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 * 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 *table =
152 cpufreq_frequency_get_table(cpu);
160 for (i = 0; table[i].frequency != CPUFREQ_TABLE_END; i++) {
161 /* ignore invalid entries */
162 if (table[i].frequency == CPUFREQ_ENTRY_INVALID)
165 /* ignore duplicate entry */
166 if (freq == table[i].frequency)
169 /* get the frequency order */
170 if (freq != CPUFREQ_ENTRY_INVALID && descend != -1)
171 descend = !!(freq > table[i].frequency);
173 freq = table[i].frequency;
178 if (property == GET_MAXL) {
179 *output = (unsigned int)max_level;
183 if (property == GET_FREQ)
184 level = descend ? input : (max_level - input -1);
187 for (i = 0, j = 0; table[i].frequency != CPUFREQ_TABLE_END; i++) {
188 /* ignore invalid entry */
189 if (table[i].frequency == CPUFREQ_ENTRY_INVALID)
192 /* ignore duplicate entry */
193 if (freq == table[i].frequency)
196 /* now we have a valid frequency entry */
197 freq = table[i].frequency;
199 if (property == GET_LEVEL && (unsigned int)input == freq) {
200 /* get level by frequency */
201 *output = descend ? j : (max_level - j - 1);
204 if (property == GET_FREQ && level == j) {
205 /* get frequency by level */
216 * cpufreq_cooling_get_level - for a give cpu, return the cooling level.
217 * @cpu: cpu for which the level is required
218 * @freq: the frequency of interest
220 * This function will match the cooling level corresponding to the
221 * requested @freq and return it.
223 * Return: The matched cooling level on success or THERMAL_CSTATE_INVALID
226 unsigned long cpufreq_cooling_get_level(unsigned int cpu, unsigned int freq)
230 if (get_property(cpu, (unsigned long)freq, &val, GET_LEVEL))
231 return THERMAL_CSTATE_INVALID;
233 return (unsigned long)val;
235 EXPORT_SYMBOL_GPL(cpufreq_cooling_get_level);
238 * get_cpu_frequency - get the absolute value of frequency from level.
239 * @cpu: cpu for which frequency is fetched.
240 * @level: cooling level
242 * This function matches cooling level with frequency. Based on a cooling level
243 * of frequency, equals cooling state of cpu cooling device, it will return
244 * the corresponding frequency.
245 * e.g level=0 --> 1st MAX FREQ, level=1 ---> 2nd MAX FREQ, .... etc
247 * Return: 0 on error, the corresponding frequency otherwise.
249 static unsigned int get_cpu_frequency(unsigned int cpu, unsigned long level)
254 ret = get_property(cpu, level, &freq, GET_FREQ);
262 * cpufreq_apply_cooling - function to apply frequency clipping.
263 * @cpufreq_device: cpufreq_cooling_device pointer containing frequency
265 * @cooling_state: value of the cooling state.
267 * Function used to make sure the cpufreq layer is aware of current thermal
268 * limits. The limits are applied by updating the cpufreq policy.
270 * Return: 0 on success, an error code otherwise (-EINVAL in case wrong
273 static int cpufreq_apply_cooling(struct cpufreq_cooling_device *cpufreq_device,
274 unsigned long cooling_state)
276 unsigned int cpuid, clip_freq;
277 struct cpumask *mask = &cpufreq_device->allowed_cpus;
278 unsigned int cpu = cpumask_any(mask);
281 /* Check if the old cooling action is same as new cooling action */
282 if (cpufreq_device->cpufreq_state == cooling_state)
285 clip_freq = get_cpu_frequency(cpu, cooling_state);
289 cpufreq_device->cpufreq_state = cooling_state;
290 cpufreq_device->cpufreq_val = clip_freq;
291 notify_device = cpufreq_device;
293 for_each_cpu(cpuid, mask) {
294 if (is_cpufreq_valid(cpuid))
295 cpufreq_update_policy(cpuid);
298 notify_device = NOTIFY_INVALID;
304 * cpufreq_thermal_notifier - notifier callback for cpufreq policy change.
305 * @nb: struct notifier_block * with callback info.
306 * @event: value showing cpufreq event for which this function invoked.
307 * @data: callback-specific data
309 * Callback to highjack the notification on cpufreq policy transition.
310 * Every time there is a change in policy, we will intercept and
311 * update the cpufreq policy with thermal constraints.
313 * Return: 0 (success)
315 static int cpufreq_thermal_notifier(struct notifier_block *nb,
316 unsigned long event, void *data)
318 struct cpufreq_policy *policy = data;
319 unsigned long max_freq = 0;
321 if (event != CPUFREQ_ADJUST || notify_device == NOTIFY_INVALID)
324 if (cpumask_test_cpu(policy->cpu, ¬ify_device->allowed_cpus))
325 max_freq = notify_device->cpufreq_val;
327 /* Never exceed user_policy.max */
328 if (max_freq > policy->user_policy.max)
329 max_freq = policy->user_policy.max;
331 if (policy->max != max_freq)
332 cpufreq_verify_within_limits(policy, 0, max_freq);
337 /* cpufreq cooling device callback functions are defined below */
340 * cpufreq_get_max_state - callback function to get the max cooling state.
341 * @cdev: thermal cooling device pointer.
342 * @state: fill this variable with the max cooling state.
344 * Callback for the thermal cooling device to return the cpufreq
347 * Return: 0 on success, an error code otherwise.
349 static int cpufreq_get_max_state(struct thermal_cooling_device *cdev,
350 unsigned long *state)
352 struct cpufreq_cooling_device *cpufreq_device = cdev->devdata;
353 struct cpumask *mask = &cpufreq_device->allowed_cpus;
355 unsigned int count = 0;
358 cpu = cpumask_any(mask);
360 ret = get_property(cpu, 0, &count, GET_MAXL);
369 * cpufreq_get_cur_state - callback function to get the current cooling state.
370 * @cdev: thermal cooling device pointer.
371 * @state: fill this variable with the current cooling state.
373 * Callback for the thermal cooling device to return the cpufreq
374 * current cooling state.
376 * Return: 0 on success, an error code otherwise.
378 static int cpufreq_get_cur_state(struct thermal_cooling_device *cdev,
379 unsigned long *state)
381 struct cpufreq_cooling_device *cpufreq_device = cdev->devdata;
383 *state = cpufreq_device->cpufreq_state;
389 * cpufreq_set_cur_state - callback function to set the current cooling state.
390 * @cdev: thermal cooling device pointer.
391 * @state: set this variable to the current cooling state.
393 * Callback for the thermal cooling device to change the cpufreq
394 * current cooling state.
396 * Return: 0 on success, an error code otherwise.
398 static int cpufreq_set_cur_state(struct thermal_cooling_device *cdev,
401 struct cpufreq_cooling_device *cpufreq_device = cdev->devdata;
403 return cpufreq_apply_cooling(cpufreq_device, state);
406 /* Bind cpufreq callbacks to thermal cooling device ops */
407 static struct thermal_cooling_device_ops const cpufreq_cooling_ops = {
408 .get_max_state = cpufreq_get_max_state,
409 .get_cur_state = cpufreq_get_cur_state,
410 .set_cur_state = cpufreq_set_cur_state,
413 /* Notifier for cpufreq policy change */
414 static struct notifier_block thermal_cpufreq_notifier_block = {
415 .notifier_call = cpufreq_thermal_notifier,
419 * cpufreq_cooling_register - function to create cpufreq cooling device.
420 * @clip_cpus: cpumask of cpus where the frequency constraints will happen.
422 * This interface function registers the cpufreq cooling device with the name
423 * "thermal-cpufreq-%x". This api can support multiple instances of cpufreq
426 * Return: a valid struct thermal_cooling_device pointer on success,
427 * on failure, it returns a corresponding ERR_PTR().
429 struct thermal_cooling_device *cpufreq_cooling_register(
430 const struct cpumask *clip_cpus)
432 struct thermal_cooling_device *cool_dev;
433 struct cpufreq_cooling_device *cpufreq_dev = NULL;
434 unsigned int min = 0, max = 0;
435 char dev_name[THERMAL_NAME_LENGTH];
437 struct cpufreq_policy policy;
439 /* Verify that all the clip cpus have same freq_min, freq_max limit */
440 for_each_cpu(i, clip_cpus) {
441 /* continue if cpufreq policy not found and not return error */
442 if (!cpufreq_get_policy(&policy, i))
444 if (min == 0 && max == 0) {
445 min = policy.cpuinfo.min_freq;
446 max = policy.cpuinfo.max_freq;
448 if (min != policy.cpuinfo.min_freq ||
449 max != policy.cpuinfo.max_freq)
450 return ERR_PTR(-EINVAL);
453 cpufreq_dev = kzalloc(sizeof(struct cpufreq_cooling_device),
456 return ERR_PTR(-ENOMEM);
458 cpumask_copy(&cpufreq_dev->allowed_cpus, clip_cpus);
460 ret = get_idr(&cpufreq_idr, &cpufreq_dev->id);
463 return ERR_PTR(-EINVAL);
466 snprintf(dev_name, sizeof(dev_name), "thermal-cpufreq-%d",
469 cool_dev = thermal_cooling_device_register(dev_name, cpufreq_dev,
470 &cpufreq_cooling_ops);
472 release_idr(&cpufreq_idr, cpufreq_dev->id);
474 return ERR_PTR(-EINVAL);
476 cpufreq_dev->cool_dev = cool_dev;
477 cpufreq_dev->cpufreq_state = 0;
478 mutex_lock(&cooling_cpufreq_lock);
480 /* Register the notifier for first cpufreq cooling device */
481 if (cpufreq_dev_count == 0)
482 cpufreq_register_notifier(&thermal_cpufreq_notifier_block,
483 CPUFREQ_POLICY_NOTIFIER);
486 mutex_unlock(&cooling_cpufreq_lock);
490 EXPORT_SYMBOL_GPL(cpufreq_cooling_register);
493 * cpufreq_cooling_unregister - function to remove cpufreq cooling device.
494 * @cdev: thermal cooling device pointer.
496 * This interface function unregisters the "thermal-cpufreq-%x" cooling device.
498 void cpufreq_cooling_unregister(struct thermal_cooling_device *cdev)
500 struct cpufreq_cooling_device *cpufreq_dev = cdev->devdata;
502 mutex_lock(&cooling_cpufreq_lock);
505 /* Unregister the notifier for the last cpufreq cooling device */
506 if (cpufreq_dev_count == 0)
507 cpufreq_unregister_notifier(&thermal_cpufreq_notifier_block,
508 CPUFREQ_POLICY_NOTIFIER);
510 mutex_unlock(&cooling_cpufreq_lock);
512 thermal_cooling_device_unregister(cpufreq_dev->cool_dev);
513 release_idr(&cpufreq_idr, cpufreq_dev->id);
516 EXPORT_SYMBOL_GPL(cpufreq_cooling_unregister);