drivers/iio/potentiometer/ds1803.c

   1 /*
   2  * Maxim Integrated DS1803 digital potentiometer driver
   3  * Copyright (c) 2016 Slawomir Stepien
   4  *
   5  * Datasheet: https://datasheets.maximintegrated.com/en/ds/DS1803.pdf
   6  *
   7  * DEVID        #Wipers #Positions      Resistor Opts (kOhm)    i2c address
   8  * ds1803       2       256             10, 50, 100             0101xxx
   9  *
  10  * This program is free software; you can redistribute it and/or modify it
  11  * under the terms of the GNU General Public License version 2 as published by
  12  * the Free Software Foundation.
  13  */
  14
  15 #include <linux/err.h>
  16 #include <linux/export.h>
  17 #include <linux/i2c.h>
  18 #include <linux/iio/iio.h>
  19 #include <linux/module.h>
  20 #include <linux/of.h>
  21
  22 #define DS1803_MAX_POS          255
  23 #define DS1803_WRITE(chan)      (0xa8 | ((chan) + 1))
  24
  25 enum ds1803_type {
  26         DS1803_010,
  27         DS1803_050,
  28         DS1803_100,
  29 };
  30
  31 struct ds1803_cfg {
  32         int kohms;
  33 };
  34
  35 static const struct ds1803_cfg ds1803_cfg[] = {
  36         [DS1803_010] = { .kohms =  10, },
  37         [DS1803_050] = { .kohms =  50, },
  38         [DS1803_100] = { .kohms = 100, },
  39 };
  40
  41 struct ds1803_data {
  42         struct i2c_client *client;
  43         const struct ds1803_cfg *cfg;
  44 };
  45
  46 #define DS1803_CHANNEL(ch) {                                    \
  47         .type = IIO_RESISTANCE,                                 \
  48         .indexed = 1,                                           \
  49         .output = 1,                                            \
  50         .channel = (ch),                                        \
  51         .info_mask_separate = BIT(IIO_CHAN_INFO_RAW),           \
  52         .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE),   \
  53 }
  54
  55 static const struct iio_chan_spec ds1803_channels[] = {
  56         DS1803_CHANNEL(0),
  57         DS1803_CHANNEL(1),
  58 };
  59
  60 static int ds1803_read_raw(struct iio_dev *indio_dev,
  61                             struct iio_chan_spec const *chan,
  62                             int *val, int *val2, long mask)
  63 {
  64         struct ds1803_data *data = iio_priv(indio_dev);
  65         int pot = chan->channel;
  66         int ret;
  67         u8 result[indio_dev->num_channels];
  68
  69         switch (mask) {
  70         case IIO_CHAN_INFO_RAW:
  71                 ret = i2c_master_recv(data->client, result,
  72                                 indio_dev->num_channels);
  73                 if (ret < 0)
  74                         return ret;
  75
  76                 *val = result[pot];
  77                 return IIO_VAL_INT;
  78
  79         case IIO_CHAN_INFO_SCALE:
  80                 *val = 1000 * data->cfg->kohms;
  81                 *val2 = DS1803_MAX_POS;
  82                 return IIO_VAL_FRACTIONAL;
  83         }
  84
  85         return -EINVAL;
  86 }
  87
  88 static int ds1803_write_raw(struct iio_dev *indio_dev,
  89                              struct iio_chan_spec const *chan,
  90                              int val, int val2, long mask)
  91 {
  92         struct ds1803_data *data = iio_priv(indio_dev);
  93         int pot = chan->channel;
  94
  95         if (val2 != 0)
  96                 return -EINVAL;
  97
  98         switch (mask) {
  99         case IIO_CHAN_INFO_RAW:
 100                 if (val > DS1803_MAX_POS || val < 0)
 101                         return -EINVAL;
 102                 break;
 103         default:
 104                 return -EINVAL;
 105         }
 106
 107         return i2c_smbus_write_byte_data(data->client, DS1803_WRITE(pot), val);
 108 }
 109
 110 static const struct iio_info ds1803_info = {
 111         .read_raw = ds1803_read_raw,
 112         .write_raw = ds1803_write_raw,
 113         .driver_module = THIS_MODULE,
 114 };
 115
 116 static int ds1803_probe(struct i2c_client *client,
 117                          const struct i2c_device_id *id)
 118 {
 119         struct device *dev = &client->dev;
 120         struct ds1803_data *data;
 121         struct iio_dev *indio_dev;
 122
 123         indio_dev = devm_iio_device_alloc(dev, sizeof(*data));
 124         if (!indio_dev)
 125                 return -ENOMEM;
 126
 127         i2c_set_clientdata(client, indio_dev);
 128
 129         data = iio_priv(indio_dev);
 130         data->client = client;
 131         data->cfg = &ds1803_cfg[id->driver_data];
 132
 133         indio_dev->dev.parent = dev;
 134         indio_dev->info = &ds1803_info;
 135         indio_dev->channels = ds1803_channels;
 136         indio_dev->num_channels = ARRAY_SIZE(ds1803_channels);
 137         indio_dev->name = client->name;
 138
 139         return devm_iio_device_register(dev, indio_dev);
 140 }
 141
 142 #if defined(CONFIG_OF)
 143 static const struct of_device_id ds1803_dt_ids[] = {
 144         { .compatible = "maxim,ds1803-010", .data = &ds1803_cfg[DS1803_010] },
 145         { .compatible = "maxim,ds1803-050", .data = &ds1803_cfg[DS1803_050] },
 146         { .compatible = "maxim,ds1803-100", .data = &ds1803_cfg[DS1803_100] },
 147         {}
 148 };
 149 MODULE_DEVICE_TABLE(of, ds1803_dt_ids);
 150 #endif /* CONFIG_OF */
 151
 152 static const struct i2c_device_id ds1803_id[] = {
 153         { "ds1803-010", DS1803_010 },
 154         { "ds1803-050", DS1803_050 },
 155         { "ds1803-100", DS1803_100 },
 156         {}
 157 };
 158 MODULE_DEVICE_TABLE(i2c, ds1803_id);
 159
 160 static struct i2c_driver ds1803_driver = {
 161         .driver = {
 162                 .name   = "ds1803",
 163                 .of_match_table = of_match_ptr(ds1803_dt_ids),
 164         },
 165         .probe          = ds1803_probe,
 166         .id_table       = ds1803_id,
 167 };
 168
 169 module_i2c_driver(ds1803_driver);
 170
 171 MODULE_AUTHOR("Slawomir Stepien <sst@poczta.fm>");
 172 MODULE_DESCRIPTION("DS1803 digital potentiometer");
 173 MODULE_LICENSE("GPL v2");