From 2d5645e57a73928e03feea84e29ec27dfb352b91 Mon Sep 17 00:00:00 2001
From: Andrew Boie <andrew.p.boie@intel.com>
Date: Tue, 3 May 2016 11:47:01 -0700
Subject: [PATCH] nios2: add minimal crt0.S

At the moment this just jumps into prep_c, with comments left
on other things that need to be done. Having this here ensures that
the early boot code isn't discarded by gc-sections.

vector_table.c removed, it isn't the right approach for this CPU.
Proper method for initializing reset and exception vectors still
being investigated.

Change-Id: Id7965c671f1a55c42ecfb65119497405a646bec4
Signed-off-by: Andrew Boie <andrew.p.boie@intel.com>
---
 arch/nios2/core/Makefile                      |  4 +-
 arch/nios2/core/crt0.S                        | 45 +++++++++++++++++++
 .../arch/nios2/asm.h                          | 30 +++----------
 3 files changed, 53 insertions(+), 26 deletions(-)
 create mode 100644 arch/nios2/core/crt0.S
 rename arch/nios2/core/vector_table.c => include/arch/nios2/asm.h (53%)

diff --git a/arch/nios2/core/Makefile b/arch/nios2/core/Makefile
index 7526d9871d5..12a41278b26 100644
--- a/arch/nios2/core/Makefile
+++ b/arch/nios2/core/Makefile
@@ -2,8 +2,8 @@ ccflags-y += -I$(srctree)/kernel/nanokernel/include
 ccflags-y +=-I$(srctree)/arch/$(ARCH)/include
 ccflags-y += -I$(srctree)/kernel/microkernel/include
 
-obj-y += reset.o irq_manage.o fatal.o vector_table.o swap.o thread.o \
-	 cpu_idle.o irq_offload.o prep_c.o
+obj-y += reset.o irq_manage.o fatal.o swap.o thread.o \
+	 cpu_idle.o irq_offload.o prep_c.o crt0.o
 
 obj-$(CONFIG_IRQ_OFFLOAD) += irq_offload.o
 
diff --git a/arch/nios2/core/crt0.S b/arch/nios2/core/crt0.S
new file mode 100644
index 00000000000..98a2304fe9c
--- /dev/null
+++ b/arch/nios2/core/crt0.S
@@ -0,0 +1,45 @@
+/*
+ * Copyright (c) 2016 Intel Corporation
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#define _ASMLANGUAGE
+#include <arch/nios2/asm.h>
+
+/* exports */
+GTEXT(__start)
+
+/* imports */
+GTEXT(_PrepC)
+
+
+SECTION_FUNC(TEXT_START, __start)
+
+	/* TODO initialize instruction cache, if present */
+
+	/* TODO if shadow register sets enabled, ensure we are in set 0 */
+
+	/* TODO initialize data cache, if present */
+
+	/* TODO setup stack pointer */
+
+	/* TODO setup global pointer, if used */
+
+	/* TODO if shadow register sets enabled, interate through them to set
+	 * up. Need to clear r0, write gp, set the execption stack pointer */
+
+	/* Jump into C domain. _PrepC zeroes BSS, copies rw data into RAM,
+	 * and then enters nanokernel _Cstart */
+	call _PrepC
+
diff --git a/arch/nios2/core/vector_table.c b/include/arch/nios2/asm.h
similarity index 53%
rename from arch/nios2/core/vector_table.c
rename to include/arch/nios2/asm.h
index a8745b65f8a..cf30d79d856 100644
--- a/arch/nios2/core/vector_table.c
+++ b/include/arch/nios2/asm.h
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2016 Intel Corporation
+ * Copyright (c) 2015 Intel Corporation
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -14,31 +14,13 @@
  * limitations under the License.
  */
 
-#include <nano_private.h>
+#ifndef _NIOS2_ASM_H
+#define _NIOS2_ASM_H
 
-void __reset_handler(void)
-{
-	/* stub */
-}
-
-void __exception_handler(void)
-{
-	/* stub */
-}
+#include <toolchain.h>
+#include <sections.h>
 
 
-struct vector_table {
-	uint32_t reset;
-	uint32_t exception;
-};
 
-/* FIXME not using CONFIG_RESET_VECTOR or CONFIG_EXCEPTION_VECTOR like we
- * should
- */
-struct vector_table _vector_table _GENERIC_SECTION(.exc_vector_table) = {
-	(uint32_t)__reset_handler,
-	(uint32_t)__exception_handler
-};
-
-extern struct vector_table __start _ALIAS_OF(_vector_table);
+#endif