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path: root/drivers/of/fdt.c
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-rw-r--r--drivers/of/fdt.c76
1 files changed, 76 insertions, 0 deletions
diff --git a/drivers/of/fdt.c b/drivers/of/fdt.c
index 6bb7cf2de556..585b1a67cfbe 100644
--- a/drivers/of/fdt.c
+++ b/drivers/of/fdt.c
@@ -543,6 +543,82 @@ int __init of_flat_dt_match(unsigned long node, const char *const *compat)
return of_fdt_match(initial_boot_params, node, compat);
}
+struct fdt_scan_status {
+ const char *name;
+ int namelen;
+ int depth;
+ int found;
+ int (*iterator)(unsigned long node, const char *uname, int depth, void *data);
+ void *data;
+};
+
+/**
+ * fdt_scan_node_by_path - iterator for of_scan_flat_dt_by_path function
+ */
+static int __init fdt_scan_node_by_path(unsigned long node, const char *uname,
+ int depth, void *data)
+{
+ struct fdt_scan_status *st = data;
+
+ /*
+ * if scan at the requested fdt node has been completed,
+ * return -ENXIO to abort further scanning
+ */
+ if (depth <= st->depth)
+ return -ENXIO;
+
+ /* requested fdt node has been found, so call iterator function */
+ if (st->found)
+ return st->iterator(node, uname, depth, st->data);
+
+ /* check if scanning automata is entering next level of fdt nodes */
+ if (depth == st->depth + 1 &&
+ strncmp(st->name, uname, st->namelen) == 0 &&
+ uname[st->namelen] == 0) {
+ st->depth += 1;
+ if (st->name[st->namelen] == 0) {
+ st->found = 1;
+ } else {
+ const char *next = st->name + st->namelen + 1;
+ st->name = next;
+ st->namelen = strcspn(next, "/");
+ }
+ return 0;
+ }
+
+ /* scan next fdt node */
+ return 0;
+}
+
+/**
+ * of_scan_flat_dt_by_path - scan flattened tree blob and call callback on each
+ * child of the given path.
+ * @path: path to start searching for children
+ * @it: callback function
+ * @data: context data pointer
+ *
+ * This function is used to scan the flattened device-tree starting from the
+ * node given by path. It is used to extract information (like reserved
+ * memory), which is required on ealy boot before we can unflatten the tree.
+ */
+int __init of_scan_flat_dt_by_path(const char *path,
+ int (*it)(unsigned long node, const char *name, int depth, void *data),
+ void *data)
+{
+ struct fdt_scan_status st = {path, 0, -1, 0, it, data};
+ int ret = 0;
+
+ if (initial_boot_params)
+ ret = of_scan_flat_dt(fdt_scan_node_by_path, &st);
+
+ if (!st.found)
+ return -ENOENT;
+ else if (ret == -ENXIO) /* scan has been completed */
+ return 0;
+ else
+ return ret;
+}
+
#ifdef CONFIG_BLK_DEV_INITRD
/**
* early_init_dt_check_for_initrd - Decode initrd location from flat tree