2 * kernel/power/main.c - PM subsystem core functionality.
4 * Copyright (c) 2003 Patrick Mochel
5 * Copyright (c) 2003 Open Source Development Lab
7 * This file is released under the GPLv2
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>
22 DECLARE_MUTEX(pm_sem);
24 struct pm_ops * pm_ops = NULL;
25 suspend_disk_method_t pm_disk_mode = PM_DISK_SHUTDOWN;
28 * pm_set_ops - Set the global power method table.
29 * @ops: Pointer to ops structure.
32 void pm_set_ops(struct pm_ops * ops)
41 * suspend_prepare - Do prep work before entering low-power state.
42 * @state: State we're entering.
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.
49 static int suspend_prepare(suspend_state_t state)
53 if (!pm_ops || !pm_ops->enter)
58 if (freeze_processes()) {
63 if (pm_ops->prepare) {
64 if ((error = pm_ops->prepare(state)))
68 if ((error = device_suspend(PMSG_SUSPEND)))
73 pm_ops->finish(state);
81 static int suspend_enter(suspend_state_t state)
86 local_irq_save(flags);
88 if ((error = device_power_down(PMSG_SUSPEND)))
90 error = pm_ops->enter(state);
93 local_irq_restore(flags);
99 * suspend_finish - Do final work before exiting suspend sequence.
100 * @state: State we're coming out of.
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.
106 static void suspend_finish(suspend_state_t state)
109 if (pm_ops && pm_ops->finish)
110 pm_ops->finish(state);
112 pm_restore_console();
118 char * pm_states[] = {
119 [PM_SUSPEND_STANDBY] = "standby",
120 [PM_SUSPEND_MEM] = "mem",
121 [PM_SUSPEND_DISK] = "disk",
127 * enter_state - Do common work of entering low-power state.
128 * @state: pm_state structure for state we're entering.
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
137 static int enter_state(suspend_state_t state)
141 if (down_trylock(&pm_sem))
144 if (state == PM_SUSPEND_DISK) {
145 error = pm_suspend_disk();
149 /* Suspend is hard to get right on SMP. */
150 if (num_online_cpus() != 1) {
155 pr_debug("PM: Preparing system for suspend\n");
156 if ((error = suspend_prepare(state)))
159 pr_debug("PM: Entering state.\n");
160 error = suspend_enter(state);
162 pr_debug("PM: Finishing up.\n");
163 suspend_finish(state);
170 * This is main interface to the outside world. It needs to be
171 * called from process context.
173 int software_suspend(void)
175 return enter_state(PM_SUSPEND_DISK);
180 * pm_suspend - Externally visible function for suspending system.
181 * @state: Enumarted value of state to enter.
183 * Determine whether or not value is within range, get state
184 * structure, and enter (above).
187 int pm_suspend(suspend_state_t state)
189 if (state > PM_SUSPEND_ON && state < PM_SUSPEND_MAX)
190 return enter_state(state);
196 decl_subsys(power,NULL,NULL);
200 * state - control system power state.
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).
206 * store() accepts one of those strings, translates it into the
207 * proper enumerated value, and initiates a suspend transition.
210 static ssize_t state_show(struct subsystem * subsys, char * buf)
215 for (i = 0; i < PM_SUSPEND_MAX; i++) {
217 s += sprintf(s,"%s ",pm_states[i]);
219 s += sprintf(s,"\n");
223 static ssize_t state_store(struct subsystem * subsys, const char * buf, size_t n)
225 suspend_state_t state = PM_SUSPEND_STANDBY;
231 p = memchr(buf, '\n', n);
232 len = p ? p - buf : n;
234 for (s = &pm_states[state]; state < PM_SUSPEND_MAX; s++, state++) {
235 if (*s && !strncmp(buf, *s, len))
239 error = enter_state(state);
242 return error ? error : n;
247 static struct attribute * g[] = {
252 static struct attribute_group attr_group = {
257 static int __init pm_init(void)
259 int error = subsystem_register(&power_subsys);
261 error = sysfs_create_group(&power_subsys.kset.kobj,&attr_group);
265 core_initcall(pm_init);