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/*----------------------------------------------------------------
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// //
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// start.S //
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// //
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// This file is part of the Amber project //
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// http://www.opencores.org/project,amber //
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// //
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// Description //
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// Assembly routines for boot-loader. //
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// As boot-loader is a stand-alone application, it needs a //
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// simple start function written in assembly to call the //
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// C code main() function. //
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// //
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// Author(s): //
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// - Conor Santifort, csantifort.amber@gmail.com //
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// //
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//////////////////////////////////////////////////////////////////
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// //
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// Copyright (C) 2010 Authors and OPENCORES.ORG //
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// //
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// This source file may be used and distributed without //
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// restriction provided that this copyright statement is not //
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// removed from the file and that any derivative work contains //
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// the original copyright notice and the associated disclaimer. //
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// //
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// This source file is free software; you can redistribute it //
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// and/or modify it under the terms of the GNU Lesser General //
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// Public License as published by the Free Software Foundation; //
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// either version 2.1 of the License, or (at your option) any //
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// later version. //
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// //
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// This source is distributed in the hope that it will be //
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// useful, but WITHOUT ANY WARRANTY; without even the implied //
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// warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR //
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// PURPOSE. See the GNU Lesser General Public License for more //
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// details. //
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// //
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// You should have received a copy of the GNU Lesser General //
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// Public License along with this source; if not, download it //
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// from http://www.opencores.org/lgpl.shtml //
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// //
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----------------------------------------------------------------*/
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#include "amber_registers.h"
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/* Defined in vmlinux/include/asm-arm/setup.h */
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#define ATAG_CORE 0x54410001
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#define ATAG_MEM 0x54410002
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#define ATAG_INITRD 0x54410005
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#define ATAG_RAMDISK 0x54410004
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#define ATAG_NONE 0x00000000
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#define ATAG_CORE_SIZE ((2*4 + 3*4) >> 2)
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#define ATAG_MEM_SIZE ((2*4 + 2*4) >> 2)
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#define ATAG_INITRD_SIZE ((2*4 + 2*4) >> 2)
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#define ATAG_RAMDISK_SIZE ((2*4 + 3*4) >> 2)
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/* from vmlinux/arch/arm/kernel/compat.c */
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#define FLAG_READONLY 1
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/* from the list in wmlinux/arch/arm/tools/mach-types */
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#define MACH_TYPE_A5K 11
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.section .text
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.globl start
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start:
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/* 0x00 Reset Interrupt vector address */
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b startup
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/* 0x04 Undefined Instruction Interrupt vector address */
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b _testfail
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/* 0x08 SWI Interrupt vector address */
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b _testfail
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/* 0x0c Prefetch abort Interrupt vector address */
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b _testfail
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/* 0x10 Data abort Interrupt vector address */
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b _testfail
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b _testfail
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/* 0x18 IRQ vector address */
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b _testfail
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/* 0x1c FIRQ vector address */
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b _testfail
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startup:
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/* Unset interrupt mask bits, stay in svc mode */
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mov r0, #0x00000003
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teqp pc, r0
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@ Enable the cache
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mov r0, #0xffffffff
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mcr 15, 0, r0, cr3, cr0, 0 @ cacheable area
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mov r0, #1
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mcr 15, 0, r0, cr2, cr0, 0 @ cache enable
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@ init SP
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ldr sp, AdrStack
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@ Set 32MB memory mode
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ldr r0, AdrMemCtrl
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mov r1, #1
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str r1, [r0]
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.extern main
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bl main
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@ jump to program at r0
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.globl _jump_to_program
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_jump_to_program:
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@ ----------------------------------------------
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@ Copy ATAG structure to AdrBootParams
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@ ----------------------------------------------
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ldr r1, AdrBootParams
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ldr r2, AdrATAGBase
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ldr r3, AdeEndATAG
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1: cmp r2, r3
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beq 2f
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ldr r4, [r2], #4
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str r4, [r1], #4
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b 1b
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@ Set memc page tables
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2: ldr r2, AdrPageTabes
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mov r3, #0
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mov r4, #40
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3: str r3,[r2],#4
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subs r4, r4, #1
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bne 3b
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@ ----------------------------------------------
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@ jump to start of program in svc mode with interrupts disabled
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@ ----------------------------------------------
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mov r4, r0
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orr r4, #0x0c000003
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mov r0, #0
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mov pc, r4
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@ ----------------------------------------------
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@ Print CPU Core status
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@ ----------------------------------------------
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.globl _core_status
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_core_status:
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stmdb sp!,{lr}
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stmdb sp!,{r0-r12}
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mov r4, #0
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mov r5, sp
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mov r6, lr
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1: ldr r0, =Status_Message
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mov r1, r4
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ldr r2, [r5], #4
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bl printf
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cmp r4, #13
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addne r4, r4, #1
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bne 1b
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@ Stack Pointer
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ldr r0, =SPStatus_Message
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mov r1, sp
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bl printf
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@ Program Counter - Use Link Register value because
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@ want the PC value of whatever called this function
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ldr r0, =PCStatus_Message
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sub r1, r6, #4
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bl printf
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ldmia sp!,{r0-r12}
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ldmia sp!,{pc}^
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/* stack at top of ddr3 memory space */
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AdrStack: .word 0x02000000
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AdrMemCtrl: .word ADR_AMBER_TEST_MEM_CTRL
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/* core status messages */
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Status_Message: .ascii "r%2d %08x\n\00"
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SPStatus_Message: .ascii "sp %08x\n\00"
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PCStatus_Message: .ascii "pc %08x\n\00"
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.align 2
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AdrATAGBase: .word ATAGBase
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AdeEndATAG: .word EndATAG
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ATAGBase: .word ATAG_CORE_SIZE
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.word ATAG_CORE
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.word FLAG_READONLY @ flags
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.word 4096 @ page size
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.word 0x0 @ rootdev
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.word ATAG_MEM_SIZE
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.word ATAG_MEM
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.word 32*1024*1024 @ size - 32MB
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.word 0x0 @ start
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.word ATAG_RAMDISK_SIZE
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.word ATAG_RAMDISK
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.word 1 @ flags: bit 0 = load, bit 1 = prompt
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.word 0x000000d0 @ size in 1k blocks
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.word 0x00800000 @ physical address of start of ramdisk
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.word ATAG_INITRD_SIZE
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.word ATAG_INITRD
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.word 0x02800000 @ virtual address of start of initrd image
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.word 0x00032000 @ size = 200k
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.word ATAG_NONE
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.word 0x0
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EndATAG: .word 0x0
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AdrBootParams: .word 0x7c000
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AdrPageTabes: .word 0x3f01000
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