xref: /linux/kernel/power/main.c (revision b0148a98ec5151fec82064d95f11eb9efbc628ea)
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/module.h>
12 #include <linux/suspend.h>
13 #include <linux/kobject.h>
14 #include <linux/string.h>
15 #include <linux/delay.h>
16 #include <linux/errno.h>
17 #include <linux/init.h>
18 #include <linux/pm.h>
19 #include <linux/console.h>
20 #include <linux/cpu.h>
21 #include <linux/resume-trace.h>
22 #include <linux/freezer.h>
23 
24 #include "power.h"
25 
26 /*This is just an arbitrary number */
27 #define FREE_PAGE_NUMBER (100)
28 
29 DEFINE_MUTEX(pm_mutex);
30 
31 struct pm_ops *pm_ops;
32 suspend_disk_method_t pm_disk_mode = PM_DISK_PLATFORM;
33 
34 /**
35  *	pm_set_ops - Set the global power method table.
36  *	@ops:	Pointer to ops structure.
37  */
38 
39 void pm_set_ops(struct pm_ops * ops)
40 {
41 	mutex_lock(&pm_mutex);
42 	pm_ops = ops;
43 	mutex_unlock(&pm_mutex);
44 }
45 
46 
47 /**
48  *	suspend_prepare - Do prep work before entering low-power state.
49  *	@state:		State we're entering.
50  *
51  *	This is common code that is called for each state that we're
52  *	entering. Allocate a console, stop all processes, then make sure
53  *	the platform can enter the requested state.
54  */
55 
56 static int suspend_prepare(suspend_state_t state)
57 {
58 	int error;
59 	unsigned int free_pages;
60 
61 	if (!pm_ops || !pm_ops->enter)
62 		return -EPERM;
63 
64 	pm_prepare_console();
65 
66 	error = disable_nonboot_cpus();
67 	if (error)
68 		goto Enable_cpu;
69 
70 	if (freeze_processes()) {
71 		error = -EAGAIN;
72 		goto Thaw;
73 	}
74 
75 	if ((free_pages = nr_free_pages()) < FREE_PAGE_NUMBER) {
76 		pr_debug("PM: free some memory\n");
77 		shrink_all_memory(FREE_PAGE_NUMBER - free_pages);
78 		if (nr_free_pages() < FREE_PAGE_NUMBER) {
79 			error = -ENOMEM;
80 			printk(KERN_ERR "PM: No enough memory\n");
81 			goto Thaw;
82 		}
83 	}
84 
85 	if (pm_ops->prepare) {
86 		if ((error = pm_ops->prepare(state)))
87 			goto Thaw;
88 	}
89 
90 	suspend_console();
91 	if ((error = device_suspend(PMSG_SUSPEND))) {
92 		printk(KERN_ERR "Some devices failed to suspend\n");
93 		goto Finish;
94 	}
95 	return 0;
96  Finish:
97 	if (pm_ops->finish)
98 		pm_ops->finish(state);
99  Thaw:
100 	thaw_processes();
101  Enable_cpu:
102 	enable_nonboot_cpus();
103 	pm_restore_console();
104 	return error;
105 }
106 
107 
108 int suspend_enter(suspend_state_t state)
109 {
110 	int error = 0;
111 	unsigned long flags;
112 
113 	local_irq_save(flags);
114 
115 	if ((error = device_power_down(PMSG_SUSPEND))) {
116 		printk(KERN_ERR "Some devices failed to power down\n");
117 		goto Done;
118 	}
119 	error = pm_ops->enter(state);
120 	device_power_up();
121  Done:
122 	local_irq_restore(flags);
123 	return error;
124 }
125 
126 
127 /**
128  *	suspend_finish - Do final work before exiting suspend sequence.
129  *	@state:		State we're coming out of.
130  *
131  *	Call platform code to clean up, restart processes, and free the
132  *	console that we've allocated. This is not called for suspend-to-disk.
133  */
134 
135 static void suspend_finish(suspend_state_t state)
136 {
137 	device_resume();
138 	resume_console();
139 	thaw_processes();
140 	enable_nonboot_cpus();
141 	if (pm_ops && pm_ops->finish)
142 		pm_ops->finish(state);
143 	pm_restore_console();
144 }
145 
146 
147 
148 
149 static const char * const pm_states[PM_SUSPEND_MAX] = {
150 	[PM_SUSPEND_STANDBY]	= "standby",
151 	[PM_SUSPEND_MEM]	= "mem",
152 #ifdef CONFIG_SOFTWARE_SUSPEND
153 	[PM_SUSPEND_DISK]	= "disk",
154 #endif
155 };
156 
157 static inline int valid_state(suspend_state_t state)
158 {
159 	/* Suspend-to-disk does not really need low-level support.
160 	 * It can work with reboot if needed. */
161 	if (state == PM_SUSPEND_DISK)
162 		return 1;
163 
164 	if (pm_ops && pm_ops->valid && !pm_ops->valid(state))
165 		return 0;
166 	return 1;
167 }
168 
169 
170 /**
171  *	enter_state - Do common work of entering low-power state.
172  *	@state:		pm_state structure for state we're entering.
173  *
174  *	Make sure we're the only ones trying to enter a sleep state. Fail
175  *	if someone has beat us to it, since we don't want anything weird to
176  *	happen when we wake up.
177  *	Then, do the setup for suspend, enter the state, and cleaup (after
178  *	we've woken up).
179  */
180 
181 static int enter_state(suspend_state_t state)
182 {
183 	int error;
184 
185 	if (!valid_state(state))
186 		return -ENODEV;
187 	if (!mutex_trylock(&pm_mutex))
188 		return -EBUSY;
189 
190 	if (state == PM_SUSPEND_DISK) {
191 		error = pm_suspend_disk();
192 		goto Unlock;
193 	}
194 
195 	pr_debug("PM: Preparing system for %s sleep\n", pm_states[state]);
196 	if ((error = suspend_prepare(state)))
197 		goto Unlock;
198 
199 	pr_debug("PM: Entering %s sleep\n", pm_states[state]);
200 	error = suspend_enter(state);
201 
202 	pr_debug("PM: Finishing wakeup.\n");
203 	suspend_finish(state);
204  Unlock:
205 	mutex_unlock(&pm_mutex);
206 	return error;
207 }
208 
209 /*
210  * This is main interface to the outside world. It needs to be
211  * called from process context.
212  */
213 int software_suspend(void)
214 {
215 	return enter_state(PM_SUSPEND_DISK);
216 }
217 
218 
219 /**
220  *	pm_suspend - Externally visible function for suspending system.
221  *	@state:		Enumarted value of state to enter.
222  *
223  *	Determine whether or not value is within range, get state
224  *	structure, and enter (above).
225  */
226 
227 int pm_suspend(suspend_state_t state)
228 {
229 	if (state > PM_SUSPEND_ON && state <= PM_SUSPEND_MAX)
230 		return enter_state(state);
231 	return -EINVAL;
232 }
233 
234 EXPORT_SYMBOL(pm_suspend);
235 
236 decl_subsys(power,NULL,NULL);
237 
238 
239 /**
240  *	state - control system power state.
241  *
242  *	show() returns what states are supported, which is hard-coded to
243  *	'standby' (Power-On Suspend), 'mem' (Suspend-to-RAM), and
244  *	'disk' (Suspend-to-Disk).
245  *
246  *	store() accepts one of those strings, translates it into the
247  *	proper enumerated value, and initiates a suspend transition.
248  */
249 
250 static ssize_t state_show(struct subsystem * subsys, char * buf)
251 {
252 	int i;
253 	char * s = buf;
254 
255 	for (i = 0; i < PM_SUSPEND_MAX; i++) {
256 		if (pm_states[i] && valid_state(i))
257 			s += sprintf(s,"%s ", pm_states[i]);
258 	}
259 	s += sprintf(s,"\n");
260 	return (s - buf);
261 }
262 
263 static ssize_t state_store(struct subsystem * subsys, const char * buf, size_t n)
264 {
265 	suspend_state_t state = PM_SUSPEND_STANDBY;
266 	const char * const *s;
267 	char *p;
268 	int error;
269 	int len;
270 
271 	p = memchr(buf, '\n', n);
272 	len = p ? p - buf : n;
273 
274 	for (s = &pm_states[state]; state < PM_SUSPEND_MAX; s++, state++) {
275 		if (*s && !strncmp(buf, *s, len))
276 			break;
277 	}
278 	if (state < PM_SUSPEND_MAX && *s)
279 		error = enter_state(state);
280 	else
281 		error = -EINVAL;
282 	return error ? error : n;
283 }
284 
285 power_attr(state);
286 
287 #ifdef CONFIG_PM_TRACE
288 int pm_trace_enabled;
289 
290 static ssize_t pm_trace_show(struct subsystem * subsys, char * buf)
291 {
292 	return sprintf(buf, "%d\n", pm_trace_enabled);
293 }
294 
295 static ssize_t
296 pm_trace_store(struct subsystem * subsys, const char * buf, size_t n)
297 {
298 	int val;
299 
300 	if (sscanf(buf, "%d", &val) == 1) {
301 		pm_trace_enabled = !!val;
302 		return n;
303 	}
304 	return -EINVAL;
305 }
306 
307 power_attr(pm_trace);
308 
309 static struct attribute * g[] = {
310 	&state_attr.attr,
311 	&pm_trace_attr.attr,
312 	NULL,
313 };
314 #else
315 static struct attribute * g[] = {
316 	&state_attr.attr,
317 	NULL,
318 };
319 #endif /* CONFIG_PM_TRACE */
320 
321 static struct attribute_group attr_group = {
322 	.attrs = g,
323 };
324 
325 
326 static int __init pm_init(void)
327 {
328 	int error = subsystem_register(&power_subsys);
329 	if (!error)
330 		error = sysfs_create_group(&power_subsys.kset.kobj,&attr_group);
331 	return error;
332 }
333 
334 core_initcall(pm_init);
335