5 files changed, 55 insertions, 0 deletions

diff --git a/scripts/dtc/checks.c b/scripts/dtc/checks.c
index c07ba4da9e3..40879677c8c 100644
--- a/scripts/dtc/checks.c
+++ b/scripts/dtc/checks.c
@@ -579,6 +579,8 @@ static void fixup_phandle_references(struct check *c, struct dt_info *dti,
 
 			phandle = get_node_phandle(dt, refnode);
 			*((fdt32_t *)(prop->val.val + m->offset)) = cpu_to_fdt32(phandle);
+
+			reference_node(refnode);
 		}
 	}
 }
@@ -609,11 +611,21 @@ static void fixup_path_references(struct check *c, struct dt_info *dti,
 			path = refnode->fullpath;
 			prop->val = data_insert_at_marker(prop->val, m, path,
 							  strlen(path) + 1);
+
+			reference_node(refnode);
 		}
 	}
 }
 ERROR(path_references, fixup_path_references, NULL, &duplicate_node_names);
 
+static void fixup_omit_unused_nodes(struct check *c, struct dt_info *dti,
+				    struct node *node)
+{
+	if (node->omit_if_unused && !node->is_referenced)
+		delete_node(node);
+}
+ERROR(omit_unused_nodes, fixup_omit_unused_nodes, NULL, &phandle_references, &path_references);
+
 /*
  * Semantic checks
  */
@@ -1367,6 +1379,7 @@ static struct check *check_table[] = {
 
 	&explicit_phandles,
 	&phandle_references, &path_references,
+	&omit_unused_nodes,
 
 	&address_cells_is_cell, &size_cells_is_cell, &interrupt_cells_is_cell,
 	&device_type_is_string, &model_is_string, &status_is_string,
diff --git a/scripts/dtc/dtc-lexer.l b/scripts/dtc/dtc-lexer.l
index 24af5499775..d3694d6cf20 100644
--- a/scripts/dtc/dtc-lexer.l
+++ b/scripts/dtc/dtc-lexer.l
@@ -152,6 +152,13 @@ static void PRINTF(1, 2) lexical_error(const char *fmt, ...);
 			return DT_DEL_NODE;
 		}
 
+<*>"/omit-if-no-ref/"	{
+			DPRINT("Keyword: /omit-if-no-ref/\n");
+			DPRINT("<PROPNODENAME>\n");
+			BEGIN(PROPNODENAME);
+			return DT_OMIT_NO_REF;
+		}
+
 <*>{LABEL}:	{
 			DPRINT("Label: %s\n", yytext);
 			yylval.labelref = xstrdup(yytext);
diff --git a/scripts/dtc/dtc-parser.y b/scripts/dtc/dtc-parser.y
index 44af170abfe..66ff7f7d8eb 100644
--- a/scripts/dtc/dtc-parser.y
+++ b/scripts/dtc/dtc-parser.y
@@ -63,6 +63,7 @@ extern bool treesource_error;
 %token DT_BITS
 %token DT_DEL_PROP
 %token DT_DEL_NODE
+%token DT_OMIT_NO_REF
 %token <propnodename> DT_PROPNODENAME
 %token <integer> DT_LITERAL
 %token <integer> DT_CHAR_LITERAL
@@ -219,6 +220,18 @@ devicetree:
 
 			$$ = $1;
 		}
+	| devicetree DT_OMIT_NO_REF DT_REF ';'
+		{
+			struct node *target = get_node_by_ref($1, $3);
+
+			if (target)
+				omit_node_if_unused(target);
+			else
+				ERROR(&@3, "Label or path %s not found", $3);
+
+
+			$$ = $1;
+		}
 	;
 
 nodedef:
@@ -523,6 +536,10 @@ subnode:
 		{
 			$$ = name_node(build_node_delete(), $2);
 		}
+	| DT_OMIT_NO_REF subnode
+		{
+			$$ = omit_node_if_unused($2);
+		}
 	| DT_LABEL subnode
 		{
 			add_label(&$2->labels, $1);
diff --git a/scripts/dtc/dtc.h b/scripts/dtc/dtc.h
index 3b18a42b866..6d667701ab6 100644
--- a/scripts/dtc/dtc.h
+++ b/scripts/dtc/dtc.h
@@ -168,6 +168,8 @@ struct node {
 
 	struct label *labels;
 	const struct bus_type *bus;
+
+	bool omit_if_unused, is_referenced;
 };
 
 #define for_each_label_withdel(l0, l) \
@@ -202,6 +204,8 @@ struct property *reverse_properties(struct property *first);
 struct node *build_node(struct property *proplist, struct node *children);
 struct node *build_node_delete(void);
 struct node *name_node(struct node *node, char *name);
+struct node *omit_node_if_unused(struct node *node);
+struct node *reference_node(struct node *node);
 struct node *chain_node(struct node *first, struct node *list);
 struct node *merge_nodes(struct node *old_node, struct node *new_node);
 struct node *add_orphan_node(struct node *old_node, struct node *new_node, char *ref);
diff --git a/scripts/dtc/livetree.c b/scripts/dtc/livetree.c
index 57b7db2ed15..81b6c484542 100644
--- a/scripts/dtc/livetree.c
+++ b/scripts/dtc/livetree.c
@@ -134,6 +134,20 @@ struct node *name_node(struct node *node, char *name)
 	return node;
 }
 
+struct node *omit_node_if_unused(struct node *node)
+{
+	node->omit_if_unused = 1;
+
+	return node;
+}
+
+struct node *reference_node(struct node *node)
+{
+	node->is_referenced = 1;
+
+	return node;
+}
+
 struct node *merge_nodes(struct node *old_node, struct node *new_node)
 {
 	struct property *new_prop, *old_prop;