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 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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