drivers/devfreq/devfreq.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * devfreq: Generic Dynamic Voltage and Frequency Scaling (DVFS) Framework
   4  *          for Non-CPU Devices.
   5  *
   6  * Copyright (C) 2011 Samsung Electronics
   7  *      MyungJoo Ham <[email protected]>
   8  */
   9
  10 #include <linux/kernel.h>
  11 #include <linux/kmod.h>
  12 #include <linux/sched.h>
  13 #include <linux/debugfs.h>
  14 #include <linux/errno.h>
  15 #include <linux/err.h>
  16 #include <linux/init.h>
  17 #include <linux/export.h>
  18 #include <linux/slab.h>
  19 #include <linux/stat.h>
  20 #include <linux/pm_opp.h>
  21 #include <linux/devfreq.h>
  22 #include <linux/workqueue.h>
  23 #include <linux/platform_device.h>
  24 #include <linux/list.h>
  25 #include <linux/printk.h>
  26 #include <linux/hrtimer.h>
  27 #include <linux/of.h>
  28 #include <linux/pm_qos.h>
  29 #include "governor.h"
  30
  31 #define CREATE_TRACE_POINTS
  32 #include <trace/events/devfreq.h>
  33
  34 #define HZ_PER_KHZ      1000
  35
  36 static struct class *devfreq_class;
  37 static struct dentry *devfreq_debugfs;
  38
  39 /*
  40  * devfreq core provides delayed work based load monitoring helper
  41  * functions. Governors can use these or can implement their own
  42  * monitoring mechanism.
  43  */
  44 static struct workqueue_struct *devfreq_wq;
  45
  46 /* The list of all device-devfreq governors */
  47 static LIST_HEAD(devfreq_governor_list);
  48 /* The list of all device-devfreq */
  49 static LIST_HEAD(devfreq_list);
  50 static DEFINE_MUTEX(devfreq_list_lock);
  51
  52 static const char timer_name[][DEVFREQ_NAME_LEN] = {
  53         [DEVFREQ_TIMER_DEFERRABLE] = { "deferrable" },
  54         [DEVFREQ_TIMER_DELAYED] = { "delayed" },
  55 };
  56
  57 /**
  58  * find_device_devfreq() - find devfreq struct using device pointer
  59  * @dev:        device pointer used to lookup device devfreq.
  60  *
  61  * Search the list of device devfreqs and return the matched device's
  62  * devfreq info. devfreq_list_lock should be held by the caller.
  63  */
  64 static struct devfreq *find_device_devfreq(struct device *dev)
  65 {
  66         struct devfreq *tmp_devfreq;
  67
  68         lockdep_assert_held(&devfreq_list_lock);
  69
  70         if (IS_ERR_OR_NULL(dev)) {
  71                 pr_err("DEVFREQ: %s: Invalid parameters\n", __func__);
  72                 return ERR_PTR(-EINVAL);
  73         }
  74
  75         list_for_each_entry(tmp_devfreq, &devfreq_list, node) {
  76                 if (tmp_devfreq->dev.parent == dev)
  77                         return tmp_devfreq;
  78         }
  79
  80         return ERR_PTR(-ENODEV);
  81 }
  82
  83 static unsigned long find_available_min_freq(struct devfreq *devfreq)
  84 {
  85         struct dev_pm_opp *opp;
  86         unsigned long min_freq = 0;
  87
  88         opp = dev_pm_opp_find_freq_ceil(devfreq->dev.parent, &min_freq);
  89         if (IS_ERR(opp))
  90                 min_freq = 0;
  91         else
  92                 dev_pm_opp_put(opp);
  93
  94         return min_freq;
  95 }
  96
  97 static unsigned long find_available_max_freq(struct devfreq *devfreq)
  98 {
  99         struct dev_pm_opp *opp;
 100         unsigned long max_freq = ULONG_MAX;
 101
 102         opp = dev_pm_opp_find_freq_floor(devfreq->dev.parent, &max_freq);
 103         if (IS_ERR(opp))
 104                 max_freq = 0;
 105         else
 106                 dev_pm_opp_put(opp);
 107
 108         return max_freq;
 109 }
 110
 111 /**
 112  * get_freq_range() - Get the current freq range
 113  * @devfreq:    the devfreq instance
 114  * @min_freq:   the min frequency
 115  * @max_freq:   the max frequency
 116  *
 117  * This takes into consideration all constraints.
 118  */
 119 static void get_freq_range(struct devfreq *devfreq,
 120                            unsigned long *min_freq,
 121                            unsigned long *max_freq)
 122 {
 123         unsigned long *freq_table = devfreq->profile->freq_table;
 124         s32 qos_min_freq, qos_max_freq;
 125
 126         lockdep_assert_held(&devfreq->lock);
 127
 128         /*
 129          * Initialize minimum/maximum frequency from freq table.
 130          * The devfreq drivers can initialize this in either ascending or
 131          * descending order and devfreq core supports both.
 132          */
 133         if (freq_table[0] < freq_table[devfreq->profile->max_state - 1]) {
 134                 *min_freq = freq_table[0];
 135                 *max_freq = freq_table[devfreq->profile->max_state - 1];
 136         } else {
 137                 *min_freq = freq_table[devfreq->profile->max_state - 1];
 138                 *max_freq = freq_table[0];
 139         }
 140
 141         /* Apply constraints from PM QoS */
 142         qos_min_freq = dev_pm_qos_read_value(devfreq->dev.parent,
 143                                              DEV_PM_QOS_MIN_FREQUENCY);
 144         qos_max_freq = dev_pm_qos_read_value(devfreq->dev.parent,
 145                                              DEV_PM_QOS_MAX_FREQUENCY);
 146         *min_freq = max(*min_freq, (unsigned long)HZ_PER_KHZ * qos_min_freq);
 147         if (qos_max_freq != PM_QOS_MAX_FREQUENCY_DEFAULT_VALUE)
 148                 *max_freq = min(*max_freq,
 149                                 (unsigned long)HZ_PER_KHZ * qos_max_freq);
 150
 151         /* Apply constraints from OPP interface */
 152         *min_freq = max(*min_freq, devfreq->scaling_min_freq);
 153         *max_freq = min(*max_freq, devfreq->scaling_max_freq);
 154
 155         if (*min_freq > *max_freq)
 156                 *min_freq = *max_freq;
 157 }
 158
 159 /**
 160  * devfreq_get_freq_level() - Lookup freq_table for the frequency
 161  * @devfreq:    the devfreq instance
 162  * @freq:       the target frequency
 163  */
 164 static int devfreq_get_freq_level(struct devfreq *devfreq, unsigned long freq)
 165 {
 166         int lev;
 167
 168         for (lev = 0; lev < devfreq->profile->max_state; lev++)
 169                 if (freq == devfreq->profile->freq_table[lev])
 170                         return lev;
 171
 172         return -EINVAL;
 173 }
 174
 175 static int set_freq_table(struct devfreq *devfreq)
 176 {
 177         struct devfreq_dev_profile *profile = devfreq->profile;
 178         struct dev_pm_opp *opp;
 179         unsigned long freq;
 180         int i, count;
 181
 182         /* Initialize the freq_table from OPP table */
 183         count = dev_pm_opp_get_opp_count(devfreq->dev.parent);
 184         if (count <= 0)
 185                 return -EINVAL;
 186
 187         profile->max_state = count;
 188         profile->freq_table = devm_kcalloc(devfreq->dev.parent,
 189                                         profile->max_state,
 190                                         sizeof(*profile->freq_table),
 191                                         GFP_KERNEL);
 192         if (!profile->freq_table) {
 193                 profile->max_state = 0;
 194                 return -ENOMEM;
 195         }
 196
 197         for (i = 0, freq = 0; i < profile->max_state; i++, freq++) {
 198                 opp = dev_pm_opp_find_freq_ceil(devfreq->dev.parent, &freq);
 199                 if (IS_ERR(opp)) {
 200                         devm_kfree(devfreq->dev.parent, profile->freq_table);
 201                         profile->max_state = 0;
 202                         return PTR_ERR(opp);
 203                 }
 204                 dev_pm_opp_put(opp);
 205                 profile->freq_table[i] = freq;
 206         }
 207
 208         return 0;
 209 }
 210
 211 /**
 212  * devfreq_update_status() - Update statistics of devfreq behavior
 213  * @devfreq:    the devfreq instance
 214  * @freq:       the update target frequency
 215  */
 216 int devfreq_update_status(struct devfreq *devfreq, unsigned long freq)
 217 {
 218         int lev, prev_lev, ret = 0;
 219         u64 cur_time;
 220
 221         lockdep_assert_held(&devfreq->lock);
 222         cur_time = get_jiffies_64();
 223
 224         /* Immediately exit if previous_freq is not initialized yet. */
 225         if (!devfreq->previous_freq)
 226                 goto out;
 227
 228         prev_lev = devfreq_get_freq_level(devfreq, devfreq->previous_freq);
 229         if (prev_lev < 0) {
 230                 ret = prev_lev;
 231                 goto out;
 232         }
 233
 234         devfreq->stats.time_in_state[prev_lev] +=
 235                         cur_time - devfreq->stats.last_update;
 236
 237         lev = devfreq_get_freq_level(devfreq, freq);
 238         if (lev < 0) {
 239                 ret = lev;
 240                 goto out;
 241         }
 242
 243         if (lev != prev_lev) {
 244                 devfreq->stats.trans_table[
 245                         (prev_lev * devfreq->profile->max_state) + lev]++;
 246                 devfreq->stats.total_trans++;
 247         }
 248
 249 out:
 250         devfreq->stats.last_update = cur_time;
 251         return ret;
 252 }
 253 EXPORT_SYMBOL(devfreq_update_status);
 254
 255 /**
 256  * find_devfreq_governor() - find devfreq governor from name
 257  * @name:       name of the governor
 258  *
 259  * Search the list of devfreq governors and return the matched
 260  * governor's pointer. devfreq_list_lock should be held by the caller.
 261  */
 262 static struct devfreq_governor *find_devfreq_governor(const char *name)
 263 {
 264         struct devfreq_governor *tmp_governor;
 265
 266         lockdep_assert_held(&devfreq_list_lock);
 267
 268         if (IS_ERR_OR_NULL(name)) {
 269                 pr_err("DEVFREQ: %s: Invalid parameters\n", __func__);
 270                 return ERR_PTR(-EINVAL);
 271         }
 272
 273         list_for_each_entry(tmp_governor, &devfreq_governor_list, node) {
 274                 if (!strncmp(tmp_governor->name, name, DEVFREQ_NAME_LEN))
 275                         return tmp_governor;
 276         }
 277
 278         return ERR_PTR(-ENODEV);
 279 }
 280
 281 /**
 282  * try_then_request_governor() - Try to find the governor and request the
 283  *                               module if is not found.
 284  * @name:       name of the governor
 285  *
 286  * Search the list of devfreq governors and request the module and try again
 287  * if is not found. This can happen when both drivers (the governor driver
 288  * and the driver that call devfreq_add_device) are built as modules.
 289  * devfreq_list_lock should be held by the caller. Returns the matched
 290  * governor's pointer or an error pointer.
 291  */
 292 static struct devfreq_governor *try_then_request_governor(const char *name)
 293 {
 294         struct devfreq_governor *governor;
 295         int err = 0;
 296
 297         lockdep_assert_held(&devfreq_list_lock);
 298
 299         if (IS_ERR_OR_NULL(name)) {
 300                 pr_err("DEVFREQ: %s: Invalid parameters\n", __func__);
 301                 return ERR_PTR(-EINVAL);
 302         }
 303
 304         governor = find_devfreq_governor(name);
 305         if (IS_ERR(governor)) {
 306                 mutex_unlock(&devfreq_list_lock);
 307
 308                 if (!strncmp(name, DEVFREQ_GOV_SIMPLE_ONDEMAND,
 309                              DEVFREQ_NAME_LEN))
 310                         err = request_module("governor_%s", "simpleondemand");
 311                 else
 312                         err = request_module("governor_%s", name);
 313                 /* Restore previous state before return */
 314                 mutex_lock(&devfreq_list_lock);
 315                 if (err)
 316                         return (err < 0) ? ERR_PTR(err) : ERR_PTR(-EINVAL);
 317
 318                 governor = find_devfreq_governor(name);
 319         }
 320
 321         return governor;
 322 }
 323
 324 static int devfreq_notify_transition(struct devfreq *devfreq,
 325                 struct devfreq_freqs *freqs, unsigned int state)
 326 {
 327         if (!devfreq)
 328                 return -EINVAL;
 329
 330         switch (state) {
 331         case DEVFREQ_PRECHANGE:
 332                 srcu_notifier_call_chain(&devfreq->transition_notifier_list,
 333                                 DEVFREQ_PRECHANGE, freqs);
 334                 break;
 335
 336         case DEVFREQ_POSTCHANGE:
 337                 srcu_notifier_call_chain(&devfreq->transition_notifier_list,
 338                                 DEVFREQ_POSTCHANGE, freqs);
 339                 break;
 340         default:
 341                 return -EINVAL;
 342         }
 343
 344         return 0;
 345 }
 346
 347 static int devfreq_set_target(struct devfreq *devfreq, unsigned long new_freq,
 348                               u32 flags)
 349 {
 350         struct devfreq_freqs freqs;
 351         unsigned long cur_freq;
 352         int err = 0;
 353
 354         if (devfreq->profile->get_cur_freq)
 355                 devfreq->profile->get_cur_freq(devfreq->dev.parent, &cur_freq);
 356         else
 357                 cur_freq = devfreq->previous_freq;
 358
 359         freqs.old = cur_freq;
 360         freqs.new = new_freq;
 361         devfreq_notify_transition(devfreq, &freqs, DEVFREQ_PRECHANGE);
 362
 363         err = devfreq->profile->target(devfreq->dev.parent, &new_freq, flags);
 364         if (err) {
 365                 freqs.new = cur_freq;
 366                 devfreq_notify_transition(devfreq, &freqs, DEVFREQ_POSTCHANGE);
 367                 return err;
 368         }
 369
 370         freqs.new = new_freq;
 371         devfreq_notify_transition(devfreq, &freqs, DEVFREQ_POSTCHANGE);
 372
 373         if (devfreq_update_status(devfreq, new_freq))
 374                 dev_err(&devfreq->dev,
 375                         "Couldn't update frequency transition information.\n");
 376
 377         devfreq->previous_freq = new_freq;
 378
 379         if (devfreq->suspend_freq)
 380                 devfreq->resume_freq = cur_freq;
 381
 382         return err;
 383 }
 384
 385 /* Load monitoring helper functions for governors use */
 386
 387 /**
 388  * update_devfreq() - Reevaluate the device and configure frequency.
 389  * @devfreq:    the devfreq instance.
 390  *
 391  * Note: Lock devfreq->lock before calling update_devfreq
 392  *       This function is exported for governors.
 393  */
 394 int update_devfreq(struct devfreq *devfreq)
 395 {
 396         unsigned long freq, min_freq, max_freq;
 397         int err = 0;
 398         u32 flags = 0;
 399
 400         lockdep_assert_held(&devfreq->lock);
 401
 402         if (!devfreq->governor)
 403                 return -EINVAL;
 404
 405         /* Reevaluate the proper frequency */
 406         err = devfreq->governor->get_target_freq(devfreq, &freq);
 407         if (err)
 408                 return err;
 409         get_freq_range(devfreq, &min_freq, &max_freq);
 410
 411         if (freq < min_freq) {
 412                 freq = min_freq;
 413                 flags &= ~DEVFREQ_FLAG_LEAST_UPPER_BOUND; /* Use GLB */
 414         }
 415         if (freq > max_freq) {
 416                 freq = max_freq;
 417                 flags |= DEVFREQ_FLAG_LEAST_UPPER_BOUND; /* Use LUB */
 418         }
 419
 420         return devfreq_set_target(devfreq, freq, flags);
 421
 422 }
 423 EXPORT_SYMBOL(update_devfreq);
 424
 425 /**
 426  * devfreq_monitor() - Periodically poll devfreq objects.
 427  * @work:       the work struct used to run devfreq_monitor periodically.
 428  *
 429  */
 430 static void devfreq_monitor(struct work_struct *work)
 431 {
 432         int err;
 433         struct devfreq *devfreq = container_of(work,
 434                                         struct devfreq, work.work);
 435
 436         mutex_lock(&devfreq->lock);
 437         err = update_devfreq(devfreq);
 438         if (err)
 439                 dev_err(&devfreq->dev, "dvfs failed with (%d) error\n", err);
 440
 441         queue_delayed_work(devfreq_wq, &devfreq->work,
 442                                 msecs_to_jiffies(devfreq->profile->polling_ms));
 443         mutex_unlock(&devfreq->lock);
 444
 445         trace_devfreq_monitor(devfreq);
 446 }
 447
 448 /**
 449  * devfreq_monitor_start() - Start load monitoring of devfreq instance
 450  * @devfreq:    the devfreq instance.
 451  *
 452  * Helper function for starting devfreq device load monitoring. By
 453  * default delayed work based monitoring is supported. Function
 454  * to be called from governor in response to DEVFREQ_GOV_START
 455  * event when device is added to devfreq framework.
 456  */
 457 void devfreq_monitor_start(struct devfreq *devfreq)
 458 {
 459         if (devfreq->governor->interrupt_driven)
 460                 return;
 461
 462         switch (devfreq->profile->timer) {
 463         case DEVFREQ_TIMER_DEFERRABLE:
 464                 INIT_DEFERRABLE_WORK(&devfreq->work, devfreq_monitor);
 465                 break;
 466         case DEVFREQ_TIMER_DELAYED:
 467                 INIT_DELAYED_WORK(&devfreq->work, devfreq_monitor);
 468                 break;
 469         default:
 470                 return;
 471         }
 472
 473         if (devfreq->profile->polling_ms)
 474                 queue_delayed_work(devfreq_wq, &devfreq->work,
 475                         msecs_to_jiffies(devfreq->profile->polling_ms));
 476 }
 477 EXPORT_SYMBOL(devfreq_monitor_start);
 478
 479 /**
 480  * devfreq_monitor_stop() - Stop load monitoring of a devfreq instance
 481  * @devfreq:    the devfreq instance.
 482  *
 483  * Helper function to stop devfreq device load monitoring. Function
 484  * to be called from governor in response to DEVFREQ_GOV_STOP
 485  * event when device is removed from devfreq framework.
 486  */
 487 void devfreq_monitor_stop(struct devfreq *devfreq)
 488 {
 489         if (devfreq->governor->interrupt_driven)
 490                 return;
 491
 492         cancel_delayed_work_sync(&devfreq->work);
 493 }
 494 EXPORT_SYMBOL(devfreq_monitor_stop);
 495
 496 /**
 497  * devfreq_monitor_suspend() - Suspend load monitoring of a devfreq instance
 498  * @devfreq:    the devfreq instance.
 499  *
 500  * Helper function to suspend devfreq device load monitoring. Function
 501  * to be called from governor in response to DEVFREQ_GOV_SUSPEND
 502  * event or when polling interval is set to zero.
 503  *
 504  * Note: Though this function is same as devfreq_monitor_stop(),
 505  * intentionally kept separate to provide hooks for collecting
 506  * transition statistics.
 507  */
 508 void devfreq_monitor_suspend(struct devfreq *devfreq)
 509 {
 510         mutex_lock(&devfreq->lock);
 511         if (devfreq->stop_polling) {
 512                 mutex_unlock(&devfreq->lock);
 513                 return;
 514         }
 515
 516         devfreq_update_status(devfreq, devfreq->previous_freq);
 517         devfreq->stop_polling = true;
 518         mutex_unlock(&devfreq->lock);
 519
 520         if (devfreq->governor->interrupt_driven)
 521                 return;
 522
 523         cancel_delayed_work_sync(&devfreq->work);
 524 }
 525 EXPORT_SYMBOL(devfreq_monitor_suspend);
 526
 527 /**
 528  * devfreq_monitor_resume() - Resume load monitoring of a devfreq instance
 529  * @devfreq:    the devfreq instance.
 530  *
 531  * Helper function to resume devfreq device load monitoring. Function
 532  * to be called from governor in response to DEVFREQ_GOV_RESUME
 533  * event or when polling interval is set to non-zero.
 534  */
 535 void devfreq_monitor_resume(struct devfreq *devfreq)
 536 {
 537         unsigned long freq;
 538
 539         mutex_lock(&devfreq->lock);
 540         if (!devfreq->stop_polling)
 541                 goto out;
 542
 543         if (devfreq->governor->interrupt_driven)
 544                 goto out_update;
 545
 546         if (!delayed_work_pending(&devfreq->work) &&
 547                         devfreq->profile->polling_ms)
 548                 queue_delayed_work(devfreq_wq, &devfreq->work,
 549                         msecs_to_jiffies(devfreq->profile->polling_ms));
 550
 551 out_update:
 552         devfreq->stats.last_update = get_jiffies_64();
 553         devfreq->stop_polling = false;
 554
 555         if (devfreq->profile->get_cur_freq &&
 556                 !devfreq->profile->get_cur_freq(devfreq->dev.parent, &freq))
 557                 devfreq->previous_freq = freq;
 558
 559 out:
 560         mutex_unlock(&devfreq->lock);
 561 }
 562 EXPORT_SYMBOL(devfreq_monitor_resume);
 563
 564 /**
 565  * devfreq_update_interval() - Update device devfreq monitoring interval
 566  * @devfreq:    the devfreq instance.
 567  * @delay:      new polling interval to be set.
 568  *
 569  * Helper function to set new load monitoring polling interval. Function
 570  * to be called from governor in response to DEVFREQ_GOV_UPDATE_INTERVAL event.
 571  */
 572 void devfreq_update_interval(struct devfreq *devfreq, unsigned int *delay)
 573 {
 574         unsigned int cur_delay = devfreq->profile->polling_ms;
 575         unsigned int new_delay = *delay;
 576
 577         mutex_lock(&devfreq->lock);
 578         devfreq->profile->polling_ms = new_delay;
 579
 580         if (devfreq->stop_polling)
 581                 goto out;
 582
 583         if (devfreq->governor->interrupt_driven)
 584                 goto out;
 585
 586         /* if new delay is zero, stop polling */
 587         if (!new_delay) {
 588                 mutex_unlock(&devfreq->lock);
 589                 cancel_delayed_work_sync(&devfreq->work);
 590                 return;
 591         }
 592
 593         /* if current delay is zero, start polling with new delay */
 594         if (!cur_delay) {
 595                 queue_delayed_work(devfreq_wq, &devfreq->work,
 596                         msecs_to_jiffies(devfreq->profile->polling_ms));
 597                 goto out;
 598         }
 599
 600         /* if current delay is greater than new delay, restart polling */
 601         if (cur_delay > new_delay) {
 602                 mutex_unlock(&devfreq->lock);
 603                 cancel_delayed_work_sync(&devfreq->work);
 604                 mutex_lock(&devfreq->lock);
 605                 if (!devfreq->stop_polling)
 606                         queue_delayed_work(devfreq_wq, &devfreq->work,
 607                                 msecs_to_jiffies(devfreq->profile->polling_ms));
 608         }
 609 out:
 610         mutex_unlock(&devfreq->lock);
 611 }
 612 EXPORT_SYMBOL(devfreq_update_interval);
 613
 614 /**
 615  * devfreq_notifier_call() - Notify that the device frequency requirements
 616  *                           has been changed out of devfreq framework.
 617  * @nb:         the notifier_block (supposed to be devfreq->nb)
 618  * @type:       not used
 619  * @devp:       not used
 620  *
 621  * Called by a notifier that uses devfreq->nb.
 622  */
 623 static int devfreq_notifier_call(struct notifier_block *nb, unsigned long type,
 624                                  void *devp)
 625 {
 626         struct devfreq *devfreq = container_of(nb, struct devfreq, nb);
 627         int err = -EINVAL;
 628
 629         mutex_lock(&devfreq->lock);
 630
 631         devfreq->scaling_min_freq = find_available_min_freq(devfreq);
 632         if (!devfreq->scaling_min_freq)
 633                 goto out;
 634
 635         devfreq->scaling_max_freq = find_available_max_freq(devfreq);
 636         if (!devfreq->scaling_max_freq) {
 637                 devfreq->scaling_max_freq = ULONG_MAX;
 638                 goto out;
 639         }
 640
 641         err = update_devfreq(devfreq);
 642
 643 out:
 644         mutex_unlock(&devfreq->lock);
 645         if (err)
 646                 dev_err(devfreq->dev.parent,
 647                         "failed to update frequency from OPP notifier (%d)\n",
 648                         err);
 649
 650         return NOTIFY_OK;
 651 }
 652
 653 /**
 654  * qos_notifier_call() - Common handler for QoS constraints.
 655  * @devfreq:    the devfreq instance.
 656  */
 657 static int qos_notifier_call(struct devfreq *devfreq)
 658 {
 659         int err;
 660
 661         mutex_lock(&devfreq->lock);
 662         err = update_devfreq(devfreq);
 663         mutex_unlock(&devfreq->lock);
 664         if (err)
 665                 dev_err(devfreq->dev.parent,
 666                         "failed to update frequency from PM QoS (%d)\n",
 667                         err);
 668
 669         return NOTIFY_OK;
 670 }
 671
 672 /**
 673  * qos_min_notifier_call() - Callback for QoS min_freq changes.
 674  * @nb:         Should be devfreq->nb_min
 675  */
 676 static int qos_min_notifier_call(struct notifier_block *nb,
 677                                          unsigned long val, void *ptr)
 678 {
 679         return qos_notifier_call(container_of(nb, struct devfreq, nb_min));
 680 }
 681
 682 /**
 683  * qos_max_notifier_call() - Callback for QoS max_freq changes.
 684  * @nb:         Should be devfreq->nb_max
 685  */
 686 static int qos_max_notifier_call(struct notifier_block *nb,
 687                                          unsigned long val, void *ptr)
 688 {
 689         return qos_notifier_call(container_of(nb, struct devfreq, nb_max));
 690 }
 691
 692 /**
 693  * devfreq_dev_release() - Callback for struct device to release the device.
 694  * @dev:        the devfreq device
 695  *
 696  * Remove devfreq from the list and release its resources.
 697  */
 698 static void devfreq_dev_release(struct device *dev)
 699 {
 700         struct devfreq *devfreq = to_devfreq(dev);
 701         int err;
 702
 703         mutex_lock(&devfreq_list_lock);
 704         list_del(&devfreq->node);
 705         mutex_unlock(&devfreq_list_lock);
 706
 707         err = dev_pm_qos_remove_notifier(devfreq->dev.parent, &devfreq->nb_max,
 708                                          DEV_PM_QOS_MAX_FREQUENCY);
 709         if (err && err != -ENOENT)
 710                 dev_warn(dev->parent,
 711                         "Failed to remove max_freq notifier: %d\n", err);
 712         err = dev_pm_qos_remove_notifier(devfreq->dev.parent, &devfreq->nb_min,
 713                                          DEV_PM_QOS_MIN_FREQUENCY);
 714         if (err && err != -ENOENT)
 715                 dev_warn(dev->parent,
 716                         "Failed to remove min_freq notifier: %d\n", err);
 717
 718         if (dev_pm_qos_request_active(&devfreq->user_max_freq_req)) {
 719                 err = dev_pm_qos_remove_request(&devfreq->user_max_freq_req);
 720                 if (err < 0)
 721                         dev_warn(dev->parent,
 722                                 "Failed to remove max_freq request: %d\n", err);
 723         }
 724         if (dev_pm_qos_request_active(&devfreq->user_min_freq_req)) {
 725                 err = dev_pm_qos_remove_request(&devfreq->user_min_freq_req);
 726                 if (err < 0)
 727                         dev_warn(dev->parent,
 728                                 "Failed to remove min_freq request: %d\n", err);
 729         }
 730
 731         if (devfreq->profile->exit)
 732                 devfreq->profile->exit(devfreq->dev.parent);
 733
 734         mutex_destroy(&devfreq->lock);
 735         kfree(devfreq);
 736 }
 737
 738 /**
 739  * devfreq_add_device() - Add devfreq feature to the device
 740  * @dev:        the device to add devfreq feature.
 741  * @profile:    device-specific profile to run devfreq.
 742  * @governor_name:      name of the policy to choose frequency.
 743  * @data:       private data for the governor. The devfreq framework does not
 744  *              touch this value.
 745  */
 746 struct devfreq *devfreq_add_device(struct device *dev,
 747                                    struct devfreq_dev_profile *profile,
 748                                    const char *governor_name,
 749                                    void *data)
 750 {
 751         struct devfreq *devfreq;
 752         struct devfreq_governor *governor;
 753         int err = 0;
 754
 755         if (!dev || !profile || !governor_name) {
 756                 dev_err(dev, "%s: Invalid parameters.\n", __func__);
 757                 return ERR_PTR(-EINVAL);
 758         }
 759
 760         mutex_lock(&devfreq_list_lock);
 761         devfreq = find_device_devfreq(dev);
 762         mutex_unlock(&devfreq_list_lock);
 763         if (!IS_ERR(devfreq)) {
 764                 dev_err(dev, "%s: devfreq device already exists!\n",
 765                         __func__);
 766                 err = -EINVAL;
 767                 goto err_out;
 768         }
 769
 770         devfreq = kzalloc(sizeof(struct devfreq), GFP_KERNEL);
 771         if (!devfreq) {
 772                 err = -ENOMEM;
 773                 goto err_out;
 774         }
 775
 776         mutex_init(&devfreq->lock);
 777         mutex_lock(&devfreq->lock);
 778         devfreq->dev.parent = dev;
 779         devfreq->dev.class = devfreq_class;
 780         devfreq->dev.release = devfreq_dev_release;
 781         INIT_LIST_HEAD(&devfreq->node);
 782         devfreq->profile = profile;
 783         strscpy(devfreq->governor_name, governor_name, DEVFREQ_NAME_LEN);
 784         devfreq->previous_freq = profile->initial_freq;
 785         devfreq->last_status.current_frequency = profile->initial_freq;
 786         devfreq->data = data;
 787         devfreq->nb.notifier_call = devfreq_notifier_call;
 788
 789         if (devfreq->profile->timer < 0
 790                 || devfreq->profile->timer >= DEVFREQ_TIMER_NUM) {
 791                 goto err_out;
 792         }
 793
 794         if (!devfreq->profile->max_state && !devfreq->profile->freq_table) {
 795                 mutex_unlock(&devfreq->lock);
 796                 err = set_freq_table(devfreq);
 797                 if (err < 0)
 798                         goto err_dev;
 799                 mutex_lock(&devfreq->lock);
 800         }
 801
 802         devfreq->scaling_min_freq = find_available_min_freq(devfreq);
 803         if (!devfreq->scaling_min_freq) {
 804                 mutex_unlock(&devfreq->lock);
 805                 err = -EINVAL;
 806                 goto err_dev;
 807         }
 808
 809         devfreq->scaling_max_freq = find_available_max_freq(devfreq);
 810         if (!devfreq->scaling_max_freq) {
 811                 mutex_unlock(&devfreq->lock);
 812                 err = -EINVAL;
 813                 goto err_dev;
 814         }
 815
 816         devfreq->suspend_freq = dev_pm_opp_get_suspend_opp_freq(dev);
 817         atomic_set(&devfreq->suspend_count, 0);
 818
 819         dev_set_name(&devfreq->dev, "%s", dev_name(dev));
 820         err = device_register(&devfreq->dev);
 821         if (err) {
 822                 mutex_unlock(&devfreq->lock);
 823                 put_device(&devfreq->dev);
 824                 goto err_out;
 825         }
 826
 827         devfreq->stats.trans_table = devm_kzalloc(&devfreq->dev,
 828                         array3_size(sizeof(unsigned int),
 829                                     devfreq->profile->max_state,
 830                                     devfreq->profile->max_state),
 831                         GFP_KERNEL);
 832         if (!devfreq->stats.trans_table) {
 833                 mutex_unlock(&devfreq->lock);
 834                 err = -ENOMEM;
 835                 goto err_devfreq;
 836         }
 837
 838         devfreq->stats.time_in_state = devm_kcalloc(&devfreq->dev,
 839                         devfreq->profile->max_state,
 840                         sizeof(*devfreq->stats.time_in_state),
 841                         GFP_KERNEL);
 842         if (!devfreq->stats.time_in_state) {
 843                 mutex_unlock(&devfreq->lock);
 844                 err = -ENOMEM;
 845                 goto err_devfreq;
 846         }
 847
 848         devfreq->stats.total_trans = 0;
 849         devfreq->stats.last_update = get_jiffies_64();
 850
 851         srcu_init_notifier_head(&devfreq->transition_notifier_list);
 852
 853         mutex_unlock(&devfreq->lock);
 854
 855         err = dev_pm_qos_add_request(dev, &devfreq->user_min_freq_req,
 856                                      DEV_PM_QOS_MIN_FREQUENCY, 0);
 857         if (err < 0)
 858                 goto err_devfreq;
 859         err = dev_pm_qos_add_request(dev, &devfreq->user_max_freq_req,
 860                                      DEV_PM_QOS_MAX_FREQUENCY,
 861                                      PM_QOS_MAX_FREQUENCY_DEFAULT_VALUE);
 862         if (err < 0)
 863                 goto err_devfreq;
 864
 865         devfreq->nb_min.notifier_call = qos_min_notifier_call;
 866         err = dev_pm_qos_add_notifier(devfreq->dev.parent, &devfreq->nb_min,
 867                                       DEV_PM_QOS_MIN_FREQUENCY);
 868         if (err)
 869                 goto err_devfreq;
 870
 871         devfreq->nb_max.notifier_call = qos_max_notifier_call;
 872         err = dev_pm_qos_add_notifier(devfreq->dev.parent, &devfreq->nb_max,
 873                                       DEV_PM_QOS_MAX_FREQUENCY);
 874         if (err)
 875                 goto err_devfreq;
 876
 877         mutex_lock(&devfreq_list_lock);
 878
 879         governor = try_then_request_governor(devfreq->governor_name);
 880         if (IS_ERR(governor)) {
 881                 dev_err(dev, "%s: Unable to find governor for the device\n",
 882                         __func__);
 883                 err = PTR_ERR(governor);
 884                 goto err_init;
 885         }
 886
 887         devfreq->governor = governor;
 888         err = devfreq->governor->event_handler(devfreq, DEVFREQ_GOV_START,
 889                                                 NULL);
 890         if (err) {
 891                 dev_err(dev, "%s: Unable to start governor for the device\n",
 892                         __func__);
 893                 goto err_init;
 894         }
 895
 896         list_add(&devfreq->node, &devfreq_list);
 897
 898         mutex_unlock(&devfreq_list_lock);
 899
 900         return devfreq;
 901
 902 err_init:
 903         mutex_unlock(&devfreq_list_lock);
 904 err_devfreq:
 905         devfreq_remove_device(devfreq);
 906         devfreq = NULL;
 907 err_dev:
 908         kfree(devfreq);
 909 err_out:
 910         return ERR_PTR(err);
 911 }
 912 EXPORT_SYMBOL(devfreq_add_device);
 913
 914 /**
 915  * devfreq_remove_device() - Remove devfreq feature from a device.
 916  * @devfreq:    the devfreq instance to be removed
 917  *
 918  * The opposite of devfreq_add_device().
 919  */
 920 int devfreq_remove_device(struct devfreq *devfreq)
 921 {
 922         if (!devfreq)
 923                 return -EINVAL;
 924
 925         if (devfreq->governor)
 926                 devfreq->governor->event_handler(devfreq,
 927                                                  DEVFREQ_GOV_STOP, NULL);
 928         device_unregister(&devfreq->dev);
 929
 930         return 0;
 931 }
 932 EXPORT_SYMBOL(devfreq_remove_device);
 933
 934 static int devm_devfreq_dev_match(struct device *dev, void *res, void *data)
 935 {
 936         struct devfreq **r = res;
 937
 938         if (WARN_ON(!r || !*r))
 939                 return 0;
 940
 941         return *r == data;
 942 }
 943
 944 static void devm_devfreq_dev_release(struct device *dev, void *res)
 945 {
 946         devfreq_remove_device(*(struct devfreq **)res);
 947 }
 948
 949 /**
 950  * devm_devfreq_add_device() - Resource-managed devfreq_add_device()
 951  * @dev:        the device to add devfreq feature.
 952  * @profile:    device-specific profile to run devfreq.
 953  * @governor_name:      name of the policy to choose frequency.
 954  * @data:       private data for the governor. The devfreq framework does not
 955  *              touch this value.
 956  *
 957  * This function manages automatically the memory of devfreq device using device
 958  * resource management and simplify the free operation for memory of devfreq
 959  * device.
 960  */
 961 struct devfreq *devm_devfreq_add_device(struct device *dev,
 962                                         struct devfreq_dev_profile *profile,
 963                                         const char *governor_name,
 964                                         void *data)
 965 {
 966         struct devfreq **ptr, *devfreq;
 967
 968         ptr = devres_alloc(devm_devfreq_dev_release, sizeof(*ptr), GFP_KERNEL);
 969         if (!ptr)
 970                 return ERR_PTR(-ENOMEM);
 971
 972         devfreq = devfreq_add_device(dev, profile, governor_name, data);
 973         if (IS_ERR(devfreq)) {
 974                 devres_free(ptr);
 975                 return devfreq;
 976         }
 977
 978         *ptr = devfreq;
 979         devres_add(dev, ptr);
 980
 981         return devfreq;
 982 }
 983 EXPORT_SYMBOL(devm_devfreq_add_device);
 984
 985 #ifdef CONFIG_OF
 986 /*
 987  * devfreq_get_devfreq_by_node - Get the devfreq device from devicetree
 988  * @node - pointer to device_node
 989  *
 990  * return the instance of devfreq device
 991  */
 992 struct devfreq *devfreq_get_devfreq_by_node(struct device_node *node)
 993 {
 994         struct devfreq *devfreq;
 995
 996         if (!node)
 997                 return ERR_PTR(-EINVAL);
 998
 999         mutex_lock(&devfreq_list_lock);
1000         list_for_each_entry(devfreq, &devfreq_list, node) {
1001                 if (devfreq->dev.parent
1002                         && devfreq->dev.parent->of_node == node) {
1003                         mutex_unlock(&devfreq_list_lock);
1004                         return devfreq;
1005                 }
1006         }
1007         mutex_unlock(&devfreq_list_lock);
1008
1009         return ERR_PTR(-ENODEV);
1010 }
1011
1012 /*
1013  * devfreq_get_devfreq_by_phandle - Get the devfreq device from devicetree
1014  * @dev - instance to the given device
1015  * @phandle_name - name of property holding a phandle value
1016  * @index - index into list of devfreq
1017  *
1018  * return the instance of devfreq device
1019  */
1020 struct devfreq *devfreq_get_devfreq_by_phandle(struct device *dev,
1021                                         const char *phandle_name, int index)
1022 {
1023         struct device_node *node;
1024         struct devfreq *devfreq;
1025
1026         if (!dev || !phandle_name)
1027                 return ERR_PTR(-EINVAL);
1028
1029         if (!dev->of_node)
1030                 return ERR_PTR(-EINVAL);
1031
1032         node = of_parse_phandle(dev->of_node, phandle_name, index);
1033         if (!node)
1034                 return ERR_PTR(-ENODEV);
1035
1036         devfreq = devfreq_get_devfreq_by_node(node);
1037         of_node_put(node);
1038
1039         return devfreq;
1040 }
1041
1042 #else
1043 struct devfreq *devfreq_get_devfreq_by_node(struct device_node *node)
1044 {
1045         return ERR_PTR(-ENODEV);
1046 }
1047
1048 struct devfreq *devfreq_get_devfreq_by_phandle(struct device *dev,
1049                                         const char *phandle_name, int index)
1050 {
1051         return ERR_PTR(-ENODEV);
1052 }
1053 #endif /* CONFIG_OF */
1054 EXPORT_SYMBOL_GPL(devfreq_get_devfreq_by_node);
1055 EXPORT_SYMBOL_GPL(devfreq_get_devfreq_by_phandle);
1056
1057 /**
1058  * devm_devfreq_remove_device() - Resource-managed devfreq_remove_device()
1059  * @dev:        the device from which to remove devfreq feature.
1060  * @devfreq:    the devfreq instance to be removed
1061  */
1062 void devm_devfreq_remove_device(struct device *dev, struct devfreq *devfreq)
1063 {
1064         WARN_ON(devres_release(dev, devm_devfreq_dev_release,
1065                                devm_devfreq_dev_match, devfreq));
1066 }
1067 EXPORT_SYMBOL(devm_devfreq_remove_device);
1068
1069 /**
1070  * devfreq_suspend_device() - Suspend devfreq of a device.
1071  * @devfreq: the devfreq instance to be suspended
1072  *
1073  * This function is intended to be called by the pm callbacks
1074  * (e.g., runtime_suspend, suspend) of the device driver that
1075  * holds the devfreq.
1076  */
1077 int devfreq_suspend_device(struct devfreq *devfreq)
1078 {
1079         int ret;
1080
1081         if (!devfreq)
1082                 return -EINVAL;
1083
1084         if (atomic_inc_return(&devfreq->suspend_count) > 1)
1085                 return 0;
1086
1087         if (devfreq->governor) {
1088                 ret = devfreq->governor->event_handler(devfreq,
1089                                         DEVFREQ_GOV_SUSPEND, NULL);
1090                 if (ret)
1091                         return ret;
1092         }
1093
1094         if (devfreq->suspend_freq) {
1095                 mutex_lock(&devfreq->lock);
1096                 ret = devfreq_set_target(devfreq, devfreq->suspend_freq, 0);
1097                 mutex_unlock(&devfreq->lock);
1098                 if (ret)
1099                         return ret;
1100         }
1101
1102         return 0;
1103 }
1104 EXPORT_SYMBOL(devfreq_suspend_device);
1105
1106 /**
1107  * devfreq_resume_device() - Resume devfreq of a device.
1108  * @devfreq: the devfreq instance to be resumed
1109  *
1110  * This function is intended to be called by the pm callbacks
1111  * (e.g., runtime_resume, resume) of the device driver that
1112  * holds the devfreq.
1113  */
1114 int devfreq_resume_device(struct devfreq *devfreq)
1115 {
1116         int ret;
1117
1118         if (!devfreq)
1119                 return -EINVAL;
1120
1121         if (atomic_dec_return(&devfreq->suspend_count) >= 1)
1122                 return 0;
1123
1124         if (devfreq->resume_freq) {
1125                 mutex_lock(&devfreq->lock);
1126                 ret = devfreq_set_target(devfreq, devfreq->resume_freq, 0);
1127                 mutex_unlock(&devfreq->lock);
1128                 if (ret)
1129                         return ret;
1130         }
1131
1132         if (devfreq->governor) {
1133                 ret = devfreq->governor->event_handler(devfreq,
1134                                         DEVFREQ_GOV_RESUME, NULL);
1135                 if (ret)
1136                         return ret;
1137         }
1138
1139         return 0;
1140 }
1141 EXPORT_SYMBOL(devfreq_resume_device);
1142
1143 /**
1144  * devfreq_suspend() - Suspend devfreq governors and devices
1145  *
1146  * Called during system wide Suspend/Hibernate cycles for suspending governors
1147  * and devices preserving the state for resume. On some platforms the devfreq
1148  * device must have precise state (frequency) after resume in order to provide
1149  * fully operating setup.
1150  */
1151 void devfreq_suspend(void)
1152 {
1153         struct devfreq *devfreq;
1154         int ret;
1155
1156         mutex_lock(&devfreq_list_lock);
1157         list_for_each_entry(devfreq, &devfreq_list, node) {
1158                 ret = devfreq_suspend_device(devfreq);
1159                 if (ret)
1160                         dev_err(&devfreq->dev,
1161                                 "failed to suspend devfreq device\n");
1162         }
1163         mutex_unlock(&devfreq_list_lock);
1164 }
1165
1166 /**
1167  * devfreq_resume() - Resume devfreq governors and devices
1168  *
1169  * Called during system wide Suspend/Hibernate cycle for resuming governors and
1170  * devices that are suspended with devfreq_suspend().
1171  */
1172 void devfreq_resume(void)
1173 {
1174         struct devfreq *devfreq;
1175         int ret;
1176
1177         mutex_lock(&devfreq_list_lock);
1178         list_for_each_entry(devfreq, &devfreq_list, node) {
1179                 ret = devfreq_resume_device(devfreq);
1180                 if (ret)
1181                         dev_warn(&devfreq->dev,
1182                                  "failed to resume devfreq device\n");
1183         }
1184         mutex_unlock(&devfreq_list_lock);
1185 }
1186
1187 /**
1188  * devfreq_add_governor() - Add devfreq governor
1189  * @governor:   the devfreq governor to be added
1190  */
1191 int devfreq_add_governor(struct devfreq_governor *governor)
1192 {
1193         struct devfreq_governor *g;
1194         struct devfreq *devfreq;
1195         int err = 0;
1196
1197         if (!governor) {
1198                 pr_err("%s: Invalid parameters.\n", __func__);
1199                 return -EINVAL;
1200         }
1201
1202         mutex_lock(&devfreq_list_lock);
1203         g = find_devfreq_governor(governor->name);
1204         if (!IS_ERR(g)) {
1205                 pr_err("%s: governor %s already registered\n", __func__,
1206                        g->name);
1207                 err = -EINVAL;
1208                 goto err_out;
1209         }
1210
1211         list_add(&governor->node, &devfreq_governor_list);
1212
1213         list_for_each_entry(devfreq, &devfreq_list, node) {
1214                 int ret = 0;
1215                 struct device *dev = devfreq->dev.parent;
1216
1217                 if (!strncmp(devfreq->governor_name, governor->name,
1218                              DEVFREQ_NAME_LEN)) {
1219                         /* The following should never occur */
1220                         if (devfreq->governor) {
1221                                 dev_warn(dev,
1222                                          "%s: Governor %s already present\n",
1223                                          __func__, devfreq->governor->name);
1224                                 ret = devfreq->governor->event_handler(devfreq,
1225                                                         DEVFREQ_GOV_STOP, NULL);
1226                                 if (ret) {
1227                                         dev_warn(dev,
1228                                                  "%s: Governor %s stop = %d\n",
1229                                                  __func__,
1230                                                  devfreq->governor->name, ret);
1231                                 }
1232                                 /* Fall through */
1233                         }
1234                         devfreq->governor = governor;
1235                         ret = devfreq->governor->event_handler(devfreq,
1236                                                 DEVFREQ_GOV_START, NULL);
1237                         if (ret) {
1238                                 dev_warn(dev, "%s: Governor %s start=%d\n",
1239                                          __func__, devfreq->governor->name,
1240                                          ret);
1241                         }
1242                 }
1243         }
1244
1245 err_out:
1246         mutex_unlock(&devfreq_list_lock);
1247
1248         return err;
1249 }
1250 EXPORT_SYMBOL(devfreq_add_governor);
1251
1252 /**
1253  * devfreq_remove_governor() - Remove devfreq feature from a device.
1254  * @governor:   the devfreq governor to be removed
1255  */
1256 int devfreq_remove_governor(struct devfreq_governor *governor)
1257 {
1258         struct devfreq_governor *g;
1259         struct devfreq *devfreq;
1260         int err = 0;
1261
1262         if (!governor) {
1263                 pr_err("%s: Invalid parameters.\n", __func__);
1264                 return -EINVAL;
1265         }
1266
1267         mutex_lock(&devfreq_list_lock);
1268         g = find_devfreq_governor(governor->name);
1269         if (IS_ERR(g)) {
1270                 pr_err("%s: governor %s not registered\n", __func__,
1271                        governor->name);
1272                 err = PTR_ERR(g);
1273                 goto err_out;
1274         }
1275         list_for_each_entry(devfreq, &devfreq_list, node) {
1276                 int ret;
1277                 struct device *dev = devfreq->dev.parent;
1278
1279                 if (!strncmp(devfreq->governor_name, governor->name,
1280                              DEVFREQ_NAME_LEN)) {
1281                         /* we should have a devfreq governor! */
1282                         if (!devfreq->governor) {
1283                                 dev_warn(dev, "%s: Governor %s NOT present\n",
1284                                          __func__, governor->name);
1285                                 continue;
1286                                 /* Fall through */
1287                         }
1288                         ret = devfreq->governor->event_handler(devfreq,
1289                                                 DEVFREQ_GOV_STOP, NULL);
1290                         if (ret) {
1291                                 dev_warn(dev, "%s: Governor %s stop=%d\n",
1292                                          __func__, devfreq->governor->name,
1293                                          ret);
1294                         }
1295                         devfreq->governor = NULL;
1296                 }
1297         }
1298
1299         list_del(&governor->node);
1300 err_out:
1301         mutex_unlock(&devfreq_list_lock);
1302
1303         return err;
1304 }
1305 EXPORT_SYMBOL(devfreq_remove_governor);
1306
1307 static ssize_t name_show(struct device *dev,
1308                         struct device_attribute *attr, char *buf)
1309 {
1310         struct devfreq *df = to_devfreq(dev);
1311         return sprintf(buf, "%s\n", dev_name(df->dev.parent));
1312 }
1313 static DEVICE_ATTR_RO(name);
1314
1315 static ssize_t governor_show(struct device *dev,
1316                              struct device_attribute *attr, char *buf)
1317 {
1318         struct devfreq *df = to_devfreq(dev);
1319
1320         if (!df->governor)
1321                 return -EINVAL;
1322
1323         return sprintf(buf, "%s\n", df->governor->name);
1324 }
1325
1326 static ssize_t governor_store(struct device *dev, struct device_attribute *attr,
1327                               const char *buf, size_t count)
1328 {
1329         struct devfreq *df = to_devfreq(dev);
1330         int ret;
1331         char str_governor[DEVFREQ_NAME_LEN + 1];
1332         const struct devfreq_governor *governor, *prev_governor;
1333
1334         if (!df->governor)
1335                 return -EINVAL;
1336
1337         ret = sscanf(buf, "%" __stringify(DEVFREQ_NAME_LEN) "s", str_governor);
1338         if (ret != 1)
1339                 return -EINVAL;
1340
1341         mutex_lock(&devfreq_list_lock);
1342         governor = try_then_request_governor(str_governor);
1343         if (IS_ERR(governor)) {
1344                 ret = PTR_ERR(governor);
1345                 goto out;
1346         }
1347         if (df->governor == governor) {
1348                 ret = 0;
1349                 goto out;
1350         } else if (df->governor->immutable || governor->immutable) {
1351                 ret = -EINVAL;
1352                 goto out;
1353         }
1354
1355         ret = df->governor->event_handler(df, DEVFREQ_GOV_STOP, NULL);
1356         if (ret) {
1357                 dev_warn(dev, "%s: Governor %s not stopped(%d)\n",
1358                          __func__, df->governor->name, ret);
1359                 goto out;
1360         }
1361
1362         prev_governor = df->governor;
1363         df->governor = governor;
1364         strncpy(df->governor_name, governor->name, DEVFREQ_NAME_LEN);
1365         ret = df->governor->event_handler(df, DEVFREQ_GOV_START, NULL);
1366         if (ret) {
1367                 dev_warn(dev, "%s: Governor %s not started(%d)\n",
1368                          __func__, df->governor->name, ret);
1369                 df->governor = prev_governor;
1370                 strncpy(df->governor_name, prev_governor->name,
1371                         DEVFREQ_NAME_LEN);
1372                 ret = df->governor->event_handler(df, DEVFREQ_GOV_START, NULL);
1373                 if (ret) {
1374                         dev_err(dev,
1375                                 "%s: reverting to Governor %s failed (%d)\n",
1376                                 __func__, df->governor_name, ret);
1377                         df->governor = NULL;
1378                 }
1379         }
1380 out:
1381         mutex_unlock(&devfreq_list_lock);
1382
1383         if (!ret)
1384                 ret = count;
1385         return ret;
1386 }
1387 static DEVICE_ATTR_RW(governor);
1388
1389 static ssize_t available_governors_show(struct device *d,
1390                                         struct device_attribute *attr,
1391                                         char *buf)
1392 {
1393         struct devfreq *df = to_devfreq(d);
1394         ssize_t count = 0;
1395
1396         if (!df->governor)
1397                 return -EINVAL;
1398
1399         mutex_lock(&devfreq_list_lock);
1400
1401         /*
1402          * The devfreq with immutable governor (e.g., passive) shows
1403          * only own governor.
1404          */
1405         if (df->governor->immutable) {
1406                 count = scnprintf(&buf[count], DEVFREQ_NAME_LEN,
1407                                   "%s ", df->governor_name);
1408         /*
1409          * The devfreq device shows the registered governor except for
1410          * immutable governors such as passive governor .
1411          */
1412         } else {
1413                 struct devfreq_governor *governor;
1414
1415                 list_for_each_entry(governor, &devfreq_governor_list, node) {
1416                         if (governor->immutable)
1417                                 continue;
1418                         count += scnprintf(&buf[count], (PAGE_SIZE - count - 2),
1419                                            "%s ", governor->name);
1420                 }
1421         }
1422
1423         mutex_unlock(&devfreq_list_lock);
1424
1425         /* Truncate the trailing space */
1426         if (count)
1427                 count--;
1428
1429         count += sprintf(&buf[count], "\n");
1430
1431         return count;
1432 }
1433 static DEVICE_ATTR_RO(available_governors);
1434
1435 static ssize_t cur_freq_show(struct device *dev, struct device_attribute *attr,
1436                              char *buf)
1437 {
1438         unsigned long freq;
1439         struct devfreq *df = to_devfreq(dev);
1440
1441         if (!df->profile)
1442                 return -EINVAL;
1443
1444         if (df->profile->get_cur_freq &&
1445                 !df->profile->get_cur_freq(df->dev.parent, &freq))
1446                 return sprintf(buf, "%lu\n", freq);
1447
1448         return sprintf(buf, "%lu\n", df->previous_freq);
1449 }
1450 static DEVICE_ATTR_RO(cur_freq);
1451
1452 static ssize_t target_freq_show(struct device *dev,
1453                                 struct device_attribute *attr, char *buf)
1454 {
1455         struct devfreq *df = to_devfreq(dev);
1456
1457         return sprintf(buf, "%lu\n", df->previous_freq);
1458 }
1459 static DEVICE_ATTR_RO(target_freq);
1460
1461 static ssize_t polling_interval_show(struct device *dev,
1462                                      struct device_attribute *attr, char *buf)
1463 {
1464         struct devfreq *df = to_devfreq(dev);
1465
1466         if (!df->profile)
1467                 return -EINVAL;
1468
1469         return sprintf(buf, "%d\n", df->profile->polling_ms);
1470 }
1471
1472 static ssize_t polling_interval_store(struct device *dev,
1473                                       struct device_attribute *attr,
1474                                       const char *buf, size_t count)
1475 {
1476         struct devfreq *df = to_devfreq(dev);
1477         unsigned int value;
1478         int ret;
1479
1480         if (!df->governor)
1481                 return -EINVAL;
1482
1483         ret = sscanf(buf, "%u", &value);
1484         if (ret != 1)
1485                 return -EINVAL;
1486
1487         df->governor->event_handler(df, DEVFREQ_GOV_UPDATE_INTERVAL, &value);
1488         ret = count;
1489
1490         return ret;
1491 }
1492 static DEVICE_ATTR_RW(polling_interval);
1493
1494 static ssize_t min_freq_store(struct device *dev, struct device_attribute *attr,
1495                               const char *buf, size_t count)
1496 {
1497         struct devfreq *df = to_devfreq(dev);
1498         unsigned long value;
1499         int ret;
1500
1501         /*
1502          * Protect against theoretical sysfs writes between
1503          * device_add and dev_pm_qos_add_request
1504          */
1505         if (!dev_pm_qos_request_active(&df->user_min_freq_req))
1506                 return -EAGAIN;
1507
1508         ret = sscanf(buf, "%lu", &value);
1509         if (ret != 1)
1510                 return -EINVAL;
1511
1512         /* Round down to kHz for PM QoS */
1513         ret = dev_pm_qos_update_request(&df->user_min_freq_req,
1514                                         value / HZ_PER_KHZ);
1515         if (ret < 0)
1516                 return ret;
1517
1518         return count;
1519 }
1520
1521 static ssize_t min_freq_show(struct device *dev, struct device_attribute *attr,
1522                              char *buf)
1523 {
1524         struct devfreq *df = to_devfreq(dev);
1525         unsigned long min_freq, max_freq;
1526
1527         mutex_lock(&df->lock);
1528         get_freq_range(df, &min_freq, &max_freq);
1529         mutex_unlock(&df->lock);
1530
1531         return sprintf(buf, "%lu\n", min_freq);
1532 }
1533 static DEVICE_ATTR_RW(min_freq);
1534
1535 static ssize_t max_freq_store(struct device *dev, struct device_attribute *attr,
1536                               const char *buf, size_t count)
1537 {
1538         struct devfreq *df = to_devfreq(dev);
1539         unsigned long value;
1540         int ret;
1541
1542         /*
1543          * Protect against theoretical sysfs writes between
1544          * device_add and dev_pm_qos_add_request
1545          */
1546         if (!dev_pm_qos_request_active(&df->user_max_freq_req))
1547                 return -EINVAL;
1548
1549         ret = sscanf(buf, "%lu", &value);
1550         if (ret != 1)
1551                 return -EINVAL;
1552
1553         /*
1554          * PM QoS frequencies are in kHz so we need to convert. Convert by
1555          * rounding upwards so that the acceptable interval never shrinks.
1556          *
1557          * For example if the user writes "666666666" to sysfs this value will
1558          * be converted to 666667 kHz and back to 666667000 Hz before an OPP
1559          * lookup, this ensures that an OPP of 666666666Hz is still accepted.
1560          *
1561          * A value of zero means "no limit".
1562          */
1563         if (value)
1564                 value = DIV_ROUND_UP(value, HZ_PER_KHZ);
1565         else
1566                 value = PM_QOS_MAX_FREQUENCY_DEFAULT_VALUE;
1567
1568         ret = dev_pm_qos_update_request(&df->user_max_freq_req, value);
1569         if (ret < 0)
1570                 return ret;
1571
1572         return count;
1573 }
1574
1575 static ssize_t max_freq_show(struct device *dev, struct device_attribute *attr,
1576                              char *buf)
1577 {
1578         struct devfreq *df = to_devfreq(dev);
1579         unsigned long min_freq, max_freq;
1580
1581         mutex_lock(&df->lock);
1582         get_freq_range(df, &min_freq, &max_freq);
1583         mutex_unlock(&df->lock);
1584
1585         return sprintf(buf, "%lu\n", max_freq);
1586 }
1587 static DEVICE_ATTR_RW(max_freq);
1588
1589 static ssize_t available_frequencies_show(struct device *d,
1590                                           struct device_attribute *attr,
1591                                           char *buf)
1592 {
1593         struct devfreq *df = to_devfreq(d);
1594         ssize_t count = 0;
1595         int i;
1596
1597         if (!df->profile)
1598                 return -EINVAL;
1599
1600         mutex_lock(&df->lock);
1601
1602         for (i = 0; i < df->profile->max_state; i++)
1603                 count += scnprintf(&buf[count], (PAGE_SIZE - count - 2),
1604                                 "%lu ", df->profile->freq_table[i]);
1605
1606         mutex_unlock(&df->lock);
1607         /* Truncate the trailing space */
1608         if (count)
1609                 count--;
1610
1611         count += sprintf(&buf[count], "\n");
1612
1613         return count;
1614 }
1615 static DEVICE_ATTR_RO(available_frequencies);
1616
1617 static ssize_t trans_stat_show(struct device *dev,
1618                                struct device_attribute *attr, char *buf)
1619 {
1620         struct devfreq *df = to_devfreq(dev);
1621         ssize_t len;
1622         int i, j;
1623         unsigned int max_state;
1624
1625         if (!df->profile)
1626                 return -EINVAL;
1627         max_state = df->profile->max_state;
1628
1629         if (max_state == 0)
1630                 return sprintf(buf, "Not Supported.\n");
1631
1632         mutex_lock(&df->lock);
1633         if (!df->stop_polling &&
1634                         devfreq_update_status(df, df->previous_freq)) {
1635                 mutex_unlock(&df->lock);
1636                 return 0;
1637         }
1638         mutex_unlock(&df->lock);
1639
1640         len = sprintf(buf, "     From  :   To\n");
1641         len += sprintf(buf + len, "           :");
1642         for (i = 0; i < max_state; i++)
1643                 len += sprintf(buf + len, "%10lu",
1644                                 df->profile->freq_table[i]);
1645
1646         len += sprintf(buf + len, "   time(ms)\n");
1647
1648         for (i = 0; i < max_state; i++) {
1649                 if (df->profile->freq_table[i]
1650                                         == df->previous_freq) {
1651                         len += sprintf(buf + len, "*");
1652                 } else {
1653                         len += sprintf(buf + len, " ");
1654                 }
1655                 len += sprintf(buf + len, "%10lu:",
1656                                 df->profile->freq_table[i]);
1657                 for (j = 0; j < max_state; j++)
1658                         len += sprintf(buf + len, "%10u",
1659                                 df->stats.trans_table[(i * max_state) + j]);
1660
1661                 len += sprintf(buf + len, "%10llu\n", (u64)
1662                         jiffies64_to_msecs(df->stats.time_in_state[i]));
1663         }
1664
1665         len += sprintf(buf + len, "Total transition : %u\n",
1666                                         df->stats.total_trans);
1667         return len;
1668 }
1669
1670 static ssize_t trans_stat_store(struct device *dev,
1671                                 struct device_attribute *attr,
1672                                 const char *buf, size_t count)
1673 {
1674         struct devfreq *df = to_devfreq(dev);
1675         int err, value;
1676
1677         if (!df->profile)
1678                 return -EINVAL;
1679
1680         if (df->profile->max_state == 0)
1681                 return count;
1682
1683         err = kstrtoint(buf, 10, &value);
1684         if (err || value != 0)
1685                 return -EINVAL;
1686
1687         mutex_lock(&df->lock);
1688         memset(df->stats.time_in_state, 0, (df->profile->max_state *
1689                                         sizeof(*df->stats.time_in_state)));
1690         memset(df->stats.trans_table, 0, array3_size(sizeof(unsigned int),
1691                                         df->profile->max_state,
1692                                         df->profile->max_state));
1693         df->stats.total_trans = 0;
1694         df->stats.last_update = get_jiffies_64();
1695         mutex_unlock(&df->lock);
1696
1697         return count;
1698 }
1699 static DEVICE_ATTR_RW(trans_stat);
1700
1701 static ssize_t timer_show(struct device *dev,
1702                              struct device_attribute *attr, char *buf)
1703 {
1704         struct devfreq *df = to_devfreq(dev);
1705
1706         if (!df->profile)
1707                 return -EINVAL;
1708
1709         return sprintf(buf, "%s\n", timer_name[df->profile->timer]);
1710 }
1711
1712 static ssize_t timer_store(struct device *dev, struct device_attribute *attr,
1713                               const char *buf, size_t count)
1714 {
1715         struct devfreq *df = to_devfreq(dev);
1716         char str_timer[DEVFREQ_NAME_LEN + 1];
1717         int timer = -1;
1718         int ret = 0, i;
1719
1720         if (!df->governor || !df->profile)
1721                 return -EINVAL;
1722
1723         ret = sscanf(buf, "%16s", str_timer);
1724         if (ret != 1)
1725                 return -EINVAL;
1726
1727         for (i = 0; i < DEVFREQ_TIMER_NUM; i++) {
1728                 if (!strncmp(timer_name[i], str_timer, DEVFREQ_NAME_LEN)) {
1729                         timer = i;
1730                         break;
1731                 }
1732         }
1733
1734         if (timer < 0) {
1735                 ret = -EINVAL;
1736                 goto out;
1737         }
1738
1739         if (df->profile->timer == timer) {
1740                 ret = 0;
1741                 goto out;
1742         }
1743
1744         mutex_lock(&df->lock);
1745         df->profile->timer = timer;
1746         mutex_unlock(&df->lock);
1747
1748         ret = df->governor->event_handler(df, DEVFREQ_GOV_STOP, NULL);
1749         if (ret) {
1750                 dev_warn(dev, "%s: Governor %s not stopped(%d)\n",
1751                          __func__, df->governor->name, ret);
1752                 goto out;
1753         }
1754
1755         ret = df->governor->event_handler(df, DEVFREQ_GOV_START, NULL);
1756         if (ret)
1757                 dev_warn(dev, "%s: Governor %s not started(%d)\n",
1758                          __func__, df->governor->name, ret);
1759 out:
1760         return ret ? ret : count;
1761 }
1762 static DEVICE_ATTR_RW(timer);
1763
1764 static struct attribute *devfreq_attrs[] = {
1765         &dev_attr_name.attr,
1766         &dev_attr_governor.attr,
1767         &dev_attr_available_governors.attr,
1768         &dev_attr_cur_freq.attr,
1769         &dev_attr_available_frequencies.attr,
1770         &dev_attr_target_freq.attr,
1771         &dev_attr_polling_interval.attr,
1772         &dev_attr_min_freq.attr,
1773         &dev_attr_max_freq.attr,
1774         &dev_attr_trans_stat.attr,
1775         &dev_attr_timer.attr,
1776         NULL,
1777 };
1778 ATTRIBUTE_GROUPS(devfreq);
1779
1780 /**
1781  * devfreq_summary_show() - Show the summary of the devfreq devices
1782  * @s:          seq_file instance to show the summary of devfreq devices
1783  * @data:       not used
1784  *
1785  * Show the summary of the devfreq devices via 'devfreq_summary' debugfs file.
1786  * It helps that user can know the detailed information of the devfreq devices.
1787  *
1788  * Return 0 always because it shows the information without any data change.
1789  */
1790 static int devfreq_summary_show(struct seq_file *s, void *data)
1791 {
1792         struct devfreq *devfreq;
1793         struct devfreq *p_devfreq = NULL;
1794         unsigned long cur_freq, min_freq, max_freq;
1795         unsigned int polling_ms;
1796         unsigned int timer;
1797
1798         seq_printf(s, "%-30s %-30s %-15s %-10s %10s %12s %12s %12s\n",
1799                         "dev",
1800                         "parent_dev",
1801                         "governor",
1802                         "timer",
1803                         "polling_ms",
1804                         "cur_freq_Hz",
1805                         "min_freq_Hz",
1806                         "max_freq_Hz");
1807         seq_printf(s, "%30s %30s %15s %10s %10s %12s %12s %12s\n",
1808                         "------------------------------",
1809                         "------------------------------",
1810                         "---------------",
1811                         "----------",
1812                         "----------",
1813                         "------------",
1814                         "------------",
1815                         "------------");
1816
1817         mutex_lock(&devfreq_list_lock);
1818
1819         list_for_each_entry_reverse(devfreq, &devfreq_list, node) {
1820 #if IS_ENABLED(CONFIG_DEVFREQ_GOV_PASSIVE)
1821                 if (!strncmp(devfreq->governor_name, DEVFREQ_GOV_PASSIVE,
1822                                                         DEVFREQ_NAME_LEN)) {
1823                         struct devfreq_passive_data *data = devfreq->data;
1824
1825                         if (data)
1826                                 p_devfreq = data->parent;
1827                 } else {
1828                         p_devfreq = NULL;
1829                 }
1830 #endif
1831
1832                 mutex_lock(&devfreq->lock);
1833                 cur_freq = devfreq->previous_freq;
1834                 get_freq_range(devfreq, &min_freq, &max_freq);
1835                 polling_ms = devfreq->profile->polling_ms;
1836                 timer = devfreq->profile->timer;
1837                 mutex_unlock(&devfreq->lock);
1838
1839                 seq_printf(s,
1840                         "%-30s %-30s %-15s %-10s %10d %12ld %12ld %12ld\n",
1841                         dev_name(&devfreq->dev),
1842                         p_devfreq ? dev_name(&p_devfreq->dev) : "null",
1843                         devfreq->governor_name,
1844                         polling_ms ? timer_name[timer] : "null",
1845                         polling_ms,
1846                         cur_freq,
1847                         min_freq,
1848                         max_freq);
1849         }
1850
1851         mutex_unlock(&devfreq_list_lock);
1852
1853         return 0;
1854 }
1855 DEFINE_SHOW_ATTRIBUTE(devfreq_summary);
1856
1857 static int __init devfreq_init(void)
1858 {
1859         devfreq_class = class_create(THIS_MODULE, "devfreq");
1860         if (IS_ERR(devfreq_class)) {
1861                 pr_err("%s: couldn't create class\n", __FILE__);
1862                 return PTR_ERR(devfreq_class);
1863         }
1864
1865         devfreq_wq = create_freezable_workqueue("devfreq_wq");
1866         if (!devfreq_wq) {
1867                 class_destroy(devfreq_class);
1868                 pr_err("%s: couldn't create workqueue\n", __FILE__);
1869                 return -ENOMEM;
1870         }
1871         devfreq_class->dev_groups = devfreq_groups;
1872
1873         devfreq_debugfs = debugfs_create_dir("devfreq", NULL);
1874         debugfs_create_file("devfreq_summary", 0444,
1875                                 devfreq_debugfs, NULL,
1876                                 &devfreq_summary_fops);
1877
1878         return 0;
1879 }
1880 subsys_initcall(devfreq_init);
1881
1882 /*
1883  * The following are helper functions for devfreq user device drivers with
1884  * OPP framework.
1885  */
1886
1887 /**
1888  * devfreq_recommended_opp() - Helper function to get proper OPP for the
1889  *                           freq value given to target callback.
1890  * @dev:        The devfreq user device. (parent of devfreq)
1891  * @freq:       The frequency given to target function
1892  * @flags:      Flags handed from devfreq framework.
1893  *
1894  * The callers are required to call dev_pm_opp_put() for the returned OPP after
1895  * use.
1896  */
1897 struct dev_pm_opp *devfreq_recommended_opp(struct device *dev,
1898                                            unsigned long *freq,
1899                                            u32 flags)
1900 {
1901         struct dev_pm_opp *opp;
1902
1903         if (flags & DEVFREQ_FLAG_LEAST_UPPER_BOUND) {
1904                 /* The freq is an upper bound. opp should be lower */
1905                 opp = dev_pm_opp_find_freq_floor(dev, freq);
1906
1907                 /* If not available, use the closest opp */
1908                 if (opp == ERR_PTR(-ERANGE))
1909                         opp = dev_pm_opp_find_freq_ceil(dev, freq);
1910         } else {
1911                 /* The freq is an lower bound. opp should be higher */
1912                 opp = dev_pm_opp_find_freq_ceil(dev, freq);
1913
1914                 /* If not available, use the closest opp */
1915                 if (opp == ERR_PTR(-ERANGE))
1916                         opp = dev_pm_opp_find_freq_floor(dev, freq);
1917         }
1918
1919         return opp;
1920 }
1921 EXPORT_SYMBOL(devfreq_recommended_opp);
1922
1923 /**
1924  * devfreq_register_opp_notifier() - Helper function to get devfreq notified
1925  *                                   for any changes in the OPP availability
1926  *                                   changes
1927  * @dev:        The devfreq user device. (parent of devfreq)
1928  * @devfreq:    The devfreq object.
1929  */
1930 int devfreq_register_opp_notifier(struct device *dev, struct devfreq *devfreq)
1931 {
1932         return dev_pm_opp_register_notifier(dev, &devfreq->nb);
1933 }
1934 EXPORT_SYMBOL(devfreq_register_opp_notifier);
1935
1936 /**
1937  * devfreq_unregister_opp_notifier() - Helper function to stop getting devfreq
1938  *                                     notified for any changes in the OPP
1939  *                                     availability changes anymore.
1940  * @dev:        The devfreq user device. (parent of devfreq)
1941  * @devfreq:    The devfreq object.
1942  *
1943  * At exit() callback of devfreq_dev_profile, this must be included if
1944  * devfreq_recommended_opp is used.
1945  */
1946 int devfreq_unregister_opp_notifier(struct device *dev, struct devfreq *devfreq)
1947 {
1948         return dev_pm_opp_unregister_notifier(dev, &devfreq->nb);
1949 }
1950 EXPORT_SYMBOL(devfreq_unregister_opp_notifier);
1951
1952 static void devm_devfreq_opp_release(struct device *dev, void *res)
1953 {
1954         devfreq_unregister_opp_notifier(dev, *(struct devfreq **)res);
1955 }
1956
1957 /**
1958  * devm_devfreq_register_opp_notifier() - Resource-managed
1959  *                                        devfreq_register_opp_notifier()
1960  * @dev:        The devfreq user device. (parent of devfreq)
1961  * @devfreq:    The devfreq object.
1962  */
1963 int devm_devfreq_register_opp_notifier(struct device *dev,
1964                                        struct devfreq *devfreq)
1965 {
1966         struct devfreq **ptr;
1967         int ret;
1968
1969         ptr = devres_alloc(devm_devfreq_opp_release, sizeof(*ptr), GFP_KERNEL);
1970         if (!ptr)
1971                 return -ENOMEM;
1972
1973         ret = devfreq_register_opp_notifier(dev, devfreq);
1974         if (ret) {
1975                 devres_free(ptr);
1976                 return ret;
1977         }
1978
1979         *ptr = devfreq;
1980         devres_add(dev, ptr);
1981
1982         return 0;
1983 }
1984 EXPORT_SYMBOL(devm_devfreq_register_opp_notifier);
1985
1986 /**
1987  * devm_devfreq_unregister_opp_notifier() - Resource-managed
1988  *                                          devfreq_unregister_opp_notifier()
1989  * @dev:        The devfreq user device. (parent of devfreq)
1990  * @devfreq:    The devfreq object.
1991  */
1992 void devm_devfreq_unregister_opp_notifier(struct device *dev,
1993                                          struct devfreq *devfreq)
1994 {
1995         WARN_ON(devres_release(dev, devm_devfreq_opp_release,
1996                                devm_devfreq_dev_match, devfreq));
1997 }
1998 EXPORT_SYMBOL(devm_devfreq_unregister_opp_notifier);
1999
2000 /**
2001  * devfreq_register_notifier() - Register a driver with devfreq
2002  * @devfreq:    The devfreq object.
2003  * @nb:         The notifier block to register.
2004  * @list:       DEVFREQ_TRANSITION_NOTIFIER.
2005  */
2006 int devfreq_register_notifier(struct devfreq *devfreq,
2007                               struct notifier_block *nb,
2008                               unsigned int list)
2009 {
2010         int ret = 0;
2011
2012         if (!devfreq)
2013                 return -EINVAL;
2014
2015         switch (list) {
2016         case DEVFREQ_TRANSITION_NOTIFIER:
2017                 ret = srcu_notifier_chain_register(
2018                                 &devfreq->transition_notifier_list, nb);
2019                 break;
2020         default:
2021                 ret = -EINVAL;
2022         }
2023
2024         return ret;
2025 }
2026 EXPORT_SYMBOL(devfreq_register_notifier);
2027
2028 /*
2029  * devfreq_unregister_notifier() - Unregister a driver with devfreq
2030  * @devfreq:    The devfreq object.
2031  * @nb:         The notifier block to be unregistered.
2032  * @list:       DEVFREQ_TRANSITION_NOTIFIER.
2033  */
2034 int devfreq_unregister_notifier(struct devfreq *devfreq,
2035                                 struct notifier_block *nb,
2036                                 unsigned int list)
2037 {
2038         int ret = 0;
2039
2040         if (!devfreq)
2041                 return -EINVAL;
2042
2043         switch (list) {
2044         case DEVFREQ_TRANSITION_NOTIFIER:
2045                 ret = srcu_notifier_chain_unregister(
2046                                 &devfreq->transition_notifier_list, nb);
2047                 break;
2048         default:
2049                 ret = -EINVAL;
2050         }
2051
2052         return ret;
2053 }
2054 EXPORT_SYMBOL(devfreq_unregister_notifier);
2055
2056 struct devfreq_notifier_devres {
2057         struct devfreq *devfreq;
2058         struct notifier_block *nb;
2059         unsigned int list;
2060 };
2061
2062 static void devm_devfreq_notifier_release(struct device *dev, void *res)
2063 {
2064         struct devfreq_notifier_devres *this = res;
2065
2066         devfreq_unregister_notifier(this->devfreq, this->nb, this->list);
2067 }
2068
2069 /**
2070  * devm_devfreq_register_notifier()
2071  *      - Resource-managed devfreq_register_notifier()
2072  * @dev:        The devfreq user device. (parent of devfreq)
2073  * @devfreq:    The devfreq object.
2074  * @nb:         The notifier block to be unregistered.
2075  * @list:       DEVFREQ_TRANSITION_NOTIFIER.
2076  */
2077 int devm_devfreq_register_notifier(struct device *dev,
2078                                 struct devfreq *devfreq,
2079                                 struct notifier_block *nb,
2080                                 unsigned int list)
2081 {
2082         struct devfreq_notifier_devres *ptr;
2083         int ret;
2084
2085         ptr = devres_alloc(devm_devfreq_notifier_release, sizeof(*ptr),
2086                                 GFP_KERNEL);
2087         if (!ptr)
2088                 return -ENOMEM;
2089
2090         ret = devfreq_register_notifier(devfreq, nb, list);
2091         if (ret) {
2092                 devres_free(ptr);
2093                 return ret;
2094         }
2095
2096         ptr->devfreq = devfreq;
2097         ptr->nb = nb;
2098         ptr->list = list;
2099         devres_add(dev, ptr);
2100
2101         return 0;
2102 }
2103 EXPORT_SYMBOL(devm_devfreq_register_notifier);
2104
2105 /**
2106  * devm_devfreq_unregister_notifier()
2107  *      - Resource-managed devfreq_unregister_notifier()
2108  * @dev:        The devfreq user device. (parent of devfreq)
2109  * @devfreq:    The devfreq object.
2110  * @nb:         The notifier block to be unregistered.
2111  * @list:       DEVFREQ_TRANSITION_NOTIFIER.
2112  */
2113 void devm_devfreq_unregister_notifier(struct device *dev,
2114                                       struct devfreq *devfreq,
2115                                       struct notifier_block *nb,
2116                                       unsigned int list)
2117 {
2118         WARN_ON(devres_release(dev, devm_devfreq_notifier_release,
2119                                devm_devfreq_dev_match, devfreq));
2120 }
2121 EXPORT_SYMBOL(devm_devfreq_unregister_notifier);