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 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         /* Immediately exit if previous_freq is not initialized yet. */
 141         if (!devfreq->previous_freq)
 142                 goto out;
 143
 144         prev_lev = devfreq_get_freq_level(devfreq, devfreq->previous_freq);
 145         if (prev_lev < 0) {
 146                 ret = prev_lev;
 147                 goto out;
 148         }
 149
 150         devfreq->time_in_state[prev_lev] +=
 151                          cur_time - devfreq->last_stat_updated;
 152
 153         lev = devfreq_get_freq_level(devfreq, freq);
 154         if (lev < 0) {
 155                 ret = lev;
 156                 goto out;
 157         }
 158
 159         if (lev != prev_lev) {
 160                 devfreq->trans_table[(prev_lev *
 161                                 devfreq->profile->max_state) + lev]++;
 162                 devfreq->total_trans++;
 163         }
 164
 165 out:
 166         devfreq->last_stat_updated = cur_time;
 167         return ret;
 168 }
 169 EXPORT_SYMBOL(devfreq_update_status);
 170
 171 /**
 172  * find_devfreq_governor() - find devfreq governor from name
 173  * @name:       name of the governor
 174  *
 175  * Search the list of devfreq governors and return the matched
 176  * governor's pointer. devfreq_list_lock should be held by the caller.
 177  */
 178 static struct devfreq_governor *find_devfreq_governor(const char *name)
 179 {
 180         struct devfreq_governor *tmp_governor;
 181
 182         if (IS_ERR_OR_NULL(name)) {
 183                 pr_err("DEVFREQ: %s: Invalid parameters\n", __func__);
 184                 return ERR_PTR(-EINVAL);
 185         }
 186         WARN(!mutex_is_locked(&devfreq_list_lock),
 187              "devfreq_list_lock must be locked.");
 188
 189         list_for_each_entry(tmp_governor, &devfreq_governor_list, node) {
 190                 if (!strncmp(tmp_governor->name, name, DEVFREQ_NAME_LEN))
 191                         return tmp_governor;
 192         }
 193
 194         return ERR_PTR(-ENODEV);
 195 }
 196
 197 static int devfreq_notify_transition(struct devfreq *devfreq,
 198                 struct devfreq_freqs *freqs, unsigned int state)
 199 {
 200         if (!devfreq)
 201                 return -EINVAL;
 202
 203         switch (state) {
 204         case DEVFREQ_PRECHANGE:
 205                 srcu_notifier_call_chain(&devfreq->transition_notifier_list,
 206                                 DEVFREQ_PRECHANGE, freqs);
 207                 break;
 208
 209         case DEVFREQ_POSTCHANGE:
 210                 srcu_notifier_call_chain(&devfreq->transition_notifier_list,
 211                                 DEVFREQ_POSTCHANGE, freqs);
 212                 break;
 213         default:
 214                 return -EINVAL;
 215         }
 216
 217         return 0;
 218 }
 219
 220 /* Load monitoring helper functions for governors use */
 221
 222 /**
 223  * update_devfreq() - Reevaluate the device and configure frequency.
 224  * @devfreq:    the devfreq instance.
 225  *
 226  * Note: Lock devfreq->lock before calling update_devfreq
 227  *       This function is exported for governors.
 228  */
 229 int update_devfreq(struct devfreq *devfreq)
 230 {
 231         struct devfreq_freqs freqs;
 232         unsigned long freq, cur_freq;
 233         int err = 0;
 234         u32 flags = 0;
 235
 236         if (!mutex_is_locked(&devfreq->lock)) {
 237                 WARN(true, "devfreq->lock must be locked by the caller.\n");
 238                 return -EINVAL;
 239         }
 240
 241         if (!devfreq->governor)
 242                 return -EINVAL;
 243
 244         /* Reevaluate the proper frequency */
 245         err = devfreq->governor->get_target_freq(devfreq, &freq);
 246         if (err)
 247                 return err;
 248
 249         /*
 250          * Adjust the frequency with user freq and QoS.
 251          *
 252          * List from the highest priority
 253          * max_freq
 254          * min_freq
 255          */
 256
 257         if (devfreq->min_freq && freq < devfreq->min_freq) {
 258                 freq = devfreq->min_freq;
 259                 flags &= ~DEVFREQ_FLAG_LEAST_UPPER_BOUND; /* Use GLB */
 260         }
 261         if (devfreq->max_freq && freq > devfreq->max_freq) {
 262                 freq = devfreq->max_freq;
 263                 flags |= DEVFREQ_FLAG_LEAST_UPPER_BOUND; /* Use LUB */
 264         }
 265
 266         if (devfreq->profile->get_cur_freq)
 267                 devfreq->profile->get_cur_freq(devfreq->dev.parent, &cur_freq);
 268         else
 269                 cur_freq = devfreq->previous_freq;
 270
 271         freqs.old = cur_freq;
 272         freqs.new = freq;
 273         devfreq_notify_transition(devfreq, &freqs, DEVFREQ_PRECHANGE);
 274
 275         err = devfreq->profile->target(devfreq->dev.parent, &freq, flags);
 276         if (err) {
 277                 freqs.new = cur_freq;
 278                 devfreq_notify_transition(devfreq, &freqs, DEVFREQ_POSTCHANGE);
 279                 return err;
 280         }
 281
 282         freqs.new = freq;
 283         devfreq_notify_transition(devfreq, &freqs, DEVFREQ_POSTCHANGE);
 284
 285         if (devfreq->profile->freq_table)
 286                 if (devfreq_update_status(devfreq, freq))
 287                         dev_err(&devfreq->dev,
 288                                 "Couldn't update frequency transition information.\n");
 289
 290         devfreq->previous_freq = freq;
 291         return err;
 292 }
 293 EXPORT_SYMBOL(update_devfreq);
 294
 295 /**
 296  * devfreq_monitor() - Periodically poll devfreq objects.
 297  * @work:       the work struct used to run devfreq_monitor periodically.
 298  *
 299  */
 300 static void devfreq_monitor(struct work_struct *work)
 301 {
 302         int err;
 303         struct devfreq *devfreq = container_of(work,
 304                                         struct devfreq, work.work);
 305
 306         mutex_lock(&devfreq->lock);
 307         err = update_devfreq(devfreq);
 308         if (err)
 309                 dev_err(&devfreq->dev, "dvfs failed with (%d) error\n", err);
 310
 311         queue_delayed_work(devfreq_wq, &devfreq->work,
 312                                 msecs_to_jiffies(devfreq->profile->polling_ms));
 313         mutex_unlock(&devfreq->lock);
 314 }
 315
 316 /**
 317  * devfreq_monitor_start() - Start load monitoring of devfreq instance
 318  * @devfreq:    the devfreq instance.
 319  *
 320  * Helper function for starting devfreq device load monitoing. By
 321  * default delayed work based monitoring is supported. Function
 322  * to be called from governor in response to DEVFREQ_GOV_START
 323  * event when device is added to devfreq framework.
 324  */
 325 void devfreq_monitor_start(struct devfreq *devfreq)
 326 {
 327         INIT_DEFERRABLE_WORK(&devfreq->work, devfreq_monitor);
 328         if (devfreq->profile->polling_ms)
 329                 queue_delayed_work(devfreq_wq, &devfreq->work,
 330                         msecs_to_jiffies(devfreq->profile->polling_ms));
 331 }
 332 EXPORT_SYMBOL(devfreq_monitor_start);
 333
 334 /**
 335  * devfreq_monitor_stop() - Stop load monitoring of a devfreq instance
 336  * @devfreq:    the devfreq instance.
 337  *
 338  * Helper function to stop devfreq device load monitoing. Function
 339  * to be called from governor in response to DEVFREQ_GOV_STOP
 340  * event when device is removed from devfreq framework.
 341  */
 342 void devfreq_monitor_stop(struct devfreq *devfreq)
 343 {
 344         cancel_delayed_work_sync(&devfreq->work);
 345 }
 346 EXPORT_SYMBOL(devfreq_monitor_stop);
 347
 348 /**
 349  * devfreq_monitor_suspend() - Suspend load monitoring of a devfreq instance
 350  * @devfreq:    the devfreq instance.
 351  *
 352  * Helper function to suspend devfreq device load monitoing. Function
 353  * to be called from governor in response to DEVFREQ_GOV_SUSPEND
 354  * event or when polling interval is set to zero.
 355  *
 356  * Note: Though this function is same as devfreq_monitor_stop(),
 357  * intentionally kept separate to provide hooks for collecting
 358  * transition statistics.
 359  */
 360 void devfreq_monitor_suspend(struct devfreq *devfreq)
 361 {
 362         mutex_lock(&devfreq->lock);
 363         if (devfreq->stop_polling) {
 364                 mutex_unlock(&devfreq->lock);
 365                 return;
 366         }
 367
 368         devfreq_update_status(devfreq, devfreq->previous_freq);
 369         devfreq->stop_polling = true;
 370         mutex_unlock(&devfreq->lock);
 371         cancel_delayed_work_sync(&devfreq->work);
 372 }
 373 EXPORT_SYMBOL(devfreq_monitor_suspend);
 374
 375 /**
 376  * devfreq_monitor_resume() - Resume load monitoring of a devfreq instance
 377  * @devfreq:    the devfreq instance.
 378  *
 379  * Helper function to resume devfreq device load monitoing. Function
 380  * to be called from governor in response to DEVFREQ_GOV_RESUME
 381  * event or when polling interval is set to non-zero.
 382  */
 383 void devfreq_monitor_resume(struct devfreq *devfreq)
 384 {
 385         unsigned long freq;
 386
 387         mutex_lock(&devfreq->lock);
 388         if (!devfreq->stop_polling)
 389                 goto out;
 390
 391         if (!delayed_work_pending(&devfreq->work) &&
 392                         devfreq->profile->polling_ms)
 393                 queue_delayed_work(devfreq_wq, &devfreq->work,
 394                         msecs_to_jiffies(devfreq->profile->polling_ms));
 395
 396         devfreq->last_stat_updated = jiffies;
 397         devfreq->stop_polling = false;
 398
 399         if (devfreq->profile->get_cur_freq &&
 400                 !devfreq->profile->get_cur_freq(devfreq->dev.parent, &freq))
 401                 devfreq->previous_freq = freq;
 402
 403 out:
 404         mutex_unlock(&devfreq->lock);
 405 }
 406 EXPORT_SYMBOL(devfreq_monitor_resume);
 407
 408 /**
 409  * devfreq_interval_update() - Update device devfreq monitoring interval
 410  * @devfreq:    the devfreq instance.
 411  * @delay:      new polling interval to be set.
 412  *
 413  * Helper function to set new load monitoring polling interval. Function
 414  * to be called from governor in response to DEVFREQ_GOV_INTERVAL event.
 415  */
 416 void devfreq_interval_update(struct devfreq *devfreq, unsigned int *delay)
 417 {
 418         unsigned int cur_delay = devfreq->profile->polling_ms;
 419         unsigned int new_delay = *delay;
 420
 421         mutex_lock(&devfreq->lock);
 422         devfreq->profile->polling_ms = new_delay;
 423
 424         if (devfreq->stop_polling)
 425                 goto out;
 426
 427         /* if new delay is zero, stop polling */
 428         if (!new_delay) {
 429                 mutex_unlock(&devfreq->lock);
 430                 cancel_delayed_work_sync(&devfreq->work);
 431                 return;
 432         }
 433
 434         /* if current delay is zero, start polling with new delay */
 435         if (!cur_delay) {
 436                 queue_delayed_work(devfreq_wq, &devfreq->work,
 437                         msecs_to_jiffies(devfreq->profile->polling_ms));
 438                 goto out;
 439         }
 440
 441         /* if current delay is greater than new delay, restart polling */
 442         if (cur_delay > new_delay) {
 443                 mutex_unlock(&devfreq->lock);
 444                 cancel_delayed_work_sync(&devfreq->work);
 445                 mutex_lock(&devfreq->lock);
 446                 if (!devfreq->stop_polling)
 447                         queue_delayed_work(devfreq_wq, &devfreq->work,
 448                               msecs_to_jiffies(devfreq->profile->polling_ms));
 449         }
 450 out:
 451         mutex_unlock(&devfreq->lock);
 452 }
 453 EXPORT_SYMBOL(devfreq_interval_update);
 454
 455 /**
 456  * devfreq_notifier_call() - Notify that the device frequency requirements
 457  *                         has been changed out of devfreq framework.
 458  * @nb:         the notifier_block (supposed to be devfreq->nb)
 459  * @type:       not used
 460  * @devp:       not used
 461  *
 462  * Called by a notifier that uses devfreq->nb.
 463  */
 464 static int devfreq_notifier_call(struct notifier_block *nb, unsigned long type,
 465                                  void *devp)
 466 {
 467         struct devfreq *devfreq = container_of(nb, struct devfreq, nb);
 468         int ret;
 469
 470         mutex_lock(&devfreq->lock);
 471         ret = update_devfreq(devfreq);
 472         mutex_unlock(&devfreq->lock);
 473
 474         return ret;
 475 }
 476
 477 /**
 478  * _remove_devfreq() - Remove devfreq from the list and release its resources.
 479  * @devfreq:    the devfreq struct
 480  */
 481 static void _remove_devfreq(struct devfreq *devfreq)
 482 {
 483         mutex_lock(&devfreq_list_lock);
 484         if (IS_ERR(find_device_devfreq(devfreq->dev.parent))) {
 485                 mutex_unlock(&devfreq_list_lock);
 486                 dev_warn(&devfreq->dev, "releasing devfreq which doesn't exist\n");
 487                 return;
 488         }
 489         list_del(&devfreq->node);
 490         mutex_unlock(&devfreq_list_lock);
 491
 492         if (devfreq->governor)
 493                 devfreq->governor->event_handler(devfreq,
 494                                                  DEVFREQ_GOV_STOP, NULL);
 495
 496         if (devfreq->profile->exit)
 497                 devfreq->profile->exit(devfreq->dev.parent);
 498
 499         mutex_destroy(&devfreq->lock);
 500         kfree(devfreq);
 501 }
 502
 503 /**
 504  * devfreq_dev_release() - Callback for struct device to release the device.
 505  * @dev:        the devfreq device
 506  *
 507  * This calls _remove_devfreq() if _remove_devfreq() is not called.
 508  */
 509 static void devfreq_dev_release(struct device *dev)
 510 {
 511         struct devfreq *devfreq = to_devfreq(dev);
 512
 513         _remove_devfreq(devfreq);
 514 }
 515
 516 /**
 517  * devfreq_add_device() - Add devfreq feature to the device
 518  * @dev:        the device to add devfreq feature.
 519  * @profile:    device-specific profile to run devfreq.
 520  * @governor_name:      name of the policy to choose frequency.
 521  * @data:       private data for the governor. The devfreq framework does not
 522  *              touch this value.
 523  */
 524 struct devfreq *devfreq_add_device(struct device *dev,
 525                                    struct devfreq_dev_profile *profile,
 526                                    const char *governor_name,
 527                                    void *data)
 528 {
 529         struct devfreq *devfreq;
 530         struct devfreq_governor *governor;
 531         int err = 0;
 532
 533         if (!dev || !profile || !governor_name) {
 534                 dev_err(dev, "%s: Invalid parameters.\n", __func__);
 535                 return ERR_PTR(-EINVAL);
 536         }
 537
 538         mutex_lock(&devfreq_list_lock);
 539         devfreq = find_device_devfreq(dev);
 540         mutex_unlock(&devfreq_list_lock);
 541         if (!IS_ERR(devfreq)) {
 542                 dev_err(dev, "%s: Unable to create devfreq for the device.\n",
 543                         __func__);
 544                 err = -EINVAL;
 545                 goto err_out;
 546         }
 547
 548         devfreq = kzalloc(sizeof(struct devfreq), GFP_KERNEL);
 549         if (!devfreq) {
 550                 err = -ENOMEM;
 551                 goto err_out;
 552         }
 553
 554         mutex_init(&devfreq->lock);
 555         mutex_lock(&devfreq->lock);
 556         devfreq->dev.parent = dev;
 557         devfreq->dev.class = devfreq_class;
 558         devfreq->dev.release = devfreq_dev_release;
 559         devfreq->profile = profile;
 560         strncpy(devfreq->governor_name, governor_name, DEVFREQ_NAME_LEN);
 561         devfreq->previous_freq = profile->initial_freq;
 562         devfreq->last_status.current_frequency = profile->initial_freq;
 563         devfreq->data = data;
 564         devfreq->nb.notifier_call = devfreq_notifier_call;
 565
 566         if (!devfreq->profile->max_state && !devfreq->profile->freq_table) {
 567                 mutex_unlock(&devfreq->lock);
 568                 devfreq_set_freq_table(devfreq);
 569                 mutex_lock(&devfreq->lock);
 570         }
 571
 572         dev_set_name(&devfreq->dev, "%s", dev_name(dev));
 573         err = device_register(&devfreq->dev);
 574         if (err) {
 575                 mutex_unlock(&devfreq->lock);
 576                 goto err_out;
 577         }
 578
 579         devfreq->trans_table =  devm_kzalloc(&devfreq->dev,
 580                                                 sizeof(unsigned int) *
 581                                                 devfreq->profile->max_state *
 582                                                 devfreq->profile->max_state,
 583                                                 GFP_KERNEL);
 584         devfreq->time_in_state = devm_kzalloc(&devfreq->dev,
 585                                                 sizeof(unsigned long) *
 586                                                 devfreq->profile->max_state,
 587                                                 GFP_KERNEL);
 588         devfreq->last_stat_updated = jiffies;
 589
 590         srcu_init_notifier_head(&devfreq->transition_notifier_list);
 591
 592         mutex_unlock(&devfreq->lock);
 593
 594         mutex_lock(&devfreq_list_lock);
 595         list_add(&devfreq->node, &devfreq_list);
 596
 597         governor = find_devfreq_governor(devfreq->governor_name);
 598         if (IS_ERR(governor)) {
 599                 dev_err(dev, "%s: Unable to find governor for the device\n",
 600                         __func__);
 601                 err = PTR_ERR(governor);
 602                 goto err_init;
 603         }
 604
 605         devfreq->governor = governor;
 606         err = devfreq->governor->event_handler(devfreq, DEVFREQ_GOV_START,
 607                                                 NULL);
 608         if (err) {
 609                 dev_err(dev, "%s: Unable to start governor for the device\n",
 610                         __func__);
 611                 goto err_init;
 612         }
 613         mutex_unlock(&devfreq_list_lock);
 614
 615         return devfreq;
 616
 617 err_init:
 618         list_del(&devfreq->node);
 619         mutex_unlock(&devfreq_list_lock);
 620
 621         device_unregister(&devfreq->dev);
 622 err_out:
 623         return ERR_PTR(err);
 624 }
 625 EXPORT_SYMBOL(devfreq_add_device);
 626
 627 /**
 628  * devfreq_remove_device() - Remove devfreq feature from a device.
 629  * @devfreq:    the devfreq instance to be removed
 630  *
 631  * The opposite of devfreq_add_device().
 632  */
 633 int devfreq_remove_device(struct devfreq *devfreq)
 634 {
 635         if (!devfreq)
 636                 return -EINVAL;
 637
 638         device_unregister(&devfreq->dev);
 639
 640         return 0;
 641 }
 642 EXPORT_SYMBOL(devfreq_remove_device);
 643
 644 static int devm_devfreq_dev_match(struct device *dev, void *res, void *data)
 645 {
 646         struct devfreq **r = res;
 647
 648         if (WARN_ON(!r || !*r))
 649                 return 0;
 650
 651         return *r == data;
 652 }
 653
 654 static void devm_devfreq_dev_release(struct device *dev, void *res)
 655 {
 656         devfreq_remove_device(*(struct devfreq **)res);
 657 }
 658
 659 /**
 660  * devm_devfreq_add_device() - Resource-managed devfreq_add_device()
 661  * @dev:        the device to add devfreq feature.
 662  * @profile:    device-specific profile to run devfreq.
 663  * @governor_name:      name of the policy to choose frequency.
 664  * @data:       private data for the governor. The devfreq framework does not
 665  *              touch this value.
 666  *
 667  * This function manages automatically the memory of devfreq device using device
 668  * resource management and simplify the free operation for memory of devfreq
 669  * device.
 670  */
 671 struct devfreq *devm_devfreq_add_device(struct device *dev,
 672                                         struct devfreq_dev_profile *profile,
 673                                         const char *governor_name,
 674                                         void *data)
 675 {
 676         struct devfreq **ptr, *devfreq;
 677
 678         ptr = devres_alloc(devm_devfreq_dev_release, sizeof(*ptr), GFP_KERNEL);
 679         if (!ptr)
 680                 return ERR_PTR(-ENOMEM);
 681
 682         devfreq = devfreq_add_device(dev, profile, governor_name, data);
 683         if (IS_ERR(devfreq)) {
 684                 devres_free(ptr);
 685                 return ERR_PTR(-ENOMEM);
 686         }
 687
 688         *ptr = devfreq;
 689         devres_add(dev, ptr);
 690
 691         return devfreq;
 692 }
 693 EXPORT_SYMBOL(devm_devfreq_add_device);
 694
 695 #ifdef CONFIG_OF
 696 /*
 697  * devfreq_get_devfreq_by_phandle - Get the devfreq device from devicetree
 698  * @dev - instance to the given device
 699  * @index - index into list of devfreq
 700  *
 701  * return the instance of devfreq device
 702  */
 703 struct devfreq *devfreq_get_devfreq_by_phandle(struct device *dev, int index)
 704 {
 705         struct device_node *node;
 706         struct devfreq *devfreq;
 707
 708         if (!dev)
 709                 return ERR_PTR(-EINVAL);
 710
 711         if (!dev->of_node)
 712                 return ERR_PTR(-EINVAL);
 713
 714         node = of_parse_phandle(dev->of_node, "devfreq", index);
 715         if (!node)
 716                 return ERR_PTR(-ENODEV);
 717
 718         mutex_lock(&devfreq_list_lock);
 719         list_for_each_entry(devfreq, &devfreq_list, node) {
 720                 if (devfreq->dev.parent
 721                         && devfreq->dev.parent->of_node == node) {
 722                         mutex_unlock(&devfreq_list_lock);
 723                         of_node_put(node);
 724                         return devfreq;
 725                 }
 726         }
 727         mutex_unlock(&devfreq_list_lock);
 728         of_node_put(node);
 729
 730         return ERR_PTR(-EPROBE_DEFER);
 731 }
 732 #else
 733 struct devfreq *devfreq_get_devfreq_by_phandle(struct device *dev, int index)
 734 {
 735         return ERR_PTR(-ENODEV);
 736 }
 737 #endif /* CONFIG_OF */
 738 EXPORT_SYMBOL_GPL(devfreq_get_devfreq_by_phandle);
 739
 740 /**
 741  * devm_devfreq_remove_device() - Resource-managed devfreq_remove_device()
 742  * @dev:        the device to add devfreq feature.
 743  * @devfreq:    the devfreq instance to be removed
 744  */
 745 void devm_devfreq_remove_device(struct device *dev, struct devfreq *devfreq)
 746 {
 747         WARN_ON(devres_release(dev, devm_devfreq_dev_release,
 748                                devm_devfreq_dev_match, devfreq));
 749 }
 750 EXPORT_SYMBOL(devm_devfreq_remove_device);
 751
 752 /**
 753  * devfreq_suspend_device() - Suspend devfreq of a device.
 754  * @devfreq: the devfreq instance to be suspended
 755  *
 756  * This function is intended to be called by the pm callbacks
 757  * (e.g., runtime_suspend, suspend) of the device driver that
 758  * holds the devfreq.
 759  */
 760 int devfreq_suspend_device(struct devfreq *devfreq)
 761 {
 762         if (!devfreq)
 763                 return -EINVAL;
 764
 765         if (!devfreq->governor)
 766                 return 0;
 767
 768         return devfreq->governor->event_handler(devfreq,
 769                                 DEVFREQ_GOV_SUSPEND, NULL);
 770 }
 771 EXPORT_SYMBOL(devfreq_suspend_device);
 772
 773 /**
 774  * devfreq_resume_device() - Resume devfreq of a device.
 775  * @devfreq: the devfreq instance to be resumed
 776  *
 777  * This function is intended to be called by the pm callbacks
 778  * (e.g., runtime_resume, resume) of the device driver that
 779  * holds the devfreq.
 780  */
 781 int devfreq_resume_device(struct devfreq *devfreq)
 782 {
 783         if (!devfreq)
 784                 return -EINVAL;
 785
 786         if (!devfreq->governor)
 787                 return 0;
 788
 789         return devfreq->governor->event_handler(devfreq,
 790                                 DEVFREQ_GOV_RESUME, NULL);
 791 }
 792 EXPORT_SYMBOL(devfreq_resume_device);
 793
 794 /**
 795  * devfreq_add_governor() - Add devfreq governor
 796  * @governor:   the devfreq governor to be added
 797  */
 798 int devfreq_add_governor(struct devfreq_governor *governor)
 799 {
 800         struct devfreq_governor *g;
 801         struct devfreq *devfreq;
 802         int err = 0;
 803
 804         if (!governor) {
 805                 pr_err("%s: Invalid parameters.\n", __func__);
 806                 return -EINVAL;
 807         }
 808
 809         mutex_lock(&devfreq_list_lock);
 810         g = find_devfreq_governor(governor->name);
 811         if (!IS_ERR(g)) {
 812                 pr_err("%s: governor %s already registered\n", __func__,
 813                        g->name);
 814                 err = -EINVAL;
 815                 goto err_out;
 816         }
 817
 818         list_add(&governor->node, &devfreq_governor_list);
 819
 820         list_for_each_entry(devfreq, &devfreq_list, node) {
 821                 int ret = 0;
 822                 struct device *dev = devfreq->dev.parent;
 823
 824                 if (!strncmp(devfreq->governor_name, governor->name,
 825                              DEVFREQ_NAME_LEN)) {
 826                         /* The following should never occur */
 827                         if (devfreq->governor) {
 828                                 dev_warn(dev,
 829                                          "%s: Governor %s already present\n",
 830                                          __func__, devfreq->governor->name);
 831                                 ret = devfreq->governor->event_handler(devfreq,
 832                                                         DEVFREQ_GOV_STOP, NULL);
 833                                 if (ret) {
 834                                         dev_warn(dev,
 835                                                  "%s: Governor %s stop = %d\n",
 836                                                  __func__,
 837                                                  devfreq->governor->name, ret);
 838                                 }
 839                                 /* Fall through */
 840                         }
 841                         devfreq->governor = governor;
 842                         ret = devfreq->governor->event_handler(devfreq,
 843                                                 DEVFREQ_GOV_START, NULL);
 844                         if (ret) {
 845                                 dev_warn(dev, "%s: Governor %s start=%d\n",
 846                                          __func__, devfreq->governor->name,
 847                                          ret);
 848                         }
 849                 }
 850         }
 851
 852 err_out:
 853         mutex_unlock(&devfreq_list_lock);
 854
 855         return err;
 856 }
 857 EXPORT_SYMBOL(devfreq_add_governor);
 858
 859 /**
 860  * devfreq_remove_governor() - Remove devfreq feature from a device.
 861  * @governor:   the devfreq governor to be removed
 862  */
 863 int devfreq_remove_governor(struct devfreq_governor *governor)
 864 {
 865         struct devfreq_governor *g;
 866         struct devfreq *devfreq;
 867         int err = 0;
 868
 869         if (!governor) {
 870                 pr_err("%s: Invalid parameters.\n", __func__);
 871                 return -EINVAL;
 872         }
 873
 874         mutex_lock(&devfreq_list_lock);
 875         g = find_devfreq_governor(governor->name);
 876         if (IS_ERR(g)) {
 877                 pr_err("%s: governor %s not registered\n", __func__,
 878                        governor->name);
 879                 err = PTR_ERR(g);
 880                 goto err_out;
 881         }
 882         list_for_each_entry(devfreq, &devfreq_list, node) {
 883                 int ret;
 884                 struct device *dev = devfreq->dev.parent;
 885
 886                 if (!strncmp(devfreq->governor_name, governor->name,
 887                              DEVFREQ_NAME_LEN)) {
 888                         /* we should have a devfreq governor! */
 889                         if (!devfreq->governor) {
 890                                 dev_warn(dev, "%s: Governor %s NOT present\n",
 891                                          __func__, governor->name);
 892                                 continue;
 893                                 /* Fall through */
 894                         }
 895                         ret = devfreq->governor->event_handler(devfreq,
 896                                                 DEVFREQ_GOV_STOP, NULL);
 897                         if (ret) {
 898                                 dev_warn(dev, "%s: Governor %s stop=%d\n",
 899                                          __func__, devfreq->governor->name,
 900                                          ret);
 901                         }
 902                         devfreq->governor = NULL;
 903                 }
 904         }
 905
 906         list_del(&governor->node);
 907 err_out:
 908         mutex_unlock(&devfreq_list_lock);
 909
 910         return err;
 911 }
 912 EXPORT_SYMBOL(devfreq_remove_governor);
 913
 914 static ssize_t governor_show(struct device *dev,
 915                              struct device_attribute *attr, char *buf)
 916 {
 917         if (!to_devfreq(dev)->governor)
 918                 return -EINVAL;
 919
 920         return sprintf(buf, "%s\n", to_devfreq(dev)->governor->name);
 921 }
 922
 923 static ssize_t governor_store(struct device *dev, struct device_attribute *attr,
 924                               const char *buf, size_t count)
 925 {
 926         struct devfreq *df = to_devfreq(dev);
 927         int ret;
 928         char str_governor[DEVFREQ_NAME_LEN + 1];
 929         struct devfreq_governor *governor;
 930
 931         ret = sscanf(buf, "%" __stringify(DEVFREQ_NAME_LEN) "s", str_governor);
 932         if (ret != 1)
 933                 return -EINVAL;
 934
 935         mutex_lock(&devfreq_list_lock);
 936         governor = find_devfreq_governor(str_governor);
 937         if (IS_ERR(governor)) {
 938                 ret = PTR_ERR(governor);
 939                 goto out;
 940         }
 941         if (df->governor == governor) {
 942                 ret = 0;
 943                 goto out;
 944         } else if (df->governor->immutable || governor->immutable) {
 945                 ret = -EINVAL;
 946                 goto out;
 947         }
 948
 949         if (df->governor) {
 950                 ret = df->governor->event_handler(df, DEVFREQ_GOV_STOP, NULL);
 951                 if (ret) {
 952                         dev_warn(dev, "%s: Governor %s not stopped(%d)\n",
 953                                  __func__, df->governor->name, ret);
 954                         goto out;
 955                 }
 956         }
 957         df->governor = governor;
 958         strncpy(df->governor_name, governor->name, DEVFREQ_NAME_LEN);
 959         ret = df->governor->event_handler(df, DEVFREQ_GOV_START, NULL);
 960         if (ret)
 961                 dev_warn(dev, "%s: Governor %s not started(%d)\n",
 962                          __func__, df->governor->name, ret);
 963 out:
 964         mutex_unlock(&devfreq_list_lock);
 965
 966         if (!ret)
 967                 ret = count;
 968         return ret;
 969 }
 970 static DEVICE_ATTR_RW(governor);
 971
 972 static ssize_t available_governors_show(struct device *d,
 973                                         struct device_attribute *attr,
 974                                         char *buf)
 975 {
 976         struct devfreq *df = to_devfreq(d);
 977         ssize_t count = 0;
 978
 979         mutex_lock(&devfreq_list_lock);
 980
 981         /*
 982          * The devfreq with immutable governor (e.g., passive) shows
 983          * only own governor.
 984          */
 985         if (df->governor->immutable) {
 986                 count = scnprintf(&buf[count], DEVFREQ_NAME_LEN,
 987                                    "%s ", df->governor_name);
 988         /*
 989          * The devfreq device shows the registered governor except for
 990          * immutable governors such as passive governor .
 991          */
 992         } else {
 993                 struct devfreq_governor *governor;
 994
 995                 list_for_each_entry(governor, &devfreq_governor_list, node) {
 996                         if (governor->immutable)
 997                                 continue;
 998                         count += scnprintf(&buf[count], (PAGE_SIZE - count - 2),
 999                                            "%s ", governor->name);
1000                 }
1001         }
1002
1003         mutex_unlock(&devfreq_list_lock);
1004
1005         /* Truncate the trailing space */
1006         if (count)
1007                 count--;
1008
1009         count += sprintf(&buf[count], "\n");
1010
1011         return count;
1012 }
1013 static DEVICE_ATTR_RO(available_governors);
1014
1015 static ssize_t cur_freq_show(struct device *dev, struct device_attribute *attr,
1016                              char *buf)
1017 {
1018         unsigned long freq;
1019         struct devfreq *devfreq = to_devfreq(dev);
1020
1021         if (devfreq->profile->get_cur_freq &&
1022                 !devfreq->profile->get_cur_freq(devfreq->dev.parent, &freq))
1023                 return sprintf(buf, "%lu\n", freq);
1024
1025         return sprintf(buf, "%lu\n", devfreq->previous_freq);
1026 }
1027 static DEVICE_ATTR_RO(cur_freq);
1028
1029 static ssize_t target_freq_show(struct device *dev,
1030                                 struct device_attribute *attr, char *buf)
1031 {
1032         return sprintf(buf, "%lu\n", to_devfreq(dev)->previous_freq);
1033 }
1034 static DEVICE_ATTR_RO(target_freq);
1035
1036 static ssize_t polling_interval_show(struct device *dev,
1037                                      struct device_attribute *attr, char *buf)
1038 {
1039         return sprintf(buf, "%d\n", to_devfreq(dev)->profile->polling_ms);
1040 }
1041
1042 static ssize_t polling_interval_store(struct device *dev,
1043                                       struct device_attribute *attr,
1044                                       const char *buf, size_t count)
1045 {
1046         struct devfreq *df = to_devfreq(dev);
1047         unsigned int value;
1048         int ret;
1049
1050         if (!df->governor)
1051                 return -EINVAL;
1052
1053         ret = sscanf(buf, "%u", &value);
1054         if (ret != 1)
1055                 return -EINVAL;
1056
1057         df->governor->event_handler(df, DEVFREQ_GOV_INTERVAL, &value);
1058         ret = count;
1059
1060         return ret;
1061 }
1062 static DEVICE_ATTR_RW(polling_interval);
1063
1064 static ssize_t min_freq_store(struct device *dev, struct device_attribute *attr,
1065                               const char *buf, size_t count)
1066 {
1067         struct devfreq *df = to_devfreq(dev);
1068         unsigned long value;
1069         int ret;
1070         unsigned long max;
1071
1072         ret = sscanf(buf, "%lu", &value);
1073         if (ret != 1)
1074                 return -EINVAL;
1075
1076         mutex_lock(&df->lock);
1077         max = df->max_freq;
1078         if (value && max && value > max) {
1079                 ret = -EINVAL;
1080                 goto unlock;
1081         }
1082
1083         df->min_freq = value;
1084         update_devfreq(df);
1085         ret = count;
1086 unlock:
1087         mutex_unlock(&df->lock);
1088         return ret;
1089 }
1090
1091 static ssize_t max_freq_store(struct device *dev, struct device_attribute *attr,
1092                               const char *buf, size_t count)
1093 {
1094         struct devfreq *df = to_devfreq(dev);
1095         unsigned long value;
1096         int ret;
1097         unsigned long min;
1098
1099         ret = sscanf(buf, "%lu", &value);
1100         if (ret != 1)
1101                 return -EINVAL;
1102
1103         mutex_lock(&df->lock);
1104         min = df->min_freq;
1105         if (value && min && value < min) {
1106                 ret = -EINVAL;
1107                 goto unlock;
1108         }
1109
1110         df->max_freq = value;
1111         update_devfreq(df);
1112         ret = count;
1113 unlock:
1114         mutex_unlock(&df->lock);
1115         return ret;
1116 }
1117
1118 #define show_one(name)                                          \
1119 static ssize_t name##_show                                      \
1120 (struct device *dev, struct device_attribute *attr, char *buf)  \
1121 {                                                               \
1122         return sprintf(buf, "%lu\n", to_devfreq(dev)->name);    \
1123 }
1124 show_one(min_freq);
1125 show_one(max_freq);
1126
1127 static DEVICE_ATTR_RW(min_freq);
1128 static DEVICE_ATTR_RW(max_freq);
1129
1130 static ssize_t available_frequencies_show(struct device *d,
1131                                           struct device_attribute *attr,
1132                                           char *buf)
1133 {
1134         struct devfreq *df = to_devfreq(d);
1135         struct device *dev = df->dev.parent;
1136         struct dev_pm_opp *opp;
1137         ssize_t count = 0;
1138         unsigned long freq = 0;
1139
1140         rcu_read_lock();
1141         do {
1142                 opp = dev_pm_opp_find_freq_ceil(dev, &freq);
1143                 if (IS_ERR(opp))
1144                         break;
1145
1146                 count += scnprintf(&buf[count], (PAGE_SIZE - count - 2),
1147                                    "%lu ", freq);
1148                 freq++;
1149         } while (1);
1150         rcu_read_unlock();
1151
1152         /* Truncate the trailing space */
1153         if (count)
1154                 count--;
1155
1156         count += sprintf(&buf[count], "\n");
1157
1158         return count;
1159 }
1160 static DEVICE_ATTR_RO(available_frequencies);
1161
1162 static ssize_t trans_stat_show(struct device *dev,
1163                                struct device_attribute *attr, char *buf)
1164 {
1165         struct devfreq *devfreq = to_devfreq(dev);
1166         ssize_t len;
1167         int i, j;
1168         unsigned int max_state = devfreq->profile->max_state;
1169
1170         if (!devfreq->stop_polling &&
1171                         devfreq_update_status(devfreq, devfreq->previous_freq))
1172                 return 0;
1173         if (max_state == 0)
1174                 return sprintf(buf, "Not Supported.\n");
1175
1176         len = sprintf(buf, "     From  :   To\n");
1177         len += sprintf(buf + len, "           :");
1178         for (i = 0; i < max_state; i++)
1179                 len += sprintf(buf + len, "%10lu",
1180                                 devfreq->profile->freq_table[i]);
1181
1182         len += sprintf(buf + len, "   time(ms)\n");
1183
1184         for (i = 0; i < max_state; i++) {
1185                 if (devfreq->profile->freq_table[i]
1186                                         == devfreq->previous_freq) {
1187                         len += sprintf(buf + len, "*");
1188                 } else {
1189                         len += sprintf(buf + len, " ");
1190                 }
1191                 len += sprintf(buf + len, "%10lu:",
1192                                 devfreq->profile->freq_table[i]);
1193                 for (j = 0; j < max_state; j++)
1194                         len += sprintf(buf + len, "%10u",
1195                                 devfreq->trans_table[(i * max_state) + j]);
1196                 len += sprintf(buf + len, "%10u\n",
1197                         jiffies_to_msecs(devfreq->time_in_state[i]));
1198         }
1199
1200         len += sprintf(buf + len, "Total transition : %u\n",
1201                                         devfreq->total_trans);
1202         return len;
1203 }
1204 static DEVICE_ATTR_RO(trans_stat);
1205
1206 static struct attribute *devfreq_attrs[] = {
1207         &dev_attr_governor.attr,
1208         &dev_attr_available_governors.attr,
1209         &dev_attr_cur_freq.attr,
1210         &dev_attr_available_frequencies.attr,
1211         &dev_attr_target_freq.attr,
1212         &dev_attr_polling_interval.attr,
1213         &dev_attr_min_freq.attr,
1214         &dev_attr_max_freq.attr,
1215         &dev_attr_trans_stat.attr,
1216         NULL,
1217 };
1218 ATTRIBUTE_GROUPS(devfreq);
1219
1220 static int __init devfreq_init(void)
1221 {
1222         devfreq_class = class_create(THIS_MODULE, "devfreq");
1223         if (IS_ERR(devfreq_class)) {
1224                 pr_err("%s: couldn't create class\n", __FILE__);
1225                 return PTR_ERR(devfreq_class);
1226         }
1227
1228         devfreq_wq = create_freezable_workqueue("devfreq_wq");
1229         if (!devfreq_wq) {
1230                 class_destroy(devfreq_class);
1231                 pr_err("%s: couldn't create workqueue\n", __FILE__);
1232                 return -ENOMEM;
1233         }
1234         devfreq_class->dev_groups = devfreq_groups;
1235
1236         return 0;
1237 }
1238 subsys_initcall(devfreq_init);
1239
1240 /*
1241  * The followings are helper functions for devfreq user device drivers with
1242  * OPP framework.
1243  */
1244
1245 /**
1246  * devfreq_recommended_opp() - Helper function to get proper OPP for the
1247  *                           freq value given to target callback.
1248  * @dev:        The devfreq user device. (parent of devfreq)
1249  * @freq:       The frequency given to target function
1250  * @flags:      Flags handed from devfreq framework.
1251  *
1252  * Locking: This function must be called under rcu_read_lock(). opp is a rcu
1253  * protected pointer. The reason for the same is that the opp pointer which is
1254  * returned will remain valid for use with opp_get_{voltage, freq} only while
1255  * under the locked area. The pointer returned must be used prior to unlocking
1256  * with rcu_read_unlock() to maintain the integrity of the pointer.
1257  */
1258 struct dev_pm_opp *devfreq_recommended_opp(struct device *dev,
1259                                            unsigned long *freq,
1260                                            u32 flags)
1261 {
1262         struct dev_pm_opp *opp;
1263
1264         if (flags & DEVFREQ_FLAG_LEAST_UPPER_BOUND) {
1265                 /* The freq is an upper bound. opp should be lower */
1266                 opp = dev_pm_opp_find_freq_floor(dev, freq);
1267
1268                 /* If not available, use the closest opp */
1269                 if (opp == ERR_PTR(-ERANGE))
1270                         opp = dev_pm_opp_find_freq_ceil(dev, freq);
1271         } else {
1272                 /* The freq is an lower bound. opp should be higher */
1273                 opp = dev_pm_opp_find_freq_ceil(dev, freq);
1274
1275                 /* If not available, use the closest opp */
1276                 if (opp == ERR_PTR(-ERANGE))
1277                         opp = dev_pm_opp_find_freq_floor(dev, freq);
1278         }
1279
1280         return opp;
1281 }
1282 EXPORT_SYMBOL(devfreq_recommended_opp);
1283
1284 /**
1285  * devfreq_register_opp_notifier() - Helper function to get devfreq notified
1286  *                                 for any changes in the OPP availability
1287  *                                 changes
1288  * @dev:        The devfreq user device. (parent of devfreq)
1289  * @devfreq:    The devfreq object.
1290  */
1291 int devfreq_register_opp_notifier(struct device *dev, struct devfreq *devfreq)
1292 {
1293         struct srcu_notifier_head *nh;
1294         int ret = 0;
1295
1296         rcu_read_lock();
1297         nh = dev_pm_opp_get_notifier(dev);
1298         if (IS_ERR(nh))
1299                 ret = PTR_ERR(nh);
1300         rcu_read_unlock();
1301         if (!ret)
1302                 ret = srcu_notifier_chain_register(nh, &devfreq->nb);
1303
1304         return ret;
1305 }
1306 EXPORT_SYMBOL(devfreq_register_opp_notifier);
1307
1308 /**
1309  * devfreq_unregister_opp_notifier() - Helper function to stop getting devfreq
1310  *                                   notified for any changes in the OPP
1311  *                                   availability changes anymore.
1312  * @dev:        The devfreq user device. (parent of devfreq)
1313  * @devfreq:    The devfreq object.
1314  *
1315  * At exit() callback of devfreq_dev_profile, this must be included if
1316  * devfreq_recommended_opp is used.
1317  */
1318 int devfreq_unregister_opp_notifier(struct device *dev, struct devfreq *devfreq)
1319 {
1320         struct srcu_notifier_head *nh;
1321         int ret = 0;
1322
1323         rcu_read_lock();
1324         nh = dev_pm_opp_get_notifier(dev);
1325         if (IS_ERR(nh))
1326                 ret = PTR_ERR(nh);
1327         rcu_read_unlock();
1328         if (!ret)
1329                 ret = srcu_notifier_chain_unregister(nh, &devfreq->nb);
1330
1331         return ret;
1332 }
1333 EXPORT_SYMBOL(devfreq_unregister_opp_notifier);
1334
1335 static void devm_devfreq_opp_release(struct device *dev, void *res)
1336 {
1337         devfreq_unregister_opp_notifier(dev, *(struct devfreq **)res);
1338 }
1339
1340 /**
1341  * devm_ devfreq_register_opp_notifier()
1342  *              - Resource-managed devfreq_register_opp_notifier()
1343  * @dev:        The devfreq user device. (parent of devfreq)
1344  * @devfreq:    The devfreq object.
1345  */
1346 int devm_devfreq_register_opp_notifier(struct device *dev,
1347                                        struct devfreq *devfreq)
1348 {
1349         struct devfreq **ptr;
1350         int ret;
1351
1352         ptr = devres_alloc(devm_devfreq_opp_release, sizeof(*ptr), GFP_KERNEL);
1353         if (!ptr)
1354                 return -ENOMEM;
1355
1356         ret = devfreq_register_opp_notifier(dev, devfreq);
1357         if (ret) {
1358                 devres_free(ptr);
1359                 return ret;
1360         }
1361
1362         *ptr = devfreq;
1363         devres_add(dev, ptr);
1364
1365         return 0;
1366 }
1367 EXPORT_SYMBOL(devm_devfreq_register_opp_notifier);
1368
1369 /**
1370  * devm_devfreq_unregister_opp_notifier()
1371  *              - Resource-managed devfreq_unregister_opp_notifier()
1372  * @dev:        The devfreq user device. (parent of devfreq)
1373  * @devfreq:    The devfreq object.
1374  */
1375 void devm_devfreq_unregister_opp_notifier(struct device *dev,
1376                                          struct devfreq *devfreq)
1377 {
1378         WARN_ON(devres_release(dev, devm_devfreq_opp_release,
1379                                devm_devfreq_dev_match, devfreq));
1380 }
1381 EXPORT_SYMBOL(devm_devfreq_unregister_opp_notifier);
1382
1383 /**
1384  * devfreq_register_notifier() - Register a driver with devfreq
1385  * @devfreq:    The devfreq object.
1386  * @nb:         The notifier block to register.
1387  * @list:       DEVFREQ_TRANSITION_NOTIFIER.
1388  */
1389 int devfreq_register_notifier(struct devfreq *devfreq,
1390                                 struct notifier_block *nb,
1391                                 unsigned int list)
1392 {
1393         int ret = 0;
1394
1395         if (!devfreq)
1396                 return -EINVAL;
1397
1398         switch (list) {
1399         case DEVFREQ_TRANSITION_NOTIFIER:
1400                 ret = srcu_notifier_chain_register(
1401                                 &devfreq->transition_notifier_list, nb);
1402                 break;
1403         default:
1404                 ret = -EINVAL;
1405         }
1406
1407         return ret;
1408 }
1409 EXPORT_SYMBOL(devfreq_register_notifier);
1410
1411 /*
1412  * devfreq_unregister_notifier() - Unregister a driver with devfreq
1413  * @devfreq:    The devfreq object.
1414  * @nb:         The notifier block to be unregistered.
1415  * @list:       DEVFREQ_TRANSITION_NOTIFIER.
1416  */
1417 int devfreq_unregister_notifier(struct devfreq *devfreq,
1418                                 struct notifier_block *nb,
1419                                 unsigned int list)
1420 {
1421         int ret = 0;
1422
1423         if (!devfreq)
1424                 return -EINVAL;
1425
1426         switch (list) {
1427         case DEVFREQ_TRANSITION_NOTIFIER:
1428                 ret = srcu_notifier_chain_unregister(
1429                                 &devfreq->transition_notifier_list, nb);
1430                 break;
1431         default:
1432                 ret = -EINVAL;
1433         }
1434
1435         return ret;
1436 }
1437 EXPORT_SYMBOL(devfreq_unregister_notifier);
1438
1439 struct devfreq_notifier_devres {
1440         struct devfreq *devfreq;
1441         struct notifier_block *nb;
1442         unsigned int list;
1443 };
1444
1445 static void devm_devfreq_notifier_release(struct device *dev, void *res)
1446 {
1447         struct devfreq_notifier_devres *this = res;
1448
1449         devfreq_unregister_notifier(this->devfreq, this->nb, this->list);
1450 }
1451
1452 /**
1453  * devm_devfreq_register_notifier()
1454         - Resource-managed devfreq_register_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 int devm_devfreq_register_notifier(struct device *dev,
1461                                 struct devfreq *devfreq,
1462                                 struct notifier_block *nb,
1463                                 unsigned int list)
1464 {
1465         struct devfreq_notifier_devres *ptr;
1466         int ret;
1467
1468         ptr = devres_alloc(devm_devfreq_notifier_release, sizeof(*ptr),
1469                                 GFP_KERNEL);
1470         if (!ptr)
1471                 return -ENOMEM;
1472
1473         ret = devfreq_register_notifier(devfreq, nb, list);
1474         if (ret) {
1475                 devres_free(ptr);
1476                 return ret;
1477         }
1478
1479         ptr->devfreq = devfreq;
1480         ptr->nb = nb;
1481         ptr->list = list;
1482         devres_add(dev, ptr);
1483
1484         return 0;
1485 }
1486 EXPORT_SYMBOL(devm_devfreq_register_notifier);
1487
1488 /**
1489  * devm_devfreq_unregister_notifier()
1490         - Resource-managed devfreq_unregister_notifier()
1491  * @dev:        The devfreq user device. (parent of devfreq)
1492  * @devfreq:    The devfreq object.
1493  * @nb:         The notifier block to be unregistered.
1494  * @list:       DEVFREQ_TRANSITION_NOTIFIER.
1495  */
1496 void devm_devfreq_unregister_notifier(struct device *dev,
1497                                 struct devfreq *devfreq,
1498                                 struct notifier_block *nb,
1499                                 unsigned int list)
1500 {
1501         WARN_ON(devres_release(dev, devm_devfreq_notifier_release,
1502                                devm_devfreq_dev_match, devfreq));
1503 }
1504 EXPORT_SYMBOL(devm_devfreq_unregister_notifier);