LXR linux/drivers/iio/potentiometer/ds1803.c

   1// SPDX-License-Identifier: GPL-2.0-only
   2/*
   3 * Maxim Integrated DS1803 digital potentiometer driver
   4 * Copyright (c) 2016 Slawomir Stepien
   5 *
   6 * Datasheet: https://datasheets.maximintegrated.com/en/ds/DS1803.pdf
   7 *
   8 * DEVID        #Wipers #Positions      Resistor Opts (kOhm)    i2c address
   9 * ds1803       2       256             10, 50, 100             0101xxx
  10 */
  11
  12#include <linux/err.h>
  13#include <linux/export.h>
  14#include <linux/i2c.h>
  15#include <linux/iio/iio.h>
  16#include <linux/module.h>
  17#include <linux/mod_devicetable.h>
  18
  19#define DS1803_MAX_POS          255
  20#define DS1803_WRITE(chan)      (0xa8 | ((chan) + 1))
  21
  22enum ds1803_type {
  23        DS1803_010,
  24        DS1803_050,
  25        DS1803_100,
  26};
  27
  28struct ds1803_cfg {
  29        int kohms;
  30};
  31
  32static const struct ds1803_cfg ds1803_cfg[] = {
  33        [DS1803_010] = { .kohms =  10, },
  34        [DS1803_050] = { .kohms =  50, },
  35        [DS1803_100] = { .kohms = 100, },
  36};
  37
  38struct ds1803_data {
  39        struct i2c_client *client;
  40        const struct ds1803_cfg *cfg;
  41};
  42
  43#define DS1803_CHANNEL(ch) {                                    \
  44        .type = IIO_RESISTANCE,                                 \
  45        .indexed = 1,                                           \
  46        .output = 1,                                            \
  47        .channel = (ch),                                        \
  48        .info_mask_separate = BIT(IIO_CHAN_INFO_RAW),           \
  49        .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE),   \
  50}
  51
  52static const struct iio_chan_spec ds1803_channels[] = {
  53        DS1803_CHANNEL(0),
  54        DS1803_CHANNEL(1),
  55};
  56
  57static int ds1803_read_raw(struct iio_dev *indio_dev,
  58                            struct iio_chan_spec const *chan,
  59                            int *val, int *val2, long mask)
  60{
  61        struct ds1803_data *data = iio_priv(indio_dev);
  62        int pot = chan->channel;
  63        int ret;
  64        u8 result[ARRAY_SIZE(ds1803_channels)];
  65
  66        switch (mask) {
  67        case IIO_CHAN_INFO_RAW:
  68                ret = i2c_master_recv(data->client, result,
  69                                indio_dev->num_channels);
  70                if (ret < 0)
  71                        return ret;
  72
  73                *val = result[pot];
  74                return IIO_VAL_INT;
  75
  76        case IIO_CHAN_INFO_SCALE:
  77                *val = 1000 * data->cfg->kohms;
  78                *val2 = DS1803_MAX_POS;
  79                return IIO_VAL_FRACTIONAL;
  80        }
  81
  82        return -EINVAL;
  83}
  84
  85static int ds1803_write_raw(struct iio_dev *indio_dev,
  86                             struct iio_chan_spec const *chan,
  87                             int val, int val2, long mask)
  88{
  89        struct ds1803_data *data = iio_priv(indio_dev);
  90        int pot = chan->channel;
  91
  92        if (val2 != 0)
  93                return -EINVAL;
  94
  95        switch (mask) {
  96        case IIO_CHAN_INFO_RAW:
  97                if (val > DS1803_MAX_POS || val < 0)
  98                        return -EINVAL;
  99                break;
 100        default:
 101                return -EINVAL;
 102        }
 103
 104        return i2c_smbus_write_byte_data(data->client, DS1803_WRITE(pot), val);
 105}
 106
 107static const struct iio_info ds1803_info = {
 108        .read_raw = ds1803_read_raw,
 109        .write_raw = ds1803_write_raw,
 110};
 111
 112static int ds1803_probe(struct i2c_client *client,
 113                         const struct i2c_device_id *id)
 114{
 115        struct device *dev = &client->dev;
 116        struct ds1803_data *data;
 117        struct iio_dev *indio_dev;
 118
 119        indio_dev = devm_iio_device_alloc(dev, sizeof(*data));
 120        if (!indio_dev)
 121                return -ENOMEM;
 122
 123        i2c_set_clientdata(client, indio_dev);
 124
 125        data = iio_priv(indio_dev);
 126        data->client = client;
 127        data->cfg = &ds1803_cfg[id->driver_data];
 128
 129        indio_dev->info = &ds1803_info;
 130        indio_dev->channels = ds1803_channels;
 131        indio_dev->num_channels = ARRAY_SIZE(ds1803_channels);
 132        indio_dev->name = client->name;
 133
 134        return devm_iio_device_register(dev, indio_dev);
 135}
 136
 137static const struct of_device_id ds1803_dt_ids[] = {
 138        { .compatible = "maxim,ds1803-010", .data = &ds1803_cfg[DS1803_010] },
 139        { .compatible = "maxim,ds1803-050", .data = &ds1803_cfg[DS1803_050] },
 140        { .compatible = "maxim,ds1803-100", .data = &ds1803_cfg[DS1803_100] },
 141        {}
 142};
 143MODULE_DEVICE_TABLE(of, ds1803_dt_ids);
 144
 145static const struct i2c_device_id ds1803_id[] = {
 146        { "ds1803-010", DS1803_010 },
 147        { "ds1803-050", DS1803_050 },
 148        { "ds1803-100", DS1803_100 },
 149        {}
 150};
 151MODULE_DEVICE_TABLE(i2c, ds1803_id);
 152
 153static struct i2c_driver ds1803_driver = {
 154        .driver = {
 155                .name   = "ds1803",
 156                .of_match_table = ds1803_dt_ids,
 157        },
 158        .probe          = ds1803_probe,
 159        .id_table       = ds1803_id,
 160};
 161
 162module_i2c_driver(ds1803_driver);
 163
 164MODULE_AUTHOR("Slawomir Stepien <sst@poczta.fm>");
 165MODULE_DESCRIPTION("DS1803 digital potentiometer");
 166MODULE_LICENSE("GPL v2");
 167