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
  22 enum ds1803_type {
  23         DS1803_010,
  24         DS1803_050,
  25         DS1803_100,
  26 };
  27
  28 struct ds1803_cfg {
  29         int kohms;
  30 };
  31
  32 static const struct ds1803_cfg ds1803_cfg[] = {
  33         [DS1803_010] = { .kohms =  10, },
  34         [DS1803_050] = { .kohms =  50, },
  35         [DS1803_100] = { .kohms = 100, },
  36 };
  37
  38 struct 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
  52 static const struct iio_chan_spec ds1803_channels[] = {
  53         DS1803_CHANNEL(0),
  54         DS1803_CHANNEL(1),
  55 };
  56
  57 static 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
  85 static 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
 107 static const struct iio_info ds1803_info = {
 108         .read_raw = ds1803_read_raw,
 109         .write_raw = ds1803_write_raw,
 110 };
 111
 112 static 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
 137 static 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 };
 143 MODULE_DEVICE_TABLE(of, ds1803_dt_ids);
 144
 145 static const struct i2c_device_id ds1803_id[] = {
 146         { "ds1803-010", DS1803_010 },
 147         { "ds1803-050", DS1803_050 },
 148         { "ds1803-100", DS1803_100 },
 149         {}
 150 };
 151 MODULE_DEVICE_TABLE(i2c, ds1803_id);
 152
 153 static 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
 162 module_i2c_driver(ds1803_driver);
 163
 164 MODULE_AUTHOR("Slawomir Stepien <sst@poczta.fm>");
 165 MODULE_DESCRIPTION("DS1803 digital potentiometer");
 166 MODULE_LICENSE("GPL v2");