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