[PATCH] off-by-1 in kernel/power/main.c
[linux-2.6.git] / kernel / power / main.c
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 /*This is just an arbitrary number */
23 #define FREE_PAGE_NUMBER (100)
24
25 DECLARE_MUTEX(pm_sem);
26
27 struct pm_ops *pm_ops;
28 suspend_disk_method_t pm_disk_mode = PM_DISK_SHUTDOWN;
29
30 /**
31  *      pm_set_ops - Set the global power method table. 
32  *      @ops:   Pointer to ops structure.
33  */
34
35 void pm_set_ops(struct pm_ops * ops)
36 {
37         down(&pm_sem);
38         pm_ops = ops;
39         up(&pm_sem);
40 }
41
42
43 /**
44  *      suspend_prepare - Do prep work before entering low-power state.
45  *      @state:         State we're entering.
46  *
47  *      This is common code that is called for each state that we're 
48  *      entering. Allocate a console, stop all processes, then make sure
49  *      the platform can enter the requested state.
50  */
51
52 static int suspend_prepare(suspend_state_t state)
53 {
54         int error = 0;
55         unsigned int free_pages;
56
57         if (!pm_ops || !pm_ops->enter)
58                 return -EPERM;
59
60         pm_prepare_console();
61
62         disable_nonboot_cpus();
63
64         if (num_online_cpus() != 1) {
65                 error = -EPERM;
66                 goto Enable_cpu;
67         }
68
69         if (freeze_processes()) {
70                 error = -EAGAIN;
71                 goto Thaw;
72         }
73
74         if ((free_pages = nr_free_pages()) < FREE_PAGE_NUMBER) {
75                 pr_debug("PM: free some memory\n");
76                 shrink_all_memory(FREE_PAGE_NUMBER - free_pages);
77                 if (nr_free_pages() < FREE_PAGE_NUMBER) {
78                         error = -ENOMEM;
79                         printk(KERN_ERR "PM: No enough memory\n");
80                         goto Thaw;
81                 }
82         }
83
84         if (pm_ops->prepare) {
85                 if ((error = pm_ops->prepare(state)))
86                         goto Thaw;
87         }
88
89         if ((error = device_suspend(PMSG_SUSPEND))) {
90                 printk(KERN_ERR "Some devices failed to suspend\n");
91                 goto Finish;
92         }
93         return 0;
94  Finish:
95         if (pm_ops->finish)
96                 pm_ops->finish(state);
97  Thaw:
98         thaw_processes();
99  Enable_cpu:
100         enable_nonboot_cpus();
101         pm_restore_console();
102         return error;
103 }
104
105
106 int suspend_enter(suspend_state_t state)
107 {
108         int error = 0;
109         unsigned long flags;
110
111         local_irq_save(flags);
112
113         if ((error = device_power_down(PMSG_SUSPEND))) {
114                 printk(KERN_ERR "Some devices failed to power down\n");
115                 goto Done;
116         }
117         error = pm_ops->enter(state);
118         device_power_up();
119  Done:
120         local_irq_restore(flags);
121         return error;
122 }
123
124
125 /**
126  *      suspend_finish - Do final work before exiting suspend sequence.
127  *      @state:         State we're coming out of.
128  *
129  *      Call platform code to clean up, restart processes, and free the 
130  *      console that we've allocated. This is not called for suspend-to-disk.
131  */
132
133 static void suspend_finish(suspend_state_t state)
134 {
135         device_resume();
136         thaw_processes();
137         enable_nonboot_cpus();
138         if (pm_ops && pm_ops->finish)
139                 pm_ops->finish(state);
140         pm_restore_console();
141 }
142
143
144
145
146 static char *pm_states[PM_SUSPEND_MAX] = {
147         [PM_SUSPEND_STANDBY]    = "standby",
148         [PM_SUSPEND_MEM]        = "mem",
149 #ifdef CONFIG_SOFTWARE_SUSPEND
150         [PM_SUSPEND_DISK]       = "disk",
151 #endif
152 };
153
154 static inline int valid_state(suspend_state_t state)
155 {
156         /* Suspend-to-disk does not really need low-level support.
157          * It can work with reboot if needed. */
158         if (state == PM_SUSPEND_DISK)
159                 return 1;
160
161         if (pm_ops && pm_ops->valid && !pm_ops->valid(state))
162                 return 0;
163         return 1;
164 }
165
166
167 /**
168  *      enter_state - Do common work of entering low-power state.
169  *      @state:         pm_state structure for state we're entering.
170  *
171  *      Make sure we're the only ones trying to enter a sleep state. Fail
172  *      if someone has beat us to it, since we don't want anything weird to
173  *      happen when we wake up.
174  *      Then, do the setup for suspend, enter the state, and cleaup (after
175  *      we've woken up).
176  */
177
178 static int enter_state(suspend_state_t state)
179 {
180         int error;
181
182         if (!valid_state(state))
183                 return -ENODEV;
184         if (down_trylock(&pm_sem))
185                 return -EBUSY;
186
187         if (state == PM_SUSPEND_DISK) {
188                 error = pm_suspend_disk();
189                 goto Unlock;
190         }
191
192         pr_debug("PM: Preparing system for %s sleep\n", pm_states[state]);
193         if ((error = suspend_prepare(state)))
194                 goto Unlock;
195
196         pr_debug("PM: Entering %s sleep\n", pm_states[state]);
197         error = suspend_enter(state);
198
199         pr_debug("PM: Finishing wakeup.\n");
200         suspend_finish(state);
201  Unlock:
202         up(&pm_sem);
203         return error;
204 }
205
206 /*
207  * This is main interface to the outside world. It needs to be
208  * called from process context.
209  */
210 int software_suspend(void)
211 {
212         return enter_state(PM_SUSPEND_DISK);
213 }
214
215
216 /**
217  *      pm_suspend - Externally visible function for suspending system.
218  *      @state:         Enumarted value of state to enter.
219  *
220  *      Determine whether or not value is within range, get state 
221  *      structure, and enter (above).
222  */
223
224 int pm_suspend(suspend_state_t state)
225 {
226         if (state > PM_SUSPEND_ON && state <= PM_SUSPEND_MAX)
227                 return enter_state(state);
228         return -EINVAL;
229 }
230
231
232
233 decl_subsys(power,NULL,NULL);
234
235
236 /**
237  *      state - control system power state.
238  *
239  *      show() returns what states are supported, which is hard-coded to
240  *      'standby' (Power-On Suspend), 'mem' (Suspend-to-RAM), and
241  *      'disk' (Suspend-to-Disk).
242  *
243  *      store() accepts one of those strings, translates it into the 
244  *      proper enumerated value, and initiates a suspend transition.
245  */
246
247 static ssize_t state_show(struct subsystem * subsys, char * buf)
248 {
249         int i;
250         char * s = buf;
251
252         for (i = 0; i < PM_SUSPEND_MAX; i++) {
253                 if (pm_states[i] && valid_state(i))
254                         s += sprintf(s,"%s ", pm_states[i]);
255         }
256         s += sprintf(s,"\n");
257         return (s - buf);
258 }
259
260 static ssize_t state_store(struct subsystem * subsys, const char * buf, size_t n)
261 {
262         suspend_state_t state = PM_SUSPEND_STANDBY;
263         char ** s;
264         char *p;
265         int error;
266         int len;
267
268         p = memchr(buf, '\n', n);
269         len = p ? p - buf : n;
270
271         for (s = &pm_states[state]; state < PM_SUSPEND_MAX; s++, state++) {
272                 if (*s && !strncmp(buf, *s, len))
273                         break;
274         }
275         if (state < PM_SUSPEND_MAX && *s)
276                 error = enter_state(state);
277         else
278                 error = -EINVAL;
279         return error ? error : n;
280 }
281
282 power_attr(state);
283
284 static struct attribute * g[] = {
285         &state_attr.attr,
286         NULL,
287 };
288
289 static struct attribute_group attr_group = {
290         .attrs = g,
291 };
292
293
294 static int __init pm_init(void)
295 {
296         int error = subsystem_register(&power_subsys);
297         if (!error)
298                 error = sysfs_create_group(&power_subsys.kset.kobj,&attr_group);
299         return error;
300 }
301
302 core_initcall(pm_init);