cmake: add support for building and installing interfaces

cmake/Sysroot.cmake

@@ -186,6 +186,37 @@ function(sysroot_add_file)
 	set_property(GLOBAL PROPERTY sysroot_target_list ${sysroot_targets} ${sysroot_target_name})
 endfunction(sysroot_add_file)
 
+function(sysroot_add_interface)
+	set(options)
+	set(one_value_args NAME DEST_DIR)
+	set(multi_value_args DEPENDS)
+
+	cmake_parse_arguments(PARSE_ARGV 0 arg
+		"${options}"
+		"${one_value_args}"
+		"${multi_value_args}")
+
+	iface_get_header_path(NAME ${arg_NAME} OUT src_path)
+	iface_get_parent_dir(NAME ${arg_NAME} OUT parent_dir)
+	set(dest_dir ${arg_DEST_DIR}/${parent_dir})
+	set(sysroot_target_name _sysroot-iface-${arg_NAME})
+
+	get_property(sysroot_targets GLOBAL PROPERTY sysroot_target_list)
+	list(LENGTH sysroot_targets nr_sysroot_targets)
+	if (${nr_sysroot_targets} GREATER 0)
+		math(EXPR serialiser_index "${nr_sysroot_targets}-1")
+		list(GET sysroot_targets ${serialiser_index} serialiser)
+	endif ()
+
+	add_custom_target(${sysroot_target_name}
+		COMMAND	${Python_EXECUTABLE} ${sysroot_tool}
+			add-binary ${sysroot_manifest} ${arg_NAME}
+			${dest_dir} ${src_path}
+		COMMENT "Preparing sysroot component: ${arg_ID}"
+		DEPENDS ifgen-${arg_NAME} ${serialiser} ${arg_DEPENDS})
+
+	set_property(GLOBAL PROPERTY sysroot_target_list ${sysroot_targets} ${sysroot_target_name})
+endfunction(sysroot_add_interface)
 
 function(sysroot_finalise)
 	get_property(sysroot_targets GLOBAL PROPERTY sysroot_target_list)