drivers/adc/adc_b91.c - third_party/github/zephyrproject-rtos/zephyr - Git at Google

 /*
  * Copyright (c) 2022 Telink Semiconductor
  *
  * SPDX-License-Identifier: Apache-2.0
  */

 #define DT_DRV_COMPAT telink_b91_adc

 /* Local driver headers */
 #define ADC_CONTEXT_USES_KERNEL_TIMER
 #include "adc_context.h"

 /* Zephyr Device Tree headers */
 #include <zephyr/dt-bindings/adc/b91-adc.h>

 /* Zephyr Logging headers */
 #include <zephyr/logging/log.h>
 LOG_MODULE_REGISTER(adc_b91, CONFIG_ADC_LOG_LEVEL);

 /* Telink HAL headers */
 #include <adc.h>

 /* ADC B91 defines */
 #define SIGN_BIT_POSITION          (13)
 #define AREG_ADC_DATA_STATUS       (0xf6)
 #define ADC_DATA_READY             BIT(0)

 /* B91 ADC driver data */
 struct b91_adc_data {
 	struct adc_context ctx;
 	int16_t *buffer;
 	int16_t *repeat_buffer;
 	uint8_t differential;
 	uint8_t resolution_divider;
 	struct k_sem acq_sem;
 	struct k_thread thread;

 	K_KERNEL_STACK_MEMBER(stack, CONFIG_ADC_B91_ACQUISITION_THREAD_STACK_SIZE);
 };

 struct b91_adc_cfg {
 	uint32_t sample_freq;
 	uint16_t vref_internal_mv;
 };

 /* Validate ADC data buffer size */
 static int adc_b91_validate_buffer_size(const struct adc_sequence *sequence)
 {
 	size_t needed = sizeof(int16_t);

 	if (sequence->options) {
 		needed *= (1 + sequence->options->extra_samplings);
 	}

 	if (sequence->buffer_size < needed) {
 		return -ENOMEM;
 	}

 	return 0;
 }

 /* Validate ADC read API input parameters */
 static int adc_b91_validate_sequence(const struct adc_sequence *sequence)
 {
 	int status;

 	if (sequence->channels != BIT(0)) {
 		LOG_ERR("Only channel 0 is supported.");
 		return -ENOTSUP;
 	}

 	if (sequence->oversampling) {
 		LOG_ERR("Oversampling is not supported.");
 		return -ENOTSUP;
 	}

 	status = adc_b91_validate_buffer_size(sequence);
 	if (status) {
 		LOG_ERR("Buffer size too small.");
 		return status;
 	}

 	return 0;
 }

 /* Convert dts pin to B91 SDK pin */
 static adc_input_pin_def_e adc_b91_get_pin(uint8_t dt_pin)
 {
 	adc_input_pin_def_e adc_pin;

 	switch (dt_pin) {
 	case DT_ADC_GPIO_PB0:
 		adc_pin = ADC_GPIO_PB0;
 		break;
 	case DT_ADC_GPIO_PB1:
 		adc_pin = ADC_GPIO_PB1;
 		break;
 	case DT_ADC_GPIO_PB2:
 		adc_pin = ADC_GPIO_PB2;
 		break;
 	case DT_ADC_GPIO_PB3:
 		adc_pin = ADC_GPIO_PB3;
 		break;
 	case DT_ADC_GPIO_PB4:
 		adc_pin = ADC_GPIO_PB4;
 		break;
 	case DT_ADC_GPIO_PB5:
 		adc_pin = ADC_GPIO_PB5;
 		break;
 	case DT_ADC_GPIO_PB6:
 		adc_pin = ADC_GPIO_PB6;
 		break;
 	case DT_ADC_GPIO_PB7:
 		adc_pin = ADC_GPIO_PB7;
 		break;
 	case DT_ADC_GPIO_PD0:
 		adc_pin = ADC_GPIO_PD0;
 		break;
 	case DT_ADC_GPIO_PD1:
 		adc_pin = ADC_GPIO_PD1;
 		break;
 	case DT_ADC_VBAT:
 		adc_pin = ADC_VBAT;
 		break;

 	default:
 		adc_pin = NOINPUTN;
 		break;
 	}

 	return adc_pin;
 }

 /* Get ADC value */
 static signed short adc_b91_get_code(void)
 {
 	signed short adc_code;

 	analog_write_reg8(areg_adc_data_sample_control,
 			  analog_read_reg8(areg_adc_data_sample_control) | FLD_NOT_SAMPLE_ADC_DATA);

 	adc_code = analog_read_reg16(areg_adc_misc_l);

 	analog_write_reg8(areg_adc_data_sample_control,
 		analog_read_reg8(areg_adc_data_sample_control) & (~FLD_NOT_SAMPLE_ADC_DATA));

 	return adc_code;
 }

 /* ADC Context API implementation: start sampling */
 static void adc_context_start_sampling(struct adc_context *ctx)
 {
 	struct b91_adc_data *data =
 		CONTAINER_OF(ctx, struct b91_adc_data, ctx);

 	data->repeat_buffer = data->buffer;

 	adc_power_on();

 	k_sem_give(&data->acq_sem);
 }

 /* ADC Context API implementation: buffer pointer */
 static void adc_context_update_buffer_pointer(struct adc_context *ctx, bool repeat_sampling)
 {
 	struct b91_adc_data *data =
 		CONTAINER_OF(ctx, struct b91_adc_data, ctx);

 	if (repeat_sampling) {
 		data->buffer = data->repeat_buffer;
 	}
 }

 /* Start ADC measurements */
 static int adc_b91_adc_start_read(const struct device *dev, const struct adc_sequence *sequence)
 {
 	int status;
 	struct b91_adc_data *data = dev->data;

 	/* Validate input parameters */
 	status = adc_b91_validate_sequence(sequence);
 	if (status != 0) {
 		return status;
 	}

 	/* Set resolution */
 	switch (sequence->resolution) {
 	case 14:
 		adc_set_resolution(ADC_RES14);
 		data->resolution_divider = 1;
 		break;
 	case 12:
 		adc_set_resolution(ADC_RES12);
 		data->resolution_divider = 4;
 		break;
 	case 10:
 		adc_set_resolution(ADC_RES10);
 		data->resolution_divider = 16;
 		break;
 	case 8:
 		adc_set_resolution(ADC_RES8);
 		data->resolution_divider = 64;
 		break;
 	default:
 		LOG_ERR("Selected ADC resolution is not supported.");
 		return -EINVAL;
 	}

 	/* Save buffer */
 	data->buffer = sequence->buffer;

 	/* Start ADC conversion */
 	adc_context_start_read(&data->ctx, sequence);

 	return adc_context_wait_for_completion(&data->ctx);
 }

 /* Main ADC Acquisition thread */
 static void adc_b91_acquisition_thread(void *p1, void *p2, void *p3)
 {
 	ARG_UNUSED(p2);
 	ARG_UNUSED(p3);

 	const struct device *dev = p1;
 	int16_t adc_code;
 	struct b91_adc_data *data = dev->data;

 	while (true) {
 		/* Wait for Acquisition semaphore */
 		k_sem_take(&data->acq_sem, K_FOREVER);

 		/* Wait for ADC data ready */
 		while ((analog_read_reg8(AREG_ADC_DATA_STATUS) & ADC_DATA_READY)
 				!= ADC_DATA_READY) {
 		}

 		/* Perform read */
 		adc_code = (adc_b91_get_code() / data->resolution_divider);
 		if (!data->differential) {
 			/* Sign bit is not used in case of single-ended configuration */
 			adc_code = adc_code * 2;

 			/* Do not return negative value for single-ended configuration */
 			if (adc_code < 0) {
 				adc_code = 0;
 			}
 		}
 		*data->buffer++ = adc_code;

 		/* Power off ADC */
 		adc_power_off();

 		/* Release ADC context */
 		adc_context_on_sampling_done(&data->ctx, dev);
 	}
 }

 /* ADC Driver initialization */
 static int adc_b91_init(const struct device *dev)
 {
 	struct b91_adc_data *data = dev->data;

 	k_sem_init(&data->acq_sem, 0, 1);

 	k_thread_create(&data->thread, data->stack,
 			CONFIG_ADC_B91_ACQUISITION_THREAD_STACK_SIZE,
 			adc_b91_acquisition_thread,
 			(void *)dev, NULL, NULL,
 			CONFIG_ADC_B91_ACQUISITION_THREAD_PRIO,
 			0, K_NO_WAIT);

 	adc_context_unlock_unconditionally(&data->ctx);

 	return 0;
 }

 /* API implementation: channel_setup */
 static int adc_b91_channel_setup(const struct device *dev,
 				 const struct adc_channel_cfg *channel_cfg)
 {
 	adc_ref_vol_e vref_internal_mv;
 	adc_sample_freq_e sample_freq;
 	adc_pre_scale_e pre_scale;
 	adc_sample_cycle_e sample_cycl;
 	adc_input_pin_def_e input_positive;
 	adc_input_pin_def_e input_negative;
 	struct b91_adc_data *data = dev->data;
 	const struct b91_adc_cfg *config = dev->config;

 	/* Check channel ID */
 	if (channel_cfg->channel_id > 0) {
 		LOG_ERR("Only channel 0 is supported.");
 		return -EINVAL;
 	}

 	/* Check reference */
 	if (channel_cfg->reference != ADC_REF_INTERNAL) {
 		LOG_ERR("Selected ADC reference is not supported.");
 		return -EINVAL;
 	}

 	/* Check internal reference */
 	switch (config->vref_internal_mv) {
 	case 900:
 		vref_internal_mv = ADC_VREF_0P9V;
 		break;
 	case 1200:
 		vref_internal_mv = ADC_VREF_1P2V;
 		break;
 	default:
 		LOG_ERR("Selected reference voltage is not supported.");
 		return -EINVAL;
 	}

 	/* Check sample frequency */
 	switch (config->sample_freq) {
 	case 23000:
 		sample_freq = ADC_SAMPLE_FREQ_23K;
 		break;
 	case 48000:
 		sample_freq = ADC_SAMPLE_FREQ_48K;
 		break;
 	case 96000:
 		sample_freq = ADC_SAMPLE_FREQ_96K;
 		break;
 	default:
 		LOG_ERR("Selected sample frequency is not supported.");
 		return -EINVAL;
 	}

 	/* Check gain */
 	switch (channel_cfg->gain) {
 	case ADC_GAIN_1:
 		pre_scale = ADC_PRESCALE_1;
 		break;
 	case ADC_GAIN_1_4:
 		pre_scale = ADC_PRESCALE_1F4;
 		break;
 	default:
 		LOG_ERR("Selected ADC gain is not supported.");
 		return -EINVAL;
 	}

 	/* Check acquisition time */
 	switch (channel_cfg->acquisition_time) {
 	case ADC_ACQ_TIME(ADC_ACQ_TIME_TICKS, 3):
 		sample_cycl = ADC_SAMPLE_CYC_3;
 		break;
 	case ADC_ACQ_TIME_DEFAULT:
 	case ADC_ACQ_TIME(ADC_ACQ_TIME_TICKS, 6):
 		sample_cycl = ADC_SAMPLE_CYC_6;
 		break;
 	case ADC_ACQ_TIME(ADC_ACQ_TIME_TICKS, 9):
 		sample_cycl = ADC_SAMPLE_CYC_9;
 		break;
 	case ADC_ACQ_TIME(ADC_ACQ_TIME_TICKS, 12):
 		sample_cycl = ADC_SAMPLE_CYC_12;
 		break;
 	case ADC_ACQ_TIME(ADC_ACQ_TIME_TICKS, 18):
 		sample_cycl = ADC_SAMPLE_CYC_18;
 		break;
 	case ADC_ACQ_TIME(ADC_ACQ_TIME_TICKS, 24):
 		sample_cycl = ADC_SAMPLE_CYC_24;
 		break;
 	case ADC_ACQ_TIME(ADC_ACQ_TIME_TICKS, 36):
 		sample_cycl = ADC_SAMPLE_CYC_36;
 		break;
 	case ADC_ACQ_TIME(ADC_ACQ_TIME_TICKS, 48):
 		sample_cycl = ADC_SAMPLE_CYC_48;
 		break;

 	default:
 		LOG_ERR("Selected ADC acquisition time is not supported.");
 		return -EINVAL;
 	}

 	/* Check for valid pins configuration */
 	input_positive = adc_b91_get_pin(channel_cfg->input_positive);
 	input_negative = adc_b91_get_pin(channel_cfg->input_negative);
 	if ((input_positive == (uint8_t)ADC_VBAT || input_negative == (uint8_t)ADC_VBAT) &&
 		channel_cfg->differential) {
 		LOG_ERR("VBAT pin is not available for differential mode.");
 		return -EINVAL;
 	} else if (channel_cfg->differential && (input_negative == (uint8_t)NOINPUTN)) {
 		LOG_ERR("Negative input is not selected.");
 		return -EINVAL;
 	}

 	/* Init ADC */
 	data->differential = channel_cfg->differential;
 	adc_init(vref_internal_mv, pre_scale, sample_freq);
 	adc_set_vbat_divider(ADC_VBAT_DIV_OFF);
 	adc_set_tsample_cycle(sample_cycl);

 	/* Init ADC Pins */
 	if (channel_cfg->differential) {
 		/* Differential pins configuration */
 		adc_pin_config(ADC_GPIO_MODE, input_positive);
 		adc_pin_config(ADC_GPIO_MODE, input_negative);
 		adc_set_diff_input(channel_cfg->input_positive, channel_cfg->input_negative);
 	} else if (input_positive == (uint8_t)ADC_VBAT) {
 		/* Single-ended Vbat pin configuration */
 		adc_set_diff_input(ADC_VBAT, GND);
 	} else {
 		/* Single-ended GPIO pin configuration */
 		adc_pin_config(ADC_GPIO_MODE, input_positive);
 		adc_set_diff_input(channel_cfg->input_positive, GND);
 	}

 	return 0;
 }

 /* API implementation: read */
 static int adc_b91_read(const struct device *dev,
 			const struct adc_sequence *sequence)
 {
 	int status;
 	struct b91_adc_data *data = dev->data;

 	adc_context_lock(&data->ctx, false, NULL);
 	status = adc_b91_adc_start_read(dev, sequence);
 	adc_context_release(&data->ctx, status);

 	return status;
 }

 #ifdef CONFIG_ADC_ASYNC
 /* API implementation: read_async */
 static int adc_b91_read_async(const struct device *dev,
 			      const struct adc_sequence *sequence,
 			      struct k_poll_signal *async)
 {
 	int status;
 	struct b91_adc_data *data = dev->data;

 	adc_context_lock(&data->ctx, true, async);
 	status = adc_b91_adc_start_read(dev, sequence);
 	adc_context_release(&data->ctx, status);

 	return status;
 }
 #endif /* CONFIG_ADC_ASYNC */

 static struct b91_adc_data data_0 = {
 	ADC_CONTEXT_INIT_TIMER(data_0, ctx),
 	ADC_CONTEXT_INIT_LOCK(data_0, ctx),
 	ADC_CONTEXT_INIT_SYNC(data_0, ctx),
 };

 static const struct b91_adc_cfg cfg_0 = {
 	.sample_freq = DT_INST_PROP(0, sample_freq),
 	.vref_internal_mv = DT_INST_PROP(0, vref_internal_mv),
 };

 static const struct adc_driver_api adc_b91_driver_api = {
 	.channel_setup = adc_b91_channel_setup,
 	.read = adc_b91_read,
 #ifdef CONFIG_ADC_ASYNC
 	.read_async = adc_b91_read_async,
 #endif
 	.ref_internal = cfg_0.vref_internal_mv,
 };

 DEVICE_DT_INST_DEFINE(0, adc_b91_init, NULL,
 		      &data_0,  &cfg_0,
 		      POST_KERNEL,
 		      CONFIG_ADC_INIT_PRIORITY,
 		      &adc_b91_driver_api);
	/*
	* Copyright (c) 2022 Telink Semiconductor
	*
	* SPDX-License-Identifier: Apache-2.0
	*/

	#define DT_DRV_COMPAT telink_b91_adc

	/* Local driver headers */
	#define ADC_CONTEXT_USES_KERNEL_TIMER
	#include "adc_context.h"

	/* Zephyr Device Tree headers */
	#include <zephyr/dt-bindings/adc/b91-adc.h>

	/* Zephyr Logging headers */
	#include <zephyr/logging/log.h>
	LOG_MODULE_REGISTER(adc_b91, CONFIG_ADC_LOG_LEVEL);

	/* Telink HAL headers */
	#include <adc.h>

	/* ADC B91 defines */
	#define SIGN_BIT_POSITION (13)
	#define AREG_ADC_DATA_STATUS (0xf6)
	#define ADC_DATA_READY BIT(0)

	/* B91 ADC driver data */
	struct b91_adc_data {
	struct adc_context ctx;
	int16_t *buffer;
	int16_t *repeat_buffer;
	uint8_t differential;
	uint8_t resolution_divider;
	struct k_sem acq_sem;
	struct k_thread thread;

	K_KERNEL_STACK_MEMBER(stack, CONFIG_ADC_B91_ACQUISITION_THREAD_STACK_SIZE);
	};

	struct b91_adc_cfg {
	uint32_t sample_freq;
	uint16_t vref_internal_mv;
	};

	/* Validate ADC data buffer size */
	static int adc_b91_validate_buffer_size(const struct adc_sequence *sequence)
	{
	size_t needed = sizeof(int16_t);

	if (sequence->options) {
	needed *= (1 + sequence->options->extra_samplings);
	}

	if (sequence->buffer_size < needed) {
	return -ENOMEM;
	}

	return 0;
	}

	/* Validate ADC read API input parameters */
	static int adc_b91_validate_sequence(const struct adc_sequence *sequence)
	{
	int status;

	if (sequence->channels != BIT(0)) {
	LOG_ERR("Only channel 0 is supported.");
	return -ENOTSUP;
	}

	if (sequence->oversampling) {
	LOG_ERR("Oversampling is not supported.");
	return -ENOTSUP;
	}

	status = adc_b91_validate_buffer_size(sequence);
	if (status) {
	LOG_ERR("Buffer size too small.");
	return status;
	}

	return 0;
	}

	/* Convert dts pin to B91 SDK pin */
	static adc_input_pin_def_e adc_b91_get_pin(uint8_t dt_pin)
	{
	adc_input_pin_def_e adc_pin;

	switch (dt_pin) {
	case DT_ADC_GPIO_PB0:
	adc_pin = ADC_GPIO_PB0;
	break;
	case DT_ADC_GPIO_PB1:
	adc_pin = ADC_GPIO_PB1;
	break;
	case DT_ADC_GPIO_PB2:
	adc_pin = ADC_GPIO_PB2;
	break;
	case DT_ADC_GPIO_PB3:
	adc_pin = ADC_GPIO_PB3;
	break;
	case DT_ADC_GPIO_PB4:
	adc_pin = ADC_GPIO_PB4;
	break;
	case DT_ADC_GPIO_PB5:
	adc_pin = ADC_GPIO_PB5;
	break;
	case DT_ADC_GPIO_PB6:
	adc_pin = ADC_GPIO_PB6;
	break;
	case DT_ADC_GPIO_PB7:
	adc_pin = ADC_GPIO_PB7;
	break;
	case DT_ADC_GPIO_PD0:
	adc_pin = ADC_GPIO_PD0;
	break;
	case DT_ADC_GPIO_PD1:
	adc_pin = ADC_GPIO_PD1;
	break;
	case DT_ADC_VBAT:
	adc_pin = ADC_VBAT;
	break;

	default:
	adc_pin = NOINPUTN;
	break;
	}

	return adc_pin;
	}

	/* Get ADC value */
	static signed short adc_b91_get_code(void)
	{
	signed short adc_code;

	analog_write_reg8(areg_adc_data_sample_control,
	analog_read_reg8(areg_adc_data_sample_control) \| FLD_NOT_SAMPLE_ADC_DATA);

	adc_code = analog_read_reg16(areg_adc_misc_l);

	analog_write_reg8(areg_adc_data_sample_control,
	analog_read_reg8(areg_adc_data_sample_control) & (~FLD_NOT_SAMPLE_ADC_DATA));

	return adc_code;
	}

	/* ADC Context API implementation: start sampling */
	static void adc_context_start_sampling(struct adc_context *ctx)
	{
	struct b91_adc_data *data =
	CONTAINER_OF(ctx, struct b91_adc_data, ctx);

	data->repeat_buffer = data->buffer;

	adc_power_on();

	k_sem_give(&data->acq_sem);
	}

	/* ADC Context API implementation: buffer pointer */
	static void adc_context_update_buffer_pointer(struct adc_context *ctx, bool repeat_sampling)
	{
	struct b91_adc_data *data =
	CONTAINER_OF(ctx, struct b91_adc_data, ctx);

	if (repeat_sampling) {
	data->buffer = data->repeat_buffer;
	}
	}

	/* Start ADC measurements */
	static int adc_b91_adc_start_read(const struct device dev, const struct adc_sequence sequence)
	{
	int status;
	struct b91_adc_data *data = dev->data;

	/* Validate input parameters */
	status = adc_b91_validate_sequence(sequence);
	if (status != 0) {
	return status;
	}

	/* Set resolution */
	switch (sequence->resolution) {
	case 14:
	adc_set_resolution(ADC_RES14);
	data->resolution_divider = 1;
	break;
	case 12:
	adc_set_resolution(ADC_RES12);
	data->resolution_divider = 4;
	break;
	case 10:
	adc_set_resolution(ADC_RES10);
	data->resolution_divider = 16;
	break;
	case 8:
	adc_set_resolution(ADC_RES8);
	data->resolution_divider = 64;
	break;
	default:
	LOG_ERR("Selected ADC resolution is not supported.");
	return -EINVAL;
	}

	/* Save buffer */
	data->buffer = sequence->buffer;

	/* Start ADC conversion */
	adc_context_start_read(&data->ctx, sequence);

	return adc_context_wait_for_completion(&data->ctx);
	}

	/* Main ADC Acquisition thread */
	static void adc_b91_acquisition_thread(void p1, void p2, void *p3)
	{
	ARG_UNUSED(p2);
	ARG_UNUSED(p3);

	const struct device *dev = p1;
	int16_t adc_code;
	struct b91_adc_data *data = dev->data;

	while (true) {
	/* Wait for Acquisition semaphore */
	k_sem_take(&data->acq_sem, K_FOREVER);

	/* Wait for ADC data ready */
	while ((analog_read_reg8(AREG_ADC_DATA_STATUS) & ADC_DATA_READY)
	!= ADC_DATA_READY) {
	}

	/* Perform read */
	adc_code = (adc_b91_get_code() / data->resolution_divider);
	if (!data->differential) {
	/* Sign bit is not used in case of single-ended configuration */
	adc_code = adc_code * 2;

	/* Do not return negative value for single-ended configuration */
	if (adc_code < 0) {
	adc_code = 0;
	}
	}
	*data->buffer++ = adc_code;

	/* Power off ADC */
	adc_power_off();

	/* Release ADC context */
	adc_context_on_sampling_done(&data->ctx, dev);
	}
	}

	/* ADC Driver initialization */
	static int adc_b91_init(const struct device *dev)
	{
	struct b91_adc_data *data = dev->data;

	k_sem_init(&data->acq_sem, 0, 1);

	k_thread_create(&data->thread, data->stack,
	CONFIG_ADC_B91_ACQUISITION_THREAD_STACK_SIZE,
	adc_b91_acquisition_thread,
	(void *)dev, NULL, NULL,
	CONFIG_ADC_B91_ACQUISITION_THREAD_PRIO,
	0, K_NO_WAIT);

	adc_context_unlock_unconditionally(&data->ctx);

	return 0;
	}

	/* API implementation: channel_setup */
	static int adc_b91_channel_setup(const struct device *dev,
	const struct adc_channel_cfg *channel_cfg)
	{
	adc_ref_vol_e vref_internal_mv;
	adc_sample_freq_e sample_freq;
	adc_pre_scale_e pre_scale;
	adc_sample_cycle_e sample_cycl;
	adc_input_pin_def_e input_positive;
	adc_input_pin_def_e input_negative;
	struct b91_adc_data *data = dev->data;
	const struct b91_adc_cfg *config = dev->config;

	/* Check channel ID */
	if (channel_cfg->channel_id > 0) {
	LOG_ERR("Only channel 0 is supported.");
	return -EINVAL;
	}

	/* Check reference */
	if (channel_cfg->reference != ADC_REF_INTERNAL) {
	LOG_ERR("Selected ADC reference is not supported.");
	return -EINVAL;
	}

	/* Check internal reference */
	switch (config->vref_internal_mv) {
	case 900:
	vref_internal_mv = ADC_VREF_0P9V;
	break;
	case 1200:
	vref_internal_mv = ADC_VREF_1P2V;
	break;
	default:
	LOG_ERR("Selected reference voltage is not supported.");
	return -EINVAL;
	}

	/* Check sample frequency */
	switch (config->sample_freq) {
	case 23000:
	sample_freq = ADC_SAMPLE_FREQ_23K;
	break;
	case 48000:
	sample_freq = ADC_SAMPLE_FREQ_48K;
	break;
	case 96000:
	sample_freq = ADC_SAMPLE_FREQ_96K;
	break;
	default:
	LOG_ERR("Selected sample frequency is not supported.");
	return -EINVAL;
	}

	/* Check gain */
	switch (channel_cfg->gain) {
	case ADC_GAIN_1:
	pre_scale = ADC_PRESCALE_1;
	break;
	case ADC_GAIN_1_4:
	pre_scale = ADC_PRESCALE_1F4;
	break;
	default:
	LOG_ERR("Selected ADC gain is not supported.");
	return -EINVAL;
	}

	/* Check acquisition time */
	switch (channel_cfg->acquisition_time) {
	case ADC_ACQ_TIME(ADC_ACQ_TIME_TICKS, 3):
	sample_cycl = ADC_SAMPLE_CYC_3;
	break;
	case ADC_ACQ_TIME_DEFAULT:
	case ADC_ACQ_TIME(ADC_ACQ_TIME_TICKS, 6):
	sample_cycl = ADC_SAMPLE_CYC_6;
	break;
	case ADC_ACQ_TIME(ADC_ACQ_TIME_TICKS, 9):
	sample_cycl = ADC_SAMPLE_CYC_9;
	break;
	case ADC_ACQ_TIME(ADC_ACQ_TIME_TICKS, 12):
	sample_cycl = ADC_SAMPLE_CYC_12;
	break;
	case ADC_ACQ_TIME(ADC_ACQ_TIME_TICKS, 18):
	sample_cycl = ADC_SAMPLE_CYC_18;
	break;
	case ADC_ACQ_TIME(ADC_ACQ_TIME_TICKS, 24):
	sample_cycl = ADC_SAMPLE_CYC_24;
	break;
	case ADC_ACQ_TIME(ADC_ACQ_TIME_TICKS, 36):
	sample_cycl = ADC_SAMPLE_CYC_36;
	break;
	case ADC_ACQ_TIME(ADC_ACQ_TIME_TICKS, 48):
	sample_cycl = ADC_SAMPLE_CYC_48;
	break;

	default:
	LOG_ERR("Selected ADC acquisition time is not supported.");
	return -EINVAL;
	}

	/* Check for valid pins configuration */
	input_positive = adc_b91_get_pin(channel_cfg->input_positive);
	input_negative = adc_b91_get_pin(channel_cfg->input_negative);
	if ((input_positive == (uint8_t)ADC_VBAT \|\| input_negative == (uint8_t)ADC_VBAT) &&
	channel_cfg->differential) {
	LOG_ERR("VBAT pin is not available for differential mode.");
	return -EINVAL;
	} else if (channel_cfg->differential && (input_negative == (uint8_t)NOINPUTN)) {
	LOG_ERR("Negative input is not selected.");
	return -EINVAL;
	}

	/* Init ADC */
	data->differential = channel_cfg->differential;
	adc_init(vref_internal_mv, pre_scale, sample_freq);
	adc_set_vbat_divider(ADC_VBAT_DIV_OFF);
	adc_set_tsample_cycle(sample_cycl);

	/* Init ADC Pins */
	if (channel_cfg->differential) {
	/* Differential pins configuration */
	adc_pin_config(ADC_GPIO_MODE, input_positive);
	adc_pin_config(ADC_GPIO_MODE, input_negative);
	adc_set_diff_input(channel_cfg->input_positive, channel_cfg->input_negative);
	} else if (input_positive == (uint8_t)ADC_VBAT) {
	/* Single-ended Vbat pin configuration */
	adc_set_diff_input(ADC_VBAT, GND);
	} else {
	/* Single-ended GPIO pin configuration */
	adc_pin_config(ADC_GPIO_MODE, input_positive);
	adc_set_diff_input(channel_cfg->input_positive, GND);
	}

	return 0;
	}

	/* API implementation: read */
	static int adc_b91_read(const struct device *dev,
	const struct adc_sequence *sequence)
	{
	int status;
	struct b91_adc_data *data = dev->data;

	adc_context_lock(&data->ctx, false, NULL);
	status = adc_b91_adc_start_read(dev, sequence);
	adc_context_release(&data->ctx, status);

	return status;
	}

	#ifdef CONFIG_ADC_ASYNC
	/* API implementation: read_async */
	static int adc_b91_read_async(const struct device *dev,
	const struct adc_sequence *sequence,
	struct k_poll_signal *async)
	{
	int status;
	struct b91_adc_data *data = dev->data;

	adc_context_lock(&data->ctx, true, async);
	status = adc_b91_adc_start_read(dev, sequence);
	adc_context_release(&data->ctx, status);

	return status;
	}
	#endif /* CONFIG_ADC_ASYNC */

	static struct b91_adc_data data_0 = {
	ADC_CONTEXT_INIT_TIMER(data_0, ctx),
	ADC_CONTEXT_INIT_LOCK(data_0, ctx),
	ADC_CONTEXT_INIT_SYNC(data_0, ctx),
	};

	static const struct b91_adc_cfg cfg_0 = {
	.sample_freq = DT_INST_PROP(0, sample_freq),
	.vref_internal_mv = DT_INST_PROP(0, vref_internal_mv),
	};

	static const struct adc_driver_api adc_b91_driver_api = {
	.channel_setup = adc_b91_channel_setup,
	.read = adc_b91_read,
	#ifdef CONFIG_ADC_ASYNC
	.read_async = adc_b91_read_async,
	#endif
	.ref_internal = cfg_0.vref_internal_mv,
	};

	DEVICE_DT_INST_DEFINE(0, adc_b91_init, NULL,
	&data_0, &cfg_0,
	POST_KERNEL,
	CONFIG_ADC_INIT_PRIORITY,
	&adc_b91_driver_api);