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;
54 static DEFINE_IDR(cpufreq_idr);
55 static DEFINE_MUTEX(cooling_cpufreq_lock);
57 static unsigned int cpufreq_dev_count;
59 /* notify_table passes value to the CPUFREQ_ADJUST callback function. */
60 #define NOTIFY_INVALID NULL
61 static struct cpufreq_cooling_device *notify_device;
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 static int get_idr(struct idr *idr, int *id)
72 mutex_lock(&cooling_cpufreq_lock);
73 ret = idr_alloc(idr, NULL, 0, 0, GFP_KERNEL);
74 mutex_unlock(&cooling_cpufreq_lock);
75 if (unlikely(ret < 0))
82 * release_idr - function to free the unique id.
83 * @idr: struct idr * handle used for creating the id.
84 * @id: int value representing the unique id.
86 static void release_idr(struct idr *idr, int id)
88 mutex_lock(&cooling_cpufreq_lock);
90 mutex_unlock(&cooling_cpufreq_lock);
93 /* Below code defines functions to be used for cpufreq as cooling device */
96 * is_cpufreq_valid - function to check frequency transitioning capability.
97 * @cpu: cpu for which check is needed.
99 * This function will check the current state of the system if
100 * it is capable of changing the frequency for a given @cpu.
102 * Return: 0 if the system is not currently capable of changing
103 * the frequency of given cpu. !0 in case the frequency is changeable.
105 static int is_cpufreq_valid(int cpu)
107 struct cpufreq_policy policy;
108 return !cpufreq_get_policy(&policy, cpu);
111 enum cpufreq_cooling_property {
118 * get_property - fetch a property of interest for a give cpu.
119 * @cpu: cpu for which the property is required
120 * @input: query parameter
121 * @output: query return
122 * @property: type of query (frequency, level, max level)
124 * This is the common function to
125 * 1. get maximum cpu cooling states
126 * 2. translate frequency to cooling state
127 * 3. translate cooling state to frequency
128 * Note that the code may be not in good shape
129 * but it is written in this way in order to:
130 * a) reduce duplicate code as most of the code can be shared.
131 * b) make sure the logic is consistent when translating between
132 * cooling states and frequencies.
134 * Return: 0 on success, -EINVAL when invalid parameters are passed.
136 static int get_property(unsigned int cpu, unsigned long input,
137 unsigned int* output, enum cpufreq_cooling_property property)
140 unsigned long max_level = 0, level = 0;
141 unsigned int freq = CPUFREQ_ENTRY_INVALID;
143 struct cpufreq_frequency_table *table =
144 cpufreq_frequency_get_table(cpu);
153 for (i = 0; table[i].frequency != CPUFREQ_TABLE_END; i++) {
154 /* ignore invalid entries */
155 if (table[i].frequency == CPUFREQ_ENTRY_INVALID)
158 /* ignore duplicate entry */
159 if (freq == table[i].frequency)
162 /* get the frequency order */
163 if (freq != CPUFREQ_ENTRY_INVALID && descend != -1)
164 descend = !!(freq > table[i].frequency);
166 freq = table[i].frequency;
171 if (property == GET_MAXL) {
172 *output = (unsigned int)max_level;
176 if (property == GET_FREQ)
177 level = descend ? input : (max_level - input -1);
180 for (i = 0, j = 0; table[i].frequency != CPUFREQ_TABLE_END; i++) {
181 /* ignore invalid entry */
182 if (table[i].frequency == CPUFREQ_ENTRY_INVALID)
185 /* ignore duplicate entry */
186 if (freq == table[i].frequency)
189 /* now we have a valid frequency entry */
190 freq = table[i].frequency;
192 if (property == GET_LEVEL && (unsigned int)input == freq) {
193 /* get level by frequency */
194 *output = descend ? j : (max_level - j - 1);
197 if (property == GET_FREQ && level == j) {
198 /* get frequency by level */
208 * cpufreq_cooling_get_level - for a give cpu, return the cooling level.
209 * @cpu: cpu for which the level is required
210 * @freq: the frequency of interest
212 * This function will match the cooling level corresponding to the
213 * requested @freq and return it.
215 * Return: The matched cooling level on success or THERMAL_CSTATE_INVALID
218 unsigned long cpufreq_cooling_get_level(unsigned int cpu, unsigned int freq)
222 if (get_property(cpu, (unsigned long)freq, &val, GET_LEVEL))
223 return THERMAL_CSTATE_INVALID;
224 return (unsigned long)val;
226 EXPORT_SYMBOL_GPL(cpufreq_cooling_get_level);
229 * get_cpu_frequency - get the absolute value of frequency from level.
230 * @cpu: cpu for which frequency is fetched.
231 * @level: cooling level
233 * This function matches cooling level with frequency. Based on a cooling level
234 * of frequency, equals cooling state of cpu cooling device, it will return
235 * the corresponding frequency.
236 * e.g level=0 --> 1st MAX FREQ, level=1 ---> 2nd MAX FREQ, .... etc
238 * Return: 0 on error, the corresponding frequency otherwise.
240 static unsigned int get_cpu_frequency(unsigned int cpu, unsigned long level)
245 ret = get_property(cpu, level, &freq, GET_FREQ);
252 * cpufreq_apply_cooling - function to apply frequency clipping.
253 * @cpufreq_device: cpufreq_cooling_device pointer containing frequency
255 * @cooling_state: value of the cooling state.
257 * Function used to make sure the cpufreq layer is aware of current thermal
258 * limits. The limits are applied by updating the cpufreq policy.
260 * Return: 0 on success, an error code otherwise (-EINVAL in case wrong
263 static int cpufreq_apply_cooling(struct cpufreq_cooling_device *cpufreq_device,
264 unsigned long cooling_state)
266 unsigned int cpuid, clip_freq;
267 struct cpumask *mask = &cpufreq_device->allowed_cpus;
268 unsigned int cpu = cpumask_any(mask);
271 /* Check if the old cooling action is same as new cooling action */
272 if (cpufreq_device->cpufreq_state == cooling_state)
275 clip_freq = get_cpu_frequency(cpu, cooling_state);
279 cpufreq_device->cpufreq_state = cooling_state;
280 cpufreq_device->cpufreq_val = clip_freq;
281 notify_device = cpufreq_device;
283 for_each_cpu(cpuid, mask) {
284 if (is_cpufreq_valid(cpuid))
285 cpufreq_update_policy(cpuid);
288 notify_device = NOTIFY_INVALID;
294 * cpufreq_thermal_notifier - notifier callback for cpufreq policy change.
295 * @nb: struct notifier_block * with callback info.
296 * @event: value showing cpufreq event for which this function invoked.
297 * @data: callback-specific data
299 * Callback to highjack the notification on cpufreq policy transition.
300 * Every time there is a change in policy, we will intercept and
301 * update the cpufreq policy with thermal constraints.
303 * Return: 0 (success)
305 static int cpufreq_thermal_notifier(struct notifier_block *nb,
306 unsigned long event, void *data)
308 struct cpufreq_policy *policy = data;
309 unsigned long max_freq = 0;
311 if (event != CPUFREQ_ADJUST || notify_device == NOTIFY_INVALID)
314 if (cpumask_test_cpu(policy->cpu, ¬ify_device->allowed_cpus))
315 max_freq = notify_device->cpufreq_val;
317 /* Never exceed user_policy.max*/
318 if (max_freq > policy->user_policy.max)
319 max_freq = policy->user_policy.max;
321 if (policy->max != max_freq)
322 cpufreq_verify_within_limits(policy, 0, max_freq);
328 * cpufreq cooling device callback functions are defined below
332 * cpufreq_get_max_state - callback function to get the max cooling state.
333 * @cdev: thermal cooling device pointer.
334 * @state: fill this variable with the max cooling state.
336 * Callback for the thermal cooling device to return the cpufreq
339 * Return: 0 on success, an error code otherwise.
341 static int cpufreq_get_max_state(struct thermal_cooling_device *cdev,
342 unsigned long *state)
344 struct cpufreq_cooling_device *cpufreq_device = cdev->devdata;
345 struct cpumask *mask = &cpufreq_device->allowed_cpus;
347 unsigned int count = 0;
350 cpu = cpumask_any(mask);
352 ret = get_property(cpu, 0, &count, GET_MAXL);
361 * cpufreq_get_cur_state - callback function to get the current cooling state.
362 * @cdev: thermal cooling device pointer.
363 * @state: fill this variable with the current cooling state.
365 * Callback for the thermal cooling device to return the cpufreq
366 * current cooling state.
368 * Return: 0 on success, an error code otherwise.
370 static int cpufreq_get_cur_state(struct thermal_cooling_device *cdev,
371 unsigned long *state)
373 struct cpufreq_cooling_device *cpufreq_device = cdev->devdata;
375 *state = cpufreq_device->cpufreq_state;
380 * cpufreq_set_cur_state - callback function to set the current cooling state.
381 * @cdev: thermal cooling device pointer.
382 * @state: set this variable to the current cooling state.
384 * Callback for the thermal cooling device to change the cpufreq
385 * current cooling state.
387 * Return: 0 on success, an error code otherwise.
389 static int cpufreq_set_cur_state(struct thermal_cooling_device *cdev,
392 struct cpufreq_cooling_device *cpufreq_device = cdev->devdata;
394 return cpufreq_apply_cooling(cpufreq_device, state);
397 /* Bind cpufreq callbacks to thermal cooling device ops */
398 static struct thermal_cooling_device_ops const cpufreq_cooling_ops = {
399 .get_max_state = cpufreq_get_max_state,
400 .get_cur_state = cpufreq_get_cur_state,
401 .set_cur_state = cpufreq_set_cur_state,
404 /* Notifier for cpufreq policy change */
405 static struct notifier_block thermal_cpufreq_notifier_block = {
406 .notifier_call = cpufreq_thermal_notifier,
410 * cpufreq_cooling_register - function to create cpufreq cooling device.
411 * @clip_cpus: cpumask of cpus where the frequency constraints will happen.
413 * This interface function registers the cpufreq cooling device with the name
414 * "thermal-cpufreq-%x". This api can support multiple instances of cpufreq
417 * Return: a valid struct thermal_cooling_device pointer on success,
418 * on failure, it returns a corresponding ERR_PTR().
420 struct thermal_cooling_device *cpufreq_cooling_register(
421 const struct cpumask *clip_cpus)
423 struct thermal_cooling_device *cool_dev;
424 struct cpufreq_cooling_device *cpufreq_dev = NULL;
425 unsigned int min = 0, max = 0;
426 char dev_name[THERMAL_NAME_LENGTH];
428 struct cpufreq_policy policy;
430 /*Verify that all the clip cpus have same freq_min, freq_max limit*/
431 for_each_cpu(i, clip_cpus) {
432 /*continue if cpufreq policy not found and not return error*/
433 if (!cpufreq_get_policy(&policy, i))
435 if (min == 0 && max == 0) {
436 min = policy.cpuinfo.min_freq;
437 max = policy.cpuinfo.max_freq;
439 if (min != policy.cpuinfo.min_freq ||
440 max != policy.cpuinfo.max_freq)
441 return ERR_PTR(-EINVAL);
444 cpufreq_dev = kzalloc(sizeof(struct cpufreq_cooling_device),
447 return ERR_PTR(-ENOMEM);
449 cpumask_copy(&cpufreq_dev->allowed_cpus, clip_cpus);
451 ret = get_idr(&cpufreq_idr, &cpufreq_dev->id);
454 return ERR_PTR(-EINVAL);
457 snprintf(dev_name, sizeof(dev_name), "thermal-cpufreq-%d",
460 cool_dev = thermal_cooling_device_register(dev_name, cpufreq_dev,
461 &cpufreq_cooling_ops);
463 release_idr(&cpufreq_idr, cpufreq_dev->id);
465 return ERR_PTR(-EINVAL);
467 cpufreq_dev->cool_dev = cool_dev;
468 cpufreq_dev->cpufreq_state = 0;
469 mutex_lock(&cooling_cpufreq_lock);
471 /* Register the notifier for first cpufreq cooling device */
472 if (cpufreq_dev_count == 0)
473 cpufreq_register_notifier(&thermal_cpufreq_notifier_block,
474 CPUFREQ_POLICY_NOTIFIER);
477 mutex_unlock(&cooling_cpufreq_lock);
480 EXPORT_SYMBOL_GPL(cpufreq_cooling_register);
483 * cpufreq_cooling_unregister - function to remove cpufreq cooling device.
484 * @cdev: thermal cooling device pointer.
486 * This interface function unregisters the "thermal-cpufreq-%x" cooling device.
488 void cpufreq_cooling_unregister(struct thermal_cooling_device *cdev)
490 struct cpufreq_cooling_device *cpufreq_dev = cdev->devdata;
492 mutex_lock(&cooling_cpufreq_lock);
495 /* Unregister the notifier for the last cpufreq cooling device */
496 if (cpufreq_dev_count == 0)
497 cpufreq_unregister_notifier(&thermal_cpufreq_notifier_block,
498 CPUFREQ_POLICY_NOTIFIER);
500 mutex_unlock(&cooling_cpufreq_lock);
502 thermal_cooling_device_unregister(cpufreq_dev->cool_dev);
503 release_idr(&cpufreq_idr, cpufreq_dev->id);
506 EXPORT_SYMBOL_GPL(cpufreq_cooling_unregister);