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1/*
2 * linux/drivers/thermal/cpu_cooling.c
3 *
4 * Copyright (C) 2012 Samsung Electronics Co., Ltd(http://www.samsung.com)
5 * Copyright (C) 2012 Amit Daniel <amit.kachhap@linaro.org>
6 *
7 * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
8 * This program is free software; you can redistribute it and/or modify
9 * it under the terms of the GNU General Public License as published by
10 * the Free Software Foundation; version 2 of the License.
11 *
12 * This program is distributed in the hope that it will be useful, but
13 * WITHOUT ANY WARRANTY; without even the implied warranty of
14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
15 * General Public License for more details.
16 *
17 * You should have received a copy of the GNU General Public License along
18 * with this program; if not, write to the Free Software Foundation, Inc.,
19 * 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA.
20 *
21 * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
22 */
23#include <linux/module.h>
24#include <linux/thermal.h>
25#include <linux/cpufreq.h>
26#include <linux/err.h>
27#include <linux/slab.h>
28#include <linux/cpu.h>
29#include <linux/cpu_cooling.h>
30
31/**
32 * struct cpufreq_cooling_device - data for cooling device with cpufreq
33 * @id: unique integer value corresponding to each cpufreq_cooling_device
34 * registered.
35 * @cool_dev: thermal_cooling_device pointer to keep track of the
36 * registered cooling device.
37 * @cpufreq_state: integer value representing the current state of cpufreq
38 * cooling devices.
39 * @cpufreq_val: integer value representing the absolute value of the clipped
40 * frequency.
41 * @allowed_cpus: all the cpus involved for this cpufreq_cooling_device.
42 *
43 * This structure is required for keeping information of each
44 * cpufreq_cooling_device registered. In order to prevent corruption of this a
45 * mutex lock cooling_cpufreq_lock is used.
46 */
47struct cpufreq_cooling_device {
48 int id;
49 struct thermal_cooling_device *cool_dev;
50 unsigned int cpufreq_state;
51 unsigned int cpufreq_val;
52 struct cpumask allowed_cpus;
53};
54static DEFINE_IDR(cpufreq_idr);
55static DEFINE_MUTEX(cooling_cpufreq_lock);
56
57static unsigned int cpufreq_dev_count;
58
59/* notify_table passes value to the CPUFREQ_ADJUST callback function. */
60#define NOTIFY_INVALID NULL
61static struct cpufreq_cooling_device *notify_device;
62
63/**
64 * get_idr - function to get a unique id.
65 * @idr: struct idr * handle used to create a id.
66 * @id: int * value generated by this function.
67 *
68 * This function will populate @id with an unique
69 * id, using the idr API.
70 *
71 * Return: 0 on success, an error code on failure.
72 */
73static int get_idr(struct idr *idr, int *id)
74{
75 int ret;
76
77 mutex_lock(&cooling_cpufreq_lock);
78 ret = idr_alloc(idr, NULL, 0, 0, GFP_KERNEL);
79 mutex_unlock(&cooling_cpufreq_lock);
80 if (unlikely(ret < 0))
81 return ret;
82 *id = ret;
83
84 return 0;
85}
86
87/**
88 * release_idr - function to free the unique id.
89 * @idr: struct idr * handle used for creating the id.
90 * @id: int value representing the unique id.
91 */
92static void release_idr(struct idr *idr, int id)
93{
94 mutex_lock(&cooling_cpufreq_lock);
95 idr_remove(idr, id);
96 mutex_unlock(&cooling_cpufreq_lock);
97}
98
99/* Below code defines functions to be used for cpufreq as cooling device */
100
101/**
102 * is_cpufreq_valid - function to check frequency transitioning capability.
103 * @cpu: cpu for which check is needed.
104 *
105 * This function will check the current state of the system if
106 * it is capable of changing the frequency for a given @cpu.
107 *
108 * Return: 0 if the system is not currently capable of changing
109 * the frequency of given cpu. !0 in case the frequency is changeable.
110 */
111static int is_cpufreq_valid(int cpu)
112{
113 struct cpufreq_policy policy;
114
115 return !cpufreq_get_policy(&policy, cpu);
116}
117
118enum cpufreq_cooling_property {
119 GET_LEVEL,
120 GET_FREQ,
121 GET_MAXL,
122};
123
124/**
125 * get_property - fetch a property of interest for a give cpu.
126 * @cpu: cpu for which the property is required
127 * @input: query parameter
128 * @output: query return
129 * @property: type of query (frequency, level, max level)
130 *
131 * This is the common function to
132 * 1. get maximum cpu cooling states
133 * 2. translate frequency to cooling state
134 * 3. translate cooling state to frequency
135 * Note that the code may be not in good shape
136 * but it is written in this way in order to:
137 * a) reduce duplicate code as most of the code can be shared.
138 * b) make sure the logic is consistent when translating between
139 * cooling states and frequencies.
140 *
141 * Return: 0 on success, -EINVAL when invalid parameters are passed.
142 */
143static int get_property(unsigned int cpu, unsigned long input,
144 unsigned int *output,
145 enum cpufreq_cooling_property property)
146{
147 int i, j;
148 unsigned long max_level = 0, level = 0;
149 unsigned int freq = CPUFREQ_ENTRY_INVALID;
150 int descend = -1;
151 struct cpufreq_frequency_table *table =
152 cpufreq_frequency_get_table(cpu);
153
154 if (!output)
155 return -EINVAL;
156
157 if (!table)
158 return -EINVAL;
159
160 for (i = 0; table[i].frequency != CPUFREQ_TABLE_END; i++) {
161 /* ignore invalid entries */
162 if (table[i].frequency == CPUFREQ_ENTRY_INVALID)
163 continue;
164
165 /* ignore duplicate entry */
166 if (freq == table[i].frequency)
167 continue;
168
169 /* get the frequency order */
170 if (freq != CPUFREQ_ENTRY_INVALID && descend == -1)
171 descend = !!(freq > table[i].frequency);
172
173 freq = table[i].frequency;
174 max_level++;
175 }
176
177 /* No valid cpu frequency entry */
178 if (max_level == 0)
179 return -EINVAL;
180
181 /* max_level is an index, not a counter */
182 max_level--;
183
184 /* get max level */
185 if (property == GET_MAXL) {
186 *output = (unsigned int)max_level;
187 return 0;
188 }
189
190 if (property == GET_FREQ)
191 level = descend ? input : (max_level - input);
192
193 for (i = 0, j = 0; table[i].frequency != CPUFREQ_TABLE_END; i++) {
194 /* ignore invalid entry */
195 if (table[i].frequency == CPUFREQ_ENTRY_INVALID)
196 continue;
197
198 /* ignore duplicate entry */
199 if (freq == table[i].frequency)
200 continue;
201
202 /* now we have a valid frequency entry */
203 freq = table[i].frequency;
204
205 if (property == GET_LEVEL && (unsigned int)input == freq) {
206 /* get level by frequency */
207 *output = descend ? j : (max_level - j);
208 return 0;
209 }
210 if (property == GET_FREQ && level == j) {
211 /* get frequency by level */
212 *output = freq;
213 return 0;
214 }
215 j++;
216 }
217
218 return -EINVAL;
219}
220
221/**
222 * cpufreq_cooling_get_level - for a give cpu, return the cooling level.
223 * @cpu: cpu for which the level is required
224 * @freq: the frequency of interest
225 *
226 * This function will match the cooling level corresponding to the
227 * requested @freq and return it.
228 *
229 * Return: The matched cooling level on success or THERMAL_CSTATE_INVALID
230 * otherwise.
231 */
232unsigned long cpufreq_cooling_get_level(unsigned int cpu, unsigned int freq)
233{
234 unsigned int val;
235
236 if (get_property(cpu, (unsigned long)freq, &val, GET_LEVEL))
237 return THERMAL_CSTATE_INVALID;
238
239 return (unsigned long)val;
240}
241EXPORT_SYMBOL_GPL(cpufreq_cooling_get_level);
242
243/**
244 * get_cpu_frequency - get the absolute value of frequency from level.
245 * @cpu: cpu for which frequency is fetched.
246 * @level: cooling level
247 *
248 * This function matches cooling level with frequency. Based on a cooling level
249 * of frequency, equals cooling state of cpu cooling device, it will return
250 * the corresponding frequency.
251 * e.g level=0 --> 1st MAX FREQ, level=1 ---> 2nd MAX FREQ, .... etc
252 *
253 * Return: 0 on error, the corresponding frequency otherwise.
254 */
255static unsigned int get_cpu_frequency(unsigned int cpu, unsigned long level)
256{
257 int ret = 0;
258 unsigned int freq;
259
260 ret = get_property(cpu, level, &freq, GET_FREQ);
261 if (ret)
262 return 0;
263
264 return freq;
265}
266
267/**
268 * cpufreq_apply_cooling - function to apply frequency clipping.
269 * @cpufreq_device: cpufreq_cooling_device pointer containing frequency
270 * clipping data.
271 * @cooling_state: value of the cooling state.
272 *
273 * Function used to make sure the cpufreq layer is aware of current thermal
274 * limits. The limits are applied by updating the cpufreq policy.
275 *
276 * Return: 0 on success, an error code otherwise (-EINVAL in case wrong
277 * cooling state).
278 */
279static int cpufreq_apply_cooling(struct cpufreq_cooling_device *cpufreq_device,
280 unsigned long cooling_state)
281{
282 unsigned int cpuid, clip_freq;
283 struct cpumask *mask = &cpufreq_device->allowed_cpus;
284 unsigned int cpu = cpumask_any(mask);
285
286
287 /* Check if the old cooling action is same as new cooling action */
288 if (cpufreq_device->cpufreq_state == cooling_state)
289 return 0;
290
291 clip_freq = get_cpu_frequency(cpu, cooling_state);
292 if (!clip_freq)
293 return -EINVAL;
294
295 cpufreq_device->cpufreq_state = cooling_state;
296 cpufreq_device->cpufreq_val = clip_freq;
297 notify_device = cpufreq_device;
298
299 for_each_cpu(cpuid, mask) {
300 if (is_cpufreq_valid(cpuid))
301 cpufreq_update_policy(cpuid);
302 }
303
304 notify_device = NOTIFY_INVALID;
305
306 return 0;
307}
308
309/**
310 * cpufreq_thermal_notifier - notifier callback for cpufreq policy change.
311 * @nb: struct notifier_block * with callback info.
312 * @event: value showing cpufreq event for which this function invoked.
313 * @data: callback-specific data
314 *
315 * Callback to highjack the notification on cpufreq policy transition.
316 * Every time there is a change in policy, we will intercept and
317 * update the cpufreq policy with thermal constraints.
318 *
319 * Return: 0 (success)
320 */
321static int cpufreq_thermal_notifier(struct notifier_block *nb,
322 unsigned long event, void *data)
323{
324 struct cpufreq_policy *policy = data;
325 unsigned long max_freq = 0;
326
327 if (event != CPUFREQ_ADJUST || notify_device == NOTIFY_INVALID)
328 return 0;
329
330 if (cpumask_test_cpu(policy->cpu, ¬ify_device->allowed_cpus))
331 max_freq = notify_device->cpufreq_val;
332 else
333 return 0;
334
335 /* Never exceed user_policy.max */
336 if (max_freq > policy->user_policy.max)
337 max_freq = policy->user_policy.max;
338
339 if (policy->max != max_freq)
340 cpufreq_verify_within_limits(policy, 0, max_freq);
341
342 return 0;
343}
344
345/* cpufreq cooling device callback functions are defined below */
346
347/**
348 * cpufreq_get_max_state - callback function to get the max cooling state.
349 * @cdev: thermal cooling device pointer.
350 * @state: fill this variable with the max cooling state.
351 *
352 * Callback for the thermal cooling device to return the cpufreq
353 * max cooling state.
354 *
355 * Return: 0 on success, an error code otherwise.
356 */
357static int cpufreq_get_max_state(struct thermal_cooling_device *cdev,
358 unsigned long *state)
359{
360 struct cpufreq_cooling_device *cpufreq_device = cdev->devdata;
361 struct cpumask *mask = &cpufreq_device->allowed_cpus;
362 unsigned int cpu;
363 unsigned int count = 0;
364 int ret;
365
366 cpu = cpumask_any(mask);
367
368 ret = get_property(cpu, 0, &count, GET_MAXL);
369
370 if (count > 0)
371 *state = count;
372
373 return ret;
374}
375
376/**
377 * cpufreq_get_cur_state - callback function to get the current cooling state.
378 * @cdev: thermal cooling device pointer.
379 * @state: fill this variable with the current cooling state.
380 *
381 * Callback for the thermal cooling device to return the cpufreq
382 * current cooling state.
383 *
384 * Return: 0 on success, an error code otherwise.
385 */
386static int cpufreq_get_cur_state(struct thermal_cooling_device *cdev,
387 unsigned long *state)
388{
389 struct cpufreq_cooling_device *cpufreq_device = cdev->devdata;
390
391 *state = cpufreq_device->cpufreq_state;
392
393 return 0;
394}
395
396/**
397 * cpufreq_set_cur_state - callback function to set the current cooling state.
398 * @cdev: thermal cooling device pointer.
399 * @state: set this variable to the current cooling state.
400 *
401 * Callback for the thermal cooling device to change the cpufreq
402 * current cooling state.
403 *
404 * Return: 0 on success, an error code otherwise.
405 */
406static int cpufreq_set_cur_state(struct thermal_cooling_device *cdev,
407 unsigned long state)
408{
409 struct cpufreq_cooling_device *cpufreq_device = cdev->devdata;
410
411 return cpufreq_apply_cooling(cpufreq_device, state);
412}
413
414/* Bind cpufreq callbacks to thermal cooling device ops */
415static struct thermal_cooling_device_ops const cpufreq_cooling_ops = {
416 .get_max_state = cpufreq_get_max_state,
417 .get_cur_state = cpufreq_get_cur_state,
418 .set_cur_state = cpufreq_set_cur_state,
419};
420
421/* Notifier for cpufreq policy change */
422static struct notifier_block thermal_cpufreq_notifier_block = {
423 .notifier_call = cpufreq_thermal_notifier,
424};
425
426/**
427 * __cpufreq_cooling_register - helper function to create cpufreq cooling device
428 * @np: a valid struct device_node to the cooling device device tree node
429 * @clip_cpus: cpumask of cpus where the frequency constraints will happen.
430 *
431 * This interface function registers the cpufreq cooling device with the name
432 * "thermal-cpufreq-%x". This api can support multiple instances of cpufreq
433 * cooling devices. It also gives the opportunity to link the cooling device
434 * with a device tree node, in order to bind it via the thermal DT code.
435 *
436 * Return: a valid struct thermal_cooling_device pointer on success,
437 * on failure, it returns a corresponding ERR_PTR().
438 */
439static struct thermal_cooling_device *
440__cpufreq_cooling_register(struct device_node *np,
441 const struct cpumask *clip_cpus)
442{
443 struct thermal_cooling_device *cool_dev;
444 struct cpufreq_cooling_device *cpufreq_dev = NULL;
445 unsigned int min = 0, max = 0;
446 char dev_name[THERMAL_NAME_LENGTH];
447 int ret = 0, i;
448 struct cpufreq_policy policy;
449
450 /* Verify that all the clip cpus have same freq_min, freq_max limit */
451 for_each_cpu(i, clip_cpus) {
452 /* continue if cpufreq policy not found and not return error */
453 if (!cpufreq_get_policy(&policy, i))
454 continue;
455 if (min == 0 && max == 0) {
456 min = policy.cpuinfo.min_freq;
457 max = policy.cpuinfo.max_freq;
458 } else {
459 if (min != policy.cpuinfo.min_freq ||
460 max != policy.cpuinfo.max_freq)
461 return ERR_PTR(-EINVAL);
462 }
463 }
464 cpufreq_dev = kzalloc(sizeof(struct cpufreq_cooling_device),
465 GFP_KERNEL);
466 if (!cpufreq_dev)
467 return ERR_PTR(-ENOMEM);
468
469 cpumask_copy(&cpufreq_dev->allowed_cpus, clip_cpus);
470
471 ret = get_idr(&cpufreq_idr, &cpufreq_dev->id);
472 if (ret) {
473 kfree(cpufreq_dev);
474 return ERR_PTR(-EINVAL);
475 }
476
477 snprintf(dev_name, sizeof(dev_name), "thermal-cpufreq-%d",
478 cpufreq_dev->id);
479
480 cool_dev = thermal_of_cooling_device_register(np, dev_name, cpufreq_dev,
481 &cpufreq_cooling_ops);
482 if (IS_ERR(cool_dev)) {
483 release_idr(&cpufreq_idr, cpufreq_dev->id);
484 kfree(cpufreq_dev);
485 return cool_dev;
486 }
487 cpufreq_dev->cool_dev = cool_dev;
488 cpufreq_dev->cpufreq_state = 0;
489 mutex_lock(&cooling_cpufreq_lock);
490
491 /* Register the notifier for first cpufreq cooling device */
492 if (cpufreq_dev_count == 0)
493 cpufreq_register_notifier(&thermal_cpufreq_notifier_block,
494 CPUFREQ_POLICY_NOTIFIER);
495 cpufreq_dev_count++;
496
497 mutex_unlock(&cooling_cpufreq_lock);
498
499 return cool_dev;
500}
501
502/**
503 * cpufreq_cooling_register - function to create cpufreq cooling device.
504 * @clip_cpus: cpumask of cpus where the frequency constraints will happen.
505 *
506 * This interface function registers the cpufreq cooling device with the name
507 * "thermal-cpufreq-%x". This api can support multiple instances of cpufreq
508 * cooling devices.
509 *
510 * Return: a valid struct thermal_cooling_device pointer on success,
511 * on failure, it returns a corresponding ERR_PTR().
512 */
513struct thermal_cooling_device *
514cpufreq_cooling_register(const struct cpumask *clip_cpus)
515{
516 return __cpufreq_cooling_register(NULL, clip_cpus);
517}
518EXPORT_SYMBOL_GPL(cpufreq_cooling_register);
519
520/**
521 * of_cpufreq_cooling_register - function to create cpufreq cooling device.
522 * @np: a valid struct device_node to the cooling device device tree node
523 * @clip_cpus: cpumask of cpus where the frequency constraints will happen.
524 *
525 * This interface function registers the cpufreq cooling device with the name
526 * "thermal-cpufreq-%x". This api can support multiple instances of cpufreq
527 * cooling devices. Using this API, the cpufreq cooling device will be
528 * linked to the device tree node provided.
529 *
530 * Return: a valid struct thermal_cooling_device pointer on success,
531 * on failure, it returns a corresponding ERR_PTR().
532 */
533struct thermal_cooling_device *
534of_cpufreq_cooling_register(struct device_node *np,
535 const struct cpumask *clip_cpus)
536{
537 if (!np)
538 return ERR_PTR(-EINVAL);
539
540 return __cpufreq_cooling_register(np, clip_cpus);
541}
542EXPORT_SYMBOL_GPL(of_cpufreq_cooling_register);
543
544/**
545 * cpufreq_cooling_unregister - function to remove cpufreq cooling device.
546 * @cdev: thermal cooling device pointer.
547 *
548 * This interface function unregisters the "thermal-cpufreq-%x" cooling device.
549 */
550void cpufreq_cooling_unregister(struct thermal_cooling_device *cdev)
551{
552 struct cpufreq_cooling_device *cpufreq_dev;
553
554 if (!cdev)
555 return;
556
557 cpufreq_dev = cdev->devdata;
558 mutex_lock(&cooling_cpufreq_lock);
559 cpufreq_dev_count--;
560
561 /* Unregister the notifier for the last cpufreq cooling device */
562 if (cpufreq_dev_count == 0)
563 cpufreq_unregister_notifier(&thermal_cpufreq_notifier_block,
564 CPUFREQ_POLICY_NOTIFIER);
565 mutex_unlock(&cooling_cpufreq_lock);
566
567 thermal_cooling_device_unregister(cpufreq_dev->cool_dev);
568 release_idr(&cpufreq_idr, cpufreq_dev->id);
569 kfree(cpufreq_dev);
570}
571EXPORT_SYMBOL_GPL(cpufreq_cooling_unregister);