+/**
+ * pdc_fill_sg - Fill PCI IDE PRD table
+ * @qc: Metadata associated with taskfile to be transferred
+ *
+ * Fill PCI IDE PRD (scatter-gather) table with segments
+ * associated with the current disk command.
+ * Make sure hardware does not choke on it.
+ *
+ * LOCKING:
+ * spin_lock_irqsave(host lock)
+ *
+ */
+static void pdc_fill_sg(struct ata_queued_cmd *qc)
+{
+ struct ata_port *ap = qc->ap;
+ struct scatterlist *sg;
+ const u32 SG_COUNT_ASIC_BUG = 41*4;
+ unsigned int si, idx;
+ u32 len;
+
+ if (!(qc->flags & ATA_QCFLAG_DMAMAP))
+ return;
+
+ idx = 0;
+ for_each_sg(qc->sg, sg, qc->n_elem, si) {
+ u32 addr, offset;
+ u32 sg_len, len;
+
+ /* determine if physical DMA addr spans 64K boundary.
+ * Note h/w doesn't support 64-bit, so we unconditionally
+ * truncate dma_addr_t to u32.
+ */
+ addr = (u32) sg_dma_address(sg);
+ sg_len = sg_dma_len(sg);
+
+ while (sg_len) {
+ offset = addr & 0xffff;
+ len = sg_len;
+ if ((offset + sg_len) > 0x10000)
+ len = 0x10000 - offset;
+
+ ap->prd[idx].addr = cpu_to_le32(addr);
+ ap->prd[idx].flags_len = cpu_to_le32(len & 0xffff);
+ VPRINTK("PRD[%u] = (0x%X, 0x%X)\n", idx, addr, len);
+
+ idx++;
+ sg_len -= len;
+ addr += len;
+ }
+ }
+
+ len = le32_to_cpu(ap->prd[idx - 1].flags_len);
+
+ if (len > SG_COUNT_ASIC_BUG) {
+ u32 addr;
+
+ VPRINTK("Splitting last PRD.\n");
+
+ addr = le32_to_cpu(ap->prd[idx - 1].addr);
+ ap->prd[idx - 1].flags_len = cpu_to_le32(len - SG_COUNT_ASIC_BUG);
+ VPRINTK("PRD[%u] = (0x%X, 0x%X)\n", idx - 1, addr, SG_COUNT_ASIC_BUG);
+
+ addr = addr + len - SG_COUNT_ASIC_BUG;
+ len = SG_COUNT_ASIC_BUG;
+ ap->prd[idx].addr = cpu_to_le32(addr);
+ ap->prd[idx].flags_len = cpu_to_le32(len);
+ VPRINTK("PRD[%u] = (0x%X, 0x%X)\n", idx, addr, len);
+
+ idx++;
+ }
+
+ ap->prd[idx - 1].flags_len |= cpu_to_le32(ATA_PRD_EOT);
+}
+