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* Copyright (c) 2018 Nordic Semiconductor ASA
*
* SPDX-License-Identifier: Apache-2.0
*/
#define ADC_CONTEXT_USES_KERNEL_TIMER
#include "adc_context.h"
#include <hal/nrf_saadc.h>
#define LOG_LEVEL CONFIG_ADC_LOG_LEVEL
#include <logging/log.h>
LOG_MODULE_REGISTER(adc_nrfx_saadc);
#define DT_DRV_COMPAT nordic_nrf_saadc
struct driver_data {
struct adc_context ctx;
uint8_t positive_inputs[SAADC_CH_NUM];
};
static struct driver_data m_data = {
ADC_CONTEXT_INIT_TIMER(m_data, ctx),
ADC_CONTEXT_INIT_LOCK(m_data, ctx),
ADC_CONTEXT_INIT_SYNC(m_data, ctx),
};
/* Implementation of the ADC driver API function: adc_channel_setup. */
static int adc_nrfx_channel_setup(const struct device *dev,
const struct adc_channel_cfg *channel_cfg)
{
nrf_saadc_channel_config_t config = {
.resistor_p = NRF_SAADC_RESISTOR_DISABLED,
.resistor_n = NRF_SAADC_RESISTOR_DISABLED,
.burst = NRF_SAADC_BURST_DISABLED,
};
uint8_t channel_id = channel_cfg->channel_id;
if (channel_id >= SAADC_CH_NUM) {
return -EINVAL;
}
switch (channel_cfg->gain) {
case ADC_GAIN_1_6:
config.gain = NRF_SAADC_GAIN1_6;
break;
case ADC_GAIN_1_5:
config.gain = NRF_SAADC_GAIN1_5;
break;
case ADC_GAIN_1_4:
config.gain = NRF_SAADC_GAIN1_4;
break;
case ADC_GAIN_1_3:
config.gain = NRF_SAADC_GAIN1_3;
break;
case ADC_GAIN_1_2:
config.gain = NRF_SAADC_GAIN1_2;
break;
case ADC_GAIN_1:
config.gain = NRF_SAADC_GAIN1;
break;
case ADC_GAIN_2:
config.gain = NRF_SAADC_GAIN2;
break;
case ADC_GAIN_4:
config.gain = NRF_SAADC_GAIN4;
break;
default:
LOG_ERR("Selected ADC gain is not valid");
return -EINVAL;
}
switch (channel_cfg->reference) {
case ADC_REF_INTERNAL:
config.reference = NRF_SAADC_REFERENCE_INTERNAL;
break;
case ADC_REF_VDD_1_4:
config.reference = NRF_SAADC_REFERENCE_VDD4;
break;
default:
LOG_ERR("Selected ADC reference is not valid");
return -EINVAL;
}
switch (channel_cfg->acquisition_time) {
case ADC_ACQ_TIME(ADC_ACQ_TIME_MICROSECONDS, 3):
config.acq_time = NRF_SAADC_ACQTIME_3US;
break;
case ADC_ACQ_TIME(ADC_ACQ_TIME_MICROSECONDS, 5):
config.acq_time = NRF_SAADC_ACQTIME_5US;
break;
case ADC_ACQ_TIME_DEFAULT:
case ADC_ACQ_TIME(ADC_ACQ_TIME_MICROSECONDS, 10):
config.acq_time = NRF_SAADC_ACQTIME_10US;
break;
case ADC_ACQ_TIME(ADC_ACQ_TIME_MICROSECONDS, 15):
config.acq_time = NRF_SAADC_ACQTIME_15US;
break;
case ADC_ACQ_TIME(ADC_ACQ_TIME_MICROSECONDS, 20):
config.acq_time = NRF_SAADC_ACQTIME_20US;
break;
case ADC_ACQ_TIME(ADC_ACQ_TIME_MICROSECONDS, 40):
config.acq_time = NRF_SAADC_ACQTIME_40US;
break;
default:
LOG_ERR("Selected ADC acquisition time is not valid");
return -EINVAL;
}
config.mode = (channel_cfg->differential ?
NRF_SAADC_MODE_DIFFERENTIAL : NRF_SAADC_MODE_SINGLE_ENDED);
/* Keep the channel disabled in hardware (set positive input to
* NRF_SAADC_INPUT_DISABLED) until it is selected to be included
* in a sampling sequence.
*/
nrf_saadc_channel_init(NRF_SAADC, channel_id, &config);
nrf_saadc_channel_input_set(NRF_SAADC,
channel_id,
NRF_SAADC_INPUT_DISABLED,
channel_cfg->input_negative);
/* Store the positive input selection in a dedicated array,
* to get it later when the channel is selected for a sampling
* and to mark the channel as configured (ready to be selected).
*/
m_data.positive_inputs[channel_id] = channel_cfg->input_positive;
return 0;
}
static void adc_context_start_sampling(struct adc_context *ctx)
{
nrf_saadc_enable(NRF_SAADC);
if (ctx->sequence.calibrate) {
nrf_saadc_task_trigger(NRF_SAADC,
NRF_SAADC_TASK_CALIBRATEOFFSET);
} else {
nrf_saadc_task_trigger(NRF_SAADC, NRF_SAADC_TASK_START);
nrf_saadc_task_trigger(NRF_SAADC, NRF_SAADC_TASK_SAMPLE);
}
}
static void adc_context_update_buffer_pointer(struct adc_context *ctx,
bool repeat)
{
ARG_UNUSED(ctx);
if (!repeat) {
nrf_saadc_buffer_pointer_set(
NRF_SAADC,
nrf_saadc_buffer_pointer_get(NRF_SAADC) +
nrf_saadc_amount_get(NRF_SAADC));
}
}
static int set_resolution(const struct adc_sequence *sequence)
{
nrf_saadc_resolution_t nrf_resolution;
switch (sequence->resolution) {
case 8:
nrf_resolution = NRF_SAADC_RESOLUTION_8BIT;
break;
case 10:
nrf_resolution = NRF_SAADC_RESOLUTION_10BIT;
break;
case 12:
nrf_resolution = NRF_SAADC_RESOLUTION_12BIT;
break;
case 14:
nrf_resolution = NRF_SAADC_RESOLUTION_14BIT;
break;
default:
LOG_ERR("ADC resolution value %d is not valid",
sequence->resolution);
return -EINVAL;
}
nrf_saadc_resolution_set(NRF_SAADC, nrf_resolution);
return 0;
}
static int set_oversampling(const struct adc_sequence *sequence,
uint8_t active_channels)
{
nrf_saadc_oversample_t nrf_oversampling;
if ((active_channels > 1) && (sequence->oversampling > 0)) {
LOG_ERR(
"Oversampling is supported for single channel only");
return -EINVAL;
}
switch (sequence->oversampling) {
case 0:
nrf_oversampling = NRF_SAADC_OVERSAMPLE_DISABLED;
break;
case 1:
nrf_oversampling = NRF_SAADC_OVERSAMPLE_2X;
break;
case 2:
nrf_oversampling = NRF_SAADC_OVERSAMPLE_4X;
break;
case 3:
nrf_oversampling = NRF_SAADC_OVERSAMPLE_8X;
break;
case 4:
nrf_oversampling = NRF_SAADC_OVERSAMPLE_16X;
break;
case 5:
nrf_oversampling = NRF_SAADC_OVERSAMPLE_32X;
break;
case 6:
nrf_oversampling = NRF_SAADC_OVERSAMPLE_64X;
break;
case 7:
nrf_oversampling = NRF_SAADC_OVERSAMPLE_128X;
break;
case 8:
nrf_oversampling = NRF_SAADC_OVERSAMPLE_256X;
break;
default:
LOG_ERR("Oversampling value %d is not valid",
sequence->oversampling);
return -EINVAL;
}
nrf_saadc_oversample_set(NRF_SAADC, nrf_oversampling);
return 0;
}
static int check_buffer_size(const struct adc_sequence *sequence,
uint8_t active_channels)
{
size_t needed_buffer_size;
needed_buffer_size = active_channels * sizeof(nrf_saadc_value_t);
if (sequence->options) {
needed_buffer_size *= (1 + sequence->options->extra_samplings);
}
if (sequence->buffer_size < needed_buffer_size) {
LOG_ERR("Provided buffer is too small (%u/%u)",
sequence->buffer_size, needed_buffer_size);
return -ENOMEM;
}
return 0;
}
static int start_read(const struct device *dev,
const struct adc_sequence *sequence)
{
int error;
uint32_t selected_channels = sequence->channels;
uint8_t active_channels;
uint8_t channel_id;
/* Signal an error if channel selection is invalid (no channels or
* a non-existing one is selected).
*/
if (!selected_channels ||
(selected_channels & ~BIT_MASK(SAADC_CH_NUM))) {
LOG_ERR("Invalid selection of channels");
return -EINVAL;
}
active_channels = 0U;
/* Enable only the channels selected for the pointed sequence.
* Disable all the rest.
*/
channel_id = 0U;
do {
if (selected_channels & BIT(channel_id)) {
/* Signal an error if a selected channel has not been
* configured yet.
*/
if (m_data.positive_inputs[channel_id] == 0U) {
LOG_ERR("Channel %u not configured",
channel_id);
return -EINVAL;
}
/* When oversampling is used, the burst mode needs to
* be activated. Unfortunately, this mode cannot be
* activated permanently in the channel setup, because
* then the multiple channel sampling fails (the END
* event is not generated) after switching to a single
* channel sampling and back. Thus, when oversampling
* is not used (hence, the multiple channel sampling is
* possible), the burst mode have to be deactivated.
*/
nrf_saadc_burst_set(NRF_SAADC, channel_id,
(sequence->oversampling != 0U ?
NRF_SAADC_BURST_ENABLED :
NRF_SAADC_BURST_DISABLED));
nrf_saadc_channel_pos_input_set(
NRF_SAADC,
channel_id,
m_data.positive_inputs[channel_id]);
++active_channels;
} else {
nrf_saadc_channel_pos_input_set(
NRF_SAADC,
channel_id,
NRF_SAADC_INPUT_DISABLED);
}
} while (++channel_id < SAADC_CH_NUM);
error = set_resolution(sequence);
if (error) {
return error;
}
error = set_oversampling(sequence, active_channels);
if (error) {
return error;
}
error = check_buffer_size(sequence, active_channels);
if (error) {
return error;
}
nrf_saadc_buffer_init(NRF_SAADC,
(nrf_saadc_value_t *)sequence->buffer,
active_channels);
adc_context_start_read(&m_data.ctx, sequence);
error = adc_context_wait_for_completion(&m_data.ctx);
return error;
}
/* Implementation of the ADC driver API function: adc_read. */
static int adc_nrfx_read(const struct device *dev,
const struct adc_sequence *sequence)
{
int error;
adc_context_lock(&m_data.ctx, false, NULL);
error = start_read(dev, sequence);
adc_context_release(&m_data.ctx, error);
return error;
}
#ifdef CONFIG_ADC_ASYNC
/* Implementation of the ADC driver API function: adc_read_async. */
static int adc_nrfx_read_async(const struct device *dev,
const struct adc_sequence *sequence,
struct k_poll_signal *async)
{
int error;
adc_context_lock(&m_data.ctx, true, async);
error = start_read(dev, sequence);
adc_context_release(&m_data.ctx, error);
return error;
}
#endif /* CONFIG_ADC_ASYNC */
static void saadc_irq_handler(const struct device *dev)
{
if (nrf_saadc_event_check(NRF_SAADC, NRF_SAADC_EVENT_END)) {
nrf_saadc_event_clear(NRF_SAADC, NRF_SAADC_EVENT_END);
nrf_saadc_task_trigger(NRF_SAADC, NRF_SAADC_TASK_STOP);
nrf_saadc_disable(NRF_SAADC);
adc_context_on_sampling_done(&m_data.ctx, dev);
} else if (nrf_saadc_event_check(NRF_SAADC,
NRF_SAADC_EVENT_CALIBRATEDONE)) {
nrf_saadc_event_clear(NRF_SAADC, NRF_SAADC_EVENT_CALIBRATEDONE);
/*
* The workaround for Nordic nRF52832 anomalies 86 and
* 178 is an explicit STOP after CALIBRATEOFFSET
* before issuing START.
*/
nrf_saadc_task_trigger(NRF_SAADC, NRF_SAADC_TASK_STOP);
nrf_saadc_task_trigger(NRF_SAADC, NRF_SAADC_TASK_START);
nrf_saadc_task_trigger(NRF_SAADC, NRF_SAADC_TASK_SAMPLE);
}
}
static int init_saadc(const struct device *dev)
{
nrf_saadc_event_clear(NRF_SAADC, NRF_SAADC_EVENT_END);
nrf_saadc_event_clear(NRF_SAADC, NRF_SAADC_EVENT_CALIBRATEDONE);
nrf_saadc_int_enable(NRF_SAADC,
NRF_SAADC_INT_END | NRF_SAADC_INT_CALIBRATEDONE);
NRFX_IRQ_ENABLE(DT_INST_IRQN(0));
IRQ_CONNECT(DT_INST_IRQN(0), DT_INST_IRQ(0, priority),
saadc_irq_handler, DEVICE_DT_INST_GET(0), 0);
adc_context_unlock_unconditionally(&m_data.ctx);
return 0;
}
static const struct adc_driver_api adc_nrfx_driver_api = {
.channel_setup = adc_nrfx_channel_setup,
.read = adc_nrfx_read,
#ifdef CONFIG_ADC_ASYNC
.read_async = adc_nrfx_read_async,
#endif
.ref_internal = 600,
};
/*
* There is only one instance on supported SoCs, so inst is guaranteed
* to be 0 if any instance is okay. (We use adc_0 above, so the driver
* is relying on the numeric instance value in a way that happens to
* be safe.)
*
* Just in case that assumption becomes invalid in the future, we use
* a BUILD_ASSERT().
*/
#define SAADC_INIT(inst) \
BUILD_ASSERT((inst) == 0, \
"multiple instances not supported"); \
DEVICE_DT_INST_DEFINE(0, \
init_saadc, \
NULL, \
NULL, \
NULL, \
POST_KERNEL, \
CONFIG_KERNEL_INIT_PRIORITY_DEVICE, \
&adc_nrfx_driver_api);
DT_INST_FOREACH_STATUS_OKAY(SAADC_INIT)
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