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