sunxi: Pass serial number through ATAG

Signed-off-by: Paul Kocialkowski <contact@paulk.fr>
Acked-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
diff --git a/board/sunxi/board.c b/board/sunxi/board.c
index d9f7691..4c51468 100644
--- a/board/sunxi/board.c
+++ b/board/sunxi/board.c
@@ -480,6 +480,26 @@
 }
 #endif
 
+#ifdef CONFIG_SERIAL_TAG
+void get_board_serial(struct tag_serialnr *serialnr)
+{
+	char *serial_string;
+	unsigned long long serial;
+
+	serial_string = getenv("serial#");
+
+	if (serial_string) {
+		serial = simple_strtoull(serial_string, NULL, 16);
+
+		serialnr->high = (unsigned int) (serial >> 32);
+		serialnr->low = (unsigned int) (serial & 0xffffffff);
+	} else {
+		serialnr->high = 0;
+		serialnr->low = 0;
+	}
+}
+#endif
+
 #ifdef CONFIG_MISC_INIT_R
 int misc_init_r(void)
 {