/* * kernel/power/main.c - PM subsystem core functionality. * * Copyright (c) 2003 Patrick Mochel * Copyright (c) 2003 Open Source Development Lab *  * This file is released under the GPLv2 * */ #include <linux/suspend.h>#include <linux/kobject.h>#include <linux/string.h>#include <linux/delay.h>#include <linux/errno.h>#include <linux/init.h>#include <linux/pm.h>  #include "power.h" /*This is just an arbitrary number */#define FREE_PAGE_NUMBER (100) DECLARE_MUTEX(pm_sem); struct pm_ops *pm_ops;suspend_disk_method_t pm_disk_mode = PM_DISK_SHUTDOWN; /** *	pm_set_ops - Set the global power method table.  *	@ops:	Pointer to ops structure. */ void pm_set_ops(struct pm_ops * ops){	down(&pm_sem);	pm_ops = ops;	up(&pm_sem);}  /** *	suspend_prepare - Do prep work before entering low-power state. *	@state:		State we're entering. * *	This is common code that is called for each state that we're  *	entering. Allocate a console, stop all processes, then make sure *	the platform can enter the requested state. */ static int suspend_prepare(suspend_state_t state){	int error = 0;	unsigned int free_pages; 	if (!pm_ops || !pm_ops->enter)		return -EPERM; 	pm_prepare_console(); 	disable_nonboot_cpus(); 	if (num_online_cpus() != 1) {		error = -EPERM;		goto Enable_cpu;	} 	if (freeze_processes()) {		error = -EAGAIN;		goto Thaw;	} 	if ((free_pages = nr_free_pages()) < FREE_PAGE_NUMBER) {		pr_debug("PM: free some memory\n");		shrink_all_memory(FREE_PAGE_NUMBER - free_pages);		if (nr_free_pages() < FREE_PAGE_NUMBER) {			error = -ENOMEM;			printk(KERN_ERR "PM: No enough memory\n");			goto Thaw;		}	} 	if (pm_ops->prepare) {		if ((error = pm_ops->prepare(state)))			goto Thaw;	} 	suspend_console();	if ((error = device_suspend(PMSG_SUSPEND))) {		printk(KERN_ERR "Some devices failed to suspend\n");		goto Finish;	}	return 0; Finish:	if (pm_ops->finish)		pm_ops->finish(state); Thaw:	thaw_processes(); Enable_cpu:	enable_nonboot_cpus();	pm_restore_console();	return error;}  int suspend_enter(suspend_state_t state){	int error = 0;	unsigned long flags; 	local_irq_save(flags); 	if ((error = device_power_down(PMSG_SUSPEND))) {		printk(KERN_ERR "Some devices failed to power down\n");		goto Done;	}	error = pm_ops->enter(state);	device_power_up(); Done:	local_irq_restore(flags);	return error;}  /** *	suspend_finish - Do final work before exiting suspend sequence. *	@state:		State we're coming out of. * *	Call platform code to clean up, restart processes, and free the  *	console that we've allocated. This is not called for suspend-to-disk. */ static void suspend_finish(suspend_state_t state){	device_resume();	resume_console();	thaw_processes();	enable_nonboot_cpus();	if (pm_ops && pm_ops->finish)		pm_ops->finish(state);	pm_restore_console();}    static char *pm_states[PM_SUSPEND_MAX] = {	[PM_SUSPEND_STANDBY]	= "standby",	[PM_SUSPEND_MEM]	= "mem",#ifdef CONFIG_SOFTWARE_SUSPEND	[PM_SUSPEND_DISK]	= "disk",#endif}; static inline int valid_state(suspend_state_t state){	/* Suspend-to-disk does not really need low-level support.	 * It can work with reboot if needed. */	if (state == PM_SUSPEND_DISK)		return 1; 	if (pm_ops && pm_ops->valid && !pm_ops->valid(state))		return 0;	return 1;}  /** *	enter_state - Do common work of entering low-power state. *	@state:		pm_state structure for state we're entering. * *	Make sure we're the only ones trying to enter a sleep state. Fail *	if someone has beat us to it, since we don't want anything weird to *	happen when we wake up. *	Then, do the setup for suspend, enter the state, and cleaup (after *	we've woken up). */ static int enter_state(suspend_state_t state){	int error; 	if (!valid_state(state))		return -ENODEV;	if (down_trylock(&pm_sem))		return -EBUSY; 	if (state == PM_SUSPEND_DISK) {		error = pm_suspend_disk();		goto Unlock;	} 	pr_debug("PM: Preparing system for %s sleep\n", pm_states[state]);	if ((error = suspend_prepare(state)))		goto Unlock; 	pr_debug("PM: Entering %s sleep\n", pm_states[state]);	error = suspend_enter(state); 	pr_debug("PM: Finishing wakeup.\n");	suspend_finish(state); Unlock:	up(&pm_sem);	return error;} /* * This is main interface to the outside world. It needs to be * called from process context. */int software_suspend(void){	return enter_state(PM_SUSPEND_DISK);}  /** *	pm_suspend - Externally visible function for suspending system. *	@state:		Enumarted value of state to enter. * *	Determine whether or not value is within range, get state  *	structure, and enter (above). */ int pm_suspend(suspend_state_t state){	if (state > PM_SUSPEND_ON && state <= PM_SUSPEND_MAX)		return enter_state(state);	return -EINVAL;}   decl_subsys(power,NULL,NULL);  /** *	state - control system power state. * *	show() returns what states are supported, which is hard-coded to *	'standby' (Power-On Suspend), 'mem' (Suspend-to-RAM), and *	'disk' (Suspend-to-Disk). * *	store() accepts one of those strings, translates it into the  *	proper enumerated value, and initiates a suspend transition. */ static ssize_t state_show(struct subsystem * subsys, char * buf){	int i;	char * s = buf; 	for (i = 0; i < PM_SUSPEND_MAX; i++) {		if (pm_states[i] && valid_state(i))			s += sprintf(s,"%s ", pm_states[i]);	}	s += sprintf(s,"\n");	return (s - buf);} static ssize_t state_store(struct subsystem * subsys, const char * buf, size_t n){	suspend_state_t state = PM_SUSPEND_STANDBY;	char ** s;	char *p;	int error;	int len; 	p = memchr(buf, '\n', n);	len = p ? p - buf : n; 	for (s = &pm_states[state]; state < PM_SUSPEND_MAX; s++, state++) {		if (*s && !strncmp(buf, *s, len))			break;	}	if (state < PM_SUSPEND_MAX && *s)		error = enter_state(state);	else		error = -EINVAL;	return error ? error : n;} power_attr(state); static struct attribute * g[] = {	&state_attr.attr,	NULL,}; static struct attribute_group attr_group = {	.attrs = g,};  static int __init pm_init(void){	int error = subsystem_register(&power_subsys);	if (!error)		error = sysfs_create_group(&power_subsys.kset.kobj,&attr_group);	return error;} core_initcall(pm_init);