drivers/cpuidle/sysfs.c

   1 /*
   2  * sysfs.c - sysfs support
   3  *
   4  * (C) 2006-2007 Shaohua Li <shaohua.li@intel.com>
   5  *
   6  * This code is licenced under the GPL.
   7  */
   8
   9 #include <linux/kernel.h>
  10 #include <linux/cpuidle.h>
  11 #include <linux/sysfs.h>
  12 #include <linux/slab.h>
  13 #include <linux/cpu.h>
  14 #include <linux/completion.h>
  15 #include <linux/capability.h>
  16 #include <linux/device.h>
  17 #include <linux/kobject.h>
  18
  19 #include "cpuidle.h"
  20
  21 static unsigned int sysfs_switch;
  22 static int __init cpuidle_sysfs_setup(char *unused)
  23 {
  24         sysfs_switch = 1;
  25         return 1;
  26 }
  27 __setup("cpuidle_sysfs_switch", cpuidle_sysfs_setup);
  28
  29 static ssize_t show_available_governors(struct device *dev,
  30                                         struct device_attribute *attr,
  31                                         char *buf)
  32 {
  33         ssize_t i = 0;
  34         struct cpuidle_governor *tmp;
  35
  36         mutex_lock(&cpuidle_lock);
  37         list_for_each_entry(tmp, &cpuidle_governors, governor_list) {
  38                 if (i >= (ssize_t) ((PAGE_SIZE/sizeof(char)) -
  39                                     CPUIDLE_NAME_LEN - 2))
  40                         goto out;
  41                 i += scnprintf(&buf[i], CPUIDLE_NAME_LEN, "%s ", tmp->name);
  42         }
  43
  44 out:
  45         i+= sprintf(&buf[i], "\n");
  46         mutex_unlock(&cpuidle_lock);
  47         return i;
  48 }
  49
  50 static ssize_t show_current_driver(struct device *dev,
  51                                    struct device_attribute *attr,
  52                                    char *buf)
  53 {
  54         ssize_t ret;
  55         struct cpuidle_driver *drv;
  56
  57         spin_lock(&cpuidle_driver_lock);
  58         drv = cpuidle_get_driver();
  59         if (drv)
  60                 ret = sprintf(buf, "%s\n", drv->name);
  61         else
  62                 ret = sprintf(buf, "none\n");
  63         spin_unlock(&cpuidle_driver_lock);
  64
  65         return ret;
  66 }
  67
  68 static ssize_t show_current_governor(struct device *dev,
  69                                      struct device_attribute *attr,
  70                                      char *buf)
  71 {
  72         ssize_t ret;
  73
  74         mutex_lock(&cpuidle_lock);
  75         if (cpuidle_curr_governor)
  76                 ret = sprintf(buf, "%s\n", cpuidle_curr_governor->name);
  77         else
  78                 ret = sprintf(buf, "none\n");
  79         mutex_unlock(&cpuidle_lock);
  80
  81         return ret;
  82 }
  83
  84 static ssize_t store_current_governor(struct device *dev,
  85                                       struct device_attribute *attr,
  86                                       const char *buf, size_t count)
  87 {
  88         char gov_name[CPUIDLE_NAME_LEN];
  89         int ret = -EINVAL;
  90         size_t len = count;
  91         struct cpuidle_governor *gov;
  92
  93         if (!len || len >= sizeof(gov_name))
  94                 return -EINVAL;
  95
  96         memcpy(gov_name, buf, len);
  97         gov_name[len] = '\0';
  98         if (gov_name[len - 1] == '\n')
  99                 gov_name[--len] = '\0';
 100
 101         mutex_lock(&cpuidle_lock);
 102
 103         list_for_each_entry(gov, &cpuidle_governors, governor_list) {
 104                 if (strlen(gov->name) == len && !strcmp(gov->name, gov_name)) {
 105                         ret = cpuidle_switch_governor(gov);
 106                         break;
 107                 }
 108         }
 109
 110         mutex_unlock(&cpuidle_lock);
 111
 112         if (ret)
 113                 return ret;
 114         else
 115                 return count;
 116 }
 117
 118 static DEVICE_ATTR(current_driver, 0444, show_current_driver, NULL);
 119 static DEVICE_ATTR(current_governor_ro, 0444, show_current_governor, NULL);
 120
 121 static struct attribute *cpuidle_default_attrs[] = {
 122         &dev_attr_current_driver.attr,
 123         &dev_attr_current_governor_ro.attr,
 124         NULL
 125 };
 126
 127 static DEVICE_ATTR(available_governors, 0444, show_available_governors, NULL);
 128 static DEVICE_ATTR(current_governor, 0644, show_current_governor,
 129                    store_current_governor);
 130
 131 static struct attribute *cpuidle_switch_attrs[] = {
 132         &dev_attr_available_governors.attr,
 133         &dev_attr_current_driver.attr,
 134         &dev_attr_current_governor.attr,
 135         NULL
 136 };
 137
 138 static struct attribute_group cpuidle_attr_group = {
 139         .attrs = cpuidle_default_attrs,
 140         .name = "cpuidle",
 141 };
 142
 143 /**
 144  * cpuidle_add_interface - add CPU global sysfs attributes
 145  */
 146 int cpuidle_add_interface(struct device *dev)
 147 {
 148         if (sysfs_switch)
 149                 cpuidle_attr_group.attrs = cpuidle_switch_attrs;
 150
 151         return sysfs_create_group(&dev->kobj, &cpuidle_attr_group);
 152 }
 153
 154 /**
 155  * cpuidle_remove_interface - remove CPU global sysfs attributes
 156  */
 157 void cpuidle_remove_interface(struct device *dev)
 158 {
 159         sysfs_remove_group(&dev->kobj, &cpuidle_attr_group);
 160 }
 161
 162 struct cpuidle_attr {
 163         struct attribute attr;
 164         ssize_t (*show)(struct cpuidle_device *, char *);
 165         ssize_t (*store)(struct cpuidle_device *, const char *, size_t count);
 166 };
 167
 168 #define define_one_ro(_name, show) \
 169         static struct cpuidle_attr attr_##_name = __ATTR(_name, 0444, show, NULL)
 170 #define define_one_rw(_name, show, store) \
 171         static struct cpuidle_attr attr_##_name = __ATTR(_name, 0644, show, store)
 172
 173 #define attr_to_cpuidleattr(a) container_of(a, struct cpuidle_attr, attr)
 174
 175 struct cpuidle_device_kobj {
 176         struct cpuidle_device *dev;
 177         struct completion kobj_unregister;
 178         struct kobject kobj;
 179 };
 180
 181 static inline struct cpuidle_device *to_cpuidle_device(struct kobject *kobj)
 182 {
 183         struct cpuidle_device_kobj *kdev =
 184                 container_of(kobj, struct cpuidle_device_kobj, kobj);
 185
 186         return kdev->dev;
 187 }
 188
 189 static ssize_t cpuidle_show(struct kobject *kobj, struct attribute *attr,
 190                             char *buf)
 191 {
 192         int ret = -EIO;
 193         struct cpuidle_device *dev = to_cpuidle_device(kobj);
 194         struct cpuidle_attr *cattr = attr_to_cpuidleattr(attr);
 195
 196         if (cattr->show) {
 197                 mutex_lock(&cpuidle_lock);
 198                 ret = cattr->show(dev, buf);
 199                 mutex_unlock(&cpuidle_lock);
 200         }
 201         return ret;
 202 }
 203
 204 static ssize_t cpuidle_store(struct kobject *kobj, struct attribute *attr,
 205                              const char *buf, size_t count)
 206 {
 207         int ret = -EIO;
 208         struct cpuidle_device *dev = to_cpuidle_device(kobj);
 209         struct cpuidle_attr *cattr = attr_to_cpuidleattr(attr);
 210
 211         if (cattr->store) {
 212                 mutex_lock(&cpuidle_lock);
 213                 ret = cattr->store(dev, buf, count);
 214                 mutex_unlock(&cpuidle_lock);
 215         }
 216         return ret;
 217 }
 218
 219 static const struct sysfs_ops cpuidle_sysfs_ops = {
 220         .show = cpuidle_show,
 221         .store = cpuidle_store,
 222 };
 223
 224 static void cpuidle_sysfs_release(struct kobject *kobj)
 225 {
 226         struct cpuidle_device_kobj *kdev =
 227                 container_of(kobj, struct cpuidle_device_kobj, kobj);
 228
 229         complete(&kdev->kobj_unregister);
 230 }
 231
 232 static struct kobj_type ktype_cpuidle = {
 233         .sysfs_ops = &cpuidle_sysfs_ops,
 234         .release = cpuidle_sysfs_release,
 235 };
 236
 237 struct cpuidle_state_attr {
 238         struct attribute attr;
 239         ssize_t (*show)(struct cpuidle_state *, \
 240                                         struct cpuidle_state_usage *, char *);
 241         ssize_t (*store)(struct cpuidle_state *, \
 242                         struct cpuidle_state_usage *, const char *, size_t);
 243 };
 244
 245 #define define_one_state_ro(_name, show) \
 246 static struct cpuidle_state_attr attr_##_name = __ATTR(_name, 0444, show, NULL)
 247
 248 #define define_one_state_rw(_name, show, store) \
 249 static struct cpuidle_state_attr attr_##_name = __ATTR(_name, 0644, show, store)
 250
 251 #define define_show_state_function(_name) \
 252 static ssize_t show_state_##_name(struct cpuidle_state *state, \
 253                          struct cpuidle_state_usage *state_usage, char *buf) \
 254 { \
 255         return sprintf(buf, "%u\n", state->_name);\
 256 }
 257
 258 #define define_store_state_ull_function(_name) \
 259 static ssize_t store_state_##_name(struct cpuidle_state *state, \
 260                                    struct cpuidle_state_usage *state_usage, \
 261                                    const char *buf, size_t size)        \
 262 { \
 263         unsigned long long value; \
 264         int err; \
 265         if (!capable(CAP_SYS_ADMIN)) \
 266                 return -EPERM; \
 267         err = kstrtoull(buf, 0, &value); \
 268         if (err) \
 269                 return err; \
 270         if (value) \
 271                 state_usage->_name = 1; \
 272         else \
 273                 state_usage->_name = 0; \
 274         return size; \
 275 }
 276
 277 #define define_show_state_ull_function(_name) \
 278 static ssize_t show_state_##_name(struct cpuidle_state *state, \
 279                                   struct cpuidle_state_usage *state_usage, \
 280                                   char *buf)                            \
 281 { \
 282         return sprintf(buf, "%llu\n", state_usage->_name);\
 283 }
 284
 285 #define define_show_state_str_function(_name) \
 286 static ssize_t show_state_##_name(struct cpuidle_state *state, \
 287                                   struct cpuidle_state_usage *state_usage, \
 288                                   char *buf)                            \
 289 { \
 290         if (state->_name[0] == '\0')\
 291                 return sprintf(buf, "<null>\n");\
 292         return sprintf(buf, "%s\n", state->_name);\
 293 }
 294
 295 define_show_state_function(exit_latency)
 296 define_show_state_function(target_residency)
 297 define_show_state_function(power_usage)
 298 define_show_state_ull_function(usage)
 299 define_show_state_ull_function(time)
 300 define_show_state_str_function(name)
 301 define_show_state_str_function(desc)
 302 define_show_state_ull_function(disable)
 303 define_store_state_ull_function(disable)
 304 define_show_state_ull_function(above)
 305 define_show_state_ull_function(below)
 306
 307 define_one_state_ro(name, show_state_name);
 308 define_one_state_ro(desc, show_state_desc);
 309 define_one_state_ro(latency, show_state_exit_latency);
 310 define_one_state_ro(residency, show_state_target_residency);
 311 define_one_state_ro(power, show_state_power_usage);
 312 define_one_state_ro(usage, show_state_usage);
 313 define_one_state_ro(time, show_state_time);
 314 define_one_state_rw(disable, show_state_disable, store_state_disable);
 315 define_one_state_ro(above, show_state_above);
 316 define_one_state_ro(below, show_state_below);
 317
 318 static struct attribute *cpuidle_state_default_attrs[] = {
 319         &attr_name.attr,
 320         &attr_desc.attr,
 321         &attr_latency.attr,
 322         &attr_residency.attr,
 323         &attr_power.attr,
 324         &attr_usage.attr,
 325         &attr_time.attr,
 326         &attr_disable.attr,
 327         &attr_above.attr,
 328         &attr_below.attr,
 329         NULL
 330 };
 331
 332 struct cpuidle_state_kobj {
 333         struct cpuidle_state *state;
 334         struct cpuidle_state_usage *state_usage;
 335         struct completion kobj_unregister;
 336         struct kobject kobj;
 337 };
 338
 339 #ifdef CONFIG_SUSPEND
 340 #define define_show_state_s2idle_ull_function(_name) \
 341 static ssize_t show_state_s2idle_##_name(struct cpuidle_state *state, \
 342                                          struct cpuidle_state_usage *state_usage, \
 343                                          char *buf)                             \
 344 { \
 345         return sprintf(buf, "%llu\n", state_usage->s2idle_##_name);\
 346 }
 347
 348 define_show_state_s2idle_ull_function(usage);
 349 define_show_state_s2idle_ull_function(time);
 350
 351 #define define_one_state_s2idle_ro(_name, show) \
 352 static struct cpuidle_state_attr attr_s2idle_##_name = \
 353         __ATTR(_name, 0444, show, NULL)
 354
 355 define_one_state_s2idle_ro(usage, show_state_s2idle_usage);
 356 define_one_state_s2idle_ro(time, show_state_s2idle_time);
 357
 358 static struct attribute *cpuidle_state_s2idle_attrs[] = {
 359         &attr_s2idle_usage.attr,
 360         &attr_s2idle_time.attr,
 361         NULL
 362 };
 363
 364 static const struct attribute_group cpuidle_state_s2idle_group = {
 365         .name   = "s2idle",
 366         .attrs  = cpuidle_state_s2idle_attrs,
 367 };
 368
 369 static void cpuidle_add_s2idle_attr_group(struct cpuidle_state_kobj *kobj)
 370 {
 371         int ret;
 372
 373         if (!kobj->state->enter_s2idle)
 374                 return;
 375
 376         ret = sysfs_create_group(&kobj->kobj, &cpuidle_state_s2idle_group);
 377         if (ret)
 378                 pr_debug("%s: sysfs attribute group not created\n", __func__);
 379 }
 380
 381 static void cpuidle_remove_s2idle_attr_group(struct cpuidle_state_kobj *kobj)
 382 {
 383         if (kobj->state->enter_s2idle)
 384                 sysfs_remove_group(&kobj->kobj, &cpuidle_state_s2idle_group);
 385 }
 386 #else
 387 static inline void cpuidle_add_s2idle_attr_group(struct cpuidle_state_kobj *kobj) { }
 388 static inline void cpuidle_remove_s2idle_attr_group(struct cpuidle_state_kobj *kobj) { }
 389 #endif /* CONFIG_SUSPEND */
 390
 391 #define kobj_to_state_obj(k) container_of(k, struct cpuidle_state_kobj, kobj)
 392 #define kobj_to_state(k) (kobj_to_state_obj(k)->state)
 393 #define kobj_to_state_usage(k) (kobj_to_state_obj(k)->state_usage)
 394 #define attr_to_stateattr(a) container_of(a, struct cpuidle_state_attr, attr)
 395
 396 static ssize_t cpuidle_state_show(struct kobject *kobj, struct attribute *attr,
 397                                   char * buf)
 398 {
 399         int ret = -EIO;
 400         struct cpuidle_state *state = kobj_to_state(kobj);
 401         struct cpuidle_state_usage *state_usage = kobj_to_state_usage(kobj);
 402         struct cpuidle_state_attr * cattr = attr_to_stateattr(attr);
 403
 404         if (cattr->show)
 405                 ret = cattr->show(state, state_usage, buf);
 406
 407         return ret;
 408 }
 409
 410 static ssize_t cpuidle_state_store(struct kobject *kobj, struct attribute *attr,
 411                                    const char *buf, size_t size)
 412 {
 413         int ret = -EIO;
 414         struct cpuidle_state *state = kobj_to_state(kobj);
 415         struct cpuidle_state_usage *state_usage = kobj_to_state_usage(kobj);
 416         struct cpuidle_state_attr *cattr = attr_to_stateattr(attr);
 417
 418         if (cattr->store)
 419                 ret = cattr->store(state, state_usage, buf, size);
 420
 421         return ret;
 422 }
 423
 424 static const struct sysfs_ops cpuidle_state_sysfs_ops = {
 425         .show = cpuidle_state_show,
 426         .store = cpuidle_state_store,
 427 };
 428
 429 static void cpuidle_state_sysfs_release(struct kobject *kobj)
 430 {
 431         struct cpuidle_state_kobj *state_obj = kobj_to_state_obj(kobj);
 432
 433         complete(&state_obj->kobj_unregister);
 434 }
 435
 436 static struct kobj_type ktype_state_cpuidle = {
 437         .sysfs_ops = &cpuidle_state_sysfs_ops,
 438         .default_attrs = cpuidle_state_default_attrs,
 439         .release = cpuidle_state_sysfs_release,
 440 };
 441
 442 static inline void cpuidle_free_state_kobj(struct cpuidle_device *device, int i)
 443 {
 444         cpuidle_remove_s2idle_attr_group(device->kobjs[i]);
 445         kobject_put(&device->kobjs[i]->kobj);
 446         wait_for_completion(&device->kobjs[i]->kobj_unregister);
 447         kfree(device->kobjs[i]);
 448         device->kobjs[i] = NULL;
 449 }
 450
 451 /**
 452  * cpuidle_add_state_sysfs - adds cpuidle states sysfs attributes
 453  * @device: the target device
 454  */
 455 static int cpuidle_add_state_sysfs(struct cpuidle_device *device)
 456 {
 457         int i, ret = -ENOMEM;
 458         struct cpuidle_state_kobj *kobj;
 459         struct cpuidle_device_kobj *kdev = device->kobj_dev;
 460         struct cpuidle_driver *drv = cpuidle_get_cpu_driver(device);
 461
 462         /* state statistics */
 463         for (i = 0; i < drv->state_count; i++) {
 464                 kobj = kzalloc(sizeof(struct cpuidle_state_kobj), GFP_KERNEL);
 465                 if (!kobj) {
 466                         ret = -ENOMEM;
 467                         goto error_state;
 468                 }
 469                 kobj->state = &drv->states[i];
 470                 kobj->state_usage = &device->states_usage[i];
 471                 init_completion(&kobj->kobj_unregister);
 472
 473                 ret = kobject_init_and_add(&kobj->kobj, &ktype_state_cpuidle,
 474                                            &kdev->kobj, "state%d", i);
 475                 if (ret) {
 476                         kfree(kobj);
 477                         goto error_state;
 478                 }
 479                 cpuidle_add_s2idle_attr_group(kobj);
 480                 kobject_uevent(&kobj->kobj, KOBJ_ADD);
 481                 device->kobjs[i] = kobj;
 482         }
 483
 484         return 0;
 485
 486 error_state:
 487         for (i = i - 1; i >= 0; i--)
 488                 cpuidle_free_state_kobj(device, i);
 489         return ret;
 490 }
 491
 492 /**
 493  * cpuidle_remove_driver_sysfs - removes the cpuidle states sysfs attributes
 494  * @device: the target device
 495  */
 496 static void cpuidle_remove_state_sysfs(struct cpuidle_device *device)
 497 {
 498         struct cpuidle_driver *drv = cpuidle_get_cpu_driver(device);
 499         int i;
 500
 501         for (i = 0; i < drv->state_count; i++)
 502                 cpuidle_free_state_kobj(device, i);
 503 }
 504
 505 #ifdef CONFIG_CPU_IDLE_MULTIPLE_DRIVERS
 506 #define kobj_to_driver_kobj(k) container_of(k, struct cpuidle_driver_kobj, kobj)
 507 #define attr_to_driver_attr(a) container_of(a, struct cpuidle_driver_attr, attr)
 508
 509 #define define_one_driver_ro(_name, show)                       \
 510         static struct cpuidle_driver_attr attr_driver_##_name = \
 511                 __ATTR(_name, 0444, show, NULL)
 512
 513 struct cpuidle_driver_kobj {
 514         struct cpuidle_driver *drv;
 515         struct completion kobj_unregister;
 516         struct kobject kobj;
 517 };
 518
 519 struct cpuidle_driver_attr {
 520         struct attribute attr;
 521         ssize_t (*show)(struct cpuidle_driver *, char *);
 522         ssize_t (*store)(struct cpuidle_driver *, const char *, size_t);
 523 };
 524
 525 static ssize_t show_driver_name(struct cpuidle_driver *drv, char *buf)
 526 {
 527         ssize_t ret;
 528
 529         spin_lock(&cpuidle_driver_lock);
 530         ret = sprintf(buf, "%s\n", drv ? drv->name : "none");
 531         spin_unlock(&cpuidle_driver_lock);
 532
 533         return ret;
 534 }
 535
 536 static void cpuidle_driver_sysfs_release(struct kobject *kobj)
 537 {
 538         struct cpuidle_driver_kobj *driver_kobj = kobj_to_driver_kobj(kobj);
 539         complete(&driver_kobj->kobj_unregister);
 540 }
 541
 542 static ssize_t cpuidle_driver_show(struct kobject *kobj, struct attribute *attr,
 543                                    char *buf)
 544 {
 545         int ret = -EIO;
 546         struct cpuidle_driver_kobj *driver_kobj = kobj_to_driver_kobj(kobj);
 547         struct cpuidle_driver_attr *dattr = attr_to_driver_attr(attr);
 548
 549         if (dattr->show)
 550                 ret = dattr->show(driver_kobj->drv, buf);
 551
 552         return ret;
 553 }
 554
 555 static ssize_t cpuidle_driver_store(struct kobject *kobj, struct attribute *attr,
 556                                     const char *buf, size_t size)
 557 {
 558         int ret = -EIO;
 559         struct cpuidle_driver_kobj *driver_kobj = kobj_to_driver_kobj(kobj);
 560         struct cpuidle_driver_attr *dattr = attr_to_driver_attr(attr);
 561
 562         if (dattr->store)
 563                 ret = dattr->store(driver_kobj->drv, buf, size);
 564
 565         return ret;
 566 }
 567
 568 define_one_driver_ro(name, show_driver_name);
 569
 570 static const struct sysfs_ops cpuidle_driver_sysfs_ops = {
 571         .show = cpuidle_driver_show,
 572         .store = cpuidle_driver_store,
 573 };
 574
 575 static struct attribute *cpuidle_driver_default_attrs[] = {
 576         &attr_driver_name.attr,
 577         NULL
 578 };
 579
 580 static struct kobj_type ktype_driver_cpuidle = {
 581         .sysfs_ops = &cpuidle_driver_sysfs_ops,
 582         .default_attrs = cpuidle_driver_default_attrs,
 583         .release = cpuidle_driver_sysfs_release,
 584 };
 585
 586 /**
 587  * cpuidle_add_driver_sysfs - adds the driver name sysfs attribute
 588  * @device: the target device
 589  */
 590 static int cpuidle_add_driver_sysfs(struct cpuidle_device *dev)
 591 {
 592         struct cpuidle_driver_kobj *kdrv;
 593         struct cpuidle_device_kobj *kdev = dev->kobj_dev;
 594         struct cpuidle_driver *drv = cpuidle_get_cpu_driver(dev);
 595         int ret;
 596
 597         kdrv = kzalloc(sizeof(*kdrv), GFP_KERNEL);
 598         if (!kdrv)
 599                 return -ENOMEM;
 600
 601         kdrv->drv = drv;
 602         init_completion(&kdrv->kobj_unregister);
 603
 604         ret = kobject_init_and_add(&kdrv->kobj, &ktype_driver_cpuidle,
 605                                    &kdev->kobj, "driver");
 606         if (ret) {
 607                 kfree(kdrv);
 608                 return ret;
 609         }
 610
 611         kobject_uevent(&kdrv->kobj, KOBJ_ADD);
 612         dev->kobj_driver = kdrv;
 613
 614         return ret;
 615 }
 616
 617 /**
 618  * cpuidle_remove_driver_sysfs - removes the driver name sysfs attribute
 619  * @device: the target device
 620  */
 621 static void cpuidle_remove_driver_sysfs(struct cpuidle_device *dev)
 622 {
 623         struct cpuidle_driver_kobj *kdrv = dev->kobj_driver;
 624         kobject_put(&kdrv->kobj);
 625         wait_for_completion(&kdrv->kobj_unregister);
 626         kfree(kdrv);
 627 }
 628 #else
 629 static inline int cpuidle_add_driver_sysfs(struct cpuidle_device *dev)
 630 {
 631         return 0;
 632 }
 633
 634 static inline void cpuidle_remove_driver_sysfs(struct cpuidle_device *dev)
 635 {
 636         ;
 637 }
 638 #endif
 639
 640 /**
 641  * cpuidle_add_device_sysfs - adds device specific sysfs attributes
 642  * @device: the target device
 643  */
 644 int cpuidle_add_device_sysfs(struct cpuidle_device *device)
 645 {
 646         int ret;
 647
 648         ret = cpuidle_add_state_sysfs(device);
 649         if (ret)
 650                 return ret;
 651
 652         ret = cpuidle_add_driver_sysfs(device);
 653         if (ret)
 654                 cpuidle_remove_state_sysfs(device);
 655         return ret;
 656 }
 657
 658 /**
 659  * cpuidle_remove_device_sysfs : removes device specific sysfs attributes
 660  * @device : the target device
 661  */
 662 void cpuidle_remove_device_sysfs(struct cpuidle_device *device)
 663 {
 664         cpuidle_remove_driver_sysfs(device);
 665         cpuidle_remove_state_sysfs(device);
 666 }
 667
 668 /**
 669  * cpuidle_add_sysfs - creates a sysfs instance for the target device
 670  * @dev: the target device
 671  */
 672 int cpuidle_add_sysfs(struct cpuidle_device *dev)
 673 {
 674         struct cpuidle_device_kobj *kdev;
 675         struct device *cpu_dev = get_cpu_device((unsigned long)dev->cpu);
 676         int error;
 677
 678         /*
 679          * Return if cpu_device is not setup for this CPU.
 680          *
 681          * This could happen if the arch did not set up cpu_device
 682          * since this CPU is not in cpu_present mask and the
 683          * driver did not send a correct CPU mask during registration.
 684          * Without this check we would end up passing bogus
 685          * value for &cpu_dev->kobj in kobject_init_and_add()
 686          */
 687         if (!cpu_dev)
 688                 return -ENODEV;
 689
 690         kdev = kzalloc(sizeof(*kdev), GFP_KERNEL);
 691         if (!kdev)
 692                 return -ENOMEM;
 693         kdev->dev = dev;
 694         dev->kobj_dev = kdev;
 695
 696         init_completion(&kdev->kobj_unregister);
 697
 698         error = kobject_init_and_add(&kdev->kobj, &ktype_cpuidle, &cpu_dev->kobj,
 699                                    "cpuidle");
 700         if (error) {
 701                 kfree(kdev);
 702                 return error;
 703         }
 704
 705         kobject_uevent(&kdev->kobj, KOBJ_ADD);
 706
 707         return 0;
 708 }
 709
 710 /**
 711  * cpuidle_remove_sysfs - deletes a sysfs instance on the target device
 712  * @dev: the target device
 713  */
 714 void cpuidle_remove_sysfs(struct cpuidle_device *dev)
 715 {
 716         struct cpuidle_device_kobj *kdev = dev->kobj_dev;
 717
 718         kobject_put(&kdev->kobj);
 719         wait_for_completion(&kdev->kobj_unregister);
 720         kfree(kdev);
 721 }