;/* ; * Copyright (c) 2006-2018, RT-Thread Development Team ; * ; * SPDX-License-Identifier: Apache-2.0 ; * ; * Change Logs: ; * Date Author Notes ; * 2009-01-17 Bernard first version ; * 2009-09-27 Bernard add protect when contex switch occurs ; * 2012-01-01 aozima support context switch load/store FPU register. ; * 2013-06-18 aozima add restore MSP feature. ; * 2013-06-23 aozima support lazy stack optimized. ; * 2018-07-24 aozima enhancement hard fault exception handler. ; */ ;/** ; * @addtogroup cortex-m4 ; */ ;/*@{*/ SCB_VTOR EQU 0xE000ED08 ; Vector Table Offset Register NVIC_INT_CTRL EQU 0xE000ED04 ; interrupt control state register NVIC_SYSPRI2 EQU 0xE000ED20 ; system priority register (2) NVIC_PENDSV_PRI EQU 0xFFFF0000 ; PendSV and SysTick priority value (lowest) NVIC_PENDSVSET EQU 0x10000000 ; value to trigger PendSV exception SECTION .text:CODE(2) THUMB REQUIRE8 PRESERVE8 IMPORT rt_thread_switch_interrupt_flag IMPORT rt_interrupt_from_thread IMPORT rt_interrupt_to_thread ;/* ; * rt_base_t rt_hw_interrupt_disable(); ; */ EXPORT rt_hw_interrupt_disable rt_hw_interrupt_disable: MRS r0, PRIMASK CPSID I BX LR ;/* ; * void rt_hw_interrupt_enable(rt_base_t level); ; */ EXPORT rt_hw_interrupt_enable rt_hw_interrupt_enable: MSR PRIMASK, r0 BX LR ;/* ; * void rt_hw_context_switch(rt_uint32 from, rt_uint32 to); ; * r0 --> from ; * r1 --> to ; */ EXPORT rt_hw_context_switch_interrupt EXPORT rt_hw_context_switch rt_hw_context_switch_interrupt: rt_hw_context_switch: ; set rt_thread_switch_interrupt_flag to 1 LDR r2, =rt_thread_switch_interrupt_flag LDR r3, [r2] CMP r3, #1 BEQ _reswitch MOV r3, #1 STR r3, [r2] LDR r2, =rt_interrupt_from_thread ; set rt_interrupt_from_thread STR r0, [r2] _reswitch LDR r2, =rt_interrupt_to_thread ; set rt_interrupt_to_thread STR r1, [r2] LDR r0, =NVIC_INT_CTRL ; trigger the PendSV exception (causes context switch) LDR r1, =NVIC_PENDSVSET STR r1, [r0] BX LR ; r0 --> switch from thread stack ; r1 --> switch to thread stack ; psr, pc, lr, r12, r3, r2, r1, r0 are pushed into [from] stack EXPORT PendSV_Handler PendSV_Handler: ; disable interrupt to protect context switch MRS r2, PRIMASK CPSID I ; get rt_thread_switch_interrupt_flag LDR r0, =rt_thread_switch_interrupt_flag LDR r1, [r0] CBZ r1, pendsv_exit ; pendsv already handled ; clear rt_thread_switch_interrupt_flag to 0 MOV r1, #0x00 STR r1, [r0] LDR r0, =rt_interrupt_from_thread LDR r1, [r0] CBZ r1, switch_to_thread ; skip register save at the first time MRS r1, psp ; get from thread stack pointer #if defined ( __ARMVFP__ ) TST lr, #0x10 ; if(!EXC_RETURN[4]) BNE skip_push_fpu VSTMDB r1!, {d8 - d15} ; push FPU register s16~s31 skip_push_fpu #endif STMFD r1!, {r4 - r11} ; push r4 - r11 register #if defined ( __ARMVFP__ ) MOV r4, #0x00 ; flag = 0 TST lr, #0x10 ; if(!EXC_RETURN[4]) BNE push_flag MOV r4, #0x01 ; flag = 1 push_flag ;STMFD r1!, {r4} ; push flag SUB r1, r1, #0x04 STR r4, [r1] #endif LDR r0, [r0] STR r1, [r0] ; update from thread stack pointer switch_to_thread LDR r1, =rt_interrupt_to_thread LDR r1, [r1] LDR r1, [r1] ; load thread stack pointer #if defined ( __ARMVFP__ ) LDMFD r1!, {r3} ; pop flag #endif LDMFD r1!, {r4 - r11} ; pop r4 - r11 register #if defined ( __ARMVFP__ ) CBZ r3, skip_pop_fpu VLDMIA r1!, {d8 - d15} ; pop FPU register s16~s31 skip_pop_fpu #endif MSR psp, r1 ; update stack pointer #if defined ( __ARMVFP__ ) ORR lr, lr, #0x10 ; lr |= (1 << 4), clean FPCA. CBZ r3, return_without_fpu ; if(flag_r3 != 0) BIC lr, lr, #0x10 ; lr &= ~(1 << 4), set FPCA. return_without_fpu #endif pendsv_exit ; restore interrupt MSR PRIMASK, r2 ORR lr, lr, #0x04 BX lr ;/* ; * void rt_hw_context_switch_to(rt_uint32 to); ; * r0 --> to ; */ EXPORT rt_hw_context_switch_to rt_hw_context_switch_to: LDR r1, =rt_interrupt_to_thread STR r0, [r1] #if defined ( __ARMVFP__ ) ; CLEAR CONTROL.FPCA MRS r2, CONTROL ; read BIC r2, r2, #0x04 ; modify MSR CONTROL, r2 ; write-back #endif ; set from thread to 0 LDR r1, =rt_interrupt_from_thread MOV r0, #0x0 STR r0, [r1] ; set interrupt flag to 1 LDR r1, =rt_thread_switch_interrupt_flag MOV r0, #1 STR r0, [r1] ; set the PendSV and SysTick exception priority LDR r0, =NVIC_SYSPRI2 LDR r1, =NVIC_PENDSV_PRI LDR.W r2, [r0,#0x00] ; read ORR r1,r1,r2 ; modify STR r1, [r0] ; write-back LDR r0, =NVIC_INT_CTRL ; trigger the PendSV exception (causes context switch) LDR r1, =NVIC_PENDSVSET STR r1, [r0] ; restore MSP LDR r0, =SCB_VTOR LDR r0, [r0] LDR r0, [r0] NOP MSR msp, r0 ; enable interrupts at processor level CPSIE F CPSIE I ; ensure PendSV exception taken place before subsequent operation DSB ISB ; never reach here! ; compatible with old version EXPORT rt_hw_interrupt_thread_switch rt_hw_interrupt_thread_switch: BX lr IMPORT rt_hw_hard_fault_exception EXPORT HardFault_Handler HardFault_Handler: ; get current context MRS r0, msp ; get fault context from handler. TST lr, #0x04 ; if(!EXC_RETURN[2]) BEQ _get_sp_done MRS r0, psp ; get fault context from thread. _get_sp_done STMFD r0!, {r4 - r11} ; push r4 - r11 register ;STMFD r0!, {lr} ; push exec_return register #if defined ( __ARMVFP__ ) SUB r0, r0, #0x04 ; push dummy for flag STR lr, [r0] #endif SUB r0, r0, #0x04 STR lr, [r0] TST lr, #0x04 ; if(!EXC_RETURN[2]) BEQ _update_msp MSR psp, r0 ; update stack pointer to PSP. B _update_done _update_msp MSR msp, r0 ; update stack pointer to MSP. _update_done PUSH {lr} BL rt_hw_hard_fault_exception POP {lr} ORR lr, lr, #0x04 BX lr END