ftdi_sio.c

	return rv;
}


static __u32 get_ftdi_divisor(struct usb_serial_port * port);


static int change_speed(struct usb_serial_port *port)
{
	struct ftdi_private *priv = usb_get_serial_port_data(port);
	char *buf;
        __u16 urb_value;
	__u16 urb_index;
	__u32 urb_index_value;
	int rv;

	buf = kmalloc(1, GFP_NOIO);
	if (!buf)
		return -ENOMEM;

	urb_index_value = get_ftdi_divisor(port);
	urb_value = (__u16)urb_index_value;
	urb_index = (__u16)(urb_index_value >> 16);
	if (priv->interface) {	/* FT2232C */
		urb_index = (__u16)((urb_index << 8) | priv->interface);
	}
	
	rv = usb_control_msg(port->serial->dev,
			    usb_sndctrlpipe(port->serial->dev, 0),
			    FTDI_SIO_SET_BAUDRATE_REQUEST,
			    FTDI_SIO_SET_BAUDRATE_REQUEST_TYPE,
			    urb_value, urb_index,
			    buf, 0, 100);

	kfree(buf);
	return rv;
}


static __u32 get_ftdi_divisor(struct usb_serial_port * port)
{ /* get_ftdi_divisor */
	struct ftdi_private *priv = usb_get_serial_port_data(port);
	__u32 div_value = 0;
	int div_okay = 1;
	int baud;

	/*
	 * The logic involved in setting the baudrate can be cleanly split in 3 steps.
	 * Obtaining the actual baud rate is a little tricky since unix traditionally
	 * somehow ignored the possibility to set non-standard baud rates.
	 * 1. Standard baud rates are set in tty->termios->c_cflag
	 * 2. If these are not enough, you can set any speed using alt_speed as follows:
	 *    - set tty->termios->c_cflag speed to B38400
	 *    - set your real speed in tty->alt_speed; it gets ignored when
	 *      alt_speed==0, (or)
	 *    - call TIOCSSERIAL ioctl with (struct serial_struct) set as follows:
	 *      flags & ASYNC_SPD_MASK == ASYNC_SPD_[HI, VHI, SHI, WARP], this just
	 *      sets alt_speed to (HI: 57600, VHI: 115200, SHI: 230400, WARP: 460800)
	 * ** Steps 1, 2 are done courtesy of tty_get_baud_rate
	 * 3. You can also set baud rate by setting custom divisor as follows
	 *    - set tty->termios->c_cflag speed to B38400
	 *    - call TIOCSSERIAL ioctl with (struct serial_struct) set as follows:
	 *      o flags & ASYNC_SPD_MASK == ASYNC_SPD_CUST
	 *      o custom_divisor set to baud_base / your_new_baudrate
	 * ** Step 3 is done courtesy of code borrowed from serial.c - I should really
	 *    spend some time and separate+move this common code to serial.c, it is
	 *    replicated in nearly every serial driver you see.
	 */

	/* 1. Get the baud rate from the tty settings, this observes alt_speed hack */

	baud = tty_get_baud_rate(port->tty);
	dbg("%s - tty_get_baud_rate reports speed %d", __FUNCTION__, baud);

	/* 2. Observe async-compatible custom_divisor hack, update baudrate if needed */

	if (baud == 38400 &&
	    ((priv->flags & ASYNC_SPD_MASK) == ASYNC_SPD_CUST) &&
	     (priv->custom_divisor)) {
		baud = priv->baud_base / priv->custom_divisor;
		dbg("%s - custom divisor %d sets baud rate to %d", __FUNCTION__, priv->custom_divisor, baud);
	}

	/* 3. Convert baudrate to device-specific divisor */

	if (!baud) baud = 9600;	
	switch(priv->chip_type) {
	case SIO: /* SIO chip */
		switch(baud) {
		case 300: div_value = ftdi_sio_b300; break;
		case 600: div_value = ftdi_sio_b600; break;
		case 1200: div_value = ftdi_sio_b1200; break;
		case 2400: div_value = ftdi_sio_b2400; break;
		case 4800: div_value = ftdi_sio_b4800; break;
		case 9600: div_value = ftdi_sio_b9600; break;
		case 19200: div_value = ftdi_sio_b19200; break;
		case 38400: div_value = ftdi_sio_b38400; break;
		case 57600: div_value = ftdi_sio_b57600;  break;
		case 115200: div_value = ftdi_sio_b115200; break;
		} /* baud */
		if (div_value == 0) {
  			dbg("%s - Baudrate (%d) requested is not supported", __FUNCTION__,  baud);
			div_value = ftdi_sio_b9600;
			div_okay = 0;
		}
		break;
	case FT8U232AM: /* 8U232AM chip */
		if (baud <= 3000000) {
			div_value = ftdi_232am_baud_to_divisor(baud);
		} else {
	                dbg("%s - Baud rate too high!", __FUNCTION__);
			div_value = ftdi_232am_baud_to_divisor(9600);
			div_okay = 0;
		}
		break;
	case FT232BM: /* FT232BM chip */
	case FT2232C: /* FT2232C chip */
		if (baud <= 3000000) {
			div_value = ftdi_232bm_baud_to_divisor(baud);
		} else {
	                dbg("%s - Baud rate too high!", __FUNCTION__);
			div_value = ftdi_232bm_baud_to_divisor(9600);
			div_okay = 0;
		}
		break;
	} /* priv->chip_type */

	if (div_okay) {
		dbg("%s - Baud rate set to %d (divisor 0x%lX) on chip %s",
			__FUNCTION__, baud, (unsigned long)div_value,
			ftdi_chip_name[priv->chip_type]);
	}

	return(div_value);
}


static int get_serial_info(struct usb_serial_port * port, struct serial_struct __user * retinfo)
{
	struct ftdi_private *priv = usb_get_serial_port_data(port);
	struct serial_struct tmp;

	if (!retinfo)
		return -EFAULT;
	memset(&tmp, 0, sizeof(tmp));
	tmp.flags = priv->flags;
	tmp.baud_base = priv->baud_base;
	tmp.custom_divisor = priv->custom_divisor;
	if (copy_to_user(retinfo, &tmp, sizeof(*retinfo)))
		return -EFAULT;
	return 0;
} /* get_serial_info */


static int set_serial_info(struct usb_serial_port * port, struct serial_struct __user * newinfo)
{ /* set_serial_info */
	struct ftdi_private *priv = usb_get_serial_port_data(port);
	struct serial_struct new_serial;
	struct ftdi_private old_priv;

	if (copy_from_user(&new_serial, newinfo, sizeof(new_serial)))
		return -EFAULT;
	old_priv = * priv;

	/* Do error checking and permission checking */

	if (!capable(CAP_SYS_ADMIN)) {
		if (((new_serial.flags & ~ASYNC_USR_MASK) !=
		     (priv->flags & ~ASYNC_USR_MASK)))
			return -EPERM;
		priv->flags = ((priv->flags & ~ASYNC_USR_MASK) |
			       (new_serial.flags & ASYNC_USR_MASK));
		priv->custom_divisor = new_serial.custom_divisor;
		goto check_and_exit;
	}

	if ((new_serial.baud_base != priv->baud_base) &&
	    (new_serial.baud_base < 9600))
		return -EINVAL;

	/* Make the changes - these are privileged changes! */

	priv->flags = ((priv->flags & ~ASYNC_FLAGS) |
	               (new_serial.flags & ASYNC_FLAGS));	
	priv->custom_divisor = new_serial.custom_divisor;

	port->tty->low_latency = (priv->flags & ASYNC_LOW_LATENCY) ? 1 : 0;

check_and_exit:
	if ((old_priv.flags & ASYNC_SPD_MASK) !=
	     (priv->flags & ASYNC_SPD_MASK)) {
		if ((priv->flags & ASYNC_SPD_MASK) == ASYNC_SPD_HI)
			port->tty->alt_speed = 57600;
		else if ((priv->flags & ASYNC_SPD_MASK) == ASYNC_SPD_VHI)
			port->tty->alt_speed = 115200;
		else if ((priv->flags & ASYNC_SPD_MASK) == ASYNC_SPD_SHI)
			port->tty->alt_speed = 230400;
		else if ((priv->flags & ASYNC_SPD_MASK) == ASYNC_SPD_WARP)
			port->tty->alt_speed = 460800;
		else
			port->tty->alt_speed = 0;
	}
	if (((old_priv.flags & ASYNC_SPD_MASK) !=
	     (priv->flags & ASYNC_SPD_MASK)) ||
	    (((priv->flags & ASYNC_SPD_MASK) == ASYNC_SPD_CUST) &&
	     (old_priv.custom_divisor != priv->custom_divisor))) {
		change_speed(port);
	}
	
	return (0);

} /* set_serial_info */


/*
 * ***************************************************************************
 * Sysfs Attribute
 * ***************************************************************************
 */

static ssize_t show_latency_timer(struct device *dev, char *buf)
{
	struct usb_serial_port *port = to_usb_serial_port(dev);
	struct ftdi_private *priv = usb_get_serial_port_data(port);
	struct usb_device *udev;
	unsigned short latency = 0;
	int rv = 0;
	
	udev = to_usb_device(dev);
	
	dbg("%s",__FUNCTION__);
	
	rv = usb_control_msg(udev,
			     usb_rcvctrlpipe(udev, 0),
			     FTDI_SIO_GET_LATENCY_TIMER_REQUEST,
			     FTDI_SIO_GET_LATENCY_TIMER_REQUEST_TYPE,
			     0, priv->interface, 
			     (char*) &latency, 1, WDR_TIMEOUT);
	
	if (rv < 0) {
		dev_err(dev, "Unable to read latency timer: %i", rv);
		return -EIO;
	}
	return sprintf(buf, "%i\n", latency);
}

/* Write a new value of the latency timer, in units of milliseconds. */
static ssize_t store_latency_timer(struct device *dev, const char *valbuf,
				   size_t count)
{
	struct usb_serial_port *port = to_usb_serial_port(dev);
	struct ftdi_private *priv = usb_get_serial_port_data(port);
	struct usb_device *udev;
	char buf[1];
	int v = simple_strtoul(valbuf, NULL, 10);
	int rv = 0;
	
	udev = to_usb_device(dev);
	
	dbg("%s: setting latency timer = %i", __FUNCTION__, v);
	
	rv = usb_control_msg(udev,
			     usb_sndctrlpipe(udev, 0),
			     FTDI_SIO_SET_LATENCY_TIMER_REQUEST,
			     FTDI_SIO_SET_LATENCY_TIMER_REQUEST_TYPE,
			     v, priv->interface, 
			     buf, 0, WDR_TIMEOUT);
	
	if (rv < 0) {
		dev_err(dev, "Unable to write latency timer: %i", rv);
		return -EIO;
	}
	
	return count;
}

/* Write an event character directly to the FTDI register.  The ASCII
   value is in the low 8 bits, with the enable bit in the 9th bit. */
static ssize_t store_event_char(struct device *dev, const char *valbuf,
				size_t count)
{
	struct usb_serial_port *port = to_usb_serial_port(dev);
	struct ftdi_private *priv = usb_get_serial_port_data(port);
	struct usb_device *udev;
	char buf[1];
	int v = simple_strtoul(valbuf, NULL, 10);
	int rv = 0;
	
	udev = to_usb_device(dev);
	
	dbg("%s: setting event char = %i", __FUNCTION__, v);
	
	rv = usb_control_msg(udev,
			     usb_sndctrlpipe(udev, 0),
			     FTDI_SIO_SET_EVENT_CHAR_REQUEST,
			     FTDI_SIO_SET_EVENT_CHAR_REQUEST_TYPE,
			     v, priv->interface, 
			     buf, 0, WDR_TIMEOUT);
	
	if (rv < 0) {
		dbg("Unable to write event character: %i", rv);
		return -EIO;
	}
	
	return count;
}

static DEVICE_ATTR(latency_timer, S_IWUSR | S_IRUGO, show_latency_timer, store_latency_timer);
static DEVICE_ATTR(event_char, S_IWUSR, NULL, store_event_char);

static void create_sysfs_attrs(struct usb_serial *serial)
{	
	struct ftdi_private *priv;
	struct usb_device *udev;

	dbg("%s",__FUNCTION__);
	
	priv = usb_get_serial_port_data(serial->port[0]);
	udev = serial->dev;
	
	/* XXX I've no idea if the original SIO supports the event_char
	 * sysfs parameter, so I'm playing it safe.  */
	if (priv->chip_type != SIO) {
		dbg("sysfs attributes for %s", ftdi_chip_name[priv->chip_type]);
		device_create_file(&udev->dev, &dev_attr_event_char);
		if (priv->chip_type == FT232BM || priv->chip_type == FT2232C) {
			device_create_file(&udev->dev, &dev_attr_latency_timer);
		}
	}
}

static void remove_sysfs_attrs(struct usb_serial *serial)
{
	struct ftdi_private *priv;
	struct usb_device *udev;

	dbg("%s",__FUNCTION__);	

	priv = usb_get_serial_port_data(serial->port[0]);
	udev = serial->dev;
	
	/* XXX see create_sysfs_attrs */
	if (priv->chip_type != SIO) {
		device_remove_file(&udev->dev, &dev_attr_event_char);
		if (priv->chip_type == FT232BM || priv->chip_type == FT2232C) {
			device_remove_file(&udev->dev, &dev_attr_latency_timer);
		}
	}
	
}

/*
 * ***************************************************************************
 * FTDI driver specific functions
 * ***************************************************************************
 */

/* Common startup subroutine */
/* Called from ftdi_SIO_startup, etc. */
static int ftdi_common_startup (struct usb_serial *serial)
{
	struct usb_serial_port *port = serial->port[0];
	struct ftdi_private *priv;
	
	dbg("%s",__FUNCTION__);

	priv = kmalloc(sizeof(struct ftdi_private), GFP_KERNEL);
	if (!priv){
		err("%s- kmalloc(%Zd) failed.", __FUNCTION__, sizeof(struct ftdi_private));
		return -ENOMEM;
	}
	memset(priv, 0, sizeof(*priv));

	spin_lock_init(&priv->rx_lock);
        init_waitqueue_head(&priv->delta_msr_wait);
	/* This will push the characters through immediately rather
	   than queue a task to deliver them */
	priv->flags = ASYNC_LOW_LATENCY;

	/* Increase the size of read buffers */
	kfree(port->bulk_in_buffer);
	port->bulk_in_buffer = kmalloc (BUFSZ, GFP_KERNEL);
	if (!port->bulk_in_buffer) {
		kfree (priv);
		return -ENOMEM;
	}
	if (port->read_urb) {
		port->read_urb->transfer_buffer = port->bulk_in_buffer;
		port->read_urb->transfer_buffer_length = BUFSZ;
	}

	INIT_WORK(&priv->rx_work, ftdi_process_read, port);

	/* Free port's existing write urb and transfer buffer. */
	if (port->write_urb) {
		usb_free_urb (port->write_urb);
		port->write_urb = NULL;
	}
	kfree(port->bulk_out_buffer);
	port->bulk_out_buffer = NULL;

	usb_set_serial_port_data(serial->port[0], priv);
	
	return (0);
}


/* Startup for the SIO chip */
/* Called from usbserial:serial_probe */
static int ftdi_SIO_startup (struct usb_serial *serial)
{
	struct ftdi_private *priv;
	int err;

	dbg("%s",__FUNCTION__);

	err = ftdi_common_startup(serial);
	if (err){
		return (err);
	}

	priv = usb_get_serial_port_data(serial->port[0]);
	priv->chip_type = SIO;
	priv->baud_base = 12000000 / 16;
	priv->write_offset = 1;
	
	return (0);
}

/* Startup for the 8U232AM chip */
/* Called from usbserial:serial_probe */
static int ftdi_8U232AM_startup (struct usb_serial *serial)
{ /* ftdi_8U232AM_startup */
	struct ftdi_private *priv;
	int err;

	dbg("%s",__FUNCTION__);
	err = ftdi_common_startup(serial);
	if (err){
		return (err);
	}

	priv = usb_get_serial_port_data(serial->port[0]);
	priv->chip_type = FT8U232AM;
	priv->baud_base = 48000000 / 2; /* Would be / 16, but FTDI supports 0.125, 0.25 and 0.5 divisor fractions! */
	
	create_sysfs_attrs(serial);
	
	return (0);
} /* ftdi_8U232AM_startup */

/* Startup for the FT232BM chip */
/* Called from usbserial:serial_probe */
static int ftdi_FT232BM_startup (struct usb_serial *serial)
{ /* ftdi_FT232BM_startup */
	struct ftdi_private *priv;
	int err;

	dbg("%s",__FUNCTION__);
	err = ftdi_common_startup(serial);
	if (err){
		return (err);
	}

	priv = usb_get_serial_port_data(serial->port[0]);
	priv->chip_type = FT232BM;
	priv->baud_base = 48000000 / 2; /* Would be / 16, but FT232BM supports multiple of 0.125 divisor fractions! */
	
	create_sysfs_attrs(serial);

	return (0);
} /* ftdi_FT232BM_startup */

/* Startup for the FT2232C chip */
/* Called from usbserial:serial_probe */
static int ftdi_FT2232C_startup (struct usb_serial *serial)
{ /* ftdi_FT2232C_startup */
	struct ftdi_private *priv;
	int err;
	int inter;

	dbg("%s",__FUNCTION__);
	err = ftdi_common_startup(serial);
	if (err){
		return (err);
	}

	priv = usb_get_serial_port_data(serial->port[0]);
	priv->chip_type = FT2232C;
	inter = serial->interface->altsetting->desc.bInterfaceNumber;

	if (inter) {
		priv->interface = PIT_SIOB;
	}
	else  {
		priv->interface = PIT_SIOA;
	}
	priv->baud_base = 48000000 / 2; /* Would be / 16, but FT2232C supports multiple of 0.125 divisor fractions! */
	
	create_sysfs_attrs(serial);

	return (0);
} /* ftdi_FT2232C_startup */

/* Startup for the USB-UIRT device, which requires hardwired baudrate (38400 gets mapped to 312500) */
/* Called from usbserial:serial_probe */
static int ftdi_USB_UIRT_startup (struct usb_serial *serial)
{ /* ftdi_USB_UIRT_startup */
	struct ftdi_private *priv;
	int err;

	dbg("%s",__FUNCTION__);
	err = ftdi_8U232AM_startup(serial);
	if (err){
		return (err);
	}

	priv = usb_get_serial_port_data(serial->port[0]);
	priv->flags |= ASYNC_SPD_CUST;
	priv->custom_divisor = 77;
	priv->force_baud = B38400;
	
	return (0);
} /* ftdi_USB_UIRT_startup */

/* Startup for the HE-TIRA1 device, which requires hardwired
 * baudrate (38400 gets mapped to 100000) */
static int ftdi_HE_TIRA1_startup (struct usb_serial *serial)
{ /* ftdi_HE_TIRA1_startup */
	struct ftdi_private *priv;
	int err;

	dbg("%s",__FUNCTION__);
	err = ftdi_FT232BM_startup(serial);
	if (err){
		return (err);
	}

	priv = usb_get_serial_port_data(serial->port[0]);
	priv->flags |= ASYNC_SPD_CUST;
	priv->custom_divisor = 240;
	priv->force_baud = B38400;
	priv->force_rtscts = 1;
	
	return (0);
} /* ftdi_HE_TIRA1_startup */


/* ftdi_shutdown is called from usbserial:usb_serial_disconnect 
 *   it is called when the usb device is disconnected
 *
 *   usbserial:usb_serial_disconnect
 *      calls __serial_close for each open of the port
 *      shutdown is called then (ie ftdi_shutdown)
 */


static void ftdi_shutdown (struct usb_serial *serial)
{ /* ftdi_shutdown */
	
	struct usb_serial_port *port = serial->port[0];
	struct ftdi_private *priv = usb_get_serial_port_data(port);

	dbg("%s", __FUNCTION__);

	remove_sysfs_attrs(serial);
	
	/* all open ports are closed at this point 
         *    (by usbserial.c:__serial_close, which calls ftdi_close)  
	 */

	if (priv) {
		usb_set_serial_port_data(port, NULL);
		kfree(priv);
	}
} /* ftdi_shutdown */


static int  ftdi_open (struct usb_serial_port *port, struct file *filp)
{ /* ftdi_open */
	struct termios tmp_termios;
	struct usb_device *dev = port->serial->dev;
	struct ftdi_private *priv = usb_get_serial_port_data(port);
	unsigned long flags;
	
	int result = 0;
	char buf[1]; /* Needed for the usb_control_msg I think */

	dbg("%s", __FUNCTION__);


	port->tty->low_latency = (priv->flags & ASYNC_LOW_LATENCY) ? 1 : 0;

	/* No error checking for this (will get errors later anyway) */
	/* See ftdi_sio.h for description of what is reset */
	usb_control_msg(dev, usb_sndctrlpipe(dev, 0),
			FTDI_SIO_RESET_REQUEST, FTDI_SIO_RESET_REQUEST_TYPE, 
			FTDI_SIO_RESET_SIO, 
			priv->interface, buf, 0, WDR_TIMEOUT);

	/* Termios defaults are set by usb_serial_init. We don't change
	   port->tty->termios - this would loose speed settings, etc.
	   This is same behaviour as serial.c/rs_open() - Kuba */

	/* ftdi_set_termios  will send usb control messages */
	ftdi_set_termios(port, &tmp_termios);

	/* FIXME: Flow control might be enabled, so it should be checked -
	   we have no control of defaults! */
	/* Turn on RTS and DTR since we are not flow controlling by default */
	if (set_dtr(port, HIGH) < 0) {
		err("%s Error from DTR HIGH urb", __FUNCTION__);
	}
	if (set_rts(port, HIGH) < 0){
		err("%s Error from RTS HIGH urb", __FUNCTION__);
	}

	/* Not throttled */
	spin_lock_irqsave(&priv->rx_lock, flags);
	priv->rx_flags &= ~(THROTTLED | ACTUALLY_THROTTLED);
	spin_unlock_irqrestore(&priv->rx_lock, flags);

	/* Start reading from the device */
	priv->rx_processed = 0;
	usb_fill_bulk_urb(port->read_urb, dev,
		      usb_rcvbulkpipe(dev, port->bulk_in_endpointAddress),
		      port->read_urb->transfer_buffer, port->read_urb->transfer_buffer_length,
		      ftdi_read_bulk_callback, port);
	result = usb_submit_urb(port->read_urb, GFP_KERNEL);
	if (result)
		err("%s - failed submitting read urb, error %d", __FUNCTION__, result);


	return result;
} /* ftdi_open */



/* 
 * usbserial:__serial_close  only calls ftdi_close if the point is open
 *
 *   This only gets called when it is the last close
 *   
 *   
 */

static void ftdi_close (struct usb_serial_port *port, struct file *filp)
{ /* ftdi_close */
	unsigned int c_cflag = port->tty->termios->c_cflag;
	struct ftdi_private *priv = usb_get_serial_port_data(port);
	char buf[1];

	dbg("%s", __FUNCTION__);

	if (c_cflag & HUPCL){
		/* Disable flow control */
		if (usb_control_msg(port->serial->dev, 
				    usb_sndctrlpipe(port->serial->dev, 0),
				    FTDI_SIO_SET_FLOW_CTRL_REQUEST,
				    FTDI_SIO_SET_FLOW_CTRL_REQUEST_TYPE,
				    0, priv->interface, buf, 0,
				    WDR_TIMEOUT) < 0) {
			err("error from flowcontrol urb");
		}	    

		/* drop DTR */
		if (set_dtr(port, LOW) < 0){
			err("Error from DTR LOW urb");
		}
		/* drop RTS */
		if (set_rts(port, LOW) < 0) {
			err("Error from RTS LOW urb");
		}
	} /* Note change no line if hupcl is off */

	/* cancel any scheduled reading */
	cancel_delayed_work(&priv->rx_work);
	flush_scheduled_work();
	
	/* shutdown our bulk read */
	if (port->read_urb)
		usb_kill_urb(port->read_urb);
} /* ftdi_close */


  
/* The SIO requires the first byte to have:
 *  B0 1
 *  B1 0
 *  B2..7 length of message excluding byte 0
 *
 * The new devices do not require this byte
 */
static int ftdi_write (struct usb_serial_port *port,
			   const unsigned char *buf, int count)
{ /* ftdi_write */
	struct ftdi_private *priv = usb_get_serial_port_data(port);
	struct urb *urb;
	unsigned char *buffer;
	int data_offset ;       /* will be 1 for the SIO and 0 otherwise */
	int status;
	int transfer_size;

	dbg("%s port %d, %d bytes", __FUNCTION__, port->number, count);

	if (count == 0) {
		dbg("write request of 0 bytes");
		return 0;
	}
	
	data_offset = priv->write_offset;
        dbg("data_offset set to %d",data_offset);

	/* Determine total transfer size */
	transfer_size = count;
	if (data_offset > 0) {
		/* Original sio needs control bytes too... */
		transfer_size += (data_offset *
				((count + (PKTSZ - 1 - data_offset)) /
				 (PKTSZ - data_offset)));
	}

	buffer = kmalloc (transfer_size, GFP_ATOMIC);
	if (!buffer) {
		err("%s ran out of kernel memory for urb ...", __FUNCTION__);
		return -ENOMEM;
	}

	urb = usb_alloc_urb(0, GFP_ATOMIC);
	if (!urb) {
		err("%s - no more free urbs", __FUNCTION__);
		kfree (buffer);
		return -ENOMEM;
	}

	/* Copy data */
	if (data_offset > 0) {
		/* Original sio requires control byte at start of each packet. */
		int user_pktsz = PKTSZ - data_offset;
		int todo = count;
		unsigned char *first_byte = buffer;
		const unsigned char *current_position = buf;

		while (todo > 0) {
			if (user_pktsz > todo) {
				user_pktsz = todo;
			}
			/* Write the control byte at the front of the packet*/
			*first_byte = 1 | ((user_pktsz) << 2); 
			/* Copy data for packet */
			memcpy (first_byte + data_offset,
				current_position, user_pktsz);
			first_byte += user_pktsz + data_offset;
			current_position += user_pktsz;
			todo -= user_pktsz;
		}
	} else {
		/* No control byte required. */
		/* Copy in the data to send */
		memcpy (buffer, buf, count);
	}

	usb_serial_debug_data(debug, &port->dev, __FUNCTION__, transfer_size, buffer);

	/* fill the buffer and send it */
	usb_fill_bulk_urb(urb, port->serial->dev, 
		      usb_sndbulkpipe(port->serial->dev, port->bulk_out_endpointAddress),
		      buffer, transfer_size,
		      ftdi_write_bulk_callback, port);

	status = usb_submit_urb(urb, GFP_ATOMIC);
	if (status) {
		err("%s - failed submitting write urb, error %d", __FUNCTION__, status);
		count = status;
		kfree (buffer);
	}

	/* we are done with this urb, so let the host driver
	 * really free it when it is finished with it */
	usb_free_urb (urb);

	dbg("%s write returning: %d", __FUNCTION__, count);
	return count;
} /* ftdi_write */


/* This function may get called when the device is closed */

static void ftdi_write_bulk_callback (struct urb *urb, struct pt_regs *regs)
{
	struct usb_serial_port *port = (struct usb_serial_port *)urb->context;

	/* free up the transfer buffer, as usb_free_urb() does not do this */
	kfree (urb->transfer_buffer);

	dbg("%s - port %d", __FUNCTION__, port->number);
	
	if (urb->status) {
		dbg("nonzero write bulk status received: %d", urb->status);
		return;
	}

	schedule_work(&port->work);
} /* ftdi_write_bulk_callback */


static int ftdi_write_room( struct usb_serial_port *port )
{
	dbg("%s - port %d", __FUNCTION__, port->number);

	/*
	 * We really can take anything the user throws at us
	 * but let's pick a nice big number to tell the tty
	 * layer that we have lots of free space
	 */
	return 2048;
} /* ftdi_write_room */


static int ftdi_chars_in_buffer (struct usb_serial_port *port)
{ /* ftdi_chars_in_buffer */
	dbg("%s - port %d", __FUNCTION__, port->number);

	/* 
	 * We can't really account for how much data we
	 * have sent out, but hasn't made it through to the
	 * device, so just tell the tty layer that everything
	 * is flushed.
	 */
	return 0;
} /* ftdi_chars_in_buffer */



static void ftdi_read_bulk_callback (struct urb *urb, struct pt_regs *regs)
{ /* ftdi_read_bulk_callback */
	struct usb_serial_port *port = (struct usb_serial_port *)urb->context;
	struct tty_struct *tty;
	struct ftdi_private *priv;

	if (urb->number_of_packets > 0) {
		err("%s transfer_buffer_length %d actual_length %d number of packets %d",__FUNCTION__,
		    urb->transfer_buffer_length, urb->actual_length, urb->number_of_packets );
		err("%s transfer_flags %x ", __FUNCTION__,urb->transfer_flags );
	}

	dbg("%s - port %d", __FUNCTION__, port->number);

	if (port->open_count <= 0)
		return;

	tty = port->tty;
	if (!tty) {
		dbg("%s - bad tty pointer - exiting",__FUNCTION__);
		return;
	}

	priv = usb_get_serial_port_data(port);
	if (!priv) {
		dbg("%s - bad port private data pointer - exiting", __FUNCTION__);
		return;
	}

	if (urb != port->read_urb) {
		err("%s - Not my urb!", __FUNCTION__);
	}

	if (urb->status) {
		/* This will happen at close every time so it is a dbg not an err */
		dbg("(this is ok on close) nonzero read bulk status received: %d", urb->status);
		return;
	}

	ftdi_process_read(port);

} /* ftdi_read_bulk_callback */


static void ftdi_process_read (void *param)
{ /* ftdi_process_read */
	struct usb_serial_port *port = (struct usb_serial_port*)param;
	struct urb *urb;
	struct tty_struct *tty;
	struct ftdi_private *priv;
	char error_flag;
       	unsigned char *data;

	int i;
	int result;
	int need_flip;
	int packet_offset;
	unsigned long flags;

	dbg("%s - port %d", __FUNCTION__, port->number);

	if (port->open_count <= 0)
		return;

	tty = port->tty;
	if (!tty) {
		dbg("%s - bad tty pointer - exiting",__FUNCTION__);
		return;
	}

	priv = usb_get_serial_port_data(port);
	if (!priv) {
		dbg("%s - bad port private data pointer - exiting", __FUNCTION__);
		return;
	}

	urb = port->read_urb;
	if (!urb) {
		dbg("%s - bad read_urb pointer - exiting", __FUNCTION__);
		return;
	}

	data = urb->transfer_buffer;

	if (priv->rx_processed) {
		dbg("%s - already processed: %d bytes, %d remain", __FUNCTION__,
				priv->rx_processed,
				urb->actual_length - priv->rx_processed);
	} else {
		/* The first two bytes of every read packet are status */
		if (urb->actual_length > 2) {
			usb_serial_debug_data(debug, &port->dev, __FUNCTION__, urb->actual_length, data);
		} else {
			dbg("Status only: %03oo %03oo",data[0],data[1]);
		}
	}


	/* TO DO -- check for hung up line and handle appropriately: */
	/*   send hangup  */
	/* See acm.c - you do a tty_hangup  - eg tty_hangup(tty) */
	/* if CD is dropped and the line is not CLOCAL then we should hangup */

	need_flip = 0;
	for (packet_offset = priv->rx_processed; packet_offset < urb->actual_length; packet_offset += PKTSZ) {
		int length;

		/* Compare new line status to the old one, signal if different */
		/* N.B. packet may be processed more than once, but differences
		 * are only processed once.  */
		if (priv != NULL) {
			char new_status = data[packet_offset+0] & FTDI_STATUS_B0_MASK;
			if (new_status != priv->prev_status) {
				priv->diff_status |= new_status ^ priv->prev_status;
				wake_up_interruptible(&priv->delta_msr_wait);
				priv->prev_status = new_status;
			}
		}

		length = min(PKTSZ, urb->actual_length-packet_offset)-2;
		if (length < 0) {
			err("%s - bad packet length: %d", __FUNCTION__, length+2);
			length = 0;
		}

		/* have to make sure we don't overflow the buffer
		   with tty_insert_flip_char's */
		if (tty->flip.count+length > TTY_FLIPBUF_SIZE) {
			tty_flip_buffer_push(tty);
			need_flip = 0;

			if (tty->flip.count != 0) {
				/* flip didn't work, this happens when ftdi_process_read() is
				 * called from ftdi_unthrottle, because TTY_DONT_FLIP is set */
				dbg("%s - flip buffer push failed", __FUNCTION__);
				break;
			}
		}
		if (priv->rx_flags & THROTTLED) {
			dbg("%s - throttled", __FUNCTION__);
			break;
		}
		if (tty->ldisc.receive_room(tty)-tty->flip.count < length) {
			/* break out & wait for throttling/unthrottling to happen */
			dbg("%s - receive room low", __FUNCTION__);
			break;
		}

		/* Handle errors and break */
		error_flag = TTY_NORMAL;
		/* Although the device uses a bitmask and hence can have multiple */
		/* errors on a packet - the order here sets the priority the */
		/* error is returned to the tty layer  */

		if ( data[packet_offset+1] & FTDI_RS_OE ) {
			error_flag = TTY_OVERRUN;
			dbg("OVERRRUN error");
		}
		if ( data[packet_offset+1] & FTDI_RS_BI ) {
			error_flag = TTY_BREAK;
			dbg("BREAK received");
		}
		if ( data[packet_offset+1] & FTDI_RS_PE ) {
			error_flag = TTY_PARITY;
			dbg("PARITY error");
		}