[PATCH] libata CHS: calculate read/write commands and protocol on the fly (revise #6)

     - merge ata_prot_to_cmd() and ata_dev_set_protocol() as
       ata_rwcmd_protocol()
     - pave road for read/write multiple support
     - remove usage of pre-cached command and protocol values and call
       ata_rwcmd_protocol() instead

Signed-off-by: Albert Lee <albertcc@tw.ibm.com>

==============
Signed-off-by: Jeff Garzik <jgarzik@pobox.com>

1 files changed, 37 insertions, 68 deletions

diff --git a/drivers/scsi/libata-core.c b/drivers/scsi/libata-core.c
index 55d4dee133af..19d3d717faf6 100644
--- a/drivers/scsi/libata-core.c
+++ b/drivers/scsi/libata-core.c
@@ -616,79 +616,53 @@ void ata_tf_from_fis(u8 *fis, struct ata_taskfile *tf)
         tf->hob_nsect   = fis[13];
 }
 
-/**
- *      ata_prot_to_cmd - determine which read/write opcodes to use
- *      @protocol: ATA_PROT_xxx taskfile protocol
- *      @lba48: true is lba48 is present
- *
- *      Given necessary input, determine which read/write commands
- *      to use to transfer data.
- *
- *      LOCKING:
- *      None.
- */
-static int ata_prot_to_cmd(int protocol, int lba48)
-{
-        int rcmd = 0, wcmd = 0;
-
-        switch (protocol) {
-        case ATA_PROT_PIO:
-                if (lba48) {
-                        rcmd = ATA_CMD_PIO_READ_EXT;
-                        wcmd = ATA_CMD_PIO_WRITE_EXT;
-                } else {
-                        rcmd = ATA_CMD_PIO_READ;
-                        wcmd = ATA_CMD_PIO_WRITE;
-                }
-                break;
-
-        case ATA_PROT_DMA:
-                if (lba48) {
-                        rcmd = ATA_CMD_READ_EXT;
-                        wcmd = ATA_CMD_WRITE_EXT;
-                } else {
-                        rcmd = ATA_CMD_READ;
-                        wcmd = ATA_CMD_WRITE;
-                }
-                break;
-
-        default:
-                return -1;
-        }
-
-        return rcmd | (wcmd << 8);
-}
+static const u8 ata_rw_cmds[] = {
+        /* pio multi */
+        ATA_CMD_READ_MULTI,
+        ATA_CMD_WRITE_MULTI,
+        ATA_CMD_READ_MULTI_EXT,
+        ATA_CMD_WRITE_MULTI_EXT,
+        /* pio */
+        ATA_CMD_PIO_READ,
+        ATA_CMD_PIO_WRITE,
+        ATA_CMD_PIO_READ_EXT,
+        ATA_CMD_PIO_WRITE_EXT,
+        /* dma */
+        ATA_CMD_READ,
+        ATA_CMD_WRITE,
+        ATA_CMD_READ_EXT,
+        ATA_CMD_WRITE_EXT
+};
 
 /**
- *      ata_dev_set_protocol - set taskfile protocol and r/w commands
- *      @dev: device to examine and configure
+ *      ata_rwcmd_protocol - set taskfile r/w commands and protocol
+ *      @qc: command to examine and configure
  *
- *      Examine the device configuration, after we have
- *      read the identify-device page and configured the
- *      data transfer mode.  Set internal state related to
- *      the ATA taskfile protocol (pio, pio mult, dma, etc.)
- *      and calculate the proper read/write commands to use.
+ *      Examine the device configuration and tf->flags to calculate 
+ *      the proper read/write commands and protocol to use.
  *
  *      LOCKING:
  *      caller.
  */
-static void ata_dev_set_protocol(struct ata_device *dev)
+void ata_rwcmd_protocol(struct ata_queued_cmd *qc)
 {
-        int pio = (dev->flags & ATA_DFLAG_PIO);
-        int lba48 = (dev->flags & ATA_DFLAG_LBA48);
-        int proto, cmd;
+        struct ata_taskfile *tf = &qc->tf;
+        struct ata_device *dev = qc->dev;
 
-        if (pio)
-                proto = dev->xfer_protocol = ATA_PROT_PIO;
-        else
-                proto = dev->xfer_protocol = ATA_PROT_DMA;
+        int index, lba48, write;
+ 
+        lba48 = (tf->flags & ATA_TFLAG_LBA48) ? 2 : 0;
+        write = (tf->flags & ATA_TFLAG_WRITE) ? 1 : 0;
 
-        cmd = ata_prot_to_cmd(proto, lba48);
-        if (cmd < 0)
-                BUG();
+        if (dev->flags & ATA_DFLAG_PIO) {
+                tf->protocol = ATA_PROT_PIO;
+                index = dev->multi_count ? 0 : 4;
+        } else {
+                tf->protocol = ATA_PROT_DMA;
+                index = 8;
+        }
 
-        dev->read_cmd = cmd & 0xff;
-        dev->write_cmd = (cmd >> 8) & 0xff;
+        tf->command = ata_rw_cmds[index + lba48 + write];
 }
 
 static const char * xfer_mode_str[] = {
@@ -1641,7 +1615,7 @@ static void ata_host_set_dma(struct ata_port *ap, u8 xfer_mode,
  */
 static void ata_set_mode(struct ata_port *ap)
 {
-        unsigned int i, xfer_shift;
+        unsigned int xfer_shift;
         u8 xfer_mode;
         int rc;
 
@@ -1670,11 +1644,6 @@ static void ata_set_mode(struct ata_port *ap)
         if (ap->ops->post_set_mode)
                 ap->ops->post_set_mode(ap);
 
-        for (i = 0; i < 2; i++) {
-                struct ata_device *dev = &ap->device[i];
-                ata_dev_set_protocol(dev);
-        }
-
         return;
 
 err_out: