354 lines
8.4 KiB
ArmAsm
354 lines
8.4 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) 2002 by Linus Nielsen Feltzing
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*
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* All files in this archive are subject to the GNU General Public License.
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* See the file COPYING in the source tree root for full license agreement.
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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 .init.text,"ax",%progbits
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.global start
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start:
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/* Arm bootloader and startup code based on startup.s from the iPodLinux loader
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*
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* Copyright (c) 2003, Daniel Palffy (dpalffy (at) rainstorm.org)
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* Copyright (c) 2005, Bernard Leach <leachbj@bouncycastle.org>
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*
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*/
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msr cpsr, #0xd3 /* enter supervisor mode, disable IRQ */
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#if !defined(BOOTLOADER)
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/* Copy exception handler code to address 0 */
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ldr r2, =_vectorsstart
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ldr r3, =_vectorsend
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ldr r4, =_vectorscopy
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1:
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cmp r3, r2
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ldrhi r5, [r4], #4
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strhi r5, [r2], #4
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bhi 1b
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#endif
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#if !defined(BOOTLOADER) && !defined(STUB)
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/* Zero out IBSS */
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ldr r2, =_iedata
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ldr r3, =_iend
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mov r4, #0
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1:
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cmp r3, r2
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strhi r4, [r2], #4
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bhi 1b
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/* Copy the IRAM */
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ldr r2, =_iramcopy
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ldr r3, =_iramstart
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ldr r4, =_iramend
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1:
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cmp r4, r3
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ldrhi r5, [r2], #4
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strhi r5, [r3], #4
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bhi 1b
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#endif /* !BOOTLOADER, !STUB */
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/* Initialise bss section to zero */
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ldr r2, =_edata
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ldr r3, =_end
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mov r4, #0
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1:
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cmp r3, r2
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strhi r4, [r2], #4
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bhi 1b
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/* Set up some stack and munge it with 0xdeadbeef */
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ldr sp, =stackend
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mov r3, sp
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ldr r2, =stackbegin
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ldr r4, =0xdeadbeef
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1:
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cmp r3, r2
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strhi r4, [r2], #4
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bhi 1b
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#ifdef BOOTLOADER
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/* Proper initialization pulled from 0x5070 */
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/* BWSCON
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* Reserved 0
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* Bank 0:
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* Bus width 01 (16 bit)
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* Bank 1:
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* Buswidth 00 (8 bit)
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* Disable wait 0
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* Not using UB/LB 0
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* Bank 2:
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* Buswidth 10 (32 bit)
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* Disable wait 0
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* Not using UB/LB 0
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* Bank 3:
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* Buswidth 10 (32 bit)
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* Disable wait 0
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* Use UB/LB 1
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* Bank 4:
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* Buswidth 10 (32 bit)
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* Disable wait 0
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* Use UB/LB 1
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* Bank 5:
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* Buswidth 00 (8 bit)
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* Disable wait 0
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* Not using UB/LB 0
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* Bank 6:
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* Buswidth 10 (32 bit)
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* Disable wait 0
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* Not using UB/LB 0
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* Bank 7:
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* Buswidth 00 (8 bit)
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* Disable wait 0
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* Not using UB/LB 0
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*/
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ldr r2,=0x01055102
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mov r1, #0x48000000
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str r2, [r1]
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/* BANKCON0
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* Pagemode: normal (1 data) 00
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* Pagemode access cycle: 2 clocks 00
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* Address hold: 2 clocks 10
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* Chip selection hold time: 1 clock 10
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* Access cycle: 8 clocks 101
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* Chip select setup time: 1 clock 01
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* Address setup time: 0 clock 00
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*/
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ldr r2,=0x00000D60
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str r2, [r1, #4]
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/* BANKCON1
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* Pagemode: normal (1 data) 00
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* Pagemode access cycle: 2 clocks 00
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* Address hold: 0 clocks 00
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* Chip selection hold time: 0 clock 00
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* Access cycle: 1 clocks 000
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* Chip select setup time: 0 clocks 00
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* Address setup time: 0 clocks 00
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*/
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ldr r2,=0x00000000
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str r2, [r1, #8]
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/* BANKCON2
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* Pagemode: normal (1 data) 00
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* Pagemode access cycle: 2 clocks 00
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* Address hold: 2 clocks 10
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* Chip selection hold time: 2 clocks 10
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* Access cycle: 14 clocks 111
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* Chip select setup time: 4 clocks 11
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* Address setup time: 0 clocks 00
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*/
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ldr r2,=0x00001FA0
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str r2, [r1, #0xC]
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/* BANKCON3 */
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ldr r2,=0x00001D80
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str r2, [r1, #0x10]
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/* BANKCON4 */
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str r2, [r1, #0x14]
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/* BANKCON5 */
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ldr r2,=0x00000000
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str r2, [r1, #0x18]
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/* BANKCON6/7
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* SCAN: 9 bit 01
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* Trcd: 3 clocks 01
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* Tcah: 0 clock 00
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* Tcoh: 0 clock 00
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* Tacc: 1 clock 000
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* Tcos: 0 clock 00
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* Tacs: 0 clock 00
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* MT: Sync DRAM 11
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*/
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ldr r2,=0x00018005
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str r2, [r1, #0x1C]
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/* BANKCON7 */
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str r2, [r1, #0x20]
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/* REFRESH */
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ldr r2,=0x00980501
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str r2, [r1, #0x24]
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/* BANKSIZE
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* BK76MAP: 32M/32M 000
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* Reserved: 0 0 (was 1)
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* SCLK_EN: always 1 (was 0)
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* SCKE_EN: disable 0
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* Reserved: 0 0
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* BURST_EN: enabled 1
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*/
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ldr r2,=0x00000090
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str r2, [r1, #0x28]
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/* MRSRB6 */
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ldr r2,=0x00000030
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str r2, [r1, #0x2C]
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/* MRSRB7 */
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str r2, [r1, #0x30]
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#if 0
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/* This next part I am not sure of the purpose */
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/* GPACON */
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mov r2,#0x01FFFCFF
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str r2,=0x56000000
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/* GPADAT */
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mov r2,#0x01FFFEFF
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str r2,=0x56000004
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/* MRSRB6 */
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mov r2,#0x00000000
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str r2,=0x4800002C
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/* GPADAT */
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ldr r2,=0x01FFFFFF
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mov r1, #0x56000000
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str r2, [r1, #4]
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/* MRSRB6 */
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mov r2,#0x00000030
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str r2,=0x4800002C
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/* GPACON */
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mov r2,#0x01FFFFFF
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str r2,=0x56000000
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/* End of the unknown */
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#endif
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/* get the high part of our execute address */
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ldr r2, =0xffffff00
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and r4, pc, r2
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/* Copy bootloader to safe area - 0x31000000 */
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mov r5, #0x30000000
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add r5, r5, #0x1000000
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ldr r6, = _dataend
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sub r0, r6, r5 /* length of loader */
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add r0, r4, r0 /* r0 points to start of loader */
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1:
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cmp r5, r6
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ldrcc r2, [r4], #4
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strcc r2, [r5], #4
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bcc 1b
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ldr pc, =start_loc /* jump to the relocated start_loc: */
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start_loc:
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bl main
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#else /* BOOTLOADER */
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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 to supervisor mode */
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msr cpsr_c, #0xd3
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ldr sp, =stackend
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bl main
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/* main() should never return */
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/* Exception handlers. Will be copied to address 0 after memory remapping */
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.section .vectors,"aw"
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ldr pc, [pc, #24]
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ldr pc, [pc, #24]
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ldr pc, [pc, #24]
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ldr pc, [pc, #24]
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ldr pc, [pc, #24]
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ldr pc, [pc, #24]
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ldr pc, [pc, #24]
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ldr pc, [pc, #24]
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/* Exception vectors */
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.global vectors
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vectors:
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.word start
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.word undef_instr_handler
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.word software_int_handler
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.word prefetch_abort_handler
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.word data_abort_handler
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.word reserved_handler
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.word irq_handler
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.word fiq_handler
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.text
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#ifndef STUB
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.global irq
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.global fiq
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.global UIE
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#endif
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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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*/
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undef_instr_handler:
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mov r0, lr
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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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*/
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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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#ifdef STUB
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UIE:
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b UIE
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#endif
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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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#endif /* BOOTLOADER */
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