[U-Boot-Users] U-Boot for IXP425 Little-endian

[Anders Grafstrom <grfstrm@users.sourceforge.net>]

Herb Radford wrote:

> I'm going to be using an IXP425 for u-boot and a kernel but in order to 
> re-use existing software I want to use BOTH u-boot and the kernel in 
> little-endian.
> Is there someone who has done this for this target or is working on it?
> I'll do it myself, but I thought I'd ask first.
> 
> Regards, Herb

I'd also like to see little-endian U-boot for IXDP425.
I think you need B0 stepping silicon.
The BYTE_SWAP_EN bit in EXP_CNFG1 needs to be set if I'm not mistaken.
Without it you get messed up flash accesses.

I have not been able to go all the way yet since I got A0 silicon.
But these patches might get you started.
Apply and build with: make LITTLE_ENDIAN=y

You probably need to swap the endianess of the little-endian u-boot.bin
when doing the switch from a big-endian U-boot to little-endian U-boot.

/Anders




diff -uprN -X nodiff u-boot_cvs/board/ixdp425/u-boot.lds u-boot/board/ixdp425/u-boot.lds
--- u-boot_cvs/board/ixdp425/u-boot.lds	2004-10-08 18:59:54.239024000 +0200
+++ u-boot/board/ixdp425/u-boot.lds	2004-10-07 21:21:26.000000000 +0200
@@ -21,7 +21,7 @@
   * MA 02111-1307 USA
   */

-OUTPUT_FORMAT("elf32-bigarm", "elf32-bigarm", "elf32-bigarm")
+OUTPUT_FORMAT("elf32-bigarm", "elf32-bigarm", "elf32-littlearm")
  OUTPUT_ARCH(arm)
  ENTRY(_start)
  SECTIONS
diff -uprN -X nodiff u-boot_cvs/cpu/ixp/config.mk u-boot/cpu/ixp/config.mk
--- u-boot_cvs/cpu/ixp/config.mk	2003-10-14 21:43:56.000000000 +0200
+++ u-boot/cpu/ixp/config.mk	2004-10-07 21:24:44.000000000 +0200
@@ -22,9 +22,16 @@
  # MA 02111-1307 USA
  #

-BIG_ENDIAN = y
+ifdef LITTLE_ENDIAN
+PLATFORM_RELFLAGS += -mlittle-endian
+PLATFORM_LDFLAGS += -EL
+else
+BIG_ENDIAN=y
+PLATFORM_RELFLAGS += -mbig-endian
+PLATFORM_LDFLAGS += -EB
+endif

  PLATFORM_RELFLAGS += -fno-strict-aliasing  -fno-common -ffixed-r8 \
-	-mshort-load-bytes -msoft-float -mbig-endian
+	-mshort-load-bytes -msoft-float

-PLATFORM_CPPFLAGS += -mbig-endian -mapcs-32 -march=armv4 -mtune=strongarm1100
+PLATFORM_CPPFLAGS += -mapcs-32 -march=armv4 -mtune=strongarm1100
diff -uprN -X nodiff u-boot_cvs/cpu/ixp/start.S u-boot/cpu/ixp/start.S
--- u-boot_cvs/cpu/ixp/start.S	2004-06-09 02:11:02.000000000 +0200
+++ u-boot/cpu/ixp/start.S	2004-10-07 20:53:13.000000000 +0200
@@ -130,8 +130,13 @@ FIQ_STACK_START:
  /****************************************************************************/

  reset:
+#ifdef __ARMEB__
  	/* disable mmu, set big-endian */
  	mov	r0, #0xf8
+#else
+	/* disable mmu, set little-endian */
+	mov	r0, #0x78
+#endif
  	mcr	p15, 0, r0, c1, c0, 0
  	CPWAIT  r0