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  * Cooling state <-> CPUFreq frequency
  33  *
  34  * Cooling states are translated to frequencies throughout this driver and this
  35  * is the relation between them.
  36  *
  37  * Highest cooling state corresponds to lowest possible frequency.
  38  *
  39  * i.e.
  40  *      level 0 --> 1st Max Freq
  41  *      level 1 --> 2nd Max Freq
  42  *      ...
  43  */
  44
  45 /**
  46  * struct cpufreq_cooling_device - data for cooling device with cpufreq
  47  * @id: unique integer value corresponding to each cpufreq_cooling_device
  48  *      registered.
  49  * @cool_dev: thermal_cooling_device pointer to keep track of the
  50  *      registered cooling device.
  51  * @cpufreq_state: integer value representing the current state of cpufreq
  52  *      cooling devices.
  53  * @cpufreq_val: integer value representing the absolute value of the clipped
  54  *      frequency.
  55  * @allowed_cpus: all the cpus involved for this cpufreq_cooling_device.
  56  *
  57  * This structure is required for keeping information of each registered
  58  * cpufreq_cooling_device.
  59  */
  60 struct cpufreq_cooling_device {
  61         int id;
  62         struct thermal_cooling_device *cool_dev;
  63         unsigned int cpufreq_state;
  64         unsigned int cpufreq_val;
  65         struct cpumask allowed_cpus;
  66         struct list_head node;
  67 };
  68 static DEFINE_IDR(cpufreq_idr);
  69 static DEFINE_MUTEX(cooling_cpufreq_lock);
  70
  71 static unsigned int cpufreq_dev_count;
  72
  73 static LIST_HEAD(cpufreq_dev_list);
  74
  75 /**
  76  * get_idr - function to get a unique id.
  77  * @idr: struct idr * handle used to create a id.
  78  * @id: int * value generated by this function.
  79  *
  80  * This function will populate @id with an unique
  81  * id, using the idr API.
  82  *
  83  * Return: 0 on success, an error code on failure.
  84  */
  85 static int get_idr(struct idr *idr, int *id)
  86 {
  87         int ret;
  88
  89         mutex_lock(&cooling_cpufreq_lock);
  90         ret = idr_alloc(idr, NULL, 0, 0, GFP_KERNEL);
  91         mutex_unlock(&cooling_cpufreq_lock);
  92         if (unlikely(ret < 0))
  93                 return ret;
  94         *id = ret;
  95
  96         return 0;
  97 }
  98
  99 /**
 100  * release_idr - function to free the unique id.
 101  * @idr: struct idr * handle used for creating the id.
 102  * @id: int value representing the unique id.
 103  */
 104 static void release_idr(struct idr *idr, int id)
 105 {
 106         mutex_lock(&cooling_cpufreq_lock);
 107         idr_remove(idr, id);
 108         mutex_unlock(&cooling_cpufreq_lock);
 109 }
 110
 111 /* Below code defines functions to be used for cpufreq as cooling device */
 112
 113 /**
 114  * is_cpufreq_valid - function to check frequency transitioning capability.
 115  * @cpu: cpu for which check is needed.
 116  *
 117  * This function will check the current state of the system if
 118  * it is capable of changing the frequency for a given @cpu.
 119  *
 120  * Return: 0 if the system is not currently capable of changing
 121  * the frequency of given cpu. !0 in case the frequency is changeable.
 122  */
 123 static int is_cpufreq_valid(int cpu)
 124 {
 125         struct cpufreq_policy policy;
 126
 127         return !cpufreq_get_policy(&policy, cpu);
 128 }
 129
 130 enum cpufreq_cooling_property {
 131         GET_LEVEL,
 132         GET_FREQ,
 133         GET_MAXL,
 134 };
 135
 136 /**
 137  * get_property - fetch a property of interest for a given cpu.
 138  * @cpu: cpu for which the property is required
 139  * @input: query parameter
 140  * @output: query return
 141  * @property: type of query (frequency, level, max level)
 142  *
 143  * This is the common function to
 144  * 1. get maximum cpu cooling states
 145  * 2. translate frequency to cooling state
 146  * 3. translate cooling state to frequency
 147  *
 148  * Note that the code may be not in good shape
 149  * but it is written in this way in order to:
 150  * a) reduce duplicate code as most of the code can be shared.
 151  * b) make sure the logic is consistent when translating between
 152  *    cooling states and frequencies.
 153  *
 154  * Return: 0 on success, -EINVAL when invalid parameters are passed.
 155  */
 156 static int get_property(unsigned int cpu, unsigned long input,
 157                         unsigned int *output,
 158                         enum cpufreq_cooling_property property)
 159 {
 160         int i;
 161         unsigned long max_level = 0, level = 0;
 162         unsigned int freq = CPUFREQ_ENTRY_INVALID;
 163         int descend = -1;
 164         struct cpufreq_frequency_table *pos, *table =
 165                                         cpufreq_frequency_get_table(cpu);
 166
 167         if (!output)
 168                 return -EINVAL;
 169
 170         if (!table)
 171                 return -EINVAL;
 172
 173         cpufreq_for_each_valid_entry(pos, table) {
 174                 /* ignore duplicate entry */
 175                 if (freq == pos->frequency)
 176                         continue;
 177
 178                 /* get the frequency order */
 179                 if (freq != CPUFREQ_ENTRY_INVALID && descend == -1)
 180                         descend = freq > pos->frequency;
 181
 182                 freq = pos->frequency;
 183                 max_level++;
 184         }
 185
 186         /* No valid cpu frequency entry */
 187         if (max_level == 0)
 188                 return -EINVAL;
 189
 190         /* max_level is an index, not a counter */
 191         max_level--;
 192
 193         /* get max level */
 194         if (property == GET_MAXL) {
 195                 *output = (unsigned int)max_level;
 196                 return 0;
 197         }
 198
 199         if (property == GET_FREQ)
 200                 level = descend ? input : (max_level - input);
 201
 202         i = 0;
 203         cpufreq_for_each_valid_entry(pos, table) {
 204                 /* ignore duplicate entry */
 205                 if (freq == pos->frequency)
 206                         continue;
 207
 208                 /* now we have a valid frequency entry */
 209                 freq = pos->frequency;
 210
 211                 if (property == GET_LEVEL && (unsigned int)input == freq) {
 212                         /* get level by frequency */
 213                         *output = descend ? i : (max_level - i);
 214                         return 0;
 215                 }
 216                 if (property == GET_FREQ && level == i) {
 217                         /* get frequency by level */
 218                         *output = freq;
 219                         return 0;
 220                 }
 221                 i++;
 222         }
 223
 224         return -EINVAL;
 225 }
 226
 227 /**
 228  * cpufreq_cooling_get_level - for a given cpu, return the cooling level.
 229  * @cpu: cpu for which the level is required
 230  * @freq: the frequency of interest
 231  *
 232  * This function will match the cooling level corresponding to the
 233  * requested @freq and return it.
 234  *
 235  * Return: The matched cooling level on success or THERMAL_CSTATE_INVALID
 236  * otherwise.
 237  */
 238 unsigned long cpufreq_cooling_get_level(unsigned int cpu, unsigned int freq)
 239 {
 240         unsigned int val;
 241
 242         if (get_property(cpu, (unsigned long)freq, &val, GET_LEVEL))
 243                 return THERMAL_CSTATE_INVALID;
 244
 245         return (unsigned long)val;
 246 }
 247 EXPORT_SYMBOL_GPL(cpufreq_cooling_get_level);
 248
 249 /**
 250  * get_cpu_frequency - get the absolute value of frequency from level.
 251  * @cpu: cpu for which frequency is fetched.
 252  * @level: cooling level
 253  *
 254  * This function matches cooling level with frequency. Based on a cooling level
 255  * of frequency, equals cooling state of cpu cooling device, it will return
 256  * the corresponding frequency.
 257  *      e.g level=0 --> 1st MAX FREQ, level=1 ---> 2nd MAX FREQ, .... etc
 258  *
 259  * Return: 0 on error, the corresponding frequency otherwise.
 260  */
 261 static unsigned int get_cpu_frequency(unsigned int cpu, unsigned long level)
 262 {
 263         int ret = 0;
 264         unsigned int freq;
 265
 266         ret = get_property(cpu, level, &freq, GET_FREQ);
 267         if (ret)
 268                 return 0;
 269
 270         return freq;
 271 }
 272
 273 /**
 274  * cpufreq_apply_cooling - function to apply frequency clipping.
 275  * @cpufreq_device: cpufreq_cooling_device pointer containing frequency
 276  *      clipping data.
 277  * @cooling_state: value of the cooling state.
 278  *
 279  * Function used to make sure the cpufreq layer is aware of current thermal
 280  * limits. The limits are applied by updating the cpufreq policy.
 281  *
 282  * Return: 0 on success, an error code otherwise (-EINVAL in case wrong
 283  * cooling state).
 284  */
 285 static int cpufreq_apply_cooling(struct cpufreq_cooling_device *cpufreq_device,
 286                                  unsigned long cooling_state)
 287 {
 288         unsigned int cpuid, clip_freq;
 289         struct cpumask *mask = &cpufreq_device->allowed_cpus;
 290         unsigned int cpu = cpumask_any(mask);
 291
 292
 293         /* Check if the old cooling action is same as new cooling action */
 294         if (cpufreq_device->cpufreq_state == cooling_state)
 295                 return 0;
 296
 297         clip_freq = get_cpu_frequency(cpu, cooling_state);
 298         if (!clip_freq)
 299                 return -EINVAL;
 300
 301         cpufreq_device->cpufreq_state = cooling_state;
 302         cpufreq_device->cpufreq_val = clip_freq;
 303
 304         for_each_cpu(cpuid, mask) {
 305                 if (is_cpufreq_valid(cpuid))
 306                         cpufreq_update_policy(cpuid);
 307         }
 308
 309         return 0;
 310 }
 311
 312 /**
 313  * cpufreq_thermal_notifier - notifier callback for cpufreq policy change.
 314  * @nb: struct notifier_block * with callback info.
 315  * @event: value showing cpufreq event for which this function invoked.
 316  * @data: callback-specific data
 317  *
 318  * Callback to hijack the notification on cpufreq policy transition.
 319  * Every time there is a change in policy, we will intercept and
 320  * update the cpufreq policy with thermal constraints.
 321  *
 322  * Return: 0 (success)
 323  */
 324 static int cpufreq_thermal_notifier(struct notifier_block *nb,
 325                                     unsigned long event, void *data)
 326 {
 327         struct cpufreq_policy *policy = data;
 328         unsigned long max_freq = 0;
 329         struct cpufreq_cooling_device *cpufreq_dev;
 330
 331         if (event != CPUFREQ_ADJUST)
 332                 return 0;
 333
 334         mutex_lock(&cooling_cpufreq_lock);
 335         list_for_each_entry(cpufreq_dev, &cpufreq_dev_list, node) {
 336                 if (!cpumask_test_cpu(policy->cpu,
 337                                         &cpufreq_dev->allowed_cpus))
 338                         continue;
 339
 340                 if (!cpufreq_dev->cpufreq_val)
 341                         cpufreq_dev->cpufreq_val = get_cpu_frequency(
 342                                         cpumask_any(&cpufreq_dev->allowed_cpus),
 343                                         cpufreq_dev->cpufreq_state);
 344
 345                 max_freq = cpufreq_dev->cpufreq_val;
 346
 347                 if (policy->max != max_freq)
 348                         cpufreq_verify_within_limits(policy, 0, max_freq);
 349         }
 350         mutex_unlock(&cooling_cpufreq_lock);
 351
 352         return 0;
 353 }
 354
 355 /* cpufreq cooling device callback functions are defined below */
 356
 357 /**
 358  * cpufreq_get_max_state - callback function to get the max cooling state.
 359  * @cdev: thermal cooling device pointer.
 360  * @state: fill this variable with the max cooling state.
 361  *
 362  * Callback for the thermal cooling device to return the cpufreq
 363  * max cooling state.
 364  *
 365  * Return: 0 on success, an error code otherwise.
 366  */
 367 static int cpufreq_get_max_state(struct thermal_cooling_device *cdev,
 368                                  unsigned long *state)
 369 {
 370         struct cpufreq_cooling_device *cpufreq_device = cdev->devdata;
 371         struct cpumask *mask = &cpufreq_device->allowed_cpus;
 372         unsigned int cpu;
 373         unsigned int count = 0;
 374         int ret;
 375
 376         cpu = cpumask_any(mask);
 377
 378         ret = get_property(cpu, 0, &count, GET_MAXL);
 379
 380         if (count > 0)
 381                 *state = count;
 382
 383         return ret;
 384 }
 385
 386 /**
 387  * cpufreq_get_cur_state - callback function to get the current cooling state.
 388  * @cdev: thermal cooling device pointer.
 389  * @state: fill this variable with the current cooling state.
 390  *
 391  * Callback for the thermal cooling device to return the cpufreq
 392  * current cooling state.
 393  *
 394  * Return: 0 on success, an error code otherwise.
 395  */
 396 static int cpufreq_get_cur_state(struct thermal_cooling_device *cdev,
 397                                  unsigned long *state)
 398 {
 399         struct cpufreq_cooling_device *cpufreq_device = cdev->devdata;
 400
 401         *state = cpufreq_device->cpufreq_state;
 402
 403         return 0;
 404 }
 405
 406 /**
 407  * cpufreq_set_cur_state - callback function to set the current cooling state.
 408  * @cdev: thermal cooling device pointer.
 409  * @state: set this variable to the current cooling state.
 410  *
 411  * Callback for the thermal cooling device to change the cpufreq
 412  * current cooling state.
 413  *
 414  * Return: 0 on success, an error code otherwise.
 415  */
 416 static int cpufreq_set_cur_state(struct thermal_cooling_device *cdev,
 417                                  unsigned long state)
 418 {
 419         struct cpufreq_cooling_device *cpufreq_device = cdev->devdata;
 420
 421         return cpufreq_apply_cooling(cpufreq_device, state);
 422 }
 423
 424 /* Bind cpufreq callbacks to thermal cooling device ops */
 425 static struct thermal_cooling_device_ops const cpufreq_cooling_ops = {
 426         .get_max_state = cpufreq_get_max_state,
 427         .get_cur_state = cpufreq_get_cur_state,
 428         .set_cur_state = cpufreq_set_cur_state,
 429 };
 430
 431 /* Notifier for cpufreq policy change */
 432 static struct notifier_block thermal_cpufreq_notifier_block = {
 433         .notifier_call = cpufreq_thermal_notifier,
 434 };
 435
 436 /**
 437  * __cpufreq_cooling_register - helper function to create cpufreq cooling device
 438  * @np: a valid struct device_node to the cooling device device tree node
 439  * @clip_cpus: cpumask of cpus where the frequency constraints will happen.
 440  *
 441  * This interface function registers the cpufreq cooling device with the name
 442  * "thermal-cpufreq-%x". This api can support multiple instances of cpufreq
 443  * cooling devices. It also gives the opportunity to link the cooling device
 444  * with a device tree node, in order to bind it via the thermal DT code.
 445  *
 446  * Return: a valid struct thermal_cooling_device pointer on success,
 447  * on failure, it returns a corresponding ERR_PTR().
 448  */
 449 static struct thermal_cooling_device *
 450 __cpufreq_cooling_register(struct device_node *np,
 451                            const struct cpumask *clip_cpus)
 452 {
 453         struct thermal_cooling_device *cool_dev;
 454         struct cpufreq_cooling_device *cpufreq_dev = NULL;
 455         unsigned int min = 0, max = 0;
 456         char dev_name[THERMAL_NAME_LENGTH];
 457         int ret = 0, i;
 458         struct cpufreq_policy policy;
 459
 460         if (!cpufreq_frequency_get_table(cpumask_first(clip_cpus))) {
 461                 pr_debug("%s: CPUFreq table not found\n", __func__);
 462                 return ERR_PTR(-EPROBE_DEFER);
 463         }
 464
 465         /* Verify that all the clip cpus have same freq_min, freq_max limit */
 466         for_each_cpu(i, clip_cpus) {
 467                 /* continue if cpufreq policy not found and not return error */
 468                 if (!cpufreq_get_policy(&policy, i))
 469                         continue;
 470                 if (min == 0 && max == 0) {
 471                         min = policy.cpuinfo.min_freq;
 472                         max = policy.cpuinfo.max_freq;
 473                 } else {
 474                         if (min != policy.cpuinfo.min_freq ||
 475                             max != policy.cpuinfo.max_freq)
 476                                 return ERR_PTR(-EINVAL);
 477                 }
 478         }
 479         cpufreq_dev = kzalloc(sizeof(struct cpufreq_cooling_device),
 480                               GFP_KERNEL);
 481         if (!cpufreq_dev)
 482                 return ERR_PTR(-ENOMEM);
 483
 484         cpumask_copy(&cpufreq_dev->allowed_cpus, clip_cpus);
 485
 486         ret = get_idr(&cpufreq_idr, &cpufreq_dev->id);
 487         if (ret) {
 488                 kfree(cpufreq_dev);
 489                 return ERR_PTR(-EINVAL);
 490         }
 491
 492         snprintf(dev_name, sizeof(dev_name), "thermal-cpufreq-%d",
 493                  cpufreq_dev->id);
 494
 495         cool_dev = thermal_of_cooling_device_register(np, dev_name, cpufreq_dev,
 496                                                       &cpufreq_cooling_ops);
 497         if (IS_ERR(cool_dev)) {
 498                 release_idr(&cpufreq_idr, cpufreq_dev->id);
 499                 kfree(cpufreq_dev);
 500                 return cool_dev;
 501         }
 502         cpufreq_dev->cool_dev = cool_dev;
 503         cpufreq_dev->cpufreq_state = 0;
 504         mutex_lock(&cooling_cpufreq_lock);
 505
 506         /* Register the notifier for first cpufreq cooling device */
 507         if (cpufreq_dev_count == 0)
 508                 cpufreq_register_notifier(&thermal_cpufreq_notifier_block,
 509                                           CPUFREQ_POLICY_NOTIFIER);
 510         cpufreq_dev_count++;
 511         list_add(&cpufreq_dev->node, &cpufreq_dev_list);
 512
 513         mutex_unlock(&cooling_cpufreq_lock);
 514
 515         return cool_dev;
 516 }
 517
 518 /**
 519  * cpufreq_cooling_register - function to create cpufreq cooling device.
 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.
 525  *
 526  * Return: a valid struct thermal_cooling_device pointer on success,
 527  * on failure, it returns a corresponding ERR_PTR().
 528  */
 529 struct thermal_cooling_device *
 530 cpufreq_cooling_register(const struct cpumask *clip_cpus)
 531 {
 532         return __cpufreq_cooling_register(NULL, clip_cpus);
 533 }
 534 EXPORT_SYMBOL_GPL(cpufreq_cooling_register);
 535
 536 /**
 537  * of_cpufreq_cooling_register - function to create cpufreq cooling device.
 538  * @np: a valid struct device_node to the cooling device device tree node
 539  * @clip_cpus: cpumask of cpus where the frequency constraints will happen.
 540  *
 541  * This interface function registers the cpufreq cooling device with the name
 542  * "thermal-cpufreq-%x". This api can support multiple instances of cpufreq
 543  * cooling devices. Using this API, the cpufreq cooling device will be
 544  * linked to the device tree node provided.
 545  *
 546  * Return: a valid struct thermal_cooling_device pointer on success,
 547  * on failure, it returns a corresponding ERR_PTR().
 548  */
 549 struct thermal_cooling_device *
 550 of_cpufreq_cooling_register(struct device_node *np,
 551                             const struct cpumask *clip_cpus)
 552 {
 553         if (!np)
 554                 return ERR_PTR(-EINVAL);
 555
 556         return __cpufreq_cooling_register(np, clip_cpus);
 557 }
 558 EXPORT_SYMBOL_GPL(of_cpufreq_cooling_register);
 559
 560 /**
 561  * cpufreq_cooling_unregister - function to remove cpufreq cooling device.
 562  * @cdev: thermal cooling device pointer.
 563  *
 564  * This interface function unregisters the "thermal-cpufreq-%x" cooling device.
 565  */
 566 void cpufreq_cooling_unregister(struct thermal_cooling_device *cdev)
 567 {
 568         struct cpufreq_cooling_device *cpufreq_dev;
 569
 570         if (!cdev)
 571                 return;
 572
 573         cpufreq_dev = cdev->devdata;
 574         mutex_lock(&cooling_cpufreq_lock);
 575         list_del(&cpufreq_dev->node);
 576         cpufreq_dev_count--;
 577
 578         /* Unregister the notifier for the last cpufreq cooling device */
 579         if (cpufreq_dev_count == 0)
 580                 cpufreq_unregister_notifier(&thermal_cpufreq_notifier_block,
 581                                             CPUFREQ_POLICY_NOTIFIER);
 582         mutex_unlock(&cooling_cpufreq_lock);
 583
 584         thermal_cooling_device_unregister(cpufreq_dev->cool_dev);
 585         release_idr(&cpufreq_idr, cpufreq_dev->id);
 586         kfree(cpufreq_dev);
 587 }
 588 EXPORT_SYMBOL_GPL(cpufreq_cooling_unregister);