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->last_status.current_frequency = profile->initial_freq;
 556         devfreq->data = data;
 557         devfreq->nb.notifier_call = devfreq_notifier_call;
 558
 559         if (!devfreq->profile->max_state && !devfreq->profile->freq_table) {
 560                 mutex_unlock(&devfreq->lock);
 561                 devfreq_set_freq_table(devfreq);
 562                 mutex_lock(&devfreq->lock);
 563         }
 564
 565         dev_set_name(&devfreq->dev, "%s", dev_name(dev));
 566         err = device_register(&devfreq->dev);
 567         if (err) {
 568                 mutex_unlock(&devfreq->lock);
 569                 goto err_out;
 570         }
 571
 572         devfreq->trans_table =  devm_kzalloc(&devfreq->dev, sizeof(unsigned int) *
 573                                                 devfreq->profile->max_state *
 574                                                 devfreq->profile->max_state,
 575                                                 GFP_KERNEL);
 576         devfreq->time_in_state = devm_kzalloc(&devfreq->dev, sizeof(unsigned long) *
 577                                                 devfreq->profile->max_state,
 578                                                 GFP_KERNEL);
 579         devfreq->last_stat_updated = jiffies;
 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 err_out:
 607         return ERR_PTR(err);
 608 }
 609 EXPORT_SYMBOL(devfreq_add_device);
 610
 611 /**
 612  * devfreq_remove_device() - Remove devfreq feature from a device.
 613  * @devfreq:    the devfreq instance to be removed
 614  *
 615  * The opposite of devfreq_add_device().
 616  */
 617 int devfreq_remove_device(struct devfreq *devfreq)
 618 {
 619         if (!devfreq)
 620                 return -EINVAL;
 621
 622         device_unregister(&devfreq->dev);
 623
 624         return 0;
 625 }
 626 EXPORT_SYMBOL(devfreq_remove_device);
 627
 628 static int devm_devfreq_dev_match(struct device *dev, void *res, void *data)
 629 {
 630         struct devfreq **r = res;
 631
 632         if (WARN_ON(!r || !*r))
 633                 return 0;
 634
 635         return *r == data;
 636 }
 637
 638 static void devm_devfreq_dev_release(struct device *dev, void *res)
 639 {
 640         devfreq_remove_device(*(struct devfreq **)res);
 641 }
 642
 643 /**
 644  * devm_devfreq_add_device() - Resource-managed devfreq_add_device()
 645  * @dev:        the device to add devfreq feature.
 646  * @profile:    device-specific profile to run devfreq.
 647  * @governor_name:      name of the policy to choose frequency.
 648  * @data:       private data for the governor. The devfreq framework does not
 649  *              touch this value.
 650  *
 651  * This function manages automatically the memory of devfreq device using device
 652  * resource management and simplify the free operation for memory of devfreq
 653  * device.
 654  */
 655 struct devfreq *devm_devfreq_add_device(struct device *dev,
 656                                         struct devfreq_dev_profile *profile,
 657                                         const char *governor_name,
 658                                         void *data)
 659 {
 660         struct devfreq **ptr, *devfreq;
 661
 662         ptr = devres_alloc(devm_devfreq_dev_release, sizeof(*ptr), GFP_KERNEL);
 663         if (!ptr)
 664                 return ERR_PTR(-ENOMEM);
 665
 666         devfreq = devfreq_add_device(dev, profile, governor_name, data);
 667         if (IS_ERR(devfreq)) {
 668                 devres_free(ptr);
 669                 return ERR_PTR(-ENOMEM);
 670         }
 671
 672         *ptr = devfreq;
 673         devres_add(dev, ptr);
 674
 675         return devfreq;
 676 }
 677 EXPORT_SYMBOL(devm_devfreq_add_device);
 678
 679 #ifdef CONFIG_OF
 680 /*
 681  * devfreq_get_devfreq_by_phandle - Get the devfreq device from devicetree
 682  * @dev - instance to the given device
 683  * @index - index into list of devfreq
 684  *
 685  * return the instance of devfreq device
 686  */
 687 struct devfreq *devfreq_get_devfreq_by_phandle(struct device *dev, int index)
 688 {
 689         struct device_node *node;
 690         struct devfreq *devfreq;
 691
 692         if (!dev)
 693                 return ERR_PTR(-EINVAL);
 694
 695         if (!dev->of_node)
 696                 return ERR_PTR(-EINVAL);
 697
 698         node = of_parse_phandle(dev->of_node, "devfreq", index);
 699         if (!node)
 700                 return ERR_PTR(-ENODEV);
 701
 702         mutex_lock(&devfreq_list_lock);
 703         list_for_each_entry(devfreq, &devfreq_list, node) {
 704                 if (devfreq->dev.parent
 705                         && devfreq->dev.parent->of_node == node) {
 706                         mutex_unlock(&devfreq_list_lock);
 707                         return devfreq;
 708                 }
 709         }
 710         mutex_unlock(&devfreq_list_lock);
 711
 712         return ERR_PTR(-EPROBE_DEFER);
 713 }
 714 #else
 715 struct devfreq *devfreq_get_devfreq_by_phandle(struct device *dev, int index)
 716 {
 717         return ERR_PTR(-ENODEV);
 718 }
 719 #endif /* CONFIG_OF */
 720 EXPORT_SYMBOL_GPL(devfreq_get_devfreq_by_phandle);
 721
 722 /**
 723  * devm_devfreq_remove_device() - Resource-managed devfreq_remove_device()
 724  * @dev:        the device to add devfreq feature.
 725  * @devfreq:    the devfreq instance to be removed
 726  */
 727 void devm_devfreq_remove_device(struct device *dev, struct devfreq *devfreq)
 728 {
 729         WARN_ON(devres_release(dev, devm_devfreq_dev_release,
 730                                devm_devfreq_dev_match, devfreq));
 731 }
 732 EXPORT_SYMBOL(devm_devfreq_remove_device);
 733
 734 /**
 735  * devfreq_suspend_device() - Suspend devfreq of a device.
 736  * @devfreq: the devfreq instance to be suspended
 737  *
 738  * This function is intended to be called by the pm callbacks
 739  * (e.g., runtime_suspend, suspend) of the device driver that
 740  * holds the devfreq.
 741  */
 742 int devfreq_suspend_device(struct devfreq *devfreq)
 743 {
 744         if (!devfreq)
 745                 return -EINVAL;
 746
 747         if (!devfreq->governor)
 748                 return 0;
 749
 750         return devfreq->governor->event_handler(devfreq,
 751                                 DEVFREQ_GOV_SUSPEND, NULL);
 752 }
 753 EXPORT_SYMBOL(devfreq_suspend_device);
 754
 755 /**
 756  * devfreq_resume_device() - Resume devfreq of a device.
 757  * @devfreq: the devfreq instance to be resumed
 758  *
 759  * This function is intended to be called by the pm callbacks
 760  * (e.g., runtime_resume, resume) of the device driver that
 761  * holds the devfreq.
 762  */
 763 int devfreq_resume_device(struct devfreq *devfreq)
 764 {
 765         if (!devfreq)
 766                 return -EINVAL;
 767
 768         if (!devfreq->governor)
 769                 return 0;
 770
 771         return devfreq->governor->event_handler(devfreq,
 772                                 DEVFREQ_GOV_RESUME, NULL);
 773 }
 774 EXPORT_SYMBOL(devfreq_resume_device);
 775
 776 /**
 777  * devfreq_add_governor() - Add devfreq governor
 778  * @governor:   the devfreq governor to be added
 779  */
 780 int devfreq_add_governor(struct devfreq_governor *governor)
 781 {
 782         struct devfreq_governor *g;
 783         struct devfreq *devfreq;
 784         int err = 0;
 785
 786         if (!governor) {
 787                 pr_err("%s: Invalid parameters.\n", __func__);
 788                 return -EINVAL;
 789         }
 790
 791         mutex_lock(&devfreq_list_lock);
 792         g = find_devfreq_governor(governor->name);
 793         if (!IS_ERR(g)) {
 794                 pr_err("%s: governor %s already registered\n", __func__,
 795                        g->name);
 796                 err = -EINVAL;
 797                 goto err_out;
 798         }
 799
 800         list_add(&governor->node, &devfreq_governor_list);
 801
 802         list_for_each_entry(devfreq, &devfreq_list, node) {
 803                 int ret = 0;
 804                 struct device *dev = devfreq->dev.parent;
 805
 806                 if (!strncmp(devfreq->governor_name, governor->name,
 807                              DEVFREQ_NAME_LEN)) {
 808                         /* The following should never occur */
 809                         if (devfreq->governor) {
 810                                 dev_warn(dev,
 811                                          "%s: Governor %s already present\n",
 812                                          __func__, devfreq->governor->name);
 813                                 ret = devfreq->governor->event_handler(devfreq,
 814                                                         DEVFREQ_GOV_STOP, NULL);
 815                                 if (ret) {
 816                                         dev_warn(dev,
 817                                                  "%s: Governor %s stop = %d\n",
 818                                                  __func__,
 819                                                  devfreq->governor->name, ret);
 820                                 }
 821                                 /* Fall through */
 822                         }
 823                         devfreq->governor = governor;
 824                         ret = devfreq->governor->event_handler(devfreq,
 825                                                 DEVFREQ_GOV_START, NULL);
 826                         if (ret) {
 827                                 dev_warn(dev, "%s: Governor %s start=%d\n",
 828                                          __func__, devfreq->governor->name,
 829                                          ret);
 830                         }
 831                 }
 832         }
 833
 834 err_out:
 835         mutex_unlock(&devfreq_list_lock);
 836
 837         return err;
 838 }
 839 EXPORT_SYMBOL(devfreq_add_governor);
 840
 841 /**
 842  * devfreq_remove_device() - Remove devfreq feature from a device.
 843  * @governor:   the devfreq governor to be removed
 844  */
 845 int devfreq_remove_governor(struct devfreq_governor *governor)
 846 {
 847         struct devfreq_governor *g;
 848         struct devfreq *devfreq;
 849         int err = 0;
 850
 851         if (!governor) {
 852                 pr_err("%s: Invalid parameters.\n", __func__);
 853                 return -EINVAL;
 854         }
 855
 856         mutex_lock(&devfreq_list_lock);
 857         g = find_devfreq_governor(governor->name);
 858         if (IS_ERR(g)) {
 859                 pr_err("%s: governor %s not registered\n", __func__,
 860                        governor->name);
 861                 err = PTR_ERR(g);
 862                 goto err_out;
 863         }
 864         list_for_each_entry(devfreq, &devfreq_list, node) {
 865                 int ret;
 866                 struct device *dev = devfreq->dev.parent;
 867
 868                 if (!strncmp(devfreq->governor_name, governor->name,
 869                              DEVFREQ_NAME_LEN)) {
 870                         /* we should have a devfreq governor! */
 871                         if (!devfreq->governor) {
 872                                 dev_warn(dev, "%s: Governor %s NOT present\n",
 873                                          __func__, governor->name);
 874                                 continue;
 875                                 /* Fall through */
 876                         }
 877                         ret = devfreq->governor->event_handler(devfreq,
 878                                                 DEVFREQ_GOV_STOP, NULL);
 879                         if (ret) {
 880                                 dev_warn(dev, "%s: Governor %s stop=%d\n",
 881                                          __func__, devfreq->governor->name,
 882                                          ret);
 883                         }
 884                         devfreq->governor = NULL;
 885                 }
 886         }
 887
 888         list_del(&governor->node);
 889 err_out:
 890         mutex_unlock(&devfreq_list_lock);
 891
 892         return err;
 893 }
 894 EXPORT_SYMBOL(devfreq_remove_governor);
 895
 896 static ssize_t governor_show(struct device *dev,
 897                              struct device_attribute *attr, char *buf)
 898 {
 899         if (!to_devfreq(dev)->governor)
 900                 return -EINVAL;
 901
 902         return sprintf(buf, "%s\n", to_devfreq(dev)->governor->name);
 903 }
 904
 905 static ssize_t governor_store(struct device *dev, struct device_attribute *attr,
 906                               const char *buf, size_t count)
 907 {
 908         struct devfreq *df = to_devfreq(dev);
 909         int ret;
 910         char str_governor[DEVFREQ_NAME_LEN + 1];
 911         struct devfreq_governor *governor;
 912
 913         ret = sscanf(buf, "%" __stringify(DEVFREQ_NAME_LEN) "s", str_governor);
 914         if (ret != 1)
 915                 return -EINVAL;
 916
 917         mutex_lock(&devfreq_list_lock);
 918         governor = find_devfreq_governor(str_governor);
 919         if (IS_ERR(governor)) {
 920                 ret = PTR_ERR(governor);
 921                 goto out;
 922         }
 923         if (df->governor == governor) {
 924                 ret = 0;
 925                 goto out;
 926         }
 927
 928         if (df->governor) {
 929                 ret = df->governor->event_handler(df, DEVFREQ_GOV_STOP, NULL);
 930                 if (ret) {
 931                         dev_warn(dev, "%s: Governor %s not stopped(%d)\n",
 932                                  __func__, df->governor->name, ret);
 933                         goto out;
 934                 }
 935         }
 936         df->governor = governor;
 937         strncpy(df->governor_name, governor->name, DEVFREQ_NAME_LEN);
 938         ret = df->governor->event_handler(df, DEVFREQ_GOV_START, NULL);
 939         if (ret)
 940                 dev_warn(dev, "%s: Governor %s not started(%d)\n",
 941                          __func__, df->governor->name, ret);
 942 out:
 943         mutex_unlock(&devfreq_list_lock);
 944
 945         if (!ret)
 946                 ret = count;
 947         return ret;
 948 }
 949 static DEVICE_ATTR_RW(governor);
 950
 951 static ssize_t available_governors_show(struct device *d,
 952                                         struct device_attribute *attr,
 953                                         char *buf)
 954 {
 955         struct devfreq_governor *tmp_governor;
 956         ssize_t count = 0;
 957
 958         mutex_lock(&devfreq_list_lock);
 959         list_for_each_entry(tmp_governor, &devfreq_governor_list, node)
 960                 count += scnprintf(&buf[count], (PAGE_SIZE - count - 2),
 961                                    "%s ", tmp_governor->name);
 962         mutex_unlock(&devfreq_list_lock);
 963
 964         /* Truncate the trailing space */
 965         if (count)
 966                 count--;
 967
 968         count += sprintf(&buf[count], "\n");
 969
 970         return count;
 971 }
 972 static DEVICE_ATTR_RO(available_governors);
 973
 974 static ssize_t cur_freq_show(struct device *dev, struct device_attribute *attr,
 975                              char *buf)
 976 {
 977         unsigned long freq;
 978         struct devfreq *devfreq = to_devfreq(dev);
 979
 980         if (devfreq->profile->get_cur_freq &&
 981                 !devfreq->profile->get_cur_freq(devfreq->dev.parent, &freq))
 982                         return sprintf(buf, "%lu\n", freq);
 983
 984         return sprintf(buf, "%lu\n", devfreq->previous_freq);
 985 }
 986 static DEVICE_ATTR_RO(cur_freq);
 987
 988 static ssize_t target_freq_show(struct device *dev,
 989                                 struct device_attribute *attr, char *buf)
 990 {
 991         return sprintf(buf, "%lu\n", to_devfreq(dev)->previous_freq);
 992 }
 993 static DEVICE_ATTR_RO(target_freq);
 994
 995 static ssize_t polling_interval_show(struct device *dev,
 996                                      struct device_attribute *attr, char *buf)
 997 {
 998         return sprintf(buf, "%d\n", to_devfreq(dev)->profile->polling_ms);
 999 }
1000
1001 static ssize_t polling_interval_store(struct device *dev,
1002                                       struct device_attribute *attr,
1003                                       const char *buf, size_t count)
1004 {
1005         struct devfreq *df = to_devfreq(dev);
1006         unsigned int value;
1007         int ret;
1008
1009         if (!df->governor)
1010                 return -EINVAL;
1011
1012         ret = sscanf(buf, "%u", &value);
1013         if (ret != 1)
1014                 return -EINVAL;
1015
1016         df->governor->event_handler(df, DEVFREQ_GOV_INTERVAL, &value);
1017         ret = count;
1018
1019         return ret;
1020 }
1021 static DEVICE_ATTR_RW(polling_interval);
1022
1023 static ssize_t min_freq_store(struct device *dev, struct device_attribute *attr,
1024                               const char *buf, size_t count)
1025 {
1026         struct devfreq *df = to_devfreq(dev);
1027         unsigned long value;
1028         int ret;
1029         unsigned long max;
1030
1031         ret = sscanf(buf, "%lu", &value);
1032         if (ret != 1)
1033                 return -EINVAL;
1034
1035         mutex_lock(&df->lock);
1036         max = df->max_freq;
1037         if (value && max && value > max) {
1038                 ret = -EINVAL;
1039                 goto unlock;
1040         }
1041
1042         df->min_freq = value;
1043         update_devfreq(df);
1044         ret = count;
1045 unlock:
1046         mutex_unlock(&df->lock);
1047         return ret;
1048 }
1049
1050 static ssize_t max_freq_store(struct device *dev, struct device_attribute *attr,
1051                               const char *buf, size_t count)
1052 {
1053         struct devfreq *df = to_devfreq(dev);
1054         unsigned long value;
1055         int ret;
1056         unsigned long min;
1057
1058         ret = sscanf(buf, "%lu", &value);
1059         if (ret != 1)
1060                 return -EINVAL;
1061
1062         mutex_lock(&df->lock);
1063         min = df->min_freq;
1064         if (value && min && value < min) {
1065                 ret = -EINVAL;
1066                 goto unlock;
1067         }
1068
1069         df->max_freq = value;
1070         update_devfreq(df);
1071         ret = count;
1072 unlock:
1073         mutex_unlock(&df->lock);
1074         return ret;
1075 }
1076
1077 #define show_one(name)                                          \
1078 static ssize_t name##_show                                      \
1079 (struct device *dev, struct device_attribute *attr, char *buf)  \
1080 {                                                               \
1081         return sprintf(buf, "%lu\n", to_devfreq(dev)->name);    \
1082 }
1083 show_one(min_freq);
1084 show_one(max_freq);
1085
1086 static DEVICE_ATTR_RW(min_freq);
1087 static DEVICE_ATTR_RW(max_freq);
1088
1089 static ssize_t available_frequencies_show(struct device *d,
1090                                           struct device_attribute *attr,
1091                                           char *buf)
1092 {
1093         struct devfreq *df = to_devfreq(d);
1094         struct device *dev = df->dev.parent;
1095         struct dev_pm_opp *opp;
1096         ssize_t count = 0;
1097         unsigned long freq = 0;
1098
1099         rcu_read_lock();
1100         do {
1101                 opp = dev_pm_opp_find_freq_ceil(dev, &freq);
1102                 if (IS_ERR(opp))
1103                         break;
1104
1105                 count += scnprintf(&buf[count], (PAGE_SIZE - count - 2),
1106                                    "%lu ", freq);
1107                 freq++;
1108         } while (1);
1109         rcu_read_unlock();
1110
1111         /* Truncate the trailing space */
1112         if (count)
1113                 count--;
1114
1115         count += sprintf(&buf[count], "\n");
1116
1117         return count;
1118 }
1119 static DEVICE_ATTR_RO(available_frequencies);
1120
1121 static ssize_t trans_stat_show(struct device *dev,
1122                                struct device_attribute *attr, char *buf)
1123 {
1124         struct devfreq *devfreq = to_devfreq(dev);
1125         ssize_t len;
1126         int i, j;
1127         unsigned int max_state = devfreq->profile->max_state;
1128
1129         if (!devfreq->stop_polling &&
1130                         devfreq_update_status(devfreq, devfreq->previous_freq))
1131                 return 0;
1132         if (max_state == 0)
1133                 return sprintf(buf, "Not Supported.\n");
1134
1135         len = sprintf(buf, "     From  :   To\n");
1136         len += sprintf(buf + len, "           :");
1137         for (i = 0; i < max_state; i++)
1138                 len += sprintf(buf + len, "%10lu",
1139                                 devfreq->profile->freq_table[i]);
1140
1141         len += sprintf(buf + len, "   time(ms)\n");
1142
1143         for (i = 0; i < max_state; i++) {
1144                 if (devfreq->profile->freq_table[i]
1145                                         == devfreq->previous_freq) {
1146                         len += sprintf(buf + len, "*");
1147                 } else {
1148                         len += sprintf(buf + len, " ");
1149                 }
1150                 len += sprintf(buf + len, "%10lu:",
1151                                 devfreq->profile->freq_table[i]);
1152                 for (j = 0; j < max_state; j++)
1153                         len += sprintf(buf + len, "%10u",
1154                                 devfreq->trans_table[(i * max_state) + j]);
1155                 len += sprintf(buf + len, "%10u\n",
1156                         jiffies_to_msecs(devfreq->time_in_state[i]));
1157         }
1158
1159         len += sprintf(buf + len, "Total transition : %u\n",
1160                                         devfreq->total_trans);
1161         return len;
1162 }
1163 static DEVICE_ATTR_RO(trans_stat);
1164
1165 static struct attribute *devfreq_attrs[] = {
1166         &dev_attr_governor.attr,
1167         &dev_attr_available_governors.attr,
1168         &dev_attr_cur_freq.attr,
1169         &dev_attr_available_frequencies.attr,
1170         &dev_attr_target_freq.attr,
1171         &dev_attr_polling_interval.attr,
1172         &dev_attr_min_freq.attr,
1173         &dev_attr_max_freq.attr,
1174         &dev_attr_trans_stat.attr,
1175         NULL,
1176 };
1177 ATTRIBUTE_GROUPS(devfreq);
1178
1179 static int __init devfreq_init(void)
1180 {
1181         devfreq_class = class_create(THIS_MODULE, "devfreq");
1182         if (IS_ERR(devfreq_class)) {
1183                 pr_err("%s: couldn't create class\n", __FILE__);
1184                 return PTR_ERR(devfreq_class);
1185         }
1186
1187         devfreq_wq = create_freezable_workqueue("devfreq_wq");
1188         if (!devfreq_wq) {
1189                 class_destroy(devfreq_class);
1190                 pr_err("%s: couldn't create workqueue\n", __FILE__);
1191                 return -ENOMEM;
1192         }
1193         devfreq_class->dev_groups = devfreq_groups;
1194
1195         return 0;
1196 }
1197 subsys_initcall(devfreq_init);
1198
1199 static void __exit devfreq_exit(void)
1200 {
1201         class_destroy(devfreq_class);
1202         destroy_workqueue(devfreq_wq);
1203 }
1204 module_exit(devfreq_exit);
1205
1206 /*
1207  * The followings are helper functions for devfreq user device drivers with
1208  * OPP framework.
1209  */
1210
1211 /**
1212  * devfreq_recommended_opp() - Helper function to get proper OPP for the
1213  *                           freq value given to target callback.
1214  * @dev:        The devfreq user device. (parent of devfreq)
1215  * @freq:       The frequency given to target function
1216  * @flags:      Flags handed from devfreq framework.
1217  *
1218  * Locking: This function must be called under rcu_read_lock(). opp is a rcu
1219  * protected pointer. The reason for the same is that the opp pointer which is
1220  * returned will remain valid for use with opp_get_{voltage, freq} only while
1221  * under the locked area. The pointer returned must be used prior to unlocking
1222  * with rcu_read_unlock() to maintain the integrity of the pointer.
1223  */
1224 struct dev_pm_opp *devfreq_recommended_opp(struct device *dev,
1225                                            unsigned long *freq,
1226                                            u32 flags)
1227 {
1228         struct dev_pm_opp *opp;
1229
1230         if (flags & DEVFREQ_FLAG_LEAST_UPPER_BOUND) {
1231                 /* The freq is an upper bound. opp should be lower */
1232                 opp = dev_pm_opp_find_freq_floor(dev, freq);
1233
1234                 /* If not available, use the closest opp */
1235                 if (opp == ERR_PTR(-ERANGE))
1236                         opp = dev_pm_opp_find_freq_ceil(dev, freq);
1237         } else {
1238                 /* The freq is an lower bound. opp should be higher */
1239                 opp = dev_pm_opp_find_freq_ceil(dev, freq);
1240
1241                 /* If not available, use the closest opp */
1242                 if (opp == ERR_PTR(-ERANGE))
1243                         opp = dev_pm_opp_find_freq_floor(dev, freq);
1244         }
1245
1246         return opp;
1247 }
1248 EXPORT_SYMBOL(devfreq_recommended_opp);
1249
1250 /**
1251  * devfreq_register_opp_notifier() - Helper function to get devfreq notified
1252  *                                 for any changes in the OPP availability
1253  *                                 changes
1254  * @dev:        The devfreq user device. (parent of devfreq)
1255  * @devfreq:    The devfreq object.
1256  */
1257 int devfreq_register_opp_notifier(struct device *dev, struct devfreq *devfreq)
1258 {
1259         struct srcu_notifier_head *nh;
1260         int ret = 0;
1261
1262         rcu_read_lock();
1263         nh = dev_pm_opp_get_notifier(dev);
1264         if (IS_ERR(nh))
1265                 ret = PTR_ERR(nh);
1266         rcu_read_unlock();
1267         if (!ret)
1268                 ret = srcu_notifier_chain_register(nh, &devfreq->nb);
1269
1270         return ret;
1271 }
1272 EXPORT_SYMBOL(devfreq_register_opp_notifier);
1273
1274 /**
1275  * devfreq_unregister_opp_notifier() - Helper function to stop getting devfreq
1276  *                                   notified for any changes in the OPP
1277  *                                   availability changes anymore.
1278  * @dev:        The devfreq user device. (parent of devfreq)
1279  * @devfreq:    The devfreq object.
1280  *
1281  * At exit() callback of devfreq_dev_profile, this must be included if
1282  * devfreq_recommended_opp is used.
1283  */
1284 int devfreq_unregister_opp_notifier(struct device *dev, struct devfreq *devfreq)
1285 {
1286         struct srcu_notifier_head *nh;
1287         int ret = 0;
1288
1289         rcu_read_lock();
1290         nh = dev_pm_opp_get_notifier(dev);
1291         if (IS_ERR(nh))
1292                 ret = PTR_ERR(nh);
1293         rcu_read_unlock();
1294         if (!ret)
1295                 ret = srcu_notifier_chain_unregister(nh, &devfreq->nb);
1296
1297         return ret;
1298 }
1299 EXPORT_SYMBOL(devfreq_unregister_opp_notifier);
1300
1301 static void devm_devfreq_opp_release(struct device *dev, void *res)
1302 {
1303         devfreq_unregister_opp_notifier(dev, *(struct devfreq **)res);
1304 }
1305
1306 /**
1307  * devm_ devfreq_register_opp_notifier()
1308  *              - Resource-managed devfreq_register_opp_notifier()
1309  * @dev:        The devfreq user device. (parent of devfreq)
1310  * @devfreq:    The devfreq object.
1311  */
1312 int devm_devfreq_register_opp_notifier(struct device *dev,
1313                                        struct devfreq *devfreq)
1314 {
1315         struct devfreq **ptr;
1316         int ret;
1317
1318         ptr = devres_alloc(devm_devfreq_opp_release, sizeof(*ptr), GFP_KERNEL);
1319         if (!ptr)
1320                 return -ENOMEM;
1321
1322         ret = devfreq_register_opp_notifier(dev, devfreq);
1323         if (ret) {
1324                 devres_free(ptr);
1325                 return ret;
1326         }
1327
1328         *ptr = devfreq;
1329         devres_add(dev, ptr);
1330
1331         return 0;
1332 }
1333 EXPORT_SYMBOL(devm_devfreq_register_opp_notifier);
1334
1335 /**
1336  * devm_devfreq_unregister_opp_notifier()
1337  *              - Resource-managed devfreq_unregister_opp_notifier()
1338  * @dev:        The devfreq user device. (parent of devfreq)
1339  * @devfreq:    The devfreq object.
1340  */
1341 void devm_devfreq_unregister_opp_notifier(struct device *dev,
1342                                          struct devfreq *devfreq)
1343 {
1344         WARN_ON(devres_release(dev, devm_devfreq_opp_release,
1345                                devm_devfreq_dev_match, devfreq));
1346 }
1347 EXPORT_SYMBOL(devm_devfreq_unregister_opp_notifier);
1348
1349 /**
1350  * devfreq_register_notifier() - Register a driver with devfreq
1351  * @devfreq:    The devfreq object.
1352  * @nb:         The notifier block to register.
1353  * @list:       DEVFREQ_TRANSITION_NOTIFIER.
1354  */
1355 int devfreq_register_notifier(struct devfreq *devfreq,
1356                                 struct notifier_block *nb,
1357                                 unsigned int list)
1358 {
1359         int ret = 0;
1360
1361         if (!devfreq)
1362                 return -EINVAL;
1363
1364         switch (list) {
1365         case DEVFREQ_TRANSITION_NOTIFIER:
1366                 ret = srcu_notifier_chain_register(
1367                                 &devfreq->transition_notifier_list, nb);
1368                 break;
1369         default:
1370                 ret = -EINVAL;
1371         }
1372
1373         return ret;
1374 }
1375 EXPORT_SYMBOL(devfreq_register_notifier);
1376
1377 /*
1378  * devfreq_unregister_notifier() - Unregister a driver with devfreq
1379  * @devfreq:    The devfreq object.
1380  * @nb:         The notifier block to be unregistered.
1381  * @list:       DEVFREQ_TRANSITION_NOTIFIER.
1382  */
1383 int devfreq_unregister_notifier(struct devfreq *devfreq,
1384                                 struct notifier_block *nb,
1385                                 unsigned int list)
1386 {
1387         int ret = 0;
1388
1389         if (!devfreq)
1390                 return -EINVAL;
1391
1392         switch (list) {
1393         case DEVFREQ_TRANSITION_NOTIFIER:
1394                 ret = srcu_notifier_chain_unregister(
1395                                 &devfreq->transition_notifier_list, nb);
1396                 break;
1397         default:
1398                 ret = -EINVAL;
1399         }
1400
1401         return ret;
1402 }
1403 EXPORT_SYMBOL(devfreq_unregister_notifier);
1404
1405 struct devfreq_notifier_devres {
1406         struct devfreq *devfreq;
1407         struct notifier_block *nb;
1408         unsigned int list;
1409 };
1410
1411 static void devm_devfreq_notifier_release(struct device *dev, void *res)
1412 {
1413         struct devfreq_notifier_devres *this = res;
1414
1415         devfreq_unregister_notifier(this->devfreq, this->nb, this->list);
1416 }
1417
1418 /**
1419  * devm_devfreq_register_notifier()
1420         - Resource-managed devfreq_register_notifier()
1421  * @dev:        The devfreq user device. (parent of devfreq)
1422  * @devfreq:    The devfreq object.
1423  * @nb:         The notifier block to be unregistered.
1424  * @list:       DEVFREQ_TRANSITION_NOTIFIER.
1425  */
1426 int devm_devfreq_register_notifier(struct device *dev,
1427                                 struct devfreq *devfreq,
1428                                 struct notifier_block *nb,
1429                                 unsigned int list)
1430 {
1431         struct devfreq_notifier_devres *ptr;
1432         int ret;
1433
1434         ptr = devres_alloc(devm_devfreq_notifier_release, sizeof(*ptr),
1435                                 GFP_KERNEL);
1436         if (!ptr)
1437                 return -ENOMEM;
1438
1439         ret = devfreq_register_notifier(devfreq, nb, list);
1440         if (ret) {
1441                 devres_free(ptr);
1442                 return ret;
1443         }
1444
1445         ptr->devfreq = devfreq;
1446         ptr->nb = nb;
1447         ptr->list = list;
1448         devres_add(dev, ptr);
1449
1450         return 0;
1451 }
1452 EXPORT_SYMBOL(devm_devfreq_register_notifier);
1453
1454 /**
1455  * devm_devfreq_unregister_notifier()
1456         - Resource-managed devfreq_unregister_notifier()
1457  * @dev:        The devfreq user device. (parent of devfreq)
1458  * @devfreq:    The devfreq object.
1459  * @nb:         The notifier block to be unregistered.
1460  * @list:       DEVFREQ_TRANSITION_NOTIFIER.
1461  */
1462 void devm_devfreq_unregister_notifier(struct device *dev,
1463                                 struct devfreq *devfreq,
1464                                 struct notifier_block *nb,
1465                                 unsigned int list)
1466 {
1467         WARN_ON(devres_release(dev, devm_devfreq_notifier_release,
1468                                devm_devfreq_dev_match, devfreq));
1469 }
1470 EXPORT_SYMBOL(devm_devfreq_unregister_notifier);
1471
1472 MODULE_AUTHOR("MyungJoo Ham <myungjoo.ham@samsung.com>");
1473 MODULE_DESCRIPTION("devfreq class support");
1474 MODULE_LICENSE("GPL");