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Root/drivers/devfreq/devfreq.c

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/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
30	static 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	*/
37	static struct workqueue_struct *devfreq_wq;
38
39	/* The list of all device-devfreq governors */
40	static LIST_HEAD(devfreq_governor_list);
41	/* The list of all device-devfreq */
42	static LIST_HEAD(devfreq_list);
43	static 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	*/
52	static 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	*/
76	static 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	*/
92	static 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	*/
123	static 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	*/
151	int 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	}
199	EXPORT_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	*/
206	static 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	*/
231	void 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	}
238	EXPORT_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	*/
248	void devfreq_monitor_stop(struct devfreq *devfreq)
249	{
250	cancel_delayed_work_sync(&devfreq->work);
251	}
252	EXPORT_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	*/
266	void 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->stop_polling = true;
275	mutex_unlock(&devfreq->lock);
276	cancel_delayed_work_sync(&devfreq->work);
277	}
278	EXPORT_SYMBOL(devfreq_monitor_suspend);
279
280	/**
281	* devfreq_monitor_resume() - Resume load monitoring of a devfreq instance
282	* @devfreq: the devfreq instance.
283	*
284	* Helper function to resume devfreq device load monitoing. Function
285	* to be called from governor in response to DEVFREQ_GOV_RESUME
286	* event or when polling interval is set to non-zero.
287	*/
288	void devfreq_monitor_resume(struct devfreq *devfreq)
289	{
290	mutex_lock(&devfreq->lock);
291	if (!devfreq->stop_polling)
292	goto out;
293
294	if (!delayed_work_pending(&devfreq->work) &&
295	devfreq->profile->polling_ms)
296	queue_delayed_work(devfreq_wq, &devfreq->work,
297	msecs_to_jiffies(devfreq->profile->polling_ms));
298	devfreq->stop_polling = false;
299
300	out:
301	mutex_unlock(&devfreq->lock);
302	}
303	EXPORT_SYMBOL(devfreq_monitor_resume);
304
305	/**
306	* devfreq_interval_update() - Update device devfreq monitoring interval
307	* @devfreq: the devfreq instance.
308	* @delay: new polling interval to be set.
309	*
310	* Helper function to set new load monitoring polling interval. Function
311	* to be called from governor in response to DEVFREQ_GOV_INTERVAL event.
312	*/
313	void devfreq_interval_update(struct devfreq devfreq, unsigned int delay)
314	{
315	unsigned int cur_delay = devfreq->profile->polling_ms;
316	unsigned int new_delay = *delay;
317
318	mutex_lock(&devfreq->lock);
319	devfreq->profile->polling_ms = new_delay;
320
321	if (devfreq->stop_polling)
322	goto out;
323
324	/* if new delay is zero, stop polling */
325	if (!new_delay) {
326	mutex_unlock(&devfreq->lock);
327	cancel_delayed_work_sync(&devfreq->work);
328	return;
329	}
330
331	/* if current delay is zero, start polling with new delay */
332	if (!cur_delay) {
333	queue_delayed_work(devfreq_wq, &devfreq->work,
334	msecs_to_jiffies(devfreq->profile->polling_ms));
335	goto out;
336	}
337
338	/* if current delay is greater than new delay, restart polling */
339	if (cur_delay > new_delay) {
340	mutex_unlock(&devfreq->lock);
341	cancel_delayed_work_sync(&devfreq->work);
342	mutex_lock(&devfreq->lock);
343	if (!devfreq->stop_polling)
344	queue_delayed_work(devfreq_wq, &devfreq->work,
345	msecs_to_jiffies(devfreq->profile->polling_ms));
346	}
347	out:
348	mutex_unlock(&devfreq->lock);
349	}
350	EXPORT_SYMBOL(devfreq_interval_update);
351
352	/**
353	* devfreq_notifier_call() - Notify that the device frequency requirements
354	* has been changed out of devfreq framework.
355	* @nb: the notifier_block (supposed to be devfreq->nb)
356	* @type: not used
357	* @devp: not used
358	*
359	* Called by a notifier that uses devfreq->nb.
360	*/
361	static int devfreq_notifier_call(struct notifier_block *nb, unsigned long type,
362	void *devp)
363	{
364	struct devfreq *devfreq = container_of(nb, struct devfreq, nb);
365	int ret;
366
367	mutex_lock(&devfreq->lock);
368	ret = update_devfreq(devfreq);
369	mutex_unlock(&devfreq->lock);
370
371	return ret;
372	}
373
374	/**
375	* _remove_devfreq() - Remove devfreq from the list and release its resources.
376	* @devfreq: the devfreq struct
377	* @skip: skip calling device_unregister().
378	*/
379	static void _remove_devfreq(struct devfreq *devfreq, bool skip)
380	{
381	mutex_lock(&devfreq_list_lock);
382	if (IS_ERR(find_device_devfreq(devfreq->dev.parent))) {
383	mutex_unlock(&devfreq_list_lock);
384	dev_warn(&devfreq->dev, "releasing devfreq which doesn't exist\n");
385	return;
386	}
387	list_del(&devfreq->node);
388	mutex_unlock(&devfreq_list_lock);
389
390	if (devfreq->governor)
391	devfreq->governor->event_handler(devfreq,
392	DEVFREQ_GOV_STOP, NULL);
393
394	if (devfreq->profile->exit)
395	devfreq->profile->exit(devfreq->dev.parent);
396
397	if (!skip && get_device(&devfreq->dev)) {
398	device_unregister(&devfreq->dev);
399	put_device(&devfreq->dev);
400	}
401
402	mutex_destroy(&devfreq->lock);
403	kfree(devfreq);
404	}
405
406	/**
407	* devfreq_dev_release() - Callback for struct device to release the device.
408	* @dev: the devfreq device
409	*
410	* This calls _remove_devfreq() if _remove_devfreq() is not called.
411	* Note that devfreq_dev_release() could be called by _remove_devfreq() as
412	* well as by others unregistering the device.
413	*/
414	static void devfreq_dev_release(struct device *dev)
415	{
416	struct devfreq *devfreq = to_devfreq(dev);
417
418	_remove_devfreq(devfreq, true);
419	}
420
421	/**
422	* devfreq_add_device() - Add devfreq feature to the device
423	* @dev: the device to add devfreq feature.
424	* @profile: device-specific profile to run devfreq.
425	* @governor_name: name of the policy to choose frequency.
426	* @data: private data for the governor. The devfreq framework does not
427	* touch this value.
428	*/
429	struct devfreq devfreq_add_device(struct device dev,
430	struct devfreq_dev_profile *profile,
431	const char *governor_name,
432	void *data)
433	{
434	struct devfreq *devfreq;
435	struct devfreq_governor *governor;
436	int err = 0;
437
438	if (!dev \|\| !profile \|\| !governor_name) {
439	dev_err(dev, "%s: Invalid parameters.\n", __func__);
440	return ERR_PTR(-EINVAL);
441	}
442
443	mutex_lock(&devfreq_list_lock);
444	devfreq = find_device_devfreq(dev);
445	mutex_unlock(&devfreq_list_lock);
446	if (!IS_ERR(devfreq)) {
447	dev_err(dev, "%s: Unable to create devfreq for the device. It already has one.\n", __func__);
448	err = -EINVAL;
449	goto err_out;
450	}
451
452	devfreq = kzalloc(sizeof(struct devfreq), GFP_KERNEL);
453	if (!devfreq) {
454	dev_err(dev, "%s: Unable to create devfreq for the device\n",
455	__func__);
456	err = -ENOMEM;
457	goto err_out;
458	}
459
460	mutex_init(&devfreq->lock);
461	mutex_lock(&devfreq->lock);
462	devfreq->dev.parent = dev;
463	devfreq->dev.class = devfreq_class;
464	devfreq->dev.release = devfreq_dev_release;
465	devfreq->profile = profile;
466	strncpy(devfreq->governor_name, governor_name, DEVFREQ_NAME_LEN);
467	devfreq->previous_freq = profile->initial_freq;
468	devfreq->data = data;
469	devfreq->nb.notifier_call = devfreq_notifier_call;
470
471	devfreq->trans_table = devm_kzalloc(dev, sizeof(unsigned int) *
472	devfreq->profile->max_state *
473	devfreq->profile->max_state,
474	GFP_KERNEL);
475	devfreq->time_in_state = devm_kzalloc(dev, sizeof(unsigned int) *
476	devfreq->profile->max_state,
477	GFP_KERNEL);
478	devfreq->last_stat_updated = jiffies;
479
480	dev_set_name(&devfreq->dev, dev_name(dev));
481	err = device_register(&devfreq->dev);
482	if (err) {
483	put_device(&devfreq->dev);
484	mutex_unlock(&devfreq->lock);
485	goto err_dev;
486	}
487
488	mutex_unlock(&devfreq->lock);
489
490	mutex_lock(&devfreq_list_lock);
491	list_add(&devfreq->node, &devfreq_list);
492
493	governor = find_devfreq_governor(devfreq->governor_name);
494	if (!IS_ERR(governor))
495	devfreq->governor = governor;
496	if (devfreq->governor)
497	err = devfreq->governor->event_handler(devfreq,
498	DEVFREQ_GOV_START, NULL);
499	mutex_unlock(&devfreq_list_lock);
500	if (err) {
501	dev_err(dev, "%s: Unable to start governor for the device\n",
502	__func__);
503	goto err_init;
504	}
505
506	return devfreq;
507
508	err_init:
509	list_del(&devfreq->node);
510	device_unregister(&devfreq->dev);
511	err_dev:
512	kfree(devfreq);
513	err_out:
514	return ERR_PTR(err);
515	}
516	EXPORT_SYMBOL(devfreq_add_device);
517
518	/**
519	* devfreq_remove_device() - Remove devfreq feature from a device.
520	* @devfreq: the devfreq instance to be removed
521	*/
522	int devfreq_remove_device(struct devfreq *devfreq)
523	{
524	if (!devfreq)
525	return -EINVAL;
526
527	_remove_devfreq(devfreq, false);
528
529	return 0;
530	}
531	EXPORT_SYMBOL(devfreq_remove_device);
532
533	/**
534	* devfreq_suspend_device() - Suspend devfreq of a device.
535	* @devfreq: the devfreq instance to be suspended
536	*/
537	int devfreq_suspend_device(struct devfreq *devfreq)
538	{
539	if (!devfreq)
540	return -EINVAL;
541
542	if (!devfreq->governor)
543	return 0;
544
545	return devfreq->governor->event_handler(devfreq,
546	DEVFREQ_GOV_SUSPEND, NULL);
547	}
548	EXPORT_SYMBOL(devfreq_suspend_device);
549
550	/**
551	* devfreq_resume_device() - Resume devfreq of a device.
552	* @devfreq: the devfreq instance to be resumed
553	*/
554	int devfreq_resume_device(struct devfreq *devfreq)
555	{
556	if (!devfreq)
557	return -EINVAL;
558
559	if (!devfreq->governor)
560	return 0;
561
562	return devfreq->governor->event_handler(devfreq,
563	DEVFREQ_GOV_RESUME, NULL);
564	}
565	EXPORT_SYMBOL(devfreq_resume_device);
566
567	/**
568	* devfreq_add_governor() - Add devfreq governor
569	* @governor: the devfreq governor to be added
570	*/
571	int devfreq_add_governor(struct devfreq_governor *governor)
572	{
573	struct devfreq_governor *g;
574	struct devfreq *devfreq;
575	int err = 0;
576
577	if (!governor) {
578	pr_err("%s: Invalid parameters.\n", __func__);
579	return -EINVAL;
580	}
581
582	mutex_lock(&devfreq_list_lock);
583	g = find_devfreq_governor(governor->name);
584	if (!IS_ERR(g)) {
585	pr_err("%s: governor %s already registered\n", __func__,
586	g->name);
587	err = -EINVAL;
588	goto err_out;
589	}
590
591	list_add(&governor->node, &devfreq_governor_list);
592
593	list_for_each_entry(devfreq, &devfreq_list, node) {
594	int ret = 0;
595	struct device *dev = devfreq->dev.parent;
596
597	if (!strncmp(devfreq->governor_name, governor->name,
598	DEVFREQ_NAME_LEN)) {
599	/* The following should never occur */
600	if (devfreq->governor) {
601	dev_warn(dev,
602	"%s: Governor %s already present\n",
603	__func__, devfreq->governor->name);
604	ret = devfreq->governor->event_handler(devfreq,
605	DEVFREQ_GOV_STOP, NULL);
606	if (ret) {
607	dev_warn(dev,
608	"%s: Governor %s stop = %d\n",
609	__func__,
610	devfreq->governor->name, ret);
611	}
612	/* Fall through */
613	}
614	devfreq->governor = governor;
615	ret = devfreq->governor->event_handler(devfreq,
616	DEVFREQ_GOV_START, NULL);
617	if (ret) {
618	dev_warn(dev, "%s: Governor %s start=%d\n",
619	__func__, devfreq->governor->name,
620	ret);
621	}
622	}
623	}
624
625	err_out:
626	mutex_unlock(&devfreq_list_lock);
627
628	return err;
629	}
630	EXPORT_SYMBOL(devfreq_add_governor);
631
632	/**
633	* devfreq_remove_device() - Remove devfreq feature from a device.
634	* @governor: the devfreq governor to be removed
635	*/
636	int devfreq_remove_governor(struct devfreq_governor *governor)
637	{
638	struct devfreq_governor *g;
639	struct devfreq *devfreq;
640	int err = 0;
641
642	if (!governor) {
643	pr_err("%s: Invalid parameters.\n", __func__);
644	return -EINVAL;
645	}
646
647	mutex_lock(&devfreq_list_lock);
648	g = find_devfreq_governor(governor->name);
649	if (IS_ERR(g)) {
650	pr_err("%s: governor %s not registered\n", __func__,
651	governor->name);
652	err = PTR_ERR(g);
653	goto err_out;
654	}
655	list_for_each_entry(devfreq, &devfreq_list, node) {
656	int ret;
657	struct device *dev = devfreq->dev.parent;
658
659	if (!strncmp(devfreq->governor_name, governor->name,
660	DEVFREQ_NAME_LEN)) {
661	/* we should have a devfreq governor! */
662	if (!devfreq->governor) {
663	dev_warn(dev, "%s: Governor %s NOT present\n",
664	__func__, governor->name);
665	continue;
666	/* Fall through */
667	}
668	ret = devfreq->governor->event_handler(devfreq,
669	DEVFREQ_GOV_STOP, NULL);
670	if (ret) {
671	dev_warn(dev, "%s: Governor %s stop=%d\n",
672	__func__, devfreq->governor->name,
673	ret);
674	}
675	devfreq->governor = NULL;
676	}
677	}
678
679	list_del(&governor->node);
680	err_out:
681	mutex_unlock(&devfreq_list_lock);
682
683	return err;
684	}
685	EXPORT_SYMBOL(devfreq_remove_governor);
686
687	static ssize_t show_governor(struct device *dev,
688	struct device_attribute attr, char buf)
689	{
690	if (!to_devfreq(dev)->governor)
691	return -EINVAL;
692
693	return sprintf(buf, "%s\n", to_devfreq(dev)->governor->name);
694	}
695
696	static ssize_t store_governor(struct device dev, struct device_attribute attr,
697	const char *buf, size_t count)
698	{
699	struct devfreq *df = to_devfreq(dev);
700	int ret;
701	char str_governor[DEVFREQ_NAME_LEN + 1];
702	struct devfreq_governor *governor;
703
704	ret = sscanf(buf, "%" __stringify(DEVFREQ_NAME_LEN) "s", str_governor);
705	if (ret != 1)
706	return -EINVAL;
707
708	mutex_lock(&devfreq_list_lock);
709	governor = find_devfreq_governor(str_governor);
710	if (IS_ERR(governor)) {
711	ret = PTR_ERR(governor);
712	goto out;
713	}
714	if (df->governor == governor)
715	goto out;
716
717	if (df->governor) {
718	ret = df->governor->event_handler(df, DEVFREQ_GOV_STOP, NULL);
719	if (ret) {
720	dev_warn(dev, "%s: Governor %s not stopped(%d)\n",
721	__func__, df->governor->name, ret);
722	goto out;
723	}
724	}
725	df->governor = governor;
726	strncpy(df->governor_name, governor->name, DEVFREQ_NAME_LEN);
727	ret = df->governor->event_handler(df, DEVFREQ_GOV_START, NULL);
728	if (ret)
729	dev_warn(dev, "%s: Governor %s not started(%d)\n",
730	__func__, df->governor->name, ret);
731	out:
732	mutex_unlock(&devfreq_list_lock);
733
734	if (!ret)
735	ret = count;
736	return ret;
737	}
738	static ssize_t show_available_governors(struct device *d,
739	struct device_attribute *attr,
740	char *buf)
741	{
742	struct devfreq_governor *tmp_governor;
743	ssize_t count = 0;
744
745	mutex_lock(&devfreq_list_lock);
746	list_for_each_entry(tmp_governor, &devfreq_governor_list, node)
747	count += scnprintf(&buf[count], (PAGE_SIZE - count - 2),
748	"%s ", tmp_governor->name);
749	mutex_unlock(&devfreq_list_lock);
750
751	/* Truncate the trailing space */
752	if (count)
753	count--;
754
755	count += sprintf(&buf[count], "\n");
756
757	return count;
758	}
759
760	static ssize_t show_freq(struct device *dev,
761	struct device_attribute attr, char buf)
762	{
763	unsigned long freq;
764	struct devfreq *devfreq = to_devfreq(dev);
765
766	if (devfreq->profile->get_cur_freq &&
767	!devfreq->profile->get_cur_freq(devfreq->dev.parent, &freq))
768	return sprintf(buf, "%lu\n", freq);
769
770	return sprintf(buf, "%lu\n", devfreq->previous_freq);
771	}
772
773	static ssize_t show_target_freq(struct device *dev,
774	struct device_attribute attr, char buf)
775	{
776	return sprintf(buf, "%lu\n", to_devfreq(dev)->previous_freq);
777	}
778
779	static ssize_t show_polling_interval(struct device *dev,
780	struct device_attribute attr, char buf)
781	{
782	return sprintf(buf, "%d\n", to_devfreq(dev)->profile->polling_ms);
783	}
784
785	static ssize_t store_polling_interval(struct device *dev,
786	struct device_attribute *attr,
787	const char *buf, size_t count)
788	{
789	struct devfreq *df = to_devfreq(dev);
790	unsigned int value;
791	int ret;
792
793	if (!df->governor)
794	return -EINVAL;
795
796	ret = sscanf(buf, "%u", &value);
797	if (ret != 1)
798	return -EINVAL;
799
800	df->governor->event_handler(df, DEVFREQ_GOV_INTERVAL, &value);
801	ret = count;
802
803	return ret;
804	}
805
806	static ssize_t store_min_freq(struct device dev, struct device_attribute attr,
807	const char *buf, size_t count)
808	{
809	struct devfreq *df = to_devfreq(dev);
810	unsigned long value;
811	int ret;
812	unsigned long max;
813
814	ret = sscanf(buf, "%lu", &value);
815	if (ret != 1)
816	return -EINVAL;
817
818	mutex_lock(&df->lock);
819	max = df->max_freq;
820	if (value && max && value > max) {
821	ret = -EINVAL;
822	goto unlock;
823	}
824
825	df->min_freq = value;
826	update_devfreq(df);
827	ret = count;
828	unlock:
829	mutex_unlock(&df->lock);
830	return ret;
831	}
832
833	static ssize_t show_min_freq(struct device dev, struct device_attribute attr,
834	char *buf)
835	{
836	return sprintf(buf, "%lu\n", to_devfreq(dev)->min_freq);
837	}
838
839	static ssize_t store_max_freq(struct device dev, struct device_attribute attr,
840	const char *buf, size_t count)
841	{
842	struct devfreq *df = to_devfreq(dev);
843	unsigned long value;
844	int ret;
845	unsigned long min;
846
847	ret = sscanf(buf, "%lu", &value);
848	if (ret != 1)
849	return -EINVAL;
850
851	mutex_lock(&df->lock);
852	min = df->min_freq;
853	if (value && min && value < min) {
854	ret = -EINVAL;
855	goto unlock;
856	}
857
858	df->max_freq = value;
859	update_devfreq(df);
860	ret = count;
861	unlock:
862	mutex_unlock(&df->lock);
863	return ret;
864	}
865
866	static ssize_t show_max_freq(struct device dev, struct device_attribute attr,
867	char *buf)
868	{
869	return sprintf(buf, "%lu\n", to_devfreq(dev)->max_freq);
870	}
871
872	static ssize_t show_available_freqs(struct device *d,
873	struct device_attribute *attr,
874	char *buf)
875	{
876	struct devfreq *df = to_devfreq(d);
877	struct device *dev = df->dev.parent;
878	struct opp *opp;
879	ssize_t count = 0;
880	unsigned long freq = 0;
881
882	rcu_read_lock();
883	do {
884	opp = opp_find_freq_ceil(dev, &freq);
885	if (IS_ERR(opp))
886	break;
887
888	count += scnprintf(&buf[count], (PAGE_SIZE - count - 2),
889	"%lu ", freq);
890	freq++;
891	} while (1);
892	rcu_read_unlock();
893
894	/* Truncate the trailing space */
895	if (count)
896	count--;
897
898	count += sprintf(&buf[count], "\n");
899
900	return count;
901	}
902
903	static ssize_t show_trans_table(struct device dev, struct device_attribute attr,
904	char *buf)
905	{
906	struct devfreq *devfreq = to_devfreq(dev);
907	ssize_t len;
908	int i, j, err;
909	unsigned int max_state = devfreq->profile->max_state;
910
911	err = devfreq_update_status(devfreq, devfreq->previous_freq);
912	if (err)
913	return 0;
914
915	len = sprintf(buf, " From : To\n");
916	len += sprintf(buf + len, " :");
917	for (i = 0; i < max_state; i++)
918	len += sprintf(buf + len, "%8u",
919	devfreq->profile->freq_table[i]);
920
921	len += sprintf(buf + len, " time(ms)\n");
922
923	for (i = 0; i < max_state; i++) {
924	if (devfreq->profile->freq_table[i]
925	== devfreq->previous_freq) {
926	len += sprintf(buf + len, "*");
927	} else {
928	len += sprintf(buf + len, " ");
929	}
930	len += sprintf(buf + len, "%8u:",
931	devfreq->profile->freq_table[i]);
932	for (j = 0; j < max_state; j++)
933	len += sprintf(buf + len, "%8u",
934	devfreq->trans_table[(i * max_state) + j]);
935	len += sprintf(buf + len, "%10u\n",
936	jiffies_to_msecs(devfreq->time_in_state[i]));
937	}
938
939	len += sprintf(buf + len, "Total transition : %u\n",
940	devfreq->total_trans);
941	return len;
942	}
943
944	static struct device_attribute devfreq_attrs[] = {
945	__ATTR(governor, S_IRUGO \| S_IWUSR, show_governor, store_governor),
946	__ATTR(available_governors, S_IRUGO, show_available_governors, NULL),
947	__ATTR(cur_freq, S_IRUGO, show_freq, NULL),
948	__ATTR(available_frequencies, S_IRUGO, show_available_freqs, NULL),
949	__ATTR(target_freq, S_IRUGO, show_target_freq, NULL),
950	__ATTR(polling_interval, S_IRUGO \| S_IWUSR, show_polling_interval,
951	store_polling_interval),
952	__ATTR(min_freq, S_IRUGO \| S_IWUSR, show_min_freq, store_min_freq),
953	__ATTR(max_freq, S_IRUGO \| S_IWUSR, show_max_freq, store_max_freq),
954	__ATTR(trans_stat, S_IRUGO, show_trans_table, NULL),
955	{ },
956	};
957
958	static int __init devfreq_init(void)
959	{
960	devfreq_class = class_create(THIS_MODULE, "devfreq");
961	if (IS_ERR(devfreq_class)) {
962	pr_err("%s: couldn't create class\n", __FILE__);
963	return PTR_ERR(devfreq_class);
964	}
965
966	devfreq_wq = create_freezable_workqueue("devfreq_wq");
967	if (IS_ERR(devfreq_wq)) {
968	class_destroy(devfreq_class);
969	pr_err("%s: couldn't create workqueue\n", __FILE__);
970	return PTR_ERR(devfreq_wq);
971	}
972	devfreq_class->dev_attrs = devfreq_attrs;
973
974	return 0;
975	}
976	subsys_initcall(devfreq_init);
977
978	static void __exit devfreq_exit(void)
979	{
980	class_destroy(devfreq_class);
981	destroy_workqueue(devfreq_wq);
982	}
983	module_exit(devfreq_exit);
984
985	/*
986	* The followings are helper functions for devfreq user device drivers with
987	* OPP framework.
988	*/
989
990	/**
991	* devfreq_recommended_opp() - Helper function to get proper OPP for the
992	* freq value given to target callback.
993	* @dev: The devfreq user device. (parent of devfreq)
994	* @freq: The frequency given to target function
995	* @flags: Flags handed from devfreq framework.
996	*
997	* Locking: This function must be called under rcu_read_lock(). opp is a rcu
998	* protected pointer. The reason for the same is that the opp pointer which is
999	* returned will remain valid for use with opp_get_{voltage, freq} only while
1000	* under the locked area. The pointer returned must be used prior to unlocking
1001	* with rcu_read_unlock() to maintain the integrity of the pointer.
1002	*/
1003	struct opp devfreq_recommended_opp(struct device dev, unsigned long *freq,
1004	u32 flags)
1005	{
1006	struct opp *opp;
1007
1008	if (flags & DEVFREQ_FLAG_LEAST_UPPER_BOUND) {
1009	/* The freq is an upper bound. opp should be lower */
1010	opp = opp_find_freq_floor(dev, freq);
1011
1012	/* If not available, use the closest opp */
1013	if (opp == ERR_PTR(-ERANGE))
1014	opp = opp_find_freq_ceil(dev, freq);
1015	} else {
1016	/* The freq is an lower bound. opp should be higher */
1017	opp = opp_find_freq_ceil(dev, freq);
1018
1019	/* If not available, use the closest opp */
1020	if (opp == ERR_PTR(-ERANGE))
1021	opp = opp_find_freq_floor(dev, freq);
1022	}
1023
1024	return opp;
1025	}
1026
1027	/**
1028	* devfreq_register_opp_notifier() - Helper function to get devfreq notified
1029	* for any changes in the OPP availability
1030	* changes
1031	* @dev: The devfreq user device. (parent of devfreq)
1032	* @devfreq: The devfreq object.
1033	*/
1034	int devfreq_register_opp_notifier(struct device dev, struct devfreq devfreq)
1035	{
1036	struct srcu_notifier_head *nh;
1037	int ret = 0;
1038
1039	rcu_read_lock();
1040	nh = opp_get_notifier(dev);
1041	if (IS_ERR(nh))
1042	ret = PTR_ERR(nh);
1043	rcu_read_unlock();
1044	if (!ret)
1045	ret = srcu_notifier_chain_register(nh, &devfreq->nb);
1046
1047	return ret;
1048	}
1049
1050	/**
1051	* devfreq_unregister_opp_notifier() - Helper function to stop getting devfreq
1052	* notified for any changes in the OPP
1053	* availability changes anymore.
1054	* @dev: The devfreq user device. (parent of devfreq)
1055	* @devfreq: The devfreq object.
1056	*
1057	* At exit() callback of devfreq_dev_profile, this must be included if
1058	* devfreq_recommended_opp is used.
1059	*/
1060	int devfreq_unregister_opp_notifier(struct device dev, struct devfreq devfreq)
1061	{
1062	struct srcu_notifier_head *nh;
1063	int ret = 0;
1064
1065	rcu_read_lock();
1066	nh = opp_get_notifier(dev);
1067	if (IS_ERR(nh))
1068	ret = PTR_ERR(nh);
1069	rcu_read_unlock();
1070	if (!ret)
1071	ret = srcu_notifier_chain_unregister(nh, &devfreq->nb);
1072
1073	return ret;
1074	}
1075
1076	MODULE_AUTHOR("MyungJoo Ham <myungjoo.ham@samsung.com>");
1077	MODULE_DESCRIPTION("devfreq class support");
1078	MODULE_LICENSE("GPL");
1079

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