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1/*
2 * devfreq: Generic Dynamic Voltage and Frequency Scaling (DVFS) Framework
3 * for Non-CPU Devices.
4 *
5 * Copyright (C) 2011 Samsung Electronics
6 * MyungJoo Ham <[email protected]>
7 *
8 * This program is free software; you can redistribute it and/or modify
9 * it under the terms of the GNU General Public License version 2 as
10 * published by the Free Software Foundation.
11 */
12
13#include <linux/kernel.h>
14#include <linux/sched.h>
15#include <linux/errno.h>
16#include <linux/err.h>
17#include <linux/init.h>
18#include <linux/module.h>
19#include <linux/slab.h>
20#include <linux/stat.h>
21#include <linux/pm_opp.h>
22#include <linux/devfreq.h>
23#include <linux/workqueue.h>
24#include <linux/platform_device.h>
25#include <linux/list.h>
26#include <linux/printk.h>
27#include <linux/hrtimer.h>
28#include <linux/of.h>
29#include "governor.h"
30
31static struct class *devfreq_class;
32
33/*
34 * devfreq core provides delayed work based load monitoring helper
35 * functions. Governors can use these or can implement their own
36 * monitoring mechanism.
37 */
38static struct workqueue_struct *devfreq_wq;
39
40/* The list of all device-devfreq governors */
41static LIST_HEAD(devfreq_governor_list);
42/* The list of all device-devfreq */
43static LIST_HEAD(devfreq_list);
44static DEFINE_MUTEX(devfreq_list_lock);
45
46/**
47 * find_device_devfreq() - find devfreq struct using device pointer
48 * @dev: device pointer used to lookup device devfreq.
49 *
50 * Search the list of device devfreqs and return the matched device's
51 * devfreq info. devfreq_list_lock should be held by the caller.
52 */
53static struct devfreq *find_device_devfreq(struct device *dev)
54{
55 struct devfreq *tmp_devfreq;
56
57 if (IS_ERR_OR_NULL(dev)) {
58 pr_err("DEVFREQ: %s: Invalid parameters\n", __func__);
59 return ERR_PTR(-EINVAL);
60 }
61 WARN(!mutex_is_locked(&devfreq_list_lock),
62 "devfreq_list_lock must be locked.");
63
64 list_for_each_entry(tmp_devfreq, &devfreq_list, node) {
65 if (tmp_devfreq->dev.parent == dev)
66 return tmp_devfreq;
67 }
68
69 return ERR_PTR(-ENODEV);
70}
71
72/**
73 * devfreq_get_freq_level() - Lookup freq_table for the frequency
74 * @devfreq: the devfreq instance
75 * @freq: the target frequency
76 */
77static int devfreq_get_freq_level(struct devfreq *devfreq, unsigned long freq)
78{
79 int lev;
80
81 for (lev = 0; lev < devfreq->profile->max_state; lev++)
82 if (freq == devfreq->profile->freq_table[lev])
83 return lev;
84
85 return -EINVAL;
86}
87
88/**
89 * devfreq_set_freq_table() - Initialize freq_table for the frequency
90 * @devfreq: the devfreq instance
91 */
92static void devfreq_set_freq_table(struct devfreq *devfreq)
93{
94 struct devfreq_dev_profile *profile = devfreq->profile;
95 struct dev_pm_opp *opp;
96 unsigned long freq;
97 int i, count;
98
99 /* Initialize the freq_table from OPP table */
100 count = dev_pm_opp_get_opp_count(devfreq->dev.parent);
101 if (count <= 0)
102 return;
103
104 profile->max_state = count;
105 profile->freq_table = devm_kcalloc(devfreq->dev.parent,
106 profile->max_state,
107 sizeof(*profile->freq_table),
108 GFP_KERNEL);
109 if (!profile->freq_table) {
110 profile->max_state = 0;
111 return;
112 }
113
114 rcu_read_lock();
115 for (i = 0, freq = 0; i < profile->max_state; i++, freq++) {
116 opp = dev_pm_opp_find_freq_ceil(devfreq->dev.parent, &freq);
117 if (IS_ERR(opp)) {
118 devm_kfree(devfreq->dev.parent, profile->freq_table);
119 profile->max_state = 0;
120 rcu_read_unlock();
121 return;
122 }
123 profile->freq_table[i] = freq;
124 }
125 rcu_read_unlock();
126}
127
128/**
129 * devfreq_update_status() - Update statistics of devfreq behavior
130 * @devfreq: the devfreq instance
131 * @freq: the update target frequency
132 */
133static int devfreq_update_status(struct devfreq *devfreq, unsigned long freq)
134{
135 int lev, prev_lev, ret = 0;
136 unsigned long cur_time;
137
138 cur_time = jiffies;
139
140 prev_lev = devfreq_get_freq_level(devfreq, devfreq->previous_freq);
141 if (prev_lev < 0) {
142 ret = prev_lev;
143 goto out;
144 }
145
146 devfreq->time_in_state[prev_lev] +=
147 cur_time - devfreq->last_stat_updated;
148
149 lev = devfreq_get_freq_level(devfreq, freq);
150 if (lev < 0) {
151 ret = lev;
152 goto out;
153 }
154
155 if (lev != prev_lev) {
156 devfreq->trans_table[(prev_lev *
157 devfreq->profile->max_state) + lev]++;
158 devfreq->total_trans++;
159 }
160
161out:
162 devfreq->last_stat_updated = cur_time;
163 return ret;
164}
165
166/**
167 * find_devfreq_governor() - find devfreq governor from name
168 * @name: name of the governor
169 *
170 * Search the list of devfreq governors and return the matched
171 * governor's pointer. devfreq_list_lock should be held by the caller.
172 */
173static struct devfreq_governor *find_devfreq_governor(const char *name)
174{
175 struct devfreq_governor *tmp_governor;
176
177 if (IS_ERR_OR_NULL(name)) {
178 pr_err("DEVFREQ: %s: Invalid parameters\n", __func__);
179 return ERR_PTR(-EINVAL);
180 }
181 WARN(!mutex_is_locked(&devfreq_list_lock),
182 "devfreq_list_lock must be locked.");
183
184 list_for_each_entry(tmp_governor, &devfreq_governor_list, node) {
185 if (!strncmp(tmp_governor->name, name, DEVFREQ_NAME_LEN))
186 return tmp_governor;
187 }
188
189 return ERR_PTR(-ENODEV);
190}
191
192static int devfreq_notify_transition(struct devfreq *devfreq,
193 struct devfreq_freqs *freqs, unsigned int state)
194{
195 if (!devfreq)
196 return -EINVAL;
197
198 switch (state) {
199 case DEVFREQ_PRECHANGE:
200 srcu_notifier_call_chain(&devfreq->transition_notifier_list,
201 DEVFREQ_PRECHANGE, freqs);
202 break;
203
204 case DEVFREQ_POSTCHANGE:
205 srcu_notifier_call_chain(&devfreq->transition_notifier_list,
206 DEVFREQ_POSTCHANGE, freqs);
207 break;
208 default:
209 return -EINVAL;
210 }
211
212 return 0;
213}
214
215/* Load monitoring helper functions for governors use */
216
217/**
218 * update_devfreq() - Reevaluate the device and configure frequency.
219 * @devfreq: the devfreq instance.
220 *
221 * Note: Lock devfreq->lock before calling update_devfreq
222 * This function is exported for governors.
223 */
224int update_devfreq(struct devfreq *devfreq)
225{
226 struct devfreq_freqs freqs;
227 unsigned long freq, cur_freq;
228 int err = 0;
229 u32 flags = 0;
230
231 if (!mutex_is_locked(&devfreq->lock)) {
232 WARN(true, "devfreq->lock must be locked by the caller.\n");
233 return -EINVAL;
234 }
235
236 if (!devfreq->governor)
237 return -EINVAL;
238
239 /* Reevaluate the proper frequency */
240 err = devfreq->governor->get_target_freq(devfreq, &freq);
241 if (err)
242 return err;
243
244 /*
245 * Adjust the frequency with user freq and QoS.
246 *
247 * List from the highest priority
248 * max_freq
249 * min_freq
250 */
251
252 if (devfreq->min_freq && freq < devfreq->min_freq) {
253 freq = devfreq->min_freq;
254 flags &= ~DEVFREQ_FLAG_LEAST_UPPER_BOUND; /* Use GLB */
255 }
256 if (devfreq->max_freq && freq > devfreq->max_freq) {
257 freq = devfreq->max_freq;
258 flags |= DEVFREQ_FLAG_LEAST_UPPER_BOUND; /* Use LUB */
259 }
260
261 if (devfreq->profile->get_cur_freq)
262 devfreq->profile->get_cur_freq(devfreq->dev.parent, &cur_freq);
263 else
264 cur_freq = devfreq->previous_freq;
265
266 freqs.old = cur_freq;
267 freqs.new = freq;
268 devfreq_notify_transition(devfreq, &freqs, DEVFREQ_PRECHANGE);
269
270 err = devfreq->profile->target(devfreq->dev.parent, &freq, flags);
271 if (err) {
272 freqs.new = cur_freq;
273 devfreq_notify_transition(devfreq, &freqs, DEVFREQ_POSTCHANGE);
274 return err;
275 }
276
277 freqs.new = freq;
278 devfreq_notify_transition(devfreq, &freqs, DEVFREQ_POSTCHANGE);
279
280 if (devfreq->profile->freq_table)
281 if (devfreq_update_status(devfreq, freq))
282 dev_err(&devfreq->dev,
283 "Couldn't update frequency transition information.\n");
284
285 devfreq->previous_freq = freq;
286 return err;
287}
288EXPORT_SYMBOL(update_devfreq);
289
290/**
291 * devfreq_monitor() - Periodically poll devfreq objects.
292 * @work: the work struct used to run devfreq_monitor periodically.
293 *
294 */
295static void devfreq_monitor(struct work_struct *work)
296{
297 int err;
298 struct devfreq *devfreq = container_of(work,
299 struct devfreq, work.work);
300
301 mutex_lock(&devfreq->lock);
302 err = update_devfreq(devfreq);
303 if (err)
304 dev_err(&devfreq->dev, "dvfs failed with (%d) error\n", err);
305
306 queue_delayed_work(devfreq_wq, &devfreq->work,
307 msecs_to_jiffies(devfreq->profile->polling_ms));
308 mutex_unlock(&devfreq->lock);
309}
310
311/**
312 * devfreq_monitor_start() - Start load monitoring of devfreq instance
313 * @devfreq: the devfreq instance.
314 *
315 * Helper function for starting devfreq device load monitoing. By
316 * default delayed work based monitoring is supported. Function
317 * to be called from governor in response to DEVFREQ_GOV_START
318 * event when device is added to devfreq framework.
319 */
320void devfreq_monitor_start(struct devfreq *devfreq)
321{
322 INIT_DEFERRABLE_WORK(&devfreq->work, devfreq_monitor);
323 if (devfreq->profile->polling_ms)
324 queue_delayed_work(devfreq_wq, &devfreq->work,
325 msecs_to_jiffies(devfreq->profile->polling_ms));
326}
327EXPORT_SYMBOL(devfreq_monitor_start);
328
329/**
330 * devfreq_monitor_stop() - Stop load monitoring of a devfreq instance
331 * @devfreq: the devfreq instance.
332 *
333 * Helper function to stop devfreq device load monitoing. Function
334 * to be called from governor in response to DEVFREQ_GOV_STOP
335 * event when device is removed from devfreq framework.
336 */
337void devfreq_monitor_stop(struct devfreq *devfreq)
338{
339 cancel_delayed_work_sync(&devfreq->work);
340}
341EXPORT_SYMBOL(devfreq_monitor_stop);
342
343/**
344 * devfreq_monitor_suspend() - Suspend load monitoring of a devfreq instance
345 * @devfreq: the devfreq instance.
346 *
347 * Helper function to suspend devfreq device load monitoing. Function
348 * to be called from governor in response to DEVFREQ_GOV_SUSPEND
349 * event or when polling interval is set to zero.
350 *
351 * Note: Though this function is same as devfreq_monitor_stop(),
352 * intentionally kept separate to provide hooks for collecting
353 * transition statistics.
354 */
355void devfreq_monitor_suspend(struct devfreq *devfreq)
356{
357 mutex_lock(&devfreq->lock);
358 if (devfreq->stop_polling) {
359 mutex_unlock(&devfreq->lock);
360 return;
361 }
362
363 devfreq_update_status(devfreq, devfreq->previous_freq);
364 devfreq->stop_polling = true;
365 mutex_unlock(&devfreq->lock);
366 cancel_delayed_work_sync(&devfreq->work);
367}
368EXPORT_SYMBOL(devfreq_monitor_suspend);
369
370/**
371 * devfreq_monitor_resume() - Resume load monitoring of a devfreq instance
372 * @devfreq: the devfreq instance.
373 *
374 * Helper function to resume devfreq device load monitoing. Function
375 * to be called from governor in response to DEVFREQ_GOV_RESUME
376 * event or when polling interval is set to non-zero.
377 */
378void devfreq_monitor_resume(struct devfreq *devfreq)
379{
380 unsigned long freq;
381
382 mutex_lock(&devfreq->lock);
383 if (!devfreq->stop_polling)
384 goto out;
385
386 if (!delayed_work_pending(&devfreq->work) &&
387 devfreq->profile->polling_ms)
388 queue_delayed_work(devfreq_wq, &devfreq->work,
389 msecs_to_jiffies(devfreq->profile->polling_ms));
390
391 devfreq->last_stat_updated = jiffies;
392 devfreq->stop_polling = false;
393
394 if (devfreq->profile->get_cur_freq &&
395 !devfreq->profile->get_cur_freq(devfreq->dev.parent, &freq))
396 devfreq->previous_freq = freq;
397
398out:
399 mutex_unlock(&devfreq->lock);
400}
401EXPORT_SYMBOL(devfreq_monitor_resume);
402
403/**
404 * devfreq_interval_update() - Update device devfreq monitoring interval
405 * @devfreq: the devfreq instance.
406 * @delay: new polling interval to be set.
407 *
408 * Helper function to set new load monitoring polling interval. Function
409 * to be called from governor in response to DEVFREQ_GOV_INTERVAL event.
410 */
411void devfreq_interval_update(struct devfreq *devfreq, unsigned int *delay)
412{
413 unsigned int cur_delay = devfreq->profile->polling_ms;
414 unsigned int new_delay = *delay;
415
416 mutex_lock(&devfreq->lock);
417 devfreq->profile->polling_ms = new_delay;
418
419 if (devfreq->stop_polling)
420 goto out;
421
422 /* if new delay is zero, stop polling */
423 if (!new_delay) {
424 mutex_unlock(&devfreq->lock);
425 cancel_delayed_work_sync(&devfreq->work);
426 return;
427 }
428
429 /* if current delay is zero, start polling with new delay */
430 if (!cur_delay) {
431 queue_delayed_work(devfreq_wq, &devfreq->work,
432 msecs_to_jiffies(devfreq->profile->polling_ms));
433 goto out;
434 }
435
436 /* if current delay is greater than new delay, restart polling */
437 if (cur_delay > new_delay) {
438 mutex_unlock(&devfreq->lock);
439 cancel_delayed_work_sync(&devfreq->work);
440 mutex_lock(&devfreq->lock);
441 if (!devfreq->stop_polling)
442 queue_delayed_work(devfreq_wq, &devfreq->work,
443 msecs_to_jiffies(devfreq->profile->polling_ms));
444 }
445out:
446 mutex_unlock(&devfreq->lock);
447}
448EXPORT_SYMBOL(devfreq_interval_update);
449
450/**
451 * devfreq_notifier_call() - Notify that the device frequency requirements
452 * has been changed out of devfreq framework.
453 * @nb: the notifier_block (supposed to be devfreq->nb)
454 * @type: not used
455 * @devp: not used
456 *
457 * Called by a notifier that uses devfreq->nb.
458 */
459static int devfreq_notifier_call(struct notifier_block *nb, unsigned long type,
460 void *devp)
461{
462 struct devfreq *devfreq = container_of(nb, struct devfreq, nb);
463 int ret;
464
465 mutex_lock(&devfreq->lock);
466 ret = update_devfreq(devfreq);
467 mutex_unlock(&devfreq->lock);
468
469 return ret;
470}
471
472/**
473 * _remove_devfreq() - Remove devfreq from the list and release its resources.
474 * @devfreq: the devfreq struct
475 */
476static void _remove_devfreq(struct devfreq *devfreq)
477{
478 mutex_lock(&devfreq_list_lock);
479 if (IS_ERR(find_device_devfreq(devfreq->dev.parent))) {
480 mutex_unlock(&devfreq_list_lock);
481 dev_warn(&devfreq->dev, "releasing devfreq which doesn't exist\n");
482 return;
483 }
484 list_del(&devfreq->node);
485 mutex_unlock(&devfreq_list_lock);
486
487 if (devfreq->governor)
488 devfreq->governor->event_handler(devfreq,
489 DEVFREQ_GOV_STOP, NULL);
490
491 if (devfreq->profile->exit)
492 devfreq->profile->exit(devfreq->dev.parent);
493
494 mutex_destroy(&devfreq->lock);
495 kfree(devfreq);
496}
497
498/**
499 * devfreq_dev_release() - Callback for struct device to release the device.
500 * @dev: the devfreq device
501 *
502 * This calls _remove_devfreq() if _remove_devfreq() is not called.
503 */
504static void devfreq_dev_release(struct device *dev)
505{
506 struct devfreq *devfreq = to_devfreq(dev);
507
508 _remove_devfreq(devfreq);
509}
510
511/**
512 * devfreq_add_device() - Add devfreq feature to the device
513 * @dev: the device to add devfreq feature.
514 * @profile: device-specific profile to run devfreq.
515 * @governor_name: name of the policy to choose frequency.
516 * @data: private data for the governor. The devfreq framework does not
517 * touch this value.
518 */
519struct devfreq *devfreq_add_device(struct device *dev,
520 struct devfreq_dev_profile *profile,
521 const char *governor_name,
522 void *data)
523{
524 struct devfreq *devfreq;
525 struct devfreq_governor *governor;
526 int err = 0;
527
528 if (!dev || !profile || !governor_name) {
529 dev_err(dev, "%s: Invalid parameters.\n", __func__);
530 return ERR_PTR(-EINVAL);
531 }
532
533 mutex_lock(&devfreq_list_lock);
534 devfreq = find_device_devfreq(dev);
535 mutex_unlock(&devfreq_list_lock);
536 if (!IS_ERR(devfreq)) {
537 dev_err(dev, "%s: Unable to create devfreq for the device. It already has one.\n", __func__);
538 err = -EINVAL;
539 goto err_out;
540 }
541
542 devfreq = kzalloc(sizeof(struct devfreq), GFP_KERNEL);
543 if (!devfreq) {
544 dev_err(dev, "%s: Unable to create devfreq for the device\n",
545 __func__);
546 err = -ENOMEM;
547 goto err_out;
548 }
549
550 mutex_init(&devfreq->lock);
551 mutex_lock(&devfreq->lock);
552 devfreq->dev.parent = dev;
553 devfreq->dev.class = devfreq_class;
554 devfreq->dev.release = devfreq_dev_release;
555 devfreq->profile = profile;
556 strncpy(devfreq->governor_name, governor_name, DEVFREQ_NAME_LEN);
557 devfreq->previous_freq = profile->initial_freq;
558 devfreq->last_status.current_frequency = profile->initial_freq;
559 devfreq->data = data;
560 devfreq->nb.notifier_call = devfreq_notifier_call;
561
562 if (!devfreq->profile->max_state && !devfreq->profile->freq_table) {
563 mutex_unlock(&devfreq->lock);
564 devfreq_set_freq_table(devfreq);
565 mutex_lock(&devfreq->lock);
566 }
567
568 dev_set_name(&devfreq->dev, "%s", dev_name(dev));
569 err = device_register(&devfreq->dev);
570 if (err) {
571 mutex_unlock(&devfreq->lock);
572 goto err_out;
573 }
574
575 devfreq->trans_table = devm_kzalloc(&devfreq->dev, sizeof(unsigned int) *
576 devfreq->profile->max_state *
577 devfreq->profile->max_state,
578 GFP_KERNEL);
579 devfreq->time_in_state = devm_kzalloc(&devfreq->dev, sizeof(unsigned long) *
580 devfreq->profile->max_state,
581 GFP_KERNEL);
582 devfreq->last_stat_updated = jiffies;
583
584 srcu_init_notifier_head(&devfreq->transition_notifier_list);
585
586 mutex_unlock(&devfreq->lock);
587
588 mutex_lock(&devfreq_list_lock);
589 list_add(&devfreq->node, &devfreq_list);
590
591 governor = find_devfreq_governor(devfreq->governor_name);
592 if (!IS_ERR(governor))
593 devfreq->governor = governor;
594 if (devfreq->governor)
595 err = devfreq->governor->event_handler(devfreq,
596 DEVFREQ_GOV_START, NULL);
597 mutex_unlock(&devfreq_list_lock);
598 if (err) {
599 dev_err(dev, "%s: Unable to start governor for the device\n",
600 __func__);
601 goto err_init;
602 }
603
604 return devfreq;
605
606err_init:
607 list_del(&devfreq->node);
608 device_unregister(&devfreq->dev);
609err_out:
610 return ERR_PTR(err);
611}
612EXPORT_SYMBOL(devfreq_add_device);
613
614/**
615 * devfreq_remove_device() - Remove devfreq feature from a device.
616 * @devfreq: the devfreq instance to be removed
617 *
618 * The opposite of devfreq_add_device().
619 */
620int devfreq_remove_device(struct devfreq *devfreq)
621{
622 if (!devfreq)
623 return -EINVAL;
624
625 device_unregister(&devfreq->dev);
626
627 return 0;
628}
629EXPORT_SYMBOL(devfreq_remove_device);
630
631static int devm_devfreq_dev_match(struct device *dev, void *res, void *data)
632{
633 struct devfreq **r = res;
634
635 if (WARN_ON(!r || !*r))
636 return 0;
637
638 return *r == data;
639}
640
641static void devm_devfreq_dev_release(struct device *dev, void *res)
642{
643 devfreq_remove_device(*(struct devfreq **)res);
644}
645
646/**
647 * devm_devfreq_add_device() - Resource-managed devfreq_add_device()
648 * @dev: the device to add devfreq feature.
649 * @profile: device-specific profile to run devfreq.
650 * @governor_name: name of the policy to choose frequency.
651 * @data: private data for the governor. The devfreq framework does not
652 * touch this value.
653 *
654 * This function manages automatically the memory of devfreq device using device
655 * resource management and simplify the free operation for memory of devfreq
656 * device.
657 */
658struct devfreq *devm_devfreq_add_device(struct device *dev,
659 struct devfreq_dev_profile *profile,
660 const char *governor_name,
661 void *data)
662{
663 struct devfreq **ptr, *devfreq;
664
665 ptr = devres_alloc(devm_devfreq_dev_release, sizeof(*ptr), GFP_KERNEL);
666 if (!ptr)
667 return ERR_PTR(-ENOMEM);
668
669 devfreq = devfreq_add_device(dev, profile, governor_name, data);
670 if (IS_ERR(devfreq)) {
671 devres_free(ptr);
672 return ERR_PTR(-ENOMEM);
673 }
674
675 *ptr = devfreq;
676 devres_add(dev, ptr);
677
678 return devfreq;
679}
680EXPORT_SYMBOL(devm_devfreq_add_device);
681
682#ifdef CONFIG_OF
683/*
684 * devfreq_get_devfreq_by_phandle - Get the devfreq device from devicetree
685 * @dev - instance to the given device
686 * @index - index into list of devfreq
687 *
688 * return the instance of devfreq device
689 */
690struct devfreq *devfreq_get_devfreq_by_phandle(struct device *dev, int index)
691{
692 struct device_node *node;
693 struct devfreq *devfreq;
694
695 if (!dev)
696 return ERR_PTR(-EINVAL);
697
698 if (!dev->of_node)
699 return ERR_PTR(-EINVAL);
700
701 node = of_parse_phandle(dev->of_node, "devfreq", index);
702 if (!node)
703 return ERR_PTR(-ENODEV);
704
705 mutex_lock(&devfreq_list_lock);
706 list_for_each_entry(devfreq, &devfreq_list, node) {
707 if (devfreq->dev.parent
708 && devfreq->dev.parent->of_node == node) {
709 mutex_unlock(&devfreq_list_lock);
710 return devfreq;
711 }
712 }
713 mutex_unlock(&devfreq_list_lock);
714
715 return ERR_PTR(-EPROBE_DEFER);
716}
717#else
718struct devfreq *devfreq_get_devfreq_by_phandle(struct device *dev, int index)
719{
720 return ERR_PTR(-ENODEV);
721}
722#endif /* CONFIG_OF */
723EXPORT_SYMBOL_GPL(devfreq_get_devfreq_by_phandle);
724
725/**
726 * devm_devfreq_remove_device() - Resource-managed devfreq_remove_device()
727 * @dev: the device to add devfreq feature.
728 * @devfreq: the devfreq instance to be removed
729 */
730void devm_devfreq_remove_device(struct device *dev, struct devfreq *devfreq)
731{
732 WARN_ON(devres_release(dev, devm_devfreq_dev_release,
733 devm_devfreq_dev_match, devfreq));
734}
735EXPORT_SYMBOL(devm_devfreq_remove_device);
736
737/**
738 * devfreq_suspend_device() - Suspend devfreq of a device.
739 * @devfreq: the devfreq instance to be suspended
740 *
741 * This function is intended to be called by the pm callbacks
742 * (e.g., runtime_suspend, suspend) of the device driver that
743 * holds the devfreq.
744 */
745int devfreq_suspend_device(struct devfreq *devfreq)
746{
747 if (!devfreq)
748 return -EINVAL;
749
750 if (!devfreq->governor)
751 return 0;
752
753 return devfreq->governor->event_handler(devfreq,
754 DEVFREQ_GOV_SUSPEND, NULL);
755}
756EXPORT_SYMBOL(devfreq_suspend_device);
757
758/**
759 * devfreq_resume_device() - Resume devfreq of a device.
760 * @devfreq: the devfreq instance to be resumed
761 *
762 * This function is intended to be called by the pm callbacks
763 * (e.g., runtime_resume, resume) of the device driver that
764 * holds the devfreq.
765 */
766int devfreq_resume_device(struct devfreq *devfreq)
767{
768 if (!devfreq)
769 return -EINVAL;
770
771 if (!devfreq->governor)
772 return 0;
773
774 return devfreq->governor->event_handler(devfreq,
775 DEVFREQ_GOV_RESUME, NULL);
776}
777EXPORT_SYMBOL(devfreq_resume_device);
778
779/**
780 * devfreq_add_governor() - Add devfreq governor
781 * @governor: the devfreq governor to be added
782 */
783int devfreq_add_governor(struct devfreq_governor *governor)
784{
785 struct devfreq_governor *g;
786 struct devfreq *devfreq;
787 int err = 0;
788
789 if (!governor) {
790 pr_err("%s: Invalid parameters.\n", __func__);
791 return -EINVAL;
792 }
793
794 mutex_lock(&devfreq_list_lock);
795 g = find_devfreq_governor(governor->name);
796 if (!IS_ERR(g)) {
797 pr_err("%s: governor %s already registered\n", __func__,
798 g->name);
799 err = -EINVAL;
800 goto err_out;
801 }
802
803 list_add(&governor->node, &devfreq_governor_list);
804
805 list_for_each_entry(devfreq, &devfreq_list, node) {
806 int ret = 0;
807 struct device *dev = devfreq->dev.parent;
808
809 if (!strncmp(devfreq->governor_name, governor->name,
810 DEVFREQ_NAME_LEN)) {
811 /* The following should never occur */
812 if (devfreq->governor) {
813 dev_warn(dev,
814 "%s: Governor %s already present\n",
815 __func__, devfreq->governor->name);
816 ret = devfreq->governor->event_handler(devfreq,
817 DEVFREQ_GOV_STOP, NULL);
818 if (ret) {
819 dev_warn(dev,
820 "%s: Governor %s stop = %d\n",
821 __func__,
822 devfreq->governor->name, ret);
823 }
824 /* Fall through */
825 }
826 devfreq->governor = governor;
827 ret = devfreq->governor->event_handler(devfreq,
828 DEVFREQ_GOV_START, NULL);
829 if (ret) {
830 dev_warn(dev, "%s: Governor %s start=%d\n",
831 __func__, devfreq->governor->name,
832 ret);
833 }
834 }
835 }
836
837err_out:
838 mutex_unlock(&devfreq_list_lock);
839
840 return err;
841}
842EXPORT_SYMBOL(devfreq_add_governor);
843
844/**
845 * devfreq_remove_device() - Remove devfreq feature from a device.
846 * @governor: the devfreq governor to be removed
847 */
848int devfreq_remove_governor(struct devfreq_governor *governor)
849{
850 struct devfreq_governor *g;
851 struct devfreq *devfreq;
852 int err = 0;
853
854 if (!governor) {
855 pr_err("%s: Invalid parameters.\n", __func__);
856 return -EINVAL;
857 }
858
859 mutex_lock(&devfreq_list_lock);
860 g = find_devfreq_governor(governor->name);
861 if (IS_ERR(g)) {
862 pr_err("%s: governor %s not registered\n", __func__,
863 governor->name);
864 err = PTR_ERR(g);
865 goto err_out;
866 }
867 list_for_each_entry(devfreq, &devfreq_list, node) {
868 int ret;
869 struct device *dev = devfreq->dev.parent;
870
871 if (!strncmp(devfreq->governor_name, governor->name,
872 DEVFREQ_NAME_LEN)) {
873 /* we should have a devfreq governor! */
874 if (!devfreq->governor) {
875 dev_warn(dev, "%s: Governor %s NOT present\n",
876 __func__, governor->name);
877 continue;
878 /* Fall through */
879 }
880 ret = devfreq->governor->event_handler(devfreq,
881 DEVFREQ_GOV_STOP, NULL);
882 if (ret) {
883 dev_warn(dev, "%s: Governor %s stop=%d\n",
884 __func__, devfreq->governor->name,
885 ret);
886 }
887 devfreq->governor = NULL;
888 }
889 }
890
891 list_del(&governor->node);
892err_out:
893 mutex_unlock(&devfreq_list_lock);
894
895 return err;
896}
897EXPORT_SYMBOL(devfreq_remove_governor);
898
899static ssize_t governor_show(struct device *dev,
900 struct device_attribute *attr, char *buf)
901{
902 if (!to_devfreq(dev)->governor)
903 return -EINVAL;
904
905 return sprintf(buf, "%s\n", to_devfreq(dev)->governor->name);
906}
907
908static ssize_t governor_store(struct device *dev, struct device_attribute *attr,
909 const char *buf, size_t count)
910{
911 struct devfreq *df = to_devfreq(dev);
912 int ret;
913 char str_governor[DEVFREQ_NAME_LEN + 1];
914 struct devfreq_governor *governor;
915
916 ret = sscanf(buf, "%" __stringify(DEVFREQ_NAME_LEN) "s", str_governor);
917 if (ret != 1)
918 return -EINVAL;
919
920 mutex_lock(&devfreq_list_lock);
921 governor = find_devfreq_governor(str_governor);
922 if (IS_ERR(governor)) {
923 ret = PTR_ERR(governor);
924 goto out;
925 }
926 if (df->governor == governor) {
927 ret = 0;
928 goto out;
929 }
930
931 if (df->governor) {
932 ret = df->governor->event_handler(df, DEVFREQ_GOV_STOP, NULL);
933 if (ret) {
934 dev_warn(dev, "%s: Governor %s not stopped(%d)\n",
935 __func__, df->governor->name, ret);
936 goto out;
937 }
938 }
939 df->governor = governor;
940 strncpy(df->governor_name, governor->name, DEVFREQ_NAME_LEN);
941 ret = df->governor->event_handler(df, DEVFREQ_GOV_START, NULL);
942 if (ret)
943 dev_warn(dev, "%s: Governor %s not started(%d)\n",
944 __func__, df->governor->name, ret);
945out:
946 mutex_unlock(&devfreq_list_lock);
947
948 if (!ret)
949 ret = count;
950 return ret;
951}
952static DEVICE_ATTR_RW(governor);
953
954static ssize_t available_governors_show(struct device *d,
955 struct device_attribute *attr,
956 char *buf)
957{
958 struct devfreq_governor *tmp_governor;
959 ssize_t count = 0;
960
961 mutex_lock(&devfreq_list_lock);
962 list_for_each_entry(tmp_governor, &devfreq_governor_list, node)
963 count += scnprintf(&buf[count], (PAGE_SIZE - count - 2),
964 "%s ", tmp_governor->name);
965 mutex_unlock(&devfreq_list_lock);
966
967 /* Truncate the trailing space */
968 if (count)
969 count--;
970
971 count += sprintf(&buf[count], "\n");
972
973 return count;
974}
975static DEVICE_ATTR_RO(available_governors);
976
977static ssize_t cur_freq_show(struct device *dev, struct device_attribute *attr,
978 char *buf)
979{
980 unsigned long freq;
981 struct devfreq *devfreq = to_devfreq(dev);
982
983 if (devfreq->profile->get_cur_freq &&
984 !devfreq->profile->get_cur_freq(devfreq->dev.parent, &freq))
985 return sprintf(buf, "%lu\n", freq);
986
987 return sprintf(buf, "%lu\n", devfreq->previous_freq);
988}
989static DEVICE_ATTR_RO(cur_freq);
990
991static ssize_t target_freq_show(struct device *dev,
992 struct device_attribute *attr, char *buf)
993{
994 return sprintf(buf, "%lu\n", to_devfreq(dev)->previous_freq);
995}
996static DEVICE_ATTR_RO(target_freq);
997
998static ssize_t polling_interval_show(struct device *dev,
999 struct device_attribute *attr, char *buf)
1000{
1001 return sprintf(buf, "%d\n", to_devfreq(dev)->profile->polling_ms);
1002}
1003
1004static ssize_t polling_interval_store(struct device *dev,
1005 struct device_attribute *attr,
1006 const char *buf, size_t count)
1007{
1008 struct devfreq *df = to_devfreq(dev);
1009 unsigned int value;
1010 int ret;
1011
1012 if (!df->governor)
1013 return -EINVAL;
1014
1015 ret = sscanf(buf, "%u", &value);
1016 if (ret != 1)
1017 return -EINVAL;
1018
1019 df->governor->event_handler(df, DEVFREQ_GOV_INTERVAL, &value);
1020 ret = count;
1021
1022 return ret;
1023}
1024static DEVICE_ATTR_RW(polling_interval);
1025
1026static ssize_t min_freq_store(struct device *dev, struct device_attribute *attr,
1027 const char *buf, size_t count)
1028{
1029 struct devfreq *df = to_devfreq(dev);
1030 unsigned long value;
1031 int ret;
1032 unsigned long max;
1033
1034 ret = sscanf(buf, "%lu", &value);
1035 if (ret != 1)
1036 return -EINVAL;
1037
1038 mutex_lock(&df->lock);
1039 max = df->max_freq;
1040 if (value && max && value > max) {
1041 ret = -EINVAL;
1042 goto unlock;
1043 }
1044
1045 df->min_freq = value;
1046 update_devfreq(df);
1047 ret = count;
1048unlock:
1049 mutex_unlock(&df->lock);
1050 return ret;
1051}
1052
1053static ssize_t max_freq_store(struct device *dev, struct device_attribute *attr,
1054 const char *buf, size_t count)
1055{
1056 struct devfreq *df = to_devfreq(dev);
1057 unsigned long value;
1058 int ret;
1059 unsigned long min;
1060
1061 ret = sscanf(buf, "%lu", &value);
1062 if (ret != 1)
1063 return -EINVAL;
1064
1065 mutex_lock(&df->lock);
1066 min = df->min_freq;
1067 if (value && min && value < min) {
1068 ret = -EINVAL;
1069 goto unlock;
1070 }
1071
1072 df->max_freq = value;
1073 update_devfreq(df);
1074 ret = count;
1075unlock:
1076 mutex_unlock(&df->lock);
1077 return ret;
1078}
1079
1080#define show_one(name) \
1081static ssize_t name##_show \
1082(struct device *dev, struct device_attribute *attr, char *buf) \
1083{ \
1084 return sprintf(buf, "%lu\n", to_devfreq(dev)->name); \
1085}
1086show_one(min_freq);
1087show_one(max_freq);
1088
1089static DEVICE_ATTR_RW(min_freq);
1090static DEVICE_ATTR_RW(max_freq);
1091
1092static ssize_t available_frequencies_show(struct device *d,
1093 struct device_attribute *attr,
1094 char *buf)
1095{
1096 struct devfreq *df = to_devfreq(d);
1097 struct device *dev = df->dev.parent;
1098 struct dev_pm_opp *opp;
1099 ssize_t count = 0;
1100 unsigned long freq = 0;
1101
1102 rcu_read_lock();
1103 do {
1104 opp = dev_pm_opp_find_freq_ceil(dev, &freq);
1105 if (IS_ERR(opp))
1106 break;
1107
1108 count += scnprintf(&buf[count], (PAGE_SIZE - count - 2),
1109 "%lu ", freq);
1110 freq++;
1111 } while (1);
1112 rcu_read_unlock();
1113
1114 /* Truncate the trailing space */
1115 if (count)
1116 count--;
1117
1118 count += sprintf(&buf[count], "\n");
1119
1120 return count;
1121}
1122static DEVICE_ATTR_RO(available_frequencies);
1123
1124static ssize_t trans_stat_show(struct device *dev,
1125 struct device_attribute *attr, char *buf)
1126{
1127 struct devfreq *devfreq = to_devfreq(dev);
1128 ssize_t len;
1129 int i, j;
1130 unsigned int max_state = devfreq->profile->max_state;
1131
1132 if (!devfreq->stop_polling &&
1133 devfreq_update_status(devfreq, devfreq->previous_freq))
1134 return 0;
1135 if (max_state == 0)
1136 return sprintf(buf, "Not Supported.\n");
1137
1138 len = sprintf(buf, " From : To\n");
1139 len += sprintf(buf + len, " :");
1140 for (i = 0; i < max_state; i++)
1141 len += sprintf(buf + len, "%10lu",
1142 devfreq->profile->freq_table[i]);
1143
1144 len += sprintf(buf + len, " time(ms)\n");
1145
1146 for (i = 0; i < max_state; i++) {
1147 if (devfreq->profile->freq_table[i]
1148 == devfreq->previous_freq) {
1149 len += sprintf(buf + len, "*");
1150 } else {
1151 len += sprintf(buf + len, " ");
1152 }
1153 len += sprintf(buf + len, "%10lu:",
1154 devfreq->profile->freq_table[i]);
1155 for (j = 0; j < max_state; j++)
1156 len += sprintf(buf + len, "%10u",
1157 devfreq->trans_table[(i * max_state) + j]);
1158 len += sprintf(buf + len, "%10u\n",
1159 jiffies_to_msecs(devfreq->time_in_state[i]));
1160 }
1161
1162 len += sprintf(buf + len, "Total transition : %u\n",
1163 devfreq->total_trans);
1164 return len;
1165}
1166static DEVICE_ATTR_RO(trans_stat);
1167
1168static struct attribute *devfreq_attrs[] = {
1169 &dev_attr_governor.attr,
1170 &dev_attr_available_governors.attr,
1171 &dev_attr_cur_freq.attr,
1172 &dev_attr_available_frequencies.attr,
1173 &dev_attr_target_freq.attr,
1174 &dev_attr_polling_interval.attr,
1175 &dev_attr_min_freq.attr,
1176 &dev_attr_max_freq.attr,
1177 &dev_attr_trans_stat.attr,
1178 NULL,
1179};
1180ATTRIBUTE_GROUPS(devfreq);
1181
1182static int __init devfreq_init(void)
1183{
1184 devfreq_class = class_create(THIS_MODULE, "devfreq");
1185 if (IS_ERR(devfreq_class)) {
1186 pr_err("%s: couldn't create class\n", __FILE__);
1187 return PTR_ERR(devfreq_class);
1188 }
1189
1190 devfreq_wq = create_freezable_workqueue("devfreq_wq");
1191 if (!devfreq_wq) {
1192 class_destroy(devfreq_class);
1193 pr_err("%s: couldn't create workqueue\n", __FILE__);
1194 return -ENOMEM;
1195 }
1196 devfreq_class->dev_groups = devfreq_groups;
1197
1198 return 0;
1199}
1200subsys_initcall(devfreq_init);
1201
1202static void __exit devfreq_exit(void)
1203{
1204 class_destroy(devfreq_class);
1205 destroy_workqueue(devfreq_wq);
1206}
1207module_exit(devfreq_exit);
1208
1209/*
1210 * The followings are helper functions for devfreq user device drivers with
1211 * OPP framework.
1212 */
1213
1214/**
1215 * devfreq_recommended_opp() - Helper function to get proper OPP for the
1216 * freq value given to target callback.
1217 * @dev: The devfreq user device. (parent of devfreq)
1218 * @freq: The frequency given to target function
1219 * @flags: Flags handed from devfreq framework.
1220 *
1221 * Locking: This function must be called under rcu_read_lock(). opp is a rcu
1222 * protected pointer. The reason for the same is that the opp pointer which is
1223 * returned will remain valid for use with opp_get_{voltage, freq} only while
1224 * under the locked area. The pointer returned must be used prior to unlocking
1225 * with rcu_read_unlock() to maintain the integrity of the pointer.
1226 */
1227struct dev_pm_opp *devfreq_recommended_opp(struct device *dev,
1228 unsigned long *freq,
1229 u32 flags)
1230{
1231 struct dev_pm_opp *opp;
1232
1233 if (flags & DEVFREQ_FLAG_LEAST_UPPER_BOUND) {
1234 /* The freq is an upper bound. opp should be lower */
1235 opp = dev_pm_opp_find_freq_floor(dev, freq);
1236
1237 /* If not available, use the closest opp */
1238 if (opp == ERR_PTR(-ERANGE))
1239 opp = dev_pm_opp_find_freq_ceil(dev, freq);
1240 } else {
1241 /* The freq is an lower bound. opp should be higher */
1242 opp = dev_pm_opp_find_freq_ceil(dev, freq);
1243
1244 /* If not available, use the closest opp */
1245 if (opp == ERR_PTR(-ERANGE))
1246 opp = dev_pm_opp_find_freq_floor(dev, freq);
1247 }
1248
1249 return opp;
1250}
1251EXPORT_SYMBOL(devfreq_recommended_opp);
1252
1253/**
1254 * devfreq_register_opp_notifier() - Helper function to get devfreq notified
1255 * for any changes in the OPP availability
1256 * changes
1257 * @dev: The devfreq user device. (parent of devfreq)
1258 * @devfreq: The devfreq object.
1259 */
1260int devfreq_register_opp_notifier(struct device *dev, struct devfreq *devfreq)
1261{
1262 struct srcu_notifier_head *nh;
1263 int ret = 0;
1264
1265 rcu_read_lock();
1266 nh = dev_pm_opp_get_notifier(dev);
1267 if (IS_ERR(nh))
1268 ret = PTR_ERR(nh);
1269 rcu_read_unlock();
1270 if (!ret)
1271 ret = srcu_notifier_chain_register(nh, &devfreq->nb);
1272
1273 return ret;
1274}
1275EXPORT_SYMBOL(devfreq_register_opp_notifier);
1276
1277/**
1278 * devfreq_unregister_opp_notifier() - Helper function to stop getting devfreq
1279 * notified for any changes in the OPP
1280 * availability changes anymore.
1281 * @dev: The devfreq user device. (parent of devfreq)
1282 * @devfreq: The devfreq object.
1283 *
1284 * At exit() callback of devfreq_dev_profile, this must be included if
1285 * devfreq_recommended_opp is used.
1286 */
1287int devfreq_unregister_opp_notifier(struct device *dev, struct devfreq *devfreq)
1288{
1289 struct srcu_notifier_head *nh;
1290 int ret = 0;
1291
1292 rcu_read_lock();
1293 nh = dev_pm_opp_get_notifier(dev);
1294 if (IS_ERR(nh))
1295 ret = PTR_ERR(nh);
1296 rcu_read_unlock();
1297 if (!ret)
1298 ret = srcu_notifier_chain_unregister(nh, &devfreq->nb);
1299
1300 return ret;
1301}
1302EXPORT_SYMBOL(devfreq_unregister_opp_notifier);
1303
1304static void devm_devfreq_opp_release(struct device *dev, void *res)
1305{
1306 devfreq_unregister_opp_notifier(dev, *(struct devfreq **)res);
1307}
1308
1309/**
1310 * devm_ devfreq_register_opp_notifier()
1311 * - Resource-managed devfreq_register_opp_notifier()
1312 * @dev: The devfreq user device. (parent of devfreq)
1313 * @devfreq: The devfreq object.
1314 */
1315int devm_devfreq_register_opp_notifier(struct device *dev,
1316 struct devfreq *devfreq)
1317{
1318 struct devfreq **ptr;
1319 int ret;
1320
1321 ptr = devres_alloc(devm_devfreq_opp_release, sizeof(*ptr), GFP_KERNEL);
1322 if (!ptr)
1323 return -ENOMEM;
1324
1325 ret = devfreq_register_opp_notifier(dev, devfreq);
1326 if (ret) {
1327 devres_free(ptr);
1328 return ret;
1329 }
1330
1331 *ptr = devfreq;
1332 devres_add(dev, ptr);
1333
1334 return 0;
1335}
1336EXPORT_SYMBOL(devm_devfreq_register_opp_notifier);
1337
1338/**
1339 * devm_devfreq_unregister_opp_notifier()
1340 * - Resource-managed devfreq_unregister_opp_notifier()
1341 * @dev: The devfreq user device. (parent of devfreq)
1342 * @devfreq: The devfreq object.
1343 */
1344void devm_devfreq_unregister_opp_notifier(struct device *dev,
1345 struct devfreq *devfreq)
1346{
1347 WARN_ON(devres_release(dev, devm_devfreq_opp_release,
1348 devm_devfreq_dev_match, devfreq));
1349}
1350EXPORT_SYMBOL(devm_devfreq_unregister_opp_notifier);
1351
1352/**
1353 * devfreq_register_notifier() - Register a driver with devfreq
1354 * @devfreq: The devfreq object.
1355 * @nb: The notifier block to register.
1356 * @list: DEVFREQ_TRANSITION_NOTIFIER.
1357 */
1358int devfreq_register_notifier(struct devfreq *devfreq,
1359 struct notifier_block *nb,
1360 unsigned int list)
1361{
1362 int ret = 0;
1363
1364 if (!devfreq)
1365 return -EINVAL;
1366
1367 switch (list) {
1368 case DEVFREQ_TRANSITION_NOTIFIER:
1369 ret = srcu_notifier_chain_register(
1370 &devfreq->transition_notifier_list, nb);
1371 break;
1372 default:
1373 ret = -EINVAL;
1374 }
1375
1376 return ret;
1377}
1378EXPORT_SYMBOL(devfreq_register_notifier);
1379
1380/*
1381 * devfreq_unregister_notifier() - Unregister a driver with devfreq
1382 * @devfreq: The devfreq object.
1383 * @nb: The notifier block to be unregistered.
1384 * @list: DEVFREQ_TRANSITION_NOTIFIER.
1385 */
1386int devfreq_unregister_notifier(struct devfreq *devfreq,
1387 struct notifier_block *nb,
1388 unsigned int list)
1389{
1390 int ret = 0;
1391
1392 if (!devfreq)
1393 return -EINVAL;
1394
1395 switch (list) {
1396 case DEVFREQ_TRANSITION_NOTIFIER:
1397 ret = srcu_notifier_chain_unregister(
1398 &devfreq->transition_notifier_list, nb);
1399 break;
1400 default:
1401 ret = -EINVAL;
1402 }
1403
1404 return ret;
1405}
1406EXPORT_SYMBOL(devfreq_unregister_notifier);
1407
1408struct devfreq_notifier_devres {
1409 struct devfreq *devfreq;
1410 struct notifier_block *nb;
1411 unsigned int list;
1412};
1413
1414static void devm_devfreq_notifier_release(struct device *dev, void *res)
1415{
1416 struct devfreq_notifier_devres *this = res;
1417
1418 devfreq_unregister_notifier(this->devfreq, this->nb, this->list);
1419}
1420
1421/**
1422 * devm_devfreq_register_notifier()
1423 - Resource-managed devfreq_register_notifier()
1424 * @dev: The devfreq user device. (parent of devfreq)
1425 * @devfreq: The devfreq object.
1426 * @nb: The notifier block to be unregistered.
1427 * @list: DEVFREQ_TRANSITION_NOTIFIER.
1428 */
1429int devm_devfreq_register_notifier(struct device *dev,
1430 struct devfreq *devfreq,
1431 struct notifier_block *nb,
1432 unsigned int list)
1433{
1434 struct devfreq_notifier_devres *ptr;
1435 int ret;
1436
1437 ptr = devres_alloc(devm_devfreq_notifier_release, sizeof(*ptr),
1438 GFP_KERNEL);
1439 if (!ptr)
1440 return -ENOMEM;
1441
1442 ret = devfreq_register_notifier(devfreq, nb, list);
1443 if (ret) {
1444 devres_free(ptr);
1445 return ret;
1446 }
1447
1448 ptr->devfreq = devfreq;
1449 ptr->nb = nb;
1450 ptr->list = list;
1451 devres_add(dev, ptr);
1452
1453 return 0;
1454}
1455EXPORT_SYMBOL(devm_devfreq_register_notifier);
1456
1457/**
1458 * devm_devfreq_unregister_notifier()
1459 - Resource-managed devfreq_unregister_notifier()
1460 * @dev: The devfreq user device. (parent of devfreq)
1461 * @devfreq: The devfreq object.
1462 * @nb: The notifier block to be unregistered.
1463 * @list: DEVFREQ_TRANSITION_NOTIFIER.
1464 */
1465void devm_devfreq_unregister_notifier(struct device *dev,
1466 struct devfreq *devfreq,
1467 struct notifier_block *nb,
1468 unsigned int list)
1469{
1470 WARN_ON(devres_release(dev, devm_devfreq_notifier_release,
1471 devm_devfreq_dev_match, devfreq));
1472}
1473EXPORT_SYMBOL(devm_devfreq_unregister_notifier);
1474
1475MODULE_AUTHOR("MyungJoo Ham <[email protected]>");
1476MODULE_DESCRIPTION("devfreq class support");
1477MODULE_LICENSE("GPL");