118 lines
3.3 KiB
ArmAsm
118 lines
3.3 KiB
ArmAsm
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/***************************************************************************
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* __________ __ ___.
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* Open \______ \ ____ ____ | | _\_ |__ _______ ___
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* Source | _// _ \_/ ___\| |/ /| __ \ / _ \ \/ /
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* Jukebox | | ( <_> ) \___| < | \_\ ( <_> > < <
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* Firmware |____|_ /\____/ \___ >__|_ \|___ /\____/__/\_ \
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* \/ \/ \/ \/ \/
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* $Id$
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*
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* Copyright (C) 2011 by Amaury Pouly
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version 2
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* of the License, or (at your option) any later version.
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*
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* This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
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* KIND, either express or implied.
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*
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****************************************************************************/
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#include "config.h"
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#include "cpu.h"
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.section .vectors,"ax",%progbits
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.code 32
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.global start
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start:
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/* most handlers are in DRAM which is too far away for a relative jump */
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ldr pc, =newstart
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ldr pc, =undef_instr_handler
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ldr pc, =software_int_handler
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ldr pc, =prefetch_abort_handler
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ldr pc, =data_abort_handler
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ldr pc, =reserved_handler
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ldr pc, =irq_handler
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ldr pc, =fiq_handler
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.text
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newstart:
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msr cpsr_c, #0xd3 /* enter supervisor mode, disable IRQ/FIQ */
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/* Set up some stack and munge it with 0xdeadbeef */
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ldr sp, =stackend
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ldr r2, =stackbegin
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ldr r3, =0xdeadbeef
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1:
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cmp sp, r2
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strhi r3, [r2], #4
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bhi 1b
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/* Set up stack for IRQ mode */
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msr cpsr_c, #0xd2
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ldr sp, =irq_stack
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/* Set up stack for FIQ mode */
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msr cpsr_c, #0xd1
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ldr sp, =fiq_stack
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/* Let abort and undefined modes use IRQ stack */
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msr cpsr_c, #0xd7
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ldr sp, =irq_stack
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msr cpsr_c, #0xdb
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ldr sp, =irq_stack
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/* Switch back to supervisor mode */
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msr cpsr_c, #0xd3
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/* Disable MMU, disable caching and buffering;
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* use low exception range address (the core uses high range by default) */
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mrc p15, 0, r0, c1, c0, 0
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ldr r1, =0x3005
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bic r0, r1
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mcr p15, 0, r0, c1, c0, 0
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/* Jump to main */
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bl main
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1:
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b 1b
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/* All illegal exceptions call into UIE with exception address as first
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* parameter. This is calculated differently depending on which exception
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* we're in. Second parameter is exception number, used for a string lookup
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* in UIE. */
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undef_instr_handler:
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sub r0, lr, #4 @ r0 points to the faulty ARM instruction
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#ifdef USE_THUMB
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mrs r1, spsr
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tst r1, #(1<<5) @ T bit set ?
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subne r0, lr, #2 @ if yes, r0 points to the faulty THUMB instruction
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#endif /* USE_THUMB */
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mov r1, #0
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b UIE
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/* We run supervisor mode most of the time, and should never see a software
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* exception being thrown. Perhaps make it illegal and call UIE? */
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software_int_handler:
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reserved_handler:
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movs pc, lr
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prefetch_abort_handler:
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sub r0, lr, #4
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mov r1, #1
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b UIE
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data_abort_handler:
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sub r0, lr, #8
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mov r1, #2
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b UIE
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/* 256 words of IRQ stack */
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.space 256*4
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irq_stack:
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/* 256 words of FIQ stack */
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.space 256*4
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fiq_stack:
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end:
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