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, 30 insertions, 16 deletions

diff --git a/drivers/ata/libata-core.c b/drivers/ata/libata-core.c
index 2c9745a74d50..39cedd949ed4 100644
--- a/drivers/ata/libata-core.c
+++ b/drivers/ata/libata-core.c
@@ -4994,7 +4994,7 @@ void swap_buf_le16(u16 *buf, unsigned int buf_words)
 
 /**
  *      ata_data_xfer - Transfer data by PIO
- *      @adev: device to target
+ *      @dev: device to target
  *      @buf: data buffer
  *      @buflen: buffer length
  *      @write_data: read/write
@@ -5003,37 +5003,44 @@ void swap_buf_le16(u16 *buf, unsigned int buf_words)
  *
  *      LOCKING:
  *      Inherited from caller.
+ *
+ *      RETURNS:
+ *      Bytes consumed.
  */
-void ata_data_xfer(struct ata_device *adev, unsigned char *buf,
-                   unsigned int buflen, int write_data)
+unsigned int ata_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;
+        void __iomem *data_addr = ap->ioaddr.data_addr;
         unsigned int words = buflen >> 1;
 
         /* Transfer multiple of 2 bytes */
-        if (write_data)
-                iowrite16_rep(ap->ioaddr.data_addr, buf, words);
+        if (rw == READ)
+                ioread16_rep(data_addr, buf, words);
         else
-                ioread16_rep(ap->ioaddr.data_addr, buf, words);
+                iowrite16_rep(data_addr, buf, words);
 
         /* 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);
-                        iowrite16(le16_to_cpu(align_buf[0]), ap->ioaddr.data_addr);
-                } else {
-                        align_buf[0] = cpu_to_le16(ioread16(ap->ioaddr.data_addr));
+                if (rw == READ) {
+                        align_buf[0] = cpu_to_le16(ioread16(data_addr));
                         memcpy(trailing_buf, align_buf, 1);
+                } else {
+                        memcpy(align_buf, trailing_buf, 1);
+                        iowrite16(le16_to_cpu(align_buf[0]), data_addr);
                 }
+                words++;
         }
+
+        return words << 1;
 }
 
 /**
  *      ata_data_xfer_noirq - Transfer data by PIO
- *      @adev: device to target
+ *      @dev: device to target
  *      @buf: data buffer
  *      @buflen: buffer length
  *      @write_data: read/write
@@ -5043,14 +5050,21 @@ void ata_data_xfer(struct ata_device *adev, unsigned char *buf,
  *
  *      LOCKING:
  *      Inherited from caller.
+ *
+ *      RETURNS:
+ *      Bytes consumed.
  */
-void ata_data_xfer_noirq(struct ata_device *adev, unsigned char *buf,
-                         unsigned int buflen, int write_data)
+unsigned int ata_data_xfer_noirq(struct ata_device *dev, unsigned char *buf,
+                                 unsigned int buflen, int rw)
 {
         unsigned long flags;
+        unsigned int consumed;
+
         local_irq_save(flags);
-        ata_data_xfer(adev, buf, buflen, write_data);
+        consumed = ata_data_xfer(dev, buf, buflen, rw);
         local_irq_restore(flags);
+
+        return consumed;
 }