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 * Cooling state <-> CPUFreq frequency
34 * Cooling states are translated to frequencies throughout this driver and this
35 * is the relation between them.
37 * Highest cooling state corresponds to lowest possible frequency.
40 * level 0 --> 1st Max Freq
41 * level 1 --> 2nd Max Freq
46 * struct cpufreq_cooling_device - data for cooling device with cpufreq
47 * @id: unique integer value corresponding to each cpufreq_cooling_device
49 * @cool_dev: thermal_cooling_device pointer to keep track of the
50 * registered cooling device.
51 * @cpufreq_state: integer value representing the current state of cpufreq
53 * @cpufreq_val: integer value representing the absolute value of the clipped
55 * @allowed_cpus: all the cpus involved for this cpufreq_cooling_device.
57 * This structure is required for keeping information of each registered
58 * cpufreq_cooling_device.
60 struct cpufreq_cooling_device {
62 struct thermal_cooling_device *cool_dev;
63 unsigned int cpufreq_state;
64 unsigned int cpufreq_val;
65 struct cpumask allowed_cpus;
66 struct list_head node;
68 static DEFINE_IDR(cpufreq_idr);
69 static DEFINE_MUTEX(cooling_cpufreq_lock);
71 static unsigned int cpufreq_dev_count;
73 static LIST_HEAD(cpufreq_dev_list);
76 * get_idr - function to get a unique id.
77 * @idr: struct idr * handle used to create a id.
78 * @id: int * value generated by this function.
80 * This function will populate @id with an unique
81 * id, using the idr API.
83 * Return: 0 on success, an error code on failure.
85 static int get_idr(struct idr *idr, int *id)
89 mutex_lock(&cooling_cpufreq_lock);
90 ret = idr_alloc(idr, NULL, 0, 0, GFP_KERNEL);
91 mutex_unlock(&cooling_cpufreq_lock);
92 if (unlikely(ret < 0))
100 * release_idr - function to free the unique id.
101 * @idr: struct idr * handle used for creating the id.
102 * @id: int value representing the unique id.
104 static void release_idr(struct idr *idr, int id)
106 mutex_lock(&cooling_cpufreq_lock);
108 mutex_unlock(&cooling_cpufreq_lock);
111 /* Below code defines functions to be used for cpufreq as cooling device */
114 * is_cpufreq_valid - function to check frequency transitioning capability.
115 * @cpu: cpu for which check is needed.
117 * This function will check the current state of the system if
118 * it is capable of changing the frequency for a given @cpu.
120 * Return: 0 if the system is not currently capable of changing
121 * the frequency of given cpu. !0 in case the frequency is changeable.
123 static int is_cpufreq_valid(int cpu)
125 struct cpufreq_policy policy;
127 return !cpufreq_get_policy(&policy, cpu);
130 enum cpufreq_cooling_property {
137 * get_property - fetch a property of interest for a given cpu.
138 * @cpu: cpu for which the property is required
139 * @input: query parameter
140 * @output: query return
141 * @property: type of query (frequency, level, max level)
143 * This is the common function to
144 * 1. get maximum cpu cooling states
145 * 2. translate frequency to cooling state
146 * 3. translate cooling state to frequency
148 * Note that the code may be not in good shape
149 * but it is written in this way in order to:
150 * a) reduce duplicate code as most of the code can be shared.
151 * b) make sure the logic is consistent when translating between
152 * cooling states and frequencies.
154 * Return: 0 on success, -EINVAL when invalid parameters are passed.
156 static int get_property(unsigned int cpu, unsigned long input,
157 unsigned int *output,
158 enum cpufreq_cooling_property property)
161 unsigned long max_level = 0, level = 0;
162 unsigned int freq = CPUFREQ_ENTRY_INVALID;
164 struct cpufreq_frequency_table *pos, *table =
165 cpufreq_frequency_get_table(cpu);
173 cpufreq_for_each_valid_entry(pos, table) {
174 /* ignore duplicate entry */
175 if (freq == pos->frequency)
178 /* get the frequency order */
179 if (freq != CPUFREQ_ENTRY_INVALID && descend == -1)
180 descend = freq > pos->frequency;
182 freq = pos->frequency;
186 /* No valid cpu frequency entry */
190 /* max_level is an index, not a counter */
194 if (property == GET_MAXL) {
195 *output = (unsigned int)max_level;
199 if (property == GET_FREQ)
200 level = descend ? input : (max_level - input);
203 cpufreq_for_each_valid_entry(pos, table) {
204 /* ignore duplicate entry */
205 if (freq == pos->frequency)
208 /* now we have a valid frequency entry */
209 freq = pos->frequency;
211 if (property == GET_LEVEL && (unsigned int)input == freq) {
212 /* get level by frequency */
213 *output = descend ? i : (max_level - i);
216 if (property == GET_FREQ && level == i) {
217 /* get frequency by level */
228 * cpufreq_cooling_get_level - for a given cpu, return the cooling level.
229 * @cpu: cpu for which the level is required
230 * @freq: the frequency of interest
232 * This function will match the cooling level corresponding to the
233 * requested @freq and return it.
235 * Return: The matched cooling level on success or THERMAL_CSTATE_INVALID
238 unsigned long cpufreq_cooling_get_level(unsigned int cpu, unsigned int freq)
242 if (get_property(cpu, (unsigned long)freq, &val, GET_LEVEL))
243 return THERMAL_CSTATE_INVALID;
245 return (unsigned long)val;
247 EXPORT_SYMBOL_GPL(cpufreq_cooling_get_level);
250 * get_cpu_frequency - get the absolute value of frequency from level.
251 * @cpu: cpu for which frequency is fetched.
252 * @level: cooling level
254 * This function matches cooling level with frequency. Based on a cooling level
255 * of frequency, equals cooling state of cpu cooling device, it will return
256 * the corresponding frequency.
257 * e.g level=0 --> 1st MAX FREQ, level=1 ---> 2nd MAX FREQ, .... etc
259 * Return: 0 on error, the corresponding frequency otherwise.
261 static unsigned int get_cpu_frequency(unsigned int cpu, unsigned long level)
266 ret = get_property(cpu, level, &freq, GET_FREQ);
274 * cpufreq_apply_cooling - function to apply frequency clipping.
275 * @cpufreq_device: cpufreq_cooling_device pointer containing frequency
277 * @cooling_state: value of the cooling state.
279 * Function used to make sure the cpufreq layer is aware of current thermal
280 * limits. The limits are applied by updating the cpufreq policy.
282 * Return: 0 on success, an error code otherwise (-EINVAL in case wrong
285 static int cpufreq_apply_cooling(struct cpufreq_cooling_device *cpufreq_device,
286 unsigned long cooling_state)
288 unsigned int cpuid, clip_freq;
289 struct cpumask *mask = &cpufreq_device->allowed_cpus;
290 unsigned int cpu = cpumask_any(mask);
293 /* Check if the old cooling action is same as new cooling action */
294 if (cpufreq_device->cpufreq_state == cooling_state)
297 clip_freq = get_cpu_frequency(cpu, cooling_state);
301 cpufreq_device->cpufreq_state = cooling_state;
302 cpufreq_device->cpufreq_val = clip_freq;
304 for_each_cpu(cpuid, mask) {
305 if (is_cpufreq_valid(cpuid))
306 cpufreq_update_policy(cpuid);
313 * cpufreq_thermal_notifier - notifier callback for cpufreq policy change.
314 * @nb: struct notifier_block * with callback info.
315 * @event: value showing cpufreq event for which this function invoked.
316 * @data: callback-specific data
318 * Callback to hijack the notification on cpufreq policy transition.
319 * Every time there is a change in policy, we will intercept and
320 * update the cpufreq policy with thermal constraints.
322 * Return: 0 (success)
324 static int cpufreq_thermal_notifier(struct notifier_block *nb,
325 unsigned long event, void *data)
327 struct cpufreq_policy *policy = data;
328 unsigned long max_freq = 0;
329 struct cpufreq_cooling_device *cpufreq_dev;
331 if (event != CPUFREQ_ADJUST)
334 mutex_lock(&cooling_cpufreq_lock);
335 list_for_each_entry(cpufreq_dev, &cpufreq_dev_list, node) {
336 if (!cpumask_test_cpu(policy->cpu,
337 &cpufreq_dev->allowed_cpus))
340 if (!cpufreq_dev->cpufreq_val)
341 cpufreq_dev->cpufreq_val = get_cpu_frequency(
342 cpumask_any(&cpufreq_dev->allowed_cpus),
343 cpufreq_dev->cpufreq_state);
345 max_freq = cpufreq_dev->cpufreq_val;
347 if (policy->max != max_freq)
348 cpufreq_verify_within_limits(policy, 0, max_freq);
350 mutex_unlock(&cooling_cpufreq_lock);
355 /* cpufreq cooling device callback functions are defined below */
358 * cpufreq_get_max_state - callback function to get the max cooling state.
359 * @cdev: thermal cooling device pointer.
360 * @state: fill this variable with the max cooling state.
362 * Callback for the thermal cooling device to return the cpufreq
365 * Return: 0 on success, an error code otherwise.
367 static int cpufreq_get_max_state(struct thermal_cooling_device *cdev,
368 unsigned long *state)
370 struct cpufreq_cooling_device *cpufreq_device = cdev->devdata;
371 struct cpumask *mask = &cpufreq_device->allowed_cpus;
373 unsigned int count = 0;
376 cpu = cpumask_any(mask);
378 ret = get_property(cpu, 0, &count, GET_MAXL);
387 * cpufreq_get_cur_state - callback function to get the current cooling state.
388 * @cdev: thermal cooling device pointer.
389 * @state: fill this variable with the current cooling state.
391 * Callback for the thermal cooling device to return the cpufreq
392 * current cooling state.
394 * Return: 0 on success, an error code otherwise.
396 static int cpufreq_get_cur_state(struct thermal_cooling_device *cdev,
397 unsigned long *state)
399 struct cpufreq_cooling_device *cpufreq_device = cdev->devdata;
401 *state = cpufreq_device->cpufreq_state;
407 * cpufreq_set_cur_state - callback function to set the current cooling state.
408 * @cdev: thermal cooling device pointer.
409 * @state: set this variable to the current cooling state.
411 * Callback for the thermal cooling device to change the cpufreq
412 * current cooling state.
414 * Return: 0 on success, an error code otherwise.
416 static int cpufreq_set_cur_state(struct thermal_cooling_device *cdev,
419 struct cpufreq_cooling_device *cpufreq_device = cdev->devdata;
421 return cpufreq_apply_cooling(cpufreq_device, state);
424 /* Bind cpufreq callbacks to thermal cooling device ops */
425 static struct thermal_cooling_device_ops const cpufreq_cooling_ops = {
426 .get_max_state = cpufreq_get_max_state,
427 .get_cur_state = cpufreq_get_cur_state,
428 .set_cur_state = cpufreq_set_cur_state,
431 /* Notifier for cpufreq policy change */
432 static struct notifier_block thermal_cpufreq_notifier_block = {
433 .notifier_call = cpufreq_thermal_notifier,
437 * __cpufreq_cooling_register - helper function to create cpufreq cooling device
438 * @np: a valid struct device_node to the cooling device device tree node
439 * @clip_cpus: cpumask of cpus where the frequency constraints will happen.
441 * This interface function registers the cpufreq cooling device with the name
442 * "thermal-cpufreq-%x". This api can support multiple instances of cpufreq
443 * cooling devices. It also gives the opportunity to link the cooling device
444 * with a device tree node, in order to bind it via the thermal DT code.
446 * Return: a valid struct thermal_cooling_device pointer on success,
447 * on failure, it returns a corresponding ERR_PTR().
449 static struct thermal_cooling_device *
450 __cpufreq_cooling_register(struct device_node *np,
451 const struct cpumask *clip_cpus)
453 struct thermal_cooling_device *cool_dev;
454 struct cpufreq_cooling_device *cpufreq_dev;
455 unsigned int min = 0, max = 0;
456 char dev_name[THERMAL_NAME_LENGTH];
458 struct cpufreq_policy policy;
460 if (!cpufreq_frequency_get_table(cpumask_first(clip_cpus))) {
461 pr_debug("%s: CPUFreq table not found\n", __func__);
462 return ERR_PTR(-EPROBE_DEFER);
465 /* Verify that all the clip cpus have same freq_min, freq_max limit */
466 for_each_cpu(i, clip_cpus) {
467 /* continue if cpufreq policy not found and not return error */
468 if (!cpufreq_get_policy(&policy, i))
470 if (min == 0 && max == 0) {
471 min = policy.cpuinfo.min_freq;
472 max = policy.cpuinfo.max_freq;
474 if (min != policy.cpuinfo.min_freq ||
475 max != policy.cpuinfo.max_freq)
476 return ERR_PTR(-EINVAL);
479 cpufreq_dev = kzalloc(sizeof(*cpufreq_dev), GFP_KERNEL);
481 return ERR_PTR(-ENOMEM);
483 cpumask_copy(&cpufreq_dev->allowed_cpus, clip_cpus);
485 ret = get_idr(&cpufreq_idr, &cpufreq_dev->id);
488 return ERR_PTR(-EINVAL);
491 snprintf(dev_name, sizeof(dev_name), "thermal-cpufreq-%d",
494 cool_dev = thermal_of_cooling_device_register(np, dev_name, cpufreq_dev,
495 &cpufreq_cooling_ops);
496 if (IS_ERR(cool_dev)) {
497 release_idr(&cpufreq_idr, cpufreq_dev->id);
501 cpufreq_dev->cool_dev = cool_dev;
503 mutex_lock(&cooling_cpufreq_lock);
505 /* Register the notifier for first cpufreq cooling device */
506 if (cpufreq_dev_count == 0)
507 cpufreq_register_notifier(&thermal_cpufreq_notifier_block,
508 CPUFREQ_POLICY_NOTIFIER);
510 list_add(&cpufreq_dev->node, &cpufreq_dev_list);
512 mutex_unlock(&cooling_cpufreq_lock);
518 * cpufreq_cooling_register - function to create cpufreq cooling device.
519 * @clip_cpus: cpumask of cpus where the frequency constraints will happen.
521 * This interface function registers the cpufreq cooling device with the name
522 * "thermal-cpufreq-%x". This api can support multiple instances of cpufreq
525 * Return: a valid struct thermal_cooling_device pointer on success,
526 * on failure, it returns a corresponding ERR_PTR().
528 struct thermal_cooling_device *
529 cpufreq_cooling_register(const struct cpumask *clip_cpus)
531 return __cpufreq_cooling_register(NULL, clip_cpus);
533 EXPORT_SYMBOL_GPL(cpufreq_cooling_register);
536 * of_cpufreq_cooling_register - function to create cpufreq cooling device.
537 * @np: a valid struct device_node to the cooling device device tree node
538 * @clip_cpus: cpumask of cpus where the frequency constraints will happen.
540 * This interface function registers the cpufreq cooling device with the name
541 * "thermal-cpufreq-%x". This api can support multiple instances of cpufreq
542 * cooling devices. Using this API, the cpufreq cooling device will be
543 * linked to the device tree node provided.
545 * Return: a valid struct thermal_cooling_device pointer on success,
546 * on failure, it returns a corresponding ERR_PTR().
548 struct thermal_cooling_device *
549 of_cpufreq_cooling_register(struct device_node *np,
550 const struct cpumask *clip_cpus)
553 return ERR_PTR(-EINVAL);
555 return __cpufreq_cooling_register(np, clip_cpus);
557 EXPORT_SYMBOL_GPL(of_cpufreq_cooling_register);
560 * cpufreq_cooling_unregister - function to remove cpufreq cooling device.
561 * @cdev: thermal cooling device pointer.
563 * This interface function unregisters the "thermal-cpufreq-%x" cooling device.
565 void cpufreq_cooling_unregister(struct thermal_cooling_device *cdev)
567 struct cpufreq_cooling_device *cpufreq_dev;
572 cpufreq_dev = cdev->devdata;
573 mutex_lock(&cooling_cpufreq_lock);
574 list_del(&cpufreq_dev->node);
577 /* Unregister the notifier for the last cpufreq cooling device */
578 if (cpufreq_dev_count == 0)
579 cpufreq_unregister_notifier(&thermal_cpufreq_notifier_block,
580 CPUFREQ_POLICY_NOTIFIER);
581 mutex_unlock(&cooling_cpufreq_lock);
583 thermal_cooling_device_unregister(cpufreq_dev->cool_dev);
584 release_idr(&cpufreq_idr, cpufreq_dev->id);
587 EXPORT_SYMBOL_GPL(cpufreq_cooling_unregister);