iio: chemical: sgp30: Support Sensirion SGP30/SGPC3 sensors

Support Sensirion SGP30 and SGPC3 multi-pixel I2C gas sensors

Supported Features:

* Indoor Air Quality (IAQ) concentrations for
  - tVOC (in_concentration_voc_input)
  - CO2eq (in_concentration_co2_input) - SGP30 only

  IAQ concentrations are periodically read out by a background thread
  to allow the sensor to maintain its internal baseline.

* Gas concentration signals
  - Ethanol (in_concentration_ethanol_raw)
  - H2 (in_concentration_h2_raw) - SGP30 only

https://www.sensirion.com/file/datasheet_sgp30
https://www.sensirion.com/file/datasheet_sgpc3Signed-off-by: Andreas Brauchli <andreas.brauchli@sensirion.com>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

drivers/iio/chemical/Makefile

@@ -9,5 +9,6 @@ obj-$(CONFIG_BME680_I2C) += bme680_i2c.o
 obj-$(CONFIG_BME680_SPI) += bme680_spi.o
 obj-$(CONFIG_CCS811)		+= ccs811.o
 obj-$(CONFIG_IAQCORE)		+= ams-iaq-core.o
+obj-$(CONFIG_SENSIRION_SGP30)	+= sgp30.o
 obj-$(CONFIG_SPS30) += sps30.o
 obj-$(CONFIG_VZ89X)		+= vz89x.o

drivers/iio/chemical/sgp30.c

+// SPDX-License-Identifier: GPL-2.0
+/*
+ * sgp30.c - Support for Sensirion SGP Gas Sensors
+ *
+ * Copyright (C) 2018 Andreas Brauchli <andreas.brauchli@sensirion.com>
+ *
+ * I2C slave address: 0x58
+ *
+ * Datasheets:
+ * https://www.sensirion.com/file/datasheet_sgp30
+ * https://www.sensirion.com/file/datasheet_sgpc3
+ *
+ * TODO:
+ * - baseline support
+ * - humidity compensation
+ * - power mode switching (SGPC3)
+ */
+
+#include <linux/crc8.h>
+#include <linux/delay.h>
+#include <linux/kthread.h>
+#include <linux/module.h>
+#include <linux/mutex.h>
+#include <linux/i2c.h>
+#include <linux/of_device.h>
+#include <linux/iio/iio.h>
+#include <linux/iio/sysfs.h>
+
+#define SGP_WORD_LEN				2
+#define SGP_CRC8_POLYNOMIAL			0x31
+#define SGP_CRC8_INIT				0xff
+#define SGP_CRC8_LEN				1
+#define SGP_CMD(cmd_word)			cpu_to_be16(cmd_word)
+#define SGP_CMD_DURATION_US			12000
+#define SGP_MEASUREMENT_DURATION_US		50000
+#define SGP_CMD_LEN				SGP_WORD_LEN
+#define SGP_CMD_MAX_BUF_SIZE			(SGP_CMD_LEN + 2 * SGP_WORD_LEN)
+#define SGP_MEASUREMENT_LEN			2
+#define SGP30_MEASURE_INTERVAL_HZ		1
+#define SGPC3_MEASURE_INTERVAL_HZ		2
+#define SGP_VERS_PRODUCT(data)	((((data)->feature_set) & 0xf000) >> 12)
+#define SGP_VERS_RESERVED(data)	((((data)->feature_set) & 0x0800) >> 11)
+#define SGP_VERS_GEN(data)	((((data)->feature_set) & 0x0600) >> 9)
+#define SGP_VERS_ENG_BIT(data)	((((data)->feature_set) & 0x0100) >> 8)
+#define SGP_VERS_MAJOR(data)	((((data)->feature_set) & 0x00e0) >> 5)
+#define SGP_VERS_MINOR(data)	(((data)->feature_set) & 0x001f)
+
+DECLARE_CRC8_TABLE(sgp_crc8_table);
+
+enum sgp_product_id {
+	SGP30 = 0,
+	SGPC3,
+};
+
+enum sgp30_channel_idx {
+	SGP30_IAQ_TVOC_IDX = 0,
+	SGP30_IAQ_CO2EQ_IDX,
+	SGP30_SIG_ETOH_IDX,
+	SGP30_SIG_H2_IDX,
+};
+
+enum sgpc3_channel_idx {
+	SGPC3_IAQ_TVOC_IDX = 10,
+	SGPC3_SIG_ETOH_IDX,
+};
+
+enum sgp_cmd {
+	SGP_CMD_IAQ_INIT			= SGP_CMD(0x2003),
+	SGP_CMD_IAQ_MEASURE			= SGP_CMD(0x2008),
+	SGP_CMD_GET_FEATURE_SET			= SGP_CMD(0x202f),
+	SGP_CMD_GET_SERIAL_ID			= SGP_CMD(0x3682),
+
+	SGP30_CMD_MEASURE_SIGNAL		= SGP_CMD(0x2050),
+
+	SGPC3_CMD_MEASURE_RAW			= SGP_CMD(0x2046),
+};
+
+struct sgp_version {
+	u8 major;
+	u8 minor;
+};
+
+struct sgp_crc_word {
+	__be16 value;
+	u8 crc8;
+} __attribute__((__packed__));
+
+union sgp_reading {
+	u8 start;
+	struct sgp_crc_word raw_words[4];
+};
+
+enum _iaq_buffer_state {
+	IAQ_BUFFER_EMPTY = 0,
+	IAQ_BUFFER_DEFAULT_VALS,
+	IAQ_BUFFER_VALID,
+};
+
+struct sgp_data {
+	struct i2c_client *client;
+	struct task_struct *iaq_thread;
+	struct mutex data_lock;
+	unsigned long iaq_init_start_jiffies;
+	unsigned long iaq_defval_skip_jiffies;
+	u16 product_id;
+	u16 feature_set;
+	unsigned long measure_interval_jiffies;
+	enum sgp_cmd iaq_init_cmd;
+	enum sgp_cmd measure_iaq_cmd;
+	enum sgp_cmd measure_gas_signals_cmd;
+	union sgp_reading buffer;
+	union sgp_reading iaq_buffer;
+	enum _iaq_buffer_state iaq_buffer_state;
+};
+
+struct sgp_device {
+	const struct iio_chan_spec *channels;
+	int num_channels;
+};
+
+static const struct sgp_version supported_versions_sgp30[] = {
+	{
+		.major = 1,
+		.minor = 0,
+	},
+};
+
+static const struct sgp_version supported_versions_sgpc3[] = {
+	{
+		.major = 0,
+		.minor = 4,
+	},
+};
+
+static const struct iio_chan_spec sgp30_channels[] = {
+	{
+		.type = IIO_CONCENTRATION,
+		.channel2 = IIO_MOD_VOC,
+		.modified = 1,
+		.info_mask_separate = BIT(IIO_CHAN_INFO_PROCESSED),
+		.address = SGP30_IAQ_TVOC_IDX,
+	},
+	{
+		.type = IIO_CONCENTRATION,
+		.channel2 = IIO_MOD_CO2,
+		.modified = 1,
+		.info_mask_separate = BIT(IIO_CHAN_INFO_PROCESSED),
+		.address = SGP30_IAQ_CO2EQ_IDX,
+	},
+	{
+		.type = IIO_CONCENTRATION,
+		.channel2 = IIO_MOD_ETHANOL,
+		.modified = 1,
+		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
+		.address = SGP30_SIG_ETOH_IDX,
+	},
+	{
+		.type = IIO_CONCENTRATION,
+		.channel2 = IIO_MOD_H2,
+		.modified = 1,
+		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
+		.address = SGP30_SIG_H2_IDX,
+	},
+};
+
+static const struct iio_chan_spec sgpc3_channels[] = {
+	{
+		.type = IIO_CONCENTRATION,
+		.channel2 = IIO_MOD_VOC,
+		.modified = 1,
+		.info_mask_separate = BIT(IIO_CHAN_INFO_PROCESSED),
+		.address = SGPC3_IAQ_TVOC_IDX,
+	},
+	{
+		.type = IIO_CONCENTRATION,
+		.channel2 = IIO_MOD_ETHANOL,
+		.modified = 1,
+		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
+		.address = SGPC3_SIG_ETOH_IDX,
+	},
+};
+
+static const struct sgp_device sgp_devices[] = {
+	[SGP30] = {
+		.channels = sgp30_channels,
+		.num_channels = ARRAY_SIZE(sgp30_channels),
+	},
+	[SGPC3] = {
+		.channels = sgpc3_channels,
+		.num_channels = ARRAY_SIZE(sgpc3_channels),
+	},
+};
+
+/**
+ * sgp_verify_buffer() - verify the checksums of the data buffer words
+ *
+ * @data:       SGP data
+ * @buf:        Raw data buffer
+ * @word_count: Num data words stored in the buffer, excluding CRC bytes
+ *
+ * Return:      0 on success, negative error otherwise.
+ */
+static int sgp_verify_buffer(const struct sgp_data *data,
+			     union sgp_reading *buf, size_t word_count)
+{
+	size_t size = word_count * (SGP_WORD_LEN + SGP_CRC8_LEN);
+	int i;
+	u8 crc;
+	u8 *data_buf = &buf->start;
+
+	for (i = 0; i < size; i += SGP_WORD_LEN + SGP_CRC8_LEN) {
+		crc = crc8(sgp_crc8_table, &data_buf[i], SGP_WORD_LEN,
+			   SGP_CRC8_INIT);
+		if (crc != data_buf[i + SGP_WORD_LEN]) {
+			dev_err(&data->client->dev, "CRC error\n");
+			return -EIO;
+		}
+	}
+
+	return 0;
+}
+
+/**
+ * sgp_read_cmd() - reads data from sensor after issuing a command
+ * The caller must hold data->data_lock for the duration of the call.
+ * @data:        SGP data
+ * @cmd:         SGP Command to issue
+ * @buf:         Raw data buffer to use
+ * @word_count:  Num words to read, excluding CRC bytes
+ *
+ * Return:       0 on success, negative error otherwise.
+ */
+static int sgp_read_cmd(struct sgp_data *data, enum sgp_cmd cmd,
+			union sgp_reading *buf, size_t word_count,
+			unsigned long duration_us)
+{
+	int ret;
+	struct i2c_client *client = data->client;
+	size_t size = word_count * (SGP_WORD_LEN + SGP_CRC8_LEN);
+	u8 *data_buf;
+
+	ret = i2c_master_send(client, (const char *)&cmd, SGP_CMD_LEN);
+	if (ret != SGP_CMD_LEN)
+		return -EIO;
+	usleep_range(duration_us, duration_us + 1000);
+
+	if (word_count == 0)
+		return 0;
+
+	data_buf = &buf->start;
+	ret = i2c_master_recv(client, data_buf, size);
+	if (ret < 0)
+		return ret;
+	if (ret != size)
+		return -EIO;
+
+	return sgp_verify_buffer(data, buf, word_count);
+}
+
+/**
+ * sgp_measure_iaq() - measure and retrieve IAQ values from sensor
+ * The caller must hold data->data_lock for the duration of the call.
+ * @data:       SGP data
+ *
+ * Return:      0 on success, -EBUSY on default values, negative error
+ *              otherwise.
+ */
+
+static int sgp_measure_iaq(struct sgp_data *data)
+{
+	int ret;
+	/* data contains default values */
+	bool default_vals = !time_after(jiffies, data->iaq_init_start_jiffies +
+						 data->iaq_defval_skip_jiffies);
+
+	ret = sgp_read_cmd(data, data->measure_iaq_cmd, &data->iaq_buffer,
+			   SGP_MEASUREMENT_LEN, SGP_MEASUREMENT_DURATION_US);
+	if (ret < 0)
+		return ret;
+
+	data->iaq_buffer_state = IAQ_BUFFER_DEFAULT_VALS;
+
+	if (default_vals)
+		return -EBUSY;
+
+	data->iaq_buffer_state = IAQ_BUFFER_VALID;
+
+	return 0;
+}
+
+static void sgp_iaq_thread_sleep_until(const struct sgp_data *data,
+				       unsigned long sleep_jiffies)
+{
+	const long IAQ_POLL = 50000;
+
+	while (!time_after(jiffies, sleep_jiffies)) {
+		usleep_range(IAQ_POLL, IAQ_POLL + 10000);
+		if (kthread_should_stop() || data->iaq_init_start_jiffies == 0)
+			return;
+	}
+}
+
+static int sgp_iaq_threadfn(void *p)
+{
+	struct sgp_data *data = (struct sgp_data *)p;
+	unsigned long next_update_jiffies;
+	int ret;
+
+	while (!kthread_should_stop()) {
+		mutex_lock(&data->data_lock);
+		if (data->iaq_init_start_jiffies == 0) {
+			ret = sgp_read_cmd(data, data->iaq_init_cmd, NULL, 0,
+					   SGP_CMD_DURATION_US);
+			if (ret < 0)
+				goto unlock_sleep_continue;
+			data->iaq_init_start_jiffies = jiffies;
+		}
+
+		ret = sgp_measure_iaq(data);
+		if (ret && ret != -EBUSY) {
+			dev_warn(&data->client->dev,
+				 "IAQ measurement error [%d]\n", ret);
+		}
+unlock_sleep_continue:
+		next_update_jiffies = jiffies + data->measure_interval_jiffies;
+		mutex_unlock(&data->data_lock);
+		sgp_iaq_thread_sleep_until(data, next_update_jiffies);
+	}
+
+	return 0;
+}
+
+static int sgp_read_raw(struct iio_dev *indio_dev,
+			struct iio_chan_spec const *chan, int *val,
+			int *val2, long mask)
+{
+	struct sgp_data *data = iio_priv(indio_dev);
+	struct sgp_crc_word *words;
+	int ret;
+
+	switch (mask) {
+	case IIO_CHAN_INFO_PROCESSED:
+		mutex_lock(&data->data_lock);
+		if (data->iaq_buffer_state != IAQ_BUFFER_VALID) {
+			mutex_unlock(&data->data_lock);
+			return -EBUSY;
+		}
+		words = data->iaq_buffer.raw_words;
+		switch (chan->address) {
+		case SGP30_IAQ_TVOC_IDX:
+		case SGPC3_IAQ_TVOC_IDX:
+			*val = 0;
+			*val2 = be16_to_cpu(words[1].value);
+			ret = IIO_VAL_INT_PLUS_NANO;
+			break;
+		case SGP30_IAQ_CO2EQ_IDX:
+			*val = 0;
+			*val2 = be16_to_cpu(words[0].value);
+			ret = IIO_VAL_INT_PLUS_MICRO;
+			break;
+		default:
+			ret = -EINVAL;
+			break;
+		}
+		mutex_unlock(&data->data_lock);
+		break;
+	case IIO_CHAN_INFO_RAW:
+		mutex_lock(&data->data_lock);
+		if (chan->address == SGPC3_SIG_ETOH_IDX) {
+			if (data->iaq_buffer_state == IAQ_BUFFER_EMPTY)
+				ret = -EBUSY;
+			else
+				ret = 0;
+			words = data->iaq_buffer.raw_words;
+		} else {
+			ret = sgp_read_cmd(data, data->measure_gas_signals_cmd,
+					   &data->buffer, SGP_MEASUREMENT_LEN,
+					   SGP_MEASUREMENT_DURATION_US);
+			words = data->buffer.raw_words;
+		}
+		if (ret) {
+			mutex_unlock(&data->data_lock);
+			return ret;
+		}
+
+		switch (chan->address) {
+		case SGP30_SIG_ETOH_IDX:
+			*val = be16_to_cpu(words[1].value);
+			ret = IIO_VAL_INT;
+			break;
+		case SGPC3_SIG_ETOH_IDX:
+		case SGP30_SIG_H2_IDX:
+			*val = be16_to_cpu(words[0].value);
+			ret = IIO_VAL_INT;
+			break;
+		default:
+			ret = -EINVAL;
+			break;
+		}
+		mutex_unlock(&data->data_lock);
+		break;
+	default:
+		return -EINVAL;
+	}
+
+	return ret;
+}
+
+static int sgp_check_compat(struct sgp_data *data,
+			    unsigned int product_id)
+{
+	const struct sgp_version *supported_versions;
+	u16 ix, num_fs;
+	u16 product, generation, major, minor;
+
+	/* driver does not match product */
+	generation = SGP_VERS_GEN(data);
+	if (generation != 0) {
+		dev_err(&data->client->dev,
+			"incompatible product generation %d != 0", generation);
+		return -ENODEV;
+	}
+
+	product = SGP_VERS_PRODUCT(data);
+	if (product != product_id) {
+		dev_err(&data->client->dev,
+			"sensor reports a different product: 0x%04hx\n",
+			product);
+		return -ENODEV;
+	}
+
+	if (SGP_VERS_RESERVED(data))
+		dev_warn(&data->client->dev, "reserved bit is set\n");
+
+	/* engineering samples are not supported: no interface guarantees */
+	if (SGP_VERS_ENG_BIT(data))
+		return -ENODEV;
+
+	switch (product) {
+	case SGP30:
+		supported_versions = supported_versions_sgp30;
+		num_fs = ARRAY_SIZE(supported_versions_sgp30);
+		break;
+	case SGPC3:
+		supported_versions = supported_versions_sgpc3;
+		num_fs = ARRAY_SIZE(supported_versions_sgpc3);
+		break;
+	default:
+		return -ENODEV;
+	}
+
+	major = SGP_VERS_MAJOR(data);
+	minor = SGP_VERS_MINOR(data);
+	for (ix = 0; ix < num_fs; ix++) {
+		if (major == supported_versions[ix].major &&
+		    minor >= supported_versions[ix].minor)
+			return 0;
+	}
+	dev_err(&data->client->dev, "unsupported sgp version: %d.%d\n",
+		major, minor);
+
+	return -ENODEV;
+}
+
+static void sgp_init(struct sgp_data *data)
+{
+	data->iaq_init_cmd = SGP_CMD_IAQ_INIT;
+	data->iaq_init_start_jiffies = 0;
+	data->iaq_buffer_state = IAQ_BUFFER_EMPTY;
+	switch (SGP_VERS_PRODUCT(data)) {
+	case SGP30:
+		data->measure_interval_jiffies = SGP30_MEASURE_INTERVAL_HZ * HZ;
+		data->measure_iaq_cmd = SGP_CMD_IAQ_MEASURE;
+		data->measure_gas_signals_cmd = SGP30_CMD_MEASURE_SIGNAL;
+		data->product_id = SGP30;
+		data->iaq_defval_skip_jiffies = 15 * HZ;
+		break;
+	case SGPC3:
+		data->measure_interval_jiffies = SGPC3_MEASURE_INTERVAL_HZ * HZ;
+		data->measure_iaq_cmd = SGPC3_CMD_MEASURE_RAW;
+		data->measure_gas_signals_cmd = SGPC3_CMD_MEASURE_RAW;
+		data->product_id = SGPC3;
+		data->iaq_defval_skip_jiffies =
+			43 * data->measure_interval_jiffies;
+		break;
+	};
+}
+
+static const struct iio_info sgp_info = {
+	.read_raw	= sgp_read_raw,
+};
+
+static const struct of_device_id sgp_dt_ids[] = {
+	{ .compatible = "sensirion,sgp30", .data = (void *)SGP30 },
+	{ .compatible = "sensirion,sgpc3", .data = (void *)SGPC3 },
+	{ }
+};
+
+static int sgp_probe(struct i2c_client *client,
+		     const struct i2c_device_id *id)
+{
+	struct iio_dev *indio_dev;
+	struct sgp_data *data;
+	const struct of_device_id *of_id;
+	unsigned long product_id;
+	int ret;
+
+	indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*data));
+	if (!indio_dev)
+		return -ENOMEM;
+
+	of_id = of_match_device(sgp_dt_ids, &client->dev);
+	if (of_id)
+		product_id = (unsigned long)of_id->data;
+	else
+		product_id = id->driver_data;
+
+	data = iio_priv(indio_dev);
+	i2c_set_clientdata(client, indio_dev);
+	data->client = client;
+	crc8_populate_msb(sgp_crc8_table, SGP_CRC8_POLYNOMIAL);
+	mutex_init(&data->data_lock);
+
+	/* get feature set version and write it to client data */
+	ret = sgp_read_cmd(data, SGP_CMD_GET_FEATURE_SET, &data->buffer, 1,
+			   SGP_CMD_DURATION_US);
+	if (ret < 0)
+		return ret;
+
+	data->feature_set = be16_to_cpu(data->buffer.raw_words[0].value);
+
+	ret = sgp_check_compat(data, product_id);
+	if (ret)
+		return ret;
+
+	indio_dev->dev.parent = &client->dev;
+	indio_dev->info = &sgp_info;
+	indio_dev->name = id->name;
+	indio_dev->modes = INDIO_DIRECT_MODE;
+	indio_dev->channels = sgp_devices[product_id].channels;
+	indio_dev->num_channels = sgp_devices[product_id].num_channels;
+
+	sgp_init(data);
+
+	ret = devm_iio_device_register(&client->dev, indio_dev);
+	if (ret) {
+		dev_err(&client->dev, "failed to register iio device\n");
+		return ret;
+	}
+
+	data->iaq_thread = kthread_run(sgp_iaq_threadfn, data,
+				       "%s-iaq", data->client->name);
+
+	return 0;
+}
+
+static int sgp_remove(struct i2c_client *client)
+{
+	struct iio_dev *indio_dev = i2c_get_clientdata(client);
+	struct sgp_data *data = iio_priv(indio_dev);
+
+	if (data->iaq_thread)
+		kthread_stop(data->iaq_thread);
+
+	return 0;
+}
+
+static const struct i2c_device_id sgp_id[] = {
+	{ "sgp30", SGP30 },
+	{ "sgpc3", SGPC3 },
+	{ }
+};
+
+MODULE_DEVICE_TABLE(i2c, sgp_id);
+MODULE_DEVICE_TABLE(of, sgp_dt_ids);
+
+static struct i2c_driver sgp_driver = {
+	.driver = {
+		.name = "sgp30",
+		.of_match_table = of_match_ptr(sgp_dt_ids),
+	},
+	.probe = sgp_probe,
+	.remove = sgp_remove,
+	.id_table = sgp_id,
+};
+module_i2c_driver(sgp_driver);
+
+MODULE_AUTHOR("Andreas Brauchli <andreas.brauchli@sensirion.com>");
+MODULE_AUTHOR("Pascal Sachs <pascal.sachs@sensirion.com>");
+MODULE_DESCRIPTION("Sensirion SGP gas sensors");
+MODULE_LICENSE("GPL v2");