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 (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, 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 (unlikely(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 freuqency with user freq and QoS.
 181          *
 182          * List from the highest proiority
 183          * max_freq (probably called by thermal when it's too hot)
 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  * @skip:       skip calling device_unregister().
 396  */
 397 static void _remove_devfreq(struct devfreq *devfreq, bool skip)
 398 {
 399         mutex_lock(&devfreq_list_lock);
 400         if (IS_ERR(find_device_devfreq(devfreq->dev.parent))) {
 401                 mutex_unlock(&devfreq_list_lock);
 402                 dev_warn(&devfreq->dev, "releasing devfreq which doesn't exist\n");
 403                 return;
 404         }
 405         list_del(&devfreq->node);
 406         mutex_unlock(&devfreq_list_lock);
 407
 408         if (devfreq->governor)
 409                 devfreq->governor->event_handler(devfreq,
 410                                                  DEVFREQ_GOV_STOP, NULL);
 411
 412         if (devfreq->profile->exit)
 413                 devfreq->profile->exit(devfreq->dev.parent);
 414
 415         if (!skip && get_device(&devfreq->dev)) {
 416                 device_unregister(&devfreq->dev);
 417                 put_device(&devfreq->dev);
 418         }
 419
 420         mutex_destroy(&devfreq->lock);
 421         kfree(devfreq);
 422 }
 423
 424 /**
 425  * devfreq_dev_release() - Callback for struct device to release the device.
 426  * @dev:        the devfreq device
 427  *
 428  * This calls _remove_devfreq() if _remove_devfreq() is not called.
 429  * Note that devfreq_dev_release() could be called by _remove_devfreq() as
 430  * well as by others unregistering the device.
 431  */
 432 static void devfreq_dev_release(struct device *dev)
 433 {
 434         struct devfreq *devfreq = to_devfreq(dev);
 435
 436         _remove_devfreq(devfreq, true);
 437 }
 438
 439 /**
 440  * devfreq_add_device() - Add devfreq feature to the device
 441  * @dev:        the device to add devfreq feature.
 442  * @profile:    device-specific profile to run devfreq.
 443  * @governor_name:      name of the policy to choose frequency.
 444  * @data:       private data for the governor. The devfreq framework does not
 445  *              touch this value.
 446  */
 447 struct devfreq *devfreq_add_device(struct device *dev,
 448                                    struct devfreq_dev_profile *profile,
 449                                    const char *governor_name,
 450                                    void *data)
 451 {
 452         struct devfreq *devfreq;
 453         struct devfreq_governor *governor;
 454         int err = 0;
 455
 456         if (!dev || !profile || !governor_name) {
 457                 dev_err(dev, "%s: Invalid parameters.\n", __func__);
 458                 return ERR_PTR(-EINVAL);
 459         }
 460
 461         mutex_lock(&devfreq_list_lock);
 462         devfreq = find_device_devfreq(dev);
 463         mutex_unlock(&devfreq_list_lock);
 464         if (!IS_ERR(devfreq)) {
 465                 dev_err(dev, "%s: Unable to create devfreq for the device. It already has one.\n", __func__);
 466                 err = -EINVAL;
 467                 goto err_out;
 468         }
 469
 470         devfreq = kzalloc(sizeof(struct devfreq), GFP_KERNEL);
 471         if (!devfreq) {
 472                 dev_err(dev, "%s: Unable to create devfreq for the device\n",
 473                         __func__);
 474                 err = -ENOMEM;
 475                 goto err_out;
 476         }
 477
 478         mutex_init(&devfreq->lock);
 479         mutex_lock(&devfreq->lock);
 480         devfreq->dev.parent = dev;
 481         devfreq->dev.class = devfreq_class;
 482         devfreq->dev.release = devfreq_dev_release;
 483         devfreq->profile = profile;
 484         strncpy(devfreq->governor_name, governor_name, DEVFREQ_NAME_LEN);
 485         devfreq->previous_freq = profile->initial_freq;
 486         devfreq->data = data;
 487         devfreq->nb.notifier_call = devfreq_notifier_call;
 488
 489         devfreq->trans_table =  devm_kzalloc(dev, sizeof(unsigned int) *
 490                                                 devfreq->profile->max_state *
 491                                                 devfreq->profile->max_state,
 492                                                 GFP_KERNEL);
 493         devfreq->time_in_state = devm_kzalloc(dev, sizeof(unsigned int) *
 494                                                 devfreq->profile->max_state,
 495                                                 GFP_KERNEL);
 496         devfreq->last_stat_updated = jiffies;
 497
 498         dev_set_name(&devfreq->dev, "%s", dev_name(dev));
 499         err = device_register(&devfreq->dev);
 500         if (err) {
 501                 put_device(&devfreq->dev);
 502                 mutex_unlock(&devfreq->lock);
 503                 goto err_dev;
 504         }
 505
 506         mutex_unlock(&devfreq->lock);
 507
 508         mutex_lock(&devfreq_list_lock);
 509         list_add(&devfreq->node, &devfreq_list);
 510
 511         governor = find_devfreq_governor(devfreq->governor_name);
 512         if (!IS_ERR(governor))
 513                 devfreq->governor = governor;
 514         if (devfreq->governor)
 515                 err = devfreq->governor->event_handler(devfreq,
 516                                         DEVFREQ_GOV_START, NULL);
 517         mutex_unlock(&devfreq_list_lock);
 518         if (err) {
 519                 dev_err(dev, "%s: Unable to start governor for the device\n",
 520                         __func__);
 521                 goto err_init;
 522         }
 523
 524         return devfreq;
 525
 526 err_init:
 527         list_del(&devfreq->node);
 528         device_unregister(&devfreq->dev);
 529 err_dev:
 530         kfree(devfreq);
 531 err_out:
 532         return ERR_PTR(err);
 533 }
 534 EXPORT_SYMBOL(devfreq_add_device);
 535
 536 /**
 537  * devfreq_remove_device() - Remove devfreq feature from a device.
 538  * @devfreq:    the devfreq instance to be removed
 539  *
 540  * The opposite of devfreq_add_device().
 541  */
 542 int devfreq_remove_device(struct devfreq *devfreq)
 543 {
 544         if (!devfreq)
 545                 return -EINVAL;
 546
 547         _remove_devfreq(devfreq, false);
 548
 549         return 0;
 550 }
 551 EXPORT_SYMBOL(devfreq_remove_device);
 552
 553 /**
 554  * devfreq_suspend_device() - Suspend devfreq of a device.
 555  * @devfreq: the devfreq instance to be suspended
 556  *
 557  * This function is intended to be called by the pm callbacks
 558  * (e.g., runtime_suspend, suspend) of the device driver that
 559  * holds the devfreq.
 560  */
 561 int devfreq_suspend_device(struct devfreq *devfreq)
 562 {
 563         if (!devfreq)
 564                 return -EINVAL;
 565
 566         if (!devfreq->governor)
 567                 return 0;
 568
 569         return devfreq->governor->event_handler(devfreq,
 570                                 DEVFREQ_GOV_SUSPEND, NULL);
 571 }
 572 EXPORT_SYMBOL(devfreq_suspend_device);
 573
 574 /**
 575  * devfreq_resume_device() - Resume devfreq of a device.
 576  * @devfreq: the devfreq instance to be resumed
 577  *
 578  * This function is intended to be called by the pm callbacks
 579  * (e.g., runtime_resume, resume) of the device driver that
 580  * holds the devfreq.
 581  */
 582 int devfreq_resume_device(struct devfreq *devfreq)
 583 {
 584         if (!devfreq)
 585                 return -EINVAL;
 586
 587         if (!devfreq->governor)
 588                 return 0;
 589
 590         return devfreq->governor->event_handler(devfreq,
 591                                 DEVFREQ_GOV_RESUME, NULL);
 592 }
 593 EXPORT_SYMBOL(devfreq_resume_device);
 594
 595 /**
 596  * devfreq_add_governor() - Add devfreq governor
 597  * @governor:   the devfreq governor to be added
 598  */
 599 int devfreq_add_governor(struct devfreq_governor *governor)
 600 {
 601         struct devfreq_governor *g;
 602         struct devfreq *devfreq;
 603         int err = 0;
 604
 605         if (!governor) {
 606                 pr_err("%s: Invalid parameters.\n", __func__);
 607                 return -EINVAL;
 608         }
 609
 610         mutex_lock(&devfreq_list_lock);
 611         g = find_devfreq_governor(governor->name);
 612         if (!IS_ERR(g)) {
 613                 pr_err("%s: governor %s already registered\n", __func__,
 614                        g->name);
 615                 err = -EINVAL;
 616                 goto err_out;
 617         }
 618
 619         list_add(&governor->node, &devfreq_governor_list);
 620
 621         list_for_each_entry(devfreq, &devfreq_list, node) {
 622                 int ret = 0;
 623                 struct device *dev = devfreq->dev.parent;
 624
 625                 if (!strncmp(devfreq->governor_name, governor->name,
 626                              DEVFREQ_NAME_LEN)) {
 627                         /* The following should never occur */
 628                         if (devfreq->governor) {
 629                                 dev_warn(dev,
 630                                          "%s: Governor %s already present\n",
 631                                          __func__, devfreq->governor->name);
 632                                 ret = devfreq->governor->event_handler(devfreq,
 633                                                         DEVFREQ_GOV_STOP, NULL);
 634                                 if (ret) {
 635                                         dev_warn(dev,
 636                                                  "%s: Governor %s stop = %d\n",
 637                                                  __func__,
 638                                                  devfreq->governor->name, ret);
 639                                 }
 640                                 /* Fall through */
 641                         }
 642                         devfreq->governor = governor;
 643                         ret = devfreq->governor->event_handler(devfreq,
 644                                                 DEVFREQ_GOV_START, NULL);
 645                         if (ret) {
 646                                 dev_warn(dev, "%s: Governor %s start=%d\n",
 647                                          __func__, devfreq->governor->name,
 648                                          ret);
 649                         }
 650                 }
 651         }
 652
 653 err_out:
 654         mutex_unlock(&devfreq_list_lock);
 655
 656         return err;
 657 }
 658 EXPORT_SYMBOL(devfreq_add_governor);
 659
 660 /**
 661  * devfreq_remove_device() - Remove devfreq feature from a device.
 662  * @governor:   the devfreq governor to be removed
 663  */
 664 int devfreq_remove_governor(struct devfreq_governor *governor)
 665 {
 666         struct devfreq_governor *g;
 667         struct devfreq *devfreq;
 668         int err = 0;
 669
 670         if (!governor) {
 671                 pr_err("%s: Invalid parameters.\n", __func__);
 672                 return -EINVAL;
 673         }
 674
 675         mutex_lock(&devfreq_list_lock);
 676         g = find_devfreq_governor(governor->name);
 677         if (IS_ERR(g)) {
 678                 pr_err("%s: governor %s not registered\n", __func__,
 679                        governor->name);
 680                 err = PTR_ERR(g);
 681                 goto err_out;
 682         }
 683         list_for_each_entry(devfreq, &devfreq_list, node) {
 684                 int ret;
 685                 struct device *dev = devfreq->dev.parent;
 686
 687                 if (!strncmp(devfreq->governor_name, governor->name,
 688                              DEVFREQ_NAME_LEN)) {
 689                         /* we should have a devfreq governor! */
 690                         if (!devfreq->governor) {
 691                                 dev_warn(dev, "%s: Governor %s NOT present\n",
 692                                          __func__, governor->name);
 693                                 continue;
 694                                 /* Fall through */
 695                         }
 696                         ret = devfreq->governor->event_handler(devfreq,
 697                                                 DEVFREQ_GOV_STOP, NULL);
 698                         if (ret) {
 699                                 dev_warn(dev, "%s: Governor %s stop=%d\n",
 700                                          __func__, devfreq->governor->name,
 701                                          ret);
 702                         }
 703                         devfreq->governor = NULL;
 704                 }
 705         }
 706
 707         list_del(&governor->node);
 708 err_out:
 709         mutex_unlock(&devfreq_list_lock);
 710
 711         return err;
 712 }
 713 EXPORT_SYMBOL(devfreq_remove_governor);
 714
 715 static ssize_t governor_show(struct device *dev,
 716                              struct device_attribute *attr, char *buf)
 717 {
 718         if (!to_devfreq(dev)->governor)
 719                 return -EINVAL;
 720
 721         return sprintf(buf, "%s\n", to_devfreq(dev)->governor->name);
 722 }
 723
 724 static ssize_t governor_store(struct device *dev, struct device_attribute *attr,
 725                               const char *buf, size_t count)
 726 {
 727         struct devfreq *df = to_devfreq(dev);
 728         int ret;
 729         char str_governor[DEVFREQ_NAME_LEN + 1];
 730         struct devfreq_governor *governor;
 731
 732         ret = sscanf(buf, "%" __stringify(DEVFREQ_NAME_LEN) "s", str_governor);
 733         if (ret != 1)
 734                 return -EINVAL;
 735
 736         mutex_lock(&devfreq_list_lock);
 737         governor = find_devfreq_governor(str_governor);
 738         if (IS_ERR(governor)) {
 739                 ret = PTR_ERR(governor);
 740                 goto out;
 741         }
 742         if (df->governor == governor)
 743                 goto out;
 744
 745         if (df->governor) {
 746                 ret = df->governor->event_handler(df, DEVFREQ_GOV_STOP, NULL);
 747                 if (ret) {
 748                         dev_warn(dev, "%s: Governor %s not stopped(%d)\n",
 749                                  __func__, df->governor->name, ret);
 750                         goto out;
 751                 }
 752         }
 753         df->governor = governor;
 754         strncpy(df->governor_name, governor->name, DEVFREQ_NAME_LEN);
 755         ret = df->governor->event_handler(df, DEVFREQ_GOV_START, NULL);
 756         if (ret)
 757                 dev_warn(dev, "%s: Governor %s not started(%d)\n",
 758                          __func__, df->governor->name, ret);
 759 out:
 760         mutex_unlock(&devfreq_list_lock);
 761
 762         if (!ret)
 763                 ret = count;
 764         return ret;
 765 }
 766 static DEVICE_ATTR_RW(governor);
 767
 768 static ssize_t available_governors_show(struct device *d,
 769                                         struct device_attribute *attr,
 770                                         char *buf)
 771 {
 772         struct devfreq_governor *tmp_governor;
 773         ssize_t count = 0;
 774
 775         mutex_lock(&devfreq_list_lock);
 776         list_for_each_entry(tmp_governor, &devfreq_governor_list, node)
 777                 count += scnprintf(&buf[count], (PAGE_SIZE - count - 2),
 778                                    "%s ", tmp_governor->name);
 779         mutex_unlock(&devfreq_list_lock);
 780
 781         /* Truncate the trailing space */
 782         if (count)
 783                 count--;
 784
 785         count += sprintf(&buf[count], "\n");
 786
 787         return count;
 788 }
 789 static DEVICE_ATTR_RO(available_governors);
 790
 791 static ssize_t cur_freq_show(struct device *dev, struct device_attribute *attr,
 792                              char *buf)
 793 {
 794         unsigned long freq;
 795         struct devfreq *devfreq = to_devfreq(dev);
 796
 797         if (devfreq->profile->get_cur_freq &&
 798                 !devfreq->profile->get_cur_freq(devfreq->dev.parent, &freq))
 799                         return sprintf(buf, "%lu\n", freq);
 800
 801         return sprintf(buf, "%lu\n", devfreq->previous_freq);
 802 }
 803 static DEVICE_ATTR_RO(cur_freq);
 804
 805 static ssize_t target_freq_show(struct device *dev,
 806                                 struct device_attribute *attr, char *buf)
 807 {
 808         return sprintf(buf, "%lu\n", to_devfreq(dev)->previous_freq);
 809 }
 810 static DEVICE_ATTR_RO(target_freq);
 811
 812 static ssize_t polling_interval_show(struct device *dev,
 813                                      struct device_attribute *attr, char *buf)
 814 {
 815         return sprintf(buf, "%d\n", to_devfreq(dev)->profile->polling_ms);
 816 }
 817
 818 static ssize_t polling_interval_store(struct device *dev,
 819                                       struct device_attribute *attr,
 820                                       const char *buf, size_t count)
 821 {
 822         struct devfreq *df = to_devfreq(dev);
 823         unsigned int value;
 824         int ret;
 825
 826         if (!df->governor)
 827                 return -EINVAL;
 828
 829         ret = sscanf(buf, "%u", &value);
 830         if (ret != 1)
 831                 return -EINVAL;
 832
 833         df->governor->event_handler(df, DEVFREQ_GOV_INTERVAL, &value);
 834         ret = count;
 835
 836         return ret;
 837 }
 838 static DEVICE_ATTR_RW(polling_interval);
 839
 840 static ssize_t min_freq_store(struct device *dev, struct device_attribute *attr,
 841                               const char *buf, size_t count)
 842 {
 843         struct devfreq *df = to_devfreq(dev);
 844         unsigned long value;
 845         int ret;
 846         unsigned long max;
 847
 848         ret = sscanf(buf, "%lu", &value);
 849         if (ret != 1)
 850                 return -EINVAL;
 851
 852         mutex_lock(&df->lock);
 853         max = df->max_freq;
 854         if (value && max && value > max) {
 855                 ret = -EINVAL;
 856                 goto unlock;
 857         }
 858
 859         df->min_freq = value;
 860         update_devfreq(df);
 861         ret = count;
 862 unlock:
 863         mutex_unlock(&df->lock);
 864         return ret;
 865 }
 866
 867 static ssize_t min_freq_show(struct device *dev, struct device_attribute *attr,
 868                              char *buf)
 869 {
 870         return sprintf(buf, "%lu\n", to_devfreq(dev)->min_freq);
 871 }
 872
 873 static ssize_t max_freq_store(struct device *dev, struct device_attribute *attr,
 874                               const char *buf, size_t count)
 875 {
 876         struct devfreq *df = to_devfreq(dev);
 877         unsigned long value;
 878         int ret;
 879         unsigned long min;
 880
 881         ret = sscanf(buf, "%lu", &value);
 882         if (ret != 1)
 883                 return -EINVAL;
 884
 885         mutex_lock(&df->lock);
 886         min = df->min_freq;
 887         if (value && min && value < min) {
 888                 ret = -EINVAL;
 889                 goto unlock;
 890         }
 891
 892         df->max_freq = value;
 893         update_devfreq(df);
 894         ret = count;
 895 unlock:
 896         mutex_unlock(&df->lock);
 897         return ret;
 898 }
 899 static DEVICE_ATTR_RW(min_freq);
 900
 901 static ssize_t max_freq_show(struct device *dev, struct device_attribute *attr,
 902                              char *buf)
 903 {
 904         return sprintf(buf, "%lu\n", to_devfreq(dev)->max_freq);
 905 }
 906 static DEVICE_ATTR_RW(max_freq);
 907
 908 static ssize_t available_frequencies_show(struct device *d,
 909                                           struct device_attribute *attr,
 910                                           char *buf)
 911 {
 912         struct devfreq *df = to_devfreq(d);
 913         struct device *dev = df->dev.parent;
 914         struct dev_pm_opp *opp;
 915         ssize_t count = 0;
 916         unsigned long freq = 0;
 917
 918         rcu_read_lock();
 919         do {
 920                 opp = dev_pm_opp_find_freq_ceil(dev, &freq);
 921                 if (IS_ERR(opp))
 922                         break;
 923
 924                 count += scnprintf(&buf[count], (PAGE_SIZE - count - 2),
 925                                    "%lu ", freq);
 926                 freq++;
 927         } while (1);
 928         rcu_read_unlock();
 929
 930         /* Truncate the trailing space */
 931         if (count)
 932                 count--;
 933
 934         count += sprintf(&buf[count], "\n");
 935
 936         return count;
 937 }
 938 static DEVICE_ATTR_RO(available_frequencies);
 939
 940 static ssize_t trans_stat_show(struct device *dev,
 941                                struct device_attribute *attr, char *buf)
 942 {
 943         struct devfreq *devfreq = to_devfreq(dev);
 944         ssize_t len;
 945         int i, j;
 946         unsigned int max_state = devfreq->profile->max_state;
 947
 948         if (!devfreq->stop_polling &&
 949                         devfreq_update_status(devfreq, devfreq->previous_freq))
 950                 return 0;
 951
 952         len = sprintf(buf, "   From  :   To\n");
 953         len += sprintf(buf + len, "         :");
 954         for (i = 0; i < max_state; i++)
 955                 len += sprintf(buf + len, "%8u",
 956                                 devfreq->profile->freq_table[i]);
 957
 958         len += sprintf(buf + len, "   time(ms)\n");
 959
 960         for (i = 0; i < max_state; i++) {
 961                 if (devfreq->profile->freq_table[i]
 962                                         == devfreq->previous_freq) {
 963                         len += sprintf(buf + len, "*");
 964                 } else {
 965                         len += sprintf(buf + len, " ");
 966                 }
 967                 len += sprintf(buf + len, "%8u:",
 968                                 devfreq->profile->freq_table[i]);
 969                 for (j = 0; j < max_state; j++)
 970                         len += sprintf(buf + len, "%8u",
 971                                 devfreq->trans_table[(i * max_state) + j]);
 972                 len += sprintf(buf + len, "%10u\n",
 973                         jiffies_to_msecs(devfreq->time_in_state[i]));
 974         }
 975
 976         len += sprintf(buf + len, "Total transition : %u\n",
 977                                         devfreq->total_trans);
 978         return len;
 979 }
 980 static DEVICE_ATTR_RO(trans_stat);
 981
 982 static struct attribute *devfreq_attrs[] = {
 983         &dev_attr_governor.attr,
 984         &dev_attr_available_governors.attr,
 985         &dev_attr_cur_freq.attr,
 986         &dev_attr_available_frequencies.attr,
 987         &dev_attr_target_freq.attr,
 988         &dev_attr_polling_interval.attr,
 989         &dev_attr_min_freq.attr,
 990         &dev_attr_max_freq.attr,
 991         &dev_attr_trans_stat.attr,
 992         NULL,
 993 };
 994 ATTRIBUTE_GROUPS(devfreq);
 995
 996 static int __init devfreq_init(void)
 997 {
 998         devfreq_class = class_create(THIS_MODULE, "devfreq");
 999         if (IS_ERR(devfreq_class)) {
1000                 pr_err("%s: couldn't create class\n", __FILE__);
1001                 return PTR_ERR(devfreq_class);
1002         }
1003
1004         devfreq_wq = create_freezable_workqueue("devfreq_wq");
1005         if (!devfreq_wq) {
1006                 class_destroy(devfreq_class);
1007                 pr_err("%s: couldn't create workqueue\n", __FILE__);
1008                 return -ENOMEM;
1009         }
1010         devfreq_class->dev_groups = devfreq_groups;
1011
1012         return 0;
1013 }
1014 subsys_initcall(devfreq_init);
1015
1016 static void __exit devfreq_exit(void)
1017 {
1018         class_destroy(devfreq_class);
1019         destroy_workqueue(devfreq_wq);
1020 }
1021 module_exit(devfreq_exit);
1022
1023 /*
1024  * The followings are helper functions for devfreq user device drivers with
1025  * OPP framework.
1026  */
1027
1028 /**
1029  * devfreq_recommended_opp() - Helper function to get proper OPP for the
1030  *                           freq value given to target callback.
1031  * @dev:        The devfreq user device. (parent of devfreq)
1032  * @freq:       The frequency given to target function
1033  * @flags:      Flags handed from devfreq framework.
1034  *
1035  * Locking: This function must be called under rcu_read_lock(). opp is a rcu
1036  * protected pointer. The reason for the same is that the opp pointer which is
1037  * returned will remain valid for use with opp_get_{voltage, freq} only while
1038  * under the locked area. The pointer returned must be used prior to unlocking
1039  * with rcu_read_unlock() to maintain the integrity of the pointer.
1040  */
1041 struct dev_pm_opp *devfreq_recommended_opp(struct device *dev,
1042                                            unsigned long *freq,
1043                                            u32 flags)
1044 {
1045         struct dev_pm_opp *opp;
1046
1047         if (flags & DEVFREQ_FLAG_LEAST_UPPER_BOUND) {
1048                 /* The freq is an upper bound. opp should be lower */
1049                 opp = dev_pm_opp_find_freq_floor(dev, freq);
1050
1051                 /* If not available, use the closest opp */
1052                 if (opp == ERR_PTR(-ERANGE))
1053                         opp = dev_pm_opp_find_freq_ceil(dev, freq);
1054         } else {
1055                 /* The freq is an lower bound. opp should be higher */
1056                 opp = dev_pm_opp_find_freq_ceil(dev, freq);
1057
1058                 /* If not available, use the closest opp */
1059                 if (opp == ERR_PTR(-ERANGE))
1060                         opp = dev_pm_opp_find_freq_floor(dev, freq);
1061         }
1062
1063         return opp;
1064 }
1065
1066 /**
1067  * devfreq_register_opp_notifier() - Helper function to get devfreq notified
1068  *                                 for any changes in the OPP availability
1069  *                                 changes
1070  * @dev:        The devfreq user device. (parent of devfreq)
1071  * @devfreq:    The devfreq object.
1072  */
1073 int devfreq_register_opp_notifier(struct device *dev, struct devfreq *devfreq)
1074 {
1075         struct srcu_notifier_head *nh;
1076         int ret = 0;
1077
1078         rcu_read_lock();
1079         nh = dev_pm_opp_get_notifier(dev);
1080         if (IS_ERR(nh))
1081                 ret = PTR_ERR(nh);
1082         rcu_read_unlock();
1083         if (!ret)
1084                 ret = srcu_notifier_chain_register(nh, &devfreq->nb);
1085
1086         return ret;
1087 }
1088
1089 /**
1090  * devfreq_unregister_opp_notifier() - Helper function to stop getting devfreq
1091  *                                   notified for any changes in the OPP
1092  *                                   availability changes anymore.
1093  * @dev:        The devfreq user device. (parent of devfreq)
1094  * @devfreq:    The devfreq object.
1095  *
1096  * At exit() callback of devfreq_dev_profile, this must be included if
1097  * devfreq_recommended_opp is used.
1098  */
1099 int devfreq_unregister_opp_notifier(struct device *dev, struct devfreq *devfreq)
1100 {
1101         struct srcu_notifier_head *nh;
1102         int ret = 0;
1103
1104         rcu_read_lock();
1105         nh = dev_pm_opp_get_notifier(dev);
1106         if (IS_ERR(nh))
1107                 ret = PTR_ERR(nh);
1108         rcu_read_unlock();
1109         if (!ret)
1110                 ret = srcu_notifier_chain_unregister(nh, &devfreq->nb);
1111
1112         return ret;
1113 }
1114
1115 MODULE_AUTHOR("MyungJoo Ham <myungjoo.ham@samsung.com>");
1116 MODULE_DESCRIPTION("devfreq class support");
1117 MODULE_LICENSE("GPL");