serial: add a new helper function

In most of the time, the driver needs to check if the cts flow control
is enabled. But now, the driver checks the ASYNC_CTS_FLOW flag manually,
which is not a grace way. So add a new wraper function to make the code
tidy and clean.

Signed-off-by: Huang Shijie <shijie8@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 6 insertions, 0 deletions

diff --git a/include/linux/tty.h b/include/linux/tty.h
index dbebd1e56bc1..9892121354cd 100644
--- a/include/linux/tty.h
+++ b/include/linux/tty.h
@@ -514,6 +514,12 @@ static inline struct tty_port *tty_port_get(struct tty_port *port)
         return port;
 }
 
+/* If the cts flow control is enabled, return true. */
+static inline bool tty_port_cts_enabled(struct tty_port *port)
+{
+        return port->flags & ASYNC_CTS_FLOW;
+}
+
 extern struct tty_struct *tty_port_tty_get(struct tty_port *port);
 extern void tty_port_tty_set(struct tty_port *port, struct tty_struct *tty);
 extern int tty_port_carrier_raised(struct tty_port *port);