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         for (i = 0, freq = 0; i < profile->max_state; i++, freq++) {
 115                 opp = dev_pm_opp_find_freq_ceil(devfreq->dev.parent, &freq);
 116                 if (IS_ERR(opp)) {
 117                         devm_kfree(devfreq->dev.parent, profile->freq_table);
 118                         profile->max_state = 0;
 119                         return;
 120                 }
 121                 dev_pm_opp_put(opp);
 122                 profile->freq_table[i] = freq;
 123         }
 124 }
 125
 126 /**
 127  * devfreq_update_status() - Update statistics of devfreq behavior
 128  * @devfreq:    the devfreq instance
 129  * @freq:       the update target frequency
 130  */
 131 static int devfreq_update_status(struct devfreq *devfreq, unsigned long freq)
 132 {
 133         int lev, prev_lev, ret = 0;
 134         unsigned long cur_time;
 135
 136         cur_time = jiffies;
 137
 138         /* Immediately exit if previous_freq is not initialized yet. */
 139         if (!devfreq->previous_freq)
 140                 goto out;
 141
 142         prev_lev = devfreq_get_freq_level(devfreq, devfreq->previous_freq);
 143         if (prev_lev < 0) {
 144                 ret = prev_lev;
 145                 goto out;
 146         }
 147
 148         devfreq->time_in_state[prev_lev] +=
 149                          cur_time - devfreq->last_stat_updated;
 150
 151         lev = devfreq_get_freq_level(devfreq, freq);
 152         if (lev < 0) {
 153                 ret = lev;
 154                 goto out;
 155         }
 156
 157         if (lev != prev_lev) {
 158                 devfreq->trans_table[(prev_lev *
 159                                 devfreq->profile->max_state) + lev]++;
 160                 devfreq->total_trans++;
 161         }
 162
 163 out:
 164         devfreq->last_stat_updated = cur_time;
 165         return ret;
 166 }
 167
 168 /**
 169  * find_devfreq_governor() - find devfreq governor from name
 170  * @name:       name of the governor
 171  *
 172  * Search the list of devfreq governors and return the matched
 173  * governor's pointer. devfreq_list_lock should be held by the caller.
 174  */
 175 static struct devfreq_governor *find_devfreq_governor(const char *name)
 176 {
 177         struct devfreq_governor *tmp_governor;
 178
 179         if (IS_ERR_OR_NULL(name)) {
 180                 pr_err("DEVFREQ: %s: Invalid parameters\n", __func__);
 181                 return ERR_PTR(-EINVAL);
 182         }
 183         WARN(!mutex_is_locked(&devfreq_list_lock),
 184              "devfreq_list_lock must be locked.");
 185
 186         list_for_each_entry(tmp_governor, &devfreq_governor_list, node) {
 187                 if (!strncmp(tmp_governor->name, name, DEVFREQ_NAME_LEN))
 188                         return tmp_governor;
 189         }
 190
 191         return ERR_PTR(-ENODEV);
 192 }
 193
 194 static int devfreq_notify_transition(struct devfreq *devfreq,
 195                 struct devfreq_freqs *freqs, unsigned int state)
 196 {
 197         if (!devfreq)
 198                 return -EINVAL;
 199
 200         switch (state) {
 201         case DEVFREQ_PRECHANGE:
 202                 srcu_notifier_call_chain(&devfreq->transition_notifier_list,
 203                                 DEVFREQ_PRECHANGE, freqs);
 204                 break;
 205
 206         case DEVFREQ_POSTCHANGE:
 207                 srcu_notifier_call_chain(&devfreq->transition_notifier_list,
 208                                 DEVFREQ_POSTCHANGE, freqs);
 209                 break;
 210         default:
 211                 return -EINVAL;
 212         }
 213
 214         return 0;
 215 }
 216
 217 /* Load monitoring helper functions for governors use */
 218
 219 /**
 220  * update_devfreq() - Reevaluate the device and configure frequency.
 221  * @devfreq:    the devfreq instance.
 222  *
 223  * Note: Lock devfreq->lock before calling update_devfreq
 224  *       This function is exported for governors.
 225  */
 226 int update_devfreq(struct devfreq *devfreq)
 227 {
 228         struct devfreq_freqs freqs;
 229         unsigned long freq, cur_freq;
 230         int err = 0;
 231         u32 flags = 0;
 232
 233         if (!mutex_is_locked(&devfreq->lock)) {
 234                 WARN(true, "devfreq->lock must be locked by the caller.\n");
 235                 return -EINVAL;
 236         }
 237
 238         if (!devfreq->governor)
 239                 return -EINVAL;
 240
 241         /* Reevaluate the proper frequency */
 242         err = devfreq->governor->get_target_freq(devfreq, &freq);
 243         if (err)
 244                 return err;
 245
 246         /*
 247          * Adjust the frequency with user freq and QoS.
 248          *
 249          * List from the highest priority
 250          * max_freq
 251          * min_freq
 252          */
 253
 254         if (devfreq->min_freq && freq < devfreq->min_freq) {
 255                 freq = devfreq->min_freq;
 256                 flags &= ~DEVFREQ_FLAG_LEAST_UPPER_BOUND; /* Use GLB */
 257         }
 258         if (devfreq->max_freq && freq > devfreq->max_freq) {
 259                 freq = devfreq->max_freq;
 260                 flags |= DEVFREQ_FLAG_LEAST_UPPER_BOUND; /* Use LUB */
 261         }
 262
 263         if (devfreq->profile->get_cur_freq)
 264                 devfreq->profile->get_cur_freq(devfreq->dev.parent, &cur_freq);
 265         else
 266                 cur_freq = devfreq->previous_freq;
 267
 268         freqs.old = cur_freq;
 269         freqs.new = freq;
 270         devfreq_notify_transition(devfreq, &freqs, DEVFREQ_PRECHANGE);
 271
 272         err = devfreq->profile->target(devfreq->dev.parent, &freq, flags);
 273         if (err) {
 274                 freqs.new = cur_freq;
 275                 devfreq_notify_transition(devfreq, &freqs, DEVFREQ_POSTCHANGE);
 276                 return err;
 277         }
 278
 279         freqs.new = freq;
 280         devfreq_notify_transition(devfreq, &freqs, DEVFREQ_POSTCHANGE);
 281
 282         if (devfreq->profile->freq_table)
 283                 if (devfreq_update_status(devfreq, freq))
 284                         dev_err(&devfreq->dev,
 285                                 "Couldn't update frequency transition information.\n");
 286
 287         devfreq->previous_freq = freq;
 288         return err;
 289 }
 290 EXPORT_SYMBOL(update_devfreq);
 291
 292 /**
 293  * devfreq_monitor() - Periodically poll devfreq objects.
 294  * @work:       the work struct used to run devfreq_monitor periodically.
 295  *
 296  */
 297 static void devfreq_monitor(struct work_struct *work)
 298 {
 299         int err;
 300         struct devfreq *devfreq = container_of(work,
 301                                         struct devfreq, work.work);
 302
 303         mutex_lock(&devfreq->lock);
 304         err = update_devfreq(devfreq);
 305         if (err)
 306                 dev_err(&devfreq->dev, "dvfs failed with (%d) error\n", err);
 307
 308         queue_delayed_work(devfreq_wq, &devfreq->work,
 309                                 msecs_to_jiffies(devfreq->profile->polling_ms));
 310         mutex_unlock(&devfreq->lock);
 311 }
 312
 313 /**
 314  * devfreq_monitor_start() - Start load monitoring of devfreq instance
 315  * @devfreq:    the devfreq instance.
 316  *
 317  * Helper function for starting devfreq device load monitoing. By
 318  * default delayed work based monitoring is supported. Function
 319  * to be called from governor in response to DEVFREQ_GOV_START
 320  * event when device is added to devfreq framework.
 321  */
 322 void devfreq_monitor_start(struct devfreq *devfreq)
 323 {
 324         INIT_DEFERRABLE_WORK(&devfreq->work, devfreq_monitor);
 325         if (devfreq->profile->polling_ms)
 326                 queue_delayed_work(devfreq_wq, &devfreq->work,
 327                         msecs_to_jiffies(devfreq->profile->polling_ms));
 328 }
 329 EXPORT_SYMBOL(devfreq_monitor_start);
 330
 331 /**
 332  * devfreq_monitor_stop() - Stop load monitoring of a devfreq instance
 333  * @devfreq:    the devfreq instance.
 334  *
 335  * Helper function to stop devfreq device load monitoing. Function
 336  * to be called from governor in response to DEVFREQ_GOV_STOP
 337  * event when device is removed from devfreq framework.
 338  */
 339 void devfreq_monitor_stop(struct devfreq *devfreq)
 340 {
 341         cancel_delayed_work_sync(&devfreq->work);
 342 }
 343 EXPORT_SYMBOL(devfreq_monitor_stop);
 344
 345 /**
 346  * devfreq_monitor_suspend() - Suspend load monitoring of a devfreq instance
 347  * @devfreq:    the devfreq instance.
 348  *
 349  * Helper function to suspend devfreq device load monitoing. Function
 350  * to be called from governor in response to DEVFREQ_GOV_SUSPEND
 351  * event or when polling interval is set to zero.
 352  *
 353  * Note: Though this function is same as devfreq_monitor_stop(),
 354  * intentionally kept separate to provide hooks for collecting
 355  * transition statistics.
 356  */
 357 void devfreq_monitor_suspend(struct devfreq *devfreq)
 358 {
 359         mutex_lock(&devfreq->lock);
 360         if (devfreq->stop_polling) {
 361                 mutex_unlock(&devfreq->lock);
 362                 return;
 363         }
 364
 365         devfreq_update_status(devfreq, devfreq->previous_freq);
 366         devfreq->stop_polling = true;
 367         mutex_unlock(&devfreq->lock);
 368         cancel_delayed_work_sync(&devfreq->work);
 369 }
 370 EXPORT_SYMBOL(devfreq_monitor_suspend);
 371
 372 /**
 373  * devfreq_monitor_resume() - Resume load monitoring of a devfreq instance
 374  * @devfreq:    the devfreq instance.
 375  *
 376  * Helper function to resume devfreq device load monitoing. Function
 377  * to be called from governor in response to DEVFREQ_GOV_RESUME
 378  * event or when polling interval is set to non-zero.
 379  */
 380 void devfreq_monitor_resume(struct devfreq *devfreq)
 381 {
 382         unsigned long freq;
 383
 384         mutex_lock(&devfreq->lock);
 385         if (!devfreq->stop_polling)
 386                 goto out;
 387
 388         if (!delayed_work_pending(&devfreq->work) &&
 389                         devfreq->profile->polling_ms)
 390                 queue_delayed_work(devfreq_wq, &devfreq->work,
 391                         msecs_to_jiffies(devfreq->profile->polling_ms));
 392
 393         devfreq->last_stat_updated = jiffies;
 394         devfreq->stop_polling = false;
 395
 396         if (devfreq->profile->get_cur_freq &&
 397                 !devfreq->profile->get_cur_freq(devfreq->dev.parent, &freq))
 398                 devfreq->previous_freq = freq;
 399
 400 out:
 401         mutex_unlock(&devfreq->lock);
 402 }
 403 EXPORT_SYMBOL(devfreq_monitor_resume);
 404
 405 /**
 406  * devfreq_interval_update() - Update device devfreq monitoring interval
 407  * @devfreq:    the devfreq instance.
 408  * @delay:      new polling interval to be set.
 409  *
 410  * Helper function to set new load monitoring polling interval. Function
 411  * to be called from governor in response to DEVFREQ_GOV_INTERVAL event.
 412  */
 413 void devfreq_interval_update(struct devfreq *devfreq, unsigned int *delay)
 414 {
 415         unsigned int cur_delay = devfreq->profile->polling_ms;
 416         unsigned int new_delay = *delay;
 417
 418         mutex_lock(&devfreq->lock);
 419         devfreq->profile->polling_ms = new_delay;
 420
 421         if (devfreq->stop_polling)
 422                 goto out;
 423
 424         /* if new delay is zero, stop polling */
 425         if (!new_delay) {
 426                 mutex_unlock(&devfreq->lock);
 427                 cancel_delayed_work_sync(&devfreq->work);
 428                 return;
 429         }
 430
 431         /* if current delay is zero, start polling with new delay */
 432         if (!cur_delay) {
 433                 queue_delayed_work(devfreq_wq, &devfreq->work,
 434                         msecs_to_jiffies(devfreq->profile->polling_ms));
 435                 goto out;
 436         }
 437
 438         /* if current delay is greater than new delay, restart polling */
 439         if (cur_delay > new_delay) {
 440                 mutex_unlock(&devfreq->lock);
 441                 cancel_delayed_work_sync(&devfreq->work);
 442                 mutex_lock(&devfreq->lock);
 443                 if (!devfreq->stop_polling)
 444                         queue_delayed_work(devfreq_wq, &devfreq->work,
 445                               msecs_to_jiffies(devfreq->profile->polling_ms));
 446         }
 447 out:
 448         mutex_unlock(&devfreq->lock);
 449 }
 450 EXPORT_SYMBOL(devfreq_interval_update);
 451
 452 /**
 453  * devfreq_notifier_call() - Notify that the device frequency requirements
 454  *                         has been changed out of devfreq framework.
 455  * @nb:         the notifier_block (supposed to be devfreq->nb)
 456  * @type:       not used
 457  * @devp:       not used
 458  *
 459  * Called by a notifier that uses devfreq->nb.
 460  */
 461 static int devfreq_notifier_call(struct notifier_block *nb, unsigned long type,
 462                                  void *devp)
 463 {
 464         struct devfreq *devfreq = container_of(nb, struct devfreq, nb);
 465         int ret;
 466
 467         mutex_lock(&devfreq->lock);
 468         ret = update_devfreq(devfreq);
 469         mutex_unlock(&devfreq->lock);
 470
 471         return ret;
 472 }
 473
 474 /**
 475  * _remove_devfreq() - Remove devfreq from the list and release its resources.
 476  * @devfreq:    the devfreq struct
 477  */
 478 static void _remove_devfreq(struct devfreq *devfreq)
 479 {
 480         mutex_lock(&devfreq_list_lock);
 481         if (IS_ERR(find_device_devfreq(devfreq->dev.parent))) {
 482                 mutex_unlock(&devfreq_list_lock);
 483                 dev_warn(&devfreq->dev, "releasing devfreq which doesn't exist\n");
 484                 return;
 485         }
 486         list_del(&devfreq->node);
 487         mutex_unlock(&devfreq_list_lock);
 488
 489         if (devfreq->governor)
 490                 devfreq->governor->event_handler(devfreq,
 491                                                  DEVFREQ_GOV_STOP, NULL);
 492
 493         if (devfreq->profile->exit)
 494                 devfreq->profile->exit(devfreq->dev.parent);
 495
 496         mutex_destroy(&devfreq->lock);
 497         kfree(devfreq);
 498 }
 499
 500 /**
 501  * devfreq_dev_release() - Callback for struct device to release the device.
 502  * @dev:        the devfreq device
 503  *
 504  * This calls _remove_devfreq() if _remove_devfreq() is not called.
 505  */
 506 static void devfreq_dev_release(struct device *dev)
 507 {
 508         struct devfreq *devfreq = to_devfreq(dev);
 509
 510         _remove_devfreq(devfreq);
 511 }
 512
 513 /**
 514  * devfreq_add_device() - Add devfreq feature to the device
 515  * @dev:        the device to add devfreq feature.
 516  * @profile:    device-specific profile to run devfreq.
 517  * @governor_name:      name of the policy to choose frequency.
 518  * @data:       private data for the governor. The devfreq framework does not
 519  *              touch this value.
 520  */
 521 struct devfreq *devfreq_add_device(struct device *dev,
 522                                    struct devfreq_dev_profile *profile,
 523                                    const char *governor_name,
 524                                    void *data)
 525 {
 526         struct devfreq *devfreq;
 527         struct devfreq_governor *governor;
 528         int err = 0;
 529
 530         if (!dev || !profile || !governor_name) {
 531                 dev_err(dev, "%s: Invalid parameters.\n", __func__);
 532                 return ERR_PTR(-EINVAL);
 533         }
 534
 535         mutex_lock(&devfreq_list_lock);
 536         devfreq = find_device_devfreq(dev);
 537         mutex_unlock(&devfreq_list_lock);
 538         if (!IS_ERR(devfreq)) {
 539                 dev_err(dev, "%s: Unable to create devfreq for the device. It already has one.\n", __func__);
 540                 err = -EINVAL;
 541                 goto err_out;
 542         }
 543
 544         devfreq = kzalloc(sizeof(struct devfreq), GFP_KERNEL);
 545         if (!devfreq) {
 546                 dev_err(dev, "%s: Unable to create devfreq for the device\n",
 547                         __func__);
 548                 err = -ENOMEM;
 549                 goto err_out;
 550         }
 551
 552         mutex_init(&devfreq->lock);
 553         mutex_lock(&devfreq->lock);
 554         devfreq->dev.parent = dev;
 555         devfreq->dev.class = devfreq_class;
 556         devfreq->dev.release = devfreq_dev_release;
 557         devfreq->profile = profile;
 558         strncpy(devfreq->governor_name, governor_name, DEVFREQ_NAME_LEN);
 559         devfreq->previous_freq = profile->initial_freq;
 560         devfreq->last_status.current_frequency = profile->initial_freq;
 561         devfreq->data = data;
 562         devfreq->nb.notifier_call = devfreq_notifier_call;
 563
 564         if (!devfreq->profile->max_state && !devfreq->profile->freq_table) {
 565                 mutex_unlock(&devfreq->lock);
 566                 devfreq_set_freq_table(devfreq);
 567                 mutex_lock(&devfreq->lock);
 568         }
 569
 570         dev_set_name(&devfreq->dev, "%s", dev_name(dev));
 571         err = device_register(&devfreq->dev);
 572         if (err) {
 573                 mutex_unlock(&devfreq->lock);
 574                 goto err_out;
 575         }
 576
 577         devfreq->trans_table =  devm_kzalloc(&devfreq->dev, sizeof(unsigned int) *
 578                                                 devfreq->profile->max_state *
 579                                                 devfreq->profile->max_state,
 580                                                 GFP_KERNEL);
 581         devfreq->time_in_state = devm_kzalloc(&devfreq->dev, sizeof(unsigned long) *
 582                                                 devfreq->profile->max_state,
 583                                                 GFP_KERNEL);
 584         devfreq->last_stat_updated = jiffies;
 585
 586         srcu_init_notifier_head(&devfreq->transition_notifier_list);
 587
 588         mutex_unlock(&devfreq->lock);
 589
 590         mutex_lock(&devfreq_list_lock);
 591         list_add(&devfreq->node, &devfreq_list);
 592
 593         governor = find_devfreq_governor(devfreq->governor_name);
 594         if (IS_ERR(governor)) {
 595                 dev_err(dev, "%s: Unable to find governor for the device\n",
 596                         __func__);
 597                 err = PTR_ERR(governor);
 598                 goto err_init;
 599         }
 600
 601         devfreq->governor = governor;
 602         err = devfreq->governor->event_handler(devfreq, DEVFREQ_GOV_START,
 603                                                 NULL);
 604         if (err) {
 605                 dev_err(dev, "%s: Unable to start governor for the device\n",
 606                         __func__);
 607                 goto err_init;
 608         }
 609         mutex_unlock(&devfreq_list_lock);
 610
 611         return devfreq;
 612
 613 err_init:
 614         list_del(&devfreq->node);
 615         mutex_unlock(&devfreq_list_lock);
 616
 617         device_unregister(&devfreq->dev);
 618 err_out:
 619         return ERR_PTR(err);
 620 }
 621 EXPORT_SYMBOL(devfreq_add_device);
 622
 623 /**
 624  * devfreq_remove_device() - Remove devfreq feature from a device.
 625  * @devfreq:    the devfreq instance to be removed
 626  *
 627  * The opposite of devfreq_add_device().
 628  */
 629 int devfreq_remove_device(struct devfreq *devfreq)
 630 {
 631         if (!devfreq)
 632                 return -EINVAL;
 633
 634         device_unregister(&devfreq->dev);
 635
 636         return 0;
 637 }
 638 EXPORT_SYMBOL(devfreq_remove_device);
 639
 640 static int devm_devfreq_dev_match(struct device *dev, void *res, void *data)
 641 {
 642         struct devfreq **r = res;
 643
 644         if (WARN_ON(!r || !*r))
 645                 return 0;
 646
 647         return *r == data;
 648 }
 649
 650 static void devm_devfreq_dev_release(struct device *dev, void *res)
 651 {
 652         devfreq_remove_device(*(struct devfreq **)res);
 653 }
 654
 655 /**
 656  * devm_devfreq_add_device() - Resource-managed devfreq_add_device()
 657  * @dev:        the device to add devfreq feature.
 658  * @profile:    device-specific profile to run devfreq.
 659  * @governor_name:      name of the policy to choose frequency.
 660  * @data:       private data for the governor. The devfreq framework does not
 661  *              touch this value.
 662  *
 663  * This function manages automatically the memory of devfreq device using device
 664  * resource management and simplify the free operation for memory of devfreq
 665  * device.
 666  */
 667 struct devfreq *devm_devfreq_add_device(struct device *dev,
 668                                         struct devfreq_dev_profile *profile,
 669                                         const char *governor_name,
 670                                         void *data)
 671 {
 672         struct devfreq **ptr, *devfreq;
 673
 674         ptr = devres_alloc(devm_devfreq_dev_release, sizeof(*ptr), GFP_KERNEL);
 675         if (!ptr)
 676                 return ERR_PTR(-ENOMEM);
 677
 678         devfreq = devfreq_add_device(dev, profile, governor_name, data);
 679         if (IS_ERR(devfreq)) {
 680                 devres_free(ptr);
 681                 return ERR_PTR(-ENOMEM);
 682         }
 683
 684         *ptr = devfreq;
 685         devres_add(dev, ptr);
 686
 687         return devfreq;
 688 }
 689 EXPORT_SYMBOL(devm_devfreq_add_device);
 690
 691 #ifdef CONFIG_OF
 692 /*
 693  * devfreq_get_devfreq_by_phandle - Get the devfreq device from devicetree
 694  * @dev - instance to the given device
 695  * @index - index into list of devfreq
 696  *
 697  * return the instance of devfreq device
 698  */
 699 struct devfreq *devfreq_get_devfreq_by_phandle(struct device *dev, int index)
 700 {
 701         struct device_node *node;
 702         struct devfreq *devfreq;
 703
 704         if (!dev)
 705                 return ERR_PTR(-EINVAL);
 706
 707         if (!dev->of_node)
 708                 return ERR_PTR(-EINVAL);
 709
 710         node = of_parse_phandle(dev->of_node, "devfreq", index);
 711         if (!node)
 712                 return ERR_PTR(-ENODEV);
 713
 714         mutex_lock(&devfreq_list_lock);
 715         list_for_each_entry(devfreq, &devfreq_list, node) {
 716                 if (devfreq->dev.parent
 717                         && devfreq->dev.parent->of_node == node) {
 718                         mutex_unlock(&devfreq_list_lock);
 719                         of_node_put(node);
 720                         return devfreq;
 721                 }
 722         }
 723         mutex_unlock(&devfreq_list_lock);
 724         of_node_put(node);
 725
 726         return ERR_PTR(-EPROBE_DEFER);
 727 }
 728 #else
 729 struct devfreq *devfreq_get_devfreq_by_phandle(struct device *dev, int index)
 730 {
 731         return ERR_PTR(-ENODEV);
 732 }
 733 #endif /* CONFIG_OF */
 734 EXPORT_SYMBOL_GPL(devfreq_get_devfreq_by_phandle);
 735
 736 /**
 737  * devm_devfreq_remove_device() - Resource-managed devfreq_remove_device()
 738  * @dev:        the device to add devfreq feature.
 739  * @devfreq:    the devfreq instance to be removed
 740  */
 741 void devm_devfreq_remove_device(struct device *dev, struct devfreq *devfreq)
 742 {
 743         WARN_ON(devres_release(dev, devm_devfreq_dev_release,
 744                                devm_devfreq_dev_match, devfreq));
 745 }
 746 EXPORT_SYMBOL(devm_devfreq_remove_device);
 747
 748 /**
 749  * devfreq_suspend_device() - Suspend devfreq of a device.
 750  * @devfreq: the devfreq instance to be suspended
 751  *
 752  * This function is intended to be called by the pm callbacks
 753  * (e.g., runtime_suspend, suspend) of the device driver that
 754  * holds the devfreq.
 755  */
 756 int devfreq_suspend_device(struct devfreq *devfreq)
 757 {
 758         if (!devfreq)
 759                 return -EINVAL;
 760
 761         if (!devfreq->governor)
 762                 return 0;
 763
 764         return devfreq->governor->event_handler(devfreq,
 765                                 DEVFREQ_GOV_SUSPEND, NULL);
 766 }
 767 EXPORT_SYMBOL(devfreq_suspend_device);
 768
 769 /**
 770  * devfreq_resume_device() - Resume devfreq of a device.
 771  * @devfreq: the devfreq instance to be resumed
 772  *
 773  * This function is intended to be called by the pm callbacks
 774  * (e.g., runtime_resume, resume) of the device driver that
 775  * holds the devfreq.
 776  */
 777 int devfreq_resume_device(struct devfreq *devfreq)
 778 {
 779         if (!devfreq)
 780                 return -EINVAL;
 781
 782         if (!devfreq->governor)
 783                 return 0;
 784
 785         return devfreq->governor->event_handler(devfreq,
 786                                 DEVFREQ_GOV_RESUME, NULL);
 787 }
 788 EXPORT_SYMBOL(devfreq_resume_device);
 789
 790 /**
 791  * devfreq_add_governor() - Add devfreq governor
 792  * @governor:   the devfreq governor to be added
 793  */
 794 int devfreq_add_governor(struct devfreq_governor *governor)
 795 {
 796         struct devfreq_governor *g;
 797         struct devfreq *devfreq;
 798         int err = 0;
 799
 800         if (!governor) {
 801                 pr_err("%s: Invalid parameters.\n", __func__);
 802                 return -EINVAL;
 803         }
 804
 805         mutex_lock(&devfreq_list_lock);
 806         g = find_devfreq_governor(governor->name);
 807         if (!IS_ERR(g)) {
 808                 pr_err("%s: governor %s already registered\n", __func__,
 809                        g->name);
 810                 err = -EINVAL;
 811                 goto err_out;
 812         }
 813
 814         list_add(&governor->node, &devfreq_governor_list);
 815
 816         list_for_each_entry(devfreq, &devfreq_list, node) {
 817                 int ret = 0;
 818                 struct device *dev = devfreq->dev.parent;
 819
 820                 if (!strncmp(devfreq->governor_name, governor->name,
 821                              DEVFREQ_NAME_LEN)) {
 822                         /* The following should never occur */
 823                         if (devfreq->governor) {
 824                                 dev_warn(dev,
 825                                          "%s: Governor %s already present\n",
 826                                          __func__, devfreq->governor->name);
 827                                 ret = devfreq->governor->event_handler(devfreq,
 828                                                         DEVFREQ_GOV_STOP, NULL);
 829                                 if (ret) {
 830                                         dev_warn(dev,
 831                                                  "%s: Governor %s stop = %d\n",
 832                                                  __func__,
 833                                                  devfreq->governor->name, ret);
 834                                 }
 835                                 /* Fall through */
 836                         }
 837                         devfreq->governor = governor;
 838                         ret = devfreq->governor->event_handler(devfreq,
 839                                                 DEVFREQ_GOV_START, NULL);
 840                         if (ret) {
 841                                 dev_warn(dev, "%s: Governor %s start=%d\n",
 842                                          __func__, devfreq->governor->name,
 843                                          ret);
 844                         }
 845                 }
 846         }
 847
 848 err_out:
 849         mutex_unlock(&devfreq_list_lock);
 850
 851         return err;
 852 }
 853 EXPORT_SYMBOL(devfreq_add_governor);
 854
 855 /**
 856  * devfreq_remove_governor() - Remove devfreq feature from a device.
 857  * @governor:   the devfreq governor to be removed
 858  */
 859 int devfreq_remove_governor(struct devfreq_governor *governor)
 860 {
 861         struct devfreq_governor *g;
 862         struct devfreq *devfreq;
 863         int err = 0;
 864
 865         if (!governor) {
 866                 pr_err("%s: Invalid parameters.\n", __func__);
 867                 return -EINVAL;
 868         }
 869
 870         mutex_lock(&devfreq_list_lock);
 871         g = find_devfreq_governor(governor->name);
 872         if (IS_ERR(g)) {
 873                 pr_err("%s: governor %s not registered\n", __func__,
 874                        governor->name);
 875                 err = PTR_ERR(g);
 876                 goto err_out;
 877         }
 878         list_for_each_entry(devfreq, &devfreq_list, node) {
 879                 int ret;
 880                 struct device *dev = devfreq->dev.parent;
 881
 882                 if (!strncmp(devfreq->governor_name, governor->name,
 883                              DEVFREQ_NAME_LEN)) {
 884                         /* we should have a devfreq governor! */
 885                         if (!devfreq->governor) {
 886                                 dev_warn(dev, "%s: Governor %s NOT present\n",
 887                                          __func__, governor->name);
 888                                 continue;
 889                                 /* Fall through */
 890                         }
 891                         ret = devfreq->governor->event_handler(devfreq,
 892                                                 DEVFREQ_GOV_STOP, NULL);
 893                         if (ret) {
 894                                 dev_warn(dev, "%s: Governor %s stop=%d\n",
 895                                          __func__, devfreq->governor->name,
 896                                          ret);
 897                         }
 898                         devfreq->governor = NULL;
 899                 }
 900         }
 901
 902         list_del(&governor->node);
 903 err_out:
 904         mutex_unlock(&devfreq_list_lock);
 905
 906         return err;
 907 }
 908 EXPORT_SYMBOL(devfreq_remove_governor);
 909
 910 static ssize_t governor_show(struct device *dev,
 911                              struct device_attribute *attr, char *buf)
 912 {
 913         if (!to_devfreq(dev)->governor)
 914                 return -EINVAL;
 915
 916         return sprintf(buf, "%s\n", to_devfreq(dev)->governor->name);
 917 }
 918
 919 static ssize_t governor_store(struct device *dev, struct device_attribute *attr,
 920                               const char *buf, size_t count)
 921 {
 922         struct devfreq *df = to_devfreq(dev);
 923         int ret;
 924         char str_governor[DEVFREQ_NAME_LEN + 1];
 925         struct devfreq_governor *governor;
 926
 927         ret = sscanf(buf, "%" __stringify(DEVFREQ_NAME_LEN) "s", str_governor);
 928         if (ret != 1)
 929                 return -EINVAL;
 930
 931         mutex_lock(&devfreq_list_lock);
 932         governor = find_devfreq_governor(str_governor);
 933         if (IS_ERR(governor)) {
 934                 ret = PTR_ERR(governor);
 935                 goto out;
 936         }
 937         if (df->governor == governor) {
 938                 ret = 0;
 939                 goto out;
 940         }
 941
 942         if (df->governor) {
 943                 ret = df->governor->event_handler(df, DEVFREQ_GOV_STOP, NULL);
 944                 if (ret) {
 945                         dev_warn(dev, "%s: Governor %s not stopped(%d)\n",
 946                                  __func__, df->governor->name, ret);
 947                         goto out;
 948                 }
 949         }
 950         df->governor = governor;
 951         strncpy(df->governor_name, governor->name, DEVFREQ_NAME_LEN);
 952         ret = df->governor->event_handler(df, DEVFREQ_GOV_START, NULL);
 953         if (ret)
 954                 dev_warn(dev, "%s: Governor %s not started(%d)\n",
 955                          __func__, df->governor->name, ret);
 956 out:
 957         mutex_unlock(&devfreq_list_lock);
 958
 959         if (!ret)
 960                 ret = count;
 961         return ret;
 962 }
 963 static DEVICE_ATTR_RW(governor);
 964
 965 static ssize_t available_governors_show(struct device *d,
 966                                         struct device_attribute *attr,
 967                                         char *buf)
 968 {
 969         struct devfreq_governor *tmp_governor;
 970         ssize_t count = 0;
 971
 972         mutex_lock(&devfreq_list_lock);
 973         list_for_each_entry(tmp_governor, &devfreq_governor_list, node)
 974                 count += scnprintf(&buf[count], (PAGE_SIZE - count - 2),
 975                                    "%s ", tmp_governor->name);
 976         mutex_unlock(&devfreq_list_lock);
 977
 978         /* Truncate the trailing space */
 979         if (count)
 980                 count--;
 981
 982         count += sprintf(&buf[count], "\n");
 983
 984         return count;
 985 }
 986 static DEVICE_ATTR_RO(available_governors);
 987
 988 static ssize_t cur_freq_show(struct device *dev, struct device_attribute *attr,
 989                              char *buf)
 990 {
 991         unsigned long freq;
 992         struct devfreq *devfreq = to_devfreq(dev);
 993
 994         if (devfreq->profile->get_cur_freq &&
 995                 !devfreq->profile->get_cur_freq(devfreq->dev.parent, &freq))
 996                         return sprintf(buf, "%lu\n", freq);
 997
 998         return sprintf(buf, "%lu\n", devfreq->previous_freq);
 999 }
1000 static DEVICE_ATTR_RO(cur_freq);
1001
1002 static ssize_t target_freq_show(struct device *dev,
1003                                 struct device_attribute *attr, char *buf)
1004 {
1005         return sprintf(buf, "%lu\n", to_devfreq(dev)->previous_freq);
1006 }
1007 static DEVICE_ATTR_RO(target_freq);
1008
1009 static ssize_t polling_interval_show(struct device *dev,
1010                                      struct device_attribute *attr, char *buf)
1011 {
1012         return sprintf(buf, "%d\n", to_devfreq(dev)->profile->polling_ms);
1013 }
1014
1015 static ssize_t polling_interval_store(struct device *dev,
1016                                       struct device_attribute *attr,
1017                                       const char *buf, size_t count)
1018 {
1019         struct devfreq *df = to_devfreq(dev);
1020         unsigned int value;
1021         int ret;
1022
1023         if (!df->governor)
1024                 return -EINVAL;
1025
1026         ret = sscanf(buf, "%u", &value);
1027         if (ret != 1)
1028                 return -EINVAL;
1029
1030         df->governor->event_handler(df, DEVFREQ_GOV_INTERVAL, &value);
1031         ret = count;
1032
1033         return ret;
1034 }
1035 static DEVICE_ATTR_RW(polling_interval);
1036
1037 static ssize_t min_freq_store(struct device *dev, struct device_attribute *attr,
1038                               const char *buf, size_t count)
1039 {
1040         struct devfreq *df = to_devfreq(dev);
1041         unsigned long value;
1042         int ret;
1043         unsigned long max;
1044
1045         ret = sscanf(buf, "%lu", &value);
1046         if (ret != 1)
1047                 return -EINVAL;
1048
1049         mutex_lock(&df->lock);
1050         max = df->max_freq;
1051         if (value && max && value > max) {
1052                 ret = -EINVAL;
1053                 goto unlock;
1054         }
1055
1056         df->min_freq = value;
1057         update_devfreq(df);
1058         ret = count;
1059 unlock:
1060         mutex_unlock(&df->lock);
1061         return ret;
1062 }
1063
1064 static ssize_t max_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 min;
1071
1072         ret = sscanf(buf, "%lu", &value);
1073         if (ret != 1)
1074                 return -EINVAL;
1075
1076         mutex_lock(&df->lock);
1077         min = df->min_freq;
1078         if (value && min && value < min) {
1079                 ret = -EINVAL;
1080                 goto unlock;
1081         }
1082
1083         df->max_freq = value;
1084         update_devfreq(df);
1085         ret = count;
1086 unlock:
1087         mutex_unlock(&df->lock);
1088         return ret;
1089 }
1090
1091 #define show_one(name)                                          \
1092 static ssize_t name##_show                                      \
1093 (struct device *dev, struct device_attribute *attr, char *buf)  \
1094 {                                                               \
1095         return sprintf(buf, "%lu\n", to_devfreq(dev)->name);    \
1096 }
1097 show_one(min_freq);
1098 show_one(max_freq);
1099
1100 static DEVICE_ATTR_RW(min_freq);
1101 static DEVICE_ATTR_RW(max_freq);
1102
1103 static ssize_t available_frequencies_show(struct device *d,
1104                                           struct device_attribute *attr,
1105                                           char *buf)
1106 {
1107         struct devfreq *df = to_devfreq(d);
1108         struct device *dev = df->dev.parent;
1109         struct dev_pm_opp *opp;
1110         ssize_t count = 0;
1111         unsigned long freq = 0;
1112
1113         do {
1114                 opp = dev_pm_opp_find_freq_ceil(dev, &freq);
1115                 if (IS_ERR(opp))
1116                         break;
1117
1118                 dev_pm_opp_put(opp);
1119                 count += scnprintf(&buf[count], (PAGE_SIZE - count - 2),
1120                                    "%lu ", freq);
1121                 freq++;
1122         } while (1);
1123
1124         /* Truncate the trailing space */
1125         if (count)
1126                 count--;
1127
1128         count += sprintf(&buf[count], "\n");
1129
1130         return count;
1131 }
1132 static DEVICE_ATTR_RO(available_frequencies);
1133
1134 static ssize_t trans_stat_show(struct device *dev,
1135                                struct device_attribute *attr, char *buf)
1136 {
1137         struct devfreq *devfreq = to_devfreq(dev);
1138         ssize_t len;
1139         int i, j;
1140         unsigned int max_state = devfreq->profile->max_state;
1141
1142         if (!devfreq->stop_polling &&
1143                         devfreq_update_status(devfreq, devfreq->previous_freq))
1144                 return 0;
1145         if (max_state == 0)
1146                 return sprintf(buf, "Not Supported.\n");
1147
1148         len = sprintf(buf, "     From  :   To\n");
1149         len += sprintf(buf + len, "           :");
1150         for (i = 0; i < max_state; i++)
1151                 len += sprintf(buf + len, "%10lu",
1152                                 devfreq->profile->freq_table[i]);
1153
1154         len += sprintf(buf + len, "   time(ms)\n");
1155
1156         for (i = 0; i < max_state; i++) {
1157                 if (devfreq->profile->freq_table[i]
1158                                         == devfreq->previous_freq) {
1159                         len += sprintf(buf + len, "*");
1160                 } else {
1161                         len += sprintf(buf + len, " ");
1162                 }
1163                 len += sprintf(buf + len, "%10lu:",
1164                                 devfreq->profile->freq_table[i]);
1165                 for (j = 0; j < max_state; j++)
1166                         len += sprintf(buf + len, "%10u",
1167                                 devfreq->trans_table[(i * max_state) + j]);
1168                 len += sprintf(buf + len, "%10u\n",
1169                         jiffies_to_msecs(devfreq->time_in_state[i]));
1170         }
1171
1172         len += sprintf(buf + len, "Total transition : %u\n",
1173                                         devfreq->total_trans);
1174         return len;
1175 }
1176 static DEVICE_ATTR_RO(trans_stat);
1177
1178 static struct attribute *devfreq_attrs[] = {
1179         &dev_attr_governor.attr,
1180         &dev_attr_available_governors.attr,
1181         &dev_attr_cur_freq.attr,
1182         &dev_attr_available_frequencies.attr,
1183         &dev_attr_target_freq.attr,
1184         &dev_attr_polling_interval.attr,
1185         &dev_attr_min_freq.attr,
1186         &dev_attr_max_freq.attr,
1187         &dev_attr_trans_stat.attr,
1188         NULL,
1189 };
1190 ATTRIBUTE_GROUPS(devfreq);
1191
1192 static int __init devfreq_init(void)
1193 {
1194         devfreq_class = class_create(THIS_MODULE, "devfreq");
1195         if (IS_ERR(devfreq_class)) {
1196                 pr_err("%s: couldn't create class\n", __FILE__);
1197                 return PTR_ERR(devfreq_class);
1198         }
1199
1200         devfreq_wq = create_freezable_workqueue("devfreq_wq");
1201         if (!devfreq_wq) {
1202                 class_destroy(devfreq_class);
1203                 pr_err("%s: couldn't create workqueue\n", __FILE__);
1204                 return -ENOMEM;
1205         }
1206         devfreq_class->dev_groups = devfreq_groups;
1207
1208         return 0;
1209 }
1210 subsys_initcall(devfreq_init);
1211
1212 /*
1213  * The followings are helper functions for devfreq user device drivers with
1214  * OPP framework.
1215  */
1216
1217 /**
1218  * devfreq_recommended_opp() - Helper function to get proper OPP for the
1219  *                           freq value given to target callback.
1220  * @dev:        The devfreq user device. (parent of devfreq)
1221  * @freq:       The frequency given to target function
1222  * @flags:      Flags handed from devfreq framework.
1223  *
1224  * The callers are required to call dev_pm_opp_put() for the returned OPP after
1225  * use.
1226  */
1227 struct dev_pm_opp *devfreq_recommended_opp(struct device *dev,
1228                                            unsigned long *freq,
1229                                            u32 flags)
1230 {
1231         struct dev_pm_opp *opp;
1232
1233         if (flags & DEVFREQ_FLAG_LEAST_UPPER_BOUND) {
1234                 /* The freq is an upper bound. opp should be lower */
1235                 opp = dev_pm_opp_find_freq_floor(dev, freq);
1236
1237                 /* If not available, use the closest opp */
1238                 if (opp == ERR_PTR(-ERANGE))
1239                         opp = dev_pm_opp_find_freq_ceil(dev, freq);
1240         } else {
1241                 /* The freq is an lower bound. opp should be higher */
1242                 opp = dev_pm_opp_find_freq_ceil(dev, freq);
1243
1244                 /* If not available, use the closest opp */
1245                 if (opp == ERR_PTR(-ERANGE))
1246                         opp = dev_pm_opp_find_freq_floor(dev, freq);
1247         }
1248
1249         return opp;
1250 }
1251 EXPORT_SYMBOL(devfreq_recommended_opp);
1252
1253 /**
1254  * devfreq_register_opp_notifier() - Helper function to get devfreq notified
1255  *                                 for any changes in the OPP availability
1256  *                                 changes
1257  * @dev:        The devfreq user device. (parent of devfreq)
1258  * @devfreq:    The devfreq object.
1259  */
1260 int devfreq_register_opp_notifier(struct device *dev, struct devfreq *devfreq)
1261 {
1262         return dev_pm_opp_register_notifier(dev, &devfreq->nb);
1263 }
1264 EXPORT_SYMBOL(devfreq_register_opp_notifier);
1265
1266 /**
1267  * devfreq_unregister_opp_notifier() - Helper function to stop getting devfreq
1268  *                                   notified for any changes in the OPP
1269  *                                   availability changes anymore.
1270  * @dev:        The devfreq user device. (parent of devfreq)
1271  * @devfreq:    The devfreq object.
1272  *
1273  * At exit() callback of devfreq_dev_profile, this must be included if
1274  * devfreq_recommended_opp is used.
1275  */
1276 int devfreq_unregister_opp_notifier(struct device *dev, struct devfreq *devfreq)
1277 {
1278         return dev_pm_opp_unregister_notifier(dev, &devfreq->nb);
1279 }
1280 EXPORT_SYMBOL(devfreq_unregister_opp_notifier);
1281
1282 static void devm_devfreq_opp_release(struct device *dev, void *res)
1283 {
1284         devfreq_unregister_opp_notifier(dev, *(struct devfreq **)res);
1285 }
1286
1287 /**
1288  * devm_ devfreq_register_opp_notifier()
1289  *              - Resource-managed devfreq_register_opp_notifier()
1290  * @dev:        The devfreq user device. (parent of devfreq)
1291  * @devfreq:    The devfreq object.
1292  */
1293 int devm_devfreq_register_opp_notifier(struct device *dev,
1294                                        struct devfreq *devfreq)
1295 {
1296         struct devfreq **ptr;
1297         int ret;
1298
1299         ptr = devres_alloc(devm_devfreq_opp_release, sizeof(*ptr), GFP_KERNEL);
1300         if (!ptr)
1301                 return -ENOMEM;
1302
1303         ret = devfreq_register_opp_notifier(dev, devfreq);
1304         if (ret) {
1305                 devres_free(ptr);
1306                 return ret;
1307         }
1308
1309         *ptr = devfreq;
1310         devres_add(dev, ptr);
1311
1312         return 0;
1313 }
1314 EXPORT_SYMBOL(devm_devfreq_register_opp_notifier);
1315
1316 /**
1317  * devm_devfreq_unregister_opp_notifier()
1318  *              - Resource-managed devfreq_unregister_opp_notifier()
1319  * @dev:        The devfreq user device. (parent of devfreq)
1320  * @devfreq:    The devfreq object.
1321  */
1322 void devm_devfreq_unregister_opp_notifier(struct device *dev,
1323                                          struct devfreq *devfreq)
1324 {
1325         WARN_ON(devres_release(dev, devm_devfreq_opp_release,
1326                                devm_devfreq_dev_match, devfreq));
1327 }
1328 EXPORT_SYMBOL(devm_devfreq_unregister_opp_notifier);
1329
1330 /**
1331  * devfreq_register_notifier() - Register a driver with devfreq
1332  * @devfreq:    The devfreq object.
1333  * @nb:         The notifier block to register.
1334  * @list:       DEVFREQ_TRANSITION_NOTIFIER.
1335  */
1336 int devfreq_register_notifier(struct devfreq *devfreq,
1337                                 struct notifier_block *nb,
1338                                 unsigned int list)
1339 {
1340         int ret = 0;
1341
1342         if (!devfreq)
1343                 return -EINVAL;
1344
1345         switch (list) {
1346         case DEVFREQ_TRANSITION_NOTIFIER:
1347                 ret = srcu_notifier_chain_register(
1348                                 &devfreq->transition_notifier_list, nb);
1349                 break;
1350         default:
1351                 ret = -EINVAL;
1352         }
1353
1354         return ret;
1355 }
1356 EXPORT_SYMBOL(devfreq_register_notifier);
1357
1358 /*
1359  * devfreq_unregister_notifier() - Unregister a driver with devfreq
1360  * @devfreq:    The devfreq object.
1361  * @nb:         The notifier block to be unregistered.
1362  * @list:       DEVFREQ_TRANSITION_NOTIFIER.
1363  */
1364 int devfreq_unregister_notifier(struct devfreq *devfreq,
1365                                 struct notifier_block *nb,
1366                                 unsigned int list)
1367 {
1368         int ret = 0;
1369
1370         if (!devfreq)
1371                 return -EINVAL;
1372
1373         switch (list) {
1374         case DEVFREQ_TRANSITION_NOTIFIER:
1375                 ret = srcu_notifier_chain_unregister(
1376                                 &devfreq->transition_notifier_list, nb);
1377                 break;
1378         default:
1379                 ret = -EINVAL;
1380         }
1381
1382         return ret;
1383 }
1384 EXPORT_SYMBOL(devfreq_unregister_notifier);
1385
1386 struct devfreq_notifier_devres {
1387         struct devfreq *devfreq;
1388         struct notifier_block *nb;
1389         unsigned int list;
1390 };
1391
1392 static void devm_devfreq_notifier_release(struct device *dev, void *res)
1393 {
1394         struct devfreq_notifier_devres *this = res;
1395
1396         devfreq_unregister_notifier(this->devfreq, this->nb, this->list);
1397 }
1398
1399 /**
1400  * devm_devfreq_register_notifier()
1401         - Resource-managed devfreq_register_notifier()
1402  * @dev:        The devfreq user device. (parent of devfreq)
1403  * @devfreq:    The devfreq object.
1404  * @nb:         The notifier block to be unregistered.
1405  * @list:       DEVFREQ_TRANSITION_NOTIFIER.
1406  */
1407 int devm_devfreq_register_notifier(struct device *dev,
1408                                 struct devfreq *devfreq,
1409                                 struct notifier_block *nb,
1410                                 unsigned int list)
1411 {
1412         struct devfreq_notifier_devres *ptr;
1413         int ret;
1414
1415         ptr = devres_alloc(devm_devfreq_notifier_release, sizeof(*ptr),
1416                                 GFP_KERNEL);
1417         if (!ptr)
1418                 return -ENOMEM;
1419
1420         ret = devfreq_register_notifier(devfreq, nb, list);
1421         if (ret) {
1422                 devres_free(ptr);
1423                 return ret;
1424         }
1425
1426         ptr->devfreq = devfreq;
1427         ptr->nb = nb;
1428         ptr->list = list;
1429         devres_add(dev, ptr);
1430
1431         return 0;
1432 }
1433 EXPORT_SYMBOL(devm_devfreq_register_notifier);
1434
1435 /**
1436  * devm_devfreq_unregister_notifier()
1437         - Resource-managed devfreq_unregister_notifier()
1438  * @dev:        The devfreq user device. (parent of devfreq)
1439  * @devfreq:    The devfreq object.
1440  * @nb:         The notifier block to be unregistered.
1441  * @list:       DEVFREQ_TRANSITION_NOTIFIER.
1442  */
1443 void devm_devfreq_unregister_notifier(struct device *dev,
1444                                 struct devfreq *devfreq,
1445                                 struct notifier_block *nb,
1446                                 unsigned int list)
1447 {
1448         WARN_ON(devres_release(dev, devm_devfreq_notifier_release,
1449                                devm_devfreq_dev_match, devfreq));
1450 }
1451 EXPORT_SYMBOL(devm_devfreq_unregister_notifier);