写一个中断处理程序

注册一个中断处理程序的request_irq函数的声明如下：

int request_irq(unsigned int irq,
irq_handler_t handler,
unsigned long flags,
const char *name,
void *dev)

我们可以在同一个驱动程序中给同一个中断号注册多个处理程序（虽然没什么意义），使用同一个name参数来注册也没关系，name参数的作用只是让注册的中断处理程序出现在/proc/interrupts,只有与用户通信的作用。如果是共享中断号，那么要传进正确的dev参数，如果你给一个中断号注册两个使用同一个dev参数的处理程序，那么在执行free_irq的时候会死机，因为内核无法确定要释放哪个中断处理程序。
中断处理程序如下：

#include <linux/init.h>
#include <linux/module.h>
#include <linux/interrupt.h>

static void main_exit(void);

int identity1 = 0;
int identity2 = 0;

static irqreturn_t my_interrupt1(int irq, void *identity)
{
    printk(KERN_INFO "keyboard interrupt occured 1n");
    return IRQ_HANDLED;
}

static irqreturn_t my_interrupt2(int irq, void *identity)
{
    printk(KERN_INFO "keyboard interrupt occured 2n");
    return IRQ_HANDLED;
}

static int main_init(void)
{
    if (request_irq(1, my_interrupt1, IRQF_SHARED, "my_interrupt", &identity1)) {
    return -EIO;
    }
    if (request_irq(1, my_interrupt2, IRQF_SHARED, "my_interrupt", &identity2)) {
    free_irq(1, &identity1);
    return -EIO;
    }
    return 0;
}

static void main_exit(void)
{
    free_irq(1, &identity2);
    free_irq(1, &identity1);
}

module_init(main_init);
module_exit(main_exit);

dmesg | tail后输出是：
[  375.623855] keyboard interrupt occured 1
[  375.623863] keyboard interrupt occured 2
[  375.671814] keyboard interrupt occured 1
[  375.671822] keyboard interrupt occured 2
[  375.789948] keyboard interrupt occured 1
[  375.789958] keyboard interrupt occured 2
[  375.850725] keyboard interrupt occured 1
[  375.850731] keyboard interrupt occured 2
[  375.999368] keyboard interrupt occured 1
[  375.999376] keyboard interrupt occured 2