[PATCH 1/2] 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.

Signed-off-by: John Bonesio <bones-s3s/WqlpOiPyB63q8FvJNQ@public.gmane.org>
---

I was originally going to submit just one patch, as the change in the
second one is pretty trivial. However, I thought people might appreciate
that the change to refer to nodes by path is highlighted separately.

Comment away!

- John

 dtc-lexer.l  |    6 ++++++
 dtc-parser.y |   14 ++++++++++++--
 dtc.h        |    3 +++
 livetree.c   |   25 +++++++++++++++++++++++++
 4 files changed, 46 insertions(+), 2 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 e1846d4..56d7789 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
@@ -137,10 +138,19 @@ devicetree:
 			if (target)
 				merge_nodes(target, $3);
 			else
-				print_error("label, '%s' does not exist in"
-					" node extension", $2);
+				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_nodes(target);
+			else
+				print_error("label, '%s' not found", $3);
+		}
 	;
 
 nodedef:
diff --git a/dtc.h b/dtc.h
index b36ac5d..e7cb45c 100644
--- a/dtc.h
+++ b/dtc.h
@@ -175,9 +175,12 @@ 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);
+void remove_nodes(struct node *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..924c060 100644
--- a/livetree.c
+++ b/livetree.c
@@ -167,6 +167,14 @@ struct node *merge_nodes(struct node *old_node, struct node *new_node)
 	return old_node;
 }
 
+void remove_nodes(struct node *node) {
+	/*
+	 * For now, just unlink the node from the tree structure.
+	 * This leaks memory, but at this point the developers are ok with this.
+	 */
+	remove_child(node->parent, node);
+}
+
 struct node *chain_node(struct node *first, struct node *list)
 {
 	assert(first->next_sibling == NULL);
@@ -202,6 +210,23 @@ 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;
+		}
+		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));