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