[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>

3 files changed, 44 insertions, 75 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:
diff --git a/drivers/scsi/libata-scsi.c b/drivers/scsi/libata-scsi.c
index ea7a4d8a6fc9..90bf22204668 100644
--- a/drivers/scsi/libata-scsi.c
+++ b/drivers/scsi/libata-scsi.c
@@ -742,15 +742,10 @@ static unsigned int ata_scsi_rw_xlat(struct ata_queued_cmd *qc, u8 *scsicmd)
         u32 n_block;
 
         tf->flags |= ATA_TFLAG_ISADDR | ATA_TFLAG_DEVICE;
-        tf->protocol = qc->dev->xfer_protocol;
 
-        if (scsicmd[0] == READ_10 || scsicmd[0] == READ_6 ||
-            scsicmd[0] == READ_16) {
-                tf->command = qc->dev->read_cmd;
-        } else {
-                tf->command = qc->dev->write_cmd;
+        if (scsicmd[0] == WRITE_10 || scsicmd[0] == WRITE_6 ||
+            scsicmd[0] == WRITE_16)
                 tf->flags |= ATA_TFLAG_WRITE;
-        }
 
         /* Calculate the SCSI LBA and transfer length. */
         switch (scsicmd[0]) {
@@ -812,6 +807,8 @@ static unsigned int ata_scsi_rw_xlat(struct ata_queued_cmd *qc, u8 *scsicmd)
                         tf->device |= (block >> 24) & 0xf;
                 }
 
+                ata_rwcmd_protocol(qc);
+
                 qc->nsect = n_block;
                 tf->nsect = n_block & 0xff;
 
@@ -828,6 +825,8 @@ static unsigned int ata_scsi_rw_xlat(struct ata_queued_cmd *qc, u8 *scsicmd)
                 if ((block >> 28) || (n_block > 256))
                         goto out_of_range;
 
+                ata_rwcmd_protocol(qc);
+
                 /* Convert LBA to CHS */
                 track = (u32)block / dev->sectors;
                 cyl   = track / dev->heads;
diff --git a/drivers/scsi/libata.h b/drivers/scsi/libata.h
index a18f2ac1d4a1..67d752ca8ae2 100644
--- a/drivers/scsi/libata.h
+++ b/drivers/scsi/libata.h
@@ -42,6 +42,7 @@ extern int atapi_enabled;
 extern int ata_qc_complete_noop(struct ata_queued_cmd *qc, u8 drv_stat);
 extern struct ata_queued_cmd *ata_qc_new_init(struct ata_port *ap,
                                       struct ata_device *dev);
+extern void ata_rwcmd_protocol(struct ata_queued_cmd *qc);
 extern void ata_qc_free(struct ata_queued_cmd *qc);
 extern int ata_qc_issue(struct ata_queued_cmd *qc);
 extern int ata_check_atapi_dma(struct ata_queued_cmd *qc);