xref: /arm-trusted-firmware/plat/arm/board/arm_fpga/rom_trampoline.S (revision 91f16700b400a8c0651d24a598fc48ee2997a0d7)
1*91f16700Schasinglulu/*
2*91f16700Schasinglulu * Copyright (c) 2020, ARM Limited. All rights reserved.
3*91f16700Schasinglulu *
4*91f16700Schasinglulu * SPDX-License-Identifier: BSD-3-Clause
5*91f16700Schasinglulu *
6*91f16700Schasinglulu * The Arm Ltd. FPGA images start execution at address 0x0, which is
7*91f16700Schasinglulu * mapped at an (emulated) ROM image. The payload uploader can write to
8*91f16700Schasinglulu * this memory, but write access by the CPU cores is prohibited.
9*91f16700Schasinglulu *
10*91f16700Schasinglulu * Provide a simple trampoline to start BL31 execution at the actual
11*91f16700Schasinglulu * load address. We put the DTB address in x0, so any code in DRAM could
12*91f16700Schasinglulu * make use of that information (not yet used in BL31 right now).
13*91f16700Schasinglulu */
14*91f16700Schasinglulu
15*91f16700Schasinglulu#include <asm_macros.S>
16*91f16700Schasinglulu#include <common/bl_common.ld.h>
17*91f16700Schasinglulu
18*91f16700Schasinglulu.text
19*91f16700Schasinglulu.global _start
20*91f16700Schasinglulu
21*91f16700Schasinglulu_start:
22*91f16700Schasinglulu	mov_imm	x1, BL31_BASE			/* beginning of DRAM */
23*91f16700Schasinglulu	mov_imm	x0, FPGA_PRELOADED_DTB_BASE
24*91f16700Schasinglulu	br	x1
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