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/*
* This file is part of the libpayload project.
*
* Copyright (C) 2014 Imagination Technologies
*
* 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; version 2 of the License.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*/
#include <arch/cpu.h>
/* Disable interrupts and mark the kernel mode */
.macro setup_c0_status clr
.set push
mfc0 $t0, $CP0_STATUS
or $t0, ST0_CU0 | 0x1f | \clr
xor $t0, 0x1f | \clr
mtc0 $t0, $CP0_STATUS
.set noreorder
sll $zero, 3
.set pop
.endm
/* Don't reorder instructions */
.set noreorder
.align 4
.global cb_header_ptr
cb_header_ptr:
.word 0
.global old_sp
old_sp:
.word 0
.global _entry, _leave
.text
/* Our entry point */
_entry:
/*
* This function saves off the previous stack and switches us to our
* own execution environment.
*/
/* Clear watch and cause registers */
mtc0 $zero, $CP0_WATCHLO
mtc0 $zero, $CP0_WATCHHI
mtc0 $zero, $CP0_CAUSE
/* Disable interrupts */
setup_c0_status 0
/* Don't use at in synthetic instr. */
.set noat
/* Init timer */
mtc0 $zero, $CP0_COUNT
mtc0 $zero, $CP0_COMPARE
/* Initialize $gp */
bal 1f
nop
.word _gp
1:
lw $gp, 0($ra)
/* Save off the location of the coreboot tables */
la $at, cb_header_ptr
sw $a0, 0x00($at)
/* Save old stack pointer */
la $at, old_sp
sw $sp, 0x00($at)
/* Setup new stack */
la $sp, _stack
/* Let's rock */
la $a2, start_main
jalr $a2
nop
_leave:
/* Restore old stack. */
lw $sp, old_sp
/* Return to the original context. */
eret
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