1 // SPDX-License-Identifier: GPL-2.0+
2 /*
3  * ams-iaq-core.c - Support for AMS iAQ-Core VOC sensors
4  *
5  * Copyright (C) 2015, 2018
6  * Author: Matt Ranostay <matt.ranostay@konsulko.com>
7  */
8 
9 #include <linux/module.h>
10 #include <linux/mod_devicetable.h>
11 #include <linux/mutex.h>
12 #include <linux/init.h>
13 #include <linux/i2c.h>
14 #include <linux/iio/iio.h>
15 
16 #define AMS_IAQCORE_DATA_SIZE		9
17 
18 #define AMS_IAQCORE_VOC_CO2_IDX		0
19 #define AMS_IAQCORE_VOC_RESISTANCE_IDX	1
20 #define AMS_IAQCORE_VOC_TVOC_IDX	2
21 
22 struct ams_iaqcore_reading {
23 	__be16 co2_ppm;
24 	u8 status;
25 	__be32 resistance;
26 	__be16 voc_ppb;
27 } __attribute__((__packed__));
28 
29 struct ams_iaqcore_data {
30 	struct i2c_client *client;
31 	struct mutex lock;
32 	unsigned long last_update;
33 
34 	struct ams_iaqcore_reading buffer;
35 };
36 
37 static const struct iio_chan_spec ams_iaqcore_channels[] = {
38 	{
39 		.type = IIO_CONCENTRATION,
40 		.channel2 = IIO_MOD_CO2,
41 		.modified = 1,
42 		.info_mask_separate = BIT(IIO_CHAN_INFO_PROCESSED),
43 		.address = AMS_IAQCORE_VOC_CO2_IDX,
44 	},
45 	{
46 		.type = IIO_RESISTANCE,
47 		.info_mask_separate = BIT(IIO_CHAN_INFO_PROCESSED),
48 		.address = AMS_IAQCORE_VOC_RESISTANCE_IDX,
49 	},
50 	{
51 		.type = IIO_CONCENTRATION,
52 		.channel2 = IIO_MOD_VOC,
53 		.modified = 1,
54 		.info_mask_separate = BIT(IIO_CHAN_INFO_PROCESSED),
55 		.address = AMS_IAQCORE_VOC_TVOC_IDX,
56 	},
57 };
58 
59 static int ams_iaqcore_read_measurement(struct ams_iaqcore_data *data)
60 {
61 	struct i2c_client *client = data->client;
62 	int ret;
63 
64 	struct i2c_msg msg = {
65 		.addr = client->addr,
66 		.flags = client->flags | I2C_M_RD,
67 		.len = AMS_IAQCORE_DATA_SIZE,
68 		.buf = (char *) &data->buffer,
69 	};
70 
71 	ret = i2c_transfer(client->adapter, &msg, 1);
72 
73 	return (ret == AMS_IAQCORE_DATA_SIZE) ? 0 : ret;
74 }
75 
76 static int ams_iaqcore_get_measurement(struct ams_iaqcore_data *data)
77 {
78 	int ret;
79 
80 	/* sensor can only be polled once a second max per datasheet */
81 	if (!time_after(jiffies, data->last_update + HZ))
82 		return 0;
83 
84 	ret = ams_iaqcore_read_measurement(data);
85 	if (ret < 0)
86 		return ret;
87 
88 	data->last_update = jiffies;
89 
90 	return 0;
91 }
92 
93 static int ams_iaqcore_read_raw(struct iio_dev *indio_dev,
94 				struct iio_chan_spec const *chan, int *val,
95 				int *val2, long mask)
96 {
97 	struct ams_iaqcore_data *data = iio_priv(indio_dev);
98 	int ret;
99 
100 	if (mask != IIO_CHAN_INFO_PROCESSED)
101 		return -EINVAL;
102 
103 	mutex_lock(&data->lock);
104 	ret = ams_iaqcore_get_measurement(data);
105 
106 	if (ret)
107 		goto err_out;
108 
109 	switch (chan->address) {
110 	case AMS_IAQCORE_VOC_CO2_IDX:
111 		*val = 0;
112 		*val2 = be16_to_cpu(data->buffer.co2_ppm);
113 		ret = IIO_VAL_INT_PLUS_MICRO;
114 		break;
115 	case AMS_IAQCORE_VOC_RESISTANCE_IDX:
116 		*val = be32_to_cpu(data->buffer.resistance);
117 		ret = IIO_VAL_INT;
118 		break;
119 	case AMS_IAQCORE_VOC_TVOC_IDX:
120 		*val = 0;
121 		*val2 = be16_to_cpu(data->buffer.voc_ppb);
122 		ret = IIO_VAL_INT_PLUS_NANO;
123 		break;
124 	default:
125 		ret = -EINVAL;
126 	}
127 
128 err_out:
129 	mutex_unlock(&data->lock);
130 
131 	return ret;
132 }
133 
134 static const struct iio_info ams_iaqcore_info = {
135 	.read_raw	= ams_iaqcore_read_raw,
136 };
137 
138 static int ams_iaqcore_probe(struct i2c_client *client)
139 {
140 	struct iio_dev *indio_dev;
141 	struct ams_iaqcore_data *data;
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 	i2c_set_clientdata(client, indio_dev);
149 	data->client = client;
150 
151 	/* so initial reading will complete */
152 	data->last_update = jiffies - HZ;
153 	mutex_init(&data->lock);
154 
155 	indio_dev->info = &ams_iaqcore_info;
156 	indio_dev->name = dev_name(&client->dev);
157 	indio_dev->modes = INDIO_DIRECT_MODE;
158 
159 	indio_dev->channels = ams_iaqcore_channels;
160 	indio_dev->num_channels = ARRAY_SIZE(ams_iaqcore_channels);
161 
162 	return devm_iio_device_register(&client->dev, indio_dev);
163 }
164 
165 static const struct i2c_device_id ams_iaqcore_id[] = {
166 	{ "ams-iaq-core", 0 },
167 	{ }
168 };
169 MODULE_DEVICE_TABLE(i2c, ams_iaqcore_id);
170 
171 static const struct of_device_id ams_iaqcore_dt_ids[] = {
172 	{ .compatible = "ams,iaq-core" },
173 	{ }
174 };
175 MODULE_DEVICE_TABLE(of, ams_iaqcore_dt_ids);
176 
177 static struct i2c_driver ams_iaqcore_driver = {
178 	.driver = {
179 		.name	= "ams-iaq-core",
180 		.of_match_table = ams_iaqcore_dt_ids,
181 	},
182 	.probe = ams_iaqcore_probe,
183 	.id_table = ams_iaqcore_id,
184 };
185 module_i2c_driver(ams_iaqcore_driver);
186 
187 MODULE_AUTHOR("Matt Ranostay <matt.ranostay@konsulko.com>");
188 MODULE_DESCRIPTION("AMS iAQ-Core VOC sensors");
189 MODULE_LICENSE("GPL v2");
190