ide: add IDE_HFLAG_4DRIVES host flag

Add IDE_HFLAG_4DRIVES host flag and use it instead of ide_4drives
chipset type in ide_init_port().

There should be no functional changes caused by this patch.
Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>

drivers/ide/ide-4drives.c

@@ -23,7 +23,8 @@ static const struct ide_port_ops ide_4drives_port_ops = {
 
 static const struct ide_port_info ide_4drives_port_info = {
 	.port_ops		= &ide_4drives_port_ops,
-	.host_flags		= IDE_HFLAG_SERIALIZE | IDE_HFLAG_NO_DMA,
+	.host_flags		= IDE_HFLAG_SERIALIZE | IDE_HFLAG_NO_DMA |
+				  IDE_HFLAG_4DRIVES,
 };
 
 static int __init ide_4drives_init(void)

drivers/ide/ide-probe.c

@@ -1381,8 +1381,8 @@ int ide_host_register(struct ide_host *host, const struct ide_port_info *d,
 		if (ide_probe_port(hwif) == 0)
 			hwif->present = 1;
 
-		if (hwif->chipset != ide_4drives || !hwif->mate ||
-		    !hwif->mate->present) {
+		if ((hwif->host_flags & IDE_HFLAG_4DRIVES) == 0 ||
+		    hwif->mate == NULL || hwif->mate->present == 0) {
 			if (ide_register_port(hwif)) {
 				ide_disable_port(hwif);
 				continue;

include/linux/ide.h

@@ -1327,6 +1327,8 @@ enum {
 	IDE_HFLAG_SERIALIZE		= (1 << 20),
 	/* host is DTC2278 */
 	IDE_HFLAG_DTC2278		= (1 << 21),
+	/* 4 devices on a single set of I/O ports */
+	IDE_HFLAG_4DRIVES		= (1 << 22),
 	/* host is TRM290 */
 	IDE_HFLAG_TRM290		= (1 << 23),
 	/* use 32-bit I/O ops */