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/module.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 "governor.h"
  29
  30 static struct class *devfreq_class;
  31
  32 /*
  33  * devfreq core provides delayed work based load monitoring helper
  34  * functions. Governors can use these or can implement their own
  35  * monitoring mechanism.
  36  */
  37 static struct workqueue_struct *devfreq_wq;
  38
  39 /* The list of all device-devfreq governors */
  40 static LIST_HEAD(devfreq_governor_list);
  41 /* The list of all device-devfreq */
  42 static LIST_HEAD(devfreq_list);
  43 static DEFINE_MUTEX(devfreq_list_lock);
  44
  45 /**
  46  * find_device_devfreq() - find devfreq struct using device pointer
  47  * @dev:        device pointer used to lookup device devfreq.
  48  *
  49  * Search the list of device devfreqs and return the matched device's
  50  * devfreq info. devfreq_list_lock should be held by the caller.
  51  */
  52 static struct devfreq *find_device_devfreq(struct device *dev)
  53 {
  54         struct devfreq *tmp_devfreq;
  55
  56         if (IS_ERR_OR_NULL(dev)) {
  57                 pr_err("DEVFREQ: %s: Invalid parameters\n", __func__);
  58                 return ERR_PTR(-EINVAL);
  59         }
  60         WARN(!mutex_is_locked(&devfreq_list_lock),
  61              "devfreq_list_lock must be locked.");
  62
  63         list_for_each_entry(tmp_devfreq, &devfreq_list, node) {
  64                 if (tmp_devfreq->dev.parent == dev)
  65                         return tmp_devfreq;
  66         }
  67
  68         return ERR_PTR(-ENODEV);
  69 }
  70
  71 /**
  72  * devfreq_get_freq_level() - Lookup freq_table for the frequency
  73  * @devfreq:    the devfreq instance
  74  * @freq:       the target frequency
  75  */
  76 static int devfreq_get_freq_level(struct devfreq *devfreq, unsigned long freq)
  77 {
  78         int lev;
  79
  80         for (lev = 0; lev < devfreq->profile->max_state; lev++)
  81                 if (freq == devfreq->profile->freq_table[lev])
  82                         return lev;
  83
  84         return -EINVAL;
  85 }
  86
  87 /**
  88  * devfreq_update_status() - Update statistics of devfreq behavior
  89  * @devfreq:    the devfreq instance
  90  * @freq:       the update target frequency
  91  */
  92 static int devfreq_update_status(struct devfreq *devfreq, unsigned long freq)
  93 {
  94         int lev, prev_lev, ret = 0;
  95         unsigned long cur_time;
  96
  97         cur_time = jiffies;
  98
  99         prev_lev = devfreq_get_freq_level(devfreq, devfreq->previous_freq);
 100         if (prev_lev < 0) {
 101                 ret = prev_lev;
 102                 goto out;
 103         }
 104
 105         devfreq->time_in_state[prev_lev] +=
 106                          cur_time - devfreq->last_stat_updated;
 107
 108         lev = devfreq_get_freq_level(devfreq, freq);
 109         if (lev < 0) {
 110                 ret = lev;
 111                 goto out;
 112         }
 113
 114         if (lev != prev_lev) {
 115                 devfreq->trans_table[(prev_lev *
 116                                 devfreq->profile->max_state) + lev]++;
 117                 devfreq->total_trans++;
 118         }
 119
 120 out:
 121         devfreq->last_stat_updated = cur_time;
 122         return ret;
 123 }
 124
 125 /**
 126  * find_devfreq_governor() - find devfreq governor from name
 127  * @name:       name of the governor
 128  *
 129  * Search the list of devfreq governors and return the matched
 130  * governor's pointer. devfreq_list_lock should be held by the caller.
 131  */
 132 static struct devfreq_governor *find_devfreq_governor(const char *name)
 133 {
 134         struct devfreq_governor *tmp_governor;
 135
 136         if (IS_ERR_OR_NULL(name)) {
 137                 pr_err("DEVFREQ: %s: Invalid parameters\n", __func__);
 138                 return ERR_PTR(-EINVAL);
 139         }
 140         WARN(!mutex_is_locked(&devfreq_list_lock),
 141              "devfreq_list_lock must be locked.");
 142
 143         list_for_each_entry(tmp_governor, &devfreq_governor_list, node) {
 144                 if (!strncmp(tmp_governor->name, name, DEVFREQ_NAME_LEN))
 145                         return tmp_governor;
 146         }
 147
 148         return ERR_PTR(-ENODEV);
 149 }
 150
 151 /* Load monitoring helper functions for governors use */
 152
 153 /**
 154  * update_devfreq() - Reevaluate the device and configure frequency.
 155  * @devfreq:    the devfreq instance.
 156  *
 157  * Note: Lock devfreq->lock before calling update_devfreq
 158  *       This function is exported for governors.
 159  */
 160 int update_devfreq(struct devfreq *devfreq)
 161 {
 162         unsigned long freq;
 163         int err = 0;
 164         u32 flags = 0;
 165
 166         if (!mutex_is_locked(&devfreq->lock)) {
 167                 WARN(true, "devfreq->lock must be locked by the caller.\n");
 168                 return -EINVAL;
 169         }
 170
 171         if (!devfreq->governor)
 172                 return -EINVAL;
 173
 174         /* Reevaluate the proper frequency */
 175         err = devfreq->governor->get_target_freq(devfreq, &freq);
 176         if (err)
 177                 return err;
 178
 179         /*
 180          * Adjust the frequency with user freq and QoS.
 181          *
 182          * List from the highest priority
 183          * max_freq
 184          * min_freq
 185          */
 186
 187         if (devfreq->min_freq && freq < devfreq->min_freq) {
 188                 freq = devfreq->min_freq;
 189                 flags &= ~DEVFREQ_FLAG_LEAST_UPPER_BOUND; /* Use GLB */
 190         }
 191         if (devfreq->max_freq && freq > devfreq->max_freq) {
 192                 freq = devfreq->max_freq;
 193                 flags |= DEVFREQ_FLAG_LEAST_UPPER_BOUND; /* Use LUB */
 194         }
 195
 196         err = devfreq->profile->target(devfreq->dev.parent, &freq, flags);
 197         if (err)
 198                 return err;
 199
 200         if (devfreq->profile->freq_table)
 201                 if (devfreq_update_status(devfreq, freq))
 202                         dev_err(&devfreq->dev,
 203                                 "Couldn't update frequency transition information.\n");
 204
 205         devfreq->previous_freq = freq;
 206         return err;
 207 }
 208 EXPORT_SYMBOL(update_devfreq);
 209
 210 /**
 211  * devfreq_monitor() - Periodically poll devfreq objects.
 212  * @work:       the work struct used to run devfreq_monitor periodically.
 213  *
 214  */
 215 static void devfreq_monitor(struct work_struct *work)
 216 {
 217         int err;
 218         struct devfreq *devfreq = container_of(work,
 219                                         struct devfreq, work.work);
 220
 221         mutex_lock(&devfreq->lock);
 222         err = update_devfreq(devfreq);
 223         if (err)
 224                 dev_err(&devfreq->dev, "dvfs failed with (%d) error\n", err);
 225
 226         queue_delayed_work(devfreq_wq, &devfreq->work,
 227                                 msecs_to_jiffies(devfreq->profile->polling_ms));
 228         mutex_unlock(&devfreq->lock);
 229 }
 230
 231 /**
 232  * devfreq_monitor_start() - Start load monitoring of devfreq instance
 233  * @devfreq:    the devfreq instance.
 234  *
 235  * Helper function for starting devfreq device load monitoing. By
 236  * default delayed work based monitoring is supported. Function
 237  * to be called from governor in response to DEVFREQ_GOV_START
 238  * event when device is added to devfreq framework.
 239  */
 240 void devfreq_monitor_start(struct devfreq *devfreq)
 241 {
 242         INIT_DEFERRABLE_WORK(&devfreq->work, devfreq_monitor);
 243         if (devfreq->profile->polling_ms)
 244                 queue_delayed_work(devfreq_wq, &devfreq->work,
 245                         msecs_to_jiffies(devfreq->profile->polling_ms));
 246 }
 247 EXPORT_SYMBOL(devfreq_monitor_start);
 248
 249 /**
 250  * devfreq_monitor_stop() - Stop load monitoring of a devfreq instance
 251  * @devfreq:    the devfreq instance.
 252  *
 253  * Helper function to stop devfreq device load monitoing. Function
 254  * to be called from governor in response to DEVFREQ_GOV_STOP
 255  * event when device is removed from devfreq framework.
 256  */
 257 void devfreq_monitor_stop(struct devfreq *devfreq)
 258 {
 259         cancel_delayed_work_sync(&devfreq->work);
 260 }
 261 EXPORT_SYMBOL(devfreq_monitor_stop);
 262
 263 /**
 264  * devfreq_monitor_suspend() - Suspend load monitoring of a devfreq instance
 265  * @devfreq:    the devfreq instance.
 266  *
 267  * Helper function to suspend devfreq device load monitoing. Function
 268  * to be called from governor in response to DEVFREQ_GOV_SUSPEND
 269  * event or when polling interval is set to zero.
 270  *
 271  * Note: Though this function is same as devfreq_monitor_stop(),
 272  * intentionally kept separate to provide hooks for collecting
 273  * transition statistics.
 274  */
 275 void devfreq_monitor_suspend(struct devfreq *devfreq)
 276 {
 277         mutex_lock(&devfreq->lock);
 278         if (devfreq->stop_polling) {
 279                 mutex_unlock(&devfreq->lock);
 280                 return;
 281         }
 282
 283         devfreq_update_status(devfreq, devfreq->previous_freq);
 284         devfreq->stop_polling = true;
 285         mutex_unlock(&devfreq->lock);
 286         cancel_delayed_work_sync(&devfreq->work);
 287 }
 288 EXPORT_SYMBOL(devfreq_monitor_suspend);
 289
 290 /**
 291  * devfreq_monitor_resume() - Resume load monitoring of a devfreq instance
 292  * @devfreq:    the devfreq instance.
 293  *
 294  * Helper function to resume devfreq device load monitoing. Function
 295  * to be called from governor in response to DEVFREQ_GOV_RESUME
 296  * event or when polling interval is set to non-zero.
 297  */
 298 void devfreq_monitor_resume(struct devfreq *devfreq)
 299 {
 300         unsigned long freq;
 301
 302         mutex_lock(&devfreq->lock);
 303         if (!devfreq->stop_polling)
 304                 goto out;
 305
 306         if (!delayed_work_pending(&devfreq->work) &&
 307                         devfreq->profile->polling_ms)
 308                 queue_delayed_work(devfreq_wq, &devfreq->work,
 309                         msecs_to_jiffies(devfreq->profile->polling_ms));
 310
 311         devfreq->last_stat_updated = jiffies;
 312         devfreq->stop_polling = false;
 313
 314         if (devfreq->profile->get_cur_freq &&
 315                 !devfreq->profile->get_cur_freq(devfreq->dev.parent, &freq))
 316                 devfreq->previous_freq = freq;
 317
 318 out:
 319         mutex_unlock(&devfreq->lock);
 320 }
 321 EXPORT_SYMBOL(devfreq_monitor_resume);
 322
 323 /**
 324  * devfreq_interval_update() - Update device devfreq monitoring interval
 325  * @devfreq:    the devfreq instance.
 326  * @delay:      new polling interval to be set.
 327  *
 328  * Helper function to set new load monitoring polling interval. Function
 329  * to be called from governor in response to DEVFREQ_GOV_INTERVAL event.
 330  */
 331 void devfreq_interval_update(struct devfreq *devfreq, unsigned int *delay)
 332 {
 333         unsigned int cur_delay = devfreq->profile->polling_ms;
 334         unsigned int new_delay = *delay;
 335
 336         mutex_lock(&devfreq->lock);
 337         devfreq->profile->polling_ms = new_delay;
 338
 339         if (devfreq->stop_polling)
 340                 goto out;
 341
 342         /* if new delay is zero, stop polling */
 343         if (!new_delay) {
 344                 mutex_unlock(&devfreq->lock);
 345                 cancel_delayed_work_sync(&devfreq->work);
 346                 return;
 347         }
 348
 349         /* if current delay is zero, start polling with new delay */
 350         if (!cur_delay) {
 351                 queue_delayed_work(devfreq_wq, &devfreq->work,
 352                         msecs_to_jiffies(devfreq->profile->polling_ms));
 353                 goto out;
 354         }
 355
 356         /* if current delay is greater than new delay, restart polling */
 357         if (cur_delay > new_delay) {
 358                 mutex_unlock(&devfreq->lock);
 359                 cancel_delayed_work_sync(&devfreq->work);
 360                 mutex_lock(&devfreq->lock);
 361                 if (!devfreq->stop_polling)
 362                         queue_delayed_work(devfreq_wq, &devfreq->work,
 363                               msecs_to_jiffies(devfreq->profile->polling_ms));
 364         }
 365 out:
 366         mutex_unlock(&devfreq->lock);
 367 }
 368 EXPORT_SYMBOL(devfreq_interval_update);
 369
 370 /**
 371  * devfreq_notifier_call() - Notify that the device frequency requirements
 372  *                         has been changed out of devfreq framework.
 373  * @nb:         the notifier_block (supposed to be devfreq->nb)
 374  * @type:       not used
 375  * @devp:       not used
 376  *
 377  * Called by a notifier that uses devfreq->nb.
 378  */
 379 static int devfreq_notifier_call(struct notifier_block *nb, unsigned long type,
 380                                  void *devp)
 381 {
 382         struct devfreq *devfreq = container_of(nb, struct devfreq, nb);
 383         int ret;
 384
 385         mutex_lock(&devfreq->lock);
 386         ret = update_devfreq(devfreq);
 387         mutex_unlock(&devfreq->lock);
 388
 389         return ret;
 390 }
 391
 392 /**
 393  * _remove_devfreq() - Remove devfreq from the list and release its resources.
 394  * @devfreq:    the devfreq struct
 395  */
 396 static void _remove_devfreq(struct devfreq *devfreq)
 397 {
 398         mutex_lock(&devfreq_list_lock);
 399         list_del(&devfreq->node);
 400         mutex_unlock(&devfreq_list_lock);
 401
 402         if (devfreq->governor)
 403                 devfreq->governor->event_handler(devfreq,
 404                                                  DEVFREQ_GOV_STOP, NULL);
 405
 406         if (devfreq->profile->exit)
 407                 devfreq->profile->exit(devfreq->dev.parent);
 408
 409         mutex_destroy(&devfreq->lock);
 410         kfree(devfreq);
 411 }
 412
 413 /**
 414  * devfreq_dev_release() - Callback for struct device to release the device.
 415  * @dev:        the devfreq device
 416  *
 417  * This calls _remove_devfreq() if _remove_devfreq() is not called.
 418  */
 419 static void devfreq_dev_release(struct device *dev)
 420 {
 421         struct devfreq *devfreq = to_devfreq(dev);
 422
 423         _remove_devfreq(devfreq);
 424 }
 425
 426 /**
 427  * devfreq_add_device() - Add devfreq feature to the device
 428  * @dev:        the device to add devfreq feature.
 429  * @profile:    device-specific profile to run devfreq.
 430  * @governor_name:      name of the policy to choose frequency.
 431  * @data:       private data for the governor. The devfreq framework does not
 432  *              touch this value.
 433  */
 434 struct devfreq *devfreq_add_device(struct device *dev,
 435                                    struct devfreq_dev_profile *profile,
 436                                    const char *governor_name,
 437                                    void *data)
 438 {
 439         struct devfreq *devfreq;
 440         struct devfreq_governor *governor;
 441         int err = 0;
 442
 443         if (!dev || !profile || !governor_name) {
 444                 dev_err(dev, "%s: Invalid parameters.\n", __func__);
 445                 return ERR_PTR(-EINVAL);
 446         }
 447
 448         mutex_lock(&devfreq_list_lock);
 449         devfreq = find_device_devfreq(dev);
 450         mutex_unlock(&devfreq_list_lock);
 451         if (!IS_ERR(devfreq)) {
 452                 dev_err(dev, "%s: Unable to create devfreq for the device. It already has one.\n", __func__);
 453                 err = -EINVAL;
 454                 goto err_out;
 455         }
 456
 457         devfreq = kzalloc(sizeof(struct devfreq), GFP_KERNEL);
 458         if (!devfreq) {
 459                 dev_err(dev, "%s: Unable to create devfreq for the device\n",
 460                         __func__);
 461                 err = -ENOMEM;
 462                 goto err_out;
 463         }
 464
 465         mutex_init(&devfreq->lock);
 466         mutex_lock(&devfreq->lock);
 467         devfreq->dev.parent = dev;
 468         devfreq->dev.class = devfreq_class;
 469         devfreq->dev.release = devfreq_dev_release;
 470         INIT_LIST_HEAD(&devfreq->node);
 471         devfreq->profile = profile;
 472         strncpy(devfreq->governor_name, governor_name, DEVFREQ_NAME_LEN);
 473         devfreq->previous_freq = profile->initial_freq;
 474         devfreq->data = data;
 475         devfreq->nb.notifier_call = devfreq_notifier_call;
 476
 477         devfreq->trans_table =  devm_kzalloc(dev, sizeof(unsigned int) *
 478                                                 devfreq->profile->max_state *
 479                                                 devfreq->profile->max_state,
 480                                                 GFP_KERNEL);
 481         devfreq->time_in_state = devm_kzalloc(dev, sizeof(unsigned long) *
 482                                                 devfreq->profile->max_state,
 483                                                 GFP_KERNEL);
 484         devfreq->last_stat_updated = jiffies;
 485
 486         dev_set_name(&devfreq->dev, "%s", dev_name(dev));
 487         err = device_register(&devfreq->dev);
 488         if (err) {
 489                 put_device(&devfreq->dev);
 490                 mutex_unlock(&devfreq->lock);
 491                 goto err_out;
 492         }
 493
 494         mutex_unlock(&devfreq->lock);
 495
 496         mutex_lock(&devfreq_list_lock);
 497         list_add(&devfreq->node, &devfreq_list);
 498
 499         governor = find_devfreq_governor(devfreq->governor_name);
 500         if (!IS_ERR(governor))
 501                 devfreq->governor = governor;
 502         if (devfreq->governor)
 503                 err = devfreq->governor->event_handler(devfreq,
 504                                         DEVFREQ_GOV_START, NULL);
 505         mutex_unlock(&devfreq_list_lock);
 506         if (err) {
 507                 dev_err(dev, "%s: Unable to start governor for the device\n",
 508                         __func__);
 509                 goto err_init;
 510         }
 511
 512         return devfreq;
 513
 514 err_init:
 515         list_del(&devfreq->node);
 516         device_unregister(&devfreq->dev);
 517         kfree(devfreq);
 518 err_out:
 519         return ERR_PTR(err);
 520 }
 521 EXPORT_SYMBOL(devfreq_add_device);
 522
 523 /**
 524  * devfreq_remove_device() - Remove devfreq feature from a device.
 525  * @devfreq:    the devfreq instance to be removed
 526  *
 527  * The opposite of devfreq_add_device().
 528  */
 529 int devfreq_remove_device(struct devfreq *devfreq)
 530 {
 531         if (!devfreq)
 532                 return -EINVAL;
 533
 534         device_unregister(&devfreq->dev);
 535         put_device(&devfreq->dev);
 536
 537         return 0;
 538 }
 539 EXPORT_SYMBOL(devfreq_remove_device);
 540
 541 static int devm_devfreq_dev_match(struct device *dev, void *res, void *data)
 542 {
 543         struct devfreq **r = res;
 544
 545         if (WARN_ON(!r || !*r))
 546                 return 0;
 547
 548         return *r == data;
 549 }
 550
 551 static void devm_devfreq_dev_release(struct device *dev, void *res)
 552 {
 553         devfreq_remove_device(*(struct devfreq **)res);
 554 }
 555
 556 /**
 557  * devm_devfreq_add_device() - Resource-managed devfreq_add_device()
 558  * @dev:        the device to add devfreq feature.
 559  * @profile:    device-specific profile to run devfreq.
 560  * @governor_name:      name of the policy to choose frequency.
 561  * @data:       private data for the governor. The devfreq framework does not
 562  *              touch this value.
 563  *
 564  * This function manages automatically the memory of devfreq device using device
 565  * resource management and simplify the free operation for memory of devfreq
 566  * device.
 567  */
 568 struct devfreq *devm_devfreq_add_device(struct device *dev,
 569                                         struct devfreq_dev_profile *profile,
 570                                         const char *governor_name,
 571                                         void *data)
 572 {
 573         struct devfreq **ptr, *devfreq;
 574
 575         ptr = devres_alloc(devm_devfreq_dev_release, sizeof(*ptr), GFP_KERNEL);
 576         if (!ptr)
 577                 return ERR_PTR(-ENOMEM);
 578
 579         devfreq = devfreq_add_device(dev, profile, governor_name, data);
 580         if (IS_ERR(devfreq)) {
 581                 devres_free(ptr);
 582                 return devfreq;
 583         }
 584
 585         *ptr = devfreq;
 586         devres_add(dev, ptr);
 587
 588         return devfreq;
 589 }
 590 EXPORT_SYMBOL(devm_devfreq_add_device);
 591
 592 /**
 593  * devm_devfreq_remove_device() - Resource-managed devfreq_remove_device()
 594  * @dev:        the device to add devfreq feature.
 595  * @devfreq:    the devfreq instance to be removed
 596  */
 597 void devm_devfreq_remove_device(struct device *dev, struct devfreq *devfreq)
 598 {
 599         WARN_ON(devres_release(dev, devm_devfreq_dev_release,
 600                                devm_devfreq_dev_match, devfreq));
 601 }
 602 EXPORT_SYMBOL(devm_devfreq_remove_device);
 603
 604 /**
 605  * devfreq_suspend_device() - Suspend devfreq of a device.
 606  * @devfreq: the devfreq instance to be suspended
 607  *
 608  * This function is intended to be called by the pm callbacks
 609  * (e.g., runtime_suspend, suspend) of the device driver that
 610  * holds the devfreq.
 611  */
 612 int devfreq_suspend_device(struct devfreq *devfreq)
 613 {
 614         if (!devfreq)
 615                 return -EINVAL;
 616
 617         if (!devfreq->governor)
 618                 return 0;
 619
 620         return devfreq->governor->event_handler(devfreq,
 621                                 DEVFREQ_GOV_SUSPEND, NULL);
 622 }
 623 EXPORT_SYMBOL(devfreq_suspend_device);
 624
 625 /**
 626  * devfreq_resume_device() - Resume devfreq of a device.
 627  * @devfreq: the devfreq instance to be resumed
 628  *
 629  * This function is intended to be called by the pm callbacks
 630  * (e.g., runtime_resume, resume) of the device driver that
 631  * holds the devfreq.
 632  */
 633 int devfreq_resume_device(struct devfreq *devfreq)
 634 {
 635         if (!devfreq)
 636                 return -EINVAL;
 637
 638         if (!devfreq->governor)
 639                 return 0;
 640
 641         return devfreq->governor->event_handler(devfreq,
 642                                 DEVFREQ_GOV_RESUME, NULL);
 643 }
 644 EXPORT_SYMBOL(devfreq_resume_device);
 645
 646 /**
 647  * devfreq_add_governor() - Add devfreq governor
 648  * @governor:   the devfreq governor to be added
 649  */
 650 int devfreq_add_governor(struct devfreq_governor *governor)
 651 {
 652         struct devfreq_governor *g;
 653         struct devfreq *devfreq;
 654         int err = 0;
 655
 656         if (!governor) {
 657                 pr_err("%s: Invalid parameters.\n", __func__);
 658                 return -EINVAL;
 659         }
 660
 661         mutex_lock(&devfreq_list_lock);
 662         g = find_devfreq_governor(governor->name);
 663         if (!IS_ERR(g)) {
 664                 pr_err("%s: governor %s already registered\n", __func__,
 665                        g->name);
 666                 err = -EINVAL;
 667                 goto err_out;
 668         }
 669
 670         list_add(&governor->node, &devfreq_governor_list);
 671
 672         list_for_each_entry(devfreq, &devfreq_list, node) {
 673                 int ret = 0;
 674                 struct device *dev = devfreq->dev.parent;
 675
 676                 if (!strncmp(devfreq->governor_name, governor->name,
 677                              DEVFREQ_NAME_LEN)) {
 678                         /* The following should never occur */
 679                         if (devfreq->governor) {
 680                                 dev_warn(dev,
 681                                          "%s: Governor %s already present\n",
 682                                          __func__, devfreq->governor->name);
 683                                 ret = devfreq->governor->event_handler(devfreq,
 684                                                         DEVFREQ_GOV_STOP, NULL);
 685                                 if (ret) {
 686                                         dev_warn(dev,
 687                                                  "%s: Governor %s stop = %d\n",
 688                                                  __func__,
 689                                                  devfreq->governor->name, ret);
 690                                 }
 691                                 /* Fall through */
 692                         }
 693                         devfreq->governor = governor;
 694                         ret = devfreq->governor->event_handler(devfreq,
 695                                                 DEVFREQ_GOV_START, NULL);
 696                         if (ret) {
 697                                 dev_warn(dev, "%s: Governor %s start=%d\n",
 698                                          __func__, devfreq->governor->name,
 699                                          ret);
 700                         }
 701                 }
 702         }
 703
 704 err_out:
 705         mutex_unlock(&devfreq_list_lock);
 706
 707         return err;
 708 }
 709 EXPORT_SYMBOL(devfreq_add_governor);
 710
 711 /**
 712  * devfreq_remove_device() - Remove devfreq feature from a device.
 713  * @governor:   the devfreq governor to be removed
 714  */
 715 int devfreq_remove_governor(struct devfreq_governor *governor)
 716 {
 717         struct devfreq_governor *g;
 718         struct devfreq *devfreq;
 719         int err = 0;
 720
 721         if (!governor) {
 722                 pr_err("%s: Invalid parameters.\n", __func__);
 723                 return -EINVAL;
 724         }
 725
 726         mutex_lock(&devfreq_list_lock);
 727         g = find_devfreq_governor(governor->name);
 728         if (IS_ERR(g)) {
 729                 pr_err("%s: governor %s not registered\n", __func__,
 730                        governor->name);
 731                 err = PTR_ERR(g);
 732                 goto err_out;
 733         }
 734         list_for_each_entry(devfreq, &devfreq_list, node) {
 735                 int ret;
 736                 struct device *dev = devfreq->dev.parent;
 737
 738                 if (!strncmp(devfreq->governor_name, governor->name,
 739                              DEVFREQ_NAME_LEN)) {
 740                         /* we should have a devfreq governor! */
 741                         if (!devfreq->governor) {
 742                                 dev_warn(dev, "%s: Governor %s NOT present\n",
 743                                          __func__, governor->name);
 744                                 continue;
 745                                 /* Fall through */
 746                         }
 747                         ret = devfreq->governor->event_handler(devfreq,
 748                                                 DEVFREQ_GOV_STOP, NULL);
 749                         if (ret) {
 750                                 dev_warn(dev, "%s: Governor %s stop=%d\n",
 751                                          __func__, devfreq->governor->name,
 752                                          ret);
 753                         }
 754                         devfreq->governor = NULL;
 755                 }
 756         }
 757
 758         list_del(&governor->node);
 759 err_out:
 760         mutex_unlock(&devfreq_list_lock);
 761
 762         return err;
 763 }
 764 EXPORT_SYMBOL(devfreq_remove_governor);
 765
 766 static ssize_t governor_show(struct device *dev,
 767                              struct device_attribute *attr, char *buf)
 768 {
 769         if (!to_devfreq(dev)->governor)
 770                 return -EINVAL;
 771
 772         return sprintf(buf, "%s\n", to_devfreq(dev)->governor->name);
 773 }
 774
 775 static ssize_t governor_store(struct device *dev, struct device_attribute *attr,
 776                               const char *buf, size_t count)
 777 {
 778         struct devfreq *df = to_devfreq(dev);
 779         int ret;
 780         char str_governor[DEVFREQ_NAME_LEN + 1];
 781         struct devfreq_governor *governor;
 782
 783         ret = sscanf(buf, "%" __stringify(DEVFREQ_NAME_LEN) "s", str_governor);
 784         if (ret != 1)
 785                 return -EINVAL;
 786
 787         mutex_lock(&devfreq_list_lock);
 788         governor = find_devfreq_governor(str_governor);
 789         if (IS_ERR(governor)) {
 790                 ret = PTR_ERR(governor);
 791                 goto out;
 792         }
 793         if (df->governor == governor) {
 794                 ret = 0;
 795                 goto out;
 796         }
 797
 798         if (df->governor) {
 799                 ret = df->governor->event_handler(df, DEVFREQ_GOV_STOP, NULL);
 800                 if (ret) {
 801                         dev_warn(dev, "%s: Governor %s not stopped(%d)\n",
 802                                  __func__, df->governor->name, ret);
 803                         goto out;
 804                 }
 805         }
 806         df->governor = governor;
 807         strncpy(df->governor_name, governor->name, DEVFREQ_NAME_LEN);
 808         ret = df->governor->event_handler(df, DEVFREQ_GOV_START, NULL);
 809         if (ret)
 810                 dev_warn(dev, "%s: Governor %s not started(%d)\n",
 811                          __func__, df->governor->name, ret);
 812 out:
 813         mutex_unlock(&devfreq_list_lock);
 814
 815         if (!ret)
 816                 ret = count;
 817         return ret;
 818 }
 819 static DEVICE_ATTR_RW(governor);
 820
 821 static ssize_t available_governors_show(struct device *d,
 822                                         struct device_attribute *attr,
 823                                         char *buf)
 824 {
 825         struct devfreq_governor *tmp_governor;
 826         ssize_t count = 0;
 827
 828         mutex_lock(&devfreq_list_lock);
 829         list_for_each_entry(tmp_governor, &devfreq_governor_list, node)
 830                 count += scnprintf(&buf[count], (PAGE_SIZE - count - 2),
 831                                    "%s ", tmp_governor->name);
 832         mutex_unlock(&devfreq_list_lock);
 833
 834         /* Truncate the trailing space */
 835         if (count)
 836                 count--;
 837
 838         count += sprintf(&buf[count], "\n");
 839
 840         return count;
 841 }
 842 static DEVICE_ATTR_RO(available_governors);
 843
 844 static ssize_t cur_freq_show(struct device *dev, struct device_attribute *attr,
 845                              char *buf)
 846 {
 847         unsigned long freq;
 848         struct devfreq *devfreq = to_devfreq(dev);
 849
 850         if (devfreq->profile->get_cur_freq &&
 851                 !devfreq->profile->get_cur_freq(devfreq->dev.parent, &freq))
 852                         return sprintf(buf, "%lu\n", freq);
 853
 854         return sprintf(buf, "%lu\n", devfreq->previous_freq);
 855 }
 856 static DEVICE_ATTR_RO(cur_freq);
 857
 858 static ssize_t target_freq_show(struct device *dev,
 859                                 struct device_attribute *attr, char *buf)
 860 {
 861         return sprintf(buf, "%lu\n", to_devfreq(dev)->previous_freq);
 862 }
 863 static DEVICE_ATTR_RO(target_freq);
 864
 865 static ssize_t polling_interval_show(struct device *dev,
 866                                      struct device_attribute *attr, char *buf)
 867 {
 868         return sprintf(buf, "%d\n", to_devfreq(dev)->profile->polling_ms);
 869 }
 870
 871 static ssize_t polling_interval_store(struct device *dev,
 872                                       struct device_attribute *attr,
 873                                       const char *buf, size_t count)
 874 {
 875         struct devfreq *df = to_devfreq(dev);
 876         unsigned int value;
 877         int ret;
 878
 879         if (!df->governor)
 880                 return -EINVAL;
 881
 882         ret = sscanf(buf, "%u", &value);
 883         if (ret != 1)
 884                 return -EINVAL;
 885
 886         df->governor->event_handler(df, DEVFREQ_GOV_INTERVAL, &value);
 887         ret = count;
 888
 889         return ret;
 890 }
 891 static DEVICE_ATTR_RW(polling_interval);
 892
 893 static ssize_t min_freq_store(struct device *dev, struct device_attribute *attr,
 894                               const char *buf, size_t count)
 895 {
 896         struct devfreq *df = to_devfreq(dev);
 897         unsigned long value;
 898         int ret;
 899         unsigned long max;
 900
 901         ret = sscanf(buf, "%lu", &value);
 902         if (ret != 1)
 903                 return -EINVAL;
 904
 905         mutex_lock(&df->lock);
 906         max = df->max_freq;
 907         if (value && max && value > max) {
 908                 ret = -EINVAL;
 909                 goto unlock;
 910         }
 911
 912         df->min_freq = value;
 913         update_devfreq(df);
 914         ret = count;
 915 unlock:
 916         mutex_unlock(&df->lock);
 917         return ret;
 918 }
 919
 920 static ssize_t min_freq_show(struct device *dev, struct device_attribute *attr,
 921                              char *buf)
 922 {
 923         return sprintf(buf, "%lu\n", to_devfreq(dev)->min_freq);
 924 }
 925
 926 static ssize_t max_freq_store(struct device *dev, struct device_attribute *attr,
 927                               const char *buf, size_t count)
 928 {
 929         struct devfreq *df = to_devfreq(dev);
 930         unsigned long value;
 931         int ret;
 932         unsigned long min;
 933
 934         ret = sscanf(buf, "%lu", &value);
 935         if (ret != 1)
 936                 return -EINVAL;
 937
 938         mutex_lock(&df->lock);
 939         min = df->min_freq;
 940         if (value && min && value < min) {
 941                 ret = -EINVAL;
 942                 goto unlock;
 943         }
 944
 945         df->max_freq = value;
 946         update_devfreq(df);
 947         ret = count;
 948 unlock:
 949         mutex_unlock(&df->lock);
 950         return ret;
 951 }
 952 static DEVICE_ATTR_RW(min_freq);
 953
 954 static ssize_t max_freq_show(struct device *dev, struct device_attribute *attr,
 955                              char *buf)
 956 {
 957         return sprintf(buf, "%lu\n", to_devfreq(dev)->max_freq);
 958 }
 959 static DEVICE_ATTR_RW(max_freq);
 960
 961 static ssize_t available_frequencies_show(struct device *d,
 962                                           struct device_attribute *attr,
 963                                           char *buf)
 964 {
 965         struct devfreq *df = to_devfreq(d);
 966         struct device *dev = df->dev.parent;
 967         struct dev_pm_opp *opp;
 968         ssize_t count = 0;
 969         unsigned long freq = 0;
 970
 971         rcu_read_lock();
 972         do {
 973                 opp = dev_pm_opp_find_freq_ceil(dev, &freq);
 974                 if (IS_ERR(opp))
 975                         break;
 976
 977                 count += scnprintf(&buf[count], (PAGE_SIZE - count - 2),
 978                                    "%lu ", freq);
 979                 freq++;
 980         } while (1);
 981         rcu_read_unlock();
 982
 983         /* Truncate the trailing space */
 984         if (count)
 985                 count--;
 986
 987         count += sprintf(&buf[count], "\n");
 988
 989         return count;
 990 }
 991 static DEVICE_ATTR_RO(available_frequencies);
 992
 993 static ssize_t trans_stat_show(struct device *dev,
 994                                struct device_attribute *attr, char *buf)
 995 {
 996         struct devfreq *devfreq = to_devfreq(dev);
 997         ssize_t len;
 998         int i, j;
 999         unsigned int max_state = devfreq->profile->max_state;
1000
1001         if (!devfreq->stop_polling &&
1002                         devfreq_update_status(devfreq, devfreq->previous_freq))
1003                 return 0;
1004
1005         len = sprintf(buf, "   From  :   To\n");
1006         len += sprintf(buf + len, "         :");
1007         for (i = 0; i < max_state; i++)
1008                 len += sprintf(buf + len, "%8u",
1009                                 devfreq->profile->freq_table[i]);
1010
1011         len += sprintf(buf + len, "   time(ms)\n");
1012
1013         for (i = 0; i < max_state; i++) {
1014                 if (devfreq->profile->freq_table[i]
1015                                         == devfreq->previous_freq) {
1016                         len += sprintf(buf + len, "*");
1017                 } else {
1018                         len += sprintf(buf + len, " ");
1019                 }
1020                 len += sprintf(buf + len, "%8u:",
1021                                 devfreq->profile->freq_table[i]);
1022                 for (j = 0; j < max_state; j++)
1023                         len += sprintf(buf + len, "%8u",
1024                                 devfreq->trans_table[(i * max_state) + j]);
1025                 len += sprintf(buf + len, "%10u\n",
1026                         jiffies_to_msecs(devfreq->time_in_state[i]));
1027         }
1028
1029         len += sprintf(buf + len, "Total transition : %u\n",
1030                                         devfreq->total_trans);
1031         return len;
1032 }
1033 static DEVICE_ATTR_RO(trans_stat);
1034
1035 static struct attribute *devfreq_attrs[] = {
1036         &dev_attr_governor.attr,
1037         &dev_attr_available_governors.attr,
1038         &dev_attr_cur_freq.attr,
1039         &dev_attr_available_frequencies.attr,
1040         &dev_attr_target_freq.attr,
1041         &dev_attr_polling_interval.attr,
1042         &dev_attr_min_freq.attr,
1043         &dev_attr_max_freq.attr,
1044         &dev_attr_trans_stat.attr,
1045         NULL,
1046 };
1047 ATTRIBUTE_GROUPS(devfreq);
1048
1049 static int __init devfreq_init(void)
1050 {
1051         devfreq_class = class_create(THIS_MODULE, "devfreq");
1052         if (IS_ERR(devfreq_class)) {
1053                 pr_err("%s: couldn't create class\n", __FILE__);
1054                 return PTR_ERR(devfreq_class);
1055         }
1056
1057         devfreq_wq = create_freezable_workqueue("devfreq_wq");
1058         if (!devfreq_wq) {
1059                 class_destroy(devfreq_class);
1060                 pr_err("%s: couldn't create workqueue\n", __FILE__);
1061                 return -ENOMEM;
1062         }
1063         devfreq_class->dev_groups = devfreq_groups;
1064
1065         return 0;
1066 }
1067 subsys_initcall(devfreq_init);
1068
1069 static void __exit devfreq_exit(void)
1070 {
1071         class_destroy(devfreq_class);
1072         destroy_workqueue(devfreq_wq);
1073 }
1074 module_exit(devfreq_exit);
1075
1076 /*
1077  * The followings are helper functions for devfreq user device drivers with
1078  * OPP framework.
1079  */
1080
1081 /**
1082  * devfreq_recommended_opp() - Helper function to get proper OPP for the
1083  *                           freq value given to target callback.
1084  * @dev:        The devfreq user device. (parent of devfreq)
1085  * @freq:       The frequency given to target function
1086  * @flags:      Flags handed from devfreq framework.
1087  *
1088  * Locking: This function must be called under rcu_read_lock(). opp is a rcu
1089  * protected pointer. The reason for the same is that the opp pointer which is
1090  * returned will remain valid for use with opp_get_{voltage, freq} only while
1091  * under the locked area. The pointer returned must be used prior to unlocking
1092  * with rcu_read_unlock() to maintain the integrity of the pointer.
1093  */
1094 struct dev_pm_opp *devfreq_recommended_opp(struct device *dev,
1095                                            unsigned long *freq,
1096                                            u32 flags)
1097 {
1098         struct dev_pm_opp *opp;
1099
1100         if (flags & DEVFREQ_FLAG_LEAST_UPPER_BOUND) {
1101                 /* The freq is an upper bound. opp should be lower */
1102                 opp = dev_pm_opp_find_freq_floor(dev, freq);
1103
1104                 /* If not available, use the closest opp */
1105                 if (opp == ERR_PTR(-ERANGE))
1106                         opp = dev_pm_opp_find_freq_ceil(dev, freq);
1107         } else {
1108                 /* The freq is an lower bound. opp should be higher */
1109                 opp = dev_pm_opp_find_freq_ceil(dev, freq);
1110
1111                 /* If not available, use the closest opp */
1112                 if (opp == ERR_PTR(-ERANGE))
1113                         opp = dev_pm_opp_find_freq_floor(dev, freq);
1114         }
1115
1116         return opp;
1117 }
1118 EXPORT_SYMBOL(devfreq_recommended_opp);
1119
1120 /**
1121  * devfreq_register_opp_notifier() - Helper function to get devfreq notified
1122  *                                 for any changes in the OPP availability
1123  *                                 changes
1124  * @dev:        The devfreq user device. (parent of devfreq)
1125  * @devfreq:    The devfreq object.
1126  */
1127 int devfreq_register_opp_notifier(struct device *dev, struct devfreq *devfreq)
1128 {
1129         struct srcu_notifier_head *nh;
1130         int ret = 0;
1131
1132         rcu_read_lock();
1133         nh = dev_pm_opp_get_notifier(dev);
1134         if (IS_ERR(nh))
1135                 ret = PTR_ERR(nh);
1136         rcu_read_unlock();
1137         if (!ret)
1138                 ret = srcu_notifier_chain_register(nh, &devfreq->nb);
1139
1140         return ret;
1141 }
1142 EXPORT_SYMBOL(devfreq_register_opp_notifier);
1143
1144 /**
1145  * devfreq_unregister_opp_notifier() - Helper function to stop getting devfreq
1146  *                                   notified for any changes in the OPP
1147  *                                   availability changes anymore.
1148  * @dev:        The devfreq user device. (parent of devfreq)
1149  * @devfreq:    The devfreq object.
1150  *
1151  * At exit() callback of devfreq_dev_profile, this must be included if
1152  * devfreq_recommended_opp is used.
1153  */
1154 int devfreq_unregister_opp_notifier(struct device *dev, struct devfreq *devfreq)
1155 {
1156         struct srcu_notifier_head *nh;
1157         int ret = 0;
1158
1159         rcu_read_lock();
1160         nh = dev_pm_opp_get_notifier(dev);
1161         if (IS_ERR(nh))
1162                 ret = PTR_ERR(nh);
1163         rcu_read_unlock();
1164         if (!ret)
1165                 ret = srcu_notifier_chain_unregister(nh, &devfreq->nb);
1166
1167         return ret;
1168 }
1169 EXPORT_SYMBOL(devfreq_unregister_opp_notifier);
1170
1171 static void devm_devfreq_opp_release(struct device *dev, void *res)
1172 {
1173         devfreq_unregister_opp_notifier(dev, *(struct devfreq **)res);
1174 }
1175
1176 /**
1177  * devm_ devfreq_register_opp_notifier()
1178  *              - Resource-managed devfreq_register_opp_notifier()
1179  * @dev:        The devfreq user device. (parent of devfreq)
1180  * @devfreq:    The devfreq object.
1181  */
1182 int devm_devfreq_register_opp_notifier(struct device *dev,
1183                                        struct devfreq *devfreq)
1184 {
1185         struct devfreq **ptr;
1186         int ret;
1187
1188         ptr = devres_alloc(devm_devfreq_opp_release, sizeof(*ptr), GFP_KERNEL);
1189         if (!ptr)
1190                 return -ENOMEM;
1191
1192         ret = devfreq_register_opp_notifier(dev, devfreq);
1193         if (ret) {
1194                 devres_free(ptr);
1195                 return ret;
1196         }
1197
1198         *ptr = devfreq;
1199         devres_add(dev, ptr);
1200
1201         return 0;
1202 }
1203 EXPORT_SYMBOL(devm_devfreq_register_opp_notifier);
1204
1205 /**
1206  * devm_devfreq_unregister_opp_notifier()
1207  *              - Resource-managed devfreq_unregister_opp_notifier()
1208  * @dev:        The devfreq user device. (parent of devfreq)
1209  * @devfreq:    The devfreq object.
1210  */
1211 void devm_devfreq_unregister_opp_notifier(struct device *dev,
1212                                          struct devfreq *devfreq)
1213 {
1214         WARN_ON(devres_release(dev, devm_devfreq_opp_release,
1215                                devm_devfreq_dev_match, devfreq));
1216 }
1217 EXPORT_SYMBOL(devm_devfreq_unregister_opp_notifier);
1218
1219 MODULE_AUTHOR("MyungJoo Ham <myungjoo.ham@samsung.com>");
1220 MODULE_DESCRIPTION("devfreq class support");
1221 MODULE_LICENSE("GPL");