From a8f2ac2ae6f15b675a55bcf3a20181f3bb223562 Mon Sep 17 00:00:00 2001
From: Simon Glass <sjg@chromium.org>
Date: Thu, 1 Jun 2023 10:22:42 -0600
Subject: [PATCH] fdt: Allow more general use of livetree

At present livetree can only be used for the control FDT. It is useful
to be able to use the ofnode API for other FDTs, e.g. those used by
the upcoming configuration editor.

We already have most of the support present, and tests can be marked with
the UT_TESTF_OTHER_FDT flag to use another FDT as a special case. But
with this change, the functionality becomes more generally available.

Plumb in the require support.

Signed-off-by: Simon Glass <sjg@chromium.org>
---
 drivers/core/ofnode.c | 26 +++++++++++++++++++++-----
 include/dm/ofnode.h   | 10 ++++++++++
 include/of_live.h     | 10 ++++++++++
 lib/of_live.c         |  6 ++++++
 test/dm/ofnode.c      | 19 +++++++++++++++++++
 5 files changed, 66 insertions(+), 5 deletions(-)

diff --git a/drivers/core/ofnode.c b/drivers/core/ofnode.c
index dee890b552..8df16e56af 100644
--- a/drivers/core/ofnode.c
+++ b/drivers/core/ofnode.c
@@ -12,6 +12,7 @@
 #include <fdt_support.h>
 #include <log.h>
 #include <malloc.h>
+#include <of_live.h>
 #include <linux/libfdt.h>
 #include <dm/of_access.h>
 #include <dm/of_addr.h>
@@ -51,6 +52,20 @@ static oftree oftree_ensure(void *fdt)
 	oftree tree;
 	int i;
 
+	if (of_live_active()) {
+		struct device_node *root;
+		int ret;
+
+		ret = unflatten_device_tree(fdt, &root);
+		if (ret) {
+			log_err("Failed to create live tree: err=%d\n", ret);
+			return oftree_null();
+		}
+		tree = oftree_from_np(root);
+
+		return tree;
+	}
+
 	if (gd->flags & GD_FLG_RELOC) {
 		i = oftree_find(fdt);
 		if (i == -1) {
@@ -60,11 +75,6 @@ static oftree oftree_ensure(void *fdt)
 				return oftree_null();
 			}
 
-			if (of_live_active()) {
-				log_err("Cannot register a flattree when OF_LIVE is active\n");
-				return oftree_null();
-			}
-
 			/* register the new tree */
 			i = oftree_count++;
 			oftree_list[i] = fdt;
@@ -82,6 +92,12 @@ static oftree oftree_ensure(void *fdt)
 	return tree;
 }
 
+void oftree_dispose(oftree tree)
+{
+	if (of_live_active())
+		of_live_free(tree.np);
+}
+
 void *ofnode_lookup_fdt(ofnode node)
 {
 	if (gd->flags & GD_FLG_RELOC) {
diff --git a/include/dm/ofnode.h b/include/dm/ofnode.h
index 443db6252d..0f38b3e736 100644
--- a/include/dm/ofnode.h
+++ b/include/dm/ofnode.h
@@ -352,6 +352,16 @@ static inline oftree oftree_from_np(struct device_node *root)
 	return tree;
 }
 
+/**
+ * oftree_dispose() - Dispose of an oftree
+ *
+ * This can be used to dispose of a tree that has been created (other than
+ * the control FDT which must not be disposed)
+ *
+ * @tree: Tree to dispose
+ */
+void oftree_dispose(oftree tree);
+
 /**
  * ofnode_name_eq() - Check if the node name is equivalent to a given name
  *                    ignoring the unit address
diff --git a/include/of_live.h b/include/of_live.h
index f59d6af335..05e86ac06b 100644
--- a/include/of_live.h
+++ b/include/of_live.h
@@ -36,4 +36,14 @@ int of_live_build(const void *fdt_blob, struct device_node **rootp);
  */
 int unflatten_device_tree(const void *blob, struct device_node **mynodes);
 
+/**
+ * of_live_free() - Dispose of a livetree
+ *
+ * This frees memory used by the tree, after which @root becomes invalid and
+ * cannot be used
+ *
+ * @root: Tree to dispose
+ */
+void of_live_free(struct device_node *root);
+
 #endif
diff --git a/lib/of_live.c b/lib/of_live.c
index 05588d5ed2..25f7af6106 100644
--- a/lib/of_live.c
+++ b/lib/of_live.c
@@ -330,3 +330,9 @@ int of_live_build(const void *fdt_blob, struct device_node **rootp)
 
 	return ret;
 }
+
+void of_live_free(struct device_node *root)
+{
+	/* the tree is stored as a contiguous block of memory */
+	free(root);
+}
diff --git a/test/dm/ofnode.c b/test/dm/ofnode.c
index 64baaf68db..6fbebc7da0 100644
--- a/test/dm/ofnode.c
+++ b/test/dm/ofnode.c
@@ -1266,3 +1266,22 @@ static int dm_test_livetree_align(struct unit_test_state *uts)
 	return 0;
 }
 DM_TEST(dm_test_livetree_align, UT_TESTF_LIVE_TREE);
+
+/* check that it is possible to load an arbitrary livetree */
+static int dm_test_livetree_ensure(struct unit_test_state *uts)
+{
+	oftree tree;
+	ofnode node;
+
+	/* read from other.dtb */
+	ut_assertok(test_load_other_fdt(uts));
+	tree = oftree_from_fdt(uts->other_fdt);
+	ut_assert(oftree_valid(tree));
+	node = oftree_path(tree, "/node/subnode");
+	ut_assert(ofnode_valid(node));
+	ut_asserteq_str("sandbox-other2",
+			ofnode_read_string(node, "compatible"));
+
+	return 0;
+}
+DM_TEST(dm_test_livetree_ensure, 0);
-- 
2.39.5