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标题: arm驱动程序——按键程序4_poll（韦东山的视频总结及针对linux-2.6.30） [打印本页]

作者: 李大许 时间: 2013-6-13 15:20
标题: arm驱动程序——按键程序4_poll（韦东山的视频总结及针对linux-2.6.30）
poll机制分析在以前的都有说明了，要是不理解可以看poll机制

测试程序中都是用while(1)死循环查询，而利用poll函数可以睡眠固定时间，然后返回，也可以发生中断时唤醒

要在测试程序中用poll函数时，必须驱动程序有poll。

用到的函数及结构体：

/*file_operations中定义的，具体定义时给予具体的函数名和参数*/

unsigned int (*poll) (struct file *, struct poll_table_struct *)

/*加入队列*/

static inline void poll_wait(struct file * filp, wait_queue_head_t * wait_address,

                           poll_table *p)

驱动程序：

#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/device.h>
#include <linux/poll.h>
#include <linux/irq.h>
#include <linux/interrupt.h>
#include <asm/uaccess.h>
#include <asm/irq.h>
#include <asm/io.h>
#include <mach/irqs.h>
#include <mach/regs-gpio.h>
/*不同的linux版本，头文件会有所不同*/

static int major;
/*定义一个类*/
static struct class *second_key_class;
/*定义一个设备*/
static struct device *second_key_device;
/*定义一个等待的头文件*/
static DECLARE_WAIT_QUEUE_HEAD(button_wait_head);
/*定义一个定时器*/
struct timer_list second_key_timer;
/*中断事件标志*/
static int ev_press=0;
static unsigned int key_val;
/*定义一个引脚描述的结构体*/
struct pindec
{
unsigned int pin;
unsigned int val;
};
/*定义引脚描述的数组，
*松开按键时,值为；0x01,0x02,0x03,0x04
*按下按键时,值为; 0x81,0x82,0x83,0x84*/
static struct pindec pin_dec[4]={
{S3C2410_GPF1,0x01},

{S3C2410_GPF4,0x02},
{S3C2410_GPF2,0x03},

{S3C2410_GPF0,0x04},
};

static struct pindec *irq_dec;

static irqreturn_t button_irq(int irq,void *dev)
{
irq_dec = (struct pindec*)dev;

/*修改定时器的超时时间*/
mod_timer(&second_key_timer,jiffies+HZ/100);
return IRQ_RETVAL(IRQ_HANDLED);
}
static int second_key_poll_open(struct inode *inode, struct file *file)
{
/*注册中断*/
request_irq(IRQ_EINT1,button_irq,IRQ_TYPE_EDGE_BOTH,"s1",&pin_dec[0]);
request_irq(IRQ_EINT4,button_irq,IRQ_TYPE_EDGE_BOTH,"s2",&pin_dec[1]);
request_irq(IRQ_EINT2,button_irq,IRQ_TYPE_EDGE_BOTH,"s3",&pin_dec[2]);
request_irq(IRQ_EINT0,button_irq,IRQ_TYPE_EDGE_BOTH,"s4",&pin_dec[3]);
return 0;
}

static ssize_t second_key_poll_read(struct file *file, char __user *user_buffer,
                                 size_t count, loff_t *ppos)
{
if(count != 1)
return -EINVAL;
/*ev_press中断标志为0，休眠，即未发生中断时，休眠*/
wait_event_interruptible(button_wait_head,ev_press);
/*传数据到用户空间*/
copy_to_user(user_buffer,&key_val,1);
/*中断结束，中断标志置0，休眠*/
ev_press = 0;
return 1;
}
static unsigned int second_key_poll(struct file *file,
                                 struct poll_table_struct*wait)
{

unsigned int mask = 0;
/*挂载到队列中去*/
poll_wait(file, &button_wait_head, wait);
if(ev_press)
mask = POLLIN; /*普通或优先级带数据可读*/
return mask;
}

static int second_key_poll_close(struct inode *inode, struct file *file)
{
free_irq(IRQ_EINT1,&pin_dec[0]);
free_irq(IRQ_EINT4,&pin_dec[1]);
free_irq(IRQ_EINT2,&pin_dec[2]);
free_irq(IRQ_EINT0,&pin_dec[3]);
return 0;
}
void second_timer_function(unsigned long data)
{
unsigned int pinval;
struct pindec *pin_desc =irq_dec;
/*获得引脚状态*/
pinval=s3c2410_gpio_getpin(pin_desc->pin);
if(pinval)
      key_val = pin_desc->val;
else
      key_val = pin_desc->val|0x80;
/*唤醒*/
ev_press = 1;
wake_up_interruptible(&button_wait_head);
}
/*定义一个file_operations结构体*/
static struct file_operations second_key_poll_fops = {
.owner = THIS_MODULE,
.open  = second_key_poll_open,
.read  = second_key_poll_read,
.poll  = second_key_poll,
.release = second_key_poll_close,
};
static int second_key_init(void)
{
/*注册*/
major = register_chrdev(0,"second_key",&second_key_poll_fops);
/*创建类在/sys/class可以查找到*/
second_key_class = class_create(THIS_MODULE,"second_key_class");
/*类下创建设备可以在/sys/class/second_key_class可以查找到*/
second_key_device =
   device_create(second_key_class,NULL,MKDEV(major,0),NULL,"second_key_device");
/*初始化定时器*/
init_timer(&second_key_timer);
second_key_timer.function = second_timer_function;
/*启动定时器*/
add_timer(&second_key_timer);
return 0;
}
static void second_key_exit(void)
{
/*注销*/
unregister_chrdev(major,"second_key");
/*删除定时器*/
del_timer(&second_key_timer);
/*注销类*/
device_unregister(second_key_device);
/*销毁定义的类*/
class_destroy(second_key_class);

}
/*修饰*/
module_init(second_key_init);
module_exit(second_key_exit);
MODULE_LICENSE("GPL");

测试程序：

#include<stdio.h>
#include<unistd.h>
#include<fcntl.h>
#include<poll.h>
int main(){
int fd;
int val=1;
unsigned char key_val;
int ret;
struct pollfd fds[1];
fd=open("/dev/second_key_device",O_RDWR);
if(fd<0)
      printf("can't open!\n");

/*设置文件描述符*/
fds[0].fd=fd;

/*设置等待的事件*/
fds[0].events = POLLIN;
while(1){

   ret = poll(fds,1,5000);

   /*超时，打印信息*/

   if(ret==0){
         printf("time out\n");
}

   else{
         read(fd,&key_val,1);
         printf("key_val = 0x%x\n",key_val);
   }
}
return 0;
}

下面就是测试：

1.加载驱动程序，利用insmod

2.运行测试程序

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