dm: fdt: Add a function to look up a chosen node

Within /chosen we may have a node which points to another node, similar
to how /aliases works. Add a helper function to do this lookup.

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

diff --git a/include/fdtdec.h b/include/fdtdec.h
index 856e6cf766dea73ac3de4e009391052a891fd9e8..4f5aafb516d71b29101516b92c875e86012d1c69 100644 (file)
--- a/include/fdtdec.h
+++ b/include/fdtdec.h
@@ -374,6 +374,18 @@ int fdtdec_get_alias_seq(const void *blob, const char *base, int node,
  */
 int fdtdec_get_alias_node(const void *blob, const char *name);
 
+/**
+ * Get the offset of the given chosen node
+ *
+ * This looks up a property in /chosen containing the path to another node,
+ * then finds the offset of that node.
+ *
+ * @param blob         Device tree blob (if NULL, then error is returned)
+ * @param name         Property name, e.g. "stdout-path"
+ * @return Node offset referred to by that chosen node, or -ve FDT_ERR_...
+ */
+int fdtdec_get_chosen_node(const void *blob, const char *name);
+
 /*
  * Get the name for a compatible ID
  *

diff --git a/lib/fdtdec.c b/lib/fdtdec.c
index eb5aa20526fd509618311fdb3b4aab3c6379d46d..2b08be2405055863f4a1ace791eccbd32e125cb4 100644 (file)
--- a/lib/fdtdec.c
+++ b/lib/fdtdec.c
@@ -380,6 +380,21 @@ int fdtdec_get_alias_node(const void *blob, const char *name)
        return fdt_path_offset(blob, prop);
 }
 
+int fdtdec_get_chosen_node(const void *blob, const char *name)
+{
+       const char *prop;
+       int chosen_node;
+       int len;
+
+       if (!blob)
+               return -FDT_ERR_NOTFOUND;
+       chosen_node = fdt_path_offset(blob, "/chosen");
+       prop = fdt_getprop(blob, chosen_node, name, &len);
+       if (!prop)
+               return -FDT_ERR_NOTFOUND;
+       return fdt_path_offset(blob, prop);
+}
+
 int fdtdec_check_fdt(void)
 {
        /*