aboutsummaryrefslogtreecommitdiff
path: root/drivers/thermal/clock_cooling.c
blob: 1b4ff0f4c7168f578253d248507cb57fc02245c2 (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
/*
 *  drivers/thermal/clock_cooling.c
 *
 *  Copyright (C) 2014 Eduardo Valentin <edubezval@gmail.com>
 *
 *  Copyright (C) 2013	Texas Instruments Inc.
 *  Contact:  Eduardo Valentin <eduardo.valentin@ti.com>
 *
 *  Highly based on 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.
 */
#include <linux/clk.h>
#include <linux/cpufreq.h>
#include <linux/device.h>
#include <linux/err.h>
#include <linux/idr.h>
#include <linux/mutex.h>
#include <linux/pm_opp.h>
#include <linux/slab.h>
#include <linux/thermal.h>
#include <linux/clock_cooling.h>

/**
 * struct clock_cooling_device - data for cooling device with clock
 * @id: unique integer value corresponding to each clock_cooling_device
 *	registered.
 * @dev: struct device pointer to the device being used to cool off using
 *       clock frequencies.
 * @cdev: thermal_cooling_device pointer to keep track of the
 *	registered cooling device.
 * @clk_rate_change_nb: reference to notifier block used to receive clock
 *                      rate changes.
 * @freq_table: frequency table used to keep track of available frequencies.
 * @clock_state: integer value representing the current state of clock
 *	cooling	devices.
 * @clock_val: integer value representing the absolute value of the clipped
 *	frequency.
 * @clk: struct clk reference used to enforce clock limits.
 * @lock: mutex lock to protect this struct.
 *
 * This structure is required for keeping information of each
 * clock_cooling_device registered. In order to prevent corruption of this a
 * mutex @lock is used.
 */
struct clock_cooling_device {
	int id;
	struct device *dev;
	struct thermal_cooling_device *cdev;
	struct notifier_block clk_rate_change_nb;
	struct cpufreq_frequency_table *freq_table;
	unsigned long clock_state;
	unsigned long clock_val;
	struct clk *clk;
	struct mutex lock; /* lock to protect the content of this struct */
};
#define to_clock_cooling_device(x) \
		container_of(x, struct clock_cooling_device, clk_rate_change_nb)
static DEFINE_IDR(clock_idr);
static DEFINE_MUTEX(cooling_clock_lock);

/**
 * clock_cooling_get_idr - function to get an unique 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 clock_cooling_get_idr(int *id)
{
	int ret;

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

	return 0;
}

/**
 * release_idr - function to free the unique id.
 * @id: int value representing the unique id.
 */
static void release_idr(int id)
{
	mutex_lock(&cooling_clock_lock);
	idr_remove(&clock_idr, id);
	mutex_unlock(&cooling_clock_lock);
}

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

enum clock_cooling_property {
	GET_LEVEL,
	GET_FREQ,
	GET_MAXL,
};

/**
 * clock_cooling_get_property - fetch a property of interest for a give cpu.
 * @ccdev: clock cooling device reference
 * @input: query parameter
 * @output: query return
 * @property: type of query (frequency, level, max level)
 *
 * This is the common function to
 * 1. get maximum clock cooling states
 * 2. translate frequency to cooling state
 * 3. translate cooling state to frequency
 * Note that the code may be not in good shape
 * but it is written in this way in order to:
 * a) reduce duplicate code as most of the code can be shared.
 * b) make sure the logic is consistent when translating between
 *    cooling states and frequencies.
 *
 * Return: 0 on success, -EINVAL when invalid parameters are passed.
 */
static int clock_cooling_get_property(struct clock_cooling_device *ccdev,
				      unsigned long input,
				      unsigned long *output,
				      enum clock_cooling_property property)
{
	int i;
	unsigned long max_level = 0, level = 0;
	unsigned int freq = CPUFREQ_ENTRY_INVALID;
	int descend = -1;
	struct cpufreq_frequency_table *pos, *table = ccdev->freq_table;

	if (!output)
		return -EINVAL;

	if (!table)
		return -EINVAL;

	cpufreq_for_each_valid_entry(pos, table) {
		/* ignore duplicate entry */
		if (freq == pos->frequency)
			continue;

		/* get the frequency order */
		if (freq != CPUFREQ_ENTRY_INVALID && descend == -1)
			descend = freq > pos->frequency;

		freq = pos->frequency;
		max_level++;
	}

	/* No valid cpu frequency entry */
	if (max_level == 0)
		return -EINVAL;

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

	/* get max level */
	if (property == GET_MAXL) {
		*output = max_level;
		return 0;
	}

	if (property == GET_FREQ)
		level = descend ? input : (max_level - input);

	i = 0;
	cpufreq_for_each_valid_entry(pos, table) {
		/* ignore duplicate entry */
		if (freq == pos->frequency)
			continue;

		/* now we have a valid frequency entry */
		freq = pos->frequency;

		if (property == GET_LEVEL && (unsigned int)input == freq) {
			/* get level by frequency */
			*output = descend ? i : (max_level - i);
			return 0;
		}
		if (property == GET_FREQ && level == i) {
			/* get frequency by level */
			*output = freq;
			return 0;
		}
		i++;
	}

	return -EINVAL;
}

/**
 * clock_cooling_get_level - return the cooling level of given clock cooling.
 * @cdev: reference of a thermal cooling device of used as clock cooling device
 * @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 clock_cooling_get_level(struct thermal_cooling_device *cdev,
				      unsigned long freq)
{
	struct clock_cooling_device *ccdev = cdev->devdata;
	unsigned long val;

	if (clock_cooling_get_property(ccdev, (unsigned long)freq, &val,
				       GET_LEVEL))
		return THERMAL_CSTATE_INVALID;

	return val;
}
EXPORT_SYMBOL_GPL(clock_cooling_get_level);

/**
 * clock_cooling_get_frequency - get the absolute value of frequency from level.
 * @ccdev: clock cooling device reference
 * @level: cooling level
 *
 * This function matches cooling level with frequency. Based on a cooling level
 * of frequency, equals cooling state of cpu cooling device, it will return
 * the corresponding frequency.
 *	e.g level=0 --> 1st MAX FREQ, level=1 ---> 2nd MAX FREQ, .... etc
 *
 * Return: 0 on error, the corresponding frequency otherwise.
 */
static unsigned long
clock_cooling_get_frequency(struct clock_cooling_device *ccdev,
			    unsigned long level)
{
	int ret = 0;
	unsigned long freq;

	ret = clock_cooling_get_property(ccdev, level, &freq, GET_FREQ);
	if (ret)
		return 0;

	return freq;
}

/**
 * clock_cooling_apply - function to apply frequency clipping.
 * @ccdev: clock_cooling_device pointer containing frequency clipping data.
 * @cooling_state: value of the cooling state.
 *
 * Function used to make sure the clock layer is aware of current thermal
 * limits. The limits are applied by updating the clock rate in case it is
 * higher than the corresponding frequency based on the requested cooling_state.
 *
 * Return: 0 on success, an error code otherwise (-EINVAL in case wrong
 * cooling state).
 */
static int clock_cooling_apply(struct clock_cooling_device *ccdev,
			       unsigned long cooling_state)
{
	unsigned long clip_freq, cur_freq;
	int ret = 0;

	/* Here we write the clipping */
	/* Check if the old cooling action is same as new cooling action */
	if (ccdev->clock_state == cooling_state)
		return 0;

	clip_freq = clock_cooling_get_frequency(ccdev, cooling_state);
	if (!clip_freq)
		return -EINVAL;

	cur_freq = clk_get_rate(ccdev->clk);

	mutex_lock(&ccdev->lock);
	ccdev->clock_state = cooling_state;
	ccdev->clock_val = clip_freq;
	/* enforce clock level */
	if (cur_freq > clip_freq)
		ret = clk_set_rate(ccdev->clk, clip_freq);
	mutex_unlock(&ccdev->lock);

	return ret;
}

/**
 * clock_cooling_clock_notifier - notifier callback on clock rate changes.
 * @nb:	struct notifier_block * with callback info.
 * @event: value showing clock event for which this function invoked.
 * @data: callback-specific data
 *
 * Callback to hijack the notification on clock transition.
 * Every time there is a clock change, we intercept all pre change events
 * and block the transition in case the new rate infringes thermal limits.
 *
 * Return: NOTIFY_DONE (success) or NOTIFY_BAD (new_rate > thermal limit).
 */
static int clock_cooling_clock_notifier(struct notifier_block *nb,
					unsigned long event, void *data)
{
	struct clk_notifier_data *ndata = data;
	struct clock_cooling_device *ccdev = to_clock_cooling_device(nb);

	switch (event) {
	case PRE_RATE_CHANGE:
		/*
		 * checks on current state
		 * TODO: current method is not best we can find as it
		 * allows possibly voltage transitions, in case DVFS
		 * layer is also hijacking clock pre notifications.
		 */
		if (ndata->new_rate > ccdev->clock_val)
			return NOTIFY_BAD;
		/* fall through */
	case POST_RATE_CHANGE:
	case ABORT_RATE_CHANGE:
	default:
		return NOTIFY_DONE;
	}
}

/* clock cooling device thermal callback functions are defined below */

/**
 * clock_cooling_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 clock
 * max cooling state.
 *
 * Return: 0 on success, an error code otherwise.
 */
static int clock_cooling_get_max_state(struct thermal_cooling_device *cdev,
				       unsigned long *state)
{
	struct clock_cooling_device *ccdev = cdev->devdata;
	unsigned long count = 0;
	int ret;

	ret = clock_cooling_get_property(ccdev, 0, &count, GET_MAXL);
	if (!ret)
		*state = count;

	return ret;
}

/**
 * clock_cooling_get_cur_state - 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 clock
 * current cooling state.
 *
 * Return: 0 (success)
 */
static int clock_cooling_get_cur_state(struct thermal_cooling_device *cdev,
				       unsigned long *state)
{
	struct clock_cooling_device *ccdev = cdev->devdata;

	*state = ccdev->clock_state;

	return 0;
}

/**
 * clock_cooling_set_cur_state - 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 clock cooling
 * current cooling state.
 *
 * Return: 0 on success, an error code otherwise.
 */
static int clock_cooling_set_cur_state(struct thermal_cooling_device *cdev,
				       unsigned long state)
{
	struct clock_cooling_device *clock_device = cdev->devdata;

	return clock_cooling_apply(clock_device, state);
}

/* Bind clock callbacks to thermal cooling device ops */
static struct thermal_cooling_device_ops const clock_cooling_ops = {
	.get_max_state = clock_cooling_get_max_state,
	.get_cur_state = clock_cooling_get_cur_state,
	.set_cur_state = clock_cooling_set_cur_state,
};

/**
 * clock_cooling_register - function to create clock cooling device.
 * @dev: struct device pointer to the device used as clock cooling device.
 * @clock_name: string containing the clock used as cooling mechanism.
 *
 * This interface function registers the clock cooling device with the name
 * "thermal-clock-%x". The cooling device is based on clock frequencies.
 * The struct device is assumed to be capable of DVFS transitions.
 * The OPP layer is used to fetch and fill the available frequencies for
 * the referred device. The ordered frequency table is used to control
 * the clock cooling device cooling states and to limit clock transitions
 * based on the cooling state requested by the thermal framework.
 *
 * Return: a valid struct thermal_cooling_device pointer on success,
 * on failure, it returns a corresponding ERR_PTR().
 */
struct thermal_cooling_device *
clock_cooling_register(struct device *dev, const char *clock_name)
{
	struct thermal_cooling_device *cdev;
	struct clock_cooling_device *ccdev = NULL;
	char dev_name[THERMAL_NAME_LENGTH];
	int ret = 0;

	ccdev = devm_kzalloc(dev, sizeof(*ccdev), GFP_KERNEL);
	if (!ccdev)
		return ERR_PTR(-ENOMEM);

	ccdev->dev = dev;
	ccdev->clk = devm_clk_get(dev, clock_name);
	if (IS_ERR(ccdev->clk))
		return ERR_CAST(ccdev->clk);

	ret = clock_cooling_get_idr(&ccdev->id);
	if (ret)
		return ERR_PTR(-EINVAL);

	snprintf(dev_name, sizeof(dev_name), "thermal-clock-%d", ccdev->id);

	cdev = thermal_cooling_device_register(dev_name, ccdev,
					       &clock_cooling_ops);
	if (IS_ERR(cdev)) {
		release_idr(ccdev->id);
		return ERR_PTR(-EINVAL);
	}
	ccdev->cdev = cdev;
	ccdev->clk_rate_change_nb.notifier_call = clock_cooling_clock_notifier;

	/* Assuming someone has already filled the opp table for this device */
	ret = dev_pm_opp_init_cpufreq_table(dev, &ccdev->freq_table);
	if (ret) {
		release_idr(ccdev->id);
		return ERR_PTR(ret);
	}
	ccdev->clock_state = 0;
	ccdev->clock_val = clock_cooling_get_frequency(ccdev, 0);

	clk_notifier_register(ccdev->clk, &ccdev->clk_rate_change_nb);

	return cdev;
}
EXPORT_SYMBOL_GPL(clock_cooling_register);

/**
 * clock_cooling_unregister - function to remove clock cooling device.
 * @cdev: thermal cooling device pointer.
 *
 * This interface function unregisters the "thermal-clock-%x" cooling device.
 */
void clock_cooling_unregister(struct thermal_cooling_device *cdev)
{
	struct clock_cooling_device *ccdev;

	if (!cdev)
		return;

	ccdev = cdev->devdata;

	clk_notifier_unregister(ccdev->clk, &ccdev->clk_rate_change_nb);
	dev_pm_opp_free_cpufreq_table(ccdev->dev, &ccdev->freq_table);

	thermal_cooling_device_unregister(ccdev->cdev);
	release_idr(ccdev->id);
}
EXPORT_SYMBOL_GPL(clock_cooling_unregister);