Root/drivers/thermal/cpu_cooling.c

1/*
2 * linux/drivers/thermal/cpu_cooling.c
3 *
4 * Copyright (C) 2012 Samsung Electronics Co., Ltd(http://www.samsung.com)
5 * Copyright (C) 2012 Amit Daniel <amit.kachhap@linaro.org>
6 *
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.
11 *
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.
16 *
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.
20 *
21 * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
22 */
23#include <linux/kernel.h>
24#include <linux/module.h>
25#include <linux/thermal.h>
26#include <linux/platform_device.h>
27#include <linux/cpufreq.h>
28#include <linux/err.h>
29#include <linux/slab.h>
30#include <linux/cpu.h>
31#include <linux/cpu_cooling.h>
32
33/**
34 * struct cpufreq_cooling_device
35 * @id: unique integer value corresponding to each cpufreq_cooling_device
36 * registered.
37 * @cool_dev: thermal_cooling_device pointer to keep track of the the
38 * egistered cooling device.
39 * @cpufreq_state: integer value representing the current state of cpufreq
40 * cooling devices.
41 * @cpufreq_val: integer value representing the absolute value of the clipped
42 * frequency.
43 * @allowed_cpus: all the cpus involved for this cpufreq_cooling_device.
44 * @node: list_head to link all cpufreq_cooling_device together.
45 *
46 * This structure is required for keeping information of each
47 * cpufreq_cooling_device registered as a list whose head is represented by
48 * cooling_cpufreq_list. In order to prevent corruption of this list a
49 * mutex lock cooling_cpufreq_lock is used.
50 */
51struct cpufreq_cooling_device {
52    int id;
53    struct thermal_cooling_device *cool_dev;
54    unsigned int cpufreq_state;
55    unsigned int cpufreq_val;
56    struct cpumask allowed_cpus;
57    struct list_head node;
58};
59static LIST_HEAD(cooling_cpufreq_list);
60static DEFINE_IDR(cpufreq_idr);
61static DEFINE_MUTEX(cooling_cpufreq_lock);
62
63static unsigned int cpufreq_dev_count;
64
65/* notify_table passes value to the CPUFREQ_ADJUST callback function. */
66#define NOTIFY_INVALID NULL
67static struct cpufreq_cooling_device *notify_device;
68
69/**
70 * get_idr - function to get a unique id.
71 * @idr: struct idr * handle used to create a id.
72 * @id: int * value generated by this function.
73 */
74static int get_idr(struct idr *idr, int *id)
75{
76    int ret;
77
78    mutex_lock(&cooling_cpufreq_lock);
79    ret = idr_alloc(idr, NULL, 0, 0, GFP_KERNEL);
80    mutex_unlock(&cooling_cpufreq_lock);
81    if (unlikely(ret < 0))
82        return ret;
83    *id = ret;
84    return 0;
85}
86
87/**
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.
91 */
92static void release_idr(struct idr *idr, int id)
93{
94    mutex_lock(&cooling_cpufreq_lock);
95    idr_remove(idr, id);
96    mutex_unlock(&cooling_cpufreq_lock);
97}
98
99/* Below code defines functions to be used for cpufreq as cooling device */
100
101/**
102 * is_cpufreq_valid - function to check if a cpu has frequency transition policy.
103 * @cpu: cpu for which check is needed.
104 */
105static int is_cpufreq_valid(int cpu)
106{
107    struct cpufreq_policy policy;
108    return !cpufreq_get_policy(&policy, cpu);
109}
110
111/**
112 * get_cpu_frequency - get the absolute value of frequency from level.
113 * @cpu: cpu for which frequency is fetched.
114 * @level: level of frequency, equals cooling state of cpu cooling device
115 * e.g level=0 --> 1st MAX FREQ, level=1 ---> 2nd MAX FREQ, .... etc
116 */
117static unsigned int get_cpu_frequency(unsigned int cpu, unsigned long level)
118{
119    int ret = 0, i = 0;
120    unsigned long level_index;
121    bool descend = false;
122    struct cpufreq_frequency_table *table =
123                    cpufreq_frequency_get_table(cpu);
124    if (!table)
125        return ret;
126
127    while (table[i].frequency != CPUFREQ_TABLE_END) {
128        if (table[i].frequency == CPUFREQ_ENTRY_INVALID)
129            continue;
130
131        /*check if table in ascending or descending order*/
132        if ((table[i + 1].frequency != CPUFREQ_TABLE_END) &&
133            (table[i + 1].frequency < table[i].frequency)
134            && !descend) {
135            descend = true;
136        }
137
138        /*return if level matched and table in descending order*/
139        if (descend && i == level)
140            return table[i].frequency;
141        i++;
142    }
143    i--;
144
145    if (level > i || descend)
146        return ret;
147    level_index = i - level;
148
149    /*Scan the table in reverse order and match the level*/
150    while (i >= 0) {
151        if (table[i].frequency == CPUFREQ_ENTRY_INVALID)
152            continue;
153        /*return if level matched*/
154        if (i == level_index)
155            return table[i].frequency;
156        i--;
157    }
158    return ret;
159}
160
161/**
162 * cpufreq_apply_cooling - function to apply frequency clipping.
163 * @cpufreq_device: cpufreq_cooling_device pointer containing frequency
164 * clipping data.
165 * @cooling_state: value of the cooling state.
166 */
167static int cpufreq_apply_cooling(struct cpufreq_cooling_device *cpufreq_device,
168                unsigned long cooling_state)
169{
170    unsigned int cpuid, clip_freq;
171    struct cpumask *maskPtr = &cpufreq_device->allowed_cpus;
172    unsigned int cpu = cpumask_any(maskPtr);
173
174
175    /* Check if the old cooling action is same as new cooling action */
176    if (cpufreq_device->cpufreq_state == cooling_state)
177        return 0;
178
179    clip_freq = get_cpu_frequency(cpu, cooling_state);
180    if (!clip_freq)
181        return -EINVAL;
182
183    cpufreq_device->cpufreq_state = cooling_state;
184    cpufreq_device->cpufreq_val = clip_freq;
185    notify_device = cpufreq_device;
186
187    for_each_cpu(cpuid, maskPtr) {
188        if (is_cpufreq_valid(cpuid))
189            cpufreq_update_policy(cpuid);
190    }
191
192    notify_device = NOTIFY_INVALID;
193
194    return 0;
195}
196
197/**
198 * cpufreq_thermal_notifier - notifier callback for cpufreq policy change.
199 * @nb: struct notifier_block * with callback info.
200 * @event: value showing cpufreq event for which this function invoked.
201 * @data: callback-specific data
202 */
203static int cpufreq_thermal_notifier(struct notifier_block *nb,
204                    unsigned long event, void *data)
205{
206    struct cpufreq_policy *policy = data;
207    unsigned long max_freq = 0;
208
209    if (event != CPUFREQ_ADJUST || notify_device == NOTIFY_INVALID)
210        return 0;
211
212    if (cpumask_test_cpu(policy->cpu, &notify_device->allowed_cpus))
213        max_freq = notify_device->cpufreq_val;
214
215    /* Never exceed user_policy.max*/
216    if (max_freq > policy->user_policy.max)
217        max_freq = policy->user_policy.max;
218
219    if (policy->max != max_freq)
220        cpufreq_verify_within_limits(policy, 0, max_freq);
221
222    return 0;
223}
224
225/*
226 * cpufreq cooling device callback functions are defined below
227 */
228
229/**
230 * cpufreq_get_max_state - callback function to get the max cooling state.
231 * @cdev: thermal cooling device pointer.
232 * @state: fill this variable with the max cooling state.
233 */
234static int cpufreq_get_max_state(struct thermal_cooling_device *cdev,
235                 unsigned long *state)
236{
237    struct cpufreq_cooling_device *cpufreq_device = cdev->devdata;
238    struct cpumask *maskPtr = &cpufreq_device->allowed_cpus;
239    unsigned int cpu;
240    struct cpufreq_frequency_table *table;
241    unsigned long count = 0;
242    int i = 0;
243
244    cpu = cpumask_any(maskPtr);
245    table = cpufreq_frequency_get_table(cpu);
246    if (!table) {
247        *state = 0;
248        return 0;
249    }
250
251    for (i = 0; (table[i].frequency != CPUFREQ_TABLE_END); i++) {
252        if (table[i].frequency == CPUFREQ_ENTRY_INVALID)
253            continue;
254        count++;
255    }
256
257    if (count > 0) {
258        *state = --count;
259        return 0;
260    }
261
262    return -EINVAL;
263}
264
265/**
266 * cpufreq_get_cur_state - callback function to get the current cooling state.
267 * @cdev: thermal cooling device pointer.
268 * @state: fill this variable with the current cooling state.
269 */
270static int cpufreq_get_cur_state(struct thermal_cooling_device *cdev,
271                 unsigned long *state)
272{
273    struct cpufreq_cooling_device *cpufreq_device = cdev->devdata;
274
275    *state = cpufreq_device->cpufreq_state;
276    return 0;
277}
278
279/**
280 * cpufreq_set_cur_state - callback function to set the current cooling state.
281 * @cdev: thermal cooling device pointer.
282 * @state: set this variable to the current cooling state.
283 */
284static int cpufreq_set_cur_state(struct thermal_cooling_device *cdev,
285                 unsigned long state)
286{
287    struct cpufreq_cooling_device *cpufreq_device = cdev->devdata;
288
289    return cpufreq_apply_cooling(cpufreq_device, state);
290}
291
292/* Bind cpufreq callbacks to thermal cooling device ops */
293static struct thermal_cooling_device_ops const cpufreq_cooling_ops = {
294    .get_max_state = cpufreq_get_max_state,
295    .get_cur_state = cpufreq_get_cur_state,
296    .set_cur_state = cpufreq_set_cur_state,
297};
298
299/* Notifier for cpufreq policy change */
300static struct notifier_block thermal_cpufreq_notifier_block = {
301    .notifier_call = cpufreq_thermal_notifier,
302};
303
304/**
305 * cpufreq_cooling_register - function to create cpufreq cooling device.
306 * @clip_cpus: cpumask of cpus where the frequency constraints will happen.
307 */
308struct thermal_cooling_device *cpufreq_cooling_register(
309    const struct cpumask *clip_cpus)
310{
311    struct thermal_cooling_device *cool_dev;
312    struct cpufreq_cooling_device *cpufreq_dev = NULL;
313    unsigned int min = 0, max = 0;
314    char dev_name[THERMAL_NAME_LENGTH];
315    int ret = 0, i;
316    struct cpufreq_policy policy;
317
318    /*Verify that all the clip cpus have same freq_min, freq_max limit*/
319    for_each_cpu(i, clip_cpus) {
320        /*continue if cpufreq policy not found and not return error*/
321        if (!cpufreq_get_policy(&policy, i))
322            continue;
323        if (min == 0 && max == 0) {
324            min = policy.cpuinfo.min_freq;
325            max = policy.cpuinfo.max_freq;
326        } else {
327            if (min != policy.cpuinfo.min_freq ||
328                max != policy.cpuinfo.max_freq)
329                return ERR_PTR(-EINVAL);
330        }
331    }
332    cpufreq_dev = kzalloc(sizeof(struct cpufreq_cooling_device),
333            GFP_KERNEL);
334    if (!cpufreq_dev)
335        return ERR_PTR(-ENOMEM);
336
337    cpumask_copy(&cpufreq_dev->allowed_cpus, clip_cpus);
338
339    ret = get_idr(&cpufreq_idr, &cpufreq_dev->id);
340    if (ret) {
341        kfree(cpufreq_dev);
342        return ERR_PTR(-EINVAL);
343    }
344
345    sprintf(dev_name, "thermal-cpufreq-%d", cpufreq_dev->id);
346
347    cool_dev = thermal_cooling_device_register(dev_name, cpufreq_dev,
348                        &cpufreq_cooling_ops);
349    if (!cool_dev) {
350        release_idr(&cpufreq_idr, cpufreq_dev->id);
351        kfree(cpufreq_dev);
352        return ERR_PTR(-EINVAL);
353    }
354    cpufreq_dev->cool_dev = cool_dev;
355    cpufreq_dev->cpufreq_state = 0;
356    mutex_lock(&cooling_cpufreq_lock);
357
358    /* Register the notifier for first cpufreq cooling device */
359    if (cpufreq_dev_count == 0)
360        cpufreq_register_notifier(&thermal_cpufreq_notifier_block,
361                        CPUFREQ_POLICY_NOTIFIER);
362    cpufreq_dev_count++;
363
364    mutex_unlock(&cooling_cpufreq_lock);
365    return cool_dev;
366}
367EXPORT_SYMBOL(cpufreq_cooling_register);
368
369/**
370 * cpufreq_cooling_unregister - function to remove cpufreq cooling device.
371 * @cdev: thermal cooling device pointer.
372 */
373void cpufreq_cooling_unregister(struct thermal_cooling_device *cdev)
374{
375    struct cpufreq_cooling_device *cpufreq_dev = cdev->devdata;
376
377    mutex_lock(&cooling_cpufreq_lock);
378    cpufreq_dev_count--;
379
380    /* Unregister the notifier for the last cpufreq cooling device */
381    if (cpufreq_dev_count == 0) {
382        cpufreq_unregister_notifier(&thermal_cpufreq_notifier_block,
383                    CPUFREQ_POLICY_NOTIFIER);
384    }
385    mutex_unlock(&cooling_cpufreq_lock);
386
387    thermal_cooling_device_unregister(cpufreq_dev->cool_dev);
388    release_idr(&cpufreq_idr, cpufreq_dev->id);
389    kfree(cpufreq_dev);
390}
391EXPORT_SYMBOL(cpufreq_cooling_unregister);
392

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