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rockbox/firmware/target/arm/pp/crt0-pp.S
Johannes Rauh da190727e7 Enable boot from SD for Sansa e200 
Change-Id: I0940f2cd5fc914d6d5061b5798b1a636009649b7
2020-08-19 19:17:01 -04:00

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12 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"
#if defined(HAVE_BOOTDATA) && !defined(BOOTLOADER)
#include "bootdata.h"
#endif
.section .init.text,"ax",%progbits
.global start
start:
/* PortalPlayer 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>
*
*/
#if CONFIG_CPU == PP5002
.equ PROC_ID, 0xc4000000
.equ CPU_ICLR, 0xcf001028
.equ CPU_CTRL, 0xcf004054
.equ COP_ICLR, 0xcf001038
.equ COP_CTRL, 0xcf004058
.equ CPU_STATUS, 0xcf004050
.equ COP_STATUS, 0xcf004050
.equ SLEEP, 0x000000ca
.equ WAKE, 0x000000ce
.equ CPUSLEEPING, 0x00008000
.equ COPSLEEPING, 0x00004000
.equ CACHE_CTRL, 0xcf004024
.equ MMAP_LOG, 0xf000f000 /* MMAP0 */
.equ MMAP_PHYS, 0xf000f004
#if MEMORYSIZE > 32
.equ MMAP_MASK, 0x00003c00
#else
.equ MMAP_MASK, 0x00003e00
#endif
.equ MMAP_FLAGS, 0x00003f84
#else
.equ PROC_ID, 0x60000000
.equ CPU_ICLR, 0x60004028
.equ CPU_CTRL, 0x60007000
.equ CPU_STATUS, 0x60007000
.equ COP_ICLR, 0x60004038
.equ COP_CTRL, 0x60007004
.equ COP_STATUS, 0x60007004
.equ SLEEP, 0x80000000
.equ WAKE, 0x00000000
.equ CPUSLEEPING, 0x80000000
.equ COPSLEEPING, 0x80000000
.equ CACHE_CTRL, 0x6000c000
.equ MMAP_LOG, 0xf000f000 /* MMAP0 */
.equ MMAP_PHYS, 0xf000f004
#if MEMORYSIZE > 32
.equ MMAP_MASK, 0x00003c00
#else
.equ MMAP_MASK, 0x00003e00
#endif
.equ MMAP_FLAGS, 0x00000f84
#endif
msr cpsr_c, #0xd3 /* enter supervisor mode, disable IRQ/FIQ */
b pad_skip
.space 6*4 /* pad to offset 0x20 */
.ascii "Rockbox" /* signature for bootloader checking osos */
.byte 1 /* osos boot version, only 1 exists for now */
.space 56*4 /* (more than enough) space for exception vectors and mi4 magic */
pad_skip:
/* Find out which processor we are - r0 should be preserved for the
* duration of the init to avoid constant reloading of the processor ID.
* For each stage, CPU proceeds first, then COP.
*/
ldr r0, =PROC_ID
ldrb r0, [r0]
/* We need to remap memory from wherever SDRAM is mapped natively, to
base address 0, so we can put our exception vectors there. We don't
want to do this remapping while executing from SDRAM, so we copy the
remapping code to IRAM, then execute from there. Hence, the following
code is compiled for address 0, but is currently executing at either
0x28000000 or 0x10000000, depending on chipset version. Do not use any
absolute addresses until remapping has been done. */
/* Cores are stepped though the init in turn: CPU then COP. The the remap
stage is completed by each core in turn and then the COP waits for the
CPU to finish initializing its kernel where the CPU will wake the COP
and wait for the COP to finish. This ensures no threading activity
starts until it is safe. */
cmp r0, #0x55
/* mask all interrupt sources before setting anything up */
ldreq r2, =CPU_ICLR
ldrne r2, =COP_ICLR
mvn r1, #0
str r1, [r2]
/* put us (co-processor) to sleep and wait for CPU to remap */
ldrne r2, =COP_CTRL
movne r1, #SLEEP
strne r1, [r2]
nop
nop
nop
/* wait for co-processor to sleep then CPU can begin its remapping */
ldreq r2, =COP_STATUS
1:
ldreq r1, [r2]
tsteq r1, #COPSLEEPING
beq 1b
/* disable cache and local interrupt vectors - it is really not desireable
to have them enabled here */
ldr r2, =CACHE_CTRL
mov r1, #0
str r1, [r2]
#if defined(IPOD_VIDEO)
/* detect 32mb vs 64mb model */
/* we do this here because after SDRAM is remapped, we already assumed */
/* its size to be whatever we were compiled for. */
mov r2, #0x12000000
mov r3, #64
strb r3, [r2, #-1] /* first write 64 to last byte of first 32MB bank */
mov r2, #0x14000000
mov r3, #32
strb r3, [r2, #-1] /* now write 32 to last byte of second 32MB bank */
/* now the last word of the first 32MB bank tells you the RAM size */
/* since on a 32MB model both writes will touch the same actual location */
/* this is read later on in boot */
#endif
mov r2, #0x40000000
ldr r3, =remap_start
ldr r4, =remap_end
and r6, pc, #0xff000000 /* adjust for execute address */
orr r3, r3, r6
orr r4, r4, r6
/* copy the code to 0x40000000 */
1:
ldr r5, [r3], #4
str r5, [r2], #4
cmp r3, r4
blo 1b
ldr r4, =MMAP_FLAGS
orr r4, r4, r6 /* adjust for execute address */
ldr r3, =MMAP_PHYS
ldr r2, =MMAP_MASK /* ldr is more flexible */
ldr r1, =MMAP_LOG
mov pc, #0x40000000
remap_start:
str r2, [r1]
str r4, [r3]
ldr r1, L_post_remap
bx r1
L_post_remap:
.word remap_end
remap_end:
cmp r0, #0x55
ldr r4, =COP_CTRL
/* Wakeup co-processor to let it do remappings */
moveq r3, #WAKE
/* Sleep us (co-processor) and wait for CPU to do kernel initialization */
movne r3, #SLEEP
str r3, [r4]
nop
nop
nop
/* Jump to co-processor init */
ldrne pc, =cop_init
cpu_init:
/* Wait for COP to go to sleep before proceeding */
ldr r4, =COP_STATUS
1:
ldr r3, [r4]
tst r3, #COPSLEEPING
beq 1b
/* Vectors and IRAM copy is done first since they are reclaimed for
* other uninitialized sections */
/* Copy 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
/* Copy the IRAM */
ldr r2, =_iramcopy
ldr r3, =_iramstart
ldr r4, =_iramend
1:
cmp r4, r3
ldrhi r5, [r2], #4
strhi r5, [r3], #4
bhi 1b
#ifdef HAVE_INIT_ATTR
/* copy init code to codec buffer */
ldr r2, =_initstart
ldr r3, =_initend
ldr r4, =_initcopy
1:
cmp r3, r2
ldrhi r5, [r4], #4
strhi r5, [r2], #4
bhi 1b
#endif
/* Zero out IBSS */
ldr r2, =_iedata
ldr r3, =_iend
mov r4, #0
1:
cmp r3, r2
strhi r4, [r2], #4
bhi 1b
/* Initialise bss section to zero */
ldr r2, =_edata
ldr r3, =_end
mov r4, #0
1:
cmp r3, r2
strhi r4, [r2], #4
bhi 1b
/* Load stack munge value */
ldr r4, =0xdeadbeef
#if NUM_CORES > 1
/* Set up idle stack and munge it with 0xdeadbeef */
ldr r2, =cpu_idlestackbegin
ldr r3, =cpu_idlestackend
1:
cmp r3, r2
strhi r4, [r2], #4
bhi 1b
#endif
/* Set up stack for IRQ mode */
msr cpsr_c, #0x92 /* IRQ disabled, FIQ enabled */
ldr sp, =irq_stack
/* Set up stack for FIQ mode */
msr cpsr_c, #0xd1 /* IRQ/FIQ disabled */
ldr sp, =fiq_stack
/* Let svc, abort and undefined modes use irq stack */
msr cpsr_c, #0xd3 /* IRQ/FIQ disabled */
ldr sp, =irq_stack
msr cpsr_c, #0xd7 /* IRQ/FIQ disabled */
ldr sp, =irq_stack
msr cpsr_c, #0xdb /* IRQ/FIQ disabled */
ldr sp, =irq_stack
/* Switch to sys mode */
msr cpsr_c, #0xdf
/* Set up some stack and munge it with 0xdeadbeef */
ldr r2, =stackbegin
ldr sp, =stackend
1:
cmp sp, r2
strhi r4, [r2], #4
bhi 1b
/* Delay waking the COP until thread initialization is complete unless dual-core
support is not enabled in which case the cop_main function does not perform
any kernel or thread initialization. It's just a trivial sleep loop. */
#if NUM_CORES == 1
ldr r4, =COP_CTRL
mov r3, #WAKE
str r3, [r4]
#endif
ldr pc, =main
/* main() should never return */
cop_init:
#if NUM_CORES > 1
/* Wait for CPU to go to sleep at the end of its kernel init */
ldr r4, =CPU_STATUS
1:
ldr r3, [r4]
tst r3, #CPUSLEEPING
beq 1b
#endif
/* Set up stack for IRQ mode */
msr cpsr_c, #0x92 /* IRQ disabled, FIQ enabled */
ldr sp, =cop_irq_stack
/* Set up stack for FIQ mode */
msr cpsr_c, #0xd1 /* IRQ/FIQ disabled */
ldr sp, =cop_fiq_stack
/* Let svc, abort and undefined modes use irq stack */
msr cpsr_c, #0xd3 /* IRQ/FIQ disabled */
ldr sp, =cop_irq_stack
msr cpsr_c, #0xd7 /* IRQ/FIQ disabled */
ldr sp, =cop_irq_stack
msr cpsr_c, #0xdb /* IRQ/FIQ disabled */
ldr sp, =cop_irq_stack
/* Switch to sys mode */
msr cpsr_c, #0xdf
/* Set up idle stack for COP and munge it with 0xdeadbeef */
ldr sp, =cop_idlestackend
ldr r2, =cop_idlestackbegin
ldr r4, =0xdeadbeef
2:
cmp sp, r2
strhi r4, [r2], #4
bhi 2b
/* Run cop_main() in apps/main.c */
ldr pc, =cop_main
/* Exception handlers. Will be copied to address 0 after memory remapping */
.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]
ldr pc, [pc, #24]
ldr pc, [pc, #24]
/* Exception vectors */
.global vectors
vectors:
.word start
.word undef_instr_handler
.word software_int_handler
.word prefetch_abort_handler
.word data_abort_handler
.word reserved_handler
.word irq_handler
.word fiq_handler
.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 sys mode most of the time, and should never see a software
exception being thrown. Make it illegal and call UIE.
*/
software_int_handler:
reserved_handler:
sub r0, lr, #4
mov r1, #4
b UIE
prefetch_abort_handler:
sub r0, lr, #4
mov r1, #1
b UIE
#if defined(HAVE_BOOTDATA) && !defined(BOOTLOADER)
/* boot data structure */
put_boot_data_here
#endif
/* Align stacks to cache line boundary */
.balign 32
/* 256 words of IRQ stack */
.space 256*4
irq_stack:
/* 256 words of COP IRQ stack */
.space 256*4
cop_irq_stack:
/* 256 words of FIQ stack */
.space 256*4
fiq_stack:
/* We'll need this soon - just reserve the symbol */
#if 0
/* 256 words of COP FIQ stack */
.space 256*4
#endif
cop_fiq_stack:
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