Linux设备驱动实现自己主动创建设备节点

#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/device.h>
#include <linux/cdev.h>
#include <linux/fs.h>
#include <linux/ioctl.h>

#define DRIVERNAME "xxx"
#define DEV_MINOR 0
static dev_t xxx_devno = 0;
static struct class * xxx_class;

struct xxx_dev
{
	struct cdev cdev;
}xxxdev;

/*-----------------------------------------------------------------------------------*/

static int xxx_open(struct inode *inode, struct file *filp)
{
	return 0;
}

static ssize_t xxx_read(struct file *filp, char __user *buf, size_t size, loff_t *ppos)
{
	return 0;
}

static ssize_t xxx_write(struct file *filp, const char __user *buf, size_t size, loff_t *ppos)
{
	return 0;
}

static int xxx_release(struct inode *inode, struct file *filp)
{
	return 0;
}

static int xxx_ioctl(struct inode *inode, struct file *filp, unsigned int cmd, unsigned long arg)
{
	int ret = 0;	

	switch (cmd)
	{
		case CPLD_VERSION:
			break;
		case CPLD_RESET:
			break;
		case CPLD_RELAY:
			break;
		case CPLD_RJ45:
			break;
		case CPLD_INTERUPT:
				break;
		case CPLD_FAN:
			break;
		default:
			printk("Error xxx cmd\n");
			break;
	}

	return 0;
}

/*-----------------------------------------------------------------------------------*/

static struct file_operations xxx_fops = {
	.owner = THIS_MODULE,
	.open = xxx_open,
	.read = xxx_read,
	.write = xxx_write,
	.ioctl = xxx_ioctl,
	.close = xxx_release,
};

static int xxx_init(void)
{
	int ret = 0;

	/*动态申请设备号*/
	ret = alloc_chrdev_region(&xxx_devno, DEV_MINOR, 1, DRIVERNAME);
	if (ret < 0)
	{
		printk("xxx register char dev failed\n");
		goto out;
	}
	/*初始化cdev结构，注冊cdev*/
	cdev_init(&(xxxdev.cdev), &xxx_fops);
	xxxdev.cdev.owner = THIS_MODULE;
	ret = cdev_add(&(xxxdev.cdev), xxx_devno, 1);
	if (ret)
	{
		printk("Error adding xxx device\n");
		goto add_err;
	}

	/*创建设备节点/sys/class/xxx和/dev/xxx*/
	xxx_class = class_create(THIS_MODULE, DRIVERNAME);
	if (IS_ERR(xxx_class))
	{
		ret = PTR_ERR(xxx_class);
		goto class_err;
	}
	device_create(xxx_class, NULL, xxx_devno, NULL, DRIVERNAME); 

	printk("xxx init\n");
	return 0;

class_err:
	cdev_del(&(xxxdev.cdev));
add_err:
	unregister_chrdev_region(xxx_devno, 1);
out:
	return ret;
}

static void xxx_exit(void)
{
	device_destroy(xxx_class, xxx_devno);
	class_destroy(xxx_class);
	cdev_del(&(xxxdev.cdev));
	unregister_chrdev_region(xxx_devno, 1);
	printk("module xxx exit\n");
}

module_init(xxx_init);
module_exit(xxx_exit);

MODULE_LICENSE("GPL");
MODULE_AUTHOR("liuwei");
MODULE_DESCRIPTION("char driver");