[PATCH] libata: improve xfer mask constants and update ata_mode_string()

Add ATA_BITS_*, ATA_MASK_* macros and reorder xfer_mask fields such
that higher transfer mode is placed at higher order bit.  As thie
reordering breaks ata_mode_string(), this patch also rewrites
ata_mode_string().

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

2 files changed, 29 insertions, 31 deletions

diff --git a/drivers/scsi/libata-core.c b/drivers/scsi/libata-core.c
index 6d8aa86f2f6b..18418c82d6f6 100644
--- a/drivers/scsi/libata-core.c
+++ b/drivers/scsi/libata-core.c
@@ -232,6 +232,14 @@ int ata_rwcmd_protocol(struct ata_queued_cmd *qc)
 }
 
 static const char * const xfer_mode_str[] = {
+        "PIO0",
+        "PIO1",
+        "PIO2",
+        "PIO3",
+        "PIO4",
+        "MWDMA0",
+        "MWDMA1",
+        "MWDMA2",
         "UDMA/16",
         "UDMA/25",
         "UDMA/33",
@@ -240,49 +248,31 @@ static const char * const xfer_mode_str[] = {
         "UDMA/100",
         "UDMA/133",
         "UDMA7",
-        "MWDMA0",
-        "MWDMA1",
-        "MWDMA2",
-        "PIO0",
-        "PIO1",
-        "PIO2",
-        "PIO3",
-        "PIO4",
 };
 
 /**
- *      ata_udma_string - convert UDMA bit offset to string
- *      @mask: mask of bits supported; only highest bit counts.
+ *      ata_mode_string - convert xfer_mask to string
+ *      @xfer_mask: mask of bits supported; only highest bit counts.
  *
  *      Determine string which represents the highest speed
- *      (highest bit in @udma_mask).
+ *      (highest bit in @modemask).
  *
  *      LOCKING:
  *      None.
  *
  *      RETURNS:
  *      Constant C string representing highest speed listed in
- *      @udma_mask, or the constant C string "<n/a>".
+ *      @mode_mask, or the constant C string "<n/a>".
  */
 
-static const char *ata_mode_string(unsigned int mask)
+static const char *ata_mode_string(unsigned int xfer_mask)
 {
-        int i;
-
-        for (i = 7; i >= 0; i--)
-                if (mask & (1 << i))
-                        goto out;
-        for (i = ATA_SHIFT_MWDMA + 2; i >= ATA_SHIFT_MWDMA; i--)
-                if (mask & (1 << i))
-                        goto out;
-        for (i = ATA_SHIFT_PIO + 4; i >= ATA_SHIFT_PIO; i--)
-                if (mask & (1 << i))
-                        goto out;
+        int highbit;
 
+        highbit = fls(xfer_mask) - 1;
+        if (highbit >= 0 && highbit < ARRAY_SIZE(xfer_mode_str))
+                return xfer_mode_str[highbit];
         return "<n/a>";
-
-out:
-        return xfer_mode_str[i];
 }
 
 /**
diff --git a/include/linux/libata.h b/include/linux/libata.h
index 15674923cc84..239408ecfddf 100644
--- a/include/linux/libata.h
+++ b/include/linux/libata.h
@@ -188,11 +188,19 @@ enum {
         PORT_DISABLED           = 2,
 
         /* encoding various smaller bitmaps into a single
-         * unsigned long bitmap
+         * unsigned int bitmap
          */
-        ATA_SHIFT_UDMA          = 0,
-        ATA_SHIFT_MWDMA         = 8,
-        ATA_SHIFT_PIO           = 11,
+        ATA_BITS_PIO            = 5,
+        ATA_BITS_MWDMA          = 3,
+        ATA_BITS_UDMA           = 8,
+
+        ATA_SHIFT_PIO           = 0,
+        ATA_SHIFT_MWDMA         = ATA_SHIFT_PIO + ATA_BITS_PIO,
+        ATA_SHIFT_UDMA          = ATA_SHIFT_MWDMA + ATA_BITS_MWDMA,
+
+        ATA_MASK_PIO            = ((1 << ATA_BITS_PIO) - 1) << ATA_SHIFT_PIO,
+        ATA_MASK_MWDMA          = ((1 << ATA_BITS_MWDMA) - 1) << ATA_SHIFT_MWDMA,
+        ATA_MASK_UDMA           = ((1 << ATA_BITS_UDMA) - 1) << ATA_SHIFT_UDMA,
 
         /* size of buffer to pad xfers ending on unaligned boundaries */
         ATA_DMA_PAD_SZ          = 4,