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/**
* @file
*
* @brief Emulated ADC driver
*/
/*
* Copyright 2021 Google LLC
*
* SPDX-License-Identifier: Apache-2.0
*/
#define DT_DRV_COMPAT zephyr_adc_emul
#include <zephyr/drivers/adc.h>
#include <zephyr/drivers/adc/adc_emul.h>
#include <zephyr/kernel.h>
#include <zephyr/logging/log.h>
#include <zephyr/sys/byteorder.h>
#include <zephyr/sys/util.h>
LOG_MODULE_REGISTER(adc_emul, CONFIG_ADC_LOG_LEVEL);
#define ADC_CONTEXT_USES_KERNEL_TIMER
#include "adc_context.h"
#define ADC_EMUL_MAX_RESOLUTION 16
typedef uint16_t adc_emul_res_t;
enum adc_emul_input_source {
ADC_EMUL_CONST_VALUE,
ADC_EMUL_CUSTOM_FUNC,
};
/**
* @brief Channel of emulated ADC config
*
* This structure contains configuration of one channel of emulated ADC.
*/
struct adc_emul_chan_cfg {
/** Pointer to function used to obtain input mV */
adc_emul_value_func func;
/** Pointer to data that are passed to @a func on call */
void *func_data;
/** Constant mV input value */
uint32_t const_value;
/** Gain used on output value */
enum adc_gain gain;
/** Reference source */
enum adc_reference ref;
/** Input source which is used to obtain input value */
enum adc_emul_input_source input;
};
/**
* @brief Emulated ADC config
*
* This structure contains constant data for given instance of emulated ADC.
*/
struct adc_emul_config {
/** Number of supported channels */
uint8_t num_channels;
};
/**
* @brief Emulated ADC data
*
* This structure contains data structures used by a emulated ADC.
*/
struct adc_emul_data {
/** Structure that handle state of ongoing read operation */
struct adc_context ctx;
/** Pointer to ADC emulator own device structure */
const struct device *dev;
/** Pointer to memory where next sample will be written */
uint16_t *buf;
/** Pointer to where will be data stored in case of repeated sampling */
uint16_t *repeat_buf;
/** Mask with channels that will be sampled */
uint32_t channels;
/** Mask created from requested resolution in read operation */
uint16_t res_mask;
/** Reference voltage for ADC_REF_VDD_1 source */
uint16_t ref_vdd;
/** Reference voltage for ADC_REF_EXTERNAL0 source */
uint16_t ref_ext0;
/** Reference voltage for ADC_REF_EXTERNAL1 source */
uint16_t ref_ext1;
/** Reference voltage for ADC_REF_INTERNAL source */
uint16_t ref_int;
/** Array of each channel configuration */
struct adc_emul_chan_cfg *chan_cfg;
/** Structure used for acquisition thread */
struct k_thread thread;
/** Semaphore used to control acquisition thread */
struct k_sem sem;
/** Mutex used to control access to channels config and ref voltages */
struct k_mutex cfg_mtx;
/** Stack for acquisition thread */
K_KERNEL_STACK_MEMBER(stack,
CONFIG_ADC_EMUL_ACQUISITION_THREAD_STACK_SIZE);
};
int adc_emul_const_value_set(const struct device *dev, unsigned int chan,
uint32_t value)
{
const struct adc_emul_config *config = dev->config;
struct adc_emul_data *data = dev->data;
struct adc_emul_chan_cfg *chan_cfg;
if (chan >= config->num_channels) {
LOG_ERR("unsupported channel %d", chan);
return -EINVAL;
}
chan_cfg = &data->chan_cfg[chan];
k_mutex_lock(&data->cfg_mtx, K_FOREVER);
chan_cfg->input = ADC_EMUL_CONST_VALUE;
chan_cfg->const_value = value;
k_mutex_unlock(&data->cfg_mtx);
return 0;
}
int adc_emul_value_func_set(const struct device *dev, unsigned int chan,
adc_emul_value_func func, void *func_data)
{
const struct adc_emul_config *config = dev->config;
struct adc_emul_data *data = dev->data;
struct adc_emul_chan_cfg *chan_cfg;
if (chan >= config->num_channels) {
LOG_ERR("unsupported channel %d", chan);
return -EINVAL;
}
chan_cfg = &data->chan_cfg[chan];
k_mutex_lock(&data->cfg_mtx, K_FOREVER);
chan_cfg->func = func;
chan_cfg->func_data = func_data;
chan_cfg->input = ADC_EMUL_CUSTOM_FUNC;
k_mutex_unlock(&data->cfg_mtx);
return 0;
}
int adc_emul_ref_voltage_set(const struct device *dev, enum adc_reference ref,
uint16_t value)
{
struct adc_driver_api *api = (struct adc_driver_api *)dev->api;
struct adc_emul_data *data = dev->data;
int err = 0;
k_mutex_lock(&data->cfg_mtx, K_FOREVER);
switch (ref) {
case ADC_REF_VDD_1:
data->ref_vdd = value;
break;
case ADC_REF_INTERNAL:
data->ref_int = value;
api->ref_internal = value;
break;
case ADC_REF_EXTERNAL0:
data->ref_ext0 = value;
break;
case ADC_REF_EXTERNAL1:
data->ref_ext1 = value;
break;
default:
err = -EINVAL;
}
k_mutex_unlock(&data->cfg_mtx);
return err;
}
/**
* @brief Convert @p ref to reference voltage value in mV
*
* @param data Internal data of ADC emulator
* @param ref Select which reference source should be used
*
* @return Reference voltage in mV
* @return 0 on error
*/
static uint16_t adc_emul_get_ref_voltage(struct adc_emul_data *data,
enum adc_reference ref)
{
uint16_t voltage;
k_mutex_lock(&data->cfg_mtx, K_FOREVER);
switch (ref) {
case ADC_REF_VDD_1:
voltage = data->ref_vdd;
break;
case ADC_REF_VDD_1_2:
voltage = data->ref_vdd / 2;
break;
case ADC_REF_VDD_1_3:
voltage = data->ref_vdd / 3;
break;
case ADC_REF_VDD_1_4:
voltage = data->ref_vdd / 4;
break;
case ADC_REF_INTERNAL:
voltage = data->ref_int;
break;
case ADC_REF_EXTERNAL0:
voltage = data->ref_ext0;
break;
case ADC_REF_EXTERNAL1:
voltage = data->ref_ext1;
break;
default:
voltage = 0;
}
k_mutex_unlock(&data->cfg_mtx);
return voltage;
}
static int adc_emul_channel_setup(const struct device *dev,
const struct adc_channel_cfg *channel_cfg)
{
const struct adc_emul_config *config = dev->config;
struct adc_emul_chan_cfg *emul_chan_cfg;
struct adc_emul_data *data = dev->data;
if (channel_cfg->channel_id >= config->num_channels) {
LOG_ERR("unsupported channel id '%d'", channel_cfg->channel_id);
return -ENOTSUP;
}
if (adc_emul_get_ref_voltage(data, channel_cfg->reference) == 0) {
LOG_ERR("unsupported channel reference '%d'",
channel_cfg->reference);
return -ENOTSUP;
}
if (channel_cfg->differential) {
LOG_ERR("unsupported differential mode");
return -ENOTSUP;
}
emul_chan_cfg = &data->chan_cfg[channel_cfg->channel_id];
k_mutex_lock(&data->cfg_mtx, K_FOREVER);
emul_chan_cfg->gain = channel_cfg->gain;
emul_chan_cfg->ref = channel_cfg->reference;
k_mutex_unlock(&data->cfg_mtx);
return 0;
}
/**
* @brief Check if buffer in @p sequence is big enough to hold all ADC samples
*
* @param dev ADC emulator device
* @param sequence ADC sequence description
*
* @return 0 on success
* @return -ENOMEM if buffer is not big enough
*/
static int adc_emul_check_buffer_size(const struct device *dev,
const struct adc_sequence *sequence)
{
const struct adc_emul_config *config = dev->config;
uint8_t channels = 0;
size_t needed;
uint32_t mask;
for (mask = BIT(config->num_channels - 1); mask != 0; mask >>= 1) {
if (mask & sequence->channels) {
channels++;
}
}
needed = channels * sizeof(adc_emul_res_t);
if (sequence->options) {
needed *= (1 + sequence->options->extra_samplings);
}
if (sequence->buffer_size < needed) {
return -ENOMEM;
}
return 0;
}
/**
* @brief Start processing read request
*
* @param dev ADC emulator device
* @param sequence ADC sequence description
*
* @return 0 on success
* @return -ENOTSUP if requested resolution or channel is out side of supported
* range
* @return -ENOMEM if buffer is not big enough
* (see @ref adc_emul_check_buffer_size)
* @return other error code returned by adc_context_wait_for_completion
*/
static int adc_emul_start_read(const struct device *dev,
const struct adc_sequence *sequence)
{
const struct adc_emul_config *config = dev->config;
struct adc_emul_data *data = dev->data;
int err;
if (sequence->resolution > ADC_EMUL_MAX_RESOLUTION ||
sequence->resolution == 0) {
LOG_ERR("unsupported resolution %d", sequence->resolution);
return -ENOTSUP;
}
if (find_msb_set(sequence->channels) > config->num_channels) {
LOG_ERR("unsupported channels in mask: 0x%08x",
sequence->channels);
return -ENOTSUP;
}
err = adc_emul_check_buffer_size(dev, sequence);
if (err) {
LOG_ERR("buffer size too small");
return err;
}
data->res_mask = BIT_MASK(sequence->resolution);
data->buf = sequence->buffer;
adc_context_start_read(&data->ctx, sequence);
return adc_context_wait_for_completion(&data->ctx);
}
static int adc_emul_read_async(const struct device *dev,
const struct adc_sequence *sequence,
struct k_poll_signal *async)
{
struct adc_emul_data *data = dev->data;
int err;
adc_context_lock(&data->ctx, async ? true : false, async);
err = adc_emul_start_read(dev, sequence);
adc_context_release(&data->ctx, err);
return err;
}
static int adc_emul_read(const struct device *dev,
const struct adc_sequence *sequence)
{
return adc_emul_read_async(dev, sequence, NULL);
}
static void adc_context_start_sampling(struct adc_context *ctx)
{
struct adc_emul_data *data = CONTAINER_OF(ctx, struct adc_emul_data,
ctx);
data->channels = ctx->sequence.channels;
data->repeat_buf = data->buf;
k_sem_give(&data->sem);
}
static void adc_context_update_buffer_pointer(struct adc_context *ctx,
bool repeat_sampling)
{
struct adc_emul_data *data = CONTAINER_OF(ctx, struct adc_emul_data,
ctx);
if (repeat_sampling) {
data->buf = data->repeat_buf;
}
}
/**
* @brief Convert input voltage of ADC @p chan to raw output value
*
* @param data Internal data of ADC emulator
* @param chan ADC channel to sample
* @param result Raw output value
*
* @return 0 on success
* @return -EINVAL if failed to get reference voltage or unknown input is
* selected
* @return other error code returned by custom function
*/
static int adc_emul_get_chan_value(struct adc_emul_data *data,
unsigned int chan,
adc_emul_res_t *result)
{
struct adc_emul_chan_cfg *chan_cfg = &data->chan_cfg[chan];
uint32_t input_mV;
uint32_t ref_v;
uint64_t temp; /* Temporary 64 bit value prevent overflows */
int err = 0;
k_mutex_lock(&data->cfg_mtx, K_FOREVER);
/* Get input voltage */
switch (chan_cfg->input) {
case ADC_EMUL_CONST_VALUE:
input_mV = chan_cfg->const_value;
break;
case ADC_EMUL_CUSTOM_FUNC:
err = chan_cfg->func(data->dev, chan, chan_cfg->func_data,
&input_mV);
if (err) {
LOG_ERR("failed to read channel %d (err %d)",
chan, err);
goto out;
}
break;
default:
LOG_ERR("unknown input source %d", chan_cfg->input);
err = -EINVAL;
goto out;
}
/* Get reference voltage and apply inverted gain */
ref_v = adc_emul_get_ref_voltage(data, chan_cfg->ref);
err = adc_gain_invert(chan_cfg->gain, &ref_v);
if (ref_v == 0 || err) {
LOG_ERR("failed to get ref voltage (channel %d)", chan);
err = -EINVAL;
goto out;
}
/* Calculate output value */
temp = (uint64_t)input_mV * data->res_mask / ref_v;
/* If output value is greater than resolution, it has to be trimmed */
if (temp > data->res_mask) {
temp = data->res_mask;
}
*result = temp;
out:
k_mutex_unlock(&data->cfg_mtx);
return err;
}
/**
* @brief Main function of thread which is used to collect samples from
* emulated ADC. When adc_context_start_sampling give semaphore,
* for each requested channel value function is called. Returned
* mV value is converted to output using reference voltage, gain
* and requested resolution.
*
* @param data Internal data of ADC emulator
*
* @return This thread should not end
*/
static void adc_emul_acquisition_thread(struct adc_emul_data *data)
{
int err;
while (true) {
k_sem_take(&data->sem, K_FOREVER);
err = 0;
while (data->channels) {
adc_emul_res_t result = 0;
unsigned int chan = find_lsb_set(data->channels) - 1;
LOG_DBG("reading channel %d", chan);
err = adc_emul_get_chan_value(data, chan, &result);
if (err) {
adc_context_complete(&data->ctx, err);
break;
}
LOG_DBG("read channel %d, result = %d", chan, result);
*data->buf++ = result;
WRITE_BIT(data->channels, chan, 0);
}
if (!err) {
adc_context_on_sampling_done(&data->ctx, data->dev);
}
}
}
/**
* @brief Function called on init for each ADC emulator device. It setups all
* channels to return constant 0 mV and create acquisition thread.
*
* @param dev ADC emulator device
*
* @return 0 on success
*/
static int adc_emul_init(const struct device *dev)
{
const struct adc_emul_config *config = dev->config;
struct adc_emul_data *data = dev->data;
int chan;
data->dev = dev;
k_sem_init(&data->sem, 0, 1);
k_mutex_init(&data->cfg_mtx);
for (chan = 0; chan < config->num_channels; chan++) {
struct adc_emul_chan_cfg *chan_cfg = &data->chan_cfg[chan];
chan_cfg->func = NULL;
chan_cfg->func_data = NULL;
chan_cfg->input = ADC_EMUL_CONST_VALUE;
chan_cfg->const_value = 0;
}
k_thread_create(&data->thread, data->stack,
CONFIG_ADC_EMUL_ACQUISITION_THREAD_STACK_SIZE,
(k_thread_entry_t)adc_emul_acquisition_thread,
data, NULL, NULL,
CONFIG_ADC_EMUL_ACQUISITION_THREAD_PRIO,
0, K_NO_WAIT);
adc_context_unlock_unconditionally(&data->ctx);
return 0;
}
#define ADC_EMUL_INIT(_num) \
static struct adc_driver_api adc_emul_api_##_num = { \
.channel_setup = adc_emul_channel_setup, \
.read = adc_emul_read, \
.ref_internal = DT_INST_PROP(_num, ref_internal_mv), \
IF_ENABLED(CONFIG_ADC_ASYNC, \
(.read_async = adc_emul_read_async,)) \
}; \
\
static struct adc_emul_chan_cfg \
adc_emul_ch_cfg_##_num[DT_INST_PROP(_num, nchannels)]; \
\
static const struct adc_emul_config adc_emul_config_##_num = { \
.num_channels = DT_INST_PROP(_num, nchannels), \
}; \
\
static struct adc_emul_data adc_emul_data_##_num = { \
ADC_CONTEXT_INIT_TIMER(adc_emul_data_##_num, ctx), \
ADC_CONTEXT_INIT_LOCK(adc_emul_data_##_num, ctx), \
ADC_CONTEXT_INIT_SYNC(adc_emul_data_##_num, ctx), \
.chan_cfg = adc_emul_ch_cfg_##_num, \
.ref_vdd = DT_INST_PROP(_num, ref_vdd_mv), \
.ref_ext0 = DT_INST_PROP(_num, ref_external0_mv), \
.ref_ext1 = DT_INST_PROP(_num, ref_external1_mv), \
.ref_int = DT_INST_PROP(_num, ref_internal_mv), \
}; \
\
DEVICE_DT_INST_DEFINE(_num, adc_emul_init, NULL, \
&adc_emul_data_##_num, \
&adc_emul_config_##_num, POST_KERNEL, \
CONFIG_ADC_INIT_PRIORITY, \
&adc_emul_api_##_num);
DT_INST_FOREACH_STATUS_OKAY(ADC_EMUL_INIT)