150 lines
3.6 KiB
ArmAsm
150 lines
3.6 KiB
ArmAsm
/***************************************************************************
|
|
* __________ __ ___.
|
|
* Open \______ \ ____ ____ | | _\_ |__ _______ ___
|
|
* Source | _// _ \_/ ___\| |/ /| __ \ / _ \ \/ /
|
|
* Jukebox | | ( <_> ) \___| < | \_\ ( <_> > < <
|
|
* Firmware |____|_ /\____/ \___ >__|_ \|___ /\____/__/\_ \
|
|
* \/ \/ \/ \/ \/
|
|
* $Id$
|
|
*
|
|
* Copyright (C) 2021-2022 Aidan MacDonald
|
|
*
|
|
* 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 "mips.h"
|
|
#include "bootdata.h"
|
|
|
|
.text
|
|
.extern main
|
|
.extern system_early_init
|
|
.extern _loadaddress
|
|
.global _start
|
|
|
|
.set push
|
|
.set mips32
|
|
.set noreorder
|
|
.set noat
|
|
|
|
.section .init.text
|
|
|
|
_start:
|
|
b _realstart
|
|
nop
|
|
|
|
/* Header entries are 4-byte string labels (not null terminated!) followed
|
|
* by 4-byte values. Header should begin in the first 128 bytes and should
|
|
* be no more than 256 bytes in length. */
|
|
_header:
|
|
.ascii "BEGINHDR" /* beginning of header */
|
|
.ascii "LOAD"
|
|
.word _loadaddress
|
|
.ascii "ENDH" /* end of header structure */
|
|
|
|
#ifndef BOOTLOADER
|
|
/* Multiboot support header; this is not part of the above header. */
|
|
put_boot_data_here
|
|
#endif
|
|
|
|
_realstart:
|
|
/* Save bootloader arguments. */
|
|
move s0, a0
|
|
move s1, a1
|
|
move s2, a2
|
|
move s3, a3
|
|
|
|
/* Copy IRAM from BSS to low memory. */
|
|
la a0, _iramcopy
|
|
la a1, _iramstart
|
|
la a2, _iramend
|
|
bal _copy
|
|
nop
|
|
|
|
/* Copy TCSM from BSS */
|
|
la a0, _tcsmcopy
|
|
la a1, _tcsmstart
|
|
la a2, _tcsmend
|
|
bal _copy
|
|
nop
|
|
|
|
/* Clear the BSS segment (needed to zero-initialize C static values) */
|
|
la a0, _bssbegin
|
|
la a1, _bssend
|
|
bal _clear
|
|
move a2, $0
|
|
|
|
/* Set stack pointer and clear the stack */
|
|
la sp, stackend
|
|
la a0, stackbegin
|
|
li a2, 0xDEADBEEF
|
|
bal _clear
|
|
move a1, sp
|
|
|
|
/* Clear the IRQ stack */
|
|
la k0, _irqstackend
|
|
la a0, _irqstackbegin
|
|
bal _clear
|
|
move a1, k0
|
|
|
|
/* Write back D-cache and invalidate I-cache */
|
|
li v0, 0x80000000
|
|
ori v1, v0, (0x4000 - 32)
|
|
mtc0 zero, C0_TAGLO
|
|
mtc0 zero, C0_TAGHI
|
|
1:
|
|
cache DCIndexWBInv, 0(v0)
|
|
cache ICIndexStTag, 0(v0)
|
|
bne v0, v1, 1b
|
|
addiu v0, v0, 32
|
|
|
|
/* Invalidate BTB */
|
|
mfc0 v0, C0_Config, 7
|
|
nop
|
|
ori v0, v0, 2
|
|
mtc0 v0, C0_Config, 7
|
|
nop
|
|
|
|
/* Jump to C code */
|
|
jal system_early_init
|
|
nop
|
|
|
|
/* Restore bootloader arguments, jump to main. */
|
|
move a0, s0
|
|
move a1, s1
|
|
move a2, s2
|
|
move a3, s3
|
|
|
|
j main
|
|
move ra, zero /* init backtrace root */
|
|
|
|
/* copy(void* src, void* dst, void* dst_end) */
|
|
_copy:
|
|
beq a1, a2, 1f
|
|
addiu a1, 4
|
|
lw t0, 0(a0)
|
|
addiu a0, 4
|
|
b _copy
|
|
sw t0, -4(a1)
|
|
1:
|
|
jr ra
|
|
nop
|
|
|
|
/* clear(void* dst, void* dst_end, int value) */
|
|
_clear:
|
|
beq a0, a1, 1f
|
|
addiu a0, 4
|
|
b _clear
|
|
sw a2, -4(a0)
|
|
1:
|
|
jr ra
|
|
nop
|
|
|
|
.set pop
|