2 * linux/drivers/thermal/cpu_cooling.c
4 * Copyright (C) 2012 Samsung Electronics Co., Ltd(http://www.samsung.com)
5 * Copyright (C) 2012 Amit Daniel <amit.kachhap@linaro.org>
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.
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.
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.
21 * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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>
32 * struct cpufreq_cooling_device - data for cooling device with cpufreq
33 * @id: unique integer value corresponding to each cpufreq_cooling_device
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
39 * @cpufreq_val: integer value representing the absolute value of the clipped
41 * @allowed_cpus: all the cpus involved for this cpufreq_cooling_device.
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.
47 struct cpufreq_cooling_device {
49 struct thermal_cooling_device *cool_dev;
50 unsigned int cpufreq_state;
51 unsigned int cpufreq_val;
52 struct cpumask allowed_cpus;
53 struct list_head node;
55 static DEFINE_IDR(cpufreq_idr);
56 static DEFINE_MUTEX(cooling_cpufreq_lock);
58 static unsigned int cpufreq_dev_count;
60 static LIST_HEAD(cpufreq_dev_list);
63 * get_idr - function to get a unique id.
64 * @idr: struct idr * handle used to create a id.
65 * @id: int * value generated by this function.
67 * This function will populate @id with an unique
68 * id, using the idr API.
70 * Return: 0 on success, an error code on failure.
72 static int get_idr(struct idr *idr, int *id)
76 mutex_lock(&cooling_cpufreq_lock);
77 ret = idr_alloc(idr, NULL, 0, 0, GFP_KERNEL);
78 mutex_unlock(&cooling_cpufreq_lock);
79 if (unlikely(ret < 0))
87 * release_idr - function to free the unique id.
88 * @idr: struct idr * handle used for creating the id.
89 * @id: int value representing the unique id.
91 static void release_idr(struct idr *idr, int id)
93 mutex_lock(&cooling_cpufreq_lock);
95 mutex_unlock(&cooling_cpufreq_lock);
98 /* Below code defines functions to be used for cpufreq as cooling device */
101 * is_cpufreq_valid - function to check frequency transitioning capability.
102 * @cpu: cpu for which check is needed.
104 * This function will check the current state of the system if
105 * it is capable of changing the frequency for a given @cpu.
107 * Return: 0 if the system is not currently capable of changing
108 * the frequency of given cpu. !0 in case the frequency is changeable.
110 static int is_cpufreq_valid(int cpu)
112 struct cpufreq_policy policy;
114 return !cpufreq_get_policy(&policy, cpu);
117 enum cpufreq_cooling_property {
124 * get_property - fetch a property of interest for a give cpu.
125 * @cpu: cpu for which the property is required
126 * @input: query parameter
127 * @output: query return
128 * @property: type of query (frequency, level, max level)
130 * This is the common function to
131 * 1. get maximum cpu cooling states
132 * 2. translate frequency to cooling state
133 * 3. translate cooling state to frequency
134 * Note that the code may be not in good shape
135 * but it is written in this way in order to:
136 * a) reduce duplicate code as most of the code can be shared.
137 * b) make sure the logic is consistent when translating between
138 * cooling states and frequencies.
140 * Return: 0 on success, -EINVAL when invalid parameters are passed.
142 static int get_property(unsigned int cpu, unsigned long input,
143 unsigned int *output,
144 enum cpufreq_cooling_property property)
147 unsigned long max_level = 0, level = 0;
148 unsigned int freq = CPUFREQ_ENTRY_INVALID;
150 struct cpufreq_frequency_table *pos, *table =
151 cpufreq_frequency_get_table(cpu);
159 cpufreq_for_each_valid_entry(pos, table) {
160 /* ignore duplicate entry */
161 if (freq == pos->frequency)
164 /* get the frequency order */
165 if (freq != CPUFREQ_ENTRY_INVALID && descend == -1)
166 descend = freq > pos->frequency;
168 freq = pos->frequency;
172 /* No valid cpu frequency entry */
176 /* max_level is an index, not a counter */
180 if (property == GET_MAXL) {
181 *output = (unsigned int)max_level;
185 if (property == GET_FREQ)
186 level = descend ? input : (max_level - input);
189 cpufreq_for_each_valid_entry(pos, table) {
190 /* ignore duplicate entry */
191 if (freq == pos->frequency)
194 /* now we have a valid frequency entry */
195 freq = pos->frequency;
197 if (property == GET_LEVEL && (unsigned int)input == freq) {
198 /* get level by frequency */
199 *output = descend ? i : (max_level - i);
202 if (property == GET_FREQ && level == i) {
203 /* get frequency by level */
214 * cpufreq_cooling_get_level - for a give cpu, return the cooling level.
215 * @cpu: cpu for which the level is required
216 * @freq: the frequency of interest
218 * This function will match the cooling level corresponding to the
219 * requested @freq and return it.
221 * Return: The matched cooling level on success or THERMAL_CSTATE_INVALID
224 unsigned long cpufreq_cooling_get_level(unsigned int cpu, unsigned int freq)
228 if (get_property(cpu, (unsigned long)freq, &val, GET_LEVEL))
229 return THERMAL_CSTATE_INVALID;
231 return (unsigned long)val;
233 EXPORT_SYMBOL_GPL(cpufreq_cooling_get_level);
236 * get_cpu_frequency - get the absolute value of frequency from level.
237 * @cpu: cpu for which frequency is fetched.
238 * @level: cooling level
240 * This function matches cooling level with frequency. Based on a cooling level
241 * of frequency, equals cooling state of cpu cooling device, it will return
242 * the corresponding frequency.
243 * e.g level=0 --> 1st MAX FREQ, level=1 ---> 2nd MAX FREQ, .... etc
245 * Return: 0 on error, the corresponding frequency otherwise.
247 static unsigned int get_cpu_frequency(unsigned int cpu, unsigned long level)
252 ret = get_property(cpu, level, &freq, GET_FREQ);
260 * cpufreq_apply_cooling - function to apply frequency clipping.
261 * @cpufreq_device: cpufreq_cooling_device pointer containing frequency
263 * @cooling_state: value of the cooling state.
265 * Function used to make sure the cpufreq layer is aware of current thermal
266 * limits. The limits are applied by updating the cpufreq policy.
268 * Return: 0 on success, an error code otherwise (-EINVAL in case wrong
271 static int cpufreq_apply_cooling(struct cpufreq_cooling_device *cpufreq_device,
272 unsigned long cooling_state)
274 unsigned int cpuid, clip_freq;
275 struct cpumask *mask = &cpufreq_device->allowed_cpus;
276 unsigned int cpu = cpumask_any(mask);
279 /* Check if the old cooling action is same as new cooling action */
280 if (cpufreq_device->cpufreq_state == cooling_state)
283 clip_freq = get_cpu_frequency(cpu, cooling_state);
287 cpufreq_device->cpufreq_state = cooling_state;
288 cpufreq_device->cpufreq_val = clip_freq;
290 for_each_cpu(cpuid, mask) {
291 if (is_cpufreq_valid(cpuid))
292 cpufreq_update_policy(cpuid);
299 * cpufreq_thermal_notifier - notifier callback for cpufreq policy change.
300 * @nb: struct notifier_block * with callback info.
301 * @event: value showing cpufreq event for which this function invoked.
302 * @data: callback-specific data
304 * Callback to hijack the notification on cpufreq policy transition.
305 * Every time there is a change in policy, we will intercept and
306 * update the cpufreq policy with thermal constraints.
308 * Return: 0 (success)
310 static int cpufreq_thermal_notifier(struct notifier_block *nb,
311 unsigned long event, void *data)
313 struct cpufreq_policy *policy = data;
314 unsigned long max_freq = 0;
315 struct cpufreq_cooling_device *cpufreq_dev;
317 if (event != CPUFREQ_ADJUST)
320 mutex_lock(&cooling_cpufreq_lock);
321 list_for_each_entry(cpufreq_dev, &cpufreq_dev_list, node) {
322 if (!cpumask_test_cpu(policy->cpu,
323 &cpufreq_dev->allowed_cpus))
326 if (!cpufreq_dev->cpufreq_val)
327 cpufreq_dev->cpufreq_val = get_cpu_frequency(
328 cpumask_any(&cpufreq_dev->allowed_cpus),
329 cpufreq_dev->cpufreq_state);
331 max_freq = cpufreq_dev->cpufreq_val;
333 if (policy->max != max_freq)
334 cpufreq_verify_within_limits(policy, 0, max_freq);
336 mutex_unlock(&cooling_cpufreq_lock);
341 /* cpufreq cooling device callback functions are defined below */
344 * cpufreq_get_max_state - callback function to get the max cooling state.
345 * @cdev: thermal cooling device pointer.
346 * @state: fill this variable with the max cooling state.
348 * Callback for the thermal cooling device to return the cpufreq
351 * Return: 0 on success, an error code otherwise.
353 static int cpufreq_get_max_state(struct thermal_cooling_device *cdev,
354 unsigned long *state)
356 struct cpufreq_cooling_device *cpufreq_device = cdev->devdata;
357 struct cpumask *mask = &cpufreq_device->allowed_cpus;
359 unsigned int count = 0;
362 cpu = cpumask_any(mask);
364 ret = get_property(cpu, 0, &count, GET_MAXL);
373 * cpufreq_get_cur_state - callback function to get the current cooling state.
374 * @cdev: thermal cooling device pointer.
375 * @state: fill this variable with the current cooling state.
377 * Callback for the thermal cooling device to return the cpufreq
378 * current cooling state.
380 * Return: 0 on success, an error code otherwise.
382 static int cpufreq_get_cur_state(struct thermal_cooling_device *cdev,
383 unsigned long *state)
385 struct cpufreq_cooling_device *cpufreq_device = cdev->devdata;
387 *state = cpufreq_device->cpufreq_state;
393 * cpufreq_set_cur_state - callback function to set the current cooling state.
394 * @cdev: thermal cooling device pointer.
395 * @state: set this variable to the current cooling state.
397 * Callback for the thermal cooling device to change the cpufreq
398 * current cooling state.
400 * Return: 0 on success, an error code otherwise.
402 static int cpufreq_set_cur_state(struct thermal_cooling_device *cdev,
405 struct cpufreq_cooling_device *cpufreq_device = cdev->devdata;
407 return cpufreq_apply_cooling(cpufreq_device, state);
410 /* Bind cpufreq callbacks to thermal cooling device ops */
411 static struct thermal_cooling_device_ops const cpufreq_cooling_ops = {
412 .get_max_state = cpufreq_get_max_state,
413 .get_cur_state = cpufreq_get_cur_state,
414 .set_cur_state = cpufreq_set_cur_state,
417 /* Notifier for cpufreq policy change */
418 static struct notifier_block thermal_cpufreq_notifier_block = {
419 .notifier_call = cpufreq_thermal_notifier,
423 * __cpufreq_cooling_register - helper function to create cpufreq cooling device
424 * @np: a valid struct device_node to the cooling device device tree node
425 * @clip_cpus: cpumask of cpus where the frequency constraints will happen.
427 * This interface function registers the cpufreq cooling device with the name
428 * "thermal-cpufreq-%x". This api can support multiple instances of cpufreq
429 * cooling devices. It also gives the opportunity to link the cooling device
430 * with a device tree node, in order to bind it via the thermal DT code.
432 * Return: a valid struct thermal_cooling_device pointer on success,
433 * on failure, it returns a corresponding ERR_PTR().
435 static struct thermal_cooling_device *
436 __cpufreq_cooling_register(struct device_node *np,
437 const struct cpumask *clip_cpus)
439 struct thermal_cooling_device *cool_dev;
440 struct cpufreq_cooling_device *cpufreq_dev = NULL;
441 unsigned int min = 0, max = 0;
442 char dev_name[THERMAL_NAME_LENGTH];
444 struct cpufreq_policy policy;
446 /* Verify that all the clip cpus have same freq_min, freq_max limit */
447 for_each_cpu(i, clip_cpus) {
448 /* continue if cpufreq policy not found and not return error */
449 if (!cpufreq_get_policy(&policy, i))
451 if (min == 0 && max == 0) {
452 min = policy.cpuinfo.min_freq;
453 max = policy.cpuinfo.max_freq;
455 if (min != policy.cpuinfo.min_freq ||
456 max != policy.cpuinfo.max_freq)
457 return ERR_PTR(-EINVAL);
460 cpufreq_dev = kzalloc(sizeof(struct cpufreq_cooling_device),
463 return ERR_PTR(-ENOMEM);
465 cpumask_copy(&cpufreq_dev->allowed_cpus, clip_cpus);
467 ret = get_idr(&cpufreq_idr, &cpufreq_dev->id);
470 return ERR_PTR(-EINVAL);
473 snprintf(dev_name, sizeof(dev_name), "thermal-cpufreq-%d",
476 cool_dev = thermal_of_cooling_device_register(np, dev_name, cpufreq_dev,
477 &cpufreq_cooling_ops);
478 if (IS_ERR(cool_dev)) {
479 release_idr(&cpufreq_idr, cpufreq_dev->id);
483 cpufreq_dev->cool_dev = cool_dev;
484 cpufreq_dev->cpufreq_state = 0;
485 mutex_lock(&cooling_cpufreq_lock);
487 /* Register the notifier for first cpufreq cooling device */
488 if (cpufreq_dev_count == 0)
489 cpufreq_register_notifier(&thermal_cpufreq_notifier_block,
490 CPUFREQ_POLICY_NOTIFIER);
492 list_add(&cpufreq_dev->node, &cpufreq_dev_list);
494 mutex_unlock(&cooling_cpufreq_lock);
500 * cpufreq_cooling_register - function to create cpufreq cooling device.
501 * @clip_cpus: cpumask of cpus where the frequency constraints will happen.
503 * This interface function registers the cpufreq cooling device with the name
504 * "thermal-cpufreq-%x". This api can support multiple instances of cpufreq
507 * Return: a valid struct thermal_cooling_device pointer on success,
508 * on failure, it returns a corresponding ERR_PTR().
510 struct thermal_cooling_device *
511 cpufreq_cooling_register(const struct cpumask *clip_cpus)
513 return __cpufreq_cooling_register(NULL, clip_cpus);
515 EXPORT_SYMBOL_GPL(cpufreq_cooling_register);
518 * of_cpufreq_cooling_register - function to create cpufreq cooling device.
519 * @np: a valid struct device_node to the cooling device device tree node
520 * @clip_cpus: cpumask of cpus where the frequency constraints will happen.
522 * This interface function registers the cpufreq cooling device with the name
523 * "thermal-cpufreq-%x". This api can support multiple instances of cpufreq
524 * cooling devices. Using this API, the cpufreq cooling device will be
525 * linked to the device tree node provided.
527 * Return: a valid struct thermal_cooling_device pointer on success,
528 * on failure, it returns a corresponding ERR_PTR().
530 struct thermal_cooling_device *
531 of_cpufreq_cooling_register(struct device_node *np,
532 const struct cpumask *clip_cpus)
535 return ERR_PTR(-EINVAL);
537 return __cpufreq_cooling_register(np, clip_cpus);
539 EXPORT_SYMBOL_GPL(of_cpufreq_cooling_register);
542 * cpufreq_cooling_unregister - function to remove cpufreq cooling device.
543 * @cdev: thermal cooling device pointer.
545 * This interface function unregisters the "thermal-cpufreq-%x" cooling device.
547 void cpufreq_cooling_unregister(struct thermal_cooling_device *cdev)
549 struct cpufreq_cooling_device *cpufreq_dev;
554 cpufreq_dev = cdev->devdata;
555 mutex_lock(&cooling_cpufreq_lock);
556 list_del(&cpufreq_dev->node);
559 /* Unregister the notifier for the last cpufreq cooling device */
560 if (cpufreq_dev_count == 0)
561 cpufreq_unregister_notifier(&thermal_cpufreq_notifier_block,
562 CPUFREQ_POLICY_NOTIFIER);
563 mutex_unlock(&cooling_cpufreq_lock);
565 thermal_cooling_device_unregister(cpufreq_dev->cool_dev);
566 release_idr(&cpufreq_idr, cpufreq_dev->id);
569 EXPORT_SYMBOL_GPL(cpufreq_cooling_unregister);