MIPS: Alchemy: devboard register abstraction

All Alchemy development boards have external CPLDs with a few registers
in them.  They all share an identical register layout with only a few
minor differences (except the PB1000) in bit functions and base
addresses.

This patch
- adds a primitive facility to initialize and use these external
  registers,
- replaces all occurrences of bcsr->xxx accesses with calls to the new
  functions (the pb1200 cascade irq handling code is special).
- collects BCSR register information scattered throughout the board
  headers in a central place.

Signed-off-by: Manuel Lauss <manuel.lauss@gmail.com>
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
diff --git a/drivers/mtd/nand/au1550nd.c b/drivers/mtd/nand/au1550nd.c
index 92c334f..43d46e4 100644
--- a/drivers/mtd/nand/au1550nd.c
+++ b/drivers/mtd/nand/au1550nd.c
@@ -19,6 +19,7 @@
 #include <asm/io.h>
 
 #include <asm/mach-au1x00/au1xxx.h>
+#include <asm/mach-db1x00/bcsr.h>
 
 /*
  * MTD structure for NAND controller
@@ -475,7 +476,8 @@
 	/* set gpio206 high */
 	au_writel(au_readl(GPIO2_DIR) & ~(1 << 6), GPIO2_DIR);
 
-	boot_swapboot = (au_readl(MEM_STSTAT) & (0x7 << 1)) | ((bcsr->status >> 6) & 0x1);
+	boot_swapboot = (au_readl(MEM_STSTAT) & (0x7 << 1)) | ((bcsr_read(BCSR_STATUS) >> 6) & 0x1);
+
 	switch (boot_swapboot) {
 	case 0:
 	case 2: