[PATCH] TTY: return class device pointer from tty_register_device()

Let tty_register_device() return a pointer to the class device it creates.
This allows registrants to add their own sysfs files under the class
device node.
Signed-off-by: Hansjoerg Lipp <hjlipp@web.de>
Signed-off-by: Tilman Schmidt <tilman@imap.cc>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

drivers/char/tty_io.c

@@ -2961,12 +2961,14 @@ static struct class *tty_class;
  *	This field is optional, if there is no known struct device for this
  *	tty device it can be set to NULL safely.
  *
+ * Returns a pointer to the class device (or ERR_PTR(-EFOO) on error).
+ *
  * This call is required to be made to register an individual tty device if
  * the tty driver's flags have the TTY_DRIVER_NO_DEVFS bit set.  If that
  * bit is not set, this function should not be called.
  */
-void tty_register_device(struct tty_driver *driver, unsigned index,
-			 struct device *device)
+struct class_device *tty_register_device(struct tty_driver *driver,
+					 unsigned index, struct device *device)
 {
 	char name[64];
 	dev_t dev = MKDEV(driver->major, driver->minor_start) + index;
@@ -2974,7 +2976,7 @@ void tty_register_device(struct tty_driver *driver, unsigned index,
 	if (index >= driver->num) {
 		printk(KERN_ERR "Attempt to register invalid tty line number "
 		       " (%d).\n", index);
-		return;
+		return ERR_PTR(-EINVAL);
 	}
 
 	devfs_mk_cdev(dev, S_IFCHR | S_IRUSR | S_IWUSR,
@@ -2984,7 +2986,8 @@ void tty_register_device(struct tty_driver *driver, unsigned index,
 		pty_line_name(driver, index, name);
 	else
 		tty_line_name(driver, index, name);
-	class_device_create(tty_class, NULL, dev, device, "%s", name);
+
+	return class_device_create(tty_class, NULL, dev, device, "%s", name);
 }
 
 /**

include/linux/tty.h

@@ -290,7 +290,9 @@ extern int tty_register_ldisc(int disc, struct tty_ldisc *new_ldisc);
 extern int tty_unregister_ldisc(int disc);
 extern int tty_register_driver(struct tty_driver *driver);
 extern int tty_unregister_driver(struct tty_driver *driver);
-extern void tty_register_device(struct tty_driver *driver, unsigned index, struct device *dev);
+extern struct class_device *tty_register_device(struct tty_driver *driver,
+						unsigned index,
+						struct device *dev);
 extern void tty_unregister_device(struct tty_driver *driver, unsigned index);
 extern int tty_read_raw_data(struct tty_struct *tty, unsigned char *bufp,
 			     int buflen);