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rockbox/firmware/target/arm/imx31/crt0.S
Rafaël Carré 0ea7905395 ARM: use BX when branch to an address in register 
git-svn-id: svn://svn.rockbox.org/rockbox/trunk@26432 a1c6a512-1295-4272-9138-f99709370657
2010-05-31 15:14:26 +00:00

361 lines
11 KiB
ArmAsm
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/***************************************************************************
* __________ __ ___.
* Open \______ \ ____ ____ | | _\_ |__ _______ ___
* Source | _// _ \_/ ___\| |/ /| __ \ / _ \ \/ /
* Jukebox | | ( <_> ) \___| < | \_\ ( <_> > < <
* Firmware |____|_ /\____/ \___ >__|_ \|___ /\____/__/\_ \
* \/ \/ \/ \/ \/
* $Id$
*
* Copyright (C) 2002 by Linus Nielsen Feltzing
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version 2
* of the License, or (at your option) any later version.
*
* This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
* KIND, either express or implied.
*
****************************************************************************/
#include "config.h"
#include "cpu.h"
.section .init.text,"ax",%progbits
.global start
start:
/* Exception vectors */
b newstart
b undef_instr_handler
b software_int_handler
b prefetch_abort_handler
b data_abort_handler
b reserved_handler
subs pc, lr, #4 @ b irq_handler
b fiq_handler
.balign 0x40, 0x6B
/* Arm bootloader and startup code based on startup.s from the iPodLinux loader
*
* Copyright (c) 2003, Daniel Palffy (dpalffy (at) rainstorm.org)
* Copyright (c) 2005, Bernard Leach <leachbj@bouncycastle.org>
*
*/
/* Bootloader:
* Initially this code is running at VA 0x8a000000 (PA 0x82000000).
* The mapping stub is copied to IRAM (0x1fffc000), sets up the MMU and
* jumps into the final VA remapping starting at 0x02000000 (32MB).
*
* Firmware:
* This code will be running from VA 0x00000000 (PA 0x80000000) and perform
* similar steps to the bootloader code.
*/
newstart:
msr cpsr_c, #0xd3 /* enter supervisor mode, disable IRQ/FIQ */
adr r2, remap_start /* Load PC-relative labels (relocatable) */
adr r3, remap_end
ldr r5, =TTB_BASE_ADDR /* TTB pointer */
ldr r6, =IRAM_BASE_ADDR
mov r1, r6
1: /* Copy remapping stub to IRAM */
cmp r3, r2
ldrhi r4, [r2], #4
strhi r4, [r1], #4
bhi 1b
bx r6
/* Remapping stub. No absolute addresses may be used until after the
* remapping is complete. */
remap_start:
mrc p15, 0, r3, c1, c0, 0 /* perform writeback if D cache is enabled */
tst r3, #(1 << 2) /* dcache? */
tsteq r3, #(1 << 12) /* or icache? */
mov r0, #0
mcrne p15, 0, r0, c7, c10, 0 /* clean dcache */
mcrne p15, 0, r0, c7, c7, 0 /* invalidate I cache and D cache */
mcr p15, 0, r0, c8, c7, 0 /* invalidate TLBs */
mcr p15, 0, r0, c7, c10, 4 /* Drain the write buffer */
mcr p15, 0, r0, c13, c0, 0
mcr p15, 0, r0, c13, c0, 1
/* Also setup the Peripheral Port Remap register inside the core */
mov r0, #0x40000000 /* start from AIPS 2GB region */
add r0, r0, #0x15
mcr p15, 0, r0, c15, c2, 4
/*** L2 Cache setup/invalidation/disable ***/
/* Disable L2 cache first */
mov r0, #L2CC_BASE_ADDR
mov r1, #0
str r1, [r0, #L2_CACHE_CTL_REG]
/* Disble L1 caches and memory manager */
bic r3, r3, #(1 << 12) /* L1 I-cache disabled */
bic r3, r3, #((1 << 2) | /* L1 D-cache disabled */ \
(1 << 0)) /* MMU disabled */
mcr p15, 0, r3, c1, c0, 0
/*
* Configure L2 Cache:
* - 128k size(16k way)
* - 8-way associativity
* - 0 ws TAG/VALID/DIRTY
* - 4 ws DATA R/W
*/
mov r1, #0x00130000
orr r1, r1, #0x24
str r1, [r0, #L2_CACHE_AUX_CTL_REG]
/* Invalidate L2 */
mov r1, #0x000000FF
str r1, [r0, #L2_CACHE_INV_WAY_REG]
1:
/* Poll Invalidate By Way register */
ldr r1, [r0, #L2_CACHE_INV_WAY_REG]
cmp r1, #0
bne 1b
/*** End of L2 operations ***/
/* TTB Initialisation */
/* Set TTB base address */
mcr p15, 0, r5, c2, c0, 0
/* Set all domains to manager status */
mvn r0, #0
mcr p15, 0, r0, c3, c0, 0
/* Set page tables */
/* Map each memory loc to itself
* not cached, not buffered */
/* Physical address = 0x0 */
mov r1, #(1 << 10) /* superuser - r/w, user - no access */
orr r1, r1, #((0 << 5) | /* domain 0th */ \
(1 << 4) | /* should be "1" */ \
(1 << 1)) /* Section signature */
mov r2, r5
add r3, r5, #TTB_SIZE /* End position */
1:
str r1, [r2], #4
add r1, r1, #(1 << 20) /* Next MB */
cmp r2, r3
blo 1b
/* Bits 31:20 of r1 will be 0 due to wraparound in previous loop */
/* Map PA:0x80000000-0x83ffffff to VA:0x00000000-0x03f00000
* cached, buffered */
mov r2, r5 /* TTB pointer */
add r3, r5, #64*4 /* End position */
orr r1, r1, #(0x80000000 | /* Physical address */ \
(1 << 3) | /* cache flag */ \
(1 << 2)) /* buffer flag */
1:
str r1, [r2], #4
add r1, r1, #(1 << 20)
cmp r2, r3
blo 1b
/* Map TTB, FRAME and QHARRAY section PA:0x83f00000-0x83ffffff to
* VA:0x04000000-0x040fffff
* not cache, buffered */
sub r1, r1, #0x00100000
bic r1, r1, #(1 << 3) /* clear cache flag */
str r1, [r5, #64*4]
/* Enable MMU */
mov r0, #0
mcr p15, 0, r0, c8, c7, 0 /* Invalidate TLB */
mcr p15, 0, r0, c7, c7, 0 /* Invalidate icache and dcache */
/* Auxilliary control register */
mrc p15, 0, r0, c1, c0, 1
bic r0, r0, #((1 << 6) | /* Restrict cache size OFF */ \
(1 << 5) | /* Enable block tranfer cache operations */ \
(1 << 4) | /* Clean+Invalidate cache operation ON */ \
(1 << 3)) /* Round-robin micro TLB replacement */
orr r0, r0, #((1 << 2) | /* Static branch prediction ON */ \
(1 << 1) | /* Dynamic branch prediction ON */ \
(1 << 0)) /* Return stack enabled */
mcr p15, 0, r0, c1, c0, 1
/* Control register */
mrc p15, 0, r0, c1, c0, 0
bic r0, r0, #((1 << 29) | /* AF by AP disabled */ \
(1 << 28) | /* TEX remap disabled */ \
(1 << 23)) /* Sub AP bits enabled (compatible) */
bic r0, r0, #((1 << 21) | /* All performance features enabled */ \
(1 << 15)) /* Loads to PC set T bit */
bic r0, r0, #((1 << 13)) /* Low vectors */
bic r0, r0, #((1 << 1)) /* Strict alignment disabled */
orr r0, r0, #((1 << 24) | /* Vectored interrupt ON */ \
(1 << 22)) /* Unaligned access support enabled */
orr r0, r0, #((1 << 14) | /* Round-robin replacement for I/D caches */ \
(1 << 12) | /* L1 I-cache enabled */ \
(1 << 11) | /* Program flow prediction enabled */ \
(1 << 9) | /* ROM protection enabled */ \
(1 << 8)) /* MMU protection enabled */
orr r0, r0, #((1 << 2) | /* L1 D-cache enabled */ \
(1 << 0)) /* MMU enabled */
mcr p15, 0, r0, c1, c0, 0
nop
nop
nop
nop
nop
nop
nop
nop
ldr pc, L_post_remap
L_post_remap:
.word remap_end
remap_end:
#ifdef BOOTLOADER
/* Copy bootloader exception handler code to address 0 */
ldr r2, =_vectorsstart
ldr r3, =_vectorsend
ldr r4, =_vectorscopy
1:
cmp r3, r2
ldrhi r5, [r4], #4
strhi r5, [r2], #4
bhi 1b
#endif /* BOOTLOADER */
#ifndef BOOTLOADER
/* Copy discardable SDMA code - loaded in the stack section
* and so must be done first. Destination is the plugin buffer
* which is safe when SDMA init takes place just after kernel
* init. */
ldr r4, =_sdmacodecopy
ldr r3, =_sdmacodeend
ldr r2, =_sdmacodestart
1:
cmp r3, r2
ldrhi r5, [r4], #4
strhi r5, [r2], #4
bhi 1b
#endif /* BOOTLOADER */
/* Initialise bss and ncbss sections to zero */
ldr r2, =_edata
ldr r3, =_end
mov r4, #0
1:
cmp r3, r2
strhi r4, [r2], #4
bhi 1b
/* Set up some stack and munge it with 0xdeadbeef */
ldr sp, =stackend
ldr r2, =stackbegin
ldr r3, =0xdeadbeef
1:
cmp sp, r2
strhi r3, [r2], #4
bhi 1b
/* Set up stack for IRQ mode */
msr cpsr_c, #0xd2
ldr sp, =irq_stack
/* Set up stack for FIQ mode */
msr cpsr_c, #0xd1
ldr sp, =fiq_stack
/* Let abort and undefined modes use IRQ stack */
msr cpsr_c, #0xd7
ldr sp, =irq_stack
msr cpsr_c, #0xdb
ldr sp, =irq_stack
/* Switch back to supervisor mode */
msr cpsr_c, #0xd3
#ifndef BOOTLOADER
/* Enable access to VFP */
mrc p15, 0, r3, c1, c0, 2
orr r3, r3, #0xf00000
mcr p15, 0, r3, c1, c0, 2
/* Enable VFP */
mrc p10, 7, r3, c8, c0, 0
orr r3, r3, #1<<30
mcr p10, 7, r3, c8, c0, 0
/* Disable exceptions, enable default NaN, flush-to-zero, round toward 0 */
mrc p10, 7, r3, c1, c0, 0
orr r3, r3, #15<<22
bic r3, r3, #31<<8
mcr p10, 7, r3, c1, c0, 0
#endif
/* Make memory coherent for devices */
bl clean_dcache
bl main
#ifdef BOOTLOADER
/* Exception vectors with absolute jumps for bootloader */
.section .vectors,"aw"
ldr pc, [pc, #24]
ldr pc, [pc, #24]
ldr pc, [pc, #24]
ldr pc, [pc, #24]
ldr pc, [pc, #24]
ldr pc, [pc, #24]
subs pc, lr, #4 @ ldr pc, [pc, #24]
ldr pc, [pc, #24]
.word newstart
.word undef_instr_handler
.word software_int_handler
.word prefetch_abort_handler
.word data_abort_handler
.word reserved_handler
.word 0 @ irq_handler
.word fiq_handler
#endif /* BOOTLOADER */
.text
/* All illegal exceptions call into UIE with exception address as first
* parameter. This is calculated differently depending on which exception
* we're in. Second parameter is exception number, used for a string lookup
* in UIE. */
undef_instr_handler:
sub r0, lr, #4
mov r1, #0
b UIE
/* We run supervisor mode most of the time, and should never see a software
* exception being thrown. Perhaps make it illegal and call UIE? */
software_int_handler:
reserved_handler:
movs pc, lr
prefetch_abort_handler:
sub r0, lr, #4
mov r1, #1
b UIE
data_abort_handler:
sub r0, lr, #8
mov r1, #2
b UIE
/* 256 words of IRQ stack */
.space 256*4
irq_stack:
/* 256 words of FIQ stack */
.space 256*4
fiq_stack:
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