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;
170 * devfreq_monitor() - Periodically poll devfreq objects.
171 * @work: the work struct used to run devfreq_monitor periodically.
174 static void devfreq_monitor(struct work_struct *work)
177 struct devfreq *devfreq = container_of(work,
178 struct devfreq, work.work);
180 mutex_lock(&devfreq->lock);
181 err = update_devfreq(devfreq);
183 dev_err(&devfreq->dev, "dvfs failed with (%d) error\n", err);
185 queue_delayed_work(devfreq_wq, &devfreq->work,
186 msecs_to_jiffies(devfreq->profile->polling_ms));
187 mutex_unlock(&devfreq->lock);
191 * devfreq_monitor_start() - Start load monitoring of devfreq instance
192 * @devfreq: the devfreq instance.
194 * Helper function for starting devfreq device load monitoing. By
195 * default delayed work based monitoring is supported. Function
196 * to be called from governor in response to DEVFREQ_GOV_START
197 * event when device is added to devfreq framework.
199 void devfreq_monitor_start(struct devfreq *devfreq)
201 INIT_DEFERRABLE_WORK(&devfreq->work, devfreq_monitor);
202 if (devfreq->profile->polling_ms)
203 queue_delayed_work(devfreq_wq, &devfreq->work,
204 msecs_to_jiffies(devfreq->profile->polling_ms));
208 * devfreq_monitor_stop() - Stop load monitoring of a devfreq instance
209 * @devfreq: the devfreq instance.
211 * Helper function to stop devfreq device load monitoing. Function
212 * to be called from governor in response to DEVFREQ_GOV_STOP
213 * event when device is removed from devfreq framework.
215 void devfreq_monitor_stop(struct devfreq *devfreq)
217 cancel_delayed_work_sync(&devfreq->work);
221 * devfreq_monitor_suspend() - Suspend load monitoring of a devfreq instance
222 * @devfreq: the devfreq instance.
224 * Helper function to suspend devfreq device load monitoing. Function
225 * to be called from governor in response to DEVFREQ_GOV_SUSPEND
226 * event or when polling interval is set to zero.
228 * Note: Though this function is same as devfreq_monitor_stop(),
229 * intentionally kept separate to provide hooks for collecting
230 * transition statistics.
232 void devfreq_monitor_suspend(struct devfreq *devfreq)
234 mutex_lock(&devfreq->lock);
235 if (devfreq->stop_polling) {
236 mutex_unlock(&devfreq->lock);
240 devfreq->stop_polling = true;
241 mutex_unlock(&devfreq->lock);
242 cancel_delayed_work_sync(&devfreq->work);
246 * devfreq_monitor_resume() - Resume load monitoring of a devfreq instance
247 * @devfreq: the devfreq instance.
249 * Helper function to resume devfreq device load monitoing. Function
250 * to be called from governor in response to DEVFREQ_GOV_RESUME
251 * event or when polling interval is set to non-zero.
253 void devfreq_monitor_resume(struct devfreq *devfreq)
255 mutex_lock(&devfreq->lock);
256 if (!devfreq->stop_polling)
259 if (!delayed_work_pending(&devfreq->work) &&
260 devfreq->profile->polling_ms)
261 queue_delayed_work(devfreq_wq, &devfreq->work,
262 msecs_to_jiffies(devfreq->profile->polling_ms));
263 devfreq->stop_polling = false;
266 mutex_unlock(&devfreq->lock);
270 * devfreq_interval_update() - Update device devfreq monitoring interval
271 * @devfreq: the devfreq instance.
272 * @delay: new polling interval to be set.
274 * Helper function to set new load monitoring polling interval. Function
275 * to be called from governor in response to DEVFREQ_GOV_INTERVAL event.
277 void devfreq_interval_update(struct devfreq *devfreq, unsigned int *delay)
279 unsigned int cur_delay = devfreq->profile->polling_ms;
280 unsigned int new_delay = *delay;
282 mutex_lock(&devfreq->lock);
283 devfreq->profile->polling_ms = new_delay;
285 if (devfreq->stop_polling)
288 /* if new delay is zero, stop polling */
290 mutex_unlock(&devfreq->lock);
291 cancel_delayed_work_sync(&devfreq->work);
295 /* if current delay is zero, start polling with new delay */
297 queue_delayed_work(devfreq_wq, &devfreq->work,
298 msecs_to_jiffies(devfreq->profile->polling_ms));
302 /* if current delay is greater than new delay, restart polling */
303 if (cur_delay > new_delay) {
304 mutex_unlock(&devfreq->lock);
305 cancel_delayed_work_sync(&devfreq->work);
306 mutex_lock(&devfreq->lock);
307 if (!devfreq->stop_polling)
308 queue_delayed_work(devfreq_wq, &devfreq->work,
309 msecs_to_jiffies(devfreq->profile->polling_ms));
312 mutex_unlock(&devfreq->lock);
316 * devfreq_notifier_call() - Notify that the device frequency requirements
317 * has been changed out of devfreq framework.
318 * @nb: the notifier_block (supposed to be devfreq->nb)
322 * Called by a notifier that uses devfreq->nb.
324 static int devfreq_notifier_call(struct notifier_block *nb, unsigned long type,
327 struct devfreq *devfreq = container_of(nb, struct devfreq, nb);
330 mutex_lock(&devfreq->lock);
331 ret = update_devfreq(devfreq);
332 mutex_unlock(&devfreq->lock);
338 * _remove_devfreq() - Remove devfreq from the list and release its resources.
339 * @devfreq: the devfreq struct
340 * @skip: skip calling device_unregister().
342 static void _remove_devfreq(struct devfreq *devfreq, bool skip)
344 mutex_lock(&devfreq_list_lock);
345 if (IS_ERR(find_device_devfreq(devfreq->dev.parent))) {
346 mutex_unlock(&devfreq_list_lock);
347 dev_warn(&devfreq->dev, "releasing devfreq which doesn't exist\n");
350 list_del(&devfreq->node);
351 mutex_unlock(&devfreq_list_lock);
353 devfreq->governor->event_handler(devfreq, DEVFREQ_GOV_STOP, NULL);
355 if (devfreq->profile->exit)
356 devfreq->profile->exit(devfreq->dev.parent);
358 if (!skip && get_device(&devfreq->dev)) {
359 device_unregister(&devfreq->dev);
360 put_device(&devfreq->dev);
363 mutex_destroy(&devfreq->lock);
368 * devfreq_dev_release() - Callback for struct device to release the device.
369 * @dev: the devfreq device
371 * This calls _remove_devfreq() if _remove_devfreq() is not called.
372 * Note that devfreq_dev_release() could be called by _remove_devfreq() as
373 * well as by others unregistering the device.
375 static void devfreq_dev_release(struct device *dev)
377 struct devfreq *devfreq = to_devfreq(dev);
379 _remove_devfreq(devfreq, true);
383 * devfreq_add_device() - Add devfreq feature to the device
384 * @dev: the device to add devfreq feature.
385 * @profile: device-specific profile to run devfreq.
386 * @governor: the policy to choose frequency.
387 * @data: private data for the governor. The devfreq framework does not
390 struct devfreq *devfreq_add_device(struct device *dev,
391 struct devfreq_dev_profile *profile,
392 const struct devfreq_governor *governor,
395 struct devfreq *devfreq;
398 if (!dev || !profile || !governor) {
399 dev_err(dev, "%s: Invalid parameters.\n", __func__);
400 return ERR_PTR(-EINVAL);
403 mutex_lock(&devfreq_list_lock);
404 devfreq = find_device_devfreq(dev);
405 mutex_unlock(&devfreq_list_lock);
406 if (!IS_ERR(devfreq)) {
407 dev_err(dev, "%s: Unable to create devfreq for the device. It already has one.\n", __func__);
412 devfreq = kzalloc(sizeof(struct devfreq), GFP_KERNEL);
414 dev_err(dev, "%s: Unable to create devfreq for the device\n",
420 mutex_init(&devfreq->lock);
421 mutex_lock(&devfreq->lock);
422 devfreq->dev.parent = dev;
423 devfreq->dev.class = devfreq_class;
424 devfreq->dev.release = devfreq_dev_release;
425 devfreq->profile = profile;
426 devfreq->governor = governor;
427 devfreq->previous_freq = profile->initial_freq;
428 devfreq->data = data;
429 devfreq->nb.notifier_call = devfreq_notifier_call;
431 devfreq->trans_table = devm_kzalloc(dev, sizeof(unsigned int) *
432 devfreq->profile->max_state *
433 devfreq->profile->max_state,
435 devfreq->time_in_state = devm_kzalloc(dev, sizeof(unsigned int) *
436 devfreq->profile->max_state,
438 devfreq->last_stat_updated = jiffies;
440 dev_set_name(&devfreq->dev, dev_name(dev));
441 err = device_register(&devfreq->dev);
443 put_device(&devfreq->dev);
444 mutex_unlock(&devfreq->lock);
448 mutex_unlock(&devfreq->lock);
450 mutex_lock(&devfreq_list_lock);
451 list_add(&devfreq->node, &devfreq_list);
452 mutex_unlock(&devfreq_list_lock);
454 err = devfreq->governor->event_handler(devfreq,
455 DEVFREQ_GOV_START, NULL);
457 dev_err(dev, "%s: Unable to start governor for the device\n",
465 list_del(&devfreq->node);
466 device_unregister(&devfreq->dev);
472 EXPORT_SYMBOL(devfreq_add_device);
475 * devfreq_remove_device() - Remove devfreq feature from a device.
476 * @devfreq: the devfreq instance to be removed
478 int devfreq_remove_device(struct devfreq *devfreq)
483 _remove_devfreq(devfreq, false);
487 EXPORT_SYMBOL(devfreq_remove_device);
490 * devfreq_suspend_device() - Suspend devfreq of a device.
491 * @devfreq: the devfreq instance to be suspended
493 int devfreq_suspend_device(struct devfreq *devfreq)
498 return devfreq->governor->event_handler(devfreq,
499 DEVFREQ_GOV_SUSPEND, NULL);
501 EXPORT_SYMBOL(devfreq_suspend_device);
504 * devfreq_resume_device() - Resume devfreq of a device.
505 * @devfreq: the devfreq instance to be resumed
507 int devfreq_resume_device(struct devfreq *devfreq)
512 return devfreq->governor->event_handler(devfreq,
513 DEVFREQ_GOV_RESUME, NULL);
515 EXPORT_SYMBOL(devfreq_resume_device);
517 static ssize_t show_governor(struct device *dev,
518 struct device_attribute *attr, char *buf)
520 return sprintf(buf, "%s\n", to_devfreq(dev)->governor->name);
523 static ssize_t show_freq(struct device *dev,
524 struct device_attribute *attr, char *buf)
527 struct devfreq *devfreq = to_devfreq(dev);
529 if (devfreq->profile->get_cur_freq &&
530 !devfreq->profile->get_cur_freq(devfreq->dev.parent, &freq))
531 return sprintf(buf, "%lu\n", freq);
533 return sprintf(buf, "%lu\n", devfreq->previous_freq);
536 static ssize_t show_target_freq(struct device *dev,
537 struct device_attribute *attr, char *buf)
539 return sprintf(buf, "%lu\n", to_devfreq(dev)->previous_freq);
542 static ssize_t show_polling_interval(struct device *dev,
543 struct device_attribute *attr, char *buf)
545 return sprintf(buf, "%d\n", to_devfreq(dev)->profile->polling_ms);
548 static ssize_t store_polling_interval(struct device *dev,
549 struct device_attribute *attr,
550 const char *buf, size_t count)
552 struct devfreq *df = to_devfreq(dev);
556 ret = sscanf(buf, "%u", &value);
560 df->governor->event_handler(df, DEVFREQ_GOV_INTERVAL, &value);
566 static ssize_t store_min_freq(struct device *dev, struct device_attribute *attr,
567 const char *buf, size_t count)
569 struct devfreq *df = to_devfreq(dev);
574 ret = sscanf(buf, "%lu", &value);
578 mutex_lock(&df->lock);
580 if (value && max && value > max) {
585 df->min_freq = value;
589 mutex_unlock(&df->lock);
593 static ssize_t show_min_freq(struct device *dev, struct device_attribute *attr,
596 return sprintf(buf, "%lu\n", to_devfreq(dev)->min_freq);
599 static ssize_t store_max_freq(struct device *dev, struct device_attribute *attr,
600 const char *buf, size_t count)
602 struct devfreq *df = to_devfreq(dev);
607 ret = sscanf(buf, "%lu", &value);
611 mutex_lock(&df->lock);
613 if (value && min && value < min) {
618 df->max_freq = value;
622 mutex_unlock(&df->lock);
626 static ssize_t show_max_freq(struct device *dev, struct device_attribute *attr,
629 return sprintf(buf, "%lu\n", to_devfreq(dev)->max_freq);
632 static ssize_t show_available_freqs(struct device *d,
633 struct device_attribute *attr,
636 struct devfreq *df = to_devfreq(d);
637 struct device *dev = df->dev.parent;
640 unsigned long freq = 0;
644 opp = opp_find_freq_ceil(dev, &freq);
648 count += scnprintf(&buf[count], (PAGE_SIZE - count - 2),
654 /* Truncate the trailing space */
658 count += sprintf(&buf[count], "\n");
663 static ssize_t show_trans_table(struct device *dev, struct device_attribute *attr,
666 struct devfreq *devfreq = to_devfreq(dev);
669 unsigned int max_state = devfreq->profile->max_state;
671 err = devfreq_update_status(devfreq, devfreq->previous_freq);
675 len = sprintf(buf, " From : To\n");
676 len += sprintf(buf + len, " :");
677 for (i = 0; i < max_state; i++)
678 len += sprintf(buf + len, "%8u",
679 devfreq->profile->freq_table[i]);
681 len += sprintf(buf + len, " time(ms)\n");
683 for (i = 0; i < max_state; i++) {
684 if (devfreq->profile->freq_table[i]
685 == devfreq->previous_freq) {
686 len += sprintf(buf + len, "*");
688 len += sprintf(buf + len, " ");
690 len += sprintf(buf + len, "%8u:",
691 devfreq->profile->freq_table[i]);
692 for (j = 0; j < max_state; j++)
693 len += sprintf(buf + len, "%8u",
694 devfreq->trans_table[(i * max_state) + j]);
695 len += sprintf(buf + len, "%10u\n",
696 jiffies_to_msecs(devfreq->time_in_state[i]));
699 len += sprintf(buf + len, "Total transition : %u\n",
700 devfreq->total_trans);
704 static struct device_attribute devfreq_attrs[] = {
705 __ATTR(governor, S_IRUGO, show_governor, NULL),
706 __ATTR(cur_freq, S_IRUGO, show_freq, NULL),
707 __ATTR(available_frequencies, S_IRUGO, show_available_freqs, NULL),
708 __ATTR(target_freq, S_IRUGO, show_target_freq, NULL),
709 __ATTR(polling_interval, S_IRUGO | S_IWUSR, show_polling_interval,
710 store_polling_interval),
711 __ATTR(min_freq, S_IRUGO | S_IWUSR, show_min_freq, store_min_freq),
712 __ATTR(max_freq, S_IRUGO | S_IWUSR, show_max_freq, store_max_freq),
713 __ATTR(trans_stat, S_IRUGO, show_trans_table, NULL),
717 static int __init devfreq_init(void)
719 devfreq_class = class_create(THIS_MODULE, "devfreq");
720 if (IS_ERR(devfreq_class)) {
721 pr_err("%s: couldn't create class\n", __FILE__);
722 return PTR_ERR(devfreq_class);
725 devfreq_wq = create_freezable_workqueue("devfreq_wq");
726 if (IS_ERR(devfreq_wq)) {
727 class_destroy(devfreq_class);
728 pr_err("%s: couldn't create workqueue\n", __FILE__);
729 return PTR_ERR(devfreq_wq);
731 devfreq_class->dev_attrs = devfreq_attrs;
735 subsys_initcall(devfreq_init);
737 static void __exit devfreq_exit(void)
739 class_destroy(devfreq_class);
740 destroy_workqueue(devfreq_wq);
742 module_exit(devfreq_exit);
745 * The followings are helper functions for devfreq user device drivers with
750 * devfreq_recommended_opp() - Helper function to get proper OPP for the
751 * freq value given to target callback.
752 * @dev: The devfreq user device. (parent of devfreq)
753 * @freq: The frequency given to target function
754 * @flags: Flags handed from devfreq framework.
757 struct opp *devfreq_recommended_opp(struct device *dev, unsigned long *freq,
762 if (flags & DEVFREQ_FLAG_LEAST_UPPER_BOUND) {
763 /* The freq is an upper bound. opp should be lower */
764 opp = opp_find_freq_floor(dev, freq);
766 /* If not available, use the closest opp */
767 if (opp == ERR_PTR(-ENODEV))
768 opp = opp_find_freq_ceil(dev, freq);
770 /* The freq is an lower bound. opp should be higher */
771 opp = opp_find_freq_ceil(dev, freq);
773 /* If not available, use the closest opp */
774 if (opp == ERR_PTR(-ENODEV))
775 opp = opp_find_freq_floor(dev, freq);
782 * devfreq_register_opp_notifier() - Helper function to get devfreq notified
783 * for any changes in the OPP availability
785 * @dev: The devfreq user device. (parent of devfreq)
786 * @devfreq: The devfreq object.
788 int devfreq_register_opp_notifier(struct device *dev, struct devfreq *devfreq)
790 struct srcu_notifier_head *nh = opp_get_notifier(dev);
794 return srcu_notifier_chain_register(nh, &devfreq->nb);
798 * devfreq_unregister_opp_notifier() - Helper function to stop getting devfreq
799 * notified for any changes in the OPP
800 * availability changes anymore.
801 * @dev: The devfreq user device. (parent of devfreq)
802 * @devfreq: The devfreq object.
804 * At exit() callback of devfreq_dev_profile, this must be included if
805 * devfreq_recommended_opp is used.
807 int devfreq_unregister_opp_notifier(struct device *dev, struct devfreq *devfreq)
809 struct srcu_notifier_head *nh = opp_get_notifier(dev);
813 return srcu_notifier_chain_unregister(nh, &devfreq->nb);
816 MODULE_AUTHOR("MyungJoo Ham <myungjoo.ham@samsung.com>");
817 MODULE_DESCRIPTION("devfreq class support");
818 MODULE_LICENSE("GPL");