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/*
* drivers/base/power/main.c - Where the driver meets power management.
*
* Copyright (c) 2003 Patrick Mochel
* Copyright (c) 2003 Open Source Development Lab
*
* This file is released under the GPLv2
*
*
* The driver model core calls device_pm_add() when a device is registered.
* This will intialize the embedded device_pm_info object in the device
* and add it to the list of power-controlled devices. sysfs entries for
* controlling device power management will also be added.
*
* A different set of lists than the global subsystem list are used to
* keep track of power info because we use different lists to hold
* devices based on what stage of the power management process they
* are in. The power domain dependencies may also differ from the
* ancestral dependencies that the subsystem list maintains.
*/
#include <linux/config.h>
#include <linux/device.h>
#include "power.h"
LIST_HEAD(dpm_active);
LIST_HEAD(dpm_off);
LIST_HEAD(dpm_off_irq);
DECLARE_MUTEX(dpm_sem);
DECLARE_MUTEX(dpm_list_sem);
/*
* PM Reference Counting.
*/
static inline void device_pm_hold(struct device * dev)
{
if (dev)
atomic_inc(&dev->power.pm_users);
}
static inline void device_pm_release(struct device * dev)
{
if (dev)
atomic_dec(&dev->power.pm_users);
}
/**
* device_pm_set_parent - Specify power dependency.
* @dev: Device who needs power.
* @parent: Device that supplies power.
*
* This function is used to manually describe a power-dependency
* relationship. It may be used to specify a transversal relationship
* (where the power supplier is not the physical (or electrical)
* ancestor of a specific device.
* The effect of this is that the supplier will not be powered down
* before the power dependent.
*/
void device_pm_set_parent(struct device * dev, struct device * parent)
{
struct device * old_parent = dev->power.pm_parent;
device_pm_release(old_parent);
dev->power.pm_parent = parent;
device_pm_hold(parent);
}
EXPORT_SYMBOL_GPL(device_pm_set_parent);
int device_pm_add(struct device * dev)
{
int error;
pr_debug("PM: Adding info for %s:%s\n",
dev->bus ? dev->bus->name : "No Bus", dev->kobj.name);
atomic_set(&dev->power.pm_users, 0);
down(&dpm_list_sem);
list_add_tail(&dev->power.entry, &dpm_active);
device_pm_set_parent(dev, dev->parent);
if ((error = dpm_sysfs_add(dev)))
list_del(&dev->power.entry);
up(&dpm_list_sem);
return error;
}
void device_pm_remove(struct device * dev)
{
pr_debug("PM: Removing info for %s:%s\n",
dev->bus ? dev->bus->name : "No Bus", dev->kobj.name);
down(&dpm_list_sem);
dpm_sysfs_remove(dev);
device_pm_release(dev->power.pm_parent);
list_del_init(&dev->power.entry);
up(&dpm_list_sem);
}
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