ams-iaq-core.c

  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
 22struct ams_iaqcore_reading {
 23	__be16 co2_ppm;
 24	u8 status;
 25	__be32 resistance;
 26	__be16 voc_ppb;
 27} __packed;
 28
 29struct 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
 37static 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
 59static 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
 76static 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
 93static 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
128err_out:
129	mutex_unlock(&data->lock);
130
131	return ret;
132}
133
134static const struct iio_info ams_iaqcore_info = {
135	.read_raw	= ams_iaqcore_read_raw,
136};
137
138static 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
165static const struct i2c_device_id ams_iaqcore_id[] = {
166	{ "ams-iaq-core" },
167	{ }
168};
169MODULE_DEVICE_TABLE(i2c, ams_iaqcore_id);
170
171static const struct of_device_id ams_iaqcore_dt_ids[] = {
172	{ .compatible = "ams,iaq-core" },
173	{ }
174};
175MODULE_DEVICE_TABLE(of, ams_iaqcore_dt_ids);
176
177static 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};
185module_i2c_driver(ams_iaqcore_driver);
186
187MODULE_AUTHOR("Matt Ranostay <matt.ranostay@konsulko.com>");
188MODULE_DESCRIPTION("AMS iAQ-Core VOC sensors");
189MODULE_LICENSE("GPL v2");