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.
42 * @node: list_head to link all cpufreq_cooling_device together.
44 * This structure is required for keeping information of each
45 * cpufreq_cooling_device registered. In order to prevent corruption of this a
46 * mutex lock cooling_cpufreq_lock is used.
48 struct cpufreq_cooling_device {
50 struct thermal_cooling_device *cool_dev;
51 unsigned int cpufreq_state;
52 unsigned int cpufreq_val;
53 struct cpumask allowed_cpus;
54 struct list_head node;
56 static DEFINE_IDR(cpufreq_idr);
57 static DEFINE_MUTEX(cooling_cpufreq_lock);
59 static unsigned int cpufreq_dev_count;
61 static LIST_HEAD(cpufreq_dev_list);
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.
68 * This function will populate @id with an unique
69 * id, using the idr API.
71 * Return: 0 on success, an error code on failure.
73 static int get_idr(struct idr *idr, int *id)
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))
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.
92 static void release_idr(struct idr *idr, int id)
94 mutex_lock(&cooling_cpufreq_lock);
96 mutex_unlock(&cooling_cpufreq_lock);
99 /* Below code defines functions to be used for cpufreq as cooling device */
102 * is_cpufreq_valid - function to check frequency transitioning capability.
103 * @cpu: cpu for which check is needed.
105 * This function will check the current state of the system if
106 * it is capable of changing the frequency for a given @cpu.
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.
111 static int is_cpufreq_valid(int cpu)
113 struct cpufreq_policy policy;
115 return !cpufreq_get_policy(&policy, cpu);
118 enum cpufreq_cooling_property {
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)
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.
141 * Return: 0 on success, -EINVAL when invalid parameters are passed.
143 static int get_property(unsigned int cpu, unsigned long input,
144 unsigned int *output,
145 enum cpufreq_cooling_property property)
148 unsigned long max_level = 0, level = 0;
149 unsigned int freq = CPUFREQ_ENTRY_INVALID;
151 struct cpufreq_frequency_table *pos, *table =
152 cpufreq_frequency_get_table(cpu);
160 cpufreq_for_each_valid_entry(pos, table) {
161 /* ignore duplicate entry */
162 if (freq == pos->frequency)
165 /* get the frequency order */
166 if (freq != CPUFREQ_ENTRY_INVALID && descend == -1)
167 descend = freq > pos->frequency;
169 freq = pos->frequency;
173 /* No valid cpu frequency entry */
177 /* max_level is an index, not a counter */
181 if (property == GET_MAXL) {
182 *output = (unsigned int)max_level;
186 if (property == GET_FREQ)
187 level = descend ? input : (max_level - input);
190 cpufreq_for_each_valid_entry(pos, table) {
191 /* ignore duplicate entry */
192 if (freq == pos->frequency)
195 /* now we have a valid frequency entry */
196 freq = pos->frequency;
198 if (property == GET_LEVEL && (unsigned int)input == freq) {
199 /* get level by frequency */
200 *output = descend ? i : (max_level - i);
203 if (property == GET_FREQ && level == i) {
204 /* get frequency by level */
215 * cpufreq_cooling_get_level - for a give cpu, return the cooling level.
216 * @cpu: cpu for which the level is required
217 * @freq: the frequency of interest
219 * This function will match the cooling level corresponding to the
220 * requested @freq and return it.
222 * Return: The matched cooling level on success or THERMAL_CSTATE_INVALID
225 unsigned long cpufreq_cooling_get_level(unsigned int cpu, unsigned int freq)
229 if (get_property(cpu, (unsigned long)freq, &val, GET_LEVEL))
230 return THERMAL_CSTATE_INVALID;
232 return (unsigned long)val;
234 EXPORT_SYMBOL_GPL(cpufreq_cooling_get_level);
237 * get_cpu_frequency - get the absolute value of frequency from level.
238 * @cpu: cpu for which frequency is fetched.
239 * @level: cooling level
241 * This function matches cooling level with frequency. Based on a cooling level
242 * of frequency, equals cooling state of cpu cooling device, it will return
243 * the corresponding frequency.
244 * e.g level=0 --> 1st MAX FREQ, level=1 ---> 2nd MAX FREQ, .... etc
246 * Return: 0 on error, the corresponding frequency otherwise.
248 static unsigned int get_cpu_frequency(unsigned int cpu, unsigned long level)
253 ret = get_property(cpu, level, &freq, GET_FREQ);
261 * cpufreq_apply_cooling - function to apply frequency clipping.
262 * @cpufreq_device: cpufreq_cooling_device pointer containing frequency
264 * @cooling_state: value of the cooling state.
266 * Function used to make sure the cpufreq layer is aware of current thermal
267 * limits. The limits are applied by updating the cpufreq policy.
269 * Return: 0 on success, an error code otherwise (-EINVAL in case wrong
272 static int cpufreq_apply_cooling(struct cpufreq_cooling_device *cpufreq_device,
273 unsigned long cooling_state)
275 unsigned int cpuid, clip_freq;
276 struct cpumask *mask = &cpufreq_device->allowed_cpus;
277 unsigned int cpu = cpumask_any(mask);
280 /* Check if the old cooling action is same as new cooling action */
281 if (cpufreq_device->cpufreq_state == cooling_state)
284 clip_freq = get_cpu_frequency(cpu, cooling_state);
288 cpufreq_device->cpufreq_state = cooling_state;
289 cpufreq_device->cpufreq_val = clip_freq;
291 for_each_cpu(cpuid, mask) {
292 if (is_cpufreq_valid(cpuid))
293 cpufreq_update_policy(cpuid);
300 * cpufreq_thermal_notifier - notifier callback for cpufreq policy change.
301 * @nb: struct notifier_block * with callback info.
302 * @event: value showing cpufreq event for which this function invoked.
303 * @data: callback-specific data
305 * Callback to hijack the notification on cpufreq policy transition.
306 * Every time there is a change in policy, we will intercept and
307 * update the cpufreq policy with thermal constraints.
309 * Return: 0 (success)
311 static int cpufreq_thermal_notifier(struct notifier_block *nb,
312 unsigned long event, void *data)
314 struct cpufreq_policy *policy = data;
315 unsigned long max_freq = 0;
316 struct cpufreq_cooling_device *cpufreq_dev;
318 if (event != CPUFREQ_ADJUST)
321 mutex_lock(&cooling_cpufreq_lock);
322 list_for_each_entry(cpufreq_dev, &cpufreq_dev_list, node) {
323 if (!cpumask_test_cpu(policy->cpu,
324 &cpufreq_dev->allowed_cpus))
327 if (!cpufreq_dev->cpufreq_val)
328 cpufreq_dev->cpufreq_val = get_cpu_frequency(
329 cpumask_any(&cpufreq_dev->allowed_cpus),
330 cpufreq_dev->cpufreq_state);
332 max_freq = cpufreq_dev->cpufreq_val;
334 if (policy->max != max_freq)
335 cpufreq_verify_within_limits(policy, 0, max_freq);
337 mutex_unlock(&cooling_cpufreq_lock);
342 /* cpufreq cooling device callback functions are defined below */
345 * cpufreq_get_max_state - callback function to get the max cooling state.
346 * @cdev: thermal cooling device pointer.
347 * @state: fill this variable with the max cooling state.
349 * Callback for the thermal cooling device to return the cpufreq
352 * Return: 0 on success, an error code otherwise.
354 static int cpufreq_get_max_state(struct thermal_cooling_device *cdev,
355 unsigned long *state)
357 struct cpufreq_cooling_device *cpufreq_device = cdev->devdata;
358 struct cpumask *mask = &cpufreq_device->allowed_cpus;
360 unsigned int count = 0;
363 cpu = cpumask_any(mask);
365 ret = get_property(cpu, 0, &count, GET_MAXL);
374 * cpufreq_get_cur_state - callback function to get the current cooling state.
375 * @cdev: thermal cooling device pointer.
376 * @state: fill this variable with the current cooling state.
378 * Callback for the thermal cooling device to return the cpufreq
379 * current cooling state.
381 * Return: 0 on success, an error code otherwise.
383 static int cpufreq_get_cur_state(struct thermal_cooling_device *cdev,
384 unsigned long *state)
386 struct cpufreq_cooling_device *cpufreq_device = cdev->devdata;
388 *state = cpufreq_device->cpufreq_state;
394 * cpufreq_set_cur_state - callback function to set the current cooling state.
395 * @cdev: thermal cooling device pointer.
396 * @state: set this variable to the current cooling state.
398 * Callback for the thermal cooling device to change the cpufreq
399 * current cooling state.
401 * Return: 0 on success, an error code otherwise.
403 static int cpufreq_set_cur_state(struct thermal_cooling_device *cdev,
406 struct cpufreq_cooling_device *cpufreq_device = cdev->devdata;
408 return cpufreq_apply_cooling(cpufreq_device, state);
411 /* Bind cpufreq callbacks to thermal cooling device ops */
412 static struct thermal_cooling_device_ops const cpufreq_cooling_ops = {
413 .get_max_state = cpufreq_get_max_state,
414 .get_cur_state = cpufreq_get_cur_state,
415 .set_cur_state = cpufreq_set_cur_state,
418 /* Notifier for cpufreq policy change */
419 static struct notifier_block thermal_cpufreq_notifier_block = {
420 .notifier_call = cpufreq_thermal_notifier,
424 * __cpufreq_cooling_register - helper function to create cpufreq cooling device
425 * @np: a valid struct device_node to the cooling device device tree node
426 * @clip_cpus: cpumask of cpus where the frequency constraints will happen.
428 * This interface function registers the cpufreq cooling device with the name
429 * "thermal-cpufreq-%x". This api can support multiple instances of cpufreq
430 * cooling devices. It also gives the opportunity to link the cooling device
431 * with a device tree node, in order to bind it via the thermal DT code.
433 * Return: a valid struct thermal_cooling_device pointer on success,
434 * on failure, it returns a corresponding ERR_PTR().
436 static struct thermal_cooling_device *
437 __cpufreq_cooling_register(struct device_node *np,
438 const struct cpumask *clip_cpus)
440 struct thermal_cooling_device *cool_dev;
441 struct cpufreq_cooling_device *cpufreq_dev = NULL;
442 unsigned int min = 0, max = 0;
443 char dev_name[THERMAL_NAME_LENGTH];
445 struct cpufreq_policy policy;
447 /* Verify that all the clip cpus have same freq_min, freq_max limit */
448 for_each_cpu(i, clip_cpus) {
449 /* continue if cpufreq policy not found and not return error */
450 if (!cpufreq_get_policy(&policy, i))
452 if (min == 0 && max == 0) {
453 min = policy.cpuinfo.min_freq;
454 max = policy.cpuinfo.max_freq;
456 if (min != policy.cpuinfo.min_freq ||
457 max != policy.cpuinfo.max_freq)
458 return ERR_PTR(-EINVAL);
461 cpufreq_dev = kzalloc(sizeof(struct cpufreq_cooling_device),
464 return ERR_PTR(-ENOMEM);
466 cpumask_copy(&cpufreq_dev->allowed_cpus, clip_cpus);
468 ret = get_idr(&cpufreq_idr, &cpufreq_dev->id);
471 return ERR_PTR(-EINVAL);
474 snprintf(dev_name, sizeof(dev_name), "thermal-cpufreq-%d",
477 cool_dev = thermal_of_cooling_device_register(np, dev_name, cpufreq_dev,
478 &cpufreq_cooling_ops);
479 if (IS_ERR(cool_dev)) {
480 release_idr(&cpufreq_idr, cpufreq_dev->id);
484 cpufreq_dev->cool_dev = cool_dev;
485 cpufreq_dev->cpufreq_state = 0;
486 mutex_lock(&cooling_cpufreq_lock);
488 /* Register the notifier for first cpufreq cooling device */
489 if (cpufreq_dev_count == 0)
490 cpufreq_register_notifier(&thermal_cpufreq_notifier_block,
491 CPUFREQ_POLICY_NOTIFIER);
493 list_add(&cpufreq_dev->node, &cpufreq_dev_list);
495 mutex_unlock(&cooling_cpufreq_lock);
501 * cpufreq_cooling_register - function to create cpufreq cooling device.
502 * @clip_cpus: cpumask of cpus where the frequency constraints will happen.
504 * This interface function registers the cpufreq cooling device with the name
505 * "thermal-cpufreq-%x". This api can support multiple instances of cpufreq
508 * Return: a valid struct thermal_cooling_device pointer on success,
509 * on failure, it returns a corresponding ERR_PTR().
511 struct thermal_cooling_device *
512 cpufreq_cooling_register(const struct cpumask *clip_cpus)
514 return __cpufreq_cooling_register(NULL, clip_cpus);
516 EXPORT_SYMBOL_GPL(cpufreq_cooling_register);
519 * of_cpufreq_cooling_register - function to create cpufreq cooling device.
520 * @np: a valid struct device_node to the cooling device device tree node
521 * @clip_cpus: cpumask of cpus where the frequency constraints will happen.
523 * This interface function registers the cpufreq cooling device with the name
524 * "thermal-cpufreq-%x". This api can support multiple instances of cpufreq
525 * cooling devices. Using this API, the cpufreq cooling device will be
526 * linked to the device tree node provided.
528 * Return: a valid struct thermal_cooling_device pointer on success,
529 * on failure, it returns a corresponding ERR_PTR().
531 struct thermal_cooling_device *
532 of_cpufreq_cooling_register(struct device_node *np,
533 const struct cpumask *clip_cpus)
536 return ERR_PTR(-EINVAL);
538 return __cpufreq_cooling_register(np, clip_cpus);
540 EXPORT_SYMBOL_GPL(of_cpufreq_cooling_register);
543 * cpufreq_cooling_unregister - function to remove cpufreq cooling device.
544 * @cdev: thermal cooling device pointer.
546 * This interface function unregisters the "thermal-cpufreq-%x" cooling device.
548 void cpufreq_cooling_unregister(struct thermal_cooling_device *cdev)
550 struct cpufreq_cooling_device *cpufreq_dev;
555 cpufreq_dev = cdev->devdata;
556 mutex_lock(&cooling_cpufreq_lock);
557 list_del(&cpufreq_dev->node);
560 /* Unregister the notifier for the last cpufreq cooling device */
561 if (cpufreq_dev_count == 0)
562 cpufreq_unregister_notifier(&thermal_cpufreq_notifier_block,
563 CPUFREQ_POLICY_NOTIFIER);
564 mutex_unlock(&cooling_cpufreq_lock);
566 thermal_cooling_device_unregister(cpufreq_dev->cool_dev);
567 release_idr(&cpufreq_idr, cpufreq_dev->id);
570 EXPORT_SYMBOL_GPL(cpufreq_cooling_unregister);