cmake: enhanced board entry file handling

With a single board now covering what used to be several boards, and
with the ability to omit SoC when building for a single SoC board, then
<board>_defconfig and <board>.dts lookup is improved.

A single SoC board may prefer to keep its defconfig entry point as
<board>_defconfig instead of <board>_<soc>_defconfig.

Also, a multi-SoC board / multi-core SoC board, which used to be
implemented as n-boards may wish to have common _defconfig settings in
a common <board>_defconfig file, and the SoC / cpuset specifics in
<board>_<soc>_defconfig / <board>_<soc>_<core>_defconfig.

Such defconfig support allows also to place build variant specifics in
its own <board>_<soc>_<variant>_defconfig file.

This commit allows multiple _defconfigs for a board and its identifiers.

Similar is implemented for a board's dts file.
If a <board>_<soc>_<core>.dts file is not found, the build system will
instead use <board>_<soc>.dts, and finally fallback to <board>.dts.

This allows a board to have a shared dts file for all board identifiers
which are identical while still support specific dts where required.

A dts file is a devicetree starting point and thus two dts files cannot
be used in together. For such cases, an ordinary board overlay file must
be used.

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

cmake/modules/dts.cmake

@@ -122,9 +122,16 @@ set(DTS_CMAKE                   ${PROJECT_BINARY_DIR}/dts.cmake)
 # modules.
 set(VENDOR_PREFIXES             dts/bindings/vendor-prefixes.txt)
 
-zephyr_build_string(dts_board_string BOARD ${BOARD} BOARD_IDENTIFIER ${BOARD_IDENTIFIER})
+if(NOT DEFINED DTS_SOURCE)
+  zephyr_build_string(dts_board_string BOARD ${BOARD} BOARD_IDENTIFIER ${BOARD_IDENTIFIER} MERGE)
+  foreach(str ${dts_board_string})
+    if(EXISTS ${BOARD_DIR}/${str}.dts)
+      set(DTS_SOURCE ${BOARD_DIR}/${str}.dts)
+      break()
+    endif()
+  endforeach()
+endif()
 
-set_ifndef(DTS_SOURCE ${BOARD_DIR}/${dts_board_string}.dts)
 if(EXISTS ${DTS_SOURCE})
   # We found a devicetree. Check for a board revision overlay.
   if(DEFINED BOARD_REVISION)

cmake/modules/extensions.cmake

@@ -1510,6 +1510,22 @@ endfunction()
 #
 # This is a common function to ensure that build strings are always created
 # in a uniform way.
+# A single string is returned containing the full build string constructed from
+# all arguments.
+#
+# When MERGE is supplied a list of build strings will be returned with the full
+# build string as first item in the list.
+# The full order of build strings returned in the list will be:
+# - Full build string, including identifier and revision
+# - Build string with board variants removed in addition
+# - Build string with cpuset removed in addition
+# - Build string with soc removed in addition
+#
+# If BUILD is supplied, then build type will be appended to each entry in the
+# list above.
+# If REVISION is supplied or obtained as system wide setting a build string
+# with the sanitized revision string will be added in addition to the
+# non-revisioned entry for each entry.
 #
 # Usage:
 #   zephyr_build_string(<out-variable>
@@ -1517,12 +1533,15 @@ endfunction()
 #                       [BOARD_IDENTIFIER <identifier>]
 #                       [BOARD_REVISION <revision>]
 #                       [BUILD <type>]
+#                       [MERGE [REVERSE]]
 #   )
 #
 # <out-variable>:            Output variable where the build string will be returned.
 # BOARD <board>:             Board name to use when creating the build string.
 # BOARD_REVISION <revision>: Board revision to use when creating the build string.
 # BUILD <type>:              Build type to use when creating the build string.
+# MERGE:                     Return a list of build identifiers instead of a single build string.
+# REVERSE:                   Reverse the list before returning it.
 #
 # Examples
 # calling
@@ -1533,10 +1552,20 @@ endfunction()
 #   zephyr_build_string(build_string BOARD alpha BOARD_REVISION 1.0.0 BUILD debug)
 # will return the string `alpha_1_0_0_debug` in `build_string` parameter.
 #
+# calling
+#   zephyr_build_string(build_string BOARD alpha BOARD_IDENTIFIER /soc/bar)
+# will return the string `alpha_soc_bar` in `build_string` parameter.
+#
+# calling
+#   zephyr_build_string(build_string BOARD alpha BOARD_REVISION 1.0.0 BOARD_IDENTIFIER /soc/bar MERGE)
+# will return a list of the following strings
+# `alpha_soc_bar_1_0_0;alpha_soc_bar;alpha_soc_1_0_0;alpha_soc;alpha_1_0_0;alpha` in `build_string` parameter.
+#
 function(zephyr_build_string outvar)
+  set(options MERGE REVERSE)
   set(single_args BOARD BOARD_IDENTIFIER BOARD_REVISION BUILD)
 
-  cmake_parse_arguments(BUILD_STR "" "${single_args}" "" ${ARGN})
+  cmake_parse_arguments(BUILD_STR "${options}" "${single_args}" "" ${ARGN})
   if(BUILD_STR_UNPARSED_ARGUMENTS)
     message(FATAL_ERROR
       "zephyr_build_string(${ARGV0} <val> ...) given unknown arguments:"
@@ -1558,20 +1587,30 @@ function(zephyr_build_string outvar)
     )
   endif()
 
-  set(${outvar} ${BUILD_STR_BOARD})
+  string(REPLACE "/" ";" str_segment_list "${BUILD_STR_BOARD}${BUILD_STR_BOARD_IDENTIFIER}")
+  string(REPLACE "." "_" revision_string "${BUILD_STR_BOARD_REVISION}")
 
-  if(DEFINED BUILD_STR_BOARD_IDENTIFIER)
+  string(JOIN "_" ${outvar} ${str_segment_list} ${revision_string} ${BUILD_STR_BUILD})
-    string(REPLACE "/" "_" variant_string ${BUILD_STR_BOARD_IDENTIFIER})
+
-    set(${outvar} "${${outvar}}${variant_string}")
+  if(BUILD_STR_MERGE)
+    if(DEFINED BUILD_STR_BOARD_REVISION)
+      string(JOIN "_" variant_string ${str_segment_list} ${BUILD_STR_BUILD})
+      list(APPEND ${outvar} "${variant_string}")
+    endif()
+    list(POP_BACK str_segment_list)
+    while(NOT str_segment_list STREQUAL "")
+      if(DEFINED BUILD_STR_BOARD_REVISION)
+        string(JOIN "_" variant_string ${str_segment_list} ${revision_string} ${BUILD_STR_BUILD})
+        list(APPEND ${outvar} "${variant_string}")
+      endif()
+      string(JOIN "_" variant_string ${str_segment_list} ${BUILD_STR_BUILD})
+      list(APPEND ${outvar} "${variant_string}")
+      list(POP_BACK str_segment_list)
+    endwhile()
   endif()
 
-  if(DEFINED BUILD_STR_BOARD_REVISION)
+  if(BUILD_STR_REVERSE)
-    string(REPLACE "." "_" revision_string ${BUILD_STR_BOARD_REVISION})
+    list(REVERSE ${outvar})
-    set(${outvar} "${${outvar}}_${revision_string}")
-  endif()
-
-  if(BUILD_STR_BUILD)
-    set(${outvar} "${${outvar}}_${BUILD_STR_BUILD}")
   endif()
 
   # This updates the provided outvar in parent scope (callers scope)
@@ -2449,6 +2488,7 @@ endfunction()
 #                     files are returned. Configuration files will be:
 #                     - DTS:       Overlay files (.overlay)
 #                     - Kconfig:   Config fragments (.conf)
+#                     - defconfig: defconfig files (_defconfig)
 #                     The conf file search will return existing configuration
 #                     files for the current board.
 #                     CONF_FILES takes the following additional arguments:
@@ -2467,6 +2507,7 @@ endfunction()
 #
 #                     DTS <list>:    List to append DTS overlay files in <path> to
 #                     KCONF <list>:  List to append Kconfig fragment files in <path> to
+#                     DEFCONF <list>: List to append _defconfig files in <path> to
 #                     BUILD <type>:  Build type to include for search.
 #                                    For example:
 #                                    BUILD debug, will look for <board>_debug.conf
@@ -2490,7 +2531,7 @@ Please provide one of following: APPLICATION_ROOT, CONF_FILES")
     set(single_args APPLICATION_ROOT)
   elseif(${ARGV0} STREQUAL CONF_FILES)
     set(options REQUIRED)
-    set(single_args BOARD BOARD_REVISION DTS KCONF BUILD SUFFIX)
+    set(single_args BOARD BOARD_REVISION BOARD_IDENTIFIER DTS KCONF DEFCONFIG BUILD SUFFIX)
     set(multi_args CONF_FILES NAMES)
   endif()
 
@@ -2548,24 +2589,23 @@ Relative paths are only allowed with `-D${ARGV1}=<path>`")
       if(DEFINED BOARD_REVISION)
         set(FILE_BOARD_REVISION ${BOARD_REVISION})
       endif()
+
+      if(DEFINED BOARD_IDENTIFIER)
+        set(FILE_BOARD_IDENTIFIER ${BOARD_IDENTIFIER})
+      endif()
     endif()
 
     if(FILE_NAMES)
       set(dts_filename_list ${FILE_NAMES})
       set(kconf_filename_list ${FILE_NAMES})
     else()
-      zephyr_build_string(filename
+      zephyr_build_string(filename_list
-                          BOARD ${FILE_BOARD}
-                          BUILD ${FILE_BUILD}
-      )
-      set(filename_list ${filename})
-
-      zephyr_build_string(filename
                           BOARD ${FILE_BOARD}
                           BOARD_REVISION ${FILE_BOARD_REVISION}
+                          BOARD_IDENTIFIER ${FILE_BOARD_IDENTIFIER}
                           BUILD ${FILE_BUILD}
+                          MERGE REVERSE
       )
-      list(APPEND filename_list ${filename})
       list(REMOVE_DUPLICATES filename_list)
       set(dts_filename_list ${filename_list})
       list(TRANSFORM dts_filename_list APPEND ".overlay")
@@ -2649,6 +2689,19 @@ Relative paths are only allowed with `-D${ARGV1}=<path>`")
       message(DEPRECATION "prj_<build>.conf was deprecated after Zephyr 3.5,"
                           " you should switch to using -DFILE_SUFFIX instead")
     endif()
+
+    if(FILE_DEFCONFIG)
+      foreach(path ${FILE_CONF_FILES})
+        foreach(filename ${filename_list})
+          if(EXISTS ${path}/${filename}_defconfig)
+            list(APPEND ${FILE_DEFCONFIG} ${path}/${filename}_defconfig)
+          endif()
+        endforeach()
+      endforeach()
+
+      # This updates the provided list in parent scope (callers scope)
+      set(${FILE_DEFCONFIG} ${${FILE_DEFCONFIG}} PARENT_SCOPE)
+    endif()
   endif()
 endfunction()
 

cmake/modules/kconfig.cmake

@@ -74,14 +74,23 @@ else()
   set(KCONFIG_ROOT ${ZEPHYR_BASE}/Kconfig)
 endif()
 
-zephyr_build_string(config_board_string BOARD ${BOARD} BOARD_IDENTIFIER ${BOARD_IDENTIFIER})
-
 if(NOT DEFINED BOARD_DEFCONFIG)
-  set(BOARD_DEFCONFIG ${BOARD_DIR}/${config_board_string}_defconfig)
+  zephyr_file(CONF_FILES ${BOARD_DIR} DEFCONFIG BOARD_DEFCONFIG)
 endif()
-if((DEFINED BOARD_REVISION) AND EXISTS ${BOARD_DIR}/${config_board_string}_${BOARD_REVISION_STRING}.conf)
+
-  set_ifndef(BOARD_REVISION_CONFIG ${BOARD_DIR}/${config_board_string}_${BOARD_REVISION_STRING}.conf)
+if(DEFINED BOARD_REVISION)
+  zephyr_build_string(config_board_string
+                      BOARD ${BOARD}
+                      BOARD_IDENTIFIER ${BOARD_IDENTIFIER}
+                      BOARD_REVISION ${BOARD_REVISION}
+  )
+  set(board_rev_file ${config_board_string})
+  if(EXISTS ${BOARD_DIR}/${board_rev_file}.conf)
+    message(DEPRECATION "Use of '${board_rev_file}.conf' is deprecated, please switch to '${board_rev_file}_defconfig'")
+    set_ifndef(BOARD_REVISION_CONFIG ${BOARD_DIR}/${board_rev_file}.conf)
+  endif()
 endif()
+
 set(DOTCONFIG                  ${PROJECT_BINARY_DIR}/.config)
 set(PARSED_KCONFIG_SOURCES_TXT ${PROJECT_BINARY_DIR}/kconfig/sources.txt)