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