外部终端之request_irq()函数

/**
 *	request_threaded_irq - allocate an interrupt line
 *	@irq: Interrupt line to allocate
 *	@handler: Function to be called when the IRQ occurs.
 *		  Primary handler for threaded interrupts
 *		  If NULL and thread_fn != NULL the default
 *		  primary handler is installed
 *	@thread_fn: Function called from the irq handler thread
 *		    If NULL, no irq thread is created
 *	@irqflags: Interrupt type flags
 *	@devname: An ascii name for the claiming device
 *	@dev_id: A cookie passed back to the handler function
 *
 *	This call allocates interrupt resources and enables the
 *	interrupt line and IRQ handling. From the point this
 *	call is made your handler function may be invoked. Since
 *	your handler function must clear any interrupt the board
 *	raises, you must take care both to initialise your hardware
 *	and to set up the interrupt handler in the right order.
 *
 *	If you want to set up a threaded irq handler for your device
 *	then you need to supply @handler and @thread_fn. @handler ist
 *	still called in hard interrupt context and has to check
 *	whether the interrupt originates from the device. If yes it
 *	needs to disable the interrupt on the device and return
 *	IRQ_WAKE_THREAD which will wake up the handler thread and run
 *	@thread_fn. This split handler design is necessary to support
 *	shared interrupts.
 *
 *	Dev_id must be globally unique. Normally the address of the
 *	device data structure is used as the cookie. Since the handler
 *	receives this value it makes sense to use it.
 *
 *	If your interrupt is shared you must pass a non NULL dev_id
 *	as this is required when freeing the interrupt.
 *
 *	Flags:
 *
 *	IRQF_SHARED		Interrupt is shared
 *	IRQF_SAMPLE_RANDOM	The interrupt can be used for entropy
 *	IRQF_TRIGGER_*		Specify active edge(s) or level
 *
 */

int request_irq(unsigned int irq,
		irq_handler_t handler,
		unsigned long flags, const char *devname, void *dev_id)
{
	struct irq_node *node;
	int res;

	node = new_irq_node();
	if (!node)
		return -ENOMEM;

	node->handler = handler;
	node->flags   = flags;
	node->dev_id  = dev_id;
	node->devname = devname;

	res = setup_irq(irq, node);
	if (res)
		node->handler = NULL;

	return res;
}

参数：
unsigned int irq：中断号，根据datasheet查看对应中断号
irq_handler_t handler：中断处理函数名
unsigned long flags：中断方式(比如上升沿，下降沿，上升下降沿)
const char *devname：中断名称cat proc/interruputs命令查看名称
void *dev_id：当前设备结构体