esp-idf/components/esp_hw_support/clk_ctrl_os.c

// Copyright 2020 Espressif Systems (Shanghai) PTE LTD
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

#include <freertos/FreeRTOS.h>
#include "soc/clk_ctrl_os.h"

#define DELAY_RTC_CLK_SWITCH 5

static portMUX_TYPE periph_spinlock = portMUX_INITIALIZER_UNLOCKED;

static uint8_t s_periph_ref_counts = 0;
static uint32_t s_rtc_clk_freq = 0; // Frequency of the 8M/256 clock in Hz

bool periph_rtc_dig_clk8m_enable(void)
{
    portENTER_CRITICAL(&periph_spinlock);
    if (s_periph_ref_counts == 0) {
        rtc_dig_clk8m_enable();
        s_rtc_clk_freq = rtc_clk_freq_cal(rtc_clk_cal(RTC_CAL_8MD256, 100));
        if (s_rtc_clk_freq == 0) {
            portEXIT_CRITICAL(&periph_spinlock);
            return false;
        }
    }
    s_periph_ref_counts++;
    portEXIT_CRITICAL(&periph_spinlock);
    return true;
}

uint32_t periph_rtc_dig_clk8m_get_freq(void)
{
    return s_rtc_clk_freq * 256;
}

void periph_rtc_dig_clk8m_disable(void)
{
    portENTER_CRITICAL(&periph_spinlock);
    assert(s_periph_ref_counts > 0);
    s_periph_ref_counts--;
    if (s_periph_ref_counts == 0) {
        s_rtc_clk_freq = 0;
        rtc_dig_clk8m_disable();
    }
    portEXIT_CRITICAL(&periph_spinlock);
}