powerpc/boot: Add OPAL console to epapr wrappers

This patch adds an OPAL console backend to the powerpc boot wrapper so
that decompression failures inside the wrapper can be reported to the
user. This is important since it typically indicates data corruption in
the firmware and other nasty things.

Currently this only works when building a little endian kernel. When
compiling a 64 bit BE kernel the wrapper is always build 32 bit to be
compatible with some 32 bit firmwares. BE support will be added at a
later date. Another limitation of this is that only the "raw" type of
OPAL console is supported, however machines that provide a hvsi console
also provide a raw console so this is not an issue in practice.

Actually-written-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Oliver O'Halloran <oohall@gmail.com>
[mpe: Move #ifdef __powerpc64__ to avoid warnings on 32-bit]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
diff --git a/arch/powerpc/boot/ppc_asm.h b/arch/powerpc/boot/ppc_asm.h
index 35ea60c..b03373d 100644
--- a/arch/powerpc/boot/ppc_asm.h
+++ b/arch/powerpc/boot/ppc_asm.h
@@ -61,6 +61,10 @@
 
 #define SPRN_TBRL	268
 #define SPRN_TBRU	269
+#define SPRN_HSRR0	0x13A	/* Hypervisor Save/Restore 0 */
+#define SPRN_HSRR1	0x13B	/* Hypervisor Save/Restore 1 */
+
+#define MSR_LE		0x0000000000000001
 
 #define FIXUP_ENDIAN						   \
 	tdi   0, 0, 0x48; /* Reverse endian of b . + 8		*/ \