ide: rework the code for selecting the best DMA transfer mode (v3)

Depends on the "ide: fix UDMA/MWDMA/SWDMA masks" patch.

* add ide_hwif_t.udma_filter hook for filtering UDMA mask
  (use it in alim15x3, hpt366, siimage and serverworks drivers)
* add ide_max_dma_mode() for finding best DMA mode for the device
  (loosely based on some older libata-core.c code)
* convert ide_dma_speed() users to use ide_max_dma_mode()
* make ide_rate_filter() take "ide_drive_t *drive" as an argument instead
  of "u8 mode" and teach it to how to use UDMA mask to do filtering
* use ide_rate_filter() in hpt366 driver
* remove no longer needed ide_dma_speed() and *_ratemask()
* unexport eighty_ninty_three()

v2:
* rename ->filter_udma_mask to ->udma_filter
  [ Suggested by Sergei Shtylyov <sshtylyov@ru.mvista.com>. ]

v3:
* updated for scc_pata driver (fixes XFER_UDMA_6 filtering for user-space
  originated transfer mode change requests when 100MHz clock is used)

Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>
diff --git a/drivers/ide/pci/aec62xx.c b/drivers/ide/pci/aec62xx.c
index abe0b1b..099539e 100644
--- a/drivers/ide/pci/aec62xx.c
+++ b/drivers/ide/pci/aec62xx.c
@@ -87,38 +87,12 @@
 	return chipset_table->ultra_settings;
 }
 
-static u8 aec62xx_ratemask (ide_drive_t *drive)
-{
-	ide_hwif_t *hwif	= HWIF(drive);
-	u8 mode;
-
-	switch(hwif->pci_dev->device) {
-		case PCI_DEVICE_ID_ARTOP_ATP865:
-		case PCI_DEVICE_ID_ARTOP_ATP865R:
-			mode = (inb(hwif->channel ?
-				    hwif->mate->dma_status :
-				    hwif->dma_status) & 0x10) ? 4 : 3;
-			break;
-		case PCI_DEVICE_ID_ARTOP_ATP860:
-		case PCI_DEVICE_ID_ARTOP_ATP860R:
-			mode = 2;
-			break;
-		case PCI_DEVICE_ID_ARTOP_ATP850UF:
-		default:
-			return 1;
-	}
-
-	if (!eighty_ninty_three(drive))
-		mode = min(mode, (u8)1);
-	return mode;
-}
-
 static int aec6210_tune_chipset (ide_drive_t *drive, u8 xferspeed)
 {
 	ide_hwif_t *hwif	= HWIF(drive);
 	struct pci_dev *dev	= hwif->pci_dev;
 	u16 d_conf		= 0;
-	u8 speed	= ide_rate_filter(aec62xx_ratemask(drive), xferspeed);
+	u8 speed		= ide_rate_filter(drive, xferspeed);
 	u8 ultra = 0, ultra_conf = 0;
 	u8 tmp0 = 0, tmp1 = 0, tmp2 = 0;
 	unsigned long flags;
@@ -145,7 +119,7 @@
 {
 	ide_hwif_t *hwif	= HWIF(drive);
 	struct pci_dev *dev	= hwif->pci_dev;
-	u8 speed	= ide_rate_filter(aec62xx_ratemask(drive), xferspeed);
+	u8 speed	= ide_rate_filter(drive, xferspeed);
 	u8 unit		= (drive->select.b.unit & 0x01);
 	u8 tmp1 = 0, tmp2 = 0;
 	u8 ultra = 0, drive_conf = 0, ultra_conf = 0;
@@ -183,7 +157,7 @@
 
 static int config_chipset_for_dma (ide_drive_t *drive)
 {
-	u8 speed = ide_dma_speed(drive, aec62xx_ratemask(drive));	
+	u8 speed = ide_max_dma_mode(drive);
 
 	if (!(speed))
 		return 0;