2 * Copyright (C) 2010 Thadeu Lima de Souza Cascardo <cascardo@holoscopio.com>
4 * This program is free software; you can redistribute it and/or modify
5 * it under the terms of the GNU General Public License as published by
6 * the Free Software Foundation; either version 2 of the License, or
7 * (at your option) any later version.
9 * This program is distributed in the hope that it will be useful,
10 * but WITHOUT ANY WARRANTY; without even the implied warranty of
11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
12 * GNU General Public License for more details.
14 * You should have received a copy of the GNU General Public License along
15 * with this program; if not, write to the Free Software Foundation, Inc.,
16 * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
19 #include <linux/module.h>
21 #include <linux/cdev.h>
22 #include <linux/slab.h>
23 #include <linux/spinlock.h>
24 #include <linux/timer.h>
26 MODULE_LICENSE("GPL");
29 static struct cdev *dev;
30 static const char default_greeting[] = "Hello, World!\n";
32 static DEFINE_SPINLOCK(hello_lock);
34 static int hello_open(struct inode *ino, struct file *fp)
39 static void hello_world(unsigned long greeting)
41 printk(KERN_INFO "%s", (char *) greeting);
44 static struct timer_list hello_timer;
45 static ssize_t hello_read(struct file *fp, char __user *buf, size_t sz,
48 printk(KERN_INFO "Adding timer...\n");
49 init_timer(&hello_timer);
50 hello_timer.expires = jiffies + 5 * HZ;
51 hello_timer.function = hello_world;
52 hello_timer.data = (unsigned long) default_greeting;
53 add_timer(&hello_timer);
57 static ssize_t hello_write(struct file *fp, const char __user *buf, size_t sz,
63 static int hello_release(struct inode *ino, struct file *fp)
68 static const struct file_operations hello_fops = {
71 .release = hello_release,
76 static int __init ch_init(void)
79 r = alloc_chrdev_region(&devnum, 0, 256, "hello");
87 dev->ops = &hello_fops;
88 r = cdev_add(dev, devnum, 256);
91 printk(KERN_DEBUG "Allocate major %d\n", MAJOR(devnum));
96 unregister_chrdev_region(devnum, 256);
101 static void __exit ch_exit(void)
104 unregister_chrdev_region(devnum, 256);
107 module_init(ch_init);
108 module_exit(ch_exit);