/* * File : start_iar.s * This file is part of RT-Thread RTOS * COPYRIGHT (C) 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 * 2015-04-06 zchong the first version */ MODULE ?cstartup ; -------------------- ; Mode, correspords to bits 0-5 in CPSR MODE_MSK DEFINE 0x1F ; Bit mask for mode bits in CPSR I_Bit DEFINE 0x80 ; when I bit is set, IRQ is disabled F_Bit DEFINE 0x40 ; when F bit is set, FIQ is disabled USR_MODE DEFINE 0x10 ; User mode FIQ_MODE DEFINE 0x11 ; Fast Interrupt Request mode IRQ_MODE DEFINE 0x12 ; Interrupt Request mode SVC_MODE DEFINE 0x13 ; Supervisor mode ABT_MODE DEFINE 0x17 ; Abort mode UND_MODE DEFINE 0x1B ; Undefined Instruction mode SYS_MODE DEFINE 0x1F ; System mode ;; Forward declaration of sections. SECTION IRQ_STACK:DATA:NOROOT(3) SECTION FIQ_STACK:DATA:NOROOT(3) SECTION SVC_STACK:DATA:NOROOT(3) SECTION ABT_STACK:DATA:NOROOT(3) SECTION UND_STACK:DATA:NOROOT(3) SECTION CSTACK:DATA:NOROOT(3) SECTION .text:CODE SECTION .intvec:CODE:NOROOT(5) PUBLIC __vector PUBLIC __iar_program_start __iar_init$$done: ; The vector table is not needed ; until after copy initialization is done __vector: ; Make this a DATA label, so that stack usage ; analysis doesn't consider it an uncalled fun ARM ; All default exception handlers (except reset) are ; defined as weak symbol definitions. ; If a handler is defined by the application it will take precedence. LDR PC,Reset_Addr ; Reset LDR PC,Undefined_Addr ; Undefined instructions LDR PC,SWI_Addr ; Software interrupt (SWI/SVC) LDR PC,Prefetch_Addr ; Prefetch abort LDR PC,Abort_Addr ; Data abort DCD 0 ; RESERVED LDR PC,IRQ_Addr ; IRQ LDR PC,FIQ_Addr ; FIQ DATA Reset_Addr: DCD __iar_program_start Undefined_Addr: DCD Undefined_Handler SWI_Addr: DCD SWI_Handler Prefetch_Addr: DCD Prefetch_Handler Abort_Addr: DCD Abort_Handler IRQ_Addr: DCD IRQ_Handler FIQ_Addr: DCD FIQ_Handler ; -------------------------------------------------- ; ?cstartup -- low-level system initialization code. ; ; After a reset execution starts here, the mode is ARM, supervisor ; with interrupts disabled. ; SECTION .text:CODE:NOROOT(2) EXTERN rt_hw_trap_udef EXTERN rt_hw_trap_swi EXTERN rt_hw_trap_pabt EXTERN rt_hw_trap_dabt EXTERN rt_hw_trap_fiq EXTERN rt_hw_trap_irq EXTERN rt_interrupt_enter EXTERN rt_interrupt_leave EXTERN rt_thread_switch_interrupt_flag EXTERN rt_interrupt_from_thread EXTERN rt_interrupt_to_thread EXTERN rt_current_thread EXTERN vmm_thread EXTERN vmm_virq_check EXTERN __cmain REQUIRE __vector EXTWEAK __iar_init_core EXTWEAK __iar_init_vfp ARM __iar_program_start: ?cstartup: ; ; Add initialization needed before setup of stackpointers here. ; ; ; Initialize the stack pointers. ; The pattern below can be used for any of the exception stacks: ; FIQ, IRQ, SVC, ABT, UND, SYS. ; The USR mode uses the same stack as SYS. ; The stack segments must be defined in the linker command file, ; and be declared above. ; MRS r0, cpsr ; Original PSR value ;; Set up the interrupt stack pointer. BIC r0, r0, #MODE_MSK ; Clear the mode bits ORR r0, r0, #IRQ_MODE ; Set IRQ mode bits MSR cpsr_c, r0 ; Change the mode LDR sp, =SFE(IRQ_STACK) ; End of IRQ_STACK BIC sp,sp,#0x7 ; Make sure SP is 8 aligned ;; Set up the fast interrupt stack pointer. BIC r0, r0, #MODE_MSK ; Clear the mode bits ORR r0, r0, #FIQ_MODE ; Set FIR mode bits MSR cpsr_c, r0 ; Change the mode LDR sp, =SFE(FIQ_STACK) ; End of FIQ_STACK BIC sp,sp,#0x7 ; Make sure SP is 8 aligned BIC r0,r0,#MODE_MSK ; Clear the mode bits ORR r0,r0,#ABT_MODE ; Set Abort mode bits MSR cpsr_c,r0 ; Change the mode LDR sp,=SFE(ABT_STACK) ; End of ABT_STACK BIC sp,sp,#0x7 ; Make sure SP is 8 aligned BIC r0,r0,#MODE_MSK ; Clear the mode bits ORR r0,r0,#UND_MODE ; Set Undefined mode bits MSR cpsr_c,r0 ; Change the mode LDR sp,=SFE(UND_STACK) ; End of UND_STACK BIC sp,sp,#0x7 ; Make sure SP is 8 aligned ;; Set up the normal stack pointer. BIC r0 ,r0, #MODE_MSK ; Clear the mode bits ORR r0 ,r0, #SVC_MODE ; Set System mode bits MSR cpsr_c, r0 ; Change the mode LDR sp, =SFE(SVC_STACK) ; End of SVC_STACK BIC sp,sp,#0x7 ; Make sure SP is 8 aligned ;; Turn on core features assumed to be enabled. BL __iar_init_core ;; Initialize VFP (if needed). BL __iar_init_vfp ;; Continue to __cmain for C-level initialization. B __cmain Undefined_Handler: SUB sp, sp, #72 STMIA sp, {r0 - r12} ;/* Calling r0-r12 */ ADD r8, sp, #60 MRS r1, cpsr MRS r2, spsr ORR r2,r2, #I_Bit | F_Bit MSR cpsr_c, r2 MOV r0, r0 STMDB r8, {sp, lr} ;/* Calling SP, LR */ MSR cpsr_c, r1 ;/* return to Undefined Instruction mode */ 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 LDMIA sp, {r0 - r12} ;/* Calling r0 - r2 */ MOV r0, r0 LDR lr, [sp, #60] ;/* Get PC */ ADD sp, sp, #72 MOVS pc, lr ;/* return & move spsr_svc into cpsr */ SWI_Handler: BL rt_hw_trap_swi Prefetch_Handler: BL rt_hw_trap_pabt Abort_Handler: SUB sp, sp, #72 STMIA sp, {r0 - r12} ;/* Calling r0-r12 */ ADD r8, sp, #60 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 LDMIA sp, {r0 - r12} ;/* Calling r0 - r2 */ MOV r0, r0 LDR lr, [sp, #60] ;/* Get PC */ ADD sp, sp, #72 MOVS pc, lr ;/* return & move spsr_svc into cpsr */ FIQ_Handler: STMFD sp!,{r0-r7,lr} BL rt_hw_trap_fiq LDMFD sp!,{r0-r7,lr} SUBS pc,lr,#4 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 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-r2} ; save r0-r2 MRS r0, spsr ; get cpsr of interrupt thread SUB r1, sp, #4*3 SUB r2, lr, #4 ; save old task's pc to r2 ; switch to SVC mode with no interrupt MSR cpsr_c, #I_Bit | F_Bit | SVC_MODE STMFD sp!, {r2} ; push old task's pc STMFD sp!, {r3-r12,lr}; push old task's lr,r12-r4 LDMFD r1, {r1-r3} ; restore r0-r2 of the interrupt thread STMFD sp!, {r1-r3} ; push old task's r0-r2 STMFD sp!, {r0} ; push old task's cpsr 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 cpsr to spsr MSR spsr_cxsf, r4 LDMFD sp!, {r0-r12,lr,pc}^ ; pop new task's r0-r12,lr & pc, copy spsr to cpsr END