The kernel uses structures of type struct cdev to represent char devices internally. Include <linux/cdev.h> so that you can use the following structures functions.
struct cdev *cdev_alloc(void); //allocate a cdev void cdev_init(struct cdev *cdev, struct file_operations *fops); //initialize it int cdev_add(sturct cdev *cdev, dev_t num, unsigned int count); //add it to kernel void cdev_del(struct cdev *dev); //remove it
Example of setuping a cdev(scull):
static void scull_setup_cdev(struct scull_dev *dev, int index)
{
int err, devno = MKDEV(scull_major, scull_minor + index);
cdev_init(&dev->cdev, &scull_fops);
dev->cdev.owner = THIS_MODULE;
dev->cdev.ops = &scull_fops;
err = cdev_add (&dev->cdev, devno, );
/* Fail gracefully if need be */
if (err)
printk(KERN_NOTICE "Error %d adding scull%d", err, index);
}
The older way to register and unregister a cdev is with:
int register_chrdev(unsigned int major, const char *name, struct file_operations *fops); int unregister_chrdev(unsigned int major, const char *name);