drivers/powercap/powercap_sys.c

   1 /*
   2  * Power capping class
   3  * Copyright (c) 2013, Intel Corporation.
   4  *
   5  * This program is free software; you can redistribute it and/or modify it
   6  * under the terms and conditions of the GNU General Public License,
   7  * version 2, as published by the Free Software Foundation.
   8  *
   9  * This program is distributed in the hope it will be useful, but WITHOUT
  10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
  12  * more details.
  13  *
  14  * You should have received a copy of the GNU General Public License along with
  15  * this program; if not, write to the Free Software Foundation, Inc.
  16  *
  17  */
  18
  19 #include <linux/module.h>
  20 #include <linux/device.h>
  21 #include <linux/err.h>
  22 #include <linux/slab.h>
  23 #include <linux/powercap.h>
  24
  25 #define to_powercap_zone(n) container_of(n, struct powercap_zone, dev)
  26 #define to_powercap_control_type(n) \
  27                         container_of(n, struct powercap_control_type, dev)
  28
  29 /* Power zone show function */
  30 #define define_power_zone_show(_attr)           \
  31 static ssize_t _attr##_show(struct device *dev, \
  32                                         struct device_attribute *dev_attr,\
  33                                         char *buf) \
  34 { \
  35         u64 value; \
  36         ssize_t len = -EINVAL; \
  37         struct powercap_zone *power_zone = to_powercap_zone(dev); \
  38         \
  39         if (power_zone->ops->get_##_attr) { \
  40                 if (!power_zone->ops->get_##_attr(power_zone, &value)) \
  41                         len = sprintf(buf, "%lld\n", value); \
  42         } \
  43         \
  44         return len; \
  45 }
  46
  47 /* The only meaningful input is 0 (reset), others are silently ignored */
  48 #define define_power_zone_store(_attr)          \
  49 static ssize_t _attr##_store(struct device *dev,\
  50                                 struct device_attribute *dev_attr, \
  51                                 const char *buf, size_t count) \
  52 { \
  53         int err; \
  54         struct powercap_zone *power_zone = to_powercap_zone(dev); \
  55         u64 value; \
  56         \
  57         err = kstrtoull(buf, 10, &value); \
  58         if (err) \
  59                 return -EINVAL; \
  60         if (value) \
  61                 return count; \
  62         if (power_zone->ops->reset_##_attr) { \
  63                 if (!power_zone->ops->reset_##_attr(power_zone)) \
  64                         return count; \
  65         } \
  66         \
  67         return -EINVAL; \
  68 }
  69
  70 /* Power zone constraint show function */
  71 #define define_power_zone_constraint_show(_attr) \
  72 static ssize_t show_constraint_##_attr(struct device *dev, \
  73                                 struct device_attribute *dev_attr,\
  74                                 char *buf) \
  75 { \
  76         u64 value; \
  77         ssize_t len = -ENODATA; \
  78         struct powercap_zone *power_zone = to_powercap_zone(dev); \
  79         int id; \
  80         struct powercap_zone_constraint *pconst;\
  81         \
  82         if (!sscanf(dev_attr->attr.name, "constraint_%d_", &id)) \
  83                 return -EINVAL; \
  84         if (id >= power_zone->const_id_cnt)     \
  85                 return -EINVAL; \
  86         pconst = &power_zone->constraints[id]; \
  87         if (pconst && pconst->ops && pconst->ops->get_##_attr) { \
  88                 if (!pconst->ops->get_##_attr(power_zone, id, &value)) \
  89                         len = sprintf(buf, "%lld\n", value); \
  90         } \
  91         \
  92         return len; \
  93 }
  94
  95 /* Power zone constraint store function */
  96 #define define_power_zone_constraint_store(_attr) \
  97 static ssize_t store_constraint_##_attr(struct device *dev,\
  98                                 struct device_attribute *dev_attr, \
  99                                 const char *buf, size_t count) \
 100 { \
 101         int err; \
 102         u64 value; \
 103         struct powercap_zone *power_zone = to_powercap_zone(dev); \
 104         int id; \
 105         struct powercap_zone_constraint *pconst;\
 106         \
 107         if (!sscanf(dev_attr->attr.name, "constraint_%d_", &id)) \
 108                 return -EINVAL; \
 109         if (id >= power_zone->const_id_cnt)     \
 110                 return -EINVAL; \
 111         pconst = &power_zone->constraints[id]; \
 112         err = kstrtoull(buf, 10, &value); \
 113         if (err) \
 114                 return -EINVAL; \
 115         if (pconst && pconst->ops && pconst->ops->set_##_attr) { \
 116                 if (!pconst->ops->set_##_attr(power_zone, id, value)) \
 117                         return count; \
 118         } \
 119         \
 120         return -ENODATA; \
 121 }
 122
 123 /* Power zone information callbacks */
 124 define_power_zone_show(power_uw);
 125 define_power_zone_show(max_power_range_uw);
 126 define_power_zone_show(energy_uj);
 127 define_power_zone_store(energy_uj);
 128 define_power_zone_show(max_energy_range_uj);
 129
 130 /* Power zone attributes */
 131 static DEVICE_ATTR_RO(max_power_range_uw);
 132 static DEVICE_ATTR_RO(power_uw);
 133 static DEVICE_ATTR_RO(max_energy_range_uj);
 134 static DEVICE_ATTR_RW(energy_uj);
 135
 136 /* Power zone constraint attributes callbacks */
 137 define_power_zone_constraint_show(power_limit_uw);
 138 define_power_zone_constraint_store(power_limit_uw);
 139 define_power_zone_constraint_show(time_window_us);
 140 define_power_zone_constraint_store(time_window_us);
 141 define_power_zone_constraint_show(max_power_uw);
 142 define_power_zone_constraint_show(min_power_uw);
 143 define_power_zone_constraint_show(max_time_window_us);
 144 define_power_zone_constraint_show(min_time_window_us);
 145
 146 /* For one time seeding of constraint device attributes */
 147 struct powercap_constraint_attr {
 148         struct device_attribute power_limit_attr;
 149         struct device_attribute time_window_attr;
 150         struct device_attribute max_power_attr;
 151         struct device_attribute min_power_attr;
 152         struct device_attribute max_time_window_attr;
 153         struct device_attribute min_time_window_attr;
 154         struct device_attribute name_attr;
 155 };
 156
 157 static struct powercap_constraint_attr
 158                                 constraint_attrs[MAX_CONSTRAINTS_PER_ZONE];
 159
 160 /* A list of powercap control_types */
 161 static LIST_HEAD(powercap_cntrl_list);
 162 /* Mutex to protect list of powercap control_types */
 163 static DEFINE_MUTEX(powercap_cntrl_list_lock);
 164
 165 #define POWERCAP_CONSTRAINT_NAME_LEN    30 /* Some limit to avoid overflow */
 166 static ssize_t show_constraint_name(struct device *dev,
 167                                 struct device_attribute *dev_attr,
 168                                 char *buf)
 169 {
 170         const char *name;
 171         struct powercap_zone *power_zone = to_powercap_zone(dev);
 172         int id;
 173         ssize_t len = -ENODATA;
 174         struct powercap_zone_constraint *pconst;
 175
 176         if (!sscanf(dev_attr->attr.name, "constraint_%d_", &id))
 177                 return -EINVAL;
 178         if (id >= power_zone->const_id_cnt)
 179                 return -EINVAL;
 180         pconst = &power_zone->constraints[id];
 181
 182         if (pconst && pconst->ops && pconst->ops->get_name) {
 183                 name = pconst->ops->get_name(power_zone, id);
 184                 if (name) {
 185                         snprintf(buf, POWERCAP_CONSTRAINT_NAME_LEN,
 186                                                                 "%s\n", name);
 187                         buf[POWERCAP_CONSTRAINT_NAME_LEN] = '\0';
 188                         len = strlen(buf);
 189                 }
 190         }
 191
 192         return len;
 193 }
 194
 195 static int create_constraint_attribute(int id, const char *name,
 196                                 int mode,
 197                                 struct device_attribute *dev_attr,
 198                                 ssize_t (*show)(struct device *,
 199                                         struct device_attribute *, char *),
 200                                 ssize_t (*store)(struct device *,
 201                                         struct device_attribute *,
 202                                 const char *, size_t)
 203                                 )
 204 {
 205
 206         dev_attr->attr.name = kasprintf(GFP_KERNEL, "constraint_%d_%s",
 207                                                                 id, name);
 208         if (!dev_attr->attr.name)
 209                 return -ENOMEM;
 210         dev_attr->attr.mode = mode;
 211         dev_attr->show = show;
 212         dev_attr->store = store;
 213
 214         return 0;
 215 }
 216
 217 static void free_constraint_attributes(void)
 218 {
 219         int i;
 220
 221         for (i = 0; i < MAX_CONSTRAINTS_PER_ZONE; ++i) {
 222                 kfree(constraint_attrs[i].power_limit_attr.attr.name);
 223                 kfree(constraint_attrs[i].time_window_attr.attr.name);
 224                 kfree(constraint_attrs[i].name_attr.attr.name);
 225                 kfree(constraint_attrs[i].max_power_attr.attr.name);
 226                 kfree(constraint_attrs[i].min_power_attr.attr.name);
 227                 kfree(constraint_attrs[i].max_time_window_attr.attr.name);
 228                 kfree(constraint_attrs[i].min_time_window_attr.attr.name);
 229         }
 230 }
 231
 232 static int seed_constraint_attributes(void)
 233 {
 234         int i;
 235         int ret;
 236
 237         for (i = 0; i < MAX_CONSTRAINTS_PER_ZONE; ++i) {
 238                 ret = create_constraint_attribute(i, "power_limit_uw",
 239                                         S_IWUSR | S_IRUGO,
 240                                         &constraint_attrs[i].power_limit_attr,
 241                                         show_constraint_power_limit_uw,
 242                                         store_constraint_power_limit_uw);
 243                 if (ret)
 244                         goto err_alloc;
 245                 ret = create_constraint_attribute(i, "time_window_us",
 246                                         S_IWUSR | S_IRUGO,
 247                                         &constraint_attrs[i].time_window_attr,
 248                                         show_constraint_time_window_us,
 249                                         store_constraint_time_window_us);
 250                 if (ret)
 251                         goto err_alloc;
 252                 ret = create_constraint_attribute(i, "name", S_IRUGO,
 253                                 &constraint_attrs[i].name_attr,
 254                                 show_constraint_name,
 255                                 NULL);
 256                 if (ret)
 257                         goto err_alloc;
 258                 ret = create_constraint_attribute(i, "max_power_uw", S_IRUGO,
 259                                 &constraint_attrs[i].max_power_attr,
 260                                 show_constraint_max_power_uw,
 261                                 NULL);
 262                 if (ret)
 263                         goto err_alloc;
 264                 ret = create_constraint_attribute(i, "min_power_uw", S_IRUGO,
 265                                 &constraint_attrs[i].min_power_attr,
 266                                 show_constraint_min_power_uw,
 267                                 NULL);
 268                 if (ret)
 269                         goto err_alloc;
 270                 ret = create_constraint_attribute(i, "max_time_window_us",
 271                                 S_IRUGO,
 272                                 &constraint_attrs[i].max_time_window_attr,
 273                                 show_constraint_max_time_window_us,
 274                                 NULL);
 275                 if (ret)
 276                         goto err_alloc;
 277                 ret = create_constraint_attribute(i, "min_time_window_us",
 278                                 S_IRUGO,
 279                                 &constraint_attrs[i].min_time_window_attr,
 280                                 show_constraint_min_time_window_us,
 281                                 NULL);
 282                 if (ret)
 283                         goto err_alloc;
 284
 285         }
 286
 287         return 0;
 288
 289 err_alloc:
 290         free_constraint_attributes();
 291
 292         return ret;
 293 }
 294
 295 static int create_constraints(struct powercap_zone *power_zone,
 296                         int nr_constraints,
 297                         const struct powercap_zone_constraint_ops *const_ops)
 298 {
 299         int i;
 300         int ret = 0;
 301         int count;
 302         struct powercap_zone_constraint *pconst;
 303
 304         if (!power_zone || !const_ops || !const_ops->get_power_limit_uw ||
 305                                         !const_ops->set_power_limit_uw ||
 306                                         !const_ops->get_time_window_us ||
 307                                         !const_ops->set_time_window_us)
 308                 return -EINVAL;
 309
 310         count = power_zone->zone_attr_count;
 311         for (i = 0; i < nr_constraints; ++i) {
 312                 pconst = &power_zone->constraints[i];
 313                 pconst->ops = const_ops;
 314                 pconst->id = power_zone->const_id_cnt;
 315                 power_zone->const_id_cnt++;
 316                 power_zone->zone_dev_attrs[count++] =
 317                                 &constraint_attrs[i].power_limit_attr.attr;
 318                 power_zone->zone_dev_attrs[count++] =
 319                                 &constraint_attrs[i].time_window_attr.attr;
 320                 if (pconst->ops->get_name)
 321                         power_zone->zone_dev_attrs[count++] =
 322                                 &constraint_attrs[i].name_attr.attr;
 323                 if (pconst->ops->get_max_power_uw)
 324                         power_zone->zone_dev_attrs[count++] =
 325                                 &constraint_attrs[i].max_power_attr.attr;
 326                 if (pconst->ops->get_min_power_uw)
 327                         power_zone->zone_dev_attrs[count++] =
 328                                 &constraint_attrs[i].min_power_attr.attr;
 329                 if (pconst->ops->get_max_time_window_us)
 330                         power_zone->zone_dev_attrs[count++] =
 331                                 &constraint_attrs[i].max_time_window_attr.attr;
 332                 if (pconst->ops->get_min_time_window_us)
 333                         power_zone->zone_dev_attrs[count++] =
 334                                 &constraint_attrs[i].min_time_window_attr.attr;
 335         }
 336         power_zone->zone_attr_count = count;
 337
 338         return ret;
 339 }
 340
 341 static bool control_type_valid(void *control_type)
 342 {
 343         struct powercap_control_type *pos = NULL;
 344         bool found = false;
 345
 346         mutex_lock(&powercap_cntrl_list_lock);
 347
 348         list_for_each_entry(pos, &powercap_cntrl_list, node) {
 349                 if (pos == control_type) {
 350                         found = true;
 351                         break;
 352                 }
 353         }
 354         mutex_unlock(&powercap_cntrl_list_lock);
 355
 356         return found;
 357 }
 358
 359 static ssize_t name_show(struct device *dev,
 360                                 struct device_attribute *attr,
 361                                 char *buf)
 362 {
 363         struct powercap_zone *power_zone = to_powercap_zone(dev);
 364
 365         return sprintf(buf, "%s\n", power_zone->name);
 366 }
 367
 368 static DEVICE_ATTR_RO(name);
 369
 370 /* Create zone and attributes in sysfs */
 371 static void create_power_zone_common_attributes(
 372                                         struct powercap_zone *power_zone)
 373 {
 374         int count = 0;
 375
 376         power_zone->zone_dev_attrs[count++] = &dev_attr_name.attr;
 377         if (power_zone->ops->get_max_energy_range_uj)
 378                 power_zone->zone_dev_attrs[count++] =
 379                                         &dev_attr_max_energy_range_uj.attr;
 380         if (power_zone->ops->get_energy_uj) {
 381                 if (power_zone->ops->reset_energy_uj)
 382                         dev_attr_energy_uj.attr.mode = S_IWUSR | S_IRUGO;
 383                 else
 384                         dev_attr_energy_uj.attr.mode = S_IRUGO;
 385                 power_zone->zone_dev_attrs[count++] =
 386                                         &dev_attr_energy_uj.attr;
 387         }
 388         if (power_zone->ops->get_power_uw)
 389                 power_zone->zone_dev_attrs[count++] =
 390                                         &dev_attr_power_uw.attr;
 391         if (power_zone->ops->get_max_power_range_uw)
 392                 power_zone->zone_dev_attrs[count++] =
 393                                         &dev_attr_max_power_range_uw.attr;
 394         power_zone->zone_dev_attrs[count] = NULL;
 395         power_zone->zone_attr_count = count;
 396 }
 397
 398 static void powercap_release(struct device *dev)
 399 {
 400         bool allocated;
 401
 402         if (dev->parent) {
 403                 struct powercap_zone *power_zone = to_powercap_zone(dev);
 404
 405                 /* Store flag as the release() may free memory */
 406                 allocated = power_zone->allocated;
 407                 /* Remove id from parent idr struct */
 408                 idr_remove(power_zone->parent_idr, power_zone->id);
 409                 /* Destroy idrs allocated for this zone */
 410                 idr_destroy(&power_zone->idr);
 411                 kfree(power_zone->name);
 412                 kfree(power_zone->zone_dev_attrs);
 413                 kfree(power_zone->constraints);
 414                 if (power_zone->ops->release)
 415                         power_zone->ops->release(power_zone);
 416                 if (allocated)
 417                         kfree(power_zone);
 418         } else {
 419                 struct powercap_control_type *control_type =
 420                                                 to_powercap_control_type(dev);
 421
 422                 /* Store flag as the release() may free memory */
 423                 allocated = control_type->allocated;
 424                 idr_destroy(&control_type->idr);
 425                 mutex_destroy(&control_type->lock);
 426                 if (control_type->ops && control_type->ops->release)
 427                         control_type->ops->release(control_type);
 428                 if (allocated)
 429                         kfree(control_type);
 430         }
 431 }
 432
 433 static ssize_t enabled_show(struct device *dev,
 434                                 struct device_attribute *attr,
 435                                 char *buf)
 436 {
 437         bool mode = true;
 438
 439         /* Default is enabled */
 440         if (dev->parent) {
 441                 struct powercap_zone *power_zone = to_powercap_zone(dev);
 442                 if (power_zone->ops->get_enable)
 443                         if (power_zone->ops->get_enable(power_zone, &mode))
 444                                 mode = false;
 445         } else {
 446                 struct powercap_control_type *control_type =
 447                                                 to_powercap_control_type(dev);
 448                 if (control_type->ops && control_type->ops->get_enable)
 449                         if (control_type->ops->get_enable(control_type, &mode))
 450                                 mode = false;
 451         }
 452
 453         return sprintf(buf, "%d\n", mode);
 454 }
 455
 456 static ssize_t enabled_store(struct device *dev,
 457                                 struct device_attribute *attr,
 458                                 const char *buf,  size_t len)
 459 {
 460         bool mode;
 461
 462         if (strtobool(buf, &mode))
 463                 return -EINVAL;
 464         if (dev->parent) {
 465                 struct powercap_zone *power_zone = to_powercap_zone(dev);
 466                 if (power_zone->ops->set_enable)
 467                         if (!power_zone->ops->set_enable(power_zone, mode))
 468                                 return len;
 469         } else {
 470                 struct powercap_control_type *control_type =
 471                                                 to_powercap_control_type(dev);
 472                 if (control_type->ops && control_type->ops->set_enable)
 473                         if (!control_type->ops->set_enable(control_type, mode))
 474                                 return len;
 475         }
 476
 477         return -ENOSYS;
 478 }
 479
 480 static DEVICE_ATTR_RW(enabled);
 481
 482 static struct attribute *powercap_attrs[] = {
 483         &dev_attr_enabled.attr,
 484         NULL,
 485 };
 486 ATTRIBUTE_GROUPS(powercap);
 487
 488 static struct class powercap_class = {
 489         .name = "powercap",
 490         .dev_release = powercap_release,
 491         .dev_groups = powercap_groups,
 492 };
 493
 494 struct powercap_zone *powercap_register_zone(
 495                         struct powercap_zone *power_zone,
 496                         struct powercap_control_type *control_type,
 497                         const char *name,
 498                         struct powercap_zone *parent,
 499                         const struct powercap_zone_ops *ops,
 500                         int nr_constraints,
 501                         const struct powercap_zone_constraint_ops *const_ops)
 502 {
 503         int result;
 504         int nr_attrs;
 505
 506         if (!name || !control_type || !ops ||
 507                         nr_constraints > MAX_CONSTRAINTS_PER_ZONE ||
 508                         (!ops->get_energy_uj && !ops->get_power_uw) ||
 509                         !control_type_valid(control_type))
 510                 return ERR_PTR(-EINVAL);
 511
 512         if (power_zone) {
 513                 if (!ops->release)
 514                         return ERR_PTR(-EINVAL);
 515                 memset(power_zone, 0, sizeof(*power_zone));
 516         } else {
 517                 power_zone = kzalloc(sizeof(*power_zone), GFP_KERNEL);
 518                 if (!power_zone)
 519                         return ERR_PTR(-ENOMEM);
 520                 power_zone->allocated = true;
 521         }
 522         power_zone->ops = ops;
 523         power_zone->control_type_inst = control_type;
 524         if (!parent) {
 525                 power_zone->dev.parent = &control_type->dev;
 526                 power_zone->parent_idr = &control_type->idr;
 527         } else {
 528                 power_zone->dev.parent = &parent->dev;
 529                 power_zone->parent_idr = &parent->idr;
 530         }
 531         power_zone->dev.class = &powercap_class;
 532
 533         mutex_lock(&control_type->lock);
 534         /* Using idr to get the unique id */
 535         result = idr_alloc(power_zone->parent_idr, NULL, 0, 0, GFP_KERNEL);
 536         if (result < 0)
 537                 goto err_idr_alloc;
 538
 539         power_zone->id = result;
 540         idr_init(&power_zone->idr);
 541         result = -ENOMEM;
 542         power_zone->name = kstrdup(name, GFP_KERNEL);
 543         if (!power_zone->name)
 544                 goto err_name_alloc;
 545         dev_set_name(&power_zone->dev, "%s:%x",
 546                                         dev_name(power_zone->dev.parent),
 547                                         power_zone->id);
 548         power_zone->constraints = kzalloc(sizeof(*power_zone->constraints) *
 549                                          nr_constraints, GFP_KERNEL);
 550         if (!power_zone->constraints)
 551                 goto err_const_alloc;
 552
 553         nr_attrs = nr_constraints * POWERCAP_CONSTRAINTS_ATTRS +
 554                                                 POWERCAP_ZONE_MAX_ATTRS + 1;
 555         power_zone->zone_dev_attrs = kzalloc(sizeof(void *) *
 556                                                 nr_attrs, GFP_KERNEL);
 557         if (!power_zone->zone_dev_attrs)
 558                 goto err_attr_alloc;
 559         create_power_zone_common_attributes(power_zone);
 560         result = create_constraints(power_zone, nr_constraints, const_ops);
 561         if (result)
 562                 goto err_dev_ret;
 563
 564         power_zone->zone_dev_attrs[power_zone->zone_attr_count] = NULL;
 565         power_zone->dev_zone_attr_group.attrs = power_zone->zone_dev_attrs;
 566         power_zone->dev_attr_groups[0] = &power_zone->dev_zone_attr_group;
 567         power_zone->dev_attr_groups[1] = NULL;
 568         power_zone->dev.groups = power_zone->dev_attr_groups;
 569         result = device_register(&power_zone->dev);
 570         if (result)
 571                 goto err_dev_ret;
 572
 573         control_type->nr_zones++;
 574         mutex_unlock(&control_type->lock);
 575
 576         return power_zone;
 577
 578 err_dev_ret:
 579         kfree(power_zone->zone_dev_attrs);
 580 err_attr_alloc:
 581         kfree(power_zone->constraints);
 582 err_const_alloc:
 583         kfree(power_zone->name);
 584 err_name_alloc:
 585         idr_remove(power_zone->parent_idr, power_zone->id);
 586 err_idr_alloc:
 587         if (power_zone->allocated)
 588                 kfree(power_zone);
 589         mutex_unlock(&control_type->lock);
 590
 591         return ERR_PTR(result);
 592 }
 593 EXPORT_SYMBOL_GPL(powercap_register_zone);
 594
 595 int powercap_unregister_zone(struct powercap_control_type *control_type,
 596                                 struct powercap_zone *power_zone)
 597 {
 598         if (!power_zone || !control_type)
 599                 return -EINVAL;
 600
 601         mutex_lock(&control_type->lock);
 602         control_type->nr_zones--;
 603         mutex_unlock(&control_type->lock);
 604
 605         device_unregister(&power_zone->dev);
 606
 607         return 0;
 608 }
 609 EXPORT_SYMBOL_GPL(powercap_unregister_zone);
 610
 611 struct powercap_control_type *powercap_register_control_type(
 612                                 struct powercap_control_type *control_type,
 613                                 const char *name,
 614                                 const struct powercap_control_type_ops *ops)
 615 {
 616         int result;
 617
 618         if (!name)
 619                 return ERR_PTR(-EINVAL);
 620         if (control_type) {
 621                 if (!ops || !ops->release)
 622                         return ERR_PTR(-EINVAL);
 623                 memset(control_type, 0, sizeof(*control_type));
 624         } else {
 625                 control_type = kzalloc(sizeof(*control_type), GFP_KERNEL);
 626                 if (!control_type)
 627                         return ERR_PTR(-ENOMEM);
 628                 control_type->allocated = true;
 629         }
 630         mutex_init(&control_type->lock);
 631         control_type->ops = ops;
 632         INIT_LIST_HEAD(&control_type->node);
 633         control_type->dev.class = &powercap_class;
 634         dev_set_name(&control_type->dev, "%s", name);
 635         result = device_register(&control_type->dev);
 636         if (result) {
 637                 if (control_type->allocated)
 638                         kfree(control_type);
 639                 return ERR_PTR(result);
 640         }
 641         idr_init(&control_type->idr);
 642
 643         mutex_lock(&powercap_cntrl_list_lock);
 644         list_add_tail(&control_type->node, &powercap_cntrl_list);
 645         mutex_unlock(&powercap_cntrl_list_lock);
 646
 647         return control_type;
 648 }
 649 EXPORT_SYMBOL_GPL(powercap_register_control_type);
 650
 651 int powercap_unregister_control_type(struct powercap_control_type *control_type)
 652 {
 653         struct powercap_control_type *pos = NULL;
 654
 655         if (control_type->nr_zones) {
 656                 dev_err(&control_type->dev, "Zones of this type still not freed\n");
 657                 return -EINVAL;
 658         }
 659         mutex_lock(&powercap_cntrl_list_lock);
 660         list_for_each_entry(pos, &powercap_cntrl_list, node) {
 661                 if (pos == control_type) {
 662                         list_del(&control_type->node);
 663                         mutex_unlock(&powercap_cntrl_list_lock);
 664                         device_unregister(&control_type->dev);
 665                         return 0;
 666                 }
 667         }
 668         mutex_unlock(&powercap_cntrl_list_lock);
 669
 670         return -ENODEV;
 671 }
 672 EXPORT_SYMBOL_GPL(powercap_unregister_control_type);
 673
 674 static int __init powercap_init(void)
 675 {
 676         int result = 0;
 677
 678         result = seed_constraint_attributes();
 679         if (result)
 680                 return result;
 681
 682         result = class_register(&powercap_class);
 683
 684         return result;
 685 }
 686
 687 device_initcall(powercap_init);
 688
 689 MODULE_DESCRIPTION("PowerCap sysfs Driver");
 690 MODULE_AUTHOR("Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>");
 691 MODULE_LICENSE("GPL v2");