fdt: Add fdtdec_find_aliases() to deal with alias nodes

Stephen Warren pointed out that we should use nodes whether or not they
have an alias in the /aliases section. The aliases section specifies the
order so far as it can, but is not essential. Operating without alisses
is useful when the enumerated order of nodes does not matter (admittedly
rare in U-Boot).

This is considerably more complex, and it is important to keep this
complexity out of driver code. This patch creates a function
fdtdec_find_aliases() which returns an ordered list of node offsets
for a particular compatible ID, taking account of alias nodes.

Signed-off-by: Simon Glass <sjg@chromium.org>
Signed-off-by: Tom Warren <twarren@nvidia.com>

1 files changed, 116 insertions, 0 deletions

diff --git a/lib/fdtdec.c b/lib/fdtdec.c
index 0f87163..55d5bdf 100644
--- a/lib/fdtdec.c
+++ b/lib/fdtdec.c
@@ -35,6 +35,13 @@ DECLARE_GLOBAL_DATA_PTR;
 static const char * const compat_names[COMPAT_COUNT] = {
 };
 
+const char *fdtdec_get_compatible(enum fdt_compat_id id)
+{
+	/* We allow reading of the 'unknown' ID for testing purposes */
+	assert(id >= 0 && id < COMPAT_COUNT);
+	return compat_names[id];
+}
+
 /**
  * Look in the FDT for an alias with the given name and return its node.
  *
@@ -132,6 +139,115 @@ int fdtdec_next_alias(const void *blob, const char *name,
 	return err ? -FDT_ERR_NOTFOUND : node;
 }
 
+/* TODO: Can we tighten this code up a little? */
+int fdtdec_find_aliases_for_id(const void *blob, const char *name,
+			enum fdt_compat_id id, int *node_list, int maxcount)
+{
+	int name_len = strlen(name);
+	int nodes[maxcount];
+	int num_found = 0;
+	int offset, node;
+	int alias_node;
+	int count;
+	int i, j;
+
+	/* find the alias node if present */
+	alias_node = fdt_path_offset(blob, "/aliases");
+
+	/*
+	 * start with nothing, and we can assume that the root node can't
+	 * match
+	 */
+	memset(nodes, '\0', sizeof(nodes));
+
+	/* First find all the compatible nodes */
+	for (node = count = 0; node >= 0 && count < maxcount;) {
+		node = fdtdec_next_compatible(blob, node, id);
+		if (node >= 0)
+			nodes[count++] = node;
+	}
+	if (node >= 0)
+		debug("%s: warning: maxcount exceeded with alias '%s'\n",
+		       __func__, name);
+
+	/* Now find all the aliases */
+	memset(node_list, '\0', sizeof(*node_list) * maxcount);
+
+	for (offset = fdt_first_property_offset(blob, alias_node);
+			offset > 0;
+			offset = fdt_next_property_offset(blob, offset)) {
+		const struct fdt_property *prop;
+		const char *path;
+		int number;
+		int found;
+
+		node = 0;
+		prop = fdt_get_property_by_offset(blob, offset, NULL);
+		path = fdt_string(blob, fdt32_to_cpu(prop->nameoff));
+		if (prop->len && 0 == strncmp(path, name, name_len))
+			node = fdt_path_offset(blob, prop->data);
+		if (node <= 0)
+			continue;
+
+		/* Get the alias number */
+		number = simple_strtoul(path + name_len, NULL, 10);
+		if (number < 0 || number >= maxcount) {
+			debug("%s: warning: alias '%s' is out of range\n",
+			       __func__, path);
+			continue;
+		}
+
+		/* Make sure the node we found is actually in our list! */
+		found = -1;
+		for (j = 0; j < count; j++)
+			if (nodes[j] == node) {
+				found = j;
+				break;
+			}
+
+		if (found == -1) {
+			debug("%s: warning: alias '%s' points to a node "
+				"'%s' that is missing or is not compatible "
+				" with '%s'\n", __func__, path,
+				fdt_get_name(blob, node, NULL),
+			       compat_names[id]);
+			continue;
+		}
+
+		/*
+		 * Add this node to our list in the right place, and mark
+		 * it as done.
+		 */
+		if (fdtdec_get_is_enabled(blob, node)) {
+			node_list[number] = node;
+			if (number >= num_found)
+				num_found = number + 1;
+		}
+		nodes[j] = 0;
+	}
+
+	/* Add any nodes not mentioned by an alias */
+	for (i = j = 0; i < maxcount; i++) {
+		if (!node_list[i]) {
+			for (; j < maxcount; j++)
+				if (nodes[j] &&
+					fdtdec_get_is_enabled(blob, nodes[j]))
+					break;
+
+			/* Have we run out of nodes to add? */
+			if (j == maxcount)
+				break;
+
+			assert(!node_list[i]);
+			node_list[i] = nodes[j++];
+			if (i >= num_found)
+				num_found = i + 1;
+		}
+	}
+
+	return num_found;
+}
+
 /*
  * This function is a little odd in that it accesses global data. At some
  * point if the architecture board.c files merge this will make more sense.