1 files changed, 83 insertions, 4 deletions

diff --git a/drivers/ata/sata_promise.c b/drivers/ata/sata_promise.c
index deb26f04f2d7..3fdc7cbd9436 100644
--- a/drivers/ata/sata_promise.c
+++ b/drivers/ata/sata_promise.c
@@ -50,6 +50,7 @@
 enum {
         PDC_MAX_PORTS           = 4,
         PDC_MMIO_BAR            = 3,
+        PDC_MAX_PRD             = LIBATA_MAX_PRD - 1, /* -1 for ASIC PRD bug workaround */
 
         /* register offsets */
         PDC_FEATURE             = 0x04, /* Feature/Error reg (per port) */
@@ -157,7 +158,7 @@ static struct scsi_host_template pdc_ata_sht = {
         .queuecommand           = ata_scsi_queuecmd,
         .can_queue              = ATA_DEF_QUEUE,
         .this_id                = ATA_SHT_THIS_ID,
-        .sg_tablesize           = LIBATA_MAX_PRD,
+        .sg_tablesize           = PDC_MAX_PRD,
         .cmd_per_lun            = ATA_SHT_CMD_PER_LUN,
         .emulated               = ATA_SHT_EMULATED,
         .use_clustering         = ATA_SHT_USE_CLUSTERING,
@@ -523,6 +524,84 @@ static void pdc_atapi_pkt(struct ata_queued_cmd *qc)
         memcpy(buf+31, cdb, cdb_len);
 }
 
+/**
+ *      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;
+        unsigned int idx;
+        const u32 SG_COUNT_ASIC_BUG = 41*4;
+
+        if (!(qc->flags & ATA_QCFLAG_DMAMAP))
+                return;
+
+        WARN_ON(qc->__sg == NULL);
+        WARN_ON(qc->n_elem == 0 && qc->pad_len == 0);
+
+        idx = 0;
+        ata_for_each_sg(sg, qc) {
+                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;
+                }
+        }
+
+        if (idx) {
+                u32 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(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);
+        }
+}
+
 static void pdc_qc_prep(struct ata_queued_cmd *qc)
 {
         struct pdc_port_priv *pp = qc->ap->private_data;
@@ -532,7 +611,7 @@ static void pdc_qc_prep(struct ata_queued_cmd *qc)
 
         switch (qc->tf.protocol) {
         case ATA_PROT_DMA:
-                ata_qc_prep(qc);
+                pdc_fill_sg(qc);
                 /* fall through */
 
         case ATA_PROT_NODATA:
@@ -548,11 +627,11 @@ static void pdc_qc_prep(struct ata_queued_cmd *qc)
                 break;
 
         case ATA_PROT_ATAPI:
-                ata_qc_prep(qc);
+                pdc_fill_sg(qc);
                 break;
 
         case ATA_PROT_ATAPI_DMA:
-                ata_qc_prep(qc);
+                pdc_fill_sg(qc);
                 /*FALLTHROUGH*/
         case ATA_PROT_ATAPI_NODATA:
                 pdc_atapi_pkt(qc);