-/**
- * ata_sg_setup_one - DMA-map the memory buffer associated with a command.
- * @qc: Command with memory buffer to be mapped.
- *
- * DMA-map the memory buffer associated with queued_cmd @qc.
- *
- * LOCKING:
- * spin_lock_irqsave(host lock)
- *
- * RETURNS:
- * Zero on success, negative on error.
- */
-
-static int ata_sg_setup_one(struct ata_queued_cmd *qc)
-{
- struct ata_port *ap = qc->ap;
- int dir = qc->dma_dir;
- struct scatterlist *sg = qc->__sg;
- dma_addr_t dma_address;
- int trim_sg = 0;
-
- /* we must lengthen transfers to end on a 32-bit boundary */
- qc->pad_len = sg->length & 3;
- if (qc->pad_len) {
- void *pad_buf = ap->pad + (qc->tag * ATA_DMA_PAD_SZ);
- struct scatterlist *psg = &qc->pad_sgent;
-
- WARN_ON(qc->dev->class != ATA_DEV_ATAPI);
-
- memset(pad_buf, 0, ATA_DMA_PAD_SZ);
-
- if (qc->tf.flags & ATA_TFLAG_WRITE)
- memcpy(pad_buf, qc->buf_virt + sg->length - qc->pad_len,
- qc->pad_len);
-
- sg_dma_address(psg) = ap->pad_dma + (qc->tag * ATA_DMA_PAD_SZ);
- sg_dma_len(psg) = ATA_DMA_PAD_SZ;
- /* trim sg */
- sg->length -= qc->pad_len;
- if (sg->length == 0)
- trim_sg = 1;
-
- DPRINTK("padding done, sg->length=%u pad_len=%u\n",
- sg->length, qc->pad_len);
- }
-
- if (trim_sg) {
- qc->n_elem--;
- goto skip_map;
- }
-
- dma_address = dma_map_single(ap->dev, qc->buf_virt,
- sg->length, dir);
- if (dma_mapping_error(dma_address)) {
- /* restore sg */
- sg->length += qc->pad_len;
- return -1;
- }
-
- sg_dma_address(sg) = dma_address;
- sg_dma_len(sg) = sg->length;
-
-skip_map:
- DPRINTK("mapped buffer of %d bytes for %s\n", sg_dma_len(sg),
- qc->tf.flags & ATA_TFLAG_WRITE ? "write" : "read");
-
- return 0;
-}
-