xref: /linux/drivers/iio/temperature/mcp9600.c (revision 9a95c5bfbf02a0a7f5983280fe284a0ff0836c34)
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 
56 	*val = sign_extend32(ret, 15);
57 
58 	return 0;
59 }
60 
61 static int mcp9600_read_raw(struct iio_dev *indio_dev,
62 			    struct iio_chan_spec const *chan, int *val,
63 			    int *val2, long mask)
64 {
65 	struct mcp9600_data *data = iio_priv(indio_dev);
66 	int ret;
67 
68 	switch (mask) {
69 	case IIO_CHAN_INFO_RAW:
70 		ret = mcp9600_read(data, chan, val);
71 		if (ret)
72 			return ret;
73 		return IIO_VAL_INT;
74 	case IIO_CHAN_INFO_SCALE:
75 		*val = 62;
76 		*val2 = 500000;
77 		return IIO_VAL_INT_PLUS_MICRO;
78 	default:
79 		return -EINVAL;
80 	}
81 }
82 
83 static const struct iio_info mcp9600_info = {
84 	.read_raw = mcp9600_read_raw,
85 };
86 
87 static int mcp9600_probe(struct i2c_client *client)
88 {
89 	struct iio_dev *indio_dev;
90 	struct mcp9600_data *data;
91 	int ret;
92 
93 	ret = i2c_smbus_read_byte_data(client, MCP9600_DEVICE_ID);
94 	if (ret < 0)
95 		return dev_err_probe(&client->dev, ret, "Failed to read device ID\n");
96 	if (ret != MCP9600_DEVICE_ID_MCP9600)
97 		dev_warn(&client->dev, "Expected ID %x, got %x\n",
98 				MCP9600_DEVICE_ID_MCP9600, ret);
99 
100 	indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*data));
101 	if (!indio_dev)
102 		return -ENOMEM;
103 
104 	data = iio_priv(indio_dev);
105 	data->client = client;
106 
107 	indio_dev->info = &mcp9600_info;
108 	indio_dev->name = "mcp9600";
109 	indio_dev->modes = INDIO_DIRECT_MODE;
110 	indio_dev->channels = mcp9600_channels;
111 	indio_dev->num_channels = ARRAY_SIZE(mcp9600_channels);
112 
113 	return devm_iio_device_register(&client->dev, indio_dev);
114 }
115 
116 static const struct i2c_device_id mcp9600_id[] = {
117 	{ "mcp9600" },
118 	{}
119 };
120 MODULE_DEVICE_TABLE(i2c, mcp9600_id);
121 
122 static const struct of_device_id mcp9600_of_match[] = {
123 	{ .compatible = "microchip,mcp9600" },
124 	{}
125 };
126 MODULE_DEVICE_TABLE(of, mcp9600_of_match);
127 
128 static struct i2c_driver mcp9600_driver = {
129 	.driver = {
130 		.name = "mcp9600",
131 		.of_match_table = mcp9600_of_match,
132 	},
133 	.probe = mcp9600_probe,
134 	.id_table = mcp9600_id
135 };
136 module_i2c_driver(mcp9600_driver);
137 
138 MODULE_AUTHOR("Andrew Hepp <andrew.hepp@ahepp.dev>");
139 MODULE_DESCRIPTION("Microchip MCP9600 thermocouple EMF converter driver");
140 MODULE_LICENSE("GPL");
141