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/*
* Copyright (c) 2022 Espressif Systems (Shanghai) CO LTD
*
* SPDX-License-Identifier: Apache-2.0
*/
#define DT_DRV_COMPAT espressif_esp32_adc
#include <errno.h>
#include <hal/adc_hal.h>
#include <hal/adc_types.h>
#include <esp_adc_cal.h>
#include <esp_heap_caps.h>
#include <zephyr/kernel.h>
#include <zephyr/device.h>
#include <zephyr/drivers/adc.h>
#include "driver/periph_ctrl.h"
#include <zephyr/logging/log.h>
LOG_MODULE_REGISTER(adc_esp32, CONFIG_ADC_LOG_LEVEL);
#if CONFIG_SOC_ESP32
#define ADC_CALI_SCHEME ESP_ADC_CAL_VAL_EFUSE_VREF
#define ADC_RESOLUTION_MIN SOC_ADC_DIGI_MIN_BITWIDTH
#define ADC_RESOLUTION_MAX SOC_ADC_DIGI_MAX_BITWIDTH
/* Due to significant measurement discrepancy in higher voltage range, we
* clip the value instead of yet another correction. The IDF implementation
* for ESP32-S2 is doing it, so we copy that approach in Zephyr driver
*/
#define ADC_CLIP_MVOLT_11DB 2550
#elif CONFIG_SOC_ESP32S2
#define ADC_CALI_SCHEME ESP_ADC_CAL_VAL_EFUSE_TP
#define ADC_RESOLUTION_MIN SOC_ADC_DIGI_MAX_BITWIDTH
#define ADC_RESOLUTION_MAX SOC_ADC_MAX_BITWIDTH
#elif CONFIG_SOC_ESP32C3
#define ADC_CALI_SCHEME ESP_ADC_CAL_VAL_EFUSE_TP
#define ADC_RESOLUTION_MIN SOC_ADC_DIGI_MAX_BITWIDTH
#define ADC_RESOLUTION_MAX SOC_ADC_DIGI_MAX_BITWIDTH
#endif
/* Convert resolution in bits to esp32 enum values */
#define WIDTH_MASK(r) ((((r) - 9) < ADC_WIDTH_MAX) ? ((r) - 9) : (ADC_WIDTH_MAX - 1))
/* Validate if resolution in bits is within allowed values */
#define VALID_RESOLUTION(r) ((r) >= ADC_RESOLUTION_MIN && (r) <= ADC_RESOLUTION_MAX)
#define INVALID_RESOLUTION(r) (!VALID_RESOLUTION(r))
/* Default internal reference voltage */
#define ADC_ESP32_DEFAULT_VREF_INTERNAL (1100)
struct adc_esp32_conf {
adc_unit_t unit;
uint8_t channel_count;
};
struct adc_esp32_data {
adc_atten_t attenuation[ADC_CHANNEL_MAX];
uint8_t resolution[ADC_CHANNEL_MAX];
esp_adc_cal_characteristics_t chars[ADC_CHANNEL_MAX];
uint16_t meas_ref_internal;
uint16_t *buffer;
uint16_t *buffer_repeat;
bool calibrate;
};
/* Convert zephyr,gain property to the ESP32 attenuation */
static inline int gain_to_atten(enum adc_gain gain, adc_atten_t *atten)
{
switch (gain) {
case ADC_GAIN_1:
*atten = ADC_ATTEN_DB_0;
break;
case ADC_GAIN_4_5:
*atten = ADC_ATTEN_DB_2_5;
break;
case ADC_GAIN_1_2:
*atten = ADC_ATTEN_DB_6;
break;
case ADC_GAIN_1_4:
*atten = ADC_ATTEN_DB_11;
break;
default:
return -ENOTSUP;
}
return 0;
}
/* Convert voltage by inverted attenuation to support zephyr gain values */
static void atten_to_gain(adc_atten_t atten, uint32_t *val_mv)
{
if (!val_mv) {
return;
}
switch (atten) {
case ADC_ATTEN_DB_2_5:
*val_mv = (*val_mv * 4) / 5; /* 1/ADC_GAIN_4_5 */
break;
case ADC_ATTEN_DB_6:
*val_mv = *val_mv >> 1; /* 1/ADC_GAIN_1_2 */
break;
case ADC_ATTEN_DB_11:
*val_mv = *val_mv / 4; /* 1/ADC_GAIN_1_4 */
break;
case ADC_ATTEN_DB_0: /* 1/ADC_GAIN_1 */
default:
break;
}
}
static bool adc_calibration_init(const struct device *dev)
{
struct adc_esp32_data *data = dev->data;
switch (esp_adc_cal_check_efuse(ADC_CALI_SCHEME)) {
case ESP_ERR_NOT_SUPPORTED:
LOG_WRN("Skip software calibration - Not supported!");
break;
case ESP_ERR_INVALID_VERSION:
LOG_WRN("Skip software calibration - Invalid version!");
break;
case ESP_OK:
LOG_DBG("Software calibration possible");
return true;
default:
LOG_ERR("Invalid arg");
break;
}
return false;
}
static int adc_esp32_read(const struct device *dev, const struct adc_sequence *seq)
{
const struct adc_esp32_conf *conf = dev->config;
struct adc_esp32_data *data = dev->data;
int reading;
uint32_t cal, cal_mv;
uint8_t channel_id = find_lsb_set(seq->channels) - 1;
if (seq->buffer_size < 2) {
LOG_ERR("Sequence buffer space too low '%d'", seq->buffer_size);
return -ENOMEM;
}
if (seq->channels > BIT(channel_id)) {
LOG_ERR("Multi-channel readings not supported");
return -ENOTSUP;
}
if (INVALID_RESOLUTION(seq->resolution)) {
LOG_ERR("unsupported resolution (%d)", seq->resolution);
return -ENOTSUP;
}
if (seq->calibrate) {
/* TODO: Does this mean actual Vref measurement on selected GPIO ?*/
LOG_ERR("calibration is not supported");
return -ENOTSUP;
}
data->resolution[channel_id] = seq->resolution;
#if CONFIG_SOC_ESP32C3
/* NOTE: nothing to set on ESP32C3 SoC */
if (conf->unit == ADC_UNIT_1) {
adc1_config_width(ADC_WIDTH_BIT_DEFAULT);
}
#else
adc_set_data_width(conf->unit, WIDTH_MASK(data->resolution[channel_id]));
#endif /* CONFIG_SOC_ESP32C3 */
/* Read raw value */
if (conf->unit == ADC_UNIT_1) {
reading = adc1_get_raw(channel_id);
}
if (conf->unit == ADC_UNIT_2) {
if (adc2_get_raw(channel_id, ADC_WIDTH_BIT_DEFAULT, &reading)) {
LOG_ERR("Conversion timeout on '%s' channel %d", dev->name, channel_id);
return -ETIMEDOUT;
}
}
/* Calibration scheme is available */
if (data->calibrate) {
data->chars[channel_id].bit_width = WIDTH_MASK(data->resolution[channel_id]);
/* Get corrected voltage output */
cal = cal_mv = esp_adc_cal_raw_to_voltage(reading, &data->chars[channel_id]);
#if CONFIG_SOC_ESP32
if (data->attenuation[channel_id] == ADC_ATTEN_DB_11) {
if (cal > ADC_CLIP_MVOLT_11DB) {
cal = ADC_CLIP_MVOLT_11DB;
}
}
#endif /* CONFIG_SOC_ESP32 */
/* Fit according to selected attenuation */
atten_to_gain(data->attenuation[channel_id], &cal);
if (data->meas_ref_internal > 0) {
cal = (cal << data->resolution[channel_id]) / data->meas_ref_internal;
}
} else {
LOG_DBG("Using uncalibrated values!");
/* Uncalibrated raw value */
cal = reading;
}
/* Store result */
data->buffer = (uint16_t *) seq->buffer;
data->buffer[0] = cal;
return 0;
}
#ifdef CONFIG_ADC_ASYNC
static int adc_esp32_read_async(const struct device *dev,
const struct adc_sequence *sequence,
struct k_poll_signal *async)
{
(void)(dev);
(void)(sequence);
(void)(async);
return -ENOTSUP;
}
#endif /* CONFIG_ADC_ASYNC */
static int adc_esp32_channel_setup(const struct device *dev, const struct adc_channel_cfg *cfg)
{
const struct adc_esp32_conf *conf = (const struct adc_esp32_conf *)dev->config;
struct adc_esp32_data *data = (struct adc_esp32_data *) dev->data;
int err;
if (cfg->channel_id >= conf->channel_count) {
LOG_ERR("Unsupported channel id '%d'", cfg->channel_id);
return -ENOTSUP;
}
if (cfg->reference != ADC_REF_INTERNAL) {
LOG_ERR("Unsupported channel reference '%d'", cfg->reference);
return -ENOTSUP;
}
if (cfg->acquisition_time != ADC_ACQ_TIME_DEFAULT) {
LOG_ERR("Unsupported acquisition_time '%d'", cfg->acquisition_time);
return -ENOTSUP;
}
if (cfg->differential) {
LOG_ERR("Differential channels are not supported");
return -ENOTSUP;
}
if (gain_to_atten(cfg->gain, &data->attenuation[cfg->channel_id])) {
LOG_ERR("Unsupported gain value '%d'", cfg->gain);
return -ENOTSUP;
}
/* Prepare channel */
if (conf->unit == ADC_UNIT_1) {
adc1_config_channel_atten(cfg->channel_id, data->attenuation[cfg->channel_id]);
}
if (conf->unit == ADC_UNIT_2) {
adc2_config_channel_atten(cfg->channel_id, data->attenuation[cfg->channel_id]);
}
if (data->calibrate) {
esp_adc_cal_value_t cal = esp_adc_cal_characterize(conf->unit,
data->attenuation[cfg->channel_id],
WIDTH_MASK(data->resolution[cfg->channel_id]),
data->meas_ref_internal,
&data->chars[cfg->channel_id]);
if (cal >= ESP_ADC_CAL_VAL_NOT_SUPPORTED) {
LOG_ERR("Calibration error or not supported");
return -EIO;
}
LOG_DBG("Using ADC calibration method %d", cal);
}
return 0;
}
static int adc_esp32_init(const struct device *dev)
{
struct adc_esp32_data *data = (struct adc_esp32_data *) dev->data;
for (uint8_t i = 0; i < ARRAY_SIZE(data->resolution); i++) {
data->resolution[i] = ADC_RESOLUTION_MAX;
}
for (uint8_t i = 0; i < ARRAY_SIZE(data->attenuation); i++) {
data->attenuation[i] = ADC_ATTEN_DB_0;
}
/* Default reference voltage. This could be calibrated externaly */
data->meas_ref_internal = ADC_ESP32_DEFAULT_VREF_INTERNAL;
/* Check if calibration is possible */
data->calibrate = adc_calibration_init(dev);
return 0;
}
static const struct adc_driver_api api_esp32_driver_api = {
.channel_setup = adc_esp32_channel_setup,
.read = adc_esp32_read,
#ifdef CONFIG_ADC_ASYNC
.read_async = adc_esp32_read_async,
#endif /* CONFIG_ADC_ASYNC */
.ref_internal = ADC_ESP32_DEFAULT_VREF_INTERNAL,
};
#define ESP32_ADC_INIT(inst) \
\
static const struct adc_esp32_conf adc_esp32_conf_##inst = { \
.unit = DT_PROP(DT_DRV_INST(inst), unit), \
.channel_count = DT_PROP(DT_DRV_INST(inst), channel_count), \
}; \
\
static struct adc_esp32_data adc_esp32_data_##inst = { \
}; \
\
DEVICE_DT_INST_DEFINE(inst, &adc_esp32_init, NULL, \
&adc_esp32_data_##inst, \
&adc_esp32_conf_##inst, \
POST_KERNEL, \
CONFIG_ADC_INIT_PRIORITY, \
&api_esp32_driver_api);
DT_INST_FOREACH_STATUS_OKAY(ESP32_ADC_INIT)