/*
   * kernel/power/suspend.c - Suspend to RAM and standby functionality.
   *
   * Copyright (c) 2003 Patrick Mochel
   * Copyright (c) 2003 Open Source Development Lab
   * Copyright (c) 2009 Rafael J. Wysocki <rjw@sisk.pl>, Novell Inc.
   *
   * This file is released under the GPLv2.
   */
  
  #include <linux/string.h>
  #include <linux/delay.h>
  #include <linux/errno.h>
  #include <linux/init.h>

  #include <linux/kmod.h>

  #include <linux/console.h>
  #include <linux/cpu.h>
  #include <linux/syscalls.h>

  #include <linux/gfp.h>

  #include <linux/io.h>
  #include <linux/kernel.h>
  #include <linux/list.h>
  #include <linux/mm.h>
  #include <linux/slab.h>

  #include <linux/export.h>

  #include <linux/suspend.h>

  #include <linux/syscore_ops.h>

  #include <trace/events/power.h>

  
  #include "power.h"
  
  const char *const pm_states[PM_SUSPEND_MAX] = {
  	[PM_SUSPEND_STANDBY]	= "standby",
  	[PM_SUSPEND_MEM]	= "mem",
  };

  static const struct platform_suspend_ops *suspend_ops;

  
  /**
   *	suspend_set_ops - Set the global suspend method table.
   *	@ops:	Pointer to ops structure.
   */

  void suspend_set_ops(const struct platform_suspend_ops *ops)

  {

  	lock_system_sleep();

  	suspend_ops = ops;

  	unlock_system_sleep();

  }

  EXPORT_SYMBOL_GPL(suspend_set_ops);

  
  bool valid_state(suspend_state_t state)
  {
  	/*
  	 * All states need lowlevel support and need to be valid to the lowlevel
  	 * implementation, no valid callback implies that none are valid.
  	 */
  	return suspend_ops && suspend_ops->valid && suspend_ops->valid(state);
  }
  
  /**
   * suspend_valid_only_mem - generic memory-only valid callback
   *
   * Platform drivers that implement mem suspend only and only need
   * to check for that in their .valid callback can use this instead
   * of rolling their own .valid callback.
   */
  int suspend_valid_only_mem(suspend_state_t state)
  {
  	return state == PM_SUSPEND_MEM;
  }

  EXPORT_SYMBOL_GPL(suspend_valid_only_mem);

  
  static int suspend_test(int level)
  {
  #ifdef CONFIG_PM_DEBUG
  	if (pm_test_level == level) {
  		printk(KERN_INFO "suspend debug: Waiting for 5 seconds.
  ");
  		mdelay(5000);
  		return 1;
  	}
  #endif /* !CONFIG_PM_DEBUG */
  	return 0;
  }
  
  /**
   *	suspend_prepare - Do prep work before entering low-power state.
   *
   *	This is common code that is called for each state that we're entering.
   *	Run suspend notifiers, allocate a console and stop all processes.
   */
  static int suspend_prepare(void)
  {
  	int error;
  
  	if (!suspend_ops || !suspend_ops->enter)
  		return -EPERM;
  
  	pm_prepare_console();
  
  	error = pm_notifier_call_chain(PM_SUSPEND_PREPARE);
  	if (error)
  		goto Finish;
  
  	error = usermodehelper_disable();
  	if (error)
  		goto Finish;
  
  	error = suspend_freeze_processes();

  	if (!error)

  		return 0;

  	suspend_stats.failed_freeze++;
  	dpm_save_failed_step(SUSPEND_FREEZE);

  	usermodehelper_enable();
   Finish:
  	pm_notifier_call_chain(PM_POST_SUSPEND);
  	pm_restore_console();
  	return error;
  }
  
  /* default implementation */
  void __attribute__ ((weak)) arch_suspend_disable_irqs(void)
  {
  	local_irq_disable();
  }
  
  /* default implementation */
  void __attribute__ ((weak)) arch_suspend_enable_irqs(void)
  {
  	local_irq_enable();
  }
  
  /**

   * suspend_enter - enter the desired system sleep state.
   * @state: State to enter
   * @wakeup: Returns information that suspend should not be entered again.

   *

   * This function should be called after devices have been suspended.

   */

  static int suspend_enter(suspend_state_t state, bool *wakeup)

  {
  	int error;
  
  	if (suspend_ops->prepare) {
  		error = suspend_ops->prepare();
  		if (error)

  			goto Platform_finish;

  	}
  
  	error = dpm_suspend_noirq(PMSG_SUSPEND);
  	if (error) {
  		printk(KERN_ERR "PM: Some devices failed to power down
  ");

  		goto Platform_finish;

  	}
  
  	if (suspend_ops->prepare_late) {
  		error = suspend_ops->prepare_late();
  		if (error)

  			goto Platform_wake;

  	}
  
  	if (suspend_test(TEST_PLATFORM))
  		goto Platform_wake;
  
  	error = disable_nonboot_cpus();
  	if (error || suspend_test(TEST_CPUS))
  		goto Enable_cpus;
  
  	arch_suspend_disable_irqs();
  	BUG_ON(!irqs_disabled());

  	error = syscore_suspend();

  	if (!error) {

  		*wakeup = pm_wakeup_pending();
  		if (!(suspend_test(TEST_CORE) || *wakeup)) {

  			error = suspend_ops->enter(state);

  			events_check_enabled = false;
  		}

  		syscore_resume();

  	}
  
  	arch_suspend_enable_irqs();
  	BUG_ON(irqs_disabled());
  
   Enable_cpus:
  	enable_nonboot_cpus();
  
   Platform_wake:
  	if (suspend_ops->wake)
  		suspend_ops->wake();

  	dpm_resume_noirq(PMSG_RESUME);

   Platform_finish:

  	if (suspend_ops->finish)
  		suspend_ops->finish();
  
  	return error;
  }
  
  /**
   *	suspend_devices_and_enter - suspend devices and enter the desired system
   *				    sleep state.
   *	@state:		  state to enter
   */
  int suspend_devices_and_enter(suspend_state_t state)
  {
  	int error;

  	bool wakeup = false;

  
  	if (!suspend_ops)
  		return -ENOSYS;

  	trace_machine_suspend(state);

  	if (suspend_ops->begin) {
  		error = suspend_ops->begin(state);
  		if (error)
  			goto Close;
  	}
  	suspend_console();
  	suspend_test_start();
  	error = dpm_suspend_start(PMSG_SUSPEND);
  	if (error) {
  		printk(KERN_ERR "PM: Some devices failed to suspend
  ");
  		goto Recover_platform;
  	}
  	suspend_test_finish("suspend devices");
  	if (suspend_test(TEST_DEVICES))
  		goto Recover_platform;

  	do {
  		error = suspend_enter(state, &wakeup);
  	} while (!error && !wakeup
  		&& suspend_ops->suspend_again && suspend_ops->suspend_again());

  
   Resume_devices:
  	suspend_test_start();
  	dpm_resume_end(PMSG_RESUME);
  	suspend_test_finish("resume devices");
  	resume_console();
   Close:
  	if (suspend_ops->end)
  		suspend_ops->end();

  	trace_machine_suspend(PWR_EVENT_EXIT);

  	return error;
  
   Recover_platform:
  	if (suspend_ops->recover)
  		suspend_ops->recover();
  	goto Resume_devices;
  }
  
  /**
   *	suspend_finish - Do final work before exiting suspend sequence.
   *
   *	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(void)
  {
  	suspend_thaw_processes();
  	usermodehelper_enable();
  	pm_notifier_call_chain(PM_POST_SUSPEND);
  	pm_restore_console();
  }
  
  /**
   *	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).
   */
  int enter_state(suspend_state_t state)
  {
  	int error;
  
  	if (!valid_state(state))
  		return -ENODEV;
  
  	if (!mutex_trylock(&pm_mutex))
  		return -EBUSY;
  
  	printk(KERN_INFO "PM: Syncing filesystems ... ");
  	sys_sync();
  	printk("done.
  ");
  
  	pr_debug("PM: Preparing system for %s sleep
  ", pm_states[state]);
  	error = suspend_prepare();
  	if (error)
  		goto Unlock;
  
  	if (suspend_test(TEST_FREEZER))
  		goto Finish;
  
  	pr_debug("PM: Entering %s sleep
  ", pm_states[state]);

  	pm_restrict_gfp_mask();

  	error = suspend_devices_and_enter(state);

  	pm_restore_gfp_mask();

  
   Finish:
  	pr_debug("PM: Finishing wakeup.
  ");
  	suspend_finish();
   Unlock:
  	mutex_unlock(&pm_mutex);
  	return error;
  }
  
  /**
   *	pm_suspend - Externally visible function for suspending system.
   *	@state:		Enumerated 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)
  {

  	int ret;

  	if (state > PM_SUSPEND_ON && state < PM_SUSPEND_MAX) {

  		ret = enter_state(state);
  		if (ret) {
  			suspend_stats.fail++;
  			dpm_save_failed_errno(ret);
  		} else
  			suspend_stats.success++;
  		return ret;
  	}

  	return -EINVAL;
  }
  EXPORT_SYMBOL(pm_suspend);