cmake: kconfig: support for multiple SOC_ROOT

This commit introduces support for multiple SOC_ROOT.

This means that additional SOC_ROOTs specified using -DSOC_ROOT as
argument to CMake will be forming a list together with ${ZEPHYR_BASE}.

This allows for greater flexibility, as developers can now specify
multiple out-of-tree SoCs and not worry about the SoC used for the
board they compile for.

Also it avoid code, such as:
if(BOARD STREQUAL my_board_using_out_of_tree_soc)
  set(SOC_ROOT some/out/of/tree/soc/path)
endif()
in application CMakeLists.txt.

Finally, allowing multiple SOC_ROOTs prepares for specifying SOC_ROOTs
in Zephyr modules.

Signed-off-by: Torsten Rasmussen <Torsten.Rasmussen@nordicsemi.no>

Kconfig.zephyr

@@ -22,10 +22,10 @@ endmenu
 # $ARCH and $BOARD_DIR will be glob patterns when building documentation.
 source "boards/shields/*/Kconfig.defconfig"
 source "$(BOARD_DIR)/Kconfig.defconfig"
-source "$(SOC_DIR)/$(ARCH)/*/Kconfig.defconfig"
+source "$(KCONFIG_BINARY_DIR)/Kconfig.soc.defconfig"
 
 source "boards/Kconfig"
-source "$(SOC_DIR)/Kconfig"
+source "soc/Kconfig"
 source "arch/Kconfig"
 source "kernel/Kconfig"
 source "dts/Kconfig"

cmake/app/boilerplate.cmake

@@ -276,11 +276,9 @@ set(CACHED_SHIELD ${SHIELD} CACHE STRING "Selected shield")
 # be found. It always includes ${ZEPHYR_BASE} at the lowest priority.
 list(APPEND BOARD_ROOT ${ZEPHYR_BASE})
 
-if(NOT SOC_ROOT)
+# 'SOC_ROOT' is a prioritized list of directories where socs may be
-  set(SOC_DIR ${ZEPHYR_BASE}/soc)
+# found. It always includes ${ZEPHYR_BASE}/soc at the lowest priority.
-else()
+list(APPEND SOC_ROOT ${ZEPHYR_BASE})
-  set(SOC_DIR ${SOC_ROOT}/soc)
-endif()
 
 if(NOT ARCH_ROOT)
   set(ARCH_DIR ${ZEPHYR_BASE}/arch)
@@ -493,6 +491,7 @@ include(${ZEPHYR_BASE}/cmake/host-tools.cmake)
 include(${BOARD_DIR}/pre_dt_board.cmake OPTIONAL)
 
 # Build directory for generated KConfig files, such as:
+# - Multiple SOC_ROOT inclusion
 # - Zephyr modules Kconfig files
 set(KCONFIG_BINARY_DIR ${CMAKE_BINARY_DIR}/Kconfig)
 file(MAKE_DIRECTORY ${KCONFIG_BINARY_DIR})
@@ -525,6 +524,21 @@ else()
   set(SOC_PATH ${SOC_FAMILY}/${SOC_SERIES})
 endif()
 
+# Use SOC to search for a 'CMakeLists.txt' file.
+# e.g. zephyr/soc/xtense/intel_apl_adsp/CMakeLists.txt.
+foreach(root ${SOC_ROOT})
+  if(EXISTS ${root}/soc/${ARCH}/${SOC_PATH})
+    set(SOC_DIR ${root}/soc)
+    break()
+  endif()
+endforeach()
+
+if(NOT SOC_DIR)
+  message(FATAL_ERROR "Could not find SOC=${SOC_NAME} for BOARD=${BOARD}, \
+please check your installation. SOC roots searched: \n\
+${SOC_ROOT}")
+endif()
+
 include(${ZEPHYR_BASE}/cmake/target_toolchain.cmake)
 
 project(Zephyr-Kernel VERSION ${PROJECT_VERSION})

cmake/kconfig.cmake

@@ -5,6 +5,22 @@
 file(MAKE_DIRECTORY ${PROJECT_BINARY_DIR}/kconfig/include/generated)
 file(MAKE_DIRECTORY ${PROJECT_BINARY_DIR}/kconfig/include/config)
 
+# Support multiple SOC_ROOT
+set(OPERATION WRITE)
+foreach(root ${SOC_ROOT})
+  file(${OPERATION} ${KCONFIG_BINARY_DIR}/Kconfig.soc.defconfig
+       "osource \"${root}/soc/$(ARCH)/*/Kconfig.defconfig\"\n"
+  )
+  file(${OPERATION} ${KCONFIG_BINARY_DIR}/Kconfig.soc
+       "osource \"${root}/soc/$(ARCH)/*/Kconfig.soc\"\n"
+  )
+  file(${OPERATION} ${KCONFIG_BINARY_DIR}/Kconfig.soc.arch
+       "osource \"${root}/soc/$(ARCH)/Kconfig\"\n"
+       "osource \"${root}/soc/$(ARCH)/*/Kconfig\"\n"
+  )
+  set(OPERATION APPEND)
+endforeach()
+
 if(KCONFIG_ROOT)
   # KCONFIG_ROOT has either been specified as a CMake variable or is
   # already in the CMakeCache.txt. This has precedence.
@@ -41,7 +57,6 @@ set(ENV{PYTHON_EXECUTABLE} ${PYTHON_EXECUTABLE})
 # files for other architectures
 set(ENV{ARCH}      ${ARCH})
 set(ENV{BOARD_DIR} ${BOARD_DIR})
-set(ENV{SOC_DIR}   ${SOC_DIR})
 set(ENV{SHIELD_AS_LIST} "${SHIELD_AS_LIST}")
 set(ENV{KCONFIG_BINARY_DIR} ${KCONFIG_BINARY_DIR})
 set(ENV{ARCH_DIR}   ${ARCH_DIR})
@@ -85,7 +100,6 @@ foreach(kconfig_target
     KCONFIG_CONFIG=${DOTCONFIG}
     ARCH=$ENV{ARCH}
     BOARD_DIR=$ENV{BOARD_DIR}
-    SOC_DIR=$ENV{SOC_DIR}
     SHIELD_AS_LIST=$ENV{SHIELD_AS_LIST}
     KCONFIG_BINARY_DIR=$ENV{KCONFIG_BINARY_DIR}
     ZEPHYR_TOOLCHAIN_VARIANT=${ZEPHYR_TOOLCHAIN_VARIANT}

doc/CMakeLists.txt

@@ -42,6 +42,8 @@ endif()
 # Include version info
 include(${ZEPHYR_BASE}/cmake/version.cmake)
 # Process modules
+set(KCONFIG_BINARY_DIR ${CMAKE_BINARY_DIR}/Kconfig)
+file(MAKE_DIRECTORY ${KCONFIG_BINARY_DIR})
 include(${ZEPHYR_BASE}/cmake/zephyr_module.cmake)
 
 # Note that this won't force fatal error if latexmk is not found.
@@ -195,6 +197,17 @@ else()
   set(SEP :)
 endif()
 
+file(WRITE ${KCONFIG_BINARY_DIR}/Kconfig.soc.defconfig
+     "osource \"${ZEPHYR_BASE}/soc/$(ARCH)/*/Kconfig.defconfig\"\n"
+)
+file(WRITE ${KCONFIG_BINARY_DIR}/Kconfig.soc
+     "osource \"${ZEPHYR_BASE}/soc/$(ARCH)/*/Kconfig.soc\"\n"
+)
+file(WRITE ${KCONFIG_BINARY_DIR}/Kconfig.soc.arch
+     "osource \"${ZEPHYR_BASE}/soc/$(ARCH)/Kconfig\"\n"
+     "osource \"${ZEPHYR_BASE}/soc/$(ARCH)/*/Kconfig\"\n"
+)
+
 add_custom_target(
   kconfig
   COMMAND ${CMAKE_COMMAND} -E make_directory ${RST_OUT}/doc/reference/kconfig
@@ -206,7 +219,7 @@ add_custom_target(
   ARCH=*
   ARCH_DIR=arch
   SOC_DIR=soc
-  CMAKE_BINARY_DIR=${CMAKE_BINARY_DIR}
+  KCONFIG_BINARY_DIR=${KCONFIG_BINARY_DIR}
   KCONFIG_WARN_UNDEF=y
   KCONFIG_TURBO_MODE=${KCONFIG_TURBO_MODE}
   KCONFIG_DOC_MODE=1

scripts/ci/check_compliance.py

@@ -256,6 +256,28 @@ class KconfigCheck(ComplianceTest):
         except subprocess.CalledProcessError as ex:
             self.error(ex.output)
 
+    def write_kconfig_soc(self):
+        """
+        Write KConfig soc files to be sourced during Kconfig parsing
+
+        """
+
+        soc_defconfig_file = os.path.join(tempfile.gettempdir(), "Kconfig.soc.defconfig")
+        soc_file = os.path.join(tempfile.gettempdir(), "Kconfig.soc")
+        soc_arch_file = os.path.join(tempfile.gettempdir(), "Kconfig.soc.arch")
+        try:
+            with open(soc_defconfig_file, 'w', encoding="utf-8") as fp:
+                fp.write(f'osource "{ZEPHYR_BASE}/soc/$(ARCH)/*/Kconfig.defconfig"\n')
+
+            with open(soc_file, 'w', encoding="utf-8") as fp:
+                fp.write(f'osource "{ZEPHYR_BASE}/soc/$(ARCH)/*/Kconfig.soc"\n')
+
+            with open(soc_arch_file, 'w', encoding="utf-8") as fp:
+                fp.write(f'osource "{ZEPHYR_BASE}/soc/$(ARCH)/Kconfig"\n\
+osource "{ZEPHYR_BASE}/soc/$(ARCH)/*/Kconfig"\n')
+        except IOError as ex:
+            self.error(ex.output)
+
     def parse_kconfig(self):
         """
         Returns a kconfiglib.Kconfig object for the Kconfig files. We reuse
@@ -284,7 +306,7 @@ class KconfigCheck(ComplianceTest):
         os.environ["ARCH_DIR"] = "arch/"
         os.environ["BOARD_DIR"] = "boards/*/*"
         os.environ["ARCH"] = "*"
-        os.environ["CMAKE_BINARY_DIR"] = tempfile.gettempdir()
+        os.environ["KCONFIG_BINARY_DIR"] = tempfile.gettempdir()
         os.environ['DEVICETREE_CONF'] = "dummy"
 
         # Older name for DEVICETREE_CONF, for compatibility with older Zephyr
@@ -294,6 +316,9 @@ class KconfigCheck(ComplianceTest):
         # For multi repo support
         self.get_modules(os.path.join(tempfile.gettempdir(), "Kconfig.modules"))
 
+        # For list of SOC_ROOT support
+        self.write_kconfig_soc()
+
         # Tells Kconfiglib to generate warnings for all references to undefined
         # symbols within Kconfig files
         os.environ["KCONFIG_WARN_UNDEF"] = "y"

soc/Kconfig

@@ -3,13 +3,12 @@
 choice
 	prompt "SoC/CPU/Configuration Selection"
 
-source "$(SOC_DIR)/$(ARCH)/*/Kconfig.soc"
+source "$(KCONFIG_BINARY_DIR)/Kconfig.soc"
 
 endchoice
 
 menu "Hardware Configuration"
-osource "$(SOC_DIR)/$(ARCH)/Kconfig"
+source "$(KCONFIG_BINARY_DIR)/Kconfig.soc.arch"
-osource "$(SOC_DIR)/$(ARCH)/*/Kconfig"
 
 
 module = SOC