drivers/devfreq/devfreq.c

   1 /*
   2  * devfreq: Generic Dynamic Voltage and Frequency Scaling (DVFS) Framework
   3  *          for Non-CPU Devices.
   4  *
   5  * Copyright (C) 2011 Samsung Electronics
   6  *      MyungJoo Ham <myungjoo.ham@samsung.com>
   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 version 2 as
  10  * published by the Free Software Foundation.
  11  */
  12
  13 #include <linux/kernel.h>
  14 #include <linux/sched.h>
  15 #include <linux/errno.h>
  16 #include <linux/err.h>
  17 #include <linux/init.h>
  18 #include <linux/export.h>
  19 #include <linux/slab.h>
  20 #include <linux/stat.h>
  21 #include <linux/pm_opp.h>
  22 #include <linux/devfreq.h>
  23 #include <linux/workqueue.h>
  24 #include <linux/platform_device.h>
  25 #include <linux/list.h>
  26 #include <linux/printk.h>
  27 #include <linux/hrtimer.h>
  28 #include <linux/of.h>
  29 #include "governor.h"
  30
  31 static struct class *devfreq_class;
  32
  33 /*
  34  * devfreq core provides delayed work based load monitoring helper
  35  * functions. Governors can use these or can implement their own
  36  * monitoring mechanism.
  37  */
  38 static struct workqueue_struct *devfreq_wq;
  39
  40 /* The list of all device-devfreq governors */
  41 static LIST_HEAD(devfreq_governor_list);
  42 /* The list of all device-devfreq */
  43 static LIST_HEAD(devfreq_list);
  44 static DEFINE_MUTEX(devfreq_list_lock);
  45
  46 /**
  47  * find_device_devfreq() - find devfreq struct using device pointer
  48  * @dev:        device pointer used to lookup device devfreq.
  49  *
  50  * Search the list of device devfreqs and return the matched device's
  51  * devfreq info. devfreq_list_lock should be held by the caller.
  52  */
  53 static struct devfreq *find_device_devfreq(struct device *dev)
  54 {
  55         struct devfreq *tmp_devfreq;
  56
  57         if (IS_ERR_OR_NULL(dev)) {
  58                 pr_err("DEVFREQ: %s: Invalid parameters\n", __func__);
  59                 return ERR_PTR(-EINVAL);
  60         }
  61         WARN(!mutex_is_locked(&devfreq_list_lock),
  62              "devfreq_list_lock must be locked.");
  63
  64         list_for_each_entry(tmp_devfreq, &devfreq_list, node) {
  65                 if (tmp_devfreq->dev.parent == dev)
  66                         return tmp_devfreq;
  67         }
  68
  69         return ERR_PTR(-ENODEV);
  70 }
  71
  72 /**
  73  * devfreq_get_freq_level() - Lookup freq_table for the frequency
  74  * @devfreq:    the devfreq instance
  75  * @freq:       the target frequency
  76  */
  77 static int devfreq_get_freq_level(struct devfreq *devfreq, unsigned long freq)
  78 {
  79         int lev;
  80
  81         for (lev = 0; lev < devfreq->profile->max_state; lev++)
  82                 if (freq == devfreq->profile->freq_table[lev])
  83                         return lev;
  84
  85         return -EINVAL;
  86 }
  87
  88 /**
  89  * devfreq_set_freq_table() - Initialize freq_table for the frequency
  90  * @devfreq:    the devfreq instance
  91  */
  92 static void devfreq_set_freq_table(struct devfreq *devfreq)
  93 {
  94         struct devfreq_dev_profile *profile = devfreq->profile;
  95         struct dev_pm_opp *opp;
  96         unsigned long freq;
  97         int i, count;
  98
  99         /* Initialize the freq_table from OPP table */
 100         count = dev_pm_opp_get_opp_count(devfreq->dev.parent);
 101         if (count <= 0)
 102                 return;
 103
 104         profile->max_state = count;
 105         profile->freq_table = devm_kcalloc(devfreq->dev.parent,
 106                                         profile->max_state,
 107                                         sizeof(*profile->freq_table),
 108                                         GFP_KERNEL);
 109         if (!profile->freq_table) {
 110                 profile->max_state = 0;
 111                 return;
 112         }
 113
 114         rcu_read_lock();
 115         for (i = 0, freq = 0; i < profile->max_state; i++, freq++) {
 116                 opp = dev_pm_opp_find_freq_ceil(devfreq->dev.parent, &freq);
 117                 if (IS_ERR(opp)) {
 118                         devm_kfree(devfreq->dev.parent, profile->freq_table);
 119                         profile->max_state = 0;
 120                         rcu_read_unlock();
 121                         return;
 122                 }
 123                 profile->freq_table[i] = freq;
 124         }
 125         rcu_read_unlock();
 126 }
 127
 128 /**
 129  * devfreq_update_status() - Update statistics of devfreq behavior
 130  * @devfreq:    the devfreq instance
 131  * @freq:       the update target frequency
 132  */
 133 static int devfreq_update_status(struct devfreq *devfreq, unsigned long freq)
 134 {
 135         int lev, prev_lev, ret = 0;
 136         unsigned long cur_time;
 137
 138         cur_time = jiffies;
 139
 140         /* Immediately exit if previous_freq is not initialized yet. */
 141         if (!devfreq->previous_freq)
 142                 goto out;
 143
 144         prev_lev = devfreq_get_freq_level(devfreq, devfreq->previous_freq);
 145         if (prev_lev < 0) {
 146                 ret = prev_lev;
 147                 goto out;
 148         }
 149
 150         devfreq->time_in_state[prev_lev] +=
 151                          cur_time - devfreq->last_stat_updated;
 152
 153         lev = devfreq_get_freq_level(devfreq, freq);
 154         if (lev < 0) {
 155                 ret = lev;
 156                 goto out;
 157         }
 158
 159         if (lev != prev_lev) {
 160                 devfreq->trans_table[(prev_lev *
 161                                 devfreq->profile->max_state) + lev]++;
 162                 devfreq->total_trans++;
 163         }
 164
 165 out:
 166         devfreq->last_stat_updated = cur_time;
 167         return ret;
 168 }
 169
 170 /**
 171  * find_devfreq_governor() - find devfreq governor from name
 172  * @name:       name of the governor
 173  *
 174  * Search the list of devfreq governors and return the matched
 175  * governor's pointer. devfreq_list_lock should be held by the caller.
 176  */
 177 static struct devfreq_governor *find_devfreq_governor(const char *name)
 178 {
 179         struct devfreq_governor *tmp_governor;
 180
 181         if (IS_ERR_OR_NULL(name)) {
 182                 pr_err("DEVFREQ: %s: Invalid parameters\n", __func__);
 183                 return ERR_PTR(-EINVAL);
 184         }
 185         WARN(!mutex_is_locked(&devfreq_list_lock),
 186              "devfreq_list_lock must be locked.");
 187
 188         list_for_each_entry(tmp_governor, &devfreq_governor_list, node) {
 189                 if (!strncmp(tmp_governor->name, name, DEVFREQ_NAME_LEN))
 190                         return tmp_governor;
 191         }
 192
 193         return ERR_PTR(-ENODEV);
 194 }
 195
 196 static int devfreq_notify_transition(struct devfreq *devfreq,
 197                 struct devfreq_freqs *freqs, unsigned int state)
 198 {
 199         if (!devfreq)
 200                 return -EINVAL;
 201
 202         switch (state) {
 203         case DEVFREQ_PRECHANGE:
 204                 srcu_notifier_call_chain(&devfreq->transition_notifier_list,
 205                                 DEVFREQ_PRECHANGE, freqs);
 206                 break;
 207
 208         case DEVFREQ_POSTCHANGE:
 209                 srcu_notifier_call_chain(&devfreq->transition_notifier_list,
 210                                 DEVFREQ_POSTCHANGE, freqs);
 211                 break;
 212         default:
 213                 return -EINVAL;
 214         }
 215
 216         return 0;
 217 }
 218
 219 /* Load monitoring helper functions for governors use */
 220
 221 /**
 222  * update_devfreq() - Reevaluate the device and configure frequency.
 223  * @devfreq:    the devfreq instance.
 224  *
 225  * Note: Lock devfreq->lock before calling update_devfreq
 226  *       This function is exported for governors.
 227  */
 228 int update_devfreq(struct devfreq *devfreq)
 229 {
 230         struct devfreq_freqs freqs;
 231         unsigned long freq, cur_freq;
 232         int err = 0;
 233         u32 flags = 0;
 234
 235         if (!mutex_is_locked(&devfreq->lock)) {
 236                 WARN(true, "devfreq->lock must be locked by the caller.\n");
 237                 return -EINVAL;
 238         }
 239
 240         if (!devfreq->governor)
 241                 return -EINVAL;
 242
 243         /* Reevaluate the proper frequency */
 244         err = devfreq->governor->get_target_freq(devfreq, &freq);
 245         if (err)
 246                 return err;
 247
 248         /*
 249          * Adjust the frequency with user freq and QoS.
 250          *
 251          * List from the highest priority
 252          * max_freq
 253          * min_freq
 254          */
 255
 256         if (devfreq->min_freq && freq < devfreq->min_freq) {
 257                 freq = devfreq->min_freq;
 258                 flags &= ~DEVFREQ_FLAG_LEAST_UPPER_BOUND; /* Use GLB */
 259         }
 260         if (devfreq->max_freq && freq > devfreq->max_freq) {
 261                 freq = devfreq->max_freq;
 262                 flags |= DEVFREQ_FLAG_LEAST_UPPER_BOUND; /* Use LUB */
 263         }
 264
 265         if (devfreq->profile->get_cur_freq)
 266                 devfreq->profile->get_cur_freq(devfreq->dev.parent, &cur_freq);
 267         else
 268                 cur_freq = devfreq->previous_freq;
 269
 270         freqs.old = cur_freq;
 271         freqs.new = freq;
 272         devfreq_notify_transition(devfreq, &freqs, DEVFREQ_PRECHANGE);
 273
 274         err = devfreq->profile->target(devfreq->dev.parent, &freq, flags);
 275         if (err) {
 276                 freqs.new = cur_freq;
 277                 devfreq_notify_transition(devfreq, &freqs, DEVFREQ_POSTCHANGE);
 278                 return err;
 279         }
 280
 281         freqs.new = freq;
 282         devfreq_notify_transition(devfreq, &freqs, DEVFREQ_POSTCHANGE);
 283
 284         if (devfreq->profile->freq_table)
 285                 if (devfreq_update_status(devfreq, freq))
 286                         dev_err(&devfreq->dev,
 287                                 "Couldn't update frequency transition information.\n");
 288
 289         devfreq->previous_freq = freq;
 290         return err;
 291 }
 292 EXPORT_SYMBOL(update_devfreq);
 293
 294 /**
 295  * devfreq_monitor() - Periodically poll devfreq objects.
 296  * @work:       the work struct used to run devfreq_monitor periodically.
 297  *
 298  */
 299 static void devfreq_monitor(struct work_struct *work)
 300 {
 301         int err;
 302         struct devfreq *devfreq = container_of(work,
 303                                         struct devfreq, work.work);
 304
 305         mutex_lock(&devfreq->lock);
 306         err = update_devfreq(devfreq);
 307         if (err)
 308                 dev_err(&devfreq->dev, "dvfs failed with (%d) error\n", err);
 309
 310         queue_delayed_work(devfreq_wq, &devfreq->work,
 311                                 msecs_to_jiffies(devfreq->profile->polling_ms));
 312         mutex_unlock(&devfreq->lock);
 313 }
 314
 315 /**
 316  * devfreq_monitor_start() - Start load monitoring of devfreq instance
 317  * @devfreq:    the devfreq instance.
 318  *
 319  * Helper function for starting devfreq device load monitoing. By
 320  * default delayed work based monitoring is supported. Function
 321  * to be called from governor in response to DEVFREQ_GOV_START
 322  * event when device is added to devfreq framework.
 323  */
 324 void devfreq_monitor_start(struct devfreq *devfreq)
 325 {
 326         INIT_DEFERRABLE_WORK(&devfreq->work, devfreq_monitor);
 327         if (devfreq->profile->polling_ms)
 328                 queue_delayed_work(devfreq_wq, &devfreq->work,
 329                         msecs_to_jiffies(devfreq->profile->polling_ms));
 330 }
 331 EXPORT_SYMBOL(devfreq_monitor_start);
 332
 333 /**
 334  * devfreq_monitor_stop() - Stop load monitoring of a devfreq instance
 335  * @devfreq:    the devfreq instance.
 336  *
 337  * Helper function to stop devfreq device load monitoing. Function
 338  * to be called from governor in response to DEVFREQ_GOV_STOP
 339  * event when device is removed from devfreq framework.
 340  */
 341 void devfreq_monitor_stop(struct devfreq *devfreq)
 342 {
 343         cancel_delayed_work_sync(&devfreq->work);
 344 }
 345 EXPORT_SYMBOL(devfreq_monitor_stop);
 346
 347 /**
 348  * devfreq_monitor_suspend() - Suspend load monitoring of a devfreq instance
 349  * @devfreq:    the devfreq instance.
 350  *
 351  * Helper function to suspend devfreq device load monitoing. Function
 352  * to be called from governor in response to DEVFREQ_GOV_SUSPEND
 353  * event or when polling interval is set to zero.
 354  *
 355  * Note: Though this function is same as devfreq_monitor_stop(),
 356  * intentionally kept separate to provide hooks for collecting
 357  * transition statistics.
 358  */
 359 void devfreq_monitor_suspend(struct devfreq *devfreq)
 360 {
 361         mutex_lock(&devfreq->lock);
 362         if (devfreq->stop_polling) {
 363                 mutex_unlock(&devfreq->lock);
 364                 return;
 365         }
 366
 367         devfreq_update_status(devfreq, devfreq->previous_freq);
 368         devfreq->stop_polling = true;
 369         mutex_unlock(&devfreq->lock);
 370         cancel_delayed_work_sync(&devfreq->work);
 371 }
 372 EXPORT_SYMBOL(devfreq_monitor_suspend);
 373
 374 /**
 375  * devfreq_monitor_resume() - Resume load monitoring of a devfreq instance
 376  * @devfreq:    the devfreq instance.
 377  *
 378  * Helper function to resume devfreq device load monitoing. Function
 379  * to be called from governor in response to DEVFREQ_GOV_RESUME
 380  * event or when polling interval is set to non-zero.
 381  */
 382 void devfreq_monitor_resume(struct devfreq *devfreq)
 383 {
 384         unsigned long freq;
 385
 386         mutex_lock(&devfreq->lock);
 387         if (!devfreq->stop_polling)
 388                 goto out;
 389
 390         if (!delayed_work_pending(&devfreq->work) &&
 391                         devfreq->profile->polling_ms)
 392                 queue_delayed_work(devfreq_wq, &devfreq->work,
 393                         msecs_to_jiffies(devfreq->profile->polling_ms));
 394
 395         devfreq->last_stat_updated = jiffies;
 396         devfreq->stop_polling = false;
 397
 398         if (devfreq->profile->get_cur_freq &&
 399                 !devfreq->profile->get_cur_freq(devfreq->dev.parent, &freq))
 400                 devfreq->previous_freq = freq;
 401
 402 out:
 403         mutex_unlock(&devfreq->lock);
 404 }
 405 EXPORT_SYMBOL(devfreq_monitor_resume);
 406
 407 /**
 408  * devfreq_interval_update() - Update device devfreq monitoring interval
 409  * @devfreq:    the devfreq instance.
 410  * @delay:      new polling interval to be set.
 411  *
 412  * Helper function to set new load monitoring polling interval. Function
 413  * to be called from governor in response to DEVFREQ_GOV_INTERVAL event.
 414  */
 415 void devfreq_interval_update(struct devfreq *devfreq, unsigned int *delay)
 416 {
 417         unsigned int cur_delay = devfreq->profile->polling_ms;
 418         unsigned int new_delay = *delay;
 419
 420         mutex_lock(&devfreq->lock);
 421         devfreq->profile->polling_ms = new_delay;
 422
 423         if (devfreq->stop_polling)
 424                 goto out;
 425
 426         /* if new delay is zero, stop polling */
 427         if (!new_delay) {
 428                 mutex_unlock(&devfreq->lock);
 429                 cancel_delayed_work_sync(&devfreq->work);
 430                 return;
 431         }
 432
 433         /* if current delay is zero, start polling with new delay */
 434         if (!cur_delay) {
 435                 queue_delayed_work(devfreq_wq, &devfreq->work,
 436                         msecs_to_jiffies(devfreq->profile->polling_ms));
 437                 goto out;
 438         }
 439
 440         /* if current delay is greater than new delay, restart polling */
 441         if (cur_delay > new_delay) {
 442                 mutex_unlock(&devfreq->lock);
 443                 cancel_delayed_work_sync(&devfreq->work);
 444                 mutex_lock(&devfreq->lock);
 445                 if (!devfreq->stop_polling)
 446                         queue_delayed_work(devfreq_wq, &devfreq->work,
 447                               msecs_to_jiffies(devfreq->profile->polling_ms));
 448         }
 449 out:
 450         mutex_unlock(&devfreq->lock);
 451 }
 452 EXPORT_SYMBOL(devfreq_interval_update);
 453
 454 /**
 455  * devfreq_notifier_call() - Notify that the device frequency requirements
 456  *                         has been changed out of devfreq framework.
 457  * @nb:         the notifier_block (supposed to be devfreq->nb)
 458  * @type:       not used
 459  * @devp:       not used
 460  *
 461  * Called by a notifier that uses devfreq->nb.
 462  */
 463 static int devfreq_notifier_call(struct notifier_block *nb, unsigned long type,
 464                                  void *devp)
 465 {
 466         struct devfreq *devfreq = container_of(nb, struct devfreq, nb);
 467         int ret;
 468
 469         mutex_lock(&devfreq->lock);
 470         ret = update_devfreq(devfreq);
 471         mutex_unlock(&devfreq->lock);
 472
 473         return ret;
 474 }
 475
 476 /**
 477  * _remove_devfreq() - Remove devfreq from the list and release its resources.
 478  * @devfreq:    the devfreq struct
 479  */
 480 static void _remove_devfreq(struct devfreq *devfreq)
 481 {
 482         mutex_lock(&devfreq_list_lock);
 483         if (IS_ERR(find_device_devfreq(devfreq->dev.parent))) {
 484                 mutex_unlock(&devfreq_list_lock);
 485                 dev_warn(&devfreq->dev, "releasing devfreq which doesn't exist\n");
 486                 return;
 487         }
 488         list_del(&devfreq->node);
 489         mutex_unlock(&devfreq_list_lock);
 490
 491         if (devfreq->governor)
 492                 devfreq->governor->event_handler(devfreq,
 493                                                  DEVFREQ_GOV_STOP, NULL);
 494
 495         if (devfreq->profile->exit)
 496                 devfreq->profile->exit(devfreq->dev.parent);
 497
 498         mutex_destroy(&devfreq->lock);
 499         kfree(devfreq);
 500 }
 501
 502 /**
 503  * devfreq_dev_release() - Callback for struct device to release the device.
 504  * @dev:        the devfreq device
 505  *
 506  * This calls _remove_devfreq() if _remove_devfreq() is not called.
 507  */
 508 static void devfreq_dev_release(struct device *dev)
 509 {
 510         struct devfreq *devfreq = to_devfreq(dev);
 511
 512         _remove_devfreq(devfreq);
 513 }
 514
 515 /**
 516  * devfreq_add_device() - Add devfreq feature to the device
 517  * @dev:        the device to add devfreq feature.
 518  * @profile:    device-specific profile to run devfreq.
 519  * @governor_name:      name of the policy to choose frequency.
 520  * @data:       private data for the governor. The devfreq framework does not
 521  *              touch this value.
 522  */
 523 struct devfreq *devfreq_add_device(struct device *dev,
 524                                    struct devfreq_dev_profile *profile,
 525                                    const char *governor_name,
 526                                    void *data)
 527 {
 528         struct devfreq *devfreq;
 529         struct devfreq_governor *governor;
 530         int err = 0;
 531
 532         if (!dev || !profile || !governor_name) {
 533                 dev_err(dev, "%s: Invalid parameters.\n", __func__);
 534                 return ERR_PTR(-EINVAL);
 535         }
 536
 537         mutex_lock(&devfreq_list_lock);
 538         devfreq = find_device_devfreq(dev);
 539         mutex_unlock(&devfreq_list_lock);
 540         if (!IS_ERR(devfreq)) {
 541                 dev_err(dev, "%s: Unable to create devfreq for the device. It already has one.\n", __func__);
 542                 err = -EINVAL;
 543                 goto err_out;
 544         }
 545
 546         devfreq = kzalloc(sizeof(struct devfreq), GFP_KERNEL);
 547         if (!devfreq) {
 548                 dev_err(dev, "%s: Unable to create devfreq for the device\n",
 549                         __func__);
 550                 err = -ENOMEM;
 551                 goto err_out;
 552         }
 553
 554         mutex_init(&devfreq->lock);
 555         mutex_lock(&devfreq->lock);
 556         devfreq->dev.parent = dev;
 557         devfreq->dev.class = devfreq_class;
 558         devfreq->dev.release = devfreq_dev_release;
 559         devfreq->profile = profile;
 560         strncpy(devfreq->governor_name, governor_name, DEVFREQ_NAME_LEN);
 561         devfreq->previous_freq = profile->initial_freq;
 562         devfreq->last_status.current_frequency = profile->initial_freq;
 563         devfreq->data = data;
 564         devfreq->nb.notifier_call = devfreq_notifier_call;
 565
 566         if (!devfreq->profile->max_state && !devfreq->profile->freq_table) {
 567                 mutex_unlock(&devfreq->lock);
 568                 devfreq_set_freq_table(devfreq);
 569                 mutex_lock(&devfreq->lock);
 570         }
 571
 572         dev_set_name(&devfreq->dev, "%s", dev_name(dev));
 573         err = device_register(&devfreq->dev);
 574         if (err) {
 575                 mutex_unlock(&devfreq->lock);
 576                 goto err_out;
 577         }
 578
 579         devfreq->trans_table =  devm_kzalloc(&devfreq->dev, sizeof(unsigned int) *
 580                                                 devfreq->profile->max_state *
 581                                                 devfreq->profile->max_state,
 582                                                 GFP_KERNEL);
 583         devfreq->time_in_state = devm_kzalloc(&devfreq->dev, sizeof(unsigned long) *
 584                                                 devfreq->profile->max_state,
 585                                                 GFP_KERNEL);
 586         devfreq->last_stat_updated = jiffies;
 587
 588         srcu_init_notifier_head(&devfreq->transition_notifier_list);
 589
 590         mutex_unlock(&devfreq->lock);
 591
 592         mutex_lock(&devfreq_list_lock);
 593         list_add(&devfreq->node, &devfreq_list);
 594
 595         governor = find_devfreq_governor(devfreq->governor_name);
 596         if (IS_ERR(governor)) {
 597                 dev_err(dev, "%s: Unable to find governor for the device\n",
 598                         __func__);
 599                 err = PTR_ERR(governor);
 600                 goto err_init;
 601         }
 602
 603         devfreq->governor = governor;
 604         err = devfreq->governor->event_handler(devfreq, DEVFREQ_GOV_START,
 605                                                 NULL);
 606         if (err) {
 607                 dev_err(dev, "%s: Unable to start governor for the device\n",
 608                         __func__);
 609                 goto err_init;
 610         }
 611         mutex_unlock(&devfreq_list_lock);
 612
 613         return devfreq;
 614
 615 err_init:
 616         list_del(&devfreq->node);
 617         mutex_unlock(&devfreq_list_lock);
 618
 619         device_unregister(&devfreq->dev);
 620 err_out:
 621         return ERR_PTR(err);
 622 }
 623 EXPORT_SYMBOL(devfreq_add_device);
 624
 625 /**
 626  * devfreq_remove_device() - Remove devfreq feature from a device.
 627  * @devfreq:    the devfreq instance to be removed
 628  *
 629  * The opposite of devfreq_add_device().
 630  */
 631 int devfreq_remove_device(struct devfreq *devfreq)
 632 {
 633         if (!devfreq)
 634                 return -EINVAL;
 635
 636         device_unregister(&devfreq->dev);
 637
 638         return 0;
 639 }
 640 EXPORT_SYMBOL(devfreq_remove_device);
 641
 642 static int devm_devfreq_dev_match(struct device *dev, void *res, void *data)
 643 {
 644         struct devfreq **r = res;
 645
 646         if (WARN_ON(!r || !*r))
 647                 return 0;
 648
 649         return *r == data;
 650 }
 651
 652 static void devm_devfreq_dev_release(struct device *dev, void *res)
 653 {
 654         devfreq_remove_device(*(struct devfreq **)res);
 655 }
 656
 657 /**
 658  * devm_devfreq_add_device() - Resource-managed devfreq_add_device()
 659  * @dev:        the device to add devfreq feature.
 660  * @profile:    device-specific profile to run devfreq.
 661  * @governor_name:      name of the policy to choose frequency.
 662  * @data:       private data for the governor. The devfreq framework does not
 663  *              touch this value.
 664  *
 665  * This function manages automatically the memory of devfreq device using device
 666  * resource management and simplify the free operation for memory of devfreq
 667  * device.
 668  */
 669 struct devfreq *devm_devfreq_add_device(struct device *dev,
 670                                         struct devfreq_dev_profile *profile,
 671                                         const char *governor_name,
 672                                         void *data)
 673 {
 674         struct devfreq **ptr, *devfreq;
 675
 676         ptr = devres_alloc(devm_devfreq_dev_release, sizeof(*ptr), GFP_KERNEL);
 677         if (!ptr)
 678                 return ERR_PTR(-ENOMEM);
 679
 680         devfreq = devfreq_add_device(dev, profile, governor_name, data);
 681         if (IS_ERR(devfreq)) {
 682                 devres_free(ptr);
 683                 return ERR_PTR(-ENOMEM);
 684         }
 685
 686         *ptr = devfreq;
 687         devres_add(dev, ptr);
 688
 689         return devfreq;
 690 }
 691 EXPORT_SYMBOL(devm_devfreq_add_device);
 692
 693 #ifdef CONFIG_OF
 694 /*
 695  * devfreq_get_devfreq_by_phandle - Get the devfreq device from devicetree
 696  * @dev - instance to the given device
 697  * @index - index into list of devfreq
 698  *
 699  * return the instance of devfreq device
 700  */
 701 struct devfreq *devfreq_get_devfreq_by_phandle(struct device *dev, int index)
 702 {
 703         struct device_node *node;
 704         struct devfreq *devfreq;
 705
 706         if (!dev)
 707                 return ERR_PTR(-EINVAL);
 708
 709         if (!dev->of_node)
 710                 return ERR_PTR(-EINVAL);
 711
 712         node = of_parse_phandle(dev->of_node, "devfreq", index);
 713         if (!node)
 714                 return ERR_PTR(-ENODEV);
 715
 716         mutex_lock(&devfreq_list_lock);
 717         list_for_each_entry(devfreq, &devfreq_list, node) {
 718                 if (devfreq->dev.parent
 719                         && devfreq->dev.parent->of_node == node) {
 720                         mutex_unlock(&devfreq_list_lock);
 721                         of_node_put(node);
 722                         return devfreq;
 723                 }
 724         }
 725         mutex_unlock(&devfreq_list_lock);
 726         of_node_put(node);
 727
 728         return ERR_PTR(-EPROBE_DEFER);
 729 }
 730 #else
 731 struct devfreq *devfreq_get_devfreq_by_phandle(struct device *dev, int index)
 732 {
 733         return ERR_PTR(-ENODEV);
 734 }
 735 #endif /* CONFIG_OF */
 736 EXPORT_SYMBOL_GPL(devfreq_get_devfreq_by_phandle);
 737
 738 /**
 739  * devm_devfreq_remove_device() - Resource-managed devfreq_remove_device()
 740  * @dev:        the device to add devfreq feature.
 741  * @devfreq:    the devfreq instance to be removed
 742  */
 743 void devm_devfreq_remove_device(struct device *dev, struct devfreq *devfreq)
 744 {
 745         WARN_ON(devres_release(dev, devm_devfreq_dev_release,
 746                                devm_devfreq_dev_match, devfreq));
 747 }
 748 EXPORT_SYMBOL(devm_devfreq_remove_device);
 749
 750 /**
 751  * devfreq_suspend_device() - Suspend devfreq of a device.
 752  * @devfreq: the devfreq instance to be suspended
 753  *
 754  * This function is intended to be called by the pm callbacks
 755  * (e.g., runtime_suspend, suspend) of the device driver that
 756  * holds the devfreq.
 757  */
 758 int devfreq_suspend_device(struct devfreq *devfreq)
 759 {
 760         if (!devfreq)
 761                 return -EINVAL;
 762
 763         if (!devfreq->governor)
 764                 return 0;
 765
 766         return devfreq->governor->event_handler(devfreq,
 767                                 DEVFREQ_GOV_SUSPEND, NULL);
 768 }
 769 EXPORT_SYMBOL(devfreq_suspend_device);
 770
 771 /**
 772  * devfreq_resume_device() - Resume devfreq of a device.
 773  * @devfreq: the devfreq instance to be resumed
 774  *
 775  * This function is intended to be called by the pm callbacks
 776  * (e.g., runtime_resume, resume) of the device driver that
 777  * holds the devfreq.
 778  */
 779 int devfreq_resume_device(struct devfreq *devfreq)
 780 {
 781         if (!devfreq)
 782                 return -EINVAL;
 783
 784         if (!devfreq->governor)
 785                 return 0;
 786
 787         return devfreq->governor->event_handler(devfreq,
 788                                 DEVFREQ_GOV_RESUME, NULL);
 789 }
 790 EXPORT_SYMBOL(devfreq_resume_device);
 791
 792 /**
 793  * devfreq_add_governor() - Add devfreq governor
 794  * @governor:   the devfreq governor to be added
 795  */
 796 int devfreq_add_governor(struct devfreq_governor *governor)
 797 {
 798         struct devfreq_governor *g;
 799         struct devfreq *devfreq;
 800         int err = 0;
 801
 802         if (!governor) {
 803                 pr_err("%s: Invalid parameters.\n", __func__);
 804                 return -EINVAL;
 805         }
 806
 807         mutex_lock(&devfreq_list_lock);
 808         g = find_devfreq_governor(governor->name);
 809         if (!IS_ERR(g)) {
 810                 pr_err("%s: governor %s already registered\n", __func__,
 811                        g->name);
 812                 err = -EINVAL;
 813                 goto err_out;
 814         }
 815
 816         list_add(&governor->node, &devfreq_governor_list);
 817
 818         list_for_each_entry(devfreq, &devfreq_list, node) {
 819                 int ret = 0;
 820                 struct device *dev = devfreq->dev.parent;
 821
 822                 if (!strncmp(devfreq->governor_name, governor->name,
 823                              DEVFREQ_NAME_LEN)) {
 824                         /* The following should never occur */
 825                         if (devfreq->governor) {
 826                                 dev_warn(dev,
 827                                          "%s: Governor %s already present\n",
 828                                          __func__, devfreq->governor->name);
 829                                 ret = devfreq->governor->event_handler(devfreq,
 830                                                         DEVFREQ_GOV_STOP, NULL);
 831                                 if (ret) {
 832                                         dev_warn(dev,
 833                                                  "%s: Governor %s stop = %d\n",
 834                                                  __func__,
 835                                                  devfreq->governor->name, ret);
 836                                 }
 837                                 /* Fall through */
 838                         }
 839                         devfreq->governor = governor;
 840                         ret = devfreq->governor->event_handler(devfreq,
 841                                                 DEVFREQ_GOV_START, NULL);
 842                         if (ret) {
 843                                 dev_warn(dev, "%s: Governor %s start=%d\n",
 844                                          __func__, devfreq->governor->name,
 845                                          ret);
 846                         }
 847                 }
 848         }
 849
 850 err_out:
 851         mutex_unlock(&devfreq_list_lock);
 852
 853         return err;
 854 }
 855 EXPORT_SYMBOL(devfreq_add_governor);
 856
 857 /**
 858  * devfreq_remove_governor() - Remove devfreq feature from a device.
 859  * @governor:   the devfreq governor to be removed
 860  */
 861 int devfreq_remove_governor(struct devfreq_governor *governor)
 862 {
 863         struct devfreq_governor *g;
 864         struct devfreq *devfreq;
 865         int err = 0;
 866
 867         if (!governor) {
 868                 pr_err("%s: Invalid parameters.\n", __func__);
 869                 return -EINVAL;
 870         }
 871
 872         mutex_lock(&devfreq_list_lock);
 873         g = find_devfreq_governor(governor->name);
 874         if (IS_ERR(g)) {
 875                 pr_err("%s: governor %s not registered\n", __func__,
 876                        governor->name);
 877                 err = PTR_ERR(g);
 878                 goto err_out;
 879         }
 880         list_for_each_entry(devfreq, &devfreq_list, node) {
 881                 int ret;
 882                 struct device *dev = devfreq->dev.parent;
 883
 884                 if (!strncmp(devfreq->governor_name, governor->name,
 885                              DEVFREQ_NAME_LEN)) {
 886                         /* we should have a devfreq governor! */
 887                         if (!devfreq->governor) {
 888                                 dev_warn(dev, "%s: Governor %s NOT present\n",
 889                                          __func__, governor->name);
 890                                 continue;
 891                                 /* Fall through */
 892                         }
 893                         ret = devfreq->governor->event_handler(devfreq,
 894                                                 DEVFREQ_GOV_STOP, NULL);
 895                         if (ret) {
 896                                 dev_warn(dev, "%s: Governor %s stop=%d\n",
 897                                          __func__, devfreq->governor->name,
 898                                          ret);
 899                         }
 900                         devfreq->governor = NULL;
 901                 }
 902         }
 903
 904         list_del(&governor->node);
 905 err_out:
 906         mutex_unlock(&devfreq_list_lock);
 907
 908         return err;
 909 }
 910 EXPORT_SYMBOL(devfreq_remove_governor);
 911
 912 static ssize_t governor_show(struct device *dev,
 913                              struct device_attribute *attr, char *buf)
 914 {
 915         if (!to_devfreq(dev)->governor)
 916                 return -EINVAL;
 917
 918         return sprintf(buf, "%s\n", to_devfreq(dev)->governor->name);
 919 }
 920
 921 static ssize_t governor_store(struct device *dev, struct device_attribute *attr,
 922                               const char *buf, size_t count)
 923 {
 924         struct devfreq *df = to_devfreq(dev);
 925         int ret;
 926         char str_governor[DEVFREQ_NAME_LEN + 1];
 927         struct devfreq_governor *governor;
 928
 929         ret = sscanf(buf, "%" __stringify(DEVFREQ_NAME_LEN) "s", str_governor);
 930         if (ret != 1)
 931                 return -EINVAL;
 932
 933         mutex_lock(&devfreq_list_lock);
 934         governor = find_devfreq_governor(str_governor);
 935         if (IS_ERR(governor)) {
 936                 ret = PTR_ERR(governor);
 937                 goto out;
 938         }
 939         if (df->governor == governor) {
 940                 ret = 0;
 941                 goto out;
 942         }
 943
 944         if (df->governor) {
 945                 ret = df->governor->event_handler(df, DEVFREQ_GOV_STOP, NULL);
 946                 if (ret) {
 947                         dev_warn(dev, "%s: Governor %s not stopped(%d)\n",
 948                                  __func__, df->governor->name, ret);
 949                         goto out;
 950                 }
 951         }
 952         df->governor = governor;
 953         strncpy(df->governor_name, governor->name, DEVFREQ_NAME_LEN);
 954         ret = df->governor->event_handler(df, DEVFREQ_GOV_START, NULL);
 955         if (ret)
 956                 dev_warn(dev, "%s: Governor %s not started(%d)\n",
 957                          __func__, df->governor->name, ret);
 958 out:
 959         mutex_unlock(&devfreq_list_lock);
 960
 961         if (!ret)
 962                 ret = count;
 963         return ret;
 964 }
 965 static DEVICE_ATTR_RW(governor);
 966
 967 static ssize_t available_governors_show(struct device *d,
 968                                         struct device_attribute *attr,
 969                                         char *buf)
 970 {
 971         struct devfreq_governor *tmp_governor;
 972         ssize_t count = 0;
 973
 974         mutex_lock(&devfreq_list_lock);
 975         list_for_each_entry(tmp_governor, &devfreq_governor_list, node)
 976                 count += scnprintf(&buf[count], (PAGE_SIZE - count - 2),
 977                                    "%s ", tmp_governor->name);
 978         mutex_unlock(&devfreq_list_lock);
 979
 980         /* Truncate the trailing space */
 981         if (count)
 982                 count--;
 983
 984         count += sprintf(&buf[count], "\n");
 985
 986         return count;
 987 }
 988 static DEVICE_ATTR_RO(available_governors);
 989
 990 static ssize_t cur_freq_show(struct device *dev, struct device_attribute *attr,
 991                              char *buf)
 992 {
 993         unsigned long freq;
 994         struct devfreq *devfreq = to_devfreq(dev);
 995
 996         if (devfreq->profile->get_cur_freq &&
 997                 !devfreq->profile->get_cur_freq(devfreq->dev.parent, &freq))
 998                         return sprintf(buf, "%lu\n", freq);
 999
1000         return sprintf(buf, "%lu\n", devfreq->previous_freq);
1001 }
1002 static DEVICE_ATTR_RO(cur_freq);
1003
1004 static ssize_t target_freq_show(struct device *dev,
1005                                 struct device_attribute *attr, char *buf)
1006 {
1007         return sprintf(buf, "%lu\n", to_devfreq(dev)->previous_freq);
1008 }
1009 static DEVICE_ATTR_RO(target_freq);
1010
1011 static ssize_t polling_interval_show(struct device *dev,
1012                                      struct device_attribute *attr, char *buf)
1013 {
1014         return sprintf(buf, "%d\n", to_devfreq(dev)->profile->polling_ms);
1015 }
1016
1017 static ssize_t polling_interval_store(struct device *dev,
1018                                       struct device_attribute *attr,
1019                                       const char *buf, size_t count)
1020 {
1021         struct devfreq *df = to_devfreq(dev);
1022         unsigned int value;
1023         int ret;
1024
1025         if (!df->governor)
1026                 return -EINVAL;
1027
1028         ret = sscanf(buf, "%u", &value);
1029         if (ret != 1)
1030                 return -EINVAL;
1031
1032         df->governor->event_handler(df, DEVFREQ_GOV_INTERVAL, &value);
1033         ret = count;
1034
1035         return ret;
1036 }
1037 static DEVICE_ATTR_RW(polling_interval);
1038
1039 static ssize_t min_freq_store(struct device *dev, struct device_attribute *attr,
1040                               const char *buf, size_t count)
1041 {
1042         struct devfreq *df = to_devfreq(dev);
1043         unsigned long value;
1044         int ret;
1045         unsigned long max;
1046
1047         ret = sscanf(buf, "%lu", &value);
1048         if (ret != 1)
1049                 return -EINVAL;
1050
1051         mutex_lock(&df->lock);
1052         max = df->max_freq;
1053         if (value && max && value > max) {
1054                 ret = -EINVAL;
1055                 goto unlock;
1056         }
1057
1058         df->min_freq = value;
1059         update_devfreq(df);
1060         ret = count;
1061 unlock:
1062         mutex_unlock(&df->lock);
1063         return ret;
1064 }
1065
1066 static ssize_t max_freq_store(struct device *dev, struct device_attribute *attr,
1067                               const char *buf, size_t count)
1068 {
1069         struct devfreq *df = to_devfreq(dev);
1070         unsigned long value;
1071         int ret;
1072         unsigned long min;
1073
1074         ret = sscanf(buf, "%lu", &value);
1075         if (ret != 1)
1076                 return -EINVAL;
1077
1078         mutex_lock(&df->lock);
1079         min = df->min_freq;
1080         if (value && min && value < min) {
1081                 ret = -EINVAL;
1082                 goto unlock;
1083         }
1084
1085         df->max_freq = value;
1086         update_devfreq(df);
1087         ret = count;
1088 unlock:
1089         mutex_unlock(&df->lock);
1090         return ret;
1091 }
1092
1093 #define show_one(name)                                          \
1094 static ssize_t name##_show                                      \
1095 (struct device *dev, struct device_attribute *attr, char *buf)  \
1096 {                                                               \
1097         return sprintf(buf, "%lu\n", to_devfreq(dev)->name);    \
1098 }
1099 show_one(min_freq);
1100 show_one(max_freq);
1101
1102 static DEVICE_ATTR_RW(min_freq);
1103 static DEVICE_ATTR_RW(max_freq);
1104
1105 static ssize_t available_frequencies_show(struct device *d,
1106                                           struct device_attribute *attr,
1107                                           char *buf)
1108 {
1109         struct devfreq *df = to_devfreq(d);
1110         struct device *dev = df->dev.parent;
1111         struct dev_pm_opp *opp;
1112         ssize_t count = 0;
1113         unsigned long freq = 0;
1114
1115         rcu_read_lock();
1116         do {
1117                 opp = dev_pm_opp_find_freq_ceil(dev, &freq);
1118                 if (IS_ERR(opp))
1119                         break;
1120
1121                 count += scnprintf(&buf[count], (PAGE_SIZE - count - 2),
1122                                    "%lu ", freq);
1123                 freq++;
1124         } while (1);
1125         rcu_read_unlock();
1126
1127         /* Truncate the trailing space */
1128         if (count)
1129                 count--;
1130
1131         count += sprintf(&buf[count], "\n");
1132
1133         return count;
1134 }
1135 static DEVICE_ATTR_RO(available_frequencies);
1136
1137 static ssize_t trans_stat_show(struct device *dev,
1138                                struct device_attribute *attr, char *buf)
1139 {
1140         struct devfreq *devfreq = to_devfreq(dev);
1141         ssize_t len;
1142         int i, j;
1143         unsigned int max_state = devfreq->profile->max_state;
1144
1145         if (!devfreq->stop_polling &&
1146                         devfreq_update_status(devfreq, devfreq->previous_freq))
1147                 return 0;
1148         if (max_state == 0)
1149                 return sprintf(buf, "Not Supported.\n");
1150
1151         len = sprintf(buf, "     From  :   To\n");
1152         len += sprintf(buf + len, "           :");
1153         for (i = 0; i < max_state; i++)
1154                 len += sprintf(buf + len, "%10lu",
1155                                 devfreq->profile->freq_table[i]);
1156
1157         len += sprintf(buf + len, "   time(ms)\n");
1158
1159         for (i = 0; i < max_state; i++) {
1160                 if (devfreq->profile->freq_table[i]
1161                                         == devfreq->previous_freq) {
1162                         len += sprintf(buf + len, "*");
1163                 } else {
1164                         len += sprintf(buf + len, " ");
1165                 }
1166                 len += sprintf(buf + len, "%10lu:",
1167                                 devfreq->profile->freq_table[i]);
1168                 for (j = 0; j < max_state; j++)
1169                         len += sprintf(buf + len, "%10u",
1170                                 devfreq->trans_table[(i * max_state) + j]);
1171                 len += sprintf(buf + len, "%10u\n",
1172                         jiffies_to_msecs(devfreq->time_in_state[i]));
1173         }
1174
1175         len += sprintf(buf + len, "Total transition : %u\n",
1176                                         devfreq->total_trans);
1177         return len;
1178 }
1179 static DEVICE_ATTR_RO(trans_stat);
1180
1181 static struct attribute *devfreq_attrs[] = {
1182         &dev_attr_governor.attr,
1183         &dev_attr_available_governors.attr,
1184         &dev_attr_cur_freq.attr,
1185         &dev_attr_available_frequencies.attr,
1186         &dev_attr_target_freq.attr,
1187         &dev_attr_polling_interval.attr,
1188         &dev_attr_min_freq.attr,
1189         &dev_attr_max_freq.attr,
1190         &dev_attr_trans_stat.attr,
1191         NULL,
1192 };
1193 ATTRIBUTE_GROUPS(devfreq);
1194
1195 static int __init devfreq_init(void)
1196 {
1197         devfreq_class = class_create(THIS_MODULE, "devfreq");
1198         if (IS_ERR(devfreq_class)) {
1199                 pr_err("%s: couldn't create class\n", __FILE__);
1200                 return PTR_ERR(devfreq_class);
1201         }
1202
1203         devfreq_wq = create_freezable_workqueue("devfreq_wq");
1204         if (!devfreq_wq) {
1205                 class_destroy(devfreq_class);
1206                 pr_err("%s: couldn't create workqueue\n", __FILE__);
1207                 return -ENOMEM;
1208         }
1209         devfreq_class->dev_groups = devfreq_groups;
1210
1211         return 0;
1212 }
1213 subsys_initcall(devfreq_init);
1214
1215 /*
1216  * The followings are helper functions for devfreq user device drivers with
1217  * OPP framework.
1218  */
1219
1220 /**
1221  * devfreq_recommended_opp() - Helper function to get proper OPP for the
1222  *                           freq value given to target callback.
1223  * @dev:        The devfreq user device. (parent of devfreq)
1224  * @freq:       The frequency given to target function
1225  * @flags:      Flags handed from devfreq framework.
1226  *
1227  * Locking: This function must be called under rcu_read_lock(). opp is a rcu
1228  * protected pointer. The reason for the same is that the opp pointer which is
1229  * returned will remain valid for use with opp_get_{voltage, freq} only while
1230  * under the locked area. The pointer returned must be used prior to unlocking
1231  * with rcu_read_unlock() to maintain the integrity of the pointer.
1232  */
1233 struct dev_pm_opp *devfreq_recommended_opp(struct device *dev,
1234                                            unsigned long *freq,
1235                                            u32 flags)
1236 {
1237         struct dev_pm_opp *opp;
1238
1239         if (flags & DEVFREQ_FLAG_LEAST_UPPER_BOUND) {
1240                 /* The freq is an upper bound. opp should be lower */
1241                 opp = dev_pm_opp_find_freq_floor(dev, freq);
1242
1243                 /* If not available, use the closest opp */
1244                 if (opp == ERR_PTR(-ERANGE))
1245                         opp = dev_pm_opp_find_freq_ceil(dev, freq);
1246         } else {
1247                 /* The freq is an lower bound. opp should be higher */
1248                 opp = dev_pm_opp_find_freq_ceil(dev, freq);
1249
1250                 /* If not available, use the closest opp */
1251                 if (opp == ERR_PTR(-ERANGE))
1252                         opp = dev_pm_opp_find_freq_floor(dev, freq);
1253         }
1254
1255         return opp;
1256 }
1257 EXPORT_SYMBOL(devfreq_recommended_opp);
1258
1259 /**
1260  * devfreq_register_opp_notifier() - Helper function to get devfreq notified
1261  *                                 for any changes in the OPP availability
1262  *                                 changes
1263  * @dev:        The devfreq user device. (parent of devfreq)
1264  * @devfreq:    The devfreq object.
1265  */
1266 int devfreq_register_opp_notifier(struct device *dev, struct devfreq *devfreq)
1267 {
1268         return dev_pm_opp_register_notifier(dev, &devfreq->nb);
1269 }
1270 EXPORT_SYMBOL(devfreq_register_opp_notifier);
1271
1272 /**
1273  * devfreq_unregister_opp_notifier() - Helper function to stop getting devfreq
1274  *                                   notified for any changes in the OPP
1275  *                                   availability changes anymore.
1276  * @dev:        The devfreq user device. (parent of devfreq)
1277  * @devfreq:    The devfreq object.
1278  *
1279  * At exit() callback of devfreq_dev_profile, this must be included if
1280  * devfreq_recommended_opp is used.
1281  */
1282 int devfreq_unregister_opp_notifier(struct device *dev, struct devfreq *devfreq)
1283 {
1284         return dev_pm_opp_unregister_notifier(dev, &devfreq->nb);
1285 }
1286 EXPORT_SYMBOL(devfreq_unregister_opp_notifier);
1287
1288 static void devm_devfreq_opp_release(struct device *dev, void *res)
1289 {
1290         devfreq_unregister_opp_notifier(dev, *(struct devfreq **)res);
1291 }
1292
1293 /**
1294  * devm_ devfreq_register_opp_notifier()
1295  *              - Resource-managed devfreq_register_opp_notifier()
1296  * @dev:        The devfreq user device. (parent of devfreq)
1297  * @devfreq:    The devfreq object.
1298  */
1299 int devm_devfreq_register_opp_notifier(struct device *dev,
1300                                        struct devfreq *devfreq)
1301 {
1302         struct devfreq **ptr;
1303         int ret;
1304
1305         ptr = devres_alloc(devm_devfreq_opp_release, sizeof(*ptr), GFP_KERNEL);
1306         if (!ptr)
1307                 return -ENOMEM;
1308
1309         ret = devfreq_register_opp_notifier(dev, devfreq);
1310         if (ret) {
1311                 devres_free(ptr);
1312                 return ret;
1313         }
1314
1315         *ptr = devfreq;
1316         devres_add(dev, ptr);
1317
1318         return 0;
1319 }
1320 EXPORT_SYMBOL(devm_devfreq_register_opp_notifier);
1321
1322 /**
1323  * devm_devfreq_unregister_opp_notifier()
1324  *              - Resource-managed devfreq_unregister_opp_notifier()
1325  * @dev:        The devfreq user device. (parent of devfreq)
1326  * @devfreq:    The devfreq object.
1327  */
1328 void devm_devfreq_unregister_opp_notifier(struct device *dev,
1329                                          struct devfreq *devfreq)
1330 {
1331         WARN_ON(devres_release(dev, devm_devfreq_opp_release,
1332                                devm_devfreq_dev_match, devfreq));
1333 }
1334 EXPORT_SYMBOL(devm_devfreq_unregister_opp_notifier);
1335
1336 /**
1337  * devfreq_register_notifier() - Register a driver with devfreq
1338  * @devfreq:    The devfreq object.
1339  * @nb:         The notifier block to register.
1340  * @list:       DEVFREQ_TRANSITION_NOTIFIER.
1341  */
1342 int devfreq_register_notifier(struct devfreq *devfreq,
1343                                 struct notifier_block *nb,
1344                                 unsigned int list)
1345 {
1346         int ret = 0;
1347
1348         if (!devfreq)
1349                 return -EINVAL;
1350
1351         switch (list) {
1352         case DEVFREQ_TRANSITION_NOTIFIER:
1353                 ret = srcu_notifier_chain_register(
1354                                 &devfreq->transition_notifier_list, nb);
1355                 break;
1356         default:
1357                 ret = -EINVAL;
1358         }
1359
1360         return ret;
1361 }
1362 EXPORT_SYMBOL(devfreq_register_notifier);
1363
1364 /*
1365  * devfreq_unregister_notifier() - Unregister a driver with devfreq
1366  * @devfreq:    The devfreq object.
1367  * @nb:         The notifier block to be unregistered.
1368  * @list:       DEVFREQ_TRANSITION_NOTIFIER.
1369  */
1370 int devfreq_unregister_notifier(struct devfreq *devfreq,
1371                                 struct notifier_block *nb,
1372                                 unsigned int list)
1373 {
1374         int ret = 0;
1375
1376         if (!devfreq)
1377                 return -EINVAL;
1378
1379         switch (list) {
1380         case DEVFREQ_TRANSITION_NOTIFIER:
1381                 ret = srcu_notifier_chain_unregister(
1382                                 &devfreq->transition_notifier_list, nb);
1383                 break;
1384         default:
1385                 ret = -EINVAL;
1386         }
1387
1388         return ret;
1389 }
1390 EXPORT_SYMBOL(devfreq_unregister_notifier);
1391
1392 struct devfreq_notifier_devres {
1393         struct devfreq *devfreq;
1394         struct notifier_block *nb;
1395         unsigned int list;
1396 };
1397
1398 static void devm_devfreq_notifier_release(struct device *dev, void *res)
1399 {
1400         struct devfreq_notifier_devres *this = res;
1401
1402         devfreq_unregister_notifier(this->devfreq, this->nb, this->list);
1403 }
1404
1405 /**
1406  * devm_devfreq_register_notifier()
1407         - Resource-managed devfreq_register_notifier()
1408  * @dev:        The devfreq user device. (parent of devfreq)
1409  * @devfreq:    The devfreq object.
1410  * @nb:         The notifier block to be unregistered.
1411  * @list:       DEVFREQ_TRANSITION_NOTIFIER.
1412  */
1413 int devm_devfreq_register_notifier(struct device *dev,
1414                                 struct devfreq *devfreq,
1415                                 struct notifier_block *nb,
1416                                 unsigned int list)
1417 {
1418         struct devfreq_notifier_devres *ptr;
1419         int ret;
1420
1421         ptr = devres_alloc(devm_devfreq_notifier_release, sizeof(*ptr),
1422                                 GFP_KERNEL);
1423         if (!ptr)
1424                 return -ENOMEM;
1425
1426         ret = devfreq_register_notifier(devfreq, nb, list);
1427         if (ret) {
1428                 devres_free(ptr);
1429                 return ret;
1430         }
1431
1432         ptr->devfreq = devfreq;
1433         ptr->nb = nb;
1434         ptr->list = list;
1435         devres_add(dev, ptr);
1436
1437         return 0;
1438 }
1439 EXPORT_SYMBOL(devm_devfreq_register_notifier);
1440
1441 /**
1442  * devm_devfreq_unregister_notifier()
1443         - Resource-managed devfreq_unregister_notifier()
1444  * @dev:        The devfreq user device. (parent of devfreq)
1445  * @devfreq:    The devfreq object.
1446  * @nb:         The notifier block to be unregistered.
1447  * @list:       DEVFREQ_TRANSITION_NOTIFIER.
1448  */
1449 void devm_devfreq_unregister_notifier(struct device *dev,
1450                                 struct devfreq *devfreq,
1451                                 struct notifier_block *nb,
1452                                 unsigned int list)
1453 {
1454         WARN_ON(devres_release(dev, devm_devfreq_notifier_release,
1455                                devm_devfreq_dev_match, devfreq));
1456 }
1457 EXPORT_SYMBOL(devm_devfreq_unregister_notifier);