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