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1// SPDX-License-Identifier: GPL-2.0-or-later2/*3 * Maxim Integrated MAX5432-MAX5435 digital potentiometer driver4 * Copyright (C) 2019 Martin Kaiser <martin@kaiser.cx>5 *6 * Datasheet:7 * https://datasheets.maximintegrated.com/en/ds/MAX5432-MAX5435.pdf8 */9 10#include <linux/i2c.h>11#include <linux/iio/iio.h>12#include <linux/limits.h>13#include <linux/module.h>14#include <linux/mod_devicetable.h>15#include <linux/property.h>16 17/* All chip variants have 32 wiper positions. */18#define MAX5432_MAX_POS 3119 20#define MAX5432_OHM_50K (50 * 1000)21#define MAX5432_OHM_100K (100 * 1000)22 23/* Update the volatile (currently active) setting. */24#define MAX5432_CMD_VREG 0x1125 26struct max5432_data {27 struct i2c_client *client;28 unsigned long ohm;29};30 31static const struct iio_chan_spec max5432_channels[] = {32 {33 .type = IIO_RESISTANCE,34 .indexed = 1,35 .output = 1,36 .channel = 0,37 .address = MAX5432_CMD_VREG,38 .info_mask_separate = BIT(IIO_CHAN_INFO_RAW),39 .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE),40 }41};42 43static int max5432_read_raw(struct iio_dev *indio_dev,44 struct iio_chan_spec const *chan,45 int *val, int *val2, long mask)46{47 struct max5432_data *data = iio_priv(indio_dev);48 49 if (mask != IIO_CHAN_INFO_SCALE)50 return -EINVAL;51 52 if (unlikely(data->ohm > INT_MAX))53 return -ERANGE;54 55 *val = data->ohm;56 *val2 = MAX5432_MAX_POS;57 58 return IIO_VAL_FRACTIONAL;59}60 61static int max5432_write_raw(struct iio_dev *indio_dev,62 struct iio_chan_spec const *chan,63 int val, int val2, long mask)64{65 struct max5432_data *data = iio_priv(indio_dev);66 u8 data_byte;67 68 if (mask != IIO_CHAN_INFO_RAW)69 return -EINVAL;70 71 if (val < 0 || val > MAX5432_MAX_POS)72 return -EINVAL;73 74 if (val2 != 0)75 return -EINVAL;76 77 /* Wiper position is in bits D7-D3. (D2-D0 are don't care bits.) */78 data_byte = val << 3;79 return i2c_smbus_write_byte_data(data->client, chan->address,80 data_byte);81}82 83static const struct iio_info max5432_info = {84 .read_raw = max5432_read_raw,85 .write_raw = max5432_write_raw,86};87 88static int max5432_probe(struct i2c_client *client)89{90 struct device *dev = &client->dev;91 struct iio_dev *indio_dev;92 struct max5432_data *data;93 94 indio_dev = devm_iio_device_alloc(dev, sizeof(struct max5432_data));95 if (!indio_dev)96 return -ENOMEM;97 98 i2c_set_clientdata(client, indio_dev);99 100 data = iio_priv(indio_dev);101 data->client = client;102 data->ohm = (unsigned long)device_get_match_data(dev);103 104 indio_dev->info = &max5432_info;105 indio_dev->channels = max5432_channels;106 indio_dev->num_channels = ARRAY_SIZE(max5432_channels);107 indio_dev->name = client->name;108 109 return devm_iio_device_register(dev, indio_dev);110}111 112static const struct of_device_id max5432_dt_ids[] = {113 { .compatible = "maxim,max5432", .data = (void *)MAX5432_OHM_50K },114 { .compatible = "maxim,max5433", .data = (void *)MAX5432_OHM_100K },115 { .compatible = "maxim,max5434", .data = (void *)MAX5432_OHM_50K },116 { .compatible = "maxim,max5435", .data = (void *)MAX5432_OHM_100K },117 { /* sentinel */ }118};119MODULE_DEVICE_TABLE(of, max5432_dt_ids);120 121static struct i2c_driver max5432_driver = {122 .driver = {123 .name = "max5432",124 .of_match_table = max5432_dt_ids,125 },126 .probe = max5432_probe,127};128 129module_i2c_driver(max5432_driver);130 131MODULE_AUTHOR("Martin Kaiser <martin@kaiser.cx>");132MODULE_DESCRIPTION("max5432-max5435 digital potentiometers");133MODULE_LICENSE("GPL v2");134