mxser: rework and simplify mxser_open

In mxser_open, tty->port is already set thanks to
tty_port_register_device in ->probe. So we can simply use container_of
to deduce the struct mxser_port's pointer. Thus avoiding divisions and
complex computations.

Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Link: https://lore.kernel.org/r/20210618061516.662-51-jslaby@suse.cz
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/tty/mxser.c b/drivers/tty/mxser.c
index 1e54e94..ea5e61a 100644 (file)
--- a/drivers/tty/mxser.c
+++ b/drivers/tty/mxser.c
@@ -856,15 +856,12 @@ static void mxser_shutdown_port(struct tty_port *port)
  */
 static int mxser_open(struct tty_struct *tty, struct file *filp)
 {
-       struct mxser_port *info;
-       int line = tty->index;
+       struct tty_port *tport = tty->port;
+       struct mxser_port *port = container_of(tport, struct mxser_port, port);
 
-       info = &mxser_boards[line / MXSER_PORTS_PER_BOARD].ports[line % MXSER_PORTS_PER_BOARD];
-       if (!info->ioaddr)
-               return -ENODEV;
+       tty->driver_data = port;
 
-       tty->driver_data = info;
-       return tty_port_open(&info->port, tty, filp);
+       return tty_port_open(tport, tty, filp);
 }
 
 static void mxser_flush_buffer(struct tty_struct *tty)