drivers/iio/potentiometer/mcp4018.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * Industrial I/O driver for Microchip digital potentiometers
   4  * Copyright (c) 2018  Axentia Technologies AB
   5  * Author: Peter Rosin <peda@axentia.se>
   6  *
   7  * Datasheet: http://www.microchip.com/downloads/en/DeviceDoc/22147a.pdf
   8  *
   9  * DEVID        #Wipers #Positions      Resistor Opts (kOhm)
  10  * mcp4017      1       128             5, 10, 50, 100
  11  * mcp4018      1       128             5, 10, 50, 100
  12  * mcp4019      1       128             5, 10, 50, 100
  13  */
  14
  15 #include <linux/err.h>
  16 #include <linux/i2c.h>
  17 #include <linux/iio/iio.h>
  18 #include <linux/module.h>
  19 #include <linux/of.h>
  20 #include <linux/of_device.h>
  21
  22 #define MCP4018_WIPER_MAX 127
  23
  24 struct mcp4018_cfg {
  25         int kohms;
  26 };
  27
  28 enum mcp4018_type {
  29         MCP4018_502,
  30         MCP4018_103,
  31         MCP4018_503,
  32         MCP4018_104,
  33 };
  34
  35 static const struct mcp4018_cfg mcp4018_cfg[] = {
  36         [MCP4018_502] = { .kohms =   5, },
  37         [MCP4018_103] = { .kohms =  10, },
  38         [MCP4018_503] = { .kohms =  50, },
  39         [MCP4018_104] = { .kohms = 100, },
  40 };
  41
  42 struct mcp4018_data {
  43         struct i2c_client *client;
  44         const struct mcp4018_cfg *cfg;
  45 };
  46
  47 static const struct iio_chan_spec mcp4018_channel = {
  48         .type = IIO_RESISTANCE,
  49         .indexed = 1,
  50         .output = 1,
  51         .channel = 0,
  52         .info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
  53         .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE),
  54 };
  55
  56 static int mcp4018_read_raw(struct iio_dev *indio_dev,
  57                             struct iio_chan_spec const *chan,
  58                             int *val, int *val2, long mask)
  59 {
  60         struct mcp4018_data *data = iio_priv(indio_dev);
  61         s32 ret;
  62
  63         switch (mask) {
  64         case IIO_CHAN_INFO_RAW:
  65                 ret = i2c_smbus_read_byte(data->client);
  66                 if (ret < 0)
  67                         return ret;
  68                 *val = ret;
  69                 return IIO_VAL_INT;
  70         case IIO_CHAN_INFO_SCALE:
  71                 *val = 1000 * data->cfg->kohms;
  72                 *val2 = MCP4018_WIPER_MAX;
  73                 return IIO_VAL_FRACTIONAL;
  74         }
  75
  76         return -EINVAL;
  77 }
  78
  79 static int mcp4018_write_raw(struct iio_dev *indio_dev,
  80                              struct iio_chan_spec const *chan,
  81                              int val, int val2, long mask)
  82 {
  83         struct mcp4018_data *data = iio_priv(indio_dev);
  84
  85         switch (mask) {
  86         case IIO_CHAN_INFO_RAW:
  87                 if (val > MCP4018_WIPER_MAX || val < 0)
  88                         return -EINVAL;
  89                 break;
  90         default:
  91                 return -EINVAL;
  92         }
  93
  94         return i2c_smbus_write_byte(data->client, val);
  95 }
  96
  97 static const struct iio_info mcp4018_info = {
  98         .read_raw = mcp4018_read_raw,
  99         .write_raw = mcp4018_write_raw,
 100 };
 101
 102 static const struct i2c_device_id mcp4018_id[] = {
 103         { "mcp4017-502", MCP4018_502 },
 104         { "mcp4017-103", MCP4018_103 },
 105         { "mcp4017-503", MCP4018_503 },
 106         { "mcp4017-104", MCP4018_104 },
 107         { "mcp4018-502", MCP4018_502 },
 108         { "mcp4018-103", MCP4018_103 },
 109         { "mcp4018-503", MCP4018_503 },
 110         { "mcp4018-104", MCP4018_104 },
 111         { "mcp4019-502", MCP4018_502 },
 112         { "mcp4019-103", MCP4018_103 },
 113         { "mcp4019-503", MCP4018_503 },
 114         { "mcp4019-104", MCP4018_104 },
 115         {}
 116 };
 117 MODULE_DEVICE_TABLE(i2c, mcp4018_id);
 118
 119 #ifdef CONFIG_OF
 120
 121 #define MCP4018_COMPATIBLE(of_compatible, cfg) {        \
 122         .compatible = of_compatible,                    \
 123         .data = &mcp4018_cfg[cfg],                      \
 124 }
 125
 126 static const struct of_device_id mcp4018_of_match[] = {
 127         MCP4018_COMPATIBLE("microchip,mcp4017-502", MCP4018_502),
 128         MCP4018_COMPATIBLE("microchip,mcp4017-103", MCP4018_103),
 129         MCP4018_COMPATIBLE("microchip,mcp4017-503", MCP4018_503),
 130         MCP4018_COMPATIBLE("microchip,mcp4017-104", MCP4018_104),
 131         MCP4018_COMPATIBLE("microchip,mcp4018-502", MCP4018_502),
 132         MCP4018_COMPATIBLE("microchip,mcp4018-103", MCP4018_103),
 133         MCP4018_COMPATIBLE("microchip,mcp4018-503", MCP4018_503),
 134         MCP4018_COMPATIBLE("microchip,mcp4018-104", MCP4018_104),
 135         MCP4018_COMPATIBLE("microchip,mcp4019-502", MCP4018_502),
 136         MCP4018_COMPATIBLE("microchip,mcp4019-103", MCP4018_103),
 137         MCP4018_COMPATIBLE("microchip,mcp4019-503", MCP4018_503),
 138         MCP4018_COMPATIBLE("microchip,mcp4019-104", MCP4018_104),
 139         { /* sentinel */ }
 140 };
 141 MODULE_DEVICE_TABLE(of, mcp4018_of_match);
 142
 143 #endif
 144
 145 static int mcp4018_probe(struct i2c_client *client)
 146 {
 147         struct device *dev = &client->dev;
 148         struct mcp4018_data *data;
 149         struct iio_dev *indio_dev;
 150         const struct of_device_id *match;
 151
 152         if (!i2c_check_functionality(client->adapter,
 153                                      I2C_FUNC_SMBUS_BYTE)) {
 154                 dev_err(dev, "SMBUS Byte transfers not supported\n");
 155                 return -EOPNOTSUPP;
 156         }
 157
 158         indio_dev = devm_iio_device_alloc(dev, sizeof(*data));
 159         if (!indio_dev)
 160                 return -ENOMEM;
 161         data = iio_priv(indio_dev);
 162         i2c_set_clientdata(client, indio_dev);
 163         data->client = client;
 164
 165         match = of_match_device(of_match_ptr(mcp4018_of_match), dev);
 166         if (match)
 167                 data->cfg = of_device_get_match_data(dev);
 168         else
 169                 data->cfg = &mcp4018_cfg[i2c_match_id(mcp4018_id, client)->driver_data];
 170
 171         indio_dev->dev.parent = dev;
 172         indio_dev->info = &mcp4018_info;
 173         indio_dev->channels = &mcp4018_channel;
 174         indio_dev->num_channels = 1;
 175         indio_dev->name = client->name;
 176
 177         return devm_iio_device_register(dev, indio_dev);
 178 }
 179
 180 static struct i2c_driver mcp4018_driver = {
 181         .driver = {
 182                 .name   = "mcp4018",
 183                 .of_match_table = of_match_ptr(mcp4018_of_match),
 184         },
 185         .probe_new      = mcp4018_probe,
 186         .id_table       = mcp4018_id,
 187 };
 188
 189 module_i2c_driver(mcp4018_driver);
 190
 191 MODULE_AUTHOR("Peter Rosin <peda@axentia.se>");
 192 MODULE_DESCRIPTION("MCP4018 digital potentiometer");
 193 MODULE_LICENSE("GPL");