USB: serial: add wait_until_sent operation

Add wait_until_sent operation which can be used to wait for hardware
buffers to drain.

Signed-off-by: Johan Hovold <jhovold@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 1 insertions, 0 deletions

diff --git a/include/linux/usb/serial.h b/include/linux/usb/serial.h
index b9b0f7b4e43b..afbb7eeaac5f 100644
--- a/include/linux/usb/serial.h
+++ b/include/linux/usb/serial.h
@@ -268,6 +268,7 @@ struct usb_serial_driver {
                         struct usb_serial_port *port, struct ktermios *old);
         void (*break_ctl)(struct tty_struct *tty, int break_state);
         int  (*chars_in_buffer)(struct tty_struct *tty);
+        void (*wait_until_sent)(struct tty_struct *tty, long timeout);
         void (*throttle)(struct tty_struct *tty);
         void (*unthrottle)(struct tty_struct *tty);
         int  (*tiocmget)(struct tty_struct *tty);