[PATCH] make config_max_raw_devices work

From: "Kenneth Chen" <kenneth.w.chen@intel.com>

Even though there is a CONFIG_MAX_RAW_DEVS option, it doesn't actually
increase the number of raw devices beyond 256 because during the char
registration, it uses the standard register_chrdev() interface which has
hard coded 256 minor in it.  Here is a patch that fix this problem by using
register_chrdev_region() and cdev_(init/add/del) functions.

drivers/char/raw.c

@@ -17,6 +17,7 @@
 #include <linux/raw.h>
 #include <linux/capability.h>
 #include <linux/uio.h>
+#include <linux/cdev.h>
 
 #include <asm/uaccess.h>
 
@@ -260,11 +261,26 @@ static struct file_operations raw_ctl_fops = {
 	.owner	=	THIS_MODULE,
 };
 
+static struct cdev raw_cdev = {
+	.kobj	=	{.name = "raw", },
+	.owner	=	THIS_MODULE,
+};
+
 static int __init raw_init(void)
 {
 	int i;
+	dev_t dev = MKDEV(RAW_MAJOR, 0);
+
+	if (register_chrdev_region(dev, MAX_RAW_MINORS, "raw"))
+		goto error;
+
+	cdev_init(&raw_cdev, &raw_fops);
+	if (cdev_add(&raw_cdev, dev, MAX_RAW_MINORS)) {
+		kobject_put(&raw_cdev.kobj);
+		unregister_chrdev_region(dev, MAX_RAW_MINORS);
+		goto error;
+	}
 
-	register_chrdev(RAW_MAJOR, "raw", &raw_fops);
 	devfs_mk_cdev(MKDEV(RAW_MAJOR, 0),
 		      S_IFCHR | S_IRUGO | S_IWUGO,
 		      "raw/rawctl");
@@ -273,6 +289,10 @@ static int __init raw_init(void)
 			      S_IFCHR | S_IRUGO | S_IWUGO,
 			      "raw/raw%d", i);
 	return 0;
+
+error:
+	printk(KERN_ERR "error register raw device\n");
+	return 1;
 }
 
 static void __exit raw_exit(void)
@@ -283,7 +303,8 @@ static void __exit raw_exit(void)
 		devfs_remove("raw/raw%d", i);
 	devfs_remove("raw/rawctl");
 	devfs_remove("raw");
-	unregister_chrdev(RAW_MAJOR, "raw");
+	cdev_del(&raw_cdev);
+	unregister_chrdev_region(MKDEV(RAW_MAJOR, 0), MAX_RAW_MINORS);
 }
 
 module_init(raw_init);