Create char device.

diff --git a/hellochar.c b/hellochar.c
index e50ac2a..c2eecef 100644 (file)
--- a/hellochar.c
+++ b/hellochar.c
@@ -18,22 +18,54 @@
 
 #include <linux/module.h>
 #include <linux/fs.h>
+#include <linux/cdev.h>
+#include <linux/slab.h>
 
 MODULE_LICENSE("GPL");
+
 static dev_t devnum;
+static struct cdev *dev;
+
+static int hello_open(struct inode *ino, struct file *fp)
+{
+       printk(KERN_DEBUG "Hello, World!\n");
+       return 0;
+}
+
+static const struct file_operations hello_fops = {
+       .owner = THIS_MODULE,
+       .open = hello_open,
+};
 
 static int __init ch_init(void)
 {
-       int r;
+       int r = 0;
        r = alloc_chrdev_region(&devnum, 0, 256, "hello");
        if (r)
-               return r;
+               goto out;
+       dev = cdev_alloc();
+       if (!dev) {
+               r = -ENOMEM;
+               goto cdev_out;
+       }
+       dev->ops = &hello_fops;
+       r = cdev_add(dev, devnum, 256);
+       if (r)
+               goto add_out;
        printk(KERN_DEBUG "Allocate major %d\n", MAJOR(devnum));
        return 0;
+add_out:
+       kfree(dev);
+cdev_out:
+       unregister_chrdev_region(devnum, 256);
+out:
+       return r;
 }
 
 static void __exit ch_exit(void)
 {
+       cdev_del(dev);
+       kfree(dev);
        unregister_chrdev_region(devnum, 256);
 }