board_f: Add new function to allow runtime DTB selection

Runtime U-boot dtb selection is generally a two step process. First step
is to simply use an initial generic dtb. The second step is to select
the dtb and perhaps execute additional code ones U-boot knows what board
it is running on. Embedded_dtb_select handles the second step by allowing
board specific code to run and perform what ever necessary configuration
that is needed.

Signed-off-by: Franklin S Cooper Jr <fcooper@ti.com>
Reviewed-by: Tom Rini <trini@konsulko.com>
diff --git a/common/Kconfig b/common/Kconfig
index a5e3a6b..086b676 100644
--- a/common/Kconfig
+++ b/common/Kconfig
@@ -437,6 +437,15 @@
 
 endmenu
 
+config DTB_RESELECT
+	bool "Support swapping dtbs at a later point in boot"
+	depends on FIT_EMBED
+	help
+	  It is possible during initial boot you may need to use a generic
+	  dtb until you can fully determine the board your running on. This
+	  config allows boards to implement a function at a later point
+	  during boot to switch to the "correct" dtb.
+
 config FIT_EMBED
 	bool "Support a FIT image embedded in the U-boot image"
 	help
diff --git a/common/board_f.c b/common/board_f.c
index 2cdd12a..ffa84e3 100644
--- a/common/board_f.c
+++ b/common/board_f.c
@@ -809,6 +809,9 @@
 #if defined(CONFIG_DISPLAY_CPUINFO)
 	print_cpuinfo,		/* display cpu info (and speed) */
 #endif
+#if defined(CONFIG_DTB_RESELECT)
+	embedded_dtb_select,
+#endif
 #if defined(CONFIG_DISPLAY_BOARDINFO)
 	show_board_info,
 #endif
diff --git a/include/common.h b/include/common.h
index 1a98512..751665f 100644
--- a/include/common.h
+++ b/include/common.h
@@ -359,6 +359,10 @@
 void	pci_init      (void);
 void	pci_init_board(void);
 
+#if defined(CONFIG_DTB_RESELECT)
+int	embedded_dtb_select(void);
+#endif
+
 int	misc_init_f   (void);
 int	misc_init_r   (void);