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, 41 insertions, 20 deletions

diff --git a/drivers/char/synclink.c b/drivers/char/synclink.c
index 500f517..fb2e6b5 100644
--- a/drivers/char/synclink.c
+++ b/drivers/char/synclink.c
@@ -3281,6 +3281,23 @@ static void mgsl_hangup(struct tty_struct *tty)
 	
 }	/* end of mgsl_hangup() */
 
+/*
+ * carrier_raised()
+ *
+ *	Return true if carrier is raised
+ */
+
+static int carrier_raised(struct tty_port *port)
+{
+	unsigned long flags;
+	struct mgsl_struct *info = container_of(port, struct mgsl_struct, port);
+	
+	spin_lock_irqsave(&info->irq_spinlock, flags);
+ 	usc_get_serial_signals(info);
+	spin_unlock_irqrestore(&info->irq_spinlock, flags);
+	return (info->serial_signals & SerialSignal_DCD) ? 1 : 0;
+}
+
 /* block_til_ready()
  * 
  * 	Block the current process until the specified port
@@ -3302,6 +3319,8 @@ static int block_til_ready(struct tty_struct *tty, struct file * filp,
 	bool		do_clocal = false;
 	bool		extra_count = false;
 	unsigned long	flags;
+	int		dcd;
+	struct tty_port *port = &info->port;
 	
 	if (debug_level >= DEBUG_LEVEL_INFO)
 		printk("%s(%d):block_til_ready on %s\n",
@@ -3309,7 +3328,7 @@ static int block_til_ready(struct tty_struct *tty, struct file * filp,
 
 	if (filp->f_flags & O_NONBLOCK || tty->flags & (1 << TTY_IO_ERROR)){
 		/* nonblock mode is set or port is not enabled */
-		info->port.flags |= ASYNC_NORMAL_ACTIVE;
+		port->flags |= ASYNC_NORMAL_ACTIVE;
 		return 0;
 	}
 
@@ -3318,25 +3337,25 @@ static int block_til_ready(struct tty_struct *tty, struct file * filp,
 
 	/* Wait for carrier detect and the line to become
 	 * free (i.e., not in use by the callout).  While we are in
-	 * this loop, info->port.count is dropped by one, so that
+	 * this loop, port->count is dropped by one, so that
 	 * mgsl_close() knows when to free things.  We restore it upon
 	 * exit, either normal or abnormal.
 	 */
 	 
 	retval = 0;
-	add_wait_queue(&info->port.open_wait, &wait);
+	add_wait_queue(&port->open_wait, &wait);
 	
 	if (debug_level >= DEBUG_LEVEL_INFO)
 		printk("%s(%d):block_til_ready before block on %s count=%d\n",
-			 __FILE__,__LINE__, tty->driver->name, info->port.count );
+			 __FILE__,__LINE__, tty->driver->name, port->count );
 
 	spin_lock_irqsave(&info->irq_spinlock, flags);
 	if (!tty_hung_up_p(filp)) {
 		extra_count = true;
-		info->port.count--;
+		port->count--;
 	}
 	spin_unlock_irqrestore(&info->irq_spinlock, flags);
-	info->port.blocked_open++;
+	port->blocked_open++;
 	
 	while (1) {
 		if (tty->termios->c_cflag & CBAUD) {
@@ -3348,20 +3367,16 @@ static int block_til_ready(struct tty_struct *tty, struct file * filp,
 		
 		set_current_state(TASK_INTERRUPTIBLE);
 		
-		if (tty_hung_up_p(filp) || !(info->port.flags & ASYNC_INITIALIZED)){
-			retval = (info->port.flags & ASYNC_HUP_NOTIFY) ?
+		if (tty_hung_up_p(filp) || !(port->flags & ASYNC_INITIALIZED)){
+			retval = (port->flags & ASYNC_HUP_NOTIFY) ?
 					-EAGAIN : -ERESTARTSYS;
 			break;
 		}
 		
-		spin_lock_irqsave(&info->irq_spinlock,flags);
-	 	usc_get_serial_signals(info);
-		spin_unlock_irqrestore(&info->irq_spinlock,flags);
+		dcd = tty_port_carrier_raised(&info->port);
 		
- 		if (!(info->port.flags & ASYNC_CLOSING) &&
- 		    (do_clocal || (info->serial_signals & SerialSignal_DCD)) ) {
+ 		if (!(port->flags & ASYNC_CLOSING) && (do_clocal || dcd))
  			break;
-		}
 			
 		if (signal_pending(current)) {
 			retval = -ERESTARTSYS;
@@ -3370,24 +3385,24 @@ static int block_til_ready(struct tty_struct *tty, struct file * filp,
 		
 		if (debug_level >= DEBUG_LEVEL_INFO)
 			printk("%s(%d):block_til_ready blocking on %s count=%d\n",
-				 __FILE__,__LINE__, tty->driver->name, info->port.count );
+				 __FILE__,__LINE__, tty->driver->name, port->count );
 				 
 		schedule();
 	}
 	
 	set_current_state(TASK_RUNNING);
-	remove_wait_queue(&info->port.open_wait, &wait);
+	remove_wait_queue(&port->open_wait, &wait);
 	
 	if (extra_count)
-		info->port.count++;
-	info->port.blocked_open--;
+		port->count++;
+	port->blocked_open--;
 	
 	if (debug_level >= DEBUG_LEVEL_INFO)
 		printk("%s(%d):block_til_ready after blocking on %s count=%d\n",
-			 __FILE__,__LINE__, tty->driver->name, info->port.count );
+			 __FILE__,__LINE__, tty->driver->name, port->count );
 			 
 	if (!retval)
-		info->port.flags |= ASYNC_NORMAL_ACTIVE;
+		port->flags |= ASYNC_NORMAL_ACTIVE;
 		
 	return retval;
 	
@@ -4304,6 +4319,11 @@ static void mgsl_add_device( struct mgsl_struct *info )
 
 }	/* end of mgsl_add_device() */
 
+static const struct tty_port_operations mgsl_port_ops = {
+	.carrier_raised = carrier_raised,
+};
+
+
 /* mgsl_allocate_device()
  * 
  * 	Allocate and initialize a device instance structure
@@ -4322,6 +4342,7 @@ static struct mgsl_struct* mgsl_allocate_device(void)
 		printk("Error can't allocate device instance data\n");
 	} else {
 		tty_port_init(&info->port);
+		info->port.ops = &mgsl_port_ops;
 		info->magic = MGSL_MAGIC;
 		INIT_WORK(&info->task, mgsl_bh_handler);
 		info->max_frame_size = 4096;