// SPDX-License-Identifier: GPL-2.0 /* * Devices PM QoS constraints management * * Copyright (C) 2011 Texas Instruments, Inc. * * This module exposes the interface to kernel space for specifying * per-device PM QoS dependencies. It provides infrastructure for registration * of: * * Dependents on a QoS value : register requests * Watchers of QoS value : get notified when target QoS value changes * * This QoS design is best effort based. Dependents register their QoS needs. * Watchers register to keep track of the current QoS needs of the system. * Watchers can register a per-device notification callback using the * dev_pm_qos_*_notifier API. The notification chain data is stored in the * per-device constraint data struct. * * Note about the per-device constraint data struct allocation: * . The per-device constraints data struct ptr is stored into the device * dev_pm_info. * . To minimize the data usage by the per-device constraints, the data struct * is only allocated at the first call to dev_pm_qos_add_request. * . The data is later free'd when the device is removed from the system. * . A global mutex protects the constraints users from the data being * allocated and free'd. */ #include <linux/pm_qos.h> #include <linux/spinlock.h> #include <linux/slab.h> #include <linux/device.h> #include <linux/mutex.h> #include <linux/export.h> #include <linux/pm_runtime.h> #include <linux/err.h> #include <trace/events/power.h> #include "power.h" static DEFINE_MUTEX(dev_pm_qos_mtx); static DEFINE_MUTEX(dev_pm_qos_sysfs_mtx); /** * __dev_pm_qos_flags - Check PM QoS flags for a given device. * @dev: Device to check the PM QoS flags for. * @mask: Flags to check against. * * This routine must be called with dev->power.lock held. */ enum pm_qos_flags_status __dev_pm_qos_flags(struct device *dev, s32 mask) { … } /** * dev_pm_qos_flags - Check PM QoS flags for a given device (locked). * @dev: Device to check the PM QoS flags for. * @mask: Flags to check against. */ enum pm_qos_flags_status dev_pm_qos_flags(struct device *dev, s32 mask) { … } EXPORT_SYMBOL_GPL(…); /** * __dev_pm_qos_resume_latency - Get resume latency constraint for a given device. * @dev: Device to get the PM QoS constraint value for. * * This routine must be called with dev->power.lock held. */ s32 __dev_pm_qos_resume_latency(struct device *dev) { … } /** * dev_pm_qos_read_value - Get PM QoS constraint for a given device (locked). * @dev: Device to get the PM QoS constraint value for. * @type: QoS request type. */ s32 dev_pm_qos_read_value(struct device *dev, enum dev_pm_qos_req_type type) { … } /** * apply_constraint - Add/modify/remove device PM QoS request. * @req: Constraint request to apply * @action: Action to perform (add/update/remove). * @value: Value to assign to the QoS request. * * Internal function to update the constraints list using the PM QoS core * code and if needed call the per-device callbacks. */ static int apply_constraint(struct dev_pm_qos_request *req, enum pm_qos_req_action action, s32 value) { … } /* * dev_pm_qos_constraints_allocate * @dev: device to allocate data for * * Called at the first call to add_request, for constraint data allocation * Must be called with the dev_pm_qos_mtx mutex held */ static int dev_pm_qos_constraints_allocate(struct device *dev) { … } static void __dev_pm_qos_hide_latency_limit(struct device *dev); static void __dev_pm_qos_hide_flags(struct device *dev); /** * dev_pm_qos_constraints_destroy * @dev: target device * * Called from the device PM subsystem on device removal under device_pm_lock(). */ void dev_pm_qos_constraints_destroy(struct device *dev) { … } static bool dev_pm_qos_invalid_req_type(struct device *dev, enum dev_pm_qos_req_type type) { … } static int __dev_pm_qos_add_request(struct device *dev, struct dev_pm_qos_request *req, enum dev_pm_qos_req_type type, s32 value) { … } /** * dev_pm_qos_add_request - inserts new qos request into the list * @dev: target device for the constraint * @req: pointer to a preallocated handle * @type: type of the request * @value: defines the qos request * * This function inserts a new entry in the device constraints list of * requested qos performance characteristics. It recomputes the aggregate * QoS expectations of parameters and initializes the dev_pm_qos_request * handle. Caller needs to save this handle for later use in updates and * removal. * * Returns 1 if the aggregated constraint value has changed, * 0 if the aggregated constraint value has not changed, * -EINVAL in case of wrong parameters, -ENOMEM if there's not enough memory * to allocate for data structures, -ENODEV if the device has just been removed * from the system. * * Callers should ensure that the target device is not RPM_SUSPENDED before * using this function for requests of type DEV_PM_QOS_FLAGS. */ int dev_pm_qos_add_request(struct device *dev, struct dev_pm_qos_request *req, enum dev_pm_qos_req_type type, s32 value) { … } EXPORT_SYMBOL_GPL(…); /** * __dev_pm_qos_update_request - Modify an existing device PM QoS request. * @req : PM QoS request to modify. * @new_value: New value to request. */ static int __dev_pm_qos_update_request(struct dev_pm_qos_request *req, s32 new_value) { … } /** * dev_pm_qos_update_request - modifies an existing qos request * @req : handle to list element holding a dev_pm_qos request to use * @new_value: defines the qos request * * Updates an existing dev PM qos request along with updating the * target value. * * Attempts are made to make this code callable on hot code paths. * * Returns 1 if the aggregated constraint value has changed, * 0 if the aggregated constraint value has not changed, * -EINVAL in case of wrong parameters, -ENODEV if the device has been * removed from the system * * Callers should ensure that the target device is not RPM_SUSPENDED before * using this function for requests of type DEV_PM_QOS_FLAGS. */ int dev_pm_qos_update_request(struct dev_pm_qos_request *req, s32 new_value) { … } EXPORT_SYMBOL_GPL(…); static int __dev_pm_qos_remove_request(struct dev_pm_qos_request *req) { … } /** * dev_pm_qos_remove_request - modifies an existing qos request * @req: handle to request list element * * Will remove pm qos request from the list of constraints and * recompute the current target value. Call this on slow code paths. * * Returns 1 if the aggregated constraint value has changed, * 0 if the aggregated constraint value has not changed, * -EINVAL in case of wrong parameters, -ENODEV if the device has been * removed from the system * * Callers should ensure that the target device is not RPM_SUSPENDED before * using this function for requests of type DEV_PM_QOS_FLAGS. */ int dev_pm_qos_remove_request(struct dev_pm_qos_request *req) { … } EXPORT_SYMBOL_GPL(…); /** * dev_pm_qos_add_notifier - sets notification entry for changes to target value * of per-device PM QoS constraints * * @dev: target device for the constraint * @notifier: notifier block managed by caller. * @type: request type. * * Will register the notifier into a notification chain that gets called * upon changes to the target value for the device. * * If the device's constraints object doesn't exist when this routine is called, * it will be created (or error code will be returned if that fails). */ int dev_pm_qos_add_notifier(struct device *dev, struct notifier_block *notifier, enum dev_pm_qos_req_type type) { … } EXPORT_SYMBOL_GPL(…); /** * dev_pm_qos_remove_notifier - deletes notification for changes to target value * of per-device PM QoS constraints * * @dev: target device for the constraint * @notifier: notifier block to be removed. * @type: request type. * * Will remove the notifier from the notification chain that gets called * upon changes to the target value. */ int dev_pm_qos_remove_notifier(struct device *dev, struct notifier_block *notifier, enum dev_pm_qos_req_type type) { … } EXPORT_SYMBOL_GPL(…); /** * dev_pm_qos_add_ancestor_request - Add PM QoS request for device's ancestor. * @dev: Device whose ancestor to add the request for. * @req: Pointer to the preallocated handle. * @type: Type of the request. * @value: Constraint latency value. */ int dev_pm_qos_add_ancestor_request(struct device *dev, struct dev_pm_qos_request *req, enum dev_pm_qos_req_type type, s32 value) { … } EXPORT_SYMBOL_GPL(…); static void __dev_pm_qos_drop_user_request(struct device *dev, enum dev_pm_qos_req_type type) { … } static void dev_pm_qos_drop_user_request(struct device *dev, enum dev_pm_qos_req_type type) { … } /** * dev_pm_qos_expose_latency_limit - Expose PM QoS latency limit to user space. * @dev: Device whose PM QoS latency limit is to be exposed to user space. * @value: Initial value of the latency limit. */ int dev_pm_qos_expose_latency_limit(struct device *dev, s32 value) { … } EXPORT_SYMBOL_GPL(…); static void __dev_pm_qos_hide_latency_limit(struct device *dev) { … } /** * dev_pm_qos_hide_latency_limit - Hide PM QoS latency limit from user space. * @dev: Device whose PM QoS latency limit is to be hidden from user space. */ void dev_pm_qos_hide_latency_limit(struct device *dev) { … } EXPORT_SYMBOL_GPL(…); /** * dev_pm_qos_expose_flags - Expose PM QoS flags of a device to user space. * @dev: Device whose PM QoS flags are to be exposed to user space. * @val: Initial values of the flags. */ int dev_pm_qos_expose_flags(struct device *dev, s32 val) { … } EXPORT_SYMBOL_GPL(…); static void __dev_pm_qos_hide_flags(struct device *dev) { … } /** * dev_pm_qos_hide_flags - Hide PM QoS flags of a device from user space. * @dev: Device whose PM QoS flags are to be hidden from user space. */ void dev_pm_qos_hide_flags(struct device *dev) { … } EXPORT_SYMBOL_GPL(…); /** * dev_pm_qos_update_flags - Update PM QoS flags request owned by user space. * @dev: Device to update the PM QoS flags request for. * @mask: Flags to set/clear. * @set: Whether to set or clear the flags (true means set). */ int dev_pm_qos_update_flags(struct device *dev, s32 mask, bool set) { … } /** * dev_pm_qos_get_user_latency_tolerance - Get user space latency tolerance. * @dev: Device to obtain the user space latency tolerance for. */ s32 dev_pm_qos_get_user_latency_tolerance(struct device *dev) { … } /** * dev_pm_qos_update_user_latency_tolerance - Update user space latency tolerance. * @dev: Device to update the user space latency tolerance for. * @val: New user space latency tolerance for @dev (negative values disable). */ int dev_pm_qos_update_user_latency_tolerance(struct device *dev, s32 val) { … } EXPORT_SYMBOL_GPL(…); /** * dev_pm_qos_expose_latency_tolerance - Expose latency tolerance to userspace * @dev: Device whose latency tolerance to expose */ int dev_pm_qos_expose_latency_tolerance(struct device *dev) { … } EXPORT_SYMBOL_GPL(…); /** * dev_pm_qos_hide_latency_tolerance - Hide latency tolerance from userspace * @dev: Device whose latency tolerance to hide */ void dev_pm_qos_hide_latency_tolerance(struct device *dev) { … } EXPORT_SYMBOL_GPL(…);
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