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 500f5176b6ba..fb2e6b5e0ef1 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;