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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 | { | |
63 | struct pm_dev *dev = kmalloc(sizeof(struct pm_dev), GFP_KERNEL); | |
64 | if (dev) { | |
65 | memset(dev, 0, sizeof(*dev)); | |
66 | dev->type = type; | |
67 | dev->id = id; | |
68 | dev->callback = callback; | |
69 | ||
70 | down(&pm_devs_lock); | |
71 | list_add(&dev->entry, &pm_devs); | |
72 | up(&pm_devs_lock); | |
73 | } | |
74 | return dev; | |
75 | } | |
76 | ||
77 | /** | |
78 | * pm_unregister - unregister a device with power management | |
79 | * @dev: device to unregister | |
80 | * | |
81 | * Remove a device from the power management notification lists. The | |
82 | * dev passed must be a handle previously returned by pm_register. | |
83 | */ | |
84 | ||
85 | void pm_unregister(struct pm_dev *dev) | |
86 | { | |
87 | if (dev) { | |
88 | down(&pm_devs_lock); | |
89 | list_del(&dev->entry); | |
90 | up(&pm_devs_lock); | |
91 | ||
92 | kfree(dev); | |
93 | } | |
94 | } | |
95 | ||
96 | static void __pm_unregister(struct pm_dev *dev) | |
97 | { | |
98 | if (dev) { | |
99 | list_del(&dev->entry); | |
100 | kfree(dev); | |
101 | } | |
102 | } | |
103 | ||
104 | /** | |
105 | * pm_unregister_all - unregister all devices with matching callback | |
106 | * @callback: callback function pointer | |
107 | * | |
108 | * Unregister every device that would call the callback passed. This | |
109 | * is primarily meant as a helper function for loadable modules. It | |
110 | * enables a module to give up all its managed devices without keeping | |
111 | * its own private list. | |
112 | */ | |
113 | ||
114 | void pm_unregister_all(pm_callback callback) | |
115 | { | |
116 | struct list_head *entry; | |
117 | ||
118 | if (!callback) | |
119 | return; | |
120 | ||
121 | down(&pm_devs_lock); | |
122 | entry = pm_devs.next; | |
123 | while (entry != &pm_devs) { | |
124 | struct pm_dev *dev = list_entry(entry, struct pm_dev, entry); | |
125 | entry = entry->next; | |
126 | if (dev->callback == callback) | |
127 | __pm_unregister(dev); | |
128 | } | |
129 | up(&pm_devs_lock); | |
130 | } | |
131 | ||
132 | /** | |
133 | * pm_send - send request to a single device | |
134 | * @dev: device to send to | |
135 | * @rqst: power management request | |
136 | * @data: data for the callback | |
137 | * | |
138 | * Issue a power management request to a given device. The | |
139 | * %PM_SUSPEND and %PM_RESUME events are handled specially. The | |
140 | * data field must hold the intended next state. No call is made | |
141 | * if the state matches. | |
142 | * | |
143 | * BUGS: what stops two power management requests occurring in parallel | |
144 | * and conflicting. | |
145 | * | |
146 | * WARNING: Calling pm_send directly is not generally recommended, in | |
147 | * particular there is no locking against the pm_dev going away. The | |
148 | * caller must maintain all needed locking or have 'inside knowledge' | |
149 | * on the safety. Also remember that this function is not locked against | |
150 | * pm_unregister. This means that you must handle SMP races on callback | |
151 | * execution and unload yourself. | |
152 | */ | |
153 | ||
154 | static int pm_send(struct pm_dev *dev, pm_request_t rqst, void *data) | |
155 | { | |
156 | int status = 0; | |
157 | unsigned long prev_state, next_state; | |
158 | ||
159 | if (in_interrupt()) | |
160 | BUG(); | |
161 | ||
162 | switch (rqst) { | |
163 | case PM_SUSPEND: | |
164 | case PM_RESUME: | |
165 | prev_state = dev->state; | |
166 | next_state = (unsigned long) data; | |
167 | if (prev_state != next_state) { | |
168 | if (dev->callback) | |
169 | status = (*dev->callback)(dev, rqst, data); | |
170 | if (!status) { | |
171 | dev->state = next_state; | |
172 | dev->prev_state = prev_state; | |
173 | } | |
174 | } | |
175 | else { | |
176 | dev->prev_state = prev_state; | |
177 | } | |
178 | break; | |
179 | default: | |
180 | if (dev->callback) | |
181 | status = (*dev->callback)(dev, rqst, data); | |
182 | break; | |
183 | } | |
184 | return status; | |
185 | } | |
186 | ||
187 | /* | |
188 | * Undo incomplete request | |
189 | */ | |
190 | static void pm_undo_all(struct pm_dev *last) | |
191 | { | |
192 | struct list_head *entry = last->entry.prev; | |
193 | while (entry != &pm_devs) { | |
194 | struct pm_dev *dev = list_entry(entry, struct pm_dev, entry); | |
195 | if (dev->state != dev->prev_state) { | |
196 | /* previous state was zero (running) resume or | |
197 | * previous state was non-zero (suspended) suspend | |
198 | */ | |
199 | pm_request_t undo = (dev->prev_state | |
200 | ? PM_SUSPEND:PM_RESUME); | |
201 | pm_send(dev, undo, (void*) dev->prev_state); | |
202 | } | |
203 | entry = entry->prev; | |
204 | } | |
205 | } | |
206 | ||
207 | /** | |
208 | * pm_send_all - send request to all managed devices | |
209 | * @rqst: power management request | |
210 | * @data: data for the callback | |
211 | * | |
212 | * Issue a power management request to a all devices. The | |
213 | * %PM_SUSPEND events are handled specially. Any device is | |
214 | * permitted to fail a suspend by returning a non zero (error) | |
215 | * value from its callback function. If any device vetoes a | |
216 | * suspend request then all other devices that have suspended | |
217 | * during the processing of this request are restored to their | |
218 | * previous state. | |
219 | * | |
220 | * WARNING: This function takes the pm_devs_lock. The lock is not dropped until | |
221 | * the callbacks have completed. This prevents races against pm locking | |
222 | * functions, races against module unload pm_unregister code. It does | |
223 | * mean however that you must not issue pm_ functions within the callback | |
224 | * or you will deadlock and users will hate you. | |
225 | * | |
226 | * Zero is returned on success. If a suspend fails then the status | |
227 | * from the device that vetoes the suspend is returned. | |
228 | * | |
229 | * BUGS: what stops two power management requests occurring in parallel | |
230 | * and conflicting. | |
231 | */ | |
232 | ||
233 | int pm_send_all(pm_request_t rqst, void *data) | |
234 | { | |
235 | struct list_head *entry; | |
236 | ||
237 | down(&pm_devs_lock); | |
238 | entry = pm_devs.next; | |
239 | while (entry != &pm_devs) { | |
240 | struct pm_dev *dev = list_entry(entry, struct pm_dev, entry); | |
241 | if (dev->callback) { | |
242 | int status = pm_send(dev, rqst, data); | |
243 | if (status) { | |
244 | /* return devices to previous state on | |
245 | * failed suspend request | |
246 | */ | |
247 | if (rqst == PM_SUSPEND) | |
248 | pm_undo_all(dev); | |
249 | up(&pm_devs_lock); | |
250 | return status; | |
251 | } | |
252 | } | |
253 | entry = entry->next; | |
254 | } | |
255 | up(&pm_devs_lock); | |
256 | return 0; | |
257 | } | |
258 | ||
259 | EXPORT_SYMBOL(pm_register); | |
260 | EXPORT_SYMBOL(pm_unregister); | |
261 | EXPORT_SYMBOL(pm_unregister_all); | |
262 | EXPORT_SYMBOL(pm_send_all); | |
263 | EXPORT_SYMBOL(pm_active); | |
264 | ||
265 |