projects/linux·blob v3.13 · refs

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