1 /*
2 * drivers/base/power/runtime.c - Handling dynamic device power management.
3 *
4 * Copyright (c) 2003 Patrick Mochel
5 * Copyright (c) 2003 Open Source Development Lab
6 *
7 */
8
9 #include <linux/device.h>
10 #include "power.h"
11
12
13 static void runtime_resume(struct device * dev)
14 {
15 dev_dbg(dev, "resuming\n");
16 if (!dev->power.power_state)
17 return;
18 if (!resume_device(dev))
19 dev->power.power_state = 0;
20 }
21
22
23 /**
24 * dpm_runtime_resume - Power one device back on.
25 * @dev: Device.
26 *
27 * Bring one device back to the on state by first powering it
28 * on, then restoring state. We only operate on devices that aren't
29 * already on.
30 * FIXME: We need to handle devices that are in an unknown state.
31 */
32
33 void dpm_runtime_resume(struct device * dev)
34 {
35 down(&dpm_sem);
36 runtime_resume(dev);
37 up(&dpm_sem);
38 }
39
40
41 /**
42 * dpm_runtime_suspend - Put one device in low-power state.
43 * @dev: Device.
44 * @state: State to enter.
45 */
46
47 int dpm_runtime_suspend(struct device * dev, pm_message_t state)
48 {
49 int error = 0;
50
51 down(&dpm_sem);
52 if (dev->power.power_state == state)
53 goto Done;
54
55 if (dev->power.power_state)
56 runtime_resume(dev);
57
58 if (!(error = suspend_device(dev, state)))
59 dev->power.power_state = state;
60 Done:
61 up(&dpm_sem);
62 return error;
63 }
64
65
66 /**
67 * dpm_set_power_state - Update power_state field.
68 * @dev: Device.
69 * @state: Power state device is in.
70 *
71 * This is an update mechanism for drivers to notify the core
72 * what power state a device is in. Device probing code may not
73 * always be able to tell, but we need accurate information to
74 * work reliably.
75 */
76 void dpm_set_power_state(struct device * dev, pm_message_t state)
77 {
78 down(&dpm_sem);
79 dev->power.power_state = state;
80 up(&dpm_sem);
81 }
82
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