libata: update ->data_xfer hook for ATAPI

Depending on how many bytes are transferred as a unit, PIO data
transfer may consume more bytes than requested.  Knowing how much
data is consumed is necessary to determine how much is left for
draining.  This patch update ->data_xfer such that it returns the
number of consumed bytes.

While at it, it also makes the following changes.

* s/adev/dev/
* use READ/WRITE constants for rw indication
* misc clean ups

Signed-off-by: Tejun Heo <htejun@gmail.com>
Signed-off-by: Jeff Garzik <jeff@garzik.org>

1 files changed, 16 insertions, 14 deletions

diff --git a/drivers/ata/pata_scc.c b/drivers/ata/pata_scc.c
index ea2ef9fc15be..55055b27524c 100644
--- a/drivers/ata/pata_scc.c
+++ b/drivers/ata/pata_scc.c
@@ -768,45 +768,47 @@ static u8 scc_bmdma_status (struct ata_port *ap)
 
 /**
  *      scc_data_xfer - Transfer data by PIO
- *      @adev: device for this I/O
+ *      @dev: device for this I/O
  *      @buf: data buffer
  *      @buflen: buffer length
- *      @write_data: read/write
+ *      @rw: read/write
  *
  *      Note: Original code is ata_data_xfer().
  */
 
-static void scc_data_xfer (struct ata_device *adev, unsigned char *buf,
-                           unsigned int buflen, int write_data)
+static unsigned int scc_data_xfer (struct ata_device *dev, unsigned char *buf,
+                                   unsigned int buflen, int rw)
 {
-        struct ata_port *ap = adev->link->ap;
+        struct ata_port *ap = dev->link->ap;
         unsigned int words = buflen >> 1;
         unsigned int i;
         u16 *buf16 = (u16 *) buf;
         void __iomem *mmio = ap->ioaddr.data_addr;
 
         /* Transfer multiple of 2 bytes */
-        if (write_data) {
-                for (i = 0; i < words; i++)
-                        out_be32(mmio, cpu_to_le16(buf16[i]));
-        } else {
+        if (rw == READ)
                 for (i = 0; i < words; i++)
                         buf16[i] = le16_to_cpu(in_be32(mmio));
-        }
+        else
+                for (i = 0; i < words; i++)
+                        out_be32(mmio, cpu_to_le16(buf16[i]));
 
         /* Transfer trailing 1 byte, if any. */
         if (unlikely(buflen & 0x01)) {
                 u16 align_buf[1] = { 0 };
                 unsigned char *trailing_buf = buf + buflen - 1;
 
-                if (write_data) {
-                        memcpy(align_buf, trailing_buf, 1);
-                        out_be32(mmio, cpu_to_le16(align_buf[0]));
-                } else {
+                if (rw == READ) {
                         align_buf[0] = le16_to_cpu(in_be32(mmio));
                         memcpy(trailing_buf, align_buf, 1);
+                } else {
+                        memcpy(align_buf, trailing_buf, 1);
+                        out_be32(mmio, cpu_to_le16(align_buf[0]));
                 }
+                words++;
         }
+
+        return words << 1;
 }
 
 /**