USB: serial: add generic wait_until_sent implementation

Add generic wait_until_sent implementation which polls for empty
hardware buffers using the new port-operation tx_empty.

The generic implementation will be used for all sub-drivers that
implement tx_empty but does not define wait_until_sent.

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

1 files changed, 3 insertions, 0 deletions

diff --git a/include/linux/usb/serial.h b/include/linux/usb/serial.h
index afbb7eeaac5f..302ddf55d2da 100644
--- a/include/linux/usb/serial.h
+++ b/include/linux/usb/serial.h
@@ -269,6 +269,7 @@ struct usb_serial_driver {
         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);
+        bool (*tx_empty)(struct usb_serial_port *port);
         void (*throttle)(struct tty_struct *tty);
         void (*unthrottle)(struct tty_struct *tty);
         int  (*tiocmget)(struct tty_struct *tty);
@@ -328,6 +329,8 @@ extern void usb_serial_generic_close(struct usb_serial_port *port);
 extern int usb_serial_generic_resume(struct usb_serial *serial);
 extern int usb_serial_generic_write_room(struct tty_struct *tty);
 extern int usb_serial_generic_chars_in_buffer(struct tty_struct *tty);
+extern void usb_serial_generic_wait_until_sent(struct tty_struct *tty,
+                                                                long timeout);
 extern void usb_serial_generic_read_bulk_callback(struct urb *urb);
 extern void usb_serial_generic_write_bulk_callback(struct urb *urb);
 extern void usb_serial_generic_throttle(struct tty_struct *tty);