/* * 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 * 2008-12-11 XuXinming first version * 2011-03-17 Bernard update to 0.4.x */ #define WDMOD (0xE0000000 + 0x00) #define VICIntEnClr (0xFFFFF000 + 0x014) #define VICVectAddr (0xFFFFF000 + 0xF00) #define VICIntSelect (0xFFFFF000 + 0x00C) #define PLLCFG (0xE01FC000 + 0x084) #define PLLCON (0xE01FC000 + 0x080) #define PLLFEED (0xE01FC000 + 0x08C) #define PLLSTAT (0xE01FC000 + 0x088) #define CCLKCFG (0xE01FC000 + 0x104) #define MEMMAP (0xE01FC000 + 0x040) #define SCS (0xE01FC000 + 0x1A0) #define CLKSRCSEL (0xE01FC000 + 0x10C) #define MAMCR (0xE01FC000 + 0x000) #define MAMTIM (0xE01FC000 + 0x004) /* stack memory */ .section .bss.noinit .equ IRQ_STACK_SIZE, 0x00000200 .equ FIQ_STACK_SIZE, 0x00000100 .equ UDF_STACK_SIZE, 0x00000004 .equ ABT_STACK_SIZE, 0x00000004 .equ SVC_STACK_SIZE, 0x00000200 .space IRQ_STACK_SIZE IRQ_STACK: .space FIQ_STACK_SIZE FIQ_STACK: .space UDF_STACK_SIZE UDF_STACK: .space ABT_STACK_SIZE ABT_STACK: .space SVC_STACK_SIZE SVC_STACK: .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 /* * 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 .text .code 32 /* the system entry */ reset: /* enter svc mode */ msr cpsr_c, #SVCMODE|NOINT /*watch dog disable */ ldr r0,=WDMOD ldr r1,=0x0 str r1,[r0] /* all interrupt disable */ ldr r0,=VICIntEnClr ldr r1,=0xffffffff str r1,[r0] ldr r1, =VICVectAddr ldr r0, =0x00 str r0, [r1] ldr r1, =VICIntSelect ldr r0, =0x00 str r0, [r1] /* setup stack */ bl stack_setup /* 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 .equ USERMODE, 0x10 .equ FIQMODE, 0x11 .equ IRQMODE, 0x12 .equ SVCMODE, 0x13 .equ ABORTMODE, 0x17 .equ UNDEFMODE, 0x1b .equ MODEMASK, 0x1f .equ NOINT, 0xc0 /* exception handlers */ vector_undef: bl rt_hw_trap_udef vector_swi: bl rt_hw_trap_swi vector_pabt: bl rt_hw_trap_pabt vector_dabt: bl rt_hw_trap_dabt 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, =UDF_STACK orr r1,r0,#ABORTMODE|NOINT msr cpsr_cxsf,r1 /* abort mode */ ldr sp, =ABT_STACK orr r1,r0,#IRQMODE|NOINT msr cpsr_cxsf,r1 /* IRQ mode */ ldr sp, =IRQ_STACK orr r1,r0,#FIQMODE|NOINT msr cpsr_cxsf,r1 /* FIQ mode */ ldr sp, =FIQ_STACK bic r0,r0,#MODEMASK orr r1,r0,#SVCMODE|NOINT msr cpsr_cxsf,r1 /* SVC mode */ ldr sp, =SVC_STACK /* USER mode is not initialized. */ mov pc,lr /* The LR register may be not valid for the mode changes.*/