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0001 // SPDX-License-Identifier: GPL-2.0-only
0002 /*
0003  * Power capping class
0004  * Copyright (c) 2013, Intel Corporation.
0005  */
0006 
0007 #include <linux/module.h>
0008 #include <linux/device.h>
0009 #include <linux/err.h>
0010 #include <linux/slab.h>
0011 #include <linux/powercap.h>
0012 
0013 #define to_powercap_zone(n) container_of(n, struct powercap_zone, dev)
0014 #define to_powercap_control_type(n) \
0015             container_of(n, struct powercap_control_type, dev)
0016 
0017 /* Power zone show function */
0018 #define define_power_zone_show(_attr)       \
0019 static ssize_t _attr##_show(struct device *dev, \
0020                     struct device_attribute *dev_attr,\
0021                     char *buf) \
0022 { \
0023     u64 value; \
0024     ssize_t len = -EINVAL; \
0025     struct powercap_zone *power_zone = to_powercap_zone(dev); \
0026     \
0027     if (power_zone->ops->get_##_attr) { \
0028         if (!power_zone->ops->get_##_attr(power_zone, &value)) \
0029             len = sprintf(buf, "%lld\n", value); \
0030     } \
0031     \
0032     return len; \
0033 }
0034 
0035 /* The only meaningful input is 0 (reset), others are silently ignored */
0036 #define define_power_zone_store(_attr)      \
0037 static ssize_t _attr##_store(struct device *dev,\
0038                 struct device_attribute *dev_attr, \
0039                 const char *buf, size_t count) \
0040 { \
0041     int err; \
0042     struct powercap_zone *power_zone = to_powercap_zone(dev); \
0043     u64 value; \
0044     \
0045     err = kstrtoull(buf, 10, &value); \
0046     if (err) \
0047         return -EINVAL; \
0048     if (value) \
0049         return count; \
0050     if (power_zone->ops->reset_##_attr) { \
0051         if (!power_zone->ops->reset_##_attr(power_zone)) \
0052             return count; \
0053     } \
0054     \
0055     return -EINVAL; \
0056 }
0057 
0058 /* Power zone constraint show function */
0059 #define define_power_zone_constraint_show(_attr) \
0060 static ssize_t show_constraint_##_attr(struct device *dev, \
0061                 struct device_attribute *dev_attr,\
0062                 char *buf) \
0063 { \
0064     u64 value; \
0065     ssize_t len = -ENODATA; \
0066     struct powercap_zone *power_zone = to_powercap_zone(dev); \
0067     int id; \
0068     struct powercap_zone_constraint *pconst;\
0069     \
0070     if (!sscanf(dev_attr->attr.name, "constraint_%d_", &id)) \
0071         return -EINVAL; \
0072     if (id >= power_zone->const_id_cnt) \
0073         return -EINVAL; \
0074     pconst = &power_zone->constraints[id]; \
0075     if (pconst && pconst->ops && pconst->ops->get_##_attr) { \
0076         if (!pconst->ops->get_##_attr(power_zone, id, &value)) \
0077             len = sprintf(buf, "%lld\n", value); \
0078     } \
0079     \
0080     return len; \
0081 }
0082 
0083 /* Power zone constraint store function */
0084 #define define_power_zone_constraint_store(_attr) \
0085 static ssize_t store_constraint_##_attr(struct device *dev,\
0086                 struct device_attribute *dev_attr, \
0087                 const char *buf, size_t count) \
0088 { \
0089     int err; \
0090     u64 value; \
0091     struct powercap_zone *power_zone = to_powercap_zone(dev); \
0092     int id; \
0093     struct powercap_zone_constraint *pconst;\
0094     \
0095     if (!sscanf(dev_attr->attr.name, "constraint_%d_", &id)) \
0096         return -EINVAL; \
0097     if (id >= power_zone->const_id_cnt) \
0098         return -EINVAL; \
0099     pconst = &power_zone->constraints[id]; \
0100     err = kstrtoull(buf, 10, &value); \
0101     if (err) \
0102         return -EINVAL; \
0103     if (pconst && pconst->ops && pconst->ops->set_##_attr) { \
0104         if (!pconst->ops->set_##_attr(power_zone, id, value)) \
0105             return count; \
0106     } \
0107     \
0108     return -ENODATA; \
0109 }
0110 
0111 /* Power zone information callbacks */
0112 define_power_zone_show(power_uw);
0113 define_power_zone_show(max_power_range_uw);
0114 define_power_zone_show(energy_uj);
0115 define_power_zone_store(energy_uj);
0116 define_power_zone_show(max_energy_range_uj);
0117 
0118 /* Power zone attributes */
0119 static DEVICE_ATTR_RO(max_power_range_uw);
0120 static DEVICE_ATTR_RO(power_uw);
0121 static DEVICE_ATTR_RO(max_energy_range_uj);
0122 static DEVICE_ATTR_RW(energy_uj);
0123 
0124 /* Power zone constraint attributes callbacks */
0125 define_power_zone_constraint_show(power_limit_uw);
0126 define_power_zone_constraint_store(power_limit_uw);
0127 define_power_zone_constraint_show(time_window_us);
0128 define_power_zone_constraint_store(time_window_us);
0129 define_power_zone_constraint_show(max_power_uw);
0130 define_power_zone_constraint_show(min_power_uw);
0131 define_power_zone_constraint_show(max_time_window_us);
0132 define_power_zone_constraint_show(min_time_window_us);
0133 
0134 /* For one time seeding of constraint device attributes */
0135 struct powercap_constraint_attr {
0136     struct device_attribute power_limit_attr;
0137     struct device_attribute time_window_attr;
0138     struct device_attribute max_power_attr;
0139     struct device_attribute min_power_attr;
0140     struct device_attribute max_time_window_attr;
0141     struct device_attribute min_time_window_attr;
0142     struct device_attribute name_attr;
0143 };
0144 
0145 static struct powercap_constraint_attr
0146                 constraint_attrs[MAX_CONSTRAINTS_PER_ZONE];
0147 
0148 /* A list of powercap control_types */
0149 static LIST_HEAD(powercap_cntrl_list);
0150 /* Mutex to protect list of powercap control_types */
0151 static DEFINE_MUTEX(powercap_cntrl_list_lock);
0152 
0153 #define POWERCAP_CONSTRAINT_NAME_LEN    30 /* Some limit to avoid overflow */
0154 static ssize_t show_constraint_name(struct device *dev,
0155                 struct device_attribute *dev_attr,
0156                 char *buf)
0157 {
0158     const char *name;
0159     struct powercap_zone *power_zone = to_powercap_zone(dev);
0160     int id;
0161     ssize_t len = -ENODATA;
0162     struct powercap_zone_constraint *pconst;
0163 
0164     if (!sscanf(dev_attr->attr.name, "constraint_%d_", &id))
0165         return -EINVAL;
0166     if (id >= power_zone->const_id_cnt)
0167         return -EINVAL;
0168     pconst = &power_zone->constraints[id];
0169 
0170     if (pconst && pconst->ops && pconst->ops->get_name) {
0171         name = pconst->ops->get_name(power_zone, id);
0172         if (name) {
0173             sprintf(buf, "%.*s\n", POWERCAP_CONSTRAINT_NAME_LEN - 1,
0174                 name);
0175             len = strlen(buf);
0176         }
0177     }
0178 
0179     return len;
0180 }
0181 
0182 static int create_constraint_attribute(int id, const char *name,
0183                 int mode,
0184                 struct device_attribute *dev_attr,
0185                 ssize_t (*show)(struct device *,
0186                     struct device_attribute *, char *),
0187                 ssize_t (*store)(struct device *,
0188                     struct device_attribute *,
0189                 const char *, size_t)
0190                 )
0191 {
0192 
0193     dev_attr->attr.name = kasprintf(GFP_KERNEL, "constraint_%d_%s",
0194                                 id, name);
0195     if (!dev_attr->attr.name)
0196         return -ENOMEM;
0197     dev_attr->attr.mode = mode;
0198     dev_attr->show = show;
0199     dev_attr->store = store;
0200 
0201     return 0;
0202 }
0203 
0204 static void free_constraint_attributes(void)
0205 {
0206     int i;
0207 
0208     for (i = 0; i < MAX_CONSTRAINTS_PER_ZONE; ++i) {
0209         kfree(constraint_attrs[i].power_limit_attr.attr.name);
0210         kfree(constraint_attrs[i].time_window_attr.attr.name);
0211         kfree(constraint_attrs[i].name_attr.attr.name);
0212         kfree(constraint_attrs[i].max_power_attr.attr.name);
0213         kfree(constraint_attrs[i].min_power_attr.attr.name);
0214         kfree(constraint_attrs[i].max_time_window_attr.attr.name);
0215         kfree(constraint_attrs[i].min_time_window_attr.attr.name);
0216     }
0217 }
0218 
0219 static int seed_constraint_attributes(void)
0220 {
0221     int i;
0222     int ret;
0223 
0224     for (i = 0; i < MAX_CONSTRAINTS_PER_ZONE; ++i) {
0225         ret = create_constraint_attribute(i, "power_limit_uw",
0226                     S_IWUSR | S_IRUGO,
0227                     &constraint_attrs[i].power_limit_attr,
0228                     show_constraint_power_limit_uw,
0229                     store_constraint_power_limit_uw);
0230         if (ret)
0231             goto err_alloc;
0232         ret = create_constraint_attribute(i, "time_window_us",
0233                     S_IWUSR | S_IRUGO,
0234                     &constraint_attrs[i].time_window_attr,
0235                     show_constraint_time_window_us,
0236                     store_constraint_time_window_us);
0237         if (ret)
0238             goto err_alloc;
0239         ret = create_constraint_attribute(i, "name", S_IRUGO,
0240                 &constraint_attrs[i].name_attr,
0241                 show_constraint_name,
0242                 NULL);
0243         if (ret)
0244             goto err_alloc;
0245         ret = create_constraint_attribute(i, "max_power_uw", S_IRUGO,
0246                 &constraint_attrs[i].max_power_attr,
0247                 show_constraint_max_power_uw,
0248                 NULL);
0249         if (ret)
0250             goto err_alloc;
0251         ret = create_constraint_attribute(i, "min_power_uw", S_IRUGO,
0252                 &constraint_attrs[i].min_power_attr,
0253                 show_constraint_min_power_uw,
0254                 NULL);
0255         if (ret)
0256             goto err_alloc;
0257         ret = create_constraint_attribute(i, "max_time_window_us",
0258                 S_IRUGO,
0259                 &constraint_attrs[i].max_time_window_attr,
0260                 show_constraint_max_time_window_us,
0261                 NULL);
0262         if (ret)
0263             goto err_alloc;
0264         ret = create_constraint_attribute(i, "min_time_window_us",
0265                 S_IRUGO,
0266                 &constraint_attrs[i].min_time_window_attr,
0267                 show_constraint_min_time_window_us,
0268                 NULL);
0269         if (ret)
0270             goto err_alloc;
0271 
0272     }
0273 
0274     return 0;
0275 
0276 err_alloc:
0277     free_constraint_attributes();
0278 
0279     return ret;
0280 }
0281 
0282 static int create_constraints(struct powercap_zone *power_zone,
0283             int nr_constraints,
0284             const struct powercap_zone_constraint_ops *const_ops)
0285 {
0286     int i;
0287     int ret = 0;
0288     int count;
0289     struct powercap_zone_constraint *pconst;
0290 
0291     if (!power_zone || !const_ops || !const_ops->get_power_limit_uw ||
0292                     !const_ops->set_power_limit_uw ||
0293                     !const_ops->get_time_window_us ||
0294                     !const_ops->set_time_window_us)
0295         return -EINVAL;
0296 
0297     count = power_zone->zone_attr_count;
0298     for (i = 0; i < nr_constraints; ++i) {
0299         pconst = &power_zone->constraints[i];
0300         pconst->ops = const_ops;
0301         pconst->id = power_zone->const_id_cnt;
0302         power_zone->const_id_cnt++;
0303         power_zone->zone_dev_attrs[count++] =
0304                 &constraint_attrs[i].power_limit_attr.attr;
0305         power_zone->zone_dev_attrs[count++] =
0306                 &constraint_attrs[i].time_window_attr.attr;
0307         if (pconst->ops->get_name)
0308             power_zone->zone_dev_attrs[count++] =
0309                 &constraint_attrs[i].name_attr.attr;
0310         if (pconst->ops->get_max_power_uw)
0311             power_zone->zone_dev_attrs[count++] =
0312                 &constraint_attrs[i].max_power_attr.attr;
0313         if (pconst->ops->get_min_power_uw)
0314             power_zone->zone_dev_attrs[count++] =
0315                 &constraint_attrs[i].min_power_attr.attr;
0316         if (pconst->ops->get_max_time_window_us)
0317             power_zone->zone_dev_attrs[count++] =
0318                 &constraint_attrs[i].max_time_window_attr.attr;
0319         if (pconst->ops->get_min_time_window_us)
0320             power_zone->zone_dev_attrs[count++] =
0321                 &constraint_attrs[i].min_time_window_attr.attr;
0322     }
0323     power_zone->zone_attr_count = count;
0324 
0325     return ret;
0326 }
0327 
0328 static bool control_type_valid(void *control_type)
0329 {
0330     struct powercap_control_type *pos = NULL;
0331     bool found = false;
0332 
0333     mutex_lock(&powercap_cntrl_list_lock);
0334 
0335     list_for_each_entry(pos, &powercap_cntrl_list, node) {
0336         if (pos == control_type) {
0337             found = true;
0338             break;
0339         }
0340     }
0341     mutex_unlock(&powercap_cntrl_list_lock);
0342 
0343     return found;
0344 }
0345 
0346 static ssize_t name_show(struct device *dev,
0347                 struct device_attribute *attr,
0348                 char *buf)
0349 {
0350     struct powercap_zone *power_zone = to_powercap_zone(dev);
0351 
0352     return sprintf(buf, "%s\n", power_zone->name);
0353 }
0354 
0355 static DEVICE_ATTR_RO(name);
0356 
0357 /* Create zone and attributes in sysfs */
0358 static void create_power_zone_common_attributes(
0359                     struct powercap_zone *power_zone)
0360 {
0361     int count = 0;
0362 
0363     power_zone->zone_dev_attrs[count++] = &dev_attr_name.attr;
0364     if (power_zone->ops->get_max_energy_range_uj)
0365         power_zone->zone_dev_attrs[count++] =
0366                     &dev_attr_max_energy_range_uj.attr;
0367     if (power_zone->ops->get_energy_uj) {
0368         if (power_zone->ops->reset_energy_uj)
0369             dev_attr_energy_uj.attr.mode = S_IWUSR | S_IRUSR;
0370         else
0371             dev_attr_energy_uj.attr.mode = S_IRUSR;
0372         power_zone->zone_dev_attrs[count++] =
0373                     &dev_attr_energy_uj.attr;
0374     }
0375     if (power_zone->ops->get_power_uw)
0376         power_zone->zone_dev_attrs[count++] =
0377                     &dev_attr_power_uw.attr;
0378     if (power_zone->ops->get_max_power_range_uw)
0379         power_zone->zone_dev_attrs[count++] =
0380                     &dev_attr_max_power_range_uw.attr;
0381     power_zone->zone_dev_attrs[count] = NULL;
0382     power_zone->zone_attr_count = count;
0383 }
0384 
0385 static void powercap_release(struct device *dev)
0386 {
0387     bool allocated;
0388 
0389     if (dev->parent) {
0390         struct powercap_zone *power_zone = to_powercap_zone(dev);
0391 
0392         /* Store flag as the release() may free memory */
0393         allocated = power_zone->allocated;
0394         /* Remove id from parent idr struct */
0395         idr_remove(power_zone->parent_idr, power_zone->id);
0396         /* Destroy idrs allocated for this zone */
0397         idr_destroy(&power_zone->idr);
0398         kfree(power_zone->name);
0399         kfree(power_zone->zone_dev_attrs);
0400         kfree(power_zone->constraints);
0401         if (power_zone->ops->release)
0402             power_zone->ops->release(power_zone);
0403         if (allocated)
0404             kfree(power_zone);
0405     } else {
0406         struct powercap_control_type *control_type =
0407                         to_powercap_control_type(dev);
0408 
0409         /* Store flag as the release() may free memory */
0410         allocated = control_type->allocated;
0411         idr_destroy(&control_type->idr);
0412         mutex_destroy(&control_type->lock);
0413         if (control_type->ops && control_type->ops->release)
0414             control_type->ops->release(control_type);
0415         if (allocated)
0416             kfree(control_type);
0417     }
0418 }
0419 
0420 static ssize_t enabled_show(struct device *dev,
0421                 struct device_attribute *attr,
0422                 char *buf)
0423 {
0424     bool mode = true;
0425 
0426     /* Default is enabled */
0427     if (dev->parent) {
0428         struct powercap_zone *power_zone = to_powercap_zone(dev);
0429         if (power_zone->ops->get_enable)
0430             if (power_zone->ops->get_enable(power_zone, &mode))
0431                 mode = false;
0432     } else {
0433         struct powercap_control_type *control_type =
0434                         to_powercap_control_type(dev);
0435         if (control_type->ops && control_type->ops->get_enable)
0436             if (control_type->ops->get_enable(control_type, &mode))
0437                 mode = false;
0438     }
0439 
0440     return sprintf(buf, "%d\n", mode);
0441 }
0442 
0443 static ssize_t enabled_store(struct device *dev,
0444                 struct device_attribute *attr,
0445                 const char *buf,  size_t len)
0446 {
0447     bool mode;
0448 
0449     if (strtobool(buf, &mode))
0450         return -EINVAL;
0451     if (dev->parent) {
0452         struct powercap_zone *power_zone = to_powercap_zone(dev);
0453         if (power_zone->ops->set_enable)
0454             if (!power_zone->ops->set_enable(power_zone, mode))
0455                 return len;
0456     } else {
0457         struct powercap_control_type *control_type =
0458                         to_powercap_control_type(dev);
0459         if (control_type->ops && control_type->ops->set_enable)
0460             if (!control_type->ops->set_enable(control_type, mode))
0461                 return len;
0462     }
0463 
0464     return -ENOSYS;
0465 }
0466 
0467 static DEVICE_ATTR_RW(enabled);
0468 
0469 static struct attribute *powercap_attrs[] = {
0470     &dev_attr_enabled.attr,
0471     NULL,
0472 };
0473 ATTRIBUTE_GROUPS(powercap);
0474 
0475 static struct class powercap_class = {
0476     .name = "powercap",
0477     .dev_release = powercap_release,
0478     .dev_groups = powercap_groups,
0479 };
0480 
0481 struct powercap_zone *powercap_register_zone(
0482             struct powercap_zone *power_zone,
0483             struct powercap_control_type *control_type,
0484             const char *name,
0485             struct powercap_zone *parent,
0486             const struct powercap_zone_ops *ops,
0487             int nr_constraints,
0488             const struct powercap_zone_constraint_ops *const_ops)
0489 {
0490     int result;
0491     int nr_attrs;
0492 
0493     if (!name || !control_type || !ops ||
0494             nr_constraints > MAX_CONSTRAINTS_PER_ZONE ||
0495             (!ops->get_energy_uj && !ops->get_power_uw) ||
0496             !control_type_valid(control_type))
0497         return ERR_PTR(-EINVAL);
0498 
0499     if (power_zone) {
0500         if (!ops->release)
0501             return ERR_PTR(-EINVAL);
0502         memset(power_zone, 0, sizeof(*power_zone));
0503     } else {
0504         power_zone = kzalloc(sizeof(*power_zone), GFP_KERNEL);
0505         if (!power_zone)
0506             return ERR_PTR(-ENOMEM);
0507         power_zone->allocated = true;
0508     }
0509     power_zone->ops = ops;
0510     power_zone->control_type_inst = control_type;
0511     if (!parent) {
0512         power_zone->dev.parent = &control_type->dev;
0513         power_zone->parent_idr = &control_type->idr;
0514     } else {
0515         power_zone->dev.parent = &parent->dev;
0516         power_zone->parent_idr = &parent->idr;
0517     }
0518     power_zone->dev.class = &powercap_class;
0519 
0520     mutex_lock(&control_type->lock);
0521     /* Using idr to get the unique id */
0522     result = idr_alloc(power_zone->parent_idr, NULL, 0, 0, GFP_KERNEL);
0523     if (result < 0)
0524         goto err_idr_alloc;
0525 
0526     power_zone->id = result;
0527     idr_init(&power_zone->idr);
0528     result = -ENOMEM;
0529     power_zone->name = kstrdup(name, GFP_KERNEL);
0530     if (!power_zone->name)
0531         goto err_name_alloc;
0532     dev_set_name(&power_zone->dev, "%s:%x",
0533                     dev_name(power_zone->dev.parent),
0534                     power_zone->id);
0535     power_zone->constraints = kcalloc(nr_constraints,
0536                       sizeof(*power_zone->constraints),
0537                       GFP_KERNEL);
0538     if (!power_zone->constraints)
0539         goto err_const_alloc;
0540 
0541     nr_attrs = nr_constraints * POWERCAP_CONSTRAINTS_ATTRS +
0542                         POWERCAP_ZONE_MAX_ATTRS + 1;
0543     power_zone->zone_dev_attrs = kcalloc(nr_attrs, sizeof(void *),
0544                          GFP_KERNEL);
0545     if (!power_zone->zone_dev_attrs)
0546         goto err_attr_alloc;
0547     create_power_zone_common_attributes(power_zone);
0548     result = create_constraints(power_zone, nr_constraints, const_ops);
0549     if (result)
0550         goto err_dev_ret;
0551 
0552     power_zone->zone_dev_attrs[power_zone->zone_attr_count] = NULL;
0553     power_zone->dev_zone_attr_group.attrs = power_zone->zone_dev_attrs;
0554     power_zone->dev_attr_groups[0] = &power_zone->dev_zone_attr_group;
0555     power_zone->dev_attr_groups[1] = NULL;
0556     power_zone->dev.groups = power_zone->dev_attr_groups;
0557     result = device_register(&power_zone->dev);
0558     if (result)
0559         goto err_dev_ret;
0560 
0561     control_type->nr_zones++;
0562     mutex_unlock(&control_type->lock);
0563 
0564     return power_zone;
0565 
0566 err_dev_ret:
0567     kfree(power_zone->zone_dev_attrs);
0568 err_attr_alloc:
0569     kfree(power_zone->constraints);
0570 err_const_alloc:
0571     kfree(power_zone->name);
0572 err_name_alloc:
0573     idr_remove(power_zone->parent_idr, power_zone->id);
0574 err_idr_alloc:
0575     if (power_zone->allocated)
0576         kfree(power_zone);
0577     mutex_unlock(&control_type->lock);
0578 
0579     return ERR_PTR(result);
0580 }
0581 EXPORT_SYMBOL_GPL(powercap_register_zone);
0582 
0583 int powercap_unregister_zone(struct powercap_control_type *control_type,
0584                 struct powercap_zone *power_zone)
0585 {
0586     if (!power_zone || !control_type)
0587         return -EINVAL;
0588 
0589     mutex_lock(&control_type->lock);
0590     control_type->nr_zones--;
0591     mutex_unlock(&control_type->lock);
0592 
0593     device_unregister(&power_zone->dev);
0594 
0595     return 0;
0596 }
0597 EXPORT_SYMBOL_GPL(powercap_unregister_zone);
0598 
0599 struct powercap_control_type *powercap_register_control_type(
0600                 struct powercap_control_type *control_type,
0601                 const char *name,
0602                 const struct powercap_control_type_ops *ops)
0603 {
0604     int result;
0605 
0606     if (!name)
0607         return ERR_PTR(-EINVAL);
0608     if (control_type) {
0609         if (!ops || !ops->release)
0610             return ERR_PTR(-EINVAL);
0611         memset(control_type, 0, sizeof(*control_type));
0612     } else {
0613         control_type = kzalloc(sizeof(*control_type), GFP_KERNEL);
0614         if (!control_type)
0615             return ERR_PTR(-ENOMEM);
0616         control_type->allocated = true;
0617     }
0618     mutex_init(&control_type->lock);
0619     control_type->ops = ops;
0620     INIT_LIST_HEAD(&control_type->node);
0621     control_type->dev.class = &powercap_class;
0622     dev_set_name(&control_type->dev, "%s", name);
0623     result = device_register(&control_type->dev);
0624     if (result) {
0625         if (control_type->allocated)
0626             kfree(control_type);
0627         return ERR_PTR(result);
0628     }
0629     idr_init(&control_type->idr);
0630 
0631     mutex_lock(&powercap_cntrl_list_lock);
0632     list_add_tail(&control_type->node, &powercap_cntrl_list);
0633     mutex_unlock(&powercap_cntrl_list_lock);
0634 
0635     return control_type;
0636 }
0637 EXPORT_SYMBOL_GPL(powercap_register_control_type);
0638 
0639 int powercap_unregister_control_type(struct powercap_control_type *control_type)
0640 {
0641     struct powercap_control_type *pos = NULL;
0642 
0643     if (control_type->nr_zones) {
0644         dev_err(&control_type->dev, "Zones of this type still not freed\n");
0645         return -EINVAL;
0646     }
0647     mutex_lock(&powercap_cntrl_list_lock);
0648     list_for_each_entry(pos, &powercap_cntrl_list, node) {
0649         if (pos == control_type) {
0650             list_del(&control_type->node);
0651             mutex_unlock(&powercap_cntrl_list_lock);
0652             device_unregister(&control_type->dev);
0653             return 0;
0654         }
0655     }
0656     mutex_unlock(&powercap_cntrl_list_lock);
0657 
0658     return -ENODEV;
0659 }
0660 EXPORT_SYMBOL_GPL(powercap_unregister_control_type);
0661 
0662 static int __init powercap_init(void)
0663 {
0664     int result;
0665 
0666     result = seed_constraint_attributes();
0667     if (result)
0668         return result;
0669 
0670     return class_register(&powercap_class);
0671 }
0672 
0673 fs_initcall(powercap_init);
0674 
0675 MODULE_DESCRIPTION("PowerCap sysfs Driver");
0676 MODULE_AUTHOR("Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>");
0677 MODULE_LICENSE("GPL v2");
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