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/*
* File : start.S
* This file is part of RT-Thread RTOS
* COPYRIGHT (C) 2006, RT-Thread Development Team
*
* 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 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.
*
* You should have received a copy of the GNU General Public License along
* with this program; if not, write to the Free Software Foundation, Inc.,
* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
*
* Change Logs:
* Date Author Notes
* 2011-01-13 weety first version
*/
#define CONFIG_STACKSIZE 512
#define S_FRAME_SIZE 72
#define S_OLD_R0 68
#define S_PSR 64
#define S_PC 60
#define S_LR 56
#define S_SP 52
#define S_IP 48
#define S_FP 44
#define S_R10 40
#define S_R9 36
#define S_R8 32
#define S_R7 28
#define S_R6 24
#define S_R5 20
#define S_R4 16
#define S_R3 12
#define S_R2 8
#define S_R1 4
#define S_R0 0
.equ USERMODE, 0x10
.equ FIQMODE, 0x11
.equ IRQMODE, 0x12
.equ SVCMODE, 0x13
.equ ABORTMODE, 0x17
.equ UNDEFMODE, 0x1b
.equ MODEMASK, 0x1f
.equ NOINT, 0xc0
.equ RAM_BASE, 0x00000000 /*Start address of RAM */
.equ ROM_BASE, 0x20000000 /*Start address of Flash */
#define AT91_RSTC_PROCRST (1 << 0) /* Processor Reset */
#define AT91_RSTC_PERRST (1 << 2)
#define AT91_RSTC_KEY (0xa5 << 24)
#define AT91_MATRIX_BASE 0xffffee00
#define AT91_MATRIX_MRCR (AT91_MATRIX_BASE + 0x100) /* Master Remap Control Register */
#define AT91_MATRIX_RCB0 (1 << 0) /* Remap Command for AHB Master 0 (ARM926EJ-S Instruction Master) */
#define AT91_MATRIX_RCB1 (1 << 1) /* Remap Command for AHB Master 1 (ARM926EJ-S Data Master) */
#define AT91_AIC_BASE 0xfffff000
#define AT91_AIC_IDCR 0x124 /* Interrupt Disable Command Register */
#define AT91_AIC_ICCR 0x128 /* Interrupt Clear Command Register */
/*
*************************************************************************
*
* Jump vector table
*
*************************************************************************
*/
.section .init, "ax"
.code 32
.globl _start
_start:
b reset
ldr pc, _vector_undef
ldr pc, _vector_swi
ldr pc, _vector_pabt
ldr pc, _vector_dabt
ldr pc, _vector_resv
ldr pc, _vector_irq
ldr pc, _vector_fiq
_vector_undef: .word vector_undef
_vector_swi: .word vector_swi
_vector_pabt: .word vector_pabt
_vector_dabt: .word vector_dabt
_vector_resv: .word vector_resv
_vector_irq: .word vector_irq
_vector_fiq: .word vector_fiq
.balignl 16,0xdeadbeef
/*
*************************************************************************
*
* Startup Code (reset vector)
* relocate armboot to ram
* setup stack
* jump to second stage
*
*************************************************************************
*/
_TEXT_BASE:
.word TEXT_BASE
/*
* rtthread kernel start and end
* which are defined in linker script
*/
.globl _rtthread_start
_rtthread_start:
.word _start
.globl _rtthread_end
_rtthread_end:
.word _end
/*
* rtthread bss start and end which are defined in linker script
*/
.globl _bss_start
_bss_start:
.word __bss_start
.globl _bss_end
_bss_end:
.word __bss_end
/* IRQ stack memory (calculated at run-time) */
.globl IRQ_STACK_START
IRQ_STACK_START:
.word _irq_stack_start + 1024
.globl FIQ_STACK_START
FIQ_STACK_START:
.word _fiq_stack_start + 1024
.globl UNDEFINED_STACK_START
UNDEFINED_STACK_START:
.word _undefined_stack_start + CONFIG_STACKSIZE
.globl ABORT_STACK_START
ABORT_STACK_START:
.word _abort_stack_start + CONFIG_STACKSIZE
.globl _STACK_START
_STACK_START:
.word _svc_stack_start + 4096
/* ----------------------------------entry------------------------------*/
reset:
/* set the cpu to SVC32 mode */
mrs r0,cpsr
bic r0,r0,#MODEMASK
orr r0,r0,#SVCMODE
msr cpsr,r0
/* mask all IRQs by clearing all bits in the INTMRs */
ldr r1, =AT91_AIC_BASE
ldr r0, =0xffffffff
str r0, [r1, #AT91_AIC_IDCR]
str r0, [r1, #AT91_AIC_ICCR]
/*remap internal ram to 0x00000000 address*/
ldr r0, =AT91_MATRIX_MRCR
ldr r1, =(AT91_MATRIX_RCB0|AT91_MATRIX_RCB1)
str r1, [r0]
/* set interrupt vector */
ldr r0, _TEXT_BASE
mov r1, #0x00
add r2, r0, #0x40 /* size, 32bytes */
copy_loop:
ldmia r0!, {r3-r10} /* copy from source address [r0] */
stmia r1!, {r3-r10} /* copy to target address [r1] */
cmp r0, r2 /* until source end addreee [r2] */
ble copy_loop
/* setup stack */
bl stack_setup
/* clear .bss */
mov r0,#0 /* get a zero */
ldr r1,=__bss_start /* bss start */
ldr r2,=__bss_end /* bss end */
bss_loop:
cmp r1,r2 /* check if data to clear */
strlo r0,[r1],#4 /* clear 4 bytes */
blo bss_loop /* loop until done */
/* call C++ constructors of global objects */
ldr r0, =__ctors_start__
ldr r1, =__ctors_end__
ctor_loop:
cmp r0, r1
beq ctor_end
ldr r2, [r0], #4
stmfd sp!, {r0-r1}
mov lr, pc
bx r2
ldmfd sp!, {r0-r1}
b ctor_loop
ctor_end:
/* start RT-Thread Kernel */
ldr pc, _rtthread_startup
_rtthread_startup:
.word rtthread_startup
#if defined (__FLASH_BUILD__)
_load_address:
.word ROM_BASE + _TEXT_BASE
#else
_load_address:
.word RAM_BASE + _TEXT_BASE
#endif
.global cpu_reset
cpu_reset:
ldr r0, =0xfffffd00
ldr r1, =(AT91_RSTC_KEY | AT91_RSTC_PROCRST | AT91_RSTC_PERRST)
str r1, [r0]
mov pc, lr
/*
*************************************************************************
*
* Interrupt handling
*
*************************************************************************
*/
/* exception handlers */
.align 5
vector_undef:
sub sp, sp, #S_FRAME_SIZE
stmia sp, {r0 - r12} /* Calling r0-r12 */
add r8, sp, #S_PC
stmdb r8, {sp, lr}^ /* Calling SP, LR */
str lr, [r8, #0] /* Save calling PC */
mrs r6, spsr
str r6, [r8, #4] /* Save CPSR */
str r0, [r8, #8] /* Save OLD_R0 */
mov r0, sp
bl rt_hw_trap_udef
.align 5
vector_swi:
bl rt_hw_trap_swi
.align 5
vector_pabt:
bl rt_hw_trap_pabt
.align 5
vector_dabt:
sub sp, sp, #S_FRAME_SIZE
stmia sp, {r0 - r12} /* Calling r0-r12 */
add r8, sp, #S_PC
stmdb r8, {sp, lr}^ /* Calling SP, LR */
str lr, [r8, #0] /* Save calling PC */
mrs r6, spsr
str r6, [r8, #4] /* Save CPSR */
str r0, [r8, #8] /* Save OLD_R0 */
mov r0, sp
bl rt_hw_trap_dabt
.align 5
vector_resv:
bl rt_hw_trap_resv
.globl rt_interrupt_enter
.globl rt_interrupt_leave
.globl rt_thread_switch_interrupt_flag
.globl rt_interrupt_from_thread
.globl rt_interrupt_to_thread
vector_irq:
stmfd sp!, {r0-r12,lr}
bl rt_interrupt_enter
bl rt_hw_trap_irq
bl rt_interrupt_leave
/* if rt_thread_switch_interrupt_flag set, jump to _interrupt_thread_switch and don't return */
ldr r0, =rt_thread_switch_interrupt_flag
ldr r1, [r0]
cmp r1, #1
beq _interrupt_thread_switch
ldmfd sp!, {r0-r12,lr}
subs pc, lr, #4
.align 5
vector_fiq:
stmfd sp!,{r0-r7,lr}
bl rt_hw_trap_fiq
ldmfd sp!,{r0-r7,lr}
subs pc,lr,#4
_interrupt_thread_switch:
mov r1, #0 /* clear rt_thread_switch_interrupt_flag*/
str r1, [r0]
ldmfd sp!, {r0-r12,lr} /* reload saved registers */
stmfd sp!, {r0-r3} /* save r0-r3 */
mov r1, sp
add sp, sp, #16 /* restore sp */
sub r2, lr, #4 /* save old task's pc to r2 */
mrs r3, spsr /* disable interrupt */
orr r0, r3, #NOINT
msr spsr_c, r0
ldr r0, =.+8 /* switch to interrupted task's stack*/
movs pc, r0
stmfd sp!, {r2} /* push old task's pc */
stmfd sp!, {r4-r12,lr} /* push old task's lr,r12-r4 */
mov r4, r1 /* Special optimised code below */
mov r5, r3
ldmfd r4!, {r0-r3}
stmfd sp!, {r0-r3} /* push old task's r3-r0 */
stmfd sp!, {r5} /* push old task's psr */
mrs r4, spsr
stmfd sp!, {r4} /* push old task's spsr */
ldr r4, =rt_interrupt_from_thread
ldr r5, [r4]
str sp, [r5] /* store sp in preempted tasks's TCB*/
ldr r6, =rt_interrupt_to_thread
ldr r6, [r6]
ldr sp, [r6] /* get new task's stack pointer */
ldmfd sp!, {r4} /* pop new task's spsr */
msr SPSR_cxsf, r4
ldmfd sp!, {r4} /* pop new task's psr */
msr CPSR_cxsf, r4
ldmfd sp!, {r0-r12,lr,pc} /* pop new task's r0-r12,lr & pc */
stack_setup:
mrs r0, cpsr
bic r0, r0, #MODEMASK
orr r1, r0, #UNDEFMODE|NOINT
msr cpsr_cxsf, r1 /* undef mode */
ldr sp, UNDEFINED_STACK_START
orr r1,r0,#ABORTMODE|NOINT
msr cpsr_cxsf,r1 /* abort mode */
ldr sp, ABORT_STACK_START
orr r1,r0,#IRQMODE|NOINT
msr cpsr_cxsf,r1 /* IRQ mode */
ldr sp, IRQ_STACK_START
orr r1,r0,#FIQMODE|NOINT
msr cpsr_cxsf,r1 /* FIQ mode */
ldr sp, FIQ_STACK_START
bic r0,r0,#MODEMASK
orr r1,r0,#SVCMODE|NOINT
msr cpsr_cxsf,r1 /* SVC mode */
ldr sp, _STACK_START
/* USER mode is not initialized. */
mov pc,lr /* The LR register may be not valid for the mode changes.*/
/*/*}*/
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