fdt: Swap the signature for board_fdt_blob_setup()

This returns a devicetree and updates a parameter with an error code.
Swap it, since this fits better with the way U-Boot normally works. It
also (more easily) allows leaving the existing pointer unchanged.

No yaks were harmed in this change, but there is a very small code-size
reduction.

For sifive, the OF_BOARD option must be set for the function to be
called, so there is no point in checking it again. Also OF_SEPARATE is
defined always.

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Matthias Brugger <mbrugger@suse.com>
Reviewed-by: Patrice Chotard <patrice.chotard@foss.st.com>
[trini: Update total_compute]
Signed-off-by: Tom Rini <trini@konsulko.com>
diff --git a/arch/arm/mach-apple/board.c b/arch/arm/mach-apple/board.c
index 0b6d290..2644a04 100644
--- a/arch/arm/mach-apple/board.c
+++ b/arch/arm/mach-apple/board.c
@@ -691,11 +691,12 @@
 
 extern long fw_dtb_pointer;
 
-void *board_fdt_blob_setup(int *err)
+int board_fdt_blob_setup(void **fdtp)
 {
 	/* Return DTB pointer passed by m1n1 */
-	*err = 0;
-	return (void *)fw_dtb_pointer;
+	*fdtp = (void *)fw_dtb_pointer;
+
+	return 0;
 }
 
 void build_mem_map(void)
diff --git a/arch/arm/mach-snapdragon/board.c b/arch/arm/mach-snapdragon/board.c
index 75a880f..f1319df 100644
--- a/arch/arm/mach-snapdragon/board.c
+++ b/arch/arm/mach-snapdragon/board.c
@@ -150,12 +150,12 @@
  * or for supporting quirky devices where it's easier to leave the downstream DT in place
  * to improve ABL compatibility. Otherwise, we use the DT provided by ABL.
  */
-void *board_fdt_blob_setup(int *err)
+int board_fdt_blob_setup(void **fdtp)
 {
 	struct fdt_header *fdt;
 	bool internal_valid, external_valid;
+	int ret = 0;
 
-	*err = 0;
 	fdt = (struct fdt_header *)get_prev_bl_fdt_addr();
 	external_valid = fdt && !fdt_check_header(fdt);
 	internal_valid = !fdt_check_header(gd->fdt_blob);
@@ -170,10 +170,11 @@
 
 	if (internal_valid) {
 		debug("Using built in FDT\n");
+		ret = -EEXIST;
 	} else {
 		debug("Using external FDT\n");
 		/* So we can use it before returning */
-		gd->fdt_blob = fdt;
+		*fdtp = fdt;
 	}
 
 	/*
@@ -182,7 +183,7 @@
 	 */
 	qcom_parse_memory();
 
-	return (void *)gd->fdt_blob;
+	return ret;
 }
 
 void reset_cpu(void)
diff --git a/arch/arm/mach-stm32mp/boot_params.c b/arch/arm/mach-stm32mp/boot_params.c
index ebddf6a..2d058ed 100644
--- a/arch/arm/mach-stm32mp/boot_params.c
+++ b/arch/arm/mach-stm32mp/boot_params.c
@@ -6,6 +6,7 @@
 #define LOG_CATEGORY LOGC_ARCH
 
 #include <config.h>
+#include <errno.h>
 #include <log.h>
 #include <linux/libfdt.h>
 #include <asm/arch/sys_proto.h>
@@ -16,20 +17,22 @@
  * Use the saved FDT address provided by TF-A at boot time (NT_FW_CONFIG =
  * Non Trusted Firmware configuration file) when the pointer is valid
  */
-void *board_fdt_blob_setup(int *err)
+int board_fdt_blob_setup(void **fdtp)
 {
 	unsigned long nt_fw_dtb = get_stm32mp_bl2_dtb();
 
 	log_debug("%s: nt_fw_dtb=%lx\n", __func__, nt_fw_dtb);
 
-	*err = 0;
 	/* use external device tree only if address is valid */
-	if (nt_fw_dtb >= STM32_DDR_BASE) {
-		if (fdt_magic(nt_fw_dtb) == FDT_MAGIC)
-			return (void *)nt_fw_dtb;
-		log_debug("%s: DTB not found.\n", __func__);
+	if (nt_fw_dtb < STM32_DDR_BASE ||
+	    fdt_magic(nt_fw_dtb) != FDT_MAGIC) {
+		log_debug("DTB not found.\n");
+		log_debug("fall back to builtin DTB, %p\n", _end);
+
+		return -EEXIST;
 	}
-	log_debug("%s: fall back to builtin DTB, %p\n", __func__, _end);
+
+	*fdtp = (void *)nt_fw_dtb;
 
-	return (void *)_end;
+	return 0;
 }
diff --git a/arch/sandbox/cpu/cpu.c b/arch/sandbox/cpu/cpu.c
index d1c4dcf..6407193 100644
--- a/arch/sandbox/cpu/cpu.c
+++ b/arch/sandbox/cpu/cpu.c
@@ -368,7 +368,7 @@
 	return 0;
 }
 
-void *board_fdt_blob_setup(int *ret)
+int board_fdt_blob_setup(void **fdtp)
 {
 	struct sandbox_state *state = state_get_current();
 	const char *fname = state->fdt_fname;
@@ -378,43 +378,41 @@
 	int fd;
 
 	if (gd->fdt_blob)
-		return (void *)gd->fdt_blob;
+		return -EEXIST;
 	blob = map_sysmem(CONFIG_SYS_FDT_LOAD_ADDR, 0);
-	*ret = 0;
 	if (!state->fdt_fname) {
 		err = setup_auto_tree(blob);
-		if (!err)
-			goto done;
-		os_printf("Unable to create empty FDT: %s\n", fdt_strerror(err));
-		*ret = -EINVAL;
-		goto fail;
+		if (err) {
+			os_printf("Unable to create empty FDT: %s\n",
+				  fdt_strerror(err));
+			return -EINVAL;
+		}
+		*fdtp = blob;
+
+		return 0;
 	}
 
 	err = os_get_filesize(fname, &size);
 	if (err < 0) {
 		os_printf("Failed to find FDT file '%s'\n", fname);
-		*ret = err;
-		goto fail;
+		return err;
 	}
 	fd = os_open(fname, OS_O_RDONLY);
 	if (fd < 0) {
 		os_printf("Failed to open FDT file '%s'\n", fname);
-		*ret = -EACCES;
-		goto fail;
+		return -EACCES;
 	}
 
 	if (os_read(fd, blob, size) != size) {
 		os_close(fd);
 		os_printf("Failed to read FDT file '%s'\n", fname);
-		*ret =  -EIO;
-		goto fail;
+		return -EIO;
 	}
 	os_close(fd);
 
-done:
-	return blob;
-fail:
-	return NULL;
+	*fdtp = blob;
+
+	return 0;
 }
 
 ulong timer_get_boot_us(void)
diff --git a/board/Marvell/octeontx/board-fdt.c b/board/Marvell/octeontx/board-fdt.c
index 6642b16..9d913b9 100644
--- a/board/Marvell/octeontx/board-fdt.c
+++ b/board/Marvell/octeontx/board-fdt.c
@@ -296,13 +296,9 @@
 	return 0;
 }
 
-/**
- * Return the FDT base address that was passed by ATF
- *
- * Return:	FDT base address received from ATF in x1 register
- */
-void *board_fdt_blob_setup(int *err)
+int board_fdt_blob_setup(void **fdtp)
 {
-	*err = 0;
-	return (void *)fdt_base_addr;
+	*fdtp = (void *)fdt_base_addr;
+
+	return 0;
 }
diff --git a/board/Marvell/octeontx2/board-fdt.c b/board/Marvell/octeontx2/board-fdt.c
index 04be9fb..e5a4db0 100644
--- a/board/Marvell/octeontx2/board-fdt.c
+++ b/board/Marvell/octeontx2/board-fdt.c
@@ -210,13 +210,9 @@
 	return 0;
 }
 
-/**
- * Return the FDT base address that was passed by ATF
- *
- * Return:	FDT base address received from ATF in x1 register
- */
-void *board_fdt_blob_setup(int *err)
+int board_fdt_blob_setup(void **fdtp)
 {
-	*err = 0;
-	return (void *)fdt_base_addr;
+	*fdtp = (void *)fdt_base_addr;
+
+	return 0;
 }
diff --git a/board/Marvell/octeontx2/board.c b/board/Marvell/octeontx2/board.c
index 974e9eb..01ba53c 100644
--- a/board/Marvell/octeontx2/board.c
+++ b/board/Marvell/octeontx2/board.c
@@ -234,7 +234,8 @@
 		return CMD_RET_USAGE;
 
 	addr = hextoul(argv[1], NULL);
-	fdt = board_fdt_blob_setup(&err);
+	fdt = (void *)gd->fdt_blob;
+	err = board_fdt_blob_setup(&fdt);
 	entry = (uboot_entry_t)addr;
 	flush_cache((ulong)addr, 1 << 20);	/* 1MiB should be enough */
 	dcache_disable();
diff --git a/board/andestech/ae350/ae350.c b/board/andestech/ae350/ae350.c
index 5ae5bae..1d9d4a9 100644
--- a/board/andestech/ae350/ae350.c
+++ b/board/andestech/ae350/ae350.c
@@ -79,21 +79,24 @@
 }
 
 #define ANDES_HW_DTB_ADDRESS	0xF2000000
-void *board_fdt_blob_setup(int *err)
+int board_fdt_blob_setup(void **fdtp)
 {
-	*err = 0;
-
 	if (IS_ENABLED(CONFIG_OF_SEPARATE) || IS_ENABLED(CONFIG_OF_BOARD)) {
-		if (fdt_magic((uintptr_t)gd->arch.firmware_fdt_addr) == FDT_MAGIC)
-			return (void *)(ulong)gd->arch.firmware_fdt_addr;
+		if (fdt_magic((uintptr_t)gd->arch.firmware_fdt_addr) ==
+			FDT_MAGIC) {
+			*fdtp = (void *)(ulong)gd->arch.firmware_fdt_addr;
+
+			return 0;
+		}
 	}
 
-	if (fdt_magic(CONFIG_SYS_FDT_BASE) == FDT_MAGIC)
-		return (void *)CONFIG_SYS_FDT_BASE;
-	return (void *)ANDES_HW_DTB_ADDRESS;
+	if (fdt_magic(CONFIG_SYS_FDT_BASE) == FDT_MAGIC) {
+		*fdtp = (void *)CONFIG_SYS_FDT_BASE;
+
+		return 0;
+	}
 
-	*err = -EINVAL;
-	return NULL;
+	return -EINVAL;
 }
 
 #ifdef CONFIG_SPL_BOARD_INIT
diff --git a/board/armltd/total_compute/total_compute.c b/board/armltd/total_compute/total_compute.c
index 1336d2e..75ba3c3 100644
--- a/board/armltd/total_compute/total_compute.c
+++ b/board/armltd/total_compute/total_compute.c
@@ -37,15 +37,13 @@
  */
 unsigned long __section(".data") fw_dtb_pointer;
 
-void *board_fdt_blob_setup(int *err)
+int board_fdt_blob_setup(void **fdtp)
 {
-	*err = 0;
-	if (fdt_magic(fw_dtb_pointer) != FDT_MAGIC) {
-		*err = -ENXIO;
-		return NULL;
-	}
+	if (fdt_magic(fw_dtb_pointer) != FDT_MAGIC)
+		return -ENXIO;
 
-	return (void *)fw_dtb_pointer;
+	*fdtp = (void *)fw_dtb_pointer;
+	return 0;
 }
 
 int misc_init_r(void)
diff --git a/board/armltd/vexpress64/vexpress64.c b/board/armltd/vexpress64/vexpress64.c
index 0119f54..b5ede58 100644
--- a/board/armltd/vexpress64/vexpress64.c
+++ b/board/armltd/vexpress64/vexpress64.c
@@ -168,42 +168,37 @@
 	return fdt_subnode_offset((void *)dtb_ptr, 0, "memory") >= 0;
 }
 
-void *board_fdt_blob_setup(int *err)
+int board_fdt_blob_setup(void **fdtp)
 {
 #ifdef CONFIG_TARGET_VEXPRESS64_JUNO
 	phys_addr_t fdt_rom_addr = find_dtb_in_nor_flash(CONFIG_JUNO_DTB_PART);
 
-	*err = 0;
-	if (fdt_rom_addr == ~0UL) {
-		*err = -ENXIO;
-		return NULL;
-	}
+	if (fdt_rom_addr == ~0UL)
+		return -ENXIO;
 
-	return (void *)fdt_rom_addr;
+	*fdtp = (void *)fdt_rom_addr;
+	return 0;
 #endif
 
 #ifdef VEXPRESS_FDT_ADDR
 	if (fdt_magic(VEXPRESS_FDT_ADDR) == FDT_MAGIC) {
-		*err = 0;
-		return (void *)VEXPRESS_FDT_ADDR;
+		*fdtp = (void *)VEXPRESS_FDT_ADDR;
+		return 0;
 	}
 #endif
 
 	if (is_valid_dtb(prior_stage_fdt_address[1])) {
-		*err = 0;
-		return (void *)prior_stage_fdt_address[1];
+		*fdtp = (void *)prior_stage_fdt_address[1];
+		return 0;
 	} else if (is_valid_dtb(prior_stage_fdt_address[0])) {
-		*err = 0;
-		return (void *)prior_stage_fdt_address[0];
+		*fdtp = (void *)prior_stage_fdt_address[0];
+		return 0;
 	}
 
-	if (fdt_magic(gd->fdt_blob) == FDT_MAGIC) {
-		*err = 0;
-		return (void *)gd->fdt_blob;
-	}
+	if (fdt_magic(*fdtp) == FDT_MAGIC)
+		return 0;
 
-	*err = -ENXIO;
-	return NULL;
+	return -ENXIO;
 }
 #endif
 
diff --git a/board/broadcom/bcmstb/bcmstb.c b/board/broadcom/bcmstb/bcmstb.c
index bc05aec..e655f61 100644
--- a/board/broadcom/bcmstb/bcmstb.c
+++ b/board/broadcom/bcmstb/bcmstb.c
@@ -130,9 +130,10 @@
 	return 0;
 }
 
-void *board_fdt_blob_setup(int *err)
+int board_fdt_blob_setup(void **fdtp)
 {
-	*err = 0;
 	/* Stored the DTB address there during our init */
-	return (void *)prior_stage_fdt_address;
+	*fdtp = (void *)prior_stage_fdt_address;
+
+	return 0;
 }
diff --git a/board/emulation/qemu-arm/qemu-arm.c b/board/emulation/qemu-arm/qemu-arm.c
index e0e18b4..31f5a77 100644
--- a/board/emulation/qemu-arm/qemu-arm.c
+++ b/board/emulation/qemu-arm/qemu-arm.c
@@ -149,11 +149,12 @@
 	return 0;
 }
 
-void *board_fdt_blob_setup(int *err)
+int board_fdt_blob_setup(void **fdtp)
 {
-	*err = 0;
 	/* QEMU loads a generated DTB for us at the start of RAM. */
-	return (void *)CFG_SYS_SDRAM_BASE;
+	*fdtp = (void *)CFG_SYS_SDRAM_BASE;
+
+	return 0;
 }
 
 void enable_caches(void)
diff --git a/board/emulation/qemu-ppce500/qemu-ppce500.c b/board/emulation/qemu-ppce500/qemu-ppce500.c
index 58e5d5e..40d295d 100644
--- a/board/emulation/qemu-ppce500/qemu-ppce500.c
+++ b/board/emulation/qemu-ppce500/qemu-ppce500.c
@@ -334,15 +334,11 @@
 	return (1 << cpu_numcores()) - 1;
 }
 
-/**
- * Return the virtual address of FDT that was passed by QEMU
- *
- * Return: virtual address of FDT received from QEMU in r3 register
- */
-void *board_fdt_blob_setup(int *err)
+int board_fdt_blob_setup(void **fdtp)
 {
-	*err = 0;
-	return get_fdt_virt();
+	*fdtp = get_fdt_virt();
+
+	return 0;
 }
 
 /* See CFG_SYS_NS16550_CLK in arch/powerpc/include/asm/config.h */
diff --git a/board/emulation/qemu-riscv/qemu-riscv.c b/board/emulation/qemu-riscv/qemu-riscv.c
index e5193e3..a90222e 100644
--- a/board/emulation/qemu-riscv/qemu-riscv.c
+++ b/board/emulation/qemu-riscv/qemu-riscv.c
@@ -64,9 +64,10 @@
 }
 #endif
 
-void *board_fdt_blob_setup(int *err)
+int board_fdt_blob_setup(void **fdtp)
 {
-	*err = 0;
 	/* Stored the DTB address there during our init */
-	return (void *)(ulong)gd->arch.firmware_fdt_addr;
+	*fdtp = (void *)(ulong)gd->arch.firmware_fdt_addr;
+
+	return 0;
 }
diff --git a/board/highbank/highbank.c b/board/highbank/highbank.c
index f3df83e..0ec8844 100644
--- a/board/highbank/highbank.c
+++ b/board/highbank/highbank.c
@@ -97,15 +97,16 @@
 }
 #endif
 
-void *board_fdt_blob_setup(int *err)
+int board_fdt_blob_setup(void **fdtp)
 {
-	*err = 0;
 	/*
 	 * The ECME management processor loads the DTB from NOR flash
 	 * into DRAM (at 4KB), where it gets patched to contain the
 	 * detected memory size.
 	 */
-	return (void *)0x1000;
+	*fdtp = (void *)0x1000;
+
+	return 0;
 }
 
 static int is_highbank(void)
diff --git a/board/raspberrypi/rpi/rpi.c b/board/raspberrypi/rpi/rpi.c
index 9122f33..c46fe4b 100644
--- a/board/raspberrypi/rpi/rpi.c
+++ b/board/raspberrypi/rpi/rpi.c
@@ -508,15 +508,14 @@
 /*
  * If the firmware passed a device tree use it for U-Boot.
  */
-void *board_fdt_blob_setup(int *err)
+int board_fdt_blob_setup(void **fdtp)
 {
-	*err = 0;
-	if (fdt_magic(fw_dtb_pointer) != FDT_MAGIC) {
-		*err = -ENXIO;
-		return NULL;
-	}
+	if (fdt_magic(fw_dtb_pointer) != FDT_MAGIC)
+		return -ENXIO;
+
+	*fdtp = (void *)fw_dtb_pointer;
 
-	return (void *)fw_dtb_pointer;
+	return 0;
 }
 
 int copy_property(void *dst, void *src, char *path, char *property)
diff --git a/board/sifive/unleashed/unleashed.c b/board/sifive/unleashed/unleashed.c
index 3c5dd50..c1c3746 100644
--- a/board/sifive/unleashed/unleashed.c
+++ b/board/sifive/unleashed/unleashed.c
@@ -114,15 +114,15 @@
 
 #endif
 
-void *board_fdt_blob_setup(int *err)
+int board_fdt_blob_setup(void **fdtp)
 {
-	*err = 0;
-	if (IS_ENABLED(CONFIG_OF_SEPARATE) || IS_ENABLED(CONFIG_OF_BOARD)) {
-		if (gd->arch.firmware_fdt_addr)
-			return (ulong *)(uintptr_t)gd->arch.firmware_fdt_addr;
+	if (gd->arch.firmware_fdt_addr) {
+		*fdtp = (ulong *)(uintptr_t)gd->arch.firmware_fdt_addr;
+
+		return 0;
 	}
 
-	return (ulong *)_end;
+	return -EEXIST;
 }
 
 int board_init(void)
diff --git a/board/sifive/unmatched/unmatched.c b/board/sifive/unmatched/unmatched.c
index c869627..23e03e1 100644
--- a/board/sifive/unmatched/unmatched.c
+++ b/board/sifive/unmatched/unmatched.c
@@ -10,15 +10,14 @@
 #include <dm.h>
 #include <asm/sections.h>
 
-void *board_fdt_blob_setup(int *err)
+int board_fdt_blob_setup(void **fdtp)
 {
-	*err = 0;
-	if (IS_ENABLED(CONFIG_OF_SEPARATE) || IS_ENABLED(CONFIG_OF_BOARD)) {
-		if (gd->arch.firmware_fdt_addr)
-			return (ulong *)(uintptr_t)gd->arch.firmware_fdt_addr;
+	if (gd->arch.firmware_fdt_addr) {
+		*fdtp = (ulong *)(uintptr_t)gd->arch.firmware_fdt_addr;
+		return 0;
 	}
 
-	return (ulong *)_end;
+	return -EEXIST;
 }
 
 int board_init(void)
diff --git a/board/starfive/visionfive2/starfive_visionfive2.c b/board/starfive/visionfive2/starfive_visionfive2.c
index f611460..3940d45 100644
--- a/board/starfive/visionfive2/starfive_visionfive2.c
+++ b/board/starfive/visionfive2/starfive_visionfive2.c
@@ -115,15 +115,14 @@
 	return 0;
 }
 
-void *board_fdt_blob_setup(int *err)
+int board_fdt_blob_setup(void **fdtp)
 {
-	*err = 0;
-	if (IS_ENABLED(CONFIG_OF_SEPARATE) || IS_ENABLED(CONFIG_OF_BOARD)) {
-		if (gd->arch.firmware_fdt_addr)
-			return (ulong *)(uintptr_t)gd->arch.firmware_fdt_addr;
+	if (gd->arch.firmware_fdt_addr) {
+		*fdtp = (ulong *)(uintptr_t)gd->arch.firmware_fdt_addr;
+		return 0;
 	}
 
-	return (ulong *)_end;
+	return -EEXIST;
 }
 
 int ft_board_setup(void *blob, struct bd_info *bd)
diff --git a/board/xen/xenguest_arm64/xenguest_arm64.c b/board/xen/xenguest_arm64/xenguest_arm64.c
index 4c3b9c9..216a022 100644
--- a/board/xen/xenguest_arm64/xenguest_arm64.c
+++ b/board/xen/xenguest_arm64/xenguest_arm64.c
@@ -44,14 +44,14 @@
  * x0 is the physical address of the device tree blob (dtb) in system RAM.
  * This is stored in rom_pointer during low level init.
  */
-void *board_fdt_blob_setup(int *err)
+int board_fdt_blob_setup(void **fdtp)
 {
-	*err = 0;
-	if (fdt_magic(rom_pointer[0]) != FDT_MAGIC) {
-		*err = -ENXIO;
-		return NULL;
-	}
-	return (void *)rom_pointer[0];
+	if (fdt_magic(rom_pointer[0]) != FDT_MAGIC)
+		return -ENXIO;
+
+	*fdtp = (void *)rom_pointer[0];
+
+	return 0;
 }
 
 /*
diff --git a/board/xilinx/common/board.c b/board/xilinx/common/board.c
index a12dccd..deea6c7 100644
--- a/board/xilinx/common/board.c
+++ b/board/xilinx/common/board.c
@@ -358,17 +358,17 @@
 }
 
 #if defined(CONFIG_OF_BOARD)
-void *board_fdt_blob_setup(int *err)
+int board_fdt_blob_setup(void **fdtp)
 {
 	void *fdt_blob;
 
-	*err = 0;
-
 	if (IS_ENABLED(CONFIG_TARGET_XILINX_MBV)) {
 		fdt_blob = (void *)CONFIG_XILINX_OF_BOARD_DTB_ADDR;
 
-		if (fdt_magic(fdt_blob) == FDT_MAGIC)
-			return fdt_blob;
+		if (fdt_magic(fdt_blob) == FDT_MAGIC) {
+			*fdtp = fdt_blob;
+			return 0;
+		}
 	}
 
 	if (!IS_ENABLED(CONFIG_XPL_BUILD) &&
@@ -376,8 +376,10 @@
 	    !IS_ENABLED(CONFIG_ZYNQMP_NO_DDR)) {
 		fdt_blob = (void *)CONFIG_XILINX_OF_BOARD_DTB_ADDR;
 
-		if (fdt_magic(fdt_blob) == FDT_MAGIC)
-			return fdt_blob;
+		if (fdt_magic(fdt_blob) == FDT_MAGIC) {
+			*fdtp = fdt_blob;
+			return 0;
+		}
 
 		debug("DTB is not passed via %p\n", fdt_blob);
 	}
@@ -396,13 +398,15 @@
 		fdt_blob = (ulong *)_end;
 	}
 
-	if (fdt_magic(fdt_blob) == FDT_MAGIC)
-		return fdt_blob;
+	if (fdt_magic(fdt_blob) == FDT_MAGIC) {
+		*fdtp = fdt_blob;
+
+		return 0;
+	}
 
 	debug("DTB is also not passed via %p\n", fdt_blob);
 
-	*err = -EINVAL;
-	return NULL;
+	return -EINVAL;
 }
 #endif
 
diff --git a/include/fdtdec.h b/include/fdtdec.h
index 555c952..58bbd8f 100644
--- a/include/fdtdec.h
+++ b/include/fdtdec.h
@@ -1191,11 +1191,12 @@
  *
  * The existing devicetree is available at gd->fdt_blob
  *
- * @err: 0 on success, -EEXIST if the devicetree is already correct, or other
- * internal error code if we fail to setup a DTB
- * @returns new devicetree blob pointer
+ * @fdtp: Existing devicetree blob pointer; update this and return 0 if a
+ * different devicetree should be used
+ * Return: 0 on success, -EEXIST if the existing FDT is OK, -ve error code if we
+ * fail to setup a DTB
  */
-void *board_fdt_blob_setup(int *err);
+int board_fdt_blob_setup(void **fdtp);
 
 /*
  * Decode the size of memory
diff --git a/lib/fdtdec.c b/lib/fdtdec.c
index 60e2817..c5d29d4 100644
--- a/lib/fdtdec.c
+++ b/lib/fdtdec.c
@@ -1706,11 +1706,17 @@
 
 	/* Allow the board to override the fdt address. */
 	if (IS_ENABLED(CONFIG_OF_BOARD)) {
-		gd->fdt_blob = board_fdt_blob_setup(&ret);
-		if (!ret)
+		void *blob;
+
+		blob = (void *)gd->fdt_blob;
+		ret = board_fdt_blob_setup(&blob);
+		if (ret) {
+			if (ret != -EEXIST)
+				return ret;
+		} else {
 			gd->fdt_src = FDTSRC_BOARD;
-		else if (ret != -EEXIST)
-			return ret;
+			gd->fdt_blob = blob;
+		}
 	}
 
 	/* Allow the early environment to override the fdt address */