port_cmsis_systick.c

/*
 * FreeRTOS Kernel V10.0.0
 * Copyright (C) 2017 Amazon.com, Inc. or its affiliates.  All Rights Reserved.
 *
 * 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. If you wish to use our Amazon
 * FreeRTOS name, please do so in a fair use way that does not cause confusion.
 *
 * 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.
 *
 * http://www.FreeRTOS.org
 * http://aws.amazon.com/freertos
 *
 * 1 tab == 4 spaces!
 */

/* Scheduler includes. */
#include "FreeRTOS.h"
#include "task.h"
#include "app_util.h"

#ifdef SOFTDEVICE_PRESENT
#include "nrf_soc.h"
#include "nrf_sdh.h"
#include "app_error.h"
#include "app_util_platform.h"
#endif

/*-----------------------------------------------------------
 * Implementation of functions defined in portable.h for the ARM CM4F port.
 * CMSIS compatible layer to menage SysTick ticking source.
 *----------------------------------------------------------*/

#if configTICK_SOURCE == FREERTOS_USE_SYSTICK


#ifndef configSYSTICK_CLOCK_HZ
    #define configSYSTICK_CLOCK_HZ configCPU_CLOCK_HZ
    /* Ensure the SysTick is clocked at the same frequency as the core. */
    #define portNVIC_SYSTICK_CLK_BIT    ( SysTick_CTRL_CLKSOURCE_Msk )
#else
    /* The way the SysTick is clocked is not modified in case it is not the same
    as the core. */
    #define portNVIC_SYSTICK_CLK_BIT    ( 0 )
#endif


#if configUSE_TICKLESS_IDLE == 1
    #error SysTick port for RF52 does not support tickless idle. Use RTC mode instead.
#endif /* configUSE_TICKLESS_IDLE */

/*-----------------------------------------------------------*/

void xPortSysTickHandler( void )
{
    /* The SysTick runs at the lowest interrupt priority, so when this interrupt
    executes all interrupts must be unmasked.  There is therefore no need to
    save and then restore the interrupt mask value as its value is already
    known. */
    ( void ) portSET_INTERRUPT_MASK_FROM_ISR();
    {
        /* Increment the RTOS tick. */
        if ( xTaskIncrementTick() != pdFALSE )
        {
            /* A context switch is required.  Context switching is performed in
            the PendSV interrupt.  Pend the PendSV interrupt. */
            SCB->ICSR = SCB_ICSR_PENDSVSET_Msk;
            __SEV();
        }
    }
    portCLEAR_INTERRUPT_MASK_FROM_ISR( 0 );
}

/*-----------------------------------------------------------*/

/*
 * Setup the systick timer to generate the tick interrupts at the required
 * frequency.
 */
void vPortSetupTimerInterrupt( void )
{
    /* Set interrupt priority */
    NVIC_SetPriority(SysTick_IRQn, configKERNEL_INTERRUPT_PRIORITY);
    /* Configure SysTick to interrupt at the requested rate. */
    SysTick->LOAD = ROUNDED_DIV(configSYSTICK_CLOCK_HZ, configTICK_RATE_HZ) - 1UL;
    SysTick->CTRL = ( portNVIC_SYSTICK_CLK_BIT | SysTick_CTRL_TICKINT_Msk | SysTick_CTRL_ENABLE_Msk );
}

/*-----------------------------------------------------------*/

#elif configTICK_SOURCE == FREERTOS_USE_RTC

#if configUSE_16_BIT_TICKS == 1
#error This port does not support 16 bit ticks.
#endif

#include "nrf_rtc.h"
#include "nrf_drv_clock.h"

/*-----------------------------------------------------------*/

void xPortSysTickHandler( void )
{
#if configUSE_TICKLESS_IDLE == 1
    nrf_rtc_event_clear(portNRF_RTC_REG, NRF_RTC_EVENT_COMPARE_0);
#endif

    BaseType_t switch_req = pdFALSE;
    uint32_t isrstate = portSET_INTERRUPT_MASK_FROM_ISR();

    uint32_t systick_counter = nrf_rtc_counter_get(portNRF_RTC_REG);
    nrf_rtc_event_clear(portNRF_RTC_REG, NRF_RTC_EVENT_TICK);

    if (configUSE_DISABLE_TICK_AUTO_CORRECTION_DEBUG == 0)
    {
        /* check FreeRTOSConfig.h file for more details on configUSE_DISABLE_TICK_AUTO_CORRECTION_DEBUG */
        TickType_t diff;
        diff = (systick_counter - xTaskGetTickCount()) & portNRF_RTC_MAXTICKS;

        /* At most 1 step if scheduler is suspended - the xTaskIncrementTick
         * would return the tick state from the moment when suspend function was called. */
        if ((diff > 1) && (xTaskGetSchedulerState() != taskSCHEDULER_RUNNING))
        {
            diff = 1;
        }
        while ((diff--) > 0)
        {
            switch_req |= xTaskIncrementTick();
        }
    }
    else
    {
        switch_req = xTaskIncrementTick();
    }

    /* Increment the RTOS tick as usual which checks if there is a need for rescheduling */
    if ( switch_req != pdFALSE )
    {
        /* A context switch is required.  Context switching is performed in
        the PendSV interrupt.  Pend the PendSV interrupt. */
        SCB->ICSR = SCB_ICSR_PENDSVSET_Msk;
        __SEV();
    }

    portCLEAR_INTERRUPT_MASK_FROM_ISR( isrstate );
}

/*
 * Setup the RTC time to generate the tick interrupts at the required
 * frequency.
 */
void vPortSetupTimerInterrupt( void )
{
    /* Request LF clock */
    nrf_drv_clock_lfclk_request(NULL);

    /* Configure SysTick to interrupt at the requested rate. */
    nrf_rtc_prescaler_set(portNRF_RTC_REG, portNRF_RTC_PRESCALER);
    nrf_rtc_int_enable   (portNRF_RTC_REG, RTC_INTENSET_TICK_Msk);
    nrf_rtc_task_trigger (portNRF_RTC_REG, NRF_RTC_TASK_CLEAR);
    nrf_rtc_task_trigger (portNRF_RTC_REG, NRF_RTC_TASK_START);
    nrf_rtc_event_enable(portNRF_RTC_REG, RTC_EVTEN_OVRFLW_Msk);

    NVIC_SetPriority(portNRF_RTC_IRQn, configKERNEL_INTERRUPT_PRIORITY);
    NVIC_EnableIRQ(portNRF_RTC_IRQn);
}

#if configUSE_TICKLESS_IDLE == 1
void vPortSuppressTicksAndSleep( TickType_t xExpectedIdleTime )
{
    /*
     * Implementation note:
     *
     * To help debugging the option configUSE_TICKLESS_IDLE_SIMPLE_DEBUG was presented.
     * This option would make sure that even if program execution was stopped inside
     * this function no more than expected number of ticks would be skipped.
     *
     * Normally RTC works all the time even if firmware execution was stopped
     * and that may lead to skipping too much of ticks.
     */
    TickType_t enterTime;

    /* Make sure the SysTick reload value does not overflow the counter. */
    if ( xExpectedIdleTime > portNRF_RTC_MAXTICKS - configEXPECTED_IDLE_TIME_BEFORE_SLEEP )
    {
        xExpectedIdleTime = portNRF_RTC_MAXTICKS - configEXPECTED_IDLE_TIME_BEFORE_SLEEP;
    }
    /* Block all the interrupts globally */
#ifdef SOFTDEVICE_PRESENT
    do{
        uint8_t dummy = 0;
        uint32_t err_code = sd_nvic_critical_region_enter(&dummy);
        APP_ERROR_CHECK(err_code);
    }while (0);
#else
    __disable_irq();
#endif

    enterTime = nrf_rtc_counter_get(portNRF_RTC_REG);

    if ( eTaskConfirmSleepModeStatus() != eAbortSleep )
    {
        TickType_t xModifiableIdleTime;
        TickType_t wakeupTime = (enterTime + xExpectedIdleTime) & portNRF_RTC_MAXTICKS;

        /* Stop tick events */
        nrf_rtc_int_disable(portNRF_RTC_REG, NRF_RTC_INT_TICK_MASK);

        /* Configure CTC interrupt */
        nrf_rtc_cc_set(portNRF_RTC_REG, 0, wakeupTime);
        nrf_rtc_event_clear(portNRF_RTC_REG, NRF_RTC_EVENT_COMPARE_0);
        nrf_rtc_int_enable(portNRF_RTC_REG, NRF_RTC_INT_COMPARE0_MASK);

        __DSB();

        /* Sleep until something happens.  configPRE_SLEEP_PROCESSING() can
         * set its parameter to 0 to indicate that its implementation contains
         * its own wait for interrupt or wait for event instruction, and so wfi
         * should not be executed again.  However, the original expected idle
         * time variable must remain unmodified, so a copy is taken. */
        xModifiableIdleTime = xExpectedIdleTime;
        configPRE_SLEEP_PROCESSING( xModifiableIdleTime );
        if ( xModifiableIdleTime > 0 )
        {
#ifdef SOFTDEVICE_PRESENT
            if (nrf_sdh_is_enabled())
            {
                // Fix ERRATA 87 (https://infocenter.nordicsemi.com/index.jsp?topic=%252Fcom.nordic.infocenter.sdk5.v11.0.0%252Findex.html&cp=4_0_0)
                // Clear FPU interrupt before going to sleep. This prevent unexpected wake-up.
                #define FPU_EXCEPTION_MASK 0x0000009F
                /* Clear exceptions and PendingIRQ from the FPU unit */
                __set_FPSCR(__get_FPSCR()  & ~(FPU_EXCEPTION_MASK));
                (void) __get_FPSCR();
                NVIC_ClearPendingIRQ(FPU_IRQn);

                uint32_t err_code = sd_app_evt_wait();
                APP_ERROR_CHECK(err_code);
            }
            else
#endif
            {
                // Fix ERRATA 87 (https://infocenter.nordicsemi.com/index.jsp?topic=%252Fcom.nordic.infocenter.sdk5.v11.0.0%252Findex.html&cp=4_0_0)
                // Clear FPU interrupt before going to sleep. This prevent unexpected wake-up.
                #define FPU_EXCEPTION_MASK 0x0000009F
                /* Clear exceptions and PendingIRQ from the FPU unit */
                __set_FPSCR(__get_FPSCR()  & ~(FPU_EXCEPTION_MASK));
                (void) __get_FPSCR();
                NVIC_ClearPendingIRQ(FPU_IRQn);

                /* No SD -  we would just block interrupts globally.
                * BASEPRI cannot be used for that because it would prevent WFE from wake up.
                */
                do{
                    __WFE();
                } while (0 == (NVIC->ISPR[0] | NVIC->ISPR[1]));
            }
        }
        configPOST_SLEEP_PROCESSING( xExpectedIdleTime );

        nrf_rtc_int_disable(portNRF_RTC_REG, NRF_RTC_INT_COMPARE0_MASK);
        nrf_rtc_event_clear(portNRF_RTC_REG, NRF_RTC_EVENT_COMPARE_0);

        /* Correct the system ticks */
        {
            TickType_t diff;
            TickType_t exitTime;

            nrf_rtc_event_clear(portNRF_RTC_REG, NRF_RTC_EVENT_TICK);
            nrf_rtc_int_enable (portNRF_RTC_REG, NRF_RTC_INT_TICK_MASK);

            exitTime = nrf_rtc_counter_get(portNRF_RTC_REG);
            diff =  (exitTime - enterTime) & portNRF_RTC_MAXTICKS;

            /* It is important that we clear pending here so that our corrections are latest and in sync with tick_interrupt handler */
            NVIC_ClearPendingIRQ(portNRF_RTC_IRQn);

            if ((configUSE_TICKLESS_IDLE_SIMPLE_DEBUG) && (diff > xExpectedIdleTime))
            {
                diff = xExpectedIdleTime;
            }

            if (diff > 0)
            {
                vTaskStepTick(diff);
            }
        }
    }
#ifdef SOFTDEVICE_PRESENT
    uint32_t err_code = sd_nvic_critical_region_exit(0);
    APP_ERROR_CHECK(err_code);
#else
    __enable_irq();
#endif
}

#endif // configUSE_TICKLESS_IDLE

#else // configTICK_SOURCE
    #error  Unsupported configTICK_SOURCE value
#endif // configTICK_SOURCE == FREERTOS_USE_SYSTICK