drivers/devfreq/devfreq.c

   1 /*
   2  * devfreq: Generic Dynamic Voltage and Frequency Scaling (DVFS) Framework
   3  *          for Non-CPU Devices.
   4  *
   5  * Copyright (C) 2011 Samsung Electronics
   6  *      MyungJoo Ham <myungjoo.ham@samsung.com>
   7  *
   8  * This program is free software; you can redistribute it and/or modify
   9  * it under the terms of the GNU General Public License version 2 as
  10  * published by the Free Software Foundation.
  11  */
  12
  13 #include <linux/kernel.h>
  14 #include <linux/sched.h>
  15 #include <linux/errno.h>
  16 #include <linux/err.h>
  17 #include <linux/init.h>
  18 #include <linux/export.h>
  19 #include <linux/slab.h>
  20 #include <linux/stat.h>
  21 #include <linux/pm_opp.h>
  22 #include <linux/devfreq.h>
  23 #include <linux/workqueue.h>
  24 #include <linux/platform_device.h>
  25 #include <linux/list.h>
  26 #include <linux/printk.h>
  27 #include <linux/hrtimer.h>
  28 #include <linux/of.h>
  29 #include "governor.h"
  30
  31 static struct class *devfreq_class;
  32
  33 /*
  34  * devfreq core provides delayed work based load monitoring helper
  35  * functions. Governors can use these or can implement their own
  36  * monitoring mechanism.
  37  */
  38 static struct workqueue_struct *devfreq_wq;
  39
  40 /* The list of all device-devfreq governors */
  41 static LIST_HEAD(devfreq_governor_list);
  42 /* The list of all device-devfreq */
  43 static LIST_HEAD(devfreq_list);
  44 static DEFINE_MUTEX(devfreq_list_lock);
  45
  46 /**
  47  * find_device_devfreq() - find devfreq struct using device pointer
  48  * @dev:        device pointer used to lookup device devfreq.
  49  *
  50  * Search the list of device devfreqs and return the matched device's
  51  * devfreq info. devfreq_list_lock should be held by the caller.
  52  */
  53 static struct devfreq *find_device_devfreq(struct device *dev)
  54 {
  55         struct devfreq *tmp_devfreq;
  56
  57         if (IS_ERR_OR_NULL(dev)) {
  58                 pr_err("DEVFREQ: %s: Invalid parameters\n", __func__);
  59                 return ERR_PTR(-EINVAL);
  60         }
  61         WARN(!mutex_is_locked(&devfreq_list_lock),
  62              "devfreq_list_lock must be locked.");
  63
  64         list_for_each_entry(tmp_devfreq, &devfreq_list, node) {
  65                 if (tmp_devfreq->dev.parent == dev)
  66                         return tmp_devfreq;
  67         }
  68
  69         return ERR_PTR(-ENODEV);
  70 }
  71
  72 /**
  73  * devfreq_get_freq_level() - Lookup freq_table for the frequency
  74  * @devfreq:    the devfreq instance
  75  * @freq:       the target frequency
  76  */
  77 static int devfreq_get_freq_level(struct devfreq *devfreq, unsigned long freq)
  78 {
  79         int lev;
  80
  81         for (lev = 0; lev < devfreq->profile->max_state; lev++)
  82                 if (freq == devfreq->profile->freq_table[lev])
  83                         return lev;
  84
  85         return -EINVAL;
  86 }
  87
  88 /**
  89  * devfreq_set_freq_table() - Initialize freq_table for the frequency
  90  * @devfreq:    the devfreq instance
  91  */
  92 static void devfreq_set_freq_table(struct devfreq *devfreq)
  93 {
  94         struct devfreq_dev_profile *profile = devfreq->profile;
  95         struct dev_pm_opp *opp;
  96         unsigned long freq;
  97         int i, count;
  98
  99         /* Initialize the freq_table from OPP table */
 100         count = dev_pm_opp_get_opp_count(devfreq->dev.parent);
 101         if (count <= 0)
 102                 return;
 103
 104         profile->max_state = count;
 105         profile->freq_table = devm_kcalloc(devfreq->dev.parent,
 106                                         profile->max_state,
 107                                         sizeof(*profile->freq_table),
 108                                         GFP_KERNEL);
 109         if (!profile->freq_table) {
 110                 profile->max_state = 0;
 111                 return;
 112         }
 113
 114         rcu_read_lock();
 115         for (i = 0, freq = 0; i < profile->max_state; i++, freq++) {
 116                 opp = dev_pm_opp_find_freq_ceil(devfreq->dev.parent, &freq);
 117                 if (IS_ERR(opp)) {
 118                         devm_kfree(devfreq->dev.parent, profile->freq_table);
 119                         profile->max_state = 0;
 120                         rcu_read_unlock();
 121                         return;
 122                 }
 123                 profile->freq_table[i] = freq;
 124         }
 125         rcu_read_unlock();
 126 }
 127
 128 /**
 129  * devfreq_update_status() - Update statistics of devfreq behavior
 130  * @devfreq:    the devfreq instance
 131  * @freq:       the update target frequency
 132  */
 133 static int devfreq_update_status(struct devfreq *devfreq, unsigned long freq)
 134 {
 135         int lev, prev_lev, ret = 0;
 136         unsigned long cur_time;
 137
 138         cur_time = jiffies;
 139
 140         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                         of_node_put(node);
 711                         return devfreq;
 712                 }
 713         }
 714         mutex_unlock(&devfreq_list_lock);
 715         of_node_put(node);
 716
 717         return ERR_PTR(-EPROBE_DEFER);
 718 }
 719 #else
 720 struct devfreq *devfreq_get_devfreq_by_phandle(struct device *dev, int index)
 721 {
 722         return ERR_PTR(-ENODEV);
 723 }
 724 #endif /* CONFIG_OF */
 725 EXPORT_SYMBOL_GPL(devfreq_get_devfreq_by_phandle);
 726
 727 /**
 728  * devm_devfreq_remove_device() - Resource-managed devfreq_remove_device()
 729  * @dev:        the device to add devfreq feature.
 730  * @devfreq:    the devfreq instance to be removed
 731  */
 732 void devm_devfreq_remove_device(struct device *dev, struct devfreq *devfreq)
 733 {
 734         WARN_ON(devres_release(dev, devm_devfreq_dev_release,
 735                                devm_devfreq_dev_match, devfreq));
 736 }
 737 EXPORT_SYMBOL(devm_devfreq_remove_device);
 738
 739 /**
 740  * devfreq_suspend_device() - Suspend devfreq of a device.
 741  * @devfreq: the devfreq instance to be suspended
 742  *
 743  * This function is intended to be called by the pm callbacks
 744  * (e.g., runtime_suspend, suspend) of the device driver that
 745  * holds the devfreq.
 746  */
 747 int devfreq_suspend_device(struct devfreq *devfreq)
 748 {
 749         if (!devfreq)
 750                 return -EINVAL;
 751
 752         if (!devfreq->governor)
 753                 return 0;
 754
 755         return devfreq->governor->event_handler(devfreq,
 756                                 DEVFREQ_GOV_SUSPEND, NULL);
 757 }
 758 EXPORT_SYMBOL(devfreq_suspend_device);
 759
 760 /**
 761  * devfreq_resume_device() - Resume devfreq of a device.
 762  * @devfreq: the devfreq instance to be resumed
 763  *
 764  * This function is intended to be called by the pm callbacks
 765  * (e.g., runtime_resume, resume) of the device driver that
 766  * holds the devfreq.
 767  */
 768 int devfreq_resume_device(struct devfreq *devfreq)
 769 {
 770         if (!devfreq)
 771                 return -EINVAL;
 772
 773         if (!devfreq->governor)
 774                 return 0;
 775
 776         return devfreq->governor->event_handler(devfreq,
 777                                 DEVFREQ_GOV_RESUME, NULL);
 778 }
 779 EXPORT_SYMBOL(devfreq_resume_device);
 780
 781 /**
 782  * devfreq_add_governor() - Add devfreq governor
 783  * @governor:   the devfreq governor to be added
 784  */
 785 int devfreq_add_governor(struct devfreq_governor *governor)
 786 {
 787         struct devfreq_governor *g;
 788         struct devfreq *devfreq;
 789         int err = 0;
 790
 791         if (!governor) {
 792                 pr_err("%s: Invalid parameters.\n", __func__);
 793                 return -EINVAL;
 794         }
 795
 796         mutex_lock(&devfreq_list_lock);
 797         g = find_devfreq_governor(governor->name);
 798         if (!IS_ERR(g)) {
 799                 pr_err("%s: governor %s already registered\n", __func__,
 800                        g->name);
 801                 err = -EINVAL;
 802                 goto err_out;
 803         }
 804
 805         list_add(&governor->node, &devfreq_governor_list);
 806
 807         list_for_each_entry(devfreq, &devfreq_list, node) {
 808                 int ret = 0;
 809                 struct device *dev = devfreq->dev.parent;
 810
 811                 if (!strncmp(devfreq->governor_name, governor->name,
 812                              DEVFREQ_NAME_LEN)) {
 813                         /* The following should never occur */
 814                         if (devfreq->governor) {
 815                                 dev_warn(dev,
 816                                          "%s: Governor %s already present\n",
 817                                          __func__, devfreq->governor->name);
 818                                 ret = devfreq->governor->event_handler(devfreq,
 819                                                         DEVFREQ_GOV_STOP, NULL);
 820                                 if (ret) {
 821                                         dev_warn(dev,
 822                                                  "%s: Governor %s stop = %d\n",
 823                                                  __func__,
 824                                                  devfreq->governor->name, ret);
 825                                 }
 826                                 /* Fall through */
 827                         }
 828                         devfreq->governor = governor;
 829                         ret = devfreq->governor->event_handler(devfreq,
 830                                                 DEVFREQ_GOV_START, NULL);
 831                         if (ret) {
 832                                 dev_warn(dev, "%s: Governor %s start=%d\n",
 833                                          __func__, devfreq->governor->name,
 834                                          ret);
 835                         }
 836                 }
 837         }
 838
 839 err_out:
 840         mutex_unlock(&devfreq_list_lock);
 841
 842         return err;
 843 }
 844 EXPORT_SYMBOL(devfreq_add_governor);
 845
 846 /**
 847  * devfreq_remove_device() - Remove devfreq feature from a device.
 848  * @governor:   the devfreq governor to be removed
 849  */
 850 int devfreq_remove_governor(struct devfreq_governor *governor)
 851 {
 852         struct devfreq_governor *g;
 853         struct devfreq *devfreq;
 854         int err = 0;
 855
 856         if (!governor) {
 857                 pr_err("%s: Invalid parameters.\n", __func__);
 858                 return -EINVAL;
 859         }
 860
 861         mutex_lock(&devfreq_list_lock);
 862         g = find_devfreq_governor(governor->name);
 863         if (IS_ERR(g)) {
 864                 pr_err("%s: governor %s not registered\n", __func__,
 865                        governor->name);
 866                 err = PTR_ERR(g);
 867                 goto err_out;
 868         }
 869         list_for_each_entry(devfreq, &devfreq_list, node) {
 870                 int ret;
 871                 struct device *dev = devfreq->dev.parent;
 872
 873                 if (!strncmp(devfreq->governor_name, governor->name,
 874                              DEVFREQ_NAME_LEN)) {
 875                         /* we should have a devfreq governor! */
 876                         if (!devfreq->governor) {
 877                                 dev_warn(dev, "%s: Governor %s NOT present\n",
 878                                          __func__, governor->name);
 879                                 continue;
 880                                 /* Fall through */
 881                         }
 882                         ret = devfreq->governor->event_handler(devfreq,
 883                                                 DEVFREQ_GOV_STOP, NULL);
 884                         if (ret) {
 885                                 dev_warn(dev, "%s: Governor %s stop=%d\n",
 886                                          __func__, devfreq->governor->name,
 887                                          ret);
 888                         }
 889                         devfreq->governor = NULL;
 890                 }
 891         }
 892
 893         list_del(&governor->node);
 894 err_out:
 895         mutex_unlock(&devfreq_list_lock);
 896
 897         return err;
 898 }
 899 EXPORT_SYMBOL(devfreq_remove_governor);
 900
 901 static ssize_t governor_show(struct device *dev,
 902                              struct device_attribute *attr, char *buf)
 903 {
 904         if (!to_devfreq(dev)->governor)
 905                 return -EINVAL;
 906
 907         return sprintf(buf, "%s\n", to_devfreq(dev)->governor->name);
 908 }
 909
 910 static ssize_t governor_store(struct device *dev, struct device_attribute *attr,
 911                               const char *buf, size_t count)
 912 {
 913         struct devfreq *df = to_devfreq(dev);
 914         int ret;
 915         char str_governor[DEVFREQ_NAME_LEN + 1];
 916         struct devfreq_governor *governor;
 917
 918         ret = sscanf(buf, "%" __stringify(DEVFREQ_NAME_LEN) "s", str_governor);
 919         if (ret != 1)
 920                 return -EINVAL;
 921
 922         mutex_lock(&devfreq_list_lock);
 923         governor = find_devfreq_governor(str_governor);
 924         if (IS_ERR(governor)) {
 925                 ret = PTR_ERR(governor);
 926                 goto out;
 927         }
 928         if (df->governor == governor) {
 929                 ret = 0;
 930                 goto out;
 931         }
 932
 933         if (df->governor) {
 934                 ret = df->governor->event_handler(df, DEVFREQ_GOV_STOP, NULL);
 935                 if (ret) {
 936                         dev_warn(dev, "%s: Governor %s not stopped(%d)\n",
 937                                  __func__, df->governor->name, ret);
 938                         goto out;
 939                 }
 940         }
 941         df->governor = governor;
 942         strncpy(df->governor_name, governor->name, DEVFREQ_NAME_LEN);
 943         ret = df->governor->event_handler(df, DEVFREQ_GOV_START, NULL);
 944         if (ret)
 945                 dev_warn(dev, "%s: Governor %s not started(%d)\n",
 946                          __func__, df->governor->name, ret);
 947 out:
 948         mutex_unlock(&devfreq_list_lock);
 949
 950         if (!ret)
 951                 ret = count;
 952         return ret;
 953 }
 954 static DEVICE_ATTR_RW(governor);
 955
 956 static ssize_t available_governors_show(struct device *d,
 957                                         struct device_attribute *attr,
 958                                         char *buf)
 959 {
 960         struct devfreq_governor *tmp_governor;
 961         ssize_t count = 0;
 962
 963         mutex_lock(&devfreq_list_lock);
 964         list_for_each_entry(tmp_governor, &devfreq_governor_list, node)
 965                 count += scnprintf(&buf[count], (PAGE_SIZE - count - 2),
 966                                    "%s ", tmp_governor->name);
 967         mutex_unlock(&devfreq_list_lock);
 968
 969         /* Truncate the trailing space */
 970         if (count)
 971                 count--;
 972
 973         count += sprintf(&buf[count], "\n");
 974
 975         return count;
 976 }
 977 static DEVICE_ATTR_RO(available_governors);
 978
 979 static ssize_t cur_freq_show(struct device *dev, struct device_attribute *attr,
 980                              char *buf)
 981 {
 982         unsigned long freq;
 983         struct devfreq *devfreq = to_devfreq(dev);
 984
 985         if (devfreq->profile->get_cur_freq &&
 986                 !devfreq->profile->get_cur_freq(devfreq->dev.parent, &freq))
 987                         return sprintf(buf, "%lu\n", freq);
 988
 989         return sprintf(buf, "%lu\n", devfreq->previous_freq);
 990 }
 991 static DEVICE_ATTR_RO(cur_freq);
 992
 993 static ssize_t target_freq_show(struct device *dev,
 994                                 struct device_attribute *attr, char *buf)
 995 {
 996         return sprintf(buf, "%lu\n", to_devfreq(dev)->previous_freq);
 997 }
 998 static DEVICE_ATTR_RO(target_freq);
 999
1000 static ssize_t polling_interval_show(struct device *dev,
1001                                      struct device_attribute *attr, char *buf)
1002 {
1003         return sprintf(buf, "%d\n", to_devfreq(dev)->profile->polling_ms);
1004 }
1005
1006 static ssize_t polling_interval_store(struct device *dev,
1007                                       struct device_attribute *attr,
1008                                       const char *buf, size_t count)
1009 {
1010         struct devfreq *df = to_devfreq(dev);
1011         unsigned int value;
1012         int ret;
1013
1014         if (!df->governor)
1015                 return -EINVAL;
1016
1017         ret = sscanf(buf, "%u", &value);
1018         if (ret != 1)
1019                 return -EINVAL;
1020
1021         df->governor->event_handler(df, DEVFREQ_GOV_INTERVAL, &value);
1022         ret = count;
1023
1024         return ret;
1025 }
1026 static DEVICE_ATTR_RW(polling_interval);
1027
1028 static ssize_t min_freq_store(struct device *dev, struct device_attribute *attr,
1029                               const char *buf, size_t count)
1030 {
1031         struct devfreq *df = to_devfreq(dev);
1032         unsigned long value;
1033         int ret;
1034         unsigned long max;
1035
1036         ret = sscanf(buf, "%lu", &value);
1037         if (ret != 1)
1038                 return -EINVAL;
1039
1040         mutex_lock(&df->lock);
1041         max = df->max_freq;
1042         if (value && max && value > max) {
1043                 ret = -EINVAL;
1044                 goto unlock;
1045         }
1046
1047         df->min_freq = value;
1048         update_devfreq(df);
1049         ret = count;
1050 unlock:
1051         mutex_unlock(&df->lock);
1052         return ret;
1053 }
1054
1055 static ssize_t max_freq_store(struct device *dev, struct device_attribute *attr,
1056                               const char *buf, size_t count)
1057 {
1058         struct devfreq *df = to_devfreq(dev);
1059         unsigned long value;
1060         int ret;
1061         unsigned long min;
1062
1063         ret = sscanf(buf, "%lu", &value);
1064         if (ret != 1)
1065                 return -EINVAL;
1066
1067         mutex_lock(&df->lock);
1068         min = df->min_freq;
1069         if (value && min && value < min) {
1070                 ret = -EINVAL;
1071                 goto unlock;
1072         }
1073
1074         df->max_freq = value;
1075         update_devfreq(df);
1076         ret = count;
1077 unlock:
1078         mutex_unlock(&df->lock);
1079         return ret;
1080 }
1081
1082 #define show_one(name)                                          \
1083 static ssize_t name##_show                                      \
1084 (struct device *dev, struct device_attribute *attr, char *buf)  \
1085 {                                                               \
1086         return sprintf(buf, "%lu\n", to_devfreq(dev)->name);    \
1087 }
1088 show_one(min_freq);
1089 show_one(max_freq);
1090
1091 static DEVICE_ATTR_RW(min_freq);
1092 static DEVICE_ATTR_RW(max_freq);
1093
1094 static ssize_t available_frequencies_show(struct device *d,
1095                                           struct device_attribute *attr,
1096                                           char *buf)
1097 {
1098         struct devfreq *df = to_devfreq(d);
1099         struct device *dev = df->dev.parent;
1100         struct dev_pm_opp *opp;
1101         ssize_t count = 0;
1102         unsigned long freq = 0;
1103
1104         rcu_read_lock();
1105         do {
1106                 opp = dev_pm_opp_find_freq_ceil(dev, &freq);
1107                 if (IS_ERR(opp))
1108                         break;
1109
1110                 count += scnprintf(&buf[count], (PAGE_SIZE - count - 2),
1111                                    "%lu ", freq);
1112                 freq++;
1113         } while (1);
1114         rcu_read_unlock();
1115
1116         /* Truncate the trailing space */
1117         if (count)
1118                 count--;
1119
1120         count += sprintf(&buf[count], "\n");
1121
1122         return count;
1123 }
1124 static DEVICE_ATTR_RO(available_frequencies);
1125
1126 static ssize_t trans_stat_show(struct device *dev,
1127                                struct device_attribute *attr, char *buf)
1128 {
1129         struct devfreq *devfreq = to_devfreq(dev);
1130         ssize_t len;
1131         int i, j;
1132         unsigned int max_state = devfreq->profile->max_state;
1133
1134         if (!devfreq->stop_polling &&
1135                         devfreq_update_status(devfreq, devfreq->previous_freq))
1136                 return 0;
1137         if (max_state == 0)
1138                 return sprintf(buf, "Not Supported.\n");
1139
1140         len = sprintf(buf, "     From  :   To\n");
1141         len += sprintf(buf + len, "           :");
1142         for (i = 0; i < max_state; i++)
1143                 len += sprintf(buf + len, "%10lu",
1144                                 devfreq->profile->freq_table[i]);
1145
1146         len += sprintf(buf + len, "   time(ms)\n");
1147
1148         for (i = 0; i < max_state; i++) {
1149                 if (devfreq->profile->freq_table[i]
1150                                         == devfreq->previous_freq) {
1151                         len += sprintf(buf + len, "*");
1152                 } else {
1153                         len += sprintf(buf + len, " ");
1154                 }
1155                 len += sprintf(buf + len, "%10lu:",
1156                                 devfreq->profile->freq_table[i]);
1157                 for (j = 0; j < max_state; j++)
1158                         len += sprintf(buf + len, "%10u",
1159                                 devfreq->trans_table[(i * max_state) + j]);
1160                 len += sprintf(buf + len, "%10u\n",
1161                         jiffies_to_msecs(devfreq->time_in_state[i]));
1162         }
1163
1164         len += sprintf(buf + len, "Total transition : %u\n",
1165                                         devfreq->total_trans);
1166         return len;
1167 }
1168 static DEVICE_ATTR_RO(trans_stat);
1169
1170 static struct attribute *devfreq_attrs[] = {
1171         &dev_attr_governor.attr,
1172         &dev_attr_available_governors.attr,
1173         &dev_attr_cur_freq.attr,
1174         &dev_attr_available_frequencies.attr,
1175         &dev_attr_target_freq.attr,
1176         &dev_attr_polling_interval.attr,
1177         &dev_attr_min_freq.attr,
1178         &dev_attr_max_freq.attr,
1179         &dev_attr_trans_stat.attr,
1180         NULL,
1181 };
1182 ATTRIBUTE_GROUPS(devfreq);
1183
1184 static int __init devfreq_init(void)
1185 {
1186         devfreq_class = class_create(THIS_MODULE, "devfreq");
1187         if (IS_ERR(devfreq_class)) {
1188                 pr_err("%s: couldn't create class\n", __FILE__);
1189                 return PTR_ERR(devfreq_class);
1190         }
1191
1192         devfreq_wq = create_freezable_workqueue("devfreq_wq");
1193         if (!devfreq_wq) {
1194                 class_destroy(devfreq_class);
1195                 pr_err("%s: couldn't create workqueue\n", __FILE__);
1196                 return -ENOMEM;
1197         }
1198         devfreq_class->dev_groups = devfreq_groups;
1199
1200         return 0;
1201 }
1202 subsys_initcall(devfreq_init);
1203
1204 /*
1205  * The followings are helper functions for devfreq user device drivers with
1206  * OPP framework.
1207  */
1208
1209 /**
1210  * devfreq_recommended_opp() - Helper function to get proper OPP for the
1211  *                           freq value given to target callback.
1212  * @dev:        The devfreq user device. (parent of devfreq)
1213  * @freq:       The frequency given to target function
1214  * @flags:      Flags handed from devfreq framework.
1215  *
1216  * Locking: This function must be called under rcu_read_lock(). opp is a rcu
1217  * protected pointer. The reason for the same is that the opp pointer which is
1218  * returned will remain valid for use with opp_get_{voltage, freq} only while
1219  * under the locked area. The pointer returned must be used prior to unlocking
1220  * with rcu_read_unlock() to maintain the integrity of the pointer.
1221  */
1222 struct dev_pm_opp *devfreq_recommended_opp(struct device *dev,
1223                                            unsigned long *freq,
1224                                            u32 flags)
1225 {
1226         struct dev_pm_opp *opp;
1227
1228         if (flags & DEVFREQ_FLAG_LEAST_UPPER_BOUND) {
1229                 /* The freq is an upper bound. opp should be lower */
1230                 opp = dev_pm_opp_find_freq_floor(dev, freq);
1231
1232                 /* If not available, use the closest opp */
1233                 if (opp == ERR_PTR(-ERANGE))
1234                         opp = dev_pm_opp_find_freq_ceil(dev, freq);
1235         } else {
1236                 /* The freq is an lower bound. opp should be higher */
1237                 opp = dev_pm_opp_find_freq_ceil(dev, freq);
1238
1239                 /* If not available, use the closest opp */
1240                 if (opp == ERR_PTR(-ERANGE))
1241                         opp = dev_pm_opp_find_freq_floor(dev, freq);
1242         }
1243
1244         return opp;
1245 }
1246 EXPORT_SYMBOL(devfreq_recommended_opp);
1247
1248 /**
1249  * devfreq_register_opp_notifier() - Helper function to get devfreq notified
1250  *                                 for any changes in the OPP availability
1251  *                                 changes
1252  * @dev:        The devfreq user device. (parent of devfreq)
1253  * @devfreq:    The devfreq object.
1254  */
1255 int devfreq_register_opp_notifier(struct device *dev, struct devfreq *devfreq)
1256 {
1257         struct srcu_notifier_head *nh;
1258         int ret = 0;
1259
1260         rcu_read_lock();
1261         nh = dev_pm_opp_get_notifier(dev);
1262         if (IS_ERR(nh))
1263                 ret = PTR_ERR(nh);
1264         rcu_read_unlock();
1265         if (!ret)
1266                 ret = srcu_notifier_chain_register(nh, &devfreq->nb);
1267
1268         return ret;
1269 }
1270 EXPORT_SYMBOL(devfreq_register_opp_notifier);
1271
1272 /**
1273  * devfreq_unregister_opp_notifier() - Helper function to stop getting devfreq
1274  *                                   notified for any changes in the OPP
1275  *                                   availability changes anymore.
1276  * @dev:        The devfreq user device. (parent of devfreq)
1277  * @devfreq:    The devfreq object.
1278  *
1279  * At exit() callback of devfreq_dev_profile, this must be included if
1280  * devfreq_recommended_opp is used.
1281  */
1282 int devfreq_unregister_opp_notifier(struct device *dev, struct devfreq *devfreq)
1283 {
1284         struct srcu_notifier_head *nh;
1285         int ret = 0;
1286
1287         rcu_read_lock();
1288         nh = dev_pm_opp_get_notifier(dev);
1289         if (IS_ERR(nh))
1290                 ret = PTR_ERR(nh);
1291         rcu_read_unlock();
1292         if (!ret)
1293                 ret = srcu_notifier_chain_unregister(nh, &devfreq->nb);
1294
1295         return ret;
1296 }
1297 EXPORT_SYMBOL(devfreq_unregister_opp_notifier);
1298
1299 static void devm_devfreq_opp_release(struct device *dev, void *res)
1300 {
1301         devfreq_unregister_opp_notifier(dev, *(struct devfreq **)res);
1302 }
1303
1304 /**
1305  * devm_ devfreq_register_opp_notifier()
1306  *              - Resource-managed devfreq_register_opp_notifier()
1307  * @dev:        The devfreq user device. (parent of devfreq)
1308  * @devfreq:    The devfreq object.
1309  */
1310 int devm_devfreq_register_opp_notifier(struct device *dev,
1311                                        struct devfreq *devfreq)
1312 {
1313         struct devfreq **ptr;
1314         int ret;
1315
1316         ptr = devres_alloc(devm_devfreq_opp_release, sizeof(*ptr), GFP_KERNEL);
1317         if (!ptr)
1318                 return -ENOMEM;
1319
1320         ret = devfreq_register_opp_notifier(dev, devfreq);
1321         if (ret) {
1322                 devres_free(ptr);
1323                 return ret;
1324         }
1325
1326         *ptr = devfreq;
1327         devres_add(dev, ptr);
1328
1329         return 0;
1330 }
1331 EXPORT_SYMBOL(devm_devfreq_register_opp_notifier);
1332
1333 /**
1334  * devm_devfreq_unregister_opp_notifier()
1335  *              - Resource-managed devfreq_unregister_opp_notifier()
1336  * @dev:        The devfreq user device. (parent of devfreq)
1337  * @devfreq:    The devfreq object.
1338  */
1339 void devm_devfreq_unregister_opp_notifier(struct device *dev,
1340                                          struct devfreq *devfreq)
1341 {
1342         WARN_ON(devres_release(dev, devm_devfreq_opp_release,
1343                                devm_devfreq_dev_match, devfreq));
1344 }
1345 EXPORT_SYMBOL(devm_devfreq_unregister_opp_notifier);
1346
1347 /**
1348  * devfreq_register_notifier() - Register a driver with devfreq
1349  * @devfreq:    The devfreq object.
1350  * @nb:         The notifier block to register.
1351  * @list:       DEVFREQ_TRANSITION_NOTIFIER.
1352  */
1353 int devfreq_register_notifier(struct devfreq *devfreq,
1354                                 struct notifier_block *nb,
1355                                 unsigned int list)
1356 {
1357         int ret = 0;
1358
1359         if (!devfreq)
1360                 return -EINVAL;
1361
1362         switch (list) {
1363         case DEVFREQ_TRANSITION_NOTIFIER:
1364                 ret = srcu_notifier_chain_register(
1365                                 &devfreq->transition_notifier_list, nb);
1366                 break;
1367         default:
1368                 ret = -EINVAL;
1369         }
1370
1371         return ret;
1372 }
1373 EXPORT_SYMBOL(devfreq_register_notifier);
1374
1375 /*
1376  * devfreq_unregister_notifier() - Unregister a driver with devfreq
1377  * @devfreq:    The devfreq object.
1378  * @nb:         The notifier block to be unregistered.
1379  * @list:       DEVFREQ_TRANSITION_NOTIFIER.
1380  */
1381 int devfreq_unregister_notifier(struct devfreq *devfreq,
1382                                 struct notifier_block *nb,
1383                                 unsigned int list)
1384 {
1385         int ret = 0;
1386
1387         if (!devfreq)
1388                 return -EINVAL;
1389
1390         switch (list) {
1391         case DEVFREQ_TRANSITION_NOTIFIER:
1392                 ret = srcu_notifier_chain_unregister(
1393                                 &devfreq->transition_notifier_list, nb);
1394                 break;
1395         default:
1396                 ret = -EINVAL;
1397         }
1398
1399         return ret;
1400 }
1401 EXPORT_SYMBOL(devfreq_unregister_notifier);
1402
1403 struct devfreq_notifier_devres {
1404         struct devfreq *devfreq;
1405         struct notifier_block *nb;
1406         unsigned int list;
1407 };
1408
1409 static void devm_devfreq_notifier_release(struct device *dev, void *res)
1410 {
1411         struct devfreq_notifier_devres *this = res;
1412
1413         devfreq_unregister_notifier(this->devfreq, this->nb, this->list);
1414 }
1415
1416 /**
1417  * devm_devfreq_register_notifier()
1418         - Resource-managed devfreq_register_notifier()
1419  * @dev:        The devfreq user device. (parent of devfreq)
1420  * @devfreq:    The devfreq object.
1421  * @nb:         The notifier block to be unregistered.
1422  * @list:       DEVFREQ_TRANSITION_NOTIFIER.
1423  */
1424 int devm_devfreq_register_notifier(struct device *dev,
1425                                 struct devfreq *devfreq,
1426                                 struct notifier_block *nb,
1427                                 unsigned int list)
1428 {
1429         struct devfreq_notifier_devres *ptr;
1430         int ret;
1431
1432         ptr = devres_alloc(devm_devfreq_notifier_release, sizeof(*ptr),
1433                                 GFP_KERNEL);
1434         if (!ptr)
1435                 return -ENOMEM;
1436
1437         ret = devfreq_register_notifier(devfreq, nb, list);
1438         if (ret) {
1439                 devres_free(ptr);
1440                 return ret;
1441         }
1442
1443         ptr->devfreq = devfreq;
1444         ptr->nb = nb;
1445         ptr->list = list;
1446         devres_add(dev, ptr);
1447
1448         return 0;
1449 }
1450 EXPORT_SYMBOL(devm_devfreq_register_notifier);
1451
1452 /**
1453  * devm_devfreq_unregister_notifier()
1454         - Resource-managed devfreq_unregister_notifier()
1455  * @dev:        The devfreq user device. (parent of devfreq)
1456  * @devfreq:    The devfreq object.
1457  * @nb:         The notifier block to be unregistered.
1458  * @list:       DEVFREQ_TRANSITION_NOTIFIER.
1459  */
1460 void devm_devfreq_unregister_notifier(struct device *dev,
1461                                 struct devfreq *devfreq,
1462                                 struct notifier_block *nb,
1463                                 unsigned int list)
1464 {
1465         WARN_ON(devres_release(dev, devm_devfreq_notifier_release,
1466                                devm_devfreq_dev_match, devfreq));
1467 }
1468 EXPORT_SYMBOL(devm_devfreq_unregister_notifier);