ide: add short cables support

This patch allows users to override both host and device side cable detection
with "ideX=ata66" kernel parameter.  Thanks to this it should be now possible
to use UDMA > 2 modes on systems (laptops mainly) which use short 40-pin cable
instead of 80-pin one.

Next patches add automatic detection of some systems using short cables.

Changes:

* Rename hwif->udma_four to hwif->cbl and make it u8.

* Convert all existing users accordingly (use ATA_CBL_* defines while at it).  

* Add ATA_CBL_PATA40_SHORT support to ide-iops.c:eighty_ninty_three().

* Use ATA_CBL_PATA40_SHORT for "ideX=ata66" kernel parameter.

Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>
Reviewed-by: Sergei Shtylyov <sshtylyov@ru.mvista.com>
diff --git a/drivers/ide/pci/cmd64x.c b/drivers/ide/pci/cmd64x.c
index b0aa7d03..8631b6c 100644
--- a/drivers/ide/pci/cmd64x.c
+++ b/drivers/ide/pci/cmd64x.c
@@ -517,7 +517,7 @@
 	return 0;
 }
 
-static unsigned int __devinit ata66_cmd64x(ide_hwif_t *hwif)
+static u8 __devinit ata66_cmd64x(ide_hwif_t *hwif)
 {
 	struct pci_dev  *dev	= hwif->pci_dev;
 	u8 bmidecsr = 0, mask	= hwif->channel ? 0x02 : 0x01;
@@ -526,9 +526,9 @@
 	case PCI_DEVICE_ID_CMD_648:
 	case PCI_DEVICE_ID_CMD_649:
  		pci_read_config_byte(dev, BMIDECSR, &bmidecsr);
-		return (bmidecsr & mask) ? 1 : 0;
+		return (bmidecsr & mask) ? ATA_CBL_PATA80 : ATA_CBL_PATA40;
 	default:
-		return 0;
+		return ATA_CBL_PATA40;
 	}
 }
 
@@ -568,8 +568,8 @@
 
 	hwif->ide_dma_check = &cmd64x_config_drive_for_dma;
 
-	if (!hwif->udma_four)
-		hwif->udma_four = ata66_cmd64x(hwif);
+	if (hwif->cbl != ATA_CBL_PATA40_SHORT)
+		hwif->cbl = ata66_cmd64x(hwif);
 
 	switch (dev->device) {
 	case PCI_DEVICE_ID_CMD_648: