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 <myungjoo.ham@samsung.com>
   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 = new_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                 mutex_unlock(&devfreq->lock);
 792                 err = -EINVAL;
 793                 goto err_dev;
 794         }
 795
 796         if (!devfreq->profile->max_state && !devfreq->profile->freq_table) {
 797                 mutex_unlock(&devfreq->lock);
 798                 err = set_freq_table(devfreq);
 799                 if (err < 0)
 800                         goto err_dev;
 801                 mutex_lock(&devfreq->lock);
 802         }
 803
 804         devfreq->scaling_min_freq = find_available_min_freq(devfreq);
 805         if (!devfreq->scaling_min_freq) {
 806                 mutex_unlock(&devfreq->lock);
 807                 err = -EINVAL;
 808                 goto err_dev;
 809         }
 810
 811         devfreq->scaling_max_freq = find_available_max_freq(devfreq);
 812         if (!devfreq->scaling_max_freq) {
 813                 mutex_unlock(&devfreq->lock);
 814                 err = -EINVAL;
 815                 goto err_dev;
 816         }
 817
 818         devfreq->suspend_freq = dev_pm_opp_get_suspend_opp_freq(dev);
 819         atomic_set(&devfreq->suspend_count, 0);
 820
 821         dev_set_name(&devfreq->dev, "%s", dev_name(dev));
 822         err = device_register(&devfreq->dev);
 823         if (err) {
 824                 mutex_unlock(&devfreq->lock);
 825                 put_device(&devfreq->dev);
 826                 goto err_out;
 827         }
 828
 829         devfreq->stats.trans_table = devm_kzalloc(&devfreq->dev,
 830                         array3_size(sizeof(unsigned int),
 831                                     devfreq->profile->max_state,
 832                                     devfreq->profile->max_state),
 833                         GFP_KERNEL);
 834         if (!devfreq->stats.trans_table) {
 835                 mutex_unlock(&devfreq->lock);
 836                 err = -ENOMEM;
 837                 goto err_devfreq;
 838         }
 839
 840         devfreq->stats.time_in_state = devm_kcalloc(&devfreq->dev,
 841                         devfreq->profile->max_state,
 842                         sizeof(*devfreq->stats.time_in_state),
 843                         GFP_KERNEL);
 844         if (!devfreq->stats.time_in_state) {
 845                 mutex_unlock(&devfreq->lock);
 846                 err = -ENOMEM;
 847                 goto err_devfreq;
 848         }
 849
 850         devfreq->stats.total_trans = 0;
 851         devfreq->stats.last_update = get_jiffies_64();
 852
 853         srcu_init_notifier_head(&devfreq->transition_notifier_list);
 854
 855         mutex_unlock(&devfreq->lock);
 856
 857         err = dev_pm_qos_add_request(dev, &devfreq->user_min_freq_req,
 858                                      DEV_PM_QOS_MIN_FREQUENCY, 0);
 859         if (err < 0)
 860                 goto err_devfreq;
 861         err = dev_pm_qos_add_request(dev, &devfreq->user_max_freq_req,
 862                                      DEV_PM_QOS_MAX_FREQUENCY,
 863                                      PM_QOS_MAX_FREQUENCY_DEFAULT_VALUE);
 864         if (err < 0)
 865                 goto err_devfreq;
 866
 867         devfreq->nb_min.notifier_call = qos_min_notifier_call;
 868         err = dev_pm_qos_add_notifier(devfreq->dev.parent, &devfreq->nb_min,
 869                                       DEV_PM_QOS_MIN_FREQUENCY);
 870         if (err)
 871                 goto err_devfreq;
 872
 873         devfreq->nb_max.notifier_call = qos_max_notifier_call;
 874         err = dev_pm_qos_add_notifier(devfreq->dev.parent, &devfreq->nb_max,
 875                                       DEV_PM_QOS_MAX_FREQUENCY);
 876         if (err)
 877                 goto err_devfreq;
 878
 879         mutex_lock(&devfreq_list_lock);
 880
 881         governor = try_then_request_governor(devfreq->governor_name);
 882         if (IS_ERR(governor)) {
 883                 dev_err(dev, "%s: Unable to find governor for the device\n",
 884                         __func__);
 885                 err = PTR_ERR(governor);
 886                 goto err_init;
 887         }
 888
 889         devfreq->governor = governor;
 890         err = devfreq->governor->event_handler(devfreq, DEVFREQ_GOV_START,
 891                                                 NULL);
 892         if (err) {
 893                 dev_err(dev, "%s: Unable to start governor for the device\n",
 894                         __func__);
 895                 goto err_init;
 896         }
 897
 898         list_add(&devfreq->node, &devfreq_list);
 899
 900         mutex_unlock(&devfreq_list_lock);
 901
 902         return devfreq;
 903
 904 err_init:
 905         mutex_unlock(&devfreq_list_lock);
 906 err_devfreq:
 907         devfreq_remove_device(devfreq);
 908         devfreq = NULL;
 909 err_dev:
 910         kfree(devfreq);
 911 err_out:
 912         return ERR_PTR(err);
 913 }
 914 EXPORT_SYMBOL(devfreq_add_device);
 915
 916 /**
 917  * devfreq_remove_device() - Remove devfreq feature from a device.
 918  * @devfreq:    the devfreq instance to be removed
 919  *
 920  * The opposite of devfreq_add_device().
 921  */
 922 int devfreq_remove_device(struct devfreq *devfreq)
 923 {
 924         if (!devfreq)
 925                 return -EINVAL;
 926
 927         if (devfreq->governor)
 928                 devfreq->governor->event_handler(devfreq,
 929                                                  DEVFREQ_GOV_STOP, NULL);
 930         device_unregister(&devfreq->dev);
 931
 932         return 0;
 933 }
 934 EXPORT_SYMBOL(devfreq_remove_device);
 935
 936 static int devm_devfreq_dev_match(struct device *dev, void *res, void *data)
 937 {
 938         struct devfreq **r = res;
 939
 940         if (WARN_ON(!r || !*r))
 941                 return 0;
 942
 943         return *r == data;
 944 }
 945
 946 static void devm_devfreq_dev_release(struct device *dev, void *res)
 947 {
 948         devfreq_remove_device(*(struct devfreq **)res);
 949 }
 950
 951 /**
 952  * devm_devfreq_add_device() - Resource-managed devfreq_add_device()
 953  * @dev:        the device to add devfreq feature.
 954  * @profile:    device-specific profile to run devfreq.
 955  * @governor_name:      name of the policy to choose frequency.
 956  * @data:       private data for the governor. The devfreq framework does not
 957  *              touch this value.
 958  *
 959  * This function manages automatically the memory of devfreq device using device
 960  * resource management and simplify the free operation for memory of devfreq
 961  * device.
 962  */
 963 struct devfreq *devm_devfreq_add_device(struct device *dev,
 964                                         struct devfreq_dev_profile *profile,
 965                                         const char *governor_name,
 966                                         void *data)
 967 {
 968         struct devfreq **ptr, *devfreq;
 969
 970         ptr = devres_alloc(devm_devfreq_dev_release, sizeof(*ptr), GFP_KERNEL);
 971         if (!ptr)
 972                 return ERR_PTR(-ENOMEM);
 973
 974         devfreq = devfreq_add_device(dev, profile, governor_name, data);
 975         if (IS_ERR(devfreq)) {
 976                 devres_free(ptr);
 977                 return devfreq;
 978         }
 979
 980         *ptr = devfreq;
 981         devres_add(dev, ptr);
 982
 983         return devfreq;
 984 }
 985 EXPORT_SYMBOL(devm_devfreq_add_device);
 986
 987 #ifdef CONFIG_OF
 988 /*
 989  * devfreq_get_devfreq_by_node - Get the devfreq device from devicetree
 990  * @node - pointer to device_node
 991  *
 992  * return the instance of devfreq device
 993  */
 994 struct devfreq *devfreq_get_devfreq_by_node(struct device_node *node)
 995 {
 996         struct devfreq *devfreq;
 997
 998         if (!node)
 999                 return ERR_PTR(-EINVAL);
1000
1001         mutex_lock(&devfreq_list_lock);
1002         list_for_each_entry(devfreq, &devfreq_list, node) {
1003                 if (devfreq->dev.parent
1004                         && devfreq->dev.parent->of_node == node) {
1005                         mutex_unlock(&devfreq_list_lock);
1006                         return devfreq;
1007                 }
1008         }
1009         mutex_unlock(&devfreq_list_lock);
1010
1011         return ERR_PTR(-ENODEV);
1012 }
1013
1014 /*
1015  * devfreq_get_devfreq_by_phandle - Get the devfreq device from devicetree
1016  * @dev - instance to the given device
1017  * @phandle_name - name of property holding a phandle value
1018  * @index - index into list of devfreq
1019  *
1020  * return the instance of devfreq device
1021  */
1022 struct devfreq *devfreq_get_devfreq_by_phandle(struct device *dev,
1023                                         const char *phandle_name, int index)
1024 {
1025         struct device_node *node;
1026         struct devfreq *devfreq;
1027
1028         if (!dev || !phandle_name)
1029                 return ERR_PTR(-EINVAL);
1030
1031         if (!dev->of_node)
1032                 return ERR_PTR(-EINVAL);
1033
1034         node = of_parse_phandle(dev->of_node, phandle_name, index);
1035         if (!node)
1036                 return ERR_PTR(-ENODEV);
1037
1038         devfreq = devfreq_get_devfreq_by_node(node);
1039         of_node_put(node);
1040
1041         return devfreq;
1042 }
1043
1044 #else
1045 struct devfreq *devfreq_get_devfreq_by_node(struct device_node *node)
1046 {
1047         return ERR_PTR(-ENODEV);
1048 }
1049
1050 struct devfreq *devfreq_get_devfreq_by_phandle(struct device *dev,
1051                                         const char *phandle_name, int index)
1052 {
1053         return ERR_PTR(-ENODEV);
1054 }
1055 #endif /* CONFIG_OF */
1056 EXPORT_SYMBOL_GPL(devfreq_get_devfreq_by_node);
1057 EXPORT_SYMBOL_GPL(devfreq_get_devfreq_by_phandle);
1058
1059 /**
1060  * devm_devfreq_remove_device() - Resource-managed devfreq_remove_device()
1061  * @dev:        the device from which to remove devfreq feature.
1062  * @devfreq:    the devfreq instance to be removed
1063  */
1064 void devm_devfreq_remove_device(struct device *dev, struct devfreq *devfreq)
1065 {
1066         WARN_ON(devres_release(dev, devm_devfreq_dev_release,
1067                                devm_devfreq_dev_match, devfreq));
1068 }
1069 EXPORT_SYMBOL(devm_devfreq_remove_device);
1070
1071 /**
1072  * devfreq_suspend_device() - Suspend devfreq of a device.
1073  * @devfreq: the devfreq instance to be suspended
1074  *
1075  * This function is intended to be called by the pm callbacks
1076  * (e.g., runtime_suspend, suspend) of the device driver that
1077  * holds the devfreq.
1078  */
1079 int devfreq_suspend_device(struct devfreq *devfreq)
1080 {
1081         int ret;
1082
1083         if (!devfreq)
1084                 return -EINVAL;
1085
1086         if (atomic_inc_return(&devfreq->suspend_count) > 1)
1087                 return 0;
1088
1089         if (devfreq->governor) {
1090                 ret = devfreq->governor->event_handler(devfreq,
1091                                         DEVFREQ_GOV_SUSPEND, NULL);
1092                 if (ret)
1093                         return ret;
1094         }
1095
1096         if (devfreq->suspend_freq) {
1097                 mutex_lock(&devfreq->lock);
1098                 ret = devfreq_set_target(devfreq, devfreq->suspend_freq, 0);
1099                 mutex_unlock(&devfreq->lock);
1100                 if (ret)
1101                         return ret;
1102         }
1103
1104         return 0;
1105 }
1106 EXPORT_SYMBOL(devfreq_suspend_device);
1107
1108 /**
1109  * devfreq_resume_device() - Resume devfreq of a device.
1110  * @devfreq: the devfreq instance to be resumed
1111  *
1112  * This function is intended to be called by the pm callbacks
1113  * (e.g., runtime_resume, resume) of the device driver that
1114  * holds the devfreq.
1115  */
1116 int devfreq_resume_device(struct devfreq *devfreq)
1117 {
1118         int ret;
1119
1120         if (!devfreq)
1121                 return -EINVAL;
1122
1123         if (atomic_dec_return(&devfreq->suspend_count) >= 1)
1124                 return 0;
1125
1126         if (devfreq->resume_freq) {
1127                 mutex_lock(&devfreq->lock);
1128                 ret = devfreq_set_target(devfreq, devfreq->resume_freq, 0);
1129                 mutex_unlock(&devfreq->lock);
1130                 if (ret)
1131                         return ret;
1132         }
1133
1134         if (devfreq->governor) {
1135                 ret = devfreq->governor->event_handler(devfreq,
1136                                         DEVFREQ_GOV_RESUME, NULL);
1137                 if (ret)
1138                         return ret;
1139         }
1140
1141         return 0;
1142 }
1143 EXPORT_SYMBOL(devfreq_resume_device);
1144
1145 /**
1146  * devfreq_suspend() - Suspend devfreq governors and devices
1147  *
1148  * Called during system wide Suspend/Hibernate cycles for suspending governors
1149  * and devices preserving the state for resume. On some platforms the devfreq
1150  * device must have precise state (frequency) after resume in order to provide
1151  * fully operating setup.
1152  */
1153 void devfreq_suspend(void)
1154 {
1155         struct devfreq *devfreq;
1156         int ret;
1157
1158         mutex_lock(&devfreq_list_lock);
1159         list_for_each_entry(devfreq, &devfreq_list, node) {
1160                 ret = devfreq_suspend_device(devfreq);
1161                 if (ret)
1162                         dev_err(&devfreq->dev,
1163                                 "failed to suspend devfreq device\n");
1164         }
1165         mutex_unlock(&devfreq_list_lock);
1166 }
1167
1168 /**
1169  * devfreq_resume() - Resume devfreq governors and devices
1170  *
1171  * Called during system wide Suspend/Hibernate cycle for resuming governors and
1172  * devices that are suspended with devfreq_suspend().
1173  */
1174 void devfreq_resume(void)
1175 {
1176         struct devfreq *devfreq;
1177         int ret;
1178
1179         mutex_lock(&devfreq_list_lock);
1180         list_for_each_entry(devfreq, &devfreq_list, node) {
1181                 ret = devfreq_resume_device(devfreq);
1182                 if (ret)
1183                         dev_warn(&devfreq->dev,
1184                                  "failed to resume devfreq device\n");
1185         }
1186         mutex_unlock(&devfreq_list_lock);
1187 }
1188
1189 /**
1190  * devfreq_add_governor() - Add devfreq governor
1191  * @governor:   the devfreq governor to be added
1192  */
1193 int devfreq_add_governor(struct devfreq_governor *governor)
1194 {
1195         struct devfreq_governor *g;
1196         struct devfreq *devfreq;
1197         int err = 0;
1198
1199         if (!governor) {
1200                 pr_err("%s: Invalid parameters.\n", __func__);
1201                 return -EINVAL;
1202         }
1203
1204         mutex_lock(&devfreq_list_lock);
1205         g = find_devfreq_governor(governor->name);
1206         if (!IS_ERR(g)) {
1207                 pr_err("%s: governor %s already registered\n", __func__,
1208                        g->name);
1209                 err = -EINVAL;
1210                 goto err_out;
1211         }
1212
1213         list_add(&governor->node, &devfreq_governor_list);
1214
1215         list_for_each_entry(devfreq, &devfreq_list, node) {
1216                 int ret = 0;
1217                 struct device *dev = devfreq->dev.parent;
1218
1219                 if (!strncmp(devfreq->governor_name, governor->name,
1220                              DEVFREQ_NAME_LEN)) {
1221                         /* The following should never occur */
1222                         if (devfreq->governor) {
1223                                 dev_warn(dev,
1224                                          "%s: Governor %s already present\n",
1225                                          __func__, devfreq->governor->name);
1226                                 ret = devfreq->governor->event_handler(devfreq,
1227                                                         DEVFREQ_GOV_STOP, NULL);
1228                                 if (ret) {
1229                                         dev_warn(dev,
1230                                                  "%s: Governor %s stop = %d\n",
1231                                                  __func__,
1232                                                  devfreq->governor->name, ret);
1233                                 }
1234                                 /* Fall through */
1235                         }
1236                         devfreq->governor = governor;
1237                         ret = devfreq->governor->event_handler(devfreq,
1238                                                 DEVFREQ_GOV_START, NULL);
1239                         if (ret) {
1240                                 dev_warn(dev, "%s: Governor %s start=%d\n",
1241                                          __func__, devfreq->governor->name,
1242                                          ret);
1243                         }
1244                 }
1245         }
1246
1247 err_out:
1248         mutex_unlock(&devfreq_list_lock);
1249
1250         return err;
1251 }
1252 EXPORT_SYMBOL(devfreq_add_governor);
1253
1254 /**
1255  * devfreq_remove_governor() - Remove devfreq feature from a device.
1256  * @governor:   the devfreq governor to be removed
1257  */
1258 int devfreq_remove_governor(struct devfreq_governor *governor)
1259 {
1260         struct devfreq_governor *g;
1261         struct devfreq *devfreq;
1262         int err = 0;
1263
1264         if (!governor) {
1265                 pr_err("%s: Invalid parameters.\n", __func__);
1266                 return -EINVAL;
1267         }
1268
1269         mutex_lock(&devfreq_list_lock);
1270         g = find_devfreq_governor(governor->name);
1271         if (IS_ERR(g)) {
1272                 pr_err("%s: governor %s not registered\n", __func__,
1273                        governor->name);
1274                 err = PTR_ERR(g);
1275                 goto err_out;
1276         }
1277         list_for_each_entry(devfreq, &devfreq_list, node) {
1278                 int ret;
1279                 struct device *dev = devfreq->dev.parent;
1280
1281                 if (!strncmp(devfreq->governor_name, governor->name,
1282                              DEVFREQ_NAME_LEN)) {
1283                         /* we should have a devfreq governor! */
1284                         if (!devfreq->governor) {
1285                                 dev_warn(dev, "%s: Governor %s NOT present\n",
1286                                          __func__, governor->name);
1287                                 continue;
1288                                 /* Fall through */
1289                         }
1290                         ret = devfreq->governor->event_handler(devfreq,
1291                                                 DEVFREQ_GOV_STOP, NULL);
1292                         if (ret) {
1293                                 dev_warn(dev, "%s: Governor %s stop=%d\n",
1294                                          __func__, devfreq->governor->name,
1295                                          ret);
1296                         }
1297                         devfreq->governor = NULL;
1298                 }
1299         }
1300
1301         list_del(&governor->node);
1302 err_out:
1303         mutex_unlock(&devfreq_list_lock);
1304
1305         return err;
1306 }
1307 EXPORT_SYMBOL(devfreq_remove_governor);
1308
1309 static ssize_t name_show(struct device *dev,
1310                         struct device_attribute *attr, char *buf)
1311 {
1312         struct devfreq *df = to_devfreq(dev);
1313         return sprintf(buf, "%s\n", dev_name(df->dev.parent));
1314 }
1315 static DEVICE_ATTR_RO(name);
1316
1317 static ssize_t governor_show(struct device *dev,
1318                              struct device_attribute *attr, char *buf)
1319 {
1320         struct devfreq *df = to_devfreq(dev);
1321
1322         if (!df->governor)
1323                 return -EINVAL;
1324
1325         return sprintf(buf, "%s\n", df->governor->name);
1326 }
1327
1328 static ssize_t governor_store(struct device *dev, struct device_attribute *attr,
1329                               const char *buf, size_t count)
1330 {
1331         struct devfreq *df = to_devfreq(dev);
1332         int ret;
1333         char str_governor[DEVFREQ_NAME_LEN + 1];
1334         const struct devfreq_governor *governor, *prev_governor;
1335
1336         if (!df->governor)
1337                 return -EINVAL;
1338
1339         ret = sscanf(buf, "%" __stringify(DEVFREQ_NAME_LEN) "s", str_governor);
1340         if (ret != 1)
1341                 return -EINVAL;
1342
1343         mutex_lock(&devfreq_list_lock);
1344         governor = try_then_request_governor(str_governor);
1345         if (IS_ERR(governor)) {
1346                 ret = PTR_ERR(governor);
1347                 goto out;
1348         }
1349         if (df->governor == governor) {
1350                 ret = 0;
1351                 goto out;
1352         } else if (df->governor->immutable || governor->immutable) {
1353                 ret = -EINVAL;
1354                 goto out;
1355         }
1356
1357         ret = df->governor->event_handler(df, DEVFREQ_GOV_STOP, NULL);
1358         if (ret) {
1359                 dev_warn(dev, "%s: Governor %s not stopped(%d)\n",
1360                          __func__, df->governor->name, ret);
1361                 goto out;
1362         }
1363
1364         prev_governor = df->governor;
1365         df->governor = governor;
1366         strncpy(df->governor_name, governor->name, DEVFREQ_NAME_LEN);
1367         ret = df->governor->event_handler(df, DEVFREQ_GOV_START, NULL);
1368         if (ret) {
1369                 dev_warn(dev, "%s: Governor %s not started(%d)\n",
1370                          __func__, df->governor->name, ret);
1371                 df->governor = prev_governor;
1372                 strncpy(df->governor_name, prev_governor->name,
1373                         DEVFREQ_NAME_LEN);
1374                 ret = df->governor->event_handler(df, DEVFREQ_GOV_START, NULL);
1375                 if (ret) {
1376                         dev_err(dev,
1377                                 "%s: reverting to Governor %s failed (%d)\n",
1378                                 __func__, df->governor_name, ret);
1379                         df->governor = NULL;
1380                 }
1381         }
1382 out:
1383         mutex_unlock(&devfreq_list_lock);
1384
1385         if (!ret)
1386                 ret = count;
1387         return ret;
1388 }
1389 static DEVICE_ATTR_RW(governor);
1390
1391 static ssize_t available_governors_show(struct device *d,
1392                                         struct device_attribute *attr,
1393                                         char *buf)
1394 {
1395         struct devfreq *df = to_devfreq(d);
1396         ssize_t count = 0;
1397
1398         if (!df->governor)
1399                 return -EINVAL;
1400
1401         mutex_lock(&devfreq_list_lock);
1402
1403         /*
1404          * The devfreq with immutable governor (e.g., passive) shows
1405          * only own governor.
1406          */
1407         if (df->governor->immutable) {
1408                 count = scnprintf(&buf[count], DEVFREQ_NAME_LEN,
1409                                   "%s ", df->governor_name);
1410         /*
1411          * The devfreq device shows the registered governor except for
1412          * immutable governors such as passive governor .
1413          */
1414         } else {
1415                 struct devfreq_governor *governor;
1416
1417                 list_for_each_entry(governor, &devfreq_governor_list, node) {
1418                         if (governor->immutable)
1419                                 continue;
1420                         count += scnprintf(&buf[count], (PAGE_SIZE - count - 2),
1421                                            "%s ", governor->name);
1422                 }
1423         }
1424
1425         mutex_unlock(&devfreq_list_lock);
1426
1427         /* Truncate the trailing space */
1428         if (count)
1429                 count--;
1430
1431         count += sprintf(&buf[count], "\n");
1432
1433         return count;
1434 }
1435 static DEVICE_ATTR_RO(available_governors);
1436
1437 static ssize_t cur_freq_show(struct device *dev, struct device_attribute *attr,
1438                              char *buf)
1439 {
1440         unsigned long freq;
1441         struct devfreq *df = to_devfreq(dev);
1442
1443         if (!df->profile)
1444                 return -EINVAL;
1445
1446         if (df->profile->get_cur_freq &&
1447                 !df->profile->get_cur_freq(df->dev.parent, &freq))
1448                 return sprintf(buf, "%lu\n", freq);
1449
1450         return sprintf(buf, "%lu\n", df->previous_freq);
1451 }
1452 static DEVICE_ATTR_RO(cur_freq);
1453
1454 static ssize_t target_freq_show(struct device *dev,
1455                                 struct device_attribute *attr, char *buf)
1456 {
1457         struct devfreq *df = to_devfreq(dev);
1458
1459         return sprintf(buf, "%lu\n", df->previous_freq);
1460 }
1461 static DEVICE_ATTR_RO(target_freq);
1462
1463 static ssize_t polling_interval_show(struct device *dev,
1464                                      struct device_attribute *attr, char *buf)
1465 {
1466         struct devfreq *df = to_devfreq(dev);
1467
1468         if (!df->profile)
1469                 return -EINVAL;
1470
1471         return sprintf(buf, "%d\n", df->profile->polling_ms);
1472 }
1473
1474 static ssize_t polling_interval_store(struct device *dev,
1475                                       struct device_attribute *attr,
1476                                       const char *buf, size_t count)
1477 {
1478         struct devfreq *df = to_devfreq(dev);
1479         unsigned int value;
1480         int ret;
1481
1482         if (!df->governor)
1483                 return -EINVAL;
1484
1485         ret = sscanf(buf, "%u", &value);
1486         if (ret != 1)
1487                 return -EINVAL;
1488
1489         df->governor->event_handler(df, DEVFREQ_GOV_UPDATE_INTERVAL, &value);
1490         ret = count;
1491
1492         return ret;
1493 }
1494 static DEVICE_ATTR_RW(polling_interval);
1495
1496 static ssize_t min_freq_store(struct device *dev, struct device_attribute *attr,
1497                               const char *buf, size_t count)
1498 {
1499         struct devfreq *df = to_devfreq(dev);
1500         unsigned long value;
1501         int ret;
1502
1503         /*
1504          * Protect against theoretical sysfs writes between
1505          * device_add and dev_pm_qos_add_request
1506          */
1507         if (!dev_pm_qos_request_active(&df->user_min_freq_req))
1508                 return -EAGAIN;
1509
1510         ret = sscanf(buf, "%lu", &value);
1511         if (ret != 1)
1512                 return -EINVAL;
1513
1514         /* Round down to kHz for PM QoS */
1515         ret = dev_pm_qos_update_request(&df->user_min_freq_req,
1516                                         value / HZ_PER_KHZ);
1517         if (ret < 0)
1518                 return ret;
1519
1520         return count;
1521 }
1522
1523 static ssize_t min_freq_show(struct device *dev, struct device_attribute *attr,
1524                              char *buf)
1525 {
1526         struct devfreq *df = to_devfreq(dev);
1527         unsigned long min_freq, max_freq;
1528
1529         mutex_lock(&df->lock);
1530         get_freq_range(df, &min_freq, &max_freq);
1531         mutex_unlock(&df->lock);
1532
1533         return sprintf(buf, "%lu\n", min_freq);
1534 }
1535 static DEVICE_ATTR_RW(min_freq);
1536
1537 static ssize_t max_freq_store(struct device *dev, struct device_attribute *attr,
1538                               const char *buf, size_t count)
1539 {
1540         struct devfreq *df = to_devfreq(dev);
1541         unsigned long value;
1542         int ret;
1543
1544         /*
1545          * Protect against theoretical sysfs writes between
1546          * device_add and dev_pm_qos_add_request
1547          */
1548         if (!dev_pm_qos_request_active(&df->user_max_freq_req))
1549                 return -EINVAL;
1550
1551         ret = sscanf(buf, "%lu", &value);
1552         if (ret != 1)
1553                 return -EINVAL;
1554
1555         /*
1556          * PM QoS frequencies are in kHz so we need to convert. Convert by
1557          * rounding upwards so that the acceptable interval never shrinks.
1558          *
1559          * For example if the user writes "666666666" to sysfs this value will
1560          * be converted to 666667 kHz and back to 666667000 Hz before an OPP
1561          * lookup, this ensures that an OPP of 666666666Hz is still accepted.
1562          *
1563          * A value of zero means "no limit".
1564          */
1565         if (value)
1566                 value = DIV_ROUND_UP(value, HZ_PER_KHZ);
1567         else
1568                 value = PM_QOS_MAX_FREQUENCY_DEFAULT_VALUE;
1569
1570         ret = dev_pm_qos_update_request(&df->user_max_freq_req, value);
1571         if (ret < 0)
1572                 return ret;
1573
1574         return count;
1575 }
1576
1577 static ssize_t max_freq_show(struct device *dev, struct device_attribute *attr,
1578                              char *buf)
1579 {
1580         struct devfreq *df = to_devfreq(dev);
1581         unsigned long min_freq, max_freq;
1582
1583         mutex_lock(&df->lock);
1584         get_freq_range(df, &min_freq, &max_freq);
1585         mutex_unlock(&df->lock);
1586
1587         return sprintf(buf, "%lu\n", max_freq);
1588 }
1589 static DEVICE_ATTR_RW(max_freq);
1590
1591 static ssize_t available_frequencies_show(struct device *d,
1592                                           struct device_attribute *attr,
1593                                           char *buf)
1594 {
1595         struct devfreq *df = to_devfreq(d);
1596         ssize_t count = 0;
1597         int i;
1598
1599         if (!df->profile)
1600                 return -EINVAL;
1601
1602         mutex_lock(&df->lock);
1603
1604         for (i = 0; i < df->profile->max_state; i++)
1605                 count += scnprintf(&buf[count], (PAGE_SIZE - count - 2),
1606                                 "%lu ", df->profile->freq_table[i]);
1607
1608         mutex_unlock(&df->lock);
1609         /* Truncate the trailing space */
1610         if (count)
1611                 count--;
1612
1613         count += sprintf(&buf[count], "\n");
1614
1615         return count;
1616 }
1617 static DEVICE_ATTR_RO(available_frequencies);
1618
1619 static ssize_t trans_stat_show(struct device *dev,
1620                                struct device_attribute *attr, char *buf)
1621 {
1622         struct devfreq *df = to_devfreq(dev);
1623         ssize_t len;
1624         int i, j;
1625         unsigned int max_state;
1626
1627         if (!df->profile)
1628                 return -EINVAL;
1629         max_state = df->profile->max_state;
1630
1631         if (max_state == 0)
1632                 return sprintf(buf, "Not Supported.\n");
1633
1634         mutex_lock(&df->lock);
1635         if (!df->stop_polling &&
1636                         devfreq_update_status(df, df->previous_freq)) {
1637                 mutex_unlock(&df->lock);
1638                 return 0;
1639         }
1640         mutex_unlock(&df->lock);
1641
1642         len = sprintf(buf, "     From  :   To\n");
1643         len += sprintf(buf + len, "           :");
1644         for (i = 0; i < max_state; i++)
1645                 len += sprintf(buf + len, "%10lu",
1646                                 df->profile->freq_table[i]);
1647
1648         len += sprintf(buf + len, "   time(ms)\n");
1649
1650         for (i = 0; i < max_state; i++) {
1651                 if (df->profile->freq_table[i]
1652                                         == df->previous_freq) {
1653                         len += sprintf(buf + len, "*");
1654                 } else {
1655                         len += sprintf(buf + len, " ");
1656                 }
1657                 len += sprintf(buf + len, "%10lu:",
1658                                 df->profile->freq_table[i]);
1659                 for (j = 0; j < max_state; j++)
1660                         len += sprintf(buf + len, "%10u",
1661                                 df->stats.trans_table[(i * max_state) + j]);
1662
1663                 len += sprintf(buf + len, "%10llu\n", (u64)
1664                         jiffies64_to_msecs(df->stats.time_in_state[i]));
1665         }
1666
1667         len += sprintf(buf + len, "Total transition : %u\n",
1668                                         df->stats.total_trans);
1669         return len;
1670 }
1671
1672 static ssize_t trans_stat_store(struct device *dev,
1673                                 struct device_attribute *attr,
1674                                 const char *buf, size_t count)
1675 {
1676         struct devfreq *df = to_devfreq(dev);
1677         int err, value;
1678
1679         if (!df->profile)
1680                 return -EINVAL;
1681
1682         if (df->profile->max_state == 0)
1683                 return count;
1684
1685         err = kstrtoint(buf, 10, &value);
1686         if (err || value != 0)
1687                 return -EINVAL;
1688
1689         mutex_lock(&df->lock);
1690         memset(df->stats.time_in_state, 0, (df->profile->max_state *
1691                                         sizeof(*df->stats.time_in_state)));
1692         memset(df->stats.trans_table, 0, array3_size(sizeof(unsigned int),
1693                                         df->profile->max_state,
1694                                         df->profile->max_state));
1695         df->stats.total_trans = 0;
1696         df->stats.last_update = get_jiffies_64();
1697         mutex_unlock(&df->lock);
1698
1699         return count;
1700 }
1701 static DEVICE_ATTR_RW(trans_stat);
1702
1703 static ssize_t timer_show(struct device *dev,
1704                              struct device_attribute *attr, char *buf)
1705 {
1706         struct devfreq *df = to_devfreq(dev);
1707
1708         if (!df->profile)
1709                 return -EINVAL;
1710
1711         return sprintf(buf, "%s\n", timer_name[df->profile->timer]);
1712 }
1713
1714 static ssize_t timer_store(struct device *dev, struct device_attribute *attr,
1715                               const char *buf, size_t count)
1716 {
1717         struct devfreq *df = to_devfreq(dev);
1718         char str_timer[DEVFREQ_NAME_LEN + 1];
1719         int timer = -1;
1720         int ret = 0, i;
1721
1722         if (!df->governor || !df->profile)
1723                 return -EINVAL;
1724
1725         ret = sscanf(buf, "%16s", str_timer);
1726         if (ret != 1)
1727                 return -EINVAL;
1728
1729         for (i = 0; i < DEVFREQ_TIMER_NUM; i++) {
1730                 if (!strncmp(timer_name[i], str_timer, DEVFREQ_NAME_LEN)) {
1731                         timer = i;
1732                         break;
1733                 }
1734         }
1735
1736         if (timer < 0) {
1737                 ret = -EINVAL;
1738                 goto out;
1739         }
1740
1741         if (df->profile->timer == timer) {
1742                 ret = 0;
1743                 goto out;
1744         }
1745
1746         mutex_lock(&df->lock);
1747         df->profile->timer = timer;
1748         mutex_unlock(&df->lock);
1749
1750         ret = df->governor->event_handler(df, DEVFREQ_GOV_STOP, NULL);
1751         if (ret) {
1752                 dev_warn(dev, "%s: Governor %s not stopped(%d)\n",
1753                          __func__, df->governor->name, ret);
1754                 goto out;
1755         }
1756
1757         ret = df->governor->event_handler(df, DEVFREQ_GOV_START, NULL);
1758         if (ret)
1759                 dev_warn(dev, "%s: Governor %s not started(%d)\n",
1760                          __func__, df->governor->name, ret);
1761 out:
1762         return ret ? ret : count;
1763 }
1764 static DEVICE_ATTR_RW(timer);
1765
1766 static struct attribute *devfreq_attrs[] = {
1767         &dev_attr_name.attr,
1768         &dev_attr_governor.attr,
1769         &dev_attr_available_governors.attr,
1770         &dev_attr_cur_freq.attr,
1771         &dev_attr_available_frequencies.attr,
1772         &dev_attr_target_freq.attr,
1773         &dev_attr_polling_interval.attr,
1774         &dev_attr_min_freq.attr,
1775         &dev_attr_max_freq.attr,
1776         &dev_attr_trans_stat.attr,
1777         &dev_attr_timer.attr,
1778         NULL,
1779 };
1780 ATTRIBUTE_GROUPS(devfreq);
1781
1782 /**
1783  * devfreq_summary_show() - Show the summary of the devfreq devices
1784  * @s:          seq_file instance to show the summary of devfreq devices
1785  * @data:       not used
1786  *
1787  * Show the summary of the devfreq devices via 'devfreq_summary' debugfs file.
1788  * It helps that user can know the detailed information of the devfreq devices.
1789  *
1790  * Return 0 always because it shows the information without any data change.
1791  */
1792 static int devfreq_summary_show(struct seq_file *s, void *data)
1793 {
1794         struct devfreq *devfreq;
1795         struct devfreq *p_devfreq = NULL;
1796         unsigned long cur_freq, min_freq, max_freq;
1797         unsigned int polling_ms;
1798         unsigned int timer;
1799
1800         seq_printf(s, "%-30s %-30s %-15s %-10s %10s %12s %12s %12s\n",
1801                         "dev",
1802                         "parent_dev",
1803                         "governor",
1804                         "timer",
1805                         "polling_ms",
1806                         "cur_freq_Hz",
1807                         "min_freq_Hz",
1808                         "max_freq_Hz");
1809         seq_printf(s, "%30s %30s %15s %10s %10s %12s %12s %12s\n",
1810                         "------------------------------",
1811                         "------------------------------",
1812                         "---------------",
1813                         "----------",
1814                         "----------",
1815                         "------------",
1816                         "------------",
1817                         "------------");
1818
1819         mutex_lock(&devfreq_list_lock);
1820
1821         list_for_each_entry_reverse(devfreq, &devfreq_list, node) {
1822 #if IS_ENABLED(CONFIG_DEVFREQ_GOV_PASSIVE)
1823                 if (!strncmp(devfreq->governor_name, DEVFREQ_GOV_PASSIVE,
1824                                                         DEVFREQ_NAME_LEN)) {
1825                         struct devfreq_passive_data *data = devfreq->data;
1826
1827                         if (data)
1828                                 p_devfreq = data->parent;
1829                 } else {
1830                         p_devfreq = NULL;
1831                 }
1832 #endif
1833
1834                 mutex_lock(&devfreq->lock);
1835                 cur_freq = devfreq->previous_freq;
1836                 get_freq_range(devfreq, &min_freq, &max_freq);
1837                 polling_ms = devfreq->profile->polling_ms;
1838                 timer = devfreq->profile->timer;
1839                 mutex_unlock(&devfreq->lock);
1840
1841                 seq_printf(s,
1842                         "%-30s %-30s %-15s %-10s %10d %12ld %12ld %12ld\n",
1843                         dev_name(&devfreq->dev),
1844                         p_devfreq ? dev_name(&p_devfreq->dev) : "null",
1845                         devfreq->governor_name,
1846                         polling_ms ? timer_name[timer] : "null",
1847                         polling_ms,
1848                         cur_freq,
1849                         min_freq,
1850                         max_freq);
1851         }
1852
1853         mutex_unlock(&devfreq_list_lock);
1854
1855         return 0;
1856 }
1857 DEFINE_SHOW_ATTRIBUTE(devfreq_summary);
1858
1859 static int __init devfreq_init(void)
1860 {
1861         devfreq_class = class_create(THIS_MODULE, "devfreq");
1862         if (IS_ERR(devfreq_class)) {
1863                 pr_err("%s: couldn't create class\n", __FILE__);
1864                 return PTR_ERR(devfreq_class);
1865         }
1866
1867         devfreq_wq = create_freezable_workqueue("devfreq_wq");
1868         if (!devfreq_wq) {
1869                 class_destroy(devfreq_class);
1870                 pr_err("%s: couldn't create workqueue\n", __FILE__);
1871                 return -ENOMEM;
1872         }
1873         devfreq_class->dev_groups = devfreq_groups;
1874
1875         devfreq_debugfs = debugfs_create_dir("devfreq", NULL);
1876         debugfs_create_file("devfreq_summary", 0444,
1877                                 devfreq_debugfs, NULL,
1878                                 &devfreq_summary_fops);
1879
1880         return 0;
1881 }
1882 subsys_initcall(devfreq_init);
1883
1884 /*
1885  * The following are helper functions for devfreq user device drivers with
1886  * OPP framework.
1887  */
1888
1889 /**
1890  * devfreq_recommended_opp() - Helper function to get proper OPP for the
1891  *                           freq value given to target callback.
1892  * @dev:        The devfreq user device. (parent of devfreq)
1893  * @freq:       The frequency given to target function
1894  * @flags:      Flags handed from devfreq framework.
1895  *
1896  * The callers are required to call dev_pm_opp_put() for the returned OPP after
1897  * use.
1898  */
1899 struct dev_pm_opp *devfreq_recommended_opp(struct device *dev,
1900                                            unsigned long *freq,
1901                                            u32 flags)
1902 {
1903         struct dev_pm_opp *opp;
1904
1905         if (flags & DEVFREQ_FLAG_LEAST_UPPER_BOUND) {
1906                 /* The freq is an upper bound. opp should be lower */
1907                 opp = dev_pm_opp_find_freq_floor(dev, freq);
1908
1909                 /* If not available, use the closest opp */
1910                 if (opp == ERR_PTR(-ERANGE))
1911                         opp = dev_pm_opp_find_freq_ceil(dev, freq);
1912         } else {
1913                 /* The freq is an lower bound. opp should be higher */
1914                 opp = dev_pm_opp_find_freq_ceil(dev, freq);
1915
1916                 /* If not available, use the closest opp */
1917                 if (opp == ERR_PTR(-ERANGE))
1918                         opp = dev_pm_opp_find_freq_floor(dev, freq);
1919         }
1920
1921         return opp;
1922 }
1923 EXPORT_SYMBOL(devfreq_recommended_opp);
1924
1925 /**
1926  * devfreq_register_opp_notifier() - Helper function to get devfreq notified
1927  *                                   for any changes in the OPP availability
1928  *                                   changes
1929  * @dev:        The devfreq user device. (parent of devfreq)
1930  * @devfreq:    The devfreq object.
1931  */
1932 int devfreq_register_opp_notifier(struct device *dev, struct devfreq *devfreq)
1933 {
1934         return dev_pm_opp_register_notifier(dev, &devfreq->nb);
1935 }
1936 EXPORT_SYMBOL(devfreq_register_opp_notifier);
1937
1938 /**
1939  * devfreq_unregister_opp_notifier() - Helper function to stop getting devfreq
1940  *                                     notified for any changes in the OPP
1941  *                                     availability changes anymore.
1942  * @dev:        The devfreq user device. (parent of devfreq)
1943  * @devfreq:    The devfreq object.
1944  *
1945  * At exit() callback of devfreq_dev_profile, this must be included if
1946  * devfreq_recommended_opp is used.
1947  */
1948 int devfreq_unregister_opp_notifier(struct device *dev, struct devfreq *devfreq)
1949 {
1950         return dev_pm_opp_unregister_notifier(dev, &devfreq->nb);
1951 }
1952 EXPORT_SYMBOL(devfreq_unregister_opp_notifier);
1953
1954 static void devm_devfreq_opp_release(struct device *dev, void *res)
1955 {
1956         devfreq_unregister_opp_notifier(dev, *(struct devfreq **)res);
1957 }
1958
1959 /**
1960  * devm_devfreq_register_opp_notifier() - Resource-managed
1961  *                                        devfreq_register_opp_notifier()
1962  * @dev:        The devfreq user device. (parent of devfreq)
1963  * @devfreq:    The devfreq object.
1964  */
1965 int devm_devfreq_register_opp_notifier(struct device *dev,
1966                                        struct devfreq *devfreq)
1967 {
1968         struct devfreq **ptr;
1969         int ret;
1970
1971         ptr = devres_alloc(devm_devfreq_opp_release, sizeof(*ptr), GFP_KERNEL);
1972         if (!ptr)
1973                 return -ENOMEM;
1974
1975         ret = devfreq_register_opp_notifier(dev, devfreq);
1976         if (ret) {
1977                 devres_free(ptr);
1978                 return ret;
1979         }
1980
1981         *ptr = devfreq;
1982         devres_add(dev, ptr);
1983
1984         return 0;
1985 }
1986 EXPORT_SYMBOL(devm_devfreq_register_opp_notifier);
1987
1988 /**
1989  * devm_devfreq_unregister_opp_notifier() - Resource-managed
1990  *                                          devfreq_unregister_opp_notifier()
1991  * @dev:        The devfreq user device. (parent of devfreq)
1992  * @devfreq:    The devfreq object.
1993  */
1994 void devm_devfreq_unregister_opp_notifier(struct device *dev,
1995                                          struct devfreq *devfreq)
1996 {
1997         WARN_ON(devres_release(dev, devm_devfreq_opp_release,
1998                                devm_devfreq_dev_match, devfreq));
1999 }
2000 EXPORT_SYMBOL(devm_devfreq_unregister_opp_notifier);
2001
2002 /**
2003  * devfreq_register_notifier() - Register a driver with devfreq
2004  * @devfreq:    The devfreq object.
2005  * @nb:         The notifier block to register.
2006  * @list:       DEVFREQ_TRANSITION_NOTIFIER.
2007  */
2008 int devfreq_register_notifier(struct devfreq *devfreq,
2009                               struct notifier_block *nb,
2010                               unsigned int list)
2011 {
2012         int ret = 0;
2013
2014         if (!devfreq)
2015                 return -EINVAL;
2016
2017         switch (list) {
2018         case DEVFREQ_TRANSITION_NOTIFIER:
2019                 ret = srcu_notifier_chain_register(
2020                                 &devfreq->transition_notifier_list, nb);
2021                 break;
2022         default:
2023                 ret = -EINVAL;
2024         }
2025
2026         return ret;
2027 }
2028 EXPORT_SYMBOL(devfreq_register_notifier);
2029
2030 /*
2031  * devfreq_unregister_notifier() - Unregister a driver with devfreq
2032  * @devfreq:    The devfreq object.
2033  * @nb:         The notifier block to be unregistered.
2034  * @list:       DEVFREQ_TRANSITION_NOTIFIER.
2035  */
2036 int devfreq_unregister_notifier(struct devfreq *devfreq,
2037                                 struct notifier_block *nb,
2038                                 unsigned int list)
2039 {
2040         int ret = 0;
2041
2042         if (!devfreq)
2043                 return -EINVAL;
2044
2045         switch (list) {
2046         case DEVFREQ_TRANSITION_NOTIFIER:
2047                 ret = srcu_notifier_chain_unregister(
2048                                 &devfreq->transition_notifier_list, nb);
2049                 break;
2050         default:
2051                 ret = -EINVAL;
2052         }
2053
2054         return ret;
2055 }
2056 EXPORT_SYMBOL(devfreq_unregister_notifier);
2057
2058 struct devfreq_notifier_devres {
2059         struct devfreq *devfreq;
2060         struct notifier_block *nb;
2061         unsigned int list;
2062 };
2063
2064 static void devm_devfreq_notifier_release(struct device *dev, void *res)
2065 {
2066         struct devfreq_notifier_devres *this = res;
2067
2068         devfreq_unregister_notifier(this->devfreq, this->nb, this->list);
2069 }
2070
2071 /**
2072  * devm_devfreq_register_notifier()
2073  *      - Resource-managed devfreq_register_notifier()
2074  * @dev:        The devfreq user device. (parent of devfreq)
2075  * @devfreq:    The devfreq object.
2076  * @nb:         The notifier block to be unregistered.
2077  * @list:       DEVFREQ_TRANSITION_NOTIFIER.
2078  */
2079 int devm_devfreq_register_notifier(struct device *dev,
2080                                 struct devfreq *devfreq,
2081                                 struct notifier_block *nb,
2082                                 unsigned int list)
2083 {
2084         struct devfreq_notifier_devres *ptr;
2085         int ret;
2086
2087         ptr = devres_alloc(devm_devfreq_notifier_release, sizeof(*ptr),
2088                                 GFP_KERNEL);
2089         if (!ptr)
2090                 return -ENOMEM;
2091
2092         ret = devfreq_register_notifier(devfreq, nb, list);
2093         if (ret) {
2094                 devres_free(ptr);
2095                 return ret;
2096         }
2097
2098         ptr->devfreq = devfreq;
2099         ptr->nb = nb;
2100         ptr->list = list;
2101         devres_add(dev, ptr);
2102
2103         return 0;
2104 }
2105 EXPORT_SYMBOL(devm_devfreq_register_notifier);
2106
2107 /**
2108  * devm_devfreq_unregister_notifier()
2109  *      - Resource-managed devfreq_unregister_notifier()
2110  * @dev:        The devfreq user device. (parent of devfreq)
2111  * @devfreq:    The devfreq object.
2112  * @nb:         The notifier block to be unregistered.
2113  * @list:       DEVFREQ_TRANSITION_NOTIFIER.
2114  */
2115 void devm_devfreq_unregister_notifier(struct device *dev,
2116                                       struct devfreq *devfreq,
2117                                       struct notifier_block *nb,
2118                                       unsigned int list)
2119 {
2120         WARN_ON(devres_release(dev, devm_devfreq_notifier_release,
2121                                devm_devfreq_dev_match, devfreq));
2122 }
2123 EXPORT_SYMBOL(devm_devfreq_unregister_notifier);