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 if a cpu has frequency transition policy.
 101  * @cpu: cpu for which check is needed.
 102  */
 103 static int is_cpufreq_valid(int cpu)
 104 {
 105         struct cpufreq_policy policy;
 106         return !cpufreq_get_policy(&policy, cpu);
 107 }
 108
 109 enum cpufreq_cooling_property {
 110         GET_LEVEL,
 111         GET_FREQ,
 112         GET_MAXL,
 113 };
 114
 115 /*
 116  * this is the common function to
 117  * 1. get maximum cpu cooling states
 118  * 2. translate frequency to cooling state
 119  * 3. translate cooling state to frequency
 120  * Note that the code may be not in good shape
 121  * but it is written in this way in order to:
 122  * a) reduce duplicate code as most of the code can be shared.
 123  * b) make sure the logic is consistent when translating between
 124  *    cooling states and frequencies.
 125 */
 126 static int get_property(unsigned int cpu, unsigned long input,
 127         unsigned int* output, enum cpufreq_cooling_property property)
 128 {
 129         int i, j;
 130         unsigned long max_level = 0, level = 0;
 131         unsigned int freq = CPUFREQ_ENTRY_INVALID;
 132         int descend = -1;
 133         struct cpufreq_frequency_table *table =
 134                                         cpufreq_frequency_get_table(cpu);
 135
 136         if (!output)
 137                 return -EINVAL;
 138
 139         if (!table)
 140                 return -EINVAL;
 141
 142
 143         for (i = 0; table[i].frequency != CPUFREQ_TABLE_END; i++) {
 144                 /* ignore invalid entries */
 145                 if (table[i].frequency == CPUFREQ_ENTRY_INVALID)
 146                         continue;
 147
 148                 /* ignore duplicate entry */
 149                 if (freq == table[i].frequency)
 150                         continue;
 151
 152                 /* get the frequency order */
 153                 if (freq != CPUFREQ_ENTRY_INVALID && descend != -1)
 154                         descend = !!(freq > table[i].frequency);
 155
 156                 freq = table[i].frequency;
 157                 max_level++;
 158         }
 159
 160         /* get max level */
 161         if (property == GET_MAXL) {
 162                 *output = (unsigned int)max_level;
 163                 return 0;
 164         }
 165
 166         if (property == GET_FREQ)
 167                 level = descend ? input : (max_level - input -1);
 168
 169
 170         for (i = 0, j = 0; table[i].frequency != CPUFREQ_TABLE_END; i++) {
 171                 /* ignore invalid entry */
 172                 if (table[i].frequency == CPUFREQ_ENTRY_INVALID)
 173                         continue;
 174
 175                 /* ignore duplicate entry */
 176                 if (freq == table[i].frequency)
 177                         continue;
 178
 179                 /* now we have a valid frequency entry */
 180                 freq = table[i].frequency;
 181
 182                 if (property == GET_LEVEL && (unsigned int)input == freq) {
 183                         /* get level by frequency */
 184                         *output = descend ? j : (max_level - j - 1);
 185                         return 0;
 186                 }
 187                 if (property == GET_FREQ && level == j) {
 188                         /* get frequency by level */
 189                         *output = freq;
 190                         return 0;
 191                 }
 192                 j++;
 193         }
 194         return -EINVAL;
 195 }
 196
 197 unsigned long cpufreq_cooling_get_level(unsigned int cpu, unsigned int freq)
 198 {
 199         unsigned int val;
 200
 201         if (get_property(cpu, (unsigned long)freq, &val, GET_LEVEL))
 202                 return THERMAL_CSTATE_INVALID;
 203         return (unsigned long)val;
 204 }
 205 EXPORT_SYMBOL_GPL(cpufreq_cooling_get_level);
 206
 207 /**
 208  * get_cpu_frequency - get the absolute value of frequency from level.
 209  * @cpu: cpu for which frequency is fetched.
 210  * @level: level of frequency, equals cooling state of cpu cooling device
 211  *      e.g level=0 --> 1st MAX FREQ, level=1 ---> 2nd MAX FREQ, .... etc
 212  */
 213 static unsigned int get_cpu_frequency(unsigned int cpu, unsigned long level)
 214 {
 215         int ret = 0;
 216         unsigned int freq;
 217
 218         ret = get_property(cpu, level, &freq, GET_FREQ);
 219         if (ret)
 220                 return 0;
 221         return freq;
 222 }
 223
 224 /**
 225  * cpufreq_apply_cooling - function to apply frequency clipping.
 226  * @cpufreq_device: cpufreq_cooling_device pointer containing frequency
 227  *      clipping data.
 228  * @cooling_state: value of the cooling state.
 229  */
 230 static int cpufreq_apply_cooling(struct cpufreq_cooling_device *cpufreq_device,
 231                                 unsigned long cooling_state)
 232 {
 233         unsigned int cpuid, clip_freq;
 234         struct cpumask *mask = &cpufreq_device->allowed_cpus;
 235         unsigned int cpu = cpumask_any(mask);
 236
 237
 238         /* Check if the old cooling action is same as new cooling action */
 239         if (cpufreq_device->cpufreq_state == cooling_state)
 240                 return 0;
 241
 242         clip_freq = get_cpu_frequency(cpu, cooling_state);
 243         if (!clip_freq)
 244                 return -EINVAL;
 245
 246         cpufreq_device->cpufreq_state = cooling_state;
 247         cpufreq_device->cpufreq_val = clip_freq;
 248         notify_device = cpufreq_device;
 249
 250         for_each_cpu(cpuid, mask) {
 251                 if (is_cpufreq_valid(cpuid))
 252                         cpufreq_update_policy(cpuid);
 253         }
 254
 255         notify_device = NOTIFY_INVALID;
 256
 257         return 0;
 258 }
 259
 260 /**
 261  * cpufreq_thermal_notifier - notifier callback for cpufreq policy change.
 262  * @nb: struct notifier_block * with callback info.
 263  * @event: value showing cpufreq event for which this function invoked.
 264  * @data: callback-specific data
 265  */
 266 static int cpufreq_thermal_notifier(struct notifier_block *nb,
 267                                         unsigned long event, void *data)
 268 {
 269         struct cpufreq_policy *policy = data;
 270         unsigned long max_freq = 0;
 271
 272         if (event != CPUFREQ_ADJUST || notify_device == NOTIFY_INVALID)
 273                 return 0;
 274
 275         if (cpumask_test_cpu(policy->cpu, &notify_device->allowed_cpus))
 276                 max_freq = notify_device->cpufreq_val;
 277
 278         /* Never exceed user_policy.max*/
 279         if (max_freq > policy->user_policy.max)
 280                 max_freq = policy->user_policy.max;
 281
 282         if (policy->max != max_freq)
 283                 cpufreq_verify_within_limits(policy, 0, max_freq);
 284
 285         return 0;
 286 }
 287
 288 /*
 289  * cpufreq cooling device callback functions are defined below
 290  */
 291
 292 /**
 293  * cpufreq_get_max_state - callback function to get the max cooling state.
 294  * @cdev: thermal cooling device pointer.
 295  * @state: fill this variable with the max cooling state.
 296  */
 297 static int cpufreq_get_max_state(struct thermal_cooling_device *cdev,
 298                                  unsigned long *state)
 299 {
 300         struct cpufreq_cooling_device *cpufreq_device = cdev->devdata;
 301         struct cpumask *mask = &cpufreq_device->allowed_cpus;
 302         unsigned int cpu;
 303         unsigned int count = 0;
 304         int ret;
 305
 306         cpu = cpumask_any(mask);
 307
 308         ret = get_property(cpu, 0, &count, GET_MAXL);
 309
 310         if (count > 0)
 311                 *state = count;
 312
 313         return ret;
 314 }
 315
 316 /**
 317  * cpufreq_get_cur_state - callback function to get the current cooling state.
 318  * @cdev: thermal cooling device pointer.
 319  * @state: fill this variable with the current cooling state.
 320  */
 321 static int cpufreq_get_cur_state(struct thermal_cooling_device *cdev,
 322                                  unsigned long *state)
 323 {
 324         struct cpufreq_cooling_device *cpufreq_device = cdev->devdata;
 325
 326         *state = cpufreq_device->cpufreq_state;
 327         return 0;
 328 }
 329
 330 /**
 331  * cpufreq_set_cur_state - callback function to set the current cooling state.
 332  * @cdev: thermal cooling device pointer.
 333  * @state: set this variable to the current cooling state.
 334  */
 335 static int cpufreq_set_cur_state(struct thermal_cooling_device *cdev,
 336                                  unsigned long state)
 337 {
 338         struct cpufreq_cooling_device *cpufreq_device = cdev->devdata;
 339
 340         return cpufreq_apply_cooling(cpufreq_device, state);
 341 }
 342
 343 /* Bind cpufreq callbacks to thermal cooling device ops */
 344 static struct thermal_cooling_device_ops const cpufreq_cooling_ops = {
 345         .get_max_state = cpufreq_get_max_state,
 346         .get_cur_state = cpufreq_get_cur_state,
 347         .set_cur_state = cpufreq_set_cur_state,
 348 };
 349
 350 /* Notifier for cpufreq policy change */
 351 static struct notifier_block thermal_cpufreq_notifier_block = {
 352         .notifier_call = cpufreq_thermal_notifier,
 353 };
 354
 355 /**
 356  * cpufreq_cooling_register - function to create cpufreq cooling device.
 357  * @clip_cpus: cpumask of cpus where the frequency constraints will happen.
 358  */
 359 struct thermal_cooling_device *cpufreq_cooling_register(
 360         const struct cpumask *clip_cpus)
 361 {
 362         struct thermal_cooling_device *cool_dev;
 363         struct cpufreq_cooling_device *cpufreq_dev = NULL;
 364         unsigned int min = 0, max = 0;
 365         char dev_name[THERMAL_NAME_LENGTH];
 366         int ret = 0, i;
 367         struct cpufreq_policy policy;
 368
 369         /*Verify that all the clip cpus have same freq_min, freq_max limit*/
 370         for_each_cpu(i, clip_cpus) {
 371                 /*continue if cpufreq policy not found and not return error*/
 372                 if (!cpufreq_get_policy(&policy, i))
 373                         continue;
 374                 if (min == 0 && max == 0) {
 375                         min = policy.cpuinfo.min_freq;
 376                         max = policy.cpuinfo.max_freq;
 377                 } else {
 378                         if (min != policy.cpuinfo.min_freq ||
 379                                 max != policy.cpuinfo.max_freq)
 380                                 return ERR_PTR(-EINVAL);
 381                 }
 382         }
 383         cpufreq_dev = kzalloc(sizeof(struct cpufreq_cooling_device),
 384                         GFP_KERNEL);
 385         if (!cpufreq_dev)
 386                 return ERR_PTR(-ENOMEM);
 387
 388         cpumask_copy(&cpufreq_dev->allowed_cpus, clip_cpus);
 389
 390         ret = get_idr(&cpufreq_idr, &cpufreq_dev->id);
 391         if (ret) {
 392                 kfree(cpufreq_dev);
 393                 return ERR_PTR(-EINVAL);
 394         }
 395
 396         sprintf(dev_name, "thermal-cpufreq-%d", cpufreq_dev->id);
 397
 398         cool_dev = thermal_cooling_device_register(dev_name, cpufreq_dev,
 399                                                 &cpufreq_cooling_ops);
 400         if (!cool_dev) {
 401                 release_idr(&cpufreq_idr, cpufreq_dev->id);
 402                 kfree(cpufreq_dev);
 403                 return ERR_PTR(-EINVAL);
 404         }
 405         cpufreq_dev->cool_dev = cool_dev;
 406         cpufreq_dev->cpufreq_state = 0;
 407         mutex_lock(&cooling_cpufreq_lock);
 408
 409         /* Register the notifier for first cpufreq cooling device */
 410         if (cpufreq_dev_count == 0)
 411                 cpufreq_register_notifier(&thermal_cpufreq_notifier_block,
 412                                                 CPUFREQ_POLICY_NOTIFIER);
 413         cpufreq_dev_count++;
 414
 415         mutex_unlock(&cooling_cpufreq_lock);
 416         return cool_dev;
 417 }
 418 EXPORT_SYMBOL_GPL(cpufreq_cooling_register);
 419
 420 /**
 421  * cpufreq_cooling_unregister - function to remove cpufreq cooling device.
 422  * @cdev: thermal cooling device pointer.
 423  */
 424 void cpufreq_cooling_unregister(struct thermal_cooling_device *cdev)
 425 {
 426         struct cpufreq_cooling_device *cpufreq_dev = cdev->devdata;
 427
 428         mutex_lock(&cooling_cpufreq_lock);
 429         cpufreq_dev_count--;
 430
 431         /* Unregister the notifier for the last cpufreq cooling device */
 432         if (cpufreq_dev_count == 0) {
 433                 cpufreq_unregister_notifier(&thermal_cpufreq_notifier_block,
 434                                         CPUFREQ_POLICY_NOTIFIER);
 435         }
 436         mutex_unlock(&cooling_cpufreq_lock);
 437
 438         thermal_cooling_device_unregister(cpufreq_dev->cool_dev);
 439         release_idr(&cpufreq_idr, cpufreq_dev->id);
 440         kfree(cpufreq_dev);
 441 }
 442 EXPORT_SYMBOL_GPL(cpufreq_cooling_unregister);