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 */
 47struct 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 * @policy: cpufreq policy.
 61 * @cooling_ops: cpufreq callbacks to thermal cooling device ops
 62 * @idle_time: idle time stats
 63 * @qos_req: PM QoS contraint to apply
 64 *
 65 * This structure is required for keeping information of each registered
 66 * cpufreq_cooling_device.
 67 */
 68struct cpufreq_cooling_device {
 69	u32 last_load;
 70	unsigned int cpufreq_state;
 71	unsigned int max_level;
 72	struct em_perf_domain *em;
 73	struct cpufreq_policy *policy;
 74	struct thermal_cooling_device_ops cooling_ops;
 75#ifndef CONFIG_SMP
 76	struct time_in_idle *idle_time;
 77#endif
 78	struct freq_qos_request qos_req;
 79};
 80
 81#ifdef CONFIG_THERMAL_GOV_POWER_ALLOCATOR
 82/**
 83 * get_level: Find the level for a particular frequency
 84 * @cpufreq_cdev: cpufreq_cdev for which the property is required
 85 * @freq: Frequency
 86 *
 87 * Return: level corresponding to the frequency.
 88 */
 89static unsigned long get_level(struct cpufreq_cooling_device *cpufreq_cdev,
 90			       unsigned int freq)
 91{
 92	struct em_perf_state *table;
 93	int i;
 94
 95	rcu_read_lock();
 96	table = em_perf_state_from_pd(cpufreq_cdev->em);
 97	for (i = cpufreq_cdev->max_level - 1; i >= 0; i--) {
 98		if (freq > table[i].frequency)
 99			break;
100	}
101	rcu_read_unlock();
102
103	return cpufreq_cdev->max_level - i - 1;
104}
105
106static u32 cpu_freq_to_power(struct cpufreq_cooling_device *cpufreq_cdev,
107			     u32 freq)
108{
109	struct em_perf_state *table;
110	unsigned long power_mw;
111	int i;
112
113	rcu_read_lock();
114	table = em_perf_state_from_pd(cpufreq_cdev->em);
115	for (i = cpufreq_cdev->max_level - 1; i >= 0; i--) {
116		if (freq > table[i].frequency)
117			break;
118	}
119
120	power_mw = table[i + 1].power;
121	power_mw /= MICROWATT_PER_MILLIWATT;
122	rcu_read_unlock();
123
124	return power_mw;
125}
126
127static u32 cpu_power_to_freq(struct cpufreq_cooling_device *cpufreq_cdev,
128			     u32 power)
129{
130	struct em_perf_state *table;
131	unsigned long em_power_mw;
132	u32 freq;
133	int i;
134
135	rcu_read_lock();
136	table = em_perf_state_from_pd(cpufreq_cdev->em);
137	for (i = cpufreq_cdev->max_level; i > 0; i--) {
138		/* Convert EM power to milli-Watts to make safe comparison */
139		em_power_mw = table[i].power;
140		em_power_mw /= MICROWATT_PER_MILLIWATT;
141		if (power >= em_power_mw)
142			break;
143	}
144	freq = table[i].frequency;
145	rcu_read_unlock();
146
147	return freq;
148}
149
150/**
151 * get_load() - get load for a cpu
152 * @cpufreq_cdev: struct cpufreq_cooling_device for the cpu
153 * @cpu: cpu number
154 * @cpu_idx: index of the cpu in time_in_idle array
155 *
156 * Return: The average load of cpu @cpu in percentage since this
157 * function was last called.
158 */
159#ifdef CONFIG_SMP
160static u32 get_load(struct cpufreq_cooling_device *cpufreq_cdev, int cpu,
161		    int cpu_idx)
162{
163	unsigned long util = sched_cpu_util(cpu);
164
165	return (util * 100) / arch_scale_cpu_capacity(cpu);
166}
167#else /* !CONFIG_SMP */
168static u32 get_load(struct cpufreq_cooling_device *cpufreq_cdev, int cpu,
169		    int cpu_idx)
170{
171	u32 load;
172	u64 now, now_idle, delta_time, delta_idle;
173	struct time_in_idle *idle_time = &cpufreq_cdev->idle_time[cpu_idx];
174
175	now_idle = get_cpu_idle_time(cpu, &now, 0);
176	delta_idle = now_idle - idle_time->time;
177	delta_time = now - idle_time->timestamp;
178
179	if (delta_time <= delta_idle)
180		load = 0;
181	else
182		load = div64_u64(100 * (delta_time - delta_idle), delta_time);
183
184	idle_time->time = now_idle;
185	idle_time->timestamp = now;
186
187	return load;
188}
189#endif /* CONFIG_SMP */
190
191/**
192 * get_dynamic_power() - calculate the dynamic power
193 * @cpufreq_cdev:	&cpufreq_cooling_device for this cdev
194 * @freq:	current frequency
195 *
196 * Return: the dynamic power consumed by the cpus described by
197 * @cpufreq_cdev.
198 */
199static u32 get_dynamic_power(struct cpufreq_cooling_device *cpufreq_cdev,
200			     unsigned long freq)
201{
202	u32 raw_cpu_power;
203
204	raw_cpu_power = cpu_freq_to_power(cpufreq_cdev, freq);
205	return (raw_cpu_power * cpufreq_cdev->last_load) / 100;
206}
207
208/**
209 * cpufreq_get_requested_power() - get the current power
210 * @cdev:	&thermal_cooling_device pointer
211 * @power:	pointer in which to store the resulting power
212 *
213 * Calculate the current power consumption of the cpus in milliwatts
214 * and store it in @power.  This function should actually calculate
215 * the requested power, but it's hard to get the frequency that
216 * cpufreq would have assigned if there were no thermal limits.
217 * Instead, we calculate the current power on the assumption that the
218 * immediate future will look like the immediate past.
219 *
220 * We use the current frequency and the average load since this
221 * function was last called.  In reality, there could have been
222 * multiple opps since this function was last called and that affects
223 * the load calculation.  While it's not perfectly accurate, this
224 * simplification is good enough and works.  REVISIT this, as more
225 * complex code may be needed if experiments show that it's not
226 * accurate enough.
227 *
228 * Return: 0 on success, this function doesn't fail.
229 */
230static int cpufreq_get_requested_power(struct thermal_cooling_device *cdev,
231				       u32 *power)
232{
233	unsigned long freq;
234	int i = 0, cpu;
235	u32 total_load = 0;
236	struct cpufreq_cooling_device *cpufreq_cdev = cdev->devdata;
237	struct cpufreq_policy *policy = cpufreq_cdev->policy;
238
239	freq = cpufreq_quick_get(policy->cpu);
240
241	for_each_cpu(cpu, policy->related_cpus) {
242		u32 load;
243
244		if (cpu_online(cpu))
245			load = get_load(cpufreq_cdev, cpu, i);
246		else
247			load = 0;
248
249		total_load += load;
250	}
251
252	cpufreq_cdev->last_load = total_load;
253
254	*power = get_dynamic_power(cpufreq_cdev, freq);
255
256	trace_thermal_power_cpu_get_power_simple(policy->cpu, *power);
257
258	return 0;
259}
260
261/**
262 * cpufreq_state2power() - convert a cpu cdev state to power consumed
263 * @cdev:	&thermal_cooling_device pointer
264 * @state:	cooling device state to be converted
265 * @power:	pointer in which to store the resulting power
266 *
267 * Convert cooling device state @state into power consumption in
268 * milliwatts assuming 100% load.  Store the calculated power in
269 * @power.
270 *
271 * Return: 0 on success, -EINVAL if the cooling device state is bigger
272 * than maximum allowed.
273 */
274static int cpufreq_state2power(struct thermal_cooling_device *cdev,
275			       unsigned long state, u32 *power)
276{
277	struct cpufreq_cooling_device *cpufreq_cdev = cdev->devdata;
278	unsigned int freq, num_cpus, idx;
279	struct em_perf_state *table;
280
281	/* Request state should be less than max_level */
282	if (state > cpufreq_cdev->max_level)
283		return -EINVAL;
284
285	num_cpus = cpumask_weight(cpufreq_cdev->policy->cpus);
286
287	idx = cpufreq_cdev->max_level - state;
288
289	rcu_read_lock();
290	table = em_perf_state_from_pd(cpufreq_cdev->em);
291	freq = table[idx].frequency;
292	rcu_read_unlock();
293
294	*power = cpu_freq_to_power(cpufreq_cdev, freq) * num_cpus;
295
296	return 0;
297}
298
299/**
300 * cpufreq_power2state() - convert power to a cooling device state
301 * @cdev:	&thermal_cooling_device pointer
302 * @power:	power in milliwatts to be converted
303 * @state:	pointer in which to store the resulting state
304 *
305 * Calculate a cooling device state for the cpus described by @cdev
306 * that would allow them to consume at most @power mW and store it in
307 * @state.  Note that this calculation depends on external factors
308 * such as the CPUs load.  Calling this function with the same power
309 * as input can yield different cooling device states depending on those
310 * external factors.
311 *
312 * Return: 0 on success, this function doesn't fail.
313 */
314static int cpufreq_power2state(struct thermal_cooling_device *cdev,
315			       u32 power, unsigned long *state)
316{
317	unsigned int target_freq;
318	u32 last_load, normalised_power;
319	struct cpufreq_cooling_device *cpufreq_cdev = cdev->devdata;
320	struct cpufreq_policy *policy = cpufreq_cdev->policy;
321
322	last_load = cpufreq_cdev->last_load ?: 1;
323	normalised_power = (power * 100) / last_load;
324	target_freq = cpu_power_to_freq(cpufreq_cdev, normalised_power);
325
326	*state = get_level(cpufreq_cdev, target_freq);
327	trace_thermal_power_cpu_limit(policy->related_cpus, target_freq, *state,
328				      power);
329	return 0;
330}
331
332static inline bool em_is_sane(struct cpufreq_cooling_device *cpufreq_cdev,
333			      struct em_perf_domain *em) {
334	struct cpufreq_policy *policy;
335	unsigned int nr_levels;
336
337	if (!em || em_is_artificial(em))
338		return false;
339
340	policy = cpufreq_cdev->policy;
341	if (!cpumask_equal(policy->related_cpus, em_span_cpus(em))) {
342		pr_err("The span of pd %*pbl is misaligned with cpufreq policy %*pbl\n",
343			cpumask_pr_args(em_span_cpus(em)),
344			cpumask_pr_args(policy->related_cpus));
345		return false;
346	}
347
348	nr_levels = cpufreq_cdev->max_level + 1;
349	if (em_pd_nr_perf_states(em) != nr_levels) {
350		pr_err("The number of performance states in pd %*pbl (%u) doesn't match the number of cooling levels (%u)\n",
351			cpumask_pr_args(em_span_cpus(em)),
352			em_pd_nr_perf_states(em), nr_levels);
353		return false;
354	}
355
356	return true;
357}
358#endif /* CONFIG_THERMAL_GOV_POWER_ALLOCATOR */
359
360#ifdef CONFIG_SMP
361static inline int allocate_idle_time(struct cpufreq_cooling_device *cpufreq_cdev)
362{
363	return 0;
364}
365
366static inline void free_idle_time(struct cpufreq_cooling_device *cpufreq_cdev)
367{
368}
369#else
370static int allocate_idle_time(struct cpufreq_cooling_device *cpufreq_cdev)
371{
372	unsigned int num_cpus = cpumask_weight(cpufreq_cdev->policy->related_cpus);
373
374	cpufreq_cdev->idle_time = kcalloc(num_cpus,
375					  sizeof(*cpufreq_cdev->idle_time),
376					  GFP_KERNEL);
377	if (!cpufreq_cdev->idle_time)
378		return -ENOMEM;
379
380	return 0;
381}
382
383static void free_idle_time(struct cpufreq_cooling_device *cpufreq_cdev)
384{
385	kfree(cpufreq_cdev->idle_time);
386	cpufreq_cdev->idle_time = NULL;
387}
388#endif /* CONFIG_SMP */
389
390static unsigned int get_state_freq(struct cpufreq_cooling_device *cpufreq_cdev,
391				   unsigned long state)
392{
393	struct cpufreq_policy *policy;
394	unsigned long idx;
395
396#ifdef CONFIG_THERMAL_GOV_POWER_ALLOCATOR
397	/* Use the Energy Model table if available */
398	if (cpufreq_cdev->em) {
399		struct em_perf_state *table;
400		unsigned int freq;
401
402		idx = cpufreq_cdev->max_level - state;
403
404		rcu_read_lock();
405		table = em_perf_state_from_pd(cpufreq_cdev->em);
406		freq = table[idx].frequency;
407		rcu_read_unlock();
408
409		return freq;
410	}
411#endif
412
413	/* Otherwise, fallback on the CPUFreq table */
414	policy = cpufreq_cdev->policy;
415	if (policy->freq_table_sorted == CPUFREQ_TABLE_SORTED_ASCENDING)
416		idx = cpufreq_cdev->max_level - state;
417	else
418		idx = state;
419
420	return policy->freq_table[idx].frequency;
421}
422
423/* cpufreq cooling device callback functions are defined below */
424
425/**
426 * cpufreq_get_max_state - callback function to get the max cooling state.
427 * @cdev: thermal cooling device pointer.
428 * @state: fill this variable with the max cooling state.
429 *
430 * Callback for the thermal cooling device to return the cpufreq
431 * max cooling state.
432 *
433 * Return: 0 on success, this function doesn't fail.
434 */
435static int cpufreq_get_max_state(struct thermal_cooling_device *cdev,
436				 unsigned long *state)
437{
438	struct cpufreq_cooling_device *cpufreq_cdev = cdev->devdata;
439
440	*state = cpufreq_cdev->max_level;
441	return 0;
442}
443
444/**
445 * cpufreq_get_cur_state - callback function to get the current cooling state.
446 * @cdev: thermal cooling device pointer.
447 * @state: fill this variable with the current cooling state.
448 *
449 * Callback for the thermal cooling device to return the cpufreq
450 * current cooling state.
451 *
452 * Return: 0 on success, this function doesn't fail.
453 */
454static int cpufreq_get_cur_state(struct thermal_cooling_device *cdev,
455				 unsigned long *state)
456{
457	struct cpufreq_cooling_device *cpufreq_cdev = cdev->devdata;
458
459	*state = cpufreq_cdev->cpufreq_state;
460
461	return 0;
462}
463
464/**
465 * cpufreq_set_cur_state - callback function to set the current cooling state.
466 * @cdev: thermal cooling device pointer.
467 * @state: set this variable to the current cooling state.
468 *
469 * Callback for the thermal cooling device to change the cpufreq
470 * current cooling state.
471 *
472 * Return: 0 on success, an error code otherwise.
473 */
474static int cpufreq_set_cur_state(struct thermal_cooling_device *cdev,
475				 unsigned long state)
476{
477	struct cpufreq_cooling_device *cpufreq_cdev = cdev->devdata;
478	unsigned int frequency;
479	int ret;
480
481	/* Request state should be less than max_level */
482	if (state > cpufreq_cdev->max_level)
483		return -EINVAL;
484
485	/* Check if the old cooling action is same as new cooling action */
486	if (cpufreq_cdev->cpufreq_state == state)
487		return 0;
488
489	frequency = get_state_freq(cpufreq_cdev, state);
490
491	ret = freq_qos_update_request(&cpufreq_cdev->qos_req, frequency);
492	if (ret >= 0) {
493		cpufreq_cdev->cpufreq_state = state;
494		ret = 0;
495	}
496
497	return ret;
498}
499
500/**
501 * __cpufreq_cooling_register - helper function to create cpufreq cooling device
502 * @np: a valid struct device_node to the cooling device tree node
503 * @policy: cpufreq policy
504 * Normally this should be same as cpufreq policy->related_cpus.
505 * @em: Energy Model of the cpufreq policy
506 *
507 * This interface function registers the cpufreq cooling device with the name
508 * "cpufreq-%s". This API can support multiple instances of cpufreq
509 * cooling devices. It also gives the opportunity to link the cooling device
510 * with a device tree node, in order to bind it via the thermal DT code.
511 *
512 * Return: a valid struct thermal_cooling_device pointer on success,
513 * on failure, it returns a corresponding ERR_PTR().
514 */
515static struct thermal_cooling_device *
516__cpufreq_cooling_register(struct device_node *np,
517			struct cpufreq_policy *policy,
518			struct em_perf_domain *em)
519{
520	struct thermal_cooling_device *cdev;
521	struct cpufreq_cooling_device *cpufreq_cdev;
522	unsigned int i;
523	struct device *dev;
524	int ret;
525	struct thermal_cooling_device_ops *cooling_ops;
526	char *name;
527
528	if (IS_ERR_OR_NULL(policy)) {
529		pr_err("%s: cpufreq policy isn't valid: %p\n", __func__, policy);
530		return ERR_PTR(-EINVAL);
531	}
532
533	dev = get_cpu_device(policy->cpu);
534	if (unlikely(!dev)) {
535		pr_warn("No cpu device for cpu %d\n", policy->cpu);
536		return ERR_PTR(-ENODEV);
537	}
538
539	i = cpufreq_table_count_valid_entries(policy);
540	if (!i) {
541		pr_debug("%s: CPUFreq table not found or has no valid entries\n",
542			 __func__);
543		return ERR_PTR(-ENODEV);
544	}
545
546	cpufreq_cdev = kzalloc(sizeof(*cpufreq_cdev), GFP_KERNEL);
547	if (!cpufreq_cdev)
548		return ERR_PTR(-ENOMEM);
549
550	cpufreq_cdev->policy = policy;
551
552	ret = allocate_idle_time(cpufreq_cdev);
553	if (ret) {
554		cdev = ERR_PTR(ret);
555		goto free_cdev;
556	}
557
558	/* max_level is an index, not a counter */
559	cpufreq_cdev->max_level = i - 1;
560
561	cooling_ops = &cpufreq_cdev->cooling_ops;
562	cooling_ops->get_max_state = cpufreq_get_max_state;
563	cooling_ops->get_cur_state = cpufreq_get_cur_state;
564	cooling_ops->set_cur_state = cpufreq_set_cur_state;
565
566#ifdef CONFIG_THERMAL_GOV_POWER_ALLOCATOR
567	if (em_is_sane(cpufreq_cdev, em)) {
568		cpufreq_cdev->em = em;
569		cooling_ops->get_requested_power = cpufreq_get_requested_power;
570		cooling_ops->state2power = cpufreq_state2power;
571		cooling_ops->power2state = cpufreq_power2state;
572	} else
573#endif
574	if (policy->freq_table_sorted == CPUFREQ_TABLE_UNSORTED) {
575		pr_err("%s: unsorted frequency tables are not supported\n",
576		       __func__);
577		cdev = ERR_PTR(-EINVAL);
578		goto free_idle_time;
579	}
580
581	ret = freq_qos_add_request(&policy->constraints,
582				   &cpufreq_cdev->qos_req, FREQ_QOS_MAX,
583				   get_state_freq(cpufreq_cdev, 0));
584	if (ret < 0) {
585		pr_err("%s: Failed to add freq constraint (%d)\n", __func__,
586		       ret);
587		cdev = ERR_PTR(ret);
588		goto free_idle_time;
589	}
590
591	cdev = ERR_PTR(-ENOMEM);
592	name = kasprintf(GFP_KERNEL, "cpufreq-%s", dev_name(dev));
593	if (!name)
594		goto remove_qos_req;
595
596	cdev = thermal_of_cooling_device_register(np, name, cpufreq_cdev,
597						  cooling_ops);
598	kfree(name);
599
600	if (IS_ERR(cdev))
601		goto remove_qos_req;
602
603	return cdev;
604
605remove_qos_req:
606	freq_qos_remove_request(&cpufreq_cdev->qos_req);
607free_idle_time:
608	free_idle_time(cpufreq_cdev);
609free_cdev:
610	kfree(cpufreq_cdev);
611	return cdev;
612}
613
614/**
615 * 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 * "cpufreq-%s". This API can support multiple instances of cpufreq cooling
620 * devices.
621 *
622 * Return: a valid struct thermal_cooling_device pointer on success,
623 * on failure, it returns a corresponding ERR_PTR().
624 */
625struct thermal_cooling_device *
626cpufreq_cooling_register(struct cpufreq_policy *policy)
627{
628	return __cpufreq_cooling_register(NULL, policy, NULL);
629}
630EXPORT_SYMBOL_GPL(cpufreq_cooling_register);
631
632/**
633 * of_cpufreq_cooling_register - function to create cpufreq cooling device.
634 * @policy: cpufreq policy
635 *
636 * This interface function registers the cpufreq cooling device with the name
637 * "cpufreq-%s". This API can support multiple instances of cpufreq cooling
638 * devices. Using this API, the cpufreq cooling device will be linked to the
639 * device tree node provided.
640 *
641 * Using this function, the cooling device will implement the power
642 * extensions by using the Energy Model (if present).  The cpus must have
643 * registered their OPPs using the OPP library.
644 *
645 * Return: a valid struct thermal_cooling_device pointer on success,
646 * and NULL on failure.
647 */
648struct thermal_cooling_device *
649of_cpufreq_cooling_register(struct cpufreq_policy *policy)
650{
651	struct device_node *np = of_get_cpu_node(policy->cpu, NULL);
652	struct thermal_cooling_device *cdev = NULL;
653
654	if (!np) {
655		pr_err("cpufreq_cooling: OF node not available for cpu%d\n",
656		       policy->cpu);
657		return NULL;
658	}
659
660	if (of_property_present(np, "#cooling-cells")) {
661		struct em_perf_domain *em = em_cpu_get(policy->cpu);
662
663		cdev = __cpufreq_cooling_register(np, policy, em);
664		if (IS_ERR(cdev)) {
665			pr_err("cpufreq_cooling: cpu%d failed to register as cooling device: %ld\n",
666			       policy->cpu, PTR_ERR(cdev));
667			cdev = NULL;
668		}
669	}
670
671	of_node_put(np);
672	return cdev;
673}
674EXPORT_SYMBOL_GPL(of_cpufreq_cooling_register);
675
676/**
677 * cpufreq_cooling_unregister - function to remove cpufreq cooling device.
678 * @cdev: thermal cooling device pointer.
679 *
680 * This interface function unregisters the "cpufreq-%x" cooling device.
681 */
682void cpufreq_cooling_unregister(struct thermal_cooling_device *cdev)
683{
684	struct cpufreq_cooling_device *cpufreq_cdev;
685
686	if (!cdev)
687		return;
688
689	cpufreq_cdev = cdev->devdata;
690
691	thermal_cooling_device_unregister(cdev);
692	freq_qos_remove_request(&cpufreq_cdev->qos_req);
693	free_idle_time(cpufreq_cdev);
694	kfree(cpufreq_cdev);
695}
696EXPORT_SYMBOL_GPL(cpufreq_cooling_unregister);