main.c revision 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 
1/*
2 * drivers/base/power/main.c - Where the driver meets power management.
3 *
4 * Copyright (c) 2003 Patrick Mochel
5 * Copyright (c) 2003 Open Source Development Lab
6 *
7 * This file is released under the GPLv2
8 *
9 *
10 * The driver model core calls device_pm_add() when a device is registered.
11 * This will intialize the embedded device_pm_info object in the device
12 * and add it to the list of power-controlled devices. sysfs entries for
13 * controlling device power management will also be added.
14 *
15 * A different set of lists than the global subsystem list are used to
16 * keep track of power info because we use different lists to hold
17 * devices based on what stage of the power management process they
18 * are in. The power domain dependencies may also differ from the
19 * ancestral dependencies that the subsystem list maintains.
20 */
21
22#include <linux/config.h>
23#include <linux/device.h>
24#include "power.h"
25
26LIST_HEAD(dpm_active);
27LIST_HEAD(dpm_off);
28LIST_HEAD(dpm_off_irq);
29
30DECLARE_MUTEX(dpm_sem);
31DECLARE_MUTEX(dpm_list_sem);
32
33/*
34 * PM Reference Counting.
35 */
36
37static inline void device_pm_hold(struct device * dev)
38{
39	if (dev)
40		atomic_inc(&dev->power.pm_users);
41}
42
43static inline void device_pm_release(struct device * dev)
44{
45	if (dev)
46		atomic_dec(&dev->power.pm_users);
47}
48
49
50/**
51 *	device_pm_set_parent - Specify power dependency.
52 *	@dev:		Device who needs power.
53 *	@parent:	Device that supplies power.
54 *
55 *	This function is used to manually describe a power-dependency
56 *	relationship. It may be used to specify a transversal relationship
57 *	(where the power supplier is not the physical (or electrical)
58 *	ancestor of a specific device.
59 *	The effect of this is that the supplier will not be powered down
60 *	before the power dependent.
61 */
62
63void device_pm_set_parent(struct device * dev, struct device * parent)
64{
65	struct device * old_parent = dev->power.pm_parent;
66	device_pm_release(old_parent);
67	dev->power.pm_parent = parent;
68	device_pm_hold(parent);
69}
70EXPORT_SYMBOL_GPL(device_pm_set_parent);
71
72int device_pm_add(struct device * dev)
73{
74	int error;
75
76	pr_debug("PM: Adding info for %s:%s\n",
77		 dev->bus ? dev->bus->name : "No Bus", dev->kobj.name);
78	atomic_set(&dev->power.pm_users, 0);
79	down(&dpm_list_sem);
80	list_add_tail(&dev->power.entry, &dpm_active);
81	device_pm_set_parent(dev, dev->parent);
82	if ((error = dpm_sysfs_add(dev)))
83		list_del(&dev->power.entry);
84	up(&dpm_list_sem);
85	return error;
86}
87
88void device_pm_remove(struct device * dev)
89{
90	pr_debug("PM: Removing info for %s:%s\n",
91		 dev->bus ? dev->bus->name : "No Bus", dev->kobj.name);
92	down(&dpm_list_sem);
93	dpm_sysfs_remove(dev);
94	device_pm_release(dev->power.pm_parent);
95	list_del_init(&dev->power.entry);
96	up(&dpm_list_sem);
97}
98
99
100