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