2 * Generic OPP Interface
4 * Copyright (C) 2009-2010 Texas Instruments Incorporated.
9 * This program is free software; you can redistribute it and/or modify
10 * it under the terms of the GNU General Public License version 2 as
11 * published by the Free Software Foundation.
14 #include <linux/kernel.h>
15 #include <linux/errno.h>
16 #include <linux/err.h>
17 #include <linux/slab.h>
18 #include <linux/device.h>
19 #include <linux/list.h>
20 #include <linux/rculist.h>
21 #include <linux/rcupdate.h>
22 #include <linux/pm_opp.h>
24 #include <linux/export.h>
27 * Internal data structure organization with the OPP layer library is as
30 * |- device 1 (represents voltage domain 1)
31 * | |- opp 1 (availability, freq, voltage)
35 * |- device 2 (represents the next voltage domain)
37 * `- device m (represents mth voltage domain)
38 * device 1, 2.. are represented by dev_opp structure while each opp
39 * is represented by the opp structure.
43 * struct dev_pm_opp - Generic OPP description structure
44 * @node: opp list node. The nodes are maintained throughout the lifetime
45 * of boot. It is expected only an optimal set of OPPs are
46 * added to the library by the SoC framework.
47 * RCU usage: opp list is traversed with RCU locks. node
48 * modification is possible realtime, hence the modifications
49 * are protected by the dev_opp_list_lock for integrity.
50 * IMPORTANT: the opp nodes should be maintained in increasing
52 * @dynamic: not-created from static DT entries.
53 * @available: true/false - marks if this OPP as available or not
54 * @rate: Frequency in hertz
55 * @u_volt: Nominal voltage in microvolts corresponding to this OPP
56 * @dev_opp: points back to the device_opp struct this opp belongs to
57 * @rcu_head: RCU callback head used for deferred freeing
59 * This structure stores the OPP information for a given device.
62 struct list_head node;
69 struct device_opp *dev_opp;
70 struct rcu_head rcu_head;
74 * struct device_opp - Device opp structure
75 * @node: list node - contains the devices with OPPs that
76 * have been registered. Nodes once added are not modified in this
78 * RCU usage: nodes are not modified in the list of device_opp,
79 * however addition is possible and is secured by dev_opp_list_lock
80 * @dev: device pointer
81 * @srcu_head: notifier head to notify the OPP availability changes.
82 * @rcu_head: RCU callback head used for deferred freeing
83 * @opp_list: list of opps
85 * This is an internal data structure maintaining the link to opps attached to
86 * a device. This structure is not meant to be shared to users as it is
87 * meant for book keeping and private to OPP library.
89 * Because the opp structures can be used from both rcu and srcu readers, we
90 * need to wait for the grace period of both of them before freeing any
91 * resources. And so we have used kfree_rcu() from within call_srcu() handlers.
94 struct list_head node;
97 struct srcu_notifier_head srcu_head;
98 struct rcu_head rcu_head;
99 struct list_head opp_list;
103 * The root of the list of all devices. All device_opp structures branch off
104 * from here, with each device_opp containing the list of opp it supports in
105 * various states of availability.
107 static LIST_HEAD(dev_opp_list);
108 /* Lock to allow exclusive modification to the device and opp lists */
109 static DEFINE_MUTEX(dev_opp_list_lock);
111 #define opp_rcu_lockdep_assert() \
113 rcu_lockdep_assert(rcu_read_lock_held() || \
114 lockdep_is_held(&dev_opp_list_lock), \
115 "Missing rcu_read_lock() or " \
116 "dev_opp_list_lock protection"); \
120 * find_device_opp() - find device_opp struct using device pointer
121 * @dev: device pointer used to lookup device OPPs
123 * Search list of device OPPs for one containing matching device. Does a RCU
124 * reader operation to grab the pointer needed.
126 * Returns pointer to 'struct device_opp' if found, otherwise -ENODEV or
127 * -EINVAL based on type of error.
129 * Locking: This function must be called under rcu_read_lock(). device_opp
130 * is a RCU protected pointer. This means that device_opp is valid as long
131 * as we are under RCU lock.
133 static struct device_opp *find_device_opp(struct device *dev)
135 struct device_opp *tmp_dev_opp, *dev_opp = ERR_PTR(-ENODEV);
137 if (unlikely(IS_ERR_OR_NULL(dev))) {
138 pr_err("%s: Invalid parameters\n", __func__);
139 return ERR_PTR(-EINVAL);
142 list_for_each_entry_rcu(tmp_dev_opp, &dev_opp_list, node) {
143 if (tmp_dev_opp->dev == dev) {
144 dev_opp = tmp_dev_opp;
153 * dev_pm_opp_get_voltage() - Gets the voltage corresponding to an available opp
154 * @opp: opp for which voltage has to be returned for
156 * Return voltage in micro volt corresponding to the opp, else
159 * Locking: This function must be called under rcu_read_lock(). opp is a rcu
160 * protected pointer. This means that opp which could have been fetched by
161 * opp_find_freq_{exact,ceil,floor} functions is valid as long as we are
162 * under RCU lock. The pointer returned by the opp_find_freq family must be
163 * used in the same section as the usage of this function with the pointer
164 * prior to unlocking with rcu_read_unlock() to maintain the integrity of the
167 unsigned long dev_pm_opp_get_voltage(struct dev_pm_opp *opp)
169 struct dev_pm_opp *tmp_opp;
172 tmp_opp = rcu_dereference(opp);
173 if (unlikely(IS_ERR_OR_NULL(tmp_opp)) || !tmp_opp->available)
174 pr_err("%s: Invalid parameters\n", __func__);
180 EXPORT_SYMBOL_GPL(dev_pm_opp_get_voltage);
183 * dev_pm_opp_get_freq() - Gets the frequency corresponding to an available opp
184 * @opp: opp for which frequency has to be returned for
186 * Return frequency in hertz corresponding to the opp, else
189 * Locking: This function must be called under rcu_read_lock(). opp is a rcu
190 * protected pointer. This means that opp which could have been fetched by
191 * opp_find_freq_{exact,ceil,floor} functions is valid as long as we are
192 * under RCU lock. The pointer returned by the opp_find_freq family must be
193 * used in the same section as the usage of this function with the pointer
194 * prior to unlocking with rcu_read_unlock() to maintain the integrity of the
197 unsigned long dev_pm_opp_get_freq(struct dev_pm_opp *opp)
199 struct dev_pm_opp *tmp_opp;
202 tmp_opp = rcu_dereference(opp);
203 if (unlikely(IS_ERR_OR_NULL(tmp_opp)) || !tmp_opp->available)
204 pr_err("%s: Invalid parameters\n", __func__);
210 EXPORT_SYMBOL_GPL(dev_pm_opp_get_freq);
213 * dev_pm_opp_get_opp_count() - Get number of opps available in the opp list
214 * @dev: device for which we do this operation
216 * This function returns the number of available opps if there are any,
217 * else returns 0 if none or the corresponding error value.
219 * Locking: This function takes rcu_read_lock().
221 int dev_pm_opp_get_opp_count(struct device *dev)
223 struct device_opp *dev_opp;
224 struct dev_pm_opp *temp_opp;
229 dev_opp = find_device_opp(dev);
230 if (IS_ERR(dev_opp)) {
231 count = PTR_ERR(dev_opp);
232 dev_err(dev, "%s: device OPP not found (%d)\n",
237 list_for_each_entry_rcu(temp_opp, &dev_opp->opp_list, node) {
238 if (temp_opp->available)
246 EXPORT_SYMBOL_GPL(dev_pm_opp_get_opp_count);
249 * dev_pm_opp_find_freq_exact() - search for an exact frequency
250 * @dev: device for which we do this operation
251 * @freq: frequency to search for
252 * @available: true/false - match for available opp
254 * Searches for exact match in the opp list and returns pointer to the matching
255 * opp if found, else returns ERR_PTR in case of error and should be handled
256 * using IS_ERR. Error return values can be:
257 * EINVAL: for bad pointer
258 * ERANGE: no match found for search
259 * ENODEV: if device not found in list of registered devices
261 * Note: available is a modifier for the search. if available=true, then the
262 * match is for exact matching frequency and is available in the stored OPP
263 * table. if false, the match is for exact frequency which is not available.
265 * This provides a mechanism to enable an opp which is not available currently
266 * or the opposite as well.
268 * Locking: This function must be called under rcu_read_lock(). opp is a rcu
269 * protected pointer. The reason for the same is that the opp pointer which is
270 * returned will remain valid for use with opp_get_{voltage, freq} only while
271 * under the locked area. The pointer returned must be used prior to unlocking
272 * with rcu_read_unlock() to maintain the integrity of the pointer.
274 struct dev_pm_opp *dev_pm_opp_find_freq_exact(struct device *dev,
278 struct device_opp *dev_opp;
279 struct dev_pm_opp *temp_opp, *opp = ERR_PTR(-ERANGE);
281 opp_rcu_lockdep_assert();
283 dev_opp = find_device_opp(dev);
284 if (IS_ERR(dev_opp)) {
285 int r = PTR_ERR(dev_opp);
286 dev_err(dev, "%s: device OPP not found (%d)\n", __func__, r);
290 list_for_each_entry_rcu(temp_opp, &dev_opp->opp_list, node) {
291 if (temp_opp->available == available &&
292 temp_opp->rate == freq) {
300 EXPORT_SYMBOL_GPL(dev_pm_opp_find_freq_exact);
303 * dev_pm_opp_find_freq_ceil() - Search for an rounded ceil freq
304 * @dev: device for which we do this operation
305 * @freq: Start frequency
307 * Search for the matching ceil *available* OPP from a starting freq
310 * Returns matching *opp and refreshes *freq accordingly, else returns
311 * ERR_PTR in case of error and should be handled using IS_ERR. Error return
313 * EINVAL: for bad pointer
314 * ERANGE: no match found for search
315 * ENODEV: if device not found in list of registered devices
317 * Locking: This function must be called under rcu_read_lock(). opp is a rcu
318 * protected pointer. The reason for the same is that the opp pointer which is
319 * returned will remain valid for use with opp_get_{voltage, freq} only while
320 * under the locked area. The pointer returned must be used prior to unlocking
321 * with rcu_read_unlock() to maintain the integrity of the pointer.
323 struct dev_pm_opp *dev_pm_opp_find_freq_ceil(struct device *dev,
326 struct device_opp *dev_opp;
327 struct dev_pm_opp *temp_opp, *opp = ERR_PTR(-ERANGE);
329 opp_rcu_lockdep_assert();
332 dev_err(dev, "%s: Invalid argument freq=%p\n", __func__, freq);
333 return ERR_PTR(-EINVAL);
336 dev_opp = find_device_opp(dev);
338 return ERR_CAST(dev_opp);
340 list_for_each_entry_rcu(temp_opp, &dev_opp->opp_list, node) {
341 if (temp_opp->available && temp_opp->rate >= *freq) {
350 EXPORT_SYMBOL_GPL(dev_pm_opp_find_freq_ceil);
353 * dev_pm_opp_find_freq_floor() - Search for a rounded floor freq
354 * @dev: device for which we do this operation
355 * @freq: Start frequency
357 * Search for the matching floor *available* OPP from a starting freq
360 * Returns matching *opp and refreshes *freq accordingly, else returns
361 * ERR_PTR in case of error and should be handled using IS_ERR. Error return
363 * EINVAL: for bad pointer
364 * ERANGE: no match found for search
365 * ENODEV: if device not found in list of registered devices
367 * Locking: This function must be called under rcu_read_lock(). opp is a rcu
368 * protected pointer. The reason for the same is that the opp pointer which is
369 * returned will remain valid for use with opp_get_{voltage, freq} only while
370 * under the locked area. The pointer returned must be used prior to unlocking
371 * with rcu_read_unlock() to maintain the integrity of the pointer.
373 struct dev_pm_opp *dev_pm_opp_find_freq_floor(struct device *dev,
376 struct device_opp *dev_opp;
377 struct dev_pm_opp *temp_opp, *opp = ERR_PTR(-ERANGE);
379 opp_rcu_lockdep_assert();
382 dev_err(dev, "%s: Invalid argument freq=%p\n", __func__, freq);
383 return ERR_PTR(-EINVAL);
386 dev_opp = find_device_opp(dev);
388 return ERR_CAST(dev_opp);
390 list_for_each_entry_rcu(temp_opp, &dev_opp->opp_list, node) {
391 if (temp_opp->available) {
392 /* go to the next node, before choosing prev */
393 if (temp_opp->rate > *freq)
404 EXPORT_SYMBOL_GPL(dev_pm_opp_find_freq_floor);
406 static struct device_opp *add_device_opp(struct device *dev)
408 struct device_opp *dev_opp;
411 * Allocate a new device OPP table. In the infrequent case where a new
412 * device is needed to be added, we pay this penalty.
414 dev_opp = kzalloc(sizeof(*dev_opp), GFP_KERNEL);
419 srcu_init_notifier_head(&dev_opp->srcu_head);
420 INIT_LIST_HEAD(&dev_opp->opp_list);
422 /* Secure the device list modification */
423 list_add_rcu(&dev_opp->node, &dev_opp_list);
427 static int dev_pm_opp_add_dynamic(struct device *dev, unsigned long freq,
428 unsigned long u_volt, bool dynamic)
430 struct device_opp *dev_opp = NULL;
431 struct dev_pm_opp *opp, *new_opp;
432 struct list_head *head;
435 /* allocate new OPP node */
436 new_opp = kzalloc(sizeof(*new_opp), GFP_KERNEL);
438 dev_warn(dev, "%s: Unable to create new OPP node\n", __func__);
442 /* Hold our list modification lock here */
443 mutex_lock(&dev_opp_list_lock);
445 /* populate the opp table */
446 new_opp->rate = freq;
447 new_opp->u_volt = u_volt;
448 new_opp->available = true;
449 new_opp->dynamic = dynamic;
451 /* Check for existing list for 'dev' */
452 dev_opp = find_device_opp(dev);
453 if (IS_ERR(dev_opp)) {
454 dev_opp = add_device_opp(dev);
460 head = &dev_opp->opp_list;
465 * Insert new OPP in order of increasing frequency
466 * and discard if already present
468 head = &dev_opp->opp_list;
469 list_for_each_entry_rcu(opp, &dev_opp->opp_list, node) {
470 if (new_opp->rate <= opp->rate)
476 /* Duplicate OPPs ? */
477 if (new_opp->rate == opp->rate) {
478 ret = opp->available && new_opp->u_volt == opp->u_volt ?
481 dev_warn(dev, "%s: duplicate OPPs detected. Existing: freq: %lu, volt: %lu, enabled: %d. New: freq: %lu, volt: %lu, enabled: %d\n",
482 __func__, opp->rate, opp->u_volt, opp->available,
483 new_opp->rate, new_opp->u_volt, new_opp->available);
488 new_opp->dev_opp = dev_opp;
489 list_add_rcu(&new_opp->node, head);
490 mutex_unlock(&dev_opp_list_lock);
493 * Notify the changes in the availability of the operable
494 * frequency/voltage list.
496 srcu_notifier_call_chain(&dev_opp->srcu_head, OPP_EVENT_ADD, new_opp);
500 mutex_unlock(&dev_opp_list_lock);
506 * dev_pm_opp_add() - Add an OPP table from a table definitions
507 * @dev: device for which we do this operation
508 * @freq: Frequency in Hz for this OPP
509 * @u_volt: Voltage in uVolts for this OPP
511 * This function adds an opp definition to the opp list and returns status.
512 * The opp is made available by default and it can be controlled using
513 * dev_pm_opp_enable/disable functions.
515 * Locking: The internal device_opp and opp structures are RCU protected.
516 * Hence this function internally uses RCU updater strategy with mutex locks
517 * to keep the integrity of the internal data structures. Callers should ensure
518 * that this function is *NOT* called under RCU protection or in contexts where
519 * mutex cannot be locked.
523 * Duplicate OPPs (both freq and volt are same) and opp->available
524 * -EEXIST: Freq are same and volt are different OR
525 * Duplicate OPPs (both freq and volt are same) and !opp->available
526 * -ENOMEM: Memory allocation failure
528 int dev_pm_opp_add(struct device *dev, unsigned long freq, unsigned long u_volt)
530 return dev_pm_opp_add_dynamic(dev, freq, u_volt, true);
532 EXPORT_SYMBOL_GPL(dev_pm_opp_add);
534 static void kfree_opp_rcu(struct rcu_head *head)
536 struct dev_pm_opp *opp = container_of(head, struct dev_pm_opp, rcu_head);
538 kfree_rcu(opp, rcu_head);
541 static void kfree_device_rcu(struct rcu_head *head)
543 struct device_opp *device_opp = container_of(head, struct device_opp, rcu_head);
545 kfree_rcu(device_opp, rcu_head);
548 static void __dev_pm_opp_remove(struct device_opp *dev_opp,
549 struct dev_pm_opp *opp)
552 * Notify the changes in the availability of the operable
553 * frequency/voltage list.
555 srcu_notifier_call_chain(&dev_opp->srcu_head, OPP_EVENT_REMOVE, opp);
556 list_del_rcu(&opp->node);
557 call_srcu(&dev_opp->srcu_head.srcu, &opp->rcu_head, kfree_opp_rcu);
559 if (list_empty(&dev_opp->opp_list)) {
560 list_del_rcu(&dev_opp->node);
561 call_srcu(&dev_opp->srcu_head.srcu, &dev_opp->rcu_head,
567 * dev_pm_opp_remove() - Remove an OPP from OPP list
568 * @dev: device for which we do this operation
569 * @freq: OPP to remove with matching 'freq'
571 * This function removes an opp from the opp list.
573 void dev_pm_opp_remove(struct device *dev, unsigned long freq)
575 struct dev_pm_opp *opp;
576 struct device_opp *dev_opp;
579 /* Hold our list modification lock here */
580 mutex_lock(&dev_opp_list_lock);
582 dev_opp = find_device_opp(dev);
586 list_for_each_entry(opp, &dev_opp->opp_list, node) {
587 if (opp->rate == freq) {
594 dev_warn(dev, "%s: Couldn't find OPP with freq: %lu\n",
599 __dev_pm_opp_remove(dev_opp, opp);
601 mutex_unlock(&dev_opp_list_lock);
603 EXPORT_SYMBOL_GPL(dev_pm_opp_remove);
606 * opp_set_availability() - helper to set the availability of an opp
607 * @dev: device for which we do this operation
608 * @freq: OPP frequency to modify availability
609 * @availability_req: availability status requested for this opp
611 * Set the availability of an OPP with an RCU operation, opp_{enable,disable}
612 * share a common logic which is isolated here.
614 * Returns -EINVAL for bad pointers, -ENOMEM if no memory available for the
615 * copy operation, returns 0 if no modifcation was done OR modification was
618 * Locking: The internal device_opp and opp structures are RCU protected.
619 * Hence this function internally uses RCU updater strategy with mutex locks to
620 * keep the integrity of the internal data structures. Callers should ensure
621 * that this function is *NOT* called under RCU protection or in contexts where
622 * mutex locking or synchronize_rcu() blocking calls cannot be used.
624 static int opp_set_availability(struct device *dev, unsigned long freq,
625 bool availability_req)
627 struct device_opp *dev_opp;
628 struct dev_pm_opp *new_opp, *tmp_opp, *opp = ERR_PTR(-ENODEV);
631 /* keep the node allocated */
632 new_opp = kmalloc(sizeof(*new_opp), GFP_KERNEL);
634 dev_warn(dev, "%s: Unable to create OPP\n", __func__);
638 mutex_lock(&dev_opp_list_lock);
640 /* Find the device_opp */
641 dev_opp = find_device_opp(dev);
642 if (IS_ERR(dev_opp)) {
643 r = PTR_ERR(dev_opp);
644 dev_warn(dev, "%s: Device OPP not found (%d)\n", __func__, r);
648 /* Do we have the frequency? */
649 list_for_each_entry(tmp_opp, &dev_opp->opp_list, node) {
650 if (tmp_opp->rate == freq) {
660 /* Is update really needed? */
661 if (opp->available == availability_req)
663 /* copy the old data over */
666 /* plug in new node */
667 new_opp->available = availability_req;
669 list_replace_rcu(&opp->node, &new_opp->node);
670 mutex_unlock(&dev_opp_list_lock);
671 call_srcu(&dev_opp->srcu_head.srcu, &opp->rcu_head, kfree_opp_rcu);
673 /* Notify the change of the OPP availability */
674 if (availability_req)
675 srcu_notifier_call_chain(&dev_opp->srcu_head, OPP_EVENT_ENABLE,
678 srcu_notifier_call_chain(&dev_opp->srcu_head, OPP_EVENT_DISABLE,
684 mutex_unlock(&dev_opp_list_lock);
690 * dev_pm_opp_enable() - Enable a specific OPP
691 * @dev: device for which we do this operation
692 * @freq: OPP frequency to enable
694 * Enables a provided opp. If the operation is valid, this returns 0, else the
695 * corresponding error value. It is meant to be used for users an OPP available
696 * after being temporarily made unavailable with dev_pm_opp_disable.
698 * Locking: The internal device_opp and opp structures are RCU protected.
699 * Hence this function indirectly uses RCU and mutex locks to keep the
700 * integrity of the internal data structures. Callers should ensure that
701 * this function is *NOT* called under RCU protection or in contexts where
702 * mutex locking or synchronize_rcu() blocking calls cannot be used.
704 int dev_pm_opp_enable(struct device *dev, unsigned long freq)
706 return opp_set_availability(dev, freq, true);
708 EXPORT_SYMBOL_GPL(dev_pm_opp_enable);
711 * dev_pm_opp_disable() - Disable a specific OPP
712 * @dev: device for which we do this operation
713 * @freq: OPP frequency to disable
715 * Disables a provided opp. If the operation is valid, this returns
716 * 0, else the corresponding error value. It is meant to be a temporary
717 * control by users to make this OPP not available until the circumstances are
718 * right to make it available again (with a call to dev_pm_opp_enable).
720 * Locking: The internal device_opp and opp structures are RCU protected.
721 * Hence this function indirectly uses RCU and mutex locks to keep the
722 * integrity of the internal data structures. Callers should ensure that
723 * this function is *NOT* called under RCU protection or in contexts where
724 * mutex locking or synchronize_rcu() blocking calls cannot be used.
726 int dev_pm_opp_disable(struct device *dev, unsigned long freq)
728 return opp_set_availability(dev, freq, false);
730 EXPORT_SYMBOL_GPL(dev_pm_opp_disable);
733 * dev_pm_opp_get_notifier() - find notifier_head of the device with opp
734 * @dev: device pointer used to lookup device OPPs.
736 struct srcu_notifier_head *dev_pm_opp_get_notifier(struct device *dev)
738 struct device_opp *dev_opp = find_device_opp(dev);
741 return ERR_CAST(dev_opp); /* matching type */
743 return &dev_opp->srcu_head;
748 * of_init_opp_table() - Initialize opp table from device tree
749 * @dev: device pointer used to lookup device OPPs.
751 * Register the initial OPP table with the OPP library for given device.
753 int of_init_opp_table(struct device *dev)
755 const struct property *prop;
759 prop = of_find_property(dev->of_node, "operating-points", NULL);
766 * Each OPP is a set of tuples consisting of frequency and
767 * voltage like <freq-kHz vol-uV>.
769 nr = prop->length / sizeof(u32);
771 dev_err(dev, "%s: Invalid OPP list\n", __func__);
777 unsigned long freq = be32_to_cpup(val++) * 1000;
778 unsigned long volt = be32_to_cpup(val++);
780 if (dev_pm_opp_add_dynamic(dev, freq, volt, false))
781 dev_warn(dev, "%s: Failed to add OPP %ld\n",
788 EXPORT_SYMBOL_GPL(of_init_opp_table);
791 * of_free_opp_table() - Free OPP table entries created from static DT entries
792 * @dev: device pointer used to lookup device OPPs.
794 * Free OPPs created using static entries present in DT.
796 void of_free_opp_table(struct device *dev)
798 struct device_opp *dev_opp;
799 struct dev_pm_opp *opp, *tmp;
801 /* Check for existing list for 'dev' */
802 dev_opp = find_device_opp(dev);
803 if (IS_ERR(dev_opp)) {
804 int error = PTR_ERR(dev_opp);
805 if (error != -ENODEV)
806 WARN(1, "%s: dev_opp: %d\n",
807 IS_ERR_OR_NULL(dev) ?
808 "Invalid device" : dev_name(dev),
813 /* Hold our list modification lock here */
814 mutex_lock(&dev_opp_list_lock);
816 /* Free static OPPs */
817 list_for_each_entry_safe(opp, tmp, &dev_opp->opp_list, node) {
819 __dev_pm_opp_remove(dev_opp, opp);
822 mutex_unlock(&dev_opp_list_lock);
824 EXPORT_SYMBOL_GPL(of_free_opp_table);