158 строки
3.5 KiB
C
158 строки
3.5 KiB
C
// SPDX-License-Identifier: GPL-2.0-only
|
|
/*
|
|
* 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>
|
|
*/
|
|
|
|
#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->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");
|