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         devfreq->trans_table =  devm_kzalloc(dev, sizeof(unsigned int) *
 565                                                 devfreq->profile->max_state *
 566                                                 devfreq->profile->max_state,
 567                                                 GFP_KERNEL);
 568         devfreq->time_in_state = devm_kzalloc(dev, sizeof(unsigned long) *
 569                                                 devfreq->profile->max_state,
 570                                                 GFP_KERNEL);
 571         devfreq->last_stat_updated = jiffies;
 572
 573         dev_set_name(&devfreq->dev, "%s", dev_name(dev));
 574         err = device_register(&devfreq->dev);
 575         if (err) {
 576                 put_device(&devfreq->dev);
 577                 mutex_unlock(&devfreq->lock);
 578                 goto err_out;
 579         }
 580
 581         srcu_init_notifier_head(&devfreq->transition_notifier_list);
 582
 583         mutex_unlock(&devfreq->lock);
 584
 585         mutex_lock(&devfreq_list_lock);
 586         list_add(&devfreq->node, &devfreq_list);
 587
 588         governor = find_devfreq_governor(devfreq->governor_name);
 589         if (!IS_ERR(governor))
 590                 devfreq->governor = governor;
 591         if (devfreq->governor)
 592                 err = devfreq->governor->event_handler(devfreq,
 593                                         DEVFREQ_GOV_START, NULL);
 594         mutex_unlock(&devfreq_list_lock);
 595         if (err) {
 596                 dev_err(dev, "%s: Unable to start governor for the device\n",
 597                         __func__);
 598                 goto err_init;
 599         }
 600
 601         return devfreq;
 602
 603 err_init:
 604         list_del(&devfreq->node);
 605         device_unregister(&devfreq->dev);
 606         kfree(devfreq);
 607 err_out:
 608         return ERR_PTR(err);
 609 }
 610 EXPORT_SYMBOL(devfreq_add_device);
 611
 612 /**
 613  * devfreq_remove_device() - Remove devfreq feature from a device.
 614  * @devfreq:    the devfreq instance to be removed
 615  *
 616  * The opposite of devfreq_add_device().
 617  */
 618 int devfreq_remove_device(struct devfreq *devfreq)
 619 {
 620         if (!devfreq)
 621                 return -EINVAL;
 622
 623         device_unregister(&devfreq->dev);
 624         put_device(&devfreq->dev);
 625
 626         return 0;
 627 }
 628 EXPORT_SYMBOL(devfreq_remove_device);
 629
 630 static int devm_devfreq_dev_match(struct device *dev, void *res, void *data)
 631 {
 632         struct devfreq **r = res;
 633
 634         if (WARN_ON(!r || !*r))
 635                 return 0;
 636
 637         return *r == data;
 638 }
 639
 640 static void devm_devfreq_dev_release(struct device *dev, void *res)
 641 {
 642         devfreq_remove_device(*(struct devfreq **)res);
 643 }
 644
 645 /**
 646  * devm_devfreq_add_device() - Resource-managed devfreq_add_device()
 647  * @dev:        the device to add devfreq feature.
 648  * @profile:    device-specific profile to run devfreq.
 649  * @governor_name:      name of the policy to choose frequency.
 650  * @data:       private data for the governor. The devfreq framework does not
 651  *              touch this value.
 652  *
 653  * This function manages automatically the memory of devfreq device using device
 654  * resource management and simplify the free operation for memory of devfreq
 655  * device.
 656  */
 657 struct devfreq *devm_devfreq_add_device(struct device *dev,
 658                                         struct devfreq_dev_profile *profile,
 659                                         const char *governor_name,
 660                                         void *data)
 661 {
 662         struct devfreq **ptr, *devfreq;
 663
 664         ptr = devres_alloc(devm_devfreq_dev_release, sizeof(*ptr), GFP_KERNEL);
 665         if (!ptr)
 666                 return ERR_PTR(-ENOMEM);
 667
 668         devfreq = devfreq_add_device(dev, profile, governor_name, data);
 669         if (IS_ERR(devfreq)) {
 670                 devres_free(ptr);
 671                 return ERR_PTR(-ENOMEM);
 672         }
 673
 674         *ptr = devfreq;
 675         devres_add(dev, ptr);
 676
 677         return devfreq;
 678 }
 679 EXPORT_SYMBOL(devm_devfreq_add_device);
 680
 681 #ifdef CONFIG_OF
 682 /*
 683  * devfreq_get_devfreq_by_phandle - Get the devfreq device from devicetree
 684  * @dev - instance to the given device
 685  * @index - index into list of devfreq
 686  *
 687  * return the instance of devfreq device
 688  */
 689 struct devfreq *devfreq_get_devfreq_by_phandle(struct device *dev, int index)
 690 {
 691         struct device_node *node;
 692         struct devfreq *devfreq;
 693
 694         if (!dev)
 695                 return ERR_PTR(-EINVAL);
 696
 697         if (!dev->of_node)
 698                 return ERR_PTR(-EINVAL);
 699
 700         node = of_parse_phandle(dev->of_node, "devfreq", index);
 701         if (!node)
 702                 return ERR_PTR(-ENODEV);
 703
 704         mutex_lock(&devfreq_list_lock);
 705         list_for_each_entry(devfreq, &devfreq_list, node) {
 706                 if (devfreq->dev.parent
 707                         && devfreq->dev.parent->of_node == node) {
 708                         mutex_unlock(&devfreq_list_lock);
 709                         return devfreq;
 710                 }
 711         }
 712         mutex_unlock(&devfreq_list_lock);
 713
 714         return ERR_PTR(-EPROBE_DEFER);
 715 }
 716 #else
 717 struct devfreq *devfreq_get_devfreq_by_phandle(struct device *dev, int index)
 718 {
 719         return ERR_PTR(-ENODEV);
 720 }
 721 #endif /* CONFIG_OF */
 722 EXPORT_SYMBOL_GPL(devfreq_get_devfreq_by_phandle);
 723
 724 /**
 725  * devm_devfreq_remove_device() - Resource-managed devfreq_remove_device()
 726  * @dev:        the device to add devfreq feature.
 727  * @devfreq:    the devfreq instance to be removed
 728  */
 729 void devm_devfreq_remove_device(struct device *dev, struct devfreq *devfreq)
 730 {
 731         WARN_ON(devres_release(dev, devm_devfreq_dev_release,
 732                                devm_devfreq_dev_match, devfreq));
 733 }
 734 EXPORT_SYMBOL(devm_devfreq_remove_device);
 735
 736 /**
 737  * devfreq_suspend_device() - Suspend devfreq of a device.
 738  * @devfreq: the devfreq instance to be suspended
 739  *
 740  * This function is intended to be called by the pm callbacks
 741  * (e.g., runtime_suspend, suspend) of the device driver that
 742  * holds the devfreq.
 743  */
 744 int devfreq_suspend_device(struct devfreq *devfreq)
 745 {
 746         if (!devfreq)
 747                 return -EINVAL;
 748
 749         if (!devfreq->governor)
 750                 return 0;
 751
 752         return devfreq->governor->event_handler(devfreq,
 753                                 DEVFREQ_GOV_SUSPEND, NULL);
 754 }
 755 EXPORT_SYMBOL(devfreq_suspend_device);
 756
 757 /**
 758  * devfreq_resume_device() - Resume devfreq of a device.
 759  * @devfreq: the devfreq instance to be resumed
 760  *
 761  * This function is intended to be called by the pm callbacks
 762  * (e.g., runtime_resume, resume) of the device driver that
 763  * holds the devfreq.
 764  */
 765 int devfreq_resume_device(struct devfreq *devfreq)
 766 {
 767         if (!devfreq)
 768                 return -EINVAL;
 769
 770         if (!devfreq->governor)
 771                 return 0;
 772
 773         return devfreq->governor->event_handler(devfreq,
 774                                 DEVFREQ_GOV_RESUME, NULL);
 775 }
 776 EXPORT_SYMBOL(devfreq_resume_device);
 777
 778 /**
 779  * devfreq_add_governor() - Add devfreq governor
 780  * @governor:   the devfreq governor to be added
 781  */
 782 int devfreq_add_governor(struct devfreq_governor *governor)
 783 {
 784         struct devfreq_governor *g;
 785         struct devfreq *devfreq;
 786         int err = 0;
 787
 788         if (!governor) {
 789                 pr_err("%s: Invalid parameters.\n", __func__);
 790                 return -EINVAL;
 791         }
 792
 793         mutex_lock(&devfreq_list_lock);
 794         g = find_devfreq_governor(governor->name);
 795         if (!IS_ERR(g)) {
 796                 pr_err("%s: governor %s already registered\n", __func__,
 797                        g->name);
 798                 err = -EINVAL;
 799                 goto err_out;
 800         }
 801
 802         list_add(&governor->node, &devfreq_governor_list);
 803
 804         list_for_each_entry(devfreq, &devfreq_list, node) {
 805                 int ret = 0;
 806                 struct device *dev = devfreq->dev.parent;
 807
 808                 if (!strncmp(devfreq->governor_name, governor->name,
 809                              DEVFREQ_NAME_LEN)) {
 810                         /* The following should never occur */
 811                         if (devfreq->governor) {
 812                                 dev_warn(dev,
 813                                          "%s: Governor %s already present\n",
 814                                          __func__, devfreq->governor->name);
 815                                 ret = devfreq->governor->event_handler(devfreq,
 816                                                         DEVFREQ_GOV_STOP, NULL);
 817                                 if (ret) {
 818                                         dev_warn(dev,
 819                                                  "%s: Governor %s stop = %d\n",
 820                                                  __func__,
 821                                                  devfreq->governor->name, ret);
 822                                 }
 823                                 /* Fall through */
 824                         }
 825                         devfreq->governor = governor;
 826                         ret = devfreq->governor->event_handler(devfreq,
 827                                                 DEVFREQ_GOV_START, NULL);
 828                         if (ret) {
 829                                 dev_warn(dev, "%s: Governor %s start=%d\n",
 830                                          __func__, devfreq->governor->name,
 831                                          ret);
 832                         }
 833                 }
 834         }
 835
 836 err_out:
 837         mutex_unlock(&devfreq_list_lock);
 838
 839         return err;
 840 }
 841 EXPORT_SYMBOL(devfreq_add_governor);
 842
 843 /**
 844  * devfreq_remove_device() - Remove devfreq feature from a device.
 845  * @governor:   the devfreq governor to be removed
 846  */
 847 int devfreq_remove_governor(struct devfreq_governor *governor)
 848 {
 849         struct devfreq_governor *g;
 850         struct devfreq *devfreq;
 851         int err = 0;
 852
 853         if (!governor) {
 854                 pr_err("%s: Invalid parameters.\n", __func__);
 855                 return -EINVAL;
 856         }
 857
 858         mutex_lock(&devfreq_list_lock);
 859         g = find_devfreq_governor(governor->name);
 860         if (IS_ERR(g)) {
 861                 pr_err("%s: governor %s not registered\n", __func__,
 862                        governor->name);
 863                 err = PTR_ERR(g);
 864                 goto err_out;
 865         }
 866         list_for_each_entry(devfreq, &devfreq_list, node) {
 867                 int ret;
 868                 struct device *dev = devfreq->dev.parent;
 869
 870                 if (!strncmp(devfreq->governor_name, governor->name,
 871                              DEVFREQ_NAME_LEN)) {
 872                         /* we should have a devfreq governor! */
 873                         if (!devfreq->governor) {
 874                                 dev_warn(dev, "%s: Governor %s NOT present\n",
 875                                          __func__, governor->name);
 876                                 continue;
 877                                 /* Fall through */
 878                         }
 879                         ret = devfreq->governor->event_handler(devfreq,
 880                                                 DEVFREQ_GOV_STOP, NULL);
 881                         if (ret) {
 882                                 dev_warn(dev, "%s: Governor %s stop=%d\n",
 883                                          __func__, devfreq->governor->name,
 884                                          ret);
 885                         }
 886                         devfreq->governor = NULL;
 887                 }
 888         }
 889
 890         list_del(&governor->node);
 891 err_out:
 892         mutex_unlock(&devfreq_list_lock);
 893
 894         return err;
 895 }
 896 EXPORT_SYMBOL(devfreq_remove_governor);
 897
 898 static ssize_t governor_show(struct device *dev,
 899                              struct device_attribute *attr, char *buf)
 900 {
 901         if (!to_devfreq(dev)->governor)
 902                 return -EINVAL;
 903
 904         return sprintf(buf, "%s\n", to_devfreq(dev)->governor->name);
 905 }
 906
 907 static ssize_t governor_store(struct device *dev, struct device_attribute *attr,
 908                               const char *buf, size_t count)
 909 {
 910         struct devfreq *df = to_devfreq(dev);
 911         int ret;
 912         char str_governor[DEVFREQ_NAME_LEN + 1];
 913         struct devfreq_governor *governor;
 914
 915         ret = sscanf(buf, "%" __stringify(DEVFREQ_NAME_LEN) "s", str_governor);
 916         if (ret != 1)
 917                 return -EINVAL;
 918
 919         mutex_lock(&devfreq_list_lock);
 920         governor = find_devfreq_governor(str_governor);
 921         if (IS_ERR(governor)) {
 922                 ret = PTR_ERR(governor);
 923                 goto out;
 924         }
 925         if (df->governor == governor) {
 926                 ret = 0;
 927                 goto out;
 928         }
 929
 930         if (df->governor) {
 931                 ret = df->governor->event_handler(df, DEVFREQ_GOV_STOP, NULL);
 932                 if (ret) {
 933                         dev_warn(dev, "%s: Governor %s not stopped(%d)\n",
 934                                  __func__, df->governor->name, ret);
 935                         goto out;
 936                 }
 937         }
 938         df->governor = governor;
 939         strncpy(df->governor_name, governor->name, DEVFREQ_NAME_LEN);
 940         ret = df->governor->event_handler(df, DEVFREQ_GOV_START, NULL);
 941         if (ret)
 942                 dev_warn(dev, "%s: Governor %s not started(%d)\n",
 943                          __func__, df->governor->name, ret);
 944 out:
 945         mutex_unlock(&devfreq_list_lock);
 946
 947         if (!ret)
 948                 ret = count;
 949         return ret;
 950 }
 951 static DEVICE_ATTR_RW(governor);
 952
 953 static ssize_t available_governors_show(struct device *d,
 954                                         struct device_attribute *attr,
 955                                         char *buf)
 956 {
 957         struct devfreq_governor *tmp_governor;
 958         ssize_t count = 0;
 959
 960         mutex_lock(&devfreq_list_lock);
 961         list_for_each_entry(tmp_governor, &devfreq_governor_list, node)
 962                 count += scnprintf(&buf[count], (PAGE_SIZE - count - 2),
 963                                    "%s ", tmp_governor->name);
 964         mutex_unlock(&devfreq_list_lock);
 965
 966         /* Truncate the trailing space */
 967         if (count)
 968                 count--;
 969
 970         count += sprintf(&buf[count], "\n");
 971
 972         return count;
 973 }
 974 static DEVICE_ATTR_RO(available_governors);
 975
 976 static ssize_t cur_freq_show(struct device *dev, struct device_attribute *attr,
 977                              char *buf)
 978 {
 979         unsigned long freq;
 980         struct devfreq *devfreq = to_devfreq(dev);
 981
 982         if (devfreq->profile->get_cur_freq &&
 983                 !devfreq->profile->get_cur_freq(devfreq->dev.parent, &freq))
 984                         return sprintf(buf, "%lu\n", freq);
 985
 986         return sprintf(buf, "%lu\n", devfreq->previous_freq);
 987 }
 988 static DEVICE_ATTR_RO(cur_freq);
 989
 990 static ssize_t target_freq_show(struct device *dev,
 991                                 struct device_attribute *attr, char *buf)
 992 {
 993         return sprintf(buf, "%lu\n", to_devfreq(dev)->previous_freq);
 994 }
 995 static DEVICE_ATTR_RO(target_freq);
 996
 997 static ssize_t polling_interval_show(struct device *dev,
 998                                      struct device_attribute *attr, char *buf)
 999 {
1000         return sprintf(buf, "%d\n", to_devfreq(dev)->profile->polling_ms);
1001 }
1002
1003 static ssize_t polling_interval_store(struct device *dev,
1004                                       struct device_attribute *attr,
1005                                       const char *buf, size_t count)
1006 {
1007         struct devfreq *df = to_devfreq(dev);
1008         unsigned int value;
1009         int ret;
1010
1011         if (!df->governor)
1012                 return -EINVAL;
1013
1014         ret = sscanf(buf, "%u", &value);
1015         if (ret != 1)
1016                 return -EINVAL;
1017
1018         df->governor->event_handler(df, DEVFREQ_GOV_INTERVAL, &value);
1019         ret = count;
1020
1021         return ret;
1022 }
1023 static DEVICE_ATTR_RW(polling_interval);
1024
1025 static ssize_t min_freq_store(struct device *dev, struct device_attribute *attr,
1026                               const char *buf, size_t count)
1027 {
1028         struct devfreq *df = to_devfreq(dev);
1029         unsigned long value;
1030         int ret;
1031         unsigned long max;
1032
1033         ret = sscanf(buf, "%lu", &value);
1034         if (ret != 1)
1035                 return -EINVAL;
1036
1037         mutex_lock(&df->lock);
1038         max = df->max_freq;
1039         if (value && max && value > max) {
1040                 ret = -EINVAL;
1041                 goto unlock;
1042         }
1043
1044         df->min_freq = value;
1045         update_devfreq(df);
1046         ret = count;
1047 unlock:
1048         mutex_unlock(&df->lock);
1049         return ret;
1050 }
1051
1052 static ssize_t max_freq_store(struct device *dev, struct device_attribute *attr,
1053                               const char *buf, size_t count)
1054 {
1055         struct devfreq *df = to_devfreq(dev);
1056         unsigned long value;
1057         int ret;
1058         unsigned long min;
1059
1060         ret = sscanf(buf, "%lu", &value);
1061         if (ret != 1)
1062                 return -EINVAL;
1063
1064         mutex_lock(&df->lock);
1065         min = df->min_freq;
1066         if (value && min && value < min) {
1067                 ret = -EINVAL;
1068                 goto unlock;
1069         }
1070
1071         df->max_freq = value;
1072         update_devfreq(df);
1073         ret = count;
1074 unlock:
1075         mutex_unlock(&df->lock);
1076         return ret;
1077 }
1078
1079 #define show_one(name)                                          \
1080 static ssize_t name##_show                                      \
1081 (struct device *dev, struct device_attribute *attr, char *buf)  \
1082 {                                                               \
1083         return sprintf(buf, "%lu\n", to_devfreq(dev)->name);    \
1084 }
1085 show_one(min_freq);
1086 show_one(max_freq);
1087
1088 static DEVICE_ATTR_RW(min_freq);
1089 static DEVICE_ATTR_RW(max_freq);
1090
1091 static ssize_t available_frequencies_show(struct device *d,
1092                                           struct device_attribute *attr,
1093                                           char *buf)
1094 {
1095         struct devfreq *df = to_devfreq(d);
1096         struct device *dev = df->dev.parent;
1097         struct dev_pm_opp *opp;
1098         ssize_t count = 0;
1099         unsigned long freq = 0;
1100
1101         rcu_read_lock();
1102         do {
1103                 opp = dev_pm_opp_find_freq_ceil(dev, &freq);
1104                 if (IS_ERR(opp))
1105                         break;
1106
1107                 count += scnprintf(&buf[count], (PAGE_SIZE - count - 2),
1108                                    "%lu ", freq);
1109                 freq++;
1110         } while (1);
1111         rcu_read_unlock();
1112
1113         /* Truncate the trailing space */
1114         if (count)
1115                 count--;
1116
1117         count += sprintf(&buf[count], "\n");
1118
1119         return count;
1120 }
1121 static DEVICE_ATTR_RO(available_frequencies);
1122
1123 static ssize_t trans_stat_show(struct device *dev,
1124                                struct device_attribute *attr, char *buf)
1125 {
1126         struct devfreq *devfreq = to_devfreq(dev);
1127         ssize_t len;
1128         int i, j;
1129         unsigned int max_state = devfreq->profile->max_state;
1130
1131         if (!devfreq->stop_polling &&
1132                         devfreq_update_status(devfreq, devfreq->previous_freq))
1133                 return 0;
1134         if (max_state == 0)
1135                 return sprintf(buf, "Not Supported.\n");
1136
1137         len = sprintf(buf, "     From  :   To\n");
1138         len += sprintf(buf + len, "           :");
1139         for (i = 0; i < max_state; i++)
1140                 len += sprintf(buf + len, "%10lu",
1141                                 devfreq->profile->freq_table[i]);
1142
1143         len += sprintf(buf + len, "   time(ms)\n");
1144
1145         for (i = 0; i < max_state; i++) {
1146                 if (devfreq->profile->freq_table[i]
1147                                         == devfreq->previous_freq) {
1148                         len += sprintf(buf + len, "*");
1149                 } else {
1150                         len += sprintf(buf + len, " ");
1151                 }
1152                 len += sprintf(buf + len, "%10lu:",
1153                                 devfreq->profile->freq_table[i]);
1154                 for (j = 0; j < max_state; j++)
1155                         len += sprintf(buf + len, "%10u",
1156                                 devfreq->trans_table[(i * max_state) + j]);
1157                 len += sprintf(buf + len, "%10u\n",
1158                         jiffies_to_msecs(devfreq->time_in_state[i]));
1159         }
1160
1161         len += sprintf(buf + len, "Total transition : %u\n",
1162                                         devfreq->total_trans);
1163         return len;
1164 }
1165 static DEVICE_ATTR_RO(trans_stat);
1166
1167 static struct attribute *devfreq_attrs[] = {
1168         &dev_attr_governor.attr,
1169         &dev_attr_available_governors.attr,
1170         &dev_attr_cur_freq.attr,
1171         &dev_attr_available_frequencies.attr,
1172         &dev_attr_target_freq.attr,
1173         &dev_attr_polling_interval.attr,
1174         &dev_attr_min_freq.attr,
1175         &dev_attr_max_freq.attr,
1176         &dev_attr_trans_stat.attr,
1177         NULL,
1178 };
1179 ATTRIBUTE_GROUPS(devfreq);
1180
1181 static int __init devfreq_init(void)
1182 {
1183         devfreq_class = class_create(THIS_MODULE, "devfreq");
1184         if (IS_ERR(devfreq_class)) {
1185                 pr_err("%s: couldn't create class\n", __FILE__);
1186                 return PTR_ERR(devfreq_class);
1187         }
1188
1189         devfreq_wq = create_freezable_workqueue("devfreq_wq");
1190         if (!devfreq_wq) {
1191                 class_destroy(devfreq_class);
1192                 pr_err("%s: couldn't create workqueue\n", __FILE__);
1193                 return -ENOMEM;
1194         }
1195         devfreq_class->dev_groups = devfreq_groups;
1196
1197         return 0;
1198 }
1199 subsys_initcall(devfreq_init);
1200
1201 static void __exit devfreq_exit(void)
1202 {
1203         class_destroy(devfreq_class);
1204         destroy_workqueue(devfreq_wq);
1205 }
1206 module_exit(devfreq_exit);
1207
1208 /*
1209  * The followings are helper functions for devfreq user device drivers with
1210  * OPP framework.
1211  */
1212
1213 /**
1214  * devfreq_recommended_opp() - Helper function to get proper OPP for the
1215  *                           freq value given to target callback.
1216  * @dev:        The devfreq user device. (parent of devfreq)
1217  * @freq:       The frequency given to target function
1218  * @flags:      Flags handed from devfreq framework.
1219  *
1220  * Locking: This function must be called under rcu_read_lock(). opp is a rcu
1221  * protected pointer. The reason for the same is that the opp pointer which is
1222  * returned will remain valid for use with opp_get_{voltage, freq} only while
1223  * under the locked area. The pointer returned must be used prior to unlocking
1224  * with rcu_read_unlock() to maintain the integrity of the pointer.
1225  */
1226 struct dev_pm_opp *devfreq_recommended_opp(struct device *dev,
1227                                            unsigned long *freq,
1228                                            u32 flags)
1229 {
1230         struct dev_pm_opp *opp;
1231
1232         if (flags & DEVFREQ_FLAG_LEAST_UPPER_BOUND) {
1233                 /* The freq is an upper bound. opp should be lower */
1234                 opp = dev_pm_opp_find_freq_floor(dev, freq);
1235
1236                 /* If not available, use the closest opp */
1237                 if (opp == ERR_PTR(-ERANGE))
1238                         opp = dev_pm_opp_find_freq_ceil(dev, freq);
1239         } else {
1240                 /* The freq is an lower bound. opp should be higher */
1241                 opp = dev_pm_opp_find_freq_ceil(dev, freq);
1242
1243                 /* If not available, use the closest opp */
1244                 if (opp == ERR_PTR(-ERANGE))
1245                         opp = dev_pm_opp_find_freq_floor(dev, freq);
1246         }
1247
1248         return opp;
1249 }
1250 EXPORT_SYMBOL(devfreq_recommended_opp);
1251
1252 /**
1253  * devfreq_register_opp_notifier() - Helper function to get devfreq notified
1254  *                                 for any changes in the OPP availability
1255  *                                 changes
1256  * @dev:        The devfreq user device. (parent of devfreq)
1257  * @devfreq:    The devfreq object.
1258  */
1259 int devfreq_register_opp_notifier(struct device *dev, struct devfreq *devfreq)
1260 {
1261         struct srcu_notifier_head *nh;
1262         int ret = 0;
1263
1264         rcu_read_lock();
1265         nh = dev_pm_opp_get_notifier(dev);
1266         if (IS_ERR(nh))
1267                 ret = PTR_ERR(nh);
1268         rcu_read_unlock();
1269         if (!ret)
1270                 ret = srcu_notifier_chain_register(nh, &devfreq->nb);
1271
1272         return ret;
1273 }
1274 EXPORT_SYMBOL(devfreq_register_opp_notifier);
1275
1276 /**
1277  * devfreq_unregister_opp_notifier() - Helper function to stop getting devfreq
1278  *                                   notified for any changes in the OPP
1279  *                                   availability changes anymore.
1280  * @dev:        The devfreq user device. (parent of devfreq)
1281  * @devfreq:    The devfreq object.
1282  *
1283  * At exit() callback of devfreq_dev_profile, this must be included if
1284  * devfreq_recommended_opp is used.
1285  */
1286 int devfreq_unregister_opp_notifier(struct device *dev, struct devfreq *devfreq)
1287 {
1288         struct srcu_notifier_head *nh;
1289         int ret = 0;
1290
1291         rcu_read_lock();
1292         nh = dev_pm_opp_get_notifier(dev);
1293         if (IS_ERR(nh))
1294                 ret = PTR_ERR(nh);
1295         rcu_read_unlock();
1296         if (!ret)
1297                 ret = srcu_notifier_chain_unregister(nh, &devfreq->nb);
1298
1299         return ret;
1300 }
1301 EXPORT_SYMBOL(devfreq_unregister_opp_notifier);
1302
1303 static void devm_devfreq_opp_release(struct device *dev, void *res)
1304 {
1305         devfreq_unregister_opp_notifier(dev, *(struct devfreq **)res);
1306 }
1307
1308 /**
1309  * devm_ devfreq_register_opp_notifier()
1310  *              - Resource-managed devfreq_register_opp_notifier()
1311  * @dev:        The devfreq user device. (parent of devfreq)
1312  * @devfreq:    The devfreq object.
1313  */
1314 int devm_devfreq_register_opp_notifier(struct device *dev,
1315                                        struct devfreq *devfreq)
1316 {
1317         struct devfreq **ptr;
1318         int ret;
1319
1320         ptr = devres_alloc(devm_devfreq_opp_release, sizeof(*ptr), GFP_KERNEL);
1321         if (!ptr)
1322                 return -ENOMEM;
1323
1324         ret = devfreq_register_opp_notifier(dev, devfreq);
1325         if (ret) {
1326                 devres_free(ptr);
1327                 return ret;
1328         }
1329
1330         *ptr = devfreq;
1331         devres_add(dev, ptr);
1332
1333         return 0;
1334 }
1335 EXPORT_SYMBOL(devm_devfreq_register_opp_notifier);
1336
1337 /**
1338  * devm_devfreq_unregister_opp_notifier()
1339  *              - Resource-managed devfreq_unregister_opp_notifier()
1340  * @dev:        The devfreq user device. (parent of devfreq)
1341  * @devfreq:    The devfreq object.
1342  */
1343 void devm_devfreq_unregister_opp_notifier(struct device *dev,
1344                                          struct devfreq *devfreq)
1345 {
1346         WARN_ON(devres_release(dev, devm_devfreq_opp_release,
1347                                devm_devfreq_dev_match, devfreq));
1348 }
1349 EXPORT_SYMBOL(devm_devfreq_unregister_opp_notifier);
1350
1351 /**
1352  * devfreq_register_notifier() - Register a driver with devfreq
1353  * @devfreq:    The devfreq object.
1354  * @nb:         The notifier block to register.
1355  * @list:       DEVFREQ_TRANSITION_NOTIFIER.
1356  */
1357 int devfreq_register_notifier(struct devfreq *devfreq,
1358                                 struct notifier_block *nb,
1359                                 unsigned int list)
1360 {
1361         int ret = 0;
1362
1363         if (!devfreq)
1364                 return -EINVAL;
1365
1366         switch (list) {
1367         case DEVFREQ_TRANSITION_NOTIFIER:
1368                 ret = srcu_notifier_chain_register(
1369                                 &devfreq->transition_notifier_list, nb);
1370                 break;
1371         default:
1372                 ret = -EINVAL;
1373         }
1374
1375         return ret;
1376 }
1377 EXPORT_SYMBOL(devfreq_register_notifier);
1378
1379 /*
1380  * devfreq_unregister_notifier() - Unregister a driver with devfreq
1381  * @devfreq:    The devfreq object.
1382  * @nb:         The notifier block to be unregistered.
1383  * @list:       DEVFREQ_TRANSITION_NOTIFIER.
1384  */
1385 int devfreq_unregister_notifier(struct devfreq *devfreq,
1386                                 struct notifier_block *nb,
1387                                 unsigned int list)
1388 {
1389         int ret = 0;
1390
1391         if (!devfreq)
1392                 return -EINVAL;
1393
1394         switch (list) {
1395         case DEVFREQ_TRANSITION_NOTIFIER:
1396                 ret = srcu_notifier_chain_unregister(
1397                                 &devfreq->transition_notifier_list, nb);
1398                 break;
1399         default:
1400                 ret = -EINVAL;
1401         }
1402
1403         return ret;
1404 }
1405 EXPORT_SYMBOL(devfreq_unregister_notifier);
1406
1407 struct devfreq_notifier_devres {
1408         struct devfreq *devfreq;
1409         struct notifier_block *nb;
1410         unsigned int list;
1411 };
1412
1413 static void devm_devfreq_notifier_release(struct device *dev, void *res)
1414 {
1415         struct devfreq_notifier_devres *this = res;
1416
1417         devfreq_unregister_notifier(this->devfreq, this->nb, this->list);
1418 }
1419
1420 /**
1421  * devm_devfreq_register_notifier()
1422         - Resource-managed devfreq_register_notifier()
1423  * @dev:        The devfreq user device. (parent of devfreq)
1424  * @devfreq:    The devfreq object.
1425  * @nb:         The notifier block to be unregistered.
1426  * @list:       DEVFREQ_TRANSITION_NOTIFIER.
1427  */
1428 int devm_devfreq_register_notifier(struct device *dev,
1429                                 struct devfreq *devfreq,
1430                                 struct notifier_block *nb,
1431                                 unsigned int list)
1432 {
1433         struct devfreq_notifier_devres *ptr;
1434         int ret;
1435
1436         ptr = devres_alloc(devm_devfreq_notifier_release, sizeof(*ptr),
1437                                 GFP_KERNEL);
1438         if (!ptr)
1439                 return -ENOMEM;
1440
1441         ret = devfreq_register_notifier(devfreq, nb, list);
1442         if (ret) {
1443                 devres_free(ptr);
1444                 return ret;
1445         }
1446
1447         ptr->devfreq = devfreq;
1448         ptr->nb = nb;
1449         ptr->list = list;
1450         devres_add(dev, ptr);
1451
1452         return 0;
1453 }
1454 EXPORT_SYMBOL(devm_devfreq_register_notifier);
1455
1456 /**
1457  * devm_devfreq_unregister_notifier()
1458         - Resource-managed devfreq_unregister_notifier()
1459  * @dev:        The devfreq user device. (parent of devfreq)
1460  * @devfreq:    The devfreq object.
1461  * @nb:         The notifier block to be unregistered.
1462  * @list:       DEVFREQ_TRANSITION_NOTIFIER.
1463  */
1464 void devm_devfreq_unregister_notifier(struct device *dev,
1465                                 struct devfreq *devfreq,
1466                                 struct notifier_block *nb,
1467                                 unsigned int list)
1468 {
1469         WARN_ON(devres_release(dev, devm_devfreq_notifier_release,
1470                                devm_devfreq_dev_match, devfreq));
1471 }
1472 EXPORT_SYMBOL(devm_devfreq_unregister_notifier);
1473
1474 MODULE_AUTHOR("MyungJoo Ham <myungjoo.ham@samsung.com>");
1475 MODULE_DESCRIPTION("devfreq class support");
1476 MODULE_LICENSE("GPL");