Commit 91ff4cb8 authored by Jean Pihet's avatar Jean Pihet Committed by Rafael J. Wysocki
Browse files

PM QoS: Implement per-device PM QoS constraints 



Implement the per-device PM QoS constraints by creating a device
PM QoS API, which calls the PM QoS constraints management core code.

The per-device latency constraints data strctures are stored
in the device dev_pm_info struct.

The device PM code calls the init and destroy of the per-device constraints
data struct in order to support the dynamic insertion and removal of the
devices in the system.

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.

Signed-off-by: default avatarJean Pihet <j-pihet@ti.com>
Reviewed-by: default avatarKevin Hilman <khilman@ti.com>
Signed-off-by: default avatarRafael J. Wysocki <rjw@sisk.pl>
parent abe98ec2

drivers/base/power/Makefile

+2 −2
Original line number Diff line number Diff line 
obj-$(CONFIG_PM)	+= sysfs.o generic_ops.o common.o

obj-$(CONFIG_PM)	+= sysfs.o generic_ops.o common.o qos.o

obj-$(CONFIG_PM_SLEEP)	+= main.o wakeup.o

obj-$(CONFIG_PM_RUNTIME)	+= runtime.o

obj-$(CONFIG_PM_TRACE_RTC)	+= trace.o

drivers/base/power/main.c

+3 −0
Original line number Diff line number Diff line
@@ -22,6 +22,7 @@ 
#include <linux/mutex.h>

#include <linux/pm.h>

#include <linux/pm_runtime.h>

#include <linux/pm_qos.h>

#include <linux/resume-trace.h>

#include <linux/interrupt.h>

#include <linux/sched.h>
@@ -97,6 +98,7 @@ void device_pm_add(struct device *dev) 
			dev_name(dev->parent));

	list_add_tail(&dev->power.entry, &dpm_list);

	mutex_unlock(&dpm_list_mtx);

	dev_pm_qos_constraints_init(dev);

}



/**
@@ -107,6 +109,7 @@ void device_pm_remove(struct device *dev) 
{

	pr_debug("PM: Removing info for %s:%s\n",

		 dev->bus ? dev->bus->name : "No Bus", dev_name(dev));

	dev_pm_qos_constraints_destroy(dev);

	complete_all(&dev->power.completion);

	mutex_lock(&dpm_list_mtx);

	list_del_init(&dev->power.entry);

drivers/base/power/qos.c

0 → 100644
+338 −0
Original line number Diff line number Diff line 
/*

 * Devices PM QoS constraints management

 *

 * Copyright (C) 2011 Texas Instruments, Inc.

 *

 * This program is free software; you can redistribute it and/or modify

 * it under the terms of the GNU General Public License version 2 as

 * published by the Free Software Foundation.

 *

 *

 * 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.

 *

 * Note about the per-device constraint data struct allocation:

 * . The per-device constraints data struct ptr is tored 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.

 * . The constraints_state variable from dev_pm_info tracks the data struct

 *    allocation state:

 *    DEV_PM_QOS_NO_DEVICE: No device present or device removed, no data

 *     allocated,

 *    DEV_PM_QOS_DEVICE_PRESENT: Device present, data not allocated and will be

 *     allocated at the first call to dev_pm_qos_add_request,

 *    DEV_PM_QOS_ALLOCATED: Device present, data allocated. The per-device

 *     PM QoS constraints framework is operational and constraints can be

 *     added, updated or removed using the dev_pm_qos_* API.

 *  . 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>





static DEFINE_MUTEX(dev_pm_qos_mtx);



/*

 * 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)

{

	struct pm_qos_constraints *c;

	struct blocking_notifier_head *n;



	c = kzalloc(sizeof(*c), GFP_KERNEL);

	if (!c)

		return -ENOMEM;



	n = kzalloc(sizeof(*n), GFP_KERNEL);

	if (!n) {

		kfree(c);

		return -ENOMEM;

	}

	BLOCKING_INIT_NOTIFIER_HEAD(n);



	dev->power.constraints = c;

	plist_head_init(&dev->power.constraints->list);

	dev->power.constraints->target_value = PM_QOS_DEV_LAT_DEFAULT_VALUE;

	dev->power.constraints->default_value =	PM_QOS_DEV_LAT_DEFAULT_VALUE;

	dev->power.constraints->type = PM_QOS_MIN;

	dev->power.constraints->notifiers = n;

	dev->power.constraints_state = DEV_PM_QOS_ALLOCATED;



	return 0;

}



/**

 * dev_pm_qos_constraints_init

 * @dev: target device

 *

 * Called from the device PM subsystem at device insertion

 */

void dev_pm_qos_constraints_init(struct device *dev)

{

	mutex_lock(&dev_pm_qos_mtx);

	dev->power.constraints_state = DEV_PM_QOS_DEVICE_PRESENT;

	mutex_unlock(&dev_pm_qos_mtx);

}



/**

 * dev_pm_qos_constraints_destroy

 * @dev: target device

 *

 * Called from the device PM subsystem at device removal

 */

void dev_pm_qos_constraints_destroy(struct device *dev)

{

	struct dev_pm_qos_request *req, *tmp;



	mutex_lock(&dev_pm_qos_mtx);



	if (dev->power.constraints_state == DEV_PM_QOS_ALLOCATED) {

		/* Flush the constraints list for the device */

		plist_for_each_entry_safe(req, tmp,

					  &dev->power.constraints->list,

					  node) {

			/*

			 * Update constraints list and call the per-device

			 * callbacks if needed

			 */

			pm_qos_update_target(req->dev->power.constraints,

					   &req->node, PM_QOS_REMOVE_REQ,

					   PM_QOS_DEFAULT_VALUE);

			memset(req, 0, sizeof(*req));

		}



		kfree(dev->power.constraints->notifiers);

		kfree(dev->power.constraints);

		dev->power.constraints = NULL;

	}

	dev->power.constraints_state = DEV_PM_QOS_NO_DEVICE;



	mutex_unlock(&dev_pm_qos_mtx);

}



/**

 * dev_pm_qos_add_request - inserts new qos request into the list

 * @dev: target device for the constraint

 * @req: pointer to a preallocated handle

 * @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, -ENODEV if the device has been

 * removed from the system

 */

int dev_pm_qos_add_request(struct device *dev, struct dev_pm_qos_request *req,

			    s32 value)

{

	int ret = 0;



	if (!dev || !req) /*guard against callers passing in null */

		return -EINVAL;



	if (dev_pm_qos_request_active(req)) {

		WARN(1, KERN_ERR "dev_pm_qos_add_request() called for already "

			"added request\n");

		return -EINVAL;

	}



	mutex_lock(&dev_pm_qos_mtx);

	req->dev = dev;



	/* Return if the device has been removed */

	if (req->dev->power.constraints_state == DEV_PM_QOS_NO_DEVICE) {

		ret = -ENODEV;

		goto out;

	}



	/*

	 * Allocate the constraints data on the first call to add_request,

	 * i.e. only if the data is not already allocated and if the device has

	 * not been removed

	 */

	if (dev->power.constraints_state == DEV_PM_QOS_DEVICE_PRESENT)

		ret = dev_pm_qos_constraints_allocate(dev);



	if (!ret)

		ret = pm_qos_update_target(dev->power.constraints, &req->node,

					   PM_QOS_ADD_REQ, value);



out:

	mutex_unlock(&dev_pm_qos_mtx);

	return ret;

}

EXPORT_SYMBOL_GPL(dev_pm_qos_add_request);



/**

 * 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

 */

int dev_pm_qos_update_request(struct dev_pm_qos_request *req,

			      s32 new_value)

{

	int ret = 0;



	if (!req) /*guard against callers passing in null */

		return -EINVAL;



	if (!dev_pm_qos_request_active(req)) {

		WARN(1, KERN_ERR "dev_pm_qos_update_request() called for "

			"unknown object\n");

		return -EINVAL;

	}



	mutex_lock(&dev_pm_qos_mtx);



	if (req->dev->power.constraints_state == DEV_PM_QOS_ALLOCATED) {

		if (new_value != req->node.prio)

			ret = pm_qos_update_target(req->dev->power.constraints,

						   &req->node,

						   PM_QOS_UPDATE_REQ,

						   new_value);

	} else {

		/* Return if the device has been removed */

		ret = -ENODEV;

	}



	mutex_unlock(&dev_pm_qos_mtx);

	return ret;

}

EXPORT_SYMBOL_GPL(dev_pm_qos_update_request);



/**

 * 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

 */

int dev_pm_qos_remove_request(struct dev_pm_qos_request *req)

{

	int ret = 0;



	if (!req) /*guard against callers passing in null */

		return -EINVAL;



	if (!dev_pm_qos_request_active(req)) {

		WARN(1, KERN_ERR "dev_pm_qos_remove_request() called for "

			"unknown object\n");

		return -EINVAL;

	}



	mutex_lock(&dev_pm_qos_mtx);



	if (req->dev->power.constraints_state == DEV_PM_QOS_ALLOCATED) {

		ret = pm_qos_update_target(req->dev->power.constraints,

					   &req->node, PM_QOS_REMOVE_REQ,

					   PM_QOS_DEFAULT_VALUE);

		memset(req, 0, sizeof(*req));

	} else {

		/* Return if the device has been removed */

		ret = -ENODEV;

	}



	mutex_unlock(&dev_pm_qos_mtx);

	return ret;

}

EXPORT_SYMBOL_GPL(dev_pm_qos_remove_request);



/**

 * 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.

 *

 * Will register the notifier into a notification chain that gets called

 * upon changes to the target value for the device.

 */

int dev_pm_qos_add_notifier(struct device *dev, struct notifier_block *notifier)

{

	int retval = 0;



	mutex_lock(&dev_pm_qos_mtx);



	/* Silently return if the device has been removed */

	if (dev->power.constraints_state != DEV_PM_QOS_ALLOCATED)

		goto out;



	retval = blocking_notifier_chain_register(

			dev->power.constraints->notifiers,

			notifier);



out:

	mutex_unlock(&dev_pm_qos_mtx);

	return retval;

}

EXPORT_SYMBOL_GPL(dev_pm_qos_add_notifier);



/**

 * 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.

 *

 * 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)

{

	int retval = 0;



	mutex_lock(&dev_pm_qos_mtx);



	/* Silently return if the device has been removed */

	if (dev->power.constraints_state != DEV_PM_QOS_ALLOCATED)

		goto out;



	retval = blocking_notifier_chain_unregister(

			dev->power.constraints->notifiers,

			notifier);



out:

	mutex_unlock(&dev_pm_qos_mtx);

	return retval;

}

EXPORT_SYMBOL_GPL(dev_pm_qos_remove_notifier);

include/linux/pm.h

+9 −0
Original line number Diff line number Diff line
@@ -419,6 +419,13 @@ enum rpm_request { 
	RPM_REQ_RESUME,

};



/* Per-device PM QoS constraints data struct state */

enum dev_pm_qos_state {

	DEV_PM_QOS_NO_DEVICE,		/* No device present */

	DEV_PM_QOS_DEVICE_PRESENT,	/* Device present, data not allocated */

	DEV_PM_QOS_ALLOCATED,		/* Device present, data allocated */

};



struct wakeup_source;



struct pm_domain_data {
@@ -480,6 +487,8 @@ struct dev_pm_info { 
	unsigned long		accounting_timestamp;

#endif

	struct pm_subsys_data	*subsys_data;  /* Owned by the subsystem. */

	struct pm_qos_constraints *constraints;

	enum dev_pm_qos_state	constraints_state;

};



extern void update_pm_runtime_accounting(struct device *dev);

include/linux/pm_qos.h

+42 −0
Original line number Diff line number Diff line
@@ -19,12 +19,18 @@ 
#define PM_QOS_CPU_DMA_LAT_DEFAULT_VALUE	(2000 * USEC_PER_SEC)

#define PM_QOS_NETWORK_LAT_DEFAULT_VALUE	(2000 * USEC_PER_SEC)

#define PM_QOS_NETWORK_THROUGHPUT_DEFAULT_VALUE	0

#define PM_QOS_DEV_LAT_DEFAULT_VALUE		0



struct pm_qos_request {

	struct plist_node node;

	int pm_qos_class;

};



struct dev_pm_qos_request {

	struct plist_node node;

	struct device *dev;

};



enum pm_qos_type {

	PM_QOS_UNITIALIZED,

	PM_QOS_MAX,		/* return the largest value */
@@ -51,6 +57,11 @@ enum pm_qos_req_action { 
	PM_QOS_REMOVE_REQ	/* Remove an existing request */

};



static inline int dev_pm_qos_request_active(struct dev_pm_qos_request *req)

{

	return req->dev != 0;

}



#ifdef CONFIG_PM

int pm_qos_update_target(struct pm_qos_constraints *c, struct plist_node *node,

			 enum pm_qos_req_action action, int value);
@@ -64,6 +75,17 @@ int pm_qos_request(int pm_qos_class); 
int pm_qos_add_notifier(int pm_qos_class, struct notifier_block *notifier);

int pm_qos_remove_notifier(int pm_qos_class, struct notifier_block *notifier);

int pm_qos_request_active(struct pm_qos_request *req);



int dev_pm_qos_add_request(struct device *dev, struct dev_pm_qos_request *req,

			   s32 value);

int dev_pm_qos_update_request(struct dev_pm_qos_request *req, s32 new_value);

int dev_pm_qos_remove_request(struct dev_pm_qos_request *req);

int dev_pm_qos_add_notifier(struct device *dev,

			    struct notifier_block *notifier);

int dev_pm_qos_remove_notifier(struct device *dev,

			       struct notifier_block *notifier);

void dev_pm_qos_constraints_init(struct device *dev);

void dev_pm_qos_constraints_destroy(struct device *dev);

#else

static inline int pm_qos_update_target(struct pm_qos_constraints *c,

				       struct plist_node *node,
@@ -89,6 +111,26 @@ static inline int pm_qos_remove_notifier(int pm_qos_class, 
			{ return 0; }

static inline int pm_qos_request_active(struct pm_qos_request *req)

			{ return 0; }



static inline int dev_pm_qos_add_request(struct device *dev,

					 struct dev_pm_qos_request *req,

					 s32 value)

			{ return 0; }

static inline int dev_pm_qos_update_request(struct dev_pm_qos_request *req,

					    s32 new_value)

			{ return 0; }

static inline int dev_pm_qos_remove_request(struct dev_pm_qos_request *req)

			{ return 0; }

static inline int dev_pm_qos_add_notifier(struct device *dev,

					  struct notifier_block *notifier)

			{ return 0; }

static inline int dev_pm_qos_remove_notifier(struct device *dev,

					     struct notifier_block *notifier)

			{ return 0; }

static inline void dev_pm_qos_constraints_init(struct device *dev)

			{ return; }

static inline void dev_pm_qos_constraints_destroy(struct device *dev)

			{ return; }

#endif



#endif

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