static int spike_do_one_message(void)
{
	int status;

	if (down_interruptible(&spike_dev.spi_sem))
		return -ERESTARTSYS;

	if (!spike_dev.spi_device) {
		up(&spike_dev.spi_sem);
		return -ENODEV;
	}

	spike_prepare_spi_message();

        /* this will put us to sleep until the transfers are complete */
	status = spi_sync(spike_dev.spi_device, &spike_ctl.msg);

	up(&spike_dev.spi_sem);

	return status;
}