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 };
  54 static DEFINE_IDR(cpufreq_idr);
  55 static DEFINE_MUTEX(cooling_cpufreq_lock);
  56
  57 static unsigned int cpufreq_dev_count;
  58
  59 /* notify_table passes value to the CPUFREQ_ADJUST callback function. */
  60 #define NOTIFY_INVALID NULL
  61 static struct cpufreq_cooling_device *notify_device;
  62
  63 /**
  64  * get_idr - function to get a unique id.
  65  * @idr: struct idr * handle used to create a id.
  66  * @id: int * value generated by this function.
  67  *
  68  * This function will populate @id with an unique
  69  * id, using the idr API.
  70  *
  71  * Return: 0 on success, an error code on failure.
  72  */
  73 static int get_idr(struct idr *idr, int *id)
  74 {
  75         int ret;
  76
  77         mutex_lock(&cooling_cpufreq_lock);
  78         ret = idr_alloc(idr, NULL, 0, 0, GFP_KERNEL);
  79         mutex_unlock(&cooling_cpufreq_lock);
  80         if (unlikely(ret < 0))
  81                 return ret;
  82         *id = ret;
  83
  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  */
  92 static 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 frequency transitioning capability.
 103  * @cpu: cpu for which check is needed.
 104  *
 105  * This function will check the current state of the system if
 106  * it is capable of changing the frequency for a given @cpu.
 107  *
 108  * Return: 0 if the system is not currently capable of changing
 109  * the frequency of given cpu. !0 in case the frequency is changeable.
 110  */
 111 static int is_cpufreq_valid(int cpu)
 112 {
 113         struct cpufreq_policy policy;
 114
 115         return !cpufreq_get_policy(&policy, cpu);
 116 }
 117
 118 enum cpufreq_cooling_property {
 119         GET_LEVEL,
 120         GET_FREQ,
 121         GET_MAXL,
 122 };
 123
 124 /**
 125  * get_property - fetch a property of interest for a give cpu.
 126  * @cpu: cpu for which the property is required
 127  * @input: query parameter
 128  * @output: query return
 129  * @property: type of query (frequency, level, max level)
 130  *
 131  * This is the common function to
 132  * 1. get maximum cpu cooling states
 133  * 2. translate frequency to cooling state
 134  * 3. translate cooling state to frequency
 135  * Note that the code may be not in good shape
 136  * but it is written in this way in order to:
 137  * a) reduce duplicate code as most of the code can be shared.
 138  * b) make sure the logic is consistent when translating between
 139  *    cooling states and frequencies.
 140  *
 141  * Return: 0 on success, -EINVAL when invalid parameters are passed.
 142  */
 143 static int get_property(unsigned int cpu, unsigned long input,
 144                         unsigned int *output,
 145                         enum cpufreq_cooling_property property)
 146 {
 147         int i, j;
 148         unsigned long max_level = 0, level = 0;
 149         unsigned int freq = CPUFREQ_ENTRY_INVALID;
 150         int descend = -1;
 151         struct cpufreq_frequency_table *table =
 152                                         cpufreq_frequency_get_table(cpu);
 153
 154         if (!output)
 155                 return -EINVAL;
 156
 157         if (!table)
 158                 return -EINVAL;
 159
 160         for (i = 0; table[i].frequency != CPUFREQ_TABLE_END; i++) {
 161                 /* ignore invalid entries */
 162                 if (table[i].frequency == CPUFREQ_ENTRY_INVALID)
 163                         continue;
 164
 165                 /* ignore duplicate entry */
 166                 if (freq == table[i].frequency)
 167                         continue;
 168
 169                 /* get the frequency order */
 170                 if (freq != CPUFREQ_ENTRY_INVALID && descend == -1)
 171                         descend = !!(freq > table[i].frequency);
 172
 173                 freq = table[i].frequency;
 174                 max_level++;
 175         }
 176
 177         /* No valid cpu frequency entry */
 178         if (max_level == 0)
 179                 return -EINVAL;
 180
 181         /* max_level is an index, not a counter */
 182         max_level--;
 183
 184         /* get max level */
 185         if (property == GET_MAXL) {
 186                 *output = (unsigned int)max_level;
 187                 return 0;
 188         }
 189
 190         if (property == GET_FREQ)
 191                 level = descend ? input : (max_level - input);
 192
 193         for (i = 0, j = 0; table[i].frequency != CPUFREQ_TABLE_END; i++) {
 194                 /* ignore invalid entry */
 195                 if (table[i].frequency == CPUFREQ_ENTRY_INVALID)
 196                         continue;
 197
 198                 /* ignore duplicate entry */
 199                 if (freq == table[i].frequency)
 200                         continue;
 201
 202                 /* now we have a valid frequency entry */
 203                 freq = table[i].frequency;
 204
 205                 if (property == GET_LEVEL && (unsigned int)input == freq) {
 206                         /* get level by frequency */
 207                         *output = descend ? j : (max_level - j);
 208                         return 0;
 209                 }
 210                 if (property == GET_FREQ && level == j) {
 211                         /* get frequency by level */
 212                         *output = freq;
 213                         return 0;
 214                 }
 215                 j++;
 216         }
 217
 218         return -EINVAL;
 219 }
 220
 221 /**
 222  * cpufreq_cooling_get_level - for a give cpu, return the cooling level.
 223  * @cpu: cpu for which the level is required
 224  * @freq: the frequency of interest
 225  *
 226  * This function will match the cooling level corresponding to the
 227  * requested @freq and return it.
 228  *
 229  * Return: The matched cooling level on success or THERMAL_CSTATE_INVALID
 230  * otherwise.
 231  */
 232 unsigned long cpufreq_cooling_get_level(unsigned int cpu, unsigned int freq)
 233 {
 234         unsigned int val;
 235
 236         if (get_property(cpu, (unsigned long)freq, &val, GET_LEVEL))
 237                 return THERMAL_CSTATE_INVALID;
 238
 239         return (unsigned long)val;
 240 }
 241 EXPORT_SYMBOL_GPL(cpufreq_cooling_get_level);
 242
 243 /**
 244  * get_cpu_frequency - get the absolute value of frequency from level.
 245  * @cpu: cpu for which frequency is fetched.
 246  * @level: cooling level
 247  *
 248  * This function matches cooling level with frequency. Based on a cooling level
 249  * of frequency, equals cooling state of cpu cooling device, it will return
 250  * the corresponding frequency.
 251  *      e.g level=0 --> 1st MAX FREQ, level=1 ---> 2nd MAX FREQ, .... etc
 252  *
 253  * Return: 0 on error, the corresponding frequency otherwise.
 254  */
 255 static unsigned int get_cpu_frequency(unsigned int cpu, unsigned long level)
 256 {
 257         int ret = 0;
 258         unsigned int freq;
 259
 260         ret = get_property(cpu, level, &freq, GET_FREQ);
 261         if (ret)
 262                 return 0;
 263
 264         return freq;
 265 }
 266
 267 /**
 268  * cpufreq_apply_cooling - function to apply frequency clipping.
 269  * @cpufreq_device: cpufreq_cooling_device pointer containing frequency
 270  *      clipping data.
 271  * @cooling_state: value of the cooling state.
 272  *
 273  * Function used to make sure the cpufreq layer is aware of current thermal
 274  * limits. The limits are applied by updating the cpufreq policy.
 275  *
 276  * Return: 0 on success, an error code otherwise (-EINVAL in case wrong
 277  * cooling state).
 278  */
 279 static int cpufreq_apply_cooling(struct cpufreq_cooling_device *cpufreq_device,
 280                                  unsigned long cooling_state)
 281 {
 282         unsigned int cpuid, clip_freq;
 283         struct cpumask *mask = &cpufreq_device->allowed_cpus;
 284         unsigned int cpu = cpumask_any(mask);
 285
 286
 287         /* Check if the old cooling action is same as new cooling action */
 288         if (cpufreq_device->cpufreq_state == cooling_state)
 289                 return 0;
 290
 291         clip_freq = get_cpu_frequency(cpu, cooling_state);
 292         if (!clip_freq)
 293                 return -EINVAL;
 294
 295         cpufreq_device->cpufreq_state = cooling_state;
 296         cpufreq_device->cpufreq_val = clip_freq;
 297         notify_device = cpufreq_device;
 298
 299         for_each_cpu(cpuid, mask) {
 300                 if (is_cpufreq_valid(cpuid))
 301                         cpufreq_update_policy(cpuid);
 302         }
 303
 304         notify_device = NOTIFY_INVALID;
 305
 306         return 0;
 307 }
 308
 309 /**
 310  * cpufreq_thermal_notifier - notifier callback for cpufreq policy change.
 311  * @nb: struct notifier_block * with callback info.
 312  * @event: value showing cpufreq event for which this function invoked.
 313  * @data: callback-specific data
 314  *
 315  * Callback to highjack the notification on cpufreq policy transition.
 316  * Every time there is a change in policy, we will intercept and
 317  * update the cpufreq policy with thermal constraints.
 318  *
 319  * Return: 0 (success)
 320  */
 321 static int cpufreq_thermal_notifier(struct notifier_block *nb,
 322                                     unsigned long event, void *data)
 323 {
 324         struct cpufreq_policy *policy = data;
 325         unsigned long max_freq = 0;
 326
 327         if (event != CPUFREQ_ADJUST || notify_device == NOTIFY_INVALID)
 328                 return 0;
 329
 330         if (cpumask_test_cpu(policy->cpu, &notify_device->allowed_cpus))
 331                 max_freq = notify_device->cpufreq_val;
 332         else
 333                 return 0;
 334
 335         /* Never exceed user_policy.max */
 336         if (max_freq > policy->user_policy.max)
 337                 max_freq = policy->user_policy.max;
 338
 339         if (policy->max != max_freq)
 340                 cpufreq_verify_within_limits(policy, 0, max_freq);
 341
 342         return 0;
 343 }
 344
 345 /* cpufreq cooling device callback functions are defined below */
 346
 347 /**
 348  * cpufreq_get_max_state - callback function to get the max cooling state.
 349  * @cdev: thermal cooling device pointer.
 350  * @state: fill this variable with the max cooling state.
 351  *
 352  * Callback for the thermal cooling device to return the cpufreq
 353  * max cooling state.
 354  *
 355  * Return: 0 on success, an error code otherwise.
 356  */
 357 static int cpufreq_get_max_state(struct thermal_cooling_device *cdev,
 358                                  unsigned long *state)
 359 {
 360         struct cpufreq_cooling_device *cpufreq_device = cdev->devdata;
 361         struct cpumask *mask = &cpufreq_device->allowed_cpus;
 362         unsigned int cpu;
 363         unsigned int count = 0;
 364         int ret;
 365
 366         cpu = cpumask_any(mask);
 367
 368         ret = get_property(cpu, 0, &count, GET_MAXL);
 369
 370         if (count > 0)
 371                 *state = count;
 372
 373         return ret;
 374 }
 375
 376 /**
 377  * cpufreq_get_cur_state - callback function to get the current cooling state.
 378  * @cdev: thermal cooling device pointer.
 379  * @state: fill this variable with the current cooling state.
 380  *
 381  * Callback for the thermal cooling device to return the cpufreq
 382  * current cooling state.
 383  *
 384  * Return: 0 on success, an error code otherwise.
 385  */
 386 static int cpufreq_get_cur_state(struct thermal_cooling_device *cdev,
 387                                  unsigned long *state)
 388 {
 389         struct cpufreq_cooling_device *cpufreq_device = cdev->devdata;
 390
 391         *state = cpufreq_device->cpufreq_state;
 392
 393         return 0;
 394 }
 395
 396 /**
 397  * cpufreq_set_cur_state - callback function to set the current cooling state.
 398  * @cdev: thermal cooling device pointer.
 399  * @state: set this variable to the current cooling state.
 400  *
 401  * Callback for the thermal cooling device to change the cpufreq
 402  * current cooling state.
 403  *
 404  * Return: 0 on success, an error code otherwise.
 405  */
 406 static int cpufreq_set_cur_state(struct thermal_cooling_device *cdev,
 407                                  unsigned long state)
 408 {
 409         struct cpufreq_cooling_device *cpufreq_device = cdev->devdata;
 410
 411         return cpufreq_apply_cooling(cpufreq_device, state);
 412 }
 413
 414 /* Bind cpufreq callbacks to thermal cooling device ops */
 415 static struct thermal_cooling_device_ops const cpufreq_cooling_ops = {
 416         .get_max_state = cpufreq_get_max_state,
 417         .get_cur_state = cpufreq_get_cur_state,
 418         .set_cur_state = cpufreq_set_cur_state,
 419 };
 420
 421 /* Notifier for cpufreq policy change */
 422 static struct notifier_block thermal_cpufreq_notifier_block = {
 423         .notifier_call = cpufreq_thermal_notifier,
 424 };
 425
 426 /**
 427  * __cpufreq_cooling_register - helper function to create cpufreq cooling device
 428  * @np: a valid struct device_node to the cooling device device tree node
 429  * @clip_cpus: cpumask of cpus where the frequency constraints will happen.
 430  *
 431  * This interface function registers the cpufreq cooling device with the name
 432  * "thermal-cpufreq-%x". This api can support multiple instances of cpufreq
 433  * cooling devices. It also gives the opportunity to link the cooling device
 434  * with a device tree node, in order to bind it via the thermal DT code.
 435  *
 436  * Return: a valid struct thermal_cooling_device pointer on success,
 437  * on failure, it returns a corresponding ERR_PTR().
 438  */
 439 static struct thermal_cooling_device *
 440 __cpufreq_cooling_register(struct device_node *np,
 441                            const struct cpumask *clip_cpus)
 442 {
 443         struct thermal_cooling_device *cool_dev;
 444         struct cpufreq_cooling_device *cpufreq_dev = NULL;
 445         unsigned int min = 0, max = 0;
 446         char dev_name[THERMAL_NAME_LENGTH];
 447         int ret = 0, i;
 448         struct cpufreq_policy policy;
 449
 450         /* Verify that all the clip cpus have same freq_min, freq_max limit */
 451         for_each_cpu(i, clip_cpus) {
 452                 /* continue if cpufreq policy not found and not return error */
 453                 if (!cpufreq_get_policy(&policy, i))
 454                         continue;
 455                 if (min == 0 && max == 0) {
 456                         min = policy.cpuinfo.min_freq;
 457                         max = policy.cpuinfo.max_freq;
 458                 } else {
 459                         if (min != policy.cpuinfo.min_freq ||
 460                             max != policy.cpuinfo.max_freq)
 461                                 return ERR_PTR(-EINVAL);
 462                 }
 463         }
 464         cpufreq_dev = kzalloc(sizeof(struct cpufreq_cooling_device),
 465                               GFP_KERNEL);
 466         if (!cpufreq_dev)
 467                 return ERR_PTR(-ENOMEM);
 468
 469         cpumask_copy(&cpufreq_dev->allowed_cpus, clip_cpus);
 470
 471         ret = get_idr(&cpufreq_idr, &cpufreq_dev->id);
 472         if (ret) {
 473                 kfree(cpufreq_dev);
 474                 return ERR_PTR(-EINVAL);
 475         }
 476
 477         snprintf(dev_name, sizeof(dev_name), "thermal-cpufreq-%d",
 478                  cpufreq_dev->id);
 479
 480         cool_dev = thermal_of_cooling_device_register(np, dev_name, cpufreq_dev,
 481                                                       &cpufreq_cooling_ops);
 482         if (IS_ERR(cool_dev)) {
 483                 release_idr(&cpufreq_idr, cpufreq_dev->id);
 484                 kfree(cpufreq_dev);
 485                 return cool_dev;
 486         }
 487         cpufreq_dev->cool_dev = cool_dev;
 488         cpufreq_dev->cpufreq_state = 0;
 489         mutex_lock(&cooling_cpufreq_lock);
 490
 491         /* Register the notifier for first cpufreq cooling device */
 492         if (cpufreq_dev_count == 0)
 493                 cpufreq_register_notifier(&thermal_cpufreq_notifier_block,
 494                                           CPUFREQ_POLICY_NOTIFIER);
 495         cpufreq_dev_count++;
 496
 497         mutex_unlock(&cooling_cpufreq_lock);
 498
 499         return cool_dev;
 500 }
 501
 502 /**
 503  * cpufreq_cooling_register - function to create cpufreq cooling device.
 504  * @clip_cpus: cpumask of cpus where the frequency constraints will happen.
 505  *
 506  * This interface function registers the cpufreq cooling device with the name
 507  * "thermal-cpufreq-%x". This api can support multiple instances of cpufreq
 508  * cooling devices.
 509  *
 510  * Return: a valid struct thermal_cooling_device pointer on success,
 511  * on failure, it returns a corresponding ERR_PTR().
 512  */
 513 struct thermal_cooling_device *
 514 cpufreq_cooling_register(const struct cpumask *clip_cpus)
 515 {
 516         return __cpufreq_cooling_register(NULL, clip_cpus);
 517 }
 518 EXPORT_SYMBOL_GPL(cpufreq_cooling_register);
 519
 520 /**
 521  * of_cpufreq_cooling_register - function to create cpufreq cooling device.
 522  * @np: a valid struct device_node to the cooling device device tree node
 523  * @clip_cpus: cpumask of cpus where the frequency constraints will happen.
 524  *
 525  * This interface function registers the cpufreq cooling device with the name
 526  * "thermal-cpufreq-%x". This api can support multiple instances of cpufreq
 527  * cooling devices. Using this API, the cpufreq cooling device will be
 528  * linked to the device tree node provided.
 529  *
 530  * Return: a valid struct thermal_cooling_device pointer on success,
 531  * on failure, it returns a corresponding ERR_PTR().
 532  */
 533 struct thermal_cooling_device *
 534 of_cpufreq_cooling_register(struct device_node *np,
 535                             const struct cpumask *clip_cpus)
 536 {
 537         if (!np)
 538                 return ERR_PTR(-EINVAL);
 539
 540         return __cpufreq_cooling_register(np, clip_cpus);
 541 }
 542 EXPORT_SYMBOL_GPL(of_cpufreq_cooling_register);
 543
 544 /**
 545  * cpufreq_cooling_unregister - function to remove cpufreq cooling device.
 546  * @cdev: thermal cooling device pointer.
 547  *
 548  * This interface function unregisters the "thermal-cpufreq-%x" cooling device.
 549  */
 550 void cpufreq_cooling_unregister(struct thermal_cooling_device *cdev)
 551 {
 552         struct cpufreq_cooling_device *cpufreq_dev;
 553
 554         if (!cdev)
 555                 return;
 556
 557         cpufreq_dev = cdev->devdata;
 558         mutex_lock(&cooling_cpufreq_lock);
 559         cpufreq_dev_count--;
 560
 561         /* Unregister the notifier for the last cpufreq cooling device */
 562         if (cpufreq_dev_count == 0)
 563                 cpufreq_unregister_notifier(&thermal_cpufreq_notifier_block,
 564                                             CPUFREQ_POLICY_NOTIFIER);
 565         mutex_unlock(&cooling_cpufreq_lock);
 566
 567         thermal_cooling_device_unregister(cpufreq_dev->cool_dev);
 568         release_idr(&cpufreq_idr, cpufreq_dev->id);
 569         kfree(cpufreq_dev);
 570 }
 571 EXPORT_SYMBOL_GPL(cpufreq_cooling_unregister);