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)