/* * Copyright (c) 2006-2022, RT-Thread Development Team * * SPDX-License-Identifier: Apache-2.0 * * 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