esp-idf/components/esp_hw_support/port/esp32p4/rtc_time.c

/*
 * SPDX-FileCopyrightText: 2022-2023 Espressif Systems (Shanghai) CO LTD
 *
 * SPDX-License-Identifier: Apache-2.0
 */

#include <stdint.h>
#include <assert.h>
#include "esp32p4/rom/ets_sys.h"
#include "soc/rtc.h"
#include "soc/lp_timer_reg.h"
#include "hal/lp_timer_hal.h"
#include "hal/clk_tree_ll.h"
#include "hal/timer_ll.h"
#include "soc/timer_group_reg.h"
#include "esp_rom_sys.h"
#include "esp_private/periph_ctrl.h"

static const char *TAG = "rtc_time";

/* Calibration of RTC_SLOW_CLK is performed using a special feature of TIMG0.
 * This feature counts the number of XTAL clock cycles within a given number of
 * RTC_SLOW_CLK cycles.
 *
 * Slow clock calibration feature has two modes of operation: one-off and cycling.
 * In cycling mode (which is enabled by default on SoC reset), counting of XTAL
 * cycles within RTC_SLOW_CLK cycle is done continuously. Cycling mode is enabled
 * using TIMG_RTC_CALI_START_CYCLING bit. In one-off mode counting is performed
 * once, and TIMG_RTC_CALI_RDY bit is set when counting is done. One-off mode is
 * enabled using TIMG_RTC_CALI_START bit.
 */

/* On ESP32P4, TIMG_RTC_CALI_CLK_SEL can config to 0, 1, 2, 3
 * 0 or 3: calibrate RC_SLOW clock
 * 1: calibrate RC_FAST clock
 * 2: calibrate 32K clock, which 32k depends on reg_32k_sel: 0: Internal 32 kHz RC oscillator, 1: External 32 kHz XTAL, 2: External 32kHz clock input by lp_pad_gpio0
 */
#define TIMG_RTC_CALI_CLK_SEL_RC_SLOW 0
#define TIMG_RTC_CALI_CLK_SEL_RC_FAST 1
#define TIMG_RTC_CALI_CLK_SEL_32K     2

uint32_t rtc_clk_cal_internal(rtc_cal_sel_t cal_clk, uint32_t slowclk_cycles)
{
    assert(slowclk_cycles < TIMG_RTC_CALI_MAX_V);

    uint32_t cali_clk_sel = 0;
    soc_rtc_slow_clk_src_t slow_clk_src = rtc_clk_slow_src_get();
    soc_rtc_slow_clk_src_t old_32k_cal_clk_sel = clk_ll_32k_calibration_get_target();
    if (cal_clk == RTC_CAL_RTC_MUX) {
        cal_clk = (rtc_cal_sel_t)slow_clk_src;
    }
    if (cal_clk == RTC_CAL_RC_FAST) {
        cali_clk_sel = TIMG_RTC_CALI_CLK_SEL_RC_FAST;
    } else if (cal_clk == RTC_CAL_RC_SLOW) {
        cali_clk_sel = TIMG_RTC_CALI_CLK_SEL_RC_SLOW;
    } else {
        cali_clk_sel = TIMG_RTC_CALI_CLK_SEL_32K;
        clk_ll_32k_calibration_set_target((soc_rtc_slow_clk_src_t)cal_clk);
    }


    /* Enable requested clock (150k clock is always on) */
    // All clocks on/off takes time to be stable, so we shouldn't frequently enable/disable the clock
    // Only enable if orignally was disabled, and set back to the disable state after calibration is done
    // If the clock is already on, then do nothing
    bool dig_32k_xtal_enabled = clk_ll_xtal32k_digi_is_enabled();
    if (cal_clk == RTC_CAL_32K_XTAL && !dig_32k_xtal_enabled) {
            clk_ll_xtal32k_digi_enable();
    }

    bool rc_fast_enabled = clk_ll_rc_fast_is_enabled();
    bool dig_rc_fast_enabled = clk_ll_rc_fast_digi_is_enabled();
    if (cal_clk == RTC_CAL_RC_FAST) {
        if (!rc_fast_enabled) {
            rtc_clk_8m_enable(true);
        }
        if (!dig_rc_fast_enabled) {
            rtc_dig_clk8m_enable();
        }
    }

    bool rc32k_enabled = clk_ll_rc32k_is_enabled();
    bool dig_rc32k_enabled = clk_ll_rc32k_digi_is_enabled();
    if (cal_clk == RTC_CAL_RC32K) {
        if (!rc32k_enabled) {
            rtc_clk_rc32k_enable(true);
        }
        if (!dig_rc32k_enabled) {
            clk_ll_rc32k_digi_enable();
        }
    }

    /* There may be another calibration process already running during we call this function,
     * so we should wait the last process is done.
     */
    if (GET_PERI_REG_MASK(TIMG_RTCCALICFG_REG(0), TIMG_RTC_CALI_START_CYCLING)) {
        /**
         * Set a small timeout threshold to accelerate the generation of timeout.
         * The internal circuit will be reset when the timeout occurs and will not affect the next calibration.
         */
        REG_SET_FIELD(TIMG_RTCCALICFG2_REG(0), TIMG_RTC_CALI_TIMEOUT_THRES, 1);
        while (!GET_PERI_REG_MASK(TIMG_RTCCALICFG_REG(0), TIMG_RTC_CALI_RDY)
               && !GET_PERI_REG_MASK(TIMG_RTCCALICFG2_REG(0), TIMG_RTC_CALI_TIMEOUT));
    }

    /* Prepare calibration */
    REG_SET_FIELD(TIMG_RTCCALICFG_REG(0), TIMG_RTC_CALI_CLK_SEL, cali_clk_sel);
    CLEAR_PERI_REG_MASK(TIMG_RTCCALICFG_REG(0), TIMG_RTC_CALI_START_CYCLING);
    REG_SET_FIELD(TIMG_RTCCALICFG_REG(0), TIMG_RTC_CALI_MAX, slowclk_cycles);
    /* Figure out how long to wait for calibration to finish */

    /* Set timeout reg and expect time delay*/
    uint32_t expected_freq;
    if (cali_clk_sel == TIMG_RTC_CALI_CLK_SEL_32K) {
        REG_SET_FIELD(TIMG_RTCCALICFG2_REG(0), TIMG_RTC_CALI_TIMEOUT_THRES, RTC_SLOW_CLK_32K_CAL_TIMEOUT_THRES(slowclk_cycles));
        expected_freq = SOC_CLK_XTAL32K_FREQ_APPROX;
    } else if (cali_clk_sel == TIMG_RTC_CALI_CLK_SEL_RC_FAST) {
        REG_SET_FIELD(TIMG_RTCCALICFG2_REG(0), TIMG_RTC_CALI_TIMEOUT_THRES, RTC_FAST_CLK_20M_CAL_TIMEOUT_THRES(slowclk_cycles));
        expected_freq = SOC_CLK_RC_FAST_FREQ_APPROX;
    } else {
        REG_SET_FIELD(TIMG_RTCCALICFG2_REG(0), TIMG_RTC_CALI_TIMEOUT_THRES, RTC_SLOW_CLK_150K_CAL_TIMEOUT_THRES(slowclk_cycles));
        expected_freq = SOC_CLK_RC_SLOW_FREQ_APPROX;
    }
    uint32_t us_time_estimate = (uint32_t) (((uint64_t) slowclk_cycles) * MHZ / expected_freq);
    /* Start calibration */
    CLEAR_PERI_REG_MASK(TIMG_RTCCALICFG_REG(0), TIMG_RTC_CALI_START);
    SET_PERI_REG_MASK(TIMG_RTCCALICFG_REG(0), TIMG_RTC_CALI_START);

    /* Wait for calibration to finish up to another us_time_estimate */
    esp_rom_delay_us(us_time_estimate);
    uint32_t cal_val;
    while (true) {
        if (GET_PERI_REG_MASK(TIMG_RTCCALICFG_REG(0), TIMG_RTC_CALI_RDY)) {
            cal_val = REG_GET_FIELD(TIMG_RTCCALICFG1_REG(0), TIMG_RTC_CALI_VALUE);
            break;
        }
        if (GET_PERI_REG_MASK(TIMG_RTCCALICFG2_REG(0), TIMG_RTC_CALI_TIMEOUT)) {
            cal_val = 0;
            break;
        }
    }
    CLEAR_PERI_REG_MASK(TIMG_RTCCALICFG_REG(0), TIMG_RTC_CALI_START);

    /* if dig_32k_xtal was originally off and enabled due to calibration, then set back to off state */
    if (cal_clk == RTC_CAL_32K_XTAL && !dig_32k_xtal_enabled) {
        clk_ll_xtal32k_digi_disable();
    }

    if (cal_clk == RTC_CAL_RC_FAST) {
        if (!dig_rc_fast_enabled) {
            rtc_dig_clk8m_disable();
        }
        if (!rc_fast_enabled) {
            rtc_clk_8m_enable(false);
        }
    }

    if (cal_clk == RTC_CAL_RC32K) {
        if (!dig_rc32k_enabled) {
            clk_ll_rc32k_digi_disable();
        }
        if (!rc32k_enabled) {
            rtc_clk_rc32k_enable(false);
        }
    }

    // Always set back the calibration 32kHz clock selection
    if (old_32k_cal_clk_sel != SOC_RTC_SLOW_CLK_SRC_INVALID) {
        clk_ll_32k_calibration_set_target(old_32k_cal_clk_sel);
    }

    return cal_val;
}

static bool rtc_clk_cal_32k_valid(rtc_xtal_freq_t xtal_freq, uint32_t slowclk_cycles, uint64_t actual_xtal_cycles)
{
    uint64_t expected_xtal_cycles = (xtal_freq * 1000000ULL * slowclk_cycles) >> 15; // xtal_freq(hz) * slowclk_cycles / 32768
    uint64_t delta = expected_xtal_cycles / 2000;                                    // 5/10000 = 0.05% error range
    return (actual_xtal_cycles >= (expected_xtal_cycles - delta)) && (actual_xtal_cycles <= (expected_xtal_cycles + delta));
}

uint32_t rtc_clk_cal(rtc_cal_sel_t cal_clk, uint32_t slowclk_cycles)
{
    rtc_xtal_freq_t xtal_freq = rtc_clk_xtal_freq_get();
    uint64_t xtal_cycles = rtc_clk_cal_internal(cal_clk, slowclk_cycles);

    if (cal_clk == RTC_CAL_32K_XTAL && !rtc_clk_cal_32k_valid(xtal_freq, slowclk_cycles, xtal_cycles)) {
        return 0;
    }

    uint64_t divider = ((uint64_t)xtal_freq) * slowclk_cycles;
    uint64_t period_64 = ((xtal_cycles << RTC_CLK_CAL_FRACT) + divider / 2 - 1) / divider;
    uint32_t period = (uint32_t)(period_64 & UINT32_MAX);
    return period;
}

uint64_t rtc_time_us_to_slowclk(uint64_t time_in_us, uint32_t period)
{
    /* Overflow will happen in this function if time_in_us >= 2^45, which is about 400 days.
     * TODO: fix overflow.
     */
    return (time_in_us << RTC_CLK_CAL_FRACT) / period;
}

uint64_t rtc_time_slowclk_to_us(uint64_t rtc_cycles, uint32_t period)
{
    return (rtc_cycles * period) >> RTC_CLK_CAL_FRACT;
}

uint64_t rtc_time_get(void)
{
    // return lp_timer_hal_get_cycle_count(0);
    ESP_EARLY_LOGE(TAG, "rtc_time_get has not been implemented yet");
    return 0;
}

void rtc_clk_wait_for_slow_cycle(void) //This function may not by useful any more
{
    // TODO: IDF-5781
    ESP_EARLY_LOGW(TAG, "rtc_clk_wait_for_slow_cycle() has not been implemented yet");
}

uint32_t rtc_clk_freq_cal(uint32_t cal_val)
{
    if (cal_val == 0) {
        return 0;   // cal_val will be denominator, return 0 as the symbol of failure.
    }
    return 1000000ULL * (1 << RTC_CLK_CAL_FRACT) / cal_val;
}

/// @brief if the calibration is used, we need to enable the timer group0 first
__attribute__((constructor))
static void enable_timer_group0_for_calibration(void)
{
    PERIPH_RCC_ACQUIRE_ATOMIC(PERIPH_TIMG0_MODULE, ref_count) {
        if (ref_count == 0) {
            timer_ll_enable_bus_clock(0, true);
            timer_ll_reset_register(0);
        }
    }
}