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linux-next/drivers/iio/adc/ad7949.c
Charles-Antoine Couret 7f40e06143 iio:adc:ad7949: Add AD7949 ADC driver family
Compatible with AD7682 and AD7689 chips.
It is a Analog Devices ADC driver 14/16 bits 4/8 channels
with SPI protocol

Datasheet of the device:
http://www.analog.com/media/en/technical-documentation/data-sheets/AD7949.pdf

Signed-off-by: Charles-Antoine Couret <charles-antoine.couret@essensium.com>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
2018-11-03 09:44:34 +00:00

348 lines
8.2 KiB
C

// SPDX-License-Identifier: GPL-2.0
/* ad7949.c - Analog Devices ADC driver 14/16 bits 4/8 channels
*
* Copyright (C) 2018 CMC NV
*
* http://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>
#define AD7949_MASK_CHANNEL_SEL GENMASK(9, 7)
#define AD7949_MASK_TOTAL GENMASK(13, 0)
#define AD7949_OFFSET_CHANNEL_SEL 7
#define AD7949_CFG_READ_BACK 0x1
#define AD7949_CFG_REG_SIZE_BITS 14
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
* @iio_dev: reference to iio structure
* @spi: reference to spi structure
* @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
*/
struct ad7949_adc_chip {
struct mutex lock;
struct regulator *vref;
struct iio_dev *indio_dev;
struct spi_device *spi;
u8 resolution;
u16 cfg;
unsigned int current_channel;
u32 buffer ____cacheline_aligned;
};
static bool ad7949_spi_cfg_is_read_back(struct ad7949_adc_chip *ad7949_adc)
{
if (!(ad7949_adc->cfg & AD7949_CFG_READ_BACK))
return true;
return false;
}
static int ad7949_spi_bits_per_word(struct ad7949_adc_chip *ad7949_adc)
{
int ret = ad7949_adc->resolution;
if (ad7949_spi_cfg_is_read_back(ad7949_adc))
ret += AD7949_CFG_REG_SIZE_BITS;
return ret;
}
static int ad7949_spi_write_cfg(struct ad7949_adc_chip *ad7949_adc, u16 val,
u16 mask)
{
int ret;
int bits_per_word = ad7949_spi_bits_per_word(ad7949_adc);
int shift = bits_per_word - AD7949_CFG_REG_SIZE_BITS;
struct spi_message msg;
struct spi_transfer tx[] = {
{
.tx_buf = &ad7949_adc->buffer,
.len = 4,
.bits_per_word = bits_per_word,
},
};
ad7949_adc->cfg = (val & mask) | (ad7949_adc->cfg & ~mask);
ad7949_adc->buffer = ad7949_adc->cfg << shift;
spi_message_init_with_transfers(&msg, tx, 1);
ret = spi_sync(ad7949_adc->spi, &msg);
/*
* 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 bits_per_word = ad7949_spi_bits_per_word(ad7949_adc);
int mask = GENMASK(ad7949_adc->resolution, 0);
struct spi_message msg;
struct spi_transfer tx[] = {
{
.rx_buf = &ad7949_adc->buffer,
.len = 4,
.bits_per_word = bits_per_word,
},
};
ret = ad7949_spi_write_cfg(ad7949_adc,
channel << AD7949_OFFSET_CHANNEL_SEL,
AD7949_MASK_CHANNEL_SEL);
if (ret)
return ret;
ad7949_adc->buffer = 0;
spi_message_init_with_transfers(&msg, tx, 1);
ret = spi_sync(ad7949_adc->spi, &msg);
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;
if (ad7949_spi_cfg_is_read_back(ad7949_adc))
*val = (ad7949_adc->buffer >> AD7949_CFG_REG_SIZE_BITS) & mask;
else
*val = ad7949_adc->buffer & mask;
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:
ret = regulator_get_voltage(ad7949_adc->vref);
if (ret < 0)
return ret;
*val = ret / 5000;
return IIO_VAL_INT;
}
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_MASK_TOTAL, AD7949_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;
/* Sequencer disabled, CFG readback disabled, IN0 as default channel */
ad7949_adc->current_channel = 0;
ret = ad7949_spi_write_cfg(ad7949_adc, 0x3C79, AD7949_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 int ad7949_spi_probe(struct spi_device *spi)
{
struct device *dev = &spi->dev;
const struct ad7949_adc_spec *spec;
struct ad7949_adc_chip *ad7949_adc;
struct iio_dev *indio_dev;
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->dev.parent = dev;
indio_dev->dev.of_node = dev->of_node;
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;
ad7949_adc->vref = devm_regulator_get(dev, "vref");
if (IS_ERR(ad7949_adc->vref)) {
dev_err(dev, "fail to request regulator\n");
return PTR_ERR(ad7949_adc->vref);
}
ret = regulator_enable(ad7949_adc->vref);
if (ret < 0) {
dev_err(dev, "fail to enable regulator\n");
return ret;
}
mutex_init(&ad7949_adc->lock);
ret = ad7949_spi_init(ad7949_adc);
if (ret) {
dev_err(dev, "enable to init this device: %d\n", ret);
goto err;
}
ret = iio_device_register(indio_dev);
if (ret) {
dev_err(dev, "fail to register iio device: %d\n", ret);
goto err;
}
return 0;
err:
mutex_destroy(&ad7949_adc->lock);
regulator_disable(ad7949_adc->vref);
return ret;
}
static int ad7949_spi_remove(struct spi_device *spi)
{
struct iio_dev *indio_dev = spi_get_drvdata(spi);
struct ad7949_adc_chip *ad7949_adc = iio_priv(indio_dev);
iio_device_unregister(indio_dev);
mutex_destroy(&ad7949_adc->lock);
regulator_disable(ad7949_adc->vref);
return 0;
}
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,
.remove = ad7949_spi_remove,
.id_table = ad7949_spi_id,
};
module_spi_driver(ad7949_spi_driver);
MODULE_AUTHOR("Charles-Antoine Couret <charles-antoine.couret@essensium.com>");
MODULE_DESCRIPTION("Analog Devices 14/16-bit 8-channel ADC driver");
MODULE_LICENSE("GPL v2");