drivers/devfreq/devfreq.c

   1 /*
   2  * devfreq: Generic Dynamic Voltage and Frequency Scaling (DVFS) Framework
   3  *          for Non-CPU Devices.
   4  *
   5  * Copyright (C) 2011 Samsung Electronics
   6  *      MyungJoo Ham <myungjoo.ham@samsung.com>
   7  *
   8  * This program is free software; you can redistribute it and/or modify
   9  * it under the terms of the GNU General Public License version 2 as
  10  * published by the Free Software Foundation.
  11  */
  12
  13 #include <linux/kernel.h>
  14 #include <linux/sched.h>
  15 #include <linux/errno.h>
  16 #include <linux/err.h>
  17 #include <linux/init.h>
  18 #include <linux/module.h>
  19 #include <linux/slab.h>
  20 #include <linux/stat.h>
  21 #include <linux/pm_opp.h>
  22 #include <linux/devfreq.h>
  23 #include <linux/workqueue.h>
  24 #include <linux/platform_device.h>
  25 #include <linux/list.h>
  26 #include <linux/printk.h>
  27 #include <linux/hrtimer.h>
  28 #include "governor.h"
  29
  30 static struct class *devfreq_class;
  31
  32 /*
  33  * devfreq core provides delayed work based load monitoring helper
  34  * functions. Governors can use these or can implement their own
  35  * monitoring mechanism.
  36  */
  37 static struct workqueue_struct *devfreq_wq;
  38
  39 /* The list of all device-devfreq governors */
  40 static LIST_HEAD(devfreq_governor_list);
  41 /* The list of all device-devfreq */
  42 static LIST_HEAD(devfreq_list);
  43 static DEFINE_MUTEX(devfreq_list_lock);
  44
  45 /**
  46  * find_device_devfreq() - find devfreq struct using device pointer
  47  * @dev:        device pointer used to lookup device devfreq.
  48  *
  49  * Search the list of device devfreqs and return the matched device's
  50  * devfreq info. devfreq_list_lock should be held by the caller.
  51  */
  52 static struct devfreq *find_device_devfreq(struct device *dev)
  53 {
  54         struct devfreq *tmp_devfreq;
  55
  56         if (IS_ERR_OR_NULL(dev)) {
  57                 pr_err("DEVFREQ: %s: Invalid parameters\n", __func__);
  58                 return ERR_PTR(-EINVAL);
  59         }
  60         WARN(!mutex_is_locked(&devfreq_list_lock),
  61              "devfreq_list_lock must be locked.");
  62
  63         list_for_each_entry(tmp_devfreq, &devfreq_list, node) {
  64                 if (tmp_devfreq->dev.parent == dev)
  65                         return tmp_devfreq;
  66         }
  67
  68         return ERR_PTR(-ENODEV);
  69 }
  70
  71 /**
  72  * devfreq_get_freq_level() - Lookup freq_table for the frequency
  73  * @devfreq:    the devfreq instance
  74  * @freq:       the target frequency
  75  */
  76 static int devfreq_get_freq_level(struct devfreq *devfreq, unsigned long freq)
  77 {
  78         int lev;
  79
  80         for (lev = 0; lev < devfreq->profile->max_state; lev++)
  81                 if (freq == devfreq->profile->freq_table[lev])
  82                         return lev;
  83
  84         return -EINVAL;
  85 }
  86
  87 /**
  88  * devfreq_set_freq_table() - Initialize freq_table for the frequency
  89  * @devfreq:    the devfreq instance
  90  */
  91 static void devfreq_set_freq_table(struct devfreq *devfreq)
  92 {
  93         struct devfreq_dev_profile *profile = devfreq->profile;
  94         struct dev_pm_opp *opp;
  95         unsigned long freq;
  96         int i, count;
  97
  98         /* Initialize the freq_table from OPP table */
  99         count = dev_pm_opp_get_opp_count(devfreq->dev.parent);
 100         if (count <= 0)
 101                 return;
 102
 103         profile->max_state = count;
 104         profile->freq_table = devm_kcalloc(devfreq->dev.parent,
 105                                         profile->max_state,
 106                                         sizeof(*profile->freq_table),
 107                                         GFP_KERNEL);
 108         if (!profile->freq_table) {
 109                 profile->max_state = 0;
 110                 return;
 111         }
 112
 113         rcu_read_lock();
 114         for (i = 0, freq = 0; i < profile->max_state; i++, freq++) {
 115                 opp = dev_pm_opp_find_freq_ceil(devfreq->dev.parent, &freq);
 116                 if (IS_ERR(opp)) {
 117                         devm_kfree(devfreq->dev.parent, profile->freq_table);
 118                         profile->max_state = 0;
 119                         rcu_read_unlock();
 120                         return;
 121                 }
 122                 profile->freq_table[i] = freq;
 123         }
 124         rcu_read_unlock();
 125 }
 126
 127 /**
 128  * devfreq_update_status() - Update statistics of devfreq behavior
 129  * @devfreq:    the devfreq instance
 130  * @freq:       the update target frequency
 131  */
 132 static int devfreq_update_status(struct devfreq *devfreq, unsigned long freq)
 133 {
 134         int lev, prev_lev, ret = 0;
 135         unsigned long cur_time;
 136
 137         cur_time = jiffies;
 138
 139         prev_lev = devfreq_get_freq_level(devfreq, devfreq->previous_freq);
 140         if (prev_lev < 0) {
 141                 ret = prev_lev;
 142                 goto out;
 143         }
 144
 145         devfreq->time_in_state[prev_lev] +=
 146                          cur_time - devfreq->last_stat_updated;
 147
 148         lev = devfreq_get_freq_level(devfreq, freq);
 149         if (lev < 0) {
 150                 ret = lev;
 151                 goto out;
 152         }
 153
 154         if (lev != prev_lev) {
 155                 devfreq->trans_table[(prev_lev *
 156                                 devfreq->profile->max_state) + lev]++;
 157                 devfreq->total_trans++;
 158         }
 159
 160 out:
 161         devfreq->last_stat_updated = cur_time;
 162         return ret;
 163 }
 164
 165 /**
 166  * find_devfreq_governor() - find devfreq governor from name
 167  * @name:       name of the governor
 168  *
 169  * Search the list of devfreq governors and return the matched
 170  * governor's pointer. devfreq_list_lock should be held by the caller.
 171  */
 172 static struct devfreq_governor *find_devfreq_governor(const char *name)
 173 {
 174         struct devfreq_governor *tmp_governor;
 175
 176         if (IS_ERR_OR_NULL(name)) {
 177                 pr_err("DEVFREQ: %s: Invalid parameters\n", __func__);
 178                 return ERR_PTR(-EINVAL);
 179         }
 180         WARN(!mutex_is_locked(&devfreq_list_lock),
 181              "devfreq_list_lock must be locked.");
 182
 183         list_for_each_entry(tmp_governor, &devfreq_governor_list, node) {
 184                 if (!strncmp(tmp_governor->name, name, DEVFREQ_NAME_LEN))
 185                         return tmp_governor;
 186         }
 187
 188         return ERR_PTR(-ENODEV);
 189 }
 190
 191 /* Load monitoring helper functions for governors use */
 192
 193 /**
 194  * update_devfreq() - Reevaluate the device and configure frequency.
 195  * @devfreq:    the devfreq instance.
 196  *
 197  * Note: Lock devfreq->lock before calling update_devfreq
 198  *       This function is exported for governors.
 199  */
 200 int update_devfreq(struct devfreq *devfreq)
 201 {
 202         unsigned long freq;
 203         int err = 0;
 204         u32 flags = 0;
 205
 206         if (!mutex_is_locked(&devfreq->lock)) {
 207                 WARN(true, "devfreq->lock must be locked by the caller.\n");
 208                 return -EINVAL;
 209         }
 210
 211         if (!devfreq->governor)
 212                 return -EINVAL;
 213
 214         /* Reevaluate the proper frequency */
 215         err = devfreq->governor->get_target_freq(devfreq, &freq);
 216         if (err)
 217                 return err;
 218
 219         /*
 220          * Adjust the frequency with user freq and QoS.
 221          *
 222          * List from the highest priority
 223          * max_freq
 224          * min_freq
 225          */
 226
 227         if (devfreq->min_freq && freq < devfreq->min_freq) {
 228                 freq = devfreq->min_freq;
 229                 flags &= ~DEVFREQ_FLAG_LEAST_UPPER_BOUND; /* Use GLB */
 230         }
 231         if (devfreq->max_freq && freq > devfreq->max_freq) {
 232                 freq = devfreq->max_freq;
 233                 flags |= DEVFREQ_FLAG_LEAST_UPPER_BOUND; /* Use LUB */
 234         }
 235
 236         err = devfreq->profile->target(devfreq->dev.parent, &freq, flags);
 237         if (err)
 238                 return err;
 239
 240         if (devfreq->profile->freq_table)
 241                 if (devfreq_update_status(devfreq, freq))
 242                         dev_err(&devfreq->dev,
 243                                 "Couldn't update frequency transition information.\n");
 244
 245         devfreq->previous_freq = freq;
 246         return err;
 247 }
 248 EXPORT_SYMBOL(update_devfreq);
 249
 250 /**
 251  * devfreq_monitor() - Periodically poll devfreq objects.
 252  * @work:       the work struct used to run devfreq_monitor periodically.
 253  *
 254  */
 255 static void devfreq_monitor(struct work_struct *work)
 256 {
 257         int err;
 258         struct devfreq *devfreq = container_of(work,
 259                                         struct devfreq, work.work);
 260
 261         mutex_lock(&devfreq->lock);
 262         err = update_devfreq(devfreq);
 263         if (err)
 264                 dev_err(&devfreq->dev, "dvfs failed with (%d) error\n", err);
 265
 266         queue_delayed_work(devfreq_wq, &devfreq->work,
 267                                 msecs_to_jiffies(devfreq->profile->polling_ms));
 268         mutex_unlock(&devfreq->lock);
 269 }
 270
 271 /**
 272  * devfreq_monitor_start() - Start load monitoring of devfreq instance
 273  * @devfreq:    the devfreq instance.
 274  *
 275  * Helper function for starting devfreq device load monitoing. By
 276  * default delayed work based monitoring is supported. Function
 277  * to be called from governor in response to DEVFREQ_GOV_START
 278  * event when device is added to devfreq framework.
 279  */
 280 void devfreq_monitor_start(struct devfreq *devfreq)
 281 {
 282         INIT_DEFERRABLE_WORK(&devfreq->work, devfreq_monitor);
 283         if (devfreq->profile->polling_ms)
 284                 queue_delayed_work(devfreq_wq, &devfreq->work,
 285                         msecs_to_jiffies(devfreq->profile->polling_ms));
 286 }
 287 EXPORT_SYMBOL(devfreq_monitor_start);
 288
 289 /**
 290  * devfreq_monitor_stop() - Stop load monitoring of a devfreq instance
 291  * @devfreq:    the devfreq instance.
 292  *
 293  * Helper function to stop devfreq device load monitoing. Function
 294  * to be called from governor in response to DEVFREQ_GOV_STOP
 295  * event when device is removed from devfreq framework.
 296  */
 297 void devfreq_monitor_stop(struct devfreq *devfreq)
 298 {
 299         cancel_delayed_work_sync(&devfreq->work);
 300 }
 301 EXPORT_SYMBOL(devfreq_monitor_stop);
 302
 303 /**
 304  * devfreq_monitor_suspend() - Suspend load monitoring of a devfreq instance
 305  * @devfreq:    the devfreq instance.
 306  *
 307  * Helper function to suspend devfreq device load monitoing. Function
 308  * to be called from governor in response to DEVFREQ_GOV_SUSPEND
 309  * event or when polling interval is set to zero.
 310  *
 311  * Note: Though this function is same as devfreq_monitor_stop(),
 312  * intentionally kept separate to provide hooks for collecting
 313  * transition statistics.
 314  */
 315 void devfreq_monitor_suspend(struct devfreq *devfreq)
 316 {
 317         mutex_lock(&devfreq->lock);
 318         if (devfreq->stop_polling) {
 319                 mutex_unlock(&devfreq->lock);
 320                 return;
 321         }
 322
 323         devfreq_update_status(devfreq, devfreq->previous_freq);
 324         devfreq->stop_polling = true;
 325         mutex_unlock(&devfreq->lock);
 326         cancel_delayed_work_sync(&devfreq->work);
 327 }
 328 EXPORT_SYMBOL(devfreq_monitor_suspend);
 329
 330 /**
 331  * devfreq_monitor_resume() - Resume load monitoring of a devfreq instance
 332  * @devfreq:    the devfreq instance.
 333  *
 334  * Helper function to resume devfreq device load monitoing. Function
 335  * to be called from governor in response to DEVFREQ_GOV_RESUME
 336  * event or when polling interval is set to non-zero.
 337  */
 338 void devfreq_monitor_resume(struct devfreq *devfreq)
 339 {
 340         unsigned long freq;
 341
 342         mutex_lock(&devfreq->lock);
 343         if (!devfreq->stop_polling)
 344                 goto out;
 345
 346         if (!delayed_work_pending(&devfreq->work) &&
 347                         devfreq->profile->polling_ms)
 348                 queue_delayed_work(devfreq_wq, &devfreq->work,
 349                         msecs_to_jiffies(devfreq->profile->polling_ms));
 350
 351         devfreq->last_stat_updated = jiffies;
 352         devfreq->stop_polling = false;
 353
 354         if (devfreq->profile->get_cur_freq &&
 355                 !devfreq->profile->get_cur_freq(devfreq->dev.parent, &freq))
 356                 devfreq->previous_freq = freq;
 357
 358 out:
 359         mutex_unlock(&devfreq->lock);
 360 }
 361 EXPORT_SYMBOL(devfreq_monitor_resume);
 362
 363 /**
 364  * devfreq_interval_update() - Update device devfreq monitoring interval
 365  * @devfreq:    the devfreq instance.
 366  * @delay:      new polling interval to be set.
 367  *
 368  * Helper function to set new load monitoring polling interval. Function
 369  * to be called from governor in response to DEVFREQ_GOV_INTERVAL event.
 370  */
 371 void devfreq_interval_update(struct devfreq *devfreq, unsigned int *delay)
 372 {
 373         unsigned int cur_delay = devfreq->profile->polling_ms;
 374         unsigned int new_delay = *delay;
 375
 376         mutex_lock(&devfreq->lock);
 377         devfreq->profile->polling_ms = new_delay;
 378
 379         if (devfreq->stop_polling)
 380                 goto out;
 381
 382         /* if new delay is zero, stop polling */
 383         if (!new_delay) {
 384                 mutex_unlock(&devfreq->lock);
 385                 cancel_delayed_work_sync(&devfreq->work);
 386                 return;
 387         }
 388
 389         /* if current delay is zero, start polling with new delay */
 390         if (!cur_delay) {
 391                 queue_delayed_work(devfreq_wq, &devfreq->work,
 392                         msecs_to_jiffies(devfreq->profile->polling_ms));
 393                 goto out;
 394         }
 395
 396         /* if current delay is greater than new delay, restart polling */
 397         if (cur_delay > new_delay) {
 398                 mutex_unlock(&devfreq->lock);
 399                 cancel_delayed_work_sync(&devfreq->work);
 400                 mutex_lock(&devfreq->lock);
 401                 if (!devfreq->stop_polling)
 402                         queue_delayed_work(devfreq_wq, &devfreq->work,
 403                               msecs_to_jiffies(devfreq->profile->polling_ms));
 404         }
 405 out:
 406         mutex_unlock(&devfreq->lock);
 407 }
 408 EXPORT_SYMBOL(devfreq_interval_update);
 409
 410 /**
 411  * devfreq_notifier_call() - Notify that the device frequency requirements
 412  *                         has been changed out of devfreq framework.
 413  * @nb:         the notifier_block (supposed to be devfreq->nb)
 414  * @type:       not used
 415  * @devp:       not used
 416  *
 417  * Called by a notifier that uses devfreq->nb.
 418  */
 419 static int devfreq_notifier_call(struct notifier_block *nb, unsigned long type,
 420                                  void *devp)
 421 {
 422         struct devfreq *devfreq = container_of(nb, struct devfreq, nb);
 423         int ret;
 424
 425         mutex_lock(&devfreq->lock);
 426         ret = update_devfreq(devfreq);
 427         mutex_unlock(&devfreq->lock);
 428
 429         return ret;
 430 }
 431
 432 /**
 433  * _remove_devfreq() - Remove devfreq from the list and release its resources.
 434  * @devfreq:    the devfreq struct
 435  */
 436 static void _remove_devfreq(struct devfreq *devfreq)
 437 {
 438         mutex_lock(&devfreq_list_lock);
 439         if (IS_ERR(find_device_devfreq(devfreq->dev.parent))) {
 440                 mutex_unlock(&devfreq_list_lock);
 441                 dev_warn(&devfreq->dev, "releasing devfreq which doesn't exist\n");
 442                 return;
 443         }
 444         list_del(&devfreq->node);
 445         mutex_unlock(&devfreq_list_lock);
 446
 447         if (devfreq->governor)
 448                 devfreq->governor->event_handler(devfreq,
 449                                                  DEVFREQ_GOV_STOP, NULL);
 450
 451         if (devfreq->profile->exit)
 452                 devfreq->profile->exit(devfreq->dev.parent);
 453
 454         mutex_destroy(&devfreq->lock);
 455         kfree(devfreq);
 456 }
 457
 458 /**
 459  * devfreq_dev_release() - Callback for struct device to release the device.
 460  * @dev:        the devfreq device
 461  *
 462  * This calls _remove_devfreq() if _remove_devfreq() is not called.
 463  */
 464 static void devfreq_dev_release(struct device *dev)
 465 {
 466         struct devfreq *devfreq = to_devfreq(dev);
 467
 468         _remove_devfreq(devfreq);
 469 }
 470
 471 /**
 472  * devfreq_add_device() - Add devfreq feature to the device
 473  * @dev:        the device to add devfreq feature.
 474  * @profile:    device-specific profile to run devfreq.
 475  * @governor_name:      name of the policy to choose frequency.
 476  * @data:       private data for the governor. The devfreq framework does not
 477  *              touch this value.
 478  */
 479 struct devfreq *devfreq_add_device(struct device *dev,
 480                                    struct devfreq_dev_profile *profile,
 481                                    const char *governor_name,
 482                                    void *data)
 483 {
 484         struct devfreq *devfreq;
 485         struct devfreq_governor *governor;
 486         int err = 0;
 487
 488         if (!dev || !profile || !governor_name) {
 489                 dev_err(dev, "%s: Invalid parameters.\n", __func__);
 490                 return ERR_PTR(-EINVAL);
 491         }
 492
 493         mutex_lock(&devfreq_list_lock);
 494         devfreq = find_device_devfreq(dev);
 495         mutex_unlock(&devfreq_list_lock);
 496         if (!IS_ERR(devfreq)) {
 497                 dev_err(dev, "%s: Unable to create devfreq for the device. It already has one.\n", __func__);
 498                 err = -EINVAL;
 499                 goto err_out;
 500         }
 501
 502         devfreq = kzalloc(sizeof(struct devfreq), GFP_KERNEL);
 503         if (!devfreq) {
 504                 dev_err(dev, "%s: Unable to create devfreq for the device\n",
 505                         __func__);
 506                 err = -ENOMEM;
 507                 goto err_out;
 508         }
 509
 510         mutex_init(&devfreq->lock);
 511         mutex_lock(&devfreq->lock);
 512         devfreq->dev.parent = dev;
 513         devfreq->dev.class = devfreq_class;
 514         devfreq->dev.release = devfreq_dev_release;
 515         devfreq->profile = profile;
 516         strncpy(devfreq->governor_name, governor_name, DEVFREQ_NAME_LEN);
 517         devfreq->previous_freq = profile->initial_freq;
 518         devfreq->data = data;
 519         devfreq->nb.notifier_call = devfreq_notifier_call;
 520
 521         if (!devfreq->profile->max_state && !devfreq->profile->freq_table) {
 522                 mutex_unlock(&devfreq->lock);
 523                 devfreq_set_freq_table(devfreq);
 524                 mutex_lock(&devfreq->lock);
 525         }
 526
 527         devfreq->trans_table =  devm_kzalloc(dev, sizeof(unsigned int) *
 528                                                 devfreq->profile->max_state *
 529                                                 devfreq->profile->max_state,
 530                                                 GFP_KERNEL);
 531         devfreq->time_in_state = devm_kzalloc(dev, sizeof(unsigned long) *
 532                                                 devfreq->profile->max_state,
 533                                                 GFP_KERNEL);
 534         devfreq->last_stat_updated = jiffies;
 535
 536         dev_set_name(&devfreq->dev, "%s", dev_name(dev));
 537         err = device_register(&devfreq->dev);
 538         if (err) {
 539                 put_device(&devfreq->dev);
 540                 mutex_unlock(&devfreq->lock);
 541                 goto err_out;
 542         }
 543
 544         mutex_unlock(&devfreq->lock);
 545
 546         mutex_lock(&devfreq_list_lock);
 547         list_add(&devfreq->node, &devfreq_list);
 548
 549         governor = find_devfreq_governor(devfreq->governor_name);
 550         if (!IS_ERR(governor))
 551                 devfreq->governor = governor;
 552         if (devfreq->governor)
 553                 err = devfreq->governor->event_handler(devfreq,
 554                                         DEVFREQ_GOV_START, NULL);
 555         mutex_unlock(&devfreq_list_lock);
 556         if (err) {
 557                 dev_err(dev, "%s: Unable to start governor for the device\n",
 558                         __func__);
 559                 goto err_init;
 560         }
 561
 562         return devfreq;
 563
 564 err_init:
 565         list_del(&devfreq->node);
 566         device_unregister(&devfreq->dev);
 567         kfree(devfreq);
 568 err_out:
 569         return ERR_PTR(err);
 570 }
 571 EXPORT_SYMBOL(devfreq_add_device);
 572
 573 /**
 574  * devfreq_remove_device() - Remove devfreq feature from a device.
 575  * @devfreq:    the devfreq instance to be removed
 576  *
 577  * The opposite of devfreq_add_device().
 578  */
 579 int devfreq_remove_device(struct devfreq *devfreq)
 580 {
 581         if (!devfreq)
 582                 return -EINVAL;
 583
 584         device_unregister(&devfreq->dev);
 585         put_device(&devfreq->dev);
 586
 587         return 0;
 588 }
 589 EXPORT_SYMBOL(devfreq_remove_device);
 590
 591 static int devm_devfreq_dev_match(struct device *dev, void *res, void *data)
 592 {
 593         struct devfreq **r = res;
 594
 595         if (WARN_ON(!r || !*r))
 596                 return 0;
 597
 598         return *r == data;
 599 }
 600
 601 static void devm_devfreq_dev_release(struct device *dev, void *res)
 602 {
 603         devfreq_remove_device(*(struct devfreq **)res);
 604 }
 605
 606 /**
 607  * devm_devfreq_add_device() - Resource-managed devfreq_add_device()
 608  * @dev:        the device to add devfreq feature.
 609  * @profile:    device-specific profile to run devfreq.
 610  * @governor_name:      name of the policy to choose frequency.
 611  * @data:       private data for the governor. The devfreq framework does not
 612  *              touch this value.
 613  *
 614  * This function manages automatically the memory of devfreq device using device
 615  * resource management and simplify the free operation for memory of devfreq
 616  * device.
 617  */
 618 struct devfreq *devm_devfreq_add_device(struct device *dev,
 619                                         struct devfreq_dev_profile *profile,
 620                                         const char *governor_name,
 621                                         void *data)
 622 {
 623         struct devfreq **ptr, *devfreq;
 624
 625         ptr = devres_alloc(devm_devfreq_dev_release, sizeof(*ptr), GFP_KERNEL);
 626         if (!ptr)
 627                 return ERR_PTR(-ENOMEM);
 628
 629         devfreq = devfreq_add_device(dev, profile, governor_name, data);
 630         if (IS_ERR(devfreq)) {
 631                 devres_free(ptr);
 632                 return ERR_PTR(-ENOMEM);
 633         }
 634
 635         *ptr = devfreq;
 636         devres_add(dev, ptr);
 637
 638         return devfreq;
 639 }
 640 EXPORT_SYMBOL(devm_devfreq_add_device);
 641
 642 /**
 643  * devm_devfreq_remove_device() - Resource-managed devfreq_remove_device()
 644  * @dev:        the device to add devfreq feature.
 645  * @devfreq:    the devfreq instance to be removed
 646  */
 647 void devm_devfreq_remove_device(struct device *dev, struct devfreq *devfreq)
 648 {
 649         WARN_ON(devres_release(dev, devm_devfreq_dev_release,
 650                                devm_devfreq_dev_match, devfreq));
 651 }
 652 EXPORT_SYMBOL(devm_devfreq_remove_device);
 653
 654 /**
 655  * devfreq_suspend_device() - Suspend devfreq of a device.
 656  * @devfreq: the devfreq instance to be suspended
 657  *
 658  * This function is intended to be called by the pm callbacks
 659  * (e.g., runtime_suspend, suspend) of the device driver that
 660  * holds the devfreq.
 661  */
 662 int devfreq_suspend_device(struct devfreq *devfreq)
 663 {
 664         if (!devfreq)
 665                 return -EINVAL;
 666
 667         if (!devfreq->governor)
 668                 return 0;
 669
 670         return devfreq->governor->event_handler(devfreq,
 671                                 DEVFREQ_GOV_SUSPEND, NULL);
 672 }
 673 EXPORT_SYMBOL(devfreq_suspend_device);
 674
 675 /**
 676  * devfreq_resume_device() - Resume devfreq of a device.
 677  * @devfreq: the devfreq instance to be resumed
 678  *
 679  * This function is intended to be called by the pm callbacks
 680  * (e.g., runtime_resume, resume) of the device driver that
 681  * holds the devfreq.
 682  */
 683 int devfreq_resume_device(struct devfreq *devfreq)
 684 {
 685         if (!devfreq)
 686                 return -EINVAL;
 687
 688         if (!devfreq->governor)
 689                 return 0;
 690
 691         return devfreq->governor->event_handler(devfreq,
 692                                 DEVFREQ_GOV_RESUME, NULL);
 693 }
 694 EXPORT_SYMBOL(devfreq_resume_device);
 695
 696 /**
 697  * devfreq_add_governor() - Add devfreq governor
 698  * @governor:   the devfreq governor to be added
 699  */
 700 int devfreq_add_governor(struct devfreq_governor *governor)
 701 {
 702         struct devfreq_governor *g;
 703         struct devfreq *devfreq;
 704         int err = 0;
 705
 706         if (!governor) {
 707                 pr_err("%s: Invalid parameters.\n", __func__);
 708                 return -EINVAL;
 709         }
 710
 711         mutex_lock(&devfreq_list_lock);
 712         g = find_devfreq_governor(governor->name);
 713         if (!IS_ERR(g)) {
 714                 pr_err("%s: governor %s already registered\n", __func__,
 715                        g->name);
 716                 err = -EINVAL;
 717                 goto err_out;
 718         }
 719
 720         list_add(&governor->node, &devfreq_governor_list);
 721
 722         list_for_each_entry(devfreq, &devfreq_list, node) {
 723                 int ret = 0;
 724                 struct device *dev = devfreq->dev.parent;
 725
 726                 if (!strncmp(devfreq->governor_name, governor->name,
 727                              DEVFREQ_NAME_LEN)) {
 728                         /* The following should never occur */
 729                         if (devfreq->governor) {
 730                                 dev_warn(dev,
 731                                          "%s: Governor %s already present\n",
 732                                          __func__, devfreq->governor->name);
 733                                 ret = devfreq->governor->event_handler(devfreq,
 734                                                         DEVFREQ_GOV_STOP, NULL);
 735                                 if (ret) {
 736                                         dev_warn(dev,
 737                                                  "%s: Governor %s stop = %d\n",
 738                                                  __func__,
 739                                                  devfreq->governor->name, ret);
 740                                 }
 741                                 /* Fall through */
 742                         }
 743                         devfreq->governor = governor;
 744                         ret = devfreq->governor->event_handler(devfreq,
 745                                                 DEVFREQ_GOV_START, NULL);
 746                         if (ret) {
 747                                 dev_warn(dev, "%s: Governor %s start=%d\n",
 748                                          __func__, devfreq->governor->name,
 749                                          ret);
 750                         }
 751                 }
 752         }
 753
 754 err_out:
 755         mutex_unlock(&devfreq_list_lock);
 756
 757         return err;
 758 }
 759 EXPORT_SYMBOL(devfreq_add_governor);
 760
 761 /**
 762  * devfreq_remove_device() - Remove devfreq feature from a device.
 763  * @governor:   the devfreq governor to be removed
 764  */
 765 int devfreq_remove_governor(struct devfreq_governor *governor)
 766 {
 767         struct devfreq_governor *g;
 768         struct devfreq *devfreq;
 769         int err = 0;
 770
 771         if (!governor) {
 772                 pr_err("%s: Invalid parameters.\n", __func__);
 773                 return -EINVAL;
 774         }
 775
 776         mutex_lock(&devfreq_list_lock);
 777         g = find_devfreq_governor(governor->name);
 778         if (IS_ERR(g)) {
 779                 pr_err("%s: governor %s not registered\n", __func__,
 780                        governor->name);
 781                 err = PTR_ERR(g);
 782                 goto err_out;
 783         }
 784         list_for_each_entry(devfreq, &devfreq_list, node) {
 785                 int ret;
 786                 struct device *dev = devfreq->dev.parent;
 787
 788                 if (!strncmp(devfreq->governor_name, governor->name,
 789                              DEVFREQ_NAME_LEN)) {
 790                         /* we should have a devfreq governor! */
 791                         if (!devfreq->governor) {
 792                                 dev_warn(dev, "%s: Governor %s NOT present\n",
 793                                          __func__, governor->name);
 794                                 continue;
 795                                 /* Fall through */
 796                         }
 797                         ret = devfreq->governor->event_handler(devfreq,
 798                                                 DEVFREQ_GOV_STOP, NULL);
 799                         if (ret) {
 800                                 dev_warn(dev, "%s: Governor %s stop=%d\n",
 801                                          __func__, devfreq->governor->name,
 802                                          ret);
 803                         }
 804                         devfreq->governor = NULL;
 805                 }
 806         }
 807
 808         list_del(&governor->node);
 809 err_out:
 810         mutex_unlock(&devfreq_list_lock);
 811
 812         return err;
 813 }
 814 EXPORT_SYMBOL(devfreq_remove_governor);
 815
 816 static ssize_t governor_show(struct device *dev,
 817                              struct device_attribute *attr, char *buf)
 818 {
 819         if (!to_devfreq(dev)->governor)
 820                 return -EINVAL;
 821
 822         return sprintf(buf, "%s\n", to_devfreq(dev)->governor->name);
 823 }
 824
 825 static ssize_t governor_store(struct device *dev, struct device_attribute *attr,
 826                               const char *buf, size_t count)
 827 {
 828         struct devfreq *df = to_devfreq(dev);
 829         int ret;
 830         char str_governor[DEVFREQ_NAME_LEN + 1];
 831         struct devfreq_governor *governor;
 832
 833         ret = sscanf(buf, "%" __stringify(DEVFREQ_NAME_LEN) "s", str_governor);
 834         if (ret != 1)
 835                 return -EINVAL;
 836
 837         mutex_lock(&devfreq_list_lock);
 838         governor = find_devfreq_governor(str_governor);
 839         if (IS_ERR(governor)) {
 840                 ret = PTR_ERR(governor);
 841                 goto out;
 842         }
 843         if (df->governor == governor) {
 844                 ret = 0;
 845                 goto out;
 846         }
 847
 848         if (df->governor) {
 849                 ret = df->governor->event_handler(df, DEVFREQ_GOV_STOP, NULL);
 850                 if (ret) {
 851                         dev_warn(dev, "%s: Governor %s not stopped(%d)\n",
 852                                  __func__, df->governor->name, ret);
 853                         goto out;
 854                 }
 855         }
 856         df->governor = governor;
 857         strncpy(df->governor_name, governor->name, DEVFREQ_NAME_LEN);
 858         ret = df->governor->event_handler(df, DEVFREQ_GOV_START, NULL);
 859         if (ret)
 860                 dev_warn(dev, "%s: Governor %s not started(%d)\n",
 861                          __func__, df->governor->name, ret);
 862 out:
 863         mutex_unlock(&devfreq_list_lock);
 864
 865         if (!ret)
 866                 ret = count;
 867         return ret;
 868 }
 869 static DEVICE_ATTR_RW(governor);
 870
 871 static ssize_t available_governors_show(struct device *d,
 872                                         struct device_attribute *attr,
 873                                         char *buf)
 874 {
 875         struct devfreq_governor *tmp_governor;
 876         ssize_t count = 0;
 877
 878         mutex_lock(&devfreq_list_lock);
 879         list_for_each_entry(tmp_governor, &devfreq_governor_list, node)
 880                 count += scnprintf(&buf[count], (PAGE_SIZE - count - 2),
 881                                    "%s ", tmp_governor->name);
 882         mutex_unlock(&devfreq_list_lock);
 883
 884         /* Truncate the trailing space */
 885         if (count)
 886                 count--;
 887
 888         count += sprintf(&buf[count], "\n");
 889
 890         return count;
 891 }
 892 static DEVICE_ATTR_RO(available_governors);
 893
 894 static ssize_t cur_freq_show(struct device *dev, struct device_attribute *attr,
 895                              char *buf)
 896 {
 897         unsigned long freq;
 898         struct devfreq *devfreq = to_devfreq(dev);
 899
 900         if (devfreq->profile->get_cur_freq &&
 901                 !devfreq->profile->get_cur_freq(devfreq->dev.parent, &freq))
 902                         return sprintf(buf, "%lu\n", freq);
 903
 904         return sprintf(buf, "%lu\n", devfreq->previous_freq);
 905 }
 906 static DEVICE_ATTR_RO(cur_freq);
 907
 908 static ssize_t target_freq_show(struct device *dev,
 909                                 struct device_attribute *attr, char *buf)
 910 {
 911         return sprintf(buf, "%lu\n", to_devfreq(dev)->previous_freq);
 912 }
 913 static DEVICE_ATTR_RO(target_freq);
 914
 915 static ssize_t polling_interval_show(struct device *dev,
 916                                      struct device_attribute *attr, char *buf)
 917 {
 918         return sprintf(buf, "%d\n", to_devfreq(dev)->profile->polling_ms);
 919 }
 920
 921 static ssize_t polling_interval_store(struct device *dev,
 922                                       struct device_attribute *attr,
 923                                       const char *buf, size_t count)
 924 {
 925         struct devfreq *df = to_devfreq(dev);
 926         unsigned int value;
 927         int ret;
 928
 929         if (!df->governor)
 930                 return -EINVAL;
 931
 932         ret = sscanf(buf, "%u", &value);
 933         if (ret != 1)
 934                 return -EINVAL;
 935
 936         df->governor->event_handler(df, DEVFREQ_GOV_INTERVAL, &value);
 937         ret = count;
 938
 939         return ret;
 940 }
 941 static DEVICE_ATTR_RW(polling_interval);
 942
 943 static ssize_t min_freq_store(struct device *dev, struct device_attribute *attr,
 944                               const char *buf, size_t count)
 945 {
 946         struct devfreq *df = to_devfreq(dev);
 947         unsigned long value;
 948         int ret;
 949         unsigned long max;
 950
 951         ret = sscanf(buf, "%lu", &value);
 952         if (ret != 1)
 953                 return -EINVAL;
 954
 955         mutex_lock(&df->lock);
 956         max = df->max_freq;
 957         if (value && max && value > max) {
 958                 ret = -EINVAL;
 959                 goto unlock;
 960         }
 961
 962         df->min_freq = value;
 963         update_devfreq(df);
 964         ret = count;
 965 unlock:
 966         mutex_unlock(&df->lock);
 967         return ret;
 968 }
 969
 970 static ssize_t max_freq_store(struct device *dev, struct device_attribute *attr,
 971                               const char *buf, size_t count)
 972 {
 973         struct devfreq *df = to_devfreq(dev);
 974         unsigned long value;
 975         int ret;
 976         unsigned long min;
 977
 978         ret = sscanf(buf, "%lu", &value);
 979         if (ret != 1)
 980                 return -EINVAL;
 981
 982         mutex_lock(&df->lock);
 983         min = df->min_freq;
 984         if (value && min && value < min) {
 985                 ret = -EINVAL;
 986                 goto unlock;
 987         }
 988
 989         df->max_freq = value;
 990         update_devfreq(df);
 991         ret = count;
 992 unlock:
 993         mutex_unlock(&df->lock);
 994         return ret;
 995 }
 996
 997 #define show_one(name)                                          \
 998 static ssize_t name##_show                                      \
 999 (struct device *dev, struct device_attribute *attr, char *buf)  \
1000 {                                                               \
1001         return sprintf(buf, "%lu\n", to_devfreq(dev)->name);    \
1002 }
1003 show_one(min_freq);
1004 show_one(max_freq);
1005
1006 static DEVICE_ATTR_RW(min_freq);
1007 static DEVICE_ATTR_RW(max_freq);
1008
1009 static ssize_t available_frequencies_show(struct device *d,
1010                                           struct device_attribute *attr,
1011                                           char *buf)
1012 {
1013         struct devfreq *df = to_devfreq(d);
1014         struct device *dev = df->dev.parent;
1015         struct dev_pm_opp *opp;
1016         ssize_t count = 0;
1017         unsigned long freq = 0;
1018
1019         rcu_read_lock();
1020         do {
1021                 opp = dev_pm_opp_find_freq_ceil(dev, &freq);
1022                 if (IS_ERR(opp))
1023                         break;
1024
1025                 count += scnprintf(&buf[count], (PAGE_SIZE - count - 2),
1026                                    "%lu ", freq);
1027                 freq++;
1028         } while (1);
1029         rcu_read_unlock();
1030
1031         /* Truncate the trailing space */
1032         if (count)
1033                 count--;
1034
1035         count += sprintf(&buf[count], "\n");
1036
1037         return count;
1038 }
1039 static DEVICE_ATTR_RO(available_frequencies);
1040
1041 static ssize_t trans_stat_show(struct device *dev,
1042                                struct device_attribute *attr, char *buf)
1043 {
1044         struct devfreq *devfreq = to_devfreq(dev);
1045         ssize_t len;
1046         int i, j;
1047         unsigned int max_state = devfreq->profile->max_state;
1048
1049         if (!devfreq->stop_polling &&
1050                         devfreq_update_status(devfreq, devfreq->previous_freq))
1051                 return 0;
1052         if (max_state == 0)
1053                 return sprintf(buf, "Not Supported.\n");
1054
1055         len = sprintf(buf, "     From  :   To\n");
1056         len += sprintf(buf + len, "           :");
1057         for (i = 0; i < max_state; i++)
1058                 len += sprintf(buf + len, "%10lu",
1059                                 devfreq->profile->freq_table[i]);
1060
1061         len += sprintf(buf + len, "   time(ms)\n");
1062
1063         for (i = 0; i < max_state; i++) {
1064                 if (devfreq->profile->freq_table[i]
1065                                         == devfreq->previous_freq) {
1066                         len += sprintf(buf + len, "*");
1067                 } else {
1068                         len += sprintf(buf + len, " ");
1069                 }
1070                 len += sprintf(buf + len, "%10lu:",
1071                                 devfreq->profile->freq_table[i]);
1072                 for (j = 0; j < max_state; j++)
1073                         len += sprintf(buf + len, "%10u",
1074                                 devfreq->trans_table[(i * max_state) + j]);
1075                 len += sprintf(buf + len, "%10u\n",
1076                         jiffies_to_msecs(devfreq->time_in_state[i]));
1077         }
1078
1079         len += sprintf(buf + len, "Total transition : %u\n",
1080                                         devfreq->total_trans);
1081         return len;
1082 }
1083 static DEVICE_ATTR_RO(trans_stat);
1084
1085 static struct attribute *devfreq_attrs[] = {
1086         &dev_attr_governor.attr,
1087         &dev_attr_available_governors.attr,
1088         &dev_attr_cur_freq.attr,
1089         &dev_attr_available_frequencies.attr,
1090         &dev_attr_target_freq.attr,
1091         &dev_attr_polling_interval.attr,
1092         &dev_attr_min_freq.attr,
1093         &dev_attr_max_freq.attr,
1094         &dev_attr_trans_stat.attr,
1095         NULL,
1096 };
1097 ATTRIBUTE_GROUPS(devfreq);
1098
1099 static int __init devfreq_init(void)
1100 {
1101         devfreq_class = class_create(THIS_MODULE, "devfreq");
1102         if (IS_ERR(devfreq_class)) {
1103                 pr_err("%s: couldn't create class\n", __FILE__);
1104                 return PTR_ERR(devfreq_class);
1105         }
1106
1107         devfreq_wq = create_freezable_workqueue("devfreq_wq");
1108         if (!devfreq_wq) {
1109                 class_destroy(devfreq_class);
1110                 pr_err("%s: couldn't create workqueue\n", __FILE__);
1111                 return -ENOMEM;
1112         }
1113         devfreq_class->dev_groups = devfreq_groups;
1114
1115         return 0;
1116 }
1117 subsys_initcall(devfreq_init);
1118
1119 static void __exit devfreq_exit(void)
1120 {
1121         class_destroy(devfreq_class);
1122         destroy_workqueue(devfreq_wq);
1123 }
1124 module_exit(devfreq_exit);
1125
1126 /*
1127  * The followings are helper functions for devfreq user device drivers with
1128  * OPP framework.
1129  */
1130
1131 /**
1132  * devfreq_recommended_opp() - Helper function to get proper OPP for the
1133  *                           freq value given to target callback.
1134  * @dev:        The devfreq user device. (parent of devfreq)
1135  * @freq:       The frequency given to target function
1136  * @flags:      Flags handed from devfreq framework.
1137  *
1138  * Locking: This function must be called under rcu_read_lock(). opp is a rcu
1139  * protected pointer. The reason for the same is that the opp pointer which is
1140  * returned will remain valid for use with opp_get_{voltage, freq} only while
1141  * under the locked area. The pointer returned must be used prior to unlocking
1142  * with rcu_read_unlock() to maintain the integrity of the pointer.
1143  */
1144 struct dev_pm_opp *devfreq_recommended_opp(struct device *dev,
1145                                            unsigned long *freq,
1146                                            u32 flags)
1147 {
1148         struct dev_pm_opp *opp;
1149
1150         if (flags & DEVFREQ_FLAG_LEAST_UPPER_BOUND) {
1151                 /* The freq is an upper bound. opp should be lower */
1152                 opp = dev_pm_opp_find_freq_floor(dev, freq);
1153
1154                 /* If not available, use the closest opp */
1155                 if (opp == ERR_PTR(-ERANGE))
1156                         opp = dev_pm_opp_find_freq_ceil(dev, freq);
1157         } else {
1158                 /* The freq is an lower bound. opp should be higher */
1159                 opp = dev_pm_opp_find_freq_ceil(dev, freq);
1160
1161                 /* If not available, use the closest opp */
1162                 if (opp == ERR_PTR(-ERANGE))
1163                         opp = dev_pm_opp_find_freq_floor(dev, freq);
1164         }
1165
1166         return opp;
1167 }
1168 EXPORT_SYMBOL(devfreq_recommended_opp);
1169
1170 /**
1171  * devfreq_register_opp_notifier() - Helper function to get devfreq notified
1172  *                                 for any changes in the OPP availability
1173  *                                 changes
1174  * @dev:        The devfreq user device. (parent of devfreq)
1175  * @devfreq:    The devfreq object.
1176  */
1177 int devfreq_register_opp_notifier(struct device *dev, struct devfreq *devfreq)
1178 {
1179         struct srcu_notifier_head *nh;
1180         int ret = 0;
1181
1182         rcu_read_lock();
1183         nh = dev_pm_opp_get_notifier(dev);
1184         if (IS_ERR(nh))
1185                 ret = PTR_ERR(nh);
1186         rcu_read_unlock();
1187         if (!ret)
1188                 ret = srcu_notifier_chain_register(nh, &devfreq->nb);
1189
1190         return ret;
1191 }
1192 EXPORT_SYMBOL(devfreq_register_opp_notifier);
1193
1194 /**
1195  * devfreq_unregister_opp_notifier() - Helper function to stop getting devfreq
1196  *                                   notified for any changes in the OPP
1197  *                                   availability changes anymore.
1198  * @dev:        The devfreq user device. (parent of devfreq)
1199  * @devfreq:    The devfreq object.
1200  *
1201  * At exit() callback of devfreq_dev_profile, this must be included if
1202  * devfreq_recommended_opp is used.
1203  */
1204 int devfreq_unregister_opp_notifier(struct device *dev, struct devfreq *devfreq)
1205 {
1206         struct srcu_notifier_head *nh;
1207         int ret = 0;
1208
1209         rcu_read_lock();
1210         nh = dev_pm_opp_get_notifier(dev);
1211         if (IS_ERR(nh))
1212                 ret = PTR_ERR(nh);
1213         rcu_read_unlock();
1214         if (!ret)
1215                 ret = srcu_notifier_chain_unregister(nh, &devfreq->nb);
1216
1217         return ret;
1218 }
1219 EXPORT_SYMBOL(devfreq_unregister_opp_notifier);
1220
1221 static void devm_devfreq_opp_release(struct device *dev, void *res)
1222 {
1223         devfreq_unregister_opp_notifier(dev, *(struct devfreq **)res);
1224 }
1225
1226 /**
1227  * devm_ devfreq_register_opp_notifier()
1228  *              - Resource-managed devfreq_register_opp_notifier()
1229  * @dev:        The devfreq user device. (parent of devfreq)
1230  * @devfreq:    The devfreq object.
1231  */
1232 int devm_devfreq_register_opp_notifier(struct device *dev,
1233                                        struct devfreq *devfreq)
1234 {
1235         struct devfreq **ptr;
1236         int ret;
1237
1238         ptr = devres_alloc(devm_devfreq_opp_release, sizeof(*ptr), GFP_KERNEL);
1239         if (!ptr)
1240                 return -ENOMEM;
1241
1242         ret = devfreq_register_opp_notifier(dev, devfreq);
1243         if (ret) {
1244                 devres_free(ptr);
1245                 return ret;
1246         }
1247
1248         *ptr = devfreq;
1249         devres_add(dev, ptr);
1250
1251         return 0;
1252 }
1253 EXPORT_SYMBOL(devm_devfreq_register_opp_notifier);
1254
1255 /**
1256  * devm_devfreq_unregister_opp_notifier()
1257  *              - Resource-managed devfreq_unregister_opp_notifier()
1258  * @dev:        The devfreq user device. (parent of devfreq)
1259  * @devfreq:    The devfreq object.
1260  */
1261 void devm_devfreq_unregister_opp_notifier(struct device *dev,
1262                                          struct devfreq *devfreq)
1263 {
1264         WARN_ON(devres_release(dev, devm_devfreq_opp_release,
1265                                devm_devfreq_dev_match, devfreq));
1266 }
1267 EXPORT_SYMBOL(devm_devfreq_unregister_opp_notifier);
1268
1269 MODULE_AUTHOR("MyungJoo Ham <myungjoo.ham@samsung.com>");
1270 MODULE_DESCRIPTION("devfreq class support");
1271 MODULE_LICENSE("GPL");