linux/drivers/thermal/cpu_cooling.c
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   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);
  61
  62static struct mutex cooling_cpufreq_lock;
  63
  64/* notify_table passes value to the CPUFREQ_ADJUST callback function. */
  65#define NOTIFY_INVALID NULL
  66struct cpufreq_cooling_device *notify_device;
  67
  68/**
  69 * get_idr - function to get a unique id.
  70 * @idr: struct idr * handle used to create a id.
  71 * @id: int * value generated by this function.
  72 */
  73static int get_idr(struct idr *idr, int *id)
  74{
  75        int err;
  76again:
  77        if (unlikely(idr_pre_get(idr, GFP_KERNEL) == 0))
  78                return -ENOMEM;
  79
  80        mutex_lock(&cooling_cpufreq_lock);
  81        err = idr_get_new(idr, NULL, id);
  82        mutex_unlock(&cooling_cpufreq_lock);
  83
  84        if (unlikely(err == -EAGAIN))
  85                goto again;
  86        else if (unlikely(err))
  87                return err;
  88
  89        *id = *id & MAX_IDR_MASK;
  90        return 0;
  91}
  92
  93/**
  94 * release_idr - function to free the unique id.
  95 * @idr: struct idr * handle used for creating the id.
  96 * @id: int value representing the unique id.
  97 */
  98static void release_idr(struct idr *idr, int id)
  99{
 100        mutex_lock(&cooling_cpufreq_lock);
 101        idr_remove(idr, id);
 102        mutex_unlock(&cooling_cpufreq_lock);
 103}
 104
 105/* Below code defines functions to be used for cpufreq as cooling device */
 106
 107/**
 108 * is_cpufreq_valid - function to check if a cpu has frequency transition policy.
 109 * @cpu: cpu for which check is needed.
 110 */
 111static int is_cpufreq_valid(int cpu)
 112{
 113        struct cpufreq_policy policy;
 114        return !cpufreq_get_policy(&policy, cpu);
 115}
 116
 117/**
 118 * get_cpu_frequency - get the absolute value of frequency from level.
 119 * @cpu: cpu for which frequency is fetched.
 120 * @level: level of frequency of the CPU
 121 *      e.g level=1 --> 1st MAX FREQ, LEVEL=2 ---> 2nd MAX FREQ, .... etc
 122 */
 123static unsigned int get_cpu_frequency(unsigned int cpu, unsigned long level)
 124{
 125        int ret = 0, i = 0;
 126        unsigned long level_index;
 127        bool descend = false;
 128        struct cpufreq_frequency_table *table =
 129                                        cpufreq_frequency_get_table(cpu);
 130        if (!table)
 131                return ret;
 132
 133        while (table[i].frequency != CPUFREQ_TABLE_END) {
 134                if (table[i].frequency == CPUFREQ_ENTRY_INVALID)
 135                        continue;
 136
 137                /*check if table in ascending or descending order*/
 138                if ((table[i + 1].frequency != CPUFREQ_TABLE_END) &&
 139                        (table[i + 1].frequency < table[i].frequency)
 140                        && !descend) {
 141                        descend = true;
 142                }
 143
 144                /*return if level matched and table in descending order*/
 145                if (descend && i == level)
 146                        return table[i].frequency;
 147                i++;
 148        }
 149        i--;
 150
 151        if (level > i || descend)
 152                return ret;
 153        level_index = i - level;
 154
 155        /*Scan the table in reverse order and match the level*/
 156        while (i >= 0) {
 157                if (table[i].frequency == CPUFREQ_ENTRY_INVALID)
 158                        continue;
 159                /*return if level matched*/
 160                if (i == level_index)
 161                        return table[i].frequency;
 162                i--;
 163        }
 164        return ret;
 165}
 166
 167/**
 168 * cpufreq_apply_cooling - function to apply frequency clipping.
 169 * @cpufreq_device: cpufreq_cooling_device pointer containing frequency
 170 *      clipping data.
 171 * @cooling_state: value of the cooling state.
 172 */
 173static int cpufreq_apply_cooling(struct cpufreq_cooling_device *cpufreq_device,
 174                                unsigned long cooling_state)
 175{
 176        unsigned int cpuid, clip_freq;
 177        struct cpumask *maskPtr = &cpufreq_device->allowed_cpus;
 178        unsigned int cpu = cpumask_any(maskPtr);
 179
 180
 181        /* Check if the old cooling action is same as new cooling action */
 182        if (cpufreq_device->cpufreq_state == cooling_state)
 183                return 0;
 184
 185        clip_freq = get_cpu_frequency(cpu, cooling_state);
 186        if (!clip_freq)
 187                return -EINVAL;
 188
 189        cpufreq_device->cpufreq_state = cooling_state;
 190        cpufreq_device->cpufreq_val = clip_freq;
 191        notify_device = cpufreq_device;
 192
 193        for_each_cpu(cpuid, maskPtr) {
 194                if (is_cpufreq_valid(cpuid))
 195                        cpufreq_update_policy(cpuid);
 196        }
 197
 198        notify_device = NOTIFY_INVALID;
 199
 200        return 0;
 201}
 202
 203/**
 204 * cpufreq_thermal_notifier - notifier callback for cpufreq policy change.
 205 * @nb: struct notifier_block * with callback info.
 206 * @event: value showing cpufreq event for which this function invoked.
 207 * @data: callback-specific data
 208 */
 209static int cpufreq_thermal_notifier(struct notifier_block *nb,
 210                                        unsigned long event, void *data)
 211{
 212        struct cpufreq_policy *policy = data;
 213        unsigned long max_freq = 0;
 214
 215        if (event != CPUFREQ_ADJUST || notify_device == NOTIFY_INVALID)
 216                return 0;
 217
 218        if (cpumask_test_cpu(policy->cpu, &notify_device->allowed_cpus))
 219                max_freq = notify_device->cpufreq_val;
 220
 221        /* Never exceed user_policy.max*/
 222        if (max_freq > policy->user_policy.max)
 223                max_freq = policy->user_policy.max;
 224
 225        if (policy->max != max_freq)
 226                cpufreq_verify_within_limits(policy, 0, max_freq);
 227
 228        return 0;
 229}
 230
 231/*
 232 * cpufreq cooling device callback functions are defined below
 233 */
 234
 235/**
 236 * cpufreq_get_max_state - callback function to get the max cooling state.
 237 * @cdev: thermal cooling device pointer.
 238 * @state: fill this variable with the max cooling state.
 239 */
 240static int cpufreq_get_max_state(struct thermal_cooling_device *cdev,
 241                                 unsigned long *state)
 242{
 243        int ret = -EINVAL, i = 0;
 244        struct cpufreq_cooling_device *cpufreq_device;
 245        struct cpumask *maskPtr;
 246        unsigned int cpu;
 247        struct cpufreq_frequency_table *table;
 248
 249        mutex_lock(&cooling_cpufreq_lock);
 250        list_for_each_entry(cpufreq_device, &cooling_cpufreq_list, node) {
 251                if (cpufreq_device && cpufreq_device->cool_dev == cdev)
 252                        break;
 253        }
 254        if (cpufreq_device == NULL)
 255                goto return_get_max_state;
 256
 257        maskPtr = &cpufreq_device->allowed_cpus;
 258        cpu = cpumask_any(maskPtr);
 259        table = cpufreq_frequency_get_table(cpu);
 260        if (!table) {
 261                *state = 0;
 262                ret = 0;
 263                goto return_get_max_state;
 264        }
 265
 266        while (table[i].frequency != CPUFREQ_TABLE_END) {
 267                if (table[i].frequency == CPUFREQ_ENTRY_INVALID)
 268                        continue;
 269                i++;
 270        }
 271        if (i > 0) {
 272                *state = --i;
 273                ret = 0;
 274        }
 275
 276return_get_max_state:
 277        mutex_unlock(&cooling_cpufreq_lock);
 278        return ret;
 279}
 280
 281/**
 282 * cpufreq_get_cur_state - callback function to get the current cooling state.
 283 * @cdev: thermal cooling device pointer.
 284 * @state: fill this variable with the current cooling state.
 285 */
 286static int cpufreq_get_cur_state(struct thermal_cooling_device *cdev,
 287                                 unsigned long *state)
 288{
 289        int ret = -EINVAL;
 290        struct cpufreq_cooling_device *cpufreq_device;
 291
 292        mutex_lock(&cooling_cpufreq_lock);
 293        list_for_each_entry(cpufreq_device, &cooling_cpufreq_list, node) {
 294                if (cpufreq_device && cpufreq_device->cool_dev == cdev) {
 295                        *state = cpufreq_device->cpufreq_state;
 296                        ret = 0;
 297                        break;
 298                }
 299        }
 300        mutex_unlock(&cooling_cpufreq_lock);
 301
 302        return ret;
 303}
 304
 305/**
 306 * cpufreq_set_cur_state - callback function to set the current cooling state.
 307 * @cdev: thermal cooling device pointer.
 308 * @state: set this variable to the current cooling state.
 309 */
 310static int cpufreq_set_cur_state(struct thermal_cooling_device *cdev,
 311                                 unsigned long state)
 312{
 313        int ret = -EINVAL;
 314        struct cpufreq_cooling_device *cpufreq_device;
 315
 316        mutex_lock(&cooling_cpufreq_lock);
 317        list_for_each_entry(cpufreq_device, &cooling_cpufreq_list, node) {
 318                if (cpufreq_device && cpufreq_device->cool_dev == cdev) {
 319                        ret = 0;
 320                        break;
 321                }
 322        }
 323        if (!ret)
 324                ret = cpufreq_apply_cooling(cpufreq_device, state);
 325
 326        mutex_unlock(&cooling_cpufreq_lock);
 327
 328        return ret;
 329}
 330
 331/* Bind cpufreq callbacks to thermal cooling device ops */
 332static struct thermal_cooling_device_ops const cpufreq_cooling_ops = {
 333        .get_max_state = cpufreq_get_max_state,
 334        .get_cur_state = cpufreq_get_cur_state,
 335        .set_cur_state = cpufreq_set_cur_state,
 336};
 337
 338/* Notifier for cpufreq policy change */
 339static struct notifier_block thermal_cpufreq_notifier_block = {
 340        .notifier_call = cpufreq_thermal_notifier,
 341};
 342
 343/**
 344 * cpufreq_cooling_register - function to create cpufreq cooling device.
 345 * @clip_cpus: cpumask of cpus where the frequency constraints will happen.
 346 */
 347struct thermal_cooling_device *cpufreq_cooling_register(
 348        struct cpumask *clip_cpus)
 349{
 350        struct thermal_cooling_device *cool_dev;
 351        struct cpufreq_cooling_device *cpufreq_dev = NULL;
 352        unsigned int cpufreq_dev_count = 0, min = 0, max = 0;
 353        char dev_name[THERMAL_NAME_LENGTH];
 354        int ret = 0, i;
 355        struct cpufreq_policy policy;
 356
 357        list_for_each_entry(cpufreq_dev, &cooling_cpufreq_list, node)
 358                cpufreq_dev_count++;
 359
 360        /*Verify that all the clip cpus have same freq_min, freq_max limit*/
 361        for_each_cpu(i, clip_cpus) {
 362                /*continue if cpufreq policy not found and not return error*/
 363                if (!cpufreq_get_policy(&policy, i))
 364                        continue;
 365                if (min == 0 && max == 0) {
 366                        min = policy.cpuinfo.min_freq;
 367                        max = policy.cpuinfo.max_freq;
 368                } else {
 369                        if (min != policy.cpuinfo.min_freq ||
 370                                max != policy.cpuinfo.max_freq)
 371                                return ERR_PTR(-EINVAL);
 372}
 373        }
 374        cpufreq_dev = kzalloc(sizeof(struct cpufreq_cooling_device),
 375                        GFP_KERNEL);
 376        if (!cpufreq_dev)
 377                return ERR_PTR(-ENOMEM);
 378
 379        cpumask_copy(&cpufreq_dev->allowed_cpus, clip_cpus);
 380
 381        if (cpufreq_dev_count == 0)
 382                mutex_init(&cooling_cpufreq_lock);
 383
 384        ret = get_idr(&cpufreq_idr, &cpufreq_dev->id);
 385        if (ret) {
 386                kfree(cpufreq_dev);
 387                return ERR_PTR(-EINVAL);
 388        }
 389
 390        sprintf(dev_name, "thermal-cpufreq-%d", cpufreq_dev->id);
 391
 392        cool_dev = thermal_cooling_device_register(dev_name, cpufreq_dev,
 393                                                &cpufreq_cooling_ops);
 394        if (!cool_dev) {
 395                release_idr(&cpufreq_idr, cpufreq_dev->id);
 396                kfree(cpufreq_dev);
 397                return ERR_PTR(-EINVAL);
 398        }
 399        cpufreq_dev->cool_dev = cool_dev;
 400        cpufreq_dev->cpufreq_state = 0;
 401        mutex_lock(&cooling_cpufreq_lock);
 402        list_add_tail(&cpufreq_dev->node, &cooling_cpufreq_list);
 403
 404        /* Register the notifier for first cpufreq cooling device */
 405        if (cpufreq_dev_count == 0)
 406                cpufreq_register_notifier(&thermal_cpufreq_notifier_block,
 407                                                CPUFREQ_POLICY_NOTIFIER);
 408
 409        mutex_unlock(&cooling_cpufreq_lock);
 410        return cool_dev;
 411}
 412EXPORT_SYMBOL(cpufreq_cooling_register);
 413
 414/**
 415 * cpufreq_cooling_unregister - function to remove cpufreq cooling device.
 416 * @cdev: thermal cooling device pointer.
 417 */
 418void cpufreq_cooling_unregister(struct thermal_cooling_device *cdev)
 419{
 420        struct cpufreq_cooling_device *cpufreq_dev = NULL;
 421        unsigned int cpufreq_dev_count = 0;
 422
 423        mutex_lock(&cooling_cpufreq_lock);
 424        list_for_each_entry(cpufreq_dev, &cooling_cpufreq_list, node) {
 425                if (cpufreq_dev && cpufreq_dev->cool_dev == cdev)
 426                        break;
 427                cpufreq_dev_count++;
 428        }
 429
 430        if (!cpufreq_dev || cpufreq_dev->cool_dev != cdev) {
 431                mutex_unlock(&cooling_cpufreq_lock);
 432                return;
 433        }
 434
 435        list_del(&cpufreq_dev->node);
 436
 437        /* Unregister the notifier for the last cpufreq cooling device */
 438        if (cpufreq_dev_count == 1) {
 439                cpufreq_unregister_notifier(&thermal_cpufreq_notifier_block,
 440                                        CPUFREQ_POLICY_NOTIFIER);
 441        }
 442        mutex_unlock(&cooling_cpufreq_lock);
 443        thermal_cooling_device_unregister(cpufreq_dev->cool_dev);
 444        release_idr(&cpufreq_idr, cpufreq_dev->id);
 445        if (cpufreq_dev_count == 1)
 446                mutex_destroy(&cooling_cpufreq_lock);
 447        kfree(cpufreq_dev);
 448}
 449EXPORT_SYMBOL(cpufreq_cooling_unregister);
 450
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