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