/*
* Copyright (c) 2006-2018, RT-Thread Development Team
*
* SPDX-License-Identifier: Apache-2.0
*
* Change Logs:
* Date Author Notes
* 2013-07-05 Bernard the first version
*/
.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 I bit is set, IRQ is disabled
.equ F_Bit, 0x40 @ when F bit is set, FIQ is disabled
.equ UND_Stack_Size, 0x00000000
.equ SVC_Stack_Size, 0x00000000
.equ ABT_Stack_Size, 0x00000000
.equ FIQ_Stack_Size, 0x00000100
.equ IRQ_Stack_Size, 0x00000100
.equ USR_Stack_Size, 0x00000000
#define ISR_Stack_Size (UND_Stack_Size + SVC_Stack_Size + ABT_Stack_Size + \
FIQ_Stack_Size + IRQ_Stack_Size)
/* stack */
.globl stack_start
.globl stack_top
.align 3
.bss
stack_start:
.rept ISR_Stack_Size
.long 0
.endr
stack_top:
.text
/* reset entry */
.globl _reset
_reset:
/* invalidate SCU */
ldr r7, =0xF8F0000C
ldr r6, =0xFFFF
str r6, [r7]
/* disable MMU */
mrc p15, 0, r0, c1, c0, 0 /* read CP15 register 1 */
bic r0, r0, #0x1 /* clear bit 0 */
mcr p15, 0, r0, c1, c0, 0 /* write value back */
/* set the cpu to SVC32 mode and disable interrupt */
mrs r0, cpsr
bic r0, r0, #0x1f
orr r0, r0, #0x13
msr cpsr_c, r0
/* setup stack */
bl stack_setup
/* 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
stack_setup:
ldr r0, =stack_top
@ Set the startup stack for svc
mov sp, r0
@ Enter Undefined Instruction Mode and set its Stack Pointer
msr cpsr_c, #Mode_UND|I_Bit|F_Bit
mov sp, r0
sub r0, r0, #UND_Stack_Size
@ Enter Abort Mode and set its Stack Pointer
msr cpsr_c, #Mode_ABT|I_Bit|F_Bit
mov sp, r0
sub r0, r0, #ABT_Stack_Size
@ Enter FIQ Mode and set its Stack Pointer
msr cpsr_c, #Mode_FIQ|I_Bit|F_Bit
mov sp, r0
sub r0, r0, #FIQ_Stack_Size
@ Enter IRQ Mode and set its Stack Pointer
msr cpsr_c, #Mode_IRQ|I_Bit|F_Bit
mov sp, r0
sub r0, r0, #IRQ_Stack_Size
@ Switch back to SVC
msr cpsr_c, #Mode_SVC|I_Bit|F_Bit
bx lr
.section .text.isr, "ax"
/* exception handlers: undef, swi, padt, dabt, resv, irq, fiq */
.align 5
.globl vector_fiq
vector_fiq:
stmfd sp!,{r0-r7,lr}
bl rt_hw_trap_fiq
ldmfd sp!,{r0-r7,lr}
subs pc,lr,#4
.globl rt_interrupt_enter
.globl rt_interrupt_leave
.globl rt_thread_switch_interrupt_flag
.globl rt_interrupt_from_thread
.globl rt_interrupt_to_thread
.align 5
.globl vector_irq
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
rt_hw_context_switch_interrupt_do:
mov r1, #0 @ clear flag
str r1, [r0]
mov r1, sp @ r1 point to {r0-r3} in stack
add sp, sp, #4*4
ldmfd sp!, {r4-r12,lr}@ reload saved registers
mrs r0, spsr @ get cpsr of interrupt thread
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|Mode_SVC
stmfd sp!, {r2} @ push old task's pc
stmfd sp!, {r4-r12,lr}@ push old task's lr,r12-r4
ldmfd r1, {r1-r4} @ restore r0-r3 of the interrupt thread
stmfd sp!, {r1-r4} @ push old task's r0-r3
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 r7, [r6]
ldr sp, [r7] @ 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
.macro push_svc_reg
sub sp, sp, #17 * 4 @/* Sizeof(struct rt_hw_exp_stack) */
stmia sp, {r0 - r12} @/* Calling r0-r12 */
mov r0, sp
mrs r6, spsr @/* Save CPSR */
str lr, [r0, #15*4] @/* Push PC */
str r6, [r0, #16*4] @/* Push CPSR */
cps #Mode_SVC
str sp, [r0, #13*4] @/* Save calling SP */
str lr, [r0, #14*4] @/* Save calling PC */
.endm
.align 5
.globl vector_swi
vector_swi:
push_svc_reg
bl rt_hw_trap_swi
b .
.align 5
.globl vector_undef
vector_undef:
push_svc_reg
bl rt_hw_trap_undef
b .
.align 5
.globl vector_pabt
vector_pabt:
push_svc_reg
bl rt_hw_trap_pabt
b .
.align 5
.globl vector_dabt
vector_dabt:
push_svc_reg
bl rt_hw_trap_dabt
b .
.align 5
.globl vector_resv
vector_resv:
push_svc_reg
bl rt_hw_trap_resv
b .