dm: core: Introduce support for multiple trees

At present ofnode only works with a single device tree, for the most part.
This is the control FDT used by U-Boot.

When booting an OS we may obtain a different device tree and want to
modify it. Add some initial support for this into the ofnode API.

Note that we don't permit aliases in this other device tree, since the
of_access implementation maintains a list of aliases collected at
start-up. Also, we don't need aliases to do fixups in the other FDT. So
make sure that flat tree and live tree processing are consistent in this
area.

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

2 files changed, 21 insertions, 4 deletions

diff --git a/drivers/core/of_access.c b/drivers/core/of_access.c
index c20b19cb50f..0e5915a43e6 100644
--- a/drivers/core/of_access.c
+++ b/drivers/core/of_access.c
@@ -343,24 +343,30 @@ static struct device_node *__of_find_node_by_path(struct device_node *parent,
 #define for_each_property_of_node(dn, pp) \
 	for (pp = dn->properties; pp != NULL; pp = pp->next)
 
-struct device_node *of_find_node_opts_by_path(const char *path,
+struct device_node *of_find_node_opts_by_path(struct device_node *root,
+					      const char *path,
 					      const char **opts)
 {
 	struct device_node *np = NULL;
 	struct property *pp;
 	const char *separator = strchr(path, ':');
 
+	if (!root)
+		root = gd->of_root;
 	if (opts)
 		*opts = separator ? separator + 1 : NULL;
 
 	if (strcmp(path, "/") == 0)
-		return of_node_get(gd->of_root);
+		return of_node_get(root);
 
 	/* The path could begin with an alias */
 	if (*path != '/') {
 		int len;
 		const char *p = separator;
 
+		/* Only allow alias processing on the control FDT */
+		if (root != gd->of_root)
+			return NULL;
 		if (!p)
 			p = strchrnul(path, '/');
 		len = p - path;
@@ -383,7 +389,7 @@ struct device_node *of_find_node_opts_by_path(const char *path,
 
 	/* Step down the tree matching path components */
 	if (!np)
-		np = of_node_get(gd->of_root);
+		np = of_node_get(root);
 	while (np && *path == '/') {
 		struct device_node *tmp = np;
 
@@ -791,7 +797,7 @@ int of_alias_scan(void)
 
 		name = of_get_property(of_chosen, "stdout-path", NULL);
 		if (name)
-			of_stdout = of_find_node_opts_by_path(name,
+			of_stdout = of_find_node_opts_by_path(NULL, name,
 							&of_stdout_options);
 	}
 
diff --git a/drivers/core/ofnode.c b/drivers/core/ofnode.c
index a59832ebbfb..bd41ef503c2 100644
--- a/drivers/core/ofnode.c
+++ b/drivers/core/ofnode.c
@@ -552,6 +552,17 @@ ofnode ofnode_path(const char *path)
 		return offset_to_ofnode(fdt_path_offset(gd->fdt_blob, path));
 }
 
+ofnode ofnode_path_root(oftree tree, const char *path)
+{
+	if (of_live_active())
+		return np_to_ofnode(of_find_node_opts_by_path(tree.np, path,
+							      NULL));
+	else if (*path != '/' && tree.fdt != gd->fdt_blob)
+		return ofnode_null();  /* Aliases only on control FDT */
+	else
+		return offset_to_ofnode(fdt_path_offset(tree.fdt, path));
+}
+
 const void *ofnode_read_chosen_prop(const char *propname, int *sizep)
 {
 	ofnode chosen_node;