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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/energy_model.h>
17#include <linux/err.h>
18#include <linux/export.h>
19#include <linux/idr.h>
20#include <linux/pm_opp.h>
21#include <linux/pm_qos.h>
22#include <linux/slab.h>
23#include <linux/thermal.h>
24
25#include <trace/events/thermal.h>
26
27/*
28 * Cooling state <-> CPUFreq frequency
29 *
30 * Cooling states are translated to frequencies throughout this driver and this
31 * is the relation between them.
32 *
33 * Highest cooling state corresponds to lowest possible frequency.
34 *
35 * i.e.
36 * level 0 --> 1st Max Freq
37 * level 1 --> 2nd Max Freq
38 * ...
39 */
40
41/**
42 * struct time_in_idle - Idle time stats
43 * @time: previous reading of the absolute time that this cpu was idle
44 * @timestamp: wall time of the last invocation of get_cpu_idle_time_us()
45 */
46struct time_in_idle {
47 u64 time;
48 u64 timestamp;
49};
50
51/**
52 * struct cpufreq_cooling_device - data for cooling device with cpufreq
53 * @id: unique integer value corresponding to each cpufreq_cooling_device
54 * registered.
55 * @last_load: load measured by the latest call to cpufreq_get_requested_power()
56 * @cpufreq_state: integer value representing the current state of cpufreq
57 * cooling devices.
58 * @max_level: maximum cooling level. One less than total number of valid
59 * cpufreq frequencies.
60 * @em: Reference on the Energy Model of the device
61 * @cdev: thermal_cooling_device pointer to keep track of the
62 * registered cooling device.
63 * @policy: cpufreq policy.
64 * @node: list_head to link all cpufreq_cooling_device together.
65 * @idle_time: idle time stats
66 * @qos_req: PM QoS contraint to apply
67 *
68 * This structure is required for keeping information of each registered
69 * cpufreq_cooling_device.
70 */
71struct cpufreq_cooling_device {
72 int id;
73 u32 last_load;
74 unsigned int cpufreq_state;
75 unsigned int max_level;
76 struct em_perf_domain *em;
77 struct cpufreq_policy *policy;
78 struct list_head node;
79 struct time_in_idle *idle_time;
80 struct freq_qos_request qos_req;
81};
82
83static DEFINE_IDA(cpufreq_ida);
84static DEFINE_MUTEX(cooling_list_lock);
85static LIST_HEAD(cpufreq_cdev_list);
86
87#ifdef CONFIG_THERMAL_GOV_POWER_ALLOCATOR
88/**
89 * get_level: Find the level for a particular frequency
90 * @cpufreq_cdev: cpufreq_cdev for which the property is required
91 * @freq: Frequency
92 *
93 * Return: level corresponding to the frequency.
94 */
95static unsigned long get_level(struct cpufreq_cooling_device *cpufreq_cdev,
96 unsigned int freq)
97{
98 int i;
99
100 for (i = cpufreq_cdev->max_level - 1; i >= 0; i--) {
101 if (freq > cpufreq_cdev->em->table[i].frequency)
102 break;
103 }
104
105 return cpufreq_cdev->max_level - i - 1;
106}
107
108static u32 cpu_freq_to_power(struct cpufreq_cooling_device *cpufreq_cdev,
109 u32 freq)
110{
111 int i;
112
113 for (i = cpufreq_cdev->max_level - 1; i >= 0; i--) {
114 if (freq > cpufreq_cdev->em->table[i].frequency)
115 break;
116 }
117
118 return cpufreq_cdev->em->table[i + 1].power;
119}
120
121static u32 cpu_power_to_freq(struct cpufreq_cooling_device *cpufreq_cdev,
122 u32 power)
123{
124 int i;
125
126 for (i = cpufreq_cdev->max_level; i >= 0; i--) {
127 if (power >= cpufreq_cdev->em->table[i].power)
128 break;
129 }
130
131 return cpufreq_cdev->em->table[i].frequency;
132}
133
134/**
135 * get_load() - get load for a cpu since last updated
136 * @cpufreq_cdev: &struct cpufreq_cooling_device for this cpu
137 * @cpu: cpu number
138 * @cpu_idx: index of the cpu in time_in_idle*
139 *
140 * Return: The average load of cpu @cpu in percentage since this
141 * function was last called.
142 */
143static u32 get_load(struct cpufreq_cooling_device *cpufreq_cdev, int cpu,
144 int cpu_idx)
145{
146 u32 load;
147 u64 now, now_idle, delta_time, delta_idle;
148 struct time_in_idle *idle_time = &cpufreq_cdev->idle_time[cpu_idx];
149
150 now_idle = get_cpu_idle_time(cpu, &now, 0);
151 delta_idle = now_idle - idle_time->time;
152 delta_time = now - idle_time->timestamp;
153
154 if (delta_time <= delta_idle)
155 load = 0;
156 else
157 load = div64_u64(100 * (delta_time - delta_idle), delta_time);
158
159 idle_time->time = now_idle;
160 idle_time->timestamp = now;
161
162 return load;
163}
164
165/**
166 * get_dynamic_power() - calculate the dynamic power
167 * @cpufreq_cdev: &cpufreq_cooling_device for this cdev
168 * @freq: current frequency
169 *
170 * Return: the dynamic power consumed by the cpus described by
171 * @cpufreq_cdev.
172 */
173static u32 get_dynamic_power(struct cpufreq_cooling_device *cpufreq_cdev,
174 unsigned long freq)
175{
176 u32 raw_cpu_power;
177
178 raw_cpu_power = cpu_freq_to_power(cpufreq_cdev, freq);
179 return (raw_cpu_power * cpufreq_cdev->last_load) / 100;
180}
181
182/**
183 * cpufreq_get_requested_power() - get the current power
184 * @cdev: &thermal_cooling_device pointer
185 * @tz: a valid thermal zone device pointer
186 * @power: pointer in which to store the resulting power
187 *
188 * Calculate the current power consumption of the cpus in milliwatts
189 * and store it in @power. This function should actually calculate
190 * the requested power, but it's hard to get the frequency that
191 * cpufreq would have assigned if there were no thermal limits.
192 * Instead, we calculate the current power on the assumption that the
193 * immediate future will look like the immediate past.
194 *
195 * We use the current frequency and the average load since this
196 * function was last called. In reality, there could have been
197 * multiple opps since this function was last called and that affects
198 * the load calculation. While it's not perfectly accurate, this
199 * simplification is good enough and works. REVISIT this, as more
200 * complex code may be needed if experiments show that it's not
201 * accurate enough.
202 *
203 * Return: 0 on success, -E* if getting the static power failed.
204 */
205static int cpufreq_get_requested_power(struct thermal_cooling_device *cdev,
206 struct thermal_zone_device *tz,
207 u32 *power)
208{
209 unsigned long freq;
210 int i = 0, cpu;
211 u32 total_load = 0;
212 struct cpufreq_cooling_device *cpufreq_cdev = cdev->devdata;
213 struct cpufreq_policy *policy = cpufreq_cdev->policy;
214 u32 *load_cpu = NULL;
215
216 freq = cpufreq_quick_get(policy->cpu);
217
218 if (trace_thermal_power_cpu_get_power_enabled()) {
219 u32 ncpus = cpumask_weight(policy->related_cpus);
220
221 load_cpu = kcalloc(ncpus, sizeof(*load_cpu), GFP_KERNEL);
222 }
223
224 for_each_cpu(cpu, policy->related_cpus) {
225 u32 load;
226
227 if (cpu_online(cpu))
228 load = get_load(cpufreq_cdev, cpu, i);
229 else
230 load = 0;
231
232 total_load += load;
233 if (load_cpu)
234 load_cpu[i] = load;
235
236 i++;
237 }
238
239 cpufreq_cdev->last_load = total_load;
240
241 *power = get_dynamic_power(cpufreq_cdev, freq);
242
243 if (load_cpu) {
244 trace_thermal_power_cpu_get_power(policy->related_cpus, freq,
245 load_cpu, i, *power);
246
247 kfree(load_cpu);
248 }
249
250 return 0;
251}
252
253/**
254 * cpufreq_state2power() - convert a cpu cdev state to power consumed
255 * @cdev: &thermal_cooling_device pointer
256 * @tz: a valid thermal zone device pointer
257 * @state: cooling device state to be converted
258 * @power: pointer in which to store the resulting power
259 *
260 * Convert cooling device state @state into power consumption in
261 * milliwatts assuming 100% load. Store the calculated power in
262 * @power.
263 *
264 * Return: 0 on success, -EINVAL if the cooling device state could not
265 * be converted into a frequency or other -E* if there was an error
266 * when calculating the static power.
267 */
268static int cpufreq_state2power(struct thermal_cooling_device *cdev,
269 struct thermal_zone_device *tz,
270 unsigned long state, u32 *power)
271{
272 unsigned int freq, num_cpus, idx;
273 struct cpufreq_cooling_device *cpufreq_cdev = cdev->devdata;
274
275 /* Request state should be less than max_level */
276 if (state > cpufreq_cdev->max_level)
277 return -EINVAL;
278
279 num_cpus = cpumask_weight(cpufreq_cdev->policy->cpus);
280
281 idx = cpufreq_cdev->max_level - state;
282 freq = cpufreq_cdev->em->table[idx].frequency;
283 *power = cpu_freq_to_power(cpufreq_cdev, freq) * num_cpus;
284
285 return 0;
286}
287
288/**
289 * cpufreq_power2state() - convert power to a cooling device state
290 * @cdev: &thermal_cooling_device pointer
291 * @tz: a valid thermal zone device pointer
292 * @power: power in milliwatts to be converted
293 * @state: pointer in which to store the resulting state
294 *
295 * Calculate a cooling device state for the cpus described by @cdev
296 * that would allow them to consume at most @power mW and store it in
297 * @state. Note that this calculation depends on external factors
298 * such as the cpu load or the current static power. Calling this
299 * function with the same power as input can yield different cooling
300 * device states depending on those external factors.
301 *
302 * Return: 0 on success, -ENODEV if no cpus are online or -EINVAL if
303 * the calculated frequency could not be converted to a valid state.
304 * The latter should not happen unless the frequencies available to
305 * cpufreq have changed since the initialization of the cpu cooling
306 * device.
307 */
308static int cpufreq_power2state(struct thermal_cooling_device *cdev,
309 struct thermal_zone_device *tz, u32 power,
310 unsigned long *state)
311{
312 unsigned int target_freq;
313 u32 last_load, normalised_power;
314 struct cpufreq_cooling_device *cpufreq_cdev = cdev->devdata;
315 struct cpufreq_policy *policy = cpufreq_cdev->policy;
316
317 last_load = cpufreq_cdev->last_load ?: 1;
318 normalised_power = (power * 100) / last_load;
319 target_freq = cpu_power_to_freq(cpufreq_cdev, normalised_power);
320
321 *state = get_level(cpufreq_cdev, target_freq);
322 trace_thermal_power_cpu_limit(policy->related_cpus, target_freq, *state,
323 power);
324 return 0;
325}
326
327static inline bool em_is_sane(struct cpufreq_cooling_device *cpufreq_cdev,
328 struct em_perf_domain *em) {
329 struct cpufreq_policy *policy;
330 unsigned int nr_levels;
331
332 if (!em)
333 return false;
334
335 policy = cpufreq_cdev->policy;
336 if (!cpumask_equal(policy->related_cpus, em_span_cpus(em))) {
337 pr_err("The span of pd %*pbl is misaligned with cpufreq policy %*pbl\n",
338 cpumask_pr_args(em_span_cpus(em)),
339 cpumask_pr_args(policy->related_cpus));
340 return false;
341 }
342
343 nr_levels = cpufreq_cdev->max_level + 1;
344 if (em_pd_nr_perf_states(em) != nr_levels) {
345 pr_err("The number of performance states in pd %*pbl (%u) doesn't match the number of cooling levels (%u)\n",
346 cpumask_pr_args(em_span_cpus(em)),
347 em_pd_nr_perf_states(em), nr_levels);
348 return false;
349 }
350
351 return true;
352}
353#endif /* CONFIG_THERMAL_GOV_POWER_ALLOCATOR */
354
355static unsigned int get_state_freq(struct cpufreq_cooling_device *cpufreq_cdev,
356 unsigned long state)
357{
358 struct cpufreq_policy *policy;
359 unsigned long idx;
360
361#ifdef CONFIG_THERMAL_GOV_POWER_ALLOCATOR
362 /* Use the Energy Model table if available */
363 if (cpufreq_cdev->em) {
364 idx = cpufreq_cdev->max_level - state;
365 return cpufreq_cdev->em->table[idx].frequency;
366 }
367#endif
368
369 /* Otherwise, fallback on the CPUFreq table */
370 policy = cpufreq_cdev->policy;
371 if (policy->freq_table_sorted == CPUFREQ_TABLE_SORTED_ASCENDING)
372 idx = cpufreq_cdev->max_level - state;
373 else
374 idx = state;
375
376 return policy->freq_table[idx].frequency;
377}
378
379/* cpufreq cooling device callback functions are defined below */
380
381/**
382 * cpufreq_get_max_state - callback function to get the max cooling state.
383 * @cdev: thermal cooling device pointer.
384 * @state: fill this variable with the max cooling state.
385 *
386 * Callback for the thermal cooling device to return the cpufreq
387 * max cooling state.
388 *
389 * Return: 0 on success, an error code otherwise.
390 */
391static int cpufreq_get_max_state(struct thermal_cooling_device *cdev,
392 unsigned long *state)
393{
394 struct cpufreq_cooling_device *cpufreq_cdev = cdev->devdata;
395
396 *state = cpufreq_cdev->max_level;
397 return 0;
398}
399
400/**
401 * cpufreq_get_cur_state - callback function to get the current cooling state.
402 * @cdev: thermal cooling device pointer.
403 * @state: fill this variable with the current cooling state.
404 *
405 * Callback for the thermal cooling device to return the cpufreq
406 * current cooling state.
407 *
408 * Return: 0 on success, an error code otherwise.
409 */
410static int cpufreq_get_cur_state(struct thermal_cooling_device *cdev,
411 unsigned long *state)
412{
413 struct cpufreq_cooling_device *cpufreq_cdev = cdev->devdata;
414
415 *state = cpufreq_cdev->cpufreq_state;
416
417 return 0;
418}
419
420/**
421 * cpufreq_set_cur_state - callback function to set the current cooling state.
422 * @cdev: thermal cooling device pointer.
423 * @state: set this variable to the current cooling state.
424 *
425 * Callback for the thermal cooling device to change the cpufreq
426 * current cooling state.
427 *
428 * Return: 0 on success, an error code otherwise.
429 */
430static int cpufreq_set_cur_state(struct thermal_cooling_device *cdev,
431 unsigned long state)
432{
433 struct cpufreq_cooling_device *cpufreq_cdev = cdev->devdata;
434 struct cpumask *cpus;
435 unsigned int frequency;
436 unsigned long max_capacity, capacity;
437 int ret;
438
439 /* Request state should be less than max_level */
440 if (state > cpufreq_cdev->max_level)
441 return -EINVAL;
442
443 /* Check if the old cooling action is same as new cooling action */
444 if (cpufreq_cdev->cpufreq_state == state)
445 return 0;
446
447 cpufreq_cdev->cpufreq_state = state;
448
449 frequency = get_state_freq(cpufreq_cdev, state);
450
451 ret = freq_qos_update_request(&cpufreq_cdev->qos_req, frequency);
452
453 if (ret > 0) {
454 cpus = cpufreq_cdev->policy->cpus;
455 max_capacity = arch_scale_cpu_capacity(cpumask_first(cpus));
456 capacity = frequency * max_capacity;
457 capacity /= cpufreq_cdev->policy->cpuinfo.max_freq;
458 arch_set_thermal_pressure(cpus, max_capacity - capacity);
459 ret = 0;
460 }
461
462 return ret;
463}
464
465/* Bind cpufreq callbacks to thermal cooling device ops */
466
467static struct thermal_cooling_device_ops cpufreq_cooling_ops = {
468 .get_max_state = cpufreq_get_max_state,
469 .get_cur_state = cpufreq_get_cur_state,
470 .set_cur_state = cpufreq_set_cur_state,
471};
472
473/**
474 * __cpufreq_cooling_register - helper function to create cpufreq cooling device
475 * @np: a valid struct device_node to the cooling device device tree node
476 * @policy: cpufreq policy
477 * Normally this should be same as cpufreq policy->related_cpus.
478 * @em: Energy Model of the cpufreq policy
479 *
480 * This interface function registers the cpufreq cooling device with the name
481 * "thermal-cpufreq-%x". This api can support multiple instances of cpufreq
482 * cooling devices. It also gives the opportunity to link the cooling device
483 * with a device tree node, in order to bind it via the thermal DT code.
484 *
485 * Return: a valid struct thermal_cooling_device pointer on success,
486 * on failure, it returns a corresponding ERR_PTR().
487 */
488static struct thermal_cooling_device *
489__cpufreq_cooling_register(struct device_node *np,
490 struct cpufreq_policy *policy,
491 struct em_perf_domain *em)
492{
493 struct thermal_cooling_device *cdev;
494 struct cpufreq_cooling_device *cpufreq_cdev;
495 char dev_name[THERMAL_NAME_LENGTH];
496 unsigned int i, num_cpus;
497 struct device *dev;
498 int ret;
499 struct thermal_cooling_device_ops *cooling_ops;
500
501 dev = get_cpu_device(policy->cpu);
502 if (unlikely(!dev)) {
503 pr_warn("No cpu device for cpu %d\n", policy->cpu);
504 return ERR_PTR(-ENODEV);
505 }
506
507
508 if (IS_ERR_OR_NULL(policy)) {
509 pr_err("%s: cpufreq policy isn't valid: %p\n", __func__, policy);
510 return ERR_PTR(-EINVAL);
511 }
512
513 i = cpufreq_table_count_valid_entries(policy);
514 if (!i) {
515 pr_debug("%s: CPUFreq table not found or has no valid entries\n",
516 __func__);
517 return ERR_PTR(-ENODEV);
518 }
519
520 cpufreq_cdev = kzalloc(sizeof(*cpufreq_cdev), GFP_KERNEL);
521 if (!cpufreq_cdev)
522 return ERR_PTR(-ENOMEM);
523
524 cpufreq_cdev->policy = policy;
525 num_cpus = cpumask_weight(policy->related_cpus);
526 cpufreq_cdev->idle_time = kcalloc(num_cpus,
527 sizeof(*cpufreq_cdev->idle_time),
528 GFP_KERNEL);
529 if (!cpufreq_cdev->idle_time) {
530 cdev = ERR_PTR(-ENOMEM);
531 goto free_cdev;
532 }
533
534 /* max_level is an index, not a counter */
535 cpufreq_cdev->max_level = i - 1;
536
537 ret = ida_simple_get(&cpufreq_ida, 0, 0, GFP_KERNEL);
538 if (ret < 0) {
539 cdev = ERR_PTR(ret);
540 goto free_idle_time;
541 }
542 cpufreq_cdev->id = ret;
543
544 snprintf(dev_name, sizeof(dev_name), "thermal-cpufreq-%d",
545 cpufreq_cdev->id);
546
547 cooling_ops = &cpufreq_cooling_ops;
548
549#ifdef CONFIG_THERMAL_GOV_POWER_ALLOCATOR
550 if (em_is_sane(cpufreq_cdev, em)) {
551 cpufreq_cdev->em = em;
552 cooling_ops->get_requested_power = cpufreq_get_requested_power;
553 cooling_ops->state2power = cpufreq_state2power;
554 cooling_ops->power2state = cpufreq_power2state;
555 } else
556#endif
557 if (policy->freq_table_sorted == CPUFREQ_TABLE_UNSORTED) {
558 pr_err("%s: unsorted frequency tables are not supported\n",
559 __func__);
560 cdev = ERR_PTR(-EINVAL);
561 goto remove_ida;
562 }
563
564 ret = freq_qos_add_request(&policy->constraints,
565 &cpufreq_cdev->qos_req, FREQ_QOS_MAX,
566 get_state_freq(cpufreq_cdev, 0));
567 if (ret < 0) {
568 pr_err("%s: Failed to add freq constraint (%d)\n", __func__,
569 ret);
570 cdev = ERR_PTR(ret);
571 goto remove_ida;
572 }
573
574 cdev = thermal_of_cooling_device_register(np, dev_name, cpufreq_cdev,
575 cooling_ops);
576 if (IS_ERR(cdev))
577 goto remove_qos_req;
578
579 mutex_lock(&cooling_list_lock);
580 list_add(&cpufreq_cdev->node, &cpufreq_cdev_list);
581 mutex_unlock(&cooling_list_lock);
582
583 return cdev;
584
585remove_qos_req:
586 freq_qos_remove_request(&cpufreq_cdev->qos_req);
587remove_ida:
588 ida_simple_remove(&cpufreq_ida, cpufreq_cdev->id);
589free_idle_time:
590 kfree(cpufreq_cdev->idle_time);
591free_cdev:
592 kfree(cpufreq_cdev);
593 return cdev;
594}
595
596/**
597 * cpufreq_cooling_register - function to create cpufreq cooling device.
598 * @policy: cpufreq policy
599 *
600 * This interface function registers the cpufreq cooling device with the name
601 * "thermal-cpufreq-%x". This api can support multiple instances of cpufreq
602 * cooling devices.
603 *
604 * Return: a valid struct thermal_cooling_device pointer on success,
605 * on failure, it returns a corresponding ERR_PTR().
606 */
607struct thermal_cooling_device *
608cpufreq_cooling_register(struct cpufreq_policy *policy)
609{
610 return __cpufreq_cooling_register(NULL, policy, NULL);
611}
612EXPORT_SYMBOL_GPL(cpufreq_cooling_register);
613
614/**
615 * of_cpufreq_cooling_register - function to create cpufreq cooling device.
616 * @policy: cpufreq policy
617 *
618 * This interface function registers the cpufreq cooling device with the name
619 * "thermal-cpufreq-%x". This api can support multiple instances of cpufreq
620 * cooling devices. Using this API, the cpufreq cooling device will be
621 * linked to the device tree node provided.
622 *
623 * Using this function, the cooling device will implement the power
624 * extensions by using a simple cpu power model. The cpus must have
625 * registered their OPPs using the OPP library.
626 *
627 * It also takes into account, if property present in policy CPU node, the
628 * static power consumed by the cpu.
629 *
630 * Return: a valid struct thermal_cooling_device pointer on success,
631 * and NULL on failure.
632 */
633struct thermal_cooling_device *
634of_cpufreq_cooling_register(struct cpufreq_policy *policy)
635{
636 struct device_node *np = of_get_cpu_node(policy->cpu, NULL);
637 struct thermal_cooling_device *cdev = NULL;
638
639 if (!np) {
640 pr_err("cpufreq_cooling: OF node not available for cpu%d\n",
641 policy->cpu);
642 return NULL;
643 }
644
645 if (of_find_property(np, "#cooling-cells", NULL)) {
646 struct em_perf_domain *em = em_cpu_get(policy->cpu);
647
648 cdev = __cpufreq_cooling_register(np, policy, em);
649 if (IS_ERR(cdev)) {
650 pr_err("cpufreq_cooling: cpu%d failed to register as cooling device: %ld\n",
651 policy->cpu, PTR_ERR(cdev));
652 cdev = NULL;
653 }
654 }
655
656 of_node_put(np);
657 return cdev;
658}
659EXPORT_SYMBOL_GPL(of_cpufreq_cooling_register);
660
661/**
662 * cpufreq_cooling_unregister - function to remove cpufreq cooling device.
663 * @cdev: thermal cooling device pointer.
664 *
665 * This interface function unregisters the "thermal-cpufreq-%x" cooling device.
666 */
667void cpufreq_cooling_unregister(struct thermal_cooling_device *cdev)
668{
669 struct cpufreq_cooling_device *cpufreq_cdev;
670
671 if (!cdev)
672 return;
673
674 cpufreq_cdev = cdev->devdata;
675
676 mutex_lock(&cooling_list_lock);
677 list_del(&cpufreq_cdev->node);
678 mutex_unlock(&cooling_list_lock);
679
680 thermal_cooling_device_unregister(cdev);
681 freq_qos_remove_request(&cpufreq_cdev->qos_req);
682 ida_simple_remove(&cpufreq_ida, cpufreq_cdev->id);
683 kfree(cpufreq_cdev->idle_time);
684 kfree(cpufreq_cdev);
685}
686EXPORT_SYMBOL_GPL(cpufreq_cooling_unregister);