tjh.dev
Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
1/*
2 * suspend.c - Functions for putting devices to sleep.
3 *
4 * Copyright (c) 2003 Patrick Mochel
5 * Copyright (c) 2003 Open Source Development Labs
6 *
7 * This file is released under the GPLv2
8 *
9 */
10
11#include <linux/device.h>
12#include "power.h"
13
14extern int sysdev_suspend(pm_message_t state);
15
16/*
17 * The entries in the dpm_active list are in a depth first order, simply
18 * because children are guaranteed to be discovered after parents, and
19 * are inserted at the back of the list on discovery.
20 *
21 * All list on the suspend path are done in reverse order, so we operate
22 * on the leaves of the device tree (or forests, depending on how you want
23 * to look at it ;) first. As nodes are removed from the back of the list,
24 * they are inserted into the front of their destintation lists.
25 *
26 * Things are the reverse on the resume path - iterations are done in
27 * forward order, and nodes are inserted at the back of their destination
28 * lists. This way, the ancestors will be accessed before their descendents.
29 */
30
31
32/**
33 * suspend_device - Save state of one device.
34 * @dev: Device.
35 * @state: Power state device is entering.
36 */
37
38int suspend_device(struct device * dev, pm_message_t state)
39{
40 int error = 0;
41
42 down(&dev->sem);
43 if (dev->power.power_state.event) {
44 dev_dbg(dev, "PM: suspend %d-->%d\n",
45 dev->power.power_state.event, state.event);
46 }
47 if (dev->power.pm_parent
48 && dev->power.pm_parent->power.power_state.event) {
49 dev_err(dev,
50 "PM: suspend %d->%d, parent %s already %d\n",
51 dev->power.power_state.event, state.event,
52 dev->power.pm_parent->bus_id,
53 dev->power.pm_parent->power.power_state.event);
54 }
55
56 dev->power.prev_state = dev->power.power_state;
57
58 if (dev->bus && dev->bus->suspend && !dev->power.power_state.event) {
59 dev_dbg(dev, "suspending\n");
60 error = dev->bus->suspend(dev, state);
61 }
62 up(&dev->sem);
63 return error;
64}
65
66
67/**
68 * device_suspend - Save state and stop all devices in system.
69 * @state: Power state to put each device in.
70 *
71 * Walk the dpm_active list, call ->suspend() for each device, and move
72 * it to dpm_off.
73 * Check the return value for each. If it returns 0, then we move the
74 * the device to the dpm_off list. If it returns -EAGAIN, we move it to
75 * the dpm_off_irq list. If we get a different error, try and back out.
76 *
77 * If we hit a failure with any of the devices, call device_resume()
78 * above to bring the suspended devices back to life.
79 *
80 */
81
82int device_suspend(pm_message_t state)
83{
84 int error = 0;
85
86 down(&dpm_sem);
87 down(&dpm_list_sem);
88 while (!list_empty(&dpm_active) && error == 0) {
89 struct list_head * entry = dpm_active.prev;
90 struct device * dev = to_device(entry);
91
92 get_device(dev);
93 up(&dpm_list_sem);
94
95 error = suspend_device(dev, state);
96
97 down(&dpm_list_sem);
98
99 /* Check if the device got removed */
100 if (!list_empty(&dev->power.entry)) {
101 /* Move it to the dpm_off or dpm_off_irq list */
102 if (!error) {
103 list_del(&dev->power.entry);
104 list_add(&dev->power.entry, &dpm_off);
105 } else if (error == -EAGAIN) {
106 list_del(&dev->power.entry);
107 list_add(&dev->power.entry, &dpm_off_irq);
108 error = 0;
109 }
110 }
111 if (error)
112 printk(KERN_ERR "Could not suspend device %s: "
113 "error %d\n", kobject_name(&dev->kobj), error);
114 put_device(dev);
115 }
116 up(&dpm_list_sem);
117 if (error) {
118 /* we failed... before resuming, bring back devices from
119 * dpm_off_irq list back to main dpm_off list, we do want
120 * to call resume() on them, in case they partially suspended
121 * despite returning -EAGAIN
122 */
123 while (!list_empty(&dpm_off_irq)) {
124 struct list_head * entry = dpm_off_irq.next;
125 list_del(entry);
126 list_add(entry, &dpm_off);
127 }
128 dpm_resume();
129 }
130 up(&dpm_sem);
131 return error;
132}
133
134EXPORT_SYMBOL_GPL(device_suspend);
135
136
137/**
138 * device_power_down - Shut down special devices.
139 * @state: Power state to enter.
140 *
141 * Walk the dpm_off_irq list, calling ->power_down() for each device that
142 * couldn't power down the device with interrupts enabled. When we're
143 * done, power down system devices.
144 */
145
146int device_power_down(pm_message_t state)
147{
148 int error = 0;
149 struct device * dev;
150
151 list_for_each_entry_reverse(dev, &dpm_off_irq, power.entry) {
152 if ((error = suspend_device(dev, state)))
153 break;
154 }
155 if (error)
156 goto Error;
157 if ((error = sysdev_suspend(state)))
158 goto Error;
159 Done:
160 return error;
161 Error:
162 printk(KERN_ERR "Could not power down device %s: "
163 "error %d\n", kobject_name(&dev->kobj), error);
164 dpm_power_up();
165 goto Done;
166}
167
168EXPORT_SYMBOL_GPL(device_power_down);
169