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qemu/mcu/arm: Implement a SysTick driver.

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Signed-off-by: iabdalkader <i.abdalkader@gmail.com>
This commit is contained in:
iabdalkader
2025-10-11 15:50:37 +02:00
committed by Damien George
parent c04d2d691c
commit e1f063a1fa
4 changed files with 90 additions and 1 deletions
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1
ports/qemu/Makefile
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@@ -77,6 +77,7 @@ LIBS = $(shell $(CC) $(CFLAGS) -print-libgcc-file-name)
SRC_C += \
mcu/arm/errorhandler.c \
mcu/arm/startup.c \
mcu/arm/ticks.c \
shared/runtime/semihosting_arm.c \
endif

2
ports/qemu/mcu/arm/errorhandler.c
View File

@@ -191,7 +191,7 @@ __attribute__((naked)) MP_NORETURN void PendSV_Handler(void) {
exception_handler(PENDING_SV);
}
__attribute__((naked)) MP_NORETURN void SysTick_Handler(void) {
__attribute__((naked, weak)) MP_NORETURN void SysTick_Handler(void) {
exception_handler(SYSTEM_TICK);
}

3
ports/qemu/mcu/arm/startup.c
View File

@@ -118,6 +118,9 @@ const uint32_t isr_vector[] __attribute__((section(".isr_vector"))) = {
void _start(void) {
mp_semihosting_init();
extern void ticks_init(void);
ticks_init();
// Enable the UART
uart_init();

85
ports/qemu/mcu/arm/ticks.c Normal file
View File

@@ -0,0 +1,85 @@
/*
* This file is part of the MicroPython project, http://micropython.org/
*
* The MIT License (MIT)
*
* Copyright (c) 2025 Ibrahim Abdelkader <iabdalkader@openmv.io>
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
*/
#include <stdint.h>
// CPU frequency
#ifndef CPU_FREQ_HZ
#define CPU_FREQ_HZ 25000000u
#endif
// SysTick registers
#define SYSTICK_BASE 0xE000E010
#define SYSTICK_CSR (*(volatile uint32_t *)(SYSTICK_BASE + 0x00))
#define SYSTICK_RVR (*(volatile uint32_t *)(SYSTICK_BASE + 0x04))
#define SYSTICK_CVR (*(volatile uint32_t *)(SYSTICK_BASE + 0x08))
// SysTick config bits
#define SYSTICK_CSR_ENABLE (1 << 0)
#define SYSTICK_CSR_TICKINT (1 << 1)
#define SYSTICK_CSR_CLKSOURCE (1 << 2)
static volatile uint32_t _ticks_ms = 0;
#if defined(__ARM_ARCH_ISA_ARM)
static volatile uint32_t _ticks_us = 0;
#endif
void ticks_init(void) {
#if !defined(__ARM_ARCH_ISA_ARM)
// Configure SysTick: reload at 1ms intervals (Cortex-M)
SYSTICK_CVR = 0;
SYSTICK_RVR = (CPU_FREQ_HZ / 1000) - 1;
SYSTICK_CSR = SYSTICK_CSR_ENABLE | SYSTICK_CSR_TICKINT | SYSTICK_CSR_CLKSOURCE;
#endif
}
uintptr_t ticks_ms(void) {
#if defined(__ARM_ARCH_ISA_ARM)
return _ticks_us++ / 1000;
#else
return _ticks_ms;
#endif
}
uintptr_t ticks_us(void) {
#if defined(__ARM_ARCH_ISA_ARM)
return _ticks_us++;
#else
// Get current values atomically
uint32_t ms = _ticks_ms;
uint32_t cvr = SYSTICK_CVR;
// Calculate microseconds from the down-counter
uint32_t elapsed_cycles = SYSTICK_RVR - cvr;
uint32_t us_fraction = (elapsed_cycles * 1000) / (CPU_FREQ_HZ / 1000);
return (ms * 1000) + us_fraction;
#endif
}
void SysTick_Handler(void) {
_ticks_ms++;
}