Build: Added support for out-of-tree Arch

Introduces the ARCH_ROOT argument, similar to BOARD_ROOT and SOC_ROOT.
This enables support for out-of-tree architectures.

The ARCH_ROOT out-of-tree layout is expected to be the following:
 * ${ARCH_ROOT}/arch/${ARCH}/
 * ${ARCH_ROOT}/include/arch/${ARCH}/ (Optional)

Signed-off-by: Klaus Petersen <kape@oticon.com>

CMakeLists.txt

@@ -59,7 +59,7 @@ zephyr_library_named(zephyr)
 
 zephyr_include_directories(
   kernel/include
-  arch/${ARCH}/include
+  ${ARCH_DIR}/${ARCH}/include
   include
   include/drivers
   ${PROJECT_BINARY_DIR}/include/generated
@@ -690,7 +690,7 @@ gen_kobj(KOBJ_INCLUDE_PATH)
 
 set(OFFSETS_LIB offsets)
 
-set(OFFSETS_C_PATH ${ZEPHYR_BASE}/arch/${ARCH}/core/offsets/offsets.c)
+set(OFFSETS_C_PATH ${ARCH_DIR}/${ARCH}/core/offsets/offsets.c)
 set(OFFSETS_H_PATH ${PROJECT_BINARY_DIR}/include/generated/offsets.h)
 
 add_library(          ${OFFSETS_LIB} OBJECT ${OFFSETS_C_PATH})

arch/CMakeLists.txt

@@ -1,4 +1,4 @@
 add_definitions(-D__ZEPHYR_SUPERVISOR__)
 
 add_subdirectory(common)
-add_subdirectory(${ARCH})
+add_subdirectory(${ARCH_DIR}/${ARCH} arch/${ARCH})

arch/Kconfig

@@ -12,7 +12,7 @@
 # overriden (by defining symbols in multiple locations)
 
 # Note: $ARCH might be a glob pattern
-source "arch/$(ARCH)/Kconfig"
+source "$(ARCH_DIR)/$(ARCH)/Kconfig"
 
 choice
 	prompt "Architecture"

cmake/app/boilerplate.cmake

@@ -255,6 +255,12 @@ else()
   set(SOC_DIR ${SOC_ROOT}/soc)
 endif()
 
+if(NOT ARCH_ROOT)
+  set(ARCH_DIR ${ZEPHYR_BASE}/arch)
+else()
+  set(ARCH_DIR ${ARCH_ROOT}/arch)
+endif()
+
 # Use BOARD to search for a '_defconfig' file.
 # e.g. zephyr/boards/arm/96b_carbon_nrf51/96b_carbon_nrf51_defconfig.
 # When found, use that path to infer the ARCH we are building for.

cmake/kconfig.cmake

@@ -30,6 +30,7 @@ set(ENV{ARCH}      ${ARCH})
 set(ENV{BOARD_DIR} ${BOARD_DIR})
 set(ENV{SOC_DIR}   ${SOC_DIR})
 set(ENV{PROJECT_BINARY_DIR} ${PROJECT_BINARY_DIR})
+set(ENV{ARCH_DIR}   ${ARCH_DIR})
 
 add_custom_target(
   menuconfig
@@ -43,6 +44,7 @@ add_custom_target(
   SOC_DIR=$ENV{SOC_DIR}
   PROJECT_BINARY_DIR=$ENV{PROJECT_BINARY_DIR}
   ZEPHYR_TOOLCHAIN_VARIANT=${ZEPHYR_TOOLCHAIN_VARIANT}
+  ARCH_DIR=$ENV{ARCH_DIR}
   ${PYTHON_EXECUTABLE} ${ZEPHYR_BASE}/scripts/kconfig/menuconfig.py ${KCONFIG_ROOT}
   WORKING_DIRECTORY ${PROJECT_BINARY_DIR}/kconfig
   USES_TERMINAL

doc/CMakeLists.txt

@@ -142,6 +142,7 @@ add_custom_target(
   KERNELVERSION=${KERNELVERSION}
   BOARD_DIR=boards/*/*/
   ARCH=*
+  ARCH_DIR=arch/
   SOC_DIR=soc/
   SRCARCH=x86
   KCONFIG_TURBO_MODE=${KCONFIG_TURBO_MODE}