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