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, 37 insertions, 24 deletions

diff --git a/drivers/char/esp.c b/drivers/char/esp.c
index 7f077c0097f6..45ec263ec012 100644
--- a/drivers/char/esp.c
+++ b/drivers/char/esp.c
@@ -2054,6 +2054,15 @@ static void esp_hangup(struct tty_struct *tty)
         wake_up_interruptible(&info->port.open_wait);
 }
 
+static int esp_carrier_raised(struct tty_port *port)
+{
+        struct esp_struct *info = container_of(port, struct esp_struct, port);
+        serial_out(info, UART_ESI_CMD1, ESI_GET_UART_STAT);
+        if (serial_in(info, UART_ESI_STAT2) & UART_MSR_DCD)
+                return 1;
+        return 0;
+}
+
 /*
  * ------------------------------------------------------------
  * esp_open() and friends
@@ -2066,17 +2075,19 @@ static int block_til_ready(struct tty_struct *tty, struct file *filp,
         int             retval;
         int             do_clocal = 0;
         unsigned long   flags;
+        int             cd;
+        struct tty_port *port = &info->port;
 
         /*
          * If the device is in the middle of being closed, then block
          * until it's done, and then try again.
          */
         if (tty_hung_up_p(filp) ||
-            (info->port.flags & ASYNC_CLOSING)) {
-                if (info->port.flags & ASYNC_CLOSING)
-                        interruptible_sleep_on(&info->port.close_wait);
+            (port->flags & ASYNC_CLOSING)) {
+                if (port->flags & ASYNC_CLOSING)
+                        interruptible_sleep_on(&port->close_wait);
 #ifdef SERIAL_DO_RESTART
-                if (info->port.flags & ASYNC_HUP_NOTIFY)
+                if (port->flags & ASYNC_HUP_NOTIFY)
                         return -EAGAIN;
                 else
                         return -ERESTARTSYS;
@@ -2091,7 +2102,7 @@ static int block_til_ready(struct tty_struct *tty, struct file *filp,
          */
         if ((filp->f_flags & O_NONBLOCK) ||
             (tty->flags & (1 << TTY_IO_ERROR))) {
-                info->port.flags |= ASYNC_NORMAL_ACTIVE;
+                port->flags |= ASYNC_NORMAL_ACTIVE;
                 return 0;
         }
 
@@ -2101,20 +2112,20 @@ static int 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, info->port.count is dropped by one, so that
+         * this loop, port->count is dropped by one, so that
          * rs_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);
 #ifdef SERIAL_DEBUG_OPEN
         printk(KERN_DEBUG "block_til_ready before block: ttys%d, count = %d\n",
-               info->line, info->port.count);
+               info->line, port->count);
 #endif
         spin_lock_irqsave(&info->lock, flags);
         if (!tty_hung_up_p(filp))
-                info->port.count--;
-        info->port.blocked_open++;
+                port->count--;
+        port->blocked_open++;
         while (1) {
                 if ((tty->termios->c_cflag & CBAUD)) {
                         unsigned int scratch;
@@ -2129,9 +2140,9 @@ 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)) {
+                    !(port->flags & ASYNC_INITIALIZED)) {
 #ifdef SERIAL_DO_RESTART
-                        if (info->port.flags & ASYNC_HUP_NOTIFY)
+                        if (port->flags & ASYNC_HUP_NOTIFY)
                                 retval = -EAGAIN;
                         else
                                 retval = -ERESTARTSYS;
@@ -2141,11 +2152,9 @@ static int block_til_ready(struct tty_struct *tty, struct file *filp,
                         break;
                 }
 
-                serial_out(info, UART_ESI_CMD1, ESI_GET_UART_STAT);
-                if (serial_in(info, UART_ESI_STAT2) & UART_MSR_DCD)
-                        do_clocal = 1;
+                cd = tty_port_carrier_raised(port);
 
-                if (!(info->port.flags & ASYNC_CLOSING) &&
+                if (!(port->flags & ASYNC_CLOSING) &&
                     (do_clocal))
                         break;
                 if (signal_pending(current)) {
@@ -2154,25 +2163,25 @@ static int block_til_ready(struct tty_struct *tty, struct file *filp,
                 }
 #ifdef SERIAL_DEBUG_OPEN
                 printk(KERN_DEBUG "block_til_ready blocking: ttys%d, count = %d\n",
-                       info->line, info->port.count);
+                       info->line, port->count);
 #endif
                 spin_unlock_irqrestore(&info->lock, flags);
                 schedule();
                 spin_lock_irqsave(&info->lock, flags);
         }
         set_current_state(TASK_RUNNING);
-        remove_wait_queue(&info->port.open_wait, &wait);
+        remove_wait_queue(&port->open_wait, &wait);
         if (!tty_hung_up_p(filp))
-                info->port.count++;
-        info->port.blocked_open--;
+                port->count++;
+        port->blocked_open--;
         spin_unlock_irqrestore(&info->lock, flags);
 #ifdef SERIAL_DEBUG_OPEN
         printk(KERN_DEBUG "block_til_ready after blocking: ttys%d, count = %d\n",
-               info->line, info->port.count);
+               info->line, port->count);
 #endif
         if (retval)
                 return retval;
-        info->port.flags |= ASYNC_NORMAL_ACTIVE;
+        port->flags |= ASYNC_NORMAL_ACTIVE;
         return 0;
 }
 
@@ -2329,6 +2338,10 @@ static const struct tty_operations esp_ops = {
         .tiocmset = esp_tiocmset,
 };
 
+static const struct tty_port_operations esp_port_ops = {
+        .esp_carrier_raised,
+};
+
 /*
  * The serial driver boot-time initialization code!
  */
@@ -2415,6 +2428,8 @@ static int __init espserial_init(void)
         offset = 0;
 
         do {
+                tty_port_init(&info->port);
+                info->port.ops = &esp_port_ops;
                 info->io_port = esp[i] + offset;
                 info->irq = irq[i];
                 info->line = (i * 8) + (offset / 8);
@@ -2437,8 +2452,6 @@ static int __init espserial_init(void)
                 info->config.flow_off = flow_off;
                 info->config.pio_threshold = pio_threshold;
                 info->next_port = ports;
-                init_waitqueue_head(&info->port.open_wait);
-                init_waitqueue_head(&info->port.close_wait);
                 init_waitqueue_head(&info->delta_msr_wait);
                 init_waitqueue_head(&info->break_wait);
                 ports = info;