int pxa2xx_spi_map_dma_buffers(struct driver_data *drv_data)
{
    struct spi_message *msg = drv_data->cur_msg;
    struct device *dev = &msg->spi->dev;

    if (!drv_data->cur_chip->enable_dma)
        return 0;

    if (msg->is_dma_mapped)
        return  drv_data->rx_dma && drv_data->tx_dma;

    if (!IS_DMA_ALIGNED(drv_data->rx) || !IS_DMA_ALIGNED(drv_data->tx))
        return 0;

    /* Modify setup if rx buffer is null */
    if (drv_data->rx == NULL) {
        *drv_data->null_dma_buf = 0;
        drv_data->rx = drv_data->null_dma_buf;
        drv_data->rx_map_len = 4;
    } else
        drv_data->rx_map_len = drv_data->len;


    /* Modify setup if tx buffer is null */
    if (drv_data->tx == NULL) {
        *drv_data->null_dma_buf = 0;
        drv_data->tx = drv_data->null_dma_buf;
        drv_data->tx_map_len = 4;
    } else
        drv_data->tx_map_len = drv_data->len;

    /* Stream map the tx buffer. Always do DMA_TO_DEVICE first
     * so we flush the cache *before* invalidating it, in case
     * the tx and rx buffers overlap.
     */
    drv_data->tx_dma = dma_map_single(dev, drv_data->tx,
                                      drv_data->tx_map_len, DMA_TO_DEVICE);
    if (dma_mapping_error(dev, drv_data->tx_dma))
        return 0;

    /* Stream map the rx buffer */
    drv_data->rx_dma = dma_map_single(dev, drv_data->rx,
                                      drv_data->rx_map_len, DMA_FROM_DEVICE);
    if (dma_mapping_error(dev, drv_data->rx_dma)) {
        dma_unmap_single(dev, drv_data->tx_dma,
                         drv_data->tx_map_len, DMA_TO_DEVICE);
        return 0;
    }

    return 1;
}
  void compute(
    in0_type      in,
    out0_type     out,
    Pinfo const&  p_in,
    Pinfo const&  p_out)
  {
    int length = p_out.l_total_size;
    int offset = p_in.l_offset[0];

    if (IS_DMA_ALIGNED(in + offset))
    {
      vector float* a = (vector float*)(in + offset);
      vector float* z = (vector float*)out;

      for (int i = 0; i < (length / 4); ++i)
	*z++ = *a++;
    }
    else
    {
      for (int i = 0; i < length; ++i)
	out[i] = in[offset + i];
    }
  }