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

[John Bonesio <bones-s3s/WqlpOiPyB63q8FvJNQ@public.gmane.org>]

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.

This patch does not yet provide a way to remove properties.

- John
---

 dtc-lexer.l  |   12 ++++++++++
 dtc-parser.y |   24 ++++++++++++++++++++
 dtc.h        |    2 ++
 livetree.c   |   69 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 4 files changed, 107 insertions(+), 0 deletions(-)

diff --git a/dtc-lexer.l b/dtc-lexer.l
index 081e13a..a24edf5 100644
--- a/dtc-lexer.l
+++ b/dtc-lexer.l
@@ -96,6 +96,18 @@ static int pop_input_file(void);
 			return DT_MEMRESERVE;
 		}
 
+<*>"/trim-node/"	{
+			DPRINT("Keyword: /trim-node/\n");
+			BEGIN_DEFAULT();
+			return DT_REPLACENODE;
+		}
+
+<*>"/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 aa250f1..a9cde72 100644
--- a/dtc-parser.y
+++ b/dtc-parser.y
@@ -54,6 +54,8 @@ static unsigned long long eval_literal(const char *s, int base, int bits);
 
 %token DT_V1
 %token DT_MEMRESERVE
+%token DT_REPLACENODE
+%token DT_REMOVENODE
 %token <propnodename> DT_PROPNODENAME
 %token <literal> DT_LITERAL
 %token <cbase> DT_BASE
@@ -140,6 +142,28 @@ devicetree:
 					" node extension", $2);
 			$$ = $1;
 		}
+	| devicetree DT_REPLACENODE DT_REF nodedef
+		{
+			struct node *target;
+
+			target = get_node_by_label($1, $3);
+			if (target)
+				replace_nodes(target, $4);
+			else
+				yyerror("label, '%s' does not exist in"
+					" node redefinition", $3);
+			$$ = $1;
+		}
+	| devicetree DT_REMOVENODE DT_REF ';'
+		{
+			struct node *target;
+
+			target = get_node_by_label($1, $3);
+			if (target)
+				remove_nodes(target);
+			else
+				yyerror("label, '%s' does not exist in"
+					" node removal", $3);
 	;
 
 nodedef:
diff --git a/dtc.h b/dtc.h
index b36ac5d..1340568 100644
--- a/dtc.h
+++ b/dtc.h
@@ -175,6 +175,8 @@ struct node *build_node(struct property *proplist, struct node *children);
 struct node *name_node(struct node *node, char *name);
 struct node *chain_node(struct node *first, struct node *list);
 struct node *merge_nodes(struct node *old_node, struct node *new_node);
+struct node *replace_nodes(struct node *old_node, struct node *new_node);
+struct node *remove_nodes(struct node *node);
 
 void add_property(struct node *node, struct property *prop);
 void add_child(struct node *parent, struct node *child);
diff --git a/livetree.c b/livetree.c
index 13c5f10..5e32510 100644
--- a/livetree.c
+++ b/livetree.c
@@ -167,6 +167,75 @@ struct node *merge_nodes(struct node *old_node, struct node *new_node)
 	return old_node;
 }
 
+struct node *remove_nodes(struct node *node) {
+	struct property *prop;
+	struct node *child, *parent;
+
+	while (node->proplist) {
+		/* Pop the property off the list */
+		prop = node->proplist;
+		node->proplist = prop->next;
+		prop->next = NULL;
+
+		free(prop);
+	}
+
+	/* Free up the node's children */
+	/* This assumes we have a tree and not a cylic or acylic graph */
+	while (node->children) {
+		/* Pop the child node off the list */
+		child = node->children;
+		node->children = child->next_sibling;
+		child->parent = NULL;
+		child->next_sibling = NULL;
+
+		child = remove_nodes(child);
+	}
+
+	/* Remove the node from it's parent's child list */
+	if (node->parent) {
+		int found = 0;
+
+		parent = node->parent;
+
+		/* if the node is the first child ... */
+		if (parent->children == node) {
+			parent->children = node->next_sibling;
+			found = 1;
+		} else {
+			for_each_child(parent, child) {
+				if (child->next_sibling == node) {
+					child->next_sibling = node->next_sibling;
+					found = 1;
+					break;
+				}
+			}
+		}
+		assert(found); /* Woah! We've got an inconsistent tree here */
+		node->parent = NULL;
+		node->next_sibling = NULL;
+	}
+
+	free(node);
+
+	return NULL;
+}
+
+struct node *replace_nodes(struct node *old_node, struct node *new_node)
+{
+	struct label *l;
+
+	/* Add old node labels to new node, so we can still refer to the
+	 * new node by the old labels.  */
+	for_each_label(old_node->labels, l)
+		add_label(&new_node->labels, l->label);
+
+	/* Free up the old_node */
+	remove_nodes(old_node);
+
+	return new_node;
+}
+
 struct node *chain_node(struct node *first, struct node *list)
 {
 	assert(first->next_sibling == NULL);