#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/fs.h>
#define MYMAJOR 200
#define MYNAME "chardev"
int mymajor ;
static int test_chardev_open(struct inode *inode,struct file *file)
{
printk(KERN_INFO "test chardev_open\n");
return 0;
}
static int test_chardev_release(struct inode *inode,struct file *file){
printk(KERN_INFO "test chardev_release\n");
return 0;
}
static ssize_t test_chardev_read(struct file *file,char __user *buf,size_t size, loff_t *ppos)
{
printk(KERN_INFO " test read\n");
return 0;
}
static ssize_t test_chardev_write(struct file *file,
const char __user *ubuf,size_t count,loff_t * ppos){
printk(KERN_INFO " test write\n");
return 0;
}
static const struct file_operations test_fops={
.owner=THIS_MODULE,
.open=test_chardev_open,
.release=test_chardev_release,
.write=test_chardev_write,
.read=test_chardev_read,
};
static int __init chardev_init(void)
{ int ret=-1;
printk(KERN_INFO "jimmy module chardev init");
mymajor=register_chrdev(0,MYNAME,&test_fops); //由內核分配，然後mkdnod /dev/chardev mymajor 0生成設備文件
//注意/dev/chardev是MYNAME給出的，不能自己任意命名，這是測試發現的，與靜態指定主設備的任意命名稍微不同
if(mymajor<0)
{printk(KERN_ERR "register_chrdev fail\n");
return -EINVAL;
}
printk(KERN_INFO "register_chrdev success...myjor=%d.\n",mymajor);
return 0;
}
static void __exit chardev_exit(void)
{
printk(KERN_INFO "jimmy module chardev exit\n");
unregister_chrdev(MYMAJOR, MYNAME);
}
module_init(chardev_init);
module_exit(chardev_exit);
// MODULE_xxx這種宏作用是用來添加模塊描述信息
MODULE_LICENSE("GPL"); // 描述模塊的許可證
MODULE_AUTHOR("aston"); // 描述模塊的作者
MODULE_DESCRIPTION("module test"); // 描述模塊的介紹信息
MODULE_ALIAS("alias xxx"); // 描述模塊的別名信息