dm: core: Guard against including dm.h in header files

Header files generally should not include header files just for a struct,
since forward declarations work just as well and reduce overhead.

Add a warning for dm.h being included, since this has crept into U-Boot.

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

diff --git a/include/dm.h b/include/dm.h
index 2e1afda..a1b8416 100644 (file)
--- a/include/dm.h
+++ b/include/dm.h
@@ -3,6 +3,10 @@
  * Copyright (c) 2013 Google, Inc
  */
 
+#ifdef _DM_H_
+#warning "Suspect dm.h is included from a header file - please fix"
+#endif
+
 #ifndef _DM_H_
 #define _DM_H_