From: Thadeu Lima de Souza Cascardo <cascardo@holoscopio.com>
Date: Wed, 19 May 2010 14:36:34 +0000 (-0400)
Subject: Create char device.
X-Git-Url: http://git.cascardo.info/?p=cascardo%2Fkernel%2Fsamples%2Fchar2%2F.git;a=commitdiff_plain;h=0c53df020c7b9a4bade2010a3eb260c4318e48f8

Create char device.
---

diff --git a/hellochar.c b/hellochar.c
index e50ac2a..c2eecef 100644
--- 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);
 }