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1da177e4 LT |
1 | /* |
2 | * pm.c - Power management interface | |
3 | * | |
4 | * Copyright (C) 2000 Andrew Henroid | |
5 | * | |
6 | * This program is free software; you can redistribute it and/or modify | |
7 | * it under the terms of the GNU General Public License as published by | |
8 | * the Free Software Foundation; either version 2 of the License, or | |
9 | * (at your option) any later version. | |
10 | * | |
11 | * This program is distributed in the hope that it will be useful, | |
12 | * but WITHOUT ANY WARRANTY; without even the implied warranty of | |
13 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
14 | * GNU General Public License for more details. | |
15 | * | |
16 | * You should have received a copy of the GNU General Public License | |
17 | * along with this program; if not, write to the Free Software | |
18 | * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA | |
19 | */ | |
20 | #include <linux/init.h> | |
21 | #include <linux/module.h> | |
22 | #include <linux/spinlock.h> | |
23 | #include <linux/mm.h> | |
24 | #include <linux/slab.h> | |
25 | #include <linux/pm.h> | |
bca73e4b | 26 | #include <linux/pm_legacy.h> |
1da177e4 | 27 | #include <linux/interrupt.h> |
97d1f15b | 28 | #include <linux/mutex.h> |
1da177e4 LT |
29 | |
30 | int pm_active; | |
31 | ||
32 | /* | |
33 | * Locking notes: | |
34 | * pm_devs_lock can be a semaphore providing pm ops are not called | |
35 | * from an interrupt handler (already a bad idea so no change here). Each | |
36 | * change must be protected so that an unlink of an entry doesn't clash | |
37 | * with a pm send - which is permitted to sleep in the current architecture | |
38 | * | |
39 | * Module unloads clashing with pm events now work out safely, the module | |
40 | * unload path will block until the event has been sent. It may well block | |
41 | * until a resume but that will be fine. | |
42 | */ | |
43 | ||
97d1f15b | 44 | static DEFINE_MUTEX(pm_devs_lock); |
1da177e4 LT |
45 | static LIST_HEAD(pm_devs); |
46 | ||
47 | /** | |
48 | * pm_register - register a device with power management | |
49 | * @type: device type | |
50 | * @id: device ID | |
51 | * @callback: callback function | |
52 | * | |
53 | * Add a device to the list of devices that wish to be notified about | |
54 | * power management events. A &pm_dev structure is returned on success, | |
55 | * on failure the return is %NULL. | |
56 | * | |
57 | * The callback function will be called in process context and | |
58 | * it may sleep. | |
59 | */ | |
60 | ||
61 | struct pm_dev *pm_register(pm_dev_t type, | |
62 | unsigned long id, | |
63 | pm_callback callback) | |
64 | { | |
dd392710 | 65 | struct pm_dev *dev = kzalloc(sizeof(struct pm_dev), GFP_KERNEL); |
1da177e4 | 66 | if (dev) { |
1da177e4 LT |
67 | dev->type = type; |
68 | dev->id = id; | |
69 | dev->callback = callback; | |
70 | ||
97d1f15b | 71 | mutex_lock(&pm_devs_lock); |
1da177e4 | 72 | list_add(&dev->entry, &pm_devs); |
97d1f15b | 73 | mutex_unlock(&pm_devs_lock); |
1da177e4 LT |
74 | } |
75 | return dev; | |
76 | } | |
77 | ||
1da177e4 LT |
78 | /** |
79 | * pm_send - send request to a single device | |
80 | * @dev: device to send to | |
81 | * @rqst: power management request | |
82 | * @data: data for the callback | |
83 | * | |
84 | * Issue a power management request to a given device. The | |
85 | * %PM_SUSPEND and %PM_RESUME events are handled specially. The | |
86 | * data field must hold the intended next state. No call is made | |
87 | * if the state matches. | |
88 | * | |
89 | * BUGS: what stops two power management requests occurring in parallel | |
90 | * and conflicting. | |
91 | * | |
92 | * WARNING: Calling pm_send directly is not generally recommended, in | |
93 | * particular there is no locking against the pm_dev going away. The | |
94 | * caller must maintain all needed locking or have 'inside knowledge' | |
95 | * on the safety. Also remember that this function is not locked against | |
96 | * pm_unregister. This means that you must handle SMP races on callback | |
97 | * execution and unload yourself. | |
98 | */ | |
99 | ||
100 | static int pm_send(struct pm_dev *dev, pm_request_t rqst, void *data) | |
101 | { | |
102 | int status = 0; | |
103 | unsigned long prev_state, next_state; | |
104 | ||
105 | if (in_interrupt()) | |
106 | BUG(); | |
107 | ||
108 | switch (rqst) { | |
109 | case PM_SUSPEND: | |
110 | case PM_RESUME: | |
111 | prev_state = dev->state; | |
112 | next_state = (unsigned long) data; | |
113 | if (prev_state != next_state) { | |
114 | if (dev->callback) | |
115 | status = (*dev->callback)(dev, rqst, data); | |
116 | if (!status) { | |
117 | dev->state = next_state; | |
118 | dev->prev_state = prev_state; | |
119 | } | |
120 | } | |
121 | else { | |
122 | dev->prev_state = prev_state; | |
123 | } | |
124 | break; | |
125 | default: | |
126 | if (dev->callback) | |
127 | status = (*dev->callback)(dev, rqst, data); | |
128 | break; | |
129 | } | |
130 | return status; | |
131 | } | |
132 | ||
133 | /* | |
134 | * Undo incomplete request | |
135 | */ | |
136 | static void pm_undo_all(struct pm_dev *last) | |
137 | { | |
138 | struct list_head *entry = last->entry.prev; | |
139 | while (entry != &pm_devs) { | |
140 | struct pm_dev *dev = list_entry(entry, struct pm_dev, entry); | |
141 | if (dev->state != dev->prev_state) { | |
142 | /* previous state was zero (running) resume or | |
143 | * previous state was non-zero (suspended) suspend | |
144 | */ | |
145 | pm_request_t undo = (dev->prev_state | |
146 | ? PM_SUSPEND:PM_RESUME); | |
147 | pm_send(dev, undo, (void*) dev->prev_state); | |
148 | } | |
149 | entry = entry->prev; | |
150 | } | |
151 | } | |
152 | ||
153 | /** | |
154 | * pm_send_all - send request to all managed devices | |
155 | * @rqst: power management request | |
156 | * @data: data for the callback | |
157 | * | |
158 | * Issue a power management request to a all devices. The | |
159 | * %PM_SUSPEND events are handled specially. Any device is | |
160 | * permitted to fail a suspend by returning a non zero (error) | |
161 | * value from its callback function. If any device vetoes a | |
162 | * suspend request then all other devices that have suspended | |
163 | * during the processing of this request are restored to their | |
164 | * previous state. | |
165 | * | |
166 | * WARNING: This function takes the pm_devs_lock. The lock is not dropped until | |
167 | * the callbacks have completed. This prevents races against pm locking | |
168 | * functions, races against module unload pm_unregister code. It does | |
169 | * mean however that you must not issue pm_ functions within the callback | |
170 | * or you will deadlock and users will hate you. | |
171 | * | |
172 | * Zero is returned on success. If a suspend fails then the status | |
173 | * from the device that vetoes the suspend is returned. | |
174 | * | |
175 | * BUGS: what stops two power management requests occurring in parallel | |
176 | * and conflicting. | |
177 | */ | |
178 | ||
179 | int pm_send_all(pm_request_t rqst, void *data) | |
180 | { | |
181 | struct list_head *entry; | |
182 | ||
97d1f15b | 183 | mutex_lock(&pm_devs_lock); |
1da177e4 LT |
184 | entry = pm_devs.next; |
185 | while (entry != &pm_devs) { | |
186 | struct pm_dev *dev = list_entry(entry, struct pm_dev, entry); | |
187 | if (dev->callback) { | |
188 | int status = pm_send(dev, rqst, data); | |
189 | if (status) { | |
190 | /* return devices to previous state on | |
191 | * failed suspend request | |
192 | */ | |
193 | if (rqst == PM_SUSPEND) | |
194 | pm_undo_all(dev); | |
97d1f15b | 195 | mutex_unlock(&pm_devs_lock); |
1da177e4 LT |
196 | return status; |
197 | } | |
198 | } | |
199 | entry = entry->next; | |
200 | } | |
97d1f15b | 201 | mutex_unlock(&pm_devs_lock); |
1da177e4 LT |
202 | return 0; |
203 | } | |
204 | ||
205 | EXPORT_SYMBOL(pm_register); | |
1da177e4 LT |
206 | EXPORT_SYMBOL(pm_send_all); |
207 | EXPORT_SYMBOL(pm_active); | |
208 | ||
209 |