驱动框架

#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/fs.h>
#include <linux/cdev.h>

//定义一个字符设备对象
struct cdev *cdev; 
dev_t dev;
unsigned int baseminor = 0;
unsigned int count = 1;
const char * name = "demochar";



//向上层提供的接口
//向下层操作硬件----在接口里去操作硬件

const struct file_operations fops = {

};

static int __init demo_init(void)
{
    int retval;
    printk("----%s---%d.\n",__func__,__LINE__);

    //1、为字符设备分配空间
    cdev = cdev_alloc();
    if(cdev == NULL){
        printk("cdev_alloc faild.\n");
        return -ENOMEM;
    }

    //2、初始化字符设备
    cdev_init(cdev,&fops);

    //3、动态申请设备号存储在dev内
    retval = alloc_chrdev_region(&dev, baseminor, count, name);
    if(retval){
        printk("alloc_chrdev_region faild.\n");
        goto err0;
    }
    printk("major :%d.\n",MAJOR(dev));

    //4、添加到内核
    retval = cdev_add(cdev, dev, count);
    if(retval){
        printk("cdev_add failed.\n");
        goto err1;
    }
    
    //5、硬件初始化

    
    return 0;

err1:
    unregister_chrdev_region(dev, count);
err0:
    return retval;
    
}

static void __exit demo_exit(void)
{
    printk("----%s---%d.\n",__func__,__LINE__);

    cdev_del(cdev);
    unregister_chrdev_region(dev, count);

}

//入口函数
module_init(demo_init);
//出口函数
module_exit(demo_exit);
//GPL许可协议
MODULE_LICENSE("GPL");