/*
   * linux/kernel/irq/pm.c
   *
   * Copyright (C) 2009 Rafael J. Wysocki <rjw@sisk.pl>, Novell Inc.
   *
   * This file contains power management functions related to interrupts.
   */
  
  #include <linux/irq.h>
  #include <linux/module.h>
  #include <linux/interrupt.h>
  
  #include "internals.h"
  
  /**
   * suspend_device_irqs - disable all currently enabled interrupt lines
   *

   * During system-wide suspend or hibernation device drivers need to be prevented
   * from receiving interrupts and this function is provided for this purpose.
   * It marks all interrupt lines in use, except for the timer ones, as disabled
   * and sets the IRQ_SUSPENDED flag for each of them.

   */
  void suspend_device_irqs(void)
  {
  	struct irq_desc *desc;
  	int irq;
  
  	for_each_irq_desc(irq, desc) {
  		unsigned long flags;

  		raw_spin_lock_irqsave(&desc->lock, flags);

  		__disable_irq(desc, irq, true);

  		raw_spin_unlock_irqrestore(&desc->lock, flags);

  	}
  
  	for_each_irq_desc(irq, desc)
  		if (desc->status & IRQ_SUSPENDED)
  			synchronize_irq(irq);
  }
  EXPORT_SYMBOL_GPL(suspend_device_irqs);
  
  /**
   * resume_device_irqs - enable interrupt lines disabled by suspend_device_irqs()
   *
   * Enable all interrupt lines previously disabled by suspend_device_irqs() that
   * have the IRQ_SUSPENDED flag set.
   */
  void resume_device_irqs(void)
  {
  	struct irq_desc *desc;
  	int irq;
  
  	for_each_irq_desc(irq, desc) {
  		unsigned long flags;
  
  		if (!(desc->status & IRQ_SUSPENDED))
  			continue;

  		raw_spin_lock_irqsave(&desc->lock, flags);

  		__enable_irq(desc, irq, true);

  		raw_spin_unlock_irqrestore(&desc->lock, flags);

  	}
  }
  EXPORT_SYMBOL_GPL(resume_device_irqs);
  
  /**
   * check_wakeup_irqs - check if any wake-up interrupts are pending
   */
  int check_wakeup_irqs(void)
  {
  	struct irq_desc *desc;
  	int irq;
  
  	for_each_irq_desc(irq, desc)
  		if ((desc->status & IRQ_WAKEUP) && (desc->status & IRQ_PENDING))
  			return -EBUSY;
  
  	return 0;
  }