1 // SPDX-License-Identifier: GPL-2.0+
2 /*
3  * atlas-ezo-sensor.c - Support for Atlas Scientific EZO sensors
4  *
5  * Copyright (C) 2020 Konsulko Group
6  * Author: Matt Ranostay <matt.ranostay@konsulko.com>
7  */
8 
9 #include <linux/module.h>
10 #include <linux/init.h>
11 #include <linux/delay.h>
12 #include <linux/mutex.h>
13 #include <linux/err.h>
14 #include <linux/i2c.h>
15 #include <linux/of_device.h>
16 #include <linux/iio/iio.h>
17 
18 #define ATLAS_EZO_DRV_NAME		"atlas-ezo-sensor"
19 #define ATLAS_CO2_INT_TIME_IN_MS	950
20 
21 enum {
22 	ATLAS_CO2_EZO,
23 };
24 
25 struct atlas_ezo_device {
26 	const struct iio_chan_spec *channels;
27 	int num_channels;
28 	int delay;
29 };
30 
31 struct atlas_ezo_data {
32 	struct i2c_client *client;
33 	struct atlas_ezo_device *chip;
34 
35 	/* lock to avoid multiple concurrent read calls */
36 	struct mutex lock;
37 
38 	u8 buffer[8];
39 };
40 
41 static const struct iio_chan_spec atlas_co2_ezo_channels[] = {
42 	{
43 		.type = IIO_CONCENTRATION,
44 		.modified = 1,
45 		.channel2 = IIO_MOD_CO2,
46 		.info_mask_separate =
47 			BIT(IIO_CHAN_INFO_RAW) | BIT(IIO_CHAN_INFO_SCALE),
48 		.scan_index = 0,
49 		.scan_type = {
50 			.sign = 'u',
51 			.realbits = 32,
52 			.storagebits = 32,
53 			.endianness = IIO_CPU,
54 		},
55 	},
56 };
57 
58 static struct atlas_ezo_device atlas_ezo_devices[] = {
59 	[ATLAS_CO2_EZO] = {
60 		.channels = atlas_co2_ezo_channels,
61 		.num_channels = 1,
62 		.delay = ATLAS_CO2_INT_TIME_IN_MS,
63 	},
64 };
65 
66 static int atlas_ezo_read_raw(struct iio_dev *indio_dev,
67 			  struct iio_chan_spec const *chan,
68 			  int *val, int *val2, long mask)
69 {
70 	struct atlas_ezo_data *data = iio_priv(indio_dev);
71 	struct i2c_client *client = data->client;
72 	int ret = 0;
73 
74 	if (chan->type != IIO_CONCENTRATION)
75 		return -EINVAL;
76 
77 	switch (mask) {
78 	case IIO_CHAN_INFO_RAW: {
79 		long tmp;
80 
81 		mutex_lock(&data->lock);
82 
83 		tmp = i2c_smbus_write_byte(client, 'R');
84 
85 		if (tmp < 0) {
86 			mutex_unlock(&data->lock);
87 			return tmp;
88 		}
89 
90 		msleep(data->chip->delay);
91 
92 		tmp = i2c_master_recv(client, data->buffer, sizeof(data->buffer));
93 
94 		if (tmp < 0 || data->buffer[0] != 1) {
95 			mutex_unlock(&data->lock);
96 			return -EBUSY;
97 		}
98 
99 		ret = kstrtol(data->buffer + 1, 10, &tmp);
100 
101 		*val = tmp;
102 
103 		mutex_unlock(&data->lock);
104 
105 		return ret ? ret : IIO_VAL_INT;
106 	}
107 	case IIO_CHAN_INFO_SCALE:
108 		*val = 0;
109 		*val2 = 100; /* 0.0001 */
110 		return IIO_VAL_INT_PLUS_MICRO;
111 	}
112 
113 	return ret;
114 }
115 
116 static const struct iio_info atlas_info = {
117 	.read_raw = atlas_ezo_read_raw,
118 };
119 
120 static const struct i2c_device_id atlas_ezo_id[] = {
121 	{ "atlas-co2-ezo", ATLAS_CO2_EZO },
122 	{}
123 };
124 MODULE_DEVICE_TABLE(i2c, atlas_ezo_id);
125 
126 static const struct of_device_id atlas_ezo_dt_ids[] = {
127 	{ .compatible = "atlas,co2-ezo", .data = (void *)ATLAS_CO2_EZO, },
128 	{}
129 };
130 MODULE_DEVICE_TABLE(of, atlas_ezo_dt_ids);
131 
132 static int atlas_ezo_probe(struct i2c_client *client,
133 		       const struct i2c_device_id *id)
134 {
135 	struct atlas_ezo_data *data;
136 	struct atlas_ezo_device *chip;
137 	const struct of_device_id *of_id;
138 	struct iio_dev *indio_dev;
139 
140 	indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*data));
141 	if (!indio_dev)
142 		return -ENOMEM;
143 
144 	of_id = of_match_device(atlas_ezo_dt_ids, &client->dev);
145 	if (!of_id)
146 		chip = &atlas_ezo_devices[id->driver_data];
147 	else
148 		chip = &atlas_ezo_devices[(unsigned long)of_id->data];
149 
150 	indio_dev->info = &atlas_info;
151 	indio_dev->name = ATLAS_EZO_DRV_NAME;
152 	indio_dev->channels = chip->channels;
153 	indio_dev->num_channels = chip->num_channels;
154 	indio_dev->modes = INDIO_DIRECT_MODE;
155 	indio_dev->dev.parent = &client->dev;
156 
157 	data = iio_priv(indio_dev);
158 	data->client = client;
159 	data->chip = chip;
160 	mutex_init(&data->lock);
161 
162 	return devm_iio_device_register(&client->dev, indio_dev);
163 };
164 
165 static struct i2c_driver atlas_ezo_driver = {
166 	.driver = {
167 		.name	= ATLAS_EZO_DRV_NAME,
168 		.of_match_table	= atlas_ezo_dt_ids,
169 	},
170 	.probe		= atlas_ezo_probe,
171 	.id_table	= atlas_ezo_id,
172 };
173 module_i2c_driver(atlas_ezo_driver);
174 
175 MODULE_AUTHOR("Matt Ranostay <matt.ranostay@konsulko.com>");
176 MODULE_DESCRIPTION("Atlas Scientific EZO sensors");
177 MODULE_LICENSE("GPL");
178