1// SPDX-License-Identifier: GPL-2.0-or-later
2/*
3 * Copyright (C) 2023 Anshul Dalal <anshulusr@gmail.com>
4 *
5 * Driver for Aosong AGS02MA
6 *
7 * Datasheet:
8 *   https://asairsensors.com/wp-content/uploads/2021/09/AGS02MA.pdf
9 * Product Page:
10 *   http://www.aosong.com/m/en/products-33.html
11 */
12
13#include <linux/crc8.h>
14#include <linux/delay.h>
15#include <linux/i2c.h>
16#include <linux/module.h>
17
18#include <linux/iio/iio.h>
19
20#define AGS02MA_TVOC_READ_REG		   0x00
21#define AGS02MA_VERSION_REG		   0x11
22
23#define AGS02MA_VERSION_PROCESSING_DELAY   30
24#define AGS02MA_TVOC_READ_PROCESSING_DELAY 1500
25
26#define AGS02MA_CRC8_INIT		   0xff
27#define AGS02MA_CRC8_POLYNOMIAL		   0x31
28
29DECLARE_CRC8_TABLE(ags02ma_crc8_table);
30
31struct ags02ma_data {
32	struct i2c_client *client;
33};
34
35struct ags02ma_reading {
36	__be32 data;
37	u8 crc;
38} __packed;
39
40static int ags02ma_register_read(struct i2c_client *client, u8 reg, u16 delay,
41				 u32 *val)
42{
43	int ret;
44	u8 crc;
45	struct ags02ma_reading read_buffer;
46
47	ret = i2c_master_send(client, &reg, sizeof(reg));
48	if (ret < 0) {
49		dev_err(&client->dev,
50			"Failed to send data to register 0x%x: %d", reg, ret);
51		return ret;
52	}
53
54	/* Processing Delay, Check Table 7.7 in the datasheet */
55	msleep_interruptible(delay);
56
57	ret = i2c_master_recv(client, (u8 *)&read_buffer, sizeof(read_buffer));
58	if (ret < 0) {
59		dev_err(&client->dev,
60			"Failed to receive from register 0x%x: %d", reg, ret);
61		return ret;
62	}
63
64	crc = crc8(ags02ma_crc8_table, (u8 *)&read_buffer.data,
65		   sizeof(read_buffer.data), AGS02MA_CRC8_INIT);
66	if (crc != read_buffer.crc) {
67		dev_err(&client->dev, "CRC error\n");
68		return -EIO;
69	}
70
71	*val = be32_to_cpu(read_buffer.data);
72	return 0;
73}
74
75static int ags02ma_read_raw(struct iio_dev *iio_device,
76			    struct iio_chan_spec const *chan, int *val,
77			    int *val2, long mask)
78{
79	int ret;
80	struct ags02ma_data *data = iio_priv(iio_device);
81
82	switch (mask) {
83	case IIO_CHAN_INFO_RAW:
84		ret = ags02ma_register_read(data->client, AGS02MA_TVOC_READ_REG,
85					    AGS02MA_TVOC_READ_PROCESSING_DELAY,
86					    val);
87		if (ret < 0)
88			return ret;
89		return IIO_VAL_INT;
90	case IIO_CHAN_INFO_SCALE:
91		/* The sensor reads data as ppb */
92		*val = 0;
93		*val2 = 100;
94		return IIO_VAL_INT_PLUS_NANO;
95	default:
96		return -EINVAL;
97	}
98}
99
100static const struct iio_info ags02ma_info = {
101	.read_raw = ags02ma_read_raw,
102};
103
104static const struct iio_chan_spec ags02ma_channel = {
105	.type = IIO_CONCENTRATION,
106	.channel2 = IIO_MOD_VOC,
107	.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
108		BIT(IIO_CHAN_INFO_SCALE),
109};
110
111static int ags02ma_probe(struct i2c_client *client)
112{
113	int ret;
114	struct ags02ma_data *data;
115	struct iio_dev *indio_dev;
116	u32 version;
117
118	indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*data));
119	if (!indio_dev)
120		return -ENOMEM;
121
122	crc8_populate_msb(ags02ma_crc8_table, AGS02MA_CRC8_POLYNOMIAL);
123
124	ret = ags02ma_register_read(client, AGS02MA_VERSION_REG,
125				    AGS02MA_VERSION_PROCESSING_DELAY, &version);
126	if (ret < 0)
127		return dev_err_probe(&client->dev, ret,
128			      "Failed to read device version\n");
129	dev_dbg(&client->dev, "Aosong AGS02MA, Version: 0x%x", version);
130
131	data = iio_priv(indio_dev);
132	data->client = client;
133	indio_dev->info = &ags02ma_info;
134	indio_dev->channels = &ags02ma_channel;
135	indio_dev->num_channels = 1;
136	indio_dev->name = "ags02ma";
137
138	return devm_iio_device_register(&client->dev, indio_dev);
139}
140
141static const struct i2c_device_id ags02ma_id_table[] = {
142	{ "ags02ma" },
143	{ /* Sentinel */ }
144};
145MODULE_DEVICE_TABLE(i2c, ags02ma_id_table);
146
147static const struct of_device_id ags02ma_of_table[] = {
148	{ .compatible = "aosong,ags02ma" },
149	{ /* Sentinel */ }
150};
151MODULE_DEVICE_TABLE(of, ags02ma_of_table);
152
153static struct i2c_driver ags02ma_driver = {
154	.driver = {
155		.name = "ags02ma",
156		.of_match_table = ags02ma_of_table,
157	},
158	.id_table = ags02ma_id_table,
159	.probe = ags02ma_probe,
160};
161module_i2c_driver(ags02ma_driver);
162
163MODULE_AUTHOR("Anshul Dalal <anshulusr@gmail.com>");
164MODULE_DESCRIPTION("Aosong AGS02MA TVOC Driver");
165MODULE_LICENSE("GPL");
166