arm64: zynqmp: Add support for OF_SEPARATE with board DTB

OF_BOARD and OF_SEPARATE can use board specific board_fdt_blob_setup().

OF_BOARD option is mostly used for picking up DTB from certain location.

OF_SEPARATE option is used when DTB is appended after u-boot binary.

This board specific function is aligned with current version in
lib/fdtdec.c with checking CONFIG_XILINX_OF_BOARD_DTB_ADDR address first.

Signed-off-by: Michal Simek <michal.simek@xilinx.com>
diff --git a/board/xilinx/Kconfig b/board/xilinx/Kconfig
index 7833b11..73fc1be 100644
--- a/board/xilinx/Kconfig
+++ b/board/xilinx/Kconfig
@@ -44,7 +44,7 @@
 	hex
 	default 0x1000 if ARCH_VERSAL
 	default 0x100000 if ARCH_ZYNQ || ARCH_ZYNQMP
-	depends on OF_BOARD
+	depends on OF_BOARD || OF_SEPARATE
 	help
 	  Offset in the memory where the board configuration DTB is placed.
 
diff --git a/board/xilinx/common/board.c b/board/xilinx/common/board.c
index 62dafe0..ae5fe27 100644
--- a/board/xilinx/common/board.c
+++ b/board/xilinx/common/board.c
@@ -5,6 +5,7 @@
  */
 
 #include <common.h>
+#include <asm/sections.h>
 #include <dm/uclass.h>
 #include <i2c.h>
 
@@ -37,16 +38,32 @@
 	return ret;
 }
 
-#if defined(CONFIG_OF_BOARD)
+#if defined(CONFIG_OF_BOARD) || defined(CONFIG_OF_SEPARATE)
 void *board_fdt_blob_setup(void)
 {
 	static void *fdt_blob = (void *)CONFIG_XILINX_OF_BOARD_DTB_ADDR;
 
-	if (fdt_magic(fdt_blob) != FDT_MAGIC) {
-		printf("DTB is not passed via %p\n", fdt_blob);
-		return NULL;
-	}
+	if (fdt_magic(fdt_blob) == FDT_MAGIC)
+		return fdt_blob;
+
+	debug("DTB is not passed via %p\n", fdt_blob);
+
+#ifdef CONFIG_SPL_BUILD
+	/* FDT is at end of BSS unless it is in a different memory region */
+	if (IS_ENABLED(CONFIG_SPL_SEPARATE_BSS))
+		fdt_blob = (ulong *)&_image_binary_end;
+	else
+		fdt_blob = (ulong *)&__bss_end;
+#else
+	/* FDT is at end of image */
+	fdt_blob = (ulong *)&_end;
+#endif
+
+	if (fdt_magic(fdt_blob) == FDT_MAGIC)
+		return fdt_blob;
+
+	debug("DTB is also not passed via %p\n", fdt_blob);
 
-	return fdt_blob;
+	return NULL;
 }
 #endif