[PATCH 2/4] Implements new features for updating existing device tree nodes.

[John Bonesio]

This is interesting when the /include/ "<filename>" feature is used. This way
we can create base device tree source files for a family of systems and modify
the device tree for a specific system.

The current sytem allows an existing node to be extended with new properties
and subnodes.

The new features allow an existing node to be replaced completely by the new
properties and subnodes. The new features also allow an existing node to be
deleted.

Signed-off-by: John Bonesio <bones at secretlab.ca>
---

 dtc-lexer.l  |    6 ++++++
 dtc-parser.y |   11 +++++++++++
 dtc.h        |    1 +
 livetree.c   |   18 ++++++++++++++++++
 4 files changed, 36 insertions(+), 0 deletions(-)

diff --git a/dtc-lexer.l b/dtc-lexer.l
index 081e13a..80a886a 100644
--- a/dtc-lexer.l
+++ b/dtc-lexer.l
@@ -96,6 +96,12 @@ static int pop_input_file(void);
 			return DT_MEMRESERVE;
 		}
 
+<*>"/remove-node/"	{
+			DPRINT("Keyword: /remove-node/\n");
+			BEGIN_DEFAULT();
+			return DT_REMOVENODE;
+		}
+
 <*>{LABEL}:	{
 			DPRINT("Label: %s\n", yytext);
 			yylval.labelref = xstrdup(yytext);
diff --git a/dtc-parser.y b/dtc-parser.y
index b58ba8e..1ba0478 100644
--- a/dtc-parser.y
+++ b/dtc-parser.y
@@ -55,6 +55,7 @@ static unsigned long long eval_literal(const char *s, int base, int bits);
 
 %token DT_V1
 %token DT_MEMRESERVE
+%token DT_REMOVENODE
 %token <propnodename> DT_PROPNODENAME
 %token <literal> DT_LITERAL
 %token <cbase> DT_BASE
@@ -140,6 +141,16 @@ devicetree:
 				print_error("label, '%s' not found", $2);
 			$$ = $1;
 		}
+	| devicetree DT_REMOVENODE DT_REF ';'
+		{
+			struct node *target;
+
+			target = get_node_by_label($1, $3);
+			if (target)
+				remove_child(target->parent, target);
+			else
+				print_error("label, '%s' not found", $3);
+		}
 	;
 
 nodedef:
diff --git a/dtc.h b/dtc.h
index b36ac5d..a7f3667 100644
--- a/dtc.h
+++ b/dtc.h
@@ -178,6 +178,7 @@ struct node *merge_nodes(struct node *old_node, struct node *new_node);
 
 void add_property(struct node *node, struct property *prop);
 void add_child(struct node *parent, struct node *child);
+void remove_child(struct node *parent, struct node *child);
 
 const char *get_unitname(struct node *node);
 struct property *get_property(struct node *node, const char *propname);
diff --git a/livetree.c b/livetree.c
index 13c5f10..21a4c48 100644
--- a/livetree.c
+++ b/livetree.c
@@ -202,6 +202,24 @@ void add_child(struct node *parent, struct node *child)
 	*p = child;
 }
 
+void remove_child(struct node *parent, struct node *child)
+{
+	struct node **p;
+
+	/* Make sure we've got a consistent tree here */
+	assert(child->parent == parent);
+
+	p = &parent->children;
+	while (*p) {
+		if (*p == child) {
+			*p = (*p)->next_sibling;
+			break;
+		}
+		p = &((*p)->next_sibling);
+	}
+	child->parent = NULL;
+}
+
 struct reserve_info *build_reserve_entry(uint64_t address, uint64_t size)
 {
 	struct reserve_info *new = xmalloc(sizeof(*new));