From ca0e5df219a1309d74c801be2b64e28eba2d0c29 Mon Sep 17 00:00:00 2001
From: Guennadi Liakhovetski <guennadi.liakhovetski@linux.intel.com>
Date: Wed, 6 Jan 2021 12:55:12 +0100
Subject: [PATCH] xtensa: don't build and run the reset handler twice

Currently Zephyr links reset-vector.S twice in xtensa builds:
into the bootloader and the main image. It is run at the end
of the boot loader execution and immediately after that again
in the beginning of the main code. This patch adds a
configuration option to select whether to link the file to the
bootloader or to the application. The default is to the
application, as needed e.g. for QEMU, SOF links it to the
bootloader like in native builds.

Signed-off-by: Guennadi Liakhovetski <guennadi.liakhovetski@linux.intel.com>
---
 arch/xtensa/Kconfig                                 |  9 +++++++++
 arch/xtensa/core/startup/CMakeLists.txt             |  5 ++++-
 samples/audio/sof/prj.conf                          |  1 +
 .../intel_adsp/common/bootloader/CMakeLists.txt     |  9 +++++++--
 .../intel_adsp/common/bootloader/start_address.S    | 13 +++++++++++++
 soc/xtensa/intel_adsp/common/main_entry.S           |  4 ++++
 6 files changed, 38 insertions(+), 3 deletions(-)

diff --git a/arch/xtensa/Kconfig b/arch/xtensa/Kconfig
index ba1678dd5a6..436ecf5c285 100644
--- a/arch/xtensa/Kconfig
+++ b/arch/xtensa/Kconfig
@@ -48,6 +48,15 @@ config XTENSA_RESET_VECTOR
 	  This is always needed for the simulator. Real boards may already
 	  implement this in boot ROM.
 
+if XTENSA_RESET_VECTOR
+config RESET_VECTOR_IN_BOOTLOADER
+	bool "Link reset vector into bootloader"
+	default n
+	help
+	  Reset vector code can be either linked in the bootloader or the
+	  application binary. Select "y" to link it into the bootloader.
+endif
+
 config XTENSA_USE_CORE_CRT1
 	bool "Use crt1.S from core"
 	default y
diff --git a/arch/xtensa/core/startup/CMakeLists.txt b/arch/xtensa/core/startup/CMakeLists.txt
index 1c21781ca72..29859e755ac 100644
--- a/arch/xtensa/core/startup/CMakeLists.txt
+++ b/arch/xtensa/core/startup/CMakeLists.txt
@@ -9,8 +9,11 @@ if(CONFIG_XTENSA_RESET_VECTOR)
     -mlongcalls
     )
 
-  zephyr_library_sources(
+  zephyr_library_sources_ifndef(CONFIG_RESET_VECTOR_IN_BOOTLOADER
     reset-vector.S
+    )
+
+  zephyr_library_sources(
     memerror-vector.S
     memctl_default.S
     )
diff --git a/samples/audio/sof/prj.conf b/samples/audio/sof/prj.conf
index 2be9a027b56..41bfe78400a 100644
--- a/samples/audio/sof/prj.conf
+++ b/samples/audio/sof/prj.conf
@@ -3,6 +3,7 @@ CONFIG_SMP=n
 CONFIG_LOG=y
 CONFIG_MP_NUM_CPUS=1
 CONFIG_BUILD_OUTPUT_BIN=n
+CONFIG_RESET_VECTOR_IN_BOOTLOADER=y
 
 # Requires heap_info() be implemented, but no Zephyr wrapper
 CONFIG_DEBUG_MEMORY_USAGE_SCAN=n
diff --git a/soc/xtensa/intel_adsp/common/bootloader/CMakeLists.txt b/soc/xtensa/intel_adsp/common/bootloader/CMakeLists.txt
index 50e939f120d..81f96729a74 100644
--- a/soc/xtensa/intel_adsp/common/bootloader/CMakeLists.txt
+++ b/soc/xtensa/intel_adsp/common/bootloader/CMakeLists.txt
@@ -26,11 +26,14 @@ add_executable(bootloader
   boot_entry.S
   ${ARCH_DIR}/${ARCH}/core/startup/memctl_default.S
   ${ARCH_DIR}/${ARCH}/core/startup/memerror-vector.S
-  ${ARCH_DIR}/${ARCH}/core/startup/reset-vector.S
   boot_loader.c
   start_address.S
   )
 
+target_sources_ifdef(CONFIG_RESET_VECTOR_IN_BOOTLOADER bootloader PRIVATE
+  ${ARCH_DIR}/${ARCH}/core/startup/reset-vector.S
+  )
+
 add_dependencies(bootloader ${SYSCALL_LIST_H_TARGET})
 
 set(zephyr_sdk $ENV{ZEPHYR_SDK_INSTALL_DIR})
@@ -69,7 +72,9 @@ add_custom_command(TARGET bootloader
  )
 
 set_source_files_properties(boot_entry.S PROPERTIES COMPILE_FLAGS -DASSEMBLY)
-set_source_files_properties(${ARCH_DIR}/${ARCH}/core/startup/reset-vector.S PROPERTIES COMPILE_FLAGS -DBOOTLOADER)
+if(CONFIG_RESET_VECTOR_IN_BOOTLOADER)
+  set_source_files_properties(${ARCH_DIR}/${ARCH}/core/startup/reset-vector.S PROPERTIES COMPILE_FLAGS -DBOOTLOADER)
+endif()
 
 target_compile_options(bootloader PUBLIC -fno-inline-functions -mlongcalls -mtext-section-literals -imacros${CMAKE_BINARY_DIR}/zephyr/include/generated/autoconf.h)
 
diff --git a/soc/xtensa/intel_adsp/common/bootloader/start_address.S b/soc/xtensa/intel_adsp/common/bootloader/start_address.S
index fa33ba48641..fae7e3a85a8 100644
--- a/soc/xtensa/intel_adsp/common/bootloader/start_address.S
+++ b/soc/xtensa/intel_adsp/common/bootloader/start_address.S
@@ -9,3 +9,16 @@
 	.global	_start
 	.equ    _start, SOF_TEXT_BASE
 
+#ifndef CONFIG_RESET_VECTOR_IN_BOOTLOADER
+	.begin	literal_prefix	.ResetVector
+	.section		.ResetVector.text, "ax"
+
+	.literal_position
+
+	.align	4
+	.global	__start
+
+__start:
+	movi	a0, 0
+	call0	_start		 /* jump to _start (in crt1-*.S) */
+#endif
diff --git a/soc/xtensa/intel_adsp/common/main_entry.S b/soc/xtensa/intel_adsp/common/main_entry.S
index efcebf91ac2..10614aa0b07 100644
--- a/soc/xtensa/intel_adsp/common/main_entry.S
+++ b/soc/xtensa/intel_adsp/common/main_entry.S
@@ -27,7 +27,11 @@
 
 _MainEntry:
 
+#ifdef CONFIG_RESET_VECTOR_IN_BOOTLOADER
+	j	_start
+#else
 	j	__start
+#endif
 
 	.size	_MainEntry, . - _MainEntry