text: /*
   * 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/console.h>
  #include <linux/cpu.h>
  #include <linux/cpuidle.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 <linux/ftrace.h>
  #include <trace/events/power.h>
  #include <linux/compiler.h>
  
  #include "power.h"
  
  const char *pm_labels[] = { "mem", "standby", "freeze", NULL };
  const char *pm_states[PM_SUSPEND_MAX];
  
  static const struct platform_suspend_ops *suspend_ops;
  static const struct platform_freeze_ops *freeze_ops;
  static DECLARE_WAIT_QUEUE_HEAD(suspend_freeze_wait_head);
  
  enum freeze_state __read_mostly suspend_freeze_state;
  static DEFINE_SPINLOCK(suspend_freeze_lock);
  
  void freeze_set_ops(const struct platform_freeze_ops *ops)
  {
  	lock_system_sleep();
  	freeze_ops = ops;
  	unlock_system_sleep();
  }
  
  static void freeze_begin(void)
  {
  	suspend_freeze_state = FREEZE_STATE_NONE;
  }
  
  static void freeze_enter(void)
  {
  	spin_lock_irq(&suspend_freeze_lock);
  	if (pm_wakeup_pending())
  		goto out;
  
  	suspend_freeze_state = FREEZE_STATE_ENTER;
  	spin_unlock_irq(&suspend_freeze_lock);
  
  	get_online_cpus();
  	cpuidle_resume();
  
  	/* Push all the CPUs into the idle loop. */
  	wake_up_all_idle_cpus();
  	pr_debug("PM: suspend-to-idle\n");
  	/* Make the current CPU wait so it can enter the idle loop too. */
  	wait_event(suspend_freeze_wait_head,
  		   suspend_freeze_state == FREEZE_STATE_WAKE);
  	pr_debug("PM: resume from suspend-to-idle\n");
  
  	cpuidle_pause();
  	put_online_cpus();
  
  	spin_lock_irq(&suspend_freeze_lock);
  
   out:
  	suspend_freeze_state = FREEZE_STATE_NONE;
  	spin_unlock_irq(&suspend_freeze_lock);
  }
  
  void freeze_wake(void)
  {
  	unsigned long flags;
  
  	spin_lock_irqsave(&suspend_freeze_lock, flags);
  	if (suspend_freeze_state > FREEZE_STATE_NONE) {
  		suspend_freeze_state = FREEZE_STATE_WAKE;
  		wake_up(&suspend_freeze_wait_head);
  	}
  	spin_unlock_irqrestore(&suspend_freeze_lock, flags);
  }
  EXPORT_SYMBOL_GPL(freeze_wake);
  
  static bool valid_state(suspend_state_t state)
  {
  	/*
  	 * PM_SUSPEND_STANDBY and PM_SUSPEND_MEM states need low level
  	 * support and need to be valid to the low level
  	 * implementation, no valid callback implies that none are valid.
  	 */
  	return suspend_ops && suspend_ops->valid && suspend_ops->valid(state);
  }
  
  /*
   * If this is set, the "mem" label always corresponds to the deepest sleep state
   * available, the "standby" label corresponds to the second deepest sleep state
   * available (if any), and the "freeze" label corresponds to the remaining
   * available sleep state (if there is one).
   */
  static bool relative_states;
  
  static int __init sleep_states_setup(char *str)
  {
  	relative_states = !strncmp(str, "1", 1);
  	pm_states[PM_SUSPEND_FREEZE] = pm_labels[relative_states ? 0 : 2];
  	return 1;
  }
  
  __setup("relative_sleep_states=", sleep_states_setup);
  
  /**
   * suspend_set_ops - Set the global suspend method table.
   * @ops: Suspend operations to use.
   */
  void suspend_set_ops(const struct platform_suspend_ops *ops)
  {
  	suspend_state_t i;
  	int j = 0;
  
  	lock_system_sleep();
  
  	suspend_ops = ops;
  	for (i = PM_SUSPEND_MEM; i >= PM_SUSPEND_STANDBY; i--)
  		if (valid_state(i)) {
  			pm_states[i] = pm_labels[j++];
  		} else if (!relative_states) {
  			pm_states[i] = NULL;
  			j++;
  		}
  
  	pm_states[PM_SUSPEND_FREEZE] = pm_labels[j];
  
  	unlock_system_sleep();
  }
  EXPORT_SYMBOL_GPL(suspend_set_ops);
  
  /**
   * 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 bool sleep_state_supported(suspend_state_t state)
  {
  	return state == PM_SUSPEND_FREEZE || (suspend_ops && suspend_ops->enter);
  }
  
  static int platform_suspend_prepare(suspend_state_t state)
  {
  	return state != PM_SUSPEND_FREEZE && suspend_ops->prepare ?
  		suspend_ops->prepare() : 0;
  }
  
  static int platform_suspend_prepare_late(suspend_state_t state)
  {
  	return state == PM_SUSPEND_FREEZE && freeze_ops && freeze_ops->prepare ?
  		freeze_ops->prepare() : 0;
  }
  
  static int platform_suspend_prepare_noirq(suspend_state_t state)
  {
  	return state != PM_SUSPEND_FREEZE && suspend_ops->prepare_late ?
  		suspend_ops->prepare_late() : 0;
  }
  
  static void platform_resume_noirq(suspend_state_t state)
  {
  	if (state != PM_SUSPEND_FREEZE && suspend_ops->wake)
  		suspend_ops->wake();
  }
  
  static void platform_resume_early(suspend_state_t state)
  {
  	if (state == PM_SUSPEND_FREEZE && freeze_ops && freeze_ops->restore)
  		freeze_ops->restore();
  }
  
  static void platform_resume_finish(suspend_state_t state)
  {
  	if (state != PM_SUSPEND_FREEZE && suspend_ops->finish)
  		suspend_ops->finish();
  }
  
  static int platform_suspend_begin(suspend_state_t state)
  {
  	if (state == PM_SUSPEND_FREEZE && freeze_ops && freeze_ops->begin)
  		return freeze_ops->begin();
  	else if (suspend_ops->begin)
  		return suspend_ops->begin(state);
  	else
  		return 0;
  }
  
  static void platform_resume_end(suspend_state_t state)
  {
  	if (state == PM_SUSPEND_FREEZE && freeze_ops && freeze_ops->end)
  		freeze_ops->end();
  	else if (suspend_ops->end)
  		suspend_ops->end();
  }
  
  static void platform_recover(suspend_state_t state)
  {
  	if (state != PM_SUSPEND_FREEZE && suspend_ops->recover)
  		suspend_ops->recover();
  }
  
  static bool platform_suspend_again(suspend_state_t state)
  {
  	return state != PM_SUSPEND_FREEZE && suspend_ops->suspend_again ?
  		suspend_ops->suspend_again() : false;
  }
  
  static int suspend_test(int level)
  {
  #ifdef CONFIG_PM_DEBUG
  	if (pm_test_level == level) {
  		printk(KERN_INFO "suspend debug: Waiting for 5 seconds.\n");
  		mdelay(5000);
  		return 1;
  	}
  #endif /* !CONFIG_PM_DEBUG */
  	return 0;
  }
  
  /**
   * suspend_prepare - Prepare for entering system sleep state.
   *
   * Common code run for every system sleep state that can be entered (except for
   * hibernation).  Run suspend notifiers, allocate the "suspend" console and
   * freeze processes.
   */
  static int suspend_prepare(suspend_state_t state)
  {
  	int error;
  
  	if (!sleep_state_supported(state))
  		return -EPERM;
  
  	pm_prepare_console();
  
  	error = pm_notifier_call_chain(PM_SUSPEND_PREPARE);
  	if (error)
  		goto Finish;
  
  	trace_suspend_resume(TPS("freeze_processes"), 0, true);
  	error = suspend_freeze_processes();
  	trace_suspend_resume(TPS("freeze_processes"), 0, false);
  	if (!error)
  		return 0;
  
  	suspend_stats.failed_freeze++;
  	dpm_save_failed_step(SUSPEND_FREEZE);
   Finish:
  	pm_notifier_call_chain(PM_POST_SUSPEND);
  	pm_restore_console();
  	return error;
  }
  
  /* default implementation */
  void __weak arch_suspend_disable_irqs(void)
  {
  	local_irq_disable();
  }
  
  /* default implementation */
  void __weak arch_suspend_enable_irqs(void)
  {
  	local_irq_enable();
  }
  
  /**
   * suspend_enter - Make the system enter the given sleep state.
   * @state: System sleep state to enter.
   * @wakeup: Returns information that the sleep state should not be re-entered.
   *
   * This function should be called after devices have been suspended.
   */
  static int suspend_enter(suspend_state_t state, bool *wakeup)
  {
  	int error;
  
  	error = platform_suspend_prepare(state);
  	if (error)
  		goto Platform_finish;
  
  	error = dpm_suspend_late(PMSG_SUSPEND);
  	if (error) {
  		printk(KERN_ERR "PM: late suspend of devices failed\n");
  		goto Platform_finish;
  	}
  	error = platform_suspend_prepare_late(state);
  	if (error)
  		goto Devices_early_resume;
  
  	error = dpm_suspend_noirq(PMSG_SUSPEND);
  	if (error) {
  		printk(KERN_ERR "PM: noirq suspend of devices failed\n");
  		goto Platform_early_resume;
  	}
  	error = platform_suspend_prepare_noirq(state);
  	if (error)
  		goto Platform_wake;
  
  	if (suspend_test(TEST_PLATFORM))
  		goto Platform_wake;
  
  	/*
  	 * PM_SUSPEND_FREEZE equals
  	 * frozen processes + suspended devices + idle processors.
  	 * Thus we should invoke freeze_enter() soon after
  	 * all the devices are suspended.
  	 */
  	if (state == PM_SUSPEND_FREEZE) {
  		trace_suspend_resume(TPS("machine_suspend"), state, true);
  		freeze_enter();
  		trace_suspend_resume(TPS("machine_suspend"), state, false);
  		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)) {
  			trace_suspend_resume(TPS("machine_suspend"),
  				state, true);
  			error = suspend_ops->enter(state);
  			trace_suspend_resume(TPS("machine_suspend"),
  				state, false);
  			events_check_enabled = false;
  		}
  		syscore_resume();
  	}
  
  	arch_suspend_enable_irqs();
  	BUG_ON(irqs_disabled());
  
   Enable_cpus:
  	enable_nonboot_cpus();
  
   Platform_wake:
  	platform_resume_noirq(state);
  	dpm_resume_noirq(PMSG_RESUME);
  
   Platform_early_resume:
  	platform_resume_early(state);
  
   Devices_early_resume:
  	dpm_resume_early(PMSG_RESUME);
  
   Platform_finish:
  	platform_resume_finish(state);
  	return error;
  }
  
  /**
   * suspend_devices_and_enter - Suspend devices and enter system sleep state.
   * @state: System sleep state to enter.
   */
  int suspend_devices_and_enter(suspend_state_t state)
  {
  	int error;
  	bool wakeup = false;
  
  	if (!sleep_state_supported(state))
  		return -ENOSYS;
  
  	error = platform_suspend_begin(state);
  	if (error)
  		goto Close;
  
  	suspend_console();
  	suspend_test_start();
  	error = dpm_suspend_start(PMSG_SUSPEND);
  	if (error) {
  		pr_err("PM: Some devices failed to suspend, or early wake event detected\n");
  		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 && platform_suspend_again(state));
  
   Resume_devices:
  	suspend_test_start();
  	dpm_resume_end(PMSG_RESUME);
  	suspend_test_finish("resume devices");
  	trace_suspend_resume(TPS("resume_console"), state, true);
  	resume_console();
  	trace_suspend_resume(TPS("resume_console"), state, false);
  
   Close:
  	platform_resume_end(state);
  	return error;
  
   Recover_platform:
  	platform_recover(state);
  	goto Resume_devices;
  }
  
  /**
   * suspend_finish - Clean up before finishing the suspend sequence.
   *
   * Call platform code to clean up, restart processes, and free the console that
   * we've allocated. This routine is not called for hibernation.
   */
  static void suspend_finish(void)
  {
  	suspend_thaw_processes();
  	pm_notifier_call_chain(PM_POST_SUSPEND);
  	pm_restore_console();
  }
  
  /**
   * enter_state - Do common work needed to enter system sleep state.
   * @state: System sleep state to enter.
   *
   * Make sure that no one else is trying to put the system into a sleep state.
   * Fail if that's not the case.  Otherwise, prepare for system suspend, make the
   * system enter the given sleep state and clean up after wakeup.
   */
  static int enter_state(suspend_state_t state)
  {
  	int error;
  
  	trace_suspend_resume(TPS("suspend_enter"), state, true);
  	if (state == PM_SUSPEND_FREEZE) {
  #ifdef CONFIG_PM_DEBUG
  		if (pm_test_level != TEST_NONE && pm_test_level <= TEST_CPUS) {
  			pr_warning("PM: Unsupported test mode for freeze state,"
  				   "please choose none/freezer/devices/platform.\n");
  			return -EAGAIN;
  		}
  #endif
  	} else if (!valid_state(state)) {
  		return -EINVAL;
  	}
  	if (!mutex_trylock(&pm_mutex))
  		return -EBUSY;
  
  	if (state == PM_SUSPEND_FREEZE)
  		freeze_begin();
  
  	trace_suspend_resume(TPS("sync_filesystems"), 0, true);
  	printk(KERN_INFO "PM: Syncing filesystems ... ");
  	sys_sync();
  	printk("done.\n");
  	trace_suspend_resume(TPS("sync_filesystems"), 0, false);
  
  	pr_debug("PM: Preparing system for %s sleep\n", pm_states[state]);
  	error = suspend_prepare(state);
  	if (error)
  		goto Unlock;
  
  	if (suspend_test(TEST_FREEZER))
  		goto Finish;
  
  	trace_suspend_resume(TPS("suspend_enter"), state, false);
  	pr_debug("PM: Entering %s sleep\n", pm_states[state]);
  	pm_restrict_gfp_mask();
  	error = suspend_devices_and_enter(state);
  	pm_restore_gfp_mask();
  
   Finish:
  	pr_debug("PM: Finishing wakeup.\n");
  	suspend_finish();
   Unlock:
  	mutex_unlock(&pm_mutex);
  	return error;
  }
  
  /**
   * pm_suspend - Externally visible function for suspending the system.
   * @state: System sleep state to enter.
   *
   * Check if the value of @state represents one of the supported states,
   * execute enter_state() and update system suspend statistics.
   */
  int pm_suspend(suspend_state_t state)
  {
  	int error;
  
  	if (state <= PM_SUSPEND_ON || state >= PM_SUSPEND_MAX)
  		return -EINVAL;
  
  	error = enter_state(state);
  	if (error) {
  		suspend_stats.fail++;
  		dpm_save_failed_errno(error);
  	} else {
  		suspend_stats.success++;
  	}
  	return error;
  }
  EXPORT_SYMBOL(pm_suspend);
  