Create a character device-driven process in the dev directory

1.struct file_operations character Device file interface

   1:  staticint mpu_open (structstruct file *file)

   2:  {    

   3:      return 0;

   4:  }

   5:  

   6:  

   7:  

   8:  staticint mpu_close (structstruct file *file)

   9:  {

  Ten:      return 0;

One   :  }

  :  

  :  

A   :  staticlongstructintlong Arg)

  :  {

+   :      return 0;

  :  }

  :  

  :  static ssize_t mpu_read (structchar __user *buffer, size_t size, loff_t *off)

  :  {

  :      return 0;

  :  }

At   :  

  :  static ssize_t mpu_write (structconstchar __ User *buffer, size_t size, loff_t *off)

  :  {

  :      return 0;

  :  }

Structure

   1:  struct file_operations mpu_ops = {

   2:      . Owner =  This_module,

   3:      . Open =   Mpu_open,

   4:      . unlocked_ioctl =  Mpu_ioctl,

   5:      

   6:      . Read = Mpu_read,

   7:      . Write = Mpu_write,

   8:  };

2. Registering the character device framework with the kernel

   1:  //register character device  according to device number and device name

   2:      "Dt-mpu", &mpu_ops);   

   3:      if (Ret < 0) {  

   4:          PRINTK ("Unable to register character device%d!\n", 253);  

   5:          return ret;  

   6:      }  

3. Register a class under/sys/class

   1:  "Dt-mpu"

   2:      if (!mcls) {

   3:          printk ("class_create dt-mpu failure...\n");

   4:          goto un_register;

   5:      }

4. Create a Dt-mpu device file in the/dev/directory

//Create a device node with the node named Device_name    "Dt-mpu");    if (!dev) {        PRINTK ("device_create dt-mpu failure...\n");        goto des_class;    }

Create a character device-driven process in the dev directory