USB: serial: opticon: add chars_in_buffer() implementation

Add a chars_in_buffer() implementation so that the tty layer will wait
for outgoing buffered data to be drained when needed (e.g. on final
close()).

Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Johan Hovold <johan@kernel.org>

diff --git a/drivers/usb/serial/opticon.c b/drivers/usb/serial/opticon.c
index cb7aac9cd9e72aadac7bc474ffecc4b57e88e828..05ea21ed967c13af2dae70c842878b150407a336 100644 (file)
--- a/drivers/usb/serial/opticon.c
+++ b/drivers/usb/serial/opticon.c
@@ -41,6 +41,7 @@ struct opticon_private {
        bool rts;
        bool cts;
        int outstanding_urbs;
+       int outstanding_bytes;
 };
 
 
@@ -169,6 +170,7 @@ static void opticon_write_control_callback(struct urb *urb)
 
        spin_lock_irqsave(&priv->lock, flags);
        --priv->outstanding_urbs;
+       priv->outstanding_bytes -= urb->transfer_buffer_length;
        spin_unlock_irqrestore(&priv->lock, flags);
 
        usb_serial_port_softint(port);
@@ -182,8 +184,8 @@ static int opticon_write(struct tty_struct *tty, struct usb_serial_port *port,
        struct urb *urb;
        unsigned char *buffer;
        unsigned long flags;
-       int status;
        struct usb_ctrlrequest *dr;
+       int ret = -ENOMEM;
 
        spin_lock_irqsave(&priv->lock, flags);
        if (priv->outstanding_urbs > URB_UPPER_LIMIT) {
@@ -192,19 +194,16 @@ static int opticon_write(struct tty_struct *tty, struct usb_serial_port *port,
                return 0;
        }
        priv->outstanding_urbs++;
+       priv->outstanding_bytes += count;
        spin_unlock_irqrestore(&priv->lock, flags);
 
        buffer = kmalloc(count, GFP_ATOMIC);
-       if (!buffer) {
-               count = -ENOMEM;
+       if (!buffer)
                goto error_no_buffer;
-       }
 
        urb = usb_alloc_urb(0, GFP_ATOMIC);
-       if (!urb) {
-               count = -ENOMEM;
+       if (!urb)
                goto error_no_urb;
-       }
 
        memcpy(buffer, buf, count);
 
@@ -213,10 +212,8 @@ static int opticon_write(struct tty_struct *tty, struct usb_serial_port *port,
        /* The connected devices do not have a bulk write endpoint,
         * to transmit data to de barcode device the control endpoint is used */
        dr = kmalloc(sizeof(struct usb_ctrlrequest), GFP_ATOMIC);
-       if (!dr) {
-               count = -ENOMEM;
+       if (!dr)
                goto error_no_dr;
-       }
 
        dr->bRequestType = USB_TYPE_VENDOR | USB_RECIP_INTERFACE | USB_DIR_OUT;
        dr->bRequest = 0x01;
@@ -230,12 +227,9 @@ static int opticon_write(struct tty_struct *tty, struct usb_serial_port *port,
                opticon_write_control_callback, port);
 
        /* send it down the pipe */
-       status = usb_submit_urb(urb, GFP_ATOMIC);
-       if (status) {
-               dev_err(&port->dev,
-               "%s - usb_submit_urb(write endpoint) failed status = %d\n",
-                                                       __func__, status);
-               count = status;
+       ret = usb_submit_urb(urb, GFP_ATOMIC);
+       if (ret) {
+               dev_err(&port->dev, "failed to submit write urb: %d\n", ret);
                goto error;
        }
 
@@ -253,8 +247,10 @@ error_no_urb:
 error_no_buffer:
        spin_lock_irqsave(&priv->lock, flags);
        --priv->outstanding_urbs;
+       priv->outstanding_bytes -= count;
        spin_unlock_irqrestore(&priv->lock, flags);
-       return count;
+
+       return ret;
 }
 
 static int opticon_write_room(struct tty_struct *tty)
@@ -279,6 +275,20 @@ static int opticon_write_room(struct tty_struct *tty)
        return 2048;
 }
 
+static int opticon_chars_in_buffer(struct tty_struct *tty)
+{
+       struct usb_serial_port *port = tty->driver_data;
+       struct opticon_private *priv = usb_get_serial_port_data(port);
+       unsigned long flags;
+       int count;
+
+       spin_lock_irqsave(&priv->lock, flags);
+       count = priv->outstanding_bytes;
+       spin_unlock_irqrestore(&priv->lock, flags);
+
+       return count;
+}
+
 static int opticon_tiocmget(struct tty_struct *tty)
 {
        struct usb_serial_port *port = tty->driver_data;
@@ -383,6 +393,7 @@ static struct usb_serial_driver opticon_device = {
        .open =                 opticon_open,
        .write =                opticon_write,
        .write_room =           opticon_write_room,
+       .chars_in_buffer =      opticon_chars_in_buffer,
        .throttle =             usb_serial_generic_throttle,
        .unthrottle =           usb_serial_generic_unthrottle,
        .get_serial =           get_serial_info,