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
25static 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
42struct mcp9600_data {
43 struct i2c_client *client;
44};
45
46static 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(client: data->client, command: chan->address);
52
53 if (ret < 0)
54 return ret;
55 *val = ret;
56
57 return 0;
58}
59
60static 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
82static const struct iio_info mcp9600_info = {
83 .read_raw = mcp9600_read_raw,
84};
85
86static 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(dev: &client->dev, err: ret, fmt: "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(parent: &client->dev, sizeof_priv: 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
115static const struct i2c_device_id mcp9600_id[] = {
116 { "mcp9600" },
117 {}
118};
119MODULE_DEVICE_TABLE(i2c, mcp9600_id);
120
121static const struct of_device_id mcp9600_of_match[] = {
122 { .compatible = "microchip,mcp9600" },
123 {}
124};
125MODULE_DEVICE_TABLE(of, mcp9600_of_match);
126
127static 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};
135module_i2c_driver(mcp9600_driver);
136
137MODULE_AUTHOR("Andrew Hepp <andrew.hepp@ahepp.dev>");
138MODULE_DESCRIPTION("Microchip MCP9600 thermocouple EMF converter driver");
139MODULE_LICENSE("GPL");
140

source code of linux/drivers/iio/temperature/mcp9600.c