text: /*
   * linux/kernel/irq/handle.c
   *
   * Copyright (C) 1992, 1998-2006 Linus Torvalds, Ingo Molnar
   * Copyright (C) 2005-2006, Thomas Gleixner, Russell King
   *
   * This file contains the core interrupt handling code.
   *
   * Detailed information is available in Documentation/DocBook/genericirq
   *
   */
  
  #include <linux/irq.h>
  #include <linux/module.h>
  #include <linux/random.h>
  #include <linux/interrupt.h>
  #include <linux/kernel_stat.h>
  #include <typedefs.h>
  #include <bcmdefs.h>
  
  #include "internals.h"
  
  /**
   * handle_bad_irq - handle spurious and unhandled irqs
   * @irq:       the interrupt number
   * @desc:      description of the interrupt
   *
   * Handles spurious and unhandled IRQ's. It also prints a debugmessage.
   */
  void fastcall
  handle_bad_irq(unsigned int irq, struct irq_desc *desc)
  {
  	print_irq_desc(irq, desc);
  	kstat_this_cpu.irqs[irq]++;
  	ack_bad_irq(irq);
  }
  
  /*
   * Linux has a controller-independent interrupt architecture.
   * Every controller has a 'controller-template', that is used
   * by the main code to do the right thing. Each driver-visible
   * interrupt source is transparently wired to the appropriate
   * controller. Thus drivers need not be aware of the
   * interrupt-controller.
   *
   * The code is designed to be easily extended with new/different
   * interrupt controllers, without having to do assembly magic or
   * having to touch the generic code.
   *
   * Controller mappings for all interrupt sources:
   */
  struct irq_desc irq_desc[NR_IRQS] __cacheline_aligned_in_smp = {
  	[0 ... NR_IRQS-1] = {
  		.status = IRQ_DISABLED,
  		.chip = &no_irq_chip,
  		.handle_irq = handle_bad_irq,
  		.depth = 1,
  		.lock = __SPIN_LOCK_UNLOCKED(irq_desc->lock),
  #ifdef CONFIG_SMP
  		.affinity = CPU_MASK_ALL
  #endif
  	}
  };
  
  /*
   * What should we do if we get a hw irq event on an illegal vector?
   * Each architecture has to answer this themself.
   */
  static void ack_bad(unsigned int irq)
  {
  	print_irq_desc(irq, irq_desc + irq);
  	ack_bad_irq(irq);
  }
  
  /*
   * NOP functions
   */
  static void noop(unsigned int irq)
  {
  }
  
  static unsigned int noop_ret(unsigned int irq)
  {
  	return 0;
  }
  
  /*
   * Generic no controller implementation
   */
  struct irq_chip no_irq_chip = {
  	.name		= "none",
  	.startup	= noop_ret,
  	.shutdown	= noop,
  	.enable		= noop,
  	.disable	= noop,
  	.ack		= ack_bad,
  	.end		= noop,
  };
  
  /*
   * Generic dummy implementation which can be used for
   * real dumb interrupt sources
   */
  struct irq_chip dummy_irq_chip = {
  	.name		= "dummy",
  	.startup	= noop_ret,
  	.shutdown	= noop,
  	.enable		= noop,
  	.disable	= noop,
  	.ack		= noop,
  	.mask		= noop,
  	.unmask		= noop,
  	.end		= noop,
  };
  
  /*
   * Special, empty irq handler:
   */
  irqreturn_t no_action(int cpl, void *dev_id)
  {
  	return IRQ_NONE;
  }
  
  /**
   * handle_IRQ_event - irq action chain handler
   * @irq:	the interrupt number
   * @action:	the interrupt action chain for this irq
   *
   * Handles the action chain of an irq event
   */
  irqreturn_t BCMFASTPATH handle_IRQ_event(unsigned int irq, struct irqaction *action)
  {
  	irqreturn_t ret, retval = IRQ_NONE;
  	unsigned int status = 0;
  
  	handle_dynamic_tick(action);
  
  	if (!(action->flags & IRQF_DISABLED))
  		local_irq_enable_in_hardirq();
  
  	do {
  		ret = action->handler(irq, action->dev_id);
  		if (ret == IRQ_HANDLED)
  			status |= action->flags;
  		retval |= ret;
  		action = action->next;
  	} while (action);
  
  	if (status & IRQF_SAMPLE_RANDOM)
  		add_interrupt_randomness(irq);
  	local_irq_disable();
  
  	return retval;
  }
  
  #ifndef CONFIG_GENERIC_HARDIRQS_NO__DO_IRQ
  /**
   * __do_IRQ - original all in one highlevel IRQ handler
   * @irq:	the interrupt number
   *
   * __do_IRQ handles all normal device IRQ's (the special
   * SMP cross-CPU interrupts have their own specific
   * handlers).
   *
   * This is the original x86 implementation which is used for every
   * interrupt type.
   */
  fastcall unsigned int BCMFASTPATH __do_IRQ(unsigned int irq)
  {
  	struct irq_desc *desc = irq_desc + irq;
  	struct irqaction *action;
  	unsigned int status;
  
  	kstat_this_cpu.irqs[irq]++;
  	if (CHECK_IRQ_PER_CPU(desc->status)) {
  		irqreturn_t action_ret;
  
  		/*
  		 * No locking required for CPU-local interrupts:
  		 */
  		if (desc->chip->ack)
  			desc->chip->ack(irq);
  		action_ret = handle_IRQ_event(irq, desc->action);
  		if (!noirqdebug)
  			note_interrupt(irq, desc, action_ret);
  		desc->chip->end(irq);
  		return 1;
  	}
  
  	spin_lock(&desc->lock);
  	if (desc->chip->ack)
  		desc->chip->ack(irq);
  	/*
  	 * REPLAY is when Linux resends an IRQ that was dropped earlier
  	 * WAITING is used by probe to mark irqs that are being tested
  	 */
  	status = desc->status & ~(IRQ_REPLAY | IRQ_WAITING);
  	status |= IRQ_PENDING; /* we _want_ to handle it */
  
  	/*
  	 * If the IRQ is disabled for whatever reason, we cannot
  	 * use the action we have.
  	 */
  	action = NULL;
  	if (likely(!(status & (IRQ_DISABLED | IRQ_INPROGRESS)))) {
  		action = desc->action;
  		status &= ~IRQ_PENDING; /* we commit to handling */
  		status |= IRQ_INPROGRESS; /* we are handling it */
  	}
  	desc->status = status;
  
  	/*
  	 * If there is no IRQ handler or it was disabled, exit early.
  	 * Since we set PENDING, if another processor is handling
  	 * a different instance of this same irq, the other processor
  	 * will take care of it.
  	 */
  	if (unlikely(!action))
  		goto out;
  
  	/*
  	 * Edge triggered interrupts need to remember
  	 * pending events.
  	 * This applies to any hw interrupts that allow a second
  	 * instance of the same irq to arrive while we are in do_IRQ
  	 * or in the handler. But the code here only handles the _second_
  	 * instance of the irq, not the third or fourth. So it is mostly
  	 * useful for irq hardware that does not mask cleanly in an
  	 * SMP environment.
  	 */
  	for (;;) {
  		irqreturn_t action_ret;
  
  		spin_unlock(&desc->lock);
  
  		action_ret = handle_IRQ_event(irq, action);
  		if (!noirqdebug)
  			note_interrupt(irq, desc, action_ret);
  
  		spin_lock(&desc->lock);
  		if (likely(!(desc->status & IRQ_PENDING)))
  			break;
  		desc->status &= ~IRQ_PENDING;
  	}
  	desc->status &= ~IRQ_INPROGRESS;
  
  out:
  	/*
  	 * The ->end() handler has to deal with interrupts which got
  	 * disabled while the handler was running.
  	 */
  	desc->chip->end(irq);
  	spin_unlock(&desc->lock);
  
  	return 1;
  }
  #endif
  
  #ifdef CONFIG_TRACE_IRQFLAGS
  
  /*
   * lockdep: we want to handle all irq_desc locks as a single lock-class:
   */
  static struct lock_class_key irq_desc_lock_class;
  
  void early_init_irq_lock_class(void)
  {
  	int i;
  
  	for (i = 0; i < NR_IRQS; i++)
  		lockdep_set_class(&irq_desc[i].lock, &irq_desc_lock_class);
  }
  
  #endif
  