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, 33 insertions, 21 deletions

diff --git a/drivers/char/mxser.c b/drivers/char/mxser.c
index 047766915411..eafbbcf355e7 100644
--- a/drivers/char/mxser.c
+++ b/drivers/char/mxser.c
@@ -541,13 +541,21 @@ static unsigned char mxser_get_msr(int baseaddr, int mode, int port)
         return status;
 }
 
+static int mxser_carrier_raised(struct tty_port *port)
+{
+        struct mxser_port *mp = container_of(port, struct mxser_port, port);
+        return (inb(mp->ioaddr + UART_MSR) & UART_MSR_DCD)?1:0;
+}
+
 static int mxser_block_til_ready(struct tty_struct *tty, struct file *filp,
-                struct mxser_port *port)
+                struct mxser_port *mp)
 {
         DECLARE_WAITQUEUE(wait, current);
         int retval;
         int do_clocal = 0;
         unsigned long flags;
+        int cd;
+        struct tty_port *port = &mp->port;
 
         /*
          * If non-blocking mode is set, or the port is not enabled,
@@ -555,7 +563,7 @@ static int mxser_block_til_ready(struct tty_struct *tty, struct file *filp,
          */
         if ((filp->f_flags & O_NONBLOCK) ||
                         test_bit(TTY_IO_ERROR, &tty->flags)) {
-                port->port.flags |= ASYNC_NORMAL_ACTIVE;
+                port->flags |= ASYNC_NORMAL_ACTIVE;
                 return 0;
         }
 
@@ -565,34 +573,33 @@ static int mxser_block_til_ready(struct tty_struct *tty, struct file *filp,
         /*
          * Block waiting for the carrier detect and the line to become
          * free (i.e., not in use by the callout).  While we are in
-         * this loop, port->port.count is dropped by one, so that
+         * this loop, port->count is dropped by one, so that
          * mxser_close() knows when to free things.  We restore it upon
          * exit, either normal or abnormal.
          */
         retval = 0;
-        add_wait_queue(&port->port.open_wait, &wait);
+        add_wait_queue(&port->open_wait, &wait);
 
-        spin_lock_irqsave(&port->slock, flags);
+        spin_lock_irqsave(&mp->slock, flags);
         if (!tty_hung_up_p(filp))
-                port->port.count--;
-        spin_unlock_irqrestore(&port->slock, flags);
-        port->port.blocked_open++;
+                port->count--;
+        spin_unlock_irqrestore(&mp->slock, flags);
+        port->blocked_open++;
         while (1) {
-                spin_lock_irqsave(&port->slock, flags);
-                outb(inb(port->ioaddr + UART_MCR) |
-                        UART_MCR_DTR | UART_MCR_RTS, port->ioaddr + UART_MCR);
-                spin_unlock_irqrestore(&port->slock, flags);
+                spin_lock_irqsave(&mp->slock, flags);
+                outb(inb(mp->ioaddr + UART_MCR) |
+                        UART_MCR_DTR | UART_MCR_RTS, mp->ioaddr + UART_MCR);
+                spin_unlock_irqrestore(&mp->slock, flags);
                 set_current_state(TASK_INTERRUPTIBLE);
-                if (tty_hung_up_p(filp) || !(port->port.flags & ASYNC_INITIALIZED)) {
-                        if (port->port.flags & ASYNC_HUP_NOTIFY)
+                if (tty_hung_up_p(filp) || !(port->flags & ASYNC_INITIALIZED)) {
+                        if (port->flags & ASYNC_HUP_NOTIFY)
                                 retval = -EAGAIN;
                         else
                                 retval = -ERESTARTSYS;
                         break;
                 }
-                if (!(port->port.flags & ASYNC_CLOSING) &&
-                                (do_clocal ||
-                                (inb(port->ioaddr + UART_MSR) & UART_MSR_DCD)))
+                cd = tty_port_carrier_raised(port);
+                if (!(port->flags & ASYNC_CLOSING) && (do_clocal || cd))
                         break;
                 if (signal_pending(current)) {
                         retval = -ERESTARTSYS;
@@ -601,13 +608,13 @@ static int mxser_block_til_ready(struct tty_struct *tty, struct file *filp,
                 schedule();
         }
         set_current_state(TASK_RUNNING);
-        remove_wait_queue(&port->port.open_wait, &wait);
+        remove_wait_queue(&port->open_wait, &wait);
         if (!tty_hung_up_p(filp))
-                port->port.count++;
-        port->port.blocked_open--;
+                port->count++;
+        port->blocked_open--;
         if (retval)
                 return retval;
-        port->port.flags |= ASYNC_NORMAL_ACTIVE;
+        port->flags |= ASYNC_NORMAL_ACTIVE;
         return 0;
 }
 
@@ -2449,6 +2456,10 @@ static const struct tty_operations mxser_ops = {
         .tiocmset = mxser_tiocmset,
 };
 
+struct tty_port_operations mxser_port_ops = {
+        .carrier_raised = mxser_carrier_raised,
+};
+
 /*
  * The MOXA Smartio/Industio serial driver boot-time initialization code!
  */
@@ -2482,6 +2493,7 @@ static int __devinit mxser_initbrd(struct mxser_board *brd,
         for (i = 0; i < brd->info->nports; i++) {
                 info = &brd->ports[i];
                 tty_port_init(&info->port);
+                info->port.ops = &mxser_port_ops;
                 info->board = brd;
                 info->stop_rx = 0;
                 info->ldisc_stop_rx = 0;