按键中断

按键中断查询，并显示中断号

#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/fs.h>
#include <linux/init.h>
#include <linux/delay.h>
#include <linux/irq.h>
#include <linux/sched.h>
#include <linux/interrupt.h>
#include <linux/device.h>
#include <asm/uaccess.h>
#include <asm/irq.h>
#include <asm/io.h>
#include <mach/regs-gpio.h>
#include <mach/hardware.h>
#include <linux/wait.h>
/*
按键k1 EINT1.  GPF1
按键k2 EINT4.  GPF4
按键k3 EINT2.  GPF2
按键k4 EINT0.  GPF0
GPFCON=0x56000050
GPFDAT=0x56000054
GPFUP=0x56000058
 */

static struct class *thirddrv_class;
static struct class_device	*thirddrv_class_dev;

volatile unsigned long *gpfcon;
volatile unsigned long *gpfdat;



static DECLARE_WAIT_QUEUE_HEAD(button_waitq);

/* 中断事件标志, 中断服务程序将它置1，third_drv_read将它清0 */
static volatile int ev_press = 0;


struct pin_desc{
	unsigned int pin;
	unsigned int key_val;
};


/* 键值: 按下时, 0x01, 0x02, 0x03, 0x04 */
/* 键值: 松开时, 0x81, 0x82, 0x83, 0x84 */
static unsigned char key_val;

struct pin_desc pins_desc[4] = {
	{S3C2410_GPF1, 0x01},
	{S3C2410_GPF4, 0x02},
	{S3C2410_GPF2, 0x03},
	{S3C2410_GPF0, 0x04},
};


/*
  * 确定按键值
  */
static irqreturn_t buttons_irq(int irq, void *dev_id)
{
	struct pin_desc * pindesc = (struct pin_desc *)dev_id;
	unsigned int pinval;
	
	pinval = s3c2410_gpio_getpin(pindesc->pin);

	if (pinval)
	{
		/* 松开 */
		key_val = 0x80 | pindesc->key_val;
	}
	else
	{
		/* 按下 */
		key_val = pindesc->key_val;
	}
/*也就是说按下时01、02、03、04    松开时显示81、82、83、84*/
    ev_press = 1;                  /* 表示中断发生了 */
    wake_up_interruptible(&button_waitq);   /* 唤醒休眠的进程 */

	
	return IRQ_RETVAL(IRQ_HANDLED);
}

static int third_drv_open(struct inode *inode, struct file *file)
{
	/* 配置GPF0,2为输入引脚 */
	/* 配置GPG3,11为输入引脚 */
	request_irq(IRQ_EINT1,  buttons_irq, IRQ_TYPE_EDGE_BOTH, "S2", &pins_desc[0]);
	request_irq(IRQ_EINT4,  buttons_irq, IRQ_TYPE_EDGE_BOTH, "S3", &pins_desc[1]);
	request_irq(IRQ_EINT2, buttons_irq, IRQ_TYPE_EDGE_BOTH, "S4", &pins_desc[2]);
	request_irq(IRQ_EINT0, buttons_irq, IRQ_TYPE_EDGE_BOTH, "S5", &pins_desc[3]);	

	return 0;
}

ssize_t third_drv_read(struct file *file, char __user *buf, size_t size, loff_t *ppos)
{
	if (size != 1)
		return -EINVAL;

	/* 如果没有按键动作, 休眠 */
	wait_event_interruptible(button_waitq, ev_press);

	/* 如果有按键动作, 返回键值 */
	copy_to_user(buf, &key_val, 1);
	ev_press = 0;
	
	return 1;
}


int third_drv_close(struct inode *inode, struct file *file)
{
	free_irq(IRQ_EINT1, &pins_desc[0]);
	free_irq(IRQ_EINT4, &pins_desc[1]);
	free_irq(IRQ_EINT2, &pins_desc[2]);
	free_irq(IRQ_EINT0, &pins_desc[3]);
	return 0;
}


static struct file_operations sencod_drv_fops = {
    .owner   =  THIS_MODULE,    /* 这是一个宏，推向编译模块时自动创建的__this_module变量 */
    .open    =  third_drv_open,     
	.read	 =	third_drv_read,	   
	.release =  third_drv_close,	   
};


int major;
static int third_drv_init(void)
{
	major = register_chrdev(0, "third_drv", &sencod_drv_fops);

	thirddrv_class = class_create(THIS_MODULE, "third_drv");

	thirddrv_class_dev = device_create(thirddrv_class, NULL, MKDEV(major, 0), NULL, "buttons"); /* /dev/buttons */

	gpfcon = (volatile unsigned long *)ioremap(0x56000050, 16);
	gpfdat = gpfcon + 1;

	return 0;
}

static void third_drv_exit(void)
{
	unregister_chrdev(major, "third_drv");
	device_destroy(thirddrv_class,MKDEV(major,0));
	class_destroy(thirddrv_class);
	iounmap(gpfcon);
	
	//return 0;
}


module_init(third_drv_init);

module_exit(third_drv_exit);

MODULE_LICENSE("GPL");

测试程序：

#include <sys/types.h> #include <sys/stat.h> #include <fcntl.h> #include <stdio.h> /* thirddrvtest */ int main(int argc, char **argv) { int fd; unsigned char key_val; fd = open("/dev/buttons", O_RDWR); if (fd < 0) { printf("can't open!\n"); } while (1) { read(fd, &key_val, 1); printf("key_val = 0x%x\n", key_val); } return 0; }

对程序的解释：

先说硬件资源： tq2440开发板的按键

 按键k1    EINT1.  GPF1               按键k2    EINT4.  GPF4            按键k3    EINT2.    GPF2         按键k4      EINT0.    GPF0

GPFCON=0x56000050      GPFDAT=0x56000054        GPFUP=0x56000058

再看程序：

在third_drv_init（）函数中，注册字符设备。当应用程序调用open函数时，third_drv_open（）会被调用，申请注册中断处理函数，根据终端号注册buttons_irq处理函数，4个中断的处理函数是一样的，但是buttons_irq(int irq, void *dev_id)根据dev_id的不一样而进行不同的处理，dev_id里面包含了{S3C2410_GPF1, 0x01}，分别是按键的代码0x01和按键的状态， 当s3c2410_gpio_getpin(pindesc->pin)为1时，说明按键松开，没有被下拉。这样就可以根据dev_id来判断哪个引脚状态是按下还是松开。用ev_press=1表示发生了中断。应用程序中用read函数时它会调用third_drv_read，当没有按键按下时，程序休眠，当中断发生时，用ev_press=1，wait_event_interruptible(button_waitq, ev_press)来唤醒read，把读到的按键值传入到用户的buf中去。

简单的说，就是当用户用读函数时，此时还没有按键按下，read函数sleep，当用中断发生时，中断函数先处理，判断中断引脚，然后ev_press=1，去唤醒read函数。

这就是此程序的思想！