Merge branch 'master'
[linux-2.6] / drivers / base / power / suspend.c
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/vt_kern.h>
12 #include <linux/device.h>
13 #include "../base.h"
14 #include "power.h"
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
38 int 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  *      device_suspend - Save state and stop all devices in system.
68  *      @state:         Power state to put each device in.
69  *
70  *      Walk the dpm_active list, call ->suspend() for each device, and move
71  *      it to dpm_off.
72  *      Check the return value for each. If it returns 0, then we move the
73  *      the device to the dpm_off list. If it returns -EAGAIN, we move it to
74  *      the dpm_off_irq list. If we get a different error, try and back out.
75  *
76  *      If we hit a failure with any of the devices, call device_resume()
77  *      above to bring the suspended devices back to life.
78  *
79  */
80
81 int device_suspend(pm_message_t state)
82 {
83         int error = 0;
84
85         if (!is_console_suspend_safe())
86                 return -EINVAL;
87
88         down(&dpm_sem);
89         down(&dpm_list_sem);
90         while (!list_empty(&dpm_active) && error == 0) {
91                 struct list_head * entry = dpm_active.prev;
92                 struct device * dev = to_device(entry);
93
94                 get_device(dev);
95                 up(&dpm_list_sem);
96
97                 error = suspend_device(dev, state);
98
99                 down(&dpm_list_sem);
100
101                 /* Check if the device got removed */
102                 if (!list_empty(&dev->power.entry)) {
103                         /* Move it to the dpm_off or dpm_off_irq list */
104                         if (!error) {
105                                 list_del(&dev->power.entry);
106                                 list_add(&dev->power.entry, &dpm_off);
107                         } else if (error == -EAGAIN) {
108                                 list_del(&dev->power.entry);
109                                 list_add(&dev->power.entry, &dpm_off_irq);
110                                 error = 0;
111                         }
112                 }
113                 if (error)
114                         printk(KERN_ERR "Could not suspend device %s: "
115                                 "error %d\n", kobject_name(&dev->kobj), error);
116                 put_device(dev);
117         }
118         up(&dpm_list_sem);
119         if (error) {
120                 /* we failed... before resuming, bring back devices from
121                  * dpm_off_irq list back to main dpm_off list, we do want
122                  * to call resume() on them, in case they partially suspended
123                  * despite returning -EAGAIN
124                  */
125                 while (!list_empty(&dpm_off_irq)) {
126                         struct list_head * entry = dpm_off_irq.next;
127                         list_del(entry);
128                         list_add(entry, &dpm_off);
129                 }
130                 dpm_resume();
131         }
132         up(&dpm_sem);
133         return error;
134 }
135
136 EXPORT_SYMBOL_GPL(device_suspend);
137
138
139 /**
140  *      device_power_down - Shut down special devices.
141  *      @state:         Power state to enter.
142  *
143  *      Walk the dpm_off_irq list, calling ->power_down() for each device that
144  *      couldn't power down the device with interrupts enabled. When we're
145  *      done, power down system devices.
146  */
147
148 int device_power_down(pm_message_t state)
149 {
150         int error = 0;
151         struct device * dev;
152
153         list_for_each_entry_reverse(dev, &dpm_off_irq, power.entry) {
154                 if ((error = suspend_device(dev, state)))
155                         break;
156         }
157         if (error)
158                 goto Error;
159         if ((error = sysdev_suspend(state)))
160                 goto Error;
161  Done:
162         return error;
163  Error:
164         printk(KERN_ERR "Could not power down device %s: "
165                 "error %d\n", kobject_name(&dev->kobj), error);
166         dpm_power_up();
167         goto Done;
168 }
169
170 EXPORT_SYMBOL_GPL(device_power_down);
171