dm: core: Add the ofnode multi-tree implementation

Add the logic to redirect requests for the device tree through a function
which can look up the tree ID. This works by using the top bits of
ofnode.of_offset to encode a tree.

It is assumed that there will only be a few device trees used at runtime,
typically the control FDT (always tree ID 0) and possibly a separate FDT
to be passed the OS.

The maximum number of device trees supported at runtime is 8, with this
implementation. That would use bits 30:28 of the node-offset value,
meaning that the positive offset range is limited to bits 27:0, versus
30:1 with this feature disabled. That still allows a device tree of up
to 256MB, which should be enough for most FITs. Larger ones can be
supported by using external data with the FIT, or by enabling OF_LIVE.

Update the documentation a little and fix up the comment for
ofnode_valid().

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

1 files changed, 64 insertions, 47 deletions

diff --git a/include/dm/ofnode.h b/include/dm/ofnode.h
index ad179a65e9..3a514f71f6 100644
--- a/include/dm/ofnode.h
+++ b/include/dm/ofnode.h
@@ -27,13 +27,14 @@ struct ofnode_phandle_args {
 	uint32_t args[OF_MAX_PHANDLE_ARGS];
 };
 
+#if CONFIG_IS_ENABLED(OFNODE_MULTI_TREE)
 /**
  * oftree_reset() - reset the state of the oftree list
  *
  * Reset the oftree list so it can be started again. This should be called
  * once the control FDT is in place, but before the ofnode interface is used.
  */
-static inline void oftree_reset(void) {}
+void oftree_reset(void);
 
 /**
  * ofnode_to_fdt() - convert an ofnode to a flat DT pointer
@@ -43,26 +44,50 @@ static inline void oftree_reset(void) {}
  * @node: Reference containing offset (possibly invalid)
  * Return: DT offset (can be NULL)
  */
+__attribute_const__ void *ofnode_to_fdt(ofnode node);
+
+/**
+ * ofnode_to_offset() - convert an ofnode to a flat DT offset
+ *
+ * This cannot be called if the reference contains a node pointer.
+ *
+ * @node: Reference containing offset (possibly invalid)
+ * Return: DT offset (can be -1)
+ */
+__attribute_const__ int ofnode_to_offset(ofnode node);
+
+/**
+ * oftree_from_fdt() - Returns an oftree from a flat device tree pointer
+ *
+ * @fdt: Device tree to use
+ *
+ * Returns: reference to the given node
+ */
+oftree oftree_from_fdt(void *fdt);
+
+/**
+ * noffset_to_ofnode() - convert a DT offset to an ofnode
+ *
+ * @other_node: Node in the same tree to use as a reference
+ * @of_offset: DT offset (either valid, or -1)
+ * Return: reference to the associated DT offset
+ */
+ofnode noffset_to_ofnode(ofnode other_node, int of_offset);
+
+#else /* !OFNODE_MULTI_TREE */
+static inline void oftree_reset(void) {}
+
 static inline void *ofnode_to_fdt(ofnode node)
 {
 #ifdef OF_CHECKS
 	if (of_live_active())
 		return NULL;
 #endif
-
 	/* Use the control FDT by default */
 	return (void *)gd->fdt_blob;
 }
 
-/**
- * ofnode_to_offset() - convert an ofnode to a flat DT offset
- *
- * This cannot be called if the reference contains a node pointer.
- *
- * @node: Reference containing offset (possibly invalid)
- * Return: DT offset (can be -1)
- */
-static inline int ofnode_to_offset(ofnode node)
+static inline __attribute_const__ int ofnode_to_offset(ofnode node)
 {
 #ifdef OF_CHECKS
 	if (of_live_active())
@@ -71,6 +96,33 @@ static inline int ofnode_to_offset(ofnode node)
 	return node.of_offset;
 }
 
+static inline oftree oftree_from_fdt(void *fdt)
+{
+	oftree tree;
+
+	/* we cannot access other trees without OFNODE_MULTI_TREE */
+	if (fdt == gd->fdt_blob)
+		tree.fdt = fdt;
+	else
+		tree.fdt = NULL;
+
+	return tree;
+}
+
+static inline ofnode noffset_to_ofnode(ofnode other_node, int of_offset)
+{
+	ofnode node;
+
+	if (of_live_active())
+		node.np = NULL;
+	else
+		node.of_offset = of_offset;
+
+	return node;
+}
+
+#endif /* OFNODE_MULTI_TREE */
+
 /**
  * ofnode_to_np() - convert an ofnode to a live DT node pointer
  *
@@ -89,29 +141,10 @@ static inline struct device_node *ofnode_to_np(ofnode node)
 }
 
 /**
- * noffset_to_ofnode() - convert a DT offset to an ofnode
- *
- * @other_node: Node in the same tree to use as a reference
- * @of_offset: DT offset (either valid, or -1)
- * Return: reference to the associated DT offset
- */
-static inline ofnode noffset_to_ofnode(ofnode other_node, int of_offset)
-{
-	ofnode node;
-
-	if (of_live_active())
-		node.np = NULL;
-	else
-		node.of_offset = of_offset;
-
-	return node;
-}
-
-/**
  * ofnode_valid() - check if an ofnode is valid
  *
  * @node: Reference containing offset (possibly invalid)
- * Return: true if the reference contains a valid ofnode, false if it is NULL
+ * Return: true if the reference contains a valid ofnode, false if not
  */
 static inline bool ofnode_valid(ofnode node)
 {
@@ -317,22 +350,6 @@ static inline oftree oftree_from_np(struct device_node *root)
 }
 
 /**
- * oftree_from_fdt() - Returns an oftree from a flat device tree pointer
- *
- * @fdt: Device tree to use
- *
- * Returns: reference to the given node
- */
-static inline oftree oftree_from_fdt(void *fdt)
-{
-	oftree tree;
-
-	tree.fdt = fdt;
-
-	return tree;
-}
-
-/**
  * ofnode_name_eq() - Check if the node name is equivalent to a given name
  *                    ignoring the unit address
  *