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         if (IS_ERR(find_device_devfreq(devfreq->dev.parent))) {
 400                 mutex_unlock(&devfreq_list_lock);
 401                 dev_warn(&devfreq->dev, "releasing devfreq which doesn't exist\n");
 402                 return;
 403         }
 404         list_del(&devfreq->node);
 405         mutex_unlock(&devfreq_list_lock);
 406
 407         if (devfreq->governor)
 408                 devfreq->governor->event_handler(devfreq,
 409                                                  DEVFREQ_GOV_STOP, NULL);
 410
 411         if (devfreq->profile->exit)
 412                 devfreq->profile->exit(devfreq->dev.parent);
 413
 414         mutex_destroy(&devfreq->lock);
 415         kfree(devfreq);
 416 }
 417
 418 /**
 419  * devfreq_dev_release() - Callback for struct device to release the device.
 420  * @dev:        the devfreq device
 421  *
 422  * This calls _remove_devfreq() if _remove_devfreq() is not called.
 423  */
 424 static void devfreq_dev_release(struct device *dev)
 425 {
 426         struct devfreq *devfreq = to_devfreq(dev);
 427
 428         _remove_devfreq(devfreq);
 429 }
 430
 431 /**
 432  * devfreq_add_device() - Add devfreq feature to the device
 433  * @dev:        the device to add devfreq feature.
 434  * @profile:    device-specific profile to run devfreq.
 435  * @governor_name:      name of the policy to choose frequency.
 436  * @data:       private data for the governor. The devfreq framework does not
 437  *              touch this value.
 438  */
 439 struct devfreq *devfreq_add_device(struct device *dev,
 440                                    struct devfreq_dev_profile *profile,
 441                                    const char *governor_name,
 442                                    void *data)
 443 {
 444         struct devfreq *devfreq;
 445         struct devfreq_governor *governor;
 446         int err = 0;
 447
 448         if (!dev || !profile || !governor_name) {
 449                 dev_err(dev, "%s: Invalid parameters.\n", __func__);
 450                 return ERR_PTR(-EINVAL);
 451         }
 452
 453         mutex_lock(&devfreq_list_lock);
 454         devfreq = find_device_devfreq(dev);
 455         mutex_unlock(&devfreq_list_lock);
 456         if (!IS_ERR(devfreq)) {
 457                 dev_err(dev, "%s: Unable to create devfreq for the device. It already has one.\n", __func__);
 458                 err = -EINVAL;
 459                 goto err_out;
 460         }
 461
 462         devfreq = kzalloc(sizeof(struct devfreq), GFP_KERNEL);
 463         if (!devfreq) {
 464                 dev_err(dev, "%s: Unable to create devfreq for the device\n",
 465                         __func__);
 466                 err = -ENOMEM;
 467                 goto err_out;
 468         }
 469
 470         mutex_init(&devfreq->lock);
 471         mutex_lock(&devfreq->lock);
 472         devfreq->dev.parent = dev;
 473         devfreq->dev.class = devfreq_class;
 474         devfreq->dev.release = devfreq_dev_release;
 475         devfreq->profile = profile;
 476         strncpy(devfreq->governor_name, governor_name, DEVFREQ_NAME_LEN);
 477         devfreq->previous_freq = profile->initial_freq;
 478         devfreq->data = data;
 479         devfreq->nb.notifier_call = devfreq_notifier_call;
 480
 481         devfreq->trans_table =  devm_kzalloc(dev, sizeof(unsigned int) *
 482                                                 devfreq->profile->max_state *
 483                                                 devfreq->profile->max_state,
 484                                                 GFP_KERNEL);
 485         devfreq->time_in_state = devm_kzalloc(dev, sizeof(unsigned long) *
 486                                                 devfreq->profile->max_state,
 487                                                 GFP_KERNEL);
 488         devfreq->last_stat_updated = jiffies;
 489
 490         dev_set_name(&devfreq->dev, "%s", dev_name(dev));
 491         err = device_register(&devfreq->dev);
 492         if (err) {
 493                 put_device(&devfreq->dev);
 494                 mutex_unlock(&devfreq->lock);
 495                 goto err_dev;
 496         }
 497
 498         mutex_unlock(&devfreq->lock);
 499
 500         mutex_lock(&devfreq_list_lock);
 501         list_add(&devfreq->node, &devfreq_list);
 502
 503         governor = find_devfreq_governor(devfreq->governor_name);
 504         if (!IS_ERR(governor))
 505                 devfreq->governor = governor;
 506         if (devfreq->governor)
 507                 err = devfreq->governor->event_handler(devfreq,
 508                                         DEVFREQ_GOV_START, NULL);
 509         mutex_unlock(&devfreq_list_lock);
 510         if (err) {
 511                 dev_err(dev, "%s: Unable to start governor for the device\n",
 512                         __func__);
 513                 goto err_init;
 514         }
 515
 516         return devfreq;
 517
 518 err_init:
 519         list_del(&devfreq->node);
 520         device_unregister(&devfreq->dev);
 521 err_dev:
 522         kfree(devfreq);
 523 err_out:
 524         return ERR_PTR(err);
 525 }
 526 EXPORT_SYMBOL(devfreq_add_device);
 527
 528 /**
 529  * devfreq_remove_device() - Remove devfreq feature from a device.
 530  * @devfreq:    the devfreq instance to be removed
 531  *
 532  * The opposite of devfreq_add_device().
 533  */
 534 int devfreq_remove_device(struct devfreq *devfreq)
 535 {
 536         if (!devfreq)
 537                 return -EINVAL;
 538
 539         device_unregister(&devfreq->dev);
 540         put_device(&devfreq->dev);
 541
 542         return 0;
 543 }
 544 EXPORT_SYMBOL(devfreq_remove_device);
 545
 546 static int devm_devfreq_dev_match(struct device *dev, void *res, void *data)
 547 {
 548         struct devfreq **r = res;
 549
 550         if (WARN_ON(!r || !*r))
 551                 return 0;
 552
 553         return *r == data;
 554 }
 555
 556 static void devm_devfreq_dev_release(struct device *dev, void *res)
 557 {
 558         devfreq_remove_device(*(struct devfreq **)res);
 559 }
 560
 561 /**
 562  * devm_devfreq_add_device() - Resource-managed devfreq_add_device()
 563  * @dev:        the device to add devfreq feature.
 564  * @profile:    device-specific profile to run devfreq.
 565  * @governor_name:      name of the policy to choose frequency.
 566  * @data:       private data for the governor. The devfreq framework does not
 567  *              touch this value.
 568  *
 569  * This function manages automatically the memory of devfreq device using device
 570  * resource management and simplify the free operation for memory of devfreq
 571  * device.
 572  */
 573 struct devfreq *devm_devfreq_add_device(struct device *dev,
 574                                         struct devfreq_dev_profile *profile,
 575                                         const char *governor_name,
 576                                         void *data)
 577 {
 578         struct devfreq **ptr, *devfreq;
 579
 580         ptr = devres_alloc(devm_devfreq_dev_release, sizeof(*ptr), GFP_KERNEL);
 581         if (!ptr)
 582                 return ERR_PTR(-ENOMEM);
 583
 584         devfreq = devfreq_add_device(dev, profile, governor_name, data);
 585         if (IS_ERR(devfreq)) {
 586                 devres_free(ptr);
 587                 return ERR_PTR(-ENOMEM);
 588         }
 589
 590         *ptr = devfreq;
 591         devres_add(dev, ptr);
 592
 593         return devfreq;
 594 }
 595 EXPORT_SYMBOL(devm_devfreq_add_device);
 596
 597 /**
 598  * devm_devfreq_remove_device() - Resource-managed devfreq_remove_device()
 599  * @dev:        the device to add devfreq feature.
 600  * @devfreq:    the devfreq instance to be removed
 601  */
 602 void devm_devfreq_remove_device(struct device *dev, struct devfreq *devfreq)
 603 {
 604         WARN_ON(devres_release(dev, devm_devfreq_dev_release,
 605                                devm_devfreq_dev_match, devfreq));
 606 }
 607 EXPORT_SYMBOL(devm_devfreq_remove_device);
 608
 609 /**
 610  * devfreq_suspend_device() - Suspend devfreq of a device.
 611  * @devfreq: the devfreq instance to be suspended
 612  *
 613  * This function is intended to be called by the pm callbacks
 614  * (e.g., runtime_suspend, suspend) of the device driver that
 615  * holds the devfreq.
 616  */
 617 int devfreq_suspend_device(struct devfreq *devfreq)
 618 {
 619         if (!devfreq)
 620                 return -EINVAL;
 621
 622         if (!devfreq->governor)
 623                 return 0;
 624
 625         return devfreq->governor->event_handler(devfreq,
 626                                 DEVFREQ_GOV_SUSPEND, NULL);
 627 }
 628 EXPORT_SYMBOL(devfreq_suspend_device);
 629
 630 /**
 631  * devfreq_resume_device() - Resume devfreq of a device.
 632  * @devfreq: the devfreq instance to be resumed
 633  *
 634  * This function is intended to be called by the pm callbacks
 635  * (e.g., runtime_resume, resume) of the device driver that
 636  * holds the devfreq.
 637  */
 638 int devfreq_resume_device(struct devfreq *devfreq)
 639 {
 640         if (!devfreq)
 641                 return -EINVAL;
 642
 643         if (!devfreq->governor)
 644                 return 0;
 645
 646         return devfreq->governor->event_handler(devfreq,
 647                                 DEVFREQ_GOV_RESUME, NULL);
 648 }
 649 EXPORT_SYMBOL(devfreq_resume_device);
 650
 651 /**
 652  * devfreq_add_governor() - Add devfreq governor
 653  * @governor:   the devfreq governor to be added
 654  */
 655 int devfreq_add_governor(struct devfreq_governor *governor)
 656 {
 657         struct devfreq_governor *g;
 658         struct devfreq *devfreq;
 659         int err = 0;
 660
 661         if (!governor) {
 662                 pr_err("%s: Invalid parameters.\n", __func__);
 663                 return -EINVAL;
 664         }
 665
 666         mutex_lock(&devfreq_list_lock);
 667         g = find_devfreq_governor(governor->name);
 668         if (!IS_ERR(g)) {
 669                 pr_err("%s: governor %s already registered\n", __func__,
 670                        g->name);
 671                 err = -EINVAL;
 672                 goto err_out;
 673         }
 674
 675         list_add(&governor->node, &devfreq_governor_list);
 676
 677         list_for_each_entry(devfreq, &devfreq_list, node) {
 678                 int ret = 0;
 679                 struct device *dev = devfreq->dev.parent;
 680
 681                 if (!strncmp(devfreq->governor_name, governor->name,
 682                              DEVFREQ_NAME_LEN)) {
 683                         /* The following should never occur */
 684                         if (devfreq->governor) {
 685                                 dev_warn(dev,
 686                                          "%s: Governor %s already present\n",
 687                                          __func__, devfreq->governor->name);
 688                                 ret = devfreq->governor->event_handler(devfreq,
 689                                                         DEVFREQ_GOV_STOP, NULL);
 690                                 if (ret) {
 691                                         dev_warn(dev,
 692                                                  "%s: Governor %s stop = %d\n",
 693                                                  __func__,
 694                                                  devfreq->governor->name, ret);
 695                                 }
 696                                 /* Fall through */
 697                         }
 698                         devfreq->governor = governor;
 699                         ret = devfreq->governor->event_handler(devfreq,
 700                                                 DEVFREQ_GOV_START, NULL);
 701                         if (ret) {
 702                                 dev_warn(dev, "%s: Governor %s start=%d\n",
 703                                          __func__, devfreq->governor->name,
 704                                          ret);
 705                         }
 706                 }
 707         }
 708
 709 err_out:
 710         mutex_unlock(&devfreq_list_lock);
 711
 712         return err;
 713 }
 714 EXPORT_SYMBOL(devfreq_add_governor);
 715
 716 /**
 717  * devfreq_remove_device() - Remove devfreq feature from a device.
 718  * @governor:   the devfreq governor to be removed
 719  */
 720 int devfreq_remove_governor(struct devfreq_governor *governor)
 721 {
 722         struct devfreq_governor *g;
 723         struct devfreq *devfreq;
 724         int err = 0;
 725
 726         if (!governor) {
 727                 pr_err("%s: Invalid parameters.\n", __func__);
 728                 return -EINVAL;
 729         }
 730
 731         mutex_lock(&devfreq_list_lock);
 732         g = find_devfreq_governor(governor->name);
 733         if (IS_ERR(g)) {
 734                 pr_err("%s: governor %s not registered\n", __func__,
 735                        governor->name);
 736                 err = PTR_ERR(g);
 737                 goto err_out;
 738         }
 739         list_for_each_entry(devfreq, &devfreq_list, node) {
 740                 int ret;
 741                 struct device *dev = devfreq->dev.parent;
 742
 743                 if (!strncmp(devfreq->governor_name, governor->name,
 744                              DEVFREQ_NAME_LEN)) {
 745                         /* we should have a devfreq governor! */
 746                         if (!devfreq->governor) {
 747                                 dev_warn(dev, "%s: Governor %s NOT present\n",
 748                                          __func__, governor->name);
 749                                 continue;
 750                                 /* Fall through */
 751                         }
 752                         ret = devfreq->governor->event_handler(devfreq,
 753                                                 DEVFREQ_GOV_STOP, NULL);
 754                         if (ret) {
 755                                 dev_warn(dev, "%s: Governor %s stop=%d\n",
 756                                          __func__, devfreq->governor->name,
 757                                          ret);
 758                         }
 759                         devfreq->governor = NULL;
 760                 }
 761         }
 762
 763         list_del(&governor->node);
 764 err_out:
 765         mutex_unlock(&devfreq_list_lock);
 766
 767         return err;
 768 }
 769 EXPORT_SYMBOL(devfreq_remove_governor);
 770
 771 static ssize_t governor_show(struct device *dev,
 772                              struct device_attribute *attr, char *buf)
 773 {
 774         if (!to_devfreq(dev)->governor)
 775                 return -EINVAL;
 776
 777         return sprintf(buf, "%s\n", to_devfreq(dev)->governor->name);
 778 }
 779
 780 static ssize_t governor_store(struct device *dev, struct device_attribute *attr,
 781                               const char *buf, size_t count)
 782 {
 783         struct devfreq *df = to_devfreq(dev);
 784         int ret;
 785         char str_governor[DEVFREQ_NAME_LEN + 1];
 786         struct devfreq_governor *governor;
 787
 788         ret = sscanf(buf, "%" __stringify(DEVFREQ_NAME_LEN) "s", str_governor);
 789         if (ret != 1)
 790                 return -EINVAL;
 791
 792         mutex_lock(&devfreq_list_lock);
 793         governor = find_devfreq_governor(str_governor);
 794         if (IS_ERR(governor)) {
 795                 ret = PTR_ERR(governor);
 796                 goto out;
 797         }
 798         if (df->governor == governor) {
 799                 ret = 0;
 800                 goto out;
 801         }
 802
 803         if (df->governor) {
 804                 ret = df->governor->event_handler(df, DEVFREQ_GOV_STOP, NULL);
 805                 if (ret) {
 806                         dev_warn(dev, "%s: Governor %s not stopped(%d)\n",
 807                                  __func__, df->governor->name, ret);
 808                         goto out;
 809                 }
 810         }
 811         df->governor = governor;
 812         strncpy(df->governor_name, governor->name, DEVFREQ_NAME_LEN);
 813         ret = df->governor->event_handler(df, DEVFREQ_GOV_START, NULL);
 814         if (ret)
 815                 dev_warn(dev, "%s: Governor %s not started(%d)\n",
 816                          __func__, df->governor->name, ret);
 817 out:
 818         mutex_unlock(&devfreq_list_lock);
 819
 820         if (!ret)
 821                 ret = count;
 822         return ret;
 823 }
 824 static DEVICE_ATTR_RW(governor);
 825
 826 static ssize_t available_governors_show(struct device *d,
 827                                         struct device_attribute *attr,
 828                                         char *buf)
 829 {
 830         struct devfreq_governor *tmp_governor;
 831         ssize_t count = 0;
 832
 833         mutex_lock(&devfreq_list_lock);
 834         list_for_each_entry(tmp_governor, &devfreq_governor_list, node)
 835                 count += scnprintf(&buf[count], (PAGE_SIZE - count - 2),
 836                                    "%s ", tmp_governor->name);
 837         mutex_unlock(&devfreq_list_lock);
 838
 839         /* Truncate the trailing space */
 840         if (count)
 841                 count--;
 842
 843         count += sprintf(&buf[count], "\n");
 844
 845         return count;
 846 }
 847 static DEVICE_ATTR_RO(available_governors);
 848
 849 static ssize_t cur_freq_show(struct device *dev, struct device_attribute *attr,
 850                              char *buf)
 851 {
 852         unsigned long freq;
 853         struct devfreq *devfreq = to_devfreq(dev);
 854
 855         if (devfreq->profile->get_cur_freq &&
 856                 !devfreq->profile->get_cur_freq(devfreq->dev.parent, &freq))
 857                         return sprintf(buf, "%lu\n", freq);
 858
 859         return sprintf(buf, "%lu\n", devfreq->previous_freq);
 860 }
 861 static DEVICE_ATTR_RO(cur_freq);
 862
 863 static ssize_t target_freq_show(struct device *dev,
 864                                 struct device_attribute *attr, char *buf)
 865 {
 866         return sprintf(buf, "%lu\n", to_devfreq(dev)->previous_freq);
 867 }
 868 static DEVICE_ATTR_RO(target_freq);
 869
 870 static ssize_t polling_interval_show(struct device *dev,
 871                                      struct device_attribute *attr, char *buf)
 872 {
 873         return sprintf(buf, "%d\n", to_devfreq(dev)->profile->polling_ms);
 874 }
 875
 876 static ssize_t polling_interval_store(struct device *dev,
 877                                       struct device_attribute *attr,
 878                                       const char *buf, size_t count)
 879 {
 880         struct devfreq *df = to_devfreq(dev);
 881         unsigned int value;
 882         int ret;
 883
 884         if (!df->governor)
 885                 return -EINVAL;
 886
 887         ret = sscanf(buf, "%u", &value);
 888         if (ret != 1)
 889                 return -EINVAL;
 890
 891         df->governor->event_handler(df, DEVFREQ_GOV_INTERVAL, &value);
 892         ret = count;
 893
 894         return ret;
 895 }
 896 static DEVICE_ATTR_RW(polling_interval);
 897
 898 static ssize_t min_freq_store(struct device *dev, struct device_attribute *attr,
 899                               const char *buf, size_t count)
 900 {
 901         struct devfreq *df = to_devfreq(dev);
 902         unsigned long value;
 903         int ret;
 904         unsigned long max;
 905
 906         ret = sscanf(buf, "%lu", &value);
 907         if (ret != 1)
 908                 return -EINVAL;
 909
 910         mutex_lock(&df->lock);
 911         max = df->max_freq;
 912         if (value && max && value > max) {
 913                 ret = -EINVAL;
 914                 goto unlock;
 915         }
 916
 917         df->min_freq = value;
 918         update_devfreq(df);
 919         ret = count;
 920 unlock:
 921         mutex_unlock(&df->lock);
 922         return ret;
 923 }
 924
 925 static ssize_t min_freq_show(struct device *dev, struct device_attribute *attr,
 926                              char *buf)
 927 {
 928         return sprintf(buf, "%lu\n", to_devfreq(dev)->min_freq);
 929 }
 930
 931 static ssize_t max_freq_store(struct device *dev, struct device_attribute *attr,
 932                               const char *buf, size_t count)
 933 {
 934         struct devfreq *df = to_devfreq(dev);
 935         unsigned long value;
 936         int ret;
 937         unsigned long min;
 938
 939         ret = sscanf(buf, "%lu", &value);
 940         if (ret != 1)
 941                 return -EINVAL;
 942
 943         mutex_lock(&df->lock);
 944         min = df->min_freq;
 945         if (value && min && value < min) {
 946                 ret = -EINVAL;
 947                 goto unlock;
 948         }
 949
 950         df->max_freq = value;
 951         update_devfreq(df);
 952         ret = count;
 953 unlock:
 954         mutex_unlock(&df->lock);
 955         return ret;
 956 }
 957 static DEVICE_ATTR_RW(min_freq);
 958
 959 static ssize_t max_freq_show(struct device *dev, struct device_attribute *attr,
 960                              char *buf)
 961 {
 962         return sprintf(buf, "%lu\n", to_devfreq(dev)->max_freq);
 963 }
 964 static DEVICE_ATTR_RW(max_freq);
 965
 966 static ssize_t available_frequencies_show(struct device *d,
 967                                           struct device_attribute *attr,
 968                                           char *buf)
 969 {
 970         struct devfreq *df = to_devfreq(d);
 971         struct device *dev = df->dev.parent;
 972         struct dev_pm_opp *opp;
 973         ssize_t count = 0;
 974         unsigned long freq = 0;
 975
 976         rcu_read_lock();
 977         do {
 978                 opp = dev_pm_opp_find_freq_ceil(dev, &freq);
 979                 if (IS_ERR(opp))
 980                         break;
 981
 982                 count += scnprintf(&buf[count], (PAGE_SIZE - count - 2),
 983                                    "%lu ", freq);
 984                 freq++;
 985         } while (1);
 986         rcu_read_unlock();
 987
 988         /* Truncate the trailing space */
 989         if (count)
 990                 count--;
 991
 992         count += sprintf(&buf[count], "\n");
 993
 994         return count;
 995 }
 996 static DEVICE_ATTR_RO(available_frequencies);
 997
 998 static ssize_t trans_stat_show(struct device *dev,
 999                                struct device_attribute *attr, char *buf)
1000 {
1001         struct devfreq *devfreq = to_devfreq(dev);
1002         ssize_t len;
1003         int i, j;
1004         unsigned int max_state = devfreq->profile->max_state;
1005
1006         if (!devfreq->stop_polling &&
1007                         devfreq_update_status(devfreq, devfreq->previous_freq))
1008                 return 0;
1009
1010         len = sprintf(buf, "   From  :   To\n");
1011         len += sprintf(buf + len, "         :");
1012         for (i = 0; i < max_state; i++)
1013                 len += sprintf(buf + len, "%8u",
1014                                 devfreq->profile->freq_table[i]);
1015
1016         len += sprintf(buf + len, "   time(ms)\n");
1017
1018         for (i = 0; i < max_state; i++) {
1019                 if (devfreq->profile->freq_table[i]
1020                                         == devfreq->previous_freq) {
1021                         len += sprintf(buf + len, "*");
1022                 } else {
1023                         len += sprintf(buf + len, " ");
1024                 }
1025                 len += sprintf(buf + len, "%8u:",
1026                                 devfreq->profile->freq_table[i]);
1027                 for (j = 0; j < max_state; j++)
1028                         len += sprintf(buf + len, "%8u",
1029                                 devfreq->trans_table[(i * max_state) + j]);
1030                 len += sprintf(buf + len, "%10u\n",
1031                         jiffies_to_msecs(devfreq->time_in_state[i]));
1032         }
1033
1034         len += sprintf(buf + len, "Total transition : %u\n",
1035                                         devfreq->total_trans);
1036         return len;
1037 }
1038 static DEVICE_ATTR_RO(trans_stat);
1039
1040 static struct attribute *devfreq_attrs[] = {
1041         &dev_attr_governor.attr,
1042         &dev_attr_available_governors.attr,
1043         &dev_attr_cur_freq.attr,
1044         &dev_attr_available_frequencies.attr,
1045         &dev_attr_target_freq.attr,
1046         &dev_attr_polling_interval.attr,
1047         &dev_attr_min_freq.attr,
1048         &dev_attr_max_freq.attr,
1049         &dev_attr_trans_stat.attr,
1050         NULL,
1051 };
1052 ATTRIBUTE_GROUPS(devfreq);
1053
1054 static int __init devfreq_init(void)
1055 {
1056         devfreq_class = class_create(THIS_MODULE, "devfreq");
1057         if (IS_ERR(devfreq_class)) {
1058                 pr_err("%s: couldn't create class\n", __FILE__);
1059                 return PTR_ERR(devfreq_class);
1060         }
1061
1062         devfreq_wq = create_freezable_workqueue("devfreq_wq");
1063         if (!devfreq_wq) {
1064                 class_destroy(devfreq_class);
1065                 pr_err("%s: couldn't create workqueue\n", __FILE__);
1066                 return -ENOMEM;
1067         }
1068         devfreq_class->dev_groups = devfreq_groups;
1069
1070         return 0;
1071 }
1072 subsys_initcall(devfreq_init);
1073
1074 static void __exit devfreq_exit(void)
1075 {
1076         class_destroy(devfreq_class);
1077         destroy_workqueue(devfreq_wq);
1078 }
1079 module_exit(devfreq_exit);
1080
1081 /*
1082  * The followings are helper functions for devfreq user device drivers with
1083  * OPP framework.
1084  */
1085
1086 /**
1087  * devfreq_recommended_opp() - Helper function to get proper OPP for the
1088  *                           freq value given to target callback.
1089  * @dev:        The devfreq user device. (parent of devfreq)
1090  * @freq:       The frequency given to target function
1091  * @flags:      Flags handed from devfreq framework.
1092  *
1093  * Locking: This function must be called under rcu_read_lock(). opp is a rcu
1094  * protected pointer. The reason for the same is that the opp pointer which is
1095  * returned will remain valid for use with opp_get_{voltage, freq} only while
1096  * under the locked area. The pointer returned must be used prior to unlocking
1097  * with rcu_read_unlock() to maintain the integrity of the pointer.
1098  */
1099 struct dev_pm_opp *devfreq_recommended_opp(struct device *dev,
1100                                            unsigned long *freq,
1101                                            u32 flags)
1102 {
1103         struct dev_pm_opp *opp;
1104
1105         if (flags & DEVFREQ_FLAG_LEAST_UPPER_BOUND) {
1106                 /* The freq is an upper bound. opp should be lower */
1107                 opp = dev_pm_opp_find_freq_floor(dev, freq);
1108
1109                 /* If not available, use the closest opp */
1110                 if (opp == ERR_PTR(-ERANGE))
1111                         opp = dev_pm_opp_find_freq_ceil(dev, freq);
1112         } else {
1113                 /* The freq is an lower bound. opp should be higher */
1114                 opp = dev_pm_opp_find_freq_ceil(dev, freq);
1115
1116                 /* If not available, use the closest opp */
1117                 if (opp == ERR_PTR(-ERANGE))
1118                         opp = dev_pm_opp_find_freq_floor(dev, freq);
1119         }
1120
1121         return opp;
1122 }
1123 EXPORT_SYMBOL(devfreq_recommended_opp);
1124
1125 /**
1126  * devfreq_register_opp_notifier() - Helper function to get devfreq notified
1127  *                                 for any changes in the OPP availability
1128  *                                 changes
1129  * @dev:        The devfreq user device. (parent of devfreq)
1130  * @devfreq:    The devfreq object.
1131  */
1132 int devfreq_register_opp_notifier(struct device *dev, struct devfreq *devfreq)
1133 {
1134         struct srcu_notifier_head *nh;
1135         int ret = 0;
1136
1137         rcu_read_lock();
1138         nh = dev_pm_opp_get_notifier(dev);
1139         if (IS_ERR(nh))
1140                 ret = PTR_ERR(nh);
1141         rcu_read_unlock();
1142         if (!ret)
1143                 ret = srcu_notifier_chain_register(nh, &devfreq->nb);
1144
1145         return ret;
1146 }
1147 EXPORT_SYMBOL(devfreq_register_opp_notifier);
1148
1149 /**
1150  * devfreq_unregister_opp_notifier() - Helper function to stop getting devfreq
1151  *                                   notified for any changes in the OPP
1152  *                                   availability changes anymore.
1153  * @dev:        The devfreq user device. (parent of devfreq)
1154  * @devfreq:    The devfreq object.
1155  *
1156  * At exit() callback of devfreq_dev_profile, this must be included if
1157  * devfreq_recommended_opp is used.
1158  */
1159 int devfreq_unregister_opp_notifier(struct device *dev, struct devfreq *devfreq)
1160 {
1161         struct srcu_notifier_head *nh;
1162         int ret = 0;
1163
1164         rcu_read_lock();
1165         nh = dev_pm_opp_get_notifier(dev);
1166         if (IS_ERR(nh))
1167                 ret = PTR_ERR(nh);
1168         rcu_read_unlock();
1169         if (!ret)
1170                 ret = srcu_notifier_chain_unregister(nh, &devfreq->nb);
1171
1172         return ret;
1173 }
1174 EXPORT_SYMBOL(devfreq_unregister_opp_notifier);
1175
1176 static void devm_devfreq_opp_release(struct device *dev, void *res)
1177 {
1178         devfreq_unregister_opp_notifier(dev, *(struct devfreq **)res);
1179 }
1180
1181 /**
1182  * devm_ devfreq_register_opp_notifier()
1183  *              - Resource-managed devfreq_register_opp_notifier()
1184  * @dev:        The devfreq user device. (parent of devfreq)
1185  * @devfreq:    The devfreq object.
1186  */
1187 int devm_devfreq_register_opp_notifier(struct device *dev,
1188                                        struct devfreq *devfreq)
1189 {
1190         struct devfreq **ptr;
1191         int ret;
1192
1193         ptr = devres_alloc(devm_devfreq_opp_release, sizeof(*ptr), GFP_KERNEL);
1194         if (!ptr)
1195                 return -ENOMEM;
1196
1197         ret = devfreq_register_opp_notifier(dev, devfreq);
1198         if (ret) {
1199                 devres_free(ptr);
1200                 return ret;
1201         }
1202
1203         *ptr = devfreq;
1204         devres_add(dev, ptr);
1205
1206         return 0;
1207 }
1208 EXPORT_SYMBOL(devm_devfreq_register_opp_notifier);
1209
1210 /**
1211  * devm_devfreq_unregister_opp_notifier()
1212  *              - Resource-managed devfreq_unregister_opp_notifier()
1213  * @dev:        The devfreq user device. (parent of devfreq)
1214  * @devfreq:    The devfreq object.
1215  */
1216 void devm_devfreq_unregister_opp_notifier(struct device *dev,
1217                                          struct devfreq *devfreq)
1218 {
1219         WARN_ON(devres_release(dev, devm_devfreq_opp_release,
1220                                devm_devfreq_dev_match, devfreq));
1221 }
1222 EXPORT_SYMBOL(devm_devfreq_unregister_opp_notifier);
1223
1224 MODULE_AUTHOR("MyungJoo Ham <myungjoo.ham@samsung.com>");
1225 MODULE_DESCRIPTION("devfreq class support");
1226 MODULE_LICENSE("GPL");