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, 14 insertions, 12 deletions

diff --git a/drivers/ata/pata_ixp4xx_cf.c b/drivers/ata/pata_ixp4xx_cf.c
index 120b5bfa7ce6..030878fedeb5 100644
--- a/drivers/ata/pata_ixp4xx_cf.c
+++ b/drivers/ata/pata_ixp4xx_cf.c
@@ -42,13 +42,13 @@ static int ixp4xx_set_mode(struct ata_link *link, struct ata_device **error)
         return 0;
 }
 
-static void ixp4xx_mmio_data_xfer(struct ata_device *adev, unsigned char *buf,
-                                unsigned int buflen, int write_data)
+static unsigned int ixp4xx_mmio_data_xfer(struct ata_device *dev,
+                                unsigned char *buf, unsigned int buflen, int rw)
 {
         unsigned int i;
         unsigned int words = buflen >> 1;
         u16 *buf16 = (u16 *) buf;
-        struct ata_port *ap = adev->link->ap;
+        struct ata_port *ap = dev->link->ap;
         void __iomem *mmio = ap->ioaddr.data_addr;
         struct ixp4xx_pata_data *data = ap->host->dev->platform_data;
 
@@ -59,30 +59,32 @@ static void ixp4xx_mmio_data_xfer(struct ata_device *adev, unsigned char *buf,
         udelay(100);
 
         /* Transfer multiple of 2 bytes */
-        if (write_data) {
-                for (i = 0; i < words; i++)
-                        writew(buf16[i], mmio);
-        } else {
+        if (rw == READ)
                 for (i = 0; i < words; i++)
                         buf16[i] = readw(mmio);
-        }
+        else
+                for (i = 0; i < words; i++)
+                        writew(buf16[i], mmio);
 
         /* 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);
-                        writew(align_buf[0], mmio);
-                } else {
+                if (rw == READ) {
                         align_buf[0] = readw(mmio);
                         memcpy(trailing_buf, align_buf, 1);
+                } else {
+                        memcpy(align_buf, trailing_buf, 1);
+                        writew(align_buf[0], mmio);
                 }
+                words++;
         }
 
         udelay(100);
         *data->cs0_cfg |= 0x01;
+
+        return words << 1;
 }
 
 static struct scsi_host_template ixp4xx_sht = {