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/module.h>
  24 #include <linux/thermal.h>
  25 #include <linux/cpufreq.h>
  26 #include <linux/err.h>
  27 #include <linux/slab.h>
  28 #include <linux/cpu.h>
  29 #include <linux/cpu_cooling.h>
  30
  31 /**
  32  * struct cpufreq_cooling_device - data for cooling device with cpufreq
  33  * @id: unique integer value corresponding to each cpufreq_cooling_device
  34  *      registered.
  35  * @cool_dev: thermal_cooling_device pointer to keep track of the
  36  *      registered cooling device.
  37  * @cpufreq_state: integer value representing the current state of cpufreq
  38  *      cooling devices.
  39  * @cpufreq_val: integer value representing the absolute value of the clipped
  40  *      frequency.
  41  * @allowed_cpus: all the cpus involved for this cpufreq_cooling_device.
  42  *
  43  * This structure is required for keeping information of each
  44  * cpufreq_cooling_device registered. In order to prevent corruption of this a
  45  * mutex lock cooling_cpufreq_lock is used.
  46  */
  47 struct cpufreq_cooling_device {
  48         int id;
  49         struct thermal_cooling_device *cool_dev;
  50         unsigned int cpufreq_state;
  51         unsigned int cpufreq_val;
  52         struct cpumask allowed_cpus;
  53         struct list_head node;
  54 };
  55 static DEFINE_IDR(cpufreq_idr);
  56 static DEFINE_MUTEX(cooling_cpufreq_lock);
  57
  58 static unsigned int cpufreq_dev_count;
  59
  60 static LIST_HEAD(cpufreq_dev_list);
  61
  62 /**
  63  * get_idr - function to get a unique id.
  64  * @idr: struct idr * handle used to create a id.
  65  * @id: int * value generated by this function.
  66  *
  67  * This function will populate @id with an unique
  68  * id, using the idr API.
  69  *
  70  * Return: 0 on success, an error code on failure.
  71  */
  72 static int get_idr(struct idr *idr, int *id)
  73 {
  74         int ret;
  75
  76         mutex_lock(&cooling_cpufreq_lock);
  77         ret = idr_alloc(idr, NULL, 0, 0, GFP_KERNEL);
  78         mutex_unlock(&cooling_cpufreq_lock);
  79         if (unlikely(ret < 0))
  80                 return ret;
  81         *id = ret;
  82
  83         return 0;
  84 }
  85
  86 /**
  87  * release_idr - function to free the unique id.
  88  * @idr: struct idr * handle used for creating the id.
  89  * @id: int value representing the unique id.
  90  */
  91 static void release_idr(struct idr *idr, int id)
  92 {
  93         mutex_lock(&cooling_cpufreq_lock);
  94         idr_remove(idr, id);
  95         mutex_unlock(&cooling_cpufreq_lock);
  96 }
  97
  98 /* Below code defines functions to be used for cpufreq as cooling device */
  99
 100 /**
 101  * is_cpufreq_valid - function to check frequency transitioning capability.
 102  * @cpu: cpu for which check is needed.
 103  *
 104  * This function will check the current state of the system if
 105  * it is capable of changing the frequency for a given @cpu.
 106  *
 107  * Return: 0 if the system is not currently capable of changing
 108  * the frequency of given cpu. !0 in case the frequency is changeable.
 109  */
 110 static int is_cpufreq_valid(int cpu)
 111 {
 112         struct cpufreq_policy policy;
 113
 114         return !cpufreq_get_policy(&policy, cpu);
 115 }
 116
 117 enum cpufreq_cooling_property {
 118         GET_LEVEL,
 119         GET_FREQ,
 120         GET_MAXL,
 121 };
 122
 123 /**
 124  * get_property - fetch a property of interest for a give cpu.
 125  * @cpu: cpu for which the property is required
 126  * @input: query parameter
 127  * @output: query return
 128  * @property: type of query (frequency, level, max level)
 129  *
 130  * This is the common function to
 131  * 1. get maximum cpu cooling states
 132  * 2. translate frequency to cooling state
 133  * 3. translate cooling state to frequency
 134  * Note that the code may be not in good shape
 135  * but it is written in this way in order to:
 136  * a) reduce duplicate code as most of the code can be shared.
 137  * b) make sure the logic is consistent when translating between
 138  *    cooling states and frequencies.
 139  *
 140  * Return: 0 on success, -EINVAL when invalid parameters are passed.
 141  */
 142 static int get_property(unsigned int cpu, unsigned long input,
 143                         unsigned int *output,
 144                         enum cpufreq_cooling_property property)
 145 {
 146         int i;
 147         unsigned long max_level = 0, level = 0;
 148         unsigned int freq = CPUFREQ_ENTRY_INVALID;
 149         int descend = -1;
 150         struct cpufreq_frequency_table *pos, *table =
 151                                         cpufreq_frequency_get_table(cpu);
 152
 153         if (!output)
 154                 return -EINVAL;
 155
 156         if (!table)
 157                 return -EINVAL;
 158
 159         cpufreq_for_each_valid_entry(pos, table) {
 160                 /* ignore duplicate entry */
 161                 if (freq == pos->frequency)
 162                         continue;
 163
 164                 /* get the frequency order */
 165                 if (freq != CPUFREQ_ENTRY_INVALID && descend == -1)
 166                         descend = freq > pos->frequency;
 167
 168                 freq = pos->frequency;
 169                 max_level++;
 170         }
 171
 172         /* No valid cpu frequency entry */
 173         if (max_level == 0)
 174                 return -EINVAL;
 175
 176         /* max_level is an index, not a counter */
 177         max_level--;
 178
 179         /* get max level */
 180         if (property == GET_MAXL) {
 181                 *output = (unsigned int)max_level;
 182                 return 0;
 183         }
 184
 185         if (property == GET_FREQ)
 186                 level = descend ? input : (max_level - input);
 187
 188         i = 0;
 189         cpufreq_for_each_valid_entry(pos, table) {
 190                 /* ignore duplicate entry */
 191                 if (freq == pos->frequency)
 192                         continue;
 193
 194                 /* now we have a valid frequency entry */
 195                 freq = pos->frequency;
 196
 197                 if (property == GET_LEVEL && (unsigned int)input == freq) {
 198                         /* get level by frequency */
 199                         *output = descend ? i : (max_level - i);
 200                         return 0;
 201                 }
 202                 if (property == GET_FREQ && level == i) {
 203                         /* get frequency by level */
 204                         *output = freq;
 205                         return 0;
 206                 }
 207                 i++;
 208         }
 209
 210         return -EINVAL;
 211 }
 212
 213 /**
 214  * cpufreq_cooling_get_level - for a give cpu, return the cooling level.
 215  * @cpu: cpu for which the level is required
 216  * @freq: the frequency of interest
 217  *
 218  * This function will match the cooling level corresponding to the
 219  * requested @freq and return it.
 220  *
 221  * Return: The matched cooling level on success or THERMAL_CSTATE_INVALID
 222  * otherwise.
 223  */
 224 unsigned long cpufreq_cooling_get_level(unsigned int cpu, unsigned int freq)
 225 {
 226         unsigned int val;
 227
 228         if (get_property(cpu, (unsigned long)freq, &val, GET_LEVEL))
 229                 return THERMAL_CSTATE_INVALID;
 230
 231         return (unsigned long)val;
 232 }
 233 EXPORT_SYMBOL_GPL(cpufreq_cooling_get_level);
 234
 235 /**
 236  * get_cpu_frequency - get the absolute value of frequency from level.
 237  * @cpu: cpu for which frequency is fetched.
 238  * @level: cooling level
 239  *
 240  * This function matches cooling level with frequency. Based on a cooling level
 241  * of frequency, equals cooling state of cpu cooling device, it will return
 242  * the corresponding frequency.
 243  *      e.g level=0 --> 1st MAX FREQ, level=1 ---> 2nd MAX FREQ, .... etc
 244  *
 245  * Return: 0 on error, the corresponding frequency otherwise.
 246  */
 247 static unsigned int get_cpu_frequency(unsigned int cpu, unsigned long level)
 248 {
 249         int ret = 0;
 250         unsigned int freq;
 251
 252         ret = get_property(cpu, level, &freq, GET_FREQ);
 253         if (ret)
 254                 return 0;
 255
 256         return freq;
 257 }
 258
 259 /**
 260  * cpufreq_apply_cooling - function to apply frequency clipping.
 261  * @cpufreq_device: cpufreq_cooling_device pointer containing frequency
 262  *      clipping data.
 263  * @cooling_state: value of the cooling state.
 264  *
 265  * Function used to make sure the cpufreq layer is aware of current thermal
 266  * limits. The limits are applied by updating the cpufreq policy.
 267  *
 268  * Return: 0 on success, an error code otherwise (-EINVAL in case wrong
 269  * cooling state).
 270  */
 271 static int cpufreq_apply_cooling(struct cpufreq_cooling_device *cpufreq_device,
 272                                  unsigned long cooling_state)
 273 {
 274         unsigned int cpuid, clip_freq;
 275         struct cpumask *mask = &cpufreq_device->allowed_cpus;
 276         unsigned int cpu = cpumask_any(mask);
 277
 278
 279         /* Check if the old cooling action is same as new cooling action */
 280         if (cpufreq_device->cpufreq_state == cooling_state)
 281                 return 0;
 282
 283         clip_freq = get_cpu_frequency(cpu, cooling_state);
 284         if (!clip_freq)
 285                 return -EINVAL;
 286
 287         cpufreq_device->cpufreq_state = cooling_state;
 288         cpufreq_device->cpufreq_val = clip_freq;
 289
 290         for_each_cpu(cpuid, mask) {
 291                 if (is_cpufreq_valid(cpuid))
 292                         cpufreq_update_policy(cpuid);
 293         }
 294
 295         return 0;
 296 }
 297
 298 /**
 299  * cpufreq_thermal_notifier - notifier callback for cpufreq policy change.
 300  * @nb: struct notifier_block * with callback info.
 301  * @event: value showing cpufreq event for which this function invoked.
 302  * @data: callback-specific data
 303  *
 304  * Callback to hijack the notification on cpufreq policy transition.
 305  * Every time there is a change in policy, we will intercept and
 306  * update the cpufreq policy with thermal constraints.
 307  *
 308  * Return: 0 (success)
 309  */
 310 static int cpufreq_thermal_notifier(struct notifier_block *nb,
 311                                     unsigned long event, void *data)
 312 {
 313         struct cpufreq_policy *policy = data;
 314         unsigned long max_freq = 0;
 315         struct cpufreq_cooling_device *cpufreq_dev;
 316
 317         if (event != CPUFREQ_ADJUST)
 318                 return 0;
 319
 320         mutex_lock(&cooling_cpufreq_lock);
 321         list_for_each_entry(cpufreq_dev, &cpufreq_dev_list, node) {
 322                 if (!cpumask_test_cpu(policy->cpu,
 323                                         &cpufreq_dev->allowed_cpus))
 324                         continue;
 325
 326                 if (!cpufreq_dev->cpufreq_val)
 327                         cpufreq_dev->cpufreq_val = get_cpu_frequency(
 328                                         cpumask_any(&cpufreq_dev->allowed_cpus),
 329                                         cpufreq_dev->cpufreq_state);
 330
 331                 max_freq = cpufreq_dev->cpufreq_val;
 332
 333                 if (policy->max != max_freq)
 334                         cpufreq_verify_within_limits(policy, 0, max_freq);
 335         }
 336         mutex_unlock(&cooling_cpufreq_lock);
 337
 338         return 0;
 339 }
 340
 341 /* cpufreq cooling device callback functions are defined below */
 342
 343 /**
 344  * cpufreq_get_max_state - callback function to get the max cooling state.
 345  * @cdev: thermal cooling device pointer.
 346  * @state: fill this variable with the max cooling state.
 347  *
 348  * Callback for the thermal cooling device to return the cpufreq
 349  * max cooling state.
 350  *
 351  * Return: 0 on success, an error code otherwise.
 352  */
 353 static int cpufreq_get_max_state(struct thermal_cooling_device *cdev,
 354                                  unsigned long *state)
 355 {
 356         struct cpufreq_cooling_device *cpufreq_device = cdev->devdata;
 357         struct cpumask *mask = &cpufreq_device->allowed_cpus;
 358         unsigned int cpu;
 359         unsigned int count = 0;
 360         int ret;
 361
 362         cpu = cpumask_any(mask);
 363
 364         ret = get_property(cpu, 0, &count, GET_MAXL);
 365
 366         if (count > 0)
 367                 *state = count;
 368
 369         return ret;
 370 }
 371
 372 /**
 373  * cpufreq_get_cur_state - callback function to get the current cooling state.
 374  * @cdev: thermal cooling device pointer.
 375  * @state: fill this variable with the current cooling state.
 376  *
 377  * Callback for the thermal cooling device to return the cpufreq
 378  * current cooling state.
 379  *
 380  * Return: 0 on success, an error code otherwise.
 381  */
 382 static int cpufreq_get_cur_state(struct thermal_cooling_device *cdev,
 383                                  unsigned long *state)
 384 {
 385         struct cpufreq_cooling_device *cpufreq_device = cdev->devdata;
 386
 387         *state = cpufreq_device->cpufreq_state;
 388
 389         return 0;
 390 }
 391
 392 /**
 393  * cpufreq_set_cur_state - callback function to set the current cooling state.
 394  * @cdev: thermal cooling device pointer.
 395  * @state: set this variable to the current cooling state.
 396  *
 397  * Callback for the thermal cooling device to change the cpufreq
 398  * current cooling state.
 399  *
 400  * Return: 0 on success, an error code otherwise.
 401  */
 402 static int cpufreq_set_cur_state(struct thermal_cooling_device *cdev,
 403                                  unsigned long state)
 404 {
 405         struct cpufreq_cooling_device *cpufreq_device = cdev->devdata;
 406
 407         return cpufreq_apply_cooling(cpufreq_device, state);
 408 }
 409
 410 /* Bind cpufreq callbacks to thermal cooling device ops */
 411 static struct thermal_cooling_device_ops const cpufreq_cooling_ops = {
 412         .get_max_state = cpufreq_get_max_state,
 413         .get_cur_state = cpufreq_get_cur_state,
 414         .set_cur_state = cpufreq_set_cur_state,
 415 };
 416
 417 /* Notifier for cpufreq policy change */
 418 static struct notifier_block thermal_cpufreq_notifier_block = {
 419         .notifier_call = cpufreq_thermal_notifier,
 420 };
 421
 422 /**
 423  * __cpufreq_cooling_register - helper function to create cpufreq cooling device
 424  * @np: a valid struct device_node to the cooling device device tree node
 425  * @clip_cpus: cpumask of cpus where the frequency constraints will happen.
 426  *
 427  * This interface function registers the cpufreq cooling device with the name
 428  * "thermal-cpufreq-%x". This api can support multiple instances of cpufreq
 429  * cooling devices. It also gives the opportunity to link the cooling device
 430  * with a device tree node, in order to bind it via the thermal DT code.
 431  *
 432  * Return: a valid struct thermal_cooling_device pointer on success,
 433  * on failure, it returns a corresponding ERR_PTR().
 434  */
 435 static struct thermal_cooling_device *
 436 __cpufreq_cooling_register(struct device_node *np,
 437                            const struct cpumask *clip_cpus)
 438 {
 439         struct thermal_cooling_device *cool_dev;
 440         struct cpufreq_cooling_device *cpufreq_dev = NULL;
 441         unsigned int min = 0, max = 0;
 442         char dev_name[THERMAL_NAME_LENGTH];
 443         int ret = 0, i;
 444         struct cpufreq_policy policy;
 445
 446         /* Verify that all the clip cpus have same freq_min, freq_max limit */
 447         for_each_cpu(i, clip_cpus) {
 448                 /* continue if cpufreq policy not found and not return error */
 449                 if (!cpufreq_get_policy(&policy, i))
 450                         continue;
 451                 if (min == 0 && max == 0) {
 452                         min = policy.cpuinfo.min_freq;
 453                         max = policy.cpuinfo.max_freq;
 454                 } else {
 455                         if (min != policy.cpuinfo.min_freq ||
 456                             max != policy.cpuinfo.max_freq)
 457                                 return ERR_PTR(-EINVAL);
 458                 }
 459         }
 460         cpufreq_dev = kzalloc(sizeof(struct cpufreq_cooling_device),
 461                               GFP_KERNEL);
 462         if (!cpufreq_dev)
 463                 return ERR_PTR(-ENOMEM);
 464
 465         cpumask_copy(&cpufreq_dev->allowed_cpus, clip_cpus);
 466
 467         ret = get_idr(&cpufreq_idr, &cpufreq_dev->id);
 468         if (ret) {
 469                 kfree(cpufreq_dev);
 470                 return ERR_PTR(-EINVAL);
 471         }
 472
 473         snprintf(dev_name, sizeof(dev_name), "thermal-cpufreq-%d",
 474                  cpufreq_dev->id);
 475
 476         cool_dev = thermal_of_cooling_device_register(np, dev_name, cpufreq_dev,
 477                                                       &cpufreq_cooling_ops);
 478         if (IS_ERR(cool_dev)) {
 479                 release_idr(&cpufreq_idr, cpufreq_dev->id);
 480                 kfree(cpufreq_dev);
 481                 return cool_dev;
 482         }
 483         cpufreq_dev->cool_dev = cool_dev;
 484         cpufreq_dev->cpufreq_state = 0;
 485         mutex_lock(&cooling_cpufreq_lock);
 486
 487         /* Register the notifier for first cpufreq cooling device */
 488         if (cpufreq_dev_count == 0)
 489                 cpufreq_register_notifier(&thermal_cpufreq_notifier_block,
 490                                           CPUFREQ_POLICY_NOTIFIER);
 491         cpufreq_dev_count++;
 492         list_add(&cpufreq_dev->node, &cpufreq_dev_list);
 493
 494         mutex_unlock(&cooling_cpufreq_lock);
 495
 496         return cool_dev;
 497 }
 498
 499 /**
 500  * cpufreq_cooling_register - function to create cpufreq cooling device.
 501  * @clip_cpus: cpumask of cpus where the frequency constraints will happen.
 502  *
 503  * This interface function registers the cpufreq cooling device with the name
 504  * "thermal-cpufreq-%x". This api can support multiple instances of cpufreq
 505  * cooling devices.
 506  *
 507  * Return: a valid struct thermal_cooling_device pointer on success,
 508  * on failure, it returns a corresponding ERR_PTR().
 509  */
 510 struct thermal_cooling_device *
 511 cpufreq_cooling_register(const struct cpumask *clip_cpus)
 512 {
 513         return __cpufreq_cooling_register(NULL, clip_cpus);
 514 }
 515 EXPORT_SYMBOL_GPL(cpufreq_cooling_register);
 516
 517 /**
 518  * of_cpufreq_cooling_register - function to create cpufreq cooling device.
 519  * @np: a valid struct device_node to the cooling device device tree node
 520  * @clip_cpus: cpumask of cpus where the frequency constraints will happen.
 521  *
 522  * This interface function registers the cpufreq cooling device with the name
 523  * "thermal-cpufreq-%x". This api can support multiple instances of cpufreq
 524  * cooling devices. Using this API, the cpufreq cooling device will be
 525  * linked to the device tree node provided.
 526  *
 527  * Return: a valid struct thermal_cooling_device pointer on success,
 528  * on failure, it returns a corresponding ERR_PTR().
 529  */
 530 struct thermal_cooling_device *
 531 of_cpufreq_cooling_register(struct device_node *np,
 532                             const struct cpumask *clip_cpus)
 533 {
 534         if (!np)
 535                 return ERR_PTR(-EINVAL);
 536
 537         return __cpufreq_cooling_register(np, clip_cpus);
 538 }
 539 EXPORT_SYMBOL_GPL(of_cpufreq_cooling_register);
 540
 541 /**
 542  * cpufreq_cooling_unregister - function to remove cpufreq cooling device.
 543  * @cdev: thermal cooling device pointer.
 544  *
 545  * This interface function unregisters the "thermal-cpufreq-%x" cooling device.
 546  */
 547 void cpufreq_cooling_unregister(struct thermal_cooling_device *cdev)
 548 {
 549         struct cpufreq_cooling_device *cpufreq_dev;
 550
 551         if (!cdev)
 552                 return;
 553
 554         cpufreq_dev = cdev->devdata;
 555         mutex_lock(&cooling_cpufreq_lock);
 556         list_del(&cpufreq_dev->node);
 557         cpufreq_dev_count--;
 558
 559         /* Unregister the notifier for the last cpufreq cooling device */
 560         if (cpufreq_dev_count == 0)
 561                 cpufreq_unregister_notifier(&thermal_cpufreq_notifier_block,
 562                                             CPUFREQ_POLICY_NOTIFIER);
 563         mutex_unlock(&cooling_cpufreq_lock);
 564
 565         thermal_cooling_device_unregister(cpufreq_dev->cool_dev);
 566         release_idr(&cpufreq_idr, cpufreq_dev->id);
 567         kfree(cpufreq_dev);
 568 }
 569 EXPORT_SYMBOL_GPL(cpufreq_cooling_unregister);