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