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