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 
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  */
46 struct time_in_idle {
47 	u64 time;
48 	u64 timestamp;
49 };
50 
51 /**
52  * struct cpufreq_cooling_device - data for cooling device with cpufreq
53  * @last_load: load measured by the latest call to cpufreq_get_requested_power()
54  * @cpufreq_state: integer value representing the current state of cpufreq
55  *	cooling	devices.
56  * @max_level: maximum cooling level. One less than total number of valid
57  *	cpufreq frequencies.
58  * @em: Reference on the Energy Model of the device
59  * @cdev: thermal_cooling_device pointer to keep track of the
60  *	registered cooling device.
61  * @policy: cpufreq policy.
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  */
68 struct 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 #ifndef CONFIG_SMP
75 	struct time_in_idle *idle_time;
76 #endif
77 	struct freq_qos_request qos_req;
78 };
79 
80 #ifdef CONFIG_THERMAL_GOV_POWER_ALLOCATOR
81 /**
82  * get_level: Find the level for a particular frequency
83  * @cpufreq_cdev: cpufreq_cdev for which the property is required
84  * @freq: Frequency
85  *
86  * Return: level corresponding to the frequency.
87  */
88 static unsigned long get_level(struct cpufreq_cooling_device *cpufreq_cdev,
89 			       unsigned int freq)
90 {
91 	int i;
92 
93 	for (i = cpufreq_cdev->max_level - 1; i >= 0; i--) {
94 		if (freq > cpufreq_cdev->em->table[i].frequency)
95 			break;
96 	}
97 
98 	return cpufreq_cdev->max_level - i - 1;
99 }
100 
101 static u32 cpu_freq_to_power(struct cpufreq_cooling_device *cpufreq_cdev,
102 			     u32 freq)
103 {
104 	int i;
105 
106 	for (i = cpufreq_cdev->max_level - 1; i >= 0; i--) {
107 		if (freq > cpufreq_cdev->em->table[i].frequency)
108 			break;
109 	}
110 
111 	return cpufreq_cdev->em->table[i + 1].power;
112 }
113 
114 static u32 cpu_power_to_freq(struct cpufreq_cooling_device *cpufreq_cdev,
115 			     u32 power)
116 {
117 	int i;
118 
119 	for (i = cpufreq_cdev->max_level; i > 0; i--) {
120 		if (power >= cpufreq_cdev->em->table[i].power)
121 			break;
122 	}
123 
124 	return cpufreq_cdev->em->table[i].frequency;
125 }
126 
127 /**
128  * get_load() - get load for a cpu
129  * @cpufreq_cdev: struct cpufreq_cooling_device for the cpu
130  * @cpu: cpu number
131  * @cpu_idx: index of the cpu in time_in_idle array
132  *
133  * Return: The average load of cpu @cpu in percentage since this
134  * function was last called.
135  */
136 #ifdef CONFIG_SMP
137 static u32 get_load(struct cpufreq_cooling_device *cpufreq_cdev, int cpu,
138 		    int cpu_idx)
139 {
140 	unsigned long max = arch_scale_cpu_capacity(cpu);
141 	unsigned long util;
142 
143 	util = sched_cpu_util(cpu, max);
144 	return (util * 100) / max;
145 }
146 #else /* !CONFIG_SMP */
147 static u32 get_load(struct cpufreq_cooling_device *cpufreq_cdev, int cpu,
148 		    int cpu_idx)
149 {
150 	u32 load;
151 	u64 now, now_idle, delta_time, delta_idle;
152 	struct time_in_idle *idle_time = &cpufreq_cdev->idle_time[cpu_idx];
153 
154 	now_idle = get_cpu_idle_time(cpu, &now, 0);
155 	delta_idle = now_idle - idle_time->time;
156 	delta_time = now - idle_time->timestamp;
157 
158 	if (delta_time <= delta_idle)
159 		load = 0;
160 	else
161 		load = div64_u64(100 * (delta_time - delta_idle), delta_time);
162 
163 	idle_time->time = now_idle;
164 	idle_time->timestamp = now;
165 
166 	return load;
167 }
168 #endif /* CONFIG_SMP */
169 
170 /**
171  * get_dynamic_power() - calculate the dynamic power
172  * @cpufreq_cdev:	&cpufreq_cooling_device for this cdev
173  * @freq:	current frequency
174  *
175  * Return: the dynamic power consumed by the cpus described by
176  * @cpufreq_cdev.
177  */
178 static u32 get_dynamic_power(struct cpufreq_cooling_device *cpufreq_cdev,
179 			     unsigned long freq)
180 {
181 	u32 raw_cpu_power;
182 
183 	raw_cpu_power = cpu_freq_to_power(cpufreq_cdev, freq);
184 	return (raw_cpu_power * cpufreq_cdev->last_load) / 100;
185 }
186 
187 /**
188  * cpufreq_get_requested_power() - get the current power
189  * @cdev:	&thermal_cooling_device pointer
190  * @power:	pointer in which to store the resulting power
191  *
192  * Calculate the current power consumption of the cpus in milliwatts
193  * and store it in @power.  This function should actually calculate
194  * the requested power, but it's hard to get the frequency that
195  * cpufreq would have assigned if there were no thermal limits.
196  * Instead, we calculate the current power on the assumption that the
197  * immediate future will look like the immediate past.
198  *
199  * We use the current frequency and the average load since this
200  * function was last called.  In reality, there could have been
201  * multiple opps since this function was last called and that affects
202  * the load calculation.  While it's not perfectly accurate, this
203  * simplification is good enough and works.  REVISIT this, as more
204  * complex code may be needed if experiments show that it's not
205  * accurate enough.
206  *
207  * Return: 0 on success, -E* if getting the static power failed.
208  */
209 static int cpufreq_get_requested_power(struct thermal_cooling_device *cdev,
210 				       u32 *power)
211 {
212 	unsigned long freq;
213 	int i = 0, cpu;
214 	u32 total_load = 0;
215 	struct cpufreq_cooling_device *cpufreq_cdev = cdev->devdata;
216 	struct cpufreq_policy *policy = cpufreq_cdev->policy;
217 	u32 *load_cpu = NULL;
218 
219 	freq = cpufreq_quick_get(policy->cpu);
220 
221 	if (trace_thermal_power_cpu_get_power_enabled()) {
222 		u32 ncpus = cpumask_weight(policy->related_cpus);
223 
224 		load_cpu = kcalloc(ncpus, sizeof(*load_cpu), GFP_KERNEL);
225 	}
226 
227 	for_each_cpu(cpu, policy->related_cpus) {
228 		u32 load;
229 
230 		if (cpu_online(cpu))
231 			load = get_load(cpufreq_cdev, cpu, i);
232 		else
233 			load = 0;
234 
235 		total_load += load;
236 		if (load_cpu)
237 			load_cpu[i] = load;
238 
239 		i++;
240 	}
241 
242 	cpufreq_cdev->last_load = total_load;
243 
244 	*power = get_dynamic_power(cpufreq_cdev, freq);
245 
246 	if (load_cpu) {
247 		trace_thermal_power_cpu_get_power(policy->related_cpus, freq,
248 						  load_cpu, i, *power);
249 
250 		kfree(load_cpu);
251 	}
252 
253 	return 0;
254 }
255 
256 /**
257  * cpufreq_state2power() - convert a cpu cdev state to power consumed
258  * @cdev:	&thermal_cooling_device pointer
259  * @state:	cooling device state to be converted
260  * @power:	pointer in which to store the resulting power
261  *
262  * Convert cooling device state @state into power consumption in
263  * milliwatts assuming 100% load.  Store the calculated power in
264  * @power.
265  *
266  * Return: 0 on success, -EINVAL if the cooling device state could not
267  * be converted into a frequency or other -E* if there was an error
268  * when calculating the static power.
269  */
270 static int cpufreq_state2power(struct thermal_cooling_device *cdev,
271 			       unsigned long state, u32 *power)
272 {
273 	unsigned int freq, num_cpus, idx;
274 	struct cpufreq_cooling_device *cpufreq_cdev = cdev->devdata;
275 
276 	/* Request state should be less than max_level */
277 	if (state > cpufreq_cdev->max_level)
278 		return -EINVAL;
279 
280 	num_cpus = cpumask_weight(cpufreq_cdev->policy->cpus);
281 
282 	idx = cpufreq_cdev->max_level - state;
283 	freq = cpufreq_cdev->em->table[idx].frequency;
284 	*power = cpu_freq_to_power(cpufreq_cdev, freq) * num_cpus;
285 
286 	return 0;
287 }
288 
289 /**
290  * cpufreq_power2state() - convert power to a cooling device state
291  * @cdev:	&thermal_cooling_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  */
308 static int cpufreq_power2state(struct thermal_cooling_device *cdev,
309 			       u32 power, unsigned long *state)
310 {
311 	unsigned int target_freq;
312 	u32 last_load, normalised_power;
313 	struct cpufreq_cooling_device *cpufreq_cdev = cdev->devdata;
314 	struct cpufreq_policy *policy = cpufreq_cdev->policy;
315 
316 	last_load = cpufreq_cdev->last_load ?: 1;
317 	normalised_power = (power * 100) / last_load;
318 	target_freq = cpu_power_to_freq(cpufreq_cdev, normalised_power);
319 
320 	*state = get_level(cpufreq_cdev, target_freq);
321 	trace_thermal_power_cpu_limit(policy->related_cpus, target_freq, *state,
322 				      power);
323 	return 0;
324 }
325 
326 static inline bool em_is_sane(struct cpufreq_cooling_device *cpufreq_cdev,
327 			      struct em_perf_domain *em) {
328 	struct cpufreq_policy *policy;
329 	unsigned int nr_levels;
330 
331 	if (!em)
332 		return false;
333 
334 	policy = cpufreq_cdev->policy;
335 	if (!cpumask_equal(policy->related_cpus, em_span_cpus(em))) {
336 		pr_err("The span of pd %*pbl is misaligned with cpufreq policy %*pbl\n",
337 			cpumask_pr_args(em_span_cpus(em)),
338 			cpumask_pr_args(policy->related_cpus));
339 		return false;
340 	}
341 
342 	nr_levels = cpufreq_cdev->max_level + 1;
343 	if (em_pd_nr_perf_states(em) != nr_levels) {
344 		pr_err("The number of performance states in pd %*pbl (%u) doesn't match the number of cooling levels (%u)\n",
345 			cpumask_pr_args(em_span_cpus(em)),
346 			em_pd_nr_perf_states(em), nr_levels);
347 		return false;
348 	}
349 
350 	return true;
351 }
352 #endif /* CONFIG_THERMAL_GOV_POWER_ALLOCATOR */
353 
354 #ifdef CONFIG_SMP
355 static inline int allocate_idle_time(struct cpufreq_cooling_device *cpufreq_cdev)
356 {
357 	return 0;
358 }
359 
360 static inline void free_idle_time(struct cpufreq_cooling_device *cpufreq_cdev)
361 {
362 }
363 #else
364 static int allocate_idle_time(struct cpufreq_cooling_device *cpufreq_cdev)
365 {
366 	unsigned int num_cpus = cpumask_weight(cpufreq_cdev->policy->related_cpus);
367 
368 	cpufreq_cdev->idle_time = kcalloc(num_cpus,
369 					  sizeof(*cpufreq_cdev->idle_time),
370 					  GFP_KERNEL);
371 	if (!cpufreq_cdev->idle_time)
372 		return -ENOMEM;
373 
374 	return 0;
375 }
376 
377 static void free_idle_time(struct cpufreq_cooling_device *cpufreq_cdev)
378 {
379 	kfree(cpufreq_cdev->idle_time);
380 	cpufreq_cdev->idle_time = NULL;
381 }
382 #endif /* CONFIG_SMP */
383 
384 static unsigned int get_state_freq(struct cpufreq_cooling_device *cpufreq_cdev,
385 				   unsigned long state)
386 {
387 	struct cpufreq_policy *policy;
388 	unsigned long idx;
389 
390 #ifdef CONFIG_THERMAL_GOV_POWER_ALLOCATOR
391 	/* Use the Energy Model table if available */
392 	if (cpufreq_cdev->em) {
393 		idx = cpufreq_cdev->max_level - state;
394 		return cpufreq_cdev->em->table[idx].frequency;
395 	}
396 #endif
397 
398 	/* Otherwise, fallback on the CPUFreq table */
399 	policy = cpufreq_cdev->policy;
400 	if (policy->freq_table_sorted == CPUFREQ_TABLE_SORTED_ASCENDING)
401 		idx = cpufreq_cdev->max_level - state;
402 	else
403 		idx = state;
404 
405 	return policy->freq_table[idx].frequency;
406 }
407 
408 /* cpufreq cooling device callback functions are defined below */
409 
410 /**
411  * cpufreq_get_max_state - callback function to get the max cooling state.
412  * @cdev: thermal cooling device pointer.
413  * @state: fill this variable with the max cooling state.
414  *
415  * Callback for the thermal cooling device to return the cpufreq
416  * max cooling state.
417  *
418  * Return: 0 on success, an error code otherwise.
419  */
420 static int cpufreq_get_max_state(struct thermal_cooling_device *cdev,
421 				 unsigned long *state)
422 {
423 	struct cpufreq_cooling_device *cpufreq_cdev = cdev->devdata;
424 
425 	*state = cpufreq_cdev->max_level;
426 	return 0;
427 }
428 
429 /**
430  * cpufreq_get_cur_state - callback function to get the current cooling state.
431  * @cdev: thermal cooling device pointer.
432  * @state: fill this variable with the current cooling state.
433  *
434  * Callback for the thermal cooling device to return the cpufreq
435  * current cooling state.
436  *
437  * Return: 0 on success, an error code otherwise.
438  */
439 static int cpufreq_get_cur_state(struct thermal_cooling_device *cdev,
440 				 unsigned long *state)
441 {
442 	struct cpufreq_cooling_device *cpufreq_cdev = cdev->devdata;
443 
444 	*state = cpufreq_cdev->cpufreq_state;
445 
446 	return 0;
447 }
448 
449 /**
450  * cpufreq_set_cur_state - callback function to set the current cooling state.
451  * @cdev: thermal cooling device pointer.
452  * @state: set this variable to the current cooling state.
453  *
454  * Callback for the thermal cooling device to change the cpufreq
455  * current cooling state.
456  *
457  * Return: 0 on success, an error code otherwise.
458  */
459 static int cpufreq_set_cur_state(struct thermal_cooling_device *cdev,
460 				 unsigned long state)
461 {
462 	struct cpufreq_cooling_device *cpufreq_cdev = cdev->devdata;
463 	struct cpumask *cpus;
464 	unsigned int frequency;
465 	unsigned long max_capacity, capacity;
466 	int ret;
467 
468 	/* Request state should be less than max_level */
469 	if (state > cpufreq_cdev->max_level)
470 		return -EINVAL;
471 
472 	/* Check if the old cooling action is same as new cooling action */
473 	if (cpufreq_cdev->cpufreq_state == state)
474 		return 0;
475 
476 	frequency = get_state_freq(cpufreq_cdev, state);
477 
478 	ret = freq_qos_update_request(&cpufreq_cdev->qos_req, frequency);
479 	if (ret >= 0) {
480 		cpufreq_cdev->cpufreq_state = state;
481 		cpus = cpufreq_cdev->policy->related_cpus;
482 		max_capacity = arch_scale_cpu_capacity(cpumask_first(cpus));
483 		capacity = frequency * max_capacity;
484 		capacity /= cpufreq_cdev->policy->cpuinfo.max_freq;
485 		arch_set_thermal_pressure(cpus, max_capacity - capacity);
486 		ret = 0;
487 	}
488 
489 	return ret;
490 }
491 
492 /* Bind cpufreq callbacks to thermal cooling device ops */
493 
494 static struct thermal_cooling_device_ops cpufreq_cooling_ops = {
495 	.get_max_state		= cpufreq_get_max_state,
496 	.get_cur_state		= cpufreq_get_cur_state,
497 	.set_cur_state		= cpufreq_set_cur_state,
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 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  * "thermal-cpufreq-%x". 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  */
515 static 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 	dev = get_cpu_device(policy->cpu);
529 	if (unlikely(!dev)) {
530 		pr_warn("No cpu device for cpu %d\n", policy->cpu);
531 		return ERR_PTR(-ENODEV);
532 	}
533 
534 	if (IS_ERR_OR_NULL(policy)) {
535 		pr_err("%s: cpufreq policy isn't valid: %p\n", __func__, policy);
536 		return ERR_PTR(-EINVAL);
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_cooling_ops;
562 
563 #ifdef CONFIG_THERMAL_GOV_POWER_ALLOCATOR
564 	if (em_is_sane(cpufreq_cdev, em)) {
565 		cpufreq_cdev->em = em;
566 		cooling_ops->get_requested_power = cpufreq_get_requested_power;
567 		cooling_ops->state2power = cpufreq_state2power;
568 		cooling_ops->power2state = cpufreq_power2state;
569 	} else
570 #endif
571 	if (policy->freq_table_sorted == CPUFREQ_TABLE_UNSORTED) {
572 		pr_err("%s: unsorted frequency tables are not supported\n",
573 		       __func__);
574 		cdev = ERR_PTR(-EINVAL);
575 		goto free_idle_time;
576 	}
577 
578 	ret = freq_qos_add_request(&policy->constraints,
579 				   &cpufreq_cdev->qos_req, FREQ_QOS_MAX,
580 				   get_state_freq(cpufreq_cdev, 0));
581 	if (ret < 0) {
582 		pr_err("%s: Failed to add freq constraint (%d)\n", __func__,
583 		       ret);
584 		cdev = ERR_PTR(ret);
585 		goto free_idle_time;
586 	}
587 
588 	cdev = ERR_PTR(-ENOMEM);
589 	name = kasprintf(GFP_KERNEL, "cpufreq-%s", dev_name(dev));
590 	if (!name)
591 		goto remove_qos_req;
592 
593 	cdev = thermal_of_cooling_device_register(np, name, cpufreq_cdev,
594 						  cooling_ops);
595 	kfree(name);
596 
597 	if (IS_ERR(cdev))
598 		goto remove_qos_req;
599 
600 	return cdev;
601 
602 remove_qos_req:
603 	freq_qos_remove_request(&cpufreq_cdev->qos_req);
604 free_idle_time:
605 	free_idle_time(cpufreq_cdev);
606 free_cdev:
607 	kfree(cpufreq_cdev);
608 	return cdev;
609 }
610 
611 /**
612  * cpufreq_cooling_register - function to create cpufreq cooling device.
613  * @policy: cpufreq policy
614  *
615  * This interface function registers the cpufreq cooling device with the name
616  * "thermal-cpufreq-%x". This api can support multiple instances of cpufreq
617  * cooling devices.
618  *
619  * Return: a valid struct thermal_cooling_device pointer on success,
620  * on failure, it returns a corresponding ERR_PTR().
621  */
622 struct thermal_cooling_device *
623 cpufreq_cooling_register(struct cpufreq_policy *policy)
624 {
625 	return __cpufreq_cooling_register(NULL, policy, NULL);
626 }
627 EXPORT_SYMBOL_GPL(cpufreq_cooling_register);
628 
629 /**
630  * of_cpufreq_cooling_register - function to create cpufreq cooling device.
631  * @policy: cpufreq policy
632  *
633  * This interface function registers the cpufreq cooling device with the name
634  * "thermal-cpufreq-%x". This api can support multiple instances of cpufreq
635  * cooling devices. Using this API, the cpufreq cooling device will be
636  * linked to the device tree node provided.
637  *
638  * Using this function, the cooling device will implement the power
639  * extensions by using a simple cpu power model.  The cpus must have
640  * registered their OPPs using the OPP library.
641  *
642  * It also takes into account, if property present in policy CPU node, the
643  * static power consumed by the cpu.
644  *
645  * Return: a valid struct thermal_cooling_device pointer on success,
646  * and NULL on failure.
647  */
648 struct thermal_cooling_device *
649 of_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_find_property(np, "#cooling-cells", NULL)) {
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 }
674 EXPORT_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 "thermal-cpufreq-%x" cooling device.
681  */
682 void 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 }
696 EXPORT_SYMBOL_GPL(cpufreq_cooling_unregister);
697