在dev目录创建一个字符设备驱动的流程

在dev目录创建一个字符设备驱动的流程
1.struct file_operations 字符设备文件接口
```
   1:  static int mpu_open(struct inode *inode, struct file *file)
```
```
   2:  {    
```
```
   3:      return 0;
```
```
   4:  }
```
```
   5:   
```
```
   6:   
```
```
   7:   
```
```
   8:  static int mpu_close(struct inode *inode, struct file *file)
```
```
   9:  {
```
```
  10:      return 0;
```
```
  11:  }
```
```
  12:   
```
```
  13:   
```
```
  14:  static long mpu_ioctl ( struct file *filp, unsigned int cmd, unsigned long arg)
```
```
  15:  {
```
```
  16:      return 0;
```
```
  17:  }
```
```
  18:   
```
```
  19:  static ssize_t mpu_read(struct file * filp, char __user *buffer, size_t size, loff_t *off)
```
```
  20:  {
```
```
  21:      return 0;
```
```
  22:  }
```
```
  23:   
```
```
  24:  static ssize_t mpu_write(struct file *filp, const char __user *buffer, size_t size, loff_t *off)
```
```
  25:  {
```
```
  26:      return 0;
```
```
  27:  }
```
```
//结构
```
```
   1:  struct file_operations mpu_ops = {
```
```
   2:      .owner =  THIS_MODULE,
```
```
   3:      .open =   mpu_open,
```
```
   4:      .unlocked_ioctl =  mpu_ioctl,
```
```
   5:      .release = mpu_close, 
```
```
   6:      .read = mpu_read,
```
```
   7:      .write = mpu_write,
```
```
   8:  };
```
```
 
```
```
 
```
```
2.向内核注册字符设备框架
```
1: //根据设备号与设备名注册字符设备
2: ret = register_chrdev(253, "dt-mpu", &mpu_ops);
3: if (ret < 0) {
4: printk("Unable to register character device %d! ", 253);
5: return ret;
6: }
3.在/sys/class下面注册一个类
```
   1:  mcls = class_create(THIS_MODULE, "dt-mpu"); 
```
```
   2:      if (!mcls) {
```
```
   3:          printk("class_create dt-mpu failure...
");
```
```
   4:          goto un_register;
```
```
   5:      }
```
```
 
```
4.在/dev/目录创建dt-mpu设备文件
```
 //创建一个设备节点，节点名为DEVICE_NAME
    dev = device_create(mcls, NULL, MKDEV(253, 0), NULL, "dt-mpu");
    if (!dev) {
        printk("device_create dt-mpu failure...
");
        goto des_class;
    }
```
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原文地址：https://www.cnblogs.com/xuyh/p/5984737.html