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clk.c
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clk.c
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/*
* SPDX-FileCopyrightText: 2015-2022 Espressif Systems (Shanghai) CO LTD
*
* SPDX-License-Identifier: Apache-2.0
*/
#include <stdint.h>
#include <sys/cdefs.h>
#include <sys/time.h>
#include <sys/param.h>
#include "sdkconfig.h"
#include "esp_attr.h"
#include "esp_log.h"
#include "esp_cpu.h"
#include "esp_private/esp_clk.h"
#include "esp_clk_internal.h"
#include "esp32c2/rom/ets_sys.h"
#include "esp32c2/rom/uart.h"
#include "esp32c2/rom/rtc.h"
#include "soc/system_reg.h"
#include "soc/soc.h"
#include "soc/rtc.h"
#include "soc/rtc_periph.h"
#include "hal/wdt_hal.h"
#include "esp_private/periph_ctrl.h"
#include "bootloader_clock.h"
#include "soc/syscon_reg.h"
#include "esp_rom_uart.h"
/* Number of cycles to wait from the 32k XTAL oscillator to consider it running.
* Larger values increase startup delay. Smaller values may cause false positive
* detection (i.e. oscillator runs for a few cycles and then stops).
*/
#define SLOW_CLK_CAL_CYCLES CONFIG_RTC_CLK_CAL_CYCLES
#define MHZ (1000000)
/* Lower threshold for a reasonably-looking calibration value for a 32k XTAL.
* The ideal value (assuming 32768 Hz frequency) is 1000000/32768*(2**19) = 16*10^6.
*/
#define MIN_32K_XTAL_CAL_VAL 15000000L
/* Indicates that this 32k oscillator gets input from external oscillator, rather
* than a crystal.
*/
#define EXT_OSC_FLAG BIT(3)
/* This is almost the same as soc_rtc_slow_clk_src_t, except that we define
* an extra enum member for the external 32k oscillator.
* For convenience, lower 2 bits should correspond to soc_rtc_slow_clk_src_t values.
*/
typedef enum {
SLOW_CLK_RTC = SOC_RTC_SLOW_CLK_SRC_RC_SLOW, //!< Internal 150 kHz RC oscillator
SLOW_CLK_8MD256 = SOC_RTC_SLOW_CLK_SRC_RC_FAST_D256, //!< Internal 8 MHz RC oscillator, divided by 256
SLOW_CLK_32K_EXT_OSC = SOC_RTC_SLOW_CLK_SRC_OSC_SLOW | EXT_OSC_FLAG //!< External 32k oscillator connected to pin0
} slow_clk_sel_t;
static void select_rtc_slow_clk(slow_clk_sel_t slow_clk);
static const char *TAG = "clk";
__attribute__((weak)) void esp_clk_init(void)
{
#if !CONFIG_IDF_ENV_FPGA
rtc_config_t cfg = RTC_CONFIG_DEFAULT();
soc_reset_reason_t rst_reas;
rst_reas = esp_rom_get_reset_reason(0);
if (rst_reas == RESET_REASON_CHIP_POWER_ON) {
cfg.cali_ocode = 1;
}
rtc_init(cfg);
#ifndef CONFIG_XTAL_FREQ_AUTO
assert(rtc_clk_xtal_freq_get() == CONFIG_XTAL_FREQ);
#endif
bool rc_fast_d256_is_enabled = rtc_clk_8md256_enabled();
rtc_clk_8m_enable(true, rc_fast_d256_is_enabled);
rtc_clk_fast_src_set(SOC_RTC_FAST_CLK_SRC_RC_FAST);
#endif
#ifdef CONFIG_BOOTLOADER_WDT_ENABLE
// WDT uses a SLOW_CLK clock source. After a function select_rtc_slow_clk a frequency of this source can changed.
// If the frequency changes from 150kHz to 32kHz, then the timeout set for the WDT will increase 4.6 times.
// Therefore, for the time of frequency change, set a new lower timeout value (1.6 sec).
// This prevents excessive delay before resetting in case the supply voltage is drawdown.
// (If frequency is changed from 150kHz to 32kHz then WDT timeout will increased to 1.6sec * 150/32 = 7.5 sec).
wdt_hal_context_t rtc_wdt_ctx = {.inst = WDT_RWDT, .rwdt_dev = &RTCCNTL};
uint32_t stage_timeout_ticks = (uint32_t)(1600ULL * rtc_clk_slow_freq_get_hz() / 1000ULL);
wdt_hal_write_protect_disable(&rtc_wdt_ctx);
wdt_hal_feed(&rtc_wdt_ctx);
//Bootloader has enabled RTC WDT until now. We're only modifying timeout, so keep the stage and timeout action the same
wdt_hal_config_stage(&rtc_wdt_ctx, WDT_STAGE0, stage_timeout_ticks, WDT_STAGE_ACTION_RESET_RTC);
wdt_hal_write_protect_enable(&rtc_wdt_ctx);
#endif
#if defined(CONFIG_RTC_CLK_SRC_EXT_OSC)
select_rtc_slow_clk(SLOW_CLK_32K_EXT_OSC);
#elif defined(CONFIG_RTC_CLK_SRC_INT_8MD256)
select_rtc_slow_clk(SLOW_CLK_8MD256);
#else
select_rtc_slow_clk(SLOW_CLK_RTC);
#endif
#ifdef CONFIG_BOOTLOADER_WDT_ENABLE
// After changing a frequency WDT timeout needs to be set for new frequency.
stage_timeout_ticks = (uint32_t)((uint64_t)CONFIG_BOOTLOADER_WDT_TIME_MS * rtc_clk_slow_freq_get_hz() / 1000);
wdt_hal_write_protect_disable(&rtc_wdt_ctx);
wdt_hal_feed(&rtc_wdt_ctx);
wdt_hal_config_stage(&rtc_wdt_ctx, WDT_STAGE0, stage_timeout_ticks, WDT_STAGE_ACTION_RESET_RTC);
wdt_hal_write_protect_enable(&rtc_wdt_ctx);
#endif
rtc_cpu_freq_config_t old_config, new_config;
rtc_clk_cpu_freq_get_config(&old_config);
const uint32_t old_freq_mhz = old_config.freq_mhz;
const uint32_t new_freq_mhz = CONFIG_ESP_DEFAULT_CPU_FREQ_MHZ;
bool res = rtc_clk_cpu_freq_mhz_to_config(new_freq_mhz, &new_config);
assert(res);
// Wait for UART TX to finish, otherwise some UART output will be lost
// when switching APB frequency
esp_rom_uart_tx_wait_idle(CONFIG_ESP_CONSOLE_UART_NUM);
if (res) {
rtc_clk_cpu_freq_set_config(&new_config);
}
// Re calculate the ccount to make time calculation correct.
esp_cpu_set_cycle_count( (uint64_t)esp_cpu_get_cycle_count() * new_freq_mhz / old_freq_mhz );
}
static void select_rtc_slow_clk(slow_clk_sel_t slow_clk)
{
soc_rtc_slow_clk_src_t rtc_slow_clk_src = slow_clk & RTC_CNTL_ANA_CLK_RTC_SEL_V;
uint32_t cal_val = 0;
/* number of times to repeat external clock calibration
* before giving up and switching to the internal RC
*/
int retry_ext_clk = 3;
do {
if (rtc_slow_clk_src == SOC_RTC_SLOW_CLK_SRC_OSC_SLOW) {
/* external clock needs to be connected to PIN0 before it can
* be used. Here we use rtc_clk_cal function to count
* the number of ext clk cycles in the given number of ext clk
* cycles. If the ext clk has not started up, calibration
* will time out, returning 0.
*/
ESP_EARLY_LOGD(TAG, "waiting for external clock by pin0 to start up");
rtc_clk_32k_enable_external();
// When SLOW_CLK_CAL_CYCLES is set to 0, clock calibration will not be performed at startup.
if (SLOW_CLK_CAL_CYCLES > 0) {
cal_val = rtc_clk_cal(RTC_CAL_EXT_CLK, SLOW_CLK_CAL_CYCLES);
if (cal_val == 0 || cal_val < MIN_32K_XTAL_CAL_VAL) {
if (retry_ext_clk-- > 0) {
continue;
}
ESP_EARLY_LOGW(TAG, "external clock connected to pin0 not found, switching to internal 150 kHz oscillator");
rtc_slow_clk_src = SOC_RTC_SLOW_CLK_SRC_RC_SLOW;
}
}
} else if (rtc_slow_clk_src == SOC_RTC_SLOW_CLK_SRC_RC_FAST_D256) {
rtc_clk_8m_enable(true, true);
}
rtc_clk_slow_src_set(rtc_slow_clk_src);
if (SLOW_CLK_CAL_CYCLES > 0) {
/* TODO: 32k XTAL oscillator has some frequency drift at startup.
* Improve calibration routine to wait until the frequency is stable.
*/
cal_val = rtc_clk_cal(RTC_CAL_RTC_MUX, SLOW_CLK_CAL_CYCLES);
} else {
const uint64_t cal_dividend = (1ULL << RTC_CLK_CAL_FRACT) * 1000000ULL;
cal_val = (uint32_t) (cal_dividend / rtc_clk_slow_freq_get_hz());
}
} while (cal_val == 0);
ESP_EARLY_LOGD(TAG, "RTC_SLOW_CLK calibration value: %d", cal_val);
esp_clk_slowclk_cal_set(cal_val);
}
/* This function is not exposed as an API at this point.
* All peripheral clocks are default enabled after chip is powered on.
* This function disables some peripheral clocks when cpu starts.
* These peripheral clocks are enabled when the peripherals are initialized
* and disabled when they are de-initialized.
*/
__attribute__((weak)) void esp_perip_clk_init(void)
{
uint32_t common_perip_clk, hwcrypto_perip_clk, wifi_bt_sdio_clk = 0;
uint32_t common_perip_clk1 = 0;
soc_reset_reason_t rst_reason = esp_rom_get_reset_reason(0);
/* For reason that only reset CPU, do not disable the clocks
* that have been enabled before reset.
*/
if (rst_reason == RESET_REASON_CPU0_MWDT0 || rst_reason == RESET_REASON_CPU0_SW ||
rst_reason == RESET_REASON_CPU0_RTC_WDT || rst_reason == RESET_REASON_CPU0_JTAG) {
common_perip_clk = ~READ_PERI_REG(SYSTEM_PERIP_CLK_EN0_REG);
hwcrypto_perip_clk = ~READ_PERI_REG(SYSTEM_PERIP_CLK_EN1_REG);
wifi_bt_sdio_clk = ~READ_PERI_REG(SYSTEM_WIFI_CLK_EN_REG);
} else {
common_perip_clk = SYSTEM_SPI2_CLK_EN |
#if CONFIG_ESP_CONSOLE_UART_NUM != 0
SYSTEM_UART_CLK_EN |
#endif
#if CONFIG_ESP_CONSOLE_UART_NUM != 1
SYSTEM_UART1_CLK_EN |
#endif
SYSTEM_LEDC_CLK_EN |
SYSTEM_I2C_EXT0_CLK_EN |
SYSTEM_LEDC_CLK_EN;
common_perip_clk1 = 0;
hwcrypto_perip_clk = SYSTEM_CRYPTO_SHA_CLK_EN;
wifi_bt_sdio_clk = SYSTEM_WIFI_CLK_WIFI_EN |
SYSTEM_WIFI_CLK_BT_EN_M |
SYSTEM_WIFI_CLK_UNUSED_BIT5 |
SYSTEM_WIFI_CLK_UNUSED_BIT12;
}
//Reset the communication peripherals like I2C, SPI, UART and bring them to known state.
common_perip_clk |= SYSTEM_SPI2_CLK_EN |
#if CONFIG_ESP_CONSOLE_UART_NUM != 0
SYSTEM_UART_CLK_EN |
#endif
#if CONFIG_ESP_CONSOLE_UART_NUM != 1
SYSTEM_UART1_CLK_EN |
#endif
SYSTEM_I2C_EXT0_CLK_EN;
common_perip_clk1 = 0;
/* Disable some peripheral clocks. */
CLEAR_PERI_REG_MASK(SYSTEM_PERIP_CLK_EN0_REG, common_perip_clk);
SET_PERI_REG_MASK(SYSTEM_PERIP_RST_EN0_REG, common_perip_clk);
CLEAR_PERI_REG_MASK(SYSTEM_PERIP_CLK_EN1_REG, common_perip_clk1);
SET_PERI_REG_MASK(SYSTEM_PERIP_RST_EN1_REG, common_perip_clk1);
/* Disable hardware crypto clocks. */
CLEAR_PERI_REG_MASK(SYSTEM_PERIP_CLK_EN1_REG, hwcrypto_perip_clk);
SET_PERI_REG_MASK(SYSTEM_PERIP_RST_EN1_REG, hwcrypto_perip_clk);
/* Disable WiFi/BT/SDIO clocks. */
CLEAR_PERI_REG_MASK(SYSTEM_WIFI_CLK_EN_REG, wifi_bt_sdio_clk);
SET_PERI_REG_MASK(SYSTEM_WIFI_CLK_EN_REG, SYSTEM_WIFI_CLK_EN);
/* Set WiFi light sleep clock source to RTC slow clock */
REG_SET_FIELD(SYSTEM_BT_LPCK_DIV_INT_REG, SYSTEM_BT_LPCK_DIV_NUM, 0);
CLEAR_PERI_REG_MASK(SYSTEM_BT_LPCK_DIV_FRAC_REG, SYSTEM_LPCLK_SEL_8M);
SET_PERI_REG_MASK(SYSTEM_BT_LPCK_DIV_FRAC_REG, SYSTEM_LPCLK_SEL_RTC_SLOW);
/* Enable RNG clock. */
periph_module_enable(PERIPH_RNG_MODULE);
}