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
26 LIST_HEAD(dpm_active);
27 LIST_HEAD(dpm_off);
28 LIST_HEAD(dpm_off_irq);
29
30 DECLARE_MUTEX(dpm_sem);
31 DECLARE_MUTEX(dpm_list_sem);
32
33 /*
34 * PM Reference Counting.
35 */
36
37 static inline void device_pm_hold(struct device * dev)
38 {
39 if (dev)
40 atomic_inc(&dev->power.pm_users);
41 }
42
43 static 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
63 void 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 }
70 EXPORT_SYMBOL_GPL(device_pm_set_parent);
71
72 int 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
88 void 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
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