cmake: linker generator: ld: Files for section input patterns

For CONFIG_USERSPACE the input from gen_app_partitions.py there is
a need to be able to specify input files as well as input sections
patterns for zephyr_linker_section_configure().  This is used for
app partitions from libraries (which generate input patterns like
foo.a:*(.data*)).

This adds documentation to zephyr_linker_section_configure() to clarify
what INPUT allows, and also adds some parsing tricks to ld_script.cmake
to properly add the file patterns when they are missing.

Signed-off-by: Björn Bergman <bjorn.bergman@iar.com>

Author: bjorniuppsala

cmake/linker/ld/ld_script.cmake

@@ -304,16 +304,23 @@ function(section_to_string)
         set(current_offset ${offset})
       endif()
 
-      if(keep AND sort)
-        set(TEMP "${TEMP}\n  KEEP(*(${SORT_TYPE_${sort}}(${setting})));")
-      elseif(SETTINGS_SORT)
-        message(WARNING "Not tested")
-        set(TEMP "${TEMP}\n  *(${SORT_TYPE_${sort}}(${setting}));")
-      elseif(keep)
-        set(TEMP "${TEMP}\n  KEEP(*(${setting}));")
+      #setting may have file-pattern or not.
+      if(setting MATCHES "(.+)\\((.+)\\)")
+        set(file_pattern "${CMAKE_MATCH_1}")
+        set(section_pattern "${CMAKE_MATCH_2}")
       else()
-        set(TEMP "${TEMP}\n  *(${setting})")
+        set(file_pattern "*")
+        set(section_pattern "${setting}")
       endif()
+
+      if(sort)
+        set(section_pattern "${SORT_TYPE_${sort}}(${section_pattern})")
+      endif()
+      set(pattern "${file_pattern}(${section_pattern})")
+      if(keep)
+        set(pattern "KEEP(${pattern})")
+      endif()
+      set(TEMP "${TEMP}\n  ${pattern};")
     endforeach()
 
     if(DEFINED symbol_end)

cmake/modules/extensions.cmake

@@ -5308,6 +5308,10 @@ endfunction()
 # ANY                 : ANY section flag in scatter file.
 #                       The FLAGS and ANY arguments only has effect for scatter files.
 # INPUT <input>       : Input section name or list of input section names.
+#                       <input> is either just a section name ".data*" or
+#                       <file-pattern>(<section-patterns>... )
+#                       <file-pattern> is [library.a:]file
+#                       e.g. foo.a:bar.o(.data*)
 #
 function(zephyr_linker_section_configure)
   set(options     "ANY;FIRST;KEEP")