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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> | |
26 | #include <linux/interrupt.h> | |
27 | ||
28 | int pm_active; | |
29 | ||
30 | /* | |
31 | * Locking notes: | |
32 | * pm_devs_lock can be a semaphore providing pm ops are not called | |
33 | * from an interrupt handler (already a bad idea so no change here). Each | |
34 | * change must be protected so that an unlink of an entry doesn't clash | |
35 | * with a pm send - which is permitted to sleep in the current architecture | |
36 | * | |
37 | * Module unloads clashing with pm events now work out safely, the module | |
38 | * unload path will block until the event has been sent. It may well block | |
39 | * until a resume but that will be fine. | |
40 | */ | |
41 | ||
42 | static DECLARE_MUTEX(pm_devs_lock); | |
43 | static LIST_HEAD(pm_devs); | |
44 | ||
45 | /** | |
46 | * pm_register - register a device with power management | |
47 | * @type: device type | |
48 | * @id: device ID | |
49 | * @callback: callback function | |
50 | * | |
51 | * Add a device to the list of devices that wish to be notified about | |
52 | * power management events. A &pm_dev structure is returned on success, | |
53 | * on failure the return is %NULL. | |
54 | * | |
55 | * The callback function will be called in process context and | |
56 | * it may sleep. | |
57 | */ | |
58 | ||
59 | struct pm_dev *pm_register(pm_dev_t type, | |
60 | unsigned long id, | |
61 | pm_callback callback) | |
62 | { | |
dd392710 | 63 | struct pm_dev *dev = kzalloc(sizeof(struct pm_dev), GFP_KERNEL); |
1da177e4 | 64 | if (dev) { |
1da177e4 LT |
65 | dev->type = type; |
66 | dev->id = id; | |
67 | dev->callback = callback; | |
68 | ||
69 | down(&pm_devs_lock); | |
70 | list_add(&dev->entry, &pm_devs); | |
71 | up(&pm_devs_lock); | |
72 | } | |
73 | return dev; | |
74 | } | |
75 | ||
76 | /** | |
77 | * pm_unregister - unregister a device with power management | |
78 | * @dev: device to unregister | |
79 | * | |
80 | * Remove a device from the power management notification lists. The | |
81 | * dev passed must be a handle previously returned by pm_register. | |
82 | */ | |
83 | ||
84 | void pm_unregister(struct pm_dev *dev) | |
85 | { | |
86 | if (dev) { | |
87 | down(&pm_devs_lock); | |
88 | list_del(&dev->entry); | |
89 | up(&pm_devs_lock); | |
90 | ||
91 | kfree(dev); | |
92 | } | |
93 | } | |
94 | ||
95 | static void __pm_unregister(struct pm_dev *dev) | |
96 | { | |
97 | if (dev) { | |
98 | list_del(&dev->entry); | |
99 | kfree(dev); | |
100 | } | |
101 | } | |
102 | ||
103 | /** | |
104 | * pm_unregister_all - unregister all devices with matching callback | |
105 | * @callback: callback function pointer | |
106 | * | |
107 | * Unregister every device that would call the callback passed. This | |
108 | * is primarily meant as a helper function for loadable modules. It | |
109 | * enables a module to give up all its managed devices without keeping | |
110 | * its own private list. | |
111 | */ | |
112 | ||
113 | void pm_unregister_all(pm_callback callback) | |
114 | { | |
115 | struct list_head *entry; | |
116 | ||
117 | if (!callback) | |
118 | return; | |
119 | ||
120 | down(&pm_devs_lock); | |
121 | entry = pm_devs.next; | |
122 | while (entry != &pm_devs) { | |
123 | struct pm_dev *dev = list_entry(entry, struct pm_dev, entry); | |
124 | entry = entry->next; | |
125 | if (dev->callback == callback) | |
126 | __pm_unregister(dev); | |
127 | } | |
128 | up(&pm_devs_lock); | |
129 | } | |
130 | ||
131 | /** | |
132 | * pm_send - send request to a single device | |
133 | * @dev: device to send to | |
134 | * @rqst: power management request | |
135 | * @data: data for the callback | |
136 | * | |
137 | * Issue a power management request to a given device. The | |
138 | * %PM_SUSPEND and %PM_RESUME events are handled specially. The | |
139 | * data field must hold the intended next state. No call is made | |
140 | * if the state matches. | |
141 | * | |
142 | * BUGS: what stops two power management requests occurring in parallel | |
143 | * and conflicting. | |
144 | * | |
145 | * WARNING: Calling pm_send directly is not generally recommended, in | |
146 | * particular there is no locking against the pm_dev going away. The | |
147 | * caller must maintain all needed locking or have 'inside knowledge' | |
148 | * on the safety. Also remember that this function is not locked against | |
149 | * pm_unregister. This means that you must handle SMP races on callback | |
150 | * execution and unload yourself. | |
151 | */ | |
152 | ||
153 | static int pm_send(struct pm_dev *dev, pm_request_t rqst, void *data) | |
154 | { | |
155 | int status = 0; | |
156 | unsigned long prev_state, next_state; | |
157 | ||
158 | if (in_interrupt()) | |
159 | BUG(); | |
160 | ||
161 | switch (rqst) { | |
162 | case PM_SUSPEND: | |
163 | case PM_RESUME: | |
164 | prev_state = dev->state; | |
165 | next_state = (unsigned long) data; | |
166 | if (prev_state != next_state) { | |
167 | if (dev->callback) | |
168 | status = (*dev->callback)(dev, rqst, data); | |
169 | if (!status) { | |
170 | dev->state = next_state; | |
171 | dev->prev_state = prev_state; | |
172 | } | |
173 | } | |
174 | else { | |
175 | dev->prev_state = prev_state; | |
176 | } | |
177 | break; | |
178 | default: | |
179 | if (dev->callback) | |
180 | status = (*dev->callback)(dev, rqst, data); | |
181 | break; | |
182 | } | |
183 | return status; | |
184 | } | |
185 | ||
186 | /* | |
187 | * Undo incomplete request | |
188 | */ | |
189 | static void pm_undo_all(struct pm_dev *last) | |
190 | { | |
191 | struct list_head *entry = last->entry.prev; | |
192 | while (entry != &pm_devs) { | |
193 | struct pm_dev *dev = list_entry(entry, struct pm_dev, entry); | |
194 | if (dev->state != dev->prev_state) { | |
195 | /* previous state was zero (running) resume or | |
196 | * previous state was non-zero (suspended) suspend | |
197 | */ | |
198 | pm_request_t undo = (dev->prev_state | |
199 | ? PM_SUSPEND:PM_RESUME); | |
200 | pm_send(dev, undo, (void*) dev->prev_state); | |
201 | } | |
202 | entry = entry->prev; | |
203 | } | |
204 | } | |
205 | ||
206 | /** | |
207 | * pm_send_all - send request to all managed devices | |
208 | * @rqst: power management request | |
209 | * @data: data for the callback | |
210 | * | |
211 | * Issue a power management request to a all devices. The | |
212 | * %PM_SUSPEND events are handled specially. Any device is | |
213 | * permitted to fail a suspend by returning a non zero (error) | |
214 | * value from its callback function. If any device vetoes a | |
215 | * suspend request then all other devices that have suspended | |
216 | * during the processing of this request are restored to their | |
217 | * previous state. | |
218 | * | |
219 | * WARNING: This function takes the pm_devs_lock. The lock is not dropped until | |
220 | * the callbacks have completed. This prevents races against pm locking | |
221 | * functions, races against module unload pm_unregister code. It does | |
222 | * mean however that you must not issue pm_ functions within the callback | |
223 | * or you will deadlock and users will hate you. | |
224 | * | |
225 | * Zero is returned on success. If a suspend fails then the status | |
226 | * from the device that vetoes the suspend is returned. | |
227 | * | |
228 | * BUGS: what stops two power management requests occurring in parallel | |
229 | * and conflicting. | |
230 | */ | |
231 | ||
232 | int pm_send_all(pm_request_t rqst, void *data) | |
233 | { | |
234 | struct list_head *entry; | |
235 | ||
236 | down(&pm_devs_lock); | |
237 | entry = pm_devs.next; | |
238 | while (entry != &pm_devs) { | |
239 | struct pm_dev *dev = list_entry(entry, struct pm_dev, entry); | |
240 | if (dev->callback) { | |
241 | int status = pm_send(dev, rqst, data); | |
242 | if (status) { | |
243 | /* return devices to previous state on | |
244 | * failed suspend request | |
245 | */ | |
246 | if (rqst == PM_SUSPEND) | |
247 | pm_undo_all(dev); | |
248 | up(&pm_devs_lock); | |
249 | return status; | |
250 | } | |
251 | } | |
252 | entry = entry->next; | |
253 | } | |
254 | up(&pm_devs_lock); | |
255 | return 0; | |
256 | } | |
257 | ||
258 | EXPORT_SYMBOL(pm_register); | |
259 | EXPORT_SYMBOL(pm_unregister); | |
260 | EXPORT_SYMBOL(pm_unregister_all); | |
261 | EXPORT_SYMBOL(pm_send_all); | |
262 | EXPORT_SYMBOL(pm_active); | |
263 | ||
264 |