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/*
* Driver for Linear Technology LTC2471 and LTC2473 voltage monitors
* The LTC2473 is identical to the 2471, but reports a differential signal.
*
* Copyright (C) 2017 Topic Embedded Products
* Author: Mike Looijmans <mike.looijmans@topic.nl>
*
* License: GPLv2
*/
#include <linux/err.h>
#include <linux/i2c.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/iio/iio.h>
#include <linux/iio/sysfs.h>
enum ltc2471_chips {
ltc2471,
ltc2473,
};
struct ltc2471_data {
struct i2c_client *client;
};
/* Reference voltage is 1.25V */
#define LTC2471_VREF 1250
/* Read two bytes from the I2C bus to obtain the ADC result */
static int ltc2471_get_value(struct i2c_client *client)
{
int ret;
__be16 buf;
ret = i2c_master_recv(client, (char *)&buf, sizeof(buf));
if (ret < 0)
return ret;
if (ret != sizeof(buf))
return -EIO;
/* MSB first */
return be16_to_cpu(buf);
}
static int ltc2471_read_raw(struct iio_dev *indio_dev,
struct iio_chan_spec const *chan,
int *val, int *val2, long info)
{
struct ltc2471_data *data = iio_priv(indio_dev);
int ret;
switch (info) {
case IIO_CHAN_INFO_RAW:
ret = ltc2471_get_value(data->client);
if (ret < 0)
return ret;
*val = ret;
return IIO_VAL_INT;
case IIO_CHAN_INFO_SCALE:
if (chan->differential)
/* Output ranges from -VREF to +VREF */
*val = 2 * LTC2471_VREF;
else
/* Output ranges from 0 to VREF */
*val = LTC2471_VREF;
*val2 = 16; /* 16 data bits */
return IIO_VAL_FRACTIONAL_LOG2;
case IIO_CHAN_INFO_OFFSET:
/* Only differential chip has this property */
*val = -LTC2471_VREF;
return IIO_VAL_INT;
default:
return -EINVAL;
}
}
static const struct iio_chan_spec ltc2471_channel[] = {
{
.type = IIO_VOLTAGE,
.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE),
},
};
static const struct iio_chan_spec ltc2473_channel[] = {
{
.type = IIO_VOLTAGE,
.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE) |
BIT(IIO_CHAN_INFO_OFFSET),
.differential = 1,
},
};
static const struct iio_info ltc2471_info = {
.read_raw = ltc2471_read_raw,
};
static int ltc2471_i2c_probe(struct i2c_client *client,
const struct i2c_device_id *id)
{
struct iio_dev *indio_dev;
struct ltc2471_data *data;
int ret;
if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C))
return -EOPNOTSUPP;
indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*data));
if (!indio_dev)
return -ENOMEM;
data = iio_priv(indio_dev);
data->client = client;
indio_dev->dev.parent = &client->dev;
indio_dev->name = id->name;
indio_dev->info = <c2471_info;
indio_dev->modes = INDIO_DIRECT_MODE;
if (id->driver_data == ltc2473)
indio_dev->channels = ltc2473_channel;
else
indio_dev->channels = ltc2471_channel;
indio_dev->num_channels = 1;
/* Trigger once to start conversion and check if chip is there */
ret = ltc2471_get_value(client);
if (ret < 0) {
dev_err(&client->dev, "Cannot read from device.\n");
return ret;
}
return devm_iio_device_register(&client->dev, indio_dev);
}
static const struct i2c_device_id ltc2471_i2c_id[] = {
{ "ltc2471", ltc2471 },
{ "ltc2473", ltc2473 },
{}
};
MODULE_DEVICE_TABLE(i2c, ltc2471_i2c_id);
static struct i2c_driver ltc2471_i2c_driver = {
.driver = {
.name = "ltc2471",
},
.probe = ltc2471_i2c_probe,
.id_table = ltc2471_i2c_id,
};
module_i2c_driver(ltc2471_i2c_driver);
MODULE_DESCRIPTION("LTC2471/LTC2473 ADC driver");
MODULE_AUTHOR("Topic Embedded Products");
MODULE_LICENSE("GPL v2");
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