// SPDX-License-Identifier: GPL-2.0
/*
* Analog Devices AD7292 SPI ADC driver
*
* Copyright 2019 Analog Devices Inc.
*/
#include <linux/bitfield.h>
#include <linux/device.h>
#include <linux/module.h>
#include <linux/mod_devicetable.h>
#include <linux/property.h>
#include <linux/regulator/consumer.h>
#include <linux/spi/spi.h>
#include <linux/iio/iio.h>
#define ADI_VENDOR_ID 0x0018
#define AD7292_INTERNAL_REF_MV 1250
/* AD7292 registers definition */
#define AD7292_REG_VENDOR_ID 0x00
#define AD7292_REG_CONF_BANK 0x05
#define AD7292_REG_CONV_COMM 0x0E
#define AD7292_REG_ADC_CH(x) (0x10 + (x))
/* AD7292 configuration bank subregisters definition */
#define AD7292_BANK_REG_VIN_RNG0 0x10
#define AD7292_BANK_REG_VIN_RNG1 0x11
#define AD7292_BANK_REG_SAMP_MODE 0x12
#define AD7292_RD_FLAG_MSK(x) (BIT(7) | ((x) & 0x3F))
/* AD7292_REG_ADC_CONVERSION */
#define AD7292_ADC_DATA_MASK GENMASK(15, 6)
#define AD7292_ADC_DATA(x) FIELD_GET(AD7292_ADC_DATA_MASK, x)
/* AD7292_CHANNEL_SAMPLING_MODE */
#define AD7292_CH_SAMP_MODE(reg, ch) (((reg) >> 8) & BIT(ch))
/* AD7292_CHANNEL_VIN_RANGE */
#define AD7292_CH_VIN_RANGE(reg, ch) ((reg) & BIT(ch))
#define AD7292_VOLTAGE_CHAN(_chan) \
{ \
.type = IIO_VOLTAGE, \
.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) | \
BIT(IIO_CHAN_INFO_SCALE), \
.indexed = 1, \
.channel = _chan, \
}
static const struct iio_chan_spec ad7292_channels[] = {
AD7292_VOLTAGE_CHAN(0),
AD7292_VOLTAGE_CHAN(1),
AD7292_VOLTAGE_CHAN(2),
AD7292_VOLTAGE_CHAN(3),
AD7292_VOLTAGE_CHAN(4),
AD7292_VOLTAGE_CHAN(5),
AD7292_VOLTAGE_CHAN(6),
AD7292_VOLTAGE_CHAN(7)
};
static const struct iio_chan_spec ad7292_channels_diff[] = {
{
.type = IIO_VOLTAGE,
.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
.indexed = 1,
.differential = 1,
.channel = 0,
.channel2 = 1,
},
AD7292_VOLTAGE_CHAN(2),
AD7292_VOLTAGE_CHAN(3),
AD7292_VOLTAGE_CHAN(4),
AD7292_VOLTAGE_CHAN(5),
AD7292_VOLTAGE_CHAN(6),
AD7292_VOLTAGE_CHAN(7)
};
struct ad7292_state {
struct spi_device *spi;
unsigned short vref_mv;
__be16 d16 __aligned(IIO_DMA_MINALIGN);
u8 d8[2];
};
static int ad7292_spi_reg_read(struct ad7292_state *st, unsigned int addr)
{
int ret;
st->d8[0] = AD7292_RD_FLAG_MSK(addr);
ret = spi_write_then_read(st->spi, st->d8, 1, &st->d16, 2);
if (ret < 0)
return ret;
return be16_to_cpu(st->d16);
}
static int ad7292_spi_subreg_read(struct ad7292_state *st, unsigned int addr,
unsigned int sub_addr, unsigned int len)
{
unsigned int shift = 16 - (8 * len);
int ret;
st->d8[0] = AD7292_RD_FLAG_MSK(addr);
st->d8[1] = sub_addr;
ret = spi_write_then_read(st->spi, st->d8, 2, &st->d16, len);
if (ret < 0)
return ret;
return (be16_to_cpu(st->d16) >> shift);
}
static int ad7292_single_conversion(struct ad7292_state *st,
unsigned int chan_addr)
{
int ret;
struct spi_transfer t[] = {
{
.tx_buf = &st->d8,
.len = 4,
.delay = {
.value = 6,
.unit = SPI_DELAY_UNIT_USECS
},
}, {
.rx_buf = &st->d16,
.len = 2,
},
};
st->d8[0] = chan_addr;
st->d8[1] = AD7292_RD_FLAG_MSK(AD7292_REG_CONV_COMM);
ret = spi_sync_transfer(st->spi, t, ARRAY_SIZE(t));
if (ret < 0)
return ret;
return be16_to_cpu(st->d16);
}
static int ad7292_vin_range_multiplier(struct ad7292_state *st, int channel)
{
int samp_mode, range0, range1, factor = 1;
/*
* Every AD7292 ADC channel may have its input range adjusted according
* to the settings at the ADC sampling mode and VIN range subregisters.
* For a given channel, the minimum input range is equal to Vref, and it
* may be increased by a multiplier factor of 2 or 4 according to the
* following rule:
* If channel is being sampled with respect to AGND:
* factor = 4 if VIN range0 and VIN range1 equal 0
* factor = 2 if only one of VIN ranges equal 1
* factor = 1 if both VIN range0 and VIN range1 equal 1
* If channel is being sampled with respect to AVDD:
* factor = 4 if VIN range0 and VIN range1 equal 0
* Behavior is undefined if any of VIN range doesn't equal 0
*/
samp_mode = ad7292_spi_subreg_read(st, AD7292_REG_CONF_BANK,
AD7292_BANK_REG_SAMP_MODE, 2);
if (samp_mode < 0)
return samp_mode;
range0 = ad7292_spi_subreg_read(st, AD7292_REG_CONF_BANK,
AD7292_BANK_REG_VIN_RNG0, 2);
if (range0 < 0)
return range0;
range1 = ad7292_spi_subreg_read(st, AD7292_REG_CONF_BANK,
AD7292_BANK_REG_VIN_RNG1, 2);
if (range1 < 0)
return range1;
if (AD7292_CH_SAMP_MODE(samp_mode, channel)) {
/* Sampling with respect to AGND */
if (!AD7292_CH_VIN_RANGE(range0, channel))
factor *= 2;
if (!AD7292_CH_VIN_RANGE(range1, channel))
factor *= 2;
} else {
/* Sampling with respect to AVDD */
if (AD7292_CH_VIN_RANGE(range0, channel) ||
AD7292_CH_VIN_RANGE(range1, channel))
return -EPERM;
factor = 4;
}
return factor;
}
static int ad7292_read_raw(struct iio_dev *indio_dev,
const struct iio_chan_spec *chan,
int *val, int *val2, long info)
{
struct ad7292_state *st = iio_priv(indio_dev);
unsigned int ch_addr;
int ret;
switch (info) {
case IIO_CHAN_INFO_RAW:
ch_addr = AD7292_REG_ADC_CH(chan->channel);
ret = ad7292_single_conversion(st, ch_addr);
if (ret < 0)
return ret;
*val = AD7292_ADC_DATA(ret);
return IIO_VAL_INT;
case IIO_CHAN_INFO_SCALE:
/*
* To convert a raw value to standard units, the IIO defines
* this formula: Scaled value = (raw + offset) * scale.
* For the scale to be a correct multiplier for (raw + offset),
* it must be calculated as the input range divided by the
* number of possible distinct input values. Given the ADC data
* is 10 bit long, it may assume 2^10 distinct values.
* Hence, scale = range / 2^10. The IIO_VAL_FRACTIONAL_LOG2
* return type indicates to the IIO API to divide *val by 2 to
* the power of *val2 when returning from read_raw.
*/
ret = ad7292_vin_range_multiplier(st, chan->channel);
if (ret < 0)
return ret;
*val = st->vref_mv * ret;
*val2 = 10;
return IIO_VAL_FRACTIONAL_LOG2;
default:
break;
}
return -EINVAL;
}
static const struct iio_info ad7292_info = {
.read_raw = ad7292_read_raw,
};
static int ad7292_probe(struct spi_device *spi)
{
struct ad7292_state *st;
struct iio_dev *indio_dev;
bool diff_channels = false;
int ret;
indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*st));
if (!indio_dev)
return -ENOMEM;
st = iio_priv(indio_dev);
st->spi = spi;
ret = ad7292_spi_reg_read(st, AD7292_REG_VENDOR_ID);
if (ret != ADI_VENDOR_ID) {
dev_err(&spi->dev, "Wrong vendor id 0x%x\n", ret);
return -EINVAL;
}
ret = devm_regulator_get_enable_read_voltage(&spi->dev, "vref");
if (ret < 0 && ret != -ENODEV)
return ret;
st->vref_mv = ret == -ENODEV ? AD7292_INTERNAL_REF_MV : ret / 1000;
indio_dev->name = spi_get_device_id(spi)->name;
indio_dev->modes = INDIO_DIRECT_MODE;
indio_dev->info = &ad7292_info;
device_for_each_child_node_scoped(&spi->dev, child) {
diff_channels = fwnode_property_read_bool(child,
"diff-channels");
if (diff_channels)
break;
}
if (diff_channels) {
indio_dev->num_channels = ARRAY_SIZE(ad7292_channels_diff);
indio_dev->channels = ad7292_channels_diff;
} else {
indio_dev->num_channels = ARRAY_SIZE(ad7292_channels);
indio_dev->channels = ad7292_channels;
}
return devm_iio_device_register(&spi->dev, indio_dev);
}
static const struct spi_device_id ad7292_id_table[] = {
{ "ad7292", 0 },
{ }
};
MODULE_DEVICE_TABLE(spi, ad7292_id_table);
static const struct of_device_id ad7292_of_match[] = {
{ .compatible = "adi,ad7292" },
{ }
};
MODULE_DEVICE_TABLE(of, ad7292_of_match);
static struct spi_driver ad7292_driver = {
.driver = {
.name = "ad7292",
.of_match_table = ad7292_of_match,
},
.probe = ad7292_probe,
.id_table = ad7292_id_table,
};
module_spi_driver(ad7292_driver);
MODULE_AUTHOR("Marcelo Schmitt <[email protected]>");
MODULE_DESCRIPTION("Analog Devices AD7292 ADC driver");
MODULE_LICENSE("GPL v2");
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