2 * devfreq: Generic Dynamic Voltage and Frequency Scaling (DVFS) Framework
5 * Copyright (C) 2011 Samsung Electronics
6 * MyungJoo Ham <myungjoo.ham@samsung.com>
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.
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>
30 static struct class *devfreq_class;
33 * devfreq core provides delayed work based load monitoring helper
34 * functions. Governors can use these or can implement their own
35 * monitoring mechanism.
37 static struct workqueue_struct *devfreq_wq;
39 /* The list of all device-devfreq */
40 static LIST_HEAD(devfreq_list);
41 static DEFINE_MUTEX(devfreq_list_lock);
44 * find_device_devfreq() - find devfreq struct using device pointer
45 * @dev: device pointer used to lookup device devfreq.
47 * Search the list of device devfreqs and return the matched device's
48 * devfreq info. devfreq_list_lock should be held by the caller.
50 static struct devfreq *find_device_devfreq(struct device *dev)
52 struct devfreq *tmp_devfreq;
54 if (unlikely(IS_ERR_OR_NULL(dev))) {
55 pr_err("DEVFREQ: %s: Invalid parameters\n", __func__);
56 return ERR_PTR(-EINVAL);
58 WARN(!mutex_is_locked(&devfreq_list_lock),
59 "devfreq_list_lock must be locked.");
61 list_for_each_entry(tmp_devfreq, &devfreq_list, node) {
62 if (tmp_devfreq->dev.parent == dev)
66 return ERR_PTR(-ENODEV);
70 * devfreq_get_freq_level() - Lookup freq_table for the frequency
71 * @devfreq: the devfreq instance
72 * @freq: the target frequency
74 static int devfreq_get_freq_level(struct devfreq *devfreq, unsigned long freq)
78 for (lev = 0; lev < devfreq->profile->max_state; lev++)
79 if (freq == devfreq->profile->freq_table[lev])
86 * devfreq_update_status() - Update statistics of devfreq behavior
87 * @devfreq: the devfreq instance
88 * @freq: the update target frequency
90 static int devfreq_update_status(struct devfreq *devfreq, unsigned long freq)
93 unsigned long cur_time;
95 lev = devfreq_get_freq_level(devfreq, freq);
100 devfreq->time_in_state[lev] +=
101 cur_time - devfreq->last_stat_updated;
102 if (freq != devfreq->previous_freq) {
103 prev_lev = devfreq_get_freq_level(devfreq,
104 devfreq->previous_freq);
105 devfreq->trans_table[(prev_lev *
106 devfreq->profile->max_state) + lev]++;
107 devfreq->total_trans++;
109 devfreq->last_stat_updated = cur_time;
114 /* Load monitoring helper functions for governors use */
117 * update_devfreq() - Reevaluate the device and configure frequency.
118 * @devfreq: the devfreq instance.
120 * Note: Lock devfreq->lock before calling update_devfreq
121 * This function is exported for governors.
123 int update_devfreq(struct devfreq *devfreq)
129 if (!mutex_is_locked(&devfreq->lock)) {
130 WARN(true, "devfreq->lock must be locked by the caller.\n");
134 /* Reevaluate the proper frequency */
135 err = devfreq->governor->get_target_freq(devfreq, &freq);
140 * Adjust the freuqency with user freq and QoS.
142 * List from the highest proiority
143 * max_freq (probably called by thermal when it's too hot)
147 if (devfreq->min_freq && freq < devfreq->min_freq) {
148 freq = devfreq->min_freq;
149 flags &= ~DEVFREQ_FLAG_LEAST_UPPER_BOUND; /* Use GLB */
151 if (devfreq->max_freq && freq > devfreq->max_freq) {
152 freq = devfreq->max_freq;
153 flags |= DEVFREQ_FLAG_LEAST_UPPER_BOUND; /* Use LUB */
156 err = devfreq->profile->target(devfreq->dev.parent, &freq, flags);
160 if (devfreq->profile->freq_table)
161 if (devfreq_update_status(devfreq, freq))
162 dev_err(&devfreq->dev,
163 "Couldn't update frequency transition information.\n");
165 devfreq->previous_freq = freq;
168 EXPORT_SYMBOL(update_devfreq);
171 * devfreq_monitor() - Periodically poll devfreq objects.
172 * @work: the work struct used to run devfreq_monitor periodically.
175 static void devfreq_monitor(struct work_struct *work)
178 struct devfreq *devfreq = container_of(work,
179 struct devfreq, work.work);
181 mutex_lock(&devfreq->lock);
182 err = update_devfreq(devfreq);
184 dev_err(&devfreq->dev, "dvfs failed with (%d) error\n", err);
186 queue_delayed_work(devfreq_wq, &devfreq->work,
187 msecs_to_jiffies(devfreq->profile->polling_ms));
188 mutex_unlock(&devfreq->lock);
192 * devfreq_monitor_start() - Start load monitoring of devfreq instance
193 * @devfreq: the devfreq instance.
195 * Helper function for starting devfreq device load monitoing. By
196 * default delayed work based monitoring is supported. Function
197 * to be called from governor in response to DEVFREQ_GOV_START
198 * event when device is added to devfreq framework.
200 void devfreq_monitor_start(struct devfreq *devfreq)
202 INIT_DEFERRABLE_WORK(&devfreq->work, devfreq_monitor);
203 if (devfreq->profile->polling_ms)
204 queue_delayed_work(devfreq_wq, &devfreq->work,
205 msecs_to_jiffies(devfreq->profile->polling_ms));
209 * devfreq_monitor_stop() - Stop load monitoring of a devfreq instance
210 * @devfreq: the devfreq instance.
212 * Helper function to stop devfreq device load monitoing. Function
213 * to be called from governor in response to DEVFREQ_GOV_STOP
214 * event when device is removed from devfreq framework.
216 void devfreq_monitor_stop(struct devfreq *devfreq)
218 cancel_delayed_work_sync(&devfreq->work);
222 * devfreq_monitor_suspend() - Suspend load monitoring of a devfreq instance
223 * @devfreq: the devfreq instance.
225 * Helper function to suspend devfreq device load monitoing. Function
226 * to be called from governor in response to DEVFREQ_GOV_SUSPEND
227 * event or when polling interval is set to zero.
229 * Note: Though this function is same as devfreq_monitor_stop(),
230 * intentionally kept separate to provide hooks for collecting
231 * transition statistics.
233 void devfreq_monitor_suspend(struct devfreq *devfreq)
235 mutex_lock(&devfreq->lock);
236 if (devfreq->stop_polling) {
237 mutex_unlock(&devfreq->lock);
241 devfreq->stop_polling = true;
242 mutex_unlock(&devfreq->lock);
243 cancel_delayed_work_sync(&devfreq->work);
247 * devfreq_monitor_resume() - Resume load monitoring of a devfreq instance
248 * @devfreq: the devfreq instance.
250 * Helper function to resume devfreq device load monitoing. Function
251 * to be called from governor in response to DEVFREQ_GOV_RESUME
252 * event or when polling interval is set to non-zero.
254 void devfreq_monitor_resume(struct devfreq *devfreq)
256 mutex_lock(&devfreq->lock);
257 if (!devfreq->stop_polling)
260 if (!delayed_work_pending(&devfreq->work) &&
261 devfreq->profile->polling_ms)
262 queue_delayed_work(devfreq_wq, &devfreq->work,
263 msecs_to_jiffies(devfreq->profile->polling_ms));
264 devfreq->stop_polling = false;
267 mutex_unlock(&devfreq->lock);
271 * devfreq_interval_update() - Update device devfreq monitoring interval
272 * @devfreq: the devfreq instance.
273 * @delay: new polling interval to be set.
275 * Helper function to set new load monitoring polling interval. Function
276 * to be called from governor in response to DEVFREQ_GOV_INTERVAL event.
278 void devfreq_interval_update(struct devfreq *devfreq, unsigned int *delay)
280 unsigned int cur_delay = devfreq->profile->polling_ms;
281 unsigned int new_delay = *delay;
283 mutex_lock(&devfreq->lock);
284 devfreq->profile->polling_ms = new_delay;
286 if (devfreq->stop_polling)
289 /* if new delay is zero, stop polling */
291 mutex_unlock(&devfreq->lock);
292 cancel_delayed_work_sync(&devfreq->work);
296 /* if current delay is zero, start polling with new delay */
298 queue_delayed_work(devfreq_wq, &devfreq->work,
299 msecs_to_jiffies(devfreq->profile->polling_ms));
303 /* if current delay is greater than new delay, restart polling */
304 if (cur_delay > new_delay) {
305 mutex_unlock(&devfreq->lock);
306 cancel_delayed_work_sync(&devfreq->work);
307 mutex_lock(&devfreq->lock);
308 if (!devfreq->stop_polling)
309 queue_delayed_work(devfreq_wq, &devfreq->work,
310 msecs_to_jiffies(devfreq->profile->polling_ms));
313 mutex_unlock(&devfreq->lock);
317 * devfreq_notifier_call() - Notify that the device frequency requirements
318 * has been changed out of devfreq framework.
319 * @nb: the notifier_block (supposed to be devfreq->nb)
323 * Called by a notifier that uses devfreq->nb.
325 static int devfreq_notifier_call(struct notifier_block *nb, unsigned long type,
328 struct devfreq *devfreq = container_of(nb, struct devfreq, nb);
331 mutex_lock(&devfreq->lock);
332 ret = update_devfreq(devfreq);
333 mutex_unlock(&devfreq->lock);
339 * _remove_devfreq() - Remove devfreq from the list and release its resources.
340 * @devfreq: the devfreq struct
341 * @skip: skip calling device_unregister().
343 static void _remove_devfreq(struct devfreq *devfreq, bool skip)
345 mutex_lock(&devfreq_list_lock);
346 if (IS_ERR(find_device_devfreq(devfreq->dev.parent))) {
347 mutex_unlock(&devfreq_list_lock);
348 dev_warn(&devfreq->dev, "releasing devfreq which doesn't exist\n");
351 list_del(&devfreq->node);
352 mutex_unlock(&devfreq_list_lock);
354 devfreq->governor->event_handler(devfreq, DEVFREQ_GOV_STOP, NULL);
356 if (devfreq->profile->exit)
357 devfreq->profile->exit(devfreq->dev.parent);
359 if (!skip && get_device(&devfreq->dev)) {
360 device_unregister(&devfreq->dev);
361 put_device(&devfreq->dev);
364 mutex_destroy(&devfreq->lock);
369 * devfreq_dev_release() - Callback for struct device to release the device.
370 * @dev: the devfreq device
372 * This calls _remove_devfreq() if _remove_devfreq() is not called.
373 * Note that devfreq_dev_release() could be called by _remove_devfreq() as
374 * well as by others unregistering the device.
376 static void devfreq_dev_release(struct device *dev)
378 struct devfreq *devfreq = to_devfreq(dev);
380 _remove_devfreq(devfreq, true);
384 * devfreq_add_device() - Add devfreq feature to the device
385 * @dev: the device to add devfreq feature.
386 * @profile: device-specific profile to run devfreq.
387 * @governor: the policy to choose frequency.
388 * @data: private data for the governor. The devfreq framework does not
391 struct devfreq *devfreq_add_device(struct device *dev,
392 struct devfreq_dev_profile *profile,
393 const struct devfreq_governor *governor,
396 struct devfreq *devfreq;
399 if (!dev || !profile || !governor) {
400 dev_err(dev, "%s: Invalid parameters.\n", __func__);
401 return ERR_PTR(-EINVAL);
404 mutex_lock(&devfreq_list_lock);
405 devfreq = find_device_devfreq(dev);
406 mutex_unlock(&devfreq_list_lock);
407 if (!IS_ERR(devfreq)) {
408 dev_err(dev, "%s: Unable to create devfreq for the device. It already has one.\n", __func__);
413 devfreq = kzalloc(sizeof(struct devfreq), GFP_KERNEL);
415 dev_err(dev, "%s: Unable to create devfreq for the device\n",
421 mutex_init(&devfreq->lock);
422 mutex_lock(&devfreq->lock);
423 devfreq->dev.parent = dev;
424 devfreq->dev.class = devfreq_class;
425 devfreq->dev.release = devfreq_dev_release;
426 devfreq->profile = profile;
427 devfreq->governor = governor;
428 devfreq->previous_freq = profile->initial_freq;
429 devfreq->data = data;
430 devfreq->nb.notifier_call = devfreq_notifier_call;
432 devfreq->trans_table = devm_kzalloc(dev, sizeof(unsigned int) *
433 devfreq->profile->max_state *
434 devfreq->profile->max_state,
436 devfreq->time_in_state = devm_kzalloc(dev, sizeof(unsigned int) *
437 devfreq->profile->max_state,
439 devfreq->last_stat_updated = jiffies;
441 dev_set_name(&devfreq->dev, dev_name(dev));
442 err = device_register(&devfreq->dev);
444 put_device(&devfreq->dev);
445 mutex_unlock(&devfreq->lock);
449 mutex_unlock(&devfreq->lock);
451 mutex_lock(&devfreq_list_lock);
452 list_add(&devfreq->node, &devfreq_list);
453 mutex_unlock(&devfreq_list_lock);
455 err = devfreq->governor->event_handler(devfreq,
456 DEVFREQ_GOV_START, NULL);
458 dev_err(dev, "%s: Unable to start governor for the device\n",
466 list_del(&devfreq->node);
467 device_unregister(&devfreq->dev);
473 EXPORT_SYMBOL(devfreq_add_device);
476 * devfreq_remove_device() - Remove devfreq feature from a device.
477 * @devfreq: the devfreq instance to be removed
479 int devfreq_remove_device(struct devfreq *devfreq)
484 _remove_devfreq(devfreq, false);
488 EXPORT_SYMBOL(devfreq_remove_device);
491 * devfreq_suspend_device() - Suspend devfreq of a device.
492 * @devfreq: the devfreq instance to be suspended
494 int devfreq_suspend_device(struct devfreq *devfreq)
499 return devfreq->governor->event_handler(devfreq,
500 DEVFREQ_GOV_SUSPEND, NULL);
502 EXPORT_SYMBOL(devfreq_suspend_device);
505 * devfreq_resume_device() - Resume devfreq of a device.
506 * @devfreq: the devfreq instance to be resumed
508 int devfreq_resume_device(struct devfreq *devfreq)
513 return devfreq->governor->event_handler(devfreq,
514 DEVFREQ_GOV_RESUME, NULL);
516 EXPORT_SYMBOL(devfreq_resume_device);
518 static ssize_t show_governor(struct device *dev,
519 struct device_attribute *attr, char *buf)
521 return sprintf(buf, "%s\n", to_devfreq(dev)->governor->name);
524 static ssize_t show_freq(struct device *dev,
525 struct device_attribute *attr, char *buf)
528 struct devfreq *devfreq = to_devfreq(dev);
530 if (devfreq->profile->get_cur_freq &&
531 !devfreq->profile->get_cur_freq(devfreq->dev.parent, &freq))
532 return sprintf(buf, "%lu\n", freq);
534 return sprintf(buf, "%lu\n", devfreq->previous_freq);
537 static ssize_t show_target_freq(struct device *dev,
538 struct device_attribute *attr, char *buf)
540 return sprintf(buf, "%lu\n", to_devfreq(dev)->previous_freq);
543 static ssize_t show_polling_interval(struct device *dev,
544 struct device_attribute *attr, char *buf)
546 return sprintf(buf, "%d\n", to_devfreq(dev)->profile->polling_ms);
549 static ssize_t store_polling_interval(struct device *dev,
550 struct device_attribute *attr,
551 const char *buf, size_t count)
553 struct devfreq *df = to_devfreq(dev);
557 ret = sscanf(buf, "%u", &value);
561 df->governor->event_handler(df, DEVFREQ_GOV_INTERVAL, &value);
567 static ssize_t store_min_freq(struct device *dev, struct device_attribute *attr,
568 const char *buf, size_t count)
570 struct devfreq *df = to_devfreq(dev);
575 ret = sscanf(buf, "%lu", &value);
579 mutex_lock(&df->lock);
581 if (value && max && value > max) {
586 df->min_freq = value;
590 mutex_unlock(&df->lock);
594 static ssize_t show_min_freq(struct device *dev, struct device_attribute *attr,
597 return sprintf(buf, "%lu\n", to_devfreq(dev)->min_freq);
600 static ssize_t store_max_freq(struct device *dev, struct device_attribute *attr,
601 const char *buf, size_t count)
603 struct devfreq *df = to_devfreq(dev);
608 ret = sscanf(buf, "%lu", &value);
612 mutex_lock(&df->lock);
614 if (value && min && value < min) {
619 df->max_freq = value;
623 mutex_unlock(&df->lock);
627 static ssize_t show_max_freq(struct device *dev, struct device_attribute *attr,
630 return sprintf(buf, "%lu\n", to_devfreq(dev)->max_freq);
633 static ssize_t show_available_freqs(struct device *d,
634 struct device_attribute *attr,
637 struct devfreq *df = to_devfreq(d);
638 struct device *dev = df->dev.parent;
641 unsigned long freq = 0;
645 opp = opp_find_freq_ceil(dev, &freq);
649 count += scnprintf(&buf[count], (PAGE_SIZE - count - 2),
655 /* Truncate the trailing space */
659 count += sprintf(&buf[count], "\n");
664 static ssize_t show_trans_table(struct device *dev, struct device_attribute *attr,
667 struct devfreq *devfreq = to_devfreq(dev);
670 unsigned int max_state = devfreq->profile->max_state;
672 err = devfreq_update_status(devfreq, devfreq->previous_freq);
676 len = sprintf(buf, " From : To\n");
677 len += sprintf(buf + len, " :");
678 for (i = 0; i < max_state; i++)
679 len += sprintf(buf + len, "%8u",
680 devfreq->profile->freq_table[i]);
682 len += sprintf(buf + len, " time(ms)\n");
684 for (i = 0; i < max_state; i++) {
685 if (devfreq->profile->freq_table[i]
686 == devfreq->previous_freq) {
687 len += sprintf(buf + len, "*");
689 len += sprintf(buf + len, " ");
691 len += sprintf(buf + len, "%8u:",
692 devfreq->profile->freq_table[i]);
693 for (j = 0; j < max_state; j++)
694 len += sprintf(buf + len, "%8u",
695 devfreq->trans_table[(i * max_state) + j]);
696 len += sprintf(buf + len, "%10u\n",
697 jiffies_to_msecs(devfreq->time_in_state[i]));
700 len += sprintf(buf + len, "Total transition : %u\n",
701 devfreq->total_trans);
705 static struct device_attribute devfreq_attrs[] = {
706 __ATTR(governor, S_IRUGO, show_governor, NULL),
707 __ATTR(cur_freq, S_IRUGO, show_freq, NULL),
708 __ATTR(available_frequencies, S_IRUGO, show_available_freqs, NULL),
709 __ATTR(target_freq, S_IRUGO, show_target_freq, NULL),
710 __ATTR(polling_interval, S_IRUGO | S_IWUSR, show_polling_interval,
711 store_polling_interval),
712 __ATTR(min_freq, S_IRUGO | S_IWUSR, show_min_freq, store_min_freq),
713 __ATTR(max_freq, S_IRUGO | S_IWUSR, show_max_freq, store_max_freq),
714 __ATTR(trans_stat, S_IRUGO, show_trans_table, NULL),
718 static int __init devfreq_init(void)
720 devfreq_class = class_create(THIS_MODULE, "devfreq");
721 if (IS_ERR(devfreq_class)) {
722 pr_err("%s: couldn't create class\n", __FILE__);
723 return PTR_ERR(devfreq_class);
726 devfreq_wq = create_freezable_workqueue("devfreq_wq");
727 if (IS_ERR(devfreq_wq)) {
728 class_destroy(devfreq_class);
729 pr_err("%s: couldn't create workqueue\n", __FILE__);
730 return PTR_ERR(devfreq_wq);
732 devfreq_class->dev_attrs = devfreq_attrs;
736 subsys_initcall(devfreq_init);
738 static void __exit devfreq_exit(void)
740 class_destroy(devfreq_class);
741 destroy_workqueue(devfreq_wq);
743 module_exit(devfreq_exit);
746 * The followings are helper functions for devfreq user device drivers with
751 * devfreq_recommended_opp() - Helper function to get proper OPP for the
752 * freq value given to target callback.
753 * @dev: The devfreq user device. (parent of devfreq)
754 * @freq: The frequency given to target function
755 * @flags: Flags handed from devfreq framework.
758 struct opp *devfreq_recommended_opp(struct device *dev, unsigned long *freq,
763 if (flags & DEVFREQ_FLAG_LEAST_UPPER_BOUND) {
764 /* The freq is an upper bound. opp should be lower */
765 opp = opp_find_freq_floor(dev, freq);
767 /* If not available, use the closest opp */
768 if (opp == ERR_PTR(-ENODEV))
769 opp = opp_find_freq_ceil(dev, freq);
771 /* The freq is an lower bound. opp should be higher */
772 opp = opp_find_freq_ceil(dev, freq);
774 /* If not available, use the closest opp */
775 if (opp == ERR_PTR(-ENODEV))
776 opp = opp_find_freq_floor(dev, freq);
783 * devfreq_register_opp_notifier() - Helper function to get devfreq notified
784 * for any changes in the OPP availability
786 * @dev: The devfreq user device. (parent of devfreq)
787 * @devfreq: The devfreq object.
789 int devfreq_register_opp_notifier(struct device *dev, struct devfreq *devfreq)
791 struct srcu_notifier_head *nh = opp_get_notifier(dev);
795 return srcu_notifier_chain_register(nh, &devfreq->nb);
799 * devfreq_unregister_opp_notifier() - Helper function to stop getting devfreq
800 * notified for any changes in the OPP
801 * availability changes anymore.
802 * @dev: The devfreq user device. (parent of devfreq)
803 * @devfreq: The devfreq object.
805 * At exit() callback of devfreq_dev_profile, this must be included if
806 * devfreq_recommended_opp is used.
808 int devfreq_unregister_opp_notifier(struct device *dev, struct devfreq *devfreq)
810 struct srcu_notifier_head *nh = opp_get_notifier(dev);
814 return srcu_notifier_chain_unregister(nh, &devfreq->nb);
817 MODULE_AUTHOR("MyungJoo Ham <myungjoo.ham@samsung.com>");
818 MODULE_DESCRIPTION("devfreq class support");
819 MODULE_LICENSE("GPL");