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;
  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_update_status(devfreq, devfreq->previous_freq);
 275         devfreq->stop_polling = true;
 276         mutex_unlock(&devfreq->lock);
 277         cancel_delayed_work_sync(&devfreq->work);
 278 }
 279 EXPORT_SYMBOL(devfreq_monitor_suspend);
 280
 281 /**
 282  * devfreq_monitor_resume() - Resume load monitoring of a devfreq instance
 283  * @devfreq:    the devfreq instance.
 284  *
 285  * Helper function to resume devfreq device load monitoing. Function
 286  * to be called from governor in response to DEVFREQ_GOV_RESUME
 287  * event or when polling interval is set to non-zero.
 288  */
 289 void devfreq_monitor_resume(struct devfreq *devfreq)
 290 {
 291         unsigned long freq;
 292
 293         mutex_lock(&devfreq->lock);
 294         if (!devfreq->stop_polling)
 295                 goto out;
 296
 297         if (!delayed_work_pending(&devfreq->work) &&
 298                         devfreq->profile->polling_ms)
 299                 queue_delayed_work(devfreq_wq, &devfreq->work,
 300                         msecs_to_jiffies(devfreq->profile->polling_ms));
 301
 302         devfreq->last_stat_updated = jiffies;
 303         devfreq->stop_polling = false;
 304
 305         if (devfreq->profile->get_cur_freq &&
 306                 !devfreq->profile->get_cur_freq(devfreq->dev.parent, &freq))
 307                 devfreq->previous_freq = freq;
 308
 309 out:
 310         mutex_unlock(&devfreq->lock);
 311 }
 312 EXPORT_SYMBOL(devfreq_monitor_resume);
 313
 314 /**
 315  * devfreq_interval_update() - Update device devfreq monitoring interval
 316  * @devfreq:    the devfreq instance.
 317  * @delay:      new polling interval to be set.
 318  *
 319  * Helper function to set new load monitoring polling interval. Function
 320  * to be called from governor in response to DEVFREQ_GOV_INTERVAL event.
 321  */
 322 void devfreq_interval_update(struct devfreq *devfreq, unsigned int *delay)
 323 {
 324         unsigned int cur_delay = devfreq->profile->polling_ms;
 325         unsigned int new_delay = *delay;
 326
 327         mutex_lock(&devfreq->lock);
 328         devfreq->profile->polling_ms = new_delay;
 329
 330         if (devfreq->stop_polling)
 331                 goto out;
 332
 333         /* if new delay is zero, stop polling */
 334         if (!new_delay) {
 335                 mutex_unlock(&devfreq->lock);
 336                 cancel_delayed_work_sync(&devfreq->work);
 337                 return;
 338         }
 339
 340         /* if current delay is zero, start polling with new delay */
 341         if (!cur_delay) {
 342                 queue_delayed_work(devfreq_wq, &devfreq->work,
 343                         msecs_to_jiffies(devfreq->profile->polling_ms));
 344                 goto out;
 345         }
 346
 347         /* if current delay is greater than new delay, restart polling */
 348         if (cur_delay > new_delay) {
 349                 mutex_unlock(&devfreq->lock);
 350                 cancel_delayed_work_sync(&devfreq->work);
 351                 mutex_lock(&devfreq->lock);
 352                 if (!devfreq->stop_polling)
 353                         queue_delayed_work(devfreq_wq, &devfreq->work,
 354                               msecs_to_jiffies(devfreq->profile->polling_ms));
 355         }
 356 out:
 357         mutex_unlock(&devfreq->lock);
 358 }
 359 EXPORT_SYMBOL(devfreq_interval_update);
 360
 361 /**
 362  * devfreq_notifier_call() - Notify that the device frequency requirements
 363  *                         has been changed out of devfreq framework.
 364  * @nb:         the notifier_block (supposed to be devfreq->nb)
 365  * @type:       not used
 366  * @devp:       not used
 367  *
 368  * Called by a notifier that uses devfreq->nb.
 369  */
 370 static int devfreq_notifier_call(struct notifier_block *nb, unsigned long type,
 371                                  void *devp)
 372 {
 373         struct devfreq *devfreq = container_of(nb, struct devfreq, nb);
 374         int ret;
 375
 376         mutex_lock(&devfreq->lock);
 377         ret = update_devfreq(devfreq);
 378         mutex_unlock(&devfreq->lock);
 379
 380         return ret;
 381 }
 382
 383 /**
 384  * _remove_devfreq() - Remove devfreq from the list and release its resources.
 385  * @devfreq:    the devfreq struct
 386  * @skip:       skip calling device_unregister().
 387  */
 388 static void _remove_devfreq(struct devfreq *devfreq, bool skip)
 389 {
 390         mutex_lock(&devfreq_list_lock);
 391         if (IS_ERR(find_device_devfreq(devfreq->dev.parent))) {
 392                 mutex_unlock(&devfreq_list_lock);
 393                 dev_warn(&devfreq->dev, "releasing devfreq which doesn't exist\n");
 394                 return;
 395         }
 396         list_del(&devfreq->node);
 397         mutex_unlock(&devfreq_list_lock);
 398
 399         if (devfreq->governor)
 400                 devfreq->governor->event_handler(devfreq,
 401                                                  DEVFREQ_GOV_STOP, NULL);
 402
 403         if (devfreq->profile->exit)
 404                 devfreq->profile->exit(devfreq->dev.parent);
 405
 406         if (!skip && get_device(&devfreq->dev)) {
 407                 device_unregister(&devfreq->dev);
 408                 put_device(&devfreq->dev);
 409         }
 410
 411         mutex_destroy(&devfreq->lock);
 412         kfree(devfreq);
 413 }
 414
 415 /**
 416  * devfreq_dev_release() - Callback for struct device to release the device.
 417  * @dev:        the devfreq device
 418  *
 419  * This calls _remove_devfreq() if _remove_devfreq() is not called.
 420  * Note that devfreq_dev_release() could be called by _remove_devfreq() as
 421  * well as by others unregistering the device.
 422  */
 423 static void devfreq_dev_release(struct device *dev)
 424 {
 425         struct devfreq *devfreq = to_devfreq(dev);
 426
 427         _remove_devfreq(devfreq, true);
 428 }
 429
 430 /**
 431  * devfreq_add_device() - Add devfreq feature to the device
 432  * @dev:        the device to add devfreq feature.
 433  * @profile:    device-specific profile to run devfreq.
 434  * @governor_name:      name of the policy to choose frequency.
 435  * @data:       private data for the governor. The devfreq framework does not
 436  *              touch this value.
 437  */
 438 struct devfreq *devfreq_add_device(struct device *dev,
 439                                    struct devfreq_dev_profile *profile,
 440                                    const char *governor_name,
 441                                    void *data)
 442 {
 443         struct devfreq *devfreq;
 444         struct devfreq_governor *governor;
 445         int err = 0;
 446
 447         if (!dev || !profile || !governor_name) {
 448                 dev_err(dev, "%s: Invalid parameters.\n", __func__);
 449                 return ERR_PTR(-EINVAL);
 450         }
 451
 452         mutex_lock(&devfreq_list_lock);
 453         devfreq = find_device_devfreq(dev);
 454         mutex_unlock(&devfreq_list_lock);
 455         if (!IS_ERR(devfreq)) {
 456                 dev_err(dev, "%s: Unable to create devfreq for the device. It already has one.\n", __func__);
 457                 err = -EINVAL;
 458                 goto err_out;
 459         }
 460
 461         devfreq = kzalloc(sizeof(struct devfreq), GFP_KERNEL);
 462         if (!devfreq) {
 463                 dev_err(dev, "%s: Unable to create devfreq for the device\n",
 464                         __func__);
 465                 err = -ENOMEM;
 466                 goto err_out;
 467         }
 468
 469         mutex_init(&devfreq->lock);
 470         mutex_lock(&devfreq->lock);
 471         devfreq->dev.parent = dev;
 472         devfreq->dev.class = devfreq_class;
 473         devfreq->dev.release = devfreq_dev_release;
 474         devfreq->profile = profile;
 475         strncpy(devfreq->governor_name, governor_name, DEVFREQ_NAME_LEN);
 476         devfreq->previous_freq = profile->initial_freq;
 477         devfreq->data = data;
 478         devfreq->nb.notifier_call = devfreq_notifier_call;
 479
 480         devfreq->trans_table =  devm_kzalloc(dev, sizeof(unsigned int) *
 481                                                 devfreq->profile->max_state *
 482                                                 devfreq->profile->max_state,
 483                                                 GFP_KERNEL);
 484         devfreq->time_in_state = devm_kzalloc(dev, sizeof(unsigned int) *
 485                                                 devfreq->profile->max_state,
 486                                                 GFP_KERNEL);
 487         devfreq->last_stat_updated = jiffies;
 488
 489         dev_set_name(&devfreq->dev, "%s", dev_name(dev));
 490         err = device_register(&devfreq->dev);
 491         if (err) {
 492                 put_device(&devfreq->dev);
 493                 mutex_unlock(&devfreq->lock);
 494                 goto err_dev;
 495         }
 496
 497         mutex_unlock(&devfreq->lock);
 498
 499         mutex_lock(&devfreq_list_lock);
 500         list_add(&devfreq->node, &devfreq_list);
 501
 502         governor = find_devfreq_governor(devfreq->governor_name);
 503         if (!IS_ERR(governor))
 504                 devfreq->governor = governor;
 505         if (devfreq->governor)
 506                 err = devfreq->governor->event_handler(devfreq,
 507                                         DEVFREQ_GOV_START, NULL);
 508         mutex_unlock(&devfreq_list_lock);
 509         if (err) {
 510                 dev_err(dev, "%s: Unable to start governor for the device\n",
 511                         __func__);
 512                 goto err_init;
 513         }
 514
 515         return devfreq;
 516
 517 err_init:
 518         list_del(&devfreq->node);
 519         device_unregister(&devfreq->dev);
 520 err_dev:
 521         kfree(devfreq);
 522 err_out:
 523         return ERR_PTR(err);
 524 }
 525 EXPORT_SYMBOL(devfreq_add_device);
 526
 527 /**
 528  * devfreq_remove_device() - Remove devfreq feature from a device.
 529  * @devfreq:    the devfreq instance to be removed
 530  *
 531  * The opposite of devfreq_add_device().
 532  */
 533 int devfreq_remove_device(struct devfreq *devfreq)
 534 {
 535         if (!devfreq)
 536                 return -EINVAL;
 537
 538         _remove_devfreq(devfreq, false);
 539
 540         return 0;
 541 }
 542 EXPORT_SYMBOL(devfreq_remove_device);
 543
 544 /**
 545  * devfreq_suspend_device() - Suspend devfreq of a device.
 546  * @devfreq: the devfreq instance to be suspended
 547  *
 548  * This function is intended to be called by the pm callbacks
 549  * (e.g., runtime_suspend, suspend) of the device driver that
 550  * holds the devfreq.
 551  */
 552 int devfreq_suspend_device(struct devfreq *devfreq)
 553 {
 554         if (!devfreq)
 555                 return -EINVAL;
 556
 557         if (!devfreq->governor)
 558                 return 0;
 559
 560         return devfreq->governor->event_handler(devfreq,
 561                                 DEVFREQ_GOV_SUSPEND, NULL);
 562 }
 563 EXPORT_SYMBOL(devfreq_suspend_device);
 564
 565 /**
 566  * devfreq_resume_device() - Resume devfreq of a device.
 567  * @devfreq: the devfreq instance to be resumed
 568  *
 569  * This function is intended to be called by the pm callbacks
 570  * (e.g., runtime_resume, resume) of the device driver that
 571  * holds the devfreq.
 572  */
 573 int devfreq_resume_device(struct devfreq *devfreq)
 574 {
 575         if (!devfreq)
 576                 return -EINVAL;
 577
 578         if (!devfreq->governor)
 579                 return 0;
 580
 581         return devfreq->governor->event_handler(devfreq,
 582                                 DEVFREQ_GOV_RESUME, NULL);
 583 }
 584 EXPORT_SYMBOL(devfreq_resume_device);
 585
 586 /**
 587  * devfreq_add_governor() - Add devfreq governor
 588  * @governor:   the devfreq governor to be added
 589  */
 590 int devfreq_add_governor(struct devfreq_governor *governor)
 591 {
 592         struct devfreq_governor *g;
 593         struct devfreq *devfreq;
 594         int err = 0;
 595
 596         if (!governor) {
 597                 pr_err("%s: Invalid parameters.\n", __func__);
 598                 return -EINVAL;
 599         }
 600
 601         mutex_lock(&devfreq_list_lock);
 602         g = find_devfreq_governor(governor->name);
 603         if (!IS_ERR(g)) {
 604                 pr_err("%s: governor %s already registered\n", __func__,
 605                        g->name);
 606                 err = -EINVAL;
 607                 goto err_out;
 608         }
 609
 610         list_add(&governor->node, &devfreq_governor_list);
 611
 612         list_for_each_entry(devfreq, &devfreq_list, node) {
 613                 int ret = 0;
 614                 struct device *dev = devfreq->dev.parent;
 615
 616                 if (!strncmp(devfreq->governor_name, governor->name,
 617                              DEVFREQ_NAME_LEN)) {
 618                         /* The following should never occur */
 619                         if (devfreq->governor) {
 620                                 dev_warn(dev,
 621                                          "%s: Governor %s already present\n",
 622                                          __func__, devfreq->governor->name);
 623                                 ret = devfreq->governor->event_handler(devfreq,
 624                                                         DEVFREQ_GOV_STOP, NULL);
 625                                 if (ret) {
 626                                         dev_warn(dev,
 627                                                  "%s: Governor %s stop = %d\n",
 628                                                  __func__,
 629                                                  devfreq->governor->name, ret);
 630                                 }
 631                                 /* Fall through */
 632                         }
 633                         devfreq->governor = governor;
 634                         ret = devfreq->governor->event_handler(devfreq,
 635                                                 DEVFREQ_GOV_START, NULL);
 636                         if (ret) {
 637                                 dev_warn(dev, "%s: Governor %s start=%d\n",
 638                                          __func__, devfreq->governor->name,
 639                                          ret);
 640                         }
 641                 }
 642         }
 643
 644 err_out:
 645         mutex_unlock(&devfreq_list_lock);
 646
 647         return err;
 648 }
 649 EXPORT_SYMBOL(devfreq_add_governor);
 650
 651 /**
 652  * devfreq_remove_device() - Remove devfreq feature from a device.
 653  * @governor:   the devfreq governor to be removed
 654  */
 655 int devfreq_remove_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 not registered\n", __func__,
 670                        governor->name);
 671                 err = PTR_ERR(g);
 672                 goto err_out;
 673         }
 674         list_for_each_entry(devfreq, &devfreq_list, node) {
 675                 int ret;
 676                 struct device *dev = devfreq->dev.parent;
 677
 678                 if (!strncmp(devfreq->governor_name, governor->name,
 679                              DEVFREQ_NAME_LEN)) {
 680                         /* we should have a devfreq governor! */
 681                         if (!devfreq->governor) {
 682                                 dev_warn(dev, "%s: Governor %s NOT present\n",
 683                                          __func__, governor->name);
 684                                 continue;
 685                                 /* Fall through */
 686                         }
 687                         ret = devfreq->governor->event_handler(devfreq,
 688                                                 DEVFREQ_GOV_STOP, NULL);
 689                         if (ret) {
 690                                 dev_warn(dev, "%s: Governor %s stop=%d\n",
 691                                          __func__, devfreq->governor->name,
 692                                          ret);
 693                         }
 694                         devfreq->governor = NULL;
 695                 }
 696         }
 697
 698         list_del(&governor->node);
 699 err_out:
 700         mutex_unlock(&devfreq_list_lock);
 701
 702         return err;
 703 }
 704 EXPORT_SYMBOL(devfreq_remove_governor);
 705
 706 static ssize_t governor_show(struct device *dev,
 707                              struct device_attribute *attr, char *buf)
 708 {
 709         if (!to_devfreq(dev)->governor)
 710                 return -EINVAL;
 711
 712         return sprintf(buf, "%s\n", to_devfreq(dev)->governor->name);
 713 }
 714
 715 static ssize_t governor_store(struct device *dev, struct device_attribute *attr,
 716                               const char *buf, size_t count)
 717 {
 718         struct devfreq *df = to_devfreq(dev);
 719         int ret;
 720         char str_governor[DEVFREQ_NAME_LEN + 1];
 721         struct devfreq_governor *governor;
 722
 723         ret = sscanf(buf, "%" __stringify(DEVFREQ_NAME_LEN) "s", str_governor);
 724         if (ret != 1)
 725                 return -EINVAL;
 726
 727         mutex_lock(&devfreq_list_lock);
 728         governor = find_devfreq_governor(str_governor);
 729         if (IS_ERR(governor)) {
 730                 ret = PTR_ERR(governor);
 731                 goto out;
 732         }
 733         if (df->governor == governor)
 734                 goto out;
 735
 736         if (df->governor) {
 737                 ret = df->governor->event_handler(df, DEVFREQ_GOV_STOP, NULL);
 738                 if (ret) {
 739                         dev_warn(dev, "%s: Governor %s not stopped(%d)\n",
 740                                  __func__, df->governor->name, ret);
 741                         goto out;
 742                 }
 743         }
 744         df->governor = governor;
 745         strncpy(df->governor_name, governor->name, DEVFREQ_NAME_LEN);
 746         ret = df->governor->event_handler(df, DEVFREQ_GOV_START, NULL);
 747         if (ret)
 748                 dev_warn(dev, "%s: Governor %s not started(%d)\n",
 749                          __func__, df->governor->name, ret);
 750 out:
 751         mutex_unlock(&devfreq_list_lock);
 752
 753         if (!ret)
 754                 ret = count;
 755         return ret;
 756 }
 757 static DEVICE_ATTR_RW(governor);
 758
 759 static ssize_t available_governors_show(struct device *d,
 760                                         struct device_attribute *attr,
 761                                         char *buf)
 762 {
 763         struct devfreq_governor *tmp_governor;
 764         ssize_t count = 0;
 765
 766         mutex_lock(&devfreq_list_lock);
 767         list_for_each_entry(tmp_governor, &devfreq_governor_list, node)
 768                 count += scnprintf(&buf[count], (PAGE_SIZE - count - 2),
 769                                    "%s ", tmp_governor->name);
 770         mutex_unlock(&devfreq_list_lock);
 771
 772         /* Truncate the trailing space */
 773         if (count)
 774                 count--;
 775
 776         count += sprintf(&buf[count], "\n");
 777
 778         return count;
 779 }
 780 static DEVICE_ATTR_RO(available_governors);
 781
 782 static ssize_t cur_freq_show(struct device *dev, struct device_attribute *attr,
 783                              char *buf)
 784 {
 785         unsigned long freq;
 786         struct devfreq *devfreq = to_devfreq(dev);
 787
 788         if (devfreq->profile->get_cur_freq &&
 789                 !devfreq->profile->get_cur_freq(devfreq->dev.parent, &freq))
 790                         return sprintf(buf, "%lu\n", freq);
 791
 792         return sprintf(buf, "%lu\n", devfreq->previous_freq);
 793 }
 794 static DEVICE_ATTR_RO(cur_freq);
 795
 796 static ssize_t target_freq_show(struct device *dev,
 797                                 struct device_attribute *attr, char *buf)
 798 {
 799         return sprintf(buf, "%lu\n", to_devfreq(dev)->previous_freq);
 800 }
 801 static DEVICE_ATTR_RO(target_freq);
 802
 803 static ssize_t polling_interval_show(struct device *dev,
 804                                      struct device_attribute *attr, char *buf)
 805 {
 806         return sprintf(buf, "%d\n", to_devfreq(dev)->profile->polling_ms);
 807 }
 808
 809 static ssize_t polling_interval_store(struct device *dev,
 810                                       struct device_attribute *attr,
 811                                       const char *buf, size_t count)
 812 {
 813         struct devfreq *df = to_devfreq(dev);
 814         unsigned int value;
 815         int ret;
 816
 817         if (!df->governor)
 818                 return -EINVAL;
 819
 820         ret = sscanf(buf, "%u", &value);
 821         if (ret != 1)
 822                 return -EINVAL;
 823
 824         df->governor->event_handler(df, DEVFREQ_GOV_INTERVAL, &value);
 825         ret = count;
 826
 827         return ret;
 828 }
 829 static DEVICE_ATTR_RW(polling_interval);
 830
 831 static ssize_t min_freq_store(struct device *dev, struct device_attribute *attr,
 832                               const char *buf, size_t count)
 833 {
 834         struct devfreq *df = to_devfreq(dev);
 835         unsigned long value;
 836         int ret;
 837         unsigned long max;
 838
 839         ret = sscanf(buf, "%lu", &value);
 840         if (ret != 1)
 841                 return -EINVAL;
 842
 843         mutex_lock(&df->lock);
 844         max = df->max_freq;
 845         if (value && max && value > max) {
 846                 ret = -EINVAL;
 847                 goto unlock;
 848         }
 849
 850         df->min_freq = value;
 851         update_devfreq(df);
 852         ret = count;
 853 unlock:
 854         mutex_unlock(&df->lock);
 855         return ret;
 856 }
 857
 858 static ssize_t min_freq_show(struct device *dev, struct device_attribute *attr,
 859                              char *buf)
 860 {
 861         return sprintf(buf, "%lu\n", to_devfreq(dev)->min_freq);
 862 }
 863
 864 static ssize_t max_freq_store(struct device *dev, struct device_attribute *attr,
 865                               const char *buf, size_t count)
 866 {
 867         struct devfreq *df = to_devfreq(dev);
 868         unsigned long value;
 869         int ret;
 870         unsigned long min;
 871
 872         ret = sscanf(buf, "%lu", &value);
 873         if (ret != 1)
 874                 return -EINVAL;
 875
 876         mutex_lock(&df->lock);
 877         min = df->min_freq;
 878         if (value && min && value < min) {
 879                 ret = -EINVAL;
 880                 goto unlock;
 881         }
 882
 883         df->max_freq = value;
 884         update_devfreq(df);
 885         ret = count;
 886 unlock:
 887         mutex_unlock(&df->lock);
 888         return ret;
 889 }
 890 static DEVICE_ATTR_RW(min_freq);
 891
 892 static ssize_t max_freq_show(struct device *dev, struct device_attribute *attr,
 893                              char *buf)
 894 {
 895         return sprintf(buf, "%lu\n", to_devfreq(dev)->max_freq);
 896 }
 897 static DEVICE_ATTR_RW(max_freq);
 898
 899 static ssize_t available_frequencies_show(struct device *d,
 900                                           struct device_attribute *attr,
 901                                           char *buf)
 902 {
 903         struct devfreq *df = to_devfreq(d);
 904         struct device *dev = df->dev.parent;
 905         struct dev_pm_opp *opp;
 906         ssize_t count = 0;
 907         unsigned long freq = 0;
 908
 909         rcu_read_lock();
 910         do {
 911                 opp = dev_pm_opp_find_freq_ceil(dev, &freq);
 912                 if (IS_ERR(opp))
 913                         break;
 914
 915                 count += scnprintf(&buf[count], (PAGE_SIZE - count - 2),
 916                                    "%lu ", freq);
 917                 freq++;
 918         } while (1);
 919         rcu_read_unlock();
 920
 921         /* Truncate the trailing space */
 922         if (count)
 923                 count--;
 924
 925         count += sprintf(&buf[count], "\n");
 926
 927         return count;
 928 }
 929 static DEVICE_ATTR_RO(available_frequencies);
 930
 931 static ssize_t trans_stat_show(struct device *dev,
 932                                struct device_attribute *attr, char *buf)
 933 {
 934         struct devfreq *devfreq = to_devfreq(dev);
 935         ssize_t len;
 936         int i, j;
 937         unsigned int max_state = devfreq->profile->max_state;
 938
 939         if (!devfreq->stop_polling &&
 940                         devfreq_update_status(devfreq, devfreq->previous_freq))
 941                 return 0;
 942
 943         len = sprintf(buf, "   From  :   To\n");
 944         len += sprintf(buf + len, "         :");
 945         for (i = 0; i < max_state; i++)
 946                 len += sprintf(buf + len, "%8u",
 947                                 devfreq->profile->freq_table[i]);
 948
 949         len += sprintf(buf + len, "   time(ms)\n");
 950
 951         for (i = 0; i < max_state; i++) {
 952                 if (devfreq->profile->freq_table[i]
 953                                         == devfreq->previous_freq) {
 954                         len += sprintf(buf + len, "*");
 955                 } else {
 956                         len += sprintf(buf + len, " ");
 957                 }
 958                 len += sprintf(buf + len, "%8u:",
 959                                 devfreq->profile->freq_table[i]);
 960                 for (j = 0; j < max_state; j++)
 961                         len += sprintf(buf + len, "%8u",
 962                                 devfreq->trans_table[(i * max_state) + j]);
 963                 len += sprintf(buf + len, "%10u\n",
 964                         jiffies_to_msecs(devfreq->time_in_state[i]));
 965         }
 966
 967         len += sprintf(buf + len, "Total transition : %u\n",
 968                                         devfreq->total_trans);
 969         return len;
 970 }
 971 static DEVICE_ATTR_RO(trans_stat);
 972
 973 static struct attribute *devfreq_attrs[] = {
 974         &dev_attr_governor.attr,
 975         &dev_attr_available_governors.attr,
 976         &dev_attr_cur_freq.attr,
 977         &dev_attr_available_frequencies.attr,
 978         &dev_attr_target_freq.attr,
 979         &dev_attr_polling_interval.attr,
 980         &dev_attr_min_freq.attr,
 981         &dev_attr_max_freq.attr,
 982         &dev_attr_trans_stat.attr,
 983         NULL,
 984 };
 985 ATTRIBUTE_GROUPS(devfreq);
 986
 987 static int __init devfreq_init(void)
 988 {
 989         devfreq_class = class_create(THIS_MODULE, "devfreq");
 990         if (IS_ERR(devfreq_class)) {
 991                 pr_err("%s: couldn't create class\n", __FILE__);
 992                 return PTR_ERR(devfreq_class);
 993         }
 994
 995         devfreq_wq = create_freezable_workqueue("devfreq_wq");
 996         if (!devfreq_wq) {
 997                 class_destroy(devfreq_class);
 998                 pr_err("%s: couldn't create workqueue\n", __FILE__);
 999                 return -ENOMEM;
1000         }
1001         devfreq_class->dev_groups = devfreq_groups;
1002
1003         return 0;
1004 }
1005 subsys_initcall(devfreq_init);
1006
1007 static void __exit devfreq_exit(void)
1008 {
1009         class_destroy(devfreq_class);
1010         destroy_workqueue(devfreq_wq);
1011 }
1012 module_exit(devfreq_exit);
1013
1014 /*
1015  * The followings are helper functions for devfreq user device drivers with
1016  * OPP framework.
1017  */
1018
1019 /**
1020  * devfreq_recommended_opp() - Helper function to get proper OPP for the
1021  *                           freq value given to target callback.
1022  * @dev:        The devfreq user device. (parent of devfreq)
1023  * @freq:       The frequency given to target function
1024  * @flags:      Flags handed from devfreq framework.
1025  *
1026  * Locking: This function must be called under rcu_read_lock(). opp is a rcu
1027  * protected pointer. The reason for the same is that the opp pointer which is
1028  * returned will remain valid for use with opp_get_{voltage, freq} only while
1029  * under the locked area. The pointer returned must be used prior to unlocking
1030  * with rcu_read_unlock() to maintain the integrity of the pointer.
1031  */
1032 struct dev_pm_opp *devfreq_recommended_opp(struct device *dev,
1033                                            unsigned long *freq,
1034                                            u32 flags)
1035 {
1036         struct dev_pm_opp *opp;
1037
1038         if (flags & DEVFREQ_FLAG_LEAST_UPPER_BOUND) {
1039                 /* The freq is an upper bound. opp should be lower */
1040                 opp = dev_pm_opp_find_freq_floor(dev, freq);
1041
1042                 /* If not available, use the closest opp */
1043                 if (opp == ERR_PTR(-ERANGE))
1044                         opp = dev_pm_opp_find_freq_ceil(dev, freq);
1045         } else {
1046                 /* The freq is an lower bound. opp should be higher */
1047                 opp = dev_pm_opp_find_freq_ceil(dev, freq);
1048
1049                 /* If not available, use the closest opp */
1050                 if (opp == ERR_PTR(-ERANGE))
1051                         opp = dev_pm_opp_find_freq_floor(dev, freq);
1052         }
1053
1054         return opp;
1055 }
1056
1057 /**
1058  * devfreq_register_opp_notifier() - Helper function to get devfreq notified
1059  *                                 for any changes in the OPP availability
1060  *                                 changes
1061  * @dev:        The devfreq user device. (parent of devfreq)
1062  * @devfreq:    The devfreq object.
1063  */
1064 int devfreq_register_opp_notifier(struct device *dev, struct devfreq *devfreq)
1065 {
1066         struct srcu_notifier_head *nh;
1067         int ret = 0;
1068
1069         rcu_read_lock();
1070         nh = dev_pm_opp_get_notifier(dev);
1071         if (IS_ERR(nh))
1072                 ret = PTR_ERR(nh);
1073         rcu_read_unlock();
1074         if (!ret)
1075                 ret = srcu_notifier_chain_register(nh, &devfreq->nb);
1076
1077         return ret;
1078 }
1079
1080 /**
1081  * devfreq_unregister_opp_notifier() - Helper function to stop getting devfreq
1082  *                                   notified for any changes in the OPP
1083  *                                   availability changes anymore.
1084  * @dev:        The devfreq user device. (parent of devfreq)
1085  * @devfreq:    The devfreq object.
1086  *
1087  * At exit() callback of devfreq_dev_profile, this must be included if
1088  * devfreq_recommended_opp is used.
1089  */
1090 int devfreq_unregister_opp_notifier(struct device *dev, struct devfreq *devfreq)
1091 {
1092         struct srcu_notifier_head *nh;
1093         int ret = 0;
1094
1095         rcu_read_lock();
1096         nh = dev_pm_opp_get_notifier(dev);
1097         if (IS_ERR(nh))
1098                 ret = PTR_ERR(nh);
1099         rcu_read_unlock();
1100         if (!ret)
1101                 ret = srcu_notifier_chain_unregister(nh, &devfreq->nb);
1102
1103         return ret;
1104 }
1105
1106 MODULE_AUTHOR("MyungJoo Ham <myungjoo.ham@samsung.com>");
1107 MODULE_DESCRIPTION("devfreq class support");
1108 MODULE_LICENSE("GPL");