device_tree: Add support for aliases

This patch adds support to lookup nodes via the "/aliases" mechanism in
device trees. This may be required for overlay support (don't quite
remember tbh) and is also just a generally useful feature. It was
adapted from depthcharge's http://crosreview.com/1249703 and
http://crosreview.com/1542702.

Change-Id: I1289ab2f02c4877a2d0111040384827e2b48a34a
Signed-off-by: Julius Werner <jwerner@chromium.org>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/32866
Reviewed-by: Hung-Te Lin <hungte@chromium.org>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
This commit is contained in:
Julius Werner 2019-05-06 19:23:28 -07:00 committed by Patrick Georgi
parent fbec63d15f
commit 6d5695fac5
2 changed files with 77 additions and 12 deletions

View File

@ -146,6 +146,9 @@ struct device_tree_node *dt_find_node_by_phandle(struct device_tree_node *root,
// represented as a string of '/' separated node names.
struct device_tree_node *dt_find_node_by_path(struct device_tree *tree,
const char *path, u32 *addrcp, u32 *sizecp, int create);
// Look up a node through an alias.
struct device_tree_node *dt_find_node_by_alias(struct device_tree *tree,
const char *alias);
// Look up a node relative to a parent node, through its compatible string.
struct device_tree_node *dt_find_compat(struct device_tree_node *parent, const char *compatible);
// Look up the next child of a parent node, through its compatible string. It

View File

@ -564,27 +564,65 @@ struct device_tree_node *dt_find_node(struct device_tree_node *parent,
* @param create 1: Create node(s) if not found. 0: Return NULL instead.
* @return The found/created node, or NULL.
*
* It is the caller responsibility to provide the correct path string, namely
* starting with a '/', not ending in a '/' and not having "//" anywhere in it.
*/
* It is the caller responsibility to provide a path string that doesn't end
* with a '/' and doesn't contain any "//". If the path does not start with a
* '/', the first segment is interpreted as an alias. */
struct device_tree_node *dt_find_node_by_path(struct device_tree *tree,
const char *path, u32 *addrcp,
u32 *sizecp, int create)
{
char *dup_path = strdup(&path[1]); /* remove leading '/' */
char *sub_path;
char *duped_str;
struct device_tree_node *parent;
char *next_slash;
/* Hopefully enough depth for any node. */
const char *path_array[15];
int i;
char *next_slash;
struct device_tree_node *node = NULL;
if (!dup_path)
return NULL;
if (path[0] == '/') { // regular path
if (path[1] == '\0') { // special case: "/" is root node
dt_read_cell_props(tree->root, addrcp, sizecp);
return tree->root;
}
next_slash = dup_path;
path_array[0] = dup_path;
sub_path = duped_str = strdup(&path[1]);
if (!sub_path)
return NULL;
parent = tree->root;
} else { // alias
char *alias;
alias = duped_str = strdup(path);
if (!alias)
return NULL;
sub_path = strchr(alias, '/');
if (sub_path)
*sub_path = '\0';
parent = dt_find_node_by_alias(tree, alias);
if (!parent) {
printk(BIOS_DEBUG,
"Could not find node '%s', alias '%s' does not exist\n",
path, alias);
free(duped_str);
return NULL;
}
if (!sub_path) {
// it's just the alias, no sub-path
free(duped_str);
return parent;
}
sub_path++;
}
next_slash = sub_path;
path_array[0] = sub_path;
for (i = 1; i < (ARRAY_SIZE(path_array) - 1); i++) {
next_slash = strchr(next_slash, '/');
if (!next_slash)
break;
@ -595,14 +633,38 @@ struct device_tree_node *dt_find_node_by_path(struct device_tree *tree,
if (!next_slash) {
path_array[i] = NULL;
node = dt_find_node(tree->root, path_array,
node = dt_find_node(parent, path_array,
addrcp, sizecp, create);
}
free(dup_path);
free(duped_str);
return node;
}
/*
* Find a node from an alias
*
* @param tree The device tree.
* @param alias The alias name.
* @return The found node, or NULL.
*/
struct device_tree_node *dt_find_node_by_alias(struct device_tree *tree,
const char *alias)
{
struct device_tree_node *node;
const char *alias_path;
node = dt_find_node_by_path(tree, "/aliases", NULL, NULL, 0);
if (!node)
return NULL;
alias_path = dt_find_string_prop(node, alias);
if (!alias_path)
return NULL;
return dt_find_node_by_path(tree, alias_path, NULL, NULL, 0);
}
struct device_tree_node *dt_find_node_by_phandle(struct device_tree_node *root,
uint32_t phandle)
{