[PATCH V2] dtc: Merge nodes with label references if possible in plugins

[Fredrik Markstrom <fredrik.markstrom@xxxxxxxxx>]

Commit 8f1b3 (Correct overlay syntactic sugar for generating target-path fragments)
changes what is produced when using label references. Instead of merging the nodes
it creates a new fragment. This patch reverts that behavior for labels but still
generates separate fragments for path references.

Previously the dts below would generate two fragments:

/dts-v1/;
/plugin/;
&x { a: a@0 {};};
&a { b {}; };

I've kept DT_REF upper case in this patch to keep the patch small and readable,
if it is decided to merge this I'll create a v3 where that is fixed

Signed-off-by: Fredrik Markstrom <fredrik.markstrom@xxxxxxxxx>
---
 dtc-lexer.l  |  4 ++--
 dtc-parser.y | 27 +++++++++++++++++++++++++--
 2 files changed, 27 insertions(+), 4 deletions(-)

diff --git a/dtc-lexer.l b/dtc-lexer.l
index 615b7ec..06c0409 100644
--- a/dtc-lexer.l
+++ b/dtc-lexer.l
@@ -213,14 +213,14 @@ static void PRINTF(1, 2) lexical_error(const char *fmt, ...);
 <*>\&{LABEL}	{	/* label reference */
 			DPRINT("Ref: %s\n", yytext+1);
 			yylval.labelref = xstrdup(yytext+1);
-			return DT_REF;
+			return DT_LABEL_REF;
 		}
 
 <*>"&{/"{PATHCHAR}*\}	{	/* new-style path reference */
 			yytext[yyleng-1] = '\0';
 			DPRINT("Ref: %s\n", yytext+2);
 			yylval.labelref = xstrdup(yytext+2);
-			return DT_REF;
+			return DT_PATH_REF;
 		}
 
 <BYTESTRING>[0-9a-fA-F]{2} {
diff --git a/dtc-parser.y b/dtc-parser.y
index 815481a..44748ed 100644
--- a/dtc-parser.y
+++ b/dtc-parser.y
@@ -70,7 +70,8 @@ extern bool treesource_error;
 %token <byte> DT_BYTE
 %token <data> DT_STRING
 %token <labelref> DT_LABEL
-%token <labelref> DT_REF
+%token <labelref> DT_LABEL_REF
+%token <labelref> DT_PATH_REF
 %token DT_INCBIN
 
 %type <data> propdata
@@ -83,6 +84,7 @@ extern bool treesource_error;
 %type <data> bytestring
 %type <prop> propdef
 %type <proplist> proplist
+%type <labelref> DT_REF
 
 %type <node> devicetree
 %type <node> nodedef
@@ -158,6 +160,8 @@ memreserve:
 		}
 	;
 
+DT_REF: DT_LABEL_REF {} | DT_PATH_REF {};
+
 devicetree:
 	  '/' nodedef
 		{
@@ -189,7 +193,7 @@ devicetree:
 				ERROR(&@3, "Label or path %s not found", $3);
 			$$ = $1;
 		}
-	| devicetree DT_REF nodedef
+	| devicetree DT_PATH_REF nodedef
 		{
 			/*
 			 * We rely on the rule being always:
@@ -208,6 +212,25 @@ devicetree:
 			}
 			$$ = $1;
 		}
+	| devicetree DT_LABEL_REF nodedef
+		{
+			struct node *target = get_node_by_ref($1, $2);
+
+			if (target) {
+				merge_nodes(target, $3);
+			} else {
+				/*
+				 * We rely on the rule being always:
+				 *   versioninfo plugindecl memreserves devicetree
+				 * so $-1 is what we want (plugindecl)
+				 */
+				if ($<flags>-1 & DTSF_PLUGIN)
+					add_orphan_node($1, $3, $2);
+				else
+					ERROR(&@2, "Label or path %s not found", $2);
+			}
+			$$ = $1;
+		}
 	| devicetree DT_DEL_NODE DT_REF ';'
 		{
 			struct node *target = get_node_by_ref($1, $3);
-- 
1.9.1