原创 linux设备驱动学习笔记8-----------蜂鸣器驱动

/*头文件*/

#include <linux/module.h>

#include <linux/types.h>

#include <linux/fs.h>

#include <linux/errno.h>

#include <linux/mm.h>

#include <linux/sched.h>

#include <linux/init.h>

#include <linux/cdev.h>

#include <linux/delay.h>

#include <asm/system.h>

#include <asm/uaccess.h>

#include <asm/io.h>

#include <asm/hardware.h>

/*一些定义*/

#define BEEP_MAJOR 245/* 主设备号*/

#define BEEP_ON 1

#define BEEP_OFF 2

/*定义了蜂鸣器操作的结构体*/

struct beep_dev

{

       struct cdev cdev;

       unsigned char value;

};

<?xml:namespace prefix = o ns = "urn:schemas-microsoft-com:office:office" />

/*定义了蜂鸣器操作的结构体的成员*/

struct beep_dev *beepdev;

/*硬件初始化函数，初始化GPIO口*/

static void sep4020_beep_setup(void)

{

*(volatile unsigned long*)GPIO_PORTA_SEL_V |= (0x1<<6); //作为通用用途

*(volatile unsigned long*)GPIO_PORTA_DIR_V &= ~(0x1<<6 );//输出

*(volatile unsigned long*)GPIO_PORTA_DATA_V &= ~(0x1<<6 );//初始输出拉低

}

/*蜂鸣器驱动的open函数*/

int sep4020_beep_open(struct inode *inode, struct file *filp)

{

sep4020_beep_setup(); 

return 0;

}

/*蜂鸣器程序的relesase函数*/

int sep4020_beep_release(struct inode *inode, struct file *filp)

{

       return 0;

}

/*蜂鸣器程序的read和write函数，

因为我们不需要使用read和write，

所以直接返回0*/

static ssize_t sep4020_beep_read(struct file *filp, char __user *buf, size_t size, loff_t *ppos)

{

       return 0;

}

static ssize_t sep4020_beep_write(struct file *filp, const char __user *buf, size_t size, loff_t *ppos)

{

       return 0;

}

/*应用程序就是通过调用ioctl这个函数来控制硬件*/

int sep4020_beep_ioctl(struct inode *inode, struct file *filp, unsigned int cmd, unsigned long arg)

{

              switch (cmd)

       {

       case BEEP_ON:

       *(volatile unsigned long*)GPIO_PORTA_DATA_V |= 0x1<<6; //beep is open;

              break;

       case BEEP_OFF:

       *(volatile unsigned long*)GPIO_PORTA_DATA_V &= ~0x1<<6; //beep is close;

              break;

       default:

              return -ENOTTY;

       }

       return 0;

}

/*将我们自己写的文件操作函数与系统提供的函数结构想挂钩*/

static const struct file_operations sep4020_beep_fops =

{

       .owner = THIS_MODULE,

       .read = sep4020_beep_read,

       .write = sep4020_beep_write,

       .ioctl = sep4020_beep_ioctl,

       .open = sep4020_beep_open,

       .release = sep4020_beep_release,

};

/*加载驱动时执行的init函数*/

static int __init sep4020_beep_init(void)

{

       int err,result;

       dev_t devno = MKDEV(BEEP_MAJOR, 0);

       if(BEEP_MAJOR)        

              result = register_chrdev_region(devno, 1, "sep4020_beep");

       else

              result = alloc_chrdev_region(&devno, 0, 1, "sep4020_beep");

       if(result < 0)

              return result; /*动态申请设备结构体的内存*/

       beepdev = kmalloc(sizeof(struct beep_dev),GFP_KERNEL);

       if (!beepdev)

       {

              result = -ENOMEM;  //如果申请失败，跳转到错误处理函数

              goto fail_malloc;

       }

       /*将结构体清空*/

       memset(beepdev,0,sizeof(struct beep_dev));

       /*注册设备进内核*/

       cdev_init(&(beepdev->cdev), &sep4020_beep_fops);

       beepdev->cdev.owner = THIS_MODULE;

       err = cdev_add(&beepdev->cdev, devno, 1);   // 创建设备文件

       if(err)

              printk("adding err\r\n");

       return 0;

       fail_malloc: unregister_chrdev_region(devno,1);

       return result;

}

/*卸载模块执行的函数*/

static void __exit sep4020_beep_exit(void)

{

       cdev_del(&beepdev->cdev);

       kfree(beepdev);

       unregister_chrdev_region(MKDEV(BEEP_MAJOR, 0),1);

}

module_init(sep4020_beep_init); //向Linux系统记录设备初始化的函数名

module_exit(sep4020_beep_exit); //向Linux系统记录设备退出的函数名称

MODULE_AUTHOR("fpmystar");

MODULE_LICENSE("GPL");

//-------------------------------------------------------------------------------------

//-------------------------------------------------------------------------------------

下面是一个蜂鸣器简单的测试程序：

#include <stdio.h>

#include <fcntl.h>

#define OPEN 1

#define CLOSE 2

int main(int argc,char **argv)

{

int fd;

int i,j;

       fd = open("/dev/beep",O_RDWR);

       if(fd == -1)

       {

              printf("wrong\r\n");

              exit(-1);

       }

       for(j=0; j<20; j++)

       {

              ioctl(fd, OPEN,0);

              for(i=0; i<1000000; i++);

              ioctl(fd, CLOSE,0);

              for(i=0; i<1000000; i++);

       }

       close(fd);

       return 0;

}