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/kernel.h>
  24 #include <linux/module.h>
  25 #include <linux/thermal.h>
  26 #include <linux/platform_device.h>
  27 #include <linux/cpufreq.h>
  28 #include <linux/err.h>
  29 #include <linux/slab.h>
  30 #include <linux/cpu.h>
  31 #include <linux/cpu_cooling.h>
  32
  33 /**
  34  * struct cpufreq_cooling_device
  35  * @id: unique integer value corresponding to each cpufreq_cooling_device
  36  *      registered.
  37  * @cool_dev: thermal_cooling_device pointer to keep track of the the
  38  *      egistered cooling device.
  39  * @cpufreq_state: integer value representing the current state of cpufreq
  40  *      cooling devices.
  41  * @cpufreq_val: integer value representing the absolute value of the clipped
  42  *      frequency.
  43  * @allowed_cpus: all the cpus involved for this cpufreq_cooling_device.
  44  * @node: list_head to link all cpufreq_cooling_device together.
  45  *
  46  * This structure is required for keeping information of each
  47  * cpufreq_cooling_device registered as a list whose head is represented by
  48  * cooling_cpufreq_list. In order to prevent corruption of this list a
  49  * mutex lock cooling_cpufreq_lock is used.
  50  */
  51 struct cpufreq_cooling_device {
  52         int id;
  53         struct thermal_cooling_device *cool_dev;
  54         unsigned int cpufreq_state;
  55         unsigned int cpufreq_val;
  56         struct cpumask allowed_cpus;
  57         struct list_head node;
  58 };
  59 static LIST_HEAD(cooling_cpufreq_list);
  60 static DEFINE_IDR(cpufreq_idr);
  61 static DEFINE_MUTEX(cooling_cpufreq_lock);
  62
  63 static unsigned int cpufreq_dev_count;
  64
  65 /* notify_table passes value to the CPUFREQ_ADJUST callback function. */
  66 #define NOTIFY_INVALID NULL
  67 static struct cpufreq_cooling_device *notify_device;
  68
  69 /**
  70  * get_idr - function to get a unique id.
  71  * @idr: struct idr * handle used to create a id.
  72  * @id: int * value generated by this function.
  73  */
  74 static int get_idr(struct idr *idr, int *id)
  75 {
  76         int err;
  77 again:
  78         if (unlikely(idr_pre_get(idr, GFP_KERNEL) == 0))
  79                 return -ENOMEM;
  80
  81         mutex_lock(&cooling_cpufreq_lock);
  82         err = idr_get_new(idr, NULL, id);
  83         mutex_unlock(&cooling_cpufreq_lock);
  84
  85         if (unlikely(err == -EAGAIN))
  86                 goto again;
  87         else if (unlikely(err))
  88                 return err;
  89
  90         *id = *id & MAX_IDR_MASK;
  91         return 0;
  92 }
  93
  94 /**
  95  * release_idr - function to free the unique id.
  96  * @idr: struct idr * handle used for creating the id.
  97  * @id: int value representing the unique id.
  98  */
  99 static void release_idr(struct idr *idr, int id)
 100 {
 101         mutex_lock(&cooling_cpufreq_lock);
 102         idr_remove(idr, id);
 103         mutex_unlock(&cooling_cpufreq_lock);
 104 }
 105
 106 /* Below code defines functions to be used for cpufreq as cooling device */
 107
 108 /**
 109  * is_cpufreq_valid - function to check if a cpu has frequency transition policy.
 110  * @cpu: cpu for which check is needed.
 111  */
 112 static int is_cpufreq_valid(int cpu)
 113 {
 114         struct cpufreq_policy policy;
 115         return !cpufreq_get_policy(&policy, cpu);
 116 }
 117
 118 /**
 119  * get_cpu_frequency - get the absolute value of frequency from level.
 120  * @cpu: cpu for which frequency is fetched.
 121  * @level: level of frequency of the CPU
 122  *      e.g level=1 --> 1st MAX FREQ, LEVEL=2 ---> 2nd MAX FREQ, .... etc
 123  */
 124 static unsigned int get_cpu_frequency(unsigned int cpu, unsigned long level)
 125 {
 126         int ret = 0, i = 0;
 127         unsigned long level_index;
 128         bool descend = false;
 129         struct cpufreq_frequency_table *table =
 130                                         cpufreq_frequency_get_table(cpu);
 131         if (!table)
 132                 return ret;
 133
 134         while (table[i].frequency != CPUFREQ_TABLE_END) {
 135                 if (table[i].frequency == CPUFREQ_ENTRY_INVALID)
 136                         continue;
 137
 138                 /*check if table in ascending or descending order*/
 139                 if ((table[i + 1].frequency != CPUFREQ_TABLE_END) &&
 140                         (table[i + 1].frequency < table[i].frequency)
 141                         && !descend) {
 142                         descend = true;
 143                 }
 144
 145                 /*return if level matched and table in descending order*/
 146                 if (descend && i == level)
 147                         return table[i].frequency;
 148                 i++;
 149         }
 150         i--;
 151
 152         if (level > i || descend)
 153                 return ret;
 154         level_index = i - level;
 155
 156         /*Scan the table in reverse order and match the level*/
 157         while (i >= 0) {
 158                 if (table[i].frequency == CPUFREQ_ENTRY_INVALID)
 159                         continue;
 160                 /*return if level matched*/
 161                 if (i == level_index)
 162                         return table[i].frequency;
 163                 i--;
 164         }
 165         return ret;
 166 }
 167
 168 /**
 169  * cpufreq_apply_cooling - function to apply frequency clipping.
 170  * @cpufreq_device: cpufreq_cooling_device pointer containing frequency
 171  *      clipping data.
 172  * @cooling_state: value of the cooling state.
 173  */
 174 static int cpufreq_apply_cooling(struct cpufreq_cooling_device *cpufreq_device,
 175                                 unsigned long cooling_state)
 176 {
 177         unsigned int cpuid, clip_freq;
 178         struct cpumask *maskPtr = &cpufreq_device->allowed_cpus;
 179         unsigned int cpu = cpumask_any(maskPtr);
 180
 181
 182         /* Check if the old cooling action is same as new cooling action */
 183         if (cpufreq_device->cpufreq_state == cooling_state)
 184                 return 0;
 185
 186         clip_freq = get_cpu_frequency(cpu, cooling_state);
 187         if (!clip_freq)
 188                 return -EINVAL;
 189
 190         cpufreq_device->cpufreq_state = cooling_state;
 191         cpufreq_device->cpufreq_val = clip_freq;
 192         notify_device = cpufreq_device;
 193
 194         for_each_cpu(cpuid, maskPtr) {
 195                 if (is_cpufreq_valid(cpuid))
 196                         cpufreq_update_policy(cpuid);
 197         }
 198
 199         notify_device = NOTIFY_INVALID;
 200
 201         return 0;
 202 }
 203
 204 /**
 205  * cpufreq_thermal_notifier - notifier callback for cpufreq policy change.
 206  * @nb: struct notifier_block * with callback info.
 207  * @event: value showing cpufreq event for which this function invoked.
 208  * @data: callback-specific data
 209  */
 210 static int cpufreq_thermal_notifier(struct notifier_block *nb,
 211                                         unsigned long event, void *data)
 212 {
 213         struct cpufreq_policy *policy = data;
 214         unsigned long max_freq = 0;
 215
 216         if (event != CPUFREQ_ADJUST || notify_device == NOTIFY_INVALID)
 217                 return 0;
 218
 219         if (cpumask_test_cpu(policy->cpu, &notify_device->allowed_cpus))
 220                 max_freq = notify_device->cpufreq_val;
 221
 222         /* Never exceed user_policy.max*/
 223         if (max_freq > policy->user_policy.max)
 224                 max_freq = policy->user_policy.max;
 225
 226         if (policy->max != max_freq)
 227                 cpufreq_verify_within_limits(policy, 0, max_freq);
 228
 229         return 0;
 230 }
 231
 232 /*
 233  * cpufreq cooling device callback functions are defined below
 234  */
 235
 236 /**
 237  * cpufreq_get_max_state - callback function to get the max cooling state.
 238  * @cdev: thermal cooling device pointer.
 239  * @state: fill this variable with the max cooling state.
 240  */
 241 static int cpufreq_get_max_state(struct thermal_cooling_device *cdev,
 242                                  unsigned long *state)
 243 {
 244         struct cpufreq_cooling_device *cpufreq_device = cdev->devdata;
 245         struct cpumask *maskPtr = &cpufreq_device->allowed_cpus;
 246         unsigned int cpu;
 247         struct cpufreq_frequency_table *table;
 248         unsigned long count = 0;
 249         int i = 0;
 250
 251         cpu = cpumask_any(maskPtr);
 252         table = cpufreq_frequency_get_table(cpu);
 253         if (!table) {
 254                 *state = 0;
 255                 return 0;
 256         }
 257
 258         for (i = 0; (table[i].frequency != CPUFREQ_TABLE_END); i++) {
 259                 if (table[i].frequency == CPUFREQ_ENTRY_INVALID)
 260                         continue;
 261                 count++;
 262         }
 263
 264         if (count > 0) {
 265                 *state = --count;
 266                 return 0;
 267         }
 268
 269         return -EINVAL;
 270 }
 271
 272 /**
 273  * cpufreq_get_cur_state - callback function to get the current cooling state.
 274  * @cdev: thermal cooling device pointer.
 275  * @state: fill this variable with the current cooling state.
 276  */
 277 static int cpufreq_get_cur_state(struct thermal_cooling_device *cdev,
 278                                  unsigned long *state)
 279 {
 280         struct cpufreq_cooling_device *cpufreq_device = cdev->devdata;
 281
 282         *state = cpufreq_device->cpufreq_state;
 283         return 0;
 284 }
 285
 286 /**
 287  * cpufreq_set_cur_state - callback function to set the current cooling state.
 288  * @cdev: thermal cooling device pointer.
 289  * @state: set this variable to the current cooling state.
 290  */
 291 static int cpufreq_set_cur_state(struct thermal_cooling_device *cdev,
 292                                  unsigned long state)
 293 {
 294         struct cpufreq_cooling_device *cpufreq_device = cdev->devdata;
 295
 296         return cpufreq_apply_cooling(cpufreq_device, state);
 297 }
 298
 299 /* Bind cpufreq callbacks to thermal cooling device ops */
 300 static struct thermal_cooling_device_ops const cpufreq_cooling_ops = {
 301         .get_max_state = cpufreq_get_max_state,
 302         .get_cur_state = cpufreq_get_cur_state,
 303         .set_cur_state = cpufreq_set_cur_state,
 304 };
 305
 306 /* Notifier for cpufreq policy change */
 307 static struct notifier_block thermal_cpufreq_notifier_block = {
 308         .notifier_call = cpufreq_thermal_notifier,
 309 };
 310
 311 /**
 312  * cpufreq_cooling_register - function to create cpufreq cooling device.
 313  * @clip_cpus: cpumask of cpus where the frequency constraints will happen.
 314  */
 315 struct thermal_cooling_device *cpufreq_cooling_register(
 316         const struct cpumask *clip_cpus)
 317 {
 318         struct thermal_cooling_device *cool_dev;
 319         struct cpufreq_cooling_device *cpufreq_dev = NULL;
 320         unsigned int min = 0, max = 0;
 321         char dev_name[THERMAL_NAME_LENGTH];
 322         int ret = 0, i;
 323         struct cpufreq_policy policy;
 324
 325         /*Verify that all the clip cpus have same freq_min, freq_max limit*/
 326         for_each_cpu(i, clip_cpus) {
 327                 /*continue if cpufreq policy not found and not return error*/
 328                 if (!cpufreq_get_policy(&policy, i))
 329                         continue;
 330                 if (min == 0 && max == 0) {
 331                         min = policy.cpuinfo.min_freq;
 332                         max = policy.cpuinfo.max_freq;
 333                 } else {
 334                         if (min != policy.cpuinfo.min_freq ||
 335                                 max != policy.cpuinfo.max_freq)
 336                                 return ERR_PTR(-EINVAL);
 337                 }
 338         }
 339         cpufreq_dev = kzalloc(sizeof(struct cpufreq_cooling_device),
 340                         GFP_KERNEL);
 341         if (!cpufreq_dev)
 342                 return ERR_PTR(-ENOMEM);
 343
 344         cpumask_copy(&cpufreq_dev->allowed_cpus, clip_cpus);
 345
 346         ret = get_idr(&cpufreq_idr, &cpufreq_dev->id);
 347         if (ret) {
 348                 kfree(cpufreq_dev);
 349                 return ERR_PTR(-EINVAL);
 350         }
 351
 352         sprintf(dev_name, "thermal-cpufreq-%d", cpufreq_dev->id);
 353
 354         cool_dev = thermal_cooling_device_register(dev_name, cpufreq_dev,
 355                                                 &cpufreq_cooling_ops);
 356         if (!cool_dev) {
 357                 release_idr(&cpufreq_idr, cpufreq_dev->id);
 358                 kfree(cpufreq_dev);
 359                 return ERR_PTR(-EINVAL);
 360         }
 361         cpufreq_dev->cool_dev = cool_dev;
 362         cpufreq_dev->cpufreq_state = 0;
 363         mutex_lock(&cooling_cpufreq_lock);
 364
 365         /* Register the notifier for first cpufreq cooling device */
 366         if (cpufreq_dev_count == 0)
 367                 cpufreq_register_notifier(&thermal_cpufreq_notifier_block,
 368                                                 CPUFREQ_POLICY_NOTIFIER);
 369         cpufreq_dev_count++;
 370
 371         mutex_unlock(&cooling_cpufreq_lock);
 372         return cool_dev;
 373 }
 374 EXPORT_SYMBOL(cpufreq_cooling_register);
 375
 376 /**
 377  * cpufreq_cooling_unregister - function to remove cpufreq cooling device.
 378  * @cdev: thermal cooling device pointer.
 379  */
 380 void cpufreq_cooling_unregister(struct thermal_cooling_device *cdev)
 381 {
 382         struct cpufreq_cooling_device *cpufreq_dev = cdev->devdata;
 383
 384         mutex_lock(&cooling_cpufreq_lock);
 385         cpufreq_dev_count--;
 386
 387         /* Unregister the notifier for the last cpufreq cooling device */
 388         if (cpufreq_dev_count == 0) {
 389                 cpufreq_unregister_notifier(&thermal_cpufreq_notifier_block,
 390                                         CPUFREQ_POLICY_NOTIFIER);
 391         }
 392         mutex_unlock(&cooling_cpufreq_lock);
 393
 394         thermal_cooling_device_unregister(cpufreq_dev->cool_dev);
 395         release_idr(&cpufreq_idr, cpufreq_dev->id);
 396         kfree(cpufreq_dev);
 397 }
 398 EXPORT_SYMBOL(cpufreq_cooling_unregister);