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int irq_set_chip(unsigned int irq, struct irq_chip *chip)为形参的irq设置对应的irq_chip其使用的例程如下：void irq_remove_generic_chip(struct irq_chip_generic *gc, u32 msk,			     unsigned int clr, unsigned int set){	unsigned int i = gc->irq_base;	raw_spin_lock(&gc_lock);	list_del(&gc->list);	raw_spin_unlock(&gc_lock);	for (; msk; msk >>= 1, i++) {		if (!(msk & 0x01))			continue;		/* Remove handler first. That will mask the irq line */		irq_set_handler(i, NULL);		irq_set_chip(i, &no_irq_chip);		irq_set_chip_data(i, NULL);		irq_modify_status(i, clr, set);	}}其源码分析如下：int irq_set_chip(unsigned int irq, struct irq_chip *chip){	unsigned long flags;	#根据中断号得到中断描述符	struct irq_desc *desc = irq_get_desc_lock(irq, &flags, 0);	#中断描述符为null，则退出	if (!desc)		return -EINVAL;	#要设置的形参chip为null的话，则设置为no_irq_chip	if (!chip)		chip = &no_irq_chip;	#更新中断描述符的irq_data.chip，从这里看到irq_set_chip 可以被反复调用，新值会覆盖旧值	desc->irq_data.chip = chip;	irq_put_desc_unlock(desc, flags);	/*	 * For !CONFIG_SPARSE_IRQ make the irq show up in	 * allocated_irqs.	 */	 #在allocated_irqs中设置irq对应的bit	irq_mark_irq(irq);	return 0;}void irq_mark_irq(unsigned int irq){	mutex_lock(&sparse_irq_lock);	bitmap_set(allocated_irqs, irq, 1);	mutex_unlock(&sparse_irq_lock);}

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