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  *  Copyright (C) 2014  Viresh Kumar <viresh.kumar@linaro.org>
   8  *
   9  * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  10  *  This program is free software; you can redistribute it and/or modify
  11  *  it under the terms of the GNU General Public License as published by
  12  *  the Free Software Foundation; version 2 of the License.
  13  *
  14  *  This program is distributed in the hope that it will be useful, but
  15  *  WITHOUT ANY WARRANTY; without even the implied warranty of
  16  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  17  *  General Public License for more details.
  18  *
  19  *  You should have received a copy of the GNU General Public License along
  20  *  with this program; if not, write to the Free Software Foundation, Inc.,
  21  *  59 Temple Place, Suite 330, Boston, MA 02111-1307 USA.
  22  *
  23  * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  24  */
  25 #include <linux/module.h>
  26 #include <linux/thermal.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  * Cooling state <-> CPUFreq frequency
  35  *
  36  * Cooling states are translated to frequencies throughout this driver and this
  37  * is the relation between them.
  38  *
  39  * Highest cooling state corresponds to lowest possible frequency.
  40  *
  41  * i.e.
  42  *      level 0 --> 1st Max Freq
  43  *      level 1 --> 2nd Max Freq
  44  *      ...
  45  */
  46
  47 /**
  48  * struct cpufreq_cooling_device - data for cooling device with cpufreq
  49  * @id: unique integer value corresponding to each cpufreq_cooling_device
  50  *      registered.
  51  * @cool_dev: thermal_cooling_device pointer to keep track of the
  52  *      registered cooling device.
  53  * @cpufreq_state: integer value representing the current state of cpufreq
  54  *      cooling devices.
  55  * @cpufreq_val: integer value representing the absolute value of the clipped
  56  *      frequency.
  57  * @max_level: maximum cooling level. One less than total number of valid
  58  *      cpufreq frequencies.
  59  * @allowed_cpus: all the cpus involved for this cpufreq_cooling_device.
  60  * @node: list_head to link all cpufreq_cooling_device together.
  61  *
  62  * This structure is required for keeping information of each registered
  63  * cpufreq_cooling_device.
  64  */
  65 struct cpufreq_cooling_device {
  66         int id;
  67         struct thermal_cooling_device *cool_dev;
  68         unsigned int cpufreq_state;
  69         unsigned int cpufreq_val;
  70         unsigned int max_level;
  71         unsigned int *freq_table;       /* In descending order */
  72         struct cpumask allowed_cpus;
  73         struct list_head node;
  74 };
  75 static DEFINE_IDR(cpufreq_idr);
  76 static DEFINE_MUTEX(cooling_cpufreq_lock);
  77
  78 static LIST_HEAD(cpufreq_dev_list);
  79
  80 /**
  81  * get_idr - function to get a unique id.
  82  * @idr: struct idr * handle used to create a id.
  83  * @id: int * value generated by this function.
  84  *
  85  * This function will populate @id with an unique
  86  * id, using the idr API.
  87  *
  88  * Return: 0 on success, an error code on failure.
  89  */
  90 static int get_idr(struct idr *idr, int *id)
  91 {
  92         int ret;
  93
  94         mutex_lock(&cooling_cpufreq_lock);
  95         ret = idr_alloc(idr, NULL, 0, 0, GFP_KERNEL);
  96         mutex_unlock(&cooling_cpufreq_lock);
  97         if (unlikely(ret < 0))
  98                 return ret;
  99         *id = ret;
 100
 101         return 0;
 102 }
 103
 104 /**
 105  * release_idr - function to free the unique id.
 106  * @idr: struct idr * handle used for creating the id.
 107  * @id: int value representing the unique id.
 108  */
 109 static void release_idr(struct idr *idr, int id)
 110 {
 111         mutex_lock(&cooling_cpufreq_lock);
 112         idr_remove(idr, id);
 113         mutex_unlock(&cooling_cpufreq_lock);
 114 }
 115
 116 /* Below code defines functions to be used for cpufreq as cooling device */
 117
 118 /**
 119  * get_level: Find the level for a particular frequency
 120  * @cpufreq_dev: cpufreq_dev for which the property is required
 121  * @freq: Frequency
 122  *
 123  * Return: level on success, THERMAL_CSTATE_INVALID on error.
 124  */
 125 static unsigned long get_level(struct cpufreq_cooling_device *cpufreq_dev,
 126                                unsigned int freq)
 127 {
 128         unsigned long level;
 129
 130         for (level = 0; level <= cpufreq_dev->max_level; level++) {
 131                 if (freq == cpufreq_dev->freq_table[level])
 132                         return level;
 133
 134                 if (freq > cpufreq_dev->freq_table[level])
 135                         break;
 136         }
 137
 138         return THERMAL_CSTATE_INVALID;
 139 }
 140
 141 /**
 142  * cpufreq_cooling_get_level - for a given cpu, return the cooling level.
 143  * @cpu: cpu for which the level is required
 144  * @freq: the frequency of interest
 145  *
 146  * This function will match the cooling level corresponding to the
 147  * requested @freq and return it.
 148  *
 149  * Return: The matched cooling level on success or THERMAL_CSTATE_INVALID
 150  * otherwise.
 151  */
 152 unsigned long cpufreq_cooling_get_level(unsigned int cpu, unsigned int freq)
 153 {
 154         struct cpufreq_cooling_device *cpufreq_dev;
 155
 156         mutex_lock(&cooling_cpufreq_lock);
 157         list_for_each_entry(cpufreq_dev, &cpufreq_dev_list, node) {
 158                 if (cpumask_test_cpu(cpu, &cpufreq_dev->allowed_cpus)) {
 159                         mutex_unlock(&cooling_cpufreq_lock);
 160                         return get_level(cpufreq_dev, freq);
 161                 }
 162         }
 163         mutex_unlock(&cooling_cpufreq_lock);
 164
 165         pr_err("%s: cpu:%d not part of any cooling device\n", __func__, cpu);
 166         return THERMAL_CSTATE_INVALID;
 167 }
 168 EXPORT_SYMBOL_GPL(cpufreq_cooling_get_level);
 169
 170 /**
 171  * cpufreq_thermal_notifier - notifier callback for cpufreq policy change.
 172  * @nb: struct notifier_block * with callback info.
 173  * @event: value showing cpufreq event for which this function invoked.
 174  * @data: callback-specific data
 175  *
 176  * Callback to hijack the notification on cpufreq policy transition.
 177  * Every time there is a change in policy, we will intercept and
 178  * update the cpufreq policy with thermal constraints.
 179  *
 180  * Return: 0 (success)
 181  */
 182 static int cpufreq_thermal_notifier(struct notifier_block *nb,
 183                                     unsigned long event, void *data)
 184 {
 185         struct cpufreq_policy *policy = data;
 186         unsigned long max_freq = 0;
 187         struct cpufreq_cooling_device *cpufreq_dev;
 188
 189         if (event != CPUFREQ_ADJUST)
 190                 return 0;
 191
 192         mutex_lock(&cooling_cpufreq_lock);
 193         list_for_each_entry(cpufreq_dev, &cpufreq_dev_list, node) {
 194                 if (!cpumask_test_cpu(policy->cpu,
 195                                         &cpufreq_dev->allowed_cpus))
 196                         continue;
 197
 198                 max_freq = cpufreq_dev->cpufreq_val;
 199
 200                 if (policy->max != max_freq)
 201                         cpufreq_verify_within_limits(policy, 0, max_freq);
 202         }
 203         mutex_unlock(&cooling_cpufreq_lock);
 204
 205         return 0;
 206 }
 207
 208 /* cpufreq cooling device callback functions are defined below */
 209
 210 /**
 211  * cpufreq_get_max_state - callback function to get the max cooling state.
 212  * @cdev: thermal cooling device pointer.
 213  * @state: fill this variable with the max cooling state.
 214  *
 215  * Callback for the thermal cooling device to return the cpufreq
 216  * max cooling state.
 217  *
 218  * Return: 0 on success, an error code otherwise.
 219  */
 220 static int cpufreq_get_max_state(struct thermal_cooling_device *cdev,
 221                                  unsigned long *state)
 222 {
 223         struct cpufreq_cooling_device *cpufreq_device = cdev->devdata;
 224
 225         *state = cpufreq_device->max_level;
 226         return 0;
 227 }
 228
 229 /**
 230  * cpufreq_get_cur_state - callback function to get the current cooling state.
 231  * @cdev: thermal cooling device pointer.
 232  * @state: fill this variable with the current cooling state.
 233  *
 234  * Callback for the thermal cooling device to return the cpufreq
 235  * current cooling state.
 236  *
 237  * Return: 0 on success, an error code otherwise.
 238  */
 239 static int cpufreq_get_cur_state(struct thermal_cooling_device *cdev,
 240                                  unsigned long *state)
 241 {
 242         struct cpufreq_cooling_device *cpufreq_device = cdev->devdata;
 243
 244         *state = cpufreq_device->cpufreq_state;
 245
 246         return 0;
 247 }
 248
 249 /**
 250  * cpufreq_set_cur_state - callback function to set the current cooling state.
 251  * @cdev: thermal cooling device pointer.
 252  * @state: set this variable to the current cooling state.
 253  *
 254  * Callback for the thermal cooling device to change the cpufreq
 255  * current cooling state.
 256  *
 257  * Return: 0 on success, an error code otherwise.
 258  */
 259 static int cpufreq_set_cur_state(struct thermal_cooling_device *cdev,
 260                                  unsigned long state)
 261 {
 262         struct cpufreq_cooling_device *cpufreq_device = cdev->devdata;
 263         unsigned int cpu = cpumask_any(&cpufreq_device->allowed_cpus);
 264         unsigned int clip_freq;
 265
 266         /* Request state should be less than max_level */
 267         if (WARN_ON(state > cpufreq_device->max_level))
 268                 return -EINVAL;
 269
 270         /* Check if the old cooling action is same as new cooling action */
 271         if (cpufreq_device->cpufreq_state == state)
 272                 return 0;
 273
 274         clip_freq = cpufreq_device->freq_table[state];
 275         cpufreq_device->cpufreq_state = state;
 276         cpufreq_device->cpufreq_val = clip_freq;
 277
 278         cpufreq_update_policy(cpu);
 279
 280         return 0;
 281 }
 282
 283 /* Bind cpufreq callbacks to thermal cooling device ops */
 284 static struct thermal_cooling_device_ops const cpufreq_cooling_ops = {
 285         .get_max_state = cpufreq_get_max_state,
 286         .get_cur_state = cpufreq_get_cur_state,
 287         .set_cur_state = cpufreq_set_cur_state,
 288 };
 289
 290 /* Notifier for cpufreq policy change */
 291 static struct notifier_block thermal_cpufreq_notifier_block = {
 292         .notifier_call = cpufreq_thermal_notifier,
 293 };
 294
 295 static unsigned int find_next_max(struct cpufreq_frequency_table *table,
 296                                   unsigned int prev_max)
 297 {
 298         struct cpufreq_frequency_table *pos;
 299         unsigned int max = 0;
 300
 301         cpufreq_for_each_valid_entry(pos, table) {
 302                 if (pos->frequency > max && pos->frequency < prev_max)
 303                         max = pos->frequency;
 304         }
 305
 306         return max;
 307 }
 308
 309 /**
 310  * __cpufreq_cooling_register - helper function to create cpufreq cooling device
 311  * @np: a valid struct device_node to the cooling device device tree node
 312  * @clip_cpus: cpumask of cpus where the frequency constraints will happen.
 313  * Normally this should be same as cpufreq policy->related_cpus.
 314  *
 315  * This interface function registers the cpufreq cooling device with the name
 316  * "thermal-cpufreq-%x". This api can support multiple instances of cpufreq
 317  * cooling devices. It also gives the opportunity to link the cooling device
 318  * with a device tree node, in order to bind it via the thermal DT code.
 319  *
 320  * Return: a valid struct thermal_cooling_device pointer on success,
 321  * on failure, it returns a corresponding ERR_PTR().
 322  */
 323 static struct thermal_cooling_device *
 324 __cpufreq_cooling_register(struct device_node *np,
 325                            const struct cpumask *clip_cpus)
 326 {
 327         struct thermal_cooling_device *cool_dev;
 328         struct cpufreq_cooling_device *cpufreq_dev;
 329         char dev_name[THERMAL_NAME_LENGTH];
 330         struct cpufreq_frequency_table *pos, *table;
 331         unsigned int freq, i;
 332         int ret;
 333
 334         table = cpufreq_frequency_get_table(cpumask_first(clip_cpus));
 335         if (!table) {
 336                 pr_debug("%s: CPUFreq table not found\n", __func__);
 337                 return ERR_PTR(-EPROBE_DEFER);
 338         }
 339
 340         cpufreq_dev = kzalloc(sizeof(*cpufreq_dev), GFP_KERNEL);
 341         if (!cpufreq_dev)
 342                 return ERR_PTR(-ENOMEM);
 343
 344         /* Find max levels */
 345         cpufreq_for_each_valid_entry(pos, table)
 346                 cpufreq_dev->max_level++;
 347
 348         cpufreq_dev->freq_table = kmalloc(sizeof(*cpufreq_dev->freq_table) *
 349                                           cpufreq_dev->max_level, GFP_KERNEL);
 350         if (!cpufreq_dev->freq_table) {
 351                 cool_dev = ERR_PTR(-ENOMEM);
 352                 goto free_cdev;
 353         }
 354
 355         /* max_level is an index, not a counter */
 356         cpufreq_dev->max_level--;
 357
 358         cpumask_copy(&cpufreq_dev->allowed_cpus, clip_cpus);
 359
 360         ret = get_idr(&cpufreq_idr, &cpufreq_dev->id);
 361         if (ret) {
 362                 cool_dev = ERR_PTR(ret);
 363                 goto free_table;
 364         }
 365
 366         snprintf(dev_name, sizeof(dev_name), "thermal-cpufreq-%d",
 367                  cpufreq_dev->id);
 368
 369         cool_dev = thermal_of_cooling_device_register(np, dev_name, cpufreq_dev,
 370                                                       &cpufreq_cooling_ops);
 371         if (IS_ERR(cool_dev))
 372                 goto remove_idr;
 373
 374         /* Fill freq-table in descending order of frequencies */
 375         for (i = 0, freq = -1; i <= cpufreq_dev->max_level; i++) {
 376                 freq = find_next_max(table, freq);
 377                 cpufreq_dev->freq_table[i] = freq;
 378
 379                 /* Warn for duplicate entries */
 380                 if (!freq)
 381                         pr_warn("%s: table has duplicate entries\n", __func__);
 382                 else
 383                         pr_debug("%s: freq:%u KHz\n", __func__, freq);
 384         }
 385
 386         cpufreq_dev->cpufreq_val = cpufreq_dev->freq_table[0];
 387         cpufreq_dev->cool_dev = cool_dev;
 388
 389         mutex_lock(&cooling_cpufreq_lock);
 390
 391         /* Register the notifier for first cpufreq cooling device */
 392         if (list_empty(&cpufreq_dev_list))
 393                 cpufreq_register_notifier(&thermal_cpufreq_notifier_block,
 394                                           CPUFREQ_POLICY_NOTIFIER);
 395         list_add(&cpufreq_dev->node, &cpufreq_dev_list);
 396
 397         mutex_unlock(&cooling_cpufreq_lock);
 398
 399         return cool_dev;
 400
 401 remove_idr:
 402         release_idr(&cpufreq_idr, cpufreq_dev->id);
 403 free_table:
 404         kfree(cpufreq_dev->freq_table);
 405 free_cdev:
 406         kfree(cpufreq_dev);
 407
 408         return cool_dev;
 409 }
 410
 411 /**
 412  * cpufreq_cooling_register - function to create cpufreq cooling device.
 413  * @clip_cpus: cpumask of cpus where the frequency constraints will happen.
 414  *
 415  * This interface function registers the cpufreq cooling device with the name
 416  * "thermal-cpufreq-%x". This api can support multiple instances of cpufreq
 417  * cooling devices.
 418  *
 419  * Return: a valid struct thermal_cooling_device pointer on success,
 420  * on failure, it returns a corresponding ERR_PTR().
 421  */
 422 struct thermal_cooling_device *
 423 cpufreq_cooling_register(const struct cpumask *clip_cpus)
 424 {
 425         return __cpufreq_cooling_register(NULL, clip_cpus);
 426 }
 427 EXPORT_SYMBOL_GPL(cpufreq_cooling_register);
 428
 429 /**
 430  * of_cpufreq_cooling_register - function to create cpufreq cooling device.
 431  * @np: a valid struct device_node to the cooling device device tree node
 432  * @clip_cpus: cpumask of cpus where the frequency constraints will happen.
 433  *
 434  * This interface function registers the cpufreq cooling device with the name
 435  * "thermal-cpufreq-%x". This api can support multiple instances of cpufreq
 436  * cooling devices. Using this API, the cpufreq cooling device will be
 437  * linked to the device tree node provided.
 438  *
 439  * Return: a valid struct thermal_cooling_device pointer on success,
 440  * on failure, it returns a corresponding ERR_PTR().
 441  */
 442 struct thermal_cooling_device *
 443 of_cpufreq_cooling_register(struct device_node *np,
 444                             const struct cpumask *clip_cpus)
 445 {
 446         if (!np)
 447                 return ERR_PTR(-EINVAL);
 448
 449         return __cpufreq_cooling_register(np, clip_cpus);
 450 }
 451 EXPORT_SYMBOL_GPL(of_cpufreq_cooling_register);
 452
 453 /**
 454  * cpufreq_cooling_unregister - function to remove cpufreq cooling device.
 455  * @cdev: thermal cooling device pointer.
 456  *
 457  * This interface function unregisters the "thermal-cpufreq-%x" cooling device.
 458  */
 459 void cpufreq_cooling_unregister(struct thermal_cooling_device *cdev)
 460 {
 461         struct cpufreq_cooling_device *cpufreq_dev;
 462
 463         if (!cdev)
 464                 return;
 465
 466         cpufreq_dev = cdev->devdata;
 467         mutex_lock(&cooling_cpufreq_lock);
 468         list_del(&cpufreq_dev->node);
 469
 470         /* Unregister the notifier for the last cpufreq cooling device */
 471         if (list_empty(&cpufreq_dev_list))
 472                 cpufreq_unregister_notifier(&thermal_cpufreq_notifier_block,
 473                                             CPUFREQ_POLICY_NOTIFIER);
 474         mutex_unlock(&cooling_cpufreq_lock);
 475
 476         thermal_cooling_device_unregister(cpufreq_dev->cool_dev);
 477         release_idr(&cpufreq_idr, cpufreq_dev->id);
 478         kfree(cpufreq_dev->freq_table);
 479         kfree(cpufreq_dev);
 480 }
 481 EXPORT_SYMBOL_GPL(cpufreq_cooling_unregister);