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circuitpython/ports/atmel-samd/tick.c

133 lines
4.6 KiB

/*
* This file is part of the MicroPython project, http://micropython.org/
*
* The MIT License (MIT)
*
* Copyright (c) 2017 Scott Shawcroft for Adafruit Industries
*
* 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 "tick.h"
#include "peripheral_clk_config.h"
#include "supervisor/shared/autoreload.h"
#include "supervisor/filesystem.h"
#include "shared-bindings/microcontroller/__init__.h"
#include "shared-bindings/microcontroller/Processor.h"
#if CIRCUITPY_GAMEPAD
#include "shared-module/gamepad/__init__.h"
#endif
#if CIRCUITPY_GAMEPADSHIFT
#include "shared-module/gamepadshift/__init__.h"
#endif
// Global millisecond tick count
volatile uint64_t ticks_ms = 0;
void SysTick_Handler(void) {
// SysTick interrupt handler called when the SysTick timer reaches zero
// (every millisecond).
common_hal_mcu_disable_interrupts();
ticks_ms += 1;
// Read the control register to reset the COUNTFLAG.
(void) SysTick->CTRL;
common_hal_mcu_enable_interrupts();
#if CIRCUITPY_FILESYSTEM_FLUSH_INTERVAL_MS > 0
filesystem_tick();
#endif
#ifdef CIRCUITPY_AUTORELOAD_DELAY_MS
autoreload_tick();
#endif
#ifdef CIRCUITPY_GAMEPAD_TICKS
if (!(ticks_ms & CIRCUITPY_GAMEPAD_TICKS)) {
#if CIRCUITPY_GAMEPAD
gamepad_tick();
#endif
#if CIRCUITPY_GAMEPADSHIFT
gamepadshift_tick();
#endif
}
#endif
}
void tick_init() {
uint32_t ticks_per_ms = common_hal_mcu_processor_get_frequency() / 1000;
SysTick_Config(ticks_per_ms-1);
NVIC_EnableIRQ(SysTick_IRQn);
// Set all peripheral interrupt priorities to the lowest priority by default.
for (uint16_t i = 0; i < PERIPH_COUNT_IRQn; i++) {
NVIC_SetPriority(i, (1UL << __NVIC_PRIO_BITS) - 1UL);
}
// Bump up the systick interrupt so nothing else interferes with timekeeping.
NVIC_SetPriority(SysTick_IRQn, 0);
#ifdef SAMD21
NVIC_SetPriority(USB_IRQn, 1);
#endif
#ifdef SAMD51
NVIC_SetPriority(USB_0_IRQn, 1);
NVIC_SetPriority(USB_1_IRQn, 1);
NVIC_SetPriority(USB_2_IRQn, 1);
NVIC_SetPriority(USB_3_IRQn, 1);
#endif
}
void tick_delay(uint32_t us) {
uint32_t ticks_per_us = common_hal_mcu_processor_get_frequency() / 1000 / 1000;
uint32_t us_until_next_tick = SysTick->VAL / ticks_per_us;
uint32_t start_tick;
while (us >= us_until_next_tick) {
start_tick = SysTick->VAL; // wait for SysTick->VAL to RESET
while (SysTick->VAL < start_tick) {}
us -= us_until_next_tick;
us_until_next_tick = 1000;
}
while (SysTick->VAL > ((us_until_next_tick - us) * ticks_per_us)) {}
}
// us counts down!
void current_tick(uint64_t* ms, uint32_t* us_until_ms) {
uint32_t ticks_per_us = common_hal_mcu_processor_get_frequency() / 1000 / 1000;
// We disable interrupts to prevent ticks_ms from changing while we grab it.
common_hal_mcu_disable_interrupts();
uint32_t tick_status = SysTick->CTRL;
uint32_t current_us = SysTick->VAL;
uint32_t tick_status2 = SysTick->CTRL;
uint64_t current_ms = ticks_ms;
// The second clause ensures our value actually rolled over. Its possible it hit zero between
// the VAL read and CTRL read.
if ((tick_status & SysTick_CTRL_COUNTFLAG_Msk) != 0 ||
((tick_status2 & SysTick_CTRL_COUNTFLAG_Msk) != 0 && current_us > ticks_per_us)) {
current_ms++;
}
common_hal_mcu_enable_interrupts();
*ms = current_ms;
*us_until_ms = current_us / ticks_per_us;
}
void wait_until(uint64_t ms, uint32_t us_until_ms) {
uint32_t ticks_per_us = common_hal_mcu_processor_get_frequency() / 1000 / 1000;
while (ticks_ms <= ms && SysTick->VAL / ticks_per_us >= us_until_ms) {}
}