linux驱动之中断方式获取键值

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回想在单片机下的中断处理

分辨是哪个中断
调用处理函数
清中断

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1、中断框架

trap_int 中构造

trap_int函数就是一些跳转指令

b...

b vector_irq + stubs_offset ;vector_irq是链接地址 stubs_offset 是偏移地址

vector_irq：

保存被中断的现场
asm_do_IRQ
恢复现场
。

。。

asm_do_IRQ：

对中断的处理。

request_irq 注冊中断

request_irq(irq,handle,irqflags,devname,dev_id)

1、分配irqaction 结构

2、setup_irq(irq,action)

0、分配一个irqaction 结构

a、在irq_desc[irq] -> action

b、desc -> chip ->settype

c、desc -> chip -> startup /enable

irq	要申请的硬件中断号	+
handle	是向系统登记的中断处理函数	是一个回调函数，主哦功能短发生时，系统将调用这个函数，并将dev_id传递给它
irqflags	是中断处理属性

free_irq 卸载中断

free_irq(irq, dev_id)

1、出链

2、禁止中断

2、代码编写

1、申请IRQ

这里我要特殊说明下：（向我这样的小白在使用request_irq这个函数时遇到了一个问题就是 IRQ_EINT1、IRQ_EINT4、IRQ_EINT2、IRQ_EINT0这四个宏找不到，终于原因找到了。我配置eclipse的时候内核树的路径有些小问题。

irqs.h这个文件是在 /linux-2.6.30.4/arch/arm/mach-s3c2410/include
这个路径下。我以为这个在mach-s3c2440也会有这个路径呢。事实上不然。另一些引脚的定义也在2410的路径里面，这里要注意一下）。

	request_irq(IRQ_EINT1,buttons_irq, IRQ_TYPE_EDGE_BOTH,"key1",&pins_desc[0]);

	request_irq(IRQ_EINT4,buttons_irq, IRQ_TYPE_EDGE_BOTH,"key2",&pins_desc[1]);

	request_irq(IRQ_EINT2,buttons_irq, IRQ_TYPE_EDGE_BOTH,"key3",&pins_desc[2]);

	request_irq(IRQ_EINT0,buttons_irq, IRQ_TYPE_EDGE_BOTH,"key4",&pins_desc[3]);

这里的pins_desc 是一个结构体数组

struct pin_desc pins_desc[4] =

{

	{S3C2410_GPF1,0x01},

	{S3C2410_GPF4,0x02},

	{S3C2410_GPF2,0x03},

	{S3C2410_GPF0,0x04},

};

这个数组里面包括了这四个中断引脚和该引脚的键值。

结构体原型是这种：

struct pin_desc{

	unsigned int pin;

	unsigned int key_value;

};

2、写中断处理函数

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

	{

		keyval = 0x80|pindesc->key_value;

	}

	else

	{

		keyval = pindesc->key_value;

	}

	ev_press =1;//中断发生

	wake_up_interruptible(&button_wait_q);

	printk("button is pressed : %d \n",irq);

	return IRQ_HANDLED;

}

说明：

pindesc :这个结构体会得知是哪个按键按下了

s3c2410_gpio_getpin：这个函数是内核提供的函数，能够获得当前引脚的高低电平

ev_press:中断事件标志。中断服务程序将他置1，read函数将他置0

wake_up_interruptible(&button_wait_q); 会唤醒休眠的进程，唤醒注冊到等待队列上的进程，当中 button_wait_q是通过例如以下方式获得的：

static DECLARE_WAIT_QUEUE_HEAD(button_wait_q);
生成一个等待队列头wait_queue_head_t,名字为 button_wait_q

3、改动read函数

ssize_t button_dev_read(struct file *file,char __user *buf,size_t size,loff_t *ppos)

{

	if(size !=1)

	{

		return -EINVAL;

	}

	/*假设没有按键动作发生  就休眠*/

	wait_event_interruptible(button_wait_q,ev_press);

	/*假设有按键动作发生，直接返回*/

	copy_to_user(buf,&keyval,1);

	ev_press = 0;

	return 0;

}

当中：

wait_event_interruptible(button_wait_q,ev_press); 假设ev_press是假的话。就会休眠

ev_press =0; 每次读完，都将中断事件标志清零。

4、填充file_operations结构体

static struct file_operations button_sdv_fops =

{

	.owner 		= THIS_MODULE,

	.open  		= button_dev_open,

	.read 		= button_dev_read,

	.release 	= button_dev_close,

};

当中button_dev_close函数为：

int button_dev_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;

}

free_irq为释放中断。当中须要两个參数。

本代码在上一篇按键的博文基础上改动。

完整的驱动代码：

#include <linux/init.h>

#include <linux/module.h>

#include <linux/kernel.h>

#include <linux/fs.h>

#include <asm/io.h>

#include <linux/cdev.h>

#include <linux/device.h>

#include <linux/irq.h>

#include <asm/uaccess.h>

#include <asm/irq.h>

#include <mach/regs-gpio.h>

#include <mach/irqs.h>//这个在/opt/EmbedSky/linux-2.6.30.4/arch/arm/mach-s3c2410/include/mach 路径

#include <linux/interrupt.h>

MODULE_LICENSE("Dual BSD/GPL");

static struct class *buttondrv_class;

static struct class_devices *buttondrv_class_dev;

/*  */

static DECLARE_WAIT_QUEUE_HEAD(button_wait_q);

/*中断事件标志，中断服务程序将他置1，read函数将他置0*/

static volatile int ev_press =0;

volatile unsigned long *gpfcon = NULL;

volatile unsigned long *gpfdat = NULL;

static unsigned keyval;

struct pin_desc{

	unsigned int pin;

	unsigned int key_value;

};

/*按键按下时是：0x01 0x02 0x03 0x04*/

/*按键松开时是：0x81 0x82 0x83 0x84*/

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

	{

		keyval = 0x80|pindesc->key_value;

	}

	else

	{

		keyval = pindesc->key_value;

	}

	ev_press =1;//中断发生

	wake_up_interruptible(&button_wait_q);

	printk("button is pressed : %d \n",irq);

	return IRQ_HANDLED;

}

static int button_dev_open(struct inode *inode ,struct file* file)

{

	//配置按键的引脚 GPF0,1,2,4为输入引脚

	request_irq(IRQ_EINT1,buttons_irq, IRQ_TYPE_EDGE_BOTH,"key1",&pins_desc[0]);

	request_irq(IRQ_EINT4,buttons_irq, IRQ_TYPE_EDGE_BOTH,"key2",&pins_desc[1]);

	request_irq(IRQ_EINT2,buttons_irq, IRQ_TYPE_EDGE_BOTH,"key3",&pins_desc[2]);

	request_irq(IRQ_EINT0,buttons_irq, IRQ_TYPE_EDGE_BOTH,"key4",&pins_desc[3]);

	return 0;

}

ssize_t button_dev_read(struct file *file,char __user *buf,size_t size,loff_t *ppos)

{

	if(size !=1)

	{

		return -EINVAL;

	}

	/*假设没有按键动作发生  就休眠*/

	wait_event_interruptible(button_wait_q,ev_press);

	/*假设有按键动作发生，直接返回*/

	copy_to_user(buf,&keyval,1);

	ev_press = 0;

	return 0;

}

int button_dev_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 button_sdv_fops =

{

	.owner 		= THIS_MODULE,

	.open  		= button_dev_open,

	.read 		= button_dev_read,

	.release 	= button_dev_close,

};

int major;

static int button_dev_init(void)//入口函数

{

	major = register_chrdev(0,"button_drv",&button_sdv_fops);

	buttondrv_class = class_create(THIS_MODULE,"button_drv");

	if(IS_ERR(buttondrv_class))

		return PTR_ERR(buttondrv_class);

	buttondrv_class_dev= device_create(buttondrv_class,NULL,MKDEV(major,0),NULL,"wq_button");

		if(unlikely(IS_ERR(buttondrv_class_dev)))

			return PTR_ERR(buttondrv_class_dev);

	/*映射物理地址*/

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

	gpfdat = gpfcon + 1;

	return 0;

}

static void button_dev_exit(void)

{

	unregister_chrdev(major,"button_drv");

	device_unregister(buttondrv_class_dev);

	class_destroy(buttondrv_class);

	iounmap(gpfcon);

}

module_init(button_dev_init);

module_exit(button_dev_exit);

測试代码：

#include <sys/types.h>

#include <sys/stat.h>

#include <fcntl.h>

#include <stdio.h>

/*

 * wq_device <dev> <on|off>

 */

int main(int argc, char **argv)

{

	int cnt=0;

	int fd;

	unsigned char key_val;

	fd = open("/dev/wq_button",	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;

}