ide: add ide_set{_max}_pio() (take 4)

* Add IDE_HFLAG_ABUSE_{PREFETCH,FAST_DEVSEL,DMA_MODES} flags
  and set them in ht6560, cmd640, cmd64x and sc1200 host drivers.

* Add set_pio_mode_abuse() for checking if host driver has a non-standard
  ->tuneproc() implementation and use it in do_special().

* Add ide_set_pio() for setting PIO mode (it uses hwif->pio_mask to find
  the maximum PIO mode supported by the host), also add ide_set_max_pio()
  wrapper for ide_set_pio() to use for auto-tuning.  Convert users of
  ->tuneproc to use ide_set{_max}_pio() where possible.  This leaves only
  do_special(), set_using_pio(), ide_hwif_restore() and ide_set_pio() as
  a direct users of ->tuneproc.

* Remove no longer needed ide_get_best_pio_mode() calls and printk-s
  reporting PIO mode selected from ->tuneproc implementations.

* Rename ->tuneproc hook to ->set_pio_mode and make 'pio' argument const.

* Remove stale comment from ide_config_drive_speed().

v2:
* Fix "ata_" prefix (Noticed by Jeff).

v3:
* Minor cleanups/fixups per Sergei's suggestions.

v4:
* Fix compile problem in drivers/ide/pci/cmd640.c
  (Noticed by Andrew Morton).

* Improve some ->set_pio_mode comments.

Reviewed-by: Sergei Shtylyov <sshtylyov@ru.mvista.com>
Cc: Jeff Garzik <jeff@garzik.org>
Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>
diff --git a/drivers/ide/pci/cmd640.c b/drivers/ide/pci/cmd640.c
index 9689494..f369645 100644
--- a/drivers/ide/pci/cmd640.c
+++ b/drivers/ide/pci/cmd640.c
@@ -628,45 +628,40 @@
 	program_drive_counts (index);
 }
 
-/*
- * Drive PIO mode selection:
- */
-static void cmd640_tune_drive (ide_drive_t *drive, u8 mode_wanted)
+static void cmd640_set_pio_mode(ide_drive_t *drive, const u8 pio)
 {
 	unsigned int index = 0, cycle_time;
 	u8 b;
 
 	while (drive != cmd_drives[index]) {
 		if (++index > 3) {
-			printk("%s: bad news in cmd640_tune_drive\n", drive->name);
+			printk(KERN_ERR "%s: bad news in %s\n",
+					drive->name, __FUNCTION__);
 			return;
 		}
 	}
-	switch (mode_wanted) {
+	switch (pio) {
 		case 6: /* set fast-devsel off */
 		case 7: /* set fast-devsel on */
-			mode_wanted &= 1;
 			b = get_cmd640_reg(CNTRL) & ~0x27;
-			if (mode_wanted)
+			if (pio & 1)
 				b |= 0x27;
 			put_cmd640_reg(CNTRL, b);
-			printk("%s: %sabled cmd640 fast host timing (devsel)\n", drive->name, mode_wanted ? "en" : "dis");
+			printk("%s: %sabled cmd640 fast host timing (devsel)\n", drive->name, (pio & 1) ? "en" : "dis");
 			return;
 
 		case 8: /* set prefetch off */
 		case 9: /* set prefetch on */
-			mode_wanted &= 1;
-			set_prefetch_mode(index, mode_wanted);
-			printk("%s: %sabled cmd640 prefetch\n", drive->name, mode_wanted ? "en" : "dis");
+			set_prefetch_mode(index, pio & 1);
+			printk("%s: %sabled cmd640 prefetch\n", drive->name, (pio & 1) ? "en" : "dis");
 			return;
 	}
 
-	mode_wanted = ide_get_best_pio_mode(drive, mode_wanted, 5);
-	cycle_time = ide_pio_cycle_time(drive, mode_wanted);
-	cmd640_set_mode(index, mode_wanted, cycle_time);
+	cycle_time = ide_pio_cycle_time(drive, pio);
+	cmd640_set_mode(index, pio, cycle_time);
 
 	printk("%s: selected cmd640 PIO mode%d (%dns)",
-		drive->name, mode_wanted, cycle_time);
+		drive->name, pio, cycle_time);
 
 	display_clocks(index);
 }
@@ -766,8 +761,10 @@
 	       cmd_hwif0->name, 'a' + cmd640_chip_version - 1, bus_type, cfr);
 	cmd_hwif0->chipset = ide_cmd640;
 #ifdef CONFIG_BLK_DEV_CMD640_ENHANCED
+	cmd_hwif0->host_flags = IDE_HFLAG_ABUSE_PREFETCH |
+				IDE_HFLAG_ABUSE_FAST_DEVSEL;
 	cmd_hwif0->pio_mask = ATA_PIO5;
-	cmd_hwif0->tuneproc = &cmd640_tune_drive;
+	cmd_hwif0->set_pio_mode = &cmd640_set_pio_mode;
 #endif /* CONFIG_BLK_DEV_CMD640_ENHANCED */
 
 	/*
@@ -822,8 +819,10 @@
 		cmd_hwif1->mate = cmd_hwif0;
 		cmd_hwif1->channel = 1;
 #ifdef CONFIG_BLK_DEV_CMD640_ENHANCED
+		cmd_hwif1->host_flags = IDE_HFLAG_ABUSE_PREFETCH |
+					IDE_HFLAG_ABUSE_FAST_DEVSEL;
 		cmd_hwif1->pio_mask = ATA_PIO5;
-		cmd_hwif1->tuneproc = &cmd640_tune_drive;
+		cmd_hwif1->set_pio_mode = &cmd640_set_pio_mode;
 #endif /* CONFIG_BLK_DEV_CMD640_ENHANCED */
 	}
 	printk(KERN_INFO "%s: %sserialized, secondary interface %s\n", cmd_hwif1->name,