/**
* usb_serial_generic_write - generic write function for serial USB devices
* @tty: Pointer to &struct tty_struct for the device
* @port: Pointer to the &usb_serial_port structure for the device
* @buf: Pointer to the data to write
* @count: Number of bytes to write
*
* Returns the number of characters actually written, which may be anything
* from zero to @count. If an error occurs, it returns the negative errno
* value.
*/
int usb_serial_generic_write(struct tty_struct *tty,
struct usb_serial_port *port, const unsigned char *buf, int count)
{
struct usb_serial *serial = port->serial;
int result;
dbg("%s - port %d", __func__, port->number);
if (count == 0) {
dbg("%s - write request of 0 bytes", __func__);
return 0;
}
/* only do something if we have a bulk out endpoint */
if (!serial->num_bulk_out)
return 0;
if (serial->type->max_in_flight_urbs)
return usb_serial_multi_urb_write(tty, port,
buf, count);
count = kfifo_put(port->write_fifo, buf, count);
result = usb_serial_generic_write_start(port);
if (result >= 0)
result = count;
return result;
}
int usb_serial_generic_write(struct tty_struct *tty,
struct usb_serial_port *port, const unsigned char *buf, int count)
{
struct usb_serial *serial = port->serial;
int result;
unsigned char *data;
dbg("%s - port %d", __func__, port->number);
if (count == 0) {
dbg("%s - write request of 0 bytes", __func__);
return 0;
}
/* only do something if we have a bulk out endpoint */
if (serial->num_bulk_out) {
unsigned long flags;
if (serial->type->max_in_flight_urbs)
return usb_serial_multi_urb_write(tty, port,
buf, count);
spin_lock_irqsave(&port->lock, flags);
if (port->write_urb_busy) {
spin_unlock_irqrestore(&port->lock, flags);
dbg("%s - already writing", __func__);
return 0;
}
port->write_urb_busy = 1;
spin_unlock_irqrestore(&port->lock, flags);
count = (count > port->bulk_out_size) ?
port->bulk_out_size : count;
memcpy(port->write_urb->transfer_buffer, buf, count);
data = port->write_urb->transfer_buffer;
usb_serial_debug_data(debug, &port->dev, __func__, count, data);
/* set up our urb */
usb_fill_bulk_urb(port->write_urb, serial->dev,
usb_sndbulkpipe(serial->dev,
port->bulk_out_endpointAddress),
port->write_urb->transfer_buffer, count,
((serial->type->write_bulk_callback) ?
serial->type->write_bulk_callback :
usb_serial_generic_write_bulk_callback),
port);
/* send the data out the bulk port */
port->write_urb_busy = 1;
result = usb_submit_urb(port->write_urb, GFP_ATOMIC);
if (result) {
dev_err(&port->dev,
"%s - failed submitting write urb, error %d\n",
__func__, result);
/* don't have to grab the lock here, as we will
retry if != 0 */
port->write_urb_busy = 0;
} else
result = count;
return result;
}
/* no bulk out, so return 0 bytes written */
return 0;
}
