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 * Callers should ensure that the target device is not RPM_SUSPENDED before
282 * using this function for requests of type DEV_PM_QOS_FLAGS.
284 int dev_pm_qos_add_request(struct device *dev, struct dev_pm_qos_request *req,
285 enum dev_pm_qos_req_type type, s32 value)
289 if (!dev || !req) /*guard against callers passing in null */
292 if (WARN(dev_pm_qos_request_active(req),
293 "%s() called for already added request\n", __func__))
298 mutex_lock(&dev_pm_qos_mtx);
300 if (!dev->power.qos) {
301 if (dev->power.power_state.event == PM_EVENT_INVALID) {
302 /* The device has been removed from the system. */
308 * Allocate the constraints data on the first call to
309 * add_request, i.e. only if the data is not already
310 * allocated and if the device has not been removed.
312 ret = dev_pm_qos_constraints_allocate(dev);
318 ret = apply_constraint(req, PM_QOS_ADD_REQ, value);
322 mutex_unlock(&dev_pm_qos_mtx);
326 EXPORT_SYMBOL_GPL(dev_pm_qos_add_request);
329 * __dev_pm_qos_update_request - Modify an existing device PM QoS request.
330 * @req : PM QoS request to modify.
331 * @new_value: New value to request.
333 static int __dev_pm_qos_update_request(struct dev_pm_qos_request *req,
339 if (!req->dev->power.qos)
343 case DEV_PM_QOS_LATENCY:
344 curr_value = req->data.pnode.prio;
346 case DEV_PM_QOS_FLAGS:
347 curr_value = req->data.flr.flags;
353 if (curr_value != new_value)
354 ret = apply_constraint(req, PM_QOS_UPDATE_REQ, new_value);
360 * dev_pm_qos_update_request - modifies an existing qos request
361 * @req : handle to list element holding a dev_pm_qos request to use
362 * @new_value: defines the qos request
364 * Updates an existing dev PM qos request along with updating the
367 * Attempts are made to make this code callable on hot code paths.
369 * Returns 1 if the aggregated constraint value has changed,
370 * 0 if the aggregated constraint value has not changed,
371 * -EINVAL in case of wrong parameters, -ENODEV if the device has been
372 * removed from the system
374 * Callers should ensure that the target device is not RPM_SUSPENDED before
375 * using this function for requests of type DEV_PM_QOS_FLAGS.
377 int dev_pm_qos_update_request(struct dev_pm_qos_request *req, s32 new_value)
381 if (!req) /*guard against callers passing in null */
384 if (WARN(!dev_pm_qos_request_active(req),
385 "%s() called for unknown object\n", __func__))
388 mutex_lock(&dev_pm_qos_mtx);
389 ret = __dev_pm_qos_update_request(req, new_value);
390 mutex_unlock(&dev_pm_qos_mtx);
394 EXPORT_SYMBOL_GPL(dev_pm_qos_update_request);
397 * dev_pm_qos_remove_request - modifies an existing qos request
398 * @req: handle to request list element
400 * Will remove pm qos request from the list of constraints and
401 * recompute the current target value. Call this on slow code paths.
403 * Returns 1 if the aggregated constraint value has changed,
404 * 0 if the aggregated constraint value has not changed,
405 * -EINVAL in case of wrong parameters, -ENODEV if the device has been
406 * removed from the system
408 * Callers should ensure that the target device is not RPM_SUSPENDED before
409 * using this function for requests of type DEV_PM_QOS_FLAGS.
411 int dev_pm_qos_remove_request(struct dev_pm_qos_request *req)
415 if (!req) /*guard against callers passing in null */
418 if (WARN(!dev_pm_qos_request_active(req),
419 "%s() called for unknown object\n", __func__))
422 mutex_lock(&dev_pm_qos_mtx);
424 if (req->dev->power.qos) {
425 ret = apply_constraint(req, PM_QOS_REMOVE_REQ,
426 PM_QOS_DEFAULT_VALUE);
427 memset(req, 0, sizeof(*req));
429 /* Return if the device has been removed */
433 mutex_unlock(&dev_pm_qos_mtx);
436 EXPORT_SYMBOL_GPL(dev_pm_qos_remove_request);
439 * dev_pm_qos_add_notifier - sets notification entry for changes to target value
440 * of per-device PM QoS constraints
442 * @dev: target device for the constraint
443 * @notifier: notifier block managed by caller.
445 * Will register the notifier into a notification chain that gets called
446 * upon changes to the target value for the device.
448 * If the device's constraints object doesn't exist when this routine is called,
449 * it will be created (or error code will be returned if that fails).
451 int dev_pm_qos_add_notifier(struct device *dev, struct notifier_block *notifier)
455 mutex_lock(&dev_pm_qos_mtx);
458 ret = dev->power.power_state.event != PM_EVENT_INVALID ?
459 dev_pm_qos_constraints_allocate(dev) : -ENODEV;
462 ret = blocking_notifier_chain_register(
463 dev->power.qos->latency.notifiers, notifier);
465 mutex_unlock(&dev_pm_qos_mtx);
468 EXPORT_SYMBOL_GPL(dev_pm_qos_add_notifier);
471 * dev_pm_qos_remove_notifier - deletes notification for changes to target value
472 * of per-device PM QoS constraints
474 * @dev: target device for the constraint
475 * @notifier: notifier block to be removed.
477 * Will remove the notifier from the notification chain that gets called
478 * upon changes to the target value.
480 int dev_pm_qos_remove_notifier(struct device *dev,
481 struct notifier_block *notifier)
485 mutex_lock(&dev_pm_qos_mtx);
487 /* Silently return if the constraints object is not present. */
489 retval = blocking_notifier_chain_unregister(
490 dev->power.qos->latency.notifiers,
493 mutex_unlock(&dev_pm_qos_mtx);
496 EXPORT_SYMBOL_GPL(dev_pm_qos_remove_notifier);
499 * dev_pm_qos_add_global_notifier - sets notification entry for changes to
500 * target value of the PM QoS constraints for any device
502 * @notifier: notifier block managed by caller.
504 * Will register the notifier into a notification chain that gets called
505 * upon changes to the target value for any device.
507 int dev_pm_qos_add_global_notifier(struct notifier_block *notifier)
509 return blocking_notifier_chain_register(&dev_pm_notifiers, notifier);
511 EXPORT_SYMBOL_GPL(dev_pm_qos_add_global_notifier);
514 * dev_pm_qos_remove_global_notifier - deletes notification for changes to
515 * target value of PM QoS constraints for any device
517 * @notifier: notifier block to be removed.
519 * Will remove the notifier from the notification chain that gets called
520 * upon changes to the target value for any device.
522 int dev_pm_qos_remove_global_notifier(struct notifier_block *notifier)
524 return blocking_notifier_chain_unregister(&dev_pm_notifiers, notifier);
526 EXPORT_SYMBOL_GPL(dev_pm_qos_remove_global_notifier);
529 * dev_pm_qos_add_ancestor_request - Add PM QoS request for device's ancestor.
530 * @dev: Device whose ancestor to add the request for.
531 * @req: Pointer to the preallocated handle.
532 * @value: Constraint latency value.
534 int dev_pm_qos_add_ancestor_request(struct device *dev,
535 struct dev_pm_qos_request *req, s32 value)
537 struct device *ancestor = dev->parent;
540 while (ancestor && !ancestor->power.ignore_children)
541 ancestor = ancestor->parent;
544 error = dev_pm_qos_add_request(ancestor, req,
545 DEV_PM_QOS_LATENCY, value);
552 EXPORT_SYMBOL_GPL(dev_pm_qos_add_ancestor_request);
554 #ifdef CONFIG_PM_RUNTIME
555 static void __dev_pm_qos_drop_user_request(struct device *dev,
556 enum dev_pm_qos_req_type type)
559 case DEV_PM_QOS_LATENCY:
560 dev_pm_qos_remove_request(dev->power.qos->latency_req);
561 dev->power.qos->latency_req = NULL;
563 case DEV_PM_QOS_FLAGS:
564 dev_pm_qos_remove_request(dev->power.qos->flags_req);
565 dev->power.qos->flags_req = NULL;
571 * dev_pm_qos_expose_latency_limit - Expose PM QoS latency limit to user space.
572 * @dev: Device whose PM QoS latency limit is to be exposed to user space.
573 * @value: Initial value of the latency limit.
575 int dev_pm_qos_expose_latency_limit(struct device *dev, s32 value)
577 struct dev_pm_qos_request *req;
580 if (!device_is_registered(dev) || value < 0)
583 if (dev->power.qos && dev->power.qos->latency_req)
586 req = kzalloc(sizeof(*req), GFP_KERNEL);
590 ret = dev_pm_qos_add_request(dev, req, DEV_PM_QOS_LATENCY, value);
594 dev->power.qos->latency_req = req;
595 ret = pm_qos_sysfs_add_latency(dev);
597 __dev_pm_qos_drop_user_request(dev, DEV_PM_QOS_LATENCY);
601 EXPORT_SYMBOL_GPL(dev_pm_qos_expose_latency_limit);
604 * dev_pm_qos_hide_latency_limit - Hide PM QoS latency limit from user space.
605 * @dev: Device whose PM QoS latency limit is to be hidden from user space.
607 void dev_pm_qos_hide_latency_limit(struct device *dev)
609 if (dev->power.qos && dev->power.qos->latency_req) {
610 pm_qos_sysfs_remove_latency(dev);
611 __dev_pm_qos_drop_user_request(dev, DEV_PM_QOS_LATENCY);
614 EXPORT_SYMBOL_GPL(dev_pm_qos_hide_latency_limit);
617 * dev_pm_qos_expose_flags - Expose PM QoS flags of a device to user space.
618 * @dev: Device whose PM QoS flags are to be exposed to user space.
619 * @val: Initial values of the flags.
621 int dev_pm_qos_expose_flags(struct device *dev, s32 val)
623 struct dev_pm_qos_request *req;
626 if (!device_is_registered(dev))
629 if (dev->power.qos && dev->power.qos->flags_req)
632 req = kzalloc(sizeof(*req), GFP_KERNEL);
636 pm_runtime_get_sync(dev);
637 ret = dev_pm_qos_add_request(dev, req, DEV_PM_QOS_FLAGS, val);
641 dev->power.qos->flags_req = req;
642 ret = pm_qos_sysfs_add_flags(dev);
644 __dev_pm_qos_drop_user_request(dev, DEV_PM_QOS_FLAGS);
650 EXPORT_SYMBOL_GPL(dev_pm_qos_expose_flags);
653 * dev_pm_qos_hide_flags - Hide PM QoS flags of a device from user space.
654 * @dev: Device whose PM QoS flags are to be hidden from user space.
656 void dev_pm_qos_hide_flags(struct device *dev)
658 if (dev->power.qos && dev->power.qos->flags_req) {
659 pm_qos_sysfs_remove_flags(dev);
660 pm_runtime_get_sync(dev);
661 __dev_pm_qos_drop_user_request(dev, DEV_PM_QOS_FLAGS);
665 EXPORT_SYMBOL_GPL(dev_pm_qos_hide_flags);
668 * dev_pm_qos_update_flags - Update PM QoS flags request owned by user space.
669 * @dev: Device to update the PM QoS flags request for.
670 * @mask: Flags to set/clear.
671 * @set: Whether to set or clear the flags (true means set).
673 int dev_pm_qos_update_flags(struct device *dev, s32 mask, bool set)
678 if (!dev->power.qos || !dev->power.qos->flags_req)
681 pm_runtime_get_sync(dev);
682 mutex_lock(&dev_pm_qos_mtx);
684 value = dev_pm_qos_requested_flags(dev);
690 ret = __dev_pm_qos_update_request(dev->power.qos->flags_req, value);
692 mutex_unlock(&dev_pm_qos_mtx);
697 #endif /* CONFIG_PM_RUNTIME */