From b6af013197d7fd10c5a647e60acef13e5e2a6bac Mon Sep 17 00:00:00 2001
From: Thadeu Lima de Souza Cascardo <cascardo@holoscopio.com>
Date: Wed, 9 Dec 2009 08:59:09 -0200
Subject: [PATCH] Change to misc device.

---
 helloc.c | 85 +++++++++++++++++---------------------------------------
 1 file changed, 25 insertions(+), 60 deletions(-)

diff --git a/helloc.c b/helloc.c
index b0271df..afcca83 100644
--- a/helloc.c
+++ b/helloc.c
@@ -8,6 +8,7 @@
 #include <linux/slab.h>
 #include <linux/proc_fs.h>
 #include <linux/seq_file.h>
+#include <linux/miscdevice.h>
 
 MODULE_LICENSE("GPL");
 MODULE_AUTHOR("Thadeu Lima de Souza Cascardo <cascardo@holoscopio.com>");
@@ -15,7 +16,6 @@ MODULE_DESCRIPTION("A hello world char device");
 MODULE_VERSION("1.0.0");
 
 #define BUFFER_SIZE 4096
-#define DEVICE_NUMBER 2
 
 struct message {
 	char *text;
@@ -23,15 +23,13 @@ struct message {
 };
 
 /* Message buffer we send to upstream */
-static struct message *hello_message[DEVICE_NUMBER];
+static struct message *hello_message;
 
 static int helloc_open(struct inode *ino, struct file *filp)
 {
 	struct message *msg;
 	printk(KERN_INFO "Opened file with minor %d\n", iminor(ino));
-	if (iminor(ino) >= DEVICE_NUMBER)
-		return -ENODEV;
-	msg = hello_message[iminor(ino)];
+	msg = hello_message;
 	filp->private_data = msg;
 	if (filp->f_flags & O_TRUNC) {
 		memset(msg->text, 0, msg->len);
@@ -119,7 +117,7 @@ static int hello_len_show(struct seq_file *seq, void *data)
 
 static int hello_proc_open(struct inode *ino, struct file *filp)
 {
-	return single_open(filp, hello_len_show, hello_message[0]);
+	return single_open(filp, hello_len_show, hello_message);
 }
 
 static struct file_operations hello_proc_fops = {
@@ -130,91 +128,58 @@ static struct file_operations hello_proc_fops = {
 	.release = seq_release,
 };
 
-
-/* the device number and the char device struct */
-static dev_t dev;
-static struct cdev *cdev;
-
 static void helloc_free(void)
 {
-	int i;
-	for (i = 0; i < DEVICE_NUMBER; i++) {
-		if (hello_message[i])
-			kfree(hello_message[i]->text);
-		kfree(hello_message[i]);
-	}
+	if (hello_message)
+		kfree(hello_message->text);
+	kfree(hello_message);
 }
 
 static int __init helloc_alloc(void)
 {
-	int i;
-	for (i = 0; i < DEVICE_NUMBER; i++) {
-		hello_message[i] = kzalloc(sizeof(struct message), GFP_KERNEL);
-		if (!hello_message[i])
-			goto out;
-		hello_message[i]->text = kzalloc(BUFFER_SIZE, GFP_KERNEL);
-		if (!hello_message[i]->text)
-			goto out;
-	}
+	hello_message = kzalloc(sizeof(struct message), GFP_KERNEL);
+	if (!hello_message)
+		return -ENOMEM;
+	hello_message->text = kzalloc(BUFFER_SIZE, GFP_KERNEL);
+	if (!hello_message->text)
+		goto out;
 	return 0;
 out:
-	for (; i >= 0; i--) {
-		if (hello_message[i])
-			kfree(hello_message[i]->text);
-		kfree(hello_message[i]);
-	}
+	kfree(hello_message);
 	return -ENOMEM;
 }
 
+static struct miscdevice hello_misc = {
+	.name = "hello",
+	.fops = &helloc_fops,
+	.minor = MISC_DYNAMIC_MINOR,
+};
+
 static int __init helloc_init(void)
 {
 	struct proc_dir_entry *hello_pde;
 	int r;
 	r = helloc_alloc();
 	if (r)
-		goto out_alloc2;
-	/* allocate any major number with only one minor */
-	r = alloc_chrdev_region(&dev, 0, DEVICE_NUMBER, "helloc");
-	if (r)
-		goto out_region;
-	r = -ENOMEM;
-	/* print the major number allocated so we can create our device node */
-	printk(KERN_INFO "Allocated major number %d\n", MAJOR(dev));
-	/* allocate the character device struct */
-	cdev = cdev_alloc();
-	if (!cdev)
 		goto out_alloc;
-	/* set the module owner and the file operations of our chardev */
-	cdev->owner = THIS_MODULE;
-	cdev->ops = &helloc_fops;
-	/* register the chardev to the system */
-	r = cdev_add(cdev, dev, DEVICE_NUMBER);
+	r = misc_register(&hello_misc);
 	if (r)
-		goto out_add;
+		goto out_reg;
 	hello_pde = proc_create("hello_len", 0666, NULL, &hello_proc_fops);
 	if (!hello_pde)
 		goto out_pde;
 	return 0;
 out_pde:
-	cdev_del(cdev);
-out_add:
-	/* release memory allocated to the cdev device */
-	kfree(cdev);
+	misc_deregister(&hello_misc);
+out_reg:
 out_alloc:
-	/* release the device number allocated */
-	unregister_chrdev_region(dev, DEVICE_NUMBER);
-out_region:
-out_alloc2:
 	return r;
 }
 
 static void __exit helloc_exit(void)
 {
 	remove_proc_entry("hello_len", NULL);
-	/* remove the chardev from the system */
-	cdev_del(cdev);
-	/* release the device number allocated */
-	unregister_chrdev_region(dev, DEVICE_NUMBER);
+	misc_deregister(&hello_misc);
 	helloc_free();
 }
 
-- 
2.20.1