字符设备驱动开发流程(总结)

准备工作：

#include<linux/errno.h>
#include<linux/kernel.h>
#include<linux/module.h>
#include<linux/slab.h>
#include<linux/input.h>
#include<linux/init.h>
#include<linux/serio.h>
#include<linux/delay.h>
#include<linux/clk.h>
#include<linux/miscdevice.h>
#include<linux/gpio.h>
#include<asm/io.h>
#include<asm/irq.h>
#include<asm/uaccess.h>
#include<mach/regs-clock.h>
#include<plat/regs-timer.h>
#include<plat/gpio-cfg.h>
#include<mach/regs-gpio.h>
//#include<mach/gpio.h>
#include<linux/cdev.h>

static int beep_major=0;
MODULE_AUTHOR("LIU");
MODULE_LICENSE("Dual BSD/GPL");

#define BEEP_MAGIC 'K'
#define BEEP_START_CMD _IO(BEEP_MAGIC,1)
#define BEEP_STOP_CMD _IO(BEEP_MAGIC,2)

int beep_open(struct inode *inode,struct file *filp)
{
return 0;
}
int beep_release(struct inode *inode,struct file *filp)
{
return 0;
}
ssize_t beep_read(struct file *file,char __user *buff,size_t count,loff_t *offp)
{
return 0;
}

 ssize_t beep_write(struct file *file,const char __user *buff,size_t count,loff_t *offp)
{
return 0;
}

void beep_stop(void)
{
    //s3c_gpiolib_output(struct gpio_chip *chip,unsigned offset, int value)


    //s3c_gpio_cfgpin(S3C64XX_GPIOREG(0x008e),S3C_GPIO_OUTPUT);
      //gpio_direction_output(S3C64XX_GPF(14),0);
      s3c_gpio_cfgpin(S3C64XX_GPK(4),0);
    //s3c2410_gpio_setpin(S3C2410_GPF(14),0);
}
void beep_start(void){
    //  s3c_gpio_cfgpin(S3C64XX_GPIOREG(0x008e),S3C_GPIO_OUTPUT);
//gpio_direction_output(S3C64XX_GPK(4),1);
       s3c_gpio_cfgpin(S3C64XX_GPK(4),1);
     // s3c_gpio_setpin(S3C64XX_GPIOREG(0x008e),1);
}
static int beep_ioctl(struct file *file,unsigned int cmd,unsigned long arg)
{
   switch(cmd){
                case BEEP_START_CMD:{
                       beep_start();
                       break;
                        }
                case BEEP_STOP_CMD:{
      beep_stop();
                      break;
                       }
                default:
                      break;          
              }
                 return 0;
}

static struct file_operations beep_remap_ops={
.owner = THIS_MODULE,
.open = beep_open,  //此接口得实现
.release = beep_release, //此接口得实现
.read = beep_read, //此接口得实现
.write = beep_write, //此接口得实现
.unlocked_ioctl = beep_ioctl, //此接口得实现
};

static struct cdev BeepDevs; //声明字符设备

xxx_init(void){

        int result;

1.字符设备号的获取

dev_t dev=MKDEV（主设备号，从设备号）；

char dev_name[]="beep";//设备名

2.申请设备号：

if(beep_major)

{

result=register_chrdev_region(dev,1,dev_name);             //手动申请设备号

}

else

{

result=alloc_chrdev_region(&dev,0,1,dev_name);//如果设备号为0则自动申请，参数dev为设备号，参数0为次设备号，1为一个设备，dev_name为设备名

beep_major = MAJOR(dev);// 获取主设备号，为设备节点的创建做准备

}

if(result<0)

{

printk("beep:unable to get major %d\n",beep_major);

}

if(beep_major==0)

 beep_major=result;  

3.调整到下面函数

        beep_setup_cdev(&BeepDevs,0,&beep_remap_ops);
         printk("beep device install,with major %d\n",beep_major);
         printk("The device name is:%s\n",dev_name);
         return 0;

}

static void beep_setup_cdev(struct cdev *dev,int minor,struct file_operation *fops){
      int err,devno = MKDEV(beep_major,minor);
3.初始化字符设备
      cdev_init(dev,fops);
      dev->owner = THIS_MODULE;
      dev->ops =fops;
4.把字符设备注册进内核
err=cdev_add(dev,devno,1);
      if(err){
      printk("error %d adding beep %d",err,minor);
    }
}

static void beep_cleanup(void)
{
cdev_del(&BeepDevs);
        unregister_chrdev_region(MKDEV(beep_major,0),1);
        printk("beep driver uninstll sucess!");
}
module_init(beep_init);
module_exit(beep_cleanup);