trezor-firmware/embed/trezorhal/systick.c

/*
 * This file is part of the TREZOR project, https://trezor.io/
 *
 * Copyright (c) SatoshiLabs
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */

/*
 * This file is part of the MicroPython project, http://micropython.org/
 *
 * The MIT License (MIT)
 *
 * Copyright (c) 2013, 2014 Damien P. George
 *
 * 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 "py/runtime.h"
#include "py/mphal.h"
#include "irq.h"
#include "systick.h"
#include "pybthread.h"

extern __IO uint32_t uwTick;

// We provide our own version of HAL_Delay that calls __WFI while waiting,
// and works when interrupts are disabled.  This function is intended to be
// used only by the ST HAL functions.
void HAL_Delay(uint32_t Delay) {
    if (query_irq() == IRQ_STATE_ENABLED) {
        // IRQs enabled, so can use systick counter to do the delay
        uint32_t start = uwTick;
        // Wraparound of tick is taken care of by 2's complement arithmetic.
        while (uwTick - start < Delay) {
            // Enter sleep mode, waiting for (at least) the SysTick interrupt.
            __WFI();
        }
    } else {
        // IRQs disabled, use mp_hal_delay_ms routine.
        mp_hal_delay_ms(Delay);
    }
}

// Core delay function that does an efficient sleep and may switch thread context.
// If IRQs are enabled then we must have the GIL.
void mp_hal_delay_ms(mp_uint_t Delay) {
    if (query_irq() == IRQ_STATE_ENABLED) {
        // IRQs enabled, so can use systick counter to do the delay
        uint32_t start = uwTick;
        // Wraparound of tick is taken care of by 2's complement arithmetic.
        while (uwTick - start < Delay) {
            // This macro will execute the necessary idle behaviour.  It may
            // raise an exception, switch threads or enter sleep mode (waiting for
            // (at least) the SysTick interrupt).
            MICROPY_EVENT_POLL_HOOK
        }
    } else {
        // IRQs disabled, so need to use a busy loop for the delay.
        // To prevent possible overflow of the counter we use a double loop.
        const uint32_t count_1ms = HAL_RCC_GetSysClockFreq() / 4000;
        for (int i = 0; i < Delay; i++) {
            for (uint32_t count = 0; ++count <= count_1ms;) {
            }
        }
    }
}

// delay for given number of microseconds
void mp_hal_delay_us(mp_uint_t usec) {
    if (query_irq() == IRQ_STATE_ENABLED) {
        // IRQs enabled, so can use systick counter to do the delay
        uint32_t start = mp_hal_ticks_us();
        while (mp_hal_ticks_us() - start < usec) {
        }
    } else {
        // IRQs disabled, so need to use a busy loop for the delay
        // sys freq is always a multiple of 2MHz, so division here won't lose precision
        const uint32_t ucount = HAL_RCC_GetSysClockFreq() / 2000000 * usec / 2;
        for (uint32_t count = 0; ++count <= ucount;) {
        }
    }
}

mp_uint_t mp_hal_ticks_ms(void) {
    return uwTick;
}

mp_uint_t mp_hal_ticks_us(void) {
    return uwTick * 1000;
}