esp-idf/components/esp_hw_support/esp_clk.c

/*
 * SPDX-FileCopyrightText: 2015-2022 Espressif Systems (Shanghai) CO LTD
 *
 * SPDX-License-Identifier: Apache-2.0
 */

#include <stdint.h>
#include <sys/param.h>
#include <sys/lock.h>

#include "freertos/FreeRTOS.h"
#include "esp_attr.h"
#include "soc/rtc.h"
#include "soc/soc_caps.h"
#include "esp_rom_caps.h"
#include "esp_rom_sys.h"
#include "esp_private/esp_clk.h"
#include "hal/clk_tree_ll.h"

#if CONFIG_IDF_TARGET_ESP32
#include "esp32/rom/rtc.h"
#include "esp32/rtc.h"
#elif CONFIG_IDF_TARGET_ESP32S2
#include "esp32s2/rom/rtc.h"
#include "esp32s2/rtc.h"
#elif CONFIG_IDF_TARGET_ESP32S3
#include "esp32s3/rom/rtc.h"
#include "esp32s3/rtc.h"
#elif CONFIG_IDF_TARGET_ESP32C3
#include "esp32c3/rom/rtc.h"
#include "esp32c3/rtc.h"
#elif CONFIG_IDF_TARGET_ESP32C2
#include "esp32c2/rom/rtc.h"
#include "esp32c2/rtc.h"
#elif CONFIG_IDF_TARGET_ESP32C6
#include "esp32c6/rom/rtc.h"
#include "esp32c6/rtc.h"
#elif CONFIG_IDF_TARGET_ESP32H2
#include "esp32h2/rom/rtc.h"
#include "esp32h2/rtc.h"
#endif

#define MHZ (1000000)

// g_ticks_us defined in ROMs for PRO and APP CPU
extern uint32_t g_ticks_per_us_pro;

static portMUX_TYPE s_esp_rtc_time_lock = portMUX_INITIALIZER_UNLOCKED;

#if SOC_RTC_FAST_MEM_SUPPORTED
static RTC_NOINIT_ATTR uint64_t s_esp_rtc_time_us, s_rtc_last_ticks;
#endif

inline static int IRAM_ATTR s_get_cpu_freq_mhz(void)
{
#if ESP_ROM_GET_CLK_FREQ
    return esp_rom_get_cpu_ticks_per_us();
#else
    return g_ticks_per_us_pro;
#endif
}

int IRAM_ATTR esp_clk_cpu_freq(void)
{
    return s_get_cpu_freq_mhz() * MHZ;
}

int IRAM_ATTR esp_clk_apb_freq(void)
{
    // TODO: IDF-5173 Require cleanup, implementation should be unified
#if CONFIG_IDF_TARGET_ESP32C6 || CONFIG_IDF_TARGET_ESP32H2
    return rtc_clk_apb_freq_get();
#else
    return MIN(s_get_cpu_freq_mhz() * MHZ, APB_CLK_FREQ);
#endif
}

int IRAM_ATTR esp_clk_xtal_freq(void)
{
    return rtc_clk_xtal_freq_get() * MHZ;
}

uint64_t esp_rtc_get_time_us(void)
{
    portENTER_CRITICAL_SAFE(&s_esp_rtc_time_lock);
    const uint32_t cal = esp_clk_slowclk_cal_get();
#if SOC_RTC_FAST_MEM_SUPPORTED
    if (cal == 0) {
        s_esp_rtc_time_us = 0;
        s_rtc_last_ticks = 0;
    }
    const uint64_t rtc_this_ticks = rtc_time_get();
    const uint64_t ticks = rtc_this_ticks - s_rtc_last_ticks;
#else
    const uint64_t ticks = rtc_time_get();
#endif
    /* RTC counter result is up to 2^48, calibration factor is up to 2^24,
     * for a 32kHz clock. We need to calculate (assuming no overflow):
     *   (ticks * cal) >> RTC_CLK_CAL_FRACT
     *
     * An overflow in the (ticks * cal) multiplication would cause time to
     * wrap around after approximately 13 days, which is probably not enough
     * for some applications.
     * Therefore multiplication is split into two terms, for the lower 32-bit
     * and the upper 16-bit parts of "ticks", i.e.:
     *   ((ticks_low + 2^32 * ticks_high) * cal) >> RTC_CLK_CAL_FRACT
     */
    const uint64_t ticks_low = ticks & UINT32_MAX;
    const uint64_t ticks_high = ticks >> 32;
    const uint64_t delta_time_us = ((ticks_low * cal) >> RTC_CLK_CAL_FRACT) +
                                   ((ticks_high * cal) << (32 - RTC_CLK_CAL_FRACT));
#if SOC_RTC_FAST_MEM_SUPPORTED
    s_esp_rtc_time_us += delta_time_us;
    s_rtc_last_ticks = rtc_this_ticks;
    portEXIT_CRITICAL_SAFE(&s_esp_rtc_time_lock);
    return s_esp_rtc_time_us;
#else
    uint64_t esp_rtc_time_us = delta_time_us + clk_ll_rtc_slow_load_rtc_fix_us();
    portEXIT_CRITICAL_SAFE(&s_esp_rtc_time_lock);
    return esp_rtc_time_us;
#endif
}

void esp_clk_slowclk_cal_set(uint32_t new_cal)
{
#if defined(CONFIG_ESP_TIME_FUNCS_USE_RTC_TIMER)
    /* To force monotonic time values even when clock calibration value changes,
     * we adjust esp_rtc_time
     */
#if SOC_RTC_FAST_MEM_SUPPORTED
    esp_rtc_get_time_us();
#else
    portENTER_CRITICAL_SAFE(&s_esp_rtc_time_lock);
    uint32_t old_cal = clk_ll_rtc_slow_load_cal();
    if (old_cal != 0) {
        /**
         * The logic of time correction is:
         * old_rtc_us = ticks * old_cal >> RTC_CLK_CAL_FRACT + old_fix_us
         * new_rtc_us = ticks * new_cal >> RTC_CLK_CAL_FRACT + new_fix_us
         *
         * Keep "old_rtc_us == new_rtc_us" to make time monotonically increasing,
         * then we can get new_fix_us:
         * new_fix_us = (ticks * old_cal >> RTC_CLK_CAL_FRACT + old_fix_us) - (ticks * new_cal >> RTC_CLK_CAL_FRACT)
         */
        uint64_t ticks = rtc_time_get();
        const uint64_t ticks_low = ticks & UINT32_MAX;
        const uint64_t ticks_high = ticks >> 32;
        uint64_t old_fix_us = clk_ll_rtc_slow_load_rtc_fix_us();
        uint64_t new_fix_us;

        old_fix_us += ((ticks_low * old_cal) >> RTC_CLK_CAL_FRACT) + ((ticks_high * old_cal) << (32 - RTC_CLK_CAL_FRACT));
        new_fix_us = ((ticks_low * new_cal) >> RTC_CLK_CAL_FRACT) + ((ticks_high * new_cal) << (32 - RTC_CLK_CAL_FRACT));
        new_fix_us = old_fix_us - new_fix_us;
        clk_ll_rtc_slow_store_rtc_fix_us(new_fix_us);
    }
    portEXIT_CRITICAL_SAFE(&s_esp_rtc_time_lock);
#endif // SOC_RTC_FAST_MEM_SUPPORTED
#endif // CONFIG_ESP_TIME_FUNCS_USE_RTC_TIMER
    clk_ll_rtc_slow_store_cal(new_cal);
}

uint32_t esp_clk_slowclk_cal_get(void)
{
    return clk_ll_rtc_slow_load_cal();
}

uint64_t esp_clk_rtc_time(void)
{
#ifdef CONFIG_ESP_TIME_FUNCS_USE_RTC_TIMER
    return esp_rtc_get_time_us();
#else
    return 0;
#endif
}

void esp_clk_private_lock(void)
{
    portENTER_CRITICAL(&s_esp_rtc_time_lock);
}

void esp_clk_private_unlock(void)
{
    portEXIT_CRITICAL(&s_esp_rtc_time_lock);
}