[PATCH] cdev-cidr, part 1

New object: struct cdev.  It contains a kobject, a pointer to
file_operations and a pointer to owner module.  These guys have a search
structure of the same sort as gendisks and chrdev_open() picks
file_operations from them.

Intended use: embed such animal in driver-owned structure (e.g.
tty_driver) and register it as associated with given range of device
numbers.  Generic code will do lookup for such object and use it for the
rest.

The behaviour of register_chrdev() is _not_ changed - it allocates
struct cdev and registers it; any old driver will work as if nothing had
changed.

On that stage we only use it during chrdev_open() to find
file_operations.  Later it will be cached in inode->i_cdev (and index in
range - in inode->i_cindex) so that ->open() could get whatever objects
it wants directly without any special-cased lookups, etc.

3 files changed, 34 insertions, 4 deletions

diff --git a/include/linux/cdev.h b/include/linux/cdev.h
new file mode 100644
index 000000000000..faa67d2f4323
--- /dev/null
+++ b/include/linux/cdev.h
@@ -0,0 +1,30 @@
+#ifndef _LINUX_CDEV_H
+#define _LINUX_CDEV_H
+#ifdef __KERNEL__
+
+struct cdev {
+	struct kobject kobj;
+	struct module *owner;
+	struct file_operations *ops;
+};
+
+void cdev_init(struct cdev *, struct file_operations *);
+
+struct cdev *cdev_alloc(void);
+
+static inline void cdev_put(struct cdev *p)
+{
+	if (p)
+		kobject_put(&p->kobj);
+}
+
+struct kobject *cdev_get(struct cdev *);
+
+int cdev_add(struct cdev *, dev_t, unsigned);
+
+void cdev_del(struct cdev *);
+
+void cdev_unmap(dev_t, unsigned);
+
+#endif
+#endif
diff --git a/include/linux/fs.h b/include/linux/fs.h
index 1b7fac010f1f..6b32c6ab8727 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -1056,10 +1056,8 @@ extern void bd_release(struct block_device *);
 extern void blk_run_queues(void);
 
 /* fs/char_dev.c */
-extern int alloc_chrdev_region(dev_t *, unsigned, char *,
-				struct file_operations *);
-extern int register_chrdev_region(dev_t, unsigned, char *,
-				struct file_operations *);
+extern int alloc_chrdev_region(dev_t *, unsigned, char *);
+extern int register_chrdev_region(dev_t, unsigned, char *);
 extern int register_chrdev(unsigned int, const char *,
 			   struct file_operations *);
 extern int unregister_chrdev(unsigned int, const char *);
diff --git a/include/linux/tty_driver.h b/include/linux/tty_driver.h
index d8d9fc435a3f..ef234da28a8c 100644
--- a/include/linux/tty_driver.h
+++ b/include/linux/tty_driver.h
@@ -117,9 +117,11 @@
 
 #include <linux/fs.h>
 #include <linux/list.h>
+#include <linux/cdev.h>
 
 struct tty_driver {
 	int	magic;		/* magic number for this structure */
+	struct cdev cdev;
 	struct module	*owner;
 	const char	*driver_name;
 	const char	*name;