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, 21 insertions, 5 deletions

diff --git a/drivers/char/moxa.c b/drivers/char/moxa.c
index 12d327a2c9ba..8b0da97d5293 100644
--- a/drivers/char/moxa.c
+++ b/drivers/char/moxa.c
@@ -206,6 +206,7 @@ static void moxa_poll(unsigned long);
 static void moxa_set_tty_param(struct tty_struct *, struct ktermios *);
 static void moxa_setup_empty_event(struct tty_struct *);
 static void moxa_shut_down(struct tty_struct *);
+static int moxa_carrier_raised(struct tty_port *);
 /*
  * moxa board interface functions:
  */
@@ -405,6 +406,10 @@ static const struct tty_operations moxa_ops = {
         .tiocmset = moxa_tiocmset,
 };
 
+static const struct tty_port_operations moxa_port_ops = {
+        .carrier_raised = moxa_carrier_raised,
+};
+
 static struct tty_driver *moxaDriver;
 static DEFINE_TIMER(moxaTimer, moxa_poll, 0, 0);
 static DEFINE_SPINLOCK(moxa_lock);
@@ -826,6 +831,7 @@ static int moxa_init_board(struct moxa_board_conf *brd, struct device *dev)
 
         for (i = 0, p = brd->ports; i < MAX_PORTS_PER_BOARD; i++, p++) {
                 tty_port_init(&p->port);
+                p->port.ops = &moxa_port_ops;
                 p->type = PORT_16550A;
                 p->cflag = B9600 | CS8 | CREAD | CLOCAL | HUPCL;
         }
@@ -1115,15 +1121,27 @@ static void moxa_close_port(struct tty_struct *tty)
         tty_port_tty_set(&ch->port, NULL);
 }
 
+static int moxa_carrier_raised(struct tty_port *port)
+{
+        struct moxa_port *ch = container_of(port, struct moxa_port, port);
+        int dcd;
+
+        spin_lock_bh(&moxa_lock);
+        dcd = ch->DCDState;
+        spin_unlock_bh(&moxa_lock);
+        return dcd;
+}
+
 static int moxa_block_till_ready(struct tty_struct *tty, struct file *filp,
                             struct moxa_port *ch)
 {
+        struct tty_port *port = &ch->port;
         DEFINE_WAIT(wait);
         int retval = 0;
         u8 dcd;
 
         while (1) {
-                prepare_to_wait(&ch->port.open_wait, &wait, TASK_INTERRUPTIBLE);
+                prepare_to_wait(&port->open_wait, &wait, TASK_INTERRUPTIBLE);
                 if (tty_hung_up_p(filp)) {
 #ifdef SERIAL_DO_RESTART
                         retval = -ERESTARTSYS;
@@ -1132,9 +1150,7 @@ static int moxa_block_till_ready(struct tty_struct *tty, struct file *filp,
 #endif
                         break;
                 }
-                spin_lock_bh(&moxa_lock);
-                dcd = ch->DCDState;
-                spin_unlock_bh(&moxa_lock);
+                dcd = tty_port_carrier_raised(port);
                 if (dcd)
                         break;
 
@@ -1144,7 +1160,7 @@ static int moxa_block_till_ready(struct tty_struct *tty, struct file *filp,
                 }
                 schedule();
         }
-        finish_wait(&ch->port.open_wait, &wait);
+        finish_wait(&port->open_wait, &wait);
 
         return retval;
 }