/* * File : start_gcc.S * This file is part of RT-Thread RTOS * COPYRIGHT (C) 2006 - 2015, 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 * 2015-04-15 ArdaFu Split from AT91SAM9260 BSP * 2015-04-21 ArdaFu Remove remap code. Using mmu to map vector table * 2015-06-04 aozima Align stack address to 8 byte. */ #include "rt_low_level_init.h" #define S_FRAME_SIZE (18*4) //72 @#define S_SPSR (17*4) //SPSR @#define S_CPSR (16*4) //CPSR #define S_PC (15*4) //R15 @#define S_LR (14*4) //R14 @#define S_SP (13*4) //R13 @#define S_IP (12*4) //R12 @#define S_FP (11*4) //R11 @#define S_R10 (10*4) @#define S_R9 (9*4) @#define S_R8 (8*4) @#define S_R7 (7*4) @#define S_R6 (6*4) @#define S_R5 (5*4) @#define S_R4 (4*4) @#define S_R3 (3*4) @#define S_R2 (2*4) @#define S_R1 (1*4) @#define S_R0 (0*4) #define MODE_SYS 0x1F #define MODE_FIQ 0x11 #define MODE_IRQ 0x12 #define MODE_SVC 0x13 #define MODE_ABT 0x17 #define MODE_UND 0x1B #define MODEMASK 0x1F #define NOINT 0xC0 @;----------------------- Stack and Heap Definitions --------------------------- .section .nobss, "w" .space UND_STK_SIZE .align 3 .global UND_STACK_START UND_STACK_START: .space ABT_STK_SIZE .align 3 .global ABT_STACK_START ABT_STACK_START: .space FIQ_STK_SIZE .align 3 .global FIQ_STACK_START FIQ_STACK_START: .space IRQ_STK_SIZE .align 3 .global IRQ_STACK_START IRQ_STACK_START: .skip SYS_STK_SIZE .align 3 .global SYS_STACK_START SYS_STACK_START: .space SVC_STK_SIZE .align 3 .global SVC_STACK_START SVC_STACK_START: @;--------------Jump vector table----------------------------------------------- .section .init, "ax" .arm .global start start: LDR PC, vector_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_reset: .word Reset_Handler vector_undef: .word Undef_Handler vector_swi: .word SWI_Handler vector_pabt: .word PAbt_Handler vector_dabt: .word DAbt_Handler vector_resv: .word Resv_Handler vector_irq: .word IRQ_Handler vector_fiq: .word FIQ_Handler .balignl 16,0xdeadbeef @;----------------- Reset Handler --------------------------------------------- .global rt_low_level_init .global main .global Reset_Handler Reset_Handler: @; Set the cpu to SVC32 mode MRS R0, CPSR BIC R0, R0, #MODEMASK ORR R0, R0, #MODE_SVC|NOINT MSR CPSR_cxsf, R0 @; Set CO-Processor @; little-end，disbale I/D Cache MMU, vector table is 0x00000000 MRC P15, 0, R0, C1, C0, 0 @; Read CP15 LDR R1, =0x00003085 @; set clear bits BIC R0, R0, R1 MCR P15, 0, R0, C1, C0, 0 @; Write CP15 @; Call low level init function, @; disable and clear all IRQs, Init MMU, Init interrupt controller, etc. LDR SP, =SVC_STACK_START LDR R0, =rt_low_level_init BLX R0 Setup_Stack: @; Setup Stack for each mode MRS R0, CPSR BIC R0, R0, #MODEMASK ORR R1, R0, #MODE_UND|NOINT MSR CPSR_cxsf, R1 @; Undef mode LDR SP, =UND_STACK_START ORR R1, R0, #MODE_ABT|NOINT MSR CPSR_cxsf, R1 @; Abort mode LDR SP, =ABT_STACK_START ORR R1, R0, #MODE_IRQ|NOINT MSR CPSR_cxsf, R1 @; IRQ mode LDR SP, =IRQ_STACK_START ORR R1, R0, #MODE_FIQ|NOINT MSR CPSR_cxsf, R1 @; FIQ mode LDR SP, =FIQ_STACK_START ORR R1, R0, #MODE_SYS|NOINT MSR CPSR_cxsf,R1 @; SYS/User mode LDR SP, =SYS_STACK_START ORR R1, R0, #MODE_SVC|NOINT MSR CPSR_cxsf, R1 @; SVC mode LDR SP, =SVC_STACK_START @; clear .bss MOV R0, #0 @; get a zero LDR R1, =__bss_start__ @; bss start LDR R2, =__bss_end__ @; bss end bss_clear_loop: CMP R1, R2 @; check if data to clear STRLO R0, [R1], #4 @; clear 4 bytes BLO bss_clear_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: @; Enter the C code LDR R0, =rtthread_startup BLX R0 @;----------------- Exception Handler ----------------------------------------- .global rt_hw_trap_udef .global rt_hw_trap_swi .global rt_hw_trap_pabt .global rt_hw_trap_dabt .global rt_hw_trap_resv .global rt_hw_trap_irq .global rt_hw_trap_fiq .global rt_interrupt_enter .global rt_interrupt_leave .global rt_thread_switch_interrupt_flag .global rt_interrupt_from_thread .global rt_interrupt_to_thread .align 5 Undef_Handler: 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 SPSR MOV R0, SP BL rt_hw_trap_udef .align 5 SWI_Handler: BL rt_hw_trap_swi .align 5 PAbt_Handler: BL rt_hw_trap_pabt .align 5 DAbt_Handler: 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 SPSR MOV R0, SP BL rt_hw_trap_dabt .align 5 Resv_Handler: BL rt_hw_trap_resv .align 5 FIQ_Handler: STMFD SP!, {R0-R7,LR} BL rt_hw_trap_fiq LDMFD SP!, {R0-R7,LR} SUBS PC, LR, #4 .align 5 IRQ_Handler: 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 @;------ 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] @; Save to flag variable LDMFD SP!, {R0-R12,LR} @; Reload saved registers STMFD SP, {R0-R2} @; Save R0-R2 SUB R1, SP, #4*3 @; Save old task's SP to R1 SUB R2, LR, #4 @; Save old task's PC to R2 MRS R0, SPSR @; Get CPSR of interrupt thread MSR CPSR_c, #MODE_SVC|NOINT @; Switch to SVC mode and no interrupt STMFD SP!, {R2} @; Push old task's PC STMFD SP!, {R3-R12,LR} @; Push old task's LR,R12-R3 LDMFD R1, {R1-R3} STMFD SP!, {R1-R3} @; Push old task's R2-R0 STMFD SP!, {R0} @; Push old task's CPSR LDR R4, =rt_interrupt_from_thread LDR R5, [R4] @; R5 = stack ptr in old tasks's TCB STR SP, [R5] @; Store SP in preempted tasks's TCB LDR R6, =rt_interrupt_to_thread LDR R6, [R6] @; R6 = stack ptr in new tasks's TCB LDR SP, [R6] @; Get new task's stack pointer LDMFD SP!, {R4} @; Pop new task's SPSR MSR SPSR_cxsf, R4 LDMFD SP!, {R0-R12,LR,PC}^ @; pop new task's R0-R12,LR & PC SPSR 2 CPSR