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 |
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 |
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 |
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_TIME, |
120 | IDLESTATE_DISABLE, |
121 | MAX_IDLESTATE_VALUE_FILES |
122 | }; |
123 | |
124 | static const char *idlestate_value_files[MAX_IDLESTATE_VALUE_FILES] = { |
125 | [IDLESTATE_USAGE] = "usage" , |
126 | [IDLESTATE_POWER] = "power" , |
127 | [IDLESTATE_LATENCY] = "latency" , |
128 | [IDLESTATE_TIME] = "time" , |
129 | [IDLESTATE_DISABLE] = "disable" , |
130 | }; |
131 | |
132 | static |
133 | unsigned long long cpuidle_state_get_one_value(unsigned int cpu, |
134 | unsigned int idlestate, |
135 | enum idlestate_value which) |
136 | { |
137 | unsigned long long value; |
138 | unsigned int len; |
139 | char linebuf[MAX_LINE_LEN]; |
140 | char *endp; |
141 | |
142 | if (which >= MAX_IDLESTATE_VALUE_FILES) |
143 | return 0; |
144 | |
145 | len = cpuidle_state_read_file(cpu, idlestate, |
146 | idlestate_value_files[which], |
147 | linebuf, sizeof(linebuf)); |
148 | if (len == 0) |
149 | return 0; |
150 | |
151 | value = strtoull(linebuf, &endp, 0); |
152 | |
153 | if (endp == linebuf || errno == ERANGE) |
154 | return 0; |
155 | |
156 | return value; |
157 | } |
158 | |
159 | /* read access to files which contain one string */ |
160 | |
161 | enum idlestate_string { |
162 | IDLESTATE_DESC, |
163 | IDLESTATE_NAME, |
164 | MAX_IDLESTATE_STRING_FILES |
165 | }; |
166 | |
167 | static const char *idlestate_string_files[MAX_IDLESTATE_STRING_FILES] = { |
168 | [IDLESTATE_DESC] = "desc" , |
169 | [IDLESTATE_NAME] = "name" , |
170 | }; |
171 | |
172 | |
173 | static char *cpuidle_state_get_one_string(unsigned int cpu, |
174 | unsigned int idlestate, |
175 | enum idlestate_string which) |
176 | { |
177 | char linebuf[MAX_LINE_LEN]; |
178 | char *result; |
179 | unsigned int len; |
180 | |
181 | if (which >= MAX_IDLESTATE_STRING_FILES) |
182 | return NULL; |
183 | |
184 | len = cpuidle_state_read_file(cpu, idlestate, |
185 | idlestate_string_files[which], |
186 | linebuf, sizeof(linebuf)); |
187 | if (len == 0) |
188 | return NULL; |
189 | |
190 | result = strdup(linebuf); |
191 | if (result == NULL) |
192 | return NULL; |
193 | |
194 | if (result[strlen(result) - 1] == '\n') |
195 | result[strlen(result) - 1] = '\0'; |
196 | |
197 | return result; |
198 | } |
199 | |
200 | /* |
201 | * Returns: |
202 | * 1 if disabled |
203 | * 0 if enabled |
204 | * -1 if idlestate is not available |
205 | * -2 if disabling is not supported by the kernel |
206 | */ |
207 | int cpuidle_is_state_disabled(unsigned int cpu, |
208 | unsigned int idlestate) |
209 | { |
210 | if (cpuidle_state_count(cpu) <= idlestate) |
211 | return -1; |
212 | |
213 | if (!cpuidle_state_file_exists(cpu, idlestate, |
214 | fname: idlestate_value_files[IDLESTATE_DISABLE])) |
215 | return -2; |
216 | return cpuidle_state_get_one_value(cpu, idlestate, which: IDLESTATE_DISABLE); |
217 | } |
218 | |
219 | /* |
220 | * Pass 1 as last argument to disable or 0 to enable the state |
221 | * Returns: |
222 | * 0 on success |
223 | * negative values on error, for example: |
224 | * -1 if idlestate is not available |
225 | * -2 if disabling is not supported by the kernel |
226 | * -3 No write access to disable/enable C-states |
227 | */ |
228 | int cpuidle_state_disable(unsigned int cpu, |
229 | unsigned int idlestate, |
230 | unsigned int disable) |
231 | { |
232 | char value[SYSFS_PATH_MAX]; |
233 | int bytes_written; |
234 | |
235 | if (cpuidle_state_count(cpu) <= idlestate) |
236 | return -1; |
237 | |
238 | if (!cpuidle_state_file_exists(cpu, idlestate, |
239 | fname: idlestate_value_files[IDLESTATE_DISABLE])) |
240 | return -2; |
241 | |
242 | snprintf(value, SYSFS_PATH_MAX, "%u" , disable); |
243 | |
244 | bytes_written = cpuidle_state_write_file(cpu, idlestate, "disable" , |
245 | value, sizeof(disable)); |
246 | if (bytes_written) |
247 | return 0; |
248 | return -3; |
249 | } |
250 | |
251 | unsigned long cpuidle_state_latency(unsigned int cpu, |
252 | unsigned int idlestate) |
253 | { |
254 | return cpuidle_state_get_one_value(cpu, idlestate, which: IDLESTATE_LATENCY); |
255 | } |
256 | |
257 | unsigned long cpuidle_state_usage(unsigned int cpu, |
258 | unsigned int idlestate) |
259 | { |
260 | return cpuidle_state_get_one_value(cpu, idlestate, which: IDLESTATE_USAGE); |
261 | } |
262 | |
263 | unsigned long long cpuidle_state_time(unsigned int cpu, |
264 | unsigned int idlestate) |
265 | { |
266 | return cpuidle_state_get_one_value(cpu, idlestate, which: IDLESTATE_TIME); |
267 | } |
268 | |
269 | char *cpuidle_state_name(unsigned int cpu, unsigned int idlestate) |
270 | { |
271 | return cpuidle_state_get_one_string(cpu, idlestate, which: IDLESTATE_NAME); |
272 | } |
273 | |
274 | char *cpuidle_state_desc(unsigned int cpu, unsigned int idlestate) |
275 | { |
276 | return cpuidle_state_get_one_string(cpu, idlestate, which: IDLESTATE_DESC); |
277 | } |
278 | |
279 | /* |
280 | * Returns number of supported C-states of CPU core cpu |
281 | * Negativ in error case |
282 | * Zero if cpuidle does not export any C-states |
283 | */ |
284 | unsigned int cpuidle_state_count(unsigned int cpu) |
285 | { |
286 | char file[SYSFS_PATH_MAX]; |
287 | struct stat statbuf; |
288 | int idlestates = 1; |
289 | |
290 | |
291 | snprintf(file, SYSFS_PATH_MAX, PATH_TO_CPU "cpuidle" ); |
292 | if (stat(file, &statbuf) != 0 || !S_ISDIR(statbuf.st_mode)) |
293 | return 0; |
294 | |
295 | snprintf(file, SYSFS_PATH_MAX, PATH_TO_CPU "cpu%u/cpuidle/state0" , cpu); |
296 | if (stat(file, &statbuf) != 0 || !S_ISDIR(statbuf.st_mode)) |
297 | return 0; |
298 | |
299 | while (stat(file, &statbuf) == 0 && S_ISDIR(statbuf.st_mode)) { |
300 | snprintf(file, SYSFS_PATH_MAX, PATH_TO_CPU |
301 | "cpu%u/cpuidle/state%d" , cpu, idlestates); |
302 | idlestates++; |
303 | } |
304 | idlestates--; |
305 | return idlestates; |
306 | } |
307 | |
308 | /* CPUidle general /sys/devices/system/cpu/cpuidle/ sysfs access ********/ |
309 | |
310 | /* |
311 | * helper function to read file from /sys into given buffer |
312 | * fname is a relative path under "cpu/cpuidle/" dir |
313 | */ |
314 | static unsigned int sysfs_cpuidle_read_file(const char *fname, char *buf, |
315 | size_t buflen) |
316 | { |
317 | char path[SYSFS_PATH_MAX]; |
318 | |
319 | snprintf(path, sizeof(path), PATH_TO_CPU "cpuidle/%s" , fname); |
320 | |
321 | return cpupower_read_sysfs(path, buf, buflen); |
322 | } |
323 | |
324 | |
325 | |
326 | /* read access to files which contain one string */ |
327 | |
328 | enum cpuidle_string { |
329 | CPUIDLE_GOVERNOR, |
330 | CPUIDLE_GOVERNOR_RO, |
331 | CPUIDLE_DRIVER, |
332 | MAX_CPUIDLE_STRING_FILES |
333 | }; |
334 | |
335 | static const char *cpuidle_string_files[MAX_CPUIDLE_STRING_FILES] = { |
336 | [CPUIDLE_GOVERNOR] = "current_governor" , |
337 | [CPUIDLE_GOVERNOR_RO] = "current_governor_ro" , |
338 | [CPUIDLE_DRIVER] = "current_driver" , |
339 | }; |
340 | |
341 | |
342 | static char *sysfs_cpuidle_get_one_string(enum cpuidle_string which) |
343 | { |
344 | char linebuf[MAX_LINE_LEN]; |
345 | char *result; |
346 | unsigned int len; |
347 | |
348 | if (which >= MAX_CPUIDLE_STRING_FILES) |
349 | return NULL; |
350 | |
351 | len = sysfs_cpuidle_read_file(cpuidle_string_files[which], |
352 | linebuf, sizeof(linebuf)); |
353 | if (len == 0) |
354 | return NULL; |
355 | |
356 | result = strdup(linebuf); |
357 | if (result == NULL) |
358 | return NULL; |
359 | |
360 | if (result[strlen(result) - 1] == '\n') |
361 | result[strlen(result) - 1] = '\0'; |
362 | |
363 | return result; |
364 | } |
365 | |
366 | char *cpuidle_get_governor(void) |
367 | { |
368 | char *tmp = sysfs_cpuidle_get_one_string(which: CPUIDLE_GOVERNOR_RO); |
369 | if (!tmp) |
370 | return sysfs_cpuidle_get_one_string(which: CPUIDLE_GOVERNOR); |
371 | else |
372 | return tmp; |
373 | } |
374 | |
375 | char *cpuidle_get_driver(void) |
376 | { |
377 | return sysfs_cpuidle_get_one_string(which: CPUIDLE_DRIVER); |
378 | } |
379 | /* CPUidle idlestate specific /sys/devices/system/cpu/cpuX/cpuidle/ access */ |
380 | |