpu, idlestates);
311 idlestates++;
312 }
313 idlestates--;
314 return idlestates;
315 }
316
317 /* CPUidle general /sys/devices/system/cpu/cpuidle/ sysfs access ********/
318
319 /*
320 * helper function to read file from /sys into given buffer
321 * fname is a relative path under "cpu/cpuidle/" dir
322 */
sysfs_cpuidle_read_file(const char * fname,char * buf,size_t buflen)323 static unsigned int sysfs_cpuidle_read_file(const char *fname, char *buf,
324 size_t buflen)
325 {
326 char path[SYSFS_PATH_MAX];
327
328 snprintf(path, sizeof(path), PATH_TO_CPU "cpuidle/%s", fname);
329
330 return cpupower_read_sysfs(path, buf, buflen);
331 }
332
333
334
335 /* read access to files which contain one string */
336
337 enum cpuidle_string {
338 CPUIDLE_GOVERNOR,
339 CPUIDLE_GOVERNOR_RO,
340 CPUIDLE_DRIVER,
341 MAX_CPUIDLE_STRING_FILES
342 };
343
344 static const char *cpuidle_string_files[MAX_CPUIDLE_STRING_FILES] = {
345 [CPUIDLE_GOVERNOR] = "current_governor",
346 [CPUIDLE_GOVERNOR_RO] = "current_governor_ro",
347 [CPUIDLE_DRIVER] = "current_driver",
348 };
349
350
sysfs_cpuidle_get_one_string(enum cpuidle_string which)351 static char *sysfs_cpuidle_get_one_string(enum cpuidle_string which)
352 {
353 char linebuf[MAX_LINE_LEN];
354 char *result;
355 unsigned int len;
356
357 if (which >= MAX_CPUIDLE_STRING_FILES)
358 return NULL;
359
360 len = sysfs_cpuidle_read_file(cpuidle_string_files[which],
361 linebuf, sizeof(linebuf));
362 if (len == 0)
363 return NULL;
364
365 result = strdup(linebuf);
366 if (result == NULL)
367 return NULL;
368
369 result[strcspn(result, "\n")] = '\0';
370
371 return result;
372 }
373
cpuidle_get_governor(void)374 char *cpuidle_get_governor(void)
375 {
376 char *tmp = sysfs_cpuidle_get_one_string(CPUIDLE_GOVERNOR_RO);
377 if (!tmp)
378 return sysfs_cpuidle_get_one_string(CPUIDLE_GOVERNOR);
379 else
380 return tmp;
381 }
382
cpuidle_get_driver(void)383 char *cpuidle_get_driver(void)
384 {
385 return sysfs_cpuidle_get_one_string(CPUIDLE_DRIVER);
386 }
387 /* CPUidle idlestate specific /sys/devices/system/cpu/cpuX/cpuidle/ access */
388