1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  * Digital temperature sensor with integrated Non-volatile memory
4  * Copyright (c) 2021 Puranjay Mohan <puranjay12@gmail.com>
5  *
6  * Driver for the Texas Instruments TMP117 Temperature Sensor
7  * (7-bit I2C slave address (0x48 - 0x4B), changeable via ADD pins)
8  *
9  * Note: This driver assumes that the sensor has been calibrated beforehand.
10  */
11 
12 #include <linux/err.h>
13 #include <linux/i2c.h>
14 #include <linux/module.h>
15 #include <linux/bitops.h>
16 #include <linux/types.h>
17 #include <linux/kernel.h>
18 #include <linux/limits.h>
19 
20 #include <linux/iio/iio.h>
21 
22 #define TMP117_REG_TEMP			0x0
23 #define TMP117_REG_CFGR			0x1
24 #define TMP117_REG_HIGH_LIM		0x2
25 #define TMP117_REG_LOW_LIM		0x3
26 #define TMP117_REG_EEPROM_UL		0x4
27 #define TMP117_REG_EEPROM1		0x5
28 #define TMP117_REG_EEPROM2		0x6
29 #define TMP117_REG_TEMP_OFFSET		0x7
30 #define TMP117_REG_EEPROM3		0x8
31 #define TMP117_REG_DEVICE_ID		0xF
32 
33 #define TMP117_RESOLUTION_10UC		78125
34 #define TMP117_DEVICE_ID		0x0117
35 #define MICRODEGREE_PER_10MILLIDEGREE	10000
36 
37 struct tmp117_data {
38 	struct i2c_client *client;
39 	s16 calibbias;
40 };
41 
tmp117_read_raw(struct iio_dev * indio_dev,struct iio_chan_spec const * channel,int * val,int * val2,long mask)42 static int tmp117_read_raw(struct iio_dev *indio_dev,
43 		struct iio_chan_spec const *channel, int *val,
44 		int *val2, long mask)
45 {
46 	struct tmp117_data *data = iio_priv(indio_dev);
47 	s32 ret;
48 
49 	switch (mask) {
50 	case IIO_CHAN_INFO_RAW:
51 		ret = i2c_smbus_read_word_swapped(data->client,
52 						TMP117_REG_TEMP);
53 		if (ret < 0)
54 			return ret;
55 		*val = sign_extend32(ret, 15);
56 		return IIO_VAL_INT;
57 
58 	case IIO_CHAN_INFO_CALIBBIAS:
59 		ret = i2c_smbus_read_word_swapped(data->client,
60 					TMP117_REG_TEMP_OFFSET);
61 		if (ret < 0)
62 			return ret;
63 		*val = sign_extend32(ret, 15);
64 		return IIO_VAL_INT;
65 
66 	case IIO_CHAN_INFO_SCALE:
67 		/*
68 		 * Conversion from 10s of uC to mC
69 		 * as IIO reports temperature in mC
70 		 */
71 		*val = TMP117_RESOLUTION_10UC / MICRODEGREE_PER_10MILLIDEGREE;
72 		*val2 = (TMP117_RESOLUTION_10UC %
73 					MICRODEGREE_PER_10MILLIDEGREE) * 100;
74 
75 		return IIO_VAL_INT_PLUS_MICRO;
76 
77 	default:
78 		return -EINVAL;
79 	}
80 }
81 
tmp117_write_raw(struct iio_dev * indio_dev,struct iio_chan_spec const * channel,int val,int val2,long mask)82 static int tmp117_write_raw(struct iio_dev *indio_dev,
83 		struct iio_chan_spec const *channel, int val,
84 		int val2, long mask)
85 {
86 	struct tmp117_data *data = iio_priv(indio_dev);
87 	s16 off;
88 
89 	switch (mask) {
90 	case IIO_CHAN_INFO_CALIBBIAS:
91 		off = clamp_t(int, val, S16_MIN, S16_MAX);
92 		if (off == data->calibbias)
93 			return 0;
94 		data->calibbias = off;
95 		return i2c_smbus_write_word_swapped(data->client,
96 						TMP117_REG_TEMP_OFFSET, off);
97 
98 	default:
99 		return -EINVAL;
100 	}
101 }
102 
103 static const struct iio_chan_spec tmp117_channels[] = {
104 	{
105 		.type = IIO_TEMP,
106 		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
107 			BIT(IIO_CHAN_INFO_CALIBBIAS) | BIT(IIO_CHAN_INFO_SCALE),
108 	},
109 };
110 
111 static const struct iio_info tmp117_info = {
112 	.read_raw = tmp117_read_raw,
113 	.write_raw = tmp117_write_raw,
114 };
115 
tmp117_identify(struct i2c_client * client)116 static int tmp117_identify(struct i2c_client *client)
117 {
118 	int dev_id;
119 
120 	dev_id = i2c_smbus_read_word_swapped(client, TMP117_REG_DEVICE_ID);
121 	if (dev_id < 0)
122 		return dev_id;
123 	if (dev_id != TMP117_DEVICE_ID) {
124 		dev_err(&client->dev, "TMP117 not found\n");
125 		return -ENODEV;
126 	}
127 	return 0;
128 }
129 
tmp117_probe(struct i2c_client * client)130 static int tmp117_probe(struct i2c_client *client)
131 {
132 	struct tmp117_data *data;
133 	struct iio_dev *indio_dev;
134 	int ret;
135 
136 	if (!i2c_check_functionality(client->adapter, I2C_FUNC_SMBUS_WORD_DATA))
137 		return -EOPNOTSUPP;
138 
139 	ret = tmp117_identify(client);
140 	if (ret < 0)
141 		return ret;
142 
143 	indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*data));
144 	if (!indio_dev)
145 		return -ENOMEM;
146 
147 	data = iio_priv(indio_dev);
148 	data->client = client;
149 	data->calibbias = 0;
150 
151 	indio_dev->name = "tmp117";
152 	indio_dev->modes = INDIO_DIRECT_MODE;
153 	indio_dev->info = &tmp117_info;
154 
155 	indio_dev->channels = tmp117_channels;
156 	indio_dev->num_channels = ARRAY_SIZE(tmp117_channels);
157 
158 	return devm_iio_device_register(&client->dev, indio_dev);
159 }
160 
161 static const struct of_device_id tmp117_of_match[] = {
162 	{ .compatible = "ti,tmp117", },
163 	{ }
164 };
165 MODULE_DEVICE_TABLE(of, tmp117_of_match);
166 
167 static const struct i2c_device_id tmp117_id[] = {
168 	{ "tmp117", 0 },
169 	{ }
170 };
171 MODULE_DEVICE_TABLE(i2c, tmp117_id);
172 
173 static struct i2c_driver tmp117_driver = {
174 	.driver = {
175 		.name	= "tmp117",
176 		.of_match_table = tmp117_of_match,
177 	},
178 	.probe_new	= tmp117_probe,
179 	.id_table	= tmp117_id,
180 };
181 module_i2c_driver(tmp117_driver);
182 
183 MODULE_AUTHOR("Puranjay Mohan <puranjay12@gmail.com>");
184 MODULE_DESCRIPTION("TI TMP117 Temperature sensor driver");
185 MODULE_LICENSE("GPL");
186