/**
* usb_serial_generic_write_start - kick off an URB write
* @port: Pointer to the &struct usb_serial_port data
*
* Returns zero on success, or a negative errno value
*/
static int usb_serial_generic_write_start(struct usb_serial_port *port)
{
struct urb *urb;
int count, result;
unsigned long flags;
int i;
if (test_and_set_bit_lock(USB_SERIAL_WRITE_BUSY, &port->flags))
return 0;
retry:
spin_lock_irqsave(&port->lock, flags);
if (!port->write_urbs_free || !kfifo_len(&port->write_fifo)) {
clear_bit_unlock(USB_SERIAL_WRITE_BUSY, &port->flags);
spin_unlock_irqrestore(&port->lock, flags);
return 0;
}
i = (int)find_first_bit(&port->write_urbs_free,
ARRAY_SIZE(port->write_urbs));
spin_unlock_irqrestore(&port->lock, flags);
urb = port->write_urbs[i];
count = port->serial->type->prepare_write_buffer(port,
urb->transfer_buffer,
port->bulk_out_size);
urb->transfer_buffer_length = count;
usb_serial_debug_data(debug, &port->dev, __func__, count,
urb->transfer_buffer);
spin_lock_irqsave(&port->lock, flags);
port->tx_bytes += count;
spin_unlock_irqrestore(&port->lock, flags);
clear_bit(i, &port->write_urbs_free);
result = usb_submit_urb(urb, GFP_ATOMIC);
if (result) {
dev_err_console(port, "%s - error submitting urb: %d\n",
__func__, result);
set_bit(i, &port->write_urbs_free);
spin_lock_irqsave(&port->lock, flags);
port->tx_bytes -= count;
spin_unlock_irqrestore(&port->lock, flags);
clear_bit_unlock(USB_SERIAL_WRITE_BUSY, &port->flags);
return result;
}
/* Try sending off another urb, unless in irq context (in which case
* there will be no free urb). */
if (!in_irq())
goto retry;
clear_bit_unlock(USB_SERIAL_WRITE_BUSY, &port->flags);
return 0;
}
static int omninet_write(struct tty_struct *tty, struct usb_serial_port *port,
const unsigned char *buf, int count)
{
struct usb_serial *serial = port->serial;
struct usb_serial_port *wport = serial->port[1];
struct omninet_data *od = usb_get_serial_port_data(port);
struct omninet_header *header = (struct omninet_header *)
wport->write_urb->transfer_buffer;
int result;
dbg("%s - port %d", __func__, port->number);
if (count == 0) {
dbg("%s - write request of 0 bytes", __func__);
return 0;
}
if (!test_and_clear_bit(0, &port->write_urbs_free)) {
dbg("%s - already writing", __func__);
return 0;
}
count = (count > OMNINET_BULKOUTSIZE) ? OMNINET_BULKOUTSIZE : count;
memcpy(wport->write_urb->transfer_buffer + OMNINET_DATAOFFSET,
buf, count);
usb_serial_debug_data(debug, &port->dev, __func__, count,
wport->write_urb->transfer_buffer);
header->oh_seq = od->od_outseq++;
header->oh_len = count;
header->oh_xxx = 0x03;
header->oh_pad = 0x00;
/* send the data out the bulk port, always 64 bytes */
wport->write_urb->transfer_buffer_length = 64;
result = usb_submit_urb(wport->write_urb, GFP_ATOMIC);
if (result) {
set_bit(0, &wport->write_urbs_free);
dev_err_console(port,
"%s - failed submitting write urb, error %d\n",
__func__, result);
} else
result = count;
return result;
}