tools/power/cpupower/utils/helpers/sysfs.c

   1 /*
   2  *  (C) 2004-2009  Dominik Brodowski <linux@dominikbrodowski.de>
   3  *  (C) 2011       Thomas Renninger <trenn@novell.com> Novell Inc.
   4  *
   5  *  Licensed under the terms of the GNU GPL License version 2.
   6  */
   7
   8 #include <stdio.h>
   9 #include <errno.h>
  10 #include <stdlib.h>
  11 #include <string.h>
  12 #include <sys/types.h>
  13 #include <sys/stat.h>
  14 #include <fcntl.h>
  15 #include <unistd.h>
  16
  17 #include "helpers/sysfs.h"
  18
  19 unsigned int sysfs_read_file(const char *path, char *buf, size_t buflen)
  20 {
  21         int fd;
  22         ssize_t numread;
  23
  24         fd = open(path, O_RDONLY);
  25         if (fd == -1)
  26                 return 0;
  27
  28         numread = read(fd, buf, buflen - 1);
  29         if (numread < 1) {
  30                 close(fd);
  31                 return 0;
  32         }
  33
  34         buf[numread] = '\0';
  35         close(fd);
  36
  37         return (unsigned int) numread;
  38 }
  39
  40 /*
  41  * Detect whether a CPU is online
  42  *
  43  * Returns:
  44  *     1 -> if CPU is online
  45  *     0 -> if CPU is offline
  46  *     negative errno values in error case
  47  */
  48 int sysfs_is_cpu_online(unsigned int cpu)
  49 {
  50         char path[SYSFS_PATH_MAX];
  51         int fd;
  52         ssize_t numread;
  53         unsigned long long value;
  54         char linebuf[MAX_LINE_LEN];
  55         char *endp;
  56         struct stat statbuf;
  57
  58         snprintf(path, sizeof(path), PATH_TO_CPU "cpu%u", cpu);
  59
  60         if (stat(path, &statbuf) != 0)
  61                 return 0;
  62
  63         /*
  64          * kernel without CONFIG_HOTPLUG_CPU
  65          * -> cpuX directory exists, but not cpuX/online file
  66          */
  67         snprintf(path, sizeof(path), PATH_TO_CPU "cpu%u/online", cpu);
  68         if (stat(path, &statbuf) != 0)
  69                 return 1;
  70
  71         fd = open(path, O_RDONLY);
  72         if (fd == -1)
  73                 return -errno;
  74
  75         numread = read(fd, linebuf, MAX_LINE_LEN - 1);
  76         if (numread < 1) {
  77                 close(fd);
  78                 return -EIO;
  79         }
  80         linebuf[numread] = '\0';
  81         close(fd);
  82
  83         value = strtoull(linebuf, &endp, 0);
  84         if (value > 1 || value < 0)
  85                 return -EINVAL;
  86
  87         return value;
  88 }
  89
  90 /* CPUidle idlestate specific /sys/devices/system/cpu/cpuX/cpuidle/ access */
  91
  92
  93 /* CPUidle idlestate specific /sys/devices/system/cpu/cpuX/cpuidle/ access */
  94
  95 /*
  96  * helper function to check whether a file under "../cpuX/cpuidle/stateX/" dir
  97  * exists.
  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
 100  * feature.
 101  *
 102  * returns 1 if the file exists, 0 otherwise.
 103  */
 104 unsigned int sysfs_idlestate_file_exists(unsigned int cpu,
 105                                          unsigned int idlestate,
 106                                          const char *fname)
 107 {
 108         char path[SYSFS_PATH_MAX];
 109         struct stat statbuf;
 110
 111
 112         snprintf(path, sizeof(path), PATH_TO_CPU "cpu%u/cpuidle/state%u/%s",
 113                  cpu, idlestate, fname);
 114         if (stat(path, &statbuf) != 0)
 115                 return 0;
 116         return 1;
 117 }
 118
 119 /*
 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
 124  */
 125 unsigned int sysfs_idlestate_read_file(unsigned int cpu, unsigned int idlestate,
 126                              const char *fname, char *buf, size_t buflen)
 127 {
 128         char path[SYSFS_PATH_MAX];
 129         int fd;
 130         ssize_t numread;
 131
 132         snprintf(path, sizeof(path), PATH_TO_CPU "cpu%u/cpuidle/state%u/%s",
 133                  cpu, idlestate, fname);
 134
 135         fd = open(path, O_RDONLY);
 136         if (fd == -1)
 137                 return 0;
 138
 139         numread = read(fd, buf, buflen - 1);
 140         if (numread < 1) {
 141                 close(fd);
 142                 return 0;
 143         }
 144
 145         buf[numread] = '\0';
 146         close(fd);
 147
 148         return (unsigned int) numread;
 149 }
 150
 151 /*
 152  * helper function to write a new value to a /sys file
 153  * fname is a relative path under "../cpuX/cpuidle/cstateY/" dir
 154  *
 155  * Returns the number of bytes written or 0 on error
 156  */
 157 static
 158 unsigned int sysfs_idlestate_write_file(unsigned int cpu,
 159                                         unsigned int idlestate,
 160                                         const char *fname,
 161                                         const char *value, size_t len)
 162 {
 163         char path[SYSFS_PATH_MAX];
 164         int fd;
 165         ssize_t numwrite;
 166
 167         snprintf(path, sizeof(path), PATH_TO_CPU "cpu%u/cpuidle/state%u/%s",
 168                  cpu, idlestate, fname);
 169
 170         fd = open(path, O_WRONLY);
 171         if (fd == -1)
 172                 return 0;
 173
 174         numwrite = write(fd, value, len);
 175         if (numwrite < 1) {
 176                 close(fd);
 177                 return 0;
 178         }
 179
 180         close(fd);
 181
 182         return (unsigned int) numwrite;
 183 }
 184
 185 /* read access to files which contain one numeric value */
 186
 187 enum idlestate_value {
 188         IDLESTATE_USAGE,
 189         IDLESTATE_POWER,
 190         IDLESTATE_LATENCY,
 191         IDLESTATE_TIME,
 192         IDLESTATE_DISABLE,
 193         MAX_IDLESTATE_VALUE_FILES
 194 };
 195
 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",
 202 };
 203
 204 static unsigned long long sysfs_idlestate_get_one_value(unsigned int cpu,
 205                                                      unsigned int idlestate,
 206                                                      enum idlestate_value which)
 207 {
 208         unsigned long long value;
 209         unsigned int len;
 210         char linebuf[MAX_LINE_LEN];
 211         char *endp;
 212
 213         if (which >= MAX_IDLESTATE_VALUE_FILES)
 214                 return 0;
 215
 216         len = sysfs_idlestate_read_file(cpu, idlestate,
 217                                         idlestate_value_files[which],
 218                                         linebuf, sizeof(linebuf));
 219         if (len == 0)
 220                 return 0;
 221
 222         value = strtoull(linebuf, &endp, 0);
 223
 224         if (endp == linebuf || errno == ERANGE)
 225                 return 0;
 226
 227         return value;
 228 }
 229
 230 /* read access to files which contain one string */
 231
 232 enum idlestate_string {
 233         IDLESTATE_DESC,
 234         IDLESTATE_NAME,
 235         MAX_IDLESTATE_STRING_FILES
 236 };
 237
 238 static const char *idlestate_string_files[MAX_IDLESTATE_STRING_FILES] = {
 239         [IDLESTATE_DESC] = "desc",
 240         [IDLESTATE_NAME] = "name",
 241 };
 242
 243
 244 static char *sysfs_idlestate_get_one_string(unsigned int cpu,
 245                                         unsigned int idlestate,
 246                                         enum idlestate_string which)
 247 {
 248         char linebuf[MAX_LINE_LEN];
 249         char *result;
 250         unsigned int len;
 251
 252         if (which >= MAX_IDLESTATE_STRING_FILES)
 253                 return NULL;
 254
 255         len = sysfs_idlestate_read_file(cpu, idlestate,
 256                                         idlestate_string_files[which],
 257                                         linebuf, sizeof(linebuf));
 258         if (len == 0)
 259                 return NULL;
 260
 261         result = strdup(linebuf);
 262         if (result == NULL)
 263                 return NULL;
 264
 265         if (result[strlen(result) - 1] == '\n')
 266                 result[strlen(result) - 1] = '\0';
 267
 268         return result;
 269 }
 270
 271 /*
 272  * Returns:
 273  *    1  if disabled
 274  *    0  if enabled
 275  *    -1 if idlestate is not available
 276  *    -2 if disabling is not supported by the kernel
 277  */
 278 int sysfs_is_idlestate_disabled(unsigned int cpu,
 279                                 unsigned int idlestate)
 280 {
 281         if (sysfs_get_idlestate_count(cpu) <= idlestate)
 282                 return -1;
 283
 284         if (!sysfs_idlestate_file_exists(cpu, idlestate,
 285                                  idlestate_value_files[IDLESTATE_DISABLE]))
 286                 return -2;
 287         return sysfs_idlestate_get_one_value(cpu, idlestate, IDLESTATE_DISABLE);
 288 }
 289
 290 /*
 291  * Pass 1 as last argument to disable or 0 to enable the state
 292  * Returns:
 293  *    0  on success
 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
 298  */
 299 int sysfs_idlestate_disable(unsigned int cpu,
 300                             unsigned int idlestate,
 301                             unsigned int disable)
 302 {
 303         char value[SYSFS_PATH_MAX];
 304         int bytes_written;
 305
 306         if (sysfs_get_idlestate_count(cpu) <= idlestate)
 307                 return -1;
 308
 309         if (!sysfs_idlestate_file_exists(cpu, idlestate,
 310                                  idlestate_value_files[IDLESTATE_DISABLE]))
 311                 return -2;
 312
 313         snprintf(value, SYSFS_PATH_MAX, "%u", disable);
 314
 315         bytes_written = sysfs_idlestate_write_file(cpu, idlestate, "disable",
 316                                                    value, sizeof(disable));
 317         if (bytes_written)
 318                 return 0;
 319         return -3;
 320 }
 321
 322 unsigned long sysfs_get_idlestate_latency(unsigned int cpu,
 323                                           unsigned int idlestate)
 324 {
 325         return sysfs_idlestate_get_one_value(cpu, idlestate, IDLESTATE_LATENCY);
 326 }
 327
 328 unsigned long sysfs_get_idlestate_usage(unsigned int cpu,
 329                                         unsigned int idlestate)
 330 {
 331         return sysfs_idlestate_get_one_value(cpu, idlestate, IDLESTATE_USAGE);
 332 }
 333
 334 unsigned long long sysfs_get_idlestate_time(unsigned int cpu,
 335                                         unsigned int idlestate)
 336 {
 337         return sysfs_idlestate_get_one_value(cpu, idlestate, IDLESTATE_TIME);
 338 }
 339
 340 char *sysfs_get_idlestate_name(unsigned int cpu, unsigned int idlestate)
 341 {
 342         return sysfs_idlestate_get_one_string(cpu, idlestate, IDLESTATE_NAME);
 343 }
 344
 345 char *sysfs_get_idlestate_desc(unsigned int cpu, unsigned int idlestate)
 346 {
 347         return sysfs_idlestate_get_one_string(cpu, idlestate, IDLESTATE_DESC);
 348 }
 349
 350 /*
 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
 354  */
 355 unsigned int sysfs_get_idlestate_count(unsigned int cpu)
 356 {
 357         char file[SYSFS_PATH_MAX];
 358         struct stat statbuf;
 359         int idlestates = 1;
 360
 361
 362         snprintf(file, SYSFS_PATH_MAX, PATH_TO_CPU "cpuidle");
 363         if (stat(file, &statbuf) != 0 || !S_ISDIR(statbuf.st_mode))
 364                 return -ENODEV;
 365
 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))
 368                 return 0;
 369
 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);
 373                 idlestates++;
 374         }
 375         idlestates--;
 376         return idlestates;
 377 }
 378
 379 /* CPUidle general /sys/devices/system/cpu/cpuidle/ sysfs access ********/
 380
 381 /*
 382  * helper function to read file from /sys into given buffer
 383  * fname is a relative path under "cpu/cpuidle/" dir
 384  */
 385 static unsigned int sysfs_cpuidle_read_file(const char *fname, char *buf,
 386                                             size_t buflen)
 387 {
 388         char path[SYSFS_PATH_MAX];
 389
 390         snprintf(path, sizeof(path), PATH_TO_CPU "cpuidle/%s", fname);
 391
 392         return sysfs_read_file(path, buf, buflen);
 393 }
 394
 395
 396
 397 /* read access to files which contain one string */
 398
 399 enum cpuidle_string {
 400         CPUIDLE_GOVERNOR,
 401         CPUIDLE_GOVERNOR_RO,
 402         CPUIDLE_DRIVER,
 403         MAX_CPUIDLE_STRING_FILES
 404 };
 405
 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",
 410 };
 411
 412
 413 static char *sysfs_cpuidle_get_one_string(enum cpuidle_string which)
 414 {
 415         char linebuf[MAX_LINE_LEN];
 416         char *result;
 417         unsigned int len;
 418
 419         if (which >= MAX_CPUIDLE_STRING_FILES)
 420                 return NULL;
 421
 422         len = sysfs_cpuidle_read_file(cpuidle_string_files[which],
 423                                 linebuf, sizeof(linebuf));
 424         if (len == 0)
 425                 return NULL;
 426
 427         result = strdup(linebuf);
 428         if (result == NULL)
 429                 return NULL;
 430
 431         if (result[strlen(result) - 1] == '\n')
 432                 result[strlen(result) - 1] = '\0';
 433
 434         return result;
 435 }
 436
 437 char *sysfs_get_cpuidle_governor(void)
 438 {
 439         char *tmp = sysfs_cpuidle_get_one_string(CPUIDLE_GOVERNOR_RO);
 440         if (!tmp)
 441                 return sysfs_cpuidle_get_one_string(CPUIDLE_GOVERNOR);
 442         else
 443                 return tmp;
 444 }
 445
 446 char *sysfs_get_cpuidle_driver(void)
 447 {
 448         return sysfs_cpuidle_get_one_string(CPUIDLE_DRIVER);
 449 }
 450 /* CPUidle idlestate specific /sys/devices/system/cpu/cpuX/cpuidle/ access */
 451
 452 /*
 453  * Get sched_mc or sched_smt settings
 454  * Pass "mc" or "smt" as argument
 455  *
 456  * Returns negative value on failure
 457  */
 458 int sysfs_get_sched(const char *smt_mc)
 459 {
 460         return -ENODEV;
 461 }
 462
 463 /*
 464  * Get sched_mc or sched_smt settings
 465  * Pass "mc" or "smt" as argument
 466  *
 467  * Returns negative value on failure
 468  */
 469 int sysfs_set_sched(const char *smt_mc, int val)
 470 {
 471         return -ENODEV;
 472 }