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);
96 * __dev_pm_qos_read_value - Get PM QoS constraint for a given device.
97 * @dev: Device to get the PM QoS constraint value for.
99 * This routine must be called with dev->power.lock held.
101 s32 __dev_pm_qos_read_value(struct device *dev)
103 return dev->power.qos ? pm_qos_read_value(&dev->power.qos->latency) : 0;
107 * dev_pm_qos_read_value - Get PM QoS constraint for a given device (locked).
108 * @dev: Device to get the PM QoS constraint value for.
110 s32 dev_pm_qos_read_value(struct device *dev)
115 spin_lock_irqsave(&dev->power.lock, flags);
116 ret = __dev_pm_qos_read_value(dev);
117 spin_unlock_irqrestore(&dev->power.lock, flags);
123 * apply_constraint - Add/modify/remove device PM QoS request.
124 * @req: Constraint request to apply
125 * @action: Action to perform (add/update/remove).
126 * @value: Value to assign to the QoS request.
128 * Internal function to update the constraints list using the PM QoS core
129 * code and if needed call the per-device and the global notification
132 static int apply_constraint(struct dev_pm_qos_request *req,
133 enum pm_qos_req_action action, s32 value)
135 struct dev_pm_qos *qos = req->dev->power.qos;
139 case DEV_PM_QOS_LATENCY:
140 ret = pm_qos_update_target(&qos->latency, &req->data.pnode,
143 value = pm_qos_read_value(&qos->latency);
144 blocking_notifier_call_chain(&dev_pm_notifiers,
145 (unsigned long)value,
149 case DEV_PM_QOS_FLAGS:
150 ret = pm_qos_update_flags(&qos->flags, &req->data.flr,
161 * dev_pm_qos_constraints_allocate
162 * @dev: device to allocate data for
164 * Called at the first call to add_request, for constraint data allocation
165 * Must be called with the dev_pm_qos_mtx mutex held
167 static int dev_pm_qos_constraints_allocate(struct device *dev)
169 struct dev_pm_qos *qos;
170 struct pm_qos_constraints *c;
171 struct blocking_notifier_head *n;
173 qos = kzalloc(sizeof(*qos), GFP_KERNEL);
177 n = kzalloc(sizeof(*n), GFP_KERNEL);
182 BLOCKING_INIT_NOTIFIER_HEAD(n);
185 plist_head_init(&c->list);
186 c->target_value = PM_QOS_DEV_LAT_DEFAULT_VALUE;
187 c->default_value = PM_QOS_DEV_LAT_DEFAULT_VALUE;
188 c->type = PM_QOS_MIN;
191 INIT_LIST_HEAD(&qos->flags.list);
193 spin_lock_irq(&dev->power.lock);
194 dev->power.qos = qos;
195 spin_unlock_irq(&dev->power.lock);
201 * dev_pm_qos_constraints_init - Initalize device's PM QoS constraints pointer.
202 * @dev: target device
204 * Called from the device PM subsystem during device insertion under
207 void dev_pm_qos_constraints_init(struct device *dev)
209 mutex_lock(&dev_pm_qos_mtx);
210 dev->power.qos = NULL;
211 dev->power.power_state = PMSG_ON;
212 mutex_unlock(&dev_pm_qos_mtx);
216 * dev_pm_qos_constraints_destroy
217 * @dev: target device
219 * Called from the device PM subsystem on device removal under device_pm_lock().
221 void dev_pm_qos_constraints_destroy(struct device *dev)
223 struct dev_pm_qos *qos;
224 struct dev_pm_qos_request *req, *tmp;
225 struct pm_qos_constraints *c;
228 * If the device's PM QoS resume latency limit has been exposed to user
229 * space, it has to be hidden at this point.
231 dev_pm_qos_hide_latency_limit(dev);
233 mutex_lock(&dev_pm_qos_mtx);
235 dev->power.power_state = PMSG_INVALID;
236 qos = dev->power.qos;
241 /* Flush the constraints list for the device */
242 plist_for_each_entry_safe(req, tmp, &c->list, data.pnode) {
244 * Update constraints list and call the notification
245 * callbacks if needed
247 apply_constraint(req, PM_QOS_REMOVE_REQ, PM_QOS_DEFAULT_VALUE);
248 memset(req, 0, sizeof(*req));
251 spin_lock_irq(&dev->power.lock);
252 dev->power.qos = NULL;
253 spin_unlock_irq(&dev->power.lock);
259 mutex_unlock(&dev_pm_qos_mtx);
263 * dev_pm_qos_add_request - inserts new qos request into the list
264 * @dev: target device for the constraint
265 * @req: pointer to a preallocated handle
266 * @type: type of the request
267 * @value: defines the qos request
269 * This function inserts a new entry in the device constraints list of
270 * requested qos performance characteristics. It recomputes the aggregate
271 * QoS expectations of parameters and initializes the dev_pm_qos_request
272 * handle. Caller needs to save this handle for later use in updates and
275 * Returns 1 if the aggregated constraint value has changed,
276 * 0 if the aggregated constraint value has not changed,
277 * -EINVAL in case of wrong parameters, -ENOMEM if there's not enough memory
278 * to allocate for data structures, -ENODEV if the device has just been removed
281 int dev_pm_qos_add_request(struct device *dev, struct dev_pm_qos_request *req,
282 enum dev_pm_qos_req_type type, s32 value)
286 if (!dev || !req) /*guard against callers passing in null */
289 if (WARN(dev_pm_qos_request_active(req),
290 "%s() called for already added request\n", __func__))
295 mutex_lock(&dev_pm_qos_mtx);
297 if (!dev->power.qos) {
298 if (dev->power.power_state.event == PM_EVENT_INVALID) {
299 /* The device has been removed from the system. */
305 * Allocate the constraints data on the first call to
306 * add_request, i.e. only if the data is not already
307 * allocated and if the device has not been removed.
309 ret = dev_pm_qos_constraints_allocate(dev);
315 ret = apply_constraint(req, PM_QOS_ADD_REQ, value);
319 mutex_unlock(&dev_pm_qos_mtx);
323 EXPORT_SYMBOL_GPL(dev_pm_qos_add_request);
326 * __dev_pm_qos_update_request - Modify an existing device PM QoS request.
327 * @req : PM QoS request to modify.
328 * @new_value: New value to request.
330 static int __dev_pm_qos_update_request(struct dev_pm_qos_request *req,
336 if (!req->dev->power.qos)
340 case DEV_PM_QOS_LATENCY:
341 curr_value = req->data.pnode.prio;
343 case DEV_PM_QOS_FLAGS:
344 curr_value = req->data.flr.flags;
350 if (curr_value != new_value)
351 ret = apply_constraint(req, PM_QOS_UPDATE_REQ, new_value);
357 * dev_pm_qos_update_request - modifies an existing qos request
358 * @req : handle to list element holding a dev_pm_qos request to use
359 * @new_value: defines the qos request
361 * Updates an existing dev PM qos request along with updating the
364 * Attempts are made to make this code callable on hot code paths.
366 * Returns 1 if the aggregated constraint value has changed,
367 * 0 if the aggregated constraint value has not changed,
368 * -EINVAL in case of wrong parameters, -ENODEV if the device has been
369 * removed from the system
371 int dev_pm_qos_update_request(struct dev_pm_qos_request *req, s32 new_value)
375 if (!req) /*guard against callers passing in null */
378 if (WARN(!dev_pm_qos_request_active(req),
379 "%s() called for unknown object\n", __func__))
382 mutex_lock(&dev_pm_qos_mtx);
383 __dev_pm_qos_update_request(req, new_value);
384 mutex_unlock(&dev_pm_qos_mtx);
388 EXPORT_SYMBOL_GPL(dev_pm_qos_update_request);
391 * dev_pm_qos_remove_request - modifies an existing qos request
392 * @req: handle to request list element
394 * Will remove pm qos request from the list of constraints and
395 * recompute the current target value. Call this on slow code paths.
397 * Returns 1 if the aggregated constraint value has changed,
398 * 0 if the aggregated constraint value has not changed,
399 * -EINVAL in case of wrong parameters, -ENODEV if the device has been
400 * removed from the system
402 int dev_pm_qos_remove_request(struct dev_pm_qos_request *req)
406 if (!req) /*guard against callers passing in null */
409 if (WARN(!dev_pm_qos_request_active(req),
410 "%s() called for unknown object\n", __func__))
413 mutex_lock(&dev_pm_qos_mtx);
415 if (req->dev->power.qos) {
416 ret = apply_constraint(req, PM_QOS_REMOVE_REQ,
417 PM_QOS_DEFAULT_VALUE);
418 memset(req, 0, sizeof(*req));
420 /* Return if the device has been removed */
424 mutex_unlock(&dev_pm_qos_mtx);
427 EXPORT_SYMBOL_GPL(dev_pm_qos_remove_request);
430 * dev_pm_qos_add_notifier - sets notification entry for changes to target value
431 * of per-device PM QoS constraints
433 * @dev: target device for the constraint
434 * @notifier: notifier block managed by caller.
436 * Will register the notifier into a notification chain that gets called
437 * upon changes to the target value for the device.
439 * If the device's constraints object doesn't exist when this routine is called,
440 * it will be created (or error code will be returned if that fails).
442 int dev_pm_qos_add_notifier(struct device *dev, struct notifier_block *notifier)
446 mutex_lock(&dev_pm_qos_mtx);
449 ret = dev->power.power_state.event != PM_EVENT_INVALID ?
450 dev_pm_qos_constraints_allocate(dev) : -ENODEV;
453 ret = blocking_notifier_chain_register(
454 dev->power.qos->latency.notifiers, notifier);
456 mutex_unlock(&dev_pm_qos_mtx);
459 EXPORT_SYMBOL_GPL(dev_pm_qos_add_notifier);
462 * dev_pm_qos_remove_notifier - deletes notification for changes to target value
463 * of per-device PM QoS constraints
465 * @dev: target device for the constraint
466 * @notifier: notifier block to be removed.
468 * Will remove the notifier from the notification chain that gets called
469 * upon changes to the target value.
471 int dev_pm_qos_remove_notifier(struct device *dev,
472 struct notifier_block *notifier)
476 mutex_lock(&dev_pm_qos_mtx);
478 /* Silently return if the constraints object is not present. */
480 retval = blocking_notifier_chain_unregister(
481 dev->power.qos->latency.notifiers,
484 mutex_unlock(&dev_pm_qos_mtx);
487 EXPORT_SYMBOL_GPL(dev_pm_qos_remove_notifier);
490 * dev_pm_qos_add_global_notifier - sets notification entry for changes to
491 * target value of the PM QoS constraints for any device
493 * @notifier: notifier block managed by caller.
495 * Will register the notifier into a notification chain that gets called
496 * upon changes to the target value for any device.
498 int dev_pm_qos_add_global_notifier(struct notifier_block *notifier)
500 return blocking_notifier_chain_register(&dev_pm_notifiers, notifier);
502 EXPORT_SYMBOL_GPL(dev_pm_qos_add_global_notifier);
505 * dev_pm_qos_remove_global_notifier - deletes notification for changes to
506 * target value of PM QoS constraints for any device
508 * @notifier: notifier block to be removed.
510 * Will remove the notifier from the notification chain that gets called
511 * upon changes to the target value for any device.
513 int dev_pm_qos_remove_global_notifier(struct notifier_block *notifier)
515 return blocking_notifier_chain_unregister(&dev_pm_notifiers, notifier);
517 EXPORT_SYMBOL_GPL(dev_pm_qos_remove_global_notifier);
520 * dev_pm_qos_add_ancestor_request - Add PM QoS request for device's ancestor.
521 * @dev: Device whose ancestor to add the request for.
522 * @req: Pointer to the preallocated handle.
523 * @value: Constraint latency value.
525 int dev_pm_qos_add_ancestor_request(struct device *dev,
526 struct dev_pm_qos_request *req, s32 value)
528 struct device *ancestor = dev->parent;
531 while (ancestor && !ancestor->power.ignore_children)
532 ancestor = ancestor->parent;
535 error = dev_pm_qos_add_request(ancestor, req,
536 DEV_PM_QOS_LATENCY, value);
543 EXPORT_SYMBOL_GPL(dev_pm_qos_add_ancestor_request);
545 #ifdef CONFIG_PM_RUNTIME
546 static void __dev_pm_qos_drop_user_request(struct device *dev,
547 enum dev_pm_qos_req_type type)
550 case DEV_PM_QOS_LATENCY:
551 dev_pm_qos_remove_request(dev->power.qos->latency_req);
552 dev->power.qos->latency_req = NULL;
554 case DEV_PM_QOS_FLAGS:
555 dev_pm_qos_remove_request(dev->power.qos->flags_req);
556 dev->power.qos->flags_req = NULL;
562 * dev_pm_qos_expose_latency_limit - Expose PM QoS latency limit to user space.
563 * @dev: Device whose PM QoS latency limit is to be exposed to user space.
564 * @value: Initial value of the latency limit.
566 int dev_pm_qos_expose_latency_limit(struct device *dev, s32 value)
568 struct dev_pm_qos_request *req;
571 if (!device_is_registered(dev) || value < 0)
574 if (dev->power.qos && dev->power.qos->latency_req)
577 req = kzalloc(sizeof(*req), GFP_KERNEL);
581 ret = dev_pm_qos_add_request(dev, req, DEV_PM_QOS_LATENCY, value);
585 dev->power.qos->latency_req = req;
586 ret = pm_qos_sysfs_add_latency(dev);
588 __dev_pm_qos_drop_user_request(dev, DEV_PM_QOS_LATENCY);
592 EXPORT_SYMBOL_GPL(dev_pm_qos_expose_latency_limit);
595 * dev_pm_qos_hide_latency_limit - Hide PM QoS latency limit from user space.
596 * @dev: Device whose PM QoS latency limit is to be hidden from user space.
598 void dev_pm_qos_hide_latency_limit(struct device *dev)
600 if (dev->power.qos && dev->power.qos->latency_req) {
601 pm_qos_sysfs_remove_latency(dev);
602 __dev_pm_qos_drop_user_request(dev, DEV_PM_QOS_LATENCY);
605 EXPORT_SYMBOL_GPL(dev_pm_qos_hide_latency_limit);
608 * dev_pm_qos_expose_flags - Expose PM QoS flags of a device to user space.
609 * @dev: Device whose PM QoS flags are to be exposed to user space.
610 * @val: Initial values of the flags.
612 int dev_pm_qos_expose_flags(struct device *dev, s32 val)
614 struct dev_pm_qos_request *req;
617 if (!device_is_registered(dev))
620 if (dev->power.qos && dev->power.qos->flags_req)
623 req = kzalloc(sizeof(*req), GFP_KERNEL);
627 ret = dev_pm_qos_add_request(dev, req, DEV_PM_QOS_FLAGS, val);
631 dev->power.qos->flags_req = req;
632 ret = pm_qos_sysfs_add_flags(dev);
634 __dev_pm_qos_drop_user_request(dev, DEV_PM_QOS_FLAGS);
638 EXPORT_SYMBOL_GPL(dev_pm_qos_expose_flags);
641 * dev_pm_qos_hide_flags - Hide PM QoS flags of a device from user space.
642 * @dev: Device whose PM QoS flags are to be hidden from user space.
644 void dev_pm_qos_hide_flags(struct device *dev)
646 if (dev->power.qos && dev->power.qos->flags_req) {
647 pm_qos_sysfs_remove_flags(dev);
648 __dev_pm_qos_drop_user_request(dev, DEV_PM_QOS_FLAGS);
651 EXPORT_SYMBOL_GPL(dev_pm_qos_hide_flags);
654 * dev_pm_qos_update_flags - Update PM QoS flags request owned by user space.
655 * @dev: Device to update the PM QoS flags request for.
656 * @mask: Flags to set/clear.
657 * @set: Whether to set or clear the flags (true means set).
659 int dev_pm_qos_update_flags(struct device *dev, s32 mask, bool set)
664 if (!dev->power.qos || !dev->power.qos->flags_req)
667 pm_runtime_get_sync(dev);
668 mutex_lock(&dev_pm_qos_mtx);
670 value = dev_pm_qos_requested_flags(dev);
676 ret = __dev_pm_qos_update_request(dev->power.qos->flags_req, value);
678 mutex_unlock(&dev_pm_qos_mtx);
683 #endif /* CONFIG_PM_RUNTIME */