#include <linux/module.h>

#include <linux/fs.h>

#include <linux/cdev.h>

#include <linux/device.h>

#include <asm/uaccess.h>

#define TEMPLATE "template"

static char hello_string[]="Hello World\n";

static dev_t template_dev_number;

static struct cdev *driver_object;

struct class *template_class;

static struct device *template_dev;

static int template_open(struct inode *gerate_datei, struct file *instanz)

{

dev_info(template_dev, "template_open called\n");

return 0;

}

static int template_read(struct file *instanz, char __user *user, size_t count, loff_t *offset)

{

dev_info(template_dev, "template_read called\n");

unsigned long not_copied, to_copy;

to_copy=min(count, strlen(hello_string)+1 );

not_copied=copy_to_user(user, hello_string, to_copy);

*offset += to_copy-not_copied;

return to_copy-not_copied;

}

static struct file_operations fops = {

.owner= THIS_MODULE,

.read= template_read,

.open= template_open,

// .release=template_close,

};

static int __init template_init(void)

{

printk( "\t registering %s\n", TEMPLATE);

if (alloc_chrdev_region(&template_dev_number, 0, 1, TEMPLATE)<0)

return -EIO;

driver_object = cdev_alloc();

if (driver_object==NULL)

goto free_device_number;

driver_object->owner = THIS_MODULE;

driver_object->ops = &fops;

if(cdev_add(driver_object, template_dev_number, 1))

goto free_cdev;

template_class = class_create(THIS_MODULE, TEMPLATE);

if(IS_ERR(template_class))

goto free_cdev;

template_dev=device_create(template_class, NULL, template_dev_number, NULL, "%s", TEMPLATE);

if(IS_ERR(template_dev)){

pr_err("hello: device create failed\n");

goto free_class;

}

printk( "\t registering %s complete\n", TEMPLATE);

return 0;

free_class:

class_destroy(template_class);

free_cdev:

kobject_put(&driver_object->kobj);

free_device_number:

unregister_chrdev_region(template_dev_number, 1);

return -EIO;

}

static void __exit template_exit(void)

{

device_destroy(template_class, template_dev_number);

class_destroy(template_class);

cdev_del(driver_object);

unregister_chrdev_region(template_dev_number, 1);

printk( "\t unregister complete\n");

return;

}

module_init(template_init);

module_exit(template_exit);

MODULE_LICENSE("GPL");