2 * Devices PM QoS constraints management
4 * Copyright (C) 2011 Texas Instruments, Inc.
6 * This program is free software; you can redistribute it and/or modify
7 * it under the terms of the GNU General Public License version 2 as
8 * published by the Free Software Foundation.
11 * This module exposes the interface to kernel space for specifying
12 * per-device PM QoS dependencies. It provides infrastructure for registration
15 * Dependents on a QoS value : register requests
16 * Watchers of QoS value : get notified when target QoS value changes
18 * This QoS design is best effort based. Dependents register their QoS needs.
19 * Watchers register to keep track of the current QoS needs of the system.
20 * Watchers can register different types of notification callbacks:
21 * . a per-device notification callback using the dev_pm_qos_*_notifier API.
22 * The notification chain data is stored in the per-device constraint
24 * . a system-wide notification callback using the dev_pm_qos_*_global_notifier
25 * API. The notification chain data is stored in a static variable.
27 * Note about the per-device constraint data struct allocation:
28 * . The per-device constraints data struct ptr is tored into the device
30 * . To minimize the data usage by the per-device constraints, the data struct
31 * is only allocated at the first call to dev_pm_qos_add_request.
32 * . The data is later free'd when the device is removed from the system.
33 * . A global mutex protects the constraints users from the data being
34 * allocated and free'd.
37 #include <linux/pm_qos.h>
38 #include <linux/spinlock.h>
39 #include <linux/slab.h>
40 #include <linux/device.h>
41 #include <linux/mutex.h>
42 #include <linux/export.h>
43 #include <linux/pm_runtime.h>
47 static DEFINE_MUTEX(dev_pm_qos_mtx);
49 static BLOCKING_NOTIFIER_HEAD(dev_pm_notifiers);
52 * __dev_pm_qos_flags - Check PM QoS flags for a given device.
53 * @dev: Device to check the PM QoS flags for.
54 * @mask: Flags to check against.
56 * This routine must be called with dev->power.lock held.
58 enum pm_qos_flags_status __dev_pm_qos_flags(struct device *dev, s32 mask)
60 struct dev_pm_qos *qos = dev->power.qos;
61 struct pm_qos_flags *pqf;
65 return PM_QOS_FLAGS_UNDEFINED;
68 if (list_empty(&pqf->list))
69 return PM_QOS_FLAGS_UNDEFINED;
71 val = pqf->effective_flags & mask;
73 return (val == mask) ? PM_QOS_FLAGS_ALL : PM_QOS_FLAGS_SOME;
75 return PM_QOS_FLAGS_NONE;
79 * dev_pm_qos_flags - Check PM QoS flags for a given device (locked).
80 * @dev: Device to check the PM QoS flags for.
81 * @mask: Flags to check against.
83 enum pm_qos_flags_status dev_pm_qos_flags(struct device *dev, s32 mask)
85 unsigned long irqflags;
86 enum pm_qos_flags_status ret;
88 spin_lock_irqsave(&dev->power.lock, irqflags);
89 ret = __dev_pm_qos_flags(dev, mask);
90 spin_unlock_irqrestore(&dev->power.lock, irqflags);
94 EXPORT_SYMBOL_GPL(dev_pm_qos_flags);
97 * __dev_pm_qos_read_value - Get PM QoS constraint for a given device.
98 * @dev: Device to get the PM QoS constraint value for.
100 * This routine must be called with dev->power.lock held.
102 s32 __dev_pm_qos_read_value(struct device *dev)
104 return dev->power.qos ? pm_qos_read_value(&dev->power.qos->latency) : 0;
108 * dev_pm_qos_read_value - Get PM QoS constraint for a given device (locked).
109 * @dev: Device to get the PM QoS constraint value for.
111 s32 dev_pm_qos_read_value(struct device *dev)
116 spin_lock_irqsave(&dev->power.lock, flags);
117 ret = __dev_pm_qos_read_value(dev);
118 spin_unlock_irqrestore(&dev->power.lock, flags);
124 * apply_constraint - Add/modify/remove device PM QoS request.
125 * @req: Constraint request to apply
126 * @action: Action to perform (add/update/remove).
127 * @value: Value to assign to the QoS request.
129 * Internal function to update the constraints list using the PM QoS core
130 * code and if needed call the per-device and the global notification
133 static int apply_constraint(struct dev_pm_qos_request *req,
134 enum pm_qos_req_action action, s32 value)
136 struct dev_pm_qos *qos = req->dev->power.qos;
140 case DEV_PM_QOS_LATENCY:
141 ret = pm_qos_update_target(&qos->latency, &req->data.pnode,
144 value = pm_qos_read_value(&qos->latency);
145 blocking_notifier_call_chain(&dev_pm_notifiers,
146 (unsigned long)value,
150 case DEV_PM_QOS_FLAGS:
151 ret = pm_qos_update_flags(&qos->flags, &req->data.flr,
162 * dev_pm_qos_constraints_allocate
163 * @dev: device to allocate data for
165 * Called at the first call to add_request, for constraint data allocation
166 * Must be called with the dev_pm_qos_mtx mutex held
168 static int dev_pm_qos_constraints_allocate(struct device *dev)
170 struct dev_pm_qos *qos;
171 struct pm_qos_constraints *c;
172 struct blocking_notifier_head *n;
174 qos = kzalloc(sizeof(*qos), GFP_KERNEL);
178 n = kzalloc(sizeof(*n), GFP_KERNEL);
183 BLOCKING_INIT_NOTIFIER_HEAD(n);
186 plist_head_init(&c->list);
187 c->target_value = PM_QOS_DEV_LAT_DEFAULT_VALUE;
188 c->default_value = PM_QOS_DEV_LAT_DEFAULT_VALUE;
189 c->type = PM_QOS_MIN;
192 INIT_LIST_HEAD(&qos->flags.list);
194 spin_lock_irq(&dev->power.lock);
195 dev->power.qos = qos;
196 spin_unlock_irq(&dev->power.lock);
202 * dev_pm_qos_constraints_init - Initalize device's PM QoS constraints pointer.
203 * @dev: target device
205 * Called from the device PM subsystem during device insertion under
208 void dev_pm_qos_constraints_init(struct device *dev)
210 mutex_lock(&dev_pm_qos_mtx);
211 dev->power.qos = NULL;
212 dev->power.power_state = PMSG_ON;
213 mutex_unlock(&dev_pm_qos_mtx);
217 * dev_pm_qos_constraints_destroy
218 * @dev: target device
220 * Called from the device PM subsystem on device removal under device_pm_lock().
222 void dev_pm_qos_constraints_destroy(struct device *dev)
224 struct dev_pm_qos *qos;
225 struct dev_pm_qos_request *req, *tmp;
226 struct pm_qos_constraints *c;
227 struct pm_qos_flags *f;
230 * If the device's PM QoS resume latency limit or PM QoS flags have been
231 * exposed to user space, they have to be hidden at this point.
233 dev_pm_qos_hide_latency_limit(dev);
234 dev_pm_qos_hide_flags(dev);
236 mutex_lock(&dev_pm_qos_mtx);
238 dev->power.power_state = PMSG_INVALID;
239 qos = dev->power.qos;
243 /* Flush the constraints lists for the device. */
245 plist_for_each_entry_safe(req, tmp, &c->list, data.pnode) {
247 * Update constraints list and call the notification
248 * callbacks if needed
250 apply_constraint(req, PM_QOS_REMOVE_REQ, PM_QOS_DEFAULT_VALUE);
251 memset(req, 0, sizeof(*req));
254 list_for_each_entry_safe(req, tmp, &f->list, data.flr.node) {
255 apply_constraint(req, PM_QOS_REMOVE_REQ, PM_QOS_DEFAULT_VALUE);
256 memset(req, 0, sizeof(*req));
259 spin_lock_irq(&dev->power.lock);
260 dev->power.qos = NULL;
261 spin_unlock_irq(&dev->power.lock);
267 mutex_unlock(&dev_pm_qos_mtx);
271 * dev_pm_qos_add_request - inserts new qos request into the list
272 * @dev: target device for the constraint
273 * @req: pointer to a preallocated handle
274 * @type: type of the request
275 * @value: defines the qos request
277 * This function inserts a new entry in the device constraints list of
278 * requested qos performance characteristics. It recomputes the aggregate
279 * QoS expectations of parameters and initializes the dev_pm_qos_request
280 * handle. Caller needs to save this handle for later use in updates and
283 * Returns 1 if the aggregated constraint value has changed,
284 * 0 if the aggregated constraint value has not changed,
285 * -EINVAL in case of wrong parameters, -ENOMEM if there's not enough memory
286 * to allocate for data structures, -ENODEV if the device has just been removed
289 * Callers should ensure that the target device is not RPM_SUSPENDED before
290 * using this function for requests of type DEV_PM_QOS_FLAGS.
292 int dev_pm_qos_add_request(struct device *dev, struct dev_pm_qos_request *req,
293 enum dev_pm_qos_req_type type, s32 value)
297 if (!dev || !req) /*guard against callers passing in null */
300 if (WARN(dev_pm_qos_request_active(req),
301 "%s() called for already added request\n", __func__))
306 mutex_lock(&dev_pm_qos_mtx);
308 if (!dev->power.qos) {
309 if (dev->power.power_state.event == PM_EVENT_INVALID) {
310 /* The device has been removed from the system. */
316 * Allocate the constraints data on the first call to
317 * add_request, i.e. only if the data is not already
318 * allocated and if the device has not been removed.
320 ret = dev_pm_qos_constraints_allocate(dev);
326 ret = apply_constraint(req, PM_QOS_ADD_REQ, value);
330 mutex_unlock(&dev_pm_qos_mtx);
334 EXPORT_SYMBOL_GPL(dev_pm_qos_add_request);
337 * __dev_pm_qos_update_request - Modify an existing device PM QoS request.
338 * @req : PM QoS request to modify.
339 * @new_value: New value to request.
341 static int __dev_pm_qos_update_request(struct dev_pm_qos_request *req,
347 if (!req) /*guard against callers passing in null */
350 if (WARN(!dev_pm_qos_request_active(req),
351 "%s() called for unknown object\n", __func__))
354 if (!req->dev->power.qos)
358 case DEV_PM_QOS_LATENCY:
359 curr_value = req->data.pnode.prio;
361 case DEV_PM_QOS_FLAGS:
362 curr_value = req->data.flr.flags;
368 if (curr_value != new_value)
369 ret = apply_constraint(req, PM_QOS_UPDATE_REQ, new_value);
375 * dev_pm_qos_update_request - modifies an existing qos request
376 * @req : handle to list element holding a dev_pm_qos request to use
377 * @new_value: defines the qos request
379 * Updates an existing dev PM qos request along with updating the
382 * Attempts are made to make this code callable on hot code paths.
384 * Returns 1 if the aggregated constraint value has changed,
385 * 0 if the aggregated constraint value has not changed,
386 * -EINVAL in case of wrong parameters, -ENODEV if the device has been
387 * removed from the system
389 * Callers should ensure that the target device is not RPM_SUSPENDED before
390 * using this function for requests of type DEV_PM_QOS_FLAGS.
392 int dev_pm_qos_update_request(struct dev_pm_qos_request *req, s32 new_value)
396 mutex_lock(&dev_pm_qos_mtx);
397 ret = __dev_pm_qos_update_request(req, new_value);
398 mutex_unlock(&dev_pm_qos_mtx);
401 EXPORT_SYMBOL_GPL(dev_pm_qos_update_request);
403 static int __dev_pm_qos_remove_request(struct dev_pm_qos_request *req)
407 if (!req) /*guard against callers passing in null */
410 if (WARN(!dev_pm_qos_request_active(req),
411 "%s() called for unknown object\n", __func__))
414 if (req->dev->power.qos) {
415 ret = apply_constraint(req, PM_QOS_REMOVE_REQ,
416 PM_QOS_DEFAULT_VALUE);
417 memset(req, 0, sizeof(*req));
425 * dev_pm_qos_remove_request - modifies an existing qos request
426 * @req: handle to request list element
428 * Will remove pm qos request from the list of constraints and
429 * recompute the current target value. Call this on slow code paths.
431 * Returns 1 if the aggregated constraint value has changed,
432 * 0 if the aggregated constraint value has not changed,
433 * -EINVAL in case of wrong parameters, -ENODEV if the device has been
434 * removed from the system
436 * Callers should ensure that the target device is not RPM_SUSPENDED before
437 * using this function for requests of type DEV_PM_QOS_FLAGS.
439 int dev_pm_qos_remove_request(struct dev_pm_qos_request *req)
443 mutex_lock(&dev_pm_qos_mtx);
444 ret = __dev_pm_qos_remove_request(req);
445 mutex_unlock(&dev_pm_qos_mtx);
448 EXPORT_SYMBOL_GPL(dev_pm_qos_remove_request);
451 * dev_pm_qos_add_notifier - sets notification entry for changes to target value
452 * of per-device PM QoS constraints
454 * @dev: target device for the constraint
455 * @notifier: notifier block managed by caller.
457 * Will register the notifier into a notification chain that gets called
458 * upon changes to the target value for the device.
460 * If the device's constraints object doesn't exist when this routine is called,
461 * it will be created (or error code will be returned if that fails).
463 int dev_pm_qos_add_notifier(struct device *dev, struct notifier_block *notifier)
467 mutex_lock(&dev_pm_qos_mtx);
470 ret = dev->power.power_state.event != PM_EVENT_INVALID ?
471 dev_pm_qos_constraints_allocate(dev) : -ENODEV;
474 ret = blocking_notifier_chain_register(
475 dev->power.qos->latency.notifiers, notifier);
477 mutex_unlock(&dev_pm_qos_mtx);
480 EXPORT_SYMBOL_GPL(dev_pm_qos_add_notifier);
483 * dev_pm_qos_remove_notifier - deletes notification for changes to target value
484 * of per-device PM QoS constraints
486 * @dev: target device for the constraint
487 * @notifier: notifier block to be removed.
489 * Will remove the notifier from the notification chain that gets called
490 * upon changes to the target value.
492 int dev_pm_qos_remove_notifier(struct device *dev,
493 struct notifier_block *notifier)
497 mutex_lock(&dev_pm_qos_mtx);
499 /* Silently return if the constraints object is not present. */
501 retval = blocking_notifier_chain_unregister(
502 dev->power.qos->latency.notifiers,
505 mutex_unlock(&dev_pm_qos_mtx);
508 EXPORT_SYMBOL_GPL(dev_pm_qos_remove_notifier);
511 * dev_pm_qos_add_global_notifier - sets notification entry for changes to
512 * target value of the PM QoS constraints for any device
514 * @notifier: notifier block managed by caller.
516 * Will register the notifier into a notification chain that gets called
517 * upon changes to the target value for any device.
519 int dev_pm_qos_add_global_notifier(struct notifier_block *notifier)
521 return blocking_notifier_chain_register(&dev_pm_notifiers, notifier);
523 EXPORT_SYMBOL_GPL(dev_pm_qos_add_global_notifier);
526 * dev_pm_qos_remove_global_notifier - deletes notification for changes to
527 * target value of PM QoS constraints for any device
529 * @notifier: notifier block to be removed.
531 * Will remove the notifier from the notification chain that gets called
532 * upon changes to the target value for any device.
534 int dev_pm_qos_remove_global_notifier(struct notifier_block *notifier)
536 return blocking_notifier_chain_unregister(&dev_pm_notifiers, notifier);
538 EXPORT_SYMBOL_GPL(dev_pm_qos_remove_global_notifier);
541 * dev_pm_qos_add_ancestor_request - Add PM QoS request for device's ancestor.
542 * @dev: Device whose ancestor to add the request for.
543 * @req: Pointer to the preallocated handle.
544 * @value: Constraint latency value.
546 int dev_pm_qos_add_ancestor_request(struct device *dev,
547 struct dev_pm_qos_request *req, s32 value)
549 struct device *ancestor = dev->parent;
552 while (ancestor && !ancestor->power.ignore_children)
553 ancestor = ancestor->parent;
556 ret = dev_pm_qos_add_request(ancestor, req,
557 DEV_PM_QOS_LATENCY, value);
564 EXPORT_SYMBOL_GPL(dev_pm_qos_add_ancestor_request);
566 #ifdef CONFIG_PM_RUNTIME
567 static void __dev_pm_qos_drop_user_request(struct device *dev,
568 enum dev_pm_qos_req_type type)
570 struct dev_pm_qos_request *req = NULL;
573 case DEV_PM_QOS_LATENCY:
574 req = dev->power.qos->latency_req;
575 dev->power.qos->latency_req = NULL;
577 case DEV_PM_QOS_FLAGS:
578 req = dev->power.qos->flags_req;
579 dev->power.qos->flags_req = NULL;
582 __dev_pm_qos_remove_request(req);
587 * dev_pm_qos_expose_latency_limit - Expose PM QoS latency limit to user space.
588 * @dev: Device whose PM QoS latency limit is to be exposed to user space.
589 * @value: Initial value of the latency limit.
591 int dev_pm_qos_expose_latency_limit(struct device *dev, s32 value)
593 struct dev_pm_qos_request *req;
596 if (!device_is_registered(dev) || value < 0)
599 req = kzalloc(sizeof(*req), GFP_KERNEL);
603 ret = dev_pm_qos_add_request(dev, req, DEV_PM_QOS_LATENCY, value);
609 mutex_lock(&dev_pm_qos_mtx);
613 else if (dev->power.qos->latency_req)
617 __dev_pm_qos_remove_request(req);
622 dev->power.qos->latency_req = req;
623 ret = pm_qos_sysfs_add_latency(dev);
625 __dev_pm_qos_drop_user_request(dev, DEV_PM_QOS_LATENCY);
628 mutex_unlock(&dev_pm_qos_mtx);
631 EXPORT_SYMBOL_GPL(dev_pm_qos_expose_latency_limit);
634 * dev_pm_qos_hide_latency_limit - Hide PM QoS latency limit from user space.
635 * @dev: Device whose PM QoS latency limit is to be hidden from user space.
637 void dev_pm_qos_hide_latency_limit(struct device *dev)
639 mutex_lock(&dev_pm_qos_mtx);
641 if (dev->power.qos && dev->power.qos->latency_req) {
642 pm_qos_sysfs_remove_latency(dev);
643 __dev_pm_qos_drop_user_request(dev, DEV_PM_QOS_LATENCY);
646 mutex_unlock(&dev_pm_qos_mtx);
648 EXPORT_SYMBOL_GPL(dev_pm_qos_hide_latency_limit);
651 * dev_pm_qos_expose_flags - Expose PM QoS flags of a device to user space.
652 * @dev: Device whose PM QoS flags are to be exposed to user space.
653 * @val: Initial values of the flags.
655 int dev_pm_qos_expose_flags(struct device *dev, s32 val)
657 struct dev_pm_qos_request *req;
660 if (!device_is_registered(dev))
663 req = kzalloc(sizeof(*req), GFP_KERNEL);
667 ret = dev_pm_qos_add_request(dev, req, DEV_PM_QOS_FLAGS, val);
673 pm_runtime_get_sync(dev);
674 mutex_lock(&dev_pm_qos_mtx);
678 else if (dev->power.qos->flags_req)
682 __dev_pm_qos_remove_request(req);
687 dev->power.qos->flags_req = req;
688 ret = pm_qos_sysfs_add_flags(dev);
690 __dev_pm_qos_drop_user_request(dev, DEV_PM_QOS_FLAGS);
693 mutex_unlock(&dev_pm_qos_mtx);
697 EXPORT_SYMBOL_GPL(dev_pm_qos_expose_flags);
700 * dev_pm_qos_hide_flags - Hide PM QoS flags of a device from user space.
701 * @dev: Device whose PM QoS flags are to be hidden from user space.
703 void dev_pm_qos_hide_flags(struct device *dev)
705 pm_runtime_get_sync(dev);
706 mutex_lock(&dev_pm_qos_mtx);
708 if (dev->power.qos && dev->power.qos->flags_req) {
709 pm_qos_sysfs_remove_flags(dev);
710 __dev_pm_qos_drop_user_request(dev, DEV_PM_QOS_FLAGS);
713 mutex_unlock(&dev_pm_qos_mtx);
716 EXPORT_SYMBOL_GPL(dev_pm_qos_hide_flags);
719 * dev_pm_qos_update_flags - Update PM QoS flags request owned by user space.
720 * @dev: Device to update the PM QoS flags request for.
721 * @mask: Flags to set/clear.
722 * @set: Whether to set or clear the flags (true means set).
724 int dev_pm_qos_update_flags(struct device *dev, s32 mask, bool set)
729 pm_runtime_get_sync(dev);
730 mutex_lock(&dev_pm_qos_mtx);
732 if (!dev->power.qos || !dev->power.qos->flags_req) {
737 value = dev_pm_qos_requested_flags(dev);
743 ret = __dev_pm_qos_update_request(dev->power.qos->flags_req, value);
746 mutex_unlock(&dev_pm_qos_mtx);
750 #endif /* CONFIG_PM_RUNTIME */