[PATCH] USB: add dev attribute for usb-serial devices in sysfs

drivers/usb/serial/bus.c

@@ -23,6 +23,17 @@
 
 #include "usb-serial.h"
 
+static ssize_t show_dev (struct device *dev, char *buf)
+{
+	struct usb_serial_port *port= to_usb_serial_port(dev);
+	dev_t base;
+
+	port = to_usb_serial_port(dev);
+
+	base = MKDEV(SERIAL_TTY_MAJOR, port->number);
+	return sprintf(buf, "%04x\n", base);
+}
+static DEVICE_ATTR(dev, S_IRUGO, show_dev, NULL);
 
 static int usb_serial_device_match (struct device *dev, struct device_driver *drv)
 {
@@ -79,6 +90,8 @@ static int usb_serial_device_probe (struct device *dev)
 	minor = port->number;
 
 	tty_register_device (&usb_serial_tty_driver, minor);
+	device_create_file (dev, &dev_attr_dev);
+
 	dev_info(&port->serial->dev->dev, 
 		 "%s converter now attached to ttyUSB%d (or usb/tts/%d for devfs)\n",
 		 driver->name, minor, minor);