fdt: Add fdtdec_get_uint64 to decode a 64-bit value from a property

It decodes a 64-bit value from a property that is at least 8 bytes long.

Signed-off-by: Che-Liang Chiou <clchiou@chromium.org>

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

include/fdtdec.h

@@ -181,6 +181,21 @@ fdt_addr_t fdtdec_get_addr(const void *blob, int node,
 s32 fdtdec_get_int(const void *blob, int node, const char *prop_name,
 		s32 default_val);
 
+/**
+ * Look up a 64-bit integer property in a node and return it. The property
+ * must have at least 8 bytes of data (2 cells). The first two cells are
+ * concatenated to form a 8 bytes value, where the first cell is top half and
+ * the second cell is bottom half.
+ *
+ * @param blob	FDT blob
+ * @param node	node to examine
+ * @param prop_name	name of property to find
+ * @param default_val	default value to return if the property is not found
+ * @return integer value, if found, or default_val if not
+ */
+uint64_t fdtdec_get_uint64(const void *blob, int node, const char *prop_name,
+		uint64_t default_val);
+
 /**
  * Checks whether a node is enabled.
  * This looks for a 'status' property. If this exists, then returns 1 if

lib/fdtdec.c

@@ -111,6 +111,19 @@ s32 fdtdec_get_int(const void *blob, int node, const char *prop_name,
 	return default_val;
 }
 
+uint64_t fdtdec_get_uint64(const void *blob, int node, const char *prop_name,
+		uint64_t default_val)
+{
+	const uint64_t *cell64;
+	int length;
+
+	cell64 = fdt_getprop(blob, node, prop_name, &length);
+	if (!cell64 || length < sizeof(*cell64))
+		return default_val;
+
+	return fdt64_to_cpu(*cell64);
+}
+
 int fdtdec_get_is_enabled(const void *blob, int node)
 {
 	const char *cell;