summaryrefslogtreecommitdiffstats
path: root/drivers/thermal/cpufreq_cooling.c
blob: 3f5f1dce132068bd162091f07c6974195ac1c39b (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
// SPDX-License-Identifier: GPL-2.0
/*
 *  linux/drivers/thermal/cpufreq_cooling.c
 *
 *  Copyright (C) 2012	Samsung Electronics Co., Ltd(http://www.samsung.com)
 *
 *  Copyright (C) 2012-2018 Linaro Limited.
 *
 *  Authors:	Amit Daniel <amit.kachhap@linaro.org>
 *		Viresh Kumar <viresh.kumar@linaro.org>
 *
 */
#include <linux/cpu.h>
#include <linux/cpufreq.h>
#include <linux/cpu_cooling.h>
#include <linux/device.h>
#include <linux/energy_model.h>
#include <linux/err.h>
#include <linux/export.h>
#include <linux/pm_opp.h>
#include <linux/pm_qos.h>
#include <linux/slab.h>
#include <linux/thermal.h>

#include <trace/events/thermal.h>

/*
 * Cooling state <-> CPUFreq frequency
 *
 * Cooling states are translated to frequencies throughout this driver and this
 * is the relation between them.
 *
 * Highest cooling state corresponds to lowest possible frequency.
 *
 * i.e.
 *	level 0 --> 1st Max Freq
 *	level 1 --> 2nd Max Freq
 *	...
 */

/**
 * struct time_in_idle - Idle time stats
 * @time: previous reading of the absolute time that this cpu was idle
 * @timestamp: wall time of the last invocation of get_cpu_idle_time_us()
 */
struct time_in_idle {
	u64 time;
	u64 timestamp;
};

/**
 * struct cpufreq_cooling_device - data for cooling device with cpufreq
 * @last_load: load measured by the latest call to cpufreq_get_requested_power()
 * @cpufreq_state: integer value representing the current state of cpufreq
 *	cooling	devices.
 * @max_level: maximum cooling level. One less than total number of valid
 *	cpufreq frequencies.
 * @em: Reference on the Energy Model of the device
 * @cdev: thermal_cooling_device pointer to keep track of the
 *	registered cooling device.
 * @policy: cpufreq policy.
 * @node: list_head to link all cpufreq_cooling_device together.
 * @idle_time: idle time stats
 * @qos_req: PM QoS contraint to apply
 *
 * This structure is required for keeping information of each registered
 * cpufreq_cooling_device.
 */
struct cpufreq_cooling_device {
	u32 last_load;
	unsigned int cpufreq_state;
	unsigned int max_level;
	struct em_perf_domain *em;
	struct cpufreq_policy *policy;
	struct list_head node;
#ifndef CONFIG_SMP
	struct time_in_idle *idle_time;
#endif
	struct freq_qos_request qos_req;
};

static DEFINE_MUTEX(cooling_list_lock);
static LIST_HEAD(cpufreq_cdev_list);

#ifdef CONFIG_THERMAL_GOV_POWER_ALLOCATOR
/**
 * get_level: Find the level for a particular frequency
 * @cpufreq_cdev: cpufreq_cdev for which the property is required
 * @freq: Frequency
 *
 * Return: level corresponding to the frequency.
 */
static unsigned long get_level(struct cpufreq_cooling_device *cpufreq_cdev,
			       unsigned int freq)
{
	int i;

	for (i = cpufreq_cdev->max_level - 1; i >= 0; i--) {
		if (freq > cpufreq_cdev->em->table[i].frequency)
			break;
	}

	return cpufreq_cdev->max_level - i - 1;
}

static u32 cpu_freq_to_power(struct cpufreq_cooling_device *cpufreq_cdev,
			     u32 freq)
{
	int i;

	for (i = cpufreq_cdev->max_level - 1; i >= 0; i--) {
		if (freq > cpufreq_cdev->em->table[i].frequency)
			break;
	}

	return cpufreq_cdev->em->table[i + 1].power;
}

static u32 cpu_power_to_freq(struct cpufreq_cooling_device *cpufreq_cdev,
			     u32 power)
{
	int i;

	for (i = cpufreq_cdev->max_level; i >= 0; i--) {
		if (power >= cpufreq_cdev->em->table[i].power)
			break;
	}

	return cpufreq_cdev->em->table[i].frequency;
}

/**
 * get_load() - get load for a cpu
 * @cpufreq_cdev: struct cpufreq_cooling_device for the cpu
 * @cpu: cpu number
 * @cpu_idx: index of the cpu in time_in_idle array
 *
 * Return: The average load of cpu @cpu in percentage since this
 * function was last called.
 */
#ifdef CONFIG_SMP
static u32 get_load(struct cpufreq_cooling_device *cpufreq_cdev, int cpu,
		    int cpu_idx)
{
	unsigned long max = arch_scale_cpu_capacity(cpu);
	unsigned long util;

	util = sched_cpu_util(cpu, max);
	return (util * 100) / max;
}
#else /* !CONFIG_SMP */
static u32 get_load(struct cpufreq_cooling_device *cpufreq_cdev, int cpu,
		    int cpu_idx)
{
	u32 load;
	u64 now, now_idle, delta_time, delta_idle;
	struct time_in_idle *idle_time = &cpufreq_cdev->idle_time[cpu_idx];

	now_idle = get_cpu_idle_time(cpu, &now, 0);
	delta_idle = now_idle - idle_time->time;
	delta_time = now - idle_time->timestamp;

	if (delta_time <= delta_idle)
		load = 0;
	else
		load = div64_u64(100 * (delta_time - delta_idle), delta_time);

	idle_time->time = now_idle;
	idle_time->timestamp = now;

	return load;
}
#endif /* CONFIG_SMP */

/**
 * get_dynamic_power() - calculate the dynamic power
 * @cpufreq_cdev:	&cpufreq_cooling_device for this cdev
 * @freq:	current frequency
 *
 * Return: the dynamic power consumed by the cpus described by
 * @cpufreq_cdev.
 */
static u32 get_dynamic_power(struct cpufreq_cooling_device *cpufreq_cdev,
			     unsigned long freq)
{
	u32 raw_cpu_power;

	raw_cpu_power = cpu_freq_to_power(cpufreq_cdev, freq);
	return (raw_cpu_power * cpufreq_cdev->last_load) / 100;
}

/**
 * cpufreq_get_requested_power() - get the current power
 * @cdev:	&thermal_cooling_device pointer
 * @power:	pointer in which to store the resulting power
 *
 * Calculate the current power consumption of the cpus in milliwatts
 * and store it in @power.  This function should actually calculate
 * the requested power, but it's hard to get the frequency that
 * cpufreq would have assigned if there were no thermal limits.
 * Instead, we calculate the current power on the assumption that the
 * immediate future will look like the immediate past.
 *
 * We use the current frequency and the average load since this
 * function was last called.  In reality, there could have been
 * multiple opps since this function was last called and that affects
 * the load calculation.  While it's not perfectly accurate, this
 * simplification is good enough and works.  REVISIT this, as more
 * complex code may be needed if experiments show that it's not
 * accurate enough.
 *
 * Return: 0 on success, -E* if getting the static power failed.
 */
static int cpufreq_get_requested_power(struct thermal_cooling_device *cdev,
				       u32 *power)
{
	unsigned long freq;
	int i = 0, cpu;
	u32 total_load = 0;
	struct cpufreq_cooling_device *cpufreq_cdev = cdev->devdata;
	struct cpufreq_policy *policy = cpufreq_cdev->policy;
	u32 *load_cpu = NULL;

	freq = cpufreq_quick_get(policy->cpu);

	if (trace_thermal_power_cpu_get_power_enabled()) {
		u32 ncpus = cpumask_weight(policy->related_cpus);

		load_cpu = kcalloc(ncpus, sizeof(*load_cpu), GFP_KERNEL);
	}

	for_each_cpu(cpu, policy->related_cpus) {
		u32 load;

		if (cpu_online(cpu))
			load = get_load(cpufreq_cdev, cpu, i);
		else
			load = 0;

		total_load += load;
		if (load_cpu)
			load_cpu[i] = load;

		i++;
	}

	cpufreq_cdev->last_load = total_load;

	*power = get_dynamic_power(cpufreq_cdev, freq);

	if (load_cpu) {
		trace_thermal_power_cpu_get_power(policy->related_cpus, freq,
						  load_cpu, i, *power);

		kfree(load_cpu);
	}

	return 0;
}

/**
 * cpufreq_state2power() - convert a cpu cdev state to power consumed
 * @cdev:	&thermal_cooling_device pointer
 * @state:	cooling device state to be converted
 * @power:	pointer in which to store the resulting power
 *
 * Convert cooling device state @state into power consumption in
 * milliwatts assuming 100% load.  Store the calculated power in
 * @power.
 *
 * Return: 0 on success, -EINVAL if the cooling device state could not
 * be converted into a frequency or other -E* if there was an error
 * when calculating the static power.
 */
static int cpufreq_state2power(struct thermal_cooling_device *cdev,
			       unsigned long state, u32 *power)
{
	unsigned int freq, num_cpus, idx;
	struct cpufreq_cooling_device *cpufreq_cdev = cdev->devdata;

	/* Request state should be less than max_level */
	if (state > cpufreq_cdev->max_level)
		return -EINVAL;

	num_cpus = cpumask_weight(cpufreq_cdev->policy->cpus);

	idx = cpufreq_cdev->max_level - state;
	freq = cpufreq_cdev->em->table[idx].frequency;
	*power = cpu_freq_to_power(cpufreq_cdev, freq) * num_cpus;

	return 0;
}

/**
 * cpufreq_power2state() - convert power to a cooling device state
 * @cdev:	&thermal_cooling_device pointer
 * @power:	power in milliwatts to be converted
 * @state:	pointer in which to store the resulting state
 *
 * Calculate a cooling device state for the cpus described by @cdev
 * that would allow them to consume at most @power mW and store it in
 * @state.  Note that this calculation depends on external factors
 * such as the cpu load or the current static power.  Calling this
 * function with the same power as input can yield different cooling
 * device states depending on those external factors.
 *
 * Return: 0 on success, -ENODEV if no cpus are online or -EINVAL if
 * the calculated frequency could not be converted to a valid state.
 * The latter should not happen unless the frequencies available to
 * cpufreq have changed since the initialization of the cpu cooling
 * device.
 */
static int cpufreq_power2state(struct thermal_cooling_device *cdev,
			       u32 power, unsigned long *state)
{
	unsigned int target_freq;
	u32 last_load, normalised_power;
	struct cpufreq_cooling_device *cpufreq_cdev = cdev->devdata;
	struct cpufreq_policy *policy = cpufreq_cdev->policy;

	last_load = cpufreq_cdev->last_load ?: 1;
	normalised_power = (power * 100) / last_load;
	target_freq = cpu_power_to_freq(cpufreq_cdev, normalised_power);

	*state = get_level(cpufreq_cdev, target_freq);
	trace_thermal_power_cpu_limit(policy->related_cpus, target_freq, *state,
				      power);
	return 0;
}

static inline bool em_is_sane(struct cpufreq_cooling_device *cpufreq_cdev,
			      struct em_perf_domain *em) {
	struct cpufreq_policy *policy;
	unsigned int nr_levels;

	if (!em)
		return false;

	policy = cpufreq_cdev->policy;
	if (!cpumask_equal(policy->related_cpus, em_span_cpus(em))) {
		pr_err("The span of pd %*pbl is misaligned with cpufreq policy %*pbl\n",
			cpumask_pr_args(em_span_cpus(em)),
			cpumask_pr_args(policy->related_cpus));
		return false;
	}

	nr_levels = cpufreq_cdev->max_level + 1;
	if (em_pd_nr_perf_states(em) != nr_levels) {
		pr_err("The number of performance states in pd %*pbl (%u) doesn't match the number of cooling levels (%u)\n",
			cpumask_pr_args(em_span_cpus(em)),
			em_pd_nr_perf_states(em), nr_levels);
		return false;
	}

	return true;
}
#endif /* CONFIG_THERMAL_GOV_POWER_ALLOCATOR */

#ifdef CONFIG_SMP
static inline int allocate_idle_time(struct cpufreq_cooling_device *cpufreq_cdev)
{
	return 0;
}

static inline void free_idle_time(struct cpufreq_cooling_device *cpufreq_cdev)
{
}
#else
static int allocate_idle_time(struct cpufreq_cooling_device *cpufreq_cdev)
{
	unsigned int num_cpus = cpumask_weight(cpufreq_cdev->policy->related_cpus);

	cpufreq_cdev->idle_time = kcalloc(num_cpus,
					  sizeof(*cpufreq_cdev->idle_time),
					  GFP_KERNEL);
	if (!cpufreq_cdev->idle_time)
		return -ENOMEM;

	return 0;
}

static void free_idle_time(struct cpufreq_cooling_device *cpufreq_cdev)
{
	kfree(cpufreq_cdev->idle_time);
	cpufreq_cdev->idle_time = NULL;
}
#endif /* CONFIG_SMP */

static unsigned int get_state_freq(struct cpufreq_cooling_device *cpufreq_cdev,
				   unsigned long state)
{
	struct cpufreq_policy *policy;
	unsigned long idx;

#ifdef CONFIG_THERMAL_GOV_POWER_ALLOCATOR
	/* Use the Energy Model table if available */
	if (cpufreq_cdev->em) {
		idx = cpufreq_cdev->max_level - state;
		return cpufreq_cdev->em->table[idx].frequency;
	}
#endif

	/* Otherwise, fallback on the CPUFreq table */
	policy = cpufreq_cdev->policy;
	if (policy->freq_table_sorted == CPUFREQ_TABLE_SORTED_ASCENDING)
		idx = cpufreq_cdev->max_level - state;
	else
		idx = state;

	return policy->freq_table[idx].frequency;
}

/* cpufreq cooling device callback functions are defined below */

/**
 * cpufreq_get_max_state - callback function to get the max cooling state.
 * @cdev: thermal cooling device pointer.
 * @state: fill this variable with the max cooling state.
 *
 * Callback for the thermal cooling device to return the cpufreq
 * max cooling state.
 *
 * Return: 0 on success, an error code otherwise.
 */
static int cpufreq_get_max_state(struct thermal_cooling_device *cdev,
				 unsigned long *state)
{
	struct cpufreq_cooling_device *cpufreq_cdev = cdev->devdata;

	*state = cpufreq_cdev->max_level;
	return 0;
}

/**
 * cpufreq_get_cur_state - callback function to get the current cooling state.
 * @cdev: thermal cooling device pointer.
 * @state: fill this variable with the current cooling state.
 *
 * Callback for the thermal cooling device to return the cpufreq
 * current cooling state.
 *
 * Return: 0 on success, an error code otherwise.
 */
static int cpufreq_get_cur_state(struct thermal_cooling_device *cdev,
				 unsigned long *state)
{
	struct cpufreq_cooling_device *cpufreq_cdev = cdev->devdata;

	*state = cpufreq_cdev->cpufreq_state;

	return 0;
}

/**
 * cpufreq_set_cur_state - callback function to set the current cooling state.
 * @cdev: thermal cooling device pointer.
 * @state: set this variable to the current cooling state.
 *
 * Callback for the thermal cooling device to change the cpufreq
 * current cooling state.
 *
 * Return: 0 on success, an error code otherwise.
 */
static int cpufreq_set_cur_state(struct thermal_cooling_device *cdev,
				 unsigned long state)
{
	struct cpufreq_cooling_device *cpufreq_cdev = cdev->devdata;
	struct cpumask *cpus;
	unsigned int frequency;
	unsigned long max_capacity, capacity;
	int ret;

	/* Request state should be less than max_level */
	if (state > cpufreq_cdev->max_level)
		return -EINVAL;

	/* Check if the old cooling action is same as new cooling action */
	if (cpufreq_cdev->cpufreq_state == state)
		return 0;

	frequency = get_state_freq(cpufreq_cdev, state);

	ret = freq_qos_update_request(&cpufreq_cdev->qos_req, frequency);
	if (ret >= 0) {
		cpufreq_cdev->cpufreq_state = state;
		cpus = cpufreq_cdev->policy->cpus;
		max_capacity = arch_scale_cpu_capacity(cpumask_first(cpus));
		capacity = frequency * max_capacity;
		capacity /= cpufreq_cdev->policy->cpuinfo.max_freq;
		arch_set_thermal_pressure(cpus, max_capacity - capacity);
		ret = 0;
	}

	return ret;
}

/* Bind cpufreq callbacks to thermal cooling device ops */

static struct thermal_cooling_device_ops cpufreq_cooling_ops = {
	.get_max_state		= cpufreq_get_max_state,
	.get_cur_state		= cpufreq_get_cur_state,
	.set_cur_state		= cpufreq_set_cur_state,
};

/**
 * __cpufreq_cooling_register - helper function to create cpufreq cooling device
 * @np: a valid struct device_node to the cooling device device tree node
 * @policy: cpufreq policy
 * Normally this should be same as cpufreq policy->related_cpus.
 * @em: Energy Model of the cpufreq policy
 *
 * This interface function registers the cpufreq cooling device with the name
 * "thermal-cpufreq-%x". This api can support multiple instances of cpufreq
 * cooling devices. It also gives the opportunity to link the cooling device
 * with a device tree node, in order to bind it via the thermal DT code.
 *
 * Return: a valid struct thermal_cooling_device pointer on success,
 * on failure, it returns a corresponding ERR_PTR().
 */
static struct thermal_cooling_device *
__cpufreq_cooling_register(struct device_node *np,
			struct cpufreq_policy *policy,
			struct em_perf_domain *em)
{
	struct thermal_cooling_device *cdev;
	struct cpufreq_cooling_device *cpufreq_cdev;
	unsigned int i;
	struct device *dev;
	int ret;
	struct thermal_cooling_device_ops *cooling_ops;
	char *name;

	dev = get_cpu_device(policy->cpu);
	if (unlikely(!dev)) {
		pr_warn("No cpu device for cpu %d\n", policy->cpu);
		return ERR_PTR(-ENODEV);
	}

	if (IS_ERR_OR_NULL(policy)) {
		pr_err("%s: cpufreq policy isn't valid: %p\n", __func__, policy);
		return ERR_PTR(-EINVAL);
	}

	i = cpufreq_table_count_valid_entries(policy);
	if (!i) {
		pr_debug("%s: CPUFreq table not found or has no valid entries\n",
			 __func__);
		return ERR_PTR(-ENODEV);
	}

	cpufreq_cdev = kzalloc(sizeof(*cpufreq_cdev), GFP_KERNEL);
	if (!cpufreq_cdev)
		return ERR_PTR(-ENOMEM);

	cpufreq_cdev->policy = policy;

	ret = allocate_idle_time(cpufreq_cdev);
	if (ret) {
		cdev = ERR_PTR(ret);
		goto free_cdev;
	}

	/* max_level is an index, not a counter */
	cpufreq_cdev->max_level = i - 1;

	cooling_ops = &cpufreq_cooling_ops;

#ifdef CONFIG_THERMAL_GOV_POWER_ALLOCATOR
	if (em_is_sane(cpufreq_cdev, em)) {
		cpufreq_cdev->em = em;
		cooling_ops->get_requested_power = cpufreq_get_requested_power;
		cooling_ops->state2power = cpufreq_state2power;
		cooling_ops->power2state = cpufreq_power2state;
	} else
#endif
	if (policy->freq_table_sorted == CPUFREQ_TABLE_UNSORTED) {
		pr_err("%s: unsorted frequency tables are not supported\n",
		       __func__);
		cdev = ERR_PTR(-EINVAL);
		goto free_idle_time;
	}

	ret = freq_qos_add_request(&policy->constraints,
				   &cpufreq_cdev->qos_req, FREQ_QOS_MAX,
				   get_state_freq(cpufreq_cdev, 0));
	if (ret < 0) {
		pr_err("%s: Failed to add freq constraint (%d)\n", __func__,
		       ret);
		cdev = ERR_PTR(ret);
		goto free_idle_time;
	}

	cdev = ERR_PTR(-ENOMEM);
	name = kasprintf(GFP_KERNEL, "cpufreq-%s", dev_name(dev));
	if (!name)
		goto remove_qos_req;

	cdev = thermal_of_cooling_device_register(np, name, cpufreq_cdev,
						  cooling_ops);
	kfree(name);

	if (IS_ERR(cdev))
		goto remove_qos_req;

	mutex_lock(&cooling_list_lock);
	list_add(&cpufreq_cdev->node, &cpufreq_cdev_list);
	mutex_unlock(&cooling_list_lock);

	return cdev;

remove_qos_req:
	freq_qos_remove_request(&cpufreq_cdev->qos_req);
free_idle_time:
	free_idle_time(cpufreq_cdev);
free_cdev:
	kfree(cpufreq_cdev);
	return cdev;
}

/**
 * cpufreq_cooling_register - function to create cpufreq cooling device.
 * @policy: cpufreq policy
 *
 * This interface function registers the cpufreq cooling device with the name
 * "thermal-cpufreq-%x". This api can support multiple instances of cpufreq
 * cooling devices.
 *
 * Return: a valid struct thermal_cooling_device pointer on success,
 * on failure, it returns a corresponding ERR_PTR().
 */
struct thermal_cooling_device *
cpufreq_cooling_register(struct cpufreq_policy *policy)
{
	return __cpufreq_cooling_register(NULL, policy, NULL);
}
EXPORT_SYMBOL_GPL(cpufreq_cooling_register);

/**
 * of_cpufreq_cooling_register - function to create cpufreq cooling device.
 * @policy: cpufreq policy
 *
 * This interface function registers the cpufreq cooling device with the name
 * "thermal-cpufreq-%x". This api can support multiple instances of cpufreq
 * cooling devices. Using this API, the cpufreq cooling device will be
 * linked to the device tree node provided.
 *
 * Using this function, the cooling device will implement the power
 * extensions by using a simple cpu power model.  The cpus must have
 * registered their OPPs using the OPP library.
 *
 * It also takes into account, if property present in policy CPU node, the
 * static power consumed by the cpu.
 *
 * Return: a valid struct thermal_cooling_device pointer on success,
 * and NULL on failure.
 */
struct thermal_cooling_device *
of_cpufreq_cooling_register(struct cpufreq_policy *policy)
{
	struct device_node *np = of_get_cpu_node(policy->cpu, NULL);
	struct thermal_cooling_device *cdev = NULL;

	if (!np) {
		pr_err("cpufreq_cooling: OF node not available for cpu%d\n",
		       policy->cpu);
		return NULL;
	}

	if (of_find_property(np, "#cooling-cells", NULL)) {
		struct em_perf_domain *em = em_cpu_get(policy->cpu);

		cdev = __cpufreq_cooling_register(np, policy, em);
		if (IS_ERR(cdev)) {
			pr_err("cpufreq_cooling: cpu%d failed to register as cooling device: %ld\n",
			       policy->cpu, PTR_ERR(cdev));
			cdev = NULL;
		}
	}

	of_node_put(np);
	return cdev;
}
EXPORT_SYMBOL_GPL(of_cpufreq_cooling_register);

/**
 * cpufreq_cooling_unregister - function to remove cpufreq cooling device.
 * @cdev: thermal cooling device pointer.
 *
 * This interface function unregisters the "thermal-cpufreq-%x" cooling device.
 */
void cpufreq_cooling_unregister(struct thermal_cooling_device *cdev)
{
	struct cpufreq_cooling_device *cpufreq_cdev;

	if (!cdev)
		return;

	cpufreq_cdev = cdev->devdata;

	mutex_lock(&cooling_list_lock);
	list_del(&cpufreq_cdev->node);
	mutex_unlock(&cooling_list_lock);

	thermal_cooling_device_unregister(cdev);
	freq_qos_remove_request(&cpufreq_cdev->qos_req);
	free_idle_time(cpufreq_cdev);
	kfree(cpufreq_cdev);
}
EXPORT_SYMBOL_GPL(cpufreq_cooling_unregister);