drivers/powercap/powercap_sys.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * Power capping class
   4  * Copyright (c) 2013, Intel Corporation.
   5  */
   6
   7 #include <linux/module.h>
   8 #include <linux/device.h>
   9 #include <linux/err.h>
  10 #include <linux/kstrtox.h>
  11 #include <linux/slab.h>
  12 #include <linux/powercap.h>
  13
  14 #define to_powercap_zone(n) container_of(n, struct powercap_zone, dev)
  15 #define to_powercap_control_type(n) \
  16                         container_of(n, struct powercap_control_type, dev)
  17
  18 /* Power zone show function */
  19 #define define_power_zone_show(_attr)           \
  20 static ssize_t _attr##_show(struct device *dev, \
  21                                         struct device_attribute *dev_attr,\
  22                                         char *buf) \
  23 { \
  24         u64 value; \
  25         ssize_t len = -EINVAL; \
  26         struct powercap_zone *power_zone = to_powercap_zone(dev); \
  27         \
  28         if (power_zone->ops->get_##_attr) { \
  29                 if (!power_zone->ops->get_##_attr(power_zone, &value)) \
  30                         len = sprintf(buf, "%lld\n", value); \
  31         } \
  32         \
  33         return len; \
  34 }
  35
  36 /* The only meaningful input is 0 (reset), others are silently ignored */
  37 #define define_power_zone_store(_attr)          \
  38 static ssize_t _attr##_store(struct device *dev,\
  39                                 struct device_attribute *dev_attr, \
  40                                 const char *buf, size_t count) \
  41 { \
  42         int err; \
  43         struct powercap_zone *power_zone = to_powercap_zone(dev); \
  44         u64 value; \
  45         \
  46         err = kstrtoull(buf, 10, &value); \
  47         if (err) \
  48                 return -EINVAL; \
  49         if (value) \
  50                 return count; \
  51         if (power_zone->ops->reset_##_attr) { \
  52                 if (!power_zone->ops->reset_##_attr(power_zone)) \
  53                         return count; \
  54         } \
  55         \
  56         return -EINVAL; \
  57 }
  58
  59 /* Power zone constraint show function */
  60 #define define_power_zone_constraint_show(_attr) \
  61 static ssize_t show_constraint_##_attr(struct device *dev, \
  62                                 struct device_attribute *dev_attr,\
  63                                 char *buf) \
  64 { \
  65         u64 value; \
  66         ssize_t len = -ENODATA; \
  67         struct powercap_zone *power_zone = to_powercap_zone(dev); \
  68         int id; \
  69         struct powercap_zone_constraint *pconst;\
  70         \
  71         if (!sscanf(dev_attr->attr.name, "constraint_%d_", &id)) \
  72                 return -EINVAL; \
  73         if (id >= power_zone->const_id_cnt)     \
  74                 return -EINVAL; \
  75         pconst = &power_zone->constraints[id]; \
  76         if (pconst && pconst->ops && pconst->ops->get_##_attr) { \
  77                 if (!pconst->ops->get_##_attr(power_zone, id, &value)) \
  78                         len = sprintf(buf, "%lld\n", value); \
  79         } \
  80         \
  81         return len; \
  82 }
  83
  84 /* Power zone constraint store function */
  85 #define define_power_zone_constraint_store(_attr) \
  86 static ssize_t store_constraint_##_attr(struct device *dev,\
  87                                 struct device_attribute *dev_attr, \
  88                                 const char *buf, size_t count) \
  89 { \
  90         int err; \
  91         u64 value; \
  92         struct powercap_zone *power_zone = to_powercap_zone(dev); \
  93         int id; \
  94         struct powercap_zone_constraint *pconst;\
  95         \
  96         if (!sscanf(dev_attr->attr.name, "constraint_%d_", &id)) \
  97                 return -EINVAL; \
  98         if (id >= power_zone->const_id_cnt)     \
  99                 return -EINVAL; \
 100         pconst = &power_zone->constraints[id]; \
 101         err = kstrtoull(buf, 10, &value); \
 102         if (err) \
 103                 return -EINVAL; \
 104         if (pconst && pconst->ops && pconst->ops->set_##_attr) { \
 105                 if (!pconst->ops->set_##_attr(power_zone, id, value)) \
 106                         return count; \
 107         } \
 108         \
 109         return -ENODATA; \
 110 }
 111
 112 /* Power zone information callbacks */
 113 define_power_zone_show(power_uw);
 114 define_power_zone_show(max_power_range_uw);
 115 define_power_zone_show(energy_uj);
 116 define_power_zone_store(energy_uj);
 117 define_power_zone_show(max_energy_range_uj);
 118
 119 /* Power zone attributes */
 120 static DEVICE_ATTR_RO(max_power_range_uw);
 121 static DEVICE_ATTR_RO(power_uw);
 122 static DEVICE_ATTR_RO(max_energy_range_uj);
 123 static DEVICE_ATTR_RW(energy_uj);
 124
 125 /* Power zone constraint attributes callbacks */
 126 define_power_zone_constraint_show(power_limit_uw);
 127 define_power_zone_constraint_store(power_limit_uw);
 128 define_power_zone_constraint_show(time_window_us);
 129 define_power_zone_constraint_store(time_window_us);
 130 define_power_zone_constraint_show(max_power_uw);
 131 define_power_zone_constraint_show(min_power_uw);
 132 define_power_zone_constraint_show(max_time_window_us);
 133 define_power_zone_constraint_show(min_time_window_us);
 134
 135 /* For one time seeding of constraint device attributes */
 136 struct powercap_constraint_attr {
 137         struct device_attribute power_limit_attr;
 138         struct device_attribute time_window_attr;
 139         struct device_attribute max_power_attr;
 140         struct device_attribute min_power_attr;
 141         struct device_attribute max_time_window_attr;
 142         struct device_attribute min_time_window_attr;
 143         struct device_attribute name_attr;
 144 };
 145
 146 static struct powercap_constraint_attr
 147                                 constraint_attrs[MAX_CONSTRAINTS_PER_ZONE];
 148
 149 /* A list of powercap control_types */
 150 static LIST_HEAD(powercap_cntrl_list);
 151 /* Mutex to protect list of powercap control_types */
 152 static DEFINE_MUTEX(powercap_cntrl_list_lock);
 153
 154 #define POWERCAP_CONSTRAINT_NAME_LEN    30 /* Some limit to avoid overflow */
 155 static ssize_t show_constraint_name(struct device *dev,
 156                                 struct device_attribute *dev_attr,
 157                                 char *buf)
 158 {
 159         const char *name;
 160         struct powercap_zone *power_zone = to_powercap_zone(dev);
 161         int id;
 162         ssize_t len = -ENODATA;
 163         struct powercap_zone_constraint *pconst;
 164
 165         if (!sscanf(dev_attr->attr.name, "constraint_%d_", &id))
 166                 return -EINVAL;
 167         if (id >= power_zone->const_id_cnt)
 168                 return -EINVAL;
 169         pconst = &power_zone->constraints[id];
 170
 171         if (pconst && pconst->ops && pconst->ops->get_name) {
 172                 name = pconst->ops->get_name(power_zone, id);
 173                 if (name) {
 174                         sprintf(buf, "%.*s\n", POWERCAP_CONSTRAINT_NAME_LEN - 1,
 175                                 name);
 176                         len = strlen(buf);
 177                 }
 178         }
 179
 180         return len;
 181 }
 182
 183 static int create_constraint_attribute(int id, const char *name,
 184                                 int mode,
 185                                 struct device_attribute *dev_attr,
 186                                 ssize_t (*show)(struct device *,
 187                                         struct device_attribute *, char *),
 188                                 ssize_t (*store)(struct device *,
 189                                         struct device_attribute *,
 190                                 const char *, size_t)
 191                                 )
 192 {
 193
 194         dev_attr->attr.name = kasprintf(GFP_KERNEL, "constraint_%d_%s",
 195                                                                 id, name);
 196         if (!dev_attr->attr.name)
 197                 return -ENOMEM;
 198         dev_attr->attr.mode = mode;
 199         dev_attr->show = show;
 200         dev_attr->store = store;
 201
 202         return 0;
 203 }
 204
 205 static void free_constraint_attributes(void)
 206 {
 207         int i;
 208
 209         for (i = 0; i < MAX_CONSTRAINTS_PER_ZONE; ++i) {
 210                 kfree(constraint_attrs[i].power_limit_attr.attr.name);
 211                 kfree(constraint_attrs[i].time_window_attr.attr.name);
 212                 kfree(constraint_attrs[i].name_attr.attr.name);
 213                 kfree(constraint_attrs[i].max_power_attr.attr.name);
 214                 kfree(constraint_attrs[i].min_power_attr.attr.name);
 215                 kfree(constraint_attrs[i].max_time_window_attr.attr.name);
 216                 kfree(constraint_attrs[i].min_time_window_attr.attr.name);
 217         }
 218 }
 219
 220 static int seed_constraint_attributes(void)
 221 {
 222         int i;
 223         int ret;
 224
 225         for (i = 0; i < MAX_CONSTRAINTS_PER_ZONE; ++i) {
 226                 ret = create_constraint_attribute(i, "power_limit_uw",
 227                                         S_IWUSR | S_IRUGO,
 228                                         &constraint_attrs[i].power_limit_attr,
 229                                         show_constraint_power_limit_uw,
 230                                         store_constraint_power_limit_uw);
 231                 if (ret)
 232                         goto err_alloc;
 233                 ret = create_constraint_attribute(i, "time_window_us",
 234                                         S_IWUSR | S_IRUGO,
 235                                         &constraint_attrs[i].time_window_attr,
 236                                         show_constraint_time_window_us,
 237                                         store_constraint_time_window_us);
 238                 if (ret)
 239                         goto err_alloc;
 240                 ret = create_constraint_attribute(i, "name", S_IRUGO,
 241                                 &constraint_attrs[i].name_attr,
 242                                 show_constraint_name,
 243                                 NULL);
 244                 if (ret)
 245                         goto err_alloc;
 246                 ret = create_constraint_attribute(i, "max_power_uw", S_IRUGO,
 247                                 &constraint_attrs[i].max_power_attr,
 248                                 show_constraint_max_power_uw,
 249                                 NULL);
 250                 if (ret)
 251                         goto err_alloc;
 252                 ret = create_constraint_attribute(i, "min_power_uw", S_IRUGO,
 253                                 &constraint_attrs[i].min_power_attr,
 254                                 show_constraint_min_power_uw,
 255                                 NULL);
 256                 if (ret)
 257                         goto err_alloc;
 258                 ret = create_constraint_attribute(i, "max_time_window_us",
 259                                 S_IRUGO,
 260                                 &constraint_attrs[i].max_time_window_attr,
 261                                 show_constraint_max_time_window_us,
 262                                 NULL);
 263                 if (ret)
 264                         goto err_alloc;
 265                 ret = create_constraint_attribute(i, "min_time_window_us",
 266                                 S_IRUGO,
 267                                 &constraint_attrs[i].min_time_window_attr,
 268                                 show_constraint_min_time_window_us,
 269                                 NULL);
 270                 if (ret)
 271                         goto err_alloc;
 272
 273         }
 274
 275         return 0;
 276
 277 err_alloc:
 278         free_constraint_attributes();
 279
 280         return ret;
 281 }
 282
 283 static int create_constraints(struct powercap_zone *power_zone,
 284                         int nr_constraints,
 285                         const struct powercap_zone_constraint_ops *const_ops)
 286 {
 287         int i;
 288         int ret = 0;
 289         int count;
 290         struct powercap_zone_constraint *pconst;
 291
 292         if (!power_zone || !const_ops || !const_ops->get_power_limit_uw ||
 293                                         !const_ops->set_power_limit_uw ||
 294                                         !const_ops->get_time_window_us ||
 295                                         !const_ops->set_time_window_us)
 296                 return -EINVAL;
 297
 298         count = power_zone->zone_attr_count;
 299         for (i = 0; i < nr_constraints; ++i) {
 300                 pconst = &power_zone->constraints[i];
 301                 pconst->ops = const_ops;
 302                 pconst->id = power_zone->const_id_cnt;
 303                 power_zone->const_id_cnt++;
 304                 power_zone->zone_dev_attrs[count++] =
 305                                 &constraint_attrs[i].power_limit_attr.attr;
 306                 power_zone->zone_dev_attrs[count++] =
 307                                 &constraint_attrs[i].time_window_attr.attr;
 308                 if (pconst->ops->get_name)
 309                         power_zone->zone_dev_attrs[count++] =
 310                                 &constraint_attrs[i].name_attr.attr;
 311                 if (pconst->ops->get_max_power_uw)
 312                         power_zone->zone_dev_attrs[count++] =
 313                                 &constraint_attrs[i].max_power_attr.attr;
 314                 if (pconst->ops->get_min_power_uw)
 315                         power_zone->zone_dev_attrs[count++] =
 316                                 &constraint_attrs[i].min_power_attr.attr;
 317                 if (pconst->ops->get_max_time_window_us)
 318                         power_zone->zone_dev_attrs[count++] =
 319                                 &constraint_attrs[i].max_time_window_attr.attr;
 320                 if (pconst->ops->get_min_time_window_us)
 321                         power_zone->zone_dev_attrs[count++] =
 322                                 &constraint_attrs[i].min_time_window_attr.attr;
 323         }
 324         power_zone->zone_attr_count = count;
 325
 326         return ret;
 327 }
 328
 329 static bool control_type_valid(void *control_type)
 330 {
 331         struct powercap_control_type *pos = NULL;
 332         bool found = false;
 333
 334         mutex_lock(&powercap_cntrl_list_lock);
 335
 336         list_for_each_entry(pos, &powercap_cntrl_list, node) {
 337                 if (pos == control_type) {
 338                         found = true;
 339                         break;
 340                 }
 341         }
 342         mutex_unlock(&powercap_cntrl_list_lock);
 343
 344         return found;
 345 }
 346
 347 static ssize_t name_show(struct device *dev,
 348                                 struct device_attribute *attr,
 349                                 char *buf)
 350 {
 351         struct powercap_zone *power_zone = to_powercap_zone(dev);
 352
 353         return sprintf(buf, "%s\n", power_zone->name);
 354 }
 355
 356 static DEVICE_ATTR_RO(name);
 357
 358 /* Create zone and attributes in sysfs */
 359 static void create_power_zone_common_attributes(
 360                                         struct powercap_zone *power_zone)
 361 {
 362         int count = 0;
 363
 364         power_zone->zone_dev_attrs[count++] = &dev_attr_name.attr;
 365         if (power_zone->ops->get_max_energy_range_uj)
 366                 power_zone->zone_dev_attrs[count++] =
 367                                         &dev_attr_max_energy_range_uj.attr;
 368         if (power_zone->ops->get_energy_uj) {
 369                 if (power_zone->ops->reset_energy_uj)
 370                         dev_attr_energy_uj.attr.mode = S_IWUSR | S_IRUSR;
 371                 else
 372                         dev_attr_energy_uj.attr.mode = S_IRUSR;
 373                 power_zone->zone_dev_attrs[count++] =
 374                                         &dev_attr_energy_uj.attr;
 375         }
 376         if (power_zone->ops->get_power_uw)
 377                 power_zone->zone_dev_attrs[count++] =
 378                                         &dev_attr_power_uw.attr;
 379         if (power_zone->ops->get_max_power_range_uw)
 380                 power_zone->zone_dev_attrs[count++] =
 381                                         &dev_attr_max_power_range_uw.attr;
 382         power_zone->zone_dev_attrs[count] = NULL;
 383         power_zone->zone_attr_count = count;
 384 }
 385
 386 static void powercap_release(struct device *dev)
 387 {
 388         bool allocated;
 389
 390         if (dev->parent) {
 391                 struct powercap_zone *power_zone = to_powercap_zone(dev);
 392
 393                 /* Store flag as the release() may free memory */
 394                 allocated = power_zone->allocated;
 395                 /* Remove id from parent idr struct */
 396                 idr_remove(power_zone->parent_idr, power_zone->id);
 397                 /* Destroy idrs allocated for this zone */
 398                 idr_destroy(&power_zone->idr);
 399                 kfree(power_zone->name);
 400                 kfree(power_zone->zone_dev_attrs);
 401                 kfree(power_zone->constraints);
 402                 if (power_zone->ops->release)
 403                         power_zone->ops->release(power_zone);
 404                 if (allocated)
 405                         kfree(power_zone);
 406         } else {
 407                 struct powercap_control_type *control_type =
 408                                                 to_powercap_control_type(dev);
 409
 410                 /* Store flag as the release() may free memory */
 411                 allocated = control_type->allocated;
 412                 idr_destroy(&control_type->idr);
 413                 mutex_destroy(&control_type->lock);
 414                 if (control_type->ops && control_type->ops->release)
 415                         control_type->ops->release(control_type);
 416                 if (allocated)
 417                         kfree(control_type);
 418         }
 419 }
 420
 421 static ssize_t enabled_show(struct device *dev,
 422                                 struct device_attribute *attr,
 423                                 char *buf)
 424 {
 425         bool mode = true;
 426
 427         /* Default is enabled */
 428         if (dev->parent) {
 429                 struct powercap_zone *power_zone = to_powercap_zone(dev);
 430                 if (power_zone->ops->get_enable)
 431                         if (power_zone->ops->get_enable(power_zone, &mode))
 432                                 mode = false;
 433         } else {
 434                 struct powercap_control_type *control_type =
 435                                                 to_powercap_control_type(dev);
 436                 if (control_type->ops && control_type->ops->get_enable)
 437                         if (control_type->ops->get_enable(control_type, &mode))
 438                                 mode = false;
 439         }
 440
 441         return sprintf(buf, "%d\n", mode);
 442 }
 443
 444 static ssize_t enabled_store(struct device *dev,
 445                                 struct device_attribute *attr,
 446                                 const char *buf,  size_t len)
 447 {
 448         bool mode;
 449
 450         if (kstrtobool(buf, &mode))
 451                 return -EINVAL;
 452         if (dev->parent) {
 453                 struct powercap_zone *power_zone = to_powercap_zone(dev);
 454                 if (power_zone->ops->set_enable)
 455                         if (!power_zone->ops->set_enable(power_zone, mode))
 456                                 return len;
 457         } else {
 458                 struct powercap_control_type *control_type =
 459                                                 to_powercap_control_type(dev);
 460                 if (control_type->ops && control_type->ops->set_enable)
 461                         if (!control_type->ops->set_enable(control_type, mode))
 462                                 return len;
 463         }
 464
 465         return -ENOSYS;
 466 }
 467
 468 static DEVICE_ATTR_RW(enabled);
 469
 470 static struct attribute *powercap_attrs[] = {
 471         &dev_attr_enabled.attr,
 472         NULL,
 473 };
 474 ATTRIBUTE_GROUPS(powercap);
 475
 476 static struct class powercap_class = {
 477         .name = "powercap",
 478         .dev_release = powercap_release,
 479         .dev_groups = powercap_groups,
 480 };
 481
 482 struct powercap_zone *powercap_register_zone(
 483                         struct powercap_zone *power_zone,
 484                         struct powercap_control_type *control_type,
 485                         const char *name,
 486                         struct powercap_zone *parent,
 487                         const struct powercap_zone_ops *ops,
 488                         int nr_constraints,
 489                         const struct powercap_zone_constraint_ops *const_ops)
 490 {
 491         int result;
 492         int nr_attrs;
 493
 494         if (!name || !control_type || !ops ||
 495                         nr_constraints > MAX_CONSTRAINTS_PER_ZONE ||
 496                         (!ops->get_energy_uj && !ops->get_power_uw) ||
 497                         !control_type_valid(control_type))
 498                 return ERR_PTR(-EINVAL);
 499
 500         if (power_zone) {
 501                 if (!ops->release)
 502                         return ERR_PTR(-EINVAL);
 503                 memset(power_zone, 0, sizeof(*power_zone));
 504         } else {
 505                 power_zone = kzalloc(sizeof(*power_zone), GFP_KERNEL);
 506                 if (!power_zone)
 507                         return ERR_PTR(-ENOMEM);
 508                 power_zone->allocated = true;
 509         }
 510         power_zone->ops = ops;
 511         power_zone->control_type_inst = control_type;
 512         if (!parent) {
 513                 power_zone->dev.parent = &control_type->dev;
 514                 power_zone->parent_idr = &control_type->idr;
 515         } else {
 516                 power_zone->dev.parent = &parent->dev;
 517                 power_zone->parent_idr = &parent->idr;
 518         }
 519         power_zone->dev.class = &powercap_class;
 520
 521         mutex_lock(&control_type->lock);
 522         /* Using idr to get the unique id */
 523         result = idr_alloc(power_zone->parent_idr, NULL, 0, 0, GFP_KERNEL);
 524         if (result < 0)
 525                 goto err_idr_alloc;
 526
 527         power_zone->id = result;
 528         idr_init(&power_zone->idr);
 529         result = -ENOMEM;
 530         power_zone->name = kstrdup(name, GFP_KERNEL);
 531         if (!power_zone->name)
 532                 goto err_name_alloc;
 533         power_zone->constraints = kcalloc(nr_constraints,
 534                                           sizeof(*power_zone->constraints),
 535                                           GFP_KERNEL);
 536         if (!power_zone->constraints)
 537                 goto err_const_alloc;
 538
 539         nr_attrs = nr_constraints * POWERCAP_CONSTRAINTS_ATTRS +
 540                                                 POWERCAP_ZONE_MAX_ATTRS + 1;
 541         power_zone->zone_dev_attrs = kcalloc(nr_attrs, sizeof(void *),
 542                                              GFP_KERNEL);
 543         if (!power_zone->zone_dev_attrs)
 544                 goto err_attr_alloc;
 545         create_power_zone_common_attributes(power_zone);
 546         result = create_constraints(power_zone, nr_constraints, const_ops);
 547         if (result)
 548                 goto err_dev_ret;
 549
 550         power_zone->zone_dev_attrs[power_zone->zone_attr_count] = NULL;
 551         power_zone->dev_zone_attr_group.attrs = power_zone->zone_dev_attrs;
 552         power_zone->dev_attr_groups[0] = &power_zone->dev_zone_attr_group;
 553         power_zone->dev_attr_groups[1] = NULL;
 554         power_zone->dev.groups = power_zone->dev_attr_groups;
 555         dev_set_name(&power_zone->dev, "%s:%x",
 556                                         dev_name(power_zone->dev.parent),
 557                                         power_zone->id);
 558         result = device_register(&power_zone->dev);
 559         if (result) {
 560                 put_device(&power_zone->dev);
 561                 mutex_unlock(&control_type->lock);
 562
 563                 return ERR_PTR(result);
 564         }
 565
 566         control_type->nr_zones++;
 567         mutex_unlock(&control_type->lock);
 568
 569         return power_zone;
 570
 571 err_dev_ret:
 572         kfree(power_zone->zone_dev_attrs);
 573 err_attr_alloc:
 574         kfree(power_zone->constraints);
 575 err_const_alloc:
 576         kfree(power_zone->name);
 577 err_name_alloc:
 578         idr_remove(power_zone->parent_idr, power_zone->id);
 579 err_idr_alloc:
 580         if (power_zone->allocated)
 581                 kfree(power_zone);
 582         mutex_unlock(&control_type->lock);
 583
 584         return ERR_PTR(result);
 585 }
 586 EXPORT_SYMBOL_GPL(powercap_register_zone);
 587
 588 int powercap_unregister_zone(struct powercap_control_type *control_type,
 589                                 struct powercap_zone *power_zone)
 590 {
 591         if (!power_zone || !control_type)
 592                 return -EINVAL;
 593
 594         mutex_lock(&control_type->lock);
 595         control_type->nr_zones--;
 596         mutex_unlock(&control_type->lock);
 597
 598         device_unregister(&power_zone->dev);
 599
 600         return 0;
 601 }
 602 EXPORT_SYMBOL_GPL(powercap_unregister_zone);
 603
 604 struct powercap_control_type *powercap_register_control_type(
 605                                 struct powercap_control_type *control_type,
 606                                 const char *name,
 607                                 const struct powercap_control_type_ops *ops)
 608 {
 609         int result;
 610
 611         if (!name)
 612                 return ERR_PTR(-EINVAL);
 613         if (control_type) {
 614                 if (!ops || !ops->release)
 615                         return ERR_PTR(-EINVAL);
 616                 memset(control_type, 0, sizeof(*control_type));
 617         } else {
 618                 control_type = kzalloc(sizeof(*control_type), GFP_KERNEL);
 619                 if (!control_type)
 620                         return ERR_PTR(-ENOMEM);
 621                 control_type->allocated = true;
 622         }
 623         mutex_init(&control_type->lock);
 624         control_type->ops = ops;
 625         INIT_LIST_HEAD(&control_type->node);
 626         control_type->dev.class = &powercap_class;
 627         dev_set_name(&control_type->dev, "%s", name);
 628         result = device_register(&control_type->dev);
 629         if (result) {
 630                 if (control_type->allocated)
 631                         kfree(control_type);
 632                 return ERR_PTR(result);
 633         }
 634         idr_init(&control_type->idr);
 635
 636         mutex_lock(&powercap_cntrl_list_lock);
 637         list_add_tail(&control_type->node, &powercap_cntrl_list);
 638         mutex_unlock(&powercap_cntrl_list_lock);
 639
 640         return control_type;
 641 }
 642 EXPORT_SYMBOL_GPL(powercap_register_control_type);
 643
 644 int powercap_unregister_control_type(struct powercap_control_type *control_type)
 645 {
 646         struct powercap_control_type *pos = NULL;
 647
 648         if (control_type->nr_zones) {
 649                 dev_err(&control_type->dev, "Zones of this type still not freed\n");
 650                 return -EINVAL;
 651         }
 652         mutex_lock(&powercap_cntrl_list_lock);
 653         list_for_each_entry(pos, &powercap_cntrl_list, node) {
 654                 if (pos == control_type) {
 655                         list_del(&control_type->node);
 656                         mutex_unlock(&powercap_cntrl_list_lock);
 657                         device_unregister(&control_type->dev);
 658                         return 0;
 659                 }
 660         }
 661         mutex_unlock(&powercap_cntrl_list_lock);
 662
 663         return -ENODEV;
 664 }
 665 EXPORT_SYMBOL_GPL(powercap_unregister_control_type);
 666
 667 static int __init powercap_init(void)
 668 {
 669         int result;
 670
 671         result = seed_constraint_attributes();
 672         if (result)
 673                 return result;
 674
 675         return class_register(&powercap_class);
 676 }
 677
 678 fs_initcall(powercap_init);
 679
 680 MODULE_DESCRIPTION("PowerCap sysfs Driver");
 681 MODULE_AUTHOR("Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>");