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                 freqs.new = cur_freq;
 273                 devfreq_notify_transition(devfreq, &freqs, DEVFREQ_POSTCHANGE);
 274                 return err;
 275         }
 276
 277         freqs.new = freq;
 278         devfreq_notify_transition(devfreq, &freqs, DEVFREQ_POSTCHANGE);
 279
 280         if (devfreq->profile->freq_table)
 281                 if (devfreq_update_status(devfreq, freq))
 282                         dev_err(&devfreq->dev,
 283                                 "Couldn't update frequency transition information.\n");
 284
 285         devfreq->previous_freq = freq;
 286         return err;
 287 }
 288 EXPORT_SYMBOL(update_devfreq);
 289
 290 /**
 291  * devfreq_monitor() - Periodically poll devfreq objects.
 292  * @work:       the work struct used to run devfreq_monitor periodically.
 293  *
 294  */
 295 static void devfreq_monitor(struct work_struct *work)
 296 {
 297         int err;
 298         struct devfreq *devfreq = container_of(work,
 299                                         struct devfreq, work.work);
 300
 301         mutex_lock(&devfreq->lock);
 302         err = update_devfreq(devfreq);
 303         if (err)
 304                 dev_err(&devfreq->dev, "dvfs failed with (%d) error\n", err);
 305
 306         queue_delayed_work(devfreq_wq, &devfreq->work,
 307                                 msecs_to_jiffies(devfreq->profile->polling_ms));
 308         mutex_unlock(&devfreq->lock);
 309 }
 310
 311 /**
 312  * devfreq_monitor_start() - Start load monitoring of devfreq instance
 313  * @devfreq:    the devfreq instance.
 314  *
 315  * Helper function for starting devfreq device load monitoing. By
 316  * default delayed work based monitoring is supported. Function
 317  * to be called from governor in response to DEVFREQ_GOV_START
 318  * event when device is added to devfreq framework.
 319  */
 320 void devfreq_monitor_start(struct devfreq *devfreq)
 321 {
 322         INIT_DEFERRABLE_WORK(&devfreq->work, devfreq_monitor);
 323         if (devfreq->profile->polling_ms)
 324                 queue_delayed_work(devfreq_wq, &devfreq->work,
 325                         msecs_to_jiffies(devfreq->profile->polling_ms));
 326 }
 327 EXPORT_SYMBOL(devfreq_monitor_start);
 328
 329 /**
 330  * devfreq_monitor_stop() - Stop load monitoring of a devfreq instance
 331  * @devfreq:    the devfreq instance.
 332  *
 333  * Helper function to stop devfreq device load monitoing. Function
 334  * to be called from governor in response to DEVFREQ_GOV_STOP
 335  * event when device is removed from devfreq framework.
 336  */
 337 void devfreq_monitor_stop(struct devfreq *devfreq)
 338 {
 339         cancel_delayed_work_sync(&devfreq->work);
 340 }
 341 EXPORT_SYMBOL(devfreq_monitor_stop);
 342
 343 /**
 344  * devfreq_monitor_suspend() - Suspend load monitoring of a devfreq instance
 345  * @devfreq:    the devfreq instance.
 346  *
 347  * Helper function to suspend devfreq device load monitoing. Function
 348  * to be called from governor in response to DEVFREQ_GOV_SUSPEND
 349  * event or when polling interval is set to zero.
 350  *
 351  * Note: Though this function is same as devfreq_monitor_stop(),
 352  * intentionally kept separate to provide hooks for collecting
 353  * transition statistics.
 354  */
 355 void devfreq_monitor_suspend(struct devfreq *devfreq)
 356 {
 357         mutex_lock(&devfreq->lock);
 358         if (devfreq->stop_polling) {
 359                 mutex_unlock(&devfreq->lock);
 360                 return;
 361         }
 362
 363         devfreq_update_status(devfreq, devfreq->previous_freq);
 364         devfreq->stop_polling = true;
 365         mutex_unlock(&devfreq->lock);
 366         cancel_delayed_work_sync(&devfreq->work);
 367 }
 368 EXPORT_SYMBOL(devfreq_monitor_suspend);
 369
 370 /**
 371  * devfreq_monitor_resume() - Resume load monitoring of a devfreq instance
 372  * @devfreq:    the devfreq instance.
 373  *
 374  * Helper function to resume devfreq device load monitoing. Function
 375  * to be called from governor in response to DEVFREQ_GOV_RESUME
 376  * event or when polling interval is set to non-zero.
 377  */
 378 void devfreq_monitor_resume(struct devfreq *devfreq)
 379 {
 380         unsigned long freq;
 381
 382         mutex_lock(&devfreq->lock);
 383         if (!devfreq->stop_polling)
 384                 goto out;
 385
 386         if (!delayed_work_pending(&devfreq->work) &&
 387                         devfreq->profile->polling_ms)
 388                 queue_delayed_work(devfreq_wq, &devfreq->work,
 389                         msecs_to_jiffies(devfreq->profile->polling_ms));
 390
 391         devfreq->last_stat_updated = jiffies;
 392         devfreq->stop_polling = false;
 393
 394         if (devfreq->profile->get_cur_freq &&
 395                 !devfreq->profile->get_cur_freq(devfreq->dev.parent, &freq))
 396                 devfreq->previous_freq = freq;
 397
 398 out:
 399         mutex_unlock(&devfreq->lock);
 400 }
 401 EXPORT_SYMBOL(devfreq_monitor_resume);
 402
 403 /**
 404  * devfreq_interval_update() - Update device devfreq monitoring interval
 405  * @devfreq:    the devfreq instance.
 406  * @delay:      new polling interval to be set.
 407  *
 408  * Helper function to set new load monitoring polling interval. Function
 409  * to be called from governor in response to DEVFREQ_GOV_INTERVAL event.
 410  */
 411 void devfreq_interval_update(struct devfreq *devfreq, unsigned int *delay)
 412 {
 413         unsigned int cur_delay = devfreq->profile->polling_ms;
 414         unsigned int new_delay = *delay;
 415
 416         mutex_lock(&devfreq->lock);
 417         devfreq->profile->polling_ms = new_delay;
 418
 419         if (devfreq->stop_polling)
 420                 goto out;
 421
 422         /* if new delay is zero, stop polling */
 423         if (!new_delay) {
 424                 mutex_unlock(&devfreq->lock);
 425                 cancel_delayed_work_sync(&devfreq->work);
 426                 return;
 427         }
 428
 429         /* if current delay is zero, start polling with new delay */
 430         if (!cur_delay) {
 431                 queue_delayed_work(devfreq_wq, &devfreq->work,
 432                         msecs_to_jiffies(devfreq->profile->polling_ms));
 433                 goto out;
 434         }
 435
 436         /* if current delay is greater than new delay, restart polling */
 437         if (cur_delay > new_delay) {
 438                 mutex_unlock(&devfreq->lock);
 439                 cancel_delayed_work_sync(&devfreq->work);
 440                 mutex_lock(&devfreq->lock);
 441                 if (!devfreq->stop_polling)
 442                         queue_delayed_work(devfreq_wq, &devfreq->work,
 443                               msecs_to_jiffies(devfreq->profile->polling_ms));
 444         }
 445 out:
 446         mutex_unlock(&devfreq->lock);
 447 }
 448 EXPORT_SYMBOL(devfreq_interval_update);
 449
 450 /**
 451  * devfreq_notifier_call() - Notify that the device frequency requirements
 452  *                         has been changed out of devfreq framework.
 453  * @nb:         the notifier_block (supposed to be devfreq->nb)
 454  * @type:       not used
 455  * @devp:       not used
 456  *
 457  * Called by a notifier that uses devfreq->nb.
 458  */
 459 static int devfreq_notifier_call(struct notifier_block *nb, unsigned long type,
 460                                  void *devp)
 461 {
 462         struct devfreq *devfreq = container_of(nb, struct devfreq, nb);
 463         int ret;
 464
 465         mutex_lock(&devfreq->lock);
 466         ret = update_devfreq(devfreq);
 467         mutex_unlock(&devfreq->lock);
 468
 469         return ret;
 470 }
 471
 472 /**
 473  * _remove_devfreq() - Remove devfreq from the list and release its resources.
 474  * @devfreq:    the devfreq struct
 475  */
 476 static void _remove_devfreq(struct devfreq *devfreq)
 477 {
 478         mutex_lock(&devfreq_list_lock);
 479         if (IS_ERR(find_device_devfreq(devfreq->dev.parent))) {
 480                 mutex_unlock(&devfreq_list_lock);
 481                 dev_warn(&devfreq->dev, "releasing devfreq which doesn't exist\n");
 482                 return;
 483         }
 484         list_del(&devfreq->node);
 485         mutex_unlock(&devfreq_list_lock);
 486
 487         if (devfreq->governor)
 488                 devfreq->governor->event_handler(devfreq,
 489                                                  DEVFREQ_GOV_STOP, NULL);
 490
 491         if (devfreq->profile->exit)
 492                 devfreq->profile->exit(devfreq->dev.parent);
 493
 494         mutex_destroy(&devfreq->lock);
 495         kfree(devfreq);
 496 }
 497
 498 /**
 499  * devfreq_dev_release() - Callback for struct device to release the device.
 500  * @dev:        the devfreq device
 501  *
 502  * This calls _remove_devfreq() if _remove_devfreq() is not called.
 503  */
 504 static void devfreq_dev_release(struct device *dev)
 505 {
 506         struct devfreq *devfreq = to_devfreq(dev);
 507
 508         _remove_devfreq(devfreq);
 509 }
 510
 511 /**
 512  * devfreq_add_device() - Add devfreq feature to the device
 513  * @dev:        the device to add devfreq feature.
 514  * @profile:    device-specific profile to run devfreq.
 515  * @governor_name:      name of the policy to choose frequency.
 516  * @data:       private data for the governor. The devfreq framework does not
 517  *              touch this value.
 518  */
 519 struct devfreq *devfreq_add_device(struct device *dev,
 520                                    struct devfreq_dev_profile *profile,
 521                                    const char *governor_name,
 522                                    void *data)
 523 {
 524         struct devfreq *devfreq;
 525         struct devfreq_governor *governor;
 526         int err = 0;
 527
 528         if (!dev || !profile || !governor_name) {
 529                 dev_err(dev, "%s: Invalid parameters.\n", __func__);
 530                 return ERR_PTR(-EINVAL);
 531         }
 532
 533         mutex_lock(&devfreq_list_lock);
 534         devfreq = find_device_devfreq(dev);
 535         mutex_unlock(&devfreq_list_lock);
 536         if (!IS_ERR(devfreq)) {
 537                 dev_err(dev, "%s: Unable to create devfreq for the device. It already has one.\n", __func__);
 538                 err = -EINVAL;
 539                 goto err_out;
 540         }
 541
 542         devfreq = kzalloc(sizeof(struct devfreq), GFP_KERNEL);
 543         if (!devfreq) {
 544                 dev_err(dev, "%s: Unable to create devfreq for the device\n",
 545                         __func__);
 546                 err = -ENOMEM;
 547                 goto err_out;
 548         }
 549
 550         mutex_init(&devfreq->lock);
 551         mutex_lock(&devfreq->lock);
 552         devfreq->dev.parent = dev;
 553         devfreq->dev.class = devfreq_class;
 554         devfreq->dev.release = devfreq_dev_release;
 555         devfreq->profile = profile;
 556         strncpy(devfreq->governor_name, governor_name, DEVFREQ_NAME_LEN);
 557         devfreq->previous_freq = profile->initial_freq;
 558         devfreq->last_status.current_frequency = profile->initial_freq;
 559         devfreq->data = data;
 560         devfreq->nb.notifier_call = devfreq_notifier_call;
 561
 562         if (!devfreq->profile->max_state && !devfreq->profile->freq_table) {
 563                 mutex_unlock(&devfreq->lock);
 564                 devfreq_set_freq_table(devfreq);
 565                 mutex_lock(&devfreq->lock);
 566         }
 567
 568         dev_set_name(&devfreq->dev, "%s", dev_name(dev));
 569         err = device_register(&devfreq->dev);
 570         if (err) {
 571                 mutex_unlock(&devfreq->lock);
 572                 goto err_out;
 573         }
 574
 575         devfreq->trans_table =  devm_kzalloc(&devfreq->dev, sizeof(unsigned int) *
 576                                                 devfreq->profile->max_state *
 577                                                 devfreq->profile->max_state,
 578                                                 GFP_KERNEL);
 579         devfreq->time_in_state = devm_kzalloc(&devfreq->dev, sizeof(unsigned long) *
 580                                                 devfreq->profile->max_state,
 581                                                 GFP_KERNEL);
 582         devfreq->last_stat_updated = jiffies;
 583
 584         srcu_init_notifier_head(&devfreq->transition_notifier_list);
 585
 586         mutex_unlock(&devfreq->lock);
 587
 588         mutex_lock(&devfreq_list_lock);
 589         list_add(&devfreq->node, &devfreq_list);
 590
 591         governor = find_devfreq_governor(devfreq->governor_name);
 592         if (!IS_ERR(governor))
 593                 devfreq->governor = governor;
 594         if (devfreq->governor)
 595                 err = devfreq->governor->event_handler(devfreq,
 596                                         DEVFREQ_GOV_START, NULL);
 597         mutex_unlock(&devfreq_list_lock);
 598         if (err) {
 599                 dev_err(dev, "%s: Unable to start governor for the device\n",
 600                         __func__);
 601                 goto err_init;
 602         }
 603
 604         return devfreq;
 605
 606 err_init:
 607         list_del(&devfreq->node);
 608         device_unregister(&devfreq->dev);
 609 err_out:
 610         return ERR_PTR(err);
 611 }
 612 EXPORT_SYMBOL(devfreq_add_device);
 613
 614 /**
 615  * devfreq_remove_device() - Remove devfreq feature from a device.
 616  * @devfreq:    the devfreq instance to be removed
 617  *
 618  * The opposite of devfreq_add_device().
 619  */
 620 int devfreq_remove_device(struct devfreq *devfreq)
 621 {
 622         if (!devfreq)
 623                 return -EINVAL;
 624
 625         device_unregister(&devfreq->dev);
 626
 627         return 0;
 628 }
 629 EXPORT_SYMBOL(devfreq_remove_device);
 630
 631 static int devm_devfreq_dev_match(struct device *dev, void *res, void *data)
 632 {
 633         struct devfreq **r = res;
 634
 635         if (WARN_ON(!r || !*r))
 636                 return 0;
 637
 638         return *r == data;
 639 }
 640
 641 static void devm_devfreq_dev_release(struct device *dev, void *res)
 642 {
 643         devfreq_remove_device(*(struct devfreq **)res);
 644 }
 645
 646 /**
 647  * devm_devfreq_add_device() - Resource-managed devfreq_add_device()
 648  * @dev:        the device to add devfreq feature.
 649  * @profile:    device-specific profile to run devfreq.
 650  * @governor_name:      name of the policy to choose frequency.
 651  * @data:       private data for the governor. The devfreq framework does not
 652  *              touch this value.
 653  *
 654  * This function manages automatically the memory of devfreq device using device
 655  * resource management and simplify the free operation for memory of devfreq
 656  * device.
 657  */
 658 struct devfreq *devm_devfreq_add_device(struct device *dev,
 659                                         struct devfreq_dev_profile *profile,
 660                                         const char *governor_name,
 661                                         void *data)
 662 {
 663         struct devfreq **ptr, *devfreq;
 664
 665         ptr = devres_alloc(devm_devfreq_dev_release, sizeof(*ptr), GFP_KERNEL);
 666         if (!ptr)
 667                 return ERR_PTR(-ENOMEM);
 668
 669         devfreq = devfreq_add_device(dev, profile, governor_name, data);
 670         if (IS_ERR(devfreq)) {
 671                 devres_free(ptr);
 672                 return ERR_PTR(-ENOMEM);
 673         }
 674
 675         *ptr = devfreq;
 676         devres_add(dev, ptr);
 677
 678         return devfreq;
 679 }
 680 EXPORT_SYMBOL(devm_devfreq_add_device);
 681
 682 #ifdef CONFIG_OF
 683 /*
 684  * devfreq_get_devfreq_by_phandle - Get the devfreq device from devicetree
 685  * @dev - instance to the given device
 686  * @index - index into list of devfreq
 687  *
 688  * return the instance of devfreq device
 689  */
 690 struct devfreq *devfreq_get_devfreq_by_phandle(struct device *dev, int index)
 691 {
 692         struct device_node *node;
 693         struct devfreq *devfreq;
 694
 695         if (!dev)
 696                 return ERR_PTR(-EINVAL);
 697
 698         if (!dev->of_node)
 699                 return ERR_PTR(-EINVAL);
 700
 701         node = of_parse_phandle(dev->of_node, "devfreq", index);
 702         if (!node)
 703                 return ERR_PTR(-ENODEV);
 704
 705         mutex_lock(&devfreq_list_lock);
 706         list_for_each_entry(devfreq, &devfreq_list, node) {
 707                 if (devfreq->dev.parent
 708                         && devfreq->dev.parent->of_node == node) {
 709                         mutex_unlock(&devfreq_list_lock);
 710                         return devfreq;
 711                 }
 712         }
 713         mutex_unlock(&devfreq_list_lock);
 714
 715         return ERR_PTR(-EPROBE_DEFER);
 716 }
 717 #else
 718 struct devfreq *devfreq_get_devfreq_by_phandle(struct device *dev, int index)
 719 {
 720         return ERR_PTR(-ENODEV);
 721 }
 722 #endif /* CONFIG_OF */
 723 EXPORT_SYMBOL_GPL(devfreq_get_devfreq_by_phandle);
 724
 725 /**
 726  * devm_devfreq_remove_device() - Resource-managed devfreq_remove_device()
 727  * @dev:        the device to add devfreq feature.
 728  * @devfreq:    the devfreq instance to be removed
 729  */
 730 void devm_devfreq_remove_device(struct device *dev, struct devfreq *devfreq)
 731 {
 732         WARN_ON(devres_release(dev, devm_devfreq_dev_release,
 733                                devm_devfreq_dev_match, devfreq));
 734 }
 735 EXPORT_SYMBOL(devm_devfreq_remove_device);
 736
 737 /**
 738  * devfreq_suspend_device() - Suspend devfreq of a device.
 739  * @devfreq: the devfreq instance to be suspended
 740  *
 741  * This function is intended to be called by the pm callbacks
 742  * (e.g., runtime_suspend, suspend) of the device driver that
 743  * holds the devfreq.
 744  */
 745 int devfreq_suspend_device(struct devfreq *devfreq)
 746 {
 747         if (!devfreq)
 748                 return -EINVAL;
 749
 750         if (!devfreq->governor)
 751                 return 0;
 752
 753         return devfreq->governor->event_handler(devfreq,
 754                                 DEVFREQ_GOV_SUSPEND, NULL);
 755 }
 756 EXPORT_SYMBOL(devfreq_suspend_device);
 757
 758 /**
 759  * devfreq_resume_device() - Resume devfreq of a device.
 760  * @devfreq: the devfreq instance to be resumed
 761  *
 762  * This function is intended to be called by the pm callbacks
 763  * (e.g., runtime_resume, resume) of the device driver that
 764  * holds the devfreq.
 765  */
 766 int devfreq_resume_device(struct devfreq *devfreq)
 767 {
 768         if (!devfreq)
 769                 return -EINVAL;
 770
 771         if (!devfreq->governor)
 772                 return 0;
 773
 774         return devfreq->governor->event_handler(devfreq,
 775                                 DEVFREQ_GOV_RESUME, NULL);
 776 }
 777 EXPORT_SYMBOL(devfreq_resume_device);
 778
 779 /**
 780  * devfreq_add_governor() - Add devfreq governor
 781  * @governor:   the devfreq governor to be added
 782  */
 783 int devfreq_add_governor(struct devfreq_governor *governor)
 784 {
 785         struct devfreq_governor *g;
 786         struct devfreq *devfreq;
 787         int err = 0;
 788
 789         if (!governor) {
 790                 pr_err("%s: Invalid parameters.\n", __func__);
 791                 return -EINVAL;
 792         }
 793
 794         mutex_lock(&devfreq_list_lock);
 795         g = find_devfreq_governor(governor->name);
 796         if (!IS_ERR(g)) {
 797                 pr_err("%s: governor %s already registered\n", __func__,
 798                        g->name);
 799                 err = -EINVAL;
 800                 goto err_out;
 801         }
 802
 803         list_add(&governor->node, &devfreq_governor_list);
 804
 805         list_for_each_entry(devfreq, &devfreq_list, node) {
 806                 int ret = 0;
 807                 struct device *dev = devfreq->dev.parent;
 808
 809                 if (!strncmp(devfreq->governor_name, governor->name,
 810                              DEVFREQ_NAME_LEN)) {
 811                         /* The following should never occur */
 812                         if (devfreq->governor) {
 813                                 dev_warn(dev,
 814                                          "%s: Governor %s already present\n",
 815                                          __func__, devfreq->governor->name);
 816                                 ret = devfreq->governor->event_handler(devfreq,
 817                                                         DEVFREQ_GOV_STOP, NULL);
 818                                 if (ret) {
 819                                         dev_warn(dev,
 820                                                  "%s: Governor %s stop = %d\n",
 821                                                  __func__,
 822                                                  devfreq->governor->name, ret);
 823                                 }
 824                                 /* Fall through */
 825                         }
 826                         devfreq->governor = governor;
 827                         ret = devfreq->governor->event_handler(devfreq,
 828                                                 DEVFREQ_GOV_START, NULL);
 829                         if (ret) {
 830                                 dev_warn(dev, "%s: Governor %s start=%d\n",
 831                                          __func__, devfreq->governor->name,
 832                                          ret);
 833                         }
 834                 }
 835         }
 836
 837 err_out:
 838         mutex_unlock(&devfreq_list_lock);
 839
 840         return err;
 841 }
 842 EXPORT_SYMBOL(devfreq_add_governor);
 843
 844 /**
 845  * devfreq_remove_device() - Remove devfreq feature from a device.
 846  * @governor:   the devfreq governor to be removed
 847  */
 848 int devfreq_remove_governor(struct devfreq_governor *governor)
 849 {
 850         struct devfreq_governor *g;
 851         struct devfreq *devfreq;
 852         int err = 0;
 853
 854         if (!governor) {
 855                 pr_err("%s: Invalid parameters.\n", __func__);
 856                 return -EINVAL;
 857         }
 858
 859         mutex_lock(&devfreq_list_lock);
 860         g = find_devfreq_governor(governor->name);
 861         if (IS_ERR(g)) {
 862                 pr_err("%s: governor %s not registered\n", __func__,
 863                        governor->name);
 864                 err = PTR_ERR(g);
 865                 goto err_out;
 866         }
 867         list_for_each_entry(devfreq, &devfreq_list, node) {
 868                 int ret;
 869                 struct device *dev = devfreq->dev.parent;
 870
 871                 if (!strncmp(devfreq->governor_name, governor->name,
 872                              DEVFREQ_NAME_LEN)) {
 873                         /* we should have a devfreq governor! */
 874                         if (!devfreq->governor) {
 875                                 dev_warn(dev, "%s: Governor %s NOT present\n",
 876                                          __func__, governor->name);
 877                                 continue;
 878                                 /* Fall through */
 879                         }
 880                         ret = devfreq->governor->event_handler(devfreq,
 881                                                 DEVFREQ_GOV_STOP, NULL);
 882                         if (ret) {
 883                                 dev_warn(dev, "%s: Governor %s stop=%d\n",
 884                                          __func__, devfreq->governor->name,
 885                                          ret);
 886                         }
 887                         devfreq->governor = NULL;
 888                 }
 889         }
 890
 891         list_del(&governor->node);
 892 err_out:
 893         mutex_unlock(&devfreq_list_lock);
 894
 895         return err;
 896 }
 897 EXPORT_SYMBOL(devfreq_remove_governor);
 898
 899 static ssize_t governor_show(struct device *dev,
 900                              struct device_attribute *attr, char *buf)
 901 {
 902         if (!to_devfreq(dev)->governor)
 903                 return -EINVAL;
 904
 905         return sprintf(buf, "%s\n", to_devfreq(dev)->governor->name);
 906 }
 907
 908 static ssize_t governor_store(struct device *dev, struct device_attribute *attr,
 909                               const char *buf, size_t count)
 910 {
 911         struct devfreq *df = to_devfreq(dev);
 912         int ret;
 913         char str_governor[DEVFREQ_NAME_LEN + 1];
 914         struct devfreq_governor *governor;
 915
 916         ret = sscanf(buf, "%" __stringify(DEVFREQ_NAME_LEN) "s", str_governor);
 917         if (ret != 1)
 918                 return -EINVAL;
 919
 920         mutex_lock(&devfreq_list_lock);
 921         governor = find_devfreq_governor(str_governor);
 922         if (IS_ERR(governor)) {
 923                 ret = PTR_ERR(governor);
 924                 goto out;
 925         }
 926         if (df->governor == governor) {
 927                 ret = 0;
 928                 goto out;
 929         }
 930
 931         if (df->governor) {
 932                 ret = df->governor->event_handler(df, DEVFREQ_GOV_STOP, NULL);
 933                 if (ret) {
 934                         dev_warn(dev, "%s: Governor %s not stopped(%d)\n",
 935                                  __func__, df->governor->name, ret);
 936                         goto out;
 937                 }
 938         }
 939         df->governor = governor;
 940         strncpy(df->governor_name, governor->name, DEVFREQ_NAME_LEN);
 941         ret = df->governor->event_handler(df, DEVFREQ_GOV_START, NULL);
 942         if (ret)
 943                 dev_warn(dev, "%s: Governor %s not started(%d)\n",
 944                          __func__, df->governor->name, ret);
 945 out:
 946         mutex_unlock(&devfreq_list_lock);
 947
 948         if (!ret)
 949                 ret = count;
 950         return ret;
 951 }
 952 static DEVICE_ATTR_RW(governor);
 953
 954 static ssize_t available_governors_show(struct device *d,
 955                                         struct device_attribute *attr,
 956                                         char *buf)
 957 {
 958         struct devfreq_governor *tmp_governor;
 959         ssize_t count = 0;
 960
 961         mutex_lock(&devfreq_list_lock);
 962         list_for_each_entry(tmp_governor, &devfreq_governor_list, node)
 963                 count += scnprintf(&buf[count], (PAGE_SIZE - count - 2),
 964                                    "%s ", tmp_governor->name);
 965         mutex_unlock(&devfreq_list_lock);
 966
 967         /* Truncate the trailing space */
 968         if (count)
 969                 count--;
 970
 971         count += sprintf(&buf[count], "\n");
 972
 973         return count;
 974 }
 975 static DEVICE_ATTR_RO(available_governors);
 976
 977 static ssize_t cur_freq_show(struct device *dev, struct device_attribute *attr,
 978                              char *buf)
 979 {
 980         unsigned long freq;
 981         struct devfreq *devfreq = to_devfreq(dev);
 982
 983         if (devfreq->profile->get_cur_freq &&
 984                 !devfreq->profile->get_cur_freq(devfreq->dev.parent, &freq))
 985                         return sprintf(buf, "%lu\n", freq);
 986
 987         return sprintf(buf, "%lu\n", devfreq->previous_freq);
 988 }
 989 static DEVICE_ATTR_RO(cur_freq);
 990
 991 static ssize_t target_freq_show(struct device *dev,
 992                                 struct device_attribute *attr, char *buf)
 993 {
 994         return sprintf(buf, "%lu\n", to_devfreq(dev)->previous_freq);
 995 }
 996 static DEVICE_ATTR_RO(target_freq);
 997
 998 static ssize_t polling_interval_show(struct device *dev,
 999                                      struct device_attribute *attr, char *buf)
1000 {
1001         return sprintf(buf, "%d\n", to_devfreq(dev)->profile->polling_ms);
1002 }
1003
1004 static ssize_t polling_interval_store(struct device *dev,
1005                                       struct device_attribute *attr,
1006                                       const char *buf, size_t count)
1007 {
1008         struct devfreq *df = to_devfreq(dev);
1009         unsigned int value;
1010         int ret;
1011
1012         if (!df->governor)
1013                 return -EINVAL;
1014
1015         ret = sscanf(buf, "%u", &value);
1016         if (ret != 1)
1017                 return -EINVAL;
1018
1019         df->governor->event_handler(df, DEVFREQ_GOV_INTERVAL, &value);
1020         ret = count;
1021
1022         return ret;
1023 }
1024 static DEVICE_ATTR_RW(polling_interval);
1025
1026 static ssize_t min_freq_store(struct device *dev, struct device_attribute *attr,
1027                               const char *buf, size_t count)
1028 {
1029         struct devfreq *df = to_devfreq(dev);
1030         unsigned long value;
1031         int ret;
1032         unsigned long max;
1033
1034         ret = sscanf(buf, "%lu", &value);
1035         if (ret != 1)
1036                 return -EINVAL;
1037
1038         mutex_lock(&df->lock);
1039         max = df->max_freq;
1040         if (value && max && value > max) {
1041                 ret = -EINVAL;
1042                 goto unlock;
1043         }
1044
1045         df->min_freq = value;
1046         update_devfreq(df);
1047         ret = count;
1048 unlock:
1049         mutex_unlock(&df->lock);
1050         return ret;
1051 }
1052
1053 static ssize_t max_freq_store(struct device *dev, struct device_attribute *attr,
1054                               const char *buf, size_t count)
1055 {
1056         struct devfreq *df = to_devfreq(dev);
1057         unsigned long value;
1058         int ret;
1059         unsigned long min;
1060
1061         ret = sscanf(buf, "%lu", &value);
1062         if (ret != 1)
1063                 return -EINVAL;
1064
1065         mutex_lock(&df->lock);
1066         min = df->min_freq;
1067         if (value && min && value < min) {
1068                 ret = -EINVAL;
1069                 goto unlock;
1070         }
1071
1072         df->max_freq = value;
1073         update_devfreq(df);
1074         ret = count;
1075 unlock:
1076         mutex_unlock(&df->lock);
1077         return ret;
1078 }
1079
1080 #define show_one(name)                                          \
1081 static ssize_t name##_show                                      \
1082 (struct device *dev, struct device_attribute *attr, char *buf)  \
1083 {                                                               \
1084         return sprintf(buf, "%lu\n", to_devfreq(dev)->name);    \
1085 }
1086 show_one(min_freq);
1087 show_one(max_freq);
1088
1089 static DEVICE_ATTR_RW(min_freq);
1090 static DEVICE_ATTR_RW(max_freq);
1091
1092 static ssize_t available_frequencies_show(struct device *d,
1093                                           struct device_attribute *attr,
1094                                           char *buf)
1095 {
1096         struct devfreq *df = to_devfreq(d);
1097         struct device *dev = df->dev.parent;
1098         struct dev_pm_opp *opp;
1099         ssize_t count = 0;
1100         unsigned long freq = 0;
1101
1102         rcu_read_lock();
1103         do {
1104                 opp = dev_pm_opp_find_freq_ceil(dev, &freq);
1105                 if (IS_ERR(opp))
1106                         break;
1107
1108                 count += scnprintf(&buf[count], (PAGE_SIZE - count - 2),
1109                                    "%lu ", freq);
1110                 freq++;
1111         } while (1);
1112         rcu_read_unlock();
1113
1114         /* Truncate the trailing space */
1115         if (count)
1116                 count--;
1117
1118         count += sprintf(&buf[count], "\n");
1119
1120         return count;
1121 }
1122 static DEVICE_ATTR_RO(available_frequencies);
1123
1124 static ssize_t trans_stat_show(struct device *dev,
1125                                struct device_attribute *attr, char *buf)
1126 {
1127         struct devfreq *devfreq = to_devfreq(dev);
1128         ssize_t len;
1129         int i, j;
1130         unsigned int max_state = devfreq->profile->max_state;
1131
1132         if (!devfreq->stop_polling &&
1133                         devfreq_update_status(devfreq, devfreq->previous_freq))
1134                 return 0;
1135         if (max_state == 0)
1136                 return sprintf(buf, "Not Supported.\n");
1137
1138         len = sprintf(buf, "     From  :   To\n");
1139         len += sprintf(buf + len, "           :");
1140         for (i = 0; i < max_state; i++)
1141                 len += sprintf(buf + len, "%10lu",
1142                                 devfreq->profile->freq_table[i]);
1143
1144         len += sprintf(buf + len, "   time(ms)\n");
1145
1146         for (i = 0; i < max_state; i++) {
1147                 if (devfreq->profile->freq_table[i]
1148                                         == devfreq->previous_freq) {
1149                         len += sprintf(buf + len, "*");
1150                 } else {
1151                         len += sprintf(buf + len, " ");
1152                 }
1153                 len += sprintf(buf + len, "%10lu:",
1154                                 devfreq->profile->freq_table[i]);
1155                 for (j = 0; j < max_state; j++)
1156                         len += sprintf(buf + len, "%10u",
1157                                 devfreq->trans_table[(i * max_state) + j]);
1158                 len += sprintf(buf + len, "%10u\n",
1159                         jiffies_to_msecs(devfreq->time_in_state[i]));
1160         }
1161
1162         len += sprintf(buf + len, "Total transition : %u\n",
1163                                         devfreq->total_trans);
1164         return len;
1165 }
1166 static DEVICE_ATTR_RO(trans_stat);
1167
1168 static struct attribute *devfreq_attrs[] = {
1169         &dev_attr_governor.attr,
1170         &dev_attr_available_governors.attr,
1171         &dev_attr_cur_freq.attr,
1172         &dev_attr_available_frequencies.attr,
1173         &dev_attr_target_freq.attr,
1174         &dev_attr_polling_interval.attr,
1175         &dev_attr_min_freq.attr,
1176         &dev_attr_max_freq.attr,
1177         &dev_attr_trans_stat.attr,
1178         NULL,
1179 };
1180 ATTRIBUTE_GROUPS(devfreq);
1181
1182 static int __init devfreq_init(void)
1183 {
1184         devfreq_class = class_create(THIS_MODULE, "devfreq");
1185         if (IS_ERR(devfreq_class)) {
1186                 pr_err("%s: couldn't create class\n", __FILE__);
1187                 return PTR_ERR(devfreq_class);
1188         }
1189
1190         devfreq_wq = create_freezable_workqueue("devfreq_wq");
1191         if (!devfreq_wq) {
1192                 class_destroy(devfreq_class);
1193                 pr_err("%s: couldn't create workqueue\n", __FILE__);
1194                 return -ENOMEM;
1195         }
1196         devfreq_class->dev_groups = devfreq_groups;
1197
1198         return 0;
1199 }
1200 subsys_initcall(devfreq_init);
1201
1202 static void __exit devfreq_exit(void)
1203 {
1204         class_destroy(devfreq_class);
1205         destroy_workqueue(devfreq_wq);
1206 }
1207 module_exit(devfreq_exit);
1208
1209 /*
1210  * The followings are helper functions for devfreq user device drivers with
1211  * OPP framework.
1212  */
1213
1214 /**
1215  * devfreq_recommended_opp() - Helper function to get proper OPP for the
1216  *                           freq value given to target callback.
1217  * @dev:        The devfreq user device. (parent of devfreq)
1218  * @freq:       The frequency given to target function
1219  * @flags:      Flags handed from devfreq framework.
1220  *
1221  * Locking: This function must be called under rcu_read_lock(). opp is a rcu
1222  * protected pointer. The reason for the same is that the opp pointer which is
1223  * returned will remain valid for use with opp_get_{voltage, freq} only while
1224  * under the locked area. The pointer returned must be used prior to unlocking
1225  * with rcu_read_unlock() to maintain the integrity of the pointer.
1226  */
1227 struct dev_pm_opp *devfreq_recommended_opp(struct device *dev,
1228                                            unsigned long *freq,
1229                                            u32 flags)
1230 {
1231         struct dev_pm_opp *opp;
1232
1233         if (flags & DEVFREQ_FLAG_LEAST_UPPER_BOUND) {
1234                 /* The freq is an upper bound. opp should be lower */
1235                 opp = dev_pm_opp_find_freq_floor(dev, freq);
1236
1237                 /* If not available, use the closest opp */
1238                 if (opp == ERR_PTR(-ERANGE))
1239                         opp = dev_pm_opp_find_freq_ceil(dev, freq);
1240         } else {
1241                 /* The freq is an lower bound. opp should be higher */
1242                 opp = dev_pm_opp_find_freq_ceil(dev, freq);
1243
1244                 /* If not available, use the closest opp */
1245                 if (opp == ERR_PTR(-ERANGE))
1246                         opp = dev_pm_opp_find_freq_floor(dev, freq);
1247         }
1248
1249         return opp;
1250 }
1251 EXPORT_SYMBOL(devfreq_recommended_opp);
1252
1253 /**
1254  * devfreq_register_opp_notifier() - Helper function to get devfreq notified
1255  *                                 for any changes in the OPP availability
1256  *                                 changes
1257  * @dev:        The devfreq user device. (parent of devfreq)
1258  * @devfreq:    The devfreq object.
1259  */
1260 int devfreq_register_opp_notifier(struct device *dev, struct devfreq *devfreq)
1261 {
1262         struct srcu_notifier_head *nh;
1263         int ret = 0;
1264
1265         rcu_read_lock();
1266         nh = dev_pm_opp_get_notifier(dev);
1267         if (IS_ERR(nh))
1268                 ret = PTR_ERR(nh);
1269         rcu_read_unlock();
1270         if (!ret)
1271                 ret = srcu_notifier_chain_register(nh, &devfreq->nb);
1272
1273         return ret;
1274 }
1275 EXPORT_SYMBOL(devfreq_register_opp_notifier);
1276
1277 /**
1278  * devfreq_unregister_opp_notifier() - Helper function to stop getting devfreq
1279  *                                   notified for any changes in the OPP
1280  *                                   availability changes anymore.
1281  * @dev:        The devfreq user device. (parent of devfreq)
1282  * @devfreq:    The devfreq object.
1283  *
1284  * At exit() callback of devfreq_dev_profile, this must be included if
1285  * devfreq_recommended_opp is used.
1286  */
1287 int devfreq_unregister_opp_notifier(struct device *dev, struct devfreq *devfreq)
1288 {
1289         struct srcu_notifier_head *nh;
1290         int ret = 0;
1291
1292         rcu_read_lock();
1293         nh = dev_pm_opp_get_notifier(dev);
1294         if (IS_ERR(nh))
1295                 ret = PTR_ERR(nh);
1296         rcu_read_unlock();
1297         if (!ret)
1298                 ret = srcu_notifier_chain_unregister(nh, &devfreq->nb);
1299
1300         return ret;
1301 }
1302 EXPORT_SYMBOL(devfreq_unregister_opp_notifier);
1303
1304 static void devm_devfreq_opp_release(struct device *dev, void *res)
1305 {
1306         devfreq_unregister_opp_notifier(dev, *(struct devfreq **)res);
1307 }
1308
1309 /**
1310  * devm_ devfreq_register_opp_notifier()
1311  *              - Resource-managed devfreq_register_opp_notifier()
1312  * @dev:        The devfreq user device. (parent of devfreq)
1313  * @devfreq:    The devfreq object.
1314  */
1315 int devm_devfreq_register_opp_notifier(struct device *dev,
1316                                        struct devfreq *devfreq)
1317 {
1318         struct devfreq **ptr;
1319         int ret;
1320
1321         ptr = devres_alloc(devm_devfreq_opp_release, sizeof(*ptr), GFP_KERNEL);
1322         if (!ptr)
1323                 return -ENOMEM;
1324
1325         ret = devfreq_register_opp_notifier(dev, devfreq);
1326         if (ret) {
1327                 devres_free(ptr);
1328                 return ret;
1329         }
1330
1331         *ptr = devfreq;
1332         devres_add(dev, ptr);
1333
1334         return 0;
1335 }
1336 EXPORT_SYMBOL(devm_devfreq_register_opp_notifier);
1337
1338 /**
1339  * devm_devfreq_unregister_opp_notifier()
1340  *              - Resource-managed devfreq_unregister_opp_notifier()
1341  * @dev:        The devfreq user device. (parent of devfreq)
1342  * @devfreq:    The devfreq object.
1343  */
1344 void devm_devfreq_unregister_opp_notifier(struct device *dev,
1345                                          struct devfreq *devfreq)
1346 {
1347         WARN_ON(devres_release(dev, devm_devfreq_opp_release,
1348                                devm_devfreq_dev_match, devfreq));
1349 }
1350 EXPORT_SYMBOL(devm_devfreq_unregister_opp_notifier);
1351
1352 /**
1353  * devfreq_register_notifier() - Register a driver with devfreq
1354  * @devfreq:    The devfreq object.
1355  * @nb:         The notifier block to register.
1356  * @list:       DEVFREQ_TRANSITION_NOTIFIER.
1357  */
1358 int devfreq_register_notifier(struct devfreq *devfreq,
1359                                 struct notifier_block *nb,
1360                                 unsigned int list)
1361 {
1362         int ret = 0;
1363
1364         if (!devfreq)
1365                 return -EINVAL;
1366
1367         switch (list) {
1368         case DEVFREQ_TRANSITION_NOTIFIER:
1369                 ret = srcu_notifier_chain_register(
1370                                 &devfreq->transition_notifier_list, nb);
1371                 break;
1372         default:
1373                 ret = -EINVAL;
1374         }
1375
1376         return ret;
1377 }
1378 EXPORT_SYMBOL(devfreq_register_notifier);
1379
1380 /*
1381  * devfreq_unregister_notifier() - Unregister a driver with devfreq
1382  * @devfreq:    The devfreq object.
1383  * @nb:         The notifier block to be unregistered.
1384  * @list:       DEVFREQ_TRANSITION_NOTIFIER.
1385  */
1386 int devfreq_unregister_notifier(struct devfreq *devfreq,
1387                                 struct notifier_block *nb,
1388                                 unsigned int list)
1389 {
1390         int ret = 0;
1391
1392         if (!devfreq)
1393                 return -EINVAL;
1394
1395         switch (list) {
1396         case DEVFREQ_TRANSITION_NOTIFIER:
1397                 ret = srcu_notifier_chain_unregister(
1398                                 &devfreq->transition_notifier_list, nb);
1399                 break;
1400         default:
1401                 ret = -EINVAL;
1402         }
1403
1404         return ret;
1405 }
1406 EXPORT_SYMBOL(devfreq_unregister_notifier);
1407
1408 struct devfreq_notifier_devres {
1409         struct devfreq *devfreq;
1410         struct notifier_block *nb;
1411         unsigned int list;
1412 };
1413
1414 static void devm_devfreq_notifier_release(struct device *dev, void *res)
1415 {
1416         struct devfreq_notifier_devres *this = res;
1417
1418         devfreq_unregister_notifier(this->devfreq, this->nb, this->list);
1419 }
1420
1421 /**
1422  * devm_devfreq_register_notifier()
1423         - Resource-managed devfreq_register_notifier()
1424  * @dev:        The devfreq user device. (parent of devfreq)
1425  * @devfreq:    The devfreq object.
1426  * @nb:         The notifier block to be unregistered.
1427  * @list:       DEVFREQ_TRANSITION_NOTIFIER.
1428  */
1429 int devm_devfreq_register_notifier(struct device *dev,
1430                                 struct devfreq *devfreq,
1431                                 struct notifier_block *nb,
1432                                 unsigned int list)
1433 {
1434         struct devfreq_notifier_devres *ptr;
1435         int ret;
1436
1437         ptr = devres_alloc(devm_devfreq_notifier_release, sizeof(*ptr),
1438                                 GFP_KERNEL);
1439         if (!ptr)
1440                 return -ENOMEM;
1441
1442         ret = devfreq_register_notifier(devfreq, nb, list);
1443         if (ret) {
1444                 devres_free(ptr);
1445                 return ret;
1446         }
1447
1448         ptr->devfreq = devfreq;
1449         ptr->nb = nb;
1450         ptr->list = list;
1451         devres_add(dev, ptr);
1452
1453         return 0;
1454 }
1455 EXPORT_SYMBOL(devm_devfreq_register_notifier);
1456
1457 /**
1458  * devm_devfreq_unregister_notifier()
1459         - Resource-managed devfreq_unregister_notifier()
1460  * @dev:        The devfreq user device. (parent of devfreq)
1461  * @devfreq:    The devfreq object.
1462  * @nb:         The notifier block to be unregistered.
1463  * @list:       DEVFREQ_TRANSITION_NOTIFIER.
1464  */
1465 void devm_devfreq_unregister_notifier(struct device *dev,
1466                                 struct devfreq *devfreq,
1467                                 struct notifier_block *nb,
1468                                 unsigned int list)
1469 {
1470         WARN_ON(devres_release(dev, devm_devfreq_notifier_release,
1471                                devm_devfreq_dev_match, devfreq));
1472 }
1473 EXPORT_SYMBOL(devm_devfreq_unregister_notifier);
1474
1475 MODULE_AUTHOR("MyungJoo Ham <myungjoo.ham@samsung.com>");
1476 MODULE_DESCRIPTION("devfreq class support");
1477 MODULE_LICENSE("GPL");