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, 31 insertions, 17 deletions

diff --git a/drivers/char/synclink_gt.c b/drivers/char/synclink_gt.c
index 08911ed66494..39ccaba8ca37 100644
--- a/drivers/char/synclink_gt.c
+++ b/drivers/char/synclink_gt.c
@@ -3132,6 +3132,17 @@ static int tiocmset(struct tty_struct *tty, struct file *file,
         return 0;
 }
 
+static int carrier_raised(struct tty_port *port)
+{
+        unsigned long flags;
+        struct slgt_info *info = container_of(port, struct slgt_info, port);
+
+        spin_lock_irqsave(&info->lock,flags);
+        get_signals(info);
+        spin_unlock_irqrestore(&info->lock,flags);
+        return (info->signals & SerialSignal_DCD) ? 1 : 0;
+}
+
 /*
  *  block current process until the device is ready to open
  */
@@ -3143,12 +3154,14 @@ static int block_til_ready(struct tty_struct *tty, struct file *filp,
         bool            do_clocal = false;
         bool            extra_count = false;
         unsigned long   flags;
+        int             cd;
+        struct tty_port *port = &info->port;
 
         DBGINFO(("%s block_til_ready\n", tty->driver->name));
 
         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;
         }
 
@@ -3157,21 +3170,21 @@ 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
          * 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);
 
         spin_lock_irqsave(&info->lock, flags);
         if (!tty_hung_up_p(filp)) {
                 extra_count = true;
-                info->port.count--;
+                port->count--;
         }
         spin_unlock_irqrestore(&info->lock, flags);
-        info->port.blocked_open++;
+        port->blocked_open++;
 
         while (1) {
                 if ((tty->termios->c_cflag & CBAUD)) {
@@ -3183,20 +3196,16 @@ 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->lock,flags);
-                get_signals(info);
-                spin_unlock_irqrestore(&info->lock,flags);
+                cd = tty_port_carrier_raised(port);
 
-                if (!(info->port.flags & ASYNC_CLOSING) &&
-                    (do_clocal || (info->signals & SerialSignal_DCD)) ) {
+                if (!(port->flags & ASYNC_CLOSING) && (do_clocal || cd ))
                         break;
-                }
 
                 if (signal_pending(current)) {
                         retval = -ERESTARTSYS;
@@ -3208,14 +3217,14 @@ static int block_til_ready(struct tty_struct *tty, struct file *filp,
         }
 
         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 (!retval)
-                info->port.flags |= ASYNC_NORMAL_ACTIVE;
+                port->flags |= ASYNC_NORMAL_ACTIVE;
 
         DBGINFO(("%s block_til_ready ready, rc=%d\n", tty->driver->name, retval));
         return retval;
@@ -3444,6 +3453,10 @@ static void add_device(struct slgt_info *info)
 #endif
 }
 
+static const struct tty_port_operations slgt_port_ops = {
+        .carrier_raised = carrier_raised,
+};
+
 /*
  *  allocate device instance structure, return NULL on failure
  */
@@ -3458,6 +3471,7 @@ static struct slgt_info *alloc_dev(int adapter_num, int port_num, struct pci_dev
                         driver_name, adapter_num, port_num));
         } else {
                 tty_port_init(&info->port);
+                info->port.ops = &slgt_port_ops;
                 info->magic = MGSL_MAGIC;
                 INIT_WORK(&info->task, bh_handler);
                 info->max_frame_size = 4096;