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

static int mpu_open(struct inode *inode, struct file *file)
{
    return 0;
}



static int mpu_close(struct inode *inode, struct file *file)
{
    return 0;
}


static long mpu_ioctl ( struct file *filp, unsigned int cmd, unsigned long arg)
{
    return 0;
}

static ssize_t mpu_read(struct file * filp, char __user *buffer, size_t size, loff_t *off)
{
    return 0;
}

static ssize_t mpu_write(struct file *filp, const char __user *buffer, size_t size, loff_t *off)
{
    return 0;
}
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   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

//根据设备号与设备名注册字符设备
    ret = register_chrdev(253, "dt-mpu", &mpu_ops);
    if (ret < 0) {
        printk("Unable to register character device %d!
", 253);
        return ret;
    }

 

3.在/sys/class下面注册一个类

mcls = class_create(THIS_MODULE, "dt-mpu");
    if (!mcls) {
        printk("class_create dt-mpu failure...
");
        goto un_register;
    }

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;
    }