linux驱动之中断方式获取键值

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linux驱动之中断方式获取键值

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回顾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 注册中断

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：（向我这种小白在使用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，最终原因找到了，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，其实不然。还有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},};

这个数组里面包含了这四个中断引脚和该引脚的键值。

结构体原型是这样的：

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，可以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，唤醒注册到等待队列上的进程，其中 button_wait_q是通过如下方式获得的：

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、修改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;}/*如果没有按键动作发生  就休眠*/wait_event_interruptible(button_wait_q,ev_press);/*如果有按键动作发生，直接返回*/copy_to_user(buf,&keyval,1);ev_press = 0;return 0;}

其中：

wait_event_interruptible(button_wait_q,ev_press); 如果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,};

其中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，其中需要两个参数。

本代码在上一篇按键的博文基础上修改。

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;}/*如果没有按键动作发生  就休眠*/wait_event_interruptible(button_wait_q,ev_press);/*如果有按键动作发生，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);

测试代码：

#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;}

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