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