linux字符设备驱动一般模板

#include <linux/miscdevice.h>  //头文件有很多，可以根据具体的情况添加删除，这里给一个例子。
#include <linux/delay.h>
#include <asm/irq.h>
#include <mach/regs-gpio.h>
#include <mach/hardware.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/mm.h>
#include <linux/fs.h>
#include <linux/types.h>
#include <linux/moduleparam.h>
#include <linux/slab.h>
#include <linux/errno.h>
#include <linux/ioctl.h>
#include <linux/cdev.h>
#include <linux/string.h>
#include <linux/list.h>
#include <linux/pci.h>
#include <linux/gpio.h>
#include <asm/uaccess.h>
#include <asm/atomic.h>
#include <asm/unistd.h>
#include <linux/device.h>

#include <plat/gpio-cfg.h>

#define DEVICE_NAME "devicename" //文件名
static int major = xxx_major;  //预定义的主设备号

struct xxx_dev_t{     //字符设备结构体
    struct cdev cdev;
}xxx_dev;//这一段和static struct cdev cdev;表达了一种意思

static struct class *xxx_class; //在驱动初始化的代码里调用class_create为该设备创建一个class，再为每个设备调用device_create创建对应的设备



static int xxx_open(struct inode *inode, struct file *filp)  //文件节点，仅有一个；file结构体，追踪文件运行时的状态信息，可为NULL
{

}
/*清理未结束的输入输出操作，释放资源，可为null*/
static int xxx_realease(struct inode *inode, struct file *filp) 
{

}
/*目标文件结构体指针；对应放置信息的缓冲区（用户空间）；要读取的信息长度；读的位置相对于文件开头的偏移*/
static ssize_t xxx_read(struct file *filp, char __user *buf, size_t len, loff_t *offset)
{

}
/*目标文件结构体指针；要写入放置信息的缓冲区；要写入的信息长度；写的位置相对于文件开头的偏移*/
static ssize_t xxx_write(struct file *filp, const char __user *buf, size_t len, loff_t *offset)
{

}

static struct file_operations xxx_fops= //文件操作结构体
{
	.owner = THIS_MODULE,
	.read = xxx_read,
	.write = xxx_writ,
	.open = xxx_open,
	.release = xxx_release,
	.ioctl = xxx_ioctl,
};

static int __init xxx_init(void) //设备驱动模块加载函数
{
   int result;
   int ret;
   dev_t xxx_dev_no = MKDEV(xxx_major,0); //由预定义的主设备号生成dev_t设备号
   if(xxx_major){
   result = register_chrdev_region(xxx_dev_no,1,DEVICE_NAME);  //静态申请设备号
   }else{
   result = alloc_chrdev_region(&xxx_dev_no,0,1,DEVICE_NAME); //动态分配设备号
   xxx_major = MAJOR(xxx_dev_no);
  }
	
  if(result<0)
  return result;
	
  cdev_init(&xxx_dev.dev,&xxx_fops); //初始化cdev结构
  xxx_dev.cdev.owner = THIS_MODULE; 
  
  ret = cdev_add(&xxx_dev.cdev,MKDEV(xxx_major,0),1); //注册字符设备
  if (ret)
    {
        printk("cdev add failed\n"); 
        goto fail1;   
    }
    
  xxx_class = class_create(THIS_MODULE,"xxx_class"); 
  if(IS_ERR(xxx_class)) 
  {
         printk("Err: failed in creating class./n");
         goto fail2;  
  } 
  device_create(xxx_class, NULL, MKDEV(xxx_major,0), NULL, DEVICE_NAME);
    return 0;

  fail2:
     cdev_del(&xxx_dev.cdev);
  fail1:
     unregister_chrdev_region(xxx_dev_no, 1);
     return result;

}

static void __exit xxx_exit(void) //设备驱动模块卸载函数
{
  device_destory(xxx_class,MKDEV(xxx_major,0));
  class_destroy(xxx_class);
  cdev_del(&xxx_dev.cdev);
  unregister_chrdev_region(MKDEV(xxx_major,0), 1);
	
}

module_init(xxx_init);
module_exit(xxx_exit);

MODULE_LICENSE("GPL");
MODULE_AUTHOR("your_name");