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/*
* File : start_gcc.S
* Change Logs:
* Date Author Notes
* 2010-05-17 swkyer first version
* 2010-09-04 bernard porting to Jz47xx
*/
#include "../common/mips.inc"
#include "../common/stackframe.h"
#include "stack.h"
.section ".start", "ax"
.set noreorder
/* the program entry */
.globl _start
_start:
.set noreorder
la ra, _start
li t1, 0x00800000
mtc0 t1, CP0_CAUSE
/* init cp0 registers. */
li t0, 0x0000FC00 /* BEV = 0 and mask all interrupt */
mtc0 t0, CP0_STATUS
/* setup stack pointer */
li sp, SYSTEM_STACK
la gp, _gp
/* init caches, assumes a 4way * 128set * 32byte I/D cache */
mtc0 zero, CP0_TAGLO /* TAGLO reg */
mtc0 zero, CP0_TAGHI /* TAGHI reg */
li t0, 3 /* enable cache for kseg0 accesses */
mtc0 t0, CP0_CONFIG /* CONFIG reg */
la t0, 0x80000000 /* an idx op should use an unmappable address */
ori t1, t0, 0x4000 /* 16kB cache */
_cache_loop:
cache 0x8, 0(t0) /* index store icache tag */
cache 0x9, 0(t0) /* index store dcache tag */
bne t0, t1, _cache_loop
addiu t0, t0, 0x20 /* 32 bytes per cache line */
nop
/* invalidate BTB */
mfc0 t0, CP0_CONFIG
nop
ori t0, 2
mtc0 t0, CP0_CONFIG
nop
/* copy IRAM section */
la t0, _iramcopy
la t1, _iramstart
la t2, _iramend
_iram_loop:
lw t3, 0(t0)
sw t3, 0(t1)
addiu t1, 4
bne t1, t2, _iram_loop
addiu t0, 4
/* clear bss */
la t0, __bss_start
la t1, __bss_end
_clr_bss_loop:
sw zero, 0(t0)
bne t0, t1, _clr_bss_loop
addiu t0, t0, 4
/* jump to RT-Thread RTOS */
jal rtthread_startup
nop
/* restart, never die */
j _start
nop
.set reorder
.globl cp0_get_cause
cp0_get_cause:
mfc0 v0, CP0_CAUSE
jr ra
nop
.globl cp0_get_status
cp0_get_status:
mfc0 v0, CP0_STATUS
jr ra
nop
.globl cp0_get_hi
cp0_get_hi:
mfhi v0
jr ra
nop
.globl cp0_get_lo
cp0_get_lo:
mflo v0
jr ra
nop
.extern tlb_refill_handler
.extern cache_error_handler
/* Exception Handler */
/* 0x0 - TLB refill handler */
.section .vectors.1, "ax", %progbits
j tlb_refill_handler
nop
/* 0x100 - Cache error handler */
.section .vectors.2, "ax", %progbits
j cache_error_handler
nop
/* 0x180 - Exception/Interrupt handler */
.section .vectors.3, "ax", %progbits
j _general_exception_handler
nop
/* 0x200 - Special Exception Interrupt handler (when IV is set in CP0_CAUSE) */
.section .vectors.4, "ax", %progbits
j _irq_handler
nop
.section .vectors, "ax", %progbits
.extern mips_irq_handle
/* general exception handler */
_general_exception_handler:
.set noreorder
mfc0 k1, CP0_CAUSE
andi k1, k1, 0x7c
srl k1, k1, 2
lw k0, sys_exception_handlers(k1)
jr k0
nop
.set reorder
/* interrupt handler */
_irq_handler:
.set noreorder
la k0, mips_irq_handle
jr k0
nop
.set reorder
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