esp-idf/components/freertos/port/riscv/port.c

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    ***************************************************************************
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    ***************************************************************************

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*/

/*-----------------------------------------------------------------------
 * Implementation of functions defined in portable.h for the RISC-V port.
 *----------------------------------------------------------------------*/

#include <string.h>
#include "FreeRTOS.h"
#include "task.h"
#include "portmacro.h"

#include "sdkconfig.h"

#include "soc/periph_defs.h"
#include "soc/system_reg.h"
#include "hal/systimer_hal.h"
#include "hal/systimer_ll.h"

#include "riscv/rvruntime-frames.h"
#include "riscv/riscv_interrupts.h"
#include "riscv/interrupt.h"

#include "esp_system.h"
#include "esp_intr_alloc.h"
#include "esp_private/crosscore_int.h"
#include "esp_attr.h"
#include "esp_debug_helpers.h"
#include "esp_log.h"

/**
 * @brief A variable is used to keep track of the critical section nesting.
 * @note This variable has to be stored as part of the task context and must be initialized to a non zero value
 *       to ensure interrupts don't inadvertently become unmasked before the scheduler starts.
 *       As it is stored as part of the task context it will automatically be set to 0 when the first task is started.
 */
static UBaseType_t uxCriticalNesting = 0;
static UBaseType_t uxSavedInterruptState = 0;
BaseType_t uxSchedulerRunning = 0;
UBaseType_t uxInterruptNesting = 0;
BaseType_t xPortSwitchFlag = 0;
__attribute__((aligned(16))) static StackType_t xIsrStack[configISR_STACK_SIZE];
StackType_t *xIsrStackTop = &xIsrStack[0] + (configISR_STACK_SIZE & (~((portPOINTER_SIZE_TYPE)portBYTE_ALIGNMENT_MASK)));

static const char *TAG = "cpu_start"; // [refactor-todo]: might be appropriate to change in the future, but

static void vPortSysTickHandler(void *arg);
static void vPortSetupTimer(void);
static void prvTaskExitError(void);

extern void esprv_intc_int_set_threshold(int); // FIXME, this function is in ROM only

void vPortEnterCritical(void)
{
    BaseType_t state = portENTER_CRITICAL_NESTED();
    uxCriticalNesting++;

    if (uxCriticalNesting == 1) {
        uxSavedInterruptState = state;
    }
}

void vPortExitCritical(void)
{
    if (uxCriticalNesting > 0) {
        uxCriticalNesting--;
        if (uxCriticalNesting == 0) {
            portEXIT_CRITICAL_NESTED(uxSavedInterruptState);
        }
    }
}

/**
 * @brief Set up the systimer peripheral to generate the tick interrupt
 *
 */
void vPortSetupTimer(void)
{
    /* set system timer interrupt vector */
    esp_err_t err = esp_intr_alloc(ETS_SYSTIMER_TARGET0_EDGE_INTR_SOURCE, ESP_INTR_FLAG_IRAM, vPortSysTickHandler, NULL, NULL);
    assert(err == ESP_OK);

    /* configure the timer */
    systimer_hal_init();
    systimer_hal_enable_counter(SYSTIMER_COUNTER_1);
    systimer_hal_set_alarm_period(SYSTIMER_ALARM_0, 1000000UL / CONFIG_FREERTOS_HZ);
    systimer_hal_select_alarm_mode(SYSTIMER_ALARM_0, SYSTIMER_ALARM_MODE_PERIOD);
    systimer_hal_enable_alarm_int(SYSTIMER_ALARM_0);
    systimer_hal_connect_alarm_counter(SYSTIMER_ALARM_0, SYSTIMER_COUNTER_1);
}

void prvTaskExitError(void)
{
    /* A function that implements a task must not exit or attempt to return to
    its caller as there is nothing to return to.  If a task wants to exit it
    should instead call vTaskDelete( NULL ).

    Artificially force an assert() to be triggered if configASSERT() is
    defined, then stop here so application writers can catch the error. */
    configASSERT(uxCriticalNesting == ~0UL);
    portDISABLE_INTERRUPTS();
    abort();
}

/* Clear current interrupt mask and set given mask */
void vPortClearInterruptMask(int mask)
{
    REG_WRITE(INTERRUPT_CORE0_CPU_INT_THRESH_REG, mask);
}

/* Set interrupt mask and return current interrupt enable register */
int vPortSetInterruptMask(void)
{
    int ret;
    unsigned old_mstatus = RV_CLEAR_CSR(mstatus, MSTATUS_MIE);
    ret = REG_READ(INTERRUPT_CORE0_CPU_INT_THRESH_REG);
    REG_WRITE(INTERRUPT_CORE0_CPU_INT_THRESH_REG, RVHAL_EXCM_LEVEL);
    RV_SET_CSR(mstatus, old_mstatus & MSTATUS_MIE);
    return ret;
}

StackType_t *pxPortInitialiseStack(StackType_t *pxTopOfStack, TaskFunction_t pxCode, void *pvParameters)
{
    extern uint32_t __global_pointer$;

    /* Simulate the stack frame as it would be created by a context switch
    interrupt. */
    pxTopOfStack -= RV_STK_FRMSZ;

    RvExcFrame *frame = (RvExcFrame *)pxTopOfStack;
    frame->ra = (UBaseType_t)prvTaskExitError;
    frame->mepc = (UBaseType_t)pxCode;
    frame->a0 = (UBaseType_t)pvParameters;
    frame->gp = (UBaseType_t)&__global_pointer$;
    frame->a1 = 0x11111111;
    frame->a2 = 0x22222222;
    frame->a3 = 0x33333333;

    //TODO: IDF-2393
    return (StackType_t *)frame;
}

IRAM_ATTR void vPortSysTickHandler(void *arg)
{
    (void)arg;

    systimer_ll_clear_alarm_int(SYSTIMER_ALARM_0);

    if (!uxSchedulerRunning) {
        return;
    }

    if (xTaskIncrementTick() != pdFALSE) {
        vPortYieldFromISR();
    }
}

BaseType_t xPortStartScheduler(void)
{
    uxInterruptNesting = 0;
    uxCriticalNesting = 0;
    uxSchedulerRunning = 0;

    vPortSetupTimer();

    esprv_intc_int_set_threshold(1); /* set global INTC masking level */
    riscv_global_interrupts_enable();

    vPortYield();

    /*Should not get here*/
    return pdFALSE;
}

void vPortEndScheduler(void)
{
    /* very unlikely this function will be called, so just trap here */
    abort();
}

void vPortYieldOtherCore(BaseType_t coreid)
{
    esp_crosscore_int_send_yield(coreid);
}

void vPortYieldFromISR( void )
{
    uxSchedulerRunning = 1;
    xPortSwitchFlag = 1;
}

void vPortYield(void)
{
    if (uxInterruptNesting) {
        vPortYieldFromISR();
    } else {

        esp_crosscore_int_send_yield(0);
        /* There are 3-4 instructions of latency between triggering the software
           interrupt and the CPU interrupt happening. Make sure it happened before
           we return, otherwise vTaskDelay() may return and execute 1-2
           instructions before the delay actually happens.

           (We could use the WFI instruction here, but there is a chance that
           the interrupt will happen while evaluating the other two conditions
           for an instant yield, and if that happens then the WFI would be
           waiting for the next interrupt to occur...)
        */
        while (uxSchedulerRunning && uxCriticalNesting == 0 && REG_READ(SYSTEM_CPU_INTR_FROM_CPU_0_REG) != 0) {}
    }

}

#define STACK_WATCH_AREA_SIZE 32
void vPortSetStackWatchpoint(void *pxStackStart)
{
    uint32_t addr = (uint32_t)pxStackStart;
    addr = (addr + (STACK_WATCH_AREA_SIZE - 1)) & (~(STACK_WATCH_AREA_SIZE - 1));
    esp_set_watchpoint(7, (char *)addr, STACK_WATCH_AREA_SIZE, ESP_WATCHPOINT_STORE);
}

BaseType_t xPortInIsrContext(void)
{
    return uxInterruptNesting;
}

BaseType_t IRAM_ATTR xPortInterruptedFromISRContext(void)
{
    /* For single core, this can be the same as xPortInIsrContext() because reading it is atomic */
    return uxInterruptNesting;
}


void vPortCPUInitializeMutex(portMUX_TYPE *mux)
{
    (void)mux;     //TODO: IDF-2393
}

void vPortCPUAcquireMutex(portMUX_TYPE *mux)
{
    (void)mux;    //TODO: IDF-2393
}

bool vPortCPUAcquireMutexTimeout(portMUX_TYPE *mux, int timeout_cycles)
{
    (void)mux;      //TODO: IDF-2393
    (void)timeout_cycles;
    return true;
}

void vPortCPUReleaseMutex(portMUX_TYPE *mux)
{
    (void)mux;     //TODO: IDF-2393
}

void __attribute__((weak)) vApplicationStackOverflowHook(TaskHandle_t xTask, char *pcTaskName)
{
#define ERR_STR1 "***ERROR*** A stack overflow in task "
#define ERR_STR2 " has been detected."
    const char *str[] = {ERR_STR1, pcTaskName, ERR_STR2};

    char buf[sizeof(ERR_STR1) + CONFIG_FREERTOS_MAX_TASK_NAME_LEN + sizeof(ERR_STR2) + 1 /* null char */] = {0};

    char *dest = buf;
    for (int i = 0; i < sizeof(str) / sizeof(str[0]); i++) {
        dest = strcat(dest, str[i]);
    }
    esp_system_abort(buf);
}

extern void esp_startup_start_app_common(void);

void esp_startup_start_app(void)
{
    esp_startup_start_app_common();

    ESP_LOGI(TAG, "Starting scheduler.");
    vTaskStartScheduler();
}