tty_port: Add a port level carrier detect operation

This is the first step to generalising the various pieces of waiting logic
duplicated in all sorts of serial drivers.

Signed-off-by: Alan Cox <alan@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 9 insertions, 0 deletions

diff --git a/include/linux/tty.h b/include/linux/tty.h
index bbbeaef99626..bc7bae78e22f 100644
--- a/include/linux/tty.h
+++ b/include/linux/tty.h
@@ -180,8 +180,16 @@ struct signal_struct;
  * until a hangup so don't use the wrong path.
  */
 
+struct tty_port;
+
+struct tty_port_operations {
+        /* Return 1 if the carrier is raised */
+        int (*carrier_raised)(struct tty_port *port);
+};
+        
 struct tty_port {
         struct tty_struct       *tty;           /* Back pointer */
+        const struct tty_port_operations *ops;  /* Port operations */
         spinlock_t              lock;           /* Lock protecting tty field */
         int                     blocked_open;   /* Waiting to open */
         int                     count;          /* Usage count */
@@ -427,6 +435,7 @@ extern int tty_port_alloc_xmit_buf(struct tty_port *port);
 extern void tty_port_free_xmit_buf(struct tty_port *port);
 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);
 
 extern int tty_register_ldisc(int disc, struct tty_ldisc_ops *new_ldisc);
 extern int tty_unregister_ldisc(int disc);