较为基础的linux设备驱动

潇洒人生

驱动程序为
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
static unsigned int major = 0;
static unsigned int minor = 0;
static unsigned int devno;
static char *filename = "mydevice";
static struct cdev *mycdev = NULL;
static int mycdevflg = 0;
static int devnoflg = 0;
static int adddevflg = 0;
MODULE_LICENSE("Dual BSD/GPL");
static int myopen(struct inode *inodep, struct file *flipl)
{
printk("my open is run\n");
return 0;
}
static ssize_t myread(struct file *flip, char __user *buf, size_t size, loff_t offset)
{
printk("myread is ok!\n");
static int i = 0;
///copy_to_user(buf,from,size);
*buf = i++;
return 0;
}
static int myrelease(struct inode *myindoe, struct file *flip)
{
printk("myrelease is run.\n");
return 0;
}
static struct file_operations myfops =
{
.owner = THIS_MODULE,
.open = myopen,
.read = myread,
.release= myrelease,
};
/* 初始化设备的过程主要是三步:1,生成设备号;2初始化设备；3，添加到内核。
*/
static int __init myinit(void)
{
int result = -1;
if(major)
{
  devno = MKDEV(major,minor); //生成设备号
  result = register_chrdev_region(devno,1,filename);//注册设备号devno,1为设备的个数
  devnoflg = 1;
}
else
{
  result = alloc_chrdev_region(&devno,minor,1,filename);//生成设备号兵注册，mior为次设备号，这里注意的是指针devno?
  major = MAJOR(devno);
  devnoflg = 1;
}
if(result
//mycdev = kmalloc(sizeof(struct cdev),GFP_KERNEL);//如果采用cdev_init(struct cdev*,struct file *)方式的话，这个才需要
mycdev = cdev_alloc();//申请cdev内存兵初始化设备cdev，不能在这之前申请内存，否则要释放两次!
if(NULL == mycdev)
{
  printk("can't request the memory!\n");
}
mycdevflg = 1;
//memset(mycdev,0,sizeof(mycdev));

mycdev->owner = THIS_MODULE;//如果采用cdev_init(struct cdev*,struct file *)方式的话，这两项可以去掉
mycdev->ops = &myfops;//如果采用cdev_init(struct cdev*,struct file *)方式的话，这两项可以去掉
result = cdev_add(mycdev,devno,1);//设备和设备号联系起来，即通常说的添加设备到内核
if(result
/* 以和设备注册的次序"卸载"，注意有的时候，当出错的时候，要注意是否用到这些操作，所以要加上判断，否则比如对空指针free会导致系统崩溃!
*/
static void  myexit(void)
{
printk("myexit begin.\n");
if(adddevflg)
{
  cdev_del(mycdev);
  adddevflg = 0;
}
if(mycdev)
{
  kfree(mycdev);
  mycdev = NULL;
}
if(devnoflg)
{
  unregister_chrdev_region(devno,1);
  devno = 0;
  devnoflg = 0;
}
printk("exit over.\n");
}
module_init(myinit);
module_exit(myexit);

应用程序为
#include
#include
#include
#include
#include
int main()
{
        int fd;
        int i=0;
        fd = open("/dev/mydevice", O_RDONLY);
        if (fd


本文来自ChinaUnix博客，如果查看原文请点：http://blog.chinaunix.net/u1/55790/showart_439135.html