linux/drivers/base/power/qos.c

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/*
* 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.
* Watchers can register different types of notification callbacks:
* . 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.
* . a system-wide notification callback using the dev_pm_qos_*_global_notifier
* API. The notification chain data is stored in a static variable.
*
* 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.
* . 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 "power.h"
static DEFINE_MUTEX(dev_pm_qos_mtx);
static BLOCKING_NOTIFIER_HEAD(dev_pm_notifiers);
/**
* __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)
{
struct dev_pm_qos *qos = dev->power.qos;
struct pm_qos_flags *pqf;
s32 val;
if (!qos)
return PM_QOS_FLAGS_UNDEFINED;
pqf = &qos->flags;
if (list_empty(&pqf->list))
return PM_QOS_FLAGS_UNDEFINED;
val = pqf->effective_flags & mask;
if (val)
return (val == mask) ? PM_QOS_FLAGS_ALL : PM_QOS_FLAGS_SOME;
return PM_QOS_FLAGS_NONE;
}
/**
* 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)
{
unsigned long irqflags;
enum pm_qos_flags_status ret;
spin_lock_irqsave(&dev->power.lock, irqflags);
ret = __dev_pm_qos_flags(dev, mask);
spin_unlock_irqrestore(&dev->power.lock, irqflags);
return ret;
}
/**
PM / Runtime: Use device PM QoS constraints (v2) Make the runtime PM core use device PM QoS constraints to check if it is allowed to suspend a given device, so that an error code is returned if the device's own PM QoS constraint is negative or one of its children has already been suspended for too long. If this is not the case, the maximum estimated time the device is allowed to be suspended, computed as the minimum of the device's PM QoS constraint and the PM QoS constraints of its children (reduced by the difference between the current time and their suspend times) is stored in a new device's PM field power.max_time_suspended_ns that can be used by the device's subsystem or PM domain to decide whether or not to put the device into lower-power (and presumably higher-latency) states later (if the constraint is 0, which means "no constraint", the power.max_time_suspended_ns is set to -1). Additionally, the time of execution of the subsystem-level .runtime_suspend() callback for the device is recorded in the new power.suspend_time field for later use by the device's subsystem or PM domain along with power.max_time_suspended_ns (it also is used by the core code when the device's parent is suspended). Introduce a new helper function, pm_runtime_update_max_time_suspended(), allowing subsystems and PM domains (or device drivers) to update the power.max_time_suspended_ns field, for example after changing the power state of a suspended device. Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
2011-12-01 07:01:31 +08:00
* __dev_pm_qos_read_value - Get PM QoS 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_read_value(struct device *dev)
{
return dev->power.qos ? pm_qos_read_value(&dev->power.qos->latency) : 0;
PM / Runtime: Use device PM QoS constraints (v2) Make the runtime PM core use device PM QoS constraints to check if it is allowed to suspend a given device, so that an error code is returned if the device's own PM QoS constraint is negative or one of its children has already been suspended for too long. If this is not the case, the maximum estimated time the device is allowed to be suspended, computed as the minimum of the device's PM QoS constraint and the PM QoS constraints of its children (reduced by the difference between the current time and their suspend times) is stored in a new device's PM field power.max_time_suspended_ns that can be used by the device's subsystem or PM domain to decide whether or not to put the device into lower-power (and presumably higher-latency) states later (if the constraint is 0, which means "no constraint", the power.max_time_suspended_ns is set to -1). Additionally, the time of execution of the subsystem-level .runtime_suspend() callback for the device is recorded in the new power.suspend_time field for later use by the device's subsystem or PM domain along with power.max_time_suspended_ns (it also is used by the core code when the device's parent is suspended). Introduce a new helper function, pm_runtime_update_max_time_suspended(), allowing subsystems and PM domains (or device drivers) to update the power.max_time_suspended_ns field, for example after changing the power state of a suspended device. Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
2011-12-01 07:01:31 +08:00
}
/**
* dev_pm_qos_read_value - Get PM QoS constraint for a given device (locked).
* @dev: Device to get the PM QoS constraint value for.
*/
s32 dev_pm_qos_read_value(struct device *dev)
{
unsigned long flags;
PM / Runtime: Use device PM QoS constraints (v2) Make the runtime PM core use device PM QoS constraints to check if it is allowed to suspend a given device, so that an error code is returned if the device's own PM QoS constraint is negative or one of its children has already been suspended for too long. If this is not the case, the maximum estimated time the device is allowed to be suspended, computed as the minimum of the device's PM QoS constraint and the PM QoS constraints of its children (reduced by the difference between the current time and their suspend times) is stored in a new device's PM field power.max_time_suspended_ns that can be used by the device's subsystem or PM domain to decide whether or not to put the device into lower-power (and presumably higher-latency) states later (if the constraint is 0, which means "no constraint", the power.max_time_suspended_ns is set to -1). Additionally, the time of execution of the subsystem-level .runtime_suspend() callback for the device is recorded in the new power.suspend_time field for later use by the device's subsystem or PM domain along with power.max_time_suspended_ns (it also is used by the core code when the device's parent is suspended). Introduce a new helper function, pm_runtime_update_max_time_suspended(), allowing subsystems and PM domains (or device drivers) to update the power.max_time_suspended_ns field, for example after changing the power state of a suspended device. Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
2011-12-01 07:01:31 +08:00
s32 ret;
spin_lock_irqsave(&dev->power.lock, flags);
PM / Runtime: Use device PM QoS constraints (v2) Make the runtime PM core use device PM QoS constraints to check if it is allowed to suspend a given device, so that an error code is returned if the device's own PM QoS constraint is negative or one of its children has already been suspended for too long. If this is not the case, the maximum estimated time the device is allowed to be suspended, computed as the minimum of the device's PM QoS constraint and the PM QoS constraints of its children (reduced by the difference between the current time and their suspend times) is stored in a new device's PM field power.max_time_suspended_ns that can be used by the device's subsystem or PM domain to decide whether or not to put the device into lower-power (and presumably higher-latency) states later (if the constraint is 0, which means "no constraint", the power.max_time_suspended_ns is set to -1). Additionally, the time of execution of the subsystem-level .runtime_suspend() callback for the device is recorded in the new power.suspend_time field for later use by the device's subsystem or PM domain along with power.max_time_suspended_ns (it also is used by the core code when the device's parent is suspended). Introduce a new helper function, pm_runtime_update_max_time_suspended(), allowing subsystems and PM domains (or device drivers) to update the power.max_time_suspended_ns field, for example after changing the power state of a suspended device. Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
2011-12-01 07:01:31 +08:00
ret = __dev_pm_qos_read_value(dev);
spin_unlock_irqrestore(&dev->power.lock, flags);
return ret;
}
/**
* 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 and the global notification
* callbacks
*/
static int apply_constraint(struct dev_pm_qos_request *req,
enum pm_qos_req_action action, s32 value)
{
struct dev_pm_qos *qos = req->dev->power.qos;
int ret;
switch(req->type) {
case DEV_PM_QOS_LATENCY:
ret = pm_qos_update_target(&qos->latency, &req->data.pnode,
action, value);
if (ret) {
value = pm_qos_read_value(&qos->latency);
blocking_notifier_call_chain(&dev_pm_notifiers,
(unsigned long)value,
req);
}
break;
case DEV_PM_QOS_FLAGS:
ret = pm_qos_update_flags(&qos->flags, &req->data.flr,
action, value);
break;
default:
ret = -EINVAL;
}
return ret;
}
/*
* 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 dev_pm_qos *qos;
struct pm_qos_constraints *c;
struct blocking_notifier_head *n;
qos = kzalloc(sizeof(*qos), GFP_KERNEL);
if (!qos)
return -ENOMEM;
n = kzalloc(sizeof(*n), GFP_KERNEL);
if (!n) {
kfree(qos);
return -ENOMEM;
}
BLOCKING_INIT_NOTIFIER_HEAD(n);
c = &qos->latency;
plist_head_init(&c->list);
c->target_value = PM_QOS_DEV_LAT_DEFAULT_VALUE;
c->default_value = PM_QOS_DEV_LAT_DEFAULT_VALUE;
c->type = PM_QOS_MIN;
c->notifiers = n;
INIT_LIST_HEAD(&qos->flags.list);
spin_lock_irq(&dev->power.lock);
dev->power.qos = qos;
spin_unlock_irq(&dev->power.lock);
return 0;
}
/**
* dev_pm_qos_constraints_init - Initalize device's PM QoS constraints pointer.
* @dev: target device
*
* Called from the device PM subsystem during device insertion under
* device_pm_lock().
*/
void dev_pm_qos_constraints_init(struct device *dev)
{
mutex_lock(&dev_pm_qos_mtx);
dev->power.qos = NULL;
dev->power.power_state = PMSG_ON;
mutex_unlock(&dev_pm_qos_mtx);
}
/**
* 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)
{
struct dev_pm_qos *qos;
struct dev_pm_qos_request *req, *tmp;
struct pm_qos_constraints *c;
struct pm_qos_flags *f;
/*
* If the device's PM QoS resume latency limit or PM QoS flags have been
* exposed to user space, they have to be hidden at this point.
*/
dev_pm_qos_hide_latency_limit(dev);
dev_pm_qos_hide_flags(dev);
mutex_lock(&dev_pm_qos_mtx);
dev->power.power_state = PMSG_INVALID;
qos = dev->power.qos;
if (!qos)
goto out;
/* Flush the constraints lists for the device. */
c = &qos->latency;
plist_for_each_entry_safe(req, tmp, &c->list, data.pnode) {
/*
* Update constraints list and call the notification
* callbacks if needed
*/
apply_constraint(req, PM_QOS_REMOVE_REQ, PM_QOS_DEFAULT_VALUE);
memset(req, 0, sizeof(*req));
}
f = &qos->flags;
list_for_each_entry_safe(req, tmp, &f->list, data.flr.node) {
apply_constraint(req, PM_QOS_REMOVE_REQ, PM_QOS_DEFAULT_VALUE);
memset(req, 0, sizeof(*req));
}
spin_lock_irq(&dev->power.lock);
dev->power.qos = NULL;
spin_unlock_irq(&dev->power.lock);
kfree(c->notifiers);
kfree(qos);
out:
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
* @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)
{
int ret = 0;
if (!dev || !req) /*guard against callers passing in null */
return -EINVAL;
if (WARN(dev_pm_qos_request_active(req),
"%s() called for already added request\n", __func__))
return -EINVAL;
req->dev = dev;
mutex_lock(&dev_pm_qos_mtx);
if (!dev->power.qos) {
if (dev->power.power_state.event == PM_EVENT_INVALID) {
/* The device has been removed from the system. */
req->dev = NULL;
ret = -ENODEV;
goto out;
} else {
/*
* 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.
*/
ret = dev_pm_qos_constraints_allocate(dev);
}
}
if (!ret) {
req->type = type;
ret = apply_constraint(req, 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 - 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)
{
s32 curr_value;
int ret = 0;
if (!req->dev->power.qos)
return -ENODEV;
switch(req->type) {
case DEV_PM_QOS_LATENCY:
curr_value = req->data.pnode.prio;
break;
case DEV_PM_QOS_FLAGS:
curr_value = req->data.flr.flags;
break;
default:
return -EINVAL;
}
if (curr_value != new_value)
ret = apply_constraint(req, PM_QOS_UPDATE_REQ, new_value);
return ret;
}
/**
* 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)
{
int ret;
if (!req) /*guard against callers passing in null */
return -EINVAL;
if (WARN(!dev_pm_qos_request_active(req),
"%s() called for unknown object\n", __func__))
return -EINVAL;
mutex_lock(&dev_pm_qos_mtx);
ret = __dev_pm_qos_update_request(req, new_value);
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
*
* 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)
{
int ret = 0;
if (!req) /*guard against callers passing in null */
return -EINVAL;
if (WARN(!dev_pm_qos_request_active(req),
"%s() called for unknown object\n", __func__))
return -EINVAL;
mutex_lock(&dev_pm_qos_mtx);
if (req->dev->power.qos) {
ret = apply_constraint(req, 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.
*
* 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)
{
int ret = 0;
mutex_lock(&dev_pm_qos_mtx);
if (!dev->power.qos)
ret = dev->power.power_state.event != PM_EVENT_INVALID ?
dev_pm_qos_constraints_allocate(dev) : -ENODEV;
if (!ret)
ret = blocking_notifier_chain_register(
dev->power.qos->latency.notifiers, notifier);
mutex_unlock(&dev_pm_qos_mtx);
return ret;
}
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 constraints object is not present. */
if (dev->power.qos)
retval = blocking_notifier_chain_unregister(
dev->power.qos->latency.notifiers,
notifier);
mutex_unlock(&dev_pm_qos_mtx);
return retval;
}
EXPORT_SYMBOL_GPL(dev_pm_qos_remove_notifier);
/**
* dev_pm_qos_add_global_notifier - sets notification entry for changes to
* target value of the PM QoS constraints for any device
*
* @notifier: notifier block managed by caller.
*
* Will register the notifier into a notification chain that gets called
* upon changes to the target value for any device.
*/
int dev_pm_qos_add_global_notifier(struct notifier_block *notifier)
{
return blocking_notifier_chain_register(&dev_pm_notifiers, notifier);
}
EXPORT_SYMBOL_GPL(dev_pm_qos_add_global_notifier);
/**
* dev_pm_qos_remove_global_notifier - deletes notification for changes to
* target value of PM QoS constraints for any device
*
* @notifier: notifier block to be removed.
*
* Will remove the notifier from the notification chain that gets called
* upon changes to the target value for any device.
*/
int dev_pm_qos_remove_global_notifier(struct notifier_block *notifier)
{
return blocking_notifier_chain_unregister(&dev_pm_notifiers, notifier);
}
EXPORT_SYMBOL_GPL(dev_pm_qos_remove_global_notifier);
PM / QoS: Introduce dev_pm_qos_add_ancestor_request() Some devices, like the I2C controller on SH7372, are not necessary for providing power to their children or forwarding wakeup signals (and generally interrupts) from them. They are only needed by their children when there's some data to transfer, so they may be suspended for the majority of time and resumed on demand, when the children have data to send or receive. For this purpose, however, their power.ignore_children flags have to be set, or the PM core wouldn't allow them to be suspended while their children were active. Unfortunately, in some situations it may take too much time to resume such devices so that they can assist their children in transferring data. For example, if such a device belongs to a PM domain which goes to the "power off" state when that device is suspended, it may take too much time to restore power to the domain in response to the request from one of the device's children. In that case, if the parent's resume time is critical, the domain should stay in the "power on" state, although it still may be desirable to power manage the parent itself (e.g. by manipulating its clock). In general, device PM QoS may be used to address this problem. Namely, if the device's children added PM QoS latency constraints for it, they would be able to prevent it from being put into an overly deep low-power state. However, in some cases the devices needing to be serviced are not the immediate children of a "children-ignoring" device, but its grandchildren or even less direct descendants. In those cases, the entity wanting to add a PM QoS request for a given device's ancestor that ignores its children will have to find it in the first place, so introduce a new helper function that may be used to achieve that. This function, dev_pm_qos_add_ancestor_request(), will search for the first ancestor of the given device whose power.ignore_children flag is set and will add a device PM QoS latency request for that ancestor on behalf of the caller. The request added this way may be removed with the help of dev_pm_qos_remove_request() in the future, like any other device PM QoS latency request. Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
2011-12-23 08:23:52 +08:00
/**
* 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.
* @value: Constraint latency value.
*/
int dev_pm_qos_add_ancestor_request(struct device *dev,
struct dev_pm_qos_request *req, s32 value)
{
struct device *ancestor = dev->parent;
int ret = -ENODEV;
PM / QoS: Introduce dev_pm_qos_add_ancestor_request() Some devices, like the I2C controller on SH7372, are not necessary for providing power to their children or forwarding wakeup signals (and generally interrupts) from them. They are only needed by their children when there's some data to transfer, so they may be suspended for the majority of time and resumed on demand, when the children have data to send or receive. For this purpose, however, their power.ignore_children flags have to be set, or the PM core wouldn't allow them to be suspended while their children were active. Unfortunately, in some situations it may take too much time to resume such devices so that they can assist their children in transferring data. For example, if such a device belongs to a PM domain which goes to the "power off" state when that device is suspended, it may take too much time to restore power to the domain in response to the request from one of the device's children. In that case, if the parent's resume time is critical, the domain should stay in the "power on" state, although it still may be desirable to power manage the parent itself (e.g. by manipulating its clock). In general, device PM QoS may be used to address this problem. Namely, if the device's children added PM QoS latency constraints for it, they would be able to prevent it from being put into an overly deep low-power state. However, in some cases the devices needing to be serviced are not the immediate children of a "children-ignoring" device, but its grandchildren or even less direct descendants. In those cases, the entity wanting to add a PM QoS request for a given device's ancestor that ignores its children will have to find it in the first place, so introduce a new helper function that may be used to achieve that. This function, dev_pm_qos_add_ancestor_request(), will search for the first ancestor of the given device whose power.ignore_children flag is set and will add a device PM QoS latency request for that ancestor on behalf of the caller. The request added this way may be removed with the help of dev_pm_qos_remove_request() in the future, like any other device PM QoS latency request. Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
2011-12-23 08:23:52 +08:00
while (ancestor && !ancestor->power.ignore_children)
ancestor = ancestor->parent;
if (ancestor)
ret = dev_pm_qos_add_request(ancestor, req,
DEV_PM_QOS_LATENCY, value);
PM / QoS: Introduce dev_pm_qos_add_ancestor_request() Some devices, like the I2C controller on SH7372, are not necessary for providing power to their children or forwarding wakeup signals (and generally interrupts) from them. They are only needed by their children when there's some data to transfer, so they may be suspended for the majority of time and resumed on demand, when the children have data to send or receive. For this purpose, however, their power.ignore_children flags have to be set, or the PM core wouldn't allow them to be suspended while their children were active. Unfortunately, in some situations it may take too much time to resume such devices so that they can assist their children in transferring data. For example, if such a device belongs to a PM domain which goes to the "power off" state when that device is suspended, it may take too much time to restore power to the domain in response to the request from one of the device's children. In that case, if the parent's resume time is critical, the domain should stay in the "power on" state, although it still may be desirable to power manage the parent itself (e.g. by manipulating its clock). In general, device PM QoS may be used to address this problem. Namely, if the device's children added PM QoS latency constraints for it, they would be able to prevent it from being put into an overly deep low-power state. However, in some cases the devices needing to be serviced are not the immediate children of a "children-ignoring" device, but its grandchildren or even less direct descendants. In those cases, the entity wanting to add a PM QoS request for a given device's ancestor that ignores its children will have to find it in the first place, so introduce a new helper function that may be used to achieve that. This function, dev_pm_qos_add_ancestor_request(), will search for the first ancestor of the given device whose power.ignore_children flag is set and will add a device PM QoS latency request for that ancestor on behalf of the caller. The request added this way may be removed with the help of dev_pm_qos_remove_request() in the future, like any other device PM QoS latency request. Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
2011-12-23 08:23:52 +08:00
if (ret < 0)
PM / QoS: Introduce dev_pm_qos_add_ancestor_request() Some devices, like the I2C controller on SH7372, are not necessary for providing power to their children or forwarding wakeup signals (and generally interrupts) from them. They are only needed by their children when there's some data to transfer, so they may be suspended for the majority of time and resumed on demand, when the children have data to send or receive. For this purpose, however, their power.ignore_children flags have to be set, or the PM core wouldn't allow them to be suspended while their children were active. Unfortunately, in some situations it may take too much time to resume such devices so that they can assist their children in transferring data. For example, if such a device belongs to a PM domain which goes to the "power off" state when that device is suspended, it may take too much time to restore power to the domain in response to the request from one of the device's children. In that case, if the parent's resume time is critical, the domain should stay in the "power on" state, although it still may be desirable to power manage the parent itself (e.g. by manipulating its clock). In general, device PM QoS may be used to address this problem. Namely, if the device's children added PM QoS latency constraints for it, they would be able to prevent it from being put into an overly deep low-power state. However, in some cases the devices needing to be serviced are not the immediate children of a "children-ignoring" device, but its grandchildren or even less direct descendants. In those cases, the entity wanting to add a PM QoS request for a given device's ancestor that ignores its children will have to find it in the first place, so introduce a new helper function that may be used to achieve that. This function, dev_pm_qos_add_ancestor_request(), will search for the first ancestor of the given device whose power.ignore_children flag is set and will add a device PM QoS latency request for that ancestor on behalf of the caller. The request added this way may be removed with the help of dev_pm_qos_remove_request() in the future, like any other device PM QoS latency request. Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
2011-12-23 08:23:52 +08:00
req->dev = NULL;
return ret;
PM / QoS: Introduce dev_pm_qos_add_ancestor_request() Some devices, like the I2C controller on SH7372, are not necessary for providing power to their children or forwarding wakeup signals (and generally interrupts) from them. They are only needed by their children when there's some data to transfer, so they may be suspended for the majority of time and resumed on demand, when the children have data to send or receive. For this purpose, however, their power.ignore_children flags have to be set, or the PM core wouldn't allow them to be suspended while their children were active. Unfortunately, in some situations it may take too much time to resume such devices so that they can assist their children in transferring data. For example, if such a device belongs to a PM domain which goes to the "power off" state when that device is suspended, it may take too much time to restore power to the domain in response to the request from one of the device's children. In that case, if the parent's resume time is critical, the domain should stay in the "power on" state, although it still may be desirable to power manage the parent itself (e.g. by manipulating its clock). In general, device PM QoS may be used to address this problem. Namely, if the device's children added PM QoS latency constraints for it, they would be able to prevent it from being put into an overly deep low-power state. However, in some cases the devices needing to be serviced are not the immediate children of a "children-ignoring" device, but its grandchildren or even less direct descendants. In those cases, the entity wanting to add a PM QoS request for a given device's ancestor that ignores its children will have to find it in the first place, so introduce a new helper function that may be used to achieve that. This function, dev_pm_qos_add_ancestor_request(), will search for the first ancestor of the given device whose power.ignore_children flag is set and will add a device PM QoS latency request for that ancestor on behalf of the caller. The request added this way may be removed with the help of dev_pm_qos_remove_request() in the future, like any other device PM QoS latency request. Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
2011-12-23 08:23:52 +08:00
}
EXPORT_SYMBOL_GPL(dev_pm_qos_add_ancestor_request);
#ifdef CONFIG_PM_RUNTIME
static void __dev_pm_qos_drop_user_request(struct device *dev,
enum dev_pm_qos_req_type type)
{
switch(type) {
case DEV_PM_QOS_LATENCY:
dev_pm_qos_remove_request(dev->power.qos->latency_req);
dev->power.qos->latency_req = NULL;
break;
case DEV_PM_QOS_FLAGS:
dev_pm_qos_remove_request(dev->power.qos->flags_req);
dev->power.qos->flags_req = NULL;
break;
}
}
/**
* 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)
{
struct dev_pm_qos_request *req;
int ret;
if (!device_is_registered(dev) || value < 0)
return -EINVAL;
if (dev->power.qos && dev->power.qos->latency_req)
return -EEXIST;
req = kzalloc(sizeof(*req), GFP_KERNEL);
if (!req)
return -ENOMEM;
ret = dev_pm_qos_add_request(dev, req, DEV_PM_QOS_LATENCY, value);
if (ret < 0)
return ret;
dev->power.qos->latency_req = req;
ret = pm_qos_sysfs_add_latency(dev);
if (ret)
__dev_pm_qos_drop_user_request(dev, DEV_PM_QOS_LATENCY);
return ret;
}
EXPORT_SYMBOL_GPL(dev_pm_qos_expose_latency_limit);
/**
* 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)
{
if (dev->power.qos && dev->power.qos->latency_req) {
pm_qos_sysfs_remove_latency(dev);
__dev_pm_qos_drop_user_request(dev, DEV_PM_QOS_LATENCY);
}
}
EXPORT_SYMBOL_GPL(dev_pm_qos_hide_latency_limit);
/**
* 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)
{
struct dev_pm_qos_request *req;
int ret;
if (!device_is_registered(dev))
return -EINVAL;
if (dev->power.qos && dev->power.qos->flags_req)
return -EEXIST;
req = kzalloc(sizeof(*req), GFP_KERNEL);
if (!req)
return -ENOMEM;
pm_runtime_get_sync(dev);
ret = dev_pm_qos_add_request(dev, req, DEV_PM_QOS_FLAGS, val);
if (ret < 0)
goto fail;
dev->power.qos->flags_req = req;
ret = pm_qos_sysfs_add_flags(dev);
if (ret)
__dev_pm_qos_drop_user_request(dev, DEV_PM_QOS_FLAGS);
fail:
pm_runtime_put(dev);
return ret;
}
EXPORT_SYMBOL_GPL(dev_pm_qos_expose_flags);
/**
* 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)
{
if (dev->power.qos && dev->power.qos->flags_req) {
pm_qos_sysfs_remove_flags(dev);
pm_runtime_get_sync(dev);
__dev_pm_qos_drop_user_request(dev, DEV_PM_QOS_FLAGS);
pm_runtime_put(dev);
}
}
EXPORT_SYMBOL_GPL(dev_pm_qos_hide_flags);
/**
* 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)
{
s32 value;
int ret;
if (!dev->power.qos || !dev->power.qos->flags_req)
return -EINVAL;
pm_runtime_get_sync(dev);
mutex_lock(&dev_pm_qos_mtx);
value = dev_pm_qos_requested_flags(dev);
if (set)
value |= mask;
else
value &= ~mask;
ret = __dev_pm_qos_update_request(dev->power.qos->flags_req, value);
mutex_unlock(&dev_pm_qos_mtx);
pm_runtime_put(dev);
return ret;
}
#endif /* CONFIG_PM_RUNTIME */