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 <linux/of.h>
  29 #include "governor.h"
  30
  31 static struct class *devfreq_class;
  32
  33 /*
  34  * devfreq core provides delayed work based load monitoring helper
  35  * functions. Governors can use these or can implement their own
  36  * monitoring mechanism.
  37  */
  38 static struct workqueue_struct *devfreq_wq;
  39
  40 /* The list of all device-devfreq governors */
  41 static LIST_HEAD(devfreq_governor_list);
  42 /* The list of all device-devfreq */
  43 static LIST_HEAD(devfreq_list);
  44 static DEFINE_MUTEX(devfreq_list_lock);
  45
  46 /**
  47  * find_device_devfreq() - find devfreq struct using device pointer
  48  * @dev:        device pointer used to lookup device devfreq.
  49  *
  50  * Search the list of device devfreqs and return the matched device's
  51  * devfreq info. devfreq_list_lock should be held by the caller.
  52  */
  53 static struct devfreq *find_device_devfreq(struct device *dev)
  54 {
  55         struct devfreq *tmp_devfreq;
  56
  57         if (IS_ERR_OR_NULL(dev)) {
  58                 pr_err("DEVFREQ: %s: Invalid parameters\n", __func__);
  59                 return ERR_PTR(-EINVAL);
  60         }
  61         WARN(!mutex_is_locked(&devfreq_list_lock),
  62              "devfreq_list_lock must be locked.");
  63
  64         list_for_each_entry(tmp_devfreq, &devfreq_list, node) {
  65                 if (tmp_devfreq->dev.parent == dev)
  66                         return tmp_devfreq;
  67         }
  68
  69         return ERR_PTR(-ENODEV);
  70 }
  71
  72 /**
  73  * devfreq_get_freq_level() - Lookup freq_table for the frequency
  74  * @devfreq:    the devfreq instance
  75  * @freq:       the target frequency
  76  */
  77 static int devfreq_get_freq_level(struct devfreq *devfreq, unsigned long freq)
  78 {
  79         int lev;
  80
  81         for (lev = 0; lev < devfreq->profile->max_state; lev++)
  82                 if (freq == devfreq->profile->freq_table[lev])
  83                         return lev;
  84
  85         return -EINVAL;
  86 }
  87
  88 /**
  89  * devfreq_set_freq_table() - Initialize freq_table for the frequency
  90  * @devfreq:    the devfreq instance
  91  */
  92 static void devfreq_set_freq_table(struct devfreq *devfreq)
  93 {
  94         struct devfreq_dev_profile *profile = devfreq->profile;
  95         struct dev_pm_opp *opp;
  96         unsigned long freq;
  97         int i, count;
  98
  99         /* Initialize the freq_table from OPP table */
 100         count = dev_pm_opp_get_opp_count(devfreq->dev.parent);
 101         if (count <= 0)
 102                 return;
 103
 104         profile->max_state = count;
 105         profile->freq_table = devm_kcalloc(devfreq->dev.parent,
 106                                         profile->max_state,
 107                                         sizeof(*profile->freq_table),
 108                                         GFP_KERNEL);
 109         if (!profile->freq_table) {
 110                 profile->max_state = 0;
 111                 return;
 112         }
 113
 114         rcu_read_lock();
 115         for (i = 0, freq = 0; i < profile->max_state; i++, freq++) {
 116                 opp = dev_pm_opp_find_freq_ceil(devfreq->dev.parent, &freq);
 117                 if (IS_ERR(opp)) {
 118                         devm_kfree(devfreq->dev.parent, profile->freq_table);
 119                         profile->max_state = 0;
 120                         rcu_read_unlock();
 121                         return;
 122                 }
 123                 profile->freq_table[i] = freq;
 124         }
 125         rcu_read_unlock();
 126 }
 127
 128 /**
 129  * devfreq_update_status() - Update statistics of devfreq behavior
 130  * @devfreq:    the devfreq instance
 131  * @freq:       the update target frequency
 132  */
 133 static int devfreq_update_status(struct devfreq *devfreq, unsigned long freq)
 134 {
 135         int lev, prev_lev, ret = 0;
 136         unsigned long cur_time;
 137
 138         cur_time = jiffies;
 139
 140         prev_lev = devfreq_get_freq_level(devfreq, devfreq->previous_freq);
 141         if (prev_lev < 0) {
 142                 ret = prev_lev;
 143                 goto out;
 144         }
 145
 146         devfreq->time_in_state[prev_lev] +=
 147                          cur_time - devfreq->last_stat_updated;
 148
 149         lev = devfreq_get_freq_level(devfreq, freq);
 150         if (lev < 0) {
 151                 ret = lev;
 152                 goto out;
 153         }
 154
 155         if (lev != prev_lev) {
 156                 devfreq->trans_table[(prev_lev *
 157                                 devfreq->profile->max_state) + lev]++;
 158                 devfreq->total_trans++;
 159         }
 160
 161 out:
 162         devfreq->last_stat_updated = cur_time;
 163         return ret;
 164 }
 165
 166 /**
 167  * find_devfreq_governor() - find devfreq governor from name
 168  * @name:       name of the governor
 169  *
 170  * Search the list of devfreq governors and return the matched
 171  * governor's pointer. devfreq_list_lock should be held by the caller.
 172  */
 173 static struct devfreq_governor *find_devfreq_governor(const char *name)
 174 {
 175         struct devfreq_governor *tmp_governor;
 176
 177         if (IS_ERR_OR_NULL(name)) {
 178                 pr_err("DEVFREQ: %s: Invalid parameters\n", __func__);
 179                 return ERR_PTR(-EINVAL);
 180         }
 181         WARN(!mutex_is_locked(&devfreq_list_lock),
 182              "devfreq_list_lock must be locked.");
 183
 184         list_for_each_entry(tmp_governor, &devfreq_governor_list, node) {
 185                 if (!strncmp(tmp_governor->name, name, DEVFREQ_NAME_LEN))
 186                         return tmp_governor;
 187         }
 188
 189         return ERR_PTR(-ENODEV);
 190 }
 191
 192 /* Load monitoring helper functions for governors use */
 193
 194 /**
 195  * update_devfreq() - Reevaluate the device and configure frequency.
 196  * @devfreq:    the devfreq instance.
 197  *
 198  * Note: Lock devfreq->lock before calling update_devfreq
 199  *       This function is exported for governors.
 200  */
 201 int update_devfreq(struct devfreq *devfreq)
 202 {
 203         unsigned long freq;
 204         int err = 0;
 205         u32 flags = 0;
 206
 207         if (!mutex_is_locked(&devfreq->lock)) {
 208                 WARN(true, "devfreq->lock must be locked by the caller.\n");
 209                 return -EINVAL;
 210         }
 211
 212         if (!devfreq->governor)
 213                 return -EINVAL;
 214
 215         /* Reevaluate the proper frequency */
 216         err = devfreq->governor->get_target_freq(devfreq, &freq);
 217         if (err)
 218                 return err;
 219
 220         /*
 221          * Adjust the frequency with user freq and QoS.
 222          *
 223          * List from the highest priority
 224          * max_freq
 225          * min_freq
 226          */
 227
 228         if (devfreq->min_freq && freq < devfreq->min_freq) {
 229                 freq = devfreq->min_freq;
 230                 flags &= ~DEVFREQ_FLAG_LEAST_UPPER_BOUND; /* Use GLB */
 231         }
 232         if (devfreq->max_freq && freq > devfreq->max_freq) {
 233                 freq = devfreq->max_freq;
 234                 flags |= DEVFREQ_FLAG_LEAST_UPPER_BOUND; /* Use LUB */
 235         }
 236
 237         err = devfreq->profile->target(devfreq->dev.parent, &freq, flags);
 238         if (err)
 239                 return err;
 240
 241         if (devfreq->profile->freq_table)
 242                 if (devfreq_update_status(devfreq, freq))
 243                         dev_err(&devfreq->dev,
 244                                 "Couldn't update frequency transition information.\n");
 245
 246         devfreq->previous_freq = freq;
 247         return err;
 248 }
 249 EXPORT_SYMBOL(update_devfreq);
 250
 251 /**
 252  * devfreq_monitor() - Periodically poll devfreq objects.
 253  * @work:       the work struct used to run devfreq_monitor periodically.
 254  *
 255  */
 256 static void devfreq_monitor(struct work_struct *work)
 257 {
 258         int err;
 259         struct devfreq *devfreq = container_of(work,
 260                                         struct devfreq, work.work);
 261
 262         mutex_lock(&devfreq->lock);
 263         err = update_devfreq(devfreq);
 264         if (err)
 265                 dev_err(&devfreq->dev, "dvfs failed with (%d) error\n", err);
 266
 267         queue_delayed_work(devfreq_wq, &devfreq->work,
 268                                 msecs_to_jiffies(devfreq->profile->polling_ms));
 269         mutex_unlock(&devfreq->lock);
 270 }
 271
 272 /**
 273  * devfreq_monitor_start() - Start load monitoring of devfreq instance
 274  * @devfreq:    the devfreq instance.
 275  *
 276  * Helper function for starting devfreq device load monitoing. By
 277  * default delayed work based monitoring is supported. Function
 278  * to be called from governor in response to DEVFREQ_GOV_START
 279  * event when device is added to devfreq framework.
 280  */
 281 void devfreq_monitor_start(struct devfreq *devfreq)
 282 {
 283         INIT_DEFERRABLE_WORK(&devfreq->work, devfreq_monitor);
 284         if (devfreq->profile->polling_ms)
 285                 queue_delayed_work(devfreq_wq, &devfreq->work,
 286                         msecs_to_jiffies(devfreq->profile->polling_ms));
 287 }
 288 EXPORT_SYMBOL(devfreq_monitor_start);
 289
 290 /**
 291  * devfreq_monitor_stop() - Stop load monitoring of a devfreq instance
 292  * @devfreq:    the devfreq instance.
 293  *
 294  * Helper function to stop devfreq device load monitoing. Function
 295  * to be called from governor in response to DEVFREQ_GOV_STOP
 296  * event when device is removed from devfreq framework.
 297  */
 298 void devfreq_monitor_stop(struct devfreq *devfreq)
 299 {
 300         cancel_delayed_work_sync(&devfreq->work);
 301 }
 302 EXPORT_SYMBOL(devfreq_monitor_stop);
 303
 304 /**
 305  * devfreq_monitor_suspend() - Suspend load monitoring of a devfreq instance
 306  * @devfreq:    the devfreq instance.
 307  *
 308  * Helper function to suspend devfreq device load monitoing. Function
 309  * to be called from governor in response to DEVFREQ_GOV_SUSPEND
 310  * event or when polling interval is set to zero.
 311  *
 312  * Note: Though this function is same as devfreq_monitor_stop(),
 313  * intentionally kept separate to provide hooks for collecting
 314  * transition statistics.
 315  */
 316 void devfreq_monitor_suspend(struct devfreq *devfreq)
 317 {
 318         mutex_lock(&devfreq->lock);
 319         if (devfreq->stop_polling) {
 320                 mutex_unlock(&devfreq->lock);
 321                 return;
 322         }
 323
 324         devfreq_update_status(devfreq, devfreq->previous_freq);
 325         devfreq->stop_polling = true;
 326         mutex_unlock(&devfreq->lock);
 327         cancel_delayed_work_sync(&devfreq->work);
 328 }
 329 EXPORT_SYMBOL(devfreq_monitor_suspend);
 330
 331 /**
 332  * devfreq_monitor_resume() - Resume load monitoring of a devfreq instance
 333  * @devfreq:    the devfreq instance.
 334  *
 335  * Helper function to resume devfreq device load monitoing. Function
 336  * to be called from governor in response to DEVFREQ_GOV_RESUME
 337  * event or when polling interval is set to non-zero.
 338  */
 339 void devfreq_monitor_resume(struct devfreq *devfreq)
 340 {
 341         unsigned long freq;
 342
 343         mutex_lock(&devfreq->lock);
 344         if (!devfreq->stop_polling)
 345                 goto out;
 346
 347         if (!delayed_work_pending(&devfreq->work) &&
 348                         devfreq->profile->polling_ms)
 349                 queue_delayed_work(devfreq_wq, &devfreq->work,
 350                         msecs_to_jiffies(devfreq->profile->polling_ms));
 351
 352         devfreq->last_stat_updated = jiffies;
 353         devfreq->stop_polling = false;
 354
 355         if (devfreq->profile->get_cur_freq &&
 356                 !devfreq->profile->get_cur_freq(devfreq->dev.parent, &freq))
 357                 devfreq->previous_freq = freq;
 358
 359 out:
 360         mutex_unlock(&devfreq->lock);
 361 }
 362 EXPORT_SYMBOL(devfreq_monitor_resume);
 363
 364 /**
 365  * devfreq_interval_update() - Update device devfreq monitoring interval
 366  * @devfreq:    the devfreq instance.
 367  * @delay:      new polling interval to be set.
 368  *
 369  * Helper function to set new load monitoring polling interval. Function
 370  * to be called from governor in response to DEVFREQ_GOV_INTERVAL event.
 371  */
 372 void devfreq_interval_update(struct devfreq *devfreq, unsigned int *delay)
 373 {
 374         unsigned int cur_delay = devfreq->profile->polling_ms;
 375         unsigned int new_delay = *delay;
 376
 377         mutex_lock(&devfreq->lock);
 378         devfreq->profile->polling_ms = new_delay;
 379
 380         if (devfreq->stop_polling)
 381                 goto out;
 382
 383         /* if new delay is zero, stop polling */
 384         if (!new_delay) {
 385                 mutex_unlock(&devfreq->lock);
 386                 cancel_delayed_work_sync(&devfreq->work);
 387                 return;
 388         }
 389
 390         /* if current delay is zero, start polling with new delay */
 391         if (!cur_delay) {
 392                 queue_delayed_work(devfreq_wq, &devfreq->work,
 393                         msecs_to_jiffies(devfreq->profile->polling_ms));
 394                 goto out;
 395         }
 396
 397         /* if current delay is greater than new delay, restart polling */
 398         if (cur_delay > new_delay) {
 399                 mutex_unlock(&devfreq->lock);
 400                 cancel_delayed_work_sync(&devfreq->work);
 401                 mutex_lock(&devfreq->lock);
 402                 if (!devfreq->stop_polling)
 403                         queue_delayed_work(devfreq_wq, &devfreq->work,
 404                               msecs_to_jiffies(devfreq->profile->polling_ms));
 405         }
 406 out:
 407         mutex_unlock(&devfreq->lock);
 408 }
 409 EXPORT_SYMBOL(devfreq_interval_update);
 410
 411 /**
 412  * devfreq_notifier_call() - Notify that the device frequency requirements
 413  *                         has been changed out of devfreq framework.
 414  * @nb:         the notifier_block (supposed to be devfreq->nb)
 415  * @type:       not used
 416  * @devp:       not used
 417  *
 418  * Called by a notifier that uses devfreq->nb.
 419  */
 420 static int devfreq_notifier_call(struct notifier_block *nb, unsigned long type,
 421                                  void *devp)
 422 {
 423         struct devfreq *devfreq = container_of(nb, struct devfreq, nb);
 424         int ret;
 425
 426         mutex_lock(&devfreq->lock);
 427         ret = update_devfreq(devfreq);
 428         mutex_unlock(&devfreq->lock);
 429
 430         return ret;
 431 }
 432
 433 /**
 434  * _remove_devfreq() - Remove devfreq from the list and release its resources.
 435  * @devfreq:    the devfreq struct
 436  */
 437 static void _remove_devfreq(struct devfreq *devfreq)
 438 {
 439         mutex_lock(&devfreq_list_lock);
 440         if (IS_ERR(find_device_devfreq(devfreq->dev.parent))) {
 441                 mutex_unlock(&devfreq_list_lock);
 442                 dev_warn(&devfreq->dev, "releasing devfreq which doesn't exist\n");
 443                 return;
 444         }
 445         list_del(&devfreq->node);
 446         mutex_unlock(&devfreq_list_lock);
 447
 448         if (devfreq->governor)
 449                 devfreq->governor->event_handler(devfreq,
 450                                                  DEVFREQ_GOV_STOP, NULL);
 451
 452         if (devfreq->profile->exit)
 453                 devfreq->profile->exit(devfreq->dev.parent);
 454
 455         mutex_destroy(&devfreq->lock);
 456         kfree(devfreq);
 457 }
 458
 459 /**
 460  * devfreq_dev_release() - Callback for struct device to release the device.
 461  * @dev:        the devfreq device
 462  *
 463  * This calls _remove_devfreq() if _remove_devfreq() is not called.
 464  */
 465 static void devfreq_dev_release(struct device *dev)
 466 {
 467         struct devfreq *devfreq = to_devfreq(dev);
 468
 469         _remove_devfreq(devfreq);
 470 }
 471
 472 /**
 473  * devfreq_add_device() - Add devfreq feature to the device
 474  * @dev:        the device to add devfreq feature.
 475  * @profile:    device-specific profile to run devfreq.
 476  * @governor_name:      name of the policy to choose frequency.
 477  * @data:       private data for the governor. The devfreq framework does not
 478  *              touch this value.
 479  */
 480 struct devfreq *devfreq_add_device(struct device *dev,
 481                                    struct devfreq_dev_profile *profile,
 482                                    const char *governor_name,
 483                                    void *data)
 484 {
 485         struct devfreq *devfreq;
 486         struct devfreq_governor *governor;
 487         int err = 0;
 488
 489         if (!dev || !profile || !governor_name) {
 490                 dev_err(dev, "%s: Invalid parameters.\n", __func__);
 491                 return ERR_PTR(-EINVAL);
 492         }
 493
 494         mutex_lock(&devfreq_list_lock);
 495         devfreq = find_device_devfreq(dev);
 496         mutex_unlock(&devfreq_list_lock);
 497         if (!IS_ERR(devfreq)) {
 498                 dev_err(dev, "%s: Unable to create devfreq for the device. It already has one.\n", __func__);
 499                 err = -EINVAL;
 500                 goto err_out;
 501         }
 502
 503         devfreq = kzalloc(sizeof(struct devfreq), GFP_KERNEL);
 504         if (!devfreq) {
 505                 dev_err(dev, "%s: Unable to create devfreq for the device\n",
 506                         __func__);
 507                 err = -ENOMEM;
 508                 goto err_out;
 509         }
 510
 511         mutex_init(&devfreq->lock);
 512         mutex_lock(&devfreq->lock);
 513         devfreq->dev.parent = dev;
 514         devfreq->dev.class = devfreq_class;
 515         devfreq->dev.release = devfreq_dev_release;
 516         devfreq->profile = profile;
 517         strncpy(devfreq->governor_name, governor_name, DEVFREQ_NAME_LEN);
 518         devfreq->previous_freq = profile->initial_freq;
 519         devfreq->data = data;
 520         devfreq->nb.notifier_call = devfreq_notifier_call;
 521
 522         if (!devfreq->profile->max_state && !devfreq->profile->freq_table) {
 523                 mutex_unlock(&devfreq->lock);
 524                 devfreq_set_freq_table(devfreq);
 525                 mutex_lock(&devfreq->lock);
 526         }
 527
 528         devfreq->trans_table =  devm_kzalloc(dev, sizeof(unsigned int) *
 529                                                 devfreq->profile->max_state *
 530                                                 devfreq->profile->max_state,
 531                                                 GFP_KERNEL);
 532         devfreq->time_in_state = devm_kzalloc(dev, sizeof(unsigned long) *
 533                                                 devfreq->profile->max_state,
 534                                                 GFP_KERNEL);
 535         devfreq->last_stat_updated = jiffies;
 536
 537         dev_set_name(&devfreq->dev, "%s", dev_name(dev));
 538         err = device_register(&devfreq->dev);
 539         if (err) {
 540                 put_device(&devfreq->dev);
 541                 mutex_unlock(&devfreq->lock);
 542                 goto err_out;
 543         }
 544
 545         mutex_unlock(&devfreq->lock);
 546
 547         mutex_lock(&devfreq_list_lock);
 548         list_add(&devfreq->node, &devfreq_list);
 549
 550         governor = find_devfreq_governor(devfreq->governor_name);
 551         if (!IS_ERR(governor))
 552                 devfreq->governor = governor;
 553         if (devfreq->governor)
 554                 err = devfreq->governor->event_handler(devfreq,
 555                                         DEVFREQ_GOV_START, NULL);
 556         mutex_unlock(&devfreq_list_lock);
 557         if (err) {
 558                 dev_err(dev, "%s: Unable to start governor for the device\n",
 559                         __func__);
 560                 goto err_init;
 561         }
 562
 563         return devfreq;
 564
 565 err_init:
 566         list_del(&devfreq->node);
 567         device_unregister(&devfreq->dev);
 568         kfree(devfreq);
 569 err_out:
 570         return ERR_PTR(err);
 571 }
 572 EXPORT_SYMBOL(devfreq_add_device);
 573
 574 /**
 575  * devfreq_remove_device() - Remove devfreq feature from a device.
 576  * @devfreq:    the devfreq instance to be removed
 577  *
 578  * The opposite of devfreq_add_device().
 579  */
 580 int devfreq_remove_device(struct devfreq *devfreq)
 581 {
 582         if (!devfreq)
 583                 return -EINVAL;
 584
 585         device_unregister(&devfreq->dev);
 586         put_device(&devfreq->dev);
 587
 588         return 0;
 589 }
 590 EXPORT_SYMBOL(devfreq_remove_device);
 591
 592 static int devm_devfreq_dev_match(struct device *dev, void *res, void *data)
 593 {
 594         struct devfreq **r = res;
 595
 596         if (WARN_ON(!r || !*r))
 597                 return 0;
 598
 599         return *r == data;
 600 }
 601
 602 static void devm_devfreq_dev_release(struct device *dev, void *res)
 603 {
 604         devfreq_remove_device(*(struct devfreq **)res);
 605 }
 606
 607 /**
 608  * devm_devfreq_add_device() - Resource-managed devfreq_add_device()
 609  * @dev:        the device to add devfreq feature.
 610  * @profile:    device-specific profile to run devfreq.
 611  * @governor_name:      name of the policy to choose frequency.
 612  * @data:       private data for the governor. The devfreq framework does not
 613  *              touch this value.
 614  *
 615  * This function manages automatically the memory of devfreq device using device
 616  * resource management and simplify the free operation for memory of devfreq
 617  * device.
 618  */
 619 struct devfreq *devm_devfreq_add_device(struct device *dev,
 620                                         struct devfreq_dev_profile *profile,
 621                                         const char *governor_name,
 622                                         void *data)
 623 {
 624         struct devfreq **ptr, *devfreq;
 625
 626         ptr = devres_alloc(devm_devfreq_dev_release, sizeof(*ptr), GFP_KERNEL);
 627         if (!ptr)
 628                 return ERR_PTR(-ENOMEM);
 629
 630         devfreq = devfreq_add_device(dev, profile, governor_name, data);
 631         if (IS_ERR(devfreq)) {
 632                 devres_free(ptr);
 633                 return ERR_PTR(-ENOMEM);
 634         }
 635
 636         *ptr = devfreq;
 637         devres_add(dev, ptr);
 638
 639         return devfreq;
 640 }
 641 EXPORT_SYMBOL(devm_devfreq_add_device);
 642
 643 #ifdef CONFIG_OF
 644 /*
 645  * devfreq_get_devfreq_by_phandle - Get the devfreq device from devicetree
 646  * @dev - instance to the given device
 647  * @index - index into list of devfreq
 648  *
 649  * return the instance of devfreq device
 650  */
 651 struct devfreq *devfreq_get_devfreq_by_phandle(struct device *dev, int index)
 652 {
 653         struct device_node *node;
 654         struct devfreq *devfreq;
 655
 656         if (!dev)
 657                 return ERR_PTR(-EINVAL);
 658
 659         if (!dev->of_node)
 660                 return ERR_PTR(-EINVAL);
 661
 662         node = of_parse_phandle(dev->of_node, "devfreq", index);
 663         if (!node)
 664                 return ERR_PTR(-ENODEV);
 665
 666         mutex_lock(&devfreq_list_lock);
 667         list_for_each_entry(devfreq, &devfreq_list, node) {
 668                 if (devfreq->dev.parent
 669                         && devfreq->dev.parent->of_node == node) {
 670                         mutex_unlock(&devfreq_list_lock);
 671                         return devfreq;
 672                 }
 673         }
 674         mutex_unlock(&devfreq_list_lock);
 675
 676         return ERR_PTR(-EPROBE_DEFER);
 677 }
 678 #else
 679 struct devfreq *devfreq_get_devfreq_by_phandle(struct device *dev, int index)
 680 {
 681         return ERR_PTR(-ENODEV);
 682 }
 683 #endif /* CONFIG_OF */
 684 EXPORT_SYMBOL_GPL(devfreq_get_devfreq_by_phandle);
 685
 686 /**
 687  * devm_devfreq_remove_device() - Resource-managed devfreq_remove_device()
 688  * @dev:        the device to add devfreq feature.
 689  * @devfreq:    the devfreq instance to be removed
 690  */
 691 void devm_devfreq_remove_device(struct device *dev, struct devfreq *devfreq)
 692 {
 693         WARN_ON(devres_release(dev, devm_devfreq_dev_release,
 694                                devm_devfreq_dev_match, devfreq));
 695 }
 696 EXPORT_SYMBOL(devm_devfreq_remove_device);
 697
 698 /**
 699  * devfreq_suspend_device() - Suspend devfreq of a device.
 700  * @devfreq: the devfreq instance to be suspended
 701  *
 702  * This function is intended to be called by the pm callbacks
 703  * (e.g., runtime_suspend, suspend) of the device driver that
 704  * holds the devfreq.
 705  */
 706 int devfreq_suspend_device(struct devfreq *devfreq)
 707 {
 708         if (!devfreq)
 709                 return -EINVAL;
 710
 711         if (!devfreq->governor)
 712                 return 0;
 713
 714         return devfreq->governor->event_handler(devfreq,
 715                                 DEVFREQ_GOV_SUSPEND, NULL);
 716 }
 717 EXPORT_SYMBOL(devfreq_suspend_device);
 718
 719 /**
 720  * devfreq_resume_device() - Resume devfreq of a device.
 721  * @devfreq: the devfreq instance to be resumed
 722  *
 723  * This function is intended to be called by the pm callbacks
 724  * (e.g., runtime_resume, resume) of the device driver that
 725  * holds the devfreq.
 726  */
 727 int devfreq_resume_device(struct devfreq *devfreq)
 728 {
 729         if (!devfreq)
 730                 return -EINVAL;
 731
 732         if (!devfreq->governor)
 733                 return 0;
 734
 735         return devfreq->governor->event_handler(devfreq,
 736                                 DEVFREQ_GOV_RESUME, NULL);
 737 }
 738 EXPORT_SYMBOL(devfreq_resume_device);
 739
 740 /**
 741  * devfreq_add_governor() - Add devfreq governor
 742  * @governor:   the devfreq governor to be added
 743  */
 744 int devfreq_add_governor(struct devfreq_governor *governor)
 745 {
 746         struct devfreq_governor *g;
 747         struct devfreq *devfreq;
 748         int err = 0;
 749
 750         if (!governor) {
 751                 pr_err("%s: Invalid parameters.\n", __func__);
 752                 return -EINVAL;
 753         }
 754
 755         mutex_lock(&devfreq_list_lock);
 756         g = find_devfreq_governor(governor->name);
 757         if (!IS_ERR(g)) {
 758                 pr_err("%s: governor %s already registered\n", __func__,
 759                        g->name);
 760                 err = -EINVAL;
 761                 goto err_out;
 762         }
 763
 764         list_add(&governor->node, &devfreq_governor_list);
 765
 766         list_for_each_entry(devfreq, &devfreq_list, node) {
 767                 int ret = 0;
 768                 struct device *dev = devfreq->dev.parent;
 769
 770                 if (!strncmp(devfreq->governor_name, governor->name,
 771                              DEVFREQ_NAME_LEN)) {
 772                         /* The following should never occur */
 773                         if (devfreq->governor) {
 774                                 dev_warn(dev,
 775                                          "%s: Governor %s already present\n",
 776                                          __func__, devfreq->governor->name);
 777                                 ret = devfreq->governor->event_handler(devfreq,
 778                                                         DEVFREQ_GOV_STOP, NULL);
 779                                 if (ret) {
 780                                         dev_warn(dev,
 781                                                  "%s: Governor %s stop = %d\n",
 782                                                  __func__,
 783                                                  devfreq->governor->name, ret);
 784                                 }
 785                                 /* Fall through */
 786                         }
 787                         devfreq->governor = governor;
 788                         ret = devfreq->governor->event_handler(devfreq,
 789                                                 DEVFREQ_GOV_START, NULL);
 790                         if (ret) {
 791                                 dev_warn(dev, "%s: Governor %s start=%d\n",
 792                                          __func__, devfreq->governor->name,
 793                                          ret);
 794                         }
 795                 }
 796         }
 797
 798 err_out:
 799         mutex_unlock(&devfreq_list_lock);
 800
 801         return err;
 802 }
 803 EXPORT_SYMBOL(devfreq_add_governor);
 804
 805 /**
 806  * devfreq_remove_device() - Remove devfreq feature from a device.
 807  * @governor:   the devfreq governor to be removed
 808  */
 809 int devfreq_remove_governor(struct devfreq_governor *governor)
 810 {
 811         struct devfreq_governor *g;
 812         struct devfreq *devfreq;
 813         int err = 0;
 814
 815         if (!governor) {
 816                 pr_err("%s: Invalid parameters.\n", __func__);
 817                 return -EINVAL;
 818         }
 819
 820         mutex_lock(&devfreq_list_lock);
 821         g = find_devfreq_governor(governor->name);
 822         if (IS_ERR(g)) {
 823                 pr_err("%s: governor %s not registered\n", __func__,
 824                        governor->name);
 825                 err = PTR_ERR(g);
 826                 goto err_out;
 827         }
 828         list_for_each_entry(devfreq, &devfreq_list, node) {
 829                 int ret;
 830                 struct device *dev = devfreq->dev.parent;
 831
 832                 if (!strncmp(devfreq->governor_name, governor->name,
 833                              DEVFREQ_NAME_LEN)) {
 834                         /* we should have a devfreq governor! */
 835                         if (!devfreq->governor) {
 836                                 dev_warn(dev, "%s: Governor %s NOT present\n",
 837                                          __func__, governor->name);
 838                                 continue;
 839                                 /* Fall through */
 840                         }
 841                         ret = devfreq->governor->event_handler(devfreq,
 842                                                 DEVFREQ_GOV_STOP, NULL);
 843                         if (ret) {
 844                                 dev_warn(dev, "%s: Governor %s stop=%d\n",
 845                                          __func__, devfreq->governor->name,
 846                                          ret);
 847                         }
 848                         devfreq->governor = NULL;
 849                 }
 850         }
 851
 852         list_del(&governor->node);
 853 err_out:
 854         mutex_unlock(&devfreq_list_lock);
 855
 856         return err;
 857 }
 858 EXPORT_SYMBOL(devfreq_remove_governor);
 859
 860 static ssize_t governor_show(struct device *dev,
 861                              struct device_attribute *attr, char *buf)
 862 {
 863         if (!to_devfreq(dev)->governor)
 864                 return -EINVAL;
 865
 866         return sprintf(buf, "%s\n", to_devfreq(dev)->governor->name);
 867 }
 868
 869 static ssize_t governor_store(struct device *dev, struct device_attribute *attr,
 870                               const char *buf, size_t count)
 871 {
 872         struct devfreq *df = to_devfreq(dev);
 873         int ret;
 874         char str_governor[DEVFREQ_NAME_LEN + 1];
 875         struct devfreq_governor *governor;
 876
 877         ret = sscanf(buf, "%" __stringify(DEVFREQ_NAME_LEN) "s", str_governor);
 878         if (ret != 1)
 879                 return -EINVAL;
 880
 881         mutex_lock(&devfreq_list_lock);
 882         governor = find_devfreq_governor(str_governor);
 883         if (IS_ERR(governor)) {
 884                 ret = PTR_ERR(governor);
 885                 goto out;
 886         }
 887         if (df->governor == governor) {
 888                 ret = 0;
 889                 goto out;
 890         }
 891
 892         if (df->governor) {
 893                 ret = df->governor->event_handler(df, DEVFREQ_GOV_STOP, NULL);
 894                 if (ret) {
 895                         dev_warn(dev, "%s: Governor %s not stopped(%d)\n",
 896                                  __func__, df->governor->name, ret);
 897                         goto out;
 898                 }
 899         }
 900         df->governor = governor;
 901         strncpy(df->governor_name, governor->name, DEVFREQ_NAME_LEN);
 902         ret = df->governor->event_handler(df, DEVFREQ_GOV_START, NULL);
 903         if (ret)
 904                 dev_warn(dev, "%s: Governor %s not started(%d)\n",
 905                          __func__, df->governor->name, ret);
 906 out:
 907         mutex_unlock(&devfreq_list_lock);
 908
 909         if (!ret)
 910                 ret = count;
 911         return ret;
 912 }
 913 static DEVICE_ATTR_RW(governor);
 914
 915 static ssize_t available_governors_show(struct device *d,
 916                                         struct device_attribute *attr,
 917                                         char *buf)
 918 {
 919         struct devfreq_governor *tmp_governor;
 920         ssize_t count = 0;
 921
 922         mutex_lock(&devfreq_list_lock);
 923         list_for_each_entry(tmp_governor, &devfreq_governor_list, node)
 924                 count += scnprintf(&buf[count], (PAGE_SIZE - count - 2),
 925                                    "%s ", tmp_governor->name);
 926         mutex_unlock(&devfreq_list_lock);
 927
 928         /* Truncate the trailing space */
 929         if (count)
 930                 count--;
 931
 932         count += sprintf(&buf[count], "\n");
 933
 934         return count;
 935 }
 936 static DEVICE_ATTR_RO(available_governors);
 937
 938 static ssize_t cur_freq_show(struct device *dev, struct device_attribute *attr,
 939                              char *buf)
 940 {
 941         unsigned long freq;
 942         struct devfreq *devfreq = to_devfreq(dev);
 943
 944         if (devfreq->profile->get_cur_freq &&
 945                 !devfreq->profile->get_cur_freq(devfreq->dev.parent, &freq))
 946                         return sprintf(buf, "%lu\n", freq);
 947
 948         return sprintf(buf, "%lu\n", devfreq->previous_freq);
 949 }
 950 static DEVICE_ATTR_RO(cur_freq);
 951
 952 static ssize_t target_freq_show(struct device *dev,
 953                                 struct device_attribute *attr, char *buf)
 954 {
 955         return sprintf(buf, "%lu\n", to_devfreq(dev)->previous_freq);
 956 }
 957 static DEVICE_ATTR_RO(target_freq);
 958
 959 static ssize_t polling_interval_show(struct device *dev,
 960                                      struct device_attribute *attr, char *buf)
 961 {
 962         return sprintf(buf, "%d\n", to_devfreq(dev)->profile->polling_ms);
 963 }
 964
 965 static ssize_t polling_interval_store(struct device *dev,
 966                                       struct device_attribute *attr,
 967                                       const char *buf, size_t count)
 968 {
 969         struct devfreq *df = to_devfreq(dev);
 970         unsigned int value;
 971         int ret;
 972
 973         if (!df->governor)
 974                 return -EINVAL;
 975
 976         ret = sscanf(buf, "%u", &value);
 977         if (ret != 1)
 978                 return -EINVAL;
 979
 980         df->governor->event_handler(df, DEVFREQ_GOV_INTERVAL, &value);
 981         ret = count;
 982
 983         return ret;
 984 }
 985 static DEVICE_ATTR_RW(polling_interval);
 986
 987 static ssize_t min_freq_store(struct device *dev, struct device_attribute *attr,
 988                               const char *buf, size_t count)
 989 {
 990         struct devfreq *df = to_devfreq(dev);
 991         unsigned long value;
 992         int ret;
 993         unsigned long max;
 994
 995         ret = sscanf(buf, "%lu", &value);
 996         if (ret != 1)
 997                 return -EINVAL;
 998
 999         mutex_lock(&df->lock);
1000         max = df->max_freq;
1001         if (value && max && value > max) {
1002                 ret = -EINVAL;
1003                 goto unlock;
1004         }
1005
1006         df->min_freq = value;
1007         update_devfreq(df);
1008         ret = count;
1009 unlock:
1010         mutex_unlock(&df->lock);
1011         return ret;
1012 }
1013
1014 static ssize_t max_freq_store(struct device *dev, struct device_attribute *attr,
1015                               const char *buf, size_t count)
1016 {
1017         struct devfreq *df = to_devfreq(dev);
1018         unsigned long value;
1019         int ret;
1020         unsigned long min;
1021
1022         ret = sscanf(buf, "%lu", &value);
1023         if (ret != 1)
1024                 return -EINVAL;
1025
1026         mutex_lock(&df->lock);
1027         min = df->min_freq;
1028         if (value && min && value < min) {
1029                 ret = -EINVAL;
1030                 goto unlock;
1031         }
1032
1033         df->max_freq = value;
1034         update_devfreq(df);
1035         ret = count;
1036 unlock:
1037         mutex_unlock(&df->lock);
1038         return ret;
1039 }
1040
1041 #define show_one(name)                                          \
1042 static ssize_t name##_show                                      \
1043 (struct device *dev, struct device_attribute *attr, char *buf)  \
1044 {                                                               \
1045         return sprintf(buf, "%lu\n", to_devfreq(dev)->name);    \
1046 }
1047 show_one(min_freq);
1048 show_one(max_freq);
1049
1050 static DEVICE_ATTR_RW(min_freq);
1051 static DEVICE_ATTR_RW(max_freq);
1052
1053 static ssize_t available_frequencies_show(struct device *d,
1054                                           struct device_attribute *attr,
1055                                           char *buf)
1056 {
1057         struct devfreq *df = to_devfreq(d);
1058         struct device *dev = df->dev.parent;
1059         struct dev_pm_opp *opp;
1060         ssize_t count = 0;
1061         unsigned long freq = 0;
1062
1063         rcu_read_lock();
1064         do {
1065                 opp = dev_pm_opp_find_freq_ceil(dev, &freq);
1066                 if (IS_ERR(opp))
1067                         break;
1068
1069                 count += scnprintf(&buf[count], (PAGE_SIZE - count - 2),
1070                                    "%lu ", freq);
1071                 freq++;
1072         } while (1);
1073         rcu_read_unlock();
1074
1075         /* Truncate the trailing space */
1076         if (count)
1077                 count--;
1078
1079         count += sprintf(&buf[count], "\n");
1080
1081         return count;
1082 }
1083 static DEVICE_ATTR_RO(available_frequencies);
1084
1085 static ssize_t trans_stat_show(struct device *dev,
1086                                struct device_attribute *attr, char *buf)
1087 {
1088         struct devfreq *devfreq = to_devfreq(dev);
1089         ssize_t len;
1090         int i, j;
1091         unsigned int max_state = devfreq->profile->max_state;
1092
1093         if (!devfreq->stop_polling &&
1094                         devfreq_update_status(devfreq, devfreq->previous_freq))
1095                 return 0;
1096         if (max_state == 0)
1097                 return sprintf(buf, "Not Supported.\n");
1098
1099         len = sprintf(buf, "     From  :   To\n");
1100         len += sprintf(buf + len, "           :");
1101         for (i = 0; i < max_state; i++)
1102                 len += sprintf(buf + len, "%10lu",
1103                                 devfreq->profile->freq_table[i]);
1104
1105         len += sprintf(buf + len, "   time(ms)\n");
1106
1107         for (i = 0; i < max_state; i++) {
1108                 if (devfreq->profile->freq_table[i]
1109                                         == devfreq->previous_freq) {
1110                         len += sprintf(buf + len, "*");
1111                 } else {
1112                         len += sprintf(buf + len, " ");
1113                 }
1114                 len += sprintf(buf + len, "%10lu:",
1115                                 devfreq->profile->freq_table[i]);
1116                 for (j = 0; j < max_state; j++)
1117                         len += sprintf(buf + len, "%10u",
1118                                 devfreq->trans_table[(i * max_state) + j]);
1119                 len += sprintf(buf + len, "%10u\n",
1120                         jiffies_to_msecs(devfreq->time_in_state[i]));
1121         }
1122
1123         len += sprintf(buf + len, "Total transition : %u\n",
1124                                         devfreq->total_trans);
1125         return len;
1126 }
1127 static DEVICE_ATTR_RO(trans_stat);
1128
1129 static struct attribute *devfreq_attrs[] = {
1130         &dev_attr_governor.attr,
1131         &dev_attr_available_governors.attr,
1132         &dev_attr_cur_freq.attr,
1133         &dev_attr_available_frequencies.attr,
1134         &dev_attr_target_freq.attr,
1135         &dev_attr_polling_interval.attr,
1136         &dev_attr_min_freq.attr,
1137         &dev_attr_max_freq.attr,
1138         &dev_attr_trans_stat.attr,
1139         NULL,
1140 };
1141 ATTRIBUTE_GROUPS(devfreq);
1142
1143 static int __init devfreq_init(void)
1144 {
1145         devfreq_class = class_create(THIS_MODULE, "devfreq");
1146         if (IS_ERR(devfreq_class)) {
1147                 pr_err("%s: couldn't create class\n", __FILE__);
1148                 return PTR_ERR(devfreq_class);
1149         }
1150
1151         devfreq_wq = create_freezable_workqueue("devfreq_wq");
1152         if (!devfreq_wq) {
1153                 class_destroy(devfreq_class);
1154                 pr_err("%s: couldn't create workqueue\n", __FILE__);
1155                 return -ENOMEM;
1156         }
1157         devfreq_class->dev_groups = devfreq_groups;
1158
1159         return 0;
1160 }
1161 subsys_initcall(devfreq_init);
1162
1163 static void __exit devfreq_exit(void)
1164 {
1165         class_destroy(devfreq_class);
1166         destroy_workqueue(devfreq_wq);
1167 }
1168 module_exit(devfreq_exit);
1169
1170 /*
1171  * The followings are helper functions for devfreq user device drivers with
1172  * OPP framework.
1173  */
1174
1175 /**
1176  * devfreq_recommended_opp() - Helper function to get proper OPP for the
1177  *                           freq value given to target callback.
1178  * @dev:        The devfreq user device. (parent of devfreq)
1179  * @freq:       The frequency given to target function
1180  * @flags:      Flags handed from devfreq framework.
1181  *
1182  * Locking: This function must be called under rcu_read_lock(). opp is a rcu
1183  * protected pointer. The reason for the same is that the opp pointer which is
1184  * returned will remain valid for use with opp_get_{voltage, freq} only while
1185  * under the locked area. The pointer returned must be used prior to unlocking
1186  * with rcu_read_unlock() to maintain the integrity of the pointer.
1187  */
1188 struct dev_pm_opp *devfreq_recommended_opp(struct device *dev,
1189                                            unsigned long *freq,
1190                                            u32 flags)
1191 {
1192         struct dev_pm_opp *opp;
1193
1194         if (flags & DEVFREQ_FLAG_LEAST_UPPER_BOUND) {
1195                 /* The freq is an upper bound. opp should be lower */
1196                 opp = dev_pm_opp_find_freq_floor(dev, freq);
1197
1198                 /* If not available, use the closest opp */
1199                 if (opp == ERR_PTR(-ERANGE))
1200                         opp = dev_pm_opp_find_freq_ceil(dev, freq);
1201         } else {
1202                 /* The freq is an lower bound. opp should be higher */
1203                 opp = dev_pm_opp_find_freq_ceil(dev, freq);
1204
1205                 /* If not available, use the closest opp */
1206                 if (opp == ERR_PTR(-ERANGE))
1207                         opp = dev_pm_opp_find_freq_floor(dev, freq);
1208         }
1209
1210         return opp;
1211 }
1212 EXPORT_SYMBOL(devfreq_recommended_opp);
1213
1214 /**
1215  * devfreq_register_opp_notifier() - Helper function to get devfreq notified
1216  *                                 for any changes in the OPP availability
1217  *                                 changes
1218  * @dev:        The devfreq user device. (parent of devfreq)
1219  * @devfreq:    The devfreq object.
1220  */
1221 int devfreq_register_opp_notifier(struct device *dev, struct devfreq *devfreq)
1222 {
1223         struct srcu_notifier_head *nh;
1224         int ret = 0;
1225
1226         rcu_read_lock();
1227         nh = dev_pm_opp_get_notifier(dev);
1228         if (IS_ERR(nh))
1229                 ret = PTR_ERR(nh);
1230         rcu_read_unlock();
1231         if (!ret)
1232                 ret = srcu_notifier_chain_register(nh, &devfreq->nb);
1233
1234         return ret;
1235 }
1236 EXPORT_SYMBOL(devfreq_register_opp_notifier);
1237
1238 /**
1239  * devfreq_unregister_opp_notifier() - Helper function to stop getting devfreq
1240  *                                   notified for any changes in the OPP
1241  *                                   availability changes anymore.
1242  * @dev:        The devfreq user device. (parent of devfreq)
1243  * @devfreq:    The devfreq object.
1244  *
1245  * At exit() callback of devfreq_dev_profile, this must be included if
1246  * devfreq_recommended_opp is used.
1247  */
1248 int devfreq_unregister_opp_notifier(struct device *dev, struct devfreq *devfreq)
1249 {
1250         struct srcu_notifier_head *nh;
1251         int ret = 0;
1252
1253         rcu_read_lock();
1254         nh = dev_pm_opp_get_notifier(dev);
1255         if (IS_ERR(nh))
1256                 ret = PTR_ERR(nh);
1257         rcu_read_unlock();
1258         if (!ret)
1259                 ret = srcu_notifier_chain_unregister(nh, &devfreq->nb);
1260
1261         return ret;
1262 }
1263 EXPORT_SYMBOL(devfreq_unregister_opp_notifier);
1264
1265 static void devm_devfreq_opp_release(struct device *dev, void *res)
1266 {
1267         devfreq_unregister_opp_notifier(dev, *(struct devfreq **)res);
1268 }
1269
1270 /**
1271  * devm_ devfreq_register_opp_notifier()
1272  *              - Resource-managed devfreq_register_opp_notifier()
1273  * @dev:        The devfreq user device. (parent of devfreq)
1274  * @devfreq:    The devfreq object.
1275  */
1276 int devm_devfreq_register_opp_notifier(struct device *dev,
1277                                        struct devfreq *devfreq)
1278 {
1279         struct devfreq **ptr;
1280         int ret;
1281
1282         ptr = devres_alloc(devm_devfreq_opp_release, sizeof(*ptr), GFP_KERNEL);
1283         if (!ptr)
1284                 return -ENOMEM;
1285
1286         ret = devfreq_register_opp_notifier(dev, devfreq);
1287         if (ret) {
1288                 devres_free(ptr);
1289                 return ret;
1290         }
1291
1292         *ptr = devfreq;
1293         devres_add(dev, ptr);
1294
1295         return 0;
1296 }
1297 EXPORT_SYMBOL(devm_devfreq_register_opp_notifier);
1298
1299 /**
1300  * devm_devfreq_unregister_opp_notifier()
1301  *              - Resource-managed devfreq_unregister_opp_notifier()
1302  * @dev:        The devfreq user device. (parent of devfreq)
1303  * @devfreq:    The devfreq object.
1304  */
1305 void devm_devfreq_unregister_opp_notifier(struct device *dev,
1306                                          struct devfreq *devfreq)
1307 {
1308         WARN_ON(devres_release(dev, devm_devfreq_opp_release,
1309                                devm_devfreq_dev_match, devfreq));
1310 }
1311 EXPORT_SYMBOL(devm_devfreq_unregister_opp_notifier);
1312
1313 MODULE_AUTHOR("MyungJoo Ham <myungjoo.ham@samsung.com>");
1314 MODULE_DESCRIPTION("devfreq class support");
1315 MODULE_LICENSE("GPL");