1 /*
2 * kernel/power/main.c - PM subsystem core functionality.
3 *
4 * Copyright (c) 2003 Patrick Mochel
5 * Copyright (c) 2003 Open Source Development Lab
6 *
7 * This file is released under the GPLv2
8 *
9 */
10
11 #include <linux/suspend.h>
12 #include <linux/kobject.h>
13 #include <linux/string.h>
14 #include <linux/delay.h>
15 #include <linux/errno.h>
16 #include <linux/init.h>
17 #include <linux/pm.h>
18
19
20 #include "power.h"
21
22 DECLARE_MUTEX(pm_sem);
23
24 struct pm_ops * pm_ops = NULL;
25 suspend_disk_method_t pm_disk_mode = PM_DISK_SHUTDOWN;
26
27 /**
28 * pm_set_ops - Set the global power method table.
29 * @ops: Pointer to ops structure.
30 */
31
32 void pm_set_ops(struct pm_ops * ops)
33 {
34 down(&pm_sem);
35 pm_ops = ops;
36 up(&pm_sem);
37 }
38
39
40 /**
41 * suspend_prepare - Do prep work before entering low-power state.
42 * @state: State we're entering.
43 *
44 * This is common code that is called for each state that we're
45 * entering. Allocate a console, stop all processes, then make sure
46 * the platform can enter the requested state.
47 */
48
49 static int suspend_prepare(suspend_state_t state)
50 {
51 int error = 0;
52
53 if (!pm_ops || !pm_ops->enter)
54 return -EPERM;
55
56 pm_prepare_console();
57
58 if (freeze_processes()) {
59 error = -EAGAIN;
60 goto Thaw;
61 }
62
63 if (pm_ops->prepare) {
64 if ((error = pm_ops->prepare(state)))
65 goto Thaw;
66 }
67
68 if ((error = device_suspend(PMSG_SUSPEND)))
69 goto Finish;
70 return 0;
71 Finish:
72 if (pm_ops->finish)
73 pm_ops->finish(state);
74 Thaw:
75 thaw_processes();
76 pm_restore_console();
77 return error;
78 }
79
80
81 static int suspend_enter(suspend_state_t state)
82 {
83 int error = 0;
84 unsigned long flags;
85
86 local_irq_save(flags);
87
88 if ((error = device_power_down(PMSG_SUSPEND)))
89 goto Done;
90 error = pm_ops->enter(state);
91 device_power_up();
92 Done:
93 local_irq_restore(flags);
94 return error;
95 }
96
97
98 /**
99 * suspend_finish - Do final work before exiting suspend sequence.
100 * @state: State we're coming out of.
101 *
102 * Call platform code to clean up, restart processes, and free the
103 * console that we've allocated. This is not called for suspend-to-disk.
104 */
105
106 static void suspend_finish(suspend_state_t state)
107 {
108 device_resume();
109 if (pm_ops && pm_ops->finish)
110 pm_ops->finish(state);
111 thaw_processes();
112 pm_restore_console();
113 }
114
115
116
117
118 char * pm_states[] = {
119 [PM_SUSPEND_STANDBY] = "standby",
120 [PM_SUSPEND_MEM] = "mem",
121 [PM_SUSPEND_DISK] = "disk",
122 NULL,
123 };
124
125
126 /**
127 * enter_state - Do common work of entering low-power state.
128 * @state: pm_state structure for state we're entering.
129 *
130 * Make sure we're the only ones trying to enter a sleep state. Fail
131 * if someone has beat us to it, since we don't want anything weird to
132 * happen when we wake up.
133 * Then, do the setup for suspend, enter the state, and cleaup (after
134 * we've woken up).
135 */
136
137 static int enter_state(suspend_state_t state)
138 {
139 int error;
140
141 if (down_trylock(&pm_sem))
142 return -EBUSY;
143
144 if (state == PM_SUSPEND_DISK) {
145 error = pm_suspend_disk();
146 goto Unlock;
147 }
148
149 /* Suspend is hard to get right on SMP. */
150 if (num_online_cpus() != 1) {
151 error = -EPERM;
152 goto Unlock;
153 }
154
155 pr_debug("PM: Preparing system for suspend\n");
156 if ((error = suspend_prepare(state)))
157 goto Unlock;
158
159 pr_debug("PM: Entering state.\n");
160 error = suspend_enter(state);
161
162 pr_debug("PM: Finishing up.\n");
163 suspend_finish(state);
164 Unlock:
165 up(&pm_sem);
166 return error;
167 }
168
169 /*
170 * This is main interface to the outside world. It needs to be
171 * called from process context.
172 */
173 int software_suspend(void)
174 {
175 return enter_state(PM_SUSPEND_DISK);
176 }
177
178
179 /**
180 * pm_suspend - Externally visible function for suspending system.
181 * @state: Enumarted value of state to enter.
182 *
183 * Determine whether or not value is within range, get state
184 * structure, and enter (above).
185 */
186
187 int pm_suspend(suspend_state_t state)
188 {
189 if (state > PM_SUSPEND_ON && state < PM_SUSPEND_MAX)
190 return enter_state(state);
191 return -EINVAL;
192 }
193
194
195
196 decl_subsys(power,NULL,NULL);
197
198
199 /**
200 * state - control system power state.
201 *
202 * show() returns what states are supported, which is hard-coded to
203 * 'standby' (Power-On Suspend), 'mem' (Suspend-to-RAM), and
204 * 'disk' (Suspend-to-Disk).
205 *
206 * store() accepts one of those strings, translates it into the
207 * proper enumerated value, and initiates a suspend transition.
208 */
209
210 static ssize_t state_show(struct subsystem * subsys, char * buf)
211 {
212 int i;
213 char * s = buf;
214
215 for (i = 0; i < PM_SUSPEND_MAX; i++) {
216 if (pm_states[i])
217 s += sprintf(s,"%s ",pm_states[i]);
218 }
219 s += sprintf(s,"\n");
220 return (s - buf);
221 }
222
223 static ssize_t state_store(struct subsystem * subsys, const char * buf, size_t n)
224 {
225 suspend_state_t state = PM_SUSPEND_STANDBY;
226 char ** s;
227 char *p;
228 int error;
229 int len;
230
231 p = memchr(buf, '\n', n);
232 len = p ? p - buf : n;
233
234 for (s = &pm_states[state]; state < PM_SUSPEND_MAX; s++, state++) {
235 if (*s && !strncmp(buf, *s, len))
236 break;
237 }
238 if (*s)
239 error = enter_state(state);
240 else
241 error = -EINVAL;
242 return error ? error : n;
243 }
244
245 power_attr(state);
246
247 static struct attribute * g[] = {
248 &state_attr.attr,
249 NULL,
250 };
251
252 static struct attribute_group attr_group = {
253 .attrs = g,
254 };
255
256
257 static int __init pm_init(void)
258 {
259 int error = subsystem_register(&power_subsys);
260 if (!error)
261 error = sysfs_create_group(&power_subsys.kset.kobj,&attr_group);
262 return error;
263 }
264
265 core_initcall(pm_init);
266
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