device_tree: Add phandle caching and lookups

This patch caches phandles when unflattening the device tree, so we
don't have to look up the phandle property again every time we're trying
to find the phandle of a node. This is especially important when
supporting phandle lookups, which are also added. In addition we keep
track of the highest phandle in the whole tree, which will be important
for applying overlays later.

With this, dt_get_phandle(node) becomes obsolete because the phandle is
already available as a member variable in the node.

This patch was adapted from depthcharge's http://crosreview.com/1536385

Change-Id: I9cbd67d1d13e57c25d068b3db18bb75c709d7ebe
Signed-off-by: Julius Werner <jwerner@chromium.org>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/32863
Reviewed-by: Hung-Te Lin <hungte@chromium.org>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>

src/include/device_tree.h

@@ -47,6 +47,7 @@ struct fdt_header {
 #define FDT_TOKEN_END_NODE	2
 #define FDT_TOKEN_PROPERTY	3
 #define FDT_TOKEN_END		9
+#define FDT_PHANDLE_ILLEGAL	0xdeadbeef
 
 struct fdt_property
 {
@@ -71,6 +72,8 @@ struct device_tree_property
 struct device_tree_node
 {
 	const char *name;
+	uint32_t phandle;
+
 	// List of struct device_tree_property-s.
 	struct list_node properties;
 	// List of struct device_tree_nodes.
@@ -91,6 +94,7 @@ struct device_tree
 {
 	const void *header;
 	uint32_t header_size;
+	uint32_t max_phandle;
 
 	struct list_node reserve_map;
 
@@ -136,6 +140,8 @@ void dt_read_cell_props(const struct device_tree_node *node, u32 *addrcp,
 // represented as an array of strings.
 struct device_tree_node *dt_find_node(struct device_tree_node *parent, const char **path,
 			     u32 *addrcp, u32 *sizecp, int create);
+struct device_tree_node *dt_find_node_by_phandle(struct device_tree_node *root,
+						 uint32_t phandle);
 // Look up or create a node relative to a parent node, through its path
 // represented as a string of '/' separated node names.
 struct device_tree_node *dt_find_node_by_path(struct device_tree_node *parent, const char *path,
@@ -150,8 +156,6 @@ struct device_tree_node *dt_find_next_compat_child(struct device_tree_node *pare
 // Look up a node relative to a parent node, through its property value.
 struct device_tree_node *dt_find_prop_value(struct device_tree_node *parent, const char *name,
 				   void *data, size_t size);
-// Return the phandle
-uint32_t dt_get_phandle(const struct device_tree_node *node);
 // Write src into *dest as a 'length'-byte big-endian integer.
 void dt_write_int(u8 *dest, u64 src, size_t length);
 // Delete a property

src/lib/device_tree.c

@@ -66,6 +66,12 @@ int fdt_node_name(const void *blob, uint32_t offset, const char **name)
 	return ALIGN_UP(strlen((char *)ptr) + 1, sizeof(uint32_t)) + 4;
 }
 
+static int dt_prop_is_phandle(struct device_tree_property *prop)
+{
+	return !(strcmp("phandle", prop->prop.name) &&
+		 strcmp("linux,phandle", prop->prop.name));
+}
+
 
 
 /*
@@ -156,6 +162,7 @@ int fdt_skip_node(const void *blob, uint32_t start_offset)
  */
 
 static int fdt_unflatten_node(const void *blob, uint32_t start_offset,
+			      struct device_tree *tree,
 			      struct device_tree_node **new_node)
 {
 	struct list_node *last;
@@ -178,6 +185,12 @@ static int fdt_unflatten_node(const void *blob, uint32_t start_offset,
 		struct device_tree_property *prop = xzalloc(sizeof(*prop));
 		prop->prop = fprop;
 
+		if (dt_prop_is_phandle(prop)) {
+			node->phandle = be32dec(prop->prop.data);
+			if (node->phandle > tree->max_phandle)
+				tree->max_phandle = node->phandle;
+		}
+
 		list_insert_after(&prop->list_node, last);
 		last = &prop->list_node;
 
@@ -186,7 +199,7 @@ static int fdt_unflatten_node(const void *blob, uint32_t start_offset,
 
 	struct device_tree_node *child;
 	last = &node->children;
-	while ((size = fdt_unflatten_node(blob, offset, &child))) {
+	while ((size = fdt_unflatten_node(blob, offset, tree, &child))) {
 		list_insert_after(&child->list_node, last);
 		last = &child->list_node;
 
@@ -260,7 +273,7 @@ struct device_tree *fdt_unflatten(const void *blob)
 		offset += size;
 	}
 
-	fdt_unflatten_node(blob, struct_offset, &tree->root);
+	fdt_unflatten_node(blob, struct_offset, tree, &tree->root);
 
 	return tree;
 }
@@ -590,6 +603,26 @@ struct device_tree_node *dt_find_node_by_path(struct device_tree_node *parent,
 	return node;
 }
 
+struct device_tree_node *dt_find_node_by_phandle(struct device_tree_node *root,
+						 uint32_t phandle)
+{
+	if (!root)
+		return NULL;
+
+	if (root->phandle == phandle)
+		return root;
+
+	struct device_tree_node *node;
+	struct device_tree_node *result;
+	list_for_each(node, root->children, list_node) {
+		result = dt_find_node_by_phandle(node, phandle);
+		if (result)
+			return result;
+	}
+
+	return NULL;
+}
+
 /*
  * Check if given node is compatible.
  *
@@ -719,28 +752,6 @@ struct device_tree_node *dt_find_prop_value(struct device_tree_node *parent,
 	return NULL;
 }
 
-/**
- * Find the phandle of a node.
- *
- * @param node Pointer to node containing the phandle
- * @return Zero on error, the phandle on success
- */
-uint32_t dt_get_phandle(const struct device_tree_node *node)
-{
-	const uint32_t *phandle;
-	size_t len;
-
-	dt_find_bin_prop(node, "phandle", (const void **)&phandle, &len);
-	if (phandle != NULL && len == sizeof(*phandle))
-		return be32_to_cpu(*phandle);
-
-	dt_find_bin_prop(node, "linux,phandle", (const void **)&phandle, &len);
-	if (phandle != NULL && len == sizeof(*phandle))
-		return be32_to_cpu(*phandle);
-
-	return 0;
-}
-
 /*
  * Write an arbitrary sized big-endian integer into a pointer.
  *

src/soc/cavium/cn81xx/soc.c

@@ -234,7 +234,7 @@ static int dt_platform_fixup(struct device_tree_fixup *fixup,
 			continue;
 		}
 		/* Store the phandle */
-		phandle = dt_get_phandle(dt_node);
+		phandle = dt_node->phandle;
 		printk(BIOS_INFO, "%s: Removing node %s\n", __func__, path);
 		list_remove(&dt_node->list_node);