280 lines
6.2 KiB
ArmAsm
280 lines
6.2 KiB
ArmAsm
/*
|
|
* File : start.S
|
|
* This file is part of RT-Thread RTOS
|
|
* COPYRIGHT (C) 2006, RT-Thread Development Team
|
|
*
|
|
* The license and distribution terms for this file may be
|
|
* found in the file LICENSE in this distribution or at
|
|
* http://openlab.rt-thread.com/license/LICENSE
|
|
*
|
|
* Change Logs:
|
|
* Date Author Notes
|
|
* 2006-08-31 Bernard first version
|
|
*/
|
|
|
|
/* Internal Memory Base Addresses */
|
|
.equ FLASH_BASE, 0x00100000
|
|
.equ RAM_BASE, 0x00200000
|
|
|
|
/* Stack Configuration */
|
|
.equ TOP_STACK, 0x00204000
|
|
.equ UND_STACK_SIZE, 0x00000100
|
|
.equ SVC_STACK_SIZE, 0x00000400
|
|
.equ ABT_STACK_SIZE, 0x00000100
|
|
.equ FIQ_STACK_SIZE, 0x00000100
|
|
.equ IRQ_STACK_SIZE, 0x00000100
|
|
.equ USR_STACK_SIZE, 0x00000004
|
|
|
|
/* ARM architecture definitions */
|
|
.equ MODE_USR, 0x10
|
|
.equ MODE_FIQ, 0x11
|
|
.equ MODE_IRQ, 0x12
|
|
.equ MODE_SVC, 0x13
|
|
.equ MODE_ABT, 0x17
|
|
.equ MODE_UND, 0x1B
|
|
.equ MODE_SYS, 0x1F
|
|
|
|
.equ I_BIT, 0x80 /* when this bit is set, IRQ is disabled */
|
|
.equ F_BIT, 0x40 /* when this bit is set, FIQ is disabled */
|
|
|
|
.section .init, "ax"
|
|
.code 32
|
|
.align 0
|
|
.globl _start
|
|
_start:
|
|
b reset
|
|
ldr pc, _vector_undef
|
|
ldr pc, _vector_swi
|
|
ldr pc, _vector_pabt
|
|
ldr pc, _vector_dabt
|
|
nop /* reserved vector */
|
|
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
|
|
|
|
/*
|
|
* 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
|
|
|
|
/* the system entry */
|
|
reset:
|
|
/* disable watchdog */
|
|
ldr r0, =0xFFFFFD40
|
|
ldr r1, =0x00008000
|
|
str r1, [r0, #0x04]
|
|
|
|
/* enable the main oscillator */
|
|
ldr r0, =0xFFFFFC00
|
|
ldr r1, =0x00000601
|
|
str r1, [r0, #0x20]
|
|
|
|
/* wait for main oscillator to stabilize */
|
|
moscs_loop:
|
|
ldr r2, [r0, #0x68]
|
|
ands r2, r2, #1
|
|
beq moscs_loop
|
|
|
|
/* set up the PLL */
|
|
ldr r1, =0x00191C05
|
|
str r1, [r0, #0x2C]
|
|
|
|
/* wait for PLL to lock */
|
|
pll_loop:
|
|
ldr r2, [r0, #0x68]
|
|
ands r2, r2, #0x04
|
|
beq pll_loop
|
|
|
|
/* select clock */
|
|
ldr r1, =0x00000007
|
|
str r1, [r0, #0x30]
|
|
|
|
#ifdef __FLASH_BUILD__
|
|
/* copy exception vectors into internal sram */
|
|
/*
|
|
mov r8, #RAM_BASE
|
|
ldr r9, =_start
|
|
ldmia r9!, {r0-r7}
|
|
stmia r8!, {r0-r7}
|
|
ldmia r9!, {r0-r6}
|
|
stmia r8!, {r0-r6}
|
|
*/
|
|
#endif
|
|
|
|
/* setup stack for each mode */
|
|
ldr r0, =TOP_STACK
|
|
|
|
/* set stack */
|
|
/* undefined instruction mode */
|
|
msr cpsr_c, #MODE_UND|I_BIT|F_BIT
|
|
mov sp, r0
|
|
sub r0, r0, #UND_STACK_SIZE
|
|
|
|
/* abort mode */
|
|
msr cpsr_c, #MODE_ABT|I_BIT|F_BIT
|
|
mov sp, r0
|
|
sub r0, r0, #ABT_STACK_SIZE
|
|
|
|
/* FIQ mode */
|
|
msr cpsr_c, #MODE_FIQ|I_BIT|F_BIT
|
|
mov sp, r0
|
|
sub r0, r0, #FIQ_STACK_SIZE
|
|
|
|
/* IRQ mode */
|
|
msr cpsr_c, #MODE_IRQ|I_BIT|F_BIT
|
|
mov sp, r0
|
|
sub r0, r0, #IRQ_STACK_SIZE
|
|
|
|
/* supervisor mode */
|
|
msr cpsr_c, #MODE_SVC|I_BIT|F_BIT
|
|
mov sp, r0
|
|
|
|
/* remap SRAM to 0x0000 */
|
|
/*
|
|
ldr r0, =0xFFFFFF00
|
|
mov r1, #0x01
|
|
str r1, [r0]
|
|
*/
|
|
|
|
/* mask all IRQs */
|
|
ldr r1, =0xFFFFF124
|
|
ldr r0, =0XFFFFFFFF
|
|
str r0, [r1]
|
|
|
|
/* copy .data to SRAM */
|
|
ldr r1, =_sidata /* .data start in image */
|
|
ldr r2, =_edata /* .data end in image */
|
|
ldr r3, =_sdata /* sram data start */
|
|
data_loop:
|
|
ldr r0, [r1, #0]
|
|
str r0, [r3]
|
|
|
|
add r1, r1, #4
|
|
add r3, r3, #4
|
|
|
|
cmp r3, r2 /* check if data to clear */
|
|
blo data_loop /* loop until done */
|
|
|
|
/* 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
|
|
|
|
/* exception handlers */
|
|
vector_undef: b vector_undef
|
|
vector_swi : b vector_swi
|
|
vector_pabt : b vector_pabt
|
|
vector_dabt : b vector_dabt
|
|
vector_resv : b vector_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
|
|
* rt_hw_context_switch_interrupt_do and don't return
|
|
*/
|
|
ldr r0, =rt_thread_switch_interrupt_flag
|
|
ldr r1, [r0]
|
|
cmp r1, #1
|
|
beq rt_hw_context_switch_interrupt_do
|
|
|
|
ldmfd sp!, {r0-r12,lr}
|
|
subs pc, lr, #4
|
|
|
|
vector_fiq:
|
|
stmfd sp!,{r0-r7,lr}
|
|
bl rt_hw_trap_fiq
|
|
ldmfd sp!,{r0-r7,lr}
|
|
subs pc,lr,#4
|
|
|
|
/*
|
|
* void rt_hw_context_switch_interrupt_do(rt_base_t flag)
|
|
*/
|
|
rt_hw_context_switch_interrupt_do:
|
|
mov r1, #0 @ clear 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, #I_BIT|F_BIT
|
|
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
|