drivers/cpuidle/sysfs.c

   1 /*
   2  * sysfs.c - sysfs support
   3  *
   4  * (C) 2006-2007 Shaohua Li <[email protected]>
   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 ssize_t show_available_governors(struct device *dev,
  22                                         struct device_attribute *attr,
  23                                         char *buf)
  24 {
  25         ssize_t i = 0;
  26         struct cpuidle_governor *tmp;
  27
  28         mutex_lock(&cpuidle_lock);
  29         list_for_each_entry(tmp, &cpuidle_governors, governor_list) {
  30                 if (i >= (ssize_t) (PAGE_SIZE - (CPUIDLE_NAME_LEN + 2)))
  31                         goto out;
  32
  33                 i += scnprintf(&buf[i], CPUIDLE_NAME_LEN + 1, "%s ", tmp->name);
  34         }
  35
  36 out:
  37         i+= sprintf(&buf[i], "\n");
  38         mutex_unlock(&cpuidle_lock);
  39         return i;
  40 }
  41
  42 static ssize_t show_current_driver(struct device *dev,
  43                                    struct device_attribute *attr,
  44                                    char *buf)
  45 {
  46         ssize_t ret;
  47         struct cpuidle_driver *drv;
  48
  49         spin_lock(&cpuidle_driver_lock);
  50         drv = cpuidle_get_driver();
  51         if (drv)
  52                 ret = sprintf(buf, "%s\n", drv->name);
  53         else
  54                 ret = sprintf(buf, "none\n");
  55         spin_unlock(&cpuidle_driver_lock);
  56
  57         return ret;
  58 }
  59
  60 static ssize_t show_current_governor(struct device *dev,
  61                                      struct device_attribute *attr,
  62                                      char *buf)
  63 {
  64         ssize_t ret;
  65
  66         mutex_lock(&cpuidle_lock);
  67         if (cpuidle_curr_governor)
  68                 ret = sprintf(buf, "%s\n", cpuidle_curr_governor->name);
  69         else
  70                 ret = sprintf(buf, "none\n");
  71         mutex_unlock(&cpuidle_lock);
  72
  73         return ret;
  74 }
  75
  76 static ssize_t store_current_governor(struct device *dev,
  77                                       struct device_attribute *attr,
  78                                       const char *buf, size_t count)
  79 {
  80         char gov_name[CPUIDLE_NAME_LEN + 1];
  81         int ret;
  82         struct cpuidle_governor *gov;
  83
  84         ret = sscanf(buf, "%" __stringify(CPUIDLE_NAME_LEN) "s", gov_name);
  85         if (ret != 1)
  86                 return -EINVAL;
  87
  88         mutex_lock(&cpuidle_lock);
  89         ret = -EINVAL;
  90         list_for_each_entry(gov, &cpuidle_governors, governor_list) {
  91                 if (!strncmp(gov->name, gov_name, CPUIDLE_NAME_LEN)) {
  92                         ret = cpuidle_switch_governor(gov);
  93                         break;
  94                 }
  95         }
  96         mutex_unlock(&cpuidle_lock);
  97
  98         return ret ? ret : count;
  99 }
 100
 101 static DEVICE_ATTR(available_governors, 0444, show_available_governors, NULL);
 102 static DEVICE_ATTR(current_driver, 0444, show_current_driver, NULL);
 103 static DEVICE_ATTR(current_governor, 0644, show_current_governor,
 104                                    store_current_governor);
 105 static DEVICE_ATTR(current_governor_ro, 0444, show_current_governor, NULL);
 106
 107 static struct attribute *cpuidle_attrs[] = {
 108         &dev_attr_available_governors.attr,
 109         &dev_attr_current_driver.attr,
 110         &dev_attr_current_governor.attr,
 111         &dev_attr_current_governor_ro.attr,
 112         NULL
 113 };
 114
 115 static struct attribute_group cpuidle_attr_group = {
 116         .attrs = cpuidle_attrs,
 117         .name = "cpuidle",
 118 };
 119
 120 /**
 121  * cpuidle_add_interface - add CPU global sysfs attributes
 122  * @dev: the target device
 123  */
 124 int cpuidle_add_interface(struct device *dev)
 125 {
 126         return sysfs_create_group(&dev->kobj, &cpuidle_attr_group);
 127 }
 128
 129 /**
 130  * cpuidle_remove_interface - remove CPU global sysfs attributes
 131  * @dev: the target device
 132  */
 133 void cpuidle_remove_interface(struct device *dev)
 134 {
 135         sysfs_remove_group(&dev->kobj, &cpuidle_attr_group);
 136 }
 137
 138 struct cpuidle_attr {
 139         struct attribute attr;
 140         ssize_t (*show)(struct cpuidle_device *, char *);
 141         ssize_t (*store)(struct cpuidle_device *, const char *, size_t count);
 142 };
 143
 144 #define attr_to_cpuidleattr(a) container_of(a, struct cpuidle_attr, attr)
 145
 146 struct cpuidle_device_kobj {
 147         struct cpuidle_device *dev;
 148         struct completion kobj_unregister;
 149         struct kobject kobj;
 150 };
 151
 152 static inline struct cpuidle_device *to_cpuidle_device(struct kobject *kobj)
 153 {
 154         struct cpuidle_device_kobj *kdev =
 155                 container_of(kobj, struct cpuidle_device_kobj, kobj);
 156
 157         return kdev->dev;
 158 }
 159
 160 static ssize_t cpuidle_show(struct kobject *kobj, struct attribute *attr,
 161                             char *buf)
 162 {
 163         int ret = -EIO;
 164         struct cpuidle_device *dev = to_cpuidle_device(kobj);
 165         struct cpuidle_attr *cattr = attr_to_cpuidleattr(attr);
 166
 167         if (cattr->show) {
 168                 mutex_lock(&cpuidle_lock);
 169                 ret = cattr->show(dev, buf);
 170                 mutex_unlock(&cpuidle_lock);
 171         }
 172         return ret;
 173 }
 174
 175 static ssize_t cpuidle_store(struct kobject *kobj, struct attribute *attr,
 176                              const char *buf, size_t count)
 177 {
 178         int ret = -EIO;
 179         struct cpuidle_device *dev = to_cpuidle_device(kobj);
 180         struct cpuidle_attr *cattr = attr_to_cpuidleattr(attr);
 181
 182         if (cattr->store) {
 183                 mutex_lock(&cpuidle_lock);
 184                 ret = cattr->store(dev, buf, count);
 185                 mutex_unlock(&cpuidle_lock);
 186         }
 187         return ret;
 188 }
 189
 190 static const struct sysfs_ops cpuidle_sysfs_ops = {
 191         .show = cpuidle_show,
 192         .store = cpuidle_store,
 193 };
 194
 195 static void cpuidle_sysfs_release(struct kobject *kobj)
 196 {
 197         struct cpuidle_device_kobj *kdev =
 198                 container_of(kobj, struct cpuidle_device_kobj, kobj);
 199
 200         complete(&kdev->kobj_unregister);
 201 }
 202
 203 static struct kobj_type ktype_cpuidle = {
 204         .sysfs_ops = &cpuidle_sysfs_ops,
 205         .release = cpuidle_sysfs_release,
 206 };
 207
 208 struct cpuidle_state_attr {
 209         struct attribute attr;
 210         ssize_t (*show)(struct cpuidle_state *, \
 211                                         struct cpuidle_state_usage *, char *);
 212         ssize_t (*store)(struct cpuidle_state *, \
 213                         struct cpuidle_state_usage *, const char *, size_t);
 214 };
 215
 216 #define define_one_state_ro(_name, show) \
 217 static struct cpuidle_state_attr attr_##_name = __ATTR(_name, 0444, show, NULL)
 218
 219 #define define_one_state_rw(_name, show, store) \
 220 static struct cpuidle_state_attr attr_##_name = __ATTR(_name, 0644, show, store)
 221
 222 #define define_show_state_function(_name) \
 223 static ssize_t show_state_##_name(struct cpuidle_state *state, \
 224                          struct cpuidle_state_usage *state_usage, char *buf) \
 225 { \
 226         return sprintf(buf, "%u\n", state->_name);\
 227 }
 228
 229 #define define_show_state_ull_function(_name) \
 230 static ssize_t show_state_##_name(struct cpuidle_state *state, \
 231                                   struct cpuidle_state_usage *state_usage, \
 232                                   char *buf)                            \
 233 { \
 234         return sprintf(buf, "%llu\n", state_usage->_name);\
 235 }
 236
 237 #define define_show_state_str_function(_name) \
 238 static ssize_t show_state_##_name(struct cpuidle_state *state, \
 239                                   struct cpuidle_state_usage *state_usage, \
 240                                   char *buf)                            \
 241 { \
 242         if (state->_name[0] == '\0')\
 243                 return sprintf(buf, "<null>\n");\
 244         return sprintf(buf, "%s\n", state->_name);\
 245 }
 246
 247 #define define_show_state_time_function(_name) \
 248 static ssize_t show_state_##_name(struct cpuidle_state *state, \
 249                                   struct cpuidle_state_usage *state_usage, \
 250                                   char *buf) \
 251 { \
 252         return sprintf(buf, "%llu\n", ktime_to_us(state->_name##_ns)); \
 253 }
 254
 255 define_show_state_time_function(exit_latency)
 256 define_show_state_time_function(target_residency)
 257 define_show_state_function(power_usage)
 258 define_show_state_ull_function(usage)
 259 define_show_state_ull_function(rejected)
 260 define_show_state_str_function(name)
 261 define_show_state_str_function(desc)
 262 define_show_state_ull_function(above)
 263 define_show_state_ull_function(below)
 264
 265 static ssize_t show_state_time(struct cpuidle_state *state,
 266                                struct cpuidle_state_usage *state_usage,
 267                                char *buf)
 268 {
 269         return sprintf(buf, "%llu\n", ktime_to_us(state_usage->time_ns));
 270 }
 271
 272 static ssize_t show_state_disable(struct cpuidle_state *state,
 273                                   struct cpuidle_state_usage *state_usage,
 274                                   char *buf)
 275 {
 276         return sprintf(buf, "%llu\n",
 277                        state_usage->disable & CPUIDLE_STATE_DISABLED_BY_USER);
 278 }
 279
 280 static ssize_t store_state_disable(struct cpuidle_state *state,
 281                                    struct cpuidle_state_usage *state_usage,
 282                                    const char *buf, size_t size)
 283 {
 284         unsigned int value;
 285         int err;
 286
 287         if (!capable(CAP_SYS_ADMIN))
 288                 return -EPERM;
 289
 290         err = kstrtouint(buf, 0, &value);
 291         if (err)
 292                 return err;
 293
 294         if (value)
 295                 state_usage->disable |= CPUIDLE_STATE_DISABLED_BY_USER;
 296         else
 297                 state_usage->disable &= ~CPUIDLE_STATE_DISABLED_BY_USER;
 298
 299         return size;
 300 }
 301
 302 static ssize_t show_state_default_status(struct cpuidle_state *state,
 303                                           struct cpuidle_state_usage *state_usage,
 304                                           char *buf)
 305 {
 306         return sprintf(buf, "%s\n",
 307                        state->flags & CPUIDLE_FLAG_OFF ? "disabled" : "enabled");
 308 }
 309
 310 define_one_state_ro(name, show_state_name);
 311 define_one_state_ro(desc, show_state_desc);
 312 define_one_state_ro(latency, show_state_exit_latency);
 313 define_one_state_ro(residency, show_state_target_residency);
 314 define_one_state_ro(power, show_state_power_usage);
 315 define_one_state_ro(usage, show_state_usage);
 316 define_one_state_ro(rejected, show_state_rejected);
 317 define_one_state_ro(time, show_state_time);
 318 define_one_state_rw(disable, show_state_disable, store_state_disable);
 319 define_one_state_ro(above, show_state_above);
 320 define_one_state_ro(below, show_state_below);
 321 define_one_state_ro(default_status, show_state_default_status);
 322
 323 static struct attribute *cpuidle_state_default_attrs[] = {
 324         &attr_name.attr,
 325         &attr_desc.attr,
 326         &attr_latency.attr,
 327         &attr_residency.attr,
 328         &attr_power.attr,
 329         &attr_usage.attr,
 330         &attr_rejected.attr,
 331         &attr_time.attr,
 332         &attr_disable.attr,
 333         &attr_above.attr,
 334         &attr_below.attr,
 335         &attr_default_status.attr,
 336         NULL
 337 };
 338
 339 struct cpuidle_state_kobj {
 340         struct cpuidle_state *state;
 341         struct cpuidle_state_usage *state_usage;
 342         struct completion kobj_unregister;
 343         struct kobject kobj;
 344         struct cpuidle_device *device;
 345 };
 346
 347 #ifdef CONFIG_SUSPEND
 348 #define define_show_state_s2idle_ull_function(_name) \
 349 static ssize_t show_state_s2idle_##_name(struct cpuidle_state *state, \
 350                                          struct cpuidle_state_usage *state_usage, \
 351                                          char *buf)                             \
 352 { \
 353         return sprintf(buf, "%llu\n", state_usage->s2idle_##_name);\
 354 }
 355
 356 define_show_state_s2idle_ull_function(usage);
 357 define_show_state_s2idle_ull_function(time);
 358
 359 #define define_one_state_s2idle_ro(_name, show) \
 360 static struct cpuidle_state_attr attr_s2idle_##_name = \
 361         __ATTR(_name, 0444, show, NULL)
 362
 363 define_one_state_s2idle_ro(usage, show_state_s2idle_usage);
 364 define_one_state_s2idle_ro(time, show_state_s2idle_time);
 365
 366 static struct attribute *cpuidle_state_s2idle_attrs[] = {
 367         &attr_s2idle_usage.attr,
 368         &attr_s2idle_time.attr,
 369         NULL
 370 };
 371
 372 static const struct attribute_group cpuidle_state_s2idle_group = {
 373         .name   = "s2idle",
 374         .attrs  = cpuidle_state_s2idle_attrs,
 375 };
 376
 377 static void cpuidle_add_s2idle_attr_group(struct cpuidle_state_kobj *kobj)
 378 {
 379         int ret;
 380
 381         if (!kobj->state->enter_s2idle)
 382                 return;
 383
 384         ret = sysfs_create_group(&kobj->kobj, &cpuidle_state_s2idle_group);
 385         if (ret)
 386                 pr_debug("%s: sysfs attribute group not created\n", __func__);
 387 }
 388
 389 static void cpuidle_remove_s2idle_attr_group(struct cpuidle_state_kobj *kobj)
 390 {
 391         if (kobj->state->enter_s2idle)
 392                 sysfs_remove_group(&kobj->kobj, &cpuidle_state_s2idle_group);
 393 }
 394 #else
 395 static inline void cpuidle_add_s2idle_attr_group(struct cpuidle_state_kobj *kobj) { }
 396 static inline void cpuidle_remove_s2idle_attr_group(struct cpuidle_state_kobj *kobj) { }
 397 #endif /* CONFIG_SUSPEND */
 398
 399 #define kobj_to_state_obj(k) container_of(k, struct cpuidle_state_kobj, kobj)
 400 #define kobj_to_state(k) (kobj_to_state_obj(k)->state)
 401 #define kobj_to_state_usage(k) (kobj_to_state_obj(k)->state_usage)
 402 #define kobj_to_device(k) (kobj_to_state_obj(k)->device)
 403 #define attr_to_stateattr(a) container_of(a, struct cpuidle_state_attr, attr)
 404
 405 static ssize_t cpuidle_state_show(struct kobject *kobj, struct attribute *attr,
 406                                   char *buf)
 407 {
 408         int ret = -EIO;
 409         struct cpuidle_state *state = kobj_to_state(kobj);
 410         struct cpuidle_state_usage *state_usage = kobj_to_state_usage(kobj);
 411         struct cpuidle_state_attr *cattr = attr_to_stateattr(attr);
 412
 413         if (cattr->show)
 414                 ret = cattr->show(state, state_usage, buf);
 415
 416         return ret;
 417 }
 418
 419 static ssize_t cpuidle_state_store(struct kobject *kobj, struct attribute *attr,
 420                                    const char *buf, size_t size)
 421 {
 422         int ret = -EIO;
 423         struct cpuidle_state *state = kobj_to_state(kobj);
 424         struct cpuidle_state_usage *state_usage = kobj_to_state_usage(kobj);
 425         struct cpuidle_state_attr *cattr = attr_to_stateattr(attr);
 426         struct cpuidle_device *dev = kobj_to_device(kobj);
 427
 428         if (cattr->store)
 429                 ret = cattr->store(state, state_usage, buf, size);
 430
 431         /* reset poll time cache */
 432         dev->poll_limit_ns = 0;
 433
 434         return ret;
 435 }
 436
 437 static const struct sysfs_ops cpuidle_state_sysfs_ops = {
 438         .show = cpuidle_state_show,
 439         .store = cpuidle_state_store,
 440 };
 441
 442 static void cpuidle_state_sysfs_release(struct kobject *kobj)
 443 {
 444         struct cpuidle_state_kobj *state_obj = kobj_to_state_obj(kobj);
 445
 446         complete(&state_obj->kobj_unregister);
 447 }
 448
 449 static struct kobj_type ktype_state_cpuidle = {
 450         .sysfs_ops = &cpuidle_state_sysfs_ops,
 451         .default_attrs = cpuidle_state_default_attrs,
 452         .release = cpuidle_state_sysfs_release,
 453 };
 454
 455 static inline void cpuidle_free_state_kobj(struct cpuidle_device *device, int i)
 456 {
 457         cpuidle_remove_s2idle_attr_group(device->kobjs[i]);
 458         kobject_put(&device->kobjs[i]->kobj);
 459         wait_for_completion(&device->kobjs[i]->kobj_unregister);
 460         kfree(device->kobjs[i]);
 461         device->kobjs[i] = NULL;
 462 }
 463
 464 /**
 465  * cpuidle_add_state_sysfs - adds cpuidle states sysfs attributes
 466  * @device: the target device
 467  */
 468 static int cpuidle_add_state_sysfs(struct cpuidle_device *device)
 469 {
 470         int i, ret = -ENOMEM;
 471         struct cpuidle_state_kobj *kobj;
 472         struct cpuidle_device_kobj *kdev = device->kobj_dev;
 473         struct cpuidle_driver *drv = cpuidle_get_cpu_driver(device);
 474
 475         /* state statistics */
 476         for (i = 0; i < drv->state_count; i++) {
 477                 kobj = kzalloc(sizeof(struct cpuidle_state_kobj), GFP_KERNEL);
 478                 if (!kobj) {
 479                         ret = -ENOMEM;
 480                         goto error_state;
 481                 }
 482                 kobj->state = &drv->states[i];
 483                 kobj->state_usage = &device->states_usage[i];
 484                 kobj->device = device;
 485                 init_completion(&kobj->kobj_unregister);
 486
 487                 ret = kobject_init_and_add(&kobj->kobj, &ktype_state_cpuidle,
 488                                            &kdev->kobj, "state%d", i);
 489                 if (ret) {
 490                         kobject_put(&kobj->kobj);
 491                         goto error_state;
 492                 }
 493                 cpuidle_add_s2idle_attr_group(kobj);
 494                 kobject_uevent(&kobj->kobj, KOBJ_ADD);
 495                 device->kobjs[i] = kobj;
 496         }
 497
 498         return 0;
 499
 500 error_state:
 501         for (i = i - 1; i >= 0; i--)
 502                 cpuidle_free_state_kobj(device, i);
 503         return ret;
 504 }
 505
 506 /**
 507  * cpuidle_remove_driver_sysfs - removes the cpuidle states sysfs attributes
 508  * @device: the target device
 509  */
 510 static void cpuidle_remove_state_sysfs(struct cpuidle_device *device)
 511 {
 512         struct cpuidle_driver *drv = cpuidle_get_cpu_driver(device);
 513         int i;
 514
 515         for (i = 0; i < drv->state_count; i++)
 516                 cpuidle_free_state_kobj(device, i);
 517 }
 518
 519 #ifdef CONFIG_CPU_IDLE_MULTIPLE_DRIVERS
 520 #define kobj_to_driver_kobj(k) container_of(k, struct cpuidle_driver_kobj, kobj)
 521 #define attr_to_driver_attr(a) container_of(a, struct cpuidle_driver_attr, attr)
 522
 523 #define define_one_driver_ro(_name, show)                       \
 524         static struct cpuidle_driver_attr attr_driver_##_name = \
 525                 __ATTR(_name, 0444, show, NULL)
 526
 527 struct cpuidle_driver_kobj {
 528         struct cpuidle_driver *drv;
 529         struct completion kobj_unregister;
 530         struct kobject kobj;
 531 };
 532
 533 struct cpuidle_driver_attr {
 534         struct attribute attr;
 535         ssize_t (*show)(struct cpuidle_driver *, char *);
 536         ssize_t (*store)(struct cpuidle_driver *, const char *, size_t);
 537 };
 538
 539 static ssize_t show_driver_name(struct cpuidle_driver *drv, char *buf)
 540 {
 541         ssize_t ret;
 542
 543         spin_lock(&cpuidle_driver_lock);
 544         ret = sprintf(buf, "%s\n", drv ? drv->name : "none");
 545         spin_unlock(&cpuidle_driver_lock);
 546
 547         return ret;
 548 }
 549
 550 static void cpuidle_driver_sysfs_release(struct kobject *kobj)
 551 {
 552         struct cpuidle_driver_kobj *driver_kobj = kobj_to_driver_kobj(kobj);
 553         complete(&driver_kobj->kobj_unregister);
 554 }
 555
 556 static ssize_t cpuidle_driver_show(struct kobject *kobj, struct attribute *attr,
 557                                    char *buf)
 558 {
 559         int ret = -EIO;
 560         struct cpuidle_driver_kobj *driver_kobj = kobj_to_driver_kobj(kobj);
 561         struct cpuidle_driver_attr *dattr = attr_to_driver_attr(attr);
 562
 563         if (dattr->show)
 564                 ret = dattr->show(driver_kobj->drv, buf);
 565
 566         return ret;
 567 }
 568
 569 static ssize_t cpuidle_driver_store(struct kobject *kobj, struct attribute *attr,
 570                                     const char *buf, size_t size)
 571 {
 572         int ret = -EIO;
 573         struct cpuidle_driver_kobj *driver_kobj = kobj_to_driver_kobj(kobj);
 574         struct cpuidle_driver_attr *dattr = attr_to_driver_attr(attr);
 575
 576         if (dattr->store)
 577                 ret = dattr->store(driver_kobj->drv, buf, size);
 578
 579         return ret;
 580 }
 581
 582 define_one_driver_ro(name, show_driver_name);
 583
 584 static const struct sysfs_ops cpuidle_driver_sysfs_ops = {
 585         .show = cpuidle_driver_show,
 586         .store = cpuidle_driver_store,
 587 };
 588
 589 static struct attribute *cpuidle_driver_default_attrs[] = {
 590         &attr_driver_name.attr,
 591         NULL
 592 };
 593
 594 static struct kobj_type ktype_driver_cpuidle = {
 595         .sysfs_ops = &cpuidle_driver_sysfs_ops,
 596         .default_attrs = cpuidle_driver_default_attrs,
 597         .release = cpuidle_driver_sysfs_release,
 598 };
 599
 600 /**
 601  * cpuidle_add_driver_sysfs - adds the driver name sysfs attribute
 602  * @dev: the target device
 603  */
 604 static int cpuidle_add_driver_sysfs(struct cpuidle_device *dev)
 605 {
 606         struct cpuidle_driver_kobj *kdrv;
 607         struct cpuidle_device_kobj *kdev = dev->kobj_dev;
 608         struct cpuidle_driver *drv = cpuidle_get_cpu_driver(dev);
 609         int ret;
 610
 611         kdrv = kzalloc(sizeof(*kdrv), GFP_KERNEL);
 612         if (!kdrv)
 613                 return -ENOMEM;
 614
 615         kdrv->drv = drv;
 616         init_completion(&kdrv->kobj_unregister);
 617
 618         ret = kobject_init_and_add(&kdrv->kobj, &ktype_driver_cpuidle,
 619                                    &kdev->kobj, "driver");
 620         if (ret) {
 621                 kobject_put(&kdrv->kobj);
 622                 return ret;
 623         }
 624
 625         kobject_uevent(&kdrv->kobj, KOBJ_ADD);
 626         dev->kobj_driver = kdrv;
 627
 628         return ret;
 629 }
 630
 631 /**
 632  * cpuidle_remove_driver_sysfs - removes the driver name sysfs attribute
 633  * @dev: the target device
 634  */
 635 static void cpuidle_remove_driver_sysfs(struct cpuidle_device *dev)
 636 {
 637         struct cpuidle_driver_kobj *kdrv = dev->kobj_driver;
 638         kobject_put(&kdrv->kobj);
 639         wait_for_completion(&kdrv->kobj_unregister);
 640         kfree(kdrv);
 641 }
 642 #else
 643 static inline int cpuidle_add_driver_sysfs(struct cpuidle_device *dev)
 644 {
 645         return 0;
 646 }
 647
 648 static inline void cpuidle_remove_driver_sysfs(struct cpuidle_device *dev)
 649 {
 650         ;
 651 }
 652 #endif
 653
 654 /**
 655  * cpuidle_add_device_sysfs - adds device specific sysfs attributes
 656  * @device: the target device
 657  */
 658 int cpuidle_add_device_sysfs(struct cpuidle_device *device)
 659 {
 660         int ret;
 661
 662         ret = cpuidle_add_state_sysfs(device);
 663         if (ret)
 664                 return ret;
 665
 666         ret = cpuidle_add_driver_sysfs(device);
 667         if (ret)
 668                 cpuidle_remove_state_sysfs(device);
 669         return ret;
 670 }
 671
 672 /**
 673  * cpuidle_remove_device_sysfs : removes device specific sysfs attributes
 674  * @device : the target device
 675  */
 676 void cpuidle_remove_device_sysfs(struct cpuidle_device *device)
 677 {
 678         cpuidle_remove_driver_sysfs(device);
 679         cpuidle_remove_state_sysfs(device);
 680 }
 681
 682 /**
 683  * cpuidle_add_sysfs - creates a sysfs instance for the target device
 684  * @dev: the target device
 685  */
 686 int cpuidle_add_sysfs(struct cpuidle_device *dev)
 687 {
 688         struct cpuidle_device_kobj *kdev;
 689         struct device *cpu_dev = get_cpu_device((unsigned long)dev->cpu);
 690         int error;
 691
 692         /*
 693          * Return if cpu_device is not setup for this CPU.
 694          *
 695          * This could happen if the arch did not set up cpu_device
 696          * since this CPU is not in cpu_present mask and the
 697          * driver did not send a correct CPU mask during registration.
 698          * Without this check we would end up passing bogus
 699          * value for &cpu_dev->kobj in kobject_init_and_add()
 700          */
 701         if (!cpu_dev)
 702                 return -ENODEV;
 703
 704         kdev = kzalloc(sizeof(*kdev), GFP_KERNEL);
 705         if (!kdev)
 706                 return -ENOMEM;
 707         kdev->dev = dev;
 708         dev->kobj_dev = kdev;
 709
 710         init_completion(&kdev->kobj_unregister);
 711
 712         error = kobject_init_and_add(&kdev->kobj, &ktype_cpuidle, &cpu_dev->kobj,
 713                                    "cpuidle");
 714         if (error) {
 715                 kobject_put(&kdev->kobj);
 716                 return error;
 717         }
 718
 719         kobject_uevent(&kdev->kobj, KOBJ_ADD);
 720
 721         return 0;
 722 }
 723
 724 /**
 725  * cpuidle_remove_sysfs - deletes a sysfs instance on the target device
 726  * @dev: the target device
 727  */
 728 void cpuidle_remove_sysfs(struct cpuidle_device *dev)
 729 {
 730         struct cpuidle_device_kobj *kdev = dev->kobj_dev;
 731
 732         kobject_put(&kdev->kobj);
 733         wait_for_completion(&kdev->kobj_unregister);
 734         kfree(kdev);
 735 }