http://lists.denx.de/pipermail/u-boot/2012-April/122594.html
http://patchwork.ozlabs.org/patch/159129/
---

diff --git a/include/ide.h b/include/ide.h
index 8ecc9dd..385e909 100644
--- a/include/ide.h
+++ b/include/ide.h
@@ -24,7 +24,7 @@
 #ifndef	_IDE_H
 #define _IDE_H
 
-#define	IDE_BUS(dev)	(dev >> 1)
+#define IDE_BUS(dev)	(dev / (CONFIG_SYS_IDE_MAXDEVICE / CONFIG_SYS_IDE_MAXBUS))
 
 #define	ATA_CURR_BASE(dev)	(CONFIG_SYS_ATA_BASE_ADDR+ide_bus_offset[IDE_BUS(dev)])