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  * devfreq_dev_release() - Callback for struct device to release the device.
 479  * @dev:        the devfreq device
 480  *
 481  * Remove devfreq from the list and release its resources.
 482  */
 483 static void devfreq_dev_release(struct device *dev)
 484 {
 485         struct devfreq *devfreq = to_devfreq(dev);
 486
 487         mutex_lock(&devfreq_list_lock);
 488         if (IS_ERR(find_device_devfreq(devfreq->dev.parent))) {
 489                 mutex_unlock(&devfreq_list_lock);
 490                 dev_warn(&devfreq->dev, "releasing devfreq which doesn't exist\n");
 491                 return;
 492         }
 493         list_del(&devfreq->node);
 494         mutex_unlock(&devfreq_list_lock);
 495
 496         if (devfreq->governor)
 497                 devfreq->governor->event_handler(devfreq,
 498                                                  DEVFREQ_GOV_STOP, NULL);
 499
 500         if (devfreq->profile->exit)
 501                 devfreq->profile->exit(devfreq->dev.parent);
 502
 503         mutex_destroy(&devfreq->lock);
 504         kfree(devfreq);
 505 }
 506
 507 /**
 508  * devfreq_add_device() - Add devfreq feature to the device
 509  * @dev:        the device to add devfreq feature.
 510  * @profile:    device-specific profile to run devfreq.
 511  * @governor_name:      name of the policy to choose frequency.
 512  * @data:       private data for the governor. The devfreq framework does not
 513  *              touch this value.
 514  */
 515 struct devfreq *devfreq_add_device(struct device *dev,
 516                                    struct devfreq_dev_profile *profile,
 517                                    const char *governor_name,
 518                                    void *data)
 519 {
 520         struct devfreq *devfreq;
 521         struct devfreq_governor *governor;
 522         int err = 0;
 523
 524         if (!dev || !profile || !governor_name) {
 525                 dev_err(dev, "%s: Invalid parameters.\n", __func__);
 526                 return ERR_PTR(-EINVAL);
 527         }
 528
 529         mutex_lock(&devfreq_list_lock);
 530         devfreq = find_device_devfreq(dev);
 531         mutex_unlock(&devfreq_list_lock);
 532         if (!IS_ERR(devfreq)) {
 533                 dev_err(dev, "%s: Unable to create devfreq for the device.\n",
 534                         __func__);
 535                 err = -EINVAL;
 536                 goto err_out;
 537         }
 538
 539         devfreq = kzalloc(sizeof(struct devfreq), GFP_KERNEL);
 540         if (!devfreq) {
 541                 err = -ENOMEM;
 542                 goto err_out;
 543         }
 544
 545         mutex_init(&devfreq->lock);
 546         mutex_lock(&devfreq->lock);
 547         devfreq->dev.parent = dev;
 548         devfreq->dev.class = devfreq_class;
 549         devfreq->dev.release = devfreq_dev_release;
 550         devfreq->profile = profile;
 551         strncpy(devfreq->governor_name, governor_name, DEVFREQ_NAME_LEN);
 552         devfreq->previous_freq = profile->initial_freq;
 553         devfreq->last_status.current_frequency = profile->initial_freq;
 554         devfreq->data = data;
 555         devfreq->nb.notifier_call = devfreq_notifier_call;
 556
 557         if (!devfreq->profile->max_state && !devfreq->profile->freq_table) {
 558                 mutex_unlock(&devfreq->lock);
 559                 devfreq_set_freq_table(devfreq);
 560                 mutex_lock(&devfreq->lock);
 561         }
 562
 563         dev_set_name(&devfreq->dev, "%s", dev_name(dev));
 564         err = device_register(&devfreq->dev);
 565         if (err) {
 566                 mutex_unlock(&devfreq->lock);
 567                 goto err_out;
 568         }
 569
 570         devfreq->trans_table =  devm_kzalloc(&devfreq->dev,
 571                                                 sizeof(unsigned int) *
 572                                                 devfreq->profile->max_state *
 573                                                 devfreq->profile->max_state,
 574                                                 GFP_KERNEL);
 575         devfreq->time_in_state = devm_kzalloc(&devfreq->dev,
 576                                                 sizeof(unsigned long) *
 577                                                 devfreq->profile->max_state,
 578                                                 GFP_KERNEL);
 579         devfreq->last_stat_updated = jiffies;
 580
 581         srcu_init_notifier_head(&devfreq->transition_notifier_list);
 582
 583         mutex_unlock(&devfreq->lock);
 584
 585         mutex_lock(&devfreq_list_lock);
 586         list_add(&devfreq->node, &devfreq_list);
 587
 588         governor = find_devfreq_governor(devfreq->governor_name);
 589         if (IS_ERR(governor)) {
 590                 dev_err(dev, "%s: Unable to find governor for the device\n",
 591                         __func__);
 592                 err = PTR_ERR(governor);
 593                 goto err_init;
 594         }
 595
 596         devfreq->governor = governor;
 597         err = devfreq->governor->event_handler(devfreq, DEVFREQ_GOV_START,
 598                                                 NULL);
 599         if (err) {
 600                 dev_err(dev, "%s: Unable to start governor for the device\n",
 601                         __func__);
 602                 goto err_init;
 603         }
 604         mutex_unlock(&devfreq_list_lock);
 605
 606         return devfreq;
 607
 608 err_init:
 609         list_del(&devfreq->node);
 610         mutex_unlock(&devfreq_list_lock);
 611
 612         device_unregister(&devfreq->dev);
 613 err_out:
 614         return ERR_PTR(err);
 615 }
 616 EXPORT_SYMBOL(devfreq_add_device);
 617
 618 /**
 619  * devfreq_remove_device() - Remove devfreq feature from a device.
 620  * @devfreq:    the devfreq instance to be removed
 621  *
 622  * The opposite of devfreq_add_device().
 623  */
 624 int devfreq_remove_device(struct devfreq *devfreq)
 625 {
 626         if (!devfreq)
 627                 return -EINVAL;
 628
 629         device_unregister(&devfreq->dev);
 630
 631         return 0;
 632 }
 633 EXPORT_SYMBOL(devfreq_remove_device);
 634
 635 static int devm_devfreq_dev_match(struct device *dev, void *res, void *data)
 636 {
 637         struct devfreq **r = res;
 638
 639         if (WARN_ON(!r || !*r))
 640                 return 0;
 641
 642         return *r == data;
 643 }
 644
 645 static void devm_devfreq_dev_release(struct device *dev, void *res)
 646 {
 647         devfreq_remove_device(*(struct devfreq **)res);
 648 }
 649
 650 /**
 651  * devm_devfreq_add_device() - Resource-managed devfreq_add_device()
 652  * @dev:        the device to add devfreq feature.
 653  * @profile:    device-specific profile to run devfreq.
 654  * @governor_name:      name of the policy to choose frequency.
 655  * @data:       private data for the governor. The devfreq framework does not
 656  *              touch this value.
 657  *
 658  * This function manages automatically the memory of devfreq device using device
 659  * resource management and simplify the free operation for memory of devfreq
 660  * device.
 661  */
 662 struct devfreq *devm_devfreq_add_device(struct device *dev,
 663                                         struct devfreq_dev_profile *profile,
 664                                         const char *governor_name,
 665                                         void *data)
 666 {
 667         struct devfreq **ptr, *devfreq;
 668
 669         ptr = devres_alloc(devm_devfreq_dev_release, sizeof(*ptr), GFP_KERNEL);
 670         if (!ptr)
 671                 return ERR_PTR(-ENOMEM);
 672
 673         devfreq = devfreq_add_device(dev, profile, governor_name, data);
 674         if (IS_ERR(devfreq)) {
 675                 devres_free(ptr);
 676                 return ERR_PTR(-ENOMEM);
 677         }
 678
 679         *ptr = devfreq;
 680         devres_add(dev, ptr);
 681
 682         return devfreq;
 683 }
 684 EXPORT_SYMBOL(devm_devfreq_add_device);
 685
 686 #ifdef CONFIG_OF
 687 /*
 688  * devfreq_get_devfreq_by_phandle - Get the devfreq device from devicetree
 689  * @dev - instance to the given device
 690  * @index - index into list of devfreq
 691  *
 692  * return the instance of devfreq device
 693  */
 694 struct devfreq *devfreq_get_devfreq_by_phandle(struct device *dev, int index)
 695 {
 696         struct device_node *node;
 697         struct devfreq *devfreq;
 698
 699         if (!dev)
 700                 return ERR_PTR(-EINVAL);
 701
 702         if (!dev->of_node)
 703                 return ERR_PTR(-EINVAL);
 704
 705         node = of_parse_phandle(dev->of_node, "devfreq", index);
 706         if (!node)
 707                 return ERR_PTR(-ENODEV);
 708
 709         mutex_lock(&devfreq_list_lock);
 710         list_for_each_entry(devfreq, &devfreq_list, node) {
 711                 if (devfreq->dev.parent
 712                         && devfreq->dev.parent->of_node == node) {
 713                         mutex_unlock(&devfreq_list_lock);
 714                         of_node_put(node);
 715                         return devfreq;
 716                 }
 717         }
 718         mutex_unlock(&devfreq_list_lock);
 719         of_node_put(node);
 720
 721         return ERR_PTR(-EPROBE_DEFER);
 722 }
 723 #else
 724 struct devfreq *devfreq_get_devfreq_by_phandle(struct device *dev, int index)
 725 {
 726         return ERR_PTR(-ENODEV);
 727 }
 728 #endif /* CONFIG_OF */
 729 EXPORT_SYMBOL_GPL(devfreq_get_devfreq_by_phandle);
 730
 731 /**
 732  * devm_devfreq_remove_device() - Resource-managed devfreq_remove_device()
 733  * @dev:        the device to add devfreq feature.
 734  * @devfreq:    the devfreq instance to be removed
 735  */
 736 void devm_devfreq_remove_device(struct device *dev, struct devfreq *devfreq)
 737 {
 738         WARN_ON(devres_release(dev, devm_devfreq_dev_release,
 739                                devm_devfreq_dev_match, devfreq));
 740 }
 741 EXPORT_SYMBOL(devm_devfreq_remove_device);
 742
 743 /**
 744  * devfreq_suspend_device() - Suspend devfreq of a device.
 745  * @devfreq: the devfreq instance to be suspended
 746  *
 747  * This function is intended to be called by the pm callbacks
 748  * (e.g., runtime_suspend, suspend) of the device driver that
 749  * holds the devfreq.
 750  */
 751 int devfreq_suspend_device(struct devfreq *devfreq)
 752 {
 753         if (!devfreq)
 754                 return -EINVAL;
 755
 756         if (!devfreq->governor)
 757                 return 0;
 758
 759         return devfreq->governor->event_handler(devfreq,
 760                                 DEVFREQ_GOV_SUSPEND, NULL);
 761 }
 762 EXPORT_SYMBOL(devfreq_suspend_device);
 763
 764 /**
 765  * devfreq_resume_device() - Resume devfreq of a device.
 766  * @devfreq: the devfreq instance to be resumed
 767  *
 768  * This function is intended to be called by the pm callbacks
 769  * (e.g., runtime_resume, resume) of the device driver that
 770  * holds the devfreq.
 771  */
 772 int devfreq_resume_device(struct devfreq *devfreq)
 773 {
 774         if (!devfreq)
 775                 return -EINVAL;
 776
 777         if (!devfreq->governor)
 778                 return 0;
 779
 780         return devfreq->governor->event_handler(devfreq,
 781                                 DEVFREQ_GOV_RESUME, NULL);
 782 }
 783 EXPORT_SYMBOL(devfreq_resume_device);
 784
 785 /**
 786  * devfreq_add_governor() - Add devfreq governor
 787  * @governor:   the devfreq governor to be added
 788  */
 789 int devfreq_add_governor(struct devfreq_governor *governor)
 790 {
 791         struct devfreq_governor *g;
 792         struct devfreq *devfreq;
 793         int err = 0;
 794
 795         if (!governor) {
 796                 pr_err("%s: Invalid parameters.\n", __func__);
 797                 return -EINVAL;
 798         }
 799
 800         mutex_lock(&devfreq_list_lock);
 801         g = find_devfreq_governor(governor->name);
 802         if (!IS_ERR(g)) {
 803                 pr_err("%s: governor %s already registered\n", __func__,
 804                        g->name);
 805                 err = -EINVAL;
 806                 goto err_out;
 807         }
 808
 809         list_add(&governor->node, &devfreq_governor_list);
 810
 811         list_for_each_entry(devfreq, &devfreq_list, node) {
 812                 int ret = 0;
 813                 struct device *dev = devfreq->dev.parent;
 814
 815                 if (!strncmp(devfreq->governor_name, governor->name,
 816                              DEVFREQ_NAME_LEN)) {
 817                         /* The following should never occur */
 818                         if (devfreq->governor) {
 819                                 dev_warn(dev,
 820                                          "%s: Governor %s already present\n",
 821                                          __func__, devfreq->governor->name);
 822                                 ret = devfreq->governor->event_handler(devfreq,
 823                                                         DEVFREQ_GOV_STOP, NULL);
 824                                 if (ret) {
 825                                         dev_warn(dev,
 826                                                  "%s: Governor %s stop = %d\n",
 827                                                  __func__,
 828                                                  devfreq->governor->name, ret);
 829                                 }
 830                                 /* Fall through */
 831                         }
 832                         devfreq->governor = governor;
 833                         ret = devfreq->governor->event_handler(devfreq,
 834                                                 DEVFREQ_GOV_START, NULL);
 835                         if (ret) {
 836                                 dev_warn(dev, "%s: Governor %s start=%d\n",
 837                                          __func__, devfreq->governor->name,
 838                                          ret);
 839                         }
 840                 }
 841         }
 842
 843 err_out:
 844         mutex_unlock(&devfreq_list_lock);
 845
 846         return err;
 847 }
 848 EXPORT_SYMBOL(devfreq_add_governor);
 849
 850 /**
 851  * devfreq_remove_governor() - Remove devfreq feature from a device.
 852  * @governor:   the devfreq governor to be removed
 853  */
 854 int devfreq_remove_governor(struct devfreq_governor *governor)
 855 {
 856         struct devfreq_governor *g;
 857         struct devfreq *devfreq;
 858         int err = 0;
 859
 860         if (!governor) {
 861                 pr_err("%s: Invalid parameters.\n", __func__);
 862                 return -EINVAL;
 863         }
 864
 865         mutex_lock(&devfreq_list_lock);
 866         g = find_devfreq_governor(governor->name);
 867         if (IS_ERR(g)) {
 868                 pr_err("%s: governor %s not registered\n", __func__,
 869                        governor->name);
 870                 err = PTR_ERR(g);
 871                 goto err_out;
 872         }
 873         list_for_each_entry(devfreq, &devfreq_list, node) {
 874                 int ret;
 875                 struct device *dev = devfreq->dev.parent;
 876
 877                 if (!strncmp(devfreq->governor_name, governor->name,
 878                              DEVFREQ_NAME_LEN)) {
 879                         /* we should have a devfreq governor! */
 880                         if (!devfreq->governor) {
 881                                 dev_warn(dev, "%s: Governor %s NOT present\n",
 882                                          __func__, governor->name);
 883                                 continue;
 884                                 /* Fall through */
 885                         }
 886                         ret = devfreq->governor->event_handler(devfreq,
 887                                                 DEVFREQ_GOV_STOP, NULL);
 888                         if (ret) {
 889                                 dev_warn(dev, "%s: Governor %s stop=%d\n",
 890                                          __func__, devfreq->governor->name,
 891                                          ret);
 892                         }
 893                         devfreq->governor = NULL;
 894                 }
 895         }
 896
 897         list_del(&governor->node);
 898 err_out:
 899         mutex_unlock(&devfreq_list_lock);
 900
 901         return err;
 902 }
 903 EXPORT_SYMBOL(devfreq_remove_governor);
 904
 905 static ssize_t governor_show(struct device *dev,
 906                              struct device_attribute *attr, char *buf)
 907 {
 908         if (!to_devfreq(dev)->governor)
 909                 return -EINVAL;
 910
 911         return sprintf(buf, "%s\n", to_devfreq(dev)->governor->name);
 912 }
 913
 914 static ssize_t governor_store(struct device *dev, struct device_attribute *attr,
 915                               const char *buf, size_t count)
 916 {
 917         struct devfreq *df = to_devfreq(dev);
 918         int ret;
 919         char str_governor[DEVFREQ_NAME_LEN + 1];
 920         struct devfreq_governor *governor;
 921
 922         ret = sscanf(buf, "%" __stringify(DEVFREQ_NAME_LEN) "s", str_governor);
 923         if (ret != 1)
 924                 return -EINVAL;
 925
 926         mutex_lock(&devfreq_list_lock);
 927         governor = find_devfreq_governor(str_governor);
 928         if (IS_ERR(governor)) {
 929                 ret = PTR_ERR(governor);
 930                 goto out;
 931         }
 932         if (df->governor == governor) {
 933                 ret = 0;
 934                 goto out;
 935         } else if (df->governor->immutable || governor->immutable) {
 936                 ret = -EINVAL;
 937                 goto out;
 938         }
 939
 940         if (df->governor) {
 941                 ret = df->governor->event_handler(df, DEVFREQ_GOV_STOP, NULL);
 942                 if (ret) {
 943                         dev_warn(dev, "%s: Governor %s not stopped(%d)\n",
 944                                  __func__, df->governor->name, ret);
 945                         goto out;
 946                 }
 947         }
 948         df->governor = governor;
 949         strncpy(df->governor_name, governor->name, DEVFREQ_NAME_LEN);
 950         ret = df->governor->event_handler(df, DEVFREQ_GOV_START, NULL);
 951         if (ret)
 952                 dev_warn(dev, "%s: Governor %s not started(%d)\n",
 953                          __func__, df->governor->name, ret);
 954 out:
 955         mutex_unlock(&devfreq_list_lock);
 956
 957         if (!ret)
 958                 ret = count;
 959         return ret;
 960 }
 961 static DEVICE_ATTR_RW(governor);
 962
 963 static ssize_t available_governors_show(struct device *d,
 964                                         struct device_attribute *attr,
 965                                         char *buf)
 966 {
 967         struct devfreq *df = to_devfreq(d);
 968         ssize_t count = 0;
 969
 970         mutex_lock(&devfreq_list_lock);
 971
 972         /*
 973          * The devfreq with immutable governor (e.g., passive) shows
 974          * only own governor.
 975          */
 976         if (df->governor->immutable) {
 977                 count = scnprintf(&buf[count], DEVFREQ_NAME_LEN,
 978                                    "%s ", df->governor_name);
 979         /*
 980          * The devfreq device shows the registered governor except for
 981          * immutable governors such as passive governor .
 982          */
 983         } else {
 984                 struct devfreq_governor *governor;
 985
 986                 list_for_each_entry(governor, &devfreq_governor_list, node) {
 987                         if (governor->immutable)
 988                                 continue;
 989                         count += scnprintf(&buf[count], (PAGE_SIZE - count - 2),
 990                                            "%s ", governor->name);
 991                 }
 992         }
 993
 994         mutex_unlock(&devfreq_list_lock);
 995
 996         /* Truncate the trailing space */
 997         if (count)
 998                 count--;
 999
1000         count += sprintf(&buf[count], "\n");
1001
1002         return count;
1003 }
1004 static DEVICE_ATTR_RO(available_governors);
1005
1006 static ssize_t cur_freq_show(struct device *dev, struct device_attribute *attr,
1007                              char *buf)
1008 {
1009         unsigned long freq;
1010         struct devfreq *devfreq = to_devfreq(dev);
1011
1012         if (devfreq->profile->get_cur_freq &&
1013                 !devfreq->profile->get_cur_freq(devfreq->dev.parent, &freq))
1014                 return sprintf(buf, "%lu\n", freq);
1015
1016         return sprintf(buf, "%lu\n", devfreq->previous_freq);
1017 }
1018 static DEVICE_ATTR_RO(cur_freq);
1019
1020 static ssize_t target_freq_show(struct device *dev,
1021                                 struct device_attribute *attr, char *buf)
1022 {
1023         return sprintf(buf, "%lu\n", to_devfreq(dev)->previous_freq);
1024 }
1025 static DEVICE_ATTR_RO(target_freq);
1026
1027 static ssize_t polling_interval_show(struct device *dev,
1028                                      struct device_attribute *attr, char *buf)
1029 {
1030         return sprintf(buf, "%d\n", to_devfreq(dev)->profile->polling_ms);
1031 }
1032
1033 static ssize_t polling_interval_store(struct device *dev,
1034                                       struct device_attribute *attr,
1035                                       const char *buf, size_t count)
1036 {
1037         struct devfreq *df = to_devfreq(dev);
1038         unsigned int value;
1039         int ret;
1040
1041         if (!df->governor)
1042                 return -EINVAL;
1043
1044         ret = sscanf(buf, "%u", &value);
1045         if (ret != 1)
1046                 return -EINVAL;
1047
1048         df->governor->event_handler(df, DEVFREQ_GOV_INTERVAL, &value);
1049         ret = count;
1050
1051         return ret;
1052 }
1053 static DEVICE_ATTR_RW(polling_interval);
1054
1055 static ssize_t min_freq_store(struct device *dev, struct device_attribute *attr,
1056                               const char *buf, size_t count)
1057 {
1058         struct devfreq *df = to_devfreq(dev);
1059         unsigned long value;
1060         int ret;
1061         unsigned long max;
1062
1063         ret = sscanf(buf, "%lu", &value);
1064         if (ret != 1)
1065                 return -EINVAL;
1066
1067         mutex_lock(&df->lock);
1068         max = df->max_freq;
1069         if (value && max && value > max) {
1070                 ret = -EINVAL;
1071                 goto unlock;
1072         }
1073
1074         df->min_freq = value;
1075         update_devfreq(df);
1076         ret = count;
1077 unlock:
1078         mutex_unlock(&df->lock);
1079         return ret;
1080 }
1081
1082 static ssize_t max_freq_store(struct device *dev, struct device_attribute *attr,
1083                               const char *buf, size_t count)
1084 {
1085         struct devfreq *df = to_devfreq(dev);
1086         unsigned long value;
1087         int ret;
1088         unsigned long min;
1089
1090         ret = sscanf(buf, "%lu", &value);
1091         if (ret != 1)
1092                 return -EINVAL;
1093
1094         mutex_lock(&df->lock);
1095         min = df->min_freq;
1096         if (value && min && value < min) {
1097                 ret = -EINVAL;
1098                 goto unlock;
1099         }
1100
1101         df->max_freq = value;
1102         update_devfreq(df);
1103         ret = count;
1104 unlock:
1105         mutex_unlock(&df->lock);
1106         return ret;
1107 }
1108
1109 #define show_one(name)                                          \
1110 static ssize_t name##_show                                      \
1111 (struct device *dev, struct device_attribute *attr, char *buf)  \
1112 {                                                               \
1113         return sprintf(buf, "%lu\n", to_devfreq(dev)->name);    \
1114 }
1115 show_one(min_freq);
1116 show_one(max_freq);
1117
1118 static DEVICE_ATTR_RW(min_freq);
1119 static DEVICE_ATTR_RW(max_freq);
1120
1121 static ssize_t available_frequencies_show(struct device *d,
1122                                           struct device_attribute *attr,
1123                                           char *buf)
1124 {
1125         struct devfreq *df = to_devfreq(d);
1126         struct device *dev = df->dev.parent;
1127         struct dev_pm_opp *opp;
1128         ssize_t count = 0;
1129         unsigned long freq = 0;
1130
1131         rcu_read_lock();
1132         do {
1133                 opp = dev_pm_opp_find_freq_ceil(dev, &freq);
1134                 if (IS_ERR(opp))
1135                         break;
1136
1137                 count += scnprintf(&buf[count], (PAGE_SIZE - count - 2),
1138                                    "%lu ", freq);
1139                 freq++;
1140         } while (1);
1141         rcu_read_unlock();
1142
1143         /* Truncate the trailing space */
1144         if (count)
1145                 count--;
1146
1147         count += sprintf(&buf[count], "\n");
1148
1149         return count;
1150 }
1151 static DEVICE_ATTR_RO(available_frequencies);
1152
1153 static ssize_t trans_stat_show(struct device *dev,
1154                                struct device_attribute *attr, char *buf)
1155 {
1156         struct devfreq *devfreq = to_devfreq(dev);
1157         ssize_t len;
1158         int i, j;
1159         unsigned int max_state = devfreq->profile->max_state;
1160
1161         if (!devfreq->stop_polling &&
1162                         devfreq_update_status(devfreq, devfreq->previous_freq))
1163                 return 0;
1164         if (max_state == 0)
1165                 return sprintf(buf, "Not Supported.\n");
1166
1167         len = sprintf(buf, "     From  :   To\n");
1168         len += sprintf(buf + len, "           :");
1169         for (i = 0; i < max_state; i++)
1170                 len += sprintf(buf + len, "%10lu",
1171                                 devfreq->profile->freq_table[i]);
1172
1173         len += sprintf(buf + len, "   time(ms)\n");
1174
1175         for (i = 0; i < max_state; i++) {
1176                 if (devfreq->profile->freq_table[i]
1177                                         == devfreq->previous_freq) {
1178                         len += sprintf(buf + len, "*");
1179                 } else {
1180                         len += sprintf(buf + len, " ");
1181                 }
1182                 len += sprintf(buf + len, "%10lu:",
1183                                 devfreq->profile->freq_table[i]);
1184                 for (j = 0; j < max_state; j++)
1185                         len += sprintf(buf + len, "%10u",
1186                                 devfreq->trans_table[(i * max_state) + j]);
1187                 len += sprintf(buf + len, "%10u\n",
1188                         jiffies_to_msecs(devfreq->time_in_state[i]));
1189         }
1190
1191         len += sprintf(buf + len, "Total transition : %u\n",
1192                                         devfreq->total_trans);
1193         return len;
1194 }
1195 static DEVICE_ATTR_RO(trans_stat);
1196
1197 static struct attribute *devfreq_attrs[] = {
1198         &dev_attr_governor.attr,
1199         &dev_attr_available_governors.attr,
1200         &dev_attr_cur_freq.attr,
1201         &dev_attr_available_frequencies.attr,
1202         &dev_attr_target_freq.attr,
1203         &dev_attr_polling_interval.attr,
1204         &dev_attr_min_freq.attr,
1205         &dev_attr_max_freq.attr,
1206         &dev_attr_trans_stat.attr,
1207         NULL,
1208 };
1209 ATTRIBUTE_GROUPS(devfreq);
1210
1211 static int __init devfreq_init(void)
1212 {
1213         devfreq_class = class_create(THIS_MODULE, "devfreq");
1214         if (IS_ERR(devfreq_class)) {
1215                 pr_err("%s: couldn't create class\n", __FILE__);
1216                 return PTR_ERR(devfreq_class);
1217         }
1218
1219         devfreq_wq = create_freezable_workqueue("devfreq_wq");
1220         if (!devfreq_wq) {
1221                 class_destroy(devfreq_class);
1222                 pr_err("%s: couldn't create workqueue\n", __FILE__);
1223                 return -ENOMEM;
1224         }
1225         devfreq_class->dev_groups = devfreq_groups;
1226
1227         return 0;
1228 }
1229 subsys_initcall(devfreq_init);
1230
1231 /*
1232  * The followings are helper functions for devfreq user device drivers with
1233  * OPP framework.
1234  */
1235
1236 /**
1237  * devfreq_recommended_opp() - Helper function to get proper OPP for the
1238  *                           freq value given to target callback.
1239  * @dev:        The devfreq user device. (parent of devfreq)
1240  * @freq:       The frequency given to target function
1241  * @flags:      Flags handed from devfreq framework.
1242  *
1243  * Locking: This function must be called under rcu_read_lock(). opp is a rcu
1244  * protected pointer. The reason for the same is that the opp pointer which is
1245  * returned will remain valid for use with opp_get_{voltage, freq} only while
1246  * under the locked area. The pointer returned must be used prior to unlocking
1247  * with rcu_read_unlock() to maintain the integrity of the pointer.
1248  */
1249 struct dev_pm_opp *devfreq_recommended_opp(struct device *dev,
1250                                            unsigned long *freq,
1251                                            u32 flags)
1252 {
1253         struct dev_pm_opp *opp;
1254
1255         if (flags & DEVFREQ_FLAG_LEAST_UPPER_BOUND) {
1256                 /* The freq is an upper bound. opp should be lower */
1257                 opp = dev_pm_opp_find_freq_floor(dev, freq);
1258
1259                 /* If not available, use the closest opp */
1260                 if (opp == ERR_PTR(-ERANGE))
1261                         opp = dev_pm_opp_find_freq_ceil(dev, freq);
1262         } else {
1263                 /* The freq is an lower bound. opp should be higher */
1264                 opp = dev_pm_opp_find_freq_ceil(dev, freq);
1265
1266                 /* If not available, use the closest opp */
1267                 if (opp == ERR_PTR(-ERANGE))
1268                         opp = dev_pm_opp_find_freq_floor(dev, freq);
1269         }
1270
1271         return opp;
1272 }
1273 EXPORT_SYMBOL(devfreq_recommended_opp);
1274
1275 /**
1276  * devfreq_register_opp_notifier() - Helper function to get devfreq notified
1277  *                                 for any changes in the OPP availability
1278  *                                 changes
1279  * @dev:        The devfreq user device. (parent of devfreq)
1280  * @devfreq:    The devfreq object.
1281  */
1282 int devfreq_register_opp_notifier(struct device *dev, struct devfreq *devfreq)
1283 {
1284         struct srcu_notifier_head *nh;
1285         int ret = 0;
1286
1287         rcu_read_lock();
1288         nh = dev_pm_opp_get_notifier(dev);
1289         if (IS_ERR(nh))
1290                 ret = PTR_ERR(nh);
1291         rcu_read_unlock();
1292         if (!ret)
1293                 ret = srcu_notifier_chain_register(nh, &devfreq->nb);
1294
1295         return ret;
1296 }
1297 EXPORT_SYMBOL(devfreq_register_opp_notifier);
1298
1299 /**
1300  * devfreq_unregister_opp_notifier() - Helper function to stop getting devfreq
1301  *                                   notified for any changes in the OPP
1302  *                                   availability changes anymore.
1303  * @dev:        The devfreq user device. (parent of devfreq)
1304  * @devfreq:    The devfreq object.
1305  *
1306  * At exit() callback of devfreq_dev_profile, this must be included if
1307  * devfreq_recommended_opp is used.
1308  */
1309 int devfreq_unregister_opp_notifier(struct device *dev, struct devfreq *devfreq)
1310 {
1311         struct srcu_notifier_head *nh;
1312         int ret = 0;
1313
1314         rcu_read_lock();
1315         nh = dev_pm_opp_get_notifier(dev);
1316         if (IS_ERR(nh))
1317                 ret = PTR_ERR(nh);
1318         rcu_read_unlock();
1319         if (!ret)
1320                 ret = srcu_notifier_chain_unregister(nh, &devfreq->nb);
1321
1322         return ret;
1323 }
1324 EXPORT_SYMBOL(devfreq_unregister_opp_notifier);
1325
1326 static void devm_devfreq_opp_release(struct device *dev, void *res)
1327 {
1328         devfreq_unregister_opp_notifier(dev, *(struct devfreq **)res);
1329 }
1330
1331 /**
1332  * devm_ devfreq_register_opp_notifier()
1333  *              - Resource-managed devfreq_register_opp_notifier()
1334  * @dev:        The devfreq user device. (parent of devfreq)
1335  * @devfreq:    The devfreq object.
1336  */
1337 int devm_devfreq_register_opp_notifier(struct device *dev,
1338                                        struct devfreq *devfreq)
1339 {
1340         struct devfreq **ptr;
1341         int ret;
1342
1343         ptr = devres_alloc(devm_devfreq_opp_release, sizeof(*ptr), GFP_KERNEL);
1344         if (!ptr)
1345                 return -ENOMEM;
1346
1347         ret = devfreq_register_opp_notifier(dev, devfreq);
1348         if (ret) {
1349                 devres_free(ptr);
1350                 return ret;
1351         }
1352
1353         *ptr = devfreq;
1354         devres_add(dev, ptr);
1355
1356         return 0;
1357 }
1358 EXPORT_SYMBOL(devm_devfreq_register_opp_notifier);
1359
1360 /**
1361  * devm_devfreq_unregister_opp_notifier()
1362  *              - Resource-managed devfreq_unregister_opp_notifier()
1363  * @dev:        The devfreq user device. (parent of devfreq)
1364  * @devfreq:    The devfreq object.
1365  */
1366 void devm_devfreq_unregister_opp_notifier(struct device *dev,
1367                                          struct devfreq *devfreq)
1368 {
1369         WARN_ON(devres_release(dev, devm_devfreq_opp_release,
1370                                devm_devfreq_dev_match, devfreq));
1371 }
1372 EXPORT_SYMBOL(devm_devfreq_unregister_opp_notifier);
1373
1374 /**
1375  * devfreq_register_notifier() - Register a driver with devfreq
1376  * @devfreq:    The devfreq object.
1377  * @nb:         The notifier block to register.
1378  * @list:       DEVFREQ_TRANSITION_NOTIFIER.
1379  */
1380 int devfreq_register_notifier(struct devfreq *devfreq,
1381                                 struct notifier_block *nb,
1382                                 unsigned int list)
1383 {
1384         int ret = 0;
1385
1386         if (!devfreq)
1387                 return -EINVAL;
1388
1389         switch (list) {
1390         case DEVFREQ_TRANSITION_NOTIFIER:
1391                 ret = srcu_notifier_chain_register(
1392                                 &devfreq->transition_notifier_list, nb);
1393                 break;
1394         default:
1395                 ret = -EINVAL;
1396         }
1397
1398         return ret;
1399 }
1400 EXPORT_SYMBOL(devfreq_register_notifier);
1401
1402 /*
1403  * devfreq_unregister_notifier() - Unregister a driver with devfreq
1404  * @devfreq:    The devfreq object.
1405  * @nb:         The notifier block to be unregistered.
1406  * @list:       DEVFREQ_TRANSITION_NOTIFIER.
1407  */
1408 int devfreq_unregister_notifier(struct devfreq *devfreq,
1409                                 struct notifier_block *nb,
1410                                 unsigned int list)
1411 {
1412         int ret = 0;
1413
1414         if (!devfreq)
1415                 return -EINVAL;
1416
1417         switch (list) {
1418         case DEVFREQ_TRANSITION_NOTIFIER:
1419                 ret = srcu_notifier_chain_unregister(
1420                                 &devfreq->transition_notifier_list, nb);
1421                 break;
1422         default:
1423                 ret = -EINVAL;
1424         }
1425
1426         return ret;
1427 }
1428 EXPORT_SYMBOL(devfreq_unregister_notifier);
1429
1430 struct devfreq_notifier_devres {
1431         struct devfreq *devfreq;
1432         struct notifier_block *nb;
1433         unsigned int list;
1434 };
1435
1436 static void devm_devfreq_notifier_release(struct device *dev, void *res)
1437 {
1438         struct devfreq_notifier_devres *this = res;
1439
1440         devfreq_unregister_notifier(this->devfreq, this->nb, this->list);
1441 }
1442
1443 /**
1444  * devm_devfreq_register_notifier()
1445         - Resource-managed devfreq_register_notifier()
1446  * @dev:        The devfreq user device. (parent of devfreq)
1447  * @devfreq:    The devfreq object.
1448  * @nb:         The notifier block to be unregistered.
1449  * @list:       DEVFREQ_TRANSITION_NOTIFIER.
1450  */
1451 int devm_devfreq_register_notifier(struct device *dev,
1452                                 struct devfreq *devfreq,
1453                                 struct notifier_block *nb,
1454                                 unsigned int list)
1455 {
1456         struct devfreq_notifier_devres *ptr;
1457         int ret;
1458
1459         ptr = devres_alloc(devm_devfreq_notifier_release, sizeof(*ptr),
1460                                 GFP_KERNEL);
1461         if (!ptr)
1462                 return -ENOMEM;
1463
1464         ret = devfreq_register_notifier(devfreq, nb, list);
1465         if (ret) {
1466                 devres_free(ptr);
1467                 return ret;
1468         }
1469
1470         ptr->devfreq = devfreq;
1471         ptr->nb = nb;
1472         ptr->list = list;
1473         devres_add(dev, ptr);
1474
1475         return 0;
1476 }
1477 EXPORT_SYMBOL(devm_devfreq_register_notifier);
1478
1479 /**
1480  * devm_devfreq_unregister_notifier()
1481         - Resource-managed devfreq_unregister_notifier()
1482  * @dev:        The devfreq user device. (parent of devfreq)
1483  * @devfreq:    The devfreq object.
1484  * @nb:         The notifier block to be unregistered.
1485  * @list:       DEVFREQ_TRANSITION_NOTIFIER.
1486  */
1487 void devm_devfreq_unregister_notifier(struct device *dev,
1488                                 struct devfreq *devfreq,
1489                                 struct notifier_block *nb,
1490                                 unsigned int list)
1491 {
1492         WARN_ON(devres_release(dev, devm_devfreq_notifier_release,
1493                                devm_devfreq_dev_match, devfreq));
1494 }
1495 EXPORT_SYMBOL(devm_devfreq_unregister_notifier);