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 "thermal_trace.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         struct em_perf_state *table;
  95         int i;
  96
  97         rcu_read_lock();
  98         table = em_perf_state_from_pd(cpufreq_cdev->em);
  99         for (i = cpufreq_cdev->max_level - 1; i >= 0; i--) {
 100                 if (freq > table[i].frequency)
 101                         break;
 102         }
 103         rcu_read_unlock();
 104
 105         return cpufreq_cdev->max_level - i - 1;
 106 }
 107
 108 static u32 cpu_freq_to_power(struct cpufreq_cooling_device *cpufreq_cdev,
 109                              u32 freq)
 110 {
 111         struct em_perf_state *table;
 112         unsigned long power_mw;
 113         int i;
 114
 115         rcu_read_lock();
 116         table = em_perf_state_from_pd(cpufreq_cdev->em);
 117         for (i = cpufreq_cdev->max_level - 1; i >= 0; i--) {
 118                 if (freq > table[i].frequency)
 119                         break;
 120         }
 121
 122         power_mw = table[i + 1].power;
 123         power_mw /= MICROWATT_PER_MILLIWATT;
 124         rcu_read_unlock();
 125
 126         return power_mw;
 127 }
 128
 129 static u32 cpu_power_to_freq(struct cpufreq_cooling_device *cpufreq_cdev,
 130                              u32 power)
 131 {
 132         struct em_perf_state *table;
 133         unsigned long em_power_mw;
 134         u32 freq;
 135         int i;
 136
 137         rcu_read_lock();
 138         table = em_perf_state_from_pd(cpufreq_cdev->em);
 139         for (i = cpufreq_cdev->max_level; i > 0; i--) {
 140                 /* Convert EM power to milli-Watts to make safe comparison */
 141                 em_power_mw = table[i].power;
 142                 em_power_mw /= MICROWATT_PER_MILLIWATT;
 143                 if (power >= em_power_mw)
 144                         break;
 145         }
 146         freq = table[i].frequency;
 147         rcu_read_unlock();
 148
 149         return freq;
 150 }
 151
 152 /**
 153  * get_load() - get load for a cpu
 154  * @cpufreq_cdev: struct cpufreq_cooling_device for the cpu
 155  * @cpu: cpu number
 156  * @cpu_idx: index of the cpu in time_in_idle array
 157  *
 158  * Return: The average load of cpu @cpu in percentage since this
 159  * function was last called.
 160  */
 161 #ifdef CONFIG_SMP
 162 static u32 get_load(struct cpufreq_cooling_device *cpufreq_cdev, int cpu,
 163                     int cpu_idx)
 164 {
 165         unsigned long util = sched_cpu_util(cpu);
 166
 167         return (util * 100) / arch_scale_cpu_capacity(cpu);
 168 }
 169 #else /* !CONFIG_SMP */
 170 static u32 get_load(struct cpufreq_cooling_device *cpufreq_cdev, int cpu,
 171                     int cpu_idx)
 172 {
 173         u32 load;
 174         u64 now, now_idle, delta_time, delta_idle;
 175         struct time_in_idle *idle_time = &cpufreq_cdev->idle_time[cpu_idx];
 176
 177         now_idle = get_cpu_idle_time(cpu, &now, 0);
 178         delta_idle = now_idle - idle_time->time;
 179         delta_time = now - idle_time->timestamp;
 180
 181         if (delta_time <= delta_idle)
 182                 load = 0;
 183         else
 184                 load = div64_u64(100 * (delta_time - delta_idle), delta_time);
 185
 186         idle_time->time = now_idle;
 187         idle_time->timestamp = now;
 188
 189         return load;
 190 }
 191 #endif /* CONFIG_SMP */
 192
 193 /**
 194  * get_dynamic_power() - calculate the dynamic power
 195  * @cpufreq_cdev:       &cpufreq_cooling_device for this cdev
 196  * @freq:       current frequency
 197  *
 198  * Return: the dynamic power consumed by the cpus described by
 199  * @cpufreq_cdev.
 200  */
 201 static u32 get_dynamic_power(struct cpufreq_cooling_device *cpufreq_cdev,
 202                              unsigned long freq)
 203 {
 204         u32 raw_cpu_power;
 205
 206         raw_cpu_power = cpu_freq_to_power(cpufreq_cdev, freq);
 207         return (raw_cpu_power * cpufreq_cdev->last_load) / 100;
 208 }
 209
 210 /**
 211  * cpufreq_get_requested_power() - get the current power
 212  * @cdev:       &thermal_cooling_device pointer
 213  * @power:      pointer in which to store the resulting power
 214  *
 215  * Calculate the current power consumption of the cpus in milliwatts
 216  * and store it in @power.  This function should actually calculate
 217  * the requested power, but it's hard to get the frequency that
 218  * cpufreq would have assigned if there were no thermal limits.
 219  * Instead, we calculate the current power on the assumption that the
 220  * immediate future will look like the immediate past.
 221  *
 222  * We use the current frequency and the average load since this
 223  * function was last called.  In reality, there could have been
 224  * multiple opps since this function was last called and that affects
 225  * the load calculation.  While it's not perfectly accurate, this
 226  * simplification is good enough and works.  REVISIT this, as more
 227  * complex code may be needed if experiments show that it's not
 228  * accurate enough.
 229  *
 230  * Return: 0 on success, this function doesn't fail.
 231  */
 232 static int cpufreq_get_requested_power(struct thermal_cooling_device *cdev,
 233                                        u32 *power)
 234 {
 235         unsigned long freq;
 236         int i = 0, cpu;
 237         u32 total_load = 0;
 238         struct cpufreq_cooling_device *cpufreq_cdev = cdev->devdata;
 239         struct cpufreq_policy *policy = cpufreq_cdev->policy;
 240
 241         freq = cpufreq_quick_get(policy->cpu);
 242
 243         for_each_cpu(cpu, policy->related_cpus) {
 244                 u32 load;
 245
 246                 if (cpu_online(cpu))
 247                         load = get_load(cpufreq_cdev, cpu, i);
 248                 else
 249                         load = 0;
 250
 251                 total_load += load;
 252         }
 253
 254         cpufreq_cdev->last_load = total_load;
 255
 256         *power = get_dynamic_power(cpufreq_cdev, freq);
 257
 258         trace_thermal_power_cpu_get_power_simple(policy->cpu, *power);
 259
 260         return 0;
 261 }
 262
 263 /**
 264  * cpufreq_state2power() - convert a cpu cdev state to power consumed
 265  * @cdev:       &thermal_cooling_device pointer
 266  * @state:      cooling device state to be converted
 267  * @power:      pointer in which to store the resulting power
 268  *
 269  * Convert cooling device state @state into power consumption in
 270  * milliwatts assuming 100% load.  Store the calculated power in
 271  * @power.
 272  *
 273  * Return: 0 on success, -EINVAL if the cooling device state is bigger
 274  * than maximum allowed.
 275  */
 276 static int cpufreq_state2power(struct thermal_cooling_device *cdev,
 277                                unsigned long state, u32 *power)
 278 {
 279         struct cpufreq_cooling_device *cpufreq_cdev = cdev->devdata;
 280         unsigned int freq, num_cpus, idx;
 281         struct em_perf_state *table;
 282
 283         /* Request state should be less than max_level */
 284         if (state > cpufreq_cdev->max_level)
 285                 return -EINVAL;
 286
 287         num_cpus = cpumask_weight(cpufreq_cdev->policy->cpus);
 288
 289         idx = cpufreq_cdev->max_level - state;
 290
 291         rcu_read_lock();
 292         table = em_perf_state_from_pd(cpufreq_cdev->em);
 293         freq = table[idx].frequency;
 294         rcu_read_unlock();
 295
 296         *power = cpu_freq_to_power(cpufreq_cdev, freq) * num_cpus;
 297
 298         return 0;
 299 }
 300
 301 /**
 302  * cpufreq_power2state() - convert power to a cooling device state
 303  * @cdev:       &thermal_cooling_device pointer
 304  * @power:      power in milliwatts to be converted
 305  * @state:      pointer in which to store the resulting state
 306  *
 307  * Calculate a cooling device state for the cpus described by @cdev
 308  * that would allow them to consume at most @power mW and store it in
 309  * @state.  Note that this calculation depends on external factors
 310  * such as the CPUs load.  Calling this function with the same power
 311  * as input can yield different cooling device states depending on those
 312  * external factors.
 313  *
 314  * Return: 0 on success, this function doesn't fail.
 315  */
 316 static int cpufreq_power2state(struct thermal_cooling_device *cdev,
 317                                u32 power, unsigned long *state)
 318 {
 319         unsigned int target_freq;
 320         u32 last_load, normalised_power;
 321         struct cpufreq_cooling_device *cpufreq_cdev = cdev->devdata;
 322         struct cpufreq_policy *policy = cpufreq_cdev->policy;
 323
 324         last_load = cpufreq_cdev->last_load ?: 1;
 325         normalised_power = (power * 100) / last_load;
 326         target_freq = cpu_power_to_freq(cpufreq_cdev, normalised_power);
 327
 328         *state = get_level(cpufreq_cdev, target_freq);
 329         trace_thermal_power_cpu_limit(policy->related_cpus, target_freq, *state,
 330                                       power);
 331         return 0;
 332 }
 333
 334 static inline bool em_is_sane(struct cpufreq_cooling_device *cpufreq_cdev,
 335                               struct em_perf_domain *em) {
 336         struct cpufreq_policy *policy;
 337         unsigned int nr_levels;
 338
 339         if (!em || em_is_artificial(em))
 340                 return false;
 341
 342         policy = cpufreq_cdev->policy;
 343         if (!cpumask_equal(policy->related_cpus, em_span_cpus(em))) {
 344                 pr_err("The span of pd %*pbl is misaligned with cpufreq policy %*pbl\n",
 345                         cpumask_pr_args(em_span_cpus(em)),
 346                         cpumask_pr_args(policy->related_cpus));
 347                 return false;
 348         }
 349
 350         nr_levels = cpufreq_cdev->max_level + 1;
 351         if (em_pd_nr_perf_states(em) != nr_levels) {
 352                 pr_err("The number of performance states in pd %*pbl (%u) doesn't match the number of cooling levels (%u)\n",
 353                         cpumask_pr_args(em_span_cpus(em)),
 354                         em_pd_nr_perf_states(em), nr_levels);
 355                 return false;
 356         }
 357
 358         return true;
 359 }
 360 #endif /* CONFIG_THERMAL_GOV_POWER_ALLOCATOR */
 361
 362 #ifdef CONFIG_SMP
 363 static inline int allocate_idle_time(struct cpufreq_cooling_device *cpufreq_cdev)
 364 {
 365         return 0;
 366 }
 367
 368 static inline void free_idle_time(struct cpufreq_cooling_device *cpufreq_cdev)
 369 {
 370 }
 371 #else
 372 static int allocate_idle_time(struct cpufreq_cooling_device *cpufreq_cdev)
 373 {
 374         unsigned int num_cpus = cpumask_weight(cpufreq_cdev->policy->related_cpus);
 375
 376         cpufreq_cdev->idle_time = kcalloc(num_cpus,
 377                                           sizeof(*cpufreq_cdev->idle_time),
 378                                           GFP_KERNEL);
 379         if (!cpufreq_cdev->idle_time)
 380                 return -ENOMEM;
 381
 382         return 0;
 383 }
 384
 385 static void free_idle_time(struct cpufreq_cooling_device *cpufreq_cdev)
 386 {
 387         kfree(cpufreq_cdev->idle_time);
 388         cpufreq_cdev->idle_time = NULL;
 389 }
 390 #endif /* CONFIG_SMP */
 391
 392 static unsigned int get_state_freq(struct cpufreq_cooling_device *cpufreq_cdev,
 393                                    unsigned long state)
 394 {
 395         struct cpufreq_policy *policy;
 396         unsigned long idx;
 397
 398 #ifdef CONFIG_THERMAL_GOV_POWER_ALLOCATOR
 399         /* Use the Energy Model table if available */
 400         if (cpufreq_cdev->em) {
 401                 struct em_perf_state *table;
 402                 unsigned int freq;
 403
 404                 idx = cpufreq_cdev->max_level - state;
 405
 406                 rcu_read_lock();
 407                 table = em_perf_state_from_pd(cpufreq_cdev->em);
 408                 freq = table[idx].frequency;
 409                 rcu_read_unlock();
 410
 411                 return freq;
 412         }
 413 #endif
 414
 415         /* Otherwise, fallback on the CPUFreq table */
 416         policy = cpufreq_cdev->policy;
 417         if (policy->freq_table_sorted == CPUFREQ_TABLE_SORTED_ASCENDING)
 418                 idx = cpufreq_cdev->max_level - state;
 419         else
 420                 idx = state;
 421
 422         return policy->freq_table[idx].frequency;
 423 }
 424
 425 /* cpufreq cooling device callback functions are defined below */
 426
 427 /**
 428  * cpufreq_get_max_state - callback function to get the max cooling state.
 429  * @cdev: thermal cooling device pointer.
 430  * @state: fill this variable with the max cooling state.
 431  *
 432  * Callback for the thermal cooling device to return the cpufreq
 433  * max cooling state.
 434  *
 435  * Return: 0 on success, this function doesn't fail.
 436  */
 437 static int cpufreq_get_max_state(struct thermal_cooling_device *cdev,
 438                                  unsigned long *state)
 439 {
 440         struct cpufreq_cooling_device *cpufreq_cdev = cdev->devdata;
 441
 442         *state = cpufreq_cdev->max_level;
 443         return 0;
 444 }
 445
 446 /**
 447  * cpufreq_get_cur_state - callback function to get the current cooling state.
 448  * @cdev: thermal cooling device pointer.
 449  * @state: fill this variable with the current cooling state.
 450  *
 451  * Callback for the thermal cooling device to return the cpufreq
 452  * current cooling state.
 453  *
 454  * Return: 0 on success, this function doesn't fail.
 455  */
 456 static int cpufreq_get_cur_state(struct thermal_cooling_device *cdev,
 457                                  unsigned long *state)
 458 {
 459         struct cpufreq_cooling_device *cpufreq_cdev = cdev->devdata;
 460
 461         *state = cpufreq_cdev->cpufreq_state;
 462
 463         return 0;
 464 }
 465
 466 /**
 467  * cpufreq_set_cur_state - callback function to set the current cooling state.
 468  * @cdev: thermal cooling device pointer.
 469  * @state: set this variable to the current cooling state.
 470  *
 471  * Callback for the thermal cooling device to change the cpufreq
 472  * current cooling state.
 473  *
 474  * Return: 0 on success, an error code otherwise.
 475  */
 476 static int cpufreq_set_cur_state(struct thermal_cooling_device *cdev,
 477                                  unsigned long state)
 478 {
 479         struct cpufreq_cooling_device *cpufreq_cdev = cdev->devdata;
 480         struct cpumask *cpus;
 481         unsigned int frequency;
 482         int ret;
 483
 484         /* Request state should be less than max_level */
 485         if (state > cpufreq_cdev->max_level)
 486                 return -EINVAL;
 487
 488         /* Check if the old cooling action is same as new cooling action */
 489         if (cpufreq_cdev->cpufreq_state == state)
 490                 return 0;
 491
 492         frequency = get_state_freq(cpufreq_cdev, state);
 493
 494         ret = freq_qos_update_request(&cpufreq_cdev->qos_req, frequency);
 495         if (ret >= 0) {
 496                 cpufreq_cdev->cpufreq_state = state;
 497                 cpus = cpufreq_cdev->policy->related_cpus;
 498                 arch_update_thermal_pressure(cpus, frequency);
 499                 ret = 0;
 500         }
 501
 502         return ret;
 503 }
 504
 505 /**
 506  * __cpufreq_cooling_register - helper function to create cpufreq cooling device
 507  * @np: a valid struct device_node to the cooling device tree node
 508  * @policy: cpufreq policy
 509  * Normally this should be same as cpufreq policy->related_cpus.
 510  * @em: Energy Model of the cpufreq policy
 511  *
 512  * This interface function registers the cpufreq cooling device with the name
 513  * "cpufreq-%s". This API can support multiple instances of cpufreq
 514  * cooling devices. It also gives the opportunity to link the cooling device
 515  * with a device tree node, in order to bind it via the thermal DT code.
 516  *
 517  * Return: a valid struct thermal_cooling_device pointer on success,
 518  * on failure, it returns a corresponding ERR_PTR().
 519  */
 520 static struct thermal_cooling_device *
 521 __cpufreq_cooling_register(struct device_node *np,
 522                         struct cpufreq_policy *policy,
 523                         struct em_perf_domain *em)
 524 {
 525         struct thermal_cooling_device *cdev;
 526         struct cpufreq_cooling_device *cpufreq_cdev;
 527         unsigned int i;
 528         struct device *dev;
 529         int ret;
 530         struct thermal_cooling_device_ops *cooling_ops;
 531         char *name;
 532
 533         if (IS_ERR_OR_NULL(policy)) {
 534                 pr_err("%s: cpufreq policy isn't valid: %p\n", __func__, policy);
 535                 return ERR_PTR(-EINVAL);
 536         }
 537
 538         dev = get_cpu_device(policy->cpu);
 539         if (unlikely(!dev)) {
 540                 pr_warn("No cpu device for cpu %d\n", policy->cpu);
 541                 return ERR_PTR(-ENODEV);
 542         }
 543
 544         i = cpufreq_table_count_valid_entries(policy);
 545         if (!i) {
 546                 pr_debug("%s: CPUFreq table not found or has no valid entries\n",
 547                          __func__);
 548                 return ERR_PTR(-ENODEV);
 549         }
 550
 551         cpufreq_cdev = kzalloc(sizeof(*cpufreq_cdev), GFP_KERNEL);
 552         if (!cpufreq_cdev)
 553                 return ERR_PTR(-ENOMEM);
 554
 555         cpufreq_cdev->policy = policy;
 556
 557         ret = allocate_idle_time(cpufreq_cdev);
 558         if (ret) {
 559                 cdev = ERR_PTR(ret);
 560                 goto free_cdev;
 561         }
 562
 563         /* max_level is an index, not a counter */
 564         cpufreq_cdev->max_level = i - 1;
 565
 566         cooling_ops = &cpufreq_cdev->cooling_ops;
 567         cooling_ops->get_max_state = cpufreq_get_max_state;
 568         cooling_ops->get_cur_state = cpufreq_get_cur_state;
 569         cooling_ops->set_cur_state = cpufreq_set_cur_state;
 570
 571 #ifdef CONFIG_THERMAL_GOV_POWER_ALLOCATOR
 572         if (em_is_sane(cpufreq_cdev, em)) {
 573                 cpufreq_cdev->em = em;
 574                 cooling_ops->get_requested_power = cpufreq_get_requested_power;
 575                 cooling_ops->state2power = cpufreq_state2power;
 576                 cooling_ops->power2state = cpufreq_power2state;
 577         } else
 578 #endif
 579         if (policy->freq_table_sorted == CPUFREQ_TABLE_UNSORTED) {
 580                 pr_err("%s: unsorted frequency tables are not supported\n",
 581                        __func__);
 582                 cdev = ERR_PTR(-EINVAL);
 583                 goto free_idle_time;
 584         }
 585
 586         ret = freq_qos_add_request(&policy->constraints,
 587                                    &cpufreq_cdev->qos_req, FREQ_QOS_MAX,
 588                                    get_state_freq(cpufreq_cdev, 0));
 589         if (ret < 0) {
 590                 pr_err("%s: Failed to add freq constraint (%d)\n", __func__,
 591                        ret);
 592                 cdev = ERR_PTR(ret);
 593                 goto free_idle_time;
 594         }
 595
 596         cdev = ERR_PTR(-ENOMEM);
 597         name = kasprintf(GFP_KERNEL, "cpufreq-%s", dev_name(dev));
 598         if (!name)
 599                 goto remove_qos_req;
 600
 601         cdev = thermal_of_cooling_device_register(np, name, cpufreq_cdev,
 602                                                   cooling_ops);
 603         kfree(name);
 604
 605         if (IS_ERR(cdev))
 606                 goto remove_qos_req;
 607
 608         return cdev;
 609
 610 remove_qos_req:
 611         freq_qos_remove_request(&cpufreq_cdev->qos_req);
 612 free_idle_time:
 613         free_idle_time(cpufreq_cdev);
 614 free_cdev:
 615         kfree(cpufreq_cdev);
 616         return cdev;
 617 }
 618
 619 /**
 620  * cpufreq_cooling_register - function to create cpufreq cooling device.
 621  * @policy: cpufreq policy
 622  *
 623  * This interface function registers the cpufreq cooling device with the name
 624  * "cpufreq-%s". This API can support multiple instances of cpufreq cooling
 625  * devices.
 626  *
 627  * Return: a valid struct thermal_cooling_device pointer on success,
 628  * on failure, it returns a corresponding ERR_PTR().
 629  */
 630 struct thermal_cooling_device *
 631 cpufreq_cooling_register(struct cpufreq_policy *policy)
 632 {
 633         return __cpufreq_cooling_register(NULL, policy, NULL);
 634 }
 635 EXPORT_SYMBOL_GPL(cpufreq_cooling_register);
 636
 637 /**
 638  * of_cpufreq_cooling_register - function to create cpufreq cooling device.
 639  * @policy: cpufreq policy
 640  *
 641  * This interface function registers the cpufreq cooling device with the name
 642  * "cpufreq-%s". This API can support multiple instances of cpufreq cooling
 643  * devices. Using this API, the cpufreq cooling device will be linked to the
 644  * device tree node provided.
 645  *
 646  * Using this function, the cooling device will implement the power
 647  * extensions by using the Energy Model (if present).  The cpus must have
 648  * registered their OPPs using the OPP library.
 649  *
 650  * Return: a valid struct thermal_cooling_device pointer on success,
 651  * and NULL on failure.
 652  */
 653 struct thermal_cooling_device *
 654 of_cpufreq_cooling_register(struct cpufreq_policy *policy)
 655 {
 656         struct device_node *np = of_get_cpu_node(policy->cpu, NULL);
 657         struct thermal_cooling_device *cdev = NULL;
 658
 659         if (!np) {
 660                 pr_err("cpufreq_cooling: OF node not available for cpu%d\n",
 661                        policy->cpu);
 662                 return NULL;
 663         }
 664
 665         if (of_property_present(np, "#cooling-cells")) {
 666                 struct em_perf_domain *em = em_cpu_get(policy->cpu);
 667
 668                 cdev = __cpufreq_cooling_register(np, policy, em);
 669                 if (IS_ERR(cdev)) {
 670                         pr_err("cpufreq_cooling: cpu%d failed to register as cooling device: %ld\n",
 671                                policy->cpu, PTR_ERR(cdev));
 672                         cdev = NULL;
 673                 }
 674         }
 675
 676         of_node_put(np);
 677         return cdev;
 678 }
 679 EXPORT_SYMBOL_GPL(of_cpufreq_cooling_register);
 680
 681 /**
 682  * cpufreq_cooling_unregister - function to remove cpufreq cooling device.
 683  * @cdev: thermal cooling device pointer.
 684  *
 685  * This interface function unregisters the "cpufreq-%x" cooling device.
 686  */
 687 void cpufreq_cooling_unregister(struct thermal_cooling_device *cdev)
 688 {
 689         struct cpufreq_cooling_device *cpufreq_cdev;
 690
 691         if (!cdev)
 692                 return;
 693
 694         cpufreq_cdev = cdev->devdata;
 695
 696         thermal_cooling_device_unregister(cdev);
 697         freq_qos_remove_request(&cpufreq_cdev->qos_req);
 698         free_idle_time(cpufreq_cdev);
 699         kfree(cpufreq_cdev);
 700 }
 701 EXPORT_SYMBOL_GPL(cpufreq_cooling_unregister);