rt-thread/libcpu/mips/loongson/start_gcc.S

/*
 * 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 "soc3210.h"

    .section ".start", "ax"
    .set noreorder

    /* the program entry */
    .globl  _start
_start:
    .set    noreorder
    la      ra, _start

	/* disable interrupt */
	mfc0	t0, CP0_STATUS
	and 	t0, 0xfffffffe	# By default it will be disabled.
	mtc0	t0, CP0_STATUS	# Set CPU to disable interrupt.
	nop

	/* disable cache */
	mfc0	t0, CP0_CONFIG
	and		t0, 0xfffffff8
	or		t0, 0x2			# disable,!default value is not it!
	mtc0	t0, CP0_CONFIG	# Set CPU to disable cache.
	nop

    /* setup stack pointer */
    li      sp, SYSTEM_STACK
    la      gp, _gp

#if 0
    /* 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
#endif

    /* 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
	.global tlb_refill_exception
	.type	tlb_refill_exception,@function
tlb_refill_exception:
    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
	.global general_exception
	.type	general_exception,@function
general_exception:
    j      _general_exception_handler
    nop
    
	/* 0x200 - Special Exception Interrupt handler (when IV is set in CP0_CAUSE) */
    .section .vectors.4, "ax", %progbits
	.global irq_exception
	.type	irq_exception,@function
irq_exception:
    j      _irq_handler
    nop
	
    .section .vectors, "ax", %progbits
	.extern mips_irq_handle

    /* general exception handler */
_general_exception_handler:
    .set    noreorder
    la      k0, mips_irq_handle
    jr      k0
    nop
    .set    reorder

    /* interrupt handler */
_irq_handler:
    .set    noreorder
    la      k0, mips_irq_handle
    jr      k0
    nop
    .set    reorder