1 裸机中断处理函数流程

分辨是哪一个中断
调用中断对应的处理函数
处理完毕清中断

2 Linux中断处理流程

在Linux内核里面，上面所说的这三项都是在linux-2.6.22.6\arch\arm\kernel\irq.c的asm_do_IRQ函数里面做的，

/*
 * do_IRQ handles all hardware IRQ's.  Decoded IRQs should not
 * come via this function.  Instead, they should provide their
 * own 'handler'
 */
asmlinkage void __exception asm_do_IRQ(unsigned int irq, struct pt_regs *regs)
{
	struct pt_regs *old_regs = set_irq_regs(regs);
	struct irq_desc *desc = irq_desc + irq;

	/*
	 * Some hardware gives randomly wrong interrupts.  Rather
	 * than crashing, do something sensible.
	 */
	if (irq >= NR_IRQS)
		desc = &bad_irq_desc;

	irq_enter();

	desc_handle_irq(irq, desc);

	/* AT91 specific workaround */
	irq_finish(irq);

	irq_exit();
	set_irq_regs(old_regs);
}

传进来的irq是中断号，irq_desc是一个中断描述数组，这个数组以中断号为下标，然后desc_handle_irq进入处理，desc_handle_irq这个函数在头文件irq.h里面，


/*
 * Obsolete inline function for calling irq descriptor handlers.
 */
static inline void desc_handle_irq(unsigned int irq, struct irq_desc *desc)
{
	desc->handle_irq(irq, desc);
}

desc是irq_desc这个数组的一个项，是根据中断号获取的这个项，这个handle_irq函数是在下面的函数中设置的

void
__set_irq_handler(unsigned int irq, irq_flow_handler_t handle, int is_chained,
		  const char *name)
{
	struct irq_desc *desc;
	unsigned long flags;

	if (irq >= NR_IRQS) {
		printk(KERN_ERR
		       "Trying to install type control for IRQ%d\n", irq);
		return;
	}

	desc = irq_desc + irq;

	if (!handle)
		handle = handle_bad_irq;
	else if (desc->chip == &no_irq_chip) {
		printk(KERN_WARNING "Trying to install %sinterrupt handler "
		       "for IRQ%d\n", is_chained ? "chained " : "", irq);
		/*
		 * Some ARM implementations install a handler for really dumb
		 * interrupt hardware without setting an irq_chip. This worked
		 * with the ARM no_irq_chip but the check in setup_irq would
		 * prevent us to setup the interrupt at all. Switch it to
		 * dummy_irq_chip for easy transition.
		 */
		desc->chip = &dummy_irq_chip;
	}

	spin_lock_irqsave(&desc->lock, flags);

	/* Uninstall? */
	if (handle == handle_bad_irq) {
		if (desc->chip != &no_irq_chip)
			mask_ack_irq(desc, irq);
		desc->status |= IRQ_DISABLED;
		desc->depth = 1;
	}
	desc->handle_irq = handle;
	desc->name = name;

	if (handle != handle_bad_irq && is_chained) {
		desc->status &= ~IRQ_DISABLED;
		desc->status |= IRQ_NOREQUEST | IRQ_NOPROBE;
		desc->depth = 0;
		desc->chip->unmask(irq);
	}
	spin_unlock_irqrestore(&desc->lock, flags);
}

然后找到

/*
 * Set a highlevel flow handler for a given IRQ:
 */
static inline void
set_irq_handler(unsigned int irq, irq_flow_handler_t handle)
{
	__set_irq_handler(irq, handle, 0, NULL);
}

然后继续搜ser_irq_handle，