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// SPDX-License-Identifier: GPL-2.0-or-later
/*
* Maxim Integrated MAX5432-MAX5435 digital potentiometer driver
* Copyright (C) 2019 Martin Kaiser <martin@kaiser.cx>
*
* Datasheet:
* https://datasheets.maximintegrated.com/en/ds/MAX5432-MAX5435.pdf
*/
#include <linux/i2c.h>
#include <linux/iio/iio.h>
#include <linux/limits.h>
#include <linux/module.h>
#include <linux/mod_devicetable.h>
#include <linux/property.h>
/* All chip variants have 32 wiper positions. */
#define MAX5432_MAX_POS 31
#define MAX5432_OHM_50K (50 * 1000)
#define MAX5432_OHM_100K (100 * 1000)
/* Update the volatile (currently active) setting. */
#define MAX5432_CMD_VREG 0x11
struct max5432_data {
struct i2c_client *client;
unsigned long ohm;
};
static const struct iio_chan_spec max5432_channels[] = {
{
.type = IIO_RESISTANCE,
.indexed = 1,
.output = 1,
.channel = 0,
.address = MAX5432_CMD_VREG,
.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE),
}
};
static int max5432_read_raw(struct iio_dev *indio_dev,
struct iio_chan_spec const *chan,
int *val, int *val2, long mask)
{
struct max5432_data *data = iio_priv(indio_dev);
if (mask != IIO_CHAN_INFO_SCALE)
return -EINVAL;
if (unlikely(data->ohm > INT_MAX))
return -ERANGE;
*val = data->ohm;
*val2 = MAX5432_MAX_POS;
return IIO_VAL_FRACTIONAL;
}
static int max5432_write_raw(struct iio_dev *indio_dev,
struct iio_chan_spec const *chan,
int val, int val2, long mask)
{
struct max5432_data *data = iio_priv(indio_dev);
u8 data_byte;
if (mask != IIO_CHAN_INFO_RAW)
return -EINVAL;
if (val < 0 || val > MAX5432_MAX_POS)
return -EINVAL;
if (val2 != 0)
return -EINVAL;
/* Wiper position is in bits D7-D3. (D2-D0 are don't care bits.) */
data_byte = val << 3;
return i2c_smbus_write_byte_data(data->client, chan->address,
data_byte);
}
static const struct iio_info max5432_info = {
.read_raw = max5432_read_raw,
.write_raw = max5432_write_raw,
};
static int max5432_probe(struct i2c_client *client)
{
struct device *dev = &client->dev;
struct iio_dev *indio_dev;
struct max5432_data *data;
indio_dev = devm_iio_device_alloc(dev, sizeof(struct max5432_data));
if (!indio_dev)
return -ENOMEM;
i2c_set_clientdata(client, indio_dev);
data = iio_priv(indio_dev);
data->client = client;
data->ohm = (unsigned long)device_get_match_data(dev);
indio_dev->info = &max5432_info;
indio_dev->channels = max5432_channels;
indio_dev->num_channels = ARRAY_SIZE(max5432_channels);
indio_dev->name = client->name;
return devm_iio_device_register(dev, indio_dev);
}
static const struct of_device_id max5432_dt_ids[] = {
{ .compatible = "maxim,max5432", .data = (void *)MAX5432_OHM_50K },
{ .compatible = "maxim,max5433", .data = (void *)MAX5432_OHM_100K },
{ .compatible = "maxim,max5434", .data = (void *)MAX5432_OHM_50K },
{ .compatible = "maxim,max5435", .data = (void *)MAX5432_OHM_100K },
{ /* sentinel */ }
};
MODULE_DEVICE_TABLE(of, max5432_dt_ids);
static struct i2c_driver max5432_driver = {
.driver = {
.name = "max5432",
.of_match_table = max5432_dt_ids,
},
.probe_new = max5432_probe,
};
module_i2c_driver(max5432_driver);
MODULE_AUTHOR("Martin Kaiser <martin@kaiser.cx>");
MODULE_DESCRIPTION("max5432-max5435 digital potentiometers");
MODULE_LICENSE("GPL v2");
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