dm: core: Add a function to create an empty tree

Provide a function to create a new, empty tree.

Signed-off-by: Simon Glass <sjg@chromium.org>

5 files changed, 104 insertions, 4 deletions

diff --git a/drivers/core/ofnode.c b/drivers/core/ofnode.c
index 515396c62f4..d2bdb8b9af1 100644
--- a/drivers/core/ofnode.c
+++ b/drivers/core/ofnode.c
@@ -47,6 +47,17 @@ static int oftree_find(const void *fdt)
 	return -1;
 }
 
+static int check_tree_count(void)
+{
+	if (oftree_count == CONFIG_OFNODE_MULTI_TREE_MAX) {
+		log_warning("Too many registered device trees (max %d)\n",
+			    CONFIG_OFNODE_MULTI_TREE_MAX);
+		return -E2BIG;
+	}
+
+	return 0;
+}
+
 static oftree oftree_ensure(void *fdt)
 {
 	oftree tree;
@@ -69,11 +80,8 @@ static oftree oftree_ensure(void *fdt)
 	if (gd->flags & GD_FLG_RELOC) {
 		i = oftree_find(fdt);
 		if (i == -1) {
-			if (oftree_count == CONFIG_OFNODE_MULTI_TREE_MAX) {
-				log_warning("Too many registered device trees (max %d)\n",
-					    CONFIG_OFNODE_MULTI_TREE_MAX);
+			if (check_tree_count())
 				return oftree_null();
-			}
 
 			/* register the new tree */
 			i = oftree_count++;
@@ -92,6 +100,41 @@ static oftree oftree_ensure(void *fdt)
 	return tree;
 }
 
+int oftree_new(oftree *treep)
+{
+	oftree tree = oftree_null();
+	int ret;
+
+	if (of_live_active()) {
+		struct device_node *root;
+
+		ret = of_live_create_empty(&root);
+		if (ret)
+			return log_msg_ret("liv", ret);
+		tree = oftree_from_np(root);
+	} else {
+		const int size = 1024;
+		void *fdt;
+
+		ret = check_tree_count();
+		if (ret)
+			return log_msg_ret("fla", ret);
+
+		/* register the new tree with a small size */
+		fdt = malloc(size);
+		if (!fdt)
+			return log_msg_ret("fla", -ENOMEM);
+		ret = fdt_create_empty_tree(fdt, size);
+		if (ret)
+			return log_msg_ret("fla", -EINVAL);
+		oftree_list[oftree_count++] = fdt;
+		tree.fdt = fdt;
+	}
+	*treep = tree;
+
+	return 0;
+}
+
 void oftree_dispose(oftree tree)
 {
 	if (of_live_active())
@@ -193,6 +236,11 @@ static inline int oftree_find(const void *fdt)
 	return 0;
 }
 
+int oftree_new(oftree *treep)
+{
+	return -ENOSYS;
+}
+
 #endif /* OFNODE_MULTI_TREE */
 
 /**
diff --git a/include/dm/ofnode.h b/include/dm/ofnode.h
index 32917f66155..0b96ab34ede 100644
--- a/include/dm/ofnode.h
+++ b/include/dm/ofnode.h
@@ -128,6 +128,15 @@ static inline ofnode noffset_to_ofnode(ofnode other_node, int of_offset)
 #endif /* OFNODE_MULTI_TREE */
 
 /**
+ * oftree_new() - Create a new, empty tree
+ *
+ * @treep: Returns a pointer to the tree, on success
+ * Returns: 0 on success, -ENOMEM if out of memory, -E2BIG if !OF_LIVE and
+ * there are too many (flattrees) already
+ */
+int oftree_new(oftree *treep);
+
+/**
  * ofnode_to_np() - convert an ofnode to a live DT node pointer
  *
  * This cannot be called if the reference contains an offset.
diff --git a/include/of_live.h b/include/of_live.h
index 05e86ac06b1..81cb9bd13e2 100644
--- a/include/of_live.h
+++ b/include/of_live.h
@@ -46,4 +46,12 @@ int unflatten_device_tree(const void *blob, struct device_node **mynodes);
  */
 void of_live_free(struct device_node *root);
 
+/**
+ * of_live_create_empty() - Create a new, empty tree
+ *
+ * @rootp: Returns the root node of the created tree
+ * Return: 0 if OK, -ENOMEM if out of memory
+ */
+int of_live_create_empty(struct device_node **rootp);
+
 #endif
diff --git a/lib/of_live.c b/lib/of_live.c
index 25f7af61061..e4eee385547 100644
--- a/lib/of_live.c
+++ b/lib/of_live.c
@@ -336,3 +336,22 @@ void of_live_free(struct device_node *root)
 	/* the tree is stored as a contiguous block of memory */
 	free(root);
 }
+
+int of_live_create_empty(struct device_node **rootp)
+{
+	struct device_node *root;
+
+	root = calloc(1, sizeof(struct device_node));
+	if (!root)
+		return -ENOMEM;
+	root->name = strdup("");
+	if (!root->name) {
+		free(root);
+		return -ENOMEM;
+	}
+	root->type = "<NULL>";
+	root->full_name = "";
+	*rootp = root;
+
+	return 0;
+}
diff --git a/test/dm/ofnode.c b/test/dm/ofnode.c
index 3bf97761d1e..594116e3c04 100644
--- a/test/dm/ofnode.c
+++ b/test/dm/ofnode.c
@@ -1346,3 +1346,19 @@ static int dm_test_livetree_ensure(struct unit_test_state *uts)
 	return 0;
 }
 DM_TEST(dm_test_livetree_ensure, UT_TESTF_SCAN_FDT);
+
+static int dm_test_oftree_new(struct unit_test_state *uts)
+{
+	ofnode node, subnode, check;
+	oftree tree;
+
+	ut_assertok(oftree_new(&tree));
+	node = oftree_root(tree);
+	ut_assert(ofnode_valid(node));
+	ut_assertok(ofnode_add_subnode(node, "edmund", &subnode));
+	check = ofnode_find_subnode(node, "edmund");
+	ut_asserteq(check.of_offset, subnode.of_offset);
+
+	return 0;
+}
+DM_TEST(dm_test_oftree_new, UT_TESTF_SCAN_FDT);