dm: core: Add a way to look up a phandle in an oftree

When we have multiple trees, the ofnode logic needs to be told which one
to use. Create a new function which takes an oftree argument, along with
a helper to obtain the FDT pointer from an oftree.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/drivers/core/ofnode.c b/drivers/core/ofnode.c
index 48d4dec..012cb8c 100644
--- a/drivers/core/ofnode.c
+++ b/drivers/core/ofnode.c
@@ -410,6 +410,20 @@
 	return node;
 }
 
+ofnode oftree_get_by_phandle(oftree tree, uint phandle)
+{
+	ofnode node;
+
+	if (of_live_active())
+		node = np_to_ofnode(of_find_node_by_phandle(tree.np, phandle));
+	else
+		node.of_offset =
+			fdt_node_offset_by_phandle(oftree_lookup_fdt(tree),
+						   phandle);
+
+	return node;
+}
+
 static fdt_addr_t __ofnode_get_addr_size_index(ofnode node, int index,
 					       fdt_size_t *size, bool translate)
 {
diff --git a/include/dm/ofnode.h b/include/dm/ofnode.h
index 328e1ed..fa72bb9 100644
--- a/include/dm/ofnode.h
+++ b/include/dm/ofnode.h
@@ -103,6 +103,22 @@
 }
 
 /**
+ * oftree_lookup_fdt() - obtain the FDT pointer from an oftree
+ *
+ * This can only be called when flat tree is enabled
+ *
+ * @tree: Tree to look at
+ * @return FDT pointer from the tree
+ */
+static inline void *oftree_lookup_fdt(oftree tree)
+{
+	if (of_live_active())
+		return NULL;
+	else
+		return tree.fdt;
+}
+
+/**
  * offset_to_ofnode() - convert a DT offset to an ofnode
  *
  * @of_offset: DT offset (either valid, or -1)
@@ -595,6 +611,15 @@
 ofnode ofnode_get_by_phandle(uint phandle);
 
 /**
+ * oftree_get_by_phandle() - get ofnode from phandle
+ *
+ * @tree:	tree to use
+ * @phandle:	phandle to look up
+ * Return: ofnode reference to the phandle
+ */
+ofnode oftree_get_by_phandle(oftree tree, uint phandle);
+
+/**
  * ofnode_read_size() - read the size of a property
  *
  * @node: node to check
diff --git a/test/dm/ofnode.c b/test/dm/ofnode.c
index f146b52..f6bb046 100644
--- a/test/dm/ofnode.c
+++ b/test/dm/ofnode.c
@@ -36,6 +36,8 @@
 	/* test unknown phandle */
 	ut_assert(!ofnode_valid(ofnode_get_by_phandle(0x1000000)));
 
+	ut_assert(ofnode_valid(oftree_get_by_phandle(oftree_default(), 1)));
+
 	return 0;
 }
 DM_TEST(dm_test_ofnode_get_by_phandle, UT_TESTF_SCAN_PDATA | UT_TESTF_SCAN_FDT);