drivers/thermal/cpufreq_cooling.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  *  linux/drivers/thermal/cpufreq_cooling.c
   4  *
   5  *  Copyright (C) 2012  Samsung Electronics Co., Ltd(http://www.samsung.com)
   6  *
   7  *  Copyright (C) 2012-2018 Linaro Limited.
   8  *
   9  *  Authors:    Amit Daniel <amit.kachhap@linaro.org>
  10  *              Viresh Kumar <viresh.kumar@linaro.org>
  11  *
  12  */
  13 #include <linux/cpu.h>
  14 #include <linux/cpufreq.h>
  15 #include <linux/cpu_cooling.h>
  16 #include <linux/device.h>
  17 #include <linux/energy_model.h>
  18 #include <linux/err.h>
  19 #include <linux/export.h>
  20 #include <linux/pm_opp.h>
  21 #include <linux/pm_qos.h>
  22 #include <linux/slab.h>
  23 #include <linux/thermal.h>
  24 #include <linux/units.h>
  25
  26 #include <trace/events/thermal.h>
  27
  28 /*
  29  * Cooling state <-> CPUFreq frequency
  30  *
  31  * Cooling states are translated to frequencies throughout this driver and this
  32  * is the relation between them.
  33  *
  34  * Highest cooling state corresponds to lowest possible frequency.
  35  *
  36  * i.e.
  37  *      level 0 --> 1st Max Freq
  38  *      level 1 --> 2nd Max Freq
  39  *      ...
  40  */
  41
  42 /**
  43  * struct time_in_idle - Idle time stats
  44  * @time: previous reading of the absolute time that this cpu was idle
  45  * @timestamp: wall time of the last invocation of get_cpu_idle_time_us()
  46  */
  47 struct time_in_idle {
  48         u64 time;
  49         u64 timestamp;
  50 };
  51
  52 /**
  53  * struct cpufreq_cooling_device - data for cooling device with cpufreq
  54  * @last_load: load measured by the latest call to cpufreq_get_requested_power()
  55  * @cpufreq_state: integer value representing the current state of cpufreq
  56  *      cooling devices.
  57  * @max_level: maximum cooling level. One less than total number of valid
  58  *      cpufreq frequencies.
  59  * @em: Reference on the Energy Model of the device
  60  * @cdev: thermal_cooling_device pointer to keep track of the
  61  *      registered cooling device.
  62  * @policy: cpufreq policy.
  63  * @cooling_ops: cpufreq callbacks to thermal cooling device ops
  64  * @idle_time: idle time stats
  65  * @qos_req: PM QoS contraint to apply
  66  *
  67  * This structure is required for keeping information of each registered
  68  * cpufreq_cooling_device.
  69  */
  70 struct cpufreq_cooling_device {
  71         u32 last_load;
  72         unsigned int cpufreq_state;
  73         unsigned int max_level;
  74         struct em_perf_domain *em;
  75         struct cpufreq_policy *policy;
  76         struct thermal_cooling_device_ops cooling_ops;
  77 #ifndef CONFIG_SMP
  78         struct time_in_idle *idle_time;
  79 #endif
  80         struct freq_qos_request qos_req;
  81 };
  82
  83 #ifdef CONFIG_THERMAL_GOV_POWER_ALLOCATOR
  84 /**
  85  * get_level: Find the level for a particular frequency
  86  * @cpufreq_cdev: cpufreq_cdev for which the property is required
  87  * @freq: Frequency
  88  *
  89  * Return: level corresponding to the frequency.
  90  */
  91 static unsigned long get_level(struct cpufreq_cooling_device *cpufreq_cdev,
  92                                unsigned int freq)
  93 {
  94         int i;
  95
  96         for (i = cpufreq_cdev->max_level - 1; i >= 0; i--) {
  97                 if (freq > cpufreq_cdev->em->table[i].frequency)
  98                         break;
  99         }
 100
 101         return cpufreq_cdev->max_level - i - 1;
 102 }
 103
 104 static u32 cpu_freq_to_power(struct cpufreq_cooling_device *cpufreq_cdev,
 105                              u32 freq)
 106 {
 107         unsigned long power_mw;
 108         int i;
 109
 110         for (i = cpufreq_cdev->max_level - 1; i >= 0; i--) {
 111                 if (freq > cpufreq_cdev->em->table[i].frequency)
 112                         break;
 113         }
 114
 115         power_mw = cpufreq_cdev->em->table[i + 1].power;
 116         power_mw /= MICROWATT_PER_MILLIWATT;
 117
 118         return power_mw;
 119 }
 120
 121 static u32 cpu_power_to_freq(struct cpufreq_cooling_device *cpufreq_cdev,
 122                              u32 power)
 123 {
 124         unsigned long em_power_mw;
 125         int i;
 126
 127         for (i = cpufreq_cdev->max_level; i > 0; i--) {
 128                 /* Convert EM power to milli-Watts to make safe comparison */
 129                 em_power_mw = cpufreq_cdev->em->table[i].power;
 130                 em_power_mw /= MICROWATT_PER_MILLIWATT;
 131                 if (power >= em_power_mw)
 132                         break;
 133         }
 134
 135         return cpufreq_cdev->em->table[i].frequency;
 136 }
 137
 138 /**
 139  * get_load() - get load for a cpu
 140  * @cpufreq_cdev: struct cpufreq_cooling_device for the cpu
 141  * @cpu: cpu number
 142  * @cpu_idx: index of the cpu in time_in_idle array
 143  *
 144  * Return: The average load of cpu @cpu in percentage since this
 145  * function was last called.
 146  */
 147 #ifdef CONFIG_SMP
 148 static u32 get_load(struct cpufreq_cooling_device *cpufreq_cdev, int cpu,
 149                     int cpu_idx)
 150 {
 151         unsigned long util = sched_cpu_util(cpu);
 152
 153         return (util * 100) / arch_scale_cpu_capacity(cpu);
 154 }
 155 #else /* !CONFIG_SMP */
 156 static u32 get_load(struct cpufreq_cooling_device *cpufreq_cdev, int cpu,
 157                     int cpu_idx)
 158 {
 159         u32 load;
 160         u64 now, now_idle, delta_time, delta_idle;
 161         struct time_in_idle *idle_time = &cpufreq_cdev->idle_time[cpu_idx];
 162
 163         now_idle = get_cpu_idle_time(cpu, &now, 0);
 164         delta_idle = now_idle - idle_time->time;
 165         delta_time = now - idle_time->timestamp;
 166
 167         if (delta_time <= delta_idle)
 168                 load = 0;
 169         else
 170                 load = div64_u64(100 * (delta_time - delta_idle), delta_time);
 171
 172         idle_time->time = now_idle;
 173         idle_time->timestamp = now;
 174
 175         return load;
 176 }
 177 #endif /* CONFIG_SMP */
 178
 179 /**
 180  * get_dynamic_power() - calculate the dynamic power
 181  * @cpufreq_cdev:       &cpufreq_cooling_device for this cdev
 182  * @freq:       current frequency
 183  *
 184  * Return: the dynamic power consumed by the cpus described by
 185  * @cpufreq_cdev.
 186  */
 187 static u32 get_dynamic_power(struct cpufreq_cooling_device *cpufreq_cdev,
 188                              unsigned long freq)
 189 {
 190         u32 raw_cpu_power;
 191
 192         raw_cpu_power = cpu_freq_to_power(cpufreq_cdev, freq);
 193         return (raw_cpu_power * cpufreq_cdev->last_load) / 100;
 194 }
 195
 196 /**
 197  * cpufreq_get_requested_power() - get the current power
 198  * @cdev:       &thermal_cooling_device pointer
 199  * @power:      pointer in which to store the resulting power
 200  *
 201  * Calculate the current power consumption of the cpus in milliwatts
 202  * and store it in @power.  This function should actually calculate
 203  * the requested power, but it's hard to get the frequency that
 204  * cpufreq would have assigned if there were no thermal limits.
 205  * Instead, we calculate the current power on the assumption that the
 206  * immediate future will look like the immediate past.
 207  *
 208  * We use the current frequency and the average load since this
 209  * function was last called.  In reality, there could have been
 210  * multiple opps since this function was last called and that affects
 211  * the load calculation.  While it's not perfectly accurate, this
 212  * simplification is good enough and works.  REVISIT this, as more
 213  * complex code may be needed if experiments show that it's not
 214  * accurate enough.
 215  *
 216  * Return: 0 on success, this function doesn't fail.
 217  */
 218 static int cpufreq_get_requested_power(struct thermal_cooling_device *cdev,
 219                                        u32 *power)
 220 {
 221         unsigned long freq;
 222         int i = 0, cpu;
 223         u32 total_load = 0;
 224         struct cpufreq_cooling_device *cpufreq_cdev = cdev->devdata;
 225         struct cpufreq_policy *policy = cpufreq_cdev->policy;
 226
 227         freq = cpufreq_quick_get(policy->cpu);
 228
 229         for_each_cpu(cpu, policy->related_cpus) {
 230                 u32 load;
 231
 232                 if (cpu_online(cpu))
 233                         load = get_load(cpufreq_cdev, cpu, i);
 234                 else
 235                         load = 0;
 236
 237                 total_load += load;
 238         }
 239
 240         cpufreq_cdev->last_load = total_load;
 241
 242         *power = get_dynamic_power(cpufreq_cdev, freq);
 243
 244         trace_thermal_power_cpu_get_power_simple(policy->cpu, *power);
 245
 246         return 0;
 247 }
 248
 249 /**
 250  * cpufreq_state2power() - convert a cpu cdev state to power consumed
 251  * @cdev:       &thermal_cooling_device pointer
 252  * @state:      cooling device state to be converted
 253  * @power:      pointer in which to store the resulting power
 254  *
 255  * Convert cooling device state @state into power consumption in
 256  * milliwatts assuming 100% load.  Store the calculated power in
 257  * @power.
 258  *
 259  * Return: 0 on success, -EINVAL if the cooling device state is bigger
 260  * than maximum allowed.
 261  */
 262 static int cpufreq_state2power(struct thermal_cooling_device *cdev,
 263                                unsigned long state, u32 *power)
 264 {
 265         unsigned int freq, num_cpus, idx;
 266         struct cpufreq_cooling_device *cpufreq_cdev = cdev->devdata;
 267
 268         /* Request state should be less than max_level */
 269         if (state > cpufreq_cdev->max_level)
 270                 return -EINVAL;
 271
 272         num_cpus = cpumask_weight(cpufreq_cdev->policy->cpus);
 273
 274         idx = cpufreq_cdev->max_level - state;
 275         freq = cpufreq_cdev->em->table[idx].frequency;
 276         *power = cpu_freq_to_power(cpufreq_cdev, freq) * num_cpus;
 277
 278         return 0;
 279 }
 280
 281 /**
 282  * cpufreq_power2state() - convert power to a cooling device state
 283  * @cdev:       &thermal_cooling_device pointer
 284  * @power:      power in milliwatts to be converted
 285  * @state:      pointer in which to store the resulting state
 286  *
 287  * Calculate a cooling device state for the cpus described by @cdev
 288  * that would allow them to consume at most @power mW and store it in
 289  * @state.  Note that this calculation depends on external factors
 290  * such as the CPUs load.  Calling this function with the same power
 291  * as input can yield different cooling device states depending on those
 292  * external factors.
 293  *
 294  * Return: 0 on success, this function doesn't fail.
 295  */
 296 static int cpufreq_power2state(struct thermal_cooling_device *cdev,
 297                                u32 power, unsigned long *state)
 298 {
 299         unsigned int target_freq;
 300         u32 last_load, normalised_power;
 301         struct cpufreq_cooling_device *cpufreq_cdev = cdev->devdata;
 302         struct cpufreq_policy *policy = cpufreq_cdev->policy;
 303
 304         last_load = cpufreq_cdev->last_load ?: 1;
 305         normalised_power = (power * 100) / last_load;
 306         target_freq = cpu_power_to_freq(cpufreq_cdev, normalised_power);
 307
 308         *state = get_level(cpufreq_cdev, target_freq);
 309         trace_thermal_power_cpu_limit(policy->related_cpus, target_freq, *state,
 310                                       power);
 311         return 0;
 312 }
 313
 314 static inline bool em_is_sane(struct cpufreq_cooling_device *cpufreq_cdev,
 315                               struct em_perf_domain *em) {
 316         struct cpufreq_policy *policy;
 317         unsigned int nr_levels;
 318
 319         if (!em || em_is_artificial(em))
 320                 return false;
 321
 322         policy = cpufreq_cdev->policy;
 323         if (!cpumask_equal(policy->related_cpus, em_span_cpus(em))) {
 324                 pr_err("The span of pd %*pbl is misaligned with cpufreq policy %*pbl\n",
 325                         cpumask_pr_args(em_span_cpus(em)),
 326                         cpumask_pr_args(policy->related_cpus));
 327                 return false;
 328         }
 329
 330         nr_levels = cpufreq_cdev->max_level + 1;
 331         if (em_pd_nr_perf_states(em) != nr_levels) {
 332                 pr_err("The number of performance states in pd %*pbl (%u) doesn't match the number of cooling levels (%u)\n",
 333                         cpumask_pr_args(em_span_cpus(em)),
 334                         em_pd_nr_perf_states(em), nr_levels);
 335                 return false;
 336         }
 337
 338         return true;
 339 }
 340 #endif /* CONFIG_THERMAL_GOV_POWER_ALLOCATOR */
 341
 342 #ifdef CONFIG_SMP
 343 static inline int allocate_idle_time(struct cpufreq_cooling_device *cpufreq_cdev)
 344 {
 345         return 0;
 346 }
 347
 348 static inline void free_idle_time(struct cpufreq_cooling_device *cpufreq_cdev)
 349 {
 350 }
 351 #else
 352 static int allocate_idle_time(struct cpufreq_cooling_device *cpufreq_cdev)
 353 {
 354         unsigned int num_cpus = cpumask_weight(cpufreq_cdev->policy->related_cpus);
 355
 356         cpufreq_cdev->idle_time = kcalloc(num_cpus,
 357                                           sizeof(*cpufreq_cdev->idle_time),
 358                                           GFP_KERNEL);
 359         if (!cpufreq_cdev->idle_time)
 360                 return -ENOMEM;
 361
 362         return 0;
 363 }
 364
 365 static void free_idle_time(struct cpufreq_cooling_device *cpufreq_cdev)
 366 {
 367         kfree(cpufreq_cdev->idle_time);
 368         cpufreq_cdev->idle_time = NULL;
 369 }
 370 #endif /* CONFIG_SMP */
 371
 372 static unsigned int get_state_freq(struct cpufreq_cooling_device *cpufreq_cdev,
 373                                    unsigned long state)
 374 {
 375         struct cpufreq_policy *policy;
 376         unsigned long idx;
 377
 378 #ifdef CONFIG_THERMAL_GOV_POWER_ALLOCATOR
 379         /* Use the Energy Model table if available */
 380         if (cpufreq_cdev->em) {
 381                 idx = cpufreq_cdev->max_level - state;
 382                 return cpufreq_cdev->em->table[idx].frequency;
 383         }
 384 #endif
 385
 386         /* Otherwise, fallback on the CPUFreq table */
 387         policy = cpufreq_cdev->policy;
 388         if (policy->freq_table_sorted == CPUFREQ_TABLE_SORTED_ASCENDING)
 389                 idx = cpufreq_cdev->max_level - state;
 390         else
 391                 idx = state;
 392
 393         return policy->freq_table[idx].frequency;
 394 }
 395
 396 /* cpufreq cooling device callback functions are defined below */
 397
 398 /**
 399  * cpufreq_get_max_state - callback function to get the max cooling state.
 400  * @cdev: thermal cooling device pointer.
 401  * @state: fill this variable with the max cooling state.
 402  *
 403  * Callback for the thermal cooling device to return the cpufreq
 404  * max cooling state.
 405  *
 406  * Return: 0 on success, this function doesn't fail.
 407  */
 408 static int cpufreq_get_max_state(struct thermal_cooling_device *cdev,
 409                                  unsigned long *state)
 410 {
 411         struct cpufreq_cooling_device *cpufreq_cdev = cdev->devdata;
 412
 413         *state = cpufreq_cdev->max_level;
 414         return 0;
 415 }
 416
 417 /**
 418  * cpufreq_get_cur_state - callback function to get the current cooling state.
 419  * @cdev: thermal cooling device pointer.
 420  * @state: fill this variable with the current cooling state.
 421  *
 422  * Callback for the thermal cooling device to return the cpufreq
 423  * current cooling state.
 424  *
 425  * Return: 0 on success, this function doesn't fail.
 426  */
 427 static int cpufreq_get_cur_state(struct thermal_cooling_device *cdev,
 428                                  unsigned long *state)
 429 {
 430         struct cpufreq_cooling_device *cpufreq_cdev = cdev->devdata;
 431
 432         *state = cpufreq_cdev->cpufreq_state;
 433
 434         return 0;
 435 }
 436
 437 /**
 438  * cpufreq_set_cur_state - callback function to set the current cooling state.
 439  * @cdev: thermal cooling device pointer.
 440  * @state: set this variable to the current cooling state.
 441  *
 442  * Callback for the thermal cooling device to change the cpufreq
 443  * current cooling state.
 444  *
 445  * Return: 0 on success, an error code otherwise.
 446  */
 447 static int cpufreq_set_cur_state(struct thermal_cooling_device *cdev,
 448                                  unsigned long state)
 449 {
 450         struct cpufreq_cooling_device *cpufreq_cdev = cdev->devdata;
 451         struct cpumask *cpus;
 452         unsigned int frequency;
 453         int ret;
 454
 455         /* Request state should be less than max_level */
 456         if (state > cpufreq_cdev->max_level)
 457                 return -EINVAL;
 458
 459         /* Check if the old cooling action is same as new cooling action */
 460         if (cpufreq_cdev->cpufreq_state == state)
 461                 return 0;
 462
 463         frequency = get_state_freq(cpufreq_cdev, state);
 464
 465         ret = freq_qos_update_request(&cpufreq_cdev->qos_req, frequency);
 466         if (ret >= 0) {
 467                 cpufreq_cdev->cpufreq_state = state;
 468                 cpus = cpufreq_cdev->policy->related_cpus;
 469                 arch_update_thermal_pressure(cpus, frequency);
 470                 ret = 0;
 471         }
 472
 473         return ret;
 474 }
 475
 476 /**
 477  * __cpufreq_cooling_register - helper function to create cpufreq cooling device
 478  * @np: a valid struct device_node to the cooling device tree node
 479  * @policy: cpufreq policy
 480  * Normally this should be same as cpufreq policy->related_cpus.
 481  * @em: Energy Model of the cpufreq policy
 482  *
 483  * This interface function registers the cpufreq cooling device with the name
 484  * "cpufreq-%s". This API can support multiple instances of cpufreq
 485  * cooling devices. It also gives the opportunity to link the cooling device
 486  * with a device tree node, in order to bind it via the thermal DT code.
 487  *
 488  * Return: a valid struct thermal_cooling_device pointer on success,
 489  * on failure, it returns a corresponding ERR_PTR().
 490  */
 491 static struct thermal_cooling_device *
 492 __cpufreq_cooling_register(struct device_node *np,
 493                         struct cpufreq_policy *policy,
 494                         struct em_perf_domain *em)
 495 {
 496         struct thermal_cooling_device *cdev;
 497         struct cpufreq_cooling_device *cpufreq_cdev;
 498         unsigned int i;
 499         struct device *dev;
 500         int ret;
 501         struct thermal_cooling_device_ops *cooling_ops;
 502         char *name;
 503
 504         if (IS_ERR_OR_NULL(policy)) {
 505                 pr_err("%s: cpufreq policy isn't valid: %p\n", __func__, policy);
 506                 return ERR_PTR(-EINVAL);
 507         }
 508
 509         dev = get_cpu_device(policy->cpu);
 510         if (unlikely(!dev)) {
 511                 pr_warn("No cpu device for cpu %d\n", policy->cpu);
 512                 return ERR_PTR(-ENODEV);
 513         }
 514
 515         i = cpufreq_table_count_valid_entries(policy);
 516         if (!i) {
 517                 pr_debug("%s: CPUFreq table not found or has no valid entries\n",
 518                          __func__);
 519                 return ERR_PTR(-ENODEV);
 520         }
 521
 522         cpufreq_cdev = kzalloc(sizeof(*cpufreq_cdev), GFP_KERNEL);
 523         if (!cpufreq_cdev)
 524                 return ERR_PTR(-ENOMEM);
 525
 526         cpufreq_cdev->policy = policy;
 527
 528         ret = allocate_idle_time(cpufreq_cdev);
 529         if (ret) {
 530                 cdev = ERR_PTR(ret);
 531                 goto free_cdev;
 532         }
 533
 534         /* max_level is an index, not a counter */
 535         cpufreq_cdev->max_level = i - 1;
 536
 537         cooling_ops = &cpufreq_cdev->cooling_ops;
 538         cooling_ops->get_max_state = cpufreq_get_max_state;
 539         cooling_ops->get_cur_state = cpufreq_get_cur_state;
 540         cooling_ops->set_cur_state = cpufreq_set_cur_state;
 541
 542 #ifdef CONFIG_THERMAL_GOV_POWER_ALLOCATOR
 543         if (em_is_sane(cpufreq_cdev, em)) {
 544                 cpufreq_cdev->em = em;
 545                 cooling_ops->get_requested_power = cpufreq_get_requested_power;
 546                 cooling_ops->state2power = cpufreq_state2power;
 547                 cooling_ops->power2state = cpufreq_power2state;
 548         } else
 549 #endif
 550         if (policy->freq_table_sorted == CPUFREQ_TABLE_UNSORTED) {
 551                 pr_err("%s: unsorted frequency tables are not supported\n",
 552                        __func__);
 553                 cdev = ERR_PTR(-EINVAL);
 554                 goto free_idle_time;
 555         }
 556
 557         ret = freq_qos_add_request(&policy->constraints,
 558                                    &cpufreq_cdev->qos_req, FREQ_QOS_MAX,
 559                                    get_state_freq(cpufreq_cdev, 0));
 560         if (ret < 0) {
 561                 pr_err("%s: Failed to add freq constraint (%d)\n", __func__,
 562                        ret);
 563                 cdev = ERR_PTR(ret);
 564                 goto free_idle_time;
 565         }
 566
 567         cdev = ERR_PTR(-ENOMEM);
 568         name = kasprintf(GFP_KERNEL, "cpufreq-%s", dev_name(dev));
 569         if (!name)
 570                 goto remove_qos_req;
 571
 572         cdev = thermal_of_cooling_device_register(np, name, cpufreq_cdev,
 573                                                   cooling_ops);
 574         kfree(name);
 575
 576         if (IS_ERR(cdev))
 577                 goto remove_qos_req;
 578
 579         return cdev;
 580
 581 remove_qos_req:
 582         freq_qos_remove_request(&cpufreq_cdev->qos_req);
 583 free_idle_time:
 584         free_idle_time(cpufreq_cdev);
 585 free_cdev:
 586         kfree(cpufreq_cdev);
 587         return cdev;
 588 }
 589
 590 /**
 591  * cpufreq_cooling_register - function to create cpufreq cooling device.
 592  * @policy: cpufreq policy
 593  *
 594  * This interface function registers the cpufreq cooling device with the name
 595  * "cpufreq-%s". This API can support multiple instances of cpufreq cooling
 596  * devices.
 597  *
 598  * Return: a valid struct thermal_cooling_device pointer on success,
 599  * on failure, it returns a corresponding ERR_PTR().
 600  */
 601 struct thermal_cooling_device *
 602 cpufreq_cooling_register(struct cpufreq_policy *policy)
 603 {
 604         return __cpufreq_cooling_register(NULL, policy, NULL);
 605 }
 606 EXPORT_SYMBOL_GPL(cpufreq_cooling_register);
 607
 608 /**
 609  * of_cpufreq_cooling_register - function to create cpufreq cooling device.
 610  * @policy: cpufreq policy
 611  *
 612  * This interface function registers the cpufreq cooling device with the name
 613  * "cpufreq-%s". This API can support multiple instances of cpufreq cooling
 614  * devices. Using this API, the cpufreq cooling device will be linked to the
 615  * device tree node provided.
 616  *
 617  * Using this function, the cooling device will implement the power
 618  * extensions by using the Energy Model (if present).  The cpus must have
 619  * registered their OPPs using the OPP library.
 620  *
 621  * Return: a valid struct thermal_cooling_device pointer on success,
 622  * and NULL on failure.
 623  */
 624 struct thermal_cooling_device *
 625 of_cpufreq_cooling_register(struct cpufreq_policy *policy)
 626 {
 627         struct device_node *np = of_get_cpu_node(policy->cpu, NULL);
 628         struct thermal_cooling_device *cdev = NULL;
 629
 630         if (!np) {
 631                 pr_err("cpufreq_cooling: OF node not available for cpu%d\n",
 632                        policy->cpu);
 633                 return NULL;
 634         }
 635
 636         if (of_find_property(np, "#cooling-cells", NULL)) {
 637                 struct em_perf_domain *em = em_cpu_get(policy->cpu);
 638
 639                 cdev = __cpufreq_cooling_register(np, policy, em);
 640                 if (IS_ERR(cdev)) {
 641                         pr_err("cpufreq_cooling: cpu%d failed to register as cooling device: %ld\n",
 642                                policy->cpu, PTR_ERR(cdev));
 643                         cdev = NULL;
 644                 }
 645         }
 646
 647         of_node_put(np);
 648         return cdev;
 649 }
 650 EXPORT_SYMBOL_GPL(of_cpufreq_cooling_register);
 651
 652 /**
 653  * cpufreq_cooling_unregister - function to remove cpufreq cooling device.
 654  * @cdev: thermal cooling device pointer.
 655  *
 656  * This interface function unregisters the "cpufreq-%x" cooling device.
 657  */
 658 void cpufreq_cooling_unregister(struct thermal_cooling_device *cdev)
 659 {
 660         struct cpufreq_cooling_device *cpufreq_cdev;
 661
 662         if (!cdev)
 663                 return;
 664
 665         cpufreq_cdev = cdev->devdata;
 666
 667         thermal_cooling_device_unregister(cdev);
 668         freq_qos_remove_request(&cpufreq_cdev->qos_req);
 669         free_idle_time(cpufreq_cdev);
 670         kfree(cpufreq_cdev);
 671 }
 672 EXPORT_SYMBOL_GPL(cpufreq_cooling_unregister);