libata: add ata_sg_is_last() helper, use it in several drivers

3 files changed, 23 insertions, 16 deletions

diff --git a/drivers/scsi/pdc_adma.c b/drivers/scsi/pdc_adma.c
index 53b8db4be1a9..c6825da6ae20 100644
--- a/drivers/scsi/pdc_adma.c
+++ b/drivers/scsi/pdc_adma.c
@@ -293,14 +293,14 @@ static void adma_eng_timeout(struct ata_port *ap)
 
 static int adma_fill_sg(struct ata_queued_cmd *qc)
 {
-        struct scatterlist *sg = qc->sg;
+        struct scatterlist *sg;
         struct ata_port *ap = qc->ap;
         struct adma_port_priv *pp = ap->private_data;
         u8  *buf = pp->pkt;
-        int nelem, i = (2 + buf[3]) * 8;
+        int i = (2 + buf[3]) * 8;
         u8 pFLAGS = pORD | ((qc->tf.flags & ATA_TFLAG_WRITE) ? pDIRO : 0);
 
-        for (nelem = 0; nelem < qc->n_elem; nelem++,sg++) {
+        ata_for_each_sg(sg, qc) {
                 u32 addr;
                 u32 len;
 
@@ -312,7 +312,7 @@ static int adma_fill_sg(struct ata_queued_cmd *qc)
                 *(__le32 *)(buf + i) = cpu_to_le32(len);
                 i += 4;
 
-                if ((nelem + 1) == qc->n_elem)
+                if (ata_sg_is_last(sg, qc))
                         pFLAGS |= pEND;
                 buf[i++] = pFLAGS;
                 buf[i++] = qc->dev->dma_mode & 0xf;
diff --git a/drivers/scsi/sata_mv.c b/drivers/scsi/sata_mv.c
index d457f5673476..be7c378dcd36 100644
--- a/drivers/scsi/sata_mv.c
+++ b/drivers/scsi/sata_mv.c
@@ -785,22 +785,24 @@ static void mv_port_stop(struct ata_port *ap)
 static void mv_fill_sg(struct ata_queued_cmd *qc)
 {
         struct mv_port_priv *pp = qc->ap->private_data;
-        unsigned int i;
+        unsigned int i = 0;
+        struct scatterlist *sg;
 
-        for (i = 0; i < qc->n_elem; i++) {
+        ata_for_each_sg(sg, qc) {
                 u32 sg_len;
                 dma_addr_t addr;
 
-                addr = sg_dma_address(&qc->sg[i]);
-                sg_len = sg_dma_len(&qc->sg[i]);
+                addr = sg_dma_address(sg);
+                sg_len = sg_dma_len(sg);
 
                 pp->sg_tbl[i].addr = cpu_to_le32(addr & 0xffffffff);
                 pp->sg_tbl[i].addr_hi = cpu_to_le32((addr >> 16) >> 16);
                 assert(0 == (sg_len & ~MV_DMA_BOUNDARY));
                 pp->sg_tbl[i].flags_size = cpu_to_le32(sg_len);
-        }
-        if (0 < qc->n_elem) {
-                pp->sg_tbl[qc->n_elem - 1].flags_size |= EPRD_FLAG_END_OF_TBL;
+                if (ata_sg_is_last(sg, qc))
+                        pp->sg_tbl[i].flags_size |= cpu_to_le32(EPRD_FLAG_END_OF_TBL);
+
+                i++;
         }
 }
 
diff --git a/drivers/scsi/sata_sil24.c b/drivers/scsi/sata_sil24.c
index 19857814d69f..e16d1815cda0 100644
--- a/drivers/scsi/sata_sil24.c
+++ b/drivers/scsi/sata_sil24.c
@@ -416,15 +416,20 @@ static void sil24_phy_reset(struct ata_port *ap)
 static inline void sil24_fill_sg(struct ata_queued_cmd *qc,
                                  struct sil24_cmd_block *cb)
 {
-        struct scatterlist *sg = qc->sg;
         struct sil24_sge *sge = cb->sge;
-        unsigned i;
+        struct scatterlist *sg;
+        unsigned int idx = 0;
 
-        for (i = 0; i < qc->n_elem; i++, sg++, sge++) {
+        ata_for_each_sg(sg, qc) {
                 sge->addr = cpu_to_le64(sg_dma_address(sg));
                 sge->cnt = cpu_to_le32(sg_dma_len(sg));
-                sge->flags = 0;
-                sge->flags = i < qc->n_elem - 1 ? 0 : cpu_to_le32(SGE_TRM);
+                if (ata_sg_is_last(sg, qc))
+                        sge->flags = cpu_to_le32(SGE_TRM);
+                else
+                        sge->flags = 0;
+
+                sge++;
+                idx++;
         }
 }