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/kmod.h>
  15 #include <linux/sched.h>
  16 #include <linux/errno.h>
  17 #include <linux/err.h>
  18 #include <linux/init.h>
  19 #include <linux/export.h>
  20 #include <linux/slab.h>
  21 #include <linux/stat.h>
  22 #include <linux/pm_opp.h>
  23 #include <linux/devfreq.h>
  24 #include <linux/workqueue.h>
  25 #include <linux/platform_device.h>
  26 #include <linux/list.h>
  27 #include <linux/printk.h>
  28 #include <linux/hrtimer.h>
  29 #include <linux/of.h>
  30 #include "governor.h"
  31
  32 static struct class *devfreq_class;
  33
  34 /*
  35  * devfreq core provides delayed work based load monitoring helper
  36  * functions. Governors can use these or can implement their own
  37  * monitoring mechanism.
  38  */
  39 static struct workqueue_struct *devfreq_wq;
  40
  41 /* The list of all device-devfreq governors */
  42 static LIST_HEAD(devfreq_governor_list);
  43 /* The list of all device-devfreq */
  44 static LIST_HEAD(devfreq_list);
  45 static DEFINE_MUTEX(devfreq_list_lock);
  46
  47 /**
  48  * find_device_devfreq() - find devfreq struct using device pointer
  49  * @dev:        device pointer used to lookup device devfreq.
  50  *
  51  * Search the list of device devfreqs and return the matched device's
  52  * devfreq info. devfreq_list_lock should be held by the caller.
  53  */
  54 static struct devfreq *find_device_devfreq(struct device *dev)
  55 {
  56         struct devfreq *tmp_devfreq;
  57
  58         if (IS_ERR_OR_NULL(dev)) {
  59                 pr_err("DEVFREQ: %s: Invalid parameters\n", __func__);
  60                 return ERR_PTR(-EINVAL);
  61         }
  62         WARN(!mutex_is_locked(&devfreq_list_lock),
  63              "devfreq_list_lock must be locked.");
  64
  65         list_for_each_entry(tmp_devfreq, &devfreq_list, node) {
  66                 if (tmp_devfreq->dev.parent == dev)
  67                         return tmp_devfreq;
  68         }
  69
  70         return ERR_PTR(-ENODEV);
  71 }
  72
  73 static unsigned long find_available_min_freq(struct devfreq *devfreq)
  74 {
  75         struct dev_pm_opp *opp;
  76         unsigned long min_freq = 0;
  77
  78         opp = dev_pm_opp_find_freq_ceil(devfreq->dev.parent, &min_freq);
  79         if (IS_ERR(opp))
  80                 min_freq = 0;
  81         else
  82                 dev_pm_opp_put(opp);
  83
  84         return min_freq;
  85 }
  86
  87 static unsigned long find_available_max_freq(struct devfreq *devfreq)
  88 {
  89         struct dev_pm_opp *opp;
  90         unsigned long max_freq = ULONG_MAX;
  91
  92         opp = dev_pm_opp_find_freq_floor(devfreq->dev.parent, &max_freq);
  93         if (IS_ERR(opp))
  94                 max_freq = 0;
  95         else
  96                 dev_pm_opp_put(opp);
  97
  98         return max_freq;
  99 }
 100
 101 /**
 102  * devfreq_get_freq_level() - Lookup freq_table for the frequency
 103  * @devfreq:    the devfreq instance
 104  * @freq:       the target frequency
 105  */
 106 static int devfreq_get_freq_level(struct devfreq *devfreq, unsigned long freq)
 107 {
 108         int lev;
 109
 110         for (lev = 0; lev < devfreq->profile->max_state; lev++)
 111                 if (freq == devfreq->profile->freq_table[lev])
 112                         return lev;
 113
 114         return -EINVAL;
 115 }
 116
 117 static int set_freq_table(struct devfreq *devfreq)
 118 {
 119         struct devfreq_dev_profile *profile = devfreq->profile;
 120         struct dev_pm_opp *opp;
 121         unsigned long freq;
 122         int i, count;
 123
 124         /* Initialize the freq_table from OPP table */
 125         count = dev_pm_opp_get_opp_count(devfreq->dev.parent);
 126         if (count <= 0)
 127                 return -EINVAL;
 128
 129         profile->max_state = count;
 130         profile->freq_table = devm_kcalloc(devfreq->dev.parent,
 131                                         profile->max_state,
 132                                         sizeof(*profile->freq_table),
 133                                         GFP_KERNEL);
 134         if (!profile->freq_table) {
 135                 profile->max_state = 0;
 136                 return -ENOMEM;
 137         }
 138
 139         for (i = 0, freq = 0; i < profile->max_state; i++, freq++) {
 140                 opp = dev_pm_opp_find_freq_ceil(devfreq->dev.parent, &freq);
 141                 if (IS_ERR(opp)) {
 142                         devm_kfree(devfreq->dev.parent, profile->freq_table);
 143                         profile->max_state = 0;
 144                         return PTR_ERR(opp);
 145                 }
 146                 dev_pm_opp_put(opp);
 147                 profile->freq_table[i] = freq;
 148         }
 149
 150         return 0;
 151 }
 152
 153 /**
 154  * devfreq_update_status() - Update statistics of devfreq behavior
 155  * @devfreq:    the devfreq instance
 156  * @freq:       the update target frequency
 157  */
 158 int devfreq_update_status(struct devfreq *devfreq, unsigned long freq)
 159 {
 160         int lev, prev_lev, ret = 0;
 161         unsigned long cur_time;
 162
 163         cur_time = jiffies;
 164
 165         /* Immediately exit if previous_freq is not initialized yet. */
 166         if (!devfreq->previous_freq)
 167                 goto out;
 168
 169         prev_lev = devfreq_get_freq_level(devfreq, devfreq->previous_freq);
 170         if (prev_lev < 0) {
 171                 ret = prev_lev;
 172                 goto out;
 173         }
 174
 175         devfreq->time_in_state[prev_lev] +=
 176                          cur_time - devfreq->last_stat_updated;
 177
 178         lev = devfreq_get_freq_level(devfreq, freq);
 179         if (lev < 0) {
 180                 ret = lev;
 181                 goto out;
 182         }
 183
 184         if (lev != prev_lev) {
 185                 devfreq->trans_table[(prev_lev *
 186                                 devfreq->profile->max_state) + lev]++;
 187                 devfreq->total_trans++;
 188         }
 189
 190 out:
 191         devfreq->last_stat_updated = cur_time;
 192         return ret;
 193 }
 194 EXPORT_SYMBOL(devfreq_update_status);
 195
 196 /**
 197  * find_devfreq_governor() - find devfreq governor from name
 198  * @name:       name of the governor
 199  *
 200  * Search the list of devfreq governors and return the matched
 201  * governor's pointer. devfreq_list_lock should be held by the caller.
 202  */
 203 static struct devfreq_governor *find_devfreq_governor(const char *name)
 204 {
 205         struct devfreq_governor *tmp_governor;
 206
 207         if (IS_ERR_OR_NULL(name)) {
 208                 pr_err("DEVFREQ: %s: Invalid parameters\n", __func__);
 209                 return ERR_PTR(-EINVAL);
 210         }
 211         WARN(!mutex_is_locked(&devfreq_list_lock),
 212              "devfreq_list_lock must be locked.");
 213
 214         list_for_each_entry(tmp_governor, &devfreq_governor_list, node) {
 215                 if (!strncmp(tmp_governor->name, name, DEVFREQ_NAME_LEN))
 216                         return tmp_governor;
 217         }
 218
 219         return ERR_PTR(-ENODEV);
 220 }
 221
 222 /**
 223  * try_then_request_governor() - Try to find the governor and request the
 224  *                               module if is not found.
 225  * @name:       name of the governor
 226  *
 227  * Search the list of devfreq governors and request the module and try again
 228  * if is not found. This can happen when both drivers (the governor driver
 229  * and the driver that call devfreq_add_device) are built as modules.
 230  * devfreq_list_lock should be held by the caller. Returns the matched
 231  * governor's pointer.
 232  */
 233 static struct devfreq_governor *try_then_request_governor(const char *name)
 234 {
 235         struct devfreq_governor *governor;
 236         int err = 0;
 237
 238         if (IS_ERR_OR_NULL(name)) {
 239                 pr_err("DEVFREQ: %s: Invalid parameters\n", __func__);
 240                 return ERR_PTR(-EINVAL);
 241         }
 242         WARN(!mutex_is_locked(&devfreq_list_lock),
 243              "devfreq_list_lock must be locked.");
 244
 245         governor = find_devfreq_governor(name);
 246         if (IS_ERR(governor)) {
 247                 mutex_unlock(&devfreq_list_lock);
 248
 249                 if (!strncmp(name, DEVFREQ_GOV_SIMPLE_ONDEMAND,
 250                              DEVFREQ_NAME_LEN))
 251                         err = request_module("governor_%s", "simpleondemand");
 252                 else
 253                         err = request_module("governor_%s", name);
 254                 /* Restore previous state before return */
 255                 mutex_lock(&devfreq_list_lock);
 256                 if (err)
 257                         return NULL;
 258
 259                 governor = find_devfreq_governor(name);
 260         }
 261
 262         return governor;
 263 }
 264
 265 static int devfreq_notify_transition(struct devfreq *devfreq,
 266                 struct devfreq_freqs *freqs, unsigned int state)
 267 {
 268         if (!devfreq)
 269                 return -EINVAL;
 270
 271         switch (state) {
 272         case DEVFREQ_PRECHANGE:
 273                 srcu_notifier_call_chain(&devfreq->transition_notifier_list,
 274                                 DEVFREQ_PRECHANGE, freqs);
 275                 break;
 276
 277         case DEVFREQ_POSTCHANGE:
 278                 srcu_notifier_call_chain(&devfreq->transition_notifier_list,
 279                                 DEVFREQ_POSTCHANGE, freqs);
 280                 break;
 281         default:
 282                 return -EINVAL;
 283         }
 284
 285         return 0;
 286 }
 287
 288 static int devfreq_set_target(struct devfreq *devfreq, unsigned long new_freq,
 289                               u32 flags)
 290 {
 291         struct devfreq_freqs freqs;
 292         unsigned long cur_freq;
 293         int err = 0;
 294
 295         if (devfreq->profile->get_cur_freq)
 296                 devfreq->profile->get_cur_freq(devfreq->dev.parent, &cur_freq);
 297         else
 298                 cur_freq = devfreq->previous_freq;
 299
 300         freqs.old = cur_freq;
 301         freqs.new = new_freq;
 302         devfreq_notify_transition(devfreq, &freqs, DEVFREQ_PRECHANGE);
 303
 304         err = devfreq->profile->target(devfreq->dev.parent, &new_freq, flags);
 305         if (err) {
 306                 freqs.new = cur_freq;
 307                 devfreq_notify_transition(devfreq, &freqs, DEVFREQ_POSTCHANGE);
 308                 return err;
 309         }
 310
 311         freqs.new = new_freq;
 312         devfreq_notify_transition(devfreq, &freqs, DEVFREQ_POSTCHANGE);
 313
 314         if (devfreq_update_status(devfreq, new_freq))
 315                 dev_err(&devfreq->dev,
 316                         "Couldn't update frequency transition information.\n");
 317
 318         devfreq->previous_freq = new_freq;
 319
 320         if (devfreq->suspend_freq)
 321                 devfreq->resume_freq = cur_freq;
 322
 323         return err;
 324 }
 325
 326 /* Load monitoring helper functions for governors use */
 327
 328 /**
 329  * update_devfreq() - Reevaluate the device and configure frequency.
 330  * @devfreq:    the devfreq instance.
 331  *
 332  * Note: Lock devfreq->lock before calling update_devfreq
 333  *       This function is exported for governors.
 334  */
 335 int update_devfreq(struct devfreq *devfreq)
 336 {
 337         unsigned long freq, min_freq, max_freq;
 338         int err = 0;
 339         u32 flags = 0;
 340
 341         if (!mutex_is_locked(&devfreq->lock)) {
 342                 WARN(true, "devfreq->lock must be locked by the caller.\n");
 343                 return -EINVAL;
 344         }
 345
 346         if (!devfreq->governor)
 347                 return -EINVAL;
 348
 349         /* Reevaluate the proper frequency */
 350         err = devfreq->governor->get_target_freq(devfreq, &freq);
 351         if (err)
 352                 return err;
 353
 354         /*
 355          * Adjust the frequency with user freq, QoS and available freq.
 356          *
 357          * List from the highest priority
 358          * max_freq
 359          * min_freq
 360          */
 361         max_freq = min(devfreq->scaling_max_freq, devfreq->max_freq);
 362         min_freq = max(devfreq->scaling_min_freq, devfreq->min_freq);
 363
 364         if (freq < min_freq) {
 365                 freq = min_freq;
 366                 flags &= ~DEVFREQ_FLAG_LEAST_UPPER_BOUND; /* Use GLB */
 367         }
 368         if (freq > max_freq) {
 369                 freq = max_freq;
 370                 flags |= DEVFREQ_FLAG_LEAST_UPPER_BOUND; /* Use LUB */
 371         }
 372
 373         return devfreq_set_target(devfreq, freq, flags);
 374
 375 }
 376 EXPORT_SYMBOL(update_devfreq);
 377
 378 /**
 379  * devfreq_monitor() - Periodically poll devfreq objects.
 380  * @work:       the work struct used to run devfreq_monitor periodically.
 381  *
 382  */
 383 static void devfreq_monitor(struct work_struct *work)
 384 {
 385         int err;
 386         struct devfreq *devfreq = container_of(work,
 387                                         struct devfreq, work.work);
 388
 389         mutex_lock(&devfreq->lock);
 390         err = update_devfreq(devfreq);
 391         if (err)
 392                 dev_err(&devfreq->dev, "dvfs failed with (%d) error\n", err);
 393
 394         queue_delayed_work(devfreq_wq, &devfreq->work,
 395                                 msecs_to_jiffies(devfreq->profile->polling_ms));
 396         mutex_unlock(&devfreq->lock);
 397 }
 398
 399 /**
 400  * devfreq_monitor_start() - Start load monitoring of devfreq instance
 401  * @devfreq:    the devfreq instance.
 402  *
 403  * Helper function for starting devfreq device load monitoing. By
 404  * default delayed work based monitoring is supported. Function
 405  * to be called from governor in response to DEVFREQ_GOV_START
 406  * event when device is added to devfreq framework.
 407  */
 408 void devfreq_monitor_start(struct devfreq *devfreq)
 409 {
 410         INIT_DEFERRABLE_WORK(&devfreq->work, devfreq_monitor);
 411         if (devfreq->profile->polling_ms)
 412                 queue_delayed_work(devfreq_wq, &devfreq->work,
 413                         msecs_to_jiffies(devfreq->profile->polling_ms));
 414 }
 415 EXPORT_SYMBOL(devfreq_monitor_start);
 416
 417 /**
 418  * devfreq_monitor_stop() - Stop load monitoring of a devfreq instance
 419  * @devfreq:    the devfreq instance.
 420  *
 421  * Helper function to stop devfreq device load monitoing. Function
 422  * to be called from governor in response to DEVFREQ_GOV_STOP
 423  * event when device is removed from devfreq framework.
 424  */
 425 void devfreq_monitor_stop(struct devfreq *devfreq)
 426 {
 427         cancel_delayed_work_sync(&devfreq->work);
 428 }
 429 EXPORT_SYMBOL(devfreq_monitor_stop);
 430
 431 /**
 432  * devfreq_monitor_suspend() - Suspend load monitoring of a devfreq instance
 433  * @devfreq:    the devfreq instance.
 434  *
 435  * Helper function to suspend devfreq device load monitoing. Function
 436  * to be called from governor in response to DEVFREQ_GOV_SUSPEND
 437  * event or when polling interval is set to zero.
 438  *
 439  * Note: Though this function is same as devfreq_monitor_stop(),
 440  * intentionally kept separate to provide hooks for collecting
 441  * transition statistics.
 442  */
 443 void devfreq_monitor_suspend(struct devfreq *devfreq)
 444 {
 445         mutex_lock(&devfreq->lock);
 446         if (devfreq->stop_polling) {
 447                 mutex_unlock(&devfreq->lock);
 448                 return;
 449         }
 450
 451         devfreq_update_status(devfreq, devfreq->previous_freq);
 452         devfreq->stop_polling = true;
 453         mutex_unlock(&devfreq->lock);
 454         cancel_delayed_work_sync(&devfreq->work);
 455 }
 456 EXPORT_SYMBOL(devfreq_monitor_suspend);
 457
 458 /**
 459  * devfreq_monitor_resume() - Resume load monitoring of a devfreq instance
 460  * @devfreq:    the devfreq instance.
 461  *
 462  * Helper function to resume devfreq device load monitoing. Function
 463  * to be called from governor in response to DEVFREQ_GOV_RESUME
 464  * event or when polling interval is set to non-zero.
 465  */
 466 void devfreq_monitor_resume(struct devfreq *devfreq)
 467 {
 468         unsigned long freq;
 469
 470         mutex_lock(&devfreq->lock);
 471         if (!devfreq->stop_polling)
 472                 goto out;
 473
 474         if (!delayed_work_pending(&devfreq->work) &&
 475                         devfreq->profile->polling_ms)
 476                 queue_delayed_work(devfreq_wq, &devfreq->work,
 477                         msecs_to_jiffies(devfreq->profile->polling_ms));
 478
 479         devfreq->last_stat_updated = jiffies;
 480         devfreq->stop_polling = false;
 481
 482         if (devfreq->profile->get_cur_freq &&
 483                 !devfreq->profile->get_cur_freq(devfreq->dev.parent, &freq))
 484                 devfreq->previous_freq = freq;
 485
 486 out:
 487         mutex_unlock(&devfreq->lock);
 488 }
 489 EXPORT_SYMBOL(devfreq_monitor_resume);
 490
 491 /**
 492  * devfreq_interval_update() - Update device devfreq monitoring interval
 493  * @devfreq:    the devfreq instance.
 494  * @delay:      new polling interval to be set.
 495  *
 496  * Helper function to set new load monitoring polling interval. Function
 497  * to be called from governor in response to DEVFREQ_GOV_INTERVAL event.
 498  */
 499 void devfreq_interval_update(struct devfreq *devfreq, unsigned int *delay)
 500 {
 501         unsigned int cur_delay = devfreq->profile->polling_ms;
 502         unsigned int new_delay = *delay;
 503
 504         mutex_lock(&devfreq->lock);
 505         devfreq->profile->polling_ms = new_delay;
 506
 507         if (devfreq->stop_polling)
 508                 goto out;
 509
 510         /* if new delay is zero, stop polling */
 511         if (!new_delay) {
 512                 mutex_unlock(&devfreq->lock);
 513                 cancel_delayed_work_sync(&devfreq->work);
 514                 return;
 515         }
 516
 517         /* if current delay is zero, start polling with new delay */
 518         if (!cur_delay) {
 519                 queue_delayed_work(devfreq_wq, &devfreq->work,
 520                         msecs_to_jiffies(devfreq->profile->polling_ms));
 521                 goto out;
 522         }
 523
 524         /* if current delay is greater than new delay, restart polling */
 525         if (cur_delay > new_delay) {
 526                 mutex_unlock(&devfreq->lock);
 527                 cancel_delayed_work_sync(&devfreq->work);
 528                 mutex_lock(&devfreq->lock);
 529                 if (!devfreq->stop_polling)
 530                         queue_delayed_work(devfreq_wq, &devfreq->work,
 531                               msecs_to_jiffies(devfreq->profile->polling_ms));
 532         }
 533 out:
 534         mutex_unlock(&devfreq->lock);
 535 }
 536 EXPORT_SYMBOL(devfreq_interval_update);
 537
 538 /**
 539  * devfreq_notifier_call() - Notify that the device frequency requirements
 540  *                         has been changed out of devfreq framework.
 541  * @nb:         the notifier_block (supposed to be devfreq->nb)
 542  * @type:       not used
 543  * @devp:       not used
 544  *
 545  * Called by a notifier that uses devfreq->nb.
 546  */
 547 static int devfreq_notifier_call(struct notifier_block *nb, unsigned long type,
 548                                  void *devp)
 549 {
 550         struct devfreq *devfreq = container_of(nb, struct devfreq, nb);
 551         int ret;
 552
 553         mutex_lock(&devfreq->lock);
 554
 555         devfreq->scaling_min_freq = find_available_min_freq(devfreq);
 556         if (!devfreq->scaling_min_freq) {
 557                 mutex_unlock(&devfreq->lock);
 558                 return -EINVAL;
 559         }
 560
 561         devfreq->scaling_max_freq = find_available_max_freq(devfreq);
 562         if (!devfreq->scaling_max_freq) {
 563                 mutex_unlock(&devfreq->lock);
 564                 return -EINVAL;
 565         }
 566
 567         ret = update_devfreq(devfreq);
 568         mutex_unlock(&devfreq->lock);
 569
 570         return ret;
 571 }
 572
 573 /**
 574  * devfreq_dev_release() - Callback for struct device to release the device.
 575  * @dev:        the devfreq device
 576  *
 577  * Remove devfreq from the list and release its resources.
 578  */
 579 static void devfreq_dev_release(struct device *dev)
 580 {
 581         struct devfreq *devfreq = to_devfreq(dev);
 582
 583         mutex_lock(&devfreq_list_lock);
 584         if (IS_ERR(find_device_devfreq(devfreq->dev.parent))) {
 585                 mutex_unlock(&devfreq_list_lock);
 586                 dev_warn(&devfreq->dev, "releasing devfreq which doesn't exist\n");
 587                 return;
 588         }
 589         list_del(&devfreq->node);
 590         mutex_unlock(&devfreq_list_lock);
 591
 592         if (devfreq->profile->exit)
 593                 devfreq->profile->exit(devfreq->dev.parent);
 594
 595         mutex_destroy(&devfreq->lock);
 596         kfree(devfreq);
 597 }
 598
 599 /**
 600  * devfreq_add_device() - Add devfreq feature to the device
 601  * @dev:        the device to add devfreq feature.
 602  * @profile:    device-specific profile to run devfreq.
 603  * @governor_name:      name of the policy to choose frequency.
 604  * @data:       private data for the governor. The devfreq framework does not
 605  *              touch this value.
 606  */
 607 struct devfreq *devfreq_add_device(struct device *dev,
 608                                    struct devfreq_dev_profile *profile,
 609                                    const char *governor_name,
 610                                    void *data)
 611 {
 612         struct devfreq *devfreq;
 613         struct devfreq_governor *governor;
 614         static atomic_t devfreq_no = ATOMIC_INIT(-1);
 615         int err = 0;
 616
 617         if (!dev || !profile || !governor_name) {
 618                 dev_err(dev, "%s: Invalid parameters.\n", __func__);
 619                 return ERR_PTR(-EINVAL);
 620         }
 621
 622         mutex_lock(&devfreq_list_lock);
 623         devfreq = find_device_devfreq(dev);
 624         mutex_unlock(&devfreq_list_lock);
 625         if (!IS_ERR(devfreq)) {
 626                 dev_err(dev, "%s: Unable to create devfreq for the device.\n",
 627                         __func__);
 628                 err = -EINVAL;
 629                 goto err_out;
 630         }
 631
 632         devfreq = kzalloc(sizeof(struct devfreq), GFP_KERNEL);
 633         if (!devfreq) {
 634                 err = -ENOMEM;
 635                 goto err_out;
 636         }
 637
 638         mutex_init(&devfreq->lock);
 639         mutex_lock(&devfreq->lock);
 640         devfreq->dev.parent = dev;
 641         devfreq->dev.class = devfreq_class;
 642         devfreq->dev.release = devfreq_dev_release;
 643         devfreq->profile = profile;
 644         strncpy(devfreq->governor_name, governor_name, DEVFREQ_NAME_LEN);
 645         devfreq->previous_freq = profile->initial_freq;
 646         devfreq->last_status.current_frequency = profile->initial_freq;
 647         devfreq->data = data;
 648         devfreq->nb.notifier_call = devfreq_notifier_call;
 649
 650         if (!devfreq->profile->max_state && !devfreq->profile->freq_table) {
 651                 mutex_unlock(&devfreq->lock);
 652                 err = set_freq_table(devfreq);
 653                 if (err < 0)
 654                         goto err_out;
 655                 mutex_lock(&devfreq->lock);
 656         }
 657
 658         devfreq->scaling_min_freq = find_available_min_freq(devfreq);
 659         if (!devfreq->scaling_min_freq) {
 660                 mutex_unlock(&devfreq->lock);
 661                 err = -EINVAL;
 662                 goto err_dev;
 663         }
 664         devfreq->min_freq = devfreq->scaling_min_freq;
 665
 666         devfreq->scaling_max_freq = find_available_max_freq(devfreq);
 667         if (!devfreq->scaling_max_freq) {
 668                 mutex_unlock(&devfreq->lock);
 669                 err = -EINVAL;
 670                 goto err_dev;
 671         }
 672         devfreq->max_freq = devfreq->scaling_max_freq;
 673
 674         devfreq->suspend_freq = dev_pm_opp_get_suspend_opp_freq(dev);
 675         atomic_set(&devfreq->suspend_count, 0);
 676
 677         dev_set_name(&devfreq->dev, "devfreq%d",
 678                                 atomic_inc_return(&devfreq_no));
 679         err = device_register(&devfreq->dev);
 680         if (err) {
 681                 mutex_unlock(&devfreq->lock);
 682                 put_device(&devfreq->dev);
 683                 goto err_out;
 684         }
 685
 686         devfreq->trans_table =
 687                 devm_kzalloc(&devfreq->dev,
 688                              array3_size(sizeof(unsigned int),
 689                                          devfreq->profile->max_state,
 690                                          devfreq->profile->max_state),
 691                              GFP_KERNEL);
 692         devfreq->time_in_state = devm_kcalloc(&devfreq->dev,
 693                                                 devfreq->profile->max_state,
 694                                                 sizeof(unsigned long),
 695                                                 GFP_KERNEL);
 696         devfreq->last_stat_updated = jiffies;
 697
 698         srcu_init_notifier_head(&devfreq->transition_notifier_list);
 699
 700         mutex_unlock(&devfreq->lock);
 701
 702         mutex_lock(&devfreq_list_lock);
 703
 704         governor = try_then_request_governor(devfreq->governor_name);
 705         if (IS_ERR(governor)) {
 706                 dev_err(dev, "%s: Unable to find governor for the device\n",
 707                         __func__);
 708                 err = PTR_ERR(governor);
 709                 goto err_init;
 710         }
 711
 712         devfreq->governor = governor;
 713         err = devfreq->governor->event_handler(devfreq, DEVFREQ_GOV_START,
 714                                                 NULL);
 715         if (err) {
 716                 dev_err(dev, "%s: Unable to start governor for the device\n",
 717                         __func__);
 718                 goto err_init;
 719         }
 720
 721         list_add(&devfreq->node, &devfreq_list);
 722
 723         mutex_unlock(&devfreq_list_lock);
 724
 725         return devfreq;
 726
 727 err_init:
 728         mutex_unlock(&devfreq_list_lock);
 729
 730         devfreq_remove_device(devfreq);
 731         devfreq = NULL;
 732 err_dev:
 733         kfree(devfreq);
 734 err_out:
 735         return ERR_PTR(err);
 736 }
 737 EXPORT_SYMBOL(devfreq_add_device);
 738
 739 /**
 740  * devfreq_remove_device() - Remove devfreq feature from a device.
 741  * @devfreq:    the devfreq instance to be removed
 742  *
 743  * The opposite of devfreq_add_device().
 744  */
 745 int devfreq_remove_device(struct devfreq *devfreq)
 746 {
 747         if (!devfreq)
 748                 return -EINVAL;
 749
 750         if (devfreq->governor)
 751                 devfreq->governor->event_handler(devfreq,
 752                                                  DEVFREQ_GOV_STOP, NULL);
 753         device_unregister(&devfreq->dev);
 754
 755         return 0;
 756 }
 757 EXPORT_SYMBOL(devfreq_remove_device);
 758
 759 static int devm_devfreq_dev_match(struct device *dev, void *res, void *data)
 760 {
 761         struct devfreq **r = res;
 762
 763         if (WARN_ON(!r || !*r))
 764                 return 0;
 765
 766         return *r == data;
 767 }
 768
 769 static void devm_devfreq_dev_release(struct device *dev, void *res)
 770 {
 771         devfreq_remove_device(*(struct devfreq **)res);
 772 }
 773
 774 /**
 775  * devm_devfreq_add_device() - Resource-managed devfreq_add_device()
 776  * @dev:        the device to add devfreq feature.
 777  * @profile:    device-specific profile to run devfreq.
 778  * @governor_name:      name of the policy to choose frequency.
 779  * @data:       private data for the governor. The devfreq framework does not
 780  *              touch this value.
 781  *
 782  * This function manages automatically the memory of devfreq device using device
 783  * resource management and simplify the free operation for memory of devfreq
 784  * device.
 785  */
 786 struct devfreq *devm_devfreq_add_device(struct device *dev,
 787                                         struct devfreq_dev_profile *profile,
 788                                         const char *governor_name,
 789                                         void *data)
 790 {
 791         struct devfreq **ptr, *devfreq;
 792
 793         ptr = devres_alloc(devm_devfreq_dev_release, sizeof(*ptr), GFP_KERNEL);
 794         if (!ptr)
 795                 return ERR_PTR(-ENOMEM);
 796
 797         devfreq = devfreq_add_device(dev, profile, governor_name, data);
 798         if (IS_ERR(devfreq)) {
 799                 devres_free(ptr);
 800                 return devfreq;
 801         }
 802
 803         *ptr = devfreq;
 804         devres_add(dev, ptr);
 805
 806         return devfreq;
 807 }
 808 EXPORT_SYMBOL(devm_devfreq_add_device);
 809
 810 #ifdef CONFIG_OF
 811 /*
 812  * devfreq_get_devfreq_by_phandle - Get the devfreq device from devicetree
 813  * @dev - instance to the given device
 814  * @index - index into list of devfreq
 815  *
 816  * return the instance of devfreq device
 817  */
 818 struct devfreq *devfreq_get_devfreq_by_phandle(struct device *dev, int index)
 819 {
 820         struct device_node *node;
 821         struct devfreq *devfreq;
 822
 823         if (!dev)
 824                 return ERR_PTR(-EINVAL);
 825
 826         if (!dev->of_node)
 827                 return ERR_PTR(-EINVAL);
 828
 829         node = of_parse_phandle(dev->of_node, "devfreq", index);
 830         if (!node)
 831                 return ERR_PTR(-ENODEV);
 832
 833         mutex_lock(&devfreq_list_lock);
 834         list_for_each_entry(devfreq, &devfreq_list, node) {
 835                 if (devfreq->dev.parent
 836                         && devfreq->dev.parent->of_node == node) {
 837                         mutex_unlock(&devfreq_list_lock);
 838                         of_node_put(node);
 839                         return devfreq;
 840                 }
 841         }
 842         mutex_unlock(&devfreq_list_lock);
 843         of_node_put(node);
 844
 845         return ERR_PTR(-EPROBE_DEFER);
 846 }
 847 #else
 848 struct devfreq *devfreq_get_devfreq_by_phandle(struct device *dev, int index)
 849 {
 850         return ERR_PTR(-ENODEV);
 851 }
 852 #endif /* CONFIG_OF */
 853 EXPORT_SYMBOL_GPL(devfreq_get_devfreq_by_phandle);
 854
 855 /**
 856  * devm_devfreq_remove_device() - Resource-managed devfreq_remove_device()
 857  * @dev:        the device to add devfreq feature.
 858  * @devfreq:    the devfreq instance to be removed
 859  */
 860 void devm_devfreq_remove_device(struct device *dev, struct devfreq *devfreq)
 861 {
 862         WARN_ON(devres_release(dev, devm_devfreq_dev_release,
 863                                devm_devfreq_dev_match, devfreq));
 864 }
 865 EXPORT_SYMBOL(devm_devfreq_remove_device);
 866
 867 /**
 868  * devfreq_suspend_device() - Suspend devfreq of a device.
 869  * @devfreq: the devfreq instance to be suspended
 870  *
 871  * This function is intended to be called by the pm callbacks
 872  * (e.g., runtime_suspend, suspend) of the device driver that
 873  * holds the devfreq.
 874  */
 875 int devfreq_suspend_device(struct devfreq *devfreq)
 876 {
 877         int ret;
 878
 879         if (!devfreq)
 880                 return -EINVAL;
 881
 882         if (atomic_inc_return(&devfreq->suspend_count) > 1)
 883                 return 0;
 884
 885         if (devfreq->governor) {
 886                 ret = devfreq->governor->event_handler(devfreq,
 887                                         DEVFREQ_GOV_SUSPEND, NULL);
 888                 if (ret)
 889                         return ret;
 890         }
 891
 892         if (devfreq->suspend_freq) {
 893                 ret = devfreq_set_target(devfreq, devfreq->suspend_freq, 0);
 894                 if (ret)
 895                         return ret;
 896         }
 897
 898         return 0;
 899 }
 900 EXPORT_SYMBOL(devfreq_suspend_device);
 901
 902 /**
 903  * devfreq_resume_device() - Resume devfreq of a device.
 904  * @devfreq: the devfreq instance to be resumed
 905  *
 906  * This function is intended to be called by the pm callbacks
 907  * (e.g., runtime_resume, resume) of the device driver that
 908  * holds the devfreq.
 909  */
 910 int devfreq_resume_device(struct devfreq *devfreq)
 911 {
 912         int ret;
 913
 914         if (!devfreq)
 915                 return -EINVAL;
 916
 917         if (atomic_dec_return(&devfreq->suspend_count) >= 1)
 918                 return 0;
 919
 920         if (devfreq->resume_freq) {
 921                 ret = devfreq_set_target(devfreq, devfreq->resume_freq, 0);
 922                 if (ret)
 923                         return ret;
 924         }
 925
 926         if (devfreq->governor) {
 927                 ret = devfreq->governor->event_handler(devfreq,
 928                                         DEVFREQ_GOV_RESUME, NULL);
 929                 if (ret)
 930                         return ret;
 931         }
 932
 933         return 0;
 934 }
 935 EXPORT_SYMBOL(devfreq_resume_device);
 936
 937 /**
 938  * devfreq_suspend() - Suspend devfreq governors and devices
 939  *
 940  * Called during system wide Suspend/Hibernate cycles for suspending governors
 941  * and devices preserving the state for resume. On some platforms the devfreq
 942  * device must have precise state (frequency) after resume in order to provide
 943  * fully operating setup.
 944  */
 945 void devfreq_suspend(void)
 946 {
 947         struct devfreq *devfreq;
 948         int ret;
 949
 950         mutex_lock(&devfreq_list_lock);
 951         list_for_each_entry(devfreq, &devfreq_list, node) {
 952                 ret = devfreq_suspend_device(devfreq);
 953                 if (ret)
 954                         dev_err(&devfreq->dev,
 955                                 "failed to suspend devfreq device\n");
 956         }
 957         mutex_unlock(&devfreq_list_lock);
 958 }
 959
 960 /**
 961  * devfreq_resume() - Resume devfreq governors and devices
 962  *
 963  * Called during system wide Suspend/Hibernate cycle for resuming governors and
 964  * devices that are suspended with devfreq_suspend().
 965  */
 966 void devfreq_resume(void)
 967 {
 968         struct devfreq *devfreq;
 969         int ret;
 970
 971         mutex_lock(&devfreq_list_lock);
 972         list_for_each_entry(devfreq, &devfreq_list, node) {
 973                 ret = devfreq_resume_device(devfreq);
 974                 if (ret)
 975                         dev_warn(&devfreq->dev,
 976                                  "failed to resume devfreq device\n");
 977         }
 978         mutex_unlock(&devfreq_list_lock);
 979 }
 980
 981 /**
 982  * devfreq_add_governor() - Add devfreq governor
 983  * @governor:   the devfreq governor to be added
 984  */
 985 int devfreq_add_governor(struct devfreq_governor *governor)
 986 {
 987         struct devfreq_governor *g;
 988         struct devfreq *devfreq;
 989         int err = 0;
 990
 991         if (!governor) {
 992                 pr_err("%s: Invalid parameters.\n", __func__);
 993                 return -EINVAL;
 994         }
 995
 996         mutex_lock(&devfreq_list_lock);
 997         g = find_devfreq_governor(governor->name);
 998         if (!IS_ERR(g)) {
 999                 pr_err("%s: governor %s already registered\n", __func__,
1000                        g->name);
1001                 err = -EINVAL;
1002                 goto err_out;
1003         }
1004
1005         list_add(&governor->node, &devfreq_governor_list);
1006
1007         list_for_each_entry(devfreq, &devfreq_list, node) {
1008                 int ret = 0;
1009                 struct device *dev = devfreq->dev.parent;
1010
1011                 if (!strncmp(devfreq->governor_name, governor->name,
1012                              DEVFREQ_NAME_LEN)) {
1013                         /* The following should never occur */
1014                         if (devfreq->governor) {
1015                                 dev_warn(dev,
1016                                          "%s: Governor %s already present\n",
1017                                          __func__, devfreq->governor->name);
1018                                 ret = devfreq->governor->event_handler(devfreq,
1019                                                         DEVFREQ_GOV_STOP, NULL);
1020                                 if (ret) {
1021                                         dev_warn(dev,
1022                                                  "%s: Governor %s stop = %d\n",
1023                                                  __func__,
1024                                                  devfreq->governor->name, ret);
1025                                 }
1026                                 /* Fall through */
1027                         }
1028                         devfreq->governor = governor;
1029                         ret = devfreq->governor->event_handler(devfreq,
1030                                                 DEVFREQ_GOV_START, NULL);
1031                         if (ret) {
1032                                 dev_warn(dev, "%s: Governor %s start=%d\n",
1033                                          __func__, devfreq->governor->name,
1034                                          ret);
1035                         }
1036                 }
1037         }
1038
1039 err_out:
1040         mutex_unlock(&devfreq_list_lock);
1041
1042         return err;
1043 }
1044 EXPORT_SYMBOL(devfreq_add_governor);
1045
1046 /**
1047  * devfreq_remove_governor() - Remove devfreq feature from a device.
1048  * @governor:   the devfreq governor to be removed
1049  */
1050 int devfreq_remove_governor(struct devfreq_governor *governor)
1051 {
1052         struct devfreq_governor *g;
1053         struct devfreq *devfreq;
1054         int err = 0;
1055
1056         if (!governor) {
1057                 pr_err("%s: Invalid parameters.\n", __func__);
1058                 return -EINVAL;
1059         }
1060
1061         mutex_lock(&devfreq_list_lock);
1062         g = find_devfreq_governor(governor->name);
1063         if (IS_ERR(g)) {
1064                 pr_err("%s: governor %s not registered\n", __func__,
1065                        governor->name);
1066                 err = PTR_ERR(g);
1067                 goto err_out;
1068         }
1069         list_for_each_entry(devfreq, &devfreq_list, node) {
1070                 int ret;
1071                 struct device *dev = devfreq->dev.parent;
1072
1073                 if (!strncmp(devfreq->governor_name, governor->name,
1074                              DEVFREQ_NAME_LEN)) {
1075                         /* we should have a devfreq governor! */
1076                         if (!devfreq->governor) {
1077                                 dev_warn(dev, "%s: Governor %s NOT present\n",
1078                                          __func__, governor->name);
1079                                 continue;
1080                                 /* Fall through */
1081                         }
1082                         ret = devfreq->governor->event_handler(devfreq,
1083                                                 DEVFREQ_GOV_STOP, NULL);
1084                         if (ret) {
1085                                 dev_warn(dev, "%s: Governor %s stop=%d\n",
1086                                          __func__, devfreq->governor->name,
1087                                          ret);
1088                         }
1089                         devfreq->governor = NULL;
1090                 }
1091         }
1092
1093         list_del(&governor->node);
1094 err_out:
1095         mutex_unlock(&devfreq_list_lock);
1096
1097         return err;
1098 }
1099 EXPORT_SYMBOL(devfreq_remove_governor);
1100
1101 static ssize_t governor_show(struct device *dev,
1102                              struct device_attribute *attr, char *buf)
1103 {
1104         if (!to_devfreq(dev)->governor)
1105                 return -EINVAL;
1106
1107         return sprintf(buf, "%s\n", to_devfreq(dev)->governor->name);
1108 }
1109
1110 static ssize_t governor_store(struct device *dev, struct device_attribute *attr,
1111                               const char *buf, size_t count)
1112 {
1113         struct devfreq *df = to_devfreq(dev);
1114         int ret;
1115         char str_governor[DEVFREQ_NAME_LEN + 1];
1116         struct devfreq_governor *governor;
1117
1118         ret = sscanf(buf, "%" __stringify(DEVFREQ_NAME_LEN) "s", str_governor);
1119         if (ret != 1)
1120                 return -EINVAL;
1121
1122         mutex_lock(&devfreq_list_lock);
1123         governor = try_then_request_governor(str_governor);
1124         if (IS_ERR(governor)) {
1125                 ret = PTR_ERR(governor);
1126                 goto out;
1127         }
1128         if (df->governor == governor) {
1129                 ret = 0;
1130                 goto out;
1131         } else if ((df->governor && df->governor->immutable) ||
1132                                         governor->immutable) {
1133                 ret = -EINVAL;
1134                 goto out;
1135         }
1136
1137         if (df->governor) {
1138                 ret = df->governor->event_handler(df, DEVFREQ_GOV_STOP, NULL);
1139                 if (ret) {
1140                         dev_warn(dev, "%s: Governor %s not stopped(%d)\n",
1141                                  __func__, df->governor->name, ret);
1142                         goto out;
1143                 }
1144         }
1145         df->governor = governor;
1146         strncpy(df->governor_name, governor->name, DEVFREQ_NAME_LEN);
1147         ret = df->governor->event_handler(df, DEVFREQ_GOV_START, NULL);
1148         if (ret)
1149                 dev_warn(dev, "%s: Governor %s not started(%d)\n",
1150                          __func__, df->governor->name, ret);
1151 out:
1152         mutex_unlock(&devfreq_list_lock);
1153
1154         if (!ret)
1155                 ret = count;
1156         return ret;
1157 }
1158 static DEVICE_ATTR_RW(governor);
1159
1160 static ssize_t available_governors_show(struct device *d,
1161                                         struct device_attribute *attr,
1162                                         char *buf)
1163 {
1164         struct devfreq *df = to_devfreq(d);
1165         ssize_t count = 0;
1166
1167         mutex_lock(&devfreq_list_lock);
1168
1169         /*
1170          * The devfreq with immutable governor (e.g., passive) shows
1171          * only own governor.
1172          */
1173         if (df->governor->immutable) {
1174                 count = scnprintf(&buf[count], DEVFREQ_NAME_LEN,
1175                                    "%s ", df->governor_name);
1176         /*
1177          * The devfreq device shows the registered governor except for
1178          * immutable governors such as passive governor .
1179          */
1180         } else {
1181                 struct devfreq_governor *governor;
1182
1183                 list_for_each_entry(governor, &devfreq_governor_list, node) {
1184                         if (governor->immutable)
1185                                 continue;
1186                         count += scnprintf(&buf[count], (PAGE_SIZE - count - 2),
1187                                            "%s ", governor->name);
1188                 }
1189         }
1190
1191         mutex_unlock(&devfreq_list_lock);
1192
1193         /* Truncate the trailing space */
1194         if (count)
1195                 count--;
1196
1197         count += sprintf(&buf[count], "\n");
1198
1199         return count;
1200 }
1201 static DEVICE_ATTR_RO(available_governors);
1202
1203 static ssize_t cur_freq_show(struct device *dev, struct device_attribute *attr,
1204                              char *buf)
1205 {
1206         unsigned long freq;
1207         struct devfreq *devfreq = to_devfreq(dev);
1208
1209         if (devfreq->profile->get_cur_freq &&
1210                 !devfreq->profile->get_cur_freq(devfreq->dev.parent, &freq))
1211                 return sprintf(buf, "%lu\n", freq);
1212
1213         return sprintf(buf, "%lu\n", devfreq->previous_freq);
1214 }
1215 static DEVICE_ATTR_RO(cur_freq);
1216
1217 static ssize_t target_freq_show(struct device *dev,
1218                                 struct device_attribute *attr, char *buf)
1219 {
1220         return sprintf(buf, "%lu\n", to_devfreq(dev)->previous_freq);
1221 }
1222 static DEVICE_ATTR_RO(target_freq);
1223
1224 static ssize_t polling_interval_show(struct device *dev,
1225                                      struct device_attribute *attr, char *buf)
1226 {
1227         return sprintf(buf, "%d\n", to_devfreq(dev)->profile->polling_ms);
1228 }
1229
1230 static ssize_t polling_interval_store(struct device *dev,
1231                                       struct device_attribute *attr,
1232                                       const char *buf, size_t count)
1233 {
1234         struct devfreq *df = to_devfreq(dev);
1235         unsigned int value;
1236         int ret;
1237
1238         if (!df->governor)
1239                 return -EINVAL;
1240
1241         ret = sscanf(buf, "%u", &value);
1242         if (ret != 1)
1243                 return -EINVAL;
1244
1245         df->governor->event_handler(df, DEVFREQ_GOV_INTERVAL, &value);
1246         ret = count;
1247
1248         return ret;
1249 }
1250 static DEVICE_ATTR_RW(polling_interval);
1251
1252 static ssize_t min_freq_store(struct device *dev, struct device_attribute *attr,
1253                               const char *buf, size_t count)
1254 {
1255         struct devfreq *df = to_devfreq(dev);
1256         unsigned long value;
1257         int ret;
1258
1259         ret = sscanf(buf, "%lu", &value);
1260         if (ret != 1)
1261                 return -EINVAL;
1262
1263         mutex_lock(&df->lock);
1264
1265         if (value) {
1266                 if (value > df->max_freq) {
1267                         ret = -EINVAL;
1268                         goto unlock;
1269                 }
1270         } else {
1271                 unsigned long *freq_table = df->profile->freq_table;
1272
1273                 /* Get minimum frequency according to sorting order */
1274                 if (freq_table[0] < freq_table[df->profile->max_state - 1])
1275                         value = freq_table[0];
1276                 else
1277                         value = freq_table[df->profile->max_state - 1];
1278         }
1279
1280         df->min_freq = value;
1281         update_devfreq(df);
1282         ret = count;
1283 unlock:
1284         mutex_unlock(&df->lock);
1285         return ret;
1286 }
1287
1288 static ssize_t min_freq_show(struct device *dev, struct device_attribute *attr,
1289                              char *buf)
1290 {
1291         struct devfreq *df = to_devfreq(dev);
1292
1293         return sprintf(buf, "%lu\n", max(df->scaling_min_freq, df->min_freq));
1294 }
1295
1296 static ssize_t max_freq_store(struct device *dev, struct device_attribute *attr,
1297                               const char *buf, size_t count)
1298 {
1299         struct devfreq *df = to_devfreq(dev);
1300         unsigned long value;
1301         int ret;
1302
1303         ret = sscanf(buf, "%lu", &value);
1304         if (ret != 1)
1305                 return -EINVAL;
1306
1307         mutex_lock(&df->lock);
1308
1309         if (value) {
1310                 if (value < df->min_freq) {
1311                         ret = -EINVAL;
1312                         goto unlock;
1313                 }
1314         } else {
1315                 unsigned long *freq_table = df->profile->freq_table;
1316
1317                 /* Get maximum frequency according to sorting order */
1318                 if (freq_table[0] < freq_table[df->profile->max_state - 1])
1319                         value = freq_table[df->profile->max_state - 1];
1320                 else
1321                         value = freq_table[0];
1322         }
1323
1324         df->max_freq = value;
1325         update_devfreq(df);
1326         ret = count;
1327 unlock:
1328         mutex_unlock(&df->lock);
1329         return ret;
1330 }
1331 static DEVICE_ATTR_RW(min_freq);
1332
1333 static ssize_t max_freq_show(struct device *dev, struct device_attribute *attr,
1334                              char *buf)
1335 {
1336         struct devfreq *df = to_devfreq(dev);
1337
1338         return sprintf(buf, "%lu\n", min(df->scaling_max_freq, df->max_freq));
1339 }
1340 static DEVICE_ATTR_RW(max_freq);
1341
1342 static ssize_t available_frequencies_show(struct device *d,
1343                                           struct device_attribute *attr,
1344                                           char *buf)
1345 {
1346         struct devfreq *df = to_devfreq(d);
1347         ssize_t count = 0;
1348         int i;
1349
1350         mutex_lock(&df->lock);
1351
1352         for (i = 0; i < df->profile->max_state; i++)
1353                 count += scnprintf(&buf[count], (PAGE_SIZE - count - 2),
1354                                 "%lu ", df->profile->freq_table[i]);
1355
1356         mutex_unlock(&df->lock);
1357         /* Truncate the trailing space */
1358         if (count)
1359                 count--;
1360
1361         count += sprintf(&buf[count], "\n");
1362
1363         return count;
1364 }
1365 static DEVICE_ATTR_RO(available_frequencies);
1366
1367 static ssize_t trans_stat_show(struct device *dev,
1368                                struct device_attribute *attr, char *buf)
1369 {
1370         struct devfreq *devfreq = to_devfreq(dev);
1371         ssize_t len;
1372         int i, j;
1373         unsigned int max_state = devfreq->profile->max_state;
1374
1375         if (!devfreq->stop_polling &&
1376                         devfreq_update_status(devfreq, devfreq->previous_freq))
1377                 return 0;
1378         if (max_state == 0)
1379                 return sprintf(buf, "Not Supported.\n");
1380
1381         len = sprintf(buf, "     From  :   To\n");
1382         len += sprintf(buf + len, "           :");
1383         for (i = 0; i < max_state; i++)
1384                 len += sprintf(buf + len, "%10lu",
1385                                 devfreq->profile->freq_table[i]);
1386
1387         len += sprintf(buf + len, "   time(ms)\n");
1388
1389         for (i = 0; i < max_state; i++) {
1390                 if (devfreq->profile->freq_table[i]
1391                                         == devfreq->previous_freq) {
1392                         len += sprintf(buf + len, "*");
1393                 } else {
1394                         len += sprintf(buf + len, " ");
1395                 }
1396                 len += sprintf(buf + len, "%10lu:",
1397                                 devfreq->profile->freq_table[i]);
1398                 for (j = 0; j < max_state; j++)
1399                         len += sprintf(buf + len, "%10u",
1400                                 devfreq->trans_table[(i * max_state) + j]);
1401                 len += sprintf(buf + len, "%10u\n",
1402                         jiffies_to_msecs(devfreq->time_in_state[i]));
1403         }
1404
1405         len += sprintf(buf + len, "Total transition : %u\n",
1406                                         devfreq->total_trans);
1407         return len;
1408 }
1409 static DEVICE_ATTR_RO(trans_stat);
1410
1411 static struct attribute *devfreq_attrs[] = {
1412         &dev_attr_governor.attr,
1413         &dev_attr_available_governors.attr,
1414         &dev_attr_cur_freq.attr,
1415         &dev_attr_available_frequencies.attr,
1416         &dev_attr_target_freq.attr,
1417         &dev_attr_polling_interval.attr,
1418         &dev_attr_min_freq.attr,
1419         &dev_attr_max_freq.attr,
1420         &dev_attr_trans_stat.attr,
1421         NULL,
1422 };
1423 ATTRIBUTE_GROUPS(devfreq);
1424
1425 static int __init devfreq_init(void)
1426 {
1427         devfreq_class = class_create(THIS_MODULE, "devfreq");
1428         if (IS_ERR(devfreq_class)) {
1429                 pr_err("%s: couldn't create class\n", __FILE__);
1430                 return PTR_ERR(devfreq_class);
1431         }
1432
1433         devfreq_wq = create_freezable_workqueue("devfreq_wq");
1434         if (!devfreq_wq) {
1435                 class_destroy(devfreq_class);
1436                 pr_err("%s: couldn't create workqueue\n", __FILE__);
1437                 return -ENOMEM;
1438         }
1439         devfreq_class->dev_groups = devfreq_groups;
1440
1441         return 0;
1442 }
1443 subsys_initcall(devfreq_init);
1444
1445 /*
1446  * The following are helper functions for devfreq user device drivers with
1447  * OPP framework.
1448  */
1449
1450 /**
1451  * devfreq_recommended_opp() - Helper function to get proper OPP for the
1452  *                           freq value given to target callback.
1453  * @dev:        The devfreq user device. (parent of devfreq)
1454  * @freq:       The frequency given to target function
1455  * @flags:      Flags handed from devfreq framework.
1456  *
1457  * The callers are required to call dev_pm_opp_put() for the returned OPP after
1458  * use.
1459  */
1460 struct dev_pm_opp *devfreq_recommended_opp(struct device *dev,
1461                                            unsigned long *freq,
1462                                            u32 flags)
1463 {
1464         struct dev_pm_opp *opp;
1465
1466         if (flags & DEVFREQ_FLAG_LEAST_UPPER_BOUND) {
1467                 /* The freq is an upper bound. opp should be lower */
1468                 opp = dev_pm_opp_find_freq_floor(dev, freq);
1469
1470                 /* If not available, use the closest opp */
1471                 if (opp == ERR_PTR(-ERANGE))
1472                         opp = dev_pm_opp_find_freq_ceil(dev, freq);
1473         } else {
1474                 /* The freq is an lower bound. opp should be higher */
1475                 opp = dev_pm_opp_find_freq_ceil(dev, freq);
1476
1477                 /* If not available, use the closest opp */
1478                 if (opp == ERR_PTR(-ERANGE))
1479                         opp = dev_pm_opp_find_freq_floor(dev, freq);
1480         }
1481
1482         return opp;
1483 }
1484 EXPORT_SYMBOL(devfreq_recommended_opp);
1485
1486 /**
1487  * devfreq_register_opp_notifier() - Helper function to get devfreq notified
1488  *                                 for any changes in the OPP availability
1489  *                                 changes
1490  * @dev:        The devfreq user device. (parent of devfreq)
1491  * @devfreq:    The devfreq object.
1492  */
1493 int devfreq_register_opp_notifier(struct device *dev, struct devfreq *devfreq)
1494 {
1495         return dev_pm_opp_register_notifier(dev, &devfreq->nb);
1496 }
1497 EXPORT_SYMBOL(devfreq_register_opp_notifier);
1498
1499 /**
1500  * devfreq_unregister_opp_notifier() - Helper function to stop getting devfreq
1501  *                                   notified for any changes in the OPP
1502  *                                   availability changes anymore.
1503  * @dev:        The devfreq user device. (parent of devfreq)
1504  * @devfreq:    The devfreq object.
1505  *
1506  * At exit() callback of devfreq_dev_profile, this must be included if
1507  * devfreq_recommended_opp is used.
1508  */
1509 int devfreq_unregister_opp_notifier(struct device *dev, struct devfreq *devfreq)
1510 {
1511         return dev_pm_opp_unregister_notifier(dev, &devfreq->nb);
1512 }
1513 EXPORT_SYMBOL(devfreq_unregister_opp_notifier);
1514
1515 static void devm_devfreq_opp_release(struct device *dev, void *res)
1516 {
1517         devfreq_unregister_opp_notifier(dev, *(struct devfreq **)res);
1518 }
1519
1520 /**
1521  * devm_ devfreq_register_opp_notifier()
1522  *              - Resource-managed devfreq_register_opp_notifier()
1523  * @dev:        The devfreq user device. (parent of devfreq)
1524  * @devfreq:    The devfreq object.
1525  */
1526 int devm_devfreq_register_opp_notifier(struct device *dev,
1527                                        struct devfreq *devfreq)
1528 {
1529         struct devfreq **ptr;
1530         int ret;
1531
1532         ptr = devres_alloc(devm_devfreq_opp_release, sizeof(*ptr), GFP_KERNEL);
1533         if (!ptr)
1534                 return -ENOMEM;
1535
1536         ret = devfreq_register_opp_notifier(dev, devfreq);
1537         if (ret) {
1538                 devres_free(ptr);
1539                 return ret;
1540         }
1541
1542         *ptr = devfreq;
1543         devres_add(dev, ptr);
1544
1545         return 0;
1546 }
1547 EXPORT_SYMBOL(devm_devfreq_register_opp_notifier);
1548
1549 /**
1550  * devm_devfreq_unregister_opp_notifier()
1551  *              - Resource-managed devfreq_unregister_opp_notifier()
1552  * @dev:        The devfreq user device. (parent of devfreq)
1553  * @devfreq:    The devfreq object.
1554  */
1555 void devm_devfreq_unregister_opp_notifier(struct device *dev,
1556                                          struct devfreq *devfreq)
1557 {
1558         WARN_ON(devres_release(dev, devm_devfreq_opp_release,
1559                                devm_devfreq_dev_match, devfreq));
1560 }
1561 EXPORT_SYMBOL(devm_devfreq_unregister_opp_notifier);
1562
1563 /**
1564  * devfreq_register_notifier() - Register a driver with devfreq
1565  * @devfreq:    The devfreq object.
1566  * @nb:         The notifier block to register.
1567  * @list:       DEVFREQ_TRANSITION_NOTIFIER.
1568  */
1569 int devfreq_register_notifier(struct devfreq *devfreq,
1570                                 struct notifier_block *nb,
1571                                 unsigned int list)
1572 {
1573         int ret = 0;
1574
1575         if (!devfreq)
1576                 return -EINVAL;
1577
1578         switch (list) {
1579         case DEVFREQ_TRANSITION_NOTIFIER:
1580                 ret = srcu_notifier_chain_register(
1581                                 &devfreq->transition_notifier_list, nb);
1582                 break;
1583         default:
1584                 ret = -EINVAL;
1585         }
1586
1587         return ret;
1588 }
1589 EXPORT_SYMBOL(devfreq_register_notifier);
1590
1591 /*
1592  * devfreq_unregister_notifier() - Unregister a driver with devfreq
1593  * @devfreq:    The devfreq object.
1594  * @nb:         The notifier block to be unregistered.
1595  * @list:       DEVFREQ_TRANSITION_NOTIFIER.
1596  */
1597 int devfreq_unregister_notifier(struct devfreq *devfreq,
1598                                 struct notifier_block *nb,
1599                                 unsigned int list)
1600 {
1601         int ret = 0;
1602
1603         if (!devfreq)
1604                 return -EINVAL;
1605
1606         switch (list) {
1607         case DEVFREQ_TRANSITION_NOTIFIER:
1608                 ret = srcu_notifier_chain_unregister(
1609                                 &devfreq->transition_notifier_list, nb);
1610                 break;
1611         default:
1612                 ret = -EINVAL;
1613         }
1614
1615         return ret;
1616 }
1617 EXPORT_SYMBOL(devfreq_unregister_notifier);
1618
1619 struct devfreq_notifier_devres {
1620         struct devfreq *devfreq;
1621         struct notifier_block *nb;
1622         unsigned int list;
1623 };
1624
1625 static void devm_devfreq_notifier_release(struct device *dev, void *res)
1626 {
1627         struct devfreq_notifier_devres *this = res;
1628
1629         devfreq_unregister_notifier(this->devfreq, this->nb, this->list);
1630 }
1631
1632 /**
1633  * devm_devfreq_register_notifier()
1634         - Resource-managed devfreq_register_notifier()
1635  * @dev:        The devfreq user device. (parent of devfreq)
1636  * @devfreq:    The devfreq object.
1637  * @nb:         The notifier block to be unregistered.
1638  * @list:       DEVFREQ_TRANSITION_NOTIFIER.
1639  */
1640 int devm_devfreq_register_notifier(struct device *dev,
1641                                 struct devfreq *devfreq,
1642                                 struct notifier_block *nb,
1643                                 unsigned int list)
1644 {
1645         struct devfreq_notifier_devres *ptr;
1646         int ret;
1647
1648         ptr = devres_alloc(devm_devfreq_notifier_release, sizeof(*ptr),
1649                                 GFP_KERNEL);
1650         if (!ptr)
1651                 return -ENOMEM;
1652
1653         ret = devfreq_register_notifier(devfreq, nb, list);
1654         if (ret) {
1655                 devres_free(ptr);
1656                 return ret;
1657         }
1658
1659         ptr->devfreq = devfreq;
1660         ptr->nb = nb;
1661         ptr->list = list;
1662         devres_add(dev, ptr);
1663
1664         return 0;
1665 }
1666 EXPORT_SYMBOL(devm_devfreq_register_notifier);
1667
1668 /**
1669  * devm_devfreq_unregister_notifier()
1670         - Resource-managed devfreq_unregister_notifier()
1671  * @dev:        The devfreq user device. (parent of devfreq)
1672  * @devfreq:    The devfreq object.
1673  * @nb:         The notifier block to be unregistered.
1674  * @list:       DEVFREQ_TRANSITION_NOTIFIER.
1675  */
1676 void devm_devfreq_unregister_notifier(struct device *dev,
1677                                 struct devfreq *devfreq,
1678                                 struct notifier_block *nb,
1679                                 unsigned int list)
1680 {
1681         WARN_ON(devres_release(dev, devm_devfreq_notifier_release,
1682                                devm_devfreq_dev_match, devfreq));
1683 }
1684 EXPORT_SYMBOL(devm_devfreq_unregister_notifier);