drivers/iio/temperature/mcp9600.c

   1 // SPDX-License-Identifier: GPL-2.0+
   2 /*
   3  * mcp9600.c - Support for Microchip MCP9600 thermocouple EMF converter
   4  *
   5  * Copyright (c) 2022 Andrew Hepp
   6  * Author: <andrew.hepp@ahepp.dev>
   7  */
   8
   9 #include <linux/err.h>
  10 #include <linux/i2c.h>
  11 #include <linux/init.h>
  12 #include <linux/mod_devicetable.h>
  13 #include <linux/module.h>
  14
  15 #include <linux/iio/iio.h>
  16
  17 /* MCP9600 registers */
  18 #define MCP9600_HOT_JUNCTION 0x0
  19 #define MCP9600_COLD_JUNCTION 0x2
  20 #define MCP9600_DEVICE_ID 0x20
  21
  22 /* MCP9600 device id value */
  23 #define MCP9600_DEVICE_ID_MCP9600 0x40
  24
  25 static const struct iio_chan_spec mcp9600_channels[] = {
  26         {
  27                 .type = IIO_TEMP,
  28                 .address = MCP9600_HOT_JUNCTION,
  29                 .info_mask_separate =
  30                         BIT(IIO_CHAN_INFO_RAW) | BIT(IIO_CHAN_INFO_SCALE),
  31         },
  32         {
  33                 .type = IIO_TEMP,
  34                 .address = MCP9600_COLD_JUNCTION,
  35                 .channel2 = IIO_MOD_TEMP_AMBIENT,
  36                 .modified = 1,
  37                 .info_mask_separate =
  38                         BIT(IIO_CHAN_INFO_RAW) | BIT(IIO_CHAN_INFO_SCALE),
  39         },
  40 };
  41
  42 struct mcp9600_data {
  43         struct i2c_client *client;
  44 };
  45
  46 static int mcp9600_read(struct mcp9600_data *data,
  47                         struct iio_chan_spec const *chan, int *val)
  48 {
  49         int ret;
  50
  51         ret = i2c_smbus_read_word_swapped(data->client, chan->address);
  52
  53         if (ret < 0)
  54                 return ret;
  55         *val = ret;
  56
  57         return 0;
  58 }
  59
  60 static int mcp9600_read_raw(struct iio_dev *indio_dev,
  61                             struct iio_chan_spec const *chan, int *val,
  62                             int *val2, long mask)
  63 {
  64         struct mcp9600_data *data = iio_priv(indio_dev);
  65         int ret;
  66
  67         switch (mask) {
  68         case IIO_CHAN_INFO_RAW:
  69                 ret = mcp9600_read(data, chan, val);
  70                 if (ret)
  71                         return ret;
  72                 return IIO_VAL_INT;
  73         case IIO_CHAN_INFO_SCALE:
  74                 *val = 62;
  75                 *val2 = 500000;
  76                 return IIO_VAL_INT_PLUS_MICRO;
  77         default:
  78                 return -EINVAL;
  79         }
  80 }
  81
  82 static const struct iio_info mcp9600_info = {
  83         .read_raw = mcp9600_read_raw,
  84 };
  85
  86 static int mcp9600_probe(struct i2c_client *client)
  87 {
  88         struct iio_dev *indio_dev;
  89         struct mcp9600_data *data;
  90         int ret;
  91
  92         ret = i2c_smbus_read_byte_data(client, MCP9600_DEVICE_ID);
  93         if (ret < 0)
  94                 return dev_err_probe(&client->dev, ret, "Failed to read device ID\n");
  95         if (ret != MCP9600_DEVICE_ID_MCP9600)
  96                 dev_warn(&client->dev, "Expected ID %x, got %x\n",
  97                                 MCP9600_DEVICE_ID_MCP9600, ret);
  98
  99         indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*data));
 100         if (!indio_dev)
 101                 return -ENOMEM;
 102
 103         data = iio_priv(indio_dev);
 104         data->client = client;
 105
 106         indio_dev->info = &mcp9600_info;
 107         indio_dev->name = "mcp9600";
 108         indio_dev->modes = INDIO_DIRECT_MODE;
 109         indio_dev->channels = mcp9600_channels;
 110         indio_dev->num_channels = ARRAY_SIZE(mcp9600_channels);
 111
 112         return devm_iio_device_register(&client->dev, indio_dev);
 113 }
 114
 115 static const struct i2c_device_id mcp9600_id[] = {
 116         { "mcp9600" },
 117         {}
 118 };
 119 MODULE_DEVICE_TABLE(i2c, mcp9600_id);
 120
 121 static const struct of_device_id mcp9600_of_match[] = {
 122         { .compatible = "microchip,mcp9600" },
 123         {}
 124 };
 125 MODULE_DEVICE_TABLE(of, mcp9600_of_match);
 126
 127 static struct i2c_driver mcp9600_driver = {
 128         .driver = {
 129                 .name = "mcp9600",
 130                 .of_match_table = mcp9600_of_match,
 131         },
 132         .probe = mcp9600_probe,
 133         .id_table = mcp9600_id
 134 };
 135 module_i2c_driver(mcp9600_driver);
 136
 137 MODULE_AUTHOR("Andrew Hepp <andrew.hepp@ahepp.dev>");
 138 MODULE_DESCRIPTION("Microchip MCP9600 thermocouple EMF converter driver");
 139 MODULE_LICENSE("GPL");