#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/fs.h>
#include <linux/slab.h>
#include <linux/uaccess.h>
#include <linux/io.h>

#define CHRDEV_MAJOR      200           //主设备号
#define CHRDEV_NAME     "chrdev"    //名字

static char readbuf[100]; /*读缓冲 */
static char writebuf[100];  /* 写缓冲 */
static char kerneldata[] = {"kernel data!"};


static int chrdev_open(struct inode *inode, struct file *filp)
{
   // printk("chrdev_open\r\n");
    return 0;
}

static int chrdev_release(struct inode *inode, struct file *filp)
{
   // printk("chrdev_release\r\n");
    return 0;   
}

static ssize_t chrdev_read(struct file *filp, __user char *buf, size_t count,
			loff_t *ppos)
{ 
    int ret  = 0;
    //printk("chrdev_read\r\n");
    memcpy(readbuf, kerneldata, sizeof(kerneldata));
    ret = copy_to_user(buf, readbuf, count);
    if(ret == 0) {

    } else {


    }


    return 0;  
}

static ssize_t chrdev_write(struct file *filp, const char __user *buf,
			 size_t count, loff_t *ppos)
{
    int ret = 0;
    //printk("chrdev_write\r\n");
    ret = copy_from_user(writebuf, buf, count);
    if(ret == 0) {
        printk("kernel recevdata:%s\r\n", writebuf);
    } else {
 
    }


    return 0; 
}

/*
 * 字符设备 操作集合
 */
static struct file_operations chrdev_fops={
    .owner = THIS_MODULE,
    .open = chrdev_open,
    .release = chrdev_release,
    .read = chrdev_read,
    .write = chrdev_write,
};


static int __init chrdev_init(void)
{
    int ret = 0;
    printk("chrdev_init\r\n");

    /* 注册字符设备 */
    ret = register_chrdev(CHRDEV_MAJOR, CHRDEV_NAME, &chrdev_fops);
    if(ret < 0) {
        printk("chrdev init failed!\r\n");
    }

	return 0;
}

static void __exit chrdev_exit(void)
{
    printk("chrdev_exit\r\n");	
    /* 注销字符设备 */
    unregister_chrdev(CHRDEV_MAJOR, CHRDEV_NAME);

}

/*
 模块入口与出口
 */
module_init(chrdev_init);  /* 入口 */
module_exit(chrdev_exit);  /* 出口 */

MODULE_LICENSE("GPL");      
MODULE_AUTHOR("zkw");