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/module.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         prev_lev = devfreq_get_freq_level(devfreq, devfreq->previous_freq);
 141         if (prev_lev < 0) {
 142                 ret = prev_lev;
 143                 goto out;
 144         }
 145
 146         devfreq->time_in_state[prev_lev] +=
 147                          cur_time - devfreq->last_stat_updated;
 148
 149         lev = devfreq_get_freq_level(devfreq, freq);
 150         if (lev < 0) {
 151                 ret = lev;
 152                 goto out;
 153         }
 154
 155         if (lev != prev_lev) {
 156                 devfreq->trans_table[(prev_lev *
 157                                 devfreq->profile->max_state) + lev]++;
 158                 devfreq->total_trans++;
 159         }
 160
 161 out:
 162         devfreq->last_stat_updated = cur_time;
 163         return ret;
 164 }
 165
 166 /**
 167  * find_devfreq_governor() - find devfreq governor from name
 168  * @name:       name of the governor
 169  *
 170  * Search the list of devfreq governors and return the matched
 171  * governor's pointer. devfreq_list_lock should be held by the caller.
 172  */
 173 static struct devfreq_governor *find_devfreq_governor(const char *name)
 174 {
 175         struct devfreq_governor *tmp_governor;
 176
 177         if (IS_ERR_OR_NULL(name)) {
 178                 pr_err("DEVFREQ: %s: Invalid parameters\n", __func__);
 179                 return ERR_PTR(-EINVAL);
 180         }
 181         WARN(!mutex_is_locked(&devfreq_list_lock),
 182              "devfreq_list_lock must be locked.");
 183
 184         list_for_each_entry(tmp_governor, &devfreq_governor_list, node) {
 185                 if (!strncmp(tmp_governor->name, name, DEVFREQ_NAME_LEN))
 186                         return tmp_governor;
 187         }
 188
 189         return ERR_PTR(-ENODEV);
 190 }
 191
 192 static int devfreq_notify_transition(struct devfreq *devfreq,
 193                 struct devfreq_freqs *freqs, unsigned int state)
 194 {
 195         if (!devfreq)
 196                 return -EINVAL;
 197
 198         switch (state) {
 199         case DEVFREQ_PRECHANGE:
 200                 srcu_notifier_call_chain(&devfreq->transition_notifier_list,
 201                                 DEVFREQ_PRECHANGE, freqs);
 202                 break;
 203
 204         case DEVFREQ_POSTCHANGE:
 205                 srcu_notifier_call_chain(&devfreq->transition_notifier_list,
 206                                 DEVFREQ_POSTCHANGE, freqs);
 207                 break;
 208         default:
 209                 return -EINVAL;
 210         }
 211
 212         return 0;
 213 }
 214
 215 /* Load monitoring helper functions for governors use */
 216
 217 /**
 218  * update_devfreq() - Reevaluate the device and configure frequency.
 219  * @devfreq:    the devfreq instance.
 220  *
 221  * Note: Lock devfreq->lock before calling update_devfreq
 222  *       This function is exported for governors.
 223  */
 224 int update_devfreq(struct devfreq *devfreq)
 225 {
 226         struct devfreq_freqs freqs;
 227         unsigned long freq, cur_freq;
 228         int err = 0;
 229         u32 flags = 0;
 230
 231         if (!mutex_is_locked(&devfreq->lock)) {
 232                 WARN(true, "devfreq->lock must be locked by the caller.\n");
 233                 return -EINVAL;
 234         }
 235
 236         if (!devfreq->governor)
 237                 return -EINVAL;
 238
 239         /* Reevaluate the proper frequency */
 240         err = devfreq->governor->get_target_freq(devfreq, &freq);
 241         if (err)
 242                 return err;
 243
 244         /*
 245          * Adjust the frequency with user freq and QoS.
 246          *
 247          * List from the highest priority
 248          * max_freq
 249          * min_freq
 250          */
 251
 252         if (devfreq->min_freq && freq < devfreq->min_freq) {
 253                 freq = devfreq->min_freq;
 254                 flags &= ~DEVFREQ_FLAG_LEAST_UPPER_BOUND; /* Use GLB */
 255         }
 256         if (devfreq->max_freq && freq > devfreq->max_freq) {
 257                 freq = devfreq->max_freq;
 258                 flags |= DEVFREQ_FLAG_LEAST_UPPER_BOUND; /* Use LUB */
 259         }
 260
 261         if (devfreq->profile->get_cur_freq)
 262                 devfreq->profile->get_cur_freq(devfreq->dev.parent, &cur_freq);
 263         else
 264                 cur_freq = devfreq->previous_freq;
 265
 266         freqs.old = cur_freq;
 267         freqs.new = freq;
 268         devfreq_notify_transition(devfreq, &freqs, DEVFREQ_PRECHANGE);
 269
 270         err = devfreq->profile->target(devfreq->dev.parent, &freq, flags);
 271         if (err)
 272                 return err;
 273
 274         freqs.new = freq;
 275         devfreq_notify_transition(devfreq, &freqs, DEVFREQ_POSTCHANGE);
 276
 277         if (devfreq->profile->freq_table)
 278                 if (devfreq_update_status(devfreq, freq))
 279                         dev_err(&devfreq->dev,
 280                                 "Couldn't update frequency transition information.\n");
 281
 282         devfreq->previous_freq = freq;
 283         return err;
 284 }
 285 EXPORT_SYMBOL(update_devfreq);
 286
 287 /**
 288  * devfreq_monitor() - Periodically poll devfreq objects.
 289  * @work:       the work struct used to run devfreq_monitor periodically.
 290  *
 291  */
 292 static void devfreq_monitor(struct work_struct *work)
 293 {
 294         int err;
 295         struct devfreq *devfreq = container_of(work,
 296                                         struct devfreq, work.work);
 297
 298         mutex_lock(&devfreq->lock);
 299         err = update_devfreq(devfreq);
 300         if (err)
 301                 dev_err(&devfreq->dev, "dvfs failed with (%d) error\n", err);
 302
 303         queue_delayed_work(devfreq_wq, &devfreq->work,
 304                                 msecs_to_jiffies(devfreq->profile->polling_ms));
 305         mutex_unlock(&devfreq->lock);
 306 }
 307
 308 /**
 309  * devfreq_monitor_start() - Start load monitoring of devfreq instance
 310  * @devfreq:    the devfreq instance.
 311  *
 312  * Helper function for starting devfreq device load monitoing. By
 313  * default delayed work based monitoring is supported. Function
 314  * to be called from governor in response to DEVFREQ_GOV_START
 315  * event when device is added to devfreq framework.
 316  */
 317 void devfreq_monitor_start(struct devfreq *devfreq)
 318 {
 319         INIT_DEFERRABLE_WORK(&devfreq->work, devfreq_monitor);
 320         if (devfreq->profile->polling_ms)
 321                 queue_delayed_work(devfreq_wq, &devfreq->work,
 322                         msecs_to_jiffies(devfreq->profile->polling_ms));
 323 }
 324 EXPORT_SYMBOL(devfreq_monitor_start);
 325
 326 /**
 327  * devfreq_monitor_stop() - Stop load monitoring of a devfreq instance
 328  * @devfreq:    the devfreq instance.
 329  *
 330  * Helper function to stop devfreq device load monitoing. Function
 331  * to be called from governor in response to DEVFREQ_GOV_STOP
 332  * event when device is removed from devfreq framework.
 333  */
 334 void devfreq_monitor_stop(struct devfreq *devfreq)
 335 {
 336         cancel_delayed_work_sync(&devfreq->work);
 337 }
 338 EXPORT_SYMBOL(devfreq_monitor_stop);
 339
 340 /**
 341  * devfreq_monitor_suspend() - Suspend load monitoring of a devfreq instance
 342  * @devfreq:    the devfreq instance.
 343  *
 344  * Helper function to suspend devfreq device load monitoing. Function
 345  * to be called from governor in response to DEVFREQ_GOV_SUSPEND
 346  * event or when polling interval is set to zero.
 347  *
 348  * Note: Though this function is same as devfreq_monitor_stop(),
 349  * intentionally kept separate to provide hooks for collecting
 350  * transition statistics.
 351  */
 352 void devfreq_monitor_suspend(struct devfreq *devfreq)
 353 {
 354         mutex_lock(&devfreq->lock);
 355         if (devfreq->stop_polling) {
 356                 mutex_unlock(&devfreq->lock);
 357                 return;
 358         }
 359
 360         devfreq_update_status(devfreq, devfreq->previous_freq);
 361         devfreq->stop_polling = true;
 362         mutex_unlock(&devfreq->lock);
 363         cancel_delayed_work_sync(&devfreq->work);
 364 }
 365 EXPORT_SYMBOL(devfreq_monitor_suspend);
 366
 367 /**
 368  * devfreq_monitor_resume() - Resume load monitoring of a devfreq instance
 369  * @devfreq:    the devfreq instance.
 370  *
 371  * Helper function to resume devfreq device load monitoing. Function
 372  * to be called from governor in response to DEVFREQ_GOV_RESUME
 373  * event or when polling interval is set to non-zero.
 374  */
 375 void devfreq_monitor_resume(struct devfreq *devfreq)
 376 {
 377         unsigned long freq;
 378
 379         mutex_lock(&devfreq->lock);
 380         if (!devfreq->stop_polling)
 381                 goto out;
 382
 383         if (!delayed_work_pending(&devfreq->work) &&
 384                         devfreq->profile->polling_ms)
 385                 queue_delayed_work(devfreq_wq, &devfreq->work,
 386                         msecs_to_jiffies(devfreq->profile->polling_ms));
 387
 388         devfreq->last_stat_updated = jiffies;
 389         devfreq->stop_polling = false;
 390
 391         if (devfreq->profile->get_cur_freq &&
 392                 !devfreq->profile->get_cur_freq(devfreq->dev.parent, &freq))
 393                 devfreq->previous_freq = freq;
 394
 395 out:
 396         mutex_unlock(&devfreq->lock);
 397 }
 398 EXPORT_SYMBOL(devfreq_monitor_resume);
 399
 400 /**
 401  * devfreq_interval_update() - Update device devfreq monitoring interval
 402  * @devfreq:    the devfreq instance.
 403  * @delay:      new polling interval to be set.
 404  *
 405  * Helper function to set new load monitoring polling interval. Function
 406  * to be called from governor in response to DEVFREQ_GOV_INTERVAL event.
 407  */
 408 void devfreq_interval_update(struct devfreq *devfreq, unsigned int *delay)
 409 {
 410         unsigned int cur_delay = devfreq->profile->polling_ms;
 411         unsigned int new_delay = *delay;
 412
 413         mutex_lock(&devfreq->lock);
 414         devfreq->profile->polling_ms = new_delay;
 415
 416         if (devfreq->stop_polling)
 417                 goto out;
 418
 419         /* if new delay is zero, stop polling */
 420         if (!new_delay) {
 421                 mutex_unlock(&devfreq->lock);
 422                 cancel_delayed_work_sync(&devfreq->work);
 423                 return;
 424         }
 425
 426         /* if current delay is zero, start polling with new delay */
 427         if (!cur_delay) {
 428                 queue_delayed_work(devfreq_wq, &devfreq->work,
 429                         msecs_to_jiffies(devfreq->profile->polling_ms));
 430                 goto out;
 431         }
 432
 433         /* if current delay is greater than new delay, restart polling */
 434         if (cur_delay > new_delay) {
 435                 mutex_unlock(&devfreq->lock);
 436                 cancel_delayed_work_sync(&devfreq->work);
 437                 mutex_lock(&devfreq->lock);
 438                 if (!devfreq->stop_polling)
 439                         queue_delayed_work(devfreq_wq, &devfreq->work,
 440                               msecs_to_jiffies(devfreq->profile->polling_ms));
 441         }
 442 out:
 443         mutex_unlock(&devfreq->lock);
 444 }
 445 EXPORT_SYMBOL(devfreq_interval_update);
 446
 447 /**
 448  * devfreq_notifier_call() - Notify that the device frequency requirements
 449  *                         has been changed out of devfreq framework.
 450  * @nb:         the notifier_block (supposed to be devfreq->nb)
 451  * @type:       not used
 452  * @devp:       not used
 453  *
 454  * Called by a notifier that uses devfreq->nb.
 455  */
 456 static int devfreq_notifier_call(struct notifier_block *nb, unsigned long type,
 457                                  void *devp)
 458 {
 459         struct devfreq *devfreq = container_of(nb, struct devfreq, nb);
 460         int ret;
 461
 462         mutex_lock(&devfreq->lock);
 463         ret = update_devfreq(devfreq);
 464         mutex_unlock(&devfreq->lock);
 465
 466         return ret;
 467 }
 468
 469 /**
 470  * _remove_devfreq() - Remove devfreq from the list and release its resources.
 471  * @devfreq:    the devfreq struct
 472  */
 473 static void _remove_devfreq(struct devfreq *devfreq)
 474 {
 475         mutex_lock(&devfreq_list_lock);
 476         if (IS_ERR(find_device_devfreq(devfreq->dev.parent))) {
 477                 mutex_unlock(&devfreq_list_lock);
 478                 dev_warn(&devfreq->dev, "releasing devfreq which doesn't exist\n");
 479                 return;
 480         }
 481         list_del(&devfreq->node);
 482         mutex_unlock(&devfreq_list_lock);
 483
 484         if (devfreq->governor)
 485                 devfreq->governor->event_handler(devfreq,
 486                                                  DEVFREQ_GOV_STOP, NULL);
 487
 488         if (devfreq->profile->exit)
 489                 devfreq->profile->exit(devfreq->dev.parent);
 490
 491         mutex_destroy(&devfreq->lock);
 492         kfree(devfreq);
 493 }
 494
 495 /**
 496  * devfreq_dev_release() - Callback for struct device to release the device.
 497  * @dev:        the devfreq device
 498  *
 499  * This calls _remove_devfreq() if _remove_devfreq() is not called.
 500  */
 501 static void devfreq_dev_release(struct device *dev)
 502 {
 503         struct devfreq *devfreq = to_devfreq(dev);
 504
 505         _remove_devfreq(devfreq);
 506 }
 507
 508 /**
 509  * devfreq_add_device() - Add devfreq feature to the device
 510  * @dev:        the device to add devfreq feature.
 511  * @profile:    device-specific profile to run devfreq.
 512  * @governor_name:      name of the policy to choose frequency.
 513  * @data:       private data for the governor. The devfreq framework does not
 514  *              touch this value.
 515  */
 516 struct devfreq *devfreq_add_device(struct device *dev,
 517                                    struct devfreq_dev_profile *profile,
 518                                    const char *governor_name,
 519                                    void *data)
 520 {
 521         struct devfreq *devfreq;
 522         struct devfreq_governor *governor;
 523         int err = 0;
 524
 525         if (!dev || !profile || !governor_name) {
 526                 dev_err(dev, "%s: Invalid parameters.\n", __func__);
 527                 return ERR_PTR(-EINVAL);
 528         }
 529
 530         mutex_lock(&devfreq_list_lock);
 531         devfreq = find_device_devfreq(dev);
 532         mutex_unlock(&devfreq_list_lock);
 533         if (!IS_ERR(devfreq)) {
 534                 dev_err(dev, "%s: Unable to create devfreq for the device. It already has one.\n", __func__);
 535                 err = -EINVAL;
 536                 goto err_out;
 537         }
 538
 539         devfreq = kzalloc(sizeof(struct devfreq), GFP_KERNEL);
 540         if (!devfreq) {
 541                 dev_err(dev, "%s: Unable to create devfreq for the device\n",
 542                         __func__);
 543                 err = -ENOMEM;
 544                 goto err_out;
 545         }
 546
 547         mutex_init(&devfreq->lock);
 548         mutex_lock(&devfreq->lock);
 549         devfreq->dev.parent = dev;
 550         devfreq->dev.class = devfreq_class;
 551         devfreq->dev.release = devfreq_dev_release;
 552         devfreq->profile = profile;
 553         strncpy(devfreq->governor_name, governor_name, DEVFREQ_NAME_LEN);
 554         devfreq->previous_freq = profile->initial_freq;
 555         devfreq->data = data;
 556         devfreq->nb.notifier_call = devfreq_notifier_call;
 557
 558         if (!devfreq->profile->max_state && !devfreq->profile->freq_table) {
 559                 mutex_unlock(&devfreq->lock);
 560                 devfreq_set_freq_table(devfreq);
 561                 mutex_lock(&devfreq->lock);
 562         }
 563
 564         dev_set_name(&devfreq->dev, "%s", dev_name(dev));
 565         err = device_register(&devfreq->dev);
 566         if (err) {
 567                 mutex_unlock(&devfreq->lock);
 568                 goto err_out;
 569         }
 570
 571         devfreq->trans_table =  devm_kzalloc(&devfreq->dev, sizeof(unsigned int) *
 572                                                 devfreq->profile->max_state *
 573                                                 devfreq->profile->max_state,
 574                                                 GFP_KERNEL);
 575         devfreq->time_in_state = devm_kzalloc(&devfreq->dev, sizeof(unsigned long) *
 576                                                 devfreq->profile->max_state,
 577                                                 GFP_KERNEL);
 578         devfreq->last_stat_updated = jiffies;
 579
 580         srcu_init_notifier_head(&devfreq->transition_notifier_list);
 581
 582         mutex_unlock(&devfreq->lock);
 583
 584         mutex_lock(&devfreq_list_lock);
 585         list_add(&devfreq->node, &devfreq_list);
 586
 587         governor = find_devfreq_governor(devfreq->governor_name);
 588         if (!IS_ERR(governor))
 589                 devfreq->governor = governor;
 590         if (devfreq->governor)
 591                 err = devfreq->governor->event_handler(devfreq,
 592                                         DEVFREQ_GOV_START, NULL);
 593         mutex_unlock(&devfreq_list_lock);
 594         if (err) {
 595                 dev_err(dev, "%s: Unable to start governor for the device\n",
 596                         __func__);
 597                 goto err_init;
 598         }
 599
 600         return devfreq;
 601
 602 err_init:
 603         list_del(&devfreq->node);
 604         device_unregister(&devfreq->dev);
 605 err_out:
 606         return ERR_PTR(err);
 607 }
 608 EXPORT_SYMBOL(devfreq_add_device);
 609
 610 /**
 611  * devfreq_remove_device() - Remove devfreq feature from a device.
 612  * @devfreq:    the devfreq instance to be removed
 613  *
 614  * The opposite of devfreq_add_device().
 615  */
 616 int devfreq_remove_device(struct devfreq *devfreq)
 617 {
 618         if (!devfreq)
 619                 return -EINVAL;
 620
 621         device_unregister(&devfreq->dev);
 622
 623         return 0;
 624 }
 625 EXPORT_SYMBOL(devfreq_remove_device);
 626
 627 static int devm_devfreq_dev_match(struct device *dev, void *res, void *data)
 628 {
 629         struct devfreq **r = res;
 630
 631         if (WARN_ON(!r || !*r))
 632                 return 0;
 633
 634         return *r == data;
 635 }
 636
 637 static void devm_devfreq_dev_release(struct device *dev, void *res)
 638 {
 639         devfreq_remove_device(*(struct devfreq **)res);
 640 }
 641
 642 /**
 643  * devm_devfreq_add_device() - Resource-managed devfreq_add_device()
 644  * @dev:        the device to add devfreq feature.
 645  * @profile:    device-specific profile to run devfreq.
 646  * @governor_name:      name of the policy to choose frequency.
 647  * @data:       private data for the governor. The devfreq framework does not
 648  *              touch this value.
 649  *
 650  * This function manages automatically the memory of devfreq device using device
 651  * resource management and simplify the free operation for memory of devfreq
 652  * device.
 653  */
 654 struct devfreq *devm_devfreq_add_device(struct device *dev,
 655                                         struct devfreq_dev_profile *profile,
 656                                         const char *governor_name,
 657                                         void *data)
 658 {
 659         struct devfreq **ptr, *devfreq;
 660
 661         ptr = devres_alloc(devm_devfreq_dev_release, sizeof(*ptr), GFP_KERNEL);
 662         if (!ptr)
 663                 return ERR_PTR(-ENOMEM);
 664
 665         devfreq = devfreq_add_device(dev, profile, governor_name, data);
 666         if (IS_ERR(devfreq)) {
 667                 devres_free(ptr);
 668                 return ERR_PTR(-ENOMEM);
 669         }
 670
 671         *ptr = devfreq;
 672         devres_add(dev, ptr);
 673
 674         return devfreq;
 675 }
 676 EXPORT_SYMBOL(devm_devfreq_add_device);
 677
 678 #ifdef CONFIG_OF
 679 /*
 680  * devfreq_get_devfreq_by_phandle - Get the devfreq device from devicetree
 681  * @dev - instance to the given device
 682  * @index - index into list of devfreq
 683  *
 684  * return the instance of devfreq device
 685  */
 686 struct devfreq *devfreq_get_devfreq_by_phandle(struct device *dev, int index)
 687 {
 688         struct device_node *node;
 689         struct devfreq *devfreq;
 690
 691         if (!dev)
 692                 return ERR_PTR(-EINVAL);
 693
 694         if (!dev->of_node)
 695                 return ERR_PTR(-EINVAL);
 696
 697         node = of_parse_phandle(dev->of_node, "devfreq", index);
 698         if (!node)
 699                 return ERR_PTR(-ENODEV);
 700
 701         mutex_lock(&devfreq_list_lock);
 702         list_for_each_entry(devfreq, &devfreq_list, node) {
 703                 if (devfreq->dev.parent
 704                         && devfreq->dev.parent->of_node == node) {
 705                         mutex_unlock(&devfreq_list_lock);
 706                         return devfreq;
 707                 }
 708         }
 709         mutex_unlock(&devfreq_list_lock);
 710
 711         return ERR_PTR(-EPROBE_DEFER);
 712 }
 713 #else
 714 struct devfreq *devfreq_get_devfreq_by_phandle(struct device *dev, int index)
 715 {
 716         return ERR_PTR(-ENODEV);
 717 }
 718 #endif /* CONFIG_OF */
 719 EXPORT_SYMBOL_GPL(devfreq_get_devfreq_by_phandle);
 720
 721 /**
 722  * devm_devfreq_remove_device() - Resource-managed devfreq_remove_device()
 723  * @dev:        the device to add devfreq feature.
 724  * @devfreq:    the devfreq instance to be removed
 725  */
 726 void devm_devfreq_remove_device(struct device *dev, struct devfreq *devfreq)
 727 {
 728         WARN_ON(devres_release(dev, devm_devfreq_dev_release,
 729                                devm_devfreq_dev_match, devfreq));
 730 }
 731 EXPORT_SYMBOL(devm_devfreq_remove_device);
 732
 733 /**
 734  * devfreq_suspend_device() - Suspend devfreq of a device.
 735  * @devfreq: the devfreq instance to be suspended
 736  *
 737  * This function is intended to be called by the pm callbacks
 738  * (e.g., runtime_suspend, suspend) of the device driver that
 739  * holds the devfreq.
 740  */
 741 int devfreq_suspend_device(struct devfreq *devfreq)
 742 {
 743         if (!devfreq)
 744                 return -EINVAL;
 745
 746         if (!devfreq->governor)
 747                 return 0;
 748
 749         return devfreq->governor->event_handler(devfreq,
 750                                 DEVFREQ_GOV_SUSPEND, NULL);
 751 }
 752 EXPORT_SYMBOL(devfreq_suspend_device);
 753
 754 /**
 755  * devfreq_resume_device() - Resume devfreq of a device.
 756  * @devfreq: the devfreq instance to be resumed
 757  *
 758  * This function is intended to be called by the pm callbacks
 759  * (e.g., runtime_resume, resume) of the device driver that
 760  * holds the devfreq.
 761  */
 762 int devfreq_resume_device(struct devfreq *devfreq)
 763 {
 764         if (!devfreq)
 765                 return -EINVAL;
 766
 767         if (!devfreq->governor)
 768                 return 0;
 769
 770         return devfreq->governor->event_handler(devfreq,
 771                                 DEVFREQ_GOV_RESUME, NULL);
 772 }
 773 EXPORT_SYMBOL(devfreq_resume_device);
 774
 775 /**
 776  * devfreq_add_governor() - Add devfreq governor
 777  * @governor:   the devfreq governor to be added
 778  */
 779 int devfreq_add_governor(struct devfreq_governor *governor)
 780 {
 781         struct devfreq_governor *g;
 782         struct devfreq *devfreq;
 783         int err = 0;
 784
 785         if (!governor) {
 786                 pr_err("%s: Invalid parameters.\n", __func__);
 787                 return -EINVAL;
 788         }
 789
 790         mutex_lock(&devfreq_list_lock);
 791         g = find_devfreq_governor(governor->name);
 792         if (!IS_ERR(g)) {
 793                 pr_err("%s: governor %s already registered\n", __func__,
 794                        g->name);
 795                 err = -EINVAL;
 796                 goto err_out;
 797         }
 798
 799         list_add(&governor->node, &devfreq_governor_list);
 800
 801         list_for_each_entry(devfreq, &devfreq_list, node) {
 802                 int ret = 0;
 803                 struct device *dev = devfreq->dev.parent;
 804
 805                 if (!strncmp(devfreq->governor_name, governor->name,
 806                              DEVFREQ_NAME_LEN)) {
 807                         /* The following should never occur */
 808                         if (devfreq->governor) {
 809                                 dev_warn(dev,
 810                                          "%s: Governor %s already present\n",
 811                                          __func__, devfreq->governor->name);
 812                                 ret = devfreq->governor->event_handler(devfreq,
 813                                                         DEVFREQ_GOV_STOP, NULL);
 814                                 if (ret) {
 815                                         dev_warn(dev,
 816                                                  "%s: Governor %s stop = %d\n",
 817                                                  __func__,
 818                                                  devfreq->governor->name, ret);
 819                                 }
 820                                 /* Fall through */
 821                         }
 822                         devfreq->governor = governor;
 823                         ret = devfreq->governor->event_handler(devfreq,
 824                                                 DEVFREQ_GOV_START, NULL);
 825                         if (ret) {
 826                                 dev_warn(dev, "%s: Governor %s start=%d\n",
 827                                          __func__, devfreq->governor->name,
 828                                          ret);
 829                         }
 830                 }
 831         }
 832
 833 err_out:
 834         mutex_unlock(&devfreq_list_lock);
 835
 836         return err;
 837 }
 838 EXPORT_SYMBOL(devfreq_add_governor);
 839
 840 /**
 841  * devfreq_remove_device() - Remove devfreq feature from a device.
 842  * @governor:   the devfreq governor to be removed
 843  */
 844 int devfreq_remove_governor(struct devfreq_governor *governor)
 845 {
 846         struct devfreq_governor *g;
 847         struct devfreq *devfreq;
 848         int err = 0;
 849
 850         if (!governor) {
 851                 pr_err("%s: Invalid parameters.\n", __func__);
 852                 return -EINVAL;
 853         }
 854
 855         mutex_lock(&devfreq_list_lock);
 856         g = find_devfreq_governor(governor->name);
 857         if (IS_ERR(g)) {
 858                 pr_err("%s: governor %s not registered\n", __func__,
 859                        governor->name);
 860                 err = PTR_ERR(g);
 861                 goto err_out;
 862         }
 863         list_for_each_entry(devfreq, &devfreq_list, node) {
 864                 int ret;
 865                 struct device *dev = devfreq->dev.parent;
 866
 867                 if (!strncmp(devfreq->governor_name, governor->name,
 868                              DEVFREQ_NAME_LEN)) {
 869                         /* we should have a devfreq governor! */
 870                         if (!devfreq->governor) {
 871                                 dev_warn(dev, "%s: Governor %s NOT present\n",
 872                                          __func__, governor->name);
 873                                 continue;
 874                                 /* Fall through */
 875                         }
 876                         ret = devfreq->governor->event_handler(devfreq,
 877                                                 DEVFREQ_GOV_STOP, NULL);
 878                         if (ret) {
 879                                 dev_warn(dev, "%s: Governor %s stop=%d\n",
 880                                          __func__, devfreq->governor->name,
 881                                          ret);
 882                         }
 883                         devfreq->governor = NULL;
 884                 }
 885         }
 886
 887         list_del(&governor->node);
 888 err_out:
 889         mutex_unlock(&devfreq_list_lock);
 890
 891         return err;
 892 }
 893 EXPORT_SYMBOL(devfreq_remove_governor);
 894
 895 static ssize_t governor_show(struct device *dev,
 896                              struct device_attribute *attr, char *buf)
 897 {
 898         if (!to_devfreq(dev)->governor)
 899                 return -EINVAL;
 900
 901         return sprintf(buf, "%s\n", to_devfreq(dev)->governor->name);
 902 }
 903
 904 static ssize_t governor_store(struct device *dev, struct device_attribute *attr,
 905                               const char *buf, size_t count)
 906 {
 907         struct devfreq *df = to_devfreq(dev);
 908         int ret;
 909         char str_governor[DEVFREQ_NAME_LEN + 1];
 910         struct devfreq_governor *governor;
 911
 912         ret = sscanf(buf, "%" __stringify(DEVFREQ_NAME_LEN) "s", str_governor);
 913         if (ret != 1)
 914                 return -EINVAL;
 915
 916         mutex_lock(&devfreq_list_lock);
 917         governor = find_devfreq_governor(str_governor);
 918         if (IS_ERR(governor)) {
 919                 ret = PTR_ERR(governor);
 920                 goto out;
 921         }
 922         if (df->governor == governor) {
 923                 ret = 0;
 924                 goto out;
 925         }
 926
 927         if (df->governor) {
 928                 ret = df->governor->event_handler(df, DEVFREQ_GOV_STOP, NULL);
 929                 if (ret) {
 930                         dev_warn(dev, "%s: Governor %s not stopped(%d)\n",
 931                                  __func__, df->governor->name, ret);
 932                         goto out;
 933                 }
 934         }
 935         df->governor = governor;
 936         strncpy(df->governor_name, governor->name, DEVFREQ_NAME_LEN);
 937         ret = df->governor->event_handler(df, DEVFREQ_GOV_START, NULL);
 938         if (ret)
 939                 dev_warn(dev, "%s: Governor %s not started(%d)\n",
 940                          __func__, df->governor->name, ret);
 941 out:
 942         mutex_unlock(&devfreq_list_lock);
 943
 944         if (!ret)
 945                 ret = count;
 946         return ret;
 947 }
 948 static DEVICE_ATTR_RW(governor);
 949
 950 static ssize_t available_governors_show(struct device *d,
 951                                         struct device_attribute *attr,
 952                                         char *buf)
 953 {
 954         struct devfreq_governor *tmp_governor;
 955         ssize_t count = 0;
 956
 957         mutex_lock(&devfreq_list_lock);
 958         list_for_each_entry(tmp_governor, &devfreq_governor_list, node)
 959                 count += scnprintf(&buf[count], (PAGE_SIZE - count - 2),
 960                                    "%s ", tmp_governor->name);
 961         mutex_unlock(&devfreq_list_lock);
 962
 963         /* Truncate the trailing space */
 964         if (count)
 965                 count--;
 966
 967         count += sprintf(&buf[count], "\n");
 968
 969         return count;
 970 }
 971 static DEVICE_ATTR_RO(available_governors);
 972
 973 static ssize_t cur_freq_show(struct device *dev, struct device_attribute *attr,
 974                              char *buf)
 975 {
 976         unsigned long freq;
 977         struct devfreq *devfreq = to_devfreq(dev);
 978
 979         if (devfreq->profile->get_cur_freq &&
 980                 !devfreq->profile->get_cur_freq(devfreq->dev.parent, &freq))
 981                         return sprintf(buf, "%lu\n", freq);
 982
 983         return sprintf(buf, "%lu\n", devfreq->previous_freq);
 984 }
 985 static DEVICE_ATTR_RO(cur_freq);
 986
 987 static ssize_t target_freq_show(struct device *dev,
 988                                 struct device_attribute *attr, char *buf)
 989 {
 990         return sprintf(buf, "%lu\n", to_devfreq(dev)->previous_freq);
 991 }
 992 static DEVICE_ATTR_RO(target_freq);
 993
 994 static ssize_t polling_interval_show(struct device *dev,
 995                                      struct device_attribute *attr, char *buf)
 996 {
 997         return sprintf(buf, "%d\n", to_devfreq(dev)->profile->polling_ms);
 998 }
 999
1000 static ssize_t polling_interval_store(struct device *dev,
1001                                       struct device_attribute *attr,
1002                                       const char *buf, size_t count)
1003 {
1004         struct devfreq *df = to_devfreq(dev);
1005         unsigned int value;
1006         int ret;
1007
1008         if (!df->governor)
1009                 return -EINVAL;
1010
1011         ret = sscanf(buf, "%u", &value);
1012         if (ret != 1)
1013                 return -EINVAL;
1014
1015         df->governor->event_handler(df, DEVFREQ_GOV_INTERVAL, &value);
1016         ret = count;
1017
1018         return ret;
1019 }
1020 static DEVICE_ATTR_RW(polling_interval);
1021
1022 static ssize_t min_freq_store(struct device *dev, struct device_attribute *attr,
1023                               const char *buf, size_t count)
1024 {
1025         struct devfreq *df = to_devfreq(dev);
1026         unsigned long value;
1027         int ret;
1028         unsigned long max;
1029
1030         ret = sscanf(buf, "%lu", &value);
1031         if (ret != 1)
1032                 return -EINVAL;
1033
1034         mutex_lock(&df->lock);
1035         max = df->max_freq;
1036         if (value && max && value > max) {
1037                 ret = -EINVAL;
1038                 goto unlock;
1039         }
1040
1041         df->min_freq = value;
1042         update_devfreq(df);
1043         ret = count;
1044 unlock:
1045         mutex_unlock(&df->lock);
1046         return ret;
1047 }
1048
1049 static ssize_t max_freq_store(struct device *dev, struct device_attribute *attr,
1050                               const char *buf, size_t count)
1051 {
1052         struct devfreq *df = to_devfreq(dev);
1053         unsigned long value;
1054         int ret;
1055         unsigned long min;
1056
1057         ret = sscanf(buf, "%lu", &value);
1058         if (ret != 1)
1059                 return -EINVAL;
1060
1061         mutex_lock(&df->lock);
1062         min = df->min_freq;
1063         if (value && min && value < min) {
1064                 ret = -EINVAL;
1065                 goto unlock;
1066         }
1067
1068         df->max_freq = value;
1069         update_devfreq(df);
1070         ret = count;
1071 unlock:
1072         mutex_unlock(&df->lock);
1073         return ret;
1074 }
1075
1076 #define show_one(name)                                          \
1077 static ssize_t name##_show                                      \
1078 (struct device *dev, struct device_attribute *attr, char *buf)  \
1079 {                                                               \
1080         return sprintf(buf, "%lu\n", to_devfreq(dev)->name);    \
1081 }
1082 show_one(min_freq);
1083 show_one(max_freq);
1084
1085 static DEVICE_ATTR_RW(min_freq);
1086 static DEVICE_ATTR_RW(max_freq);
1087
1088 static ssize_t available_frequencies_show(struct device *d,
1089                                           struct device_attribute *attr,
1090                                           char *buf)
1091 {
1092         struct devfreq *df = to_devfreq(d);
1093         struct device *dev = df->dev.parent;
1094         struct dev_pm_opp *opp;
1095         ssize_t count = 0;
1096         unsigned long freq = 0;
1097
1098         rcu_read_lock();
1099         do {
1100                 opp = dev_pm_opp_find_freq_ceil(dev, &freq);
1101                 if (IS_ERR(opp))
1102                         break;
1103
1104                 count += scnprintf(&buf[count], (PAGE_SIZE - count - 2),
1105                                    "%lu ", freq);
1106                 freq++;
1107         } while (1);
1108         rcu_read_unlock();
1109
1110         /* Truncate the trailing space */
1111         if (count)
1112                 count--;
1113
1114         count += sprintf(&buf[count], "\n");
1115
1116         return count;
1117 }
1118 static DEVICE_ATTR_RO(available_frequencies);
1119
1120 static ssize_t trans_stat_show(struct device *dev,
1121                                struct device_attribute *attr, char *buf)
1122 {
1123         struct devfreq *devfreq = to_devfreq(dev);
1124         ssize_t len;
1125         int i, j;
1126         unsigned int max_state = devfreq->profile->max_state;
1127
1128         if (!devfreq->stop_polling &&
1129                         devfreq_update_status(devfreq, devfreq->previous_freq))
1130                 return 0;
1131         if (max_state == 0)
1132                 return sprintf(buf, "Not Supported.\n");
1133
1134         len = sprintf(buf, "     From  :   To\n");
1135         len += sprintf(buf + len, "           :");
1136         for (i = 0; i < max_state; i++)
1137                 len += sprintf(buf + len, "%10lu",
1138                                 devfreq->profile->freq_table[i]);
1139
1140         len += sprintf(buf + len, "   time(ms)\n");
1141
1142         for (i = 0; i < max_state; i++) {
1143                 if (devfreq->profile->freq_table[i]
1144                                         == devfreq->previous_freq) {
1145                         len += sprintf(buf + len, "*");
1146                 } else {
1147                         len += sprintf(buf + len, " ");
1148                 }
1149                 len += sprintf(buf + len, "%10lu:",
1150                                 devfreq->profile->freq_table[i]);
1151                 for (j = 0; j < max_state; j++)
1152                         len += sprintf(buf + len, "%10u",
1153                                 devfreq->trans_table[(i * max_state) + j]);
1154                 len += sprintf(buf + len, "%10u\n",
1155                         jiffies_to_msecs(devfreq->time_in_state[i]));
1156         }
1157
1158         len += sprintf(buf + len, "Total transition : %u\n",
1159                                         devfreq->total_trans);
1160         return len;
1161 }
1162 static DEVICE_ATTR_RO(trans_stat);
1163
1164 static struct attribute *devfreq_attrs[] = {
1165         &dev_attr_governor.attr,
1166         &dev_attr_available_governors.attr,
1167         &dev_attr_cur_freq.attr,
1168         &dev_attr_available_frequencies.attr,
1169         &dev_attr_target_freq.attr,
1170         &dev_attr_polling_interval.attr,
1171         &dev_attr_min_freq.attr,
1172         &dev_attr_max_freq.attr,
1173         &dev_attr_trans_stat.attr,
1174         NULL,
1175 };
1176 ATTRIBUTE_GROUPS(devfreq);
1177
1178 static int __init devfreq_init(void)
1179 {
1180         devfreq_class = class_create(THIS_MODULE, "devfreq");
1181         if (IS_ERR(devfreq_class)) {
1182                 pr_err("%s: couldn't create class\n", __FILE__);
1183                 return PTR_ERR(devfreq_class);
1184         }
1185
1186         devfreq_wq = create_freezable_workqueue("devfreq_wq");
1187         if (!devfreq_wq) {
1188                 class_destroy(devfreq_class);
1189                 pr_err("%s: couldn't create workqueue\n", __FILE__);
1190                 return -ENOMEM;
1191         }
1192         devfreq_class->dev_groups = devfreq_groups;
1193
1194         return 0;
1195 }
1196 subsys_initcall(devfreq_init);
1197
1198 static void __exit devfreq_exit(void)
1199 {
1200         class_destroy(devfreq_class);
1201         destroy_workqueue(devfreq_wq);
1202 }
1203 module_exit(devfreq_exit);
1204
1205 /*
1206  * The followings are helper functions for devfreq user device drivers with
1207  * OPP framework.
1208  */
1209
1210 /**
1211  * devfreq_recommended_opp() - Helper function to get proper OPP for the
1212  *                           freq value given to target callback.
1213  * @dev:        The devfreq user device. (parent of devfreq)
1214  * @freq:       The frequency given to target function
1215  * @flags:      Flags handed from devfreq framework.
1216  *
1217  * Locking: This function must be called under rcu_read_lock(). opp is a rcu
1218  * protected pointer. The reason for the same is that the opp pointer which is
1219  * returned will remain valid for use with opp_get_{voltage, freq} only while
1220  * under the locked area. The pointer returned must be used prior to unlocking
1221  * with rcu_read_unlock() to maintain the integrity of the pointer.
1222  */
1223 struct dev_pm_opp *devfreq_recommended_opp(struct device *dev,
1224                                            unsigned long *freq,
1225                                            u32 flags)
1226 {
1227         struct dev_pm_opp *opp;
1228
1229         if (flags & DEVFREQ_FLAG_LEAST_UPPER_BOUND) {
1230                 /* The freq is an upper bound. opp should be lower */
1231                 opp = dev_pm_opp_find_freq_floor(dev, freq);
1232
1233                 /* If not available, use the closest opp */
1234                 if (opp == ERR_PTR(-ERANGE))
1235                         opp = dev_pm_opp_find_freq_ceil(dev, freq);
1236         } else {
1237                 /* The freq is an lower bound. opp should be higher */
1238                 opp = dev_pm_opp_find_freq_ceil(dev, freq);
1239
1240                 /* If not available, use the closest opp */
1241                 if (opp == ERR_PTR(-ERANGE))
1242                         opp = dev_pm_opp_find_freq_floor(dev, freq);
1243         }
1244
1245         return opp;
1246 }
1247 EXPORT_SYMBOL(devfreq_recommended_opp);
1248
1249 /**
1250  * devfreq_register_opp_notifier() - Helper function to get devfreq notified
1251  *                                 for any changes in the OPP availability
1252  *                                 changes
1253  * @dev:        The devfreq user device. (parent of devfreq)
1254  * @devfreq:    The devfreq object.
1255  */
1256 int devfreq_register_opp_notifier(struct device *dev, struct devfreq *devfreq)
1257 {
1258         struct srcu_notifier_head *nh;
1259         int ret = 0;
1260
1261         rcu_read_lock();
1262         nh = dev_pm_opp_get_notifier(dev);
1263         if (IS_ERR(nh))
1264                 ret = PTR_ERR(nh);
1265         rcu_read_unlock();
1266         if (!ret)
1267                 ret = srcu_notifier_chain_register(nh, &devfreq->nb);
1268
1269         return ret;
1270 }
1271 EXPORT_SYMBOL(devfreq_register_opp_notifier);
1272
1273 /**
1274  * devfreq_unregister_opp_notifier() - Helper function to stop getting devfreq
1275  *                                   notified for any changes in the OPP
1276  *                                   availability changes anymore.
1277  * @dev:        The devfreq user device. (parent of devfreq)
1278  * @devfreq:    The devfreq object.
1279  *
1280  * At exit() callback of devfreq_dev_profile, this must be included if
1281  * devfreq_recommended_opp is used.
1282  */
1283 int devfreq_unregister_opp_notifier(struct device *dev, struct devfreq *devfreq)
1284 {
1285         struct srcu_notifier_head *nh;
1286         int ret = 0;
1287
1288         rcu_read_lock();
1289         nh = dev_pm_opp_get_notifier(dev);
1290         if (IS_ERR(nh))
1291                 ret = PTR_ERR(nh);
1292         rcu_read_unlock();
1293         if (!ret)
1294                 ret = srcu_notifier_chain_unregister(nh, &devfreq->nb);
1295
1296         return ret;
1297 }
1298 EXPORT_SYMBOL(devfreq_unregister_opp_notifier);
1299
1300 static void devm_devfreq_opp_release(struct device *dev, void *res)
1301 {
1302         devfreq_unregister_opp_notifier(dev, *(struct devfreq **)res);
1303 }
1304
1305 /**
1306  * devm_ devfreq_register_opp_notifier()
1307  *              - Resource-managed devfreq_register_opp_notifier()
1308  * @dev:        The devfreq user device. (parent of devfreq)
1309  * @devfreq:    The devfreq object.
1310  */
1311 int devm_devfreq_register_opp_notifier(struct device *dev,
1312                                        struct devfreq *devfreq)
1313 {
1314         struct devfreq **ptr;
1315         int ret;
1316
1317         ptr = devres_alloc(devm_devfreq_opp_release, sizeof(*ptr), GFP_KERNEL);
1318         if (!ptr)
1319                 return -ENOMEM;
1320
1321         ret = devfreq_register_opp_notifier(dev, devfreq);
1322         if (ret) {
1323                 devres_free(ptr);
1324                 return ret;
1325         }
1326
1327         *ptr = devfreq;
1328         devres_add(dev, ptr);
1329
1330         return 0;
1331 }
1332 EXPORT_SYMBOL(devm_devfreq_register_opp_notifier);
1333
1334 /**
1335  * devm_devfreq_unregister_opp_notifier()
1336  *              - Resource-managed devfreq_unregister_opp_notifier()
1337  * @dev:        The devfreq user device. (parent of devfreq)
1338  * @devfreq:    The devfreq object.
1339  */
1340 void devm_devfreq_unregister_opp_notifier(struct device *dev,
1341                                          struct devfreq *devfreq)
1342 {
1343         WARN_ON(devres_release(dev, devm_devfreq_opp_release,
1344                                devm_devfreq_dev_match, devfreq));
1345 }
1346 EXPORT_SYMBOL(devm_devfreq_unregister_opp_notifier);
1347
1348 /**
1349  * devfreq_register_notifier() - Register a driver with devfreq
1350  * @devfreq:    The devfreq object.
1351  * @nb:         The notifier block to register.
1352  * @list:       DEVFREQ_TRANSITION_NOTIFIER.
1353  */
1354 int devfreq_register_notifier(struct devfreq *devfreq,
1355                                 struct notifier_block *nb,
1356                                 unsigned int list)
1357 {
1358         int ret = 0;
1359
1360         if (!devfreq)
1361                 return -EINVAL;
1362
1363         switch (list) {
1364         case DEVFREQ_TRANSITION_NOTIFIER:
1365                 ret = srcu_notifier_chain_register(
1366                                 &devfreq->transition_notifier_list, nb);
1367                 break;
1368         default:
1369                 ret = -EINVAL;
1370         }
1371
1372         return ret;
1373 }
1374 EXPORT_SYMBOL(devfreq_register_notifier);
1375
1376 /*
1377  * devfreq_unregister_notifier() - Unregister a driver with devfreq
1378  * @devfreq:    The devfreq object.
1379  * @nb:         The notifier block to be unregistered.
1380  * @list:       DEVFREQ_TRANSITION_NOTIFIER.
1381  */
1382 int devfreq_unregister_notifier(struct devfreq *devfreq,
1383                                 struct notifier_block *nb,
1384                                 unsigned int list)
1385 {
1386         int ret = 0;
1387
1388         if (!devfreq)
1389                 return -EINVAL;
1390
1391         switch (list) {
1392         case DEVFREQ_TRANSITION_NOTIFIER:
1393                 ret = srcu_notifier_chain_unregister(
1394                                 &devfreq->transition_notifier_list, nb);
1395                 break;
1396         default:
1397                 ret = -EINVAL;
1398         }
1399
1400         return ret;
1401 }
1402 EXPORT_SYMBOL(devfreq_unregister_notifier);
1403
1404 struct devfreq_notifier_devres {
1405         struct devfreq *devfreq;
1406         struct notifier_block *nb;
1407         unsigned int list;
1408 };
1409
1410 static void devm_devfreq_notifier_release(struct device *dev, void *res)
1411 {
1412         struct devfreq_notifier_devres *this = res;
1413
1414         devfreq_unregister_notifier(this->devfreq, this->nb, this->list);
1415 }
1416
1417 /**
1418  * devm_devfreq_register_notifier()
1419         - Resource-managed devfreq_register_notifier()
1420  * @dev:        The devfreq user device. (parent of devfreq)
1421  * @devfreq:    The devfreq object.
1422  * @nb:         The notifier block to be unregistered.
1423  * @list:       DEVFREQ_TRANSITION_NOTIFIER.
1424  */
1425 int devm_devfreq_register_notifier(struct device *dev,
1426                                 struct devfreq *devfreq,
1427                                 struct notifier_block *nb,
1428                                 unsigned int list)
1429 {
1430         struct devfreq_notifier_devres *ptr;
1431         int ret;
1432
1433         ptr = devres_alloc(devm_devfreq_notifier_release, sizeof(*ptr),
1434                                 GFP_KERNEL);
1435         if (!ptr)
1436                 return -ENOMEM;
1437
1438         ret = devfreq_register_notifier(devfreq, nb, list);
1439         if (ret) {
1440                 devres_free(ptr);
1441                 return ret;
1442         }
1443
1444         ptr->devfreq = devfreq;
1445         ptr->nb = nb;
1446         ptr->list = list;
1447         devres_add(dev, ptr);
1448
1449         return 0;
1450 }
1451 EXPORT_SYMBOL(devm_devfreq_register_notifier);
1452
1453 /**
1454  * devm_devfreq_unregister_notifier()
1455         - Resource-managed devfreq_unregister_notifier()
1456  * @dev:        The devfreq user device. (parent of devfreq)
1457  * @devfreq:    The devfreq object.
1458  * @nb:         The notifier block to be unregistered.
1459  * @list:       DEVFREQ_TRANSITION_NOTIFIER.
1460  */
1461 void devm_devfreq_unregister_notifier(struct device *dev,
1462                                 struct devfreq *devfreq,
1463                                 struct notifier_block *nb,
1464                                 unsigned int list)
1465 {
1466         WARN_ON(devres_release(dev, devm_devfreq_notifier_release,
1467                                devm_devfreq_dev_match, devfreq));
1468 }
1469 EXPORT_SYMBOL(devm_devfreq_unregister_notifier);
1470
1471 MODULE_AUTHOR("MyungJoo Ham <myungjoo.ham@samsung.com>");
1472 MODULE_DESCRIPTION("devfreq class support");
1473 MODULE_LICENSE("GPL");