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  * this is the common function to
 123  * 1. get maximum cpu cooling states
 124  * 2. translate frequency to cooling state
 125  * 3. translate cooling state to frequency
 126  * Note that the code may be not in good shape
 127  * but it is written in this way in order to:
 128  * a) reduce duplicate code as most of the code can be shared.
 129  * b) make sure the logic is consistent when translating between
 130  *    cooling states and frequencies.
 131 */
 132 static int get_property(unsigned int cpu, unsigned long input,
 133         unsigned int* output, enum cpufreq_cooling_property property)
 134 {
 135         int i, j;
 136         unsigned long max_level = 0, level = 0;
 137         unsigned int freq = CPUFREQ_ENTRY_INVALID;
 138         int descend = -1;
 139         struct cpufreq_frequency_table *table =
 140                                         cpufreq_frequency_get_table(cpu);
 141
 142         if (!output)
 143                 return -EINVAL;
 144
 145         if (!table)
 146                 return -EINVAL;
 147
 148
 149         for (i = 0; table[i].frequency != CPUFREQ_TABLE_END; i++) {
 150                 /* ignore invalid entries */
 151                 if (table[i].frequency == CPUFREQ_ENTRY_INVALID)
 152                         continue;
 153
 154                 /* ignore duplicate entry */
 155                 if (freq == table[i].frequency)
 156                         continue;
 157
 158                 /* get the frequency order */
 159                 if (freq != CPUFREQ_ENTRY_INVALID && descend != -1)
 160                         descend = !!(freq > table[i].frequency);
 161
 162                 freq = table[i].frequency;
 163                 max_level++;
 164         }
 165
 166         /* get max level */
 167         if (property == GET_MAXL) {
 168                 *output = (unsigned int)max_level;
 169                 return 0;
 170         }
 171
 172         if (property == GET_FREQ)
 173                 level = descend ? input : (max_level - input -1);
 174
 175
 176         for (i = 0, j = 0; table[i].frequency != CPUFREQ_TABLE_END; i++) {
 177                 /* ignore invalid entry */
 178                 if (table[i].frequency == CPUFREQ_ENTRY_INVALID)
 179                         continue;
 180
 181                 /* ignore duplicate entry */
 182                 if (freq == table[i].frequency)
 183                         continue;
 184
 185                 /* now we have a valid frequency entry */
 186                 freq = table[i].frequency;
 187
 188                 if (property == GET_LEVEL && (unsigned int)input == freq) {
 189                         /* get level by frequency */
 190                         *output = descend ? j : (max_level - j - 1);
 191                         return 0;
 192                 }
 193                 if (property == GET_FREQ && level == j) {
 194                         /* get frequency by level */
 195                         *output = freq;
 196                         return 0;
 197                 }
 198                 j++;
 199         }
 200         return -EINVAL;
 201 }
 202
 203 unsigned long cpufreq_cooling_get_level(unsigned int cpu, unsigned int freq)
 204 {
 205         unsigned int val;
 206
 207         if (get_property(cpu, (unsigned long)freq, &val, GET_LEVEL))
 208                 return THERMAL_CSTATE_INVALID;
 209         return (unsigned long)val;
 210 }
 211 EXPORT_SYMBOL_GPL(cpufreq_cooling_get_level);
 212
 213 /**
 214  * get_cpu_frequency - get the absolute value of frequency from level.
 215  * @cpu: cpu for which frequency is fetched.
 216  * @level: level of frequency, equals cooling state of cpu cooling device
 217  *      e.g level=0 --> 1st MAX FREQ, level=1 ---> 2nd MAX FREQ, .... etc
 218  */
 219 static unsigned int get_cpu_frequency(unsigned int cpu, unsigned long level)
 220 {
 221         int ret = 0;
 222         unsigned int freq;
 223
 224         ret = get_property(cpu, level, &freq, GET_FREQ);
 225         if (ret)
 226                 return 0;
 227         return freq;
 228 }
 229
 230 /**
 231  * cpufreq_apply_cooling - function to apply frequency clipping.
 232  * @cpufreq_device: cpufreq_cooling_device pointer containing frequency
 233  *      clipping data.
 234  * @cooling_state: value of the cooling state.
 235  */
 236 static int cpufreq_apply_cooling(struct cpufreq_cooling_device *cpufreq_device,
 237                                 unsigned long cooling_state)
 238 {
 239         unsigned int cpuid, clip_freq;
 240         struct cpumask *mask = &cpufreq_device->allowed_cpus;
 241         unsigned int cpu = cpumask_any(mask);
 242
 243
 244         /* Check if the old cooling action is same as new cooling action */
 245         if (cpufreq_device->cpufreq_state == cooling_state)
 246                 return 0;
 247
 248         clip_freq = get_cpu_frequency(cpu, cooling_state);
 249         if (!clip_freq)
 250                 return -EINVAL;
 251
 252         cpufreq_device->cpufreq_state = cooling_state;
 253         cpufreq_device->cpufreq_val = clip_freq;
 254         notify_device = cpufreq_device;
 255
 256         for_each_cpu(cpuid, mask) {
 257                 if (is_cpufreq_valid(cpuid))
 258                         cpufreq_update_policy(cpuid);
 259         }
 260
 261         notify_device = NOTIFY_INVALID;
 262
 263         return 0;
 264 }
 265
 266 /**
 267  * cpufreq_thermal_notifier - notifier callback for cpufreq policy change.
 268  * @nb: struct notifier_block * with callback info.
 269  * @event: value showing cpufreq event for which this function invoked.
 270  * @data: callback-specific data
 271  */
 272 static int cpufreq_thermal_notifier(struct notifier_block *nb,
 273                                         unsigned long event, void *data)
 274 {
 275         struct cpufreq_policy *policy = data;
 276         unsigned long max_freq = 0;
 277
 278         if (event != CPUFREQ_ADJUST || notify_device == NOTIFY_INVALID)
 279                 return 0;
 280
 281         if (cpumask_test_cpu(policy->cpu, &notify_device->allowed_cpus))
 282                 max_freq = notify_device->cpufreq_val;
 283
 284         /* Never exceed user_policy.max*/
 285         if (max_freq > policy->user_policy.max)
 286                 max_freq = policy->user_policy.max;
 287
 288         if (policy->max != max_freq)
 289                 cpufreq_verify_within_limits(policy, 0, max_freq);
 290
 291         return 0;
 292 }
 293
 294 /*
 295  * cpufreq cooling device callback functions are defined below
 296  */
 297
 298 /**
 299  * cpufreq_get_max_state - callback function to get the max cooling state.
 300  * @cdev: thermal cooling device pointer.
 301  * @state: fill this variable with the max cooling state.
 302  */
 303 static int cpufreq_get_max_state(struct thermal_cooling_device *cdev,
 304                                  unsigned long *state)
 305 {
 306         struct cpufreq_cooling_device *cpufreq_device = cdev->devdata;
 307         struct cpumask *mask = &cpufreq_device->allowed_cpus;
 308         unsigned int cpu;
 309         unsigned int count = 0;
 310         int ret;
 311
 312         cpu = cpumask_any(mask);
 313
 314         ret = get_property(cpu, 0, &count, GET_MAXL);
 315
 316         if (count > 0)
 317                 *state = count;
 318
 319         return ret;
 320 }
 321
 322 /**
 323  * cpufreq_get_cur_state - callback function to get the current cooling state.
 324  * @cdev: thermal cooling device pointer.
 325  * @state: fill this variable with the current cooling state.
 326  */
 327 static int cpufreq_get_cur_state(struct thermal_cooling_device *cdev,
 328                                  unsigned long *state)
 329 {
 330         struct cpufreq_cooling_device *cpufreq_device = cdev->devdata;
 331
 332         *state = cpufreq_device->cpufreq_state;
 333         return 0;
 334 }
 335
 336 /**
 337  * cpufreq_set_cur_state - callback function to set the current cooling state.
 338  * @cdev: thermal cooling device pointer.
 339  * @state: set this variable to the current cooling state.
 340  */
 341 static int cpufreq_set_cur_state(struct thermal_cooling_device *cdev,
 342                                  unsigned long state)
 343 {
 344         struct cpufreq_cooling_device *cpufreq_device = cdev->devdata;
 345
 346         return cpufreq_apply_cooling(cpufreq_device, state);
 347 }
 348
 349 /* Bind cpufreq callbacks to thermal cooling device ops */
 350 static struct thermal_cooling_device_ops const cpufreq_cooling_ops = {
 351         .get_max_state = cpufreq_get_max_state,
 352         .get_cur_state = cpufreq_get_cur_state,
 353         .set_cur_state = cpufreq_set_cur_state,
 354 };
 355
 356 /* Notifier for cpufreq policy change */
 357 static struct notifier_block thermal_cpufreq_notifier_block = {
 358         .notifier_call = cpufreq_thermal_notifier,
 359 };
 360
 361 /**
 362  * cpufreq_cooling_register - function to create cpufreq cooling device.
 363  * @clip_cpus: cpumask of cpus where the frequency constraints will happen.
 364  */
 365 struct thermal_cooling_device *cpufreq_cooling_register(
 366         const struct cpumask *clip_cpus)
 367 {
 368         struct thermal_cooling_device *cool_dev;
 369         struct cpufreq_cooling_device *cpufreq_dev = NULL;
 370         unsigned int min = 0, max = 0;
 371         char dev_name[THERMAL_NAME_LENGTH];
 372         int ret = 0, i;
 373         struct cpufreq_policy policy;
 374
 375         /*Verify that all the clip cpus have same freq_min, freq_max limit*/
 376         for_each_cpu(i, clip_cpus) {
 377                 /*continue if cpufreq policy not found and not return error*/
 378                 if (!cpufreq_get_policy(&policy, i))
 379                         continue;
 380                 if (min == 0 && max == 0) {
 381                         min = policy.cpuinfo.min_freq;
 382                         max = policy.cpuinfo.max_freq;
 383                 } else {
 384                         if (min != policy.cpuinfo.min_freq ||
 385                                 max != policy.cpuinfo.max_freq)
 386                                 return ERR_PTR(-EINVAL);
 387                 }
 388         }
 389         cpufreq_dev = kzalloc(sizeof(struct cpufreq_cooling_device),
 390                         GFP_KERNEL);
 391         if (!cpufreq_dev)
 392                 return ERR_PTR(-ENOMEM);
 393
 394         cpumask_copy(&cpufreq_dev->allowed_cpus, clip_cpus);
 395
 396         ret = get_idr(&cpufreq_idr, &cpufreq_dev->id);
 397         if (ret) {
 398                 kfree(cpufreq_dev);
 399                 return ERR_PTR(-EINVAL);
 400         }
 401
 402         sprintf(dev_name, "thermal-cpufreq-%d", cpufreq_dev->id);
 403
 404         cool_dev = thermal_cooling_device_register(dev_name, cpufreq_dev,
 405                                                 &cpufreq_cooling_ops);
 406         if (!cool_dev) {
 407                 release_idr(&cpufreq_idr, cpufreq_dev->id);
 408                 kfree(cpufreq_dev);
 409                 return ERR_PTR(-EINVAL);
 410         }
 411         cpufreq_dev->cool_dev = cool_dev;
 412         cpufreq_dev->cpufreq_state = 0;
 413         mutex_lock(&cooling_cpufreq_lock);
 414
 415         /* Register the notifier for first cpufreq cooling device */
 416         if (cpufreq_dev_count == 0)
 417                 cpufreq_register_notifier(&thermal_cpufreq_notifier_block,
 418                                                 CPUFREQ_POLICY_NOTIFIER);
 419         cpufreq_dev_count++;
 420
 421         mutex_unlock(&cooling_cpufreq_lock);
 422         return cool_dev;
 423 }
 424 EXPORT_SYMBOL_GPL(cpufreq_cooling_register);
 425
 426 /**
 427  * cpufreq_cooling_unregister - function to remove cpufreq cooling device.
 428  * @cdev: thermal cooling device pointer.
 429  */
 430 void cpufreq_cooling_unregister(struct thermal_cooling_device *cdev)
 431 {
 432         struct cpufreq_cooling_device *cpufreq_dev = cdev->devdata;
 433
 434         mutex_lock(&cooling_cpufreq_lock);
 435         cpufreq_dev_count--;
 436
 437         /* Unregister the notifier for the last cpufreq cooling device */
 438         if (cpufreq_dev_count == 0) {
 439                 cpufreq_unregister_notifier(&thermal_cpufreq_notifier_block,
 440                                         CPUFREQ_POLICY_NOTIFIER);
 441         }
 442         mutex_unlock(&cooling_cpufreq_lock);
 443
 444         thermal_cooling_device_unregister(cpufreq_dev->cool_dev);
 445         release_idr(&cpufreq_idr, cpufreq_dev->id);
 446         kfree(cpufreq_dev);
 447 }
 448 EXPORT_SYMBOL_GPL(cpufreq_cooling_unregister);