summaryrefslogtreecommitdiff
path: root/drivers/thermal/cpu_cooling.c
blob: cd6f64291076c941221015340fbdfc233ec82a19 (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
/*
 *  linux/drivers/thermal/cpu_cooling.c
 *
 *  Copyright (C) 2012	Samsung Electronics Co., Ltd(http://www.samsung.com)
 *  Copyright (C) 2012  Amit Daniel <amit.kachhap@linaro.org>
 *
 * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 *  This program is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation; version 2 of the License.
 *
 *  This program is distributed in the hope that it will be useful, but
 *  WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 *  General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License along
 *  with this program; if not, write to the Free Software Foundation, Inc.,
 *  59 Temple Place, Suite 330, Boston, MA 02111-1307 USA.
 *
 * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 */
#include <linux/module.h>
#include <linux/thermal.h>
#include <linux/cpufreq.h>
#include <linux/err.h>
#include <linux/slab.h>
#include <linux/cpu.h>
#include <linux/cpu_cooling.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 cpufreq_cooling_device - data for cooling device with cpufreq
 * @id: unique integer value corresponding to each cpufreq_cooling_device
 *	registered.
 * @cool_dev: thermal_cooling_device pointer to keep track of the
 *	registered cooling device.
 * @cpufreq_state: integer value representing the current state of cpufreq
 *	cooling	devices.
 * @cpufreq_val: integer value representing the absolute value of the clipped
 *	frequency.
 * @max_level: maximum cooling level. One less than total number of valid
 *	cpufreq frequencies.
 * @allowed_cpus: all the cpus involved for this cpufreq_cooling_device.
 *
 * This structure is required for keeping information of each registered
 * cpufreq_cooling_device.
 */
struct cpufreq_cooling_device {
	int id;
	struct thermal_cooling_device *cool_dev;
	unsigned int cpufreq_state;
	unsigned int cpufreq_val;
	unsigned int max_level;
	unsigned int *freq_table;	/* In descending order */
	struct cpumask allowed_cpus;
	struct list_head node;
};
static DEFINE_IDR(cpufreq_idr);
static DEFINE_MUTEX(cooling_cpufreq_lock);

static LIST_HEAD(cpufreq_dev_list);

/**
 * get_idr - function to get a unique id.
 * @idr: struct idr * handle used to create a id.
 * @id: int * value generated by this function.
 *
 * This function will populate @id with an unique
 * id, using the idr API.
 *
 * Return: 0 on success, an error code on failure.
 */
static int get_idr(struct idr *idr, int *id)
{
	int ret;

	mutex_lock(&cooling_cpufreq_lock);
	ret = idr_alloc(idr, NULL, 0, 0, GFP_KERNEL);
	mutex_unlock(&cooling_cpufreq_lock);
	if (unlikely(ret < 0))
		return ret;
	*id = ret;

	return 0;
}

/**
 * release_idr - function to free the unique id.
 * @idr: struct idr * handle used for creating the id.
 * @id: int value representing the unique id.
 */
static void release_idr(struct idr *idr, int id)
{
	mutex_lock(&cooling_cpufreq_lock);
	idr_remove(idr, id);
	mutex_unlock(&cooling_cpufreq_lock);
}

/* Below code defines functions to be used for cpufreq as cooling device */

/**
 * get_level: Find the level for a particular frequency
 * @cpufreq_dev: cpufreq_dev for which the property is required
 * @freq: Frequency
 *
 * Return: level on success, THERMAL_CSTATE_INVALID on error.
 */
static unsigned long get_level(struct cpufreq_cooling_device *cpufreq_dev,
			       unsigned int freq)
{
	unsigned long level;

	for (level = 0; level <= cpufreq_dev->max_level; level++) {
		if (freq == cpufreq_dev->freq_table[level])
			return level;

		if (freq > cpufreq_dev->freq_table[level])
			break;
	}

	return THERMAL_CSTATE_INVALID;
}

/**
 * cpufreq_cooling_get_level - for a given cpu, return the cooling level.
 * @cpu: cpu for which the level is required
 * @freq: the frequency of interest
 *
 * This function will match the cooling level corresponding to the
 * requested @freq and return it.
 *
 * Return: The matched cooling level on success or THERMAL_CSTATE_INVALID
 * otherwise.
 */
unsigned long cpufreq_cooling_get_level(unsigned int cpu, unsigned int freq)
{
	struct cpufreq_cooling_device *cpufreq_dev;

	mutex_lock(&cooling_cpufreq_lock);
	list_for_each_entry(cpufreq_dev, &cpufreq_dev_list, node) {
		if (cpumask_test_cpu(cpu, &cpufreq_dev->allowed_cpus)) {
			mutex_unlock(&cooling_cpufreq_lock);
			return get_level(cpufreq_dev, freq);
		}
	}
	mutex_unlock(&cooling_cpufreq_lock);

	pr_err("%s: cpu:%d not part of any cooling device\n", __func__, cpu);
	return THERMAL_CSTATE_INVALID;
}
EXPORT_SYMBOL_GPL(cpufreq_cooling_get_level);

/**
 * cpufreq_thermal_notifier - notifier callback for cpufreq policy change.
 * @nb:	struct notifier_block * with callback info.
 * @event: value showing cpufreq event for which this function invoked.
 * @data: callback-specific data
 *
 * Callback to hijack the notification on cpufreq policy transition.
 * Every time there is a change in policy, we will intercept and
 * update the cpufreq policy with thermal constraints.
 *
 * Return: 0 (success)
 */
static int cpufreq_thermal_notifier(struct notifier_block *nb,
				    unsigned long event, void *data)
{
	struct cpufreq_policy *policy = data;
	unsigned long max_freq = 0;
	struct cpufreq_cooling_device *cpufreq_dev;

	if (event != CPUFREQ_ADJUST)
		return 0;

	mutex_lock(&cooling_cpufreq_lock);
	list_for_each_entry(cpufreq_dev, &cpufreq_dev_list, node) {
		if (!cpumask_test_cpu(policy->cpu,
					&cpufreq_dev->allowed_cpus))
			continue;

		max_freq = cpufreq_dev->cpufreq_val;

		if (policy->max != max_freq)
			cpufreq_verify_within_limits(policy, 0, max_freq);
	}
	mutex_unlock(&cooling_cpufreq_lock);

	return 0;
}

/* 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_device = cdev->devdata;

	*state = cpufreq_device->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_device = cdev->devdata;

	*state = cpufreq_device->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_device = cdev->devdata;
	unsigned int cpu = cpumask_any(&cpufreq_device->allowed_cpus);
	unsigned int clip_freq;

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

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

	clip_freq = cpufreq_device->freq_table[state];
	cpufreq_device->cpufreq_state = state;
	cpufreq_device->cpufreq_val = clip_freq;

	cpufreq_update_policy(cpu);

	return 0;
}

/* Bind cpufreq callbacks to thermal cooling device ops */
static struct thermal_cooling_device_ops const cpufreq_cooling_ops = {
	.get_max_state = cpufreq_get_max_state,
	.get_cur_state = cpufreq_get_cur_state,
	.set_cur_state = cpufreq_set_cur_state,
};

/* Notifier for cpufreq policy change */
static struct notifier_block thermal_cpufreq_notifier_block = {
	.notifier_call = cpufreq_thermal_notifier,
};

static unsigned int find_next_max(struct cpufreq_frequency_table *table,
				  unsigned int prev_max)
{
	struct cpufreq_frequency_table *pos;
	unsigned int max = 0;

	cpufreq_for_each_valid_entry(pos, table) {
		if (pos->frequency > max && pos->frequency < prev_max)
			max = pos->frequency;
	}

	return max;
}

/**
 * __cpufreq_cooling_register - helper function to create cpufreq cooling device
 * @np: a valid struct device_node to the cooling device device tree node
 * @clip_cpus: cpumask of cpus where the frequency constraints will happen.
 * Normally this should be same as cpufreq policy->related_cpus.
 *
 * 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,
			   const struct cpumask *clip_cpus)
{
	struct thermal_cooling_device *cool_dev;
	struct cpufreq_cooling_device *cpufreq_dev;
	char dev_name[THERMAL_NAME_LENGTH];
	struct cpufreq_frequency_table *pos, *table;
	unsigned int freq, i;
	int ret;

	table = cpufreq_frequency_get_table(cpumask_first(clip_cpus));
	if (!table) {
		pr_debug("%s: CPUFreq table not found\n", __func__);
		return ERR_PTR(-EPROBE_DEFER);
	}

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

	/* Find max levels */
	cpufreq_for_each_valid_entry(pos, table)
		cpufreq_dev->max_level++;

	cpufreq_dev->freq_table = kmalloc(sizeof(*cpufreq_dev->freq_table) *
					  cpufreq_dev->max_level, GFP_KERNEL);
	if (!cpufreq_dev->freq_table) {
		return ERR_PTR(-ENOMEM);
		cool_dev = ERR_PTR(-ENOMEM);
		goto free_cdev;
	}

	/* max_level is an index, not a counter */
	cpufreq_dev->max_level--;

	cpumask_copy(&cpufreq_dev->allowed_cpus, clip_cpus);

	ret = get_idr(&cpufreq_idr, &cpufreq_dev->id);
	if (ret) {
		cool_dev = ERR_PTR(ret);
		goto free_table;
	}

	snprintf(dev_name, sizeof(dev_name), "thermal-cpufreq-%d",
		 cpufreq_dev->id);

	cool_dev = thermal_of_cooling_device_register(np, dev_name, cpufreq_dev,
						      &cpufreq_cooling_ops);
	if (IS_ERR(cool_dev))
		goto remove_idr;

	/* Fill freq-table in descending order of frequencies */
	for (i = 0, freq = -1; i <= cpufreq_dev->max_level; i++) {
		freq = find_next_max(table, freq);
		cpufreq_dev->freq_table[i] = freq;

		/* Warn for duplicate entries */
		if (!freq)
			pr_warn("%s: table has duplicate entries\n", __func__);
		else
			pr_debug("%s: freq:%u KHz\n", __func__, freq);
	}

	cpufreq_dev->cpufreq_val = cpufreq_dev->freq_table[0];
	cpufreq_dev->cool_dev = cool_dev;

	mutex_lock(&cooling_cpufreq_lock);

	/* Register the notifier for first cpufreq cooling device */
	if (list_empty(&cpufreq_dev_list))
		cpufreq_register_notifier(&thermal_cpufreq_notifier_block,
					  CPUFREQ_POLICY_NOTIFIER);
	list_add(&cpufreq_dev->node, &cpufreq_dev_list);

	mutex_unlock(&cooling_cpufreq_lock);

	return cool_dev;

remove_idr:
	release_idr(&cpufreq_idr, cpufreq_dev->id);
free_table:
	kfree(cpufreq_dev->freq_table);
free_cdev:
	kfree(cpufreq_dev);

	return cool_dev;
}

/**
 * cpufreq_cooling_register - function to create cpufreq cooling device.
 * @clip_cpus: cpumask of cpus where the frequency constraints will happen.
 *
 * 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(const struct cpumask *clip_cpus)
{
	return __cpufreq_cooling_register(NULL, clip_cpus);
}
EXPORT_SYMBOL_GPL(cpufreq_cooling_register);

/**
 * of_cpufreq_cooling_register - function to create cpufreq cooling device.
 * @np: a valid struct device_node to the cooling device device tree node
 * @clip_cpus: cpumask of cpus where the frequency constraints will happen.
 *
 * 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.
 *
 * Return: a valid struct thermal_cooling_device pointer on success,
 * on failure, it returns a corresponding ERR_PTR().
 */
struct thermal_cooling_device *
of_cpufreq_cooling_register(struct device_node *np,
			    const struct cpumask *clip_cpus)
{
	if (!np)
		return ERR_PTR(-EINVAL);

	return __cpufreq_cooling_register(np, clip_cpus);
}
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_dev;

	if (!cdev)
		return;

	cpufreq_dev = cdev->devdata;
	mutex_lock(&cooling_cpufreq_lock);
	list_del(&cpufreq_dev->node);

	/* Unregister the notifier for the last cpufreq cooling device */
	if (list_empty(&cpufreq_dev_list))
		cpufreq_unregister_notifier(&thermal_cpufreq_notifier_block,
					    CPUFREQ_POLICY_NOTIFIER);
	mutex_unlock(&cooling_cpufreq_lock);

	thermal_cooling_device_unregister(cpufreq_dev->cool_dev);
	release_idr(&cpufreq_idr, cpufreq_dev->id);
	kfree(cpufreq_dev->freq_table);
	kfree(cpufreq_dev);
}
EXPORT_SYMBOL_GPL(cpufreq_cooling_unregister);