dm: Support driver model prior to relocation

Initialise devices marked 'pre-reloc' and make them available prior to
relocation. Note that this requires pre-reloc malloc() to be available.

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

include/dm/root.h

@@ -44,6 +44,19 @@ int dm_scan_platdata(bool pre_reloc_only);
  */
 int dm_scan_fdt(const void *blob, bool pre_reloc_only);
 
+/**
+ * dm_init_and_scan() - Initialise Driver Model structures and scan for devices
+ *
+ * This function initialises the roots of the driver tree and uclass trees,
+ * then scans and binds available devices from platform data and the FDT.
+ * This calls dm_init() to set up Driver Model structures.
+ *
+ * @pre_reloc_only: If true, bind only drivers with the DM_FLAG_PRE_RELOC
+ * flag. If false bind all drivers.
+ * @return 0 if OK, -ve on error
+ */
+int dm_init_and_scan(bool pre_reloc_only);
+
 /**
  * dm_init() - Initialise Driver Model structures
  *