powerpc: dtb and purgatory support for ppc32

Some code dtb scanning & filling has been borrowed from ppc64.
The old behavior is still available if compiled with GameCube,
other PowerPC platform use the can purgatory and specify a new
dtb.
Booting a self contained elf image (incl. dtb / without the need
for a bd sturct or the like) can be booted. The dtb support is currently
optional. That means if the elf image does not contain a dtb file then
the user has to supply a complete dtb (including mem size, command line,
bus freq., mac addr, ...)

Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>

3 files changed, 73 insertions, 0 deletions

diff --git a/purgatory/arch/ppc/Makefile b/purgatory/arch/ppc/Makefile
index 69fd46c2..0dd18b67 100644
--- a/purgatory/arch/ppc/Makefile
+++ b/purgatory/arch/ppc/Makefile
@@ -2,6 +2,7 @@
 # Purgatory ppc
 #
 
+ppc_PURGATORY_SRCS += purgatory/arch/ppc/v2wrap.S
 ppc_PURGATORY_SRCS += purgatory/arch/ppc/misc.S
 ppc_PURGATORY_SRCS += purgatory/arch/ppc/purgatory-ppc.c
 ppc_PURGATORY_SRCS += purgatory/arch/ppc/console-ppc.c
diff --git a/purgatory/arch/ppc/purgatory-ppc.c b/purgatory/arch/ppc/purgatory-ppc.c
index 077f495a..01d0f386 100644
--- a/purgatory/arch/ppc/purgatory-ppc.c
+++ b/purgatory/arch/ppc/purgatory-ppc.c
@@ -1,6 +1,12 @@
 #include <purgatory.h>
 #include "purgatory-ppc.h"
 
+unsigned int pul_stack = 0;
+unsigned int dt_offset = 0;
+unsigned int kernel = 0;
+unsigned int epapr_magic = 0;
+unsigned int mem_size = 0;
+
 void setup_arch(void)
 {
 	/* Nothing for now */
diff --git a/purgatory/arch/ppc/v2wrap.S b/purgatory/arch/ppc/v2wrap.S
new file mode 100644
index 00000000..79d188f0
--- /dev/null
+++ b/purgatory/arch/ppc/v2wrap.S
@@ -0,0 +1,66 @@
+#
+#  kexec: Linux boots Linux
+#
+#  Copyright (C) 2004 - 2005, Milton D Miller II, IBM Corporation
+#  Copyright (C) 2006, Mohan Kumar M (mohan@in.ibm.com), IBM Corporation
+#  Copyright (C) 2008, Sebastian Andrzej Siewior (bigeasy@linutronix.de), linutronix
+#
+#  This program is free software; you can redistribute it and/or modify
+#  it under the terms of the GNU General Public License as published by
+#  the Free Software Foundation (version 2 of the License).
+#
+#  This program is distributed in the hope that it will be useful,
+#  but WITHOUT ANY WARRANTY; without even the implied warranty of
+#  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+#  GNU General Public License for more details.
+#
+#  You should have received a copy of the GNU General Public License
+#  along with this program; if not, write to the Free Software
+#  Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+#
+
+#include "ppc_asm.h"
+
+# v2wrap.S
+# a wrapper to call purgatory code
+# Invokes ppc kernel with the arguments according to ePAPR v1.0
+# It assumes that the MSR is allready correct.
+
+# calling convention:
+#  no register are considred
+#
+
+#define LOADADDR(rn,name)	\
+	lis     rn,name##@h;	\
+	ori     rn,rn,name##@l;	\
+
+	.globl purgatory_start
+purgatory_start:
+
+	LOADADDR(r6,pul_stack)
+	lwz	r1,0(r6)		#setup stack
+
+	subi	r1, r1, 112
+	bl	purgatory
+	nop
+
+	LOADADDR(r6,kernel)
+	lwz	r4,0(r6)		# load the kernel address
+	mtlr	r4			# prepare branch too
+
+	LOADADDR(r6, dt_offset)
+	lwz	r3, 0(r6)		# load device-tree address
+
+	li	r4, 0
+	li	r5, 0
+
+	LOADADDR(r6, epapr_magic)	# ePAPR magic value
+	lwz	r6, 0(r6)
+
+	LOADADDR(r7, mem_size)		# the Initial Mapped Area
+	lwz	r7, 0(r6)
+
+	li	r8, 0
+	li	r9, 0
+
+	blr				# start kernel