// SPDX-License-Identifier: GPL-2.0
/* ad7949.c - Analog Devices ADC driver 14/16 bits 4/8 channels
*
* Copyright (C) 2018 CMC NV
*
* https://www.analog.com/media/en/technical-documentation/data-sheets/AD7949.pdf
*/
#include <linux/delay.h>
#include <linux/iio/iio.h>
#include <linux/module.h>
#include <linux/regulator/consumer.h>
#include <linux/spi/spi.h>
#include <linux/bitfield.h>
#define AD7949_CFG_MASK_TOTAL GENMASK(13, 0)
/* CFG: Configuration Update */
#define AD7949_CFG_MASK_OVERWRITE BIT(13)
/* INCC: Input Channel Configuration */
#define AD7949_CFG_MASK_INCC GENMASK(12, 10)
#define AD7949_CFG_VAL_INCC_UNIPOLAR_GND 7
#define AD7949_CFG_VAL_INCC_UNIPOLAR_COMM 6
#define AD7949_CFG_VAL_INCC_UNIPOLAR_DIFF 4
#define AD7949_CFG_VAL_INCC_TEMP 3
#define AD7949_CFG_VAL_INCC_BIPOLAR 2
#define AD7949_CFG_VAL_INCC_BIPOLAR_DIFF 0
/* INX: Input channel Selection in a binary fashion */
#define AD7949_CFG_MASK_INX GENMASK(9, 7)
/* BW: select bandwidth for low-pass filter. Full or Quarter */
#define AD7949_CFG_MASK_BW_FULL BIT(6)
/* REF: reference/buffer selection */
#define AD7949_CFG_MASK_REF GENMASK(5, 3)
#define AD7949_CFG_VAL_REF_EXT_TEMP_BUF 3
#define AD7949_CFG_VAL_REF_EXT_TEMP 2
#define AD7949_CFG_VAL_REF_INT_4096 1
#define AD7949_CFG_VAL_REF_INT_2500 0
#define AD7949_CFG_VAL_REF_EXTERNAL BIT(1)
/* SEQ: channel sequencer. Allows for scanning channels */
#define AD7949_CFG_MASK_SEQ GENMASK(2, 1)
/* RB: Read back the CFG register */
#define AD7949_CFG_MASK_RBN BIT(0)
enum {
ID_AD7949 = 0,
ID_AD7682,
ID_AD7689,
};
struct ad7949_adc_spec {
u8 num_channels;
u8 resolution;
};
static const struct ad7949_adc_spec ad7949_adc_spec[] = {
[ID_AD7949] = { .num_channels = 8, .resolution = 14 },
[ID_AD7682] = { .num_channels = 4, .resolution = 16 },
[ID_AD7689] = { .num_channels = 8, .resolution = 16 },
};
/**
* struct ad7949_adc_chip - AD ADC chip
* @lock: protects write sequences
* @vref: regulator generating Vref
* @indio_dev: reference to iio structure
* @spi: reference to spi structure
* @refsel: reference selection
* @resolution: resolution of the chip
* @cfg: copy of the configuration register
* @current_channel: current channel in use
* @buffer: buffer to send / receive data to / from device
* @buf8b: be16 buffer to exchange data with the device in 8-bit transfers
*/
struct ad7949_adc_chip {
struct mutex lock;
struct regulator *vref;
struct iio_dev *indio_dev;
struct spi_device *spi;
u32 refsel;
u8 resolution;
u16 cfg;
unsigned int current_channel;
u16 buffer __aligned(IIO_DMA_MINALIGN);
__be16 buf8b;
};
static int ad7949_spi_write_cfg(struct ad7949_adc_chip *ad7949_adc, u16 val,
u16 mask)
{
int ret;
ad7949_adc->cfg = (val & mask) | (ad7949_adc->cfg & ~mask);
switch (ad7949_adc->spi->bits_per_word) {
case 16:
ad7949_adc->buffer = ad7949_adc->cfg << 2;
ret = spi_write(ad7949_adc->spi, &ad7949_adc->buffer, 2);
break;
case 14:
ad7949_adc->buffer = ad7949_adc->cfg;
ret = spi_write(ad7949_adc->spi, &ad7949_adc->buffer, 2);
break;
case 8:
/* Here, type is big endian as it must be sent in two transfers */
ad7949_adc->buf8b = cpu_to_be16(ad7949_adc->cfg << 2);
ret = spi_write(ad7949_adc->spi, &ad7949_adc->buf8b, 2);
break;
default:
dev_err(&ad7949_adc->indio_dev->dev, "unsupported BPW\n");
return -EINVAL;
}
/*
* This delay is to avoid a new request before the required time to
* send a new command to the device
*/
udelay(2);
return ret;
}
static int ad7949_spi_read_channel(struct ad7949_adc_chip *ad7949_adc, int *val,
unsigned int channel)
{
int ret;
int i;
/*
* 1: write CFG for sample N and read old data (sample N-2)
* 2: if CFG was not changed since sample N-1 then we'll get good data
* at the next xfer, so we bail out now, otherwise we write something
* and we read garbage (sample N-1 configuration).
*/
for (i = 0; i < 2; i++) {
ret = ad7949_spi_write_cfg(ad7949_adc,
FIELD_PREP(AD7949_CFG_MASK_INX, channel),
AD7949_CFG_MASK_INX);
if (ret)
return ret;
if (channel == ad7949_adc->current_channel)
break;
}
/* 3: write something and read actual data */
if (ad7949_adc->spi->bits_per_word == 8)
ret = spi_read(ad7949_adc->spi, &ad7949_adc->buf8b, 2);
else
ret = spi_read(ad7949_adc->spi, &ad7949_adc->buffer, 2);
if (ret)
return ret;
/*
* This delay is to avoid a new request before the required time to
* send a new command to the device
*/
udelay(2);
ad7949_adc->current_channel = channel;
switch (ad7949_adc->spi->bits_per_word) {
case 16:
*val = ad7949_adc->buffer;
/* Shift-out padding bits */
*val >>= 16 - ad7949_adc->resolution;
break;
case 14:
*val = ad7949_adc->buffer & GENMASK(13, 0);
break;
case 8:
/* Here, type is big endian as data was sent in two transfers */
*val = be16_to_cpu(ad7949_adc->buf8b);
/* Shift-out padding bits */
*val >>= 16 - ad7949_adc->resolution;
break;
default:
dev_err(&ad7949_adc->indio_dev->dev, "unsupported BPW\n");
return -EINVAL;
}
return 0;
}
#define AD7949_ADC_CHANNEL(chan) { \
.type = IIO_VOLTAGE, \
.indexed = 1, \
.channel = (chan), \
.info_mask_separate = BIT(IIO_CHAN_INFO_RAW), \
.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE), \
}
static const struct iio_chan_spec ad7949_adc_channels[] = {
AD7949_ADC_CHANNEL(0),
AD7949_ADC_CHANNEL(1),
AD7949_ADC_CHANNEL(2),
AD7949_ADC_CHANNEL(3),
AD7949_ADC_CHANNEL(4),
AD7949_ADC_CHANNEL(5),
AD7949_ADC_CHANNEL(6),
AD7949_ADC_CHANNEL(7),
};
static int ad7949_spi_read_raw(struct iio_dev *indio_dev,
struct iio_chan_spec const *chan,
int *val, int *val2, long mask)
{
struct ad7949_adc_chip *ad7949_adc = iio_priv(indio_dev);
int ret;
if (!val)
return -EINVAL;
switch (mask) {
case IIO_CHAN_INFO_RAW:
mutex_lock(&ad7949_adc->lock);
ret = ad7949_spi_read_channel(ad7949_adc, val, chan->channel);
mutex_unlock(&ad7949_adc->lock);
if (ret < 0)
return ret;
return IIO_VAL_INT;
case IIO_CHAN_INFO_SCALE:
switch (ad7949_adc->refsel) {
case AD7949_CFG_VAL_REF_INT_2500:
*val = 2500;
break;
case AD7949_CFG_VAL_REF_INT_4096:
*val = 4096;
break;
case AD7949_CFG_VAL_REF_EXT_TEMP:
case AD7949_CFG_VAL_REF_EXT_TEMP_BUF:
ret = regulator_get_voltage(ad7949_adc->vref);
if (ret < 0)
return ret;
/* convert value back to mV */
*val = ret / 1000;
break;
}
*val2 = (1 << ad7949_adc->resolution) - 1;
return IIO_VAL_FRACTIONAL;
}
return -EINVAL;
}
static int ad7949_spi_reg_access(struct iio_dev *indio_dev,
unsigned int reg, unsigned int writeval,
unsigned int *readval)
{
struct ad7949_adc_chip *ad7949_adc = iio_priv(indio_dev);
int ret = 0;
if (readval)
*readval = ad7949_adc->cfg;
else
ret = ad7949_spi_write_cfg(ad7949_adc, writeval,
AD7949_CFG_MASK_TOTAL);
return ret;
}
static const struct iio_info ad7949_spi_info = {
.read_raw = ad7949_spi_read_raw,
.debugfs_reg_access = ad7949_spi_reg_access,
};
static int ad7949_spi_init(struct ad7949_adc_chip *ad7949_adc)
{
int ret;
int val;
u16 cfg;
ad7949_adc->current_channel = 0;
cfg = FIELD_PREP(AD7949_CFG_MASK_OVERWRITE, 1) |
FIELD_PREP(AD7949_CFG_MASK_INCC, AD7949_CFG_VAL_INCC_UNIPOLAR_GND) |
FIELD_PREP(AD7949_CFG_MASK_INX, ad7949_adc->current_channel) |
FIELD_PREP(AD7949_CFG_MASK_BW_FULL, 1) |
FIELD_PREP(AD7949_CFG_MASK_REF, ad7949_adc->refsel) |
FIELD_PREP(AD7949_CFG_MASK_SEQ, 0x0) |
FIELD_PREP(AD7949_CFG_MASK_RBN, 1);
ret = ad7949_spi_write_cfg(ad7949_adc, cfg, AD7949_CFG_MASK_TOTAL);
/*
* Do two dummy conversions to apply the first configuration setting.
* Required only after the start up of the device.
*/
ad7949_spi_read_channel(ad7949_adc, &val, ad7949_adc->current_channel);
ad7949_spi_read_channel(ad7949_adc, &val, ad7949_adc->current_channel);
return ret;
}
static void ad7949_disable_reg(void *reg)
{
regulator_disable(reg);
}
static int ad7949_spi_probe(struct spi_device *spi)
{
u32 spi_ctrl_mask = spi->controller->bits_per_word_mask;
struct device *dev = &spi->dev;
const struct ad7949_adc_spec *spec;
struct ad7949_adc_chip *ad7949_adc;
struct iio_dev *indio_dev;
u32 tmp;
int ret;
indio_dev = devm_iio_device_alloc(dev, sizeof(*ad7949_adc));
if (!indio_dev) {
dev_err(dev, "can not allocate iio device\n");
return -ENOMEM;
}
indio_dev->info = &ad7949_spi_info;
indio_dev->name = spi_get_device_id(spi)->name;
indio_dev->modes = INDIO_DIRECT_MODE;
indio_dev->channels = ad7949_adc_channels;
spi_set_drvdata(spi, indio_dev);
ad7949_adc = iio_priv(indio_dev);
ad7949_adc->indio_dev = indio_dev;
ad7949_adc->spi = spi;
spec = &ad7949_adc_spec[spi_get_device_id(spi)->driver_data];
indio_dev->num_channels = spec->num_channels;
ad7949_adc->resolution = spec->resolution;
/* Set SPI bits per word */
if (spi_ctrl_mask & SPI_BPW_MASK(ad7949_adc->resolution)) {
spi->bits_per_word = ad7949_adc->resolution;
} else if (spi_ctrl_mask == SPI_BPW_MASK(16)) {
spi->bits_per_word = 16;
} else if (spi_ctrl_mask == SPI_BPW_MASK(8)) {
spi->bits_per_word = 8;
} else {
dev_err(dev, "unable to find common BPW with spi controller\n");
return -EINVAL;
}
/* Setup internal voltage reference */
tmp = 4096000;
device_property_read_u32(dev, "adi,internal-ref-microvolt", &tmp);
switch (tmp) {
case 2500000:
ad7949_adc->refsel = AD7949_CFG_VAL_REF_INT_2500;
break;
case 4096000:
ad7949_adc->refsel = AD7949_CFG_VAL_REF_INT_4096;
break;
default:
dev_err(dev, "unsupported internal voltage reference\n");
return -EINVAL;
}
/* Setup external voltage reference, buffered? */
ad7949_adc->vref = devm_regulator_get_optional(dev, "vrefin");
if (IS_ERR(ad7949_adc->vref)) {
ret = PTR_ERR(ad7949_adc->vref);
if (ret != -ENODEV)
return ret;
/* unbuffered? */
ad7949_adc->vref = devm_regulator_get_optional(dev, "vref");
if (IS_ERR(ad7949_adc->vref)) {
ret = PTR_ERR(ad7949_adc->vref);
if (ret != -ENODEV)
return ret;
} else {
ad7949_adc->refsel = AD7949_CFG_VAL_REF_EXT_TEMP;
}
} else {
ad7949_adc->refsel = AD7949_CFG_VAL_REF_EXT_TEMP_BUF;
}
if (ad7949_adc->refsel & AD7949_CFG_VAL_REF_EXTERNAL) {
ret = regulator_enable(ad7949_adc->vref);
if (ret < 0) {
dev_err(dev, "fail to enable regulator\n");
return ret;
}
ret = devm_add_action_or_reset(dev, ad7949_disable_reg,
ad7949_adc->vref);
if (ret)
return ret;
}
mutex_init(&ad7949_adc->lock);
ret = ad7949_spi_init(ad7949_adc);
if (ret) {
dev_err(dev, "fail to init this device: %d\n", ret);
return ret;
}
ret = devm_iio_device_register(dev, indio_dev);
if (ret)
dev_err(dev, "fail to register iio device: %d\n", ret);
return ret;
}
static const struct of_device_id ad7949_spi_of_id[] = {
{ .compatible = "adi,ad7949" },
{ .compatible = "adi,ad7682" },
{ .compatible = "adi,ad7689" },
{ }
};
MODULE_DEVICE_TABLE(of, ad7949_spi_of_id);
static const struct spi_device_id ad7949_spi_id[] = {
{ "ad7949", ID_AD7949 },
{ "ad7682", ID_AD7682 },
{ "ad7689", ID_AD7689 },
{ }
};
MODULE_DEVICE_TABLE(spi, ad7949_spi_id);
static struct spi_driver ad7949_spi_driver = {
.driver = {
.name = "ad7949",
.of_match_table = ad7949_spi_of_id,
},
.probe = ad7949_spi_probe,
.id_table = ad7949_spi_id,
};
module_spi_driver(ad7949_spi_driver);
MODULE_AUTHOR("Charles-Antoine Couret <[email protected]>");
MODULE_DESCRIPTION("Analog Devices 14/16-bit 8-channel ADC driver");
MODULE_LICENSE("GPL v2");
Codebase Browser
linux