USB: serial: hook up reset_resume callback

The callback is now hooked up for any USB to serial driver that wants
it.  We only register the callback if any of the usb-serial structures
want it, this keeps the USB core happy.

Thanks to Alan Stern for the ideas on how to do this.

Cc: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/usb/serial/usb-serial.c

 /*
  * USB Serial Converter driver
  *
- * Copyright (C) 1999 - 2005 Greg Kroah-Hartman (greg@kroah.com)
+ * Copyright (C) 1999 - 2012 Greg Kroah-Hartman (greg@kroah.com)
  * Copyright (C) 2000 Peter Berger (pberger@brimson.com)
  * Copyright (C) 2000 Al Borchers (borchers@steinerpoint.com)
  *
@@ -1166,6 +1166,20 @@ int usb_serial_resume(struct usb_interface *intf)
 }
 EXPORT_SYMBOL(usb_serial_resume);
 
+static int usb_serial_reset_resume(struct usb_interface *intf)
+{
+	struct usb_serial *serial = usb_get_intfdata(intf);
+	int rv;
+
+	serial->suspending = 0;
+	if (serial->type->reset_resume)
+		rv = serial->type->reset_resume(serial);
+	else
+		rv = usb_serial_generic_resume(serial);
+
+	return rv;
+}
+
 static const struct tty_operations serial_ops = {
 	.open =			serial_open,
 	.close =		serial_close,
@@ -1403,6 +1417,14 @@ int usb_serial_register_drivers(struct usb_serial_driver *const serial_drivers[]
 	udriver->resume = usb_serial_resume;
 	udriver->probe = usb_serial_probe;
 	udriver->disconnect = usb_serial_disconnect;
+
+	/* we only set the reset_resume field if the serial_driver has one */
+	for (sd = serial_drivers; *sd; ++sd) {
+		if ((*sd)->reset_resume)
+			udriver->reset_resume = usb_serial_reset_resume;
+			break;
+	}
+
 	rc = usb_register(udriver);
 	if (rc)
 		return rc;

include/linux/usb/serial.h

 /*
  * USB Serial Converter stuff
  *
- *	Copyright (C) 1999 - 2005
+ *	Copyright (C) 1999 - 2012
  *	    Greg Kroah-Hartman (greg@kroah.com)
  *
  *	This program is free software; you can redistribute it and/or modify
@@ -249,6 +249,7 @@ struct usb_serial_driver {
 
 	int (*suspend)(struct usb_serial *serial, pm_message_t message);
 	int (*resume)(struct usb_serial *serial);
+	int (*reset_resume)(struct usb_serial *serial);
 
 	/* serial function calls */
 	/* Called by console and by the tty layer */