iio: humidity: Add support for ENS210

Add support for ENS210/ENS210A/ENS211/ENS212/ENS213A/ENS215.

The ENS21x is a family of temperature and relative humidity sensors with
accuracies tailored to the needs of specific applications.

Signed-off-by: Joshua Felmeden <[e-mail]>
Link: https://patch.msgid.link/[e-mail]
Signed-off-by: Jonathan Cameron <[e-mail]>

drivers/iio/humidity/Kconfig

···
 	  Other sensors should work as well as long as they speak the
 	  same protocol.
 
+config ENS210
+	tristate "ENS210 temperature and humidity sensor"
+	depends on I2C
+	select CRC7
+	help
+	  Say yes here to get support for the ScioSense ENS210 family of
+	  humidity and temperature sensors.
+
+	  This driver can also be built as a module. If so, the module will be
+	  called ens210.
+
 config HDC100X
 	tristate "TI HDC100x relative humidity and temperature sensor"
 	depends on I2C

drivers/iio/humidity/Makefile

···
 
 obj-$(CONFIG_AM2315) += am2315.o
 obj-$(CONFIG_DHT11) += dht11.o
+obj-$(CONFIG_ENS210) += ens210.o
 obj-$(CONFIG_HDC100X) += hdc100x.o
 obj-$(CONFIG_HDC2010) += hdc2010.o
 obj-$(CONFIG_HDC3020) += hdc3020.o

drivers/iio/humidity/ens210.c

···
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * ens210.c - Support for ScioSense ens210 temperature & humidity sensor family
+ *
+ * (7-bit I2C slave address 0x43 ENS210)
+ * (7-bit I2C slave address 0x43 ENS210A)
+ * (7-bit I2C slave address 0x44 ENS211)
+ * (7-bit I2C slave address 0x45 ENS212)
+ * (7-bit I2C slave address 0x46 ENS213A)
+ * (7-bit I2C slave address 0x47 ENS215)
+ *
+ * Datasheet:
+ *  https://www.sciosense.com/wp-content/uploads/2024/04/ENS21x-Datasheet.pdf
+ *  https://www.sciosense.com/wp-content/uploads/2023/12/ENS210-Datasheet.pdf
+ */
+
+#include <linux/crc7.h>
+#include <linux/delay.h>
+#include <linux/i2c.h>
+#include <linux/iio/iio.h>
+#include <linux/mod_devicetable.h>
+#include <linux/module.h>
+#include <linux/types.h>
+
+#include <asm/unaligned.h>
+
+/* register definitions */
+#define ENS210_REG_PART_ID		0x00
+#define ENS210_REG_DIE_REV		0x02
+#define ENS210_REG_UID			0x04
+#define ENS210_REG_SYS_CTRL		0x10
+#define ENS210_REG_SYS_STAT		0x11
+#define ENS210_REG_SENS_RUN		0x21
+#define ENS210_REG_SENS_START		0x22
+#define ENS210_REG_SENS_STOP		0x23
+#define ENS210_REG_SENS_STAT		0x24
+#define ENS210_REG_T_VAL		0x30
+#define ENS210_REG_H_VAL		0x33
+
+/* value definitions */
+#define ENS210_SENS_START_T_START		BIT(0)
+#define ENS210_SENS_START_H_START		BIT(1)
+
+#define ENS210_SENS_STAT_T_ACTIVE		BIT(0)
+#define ENS210_SENS_STAT_H_ACTIVE		BIT(1)
+
+#define ENS210_SYS_CTRL_LOW_POWER_ENABLE	BIT(0)
+#define ENS210_SYS_CTRL_SYS_RESET		BIT(7)
+
+#define ENS210_SYS_STAT_SYS_ACTIVE		BIT(0)
+
+enum ens210_partnumber {
+	ENS210	= 0x0210,
+	ENS210A	= 0xa210,
+	ENS211	= 0x0211,
+	ENS212	= 0x0212,
+	ENS213A	= 0xa213,
+	ENS215	= 0x0215,
+};
+
+/**
+ * struct ens210_chip_info - Humidity/Temperature chip specific information
+ * @name:		name of device
+ * @part_id:		chip identifier
+ * @conv_time_msec:	time for conversion calculation in m/s
+ */
+struct ens210_chip_info {
+	const char *name;
+	enum ens210_partnumber part_id;
+	unsigned int conv_time_msec;
+};
+
+/**
+ * struct ens210_data - Humidity/Temperature sensor device structure
+ * @client:	i2c client
+ * @chip_info:	chip specific information
+ * @lock:	lock protecting against simultaneous callers of get_measurement
+ *		since multiple uninterrupted transactions are required
+ */
+struct ens210_data {
+	struct i2c_client *client;
+	const struct ens210_chip_info *chip_info;
+	struct mutex lock;
+};
+
+/* calculate 17-bit crc7 */
+static u8 ens210_crc7(u32 val)
+{
+	unsigned int val_be = (val & 0x1ffff) >> 0x8;
+
+	return crc7_be(0xde, (u8 *)&val_be, 3) >> 1;
+}
+
+static int ens210_get_measurement(struct iio_dev *indio_dev, bool temp, int *val)
+{
+	struct ens210_data *data = iio_priv(indio_dev);
+	struct device *dev = &data->client->dev;
+	u32 regval;
+	u8 regval_le[3];
+	int ret;
+
+	/* assert read */
+	ret = i2c_smbus_write_byte_data(data->client, ENS210_REG_SENS_START,
+					temp ? ENS210_SENS_START_T_START :
+					       ENS210_SENS_START_H_START);
+	if (ret)
+		return ret;
+
+	/* wait for conversion to be ready */
+	msleep(data->chip_info->conv_time_msec);
+
+	ret = i2c_smbus_read_byte_data(data->client, ENS210_REG_SENS_STAT);
+	if (ret < 0)
+		return ret;
+
+	/* perform read */
+	ret = i2c_smbus_read_i2c_block_data(
+		data->client, temp ? ENS210_REG_T_VAL : ENS210_REG_H_VAL, 3,
+		regval_le);
+	if (ret < 0) {
+		dev_err(dev, "failed to read register");
+		return -EIO;
+	}
+	if (ret != 3) {
+		dev_err(dev, "expected 3 bytes, received %d\n", ret);
+		return -EIO;
+	}
+
+	regval = get_unaligned_le24(regval_le);
+	if (ens210_crc7(regval) != ((regval >> 17) & 0x7f)) {
+		dev_err(dev, "invalid crc\n");
+		return -EIO;
+	}
+
+	if (!((regval >> 16) & 0x1)) {
+		dev_err(dev, "data is not valid");
+		return -EIO;
+	}
+
+	*val = regval & GENMASK(15, 0);
+	return IIO_VAL_INT;
+}
+
+static int ens210_read_raw(struct iio_dev *indio_dev,
+			   struct iio_chan_spec const *channel, int *val,
+			   int *val2, long mask)
+{
+	struct ens210_data *data = iio_priv(indio_dev);
+	int ret;
+
+	switch (mask) {
+	case IIO_CHAN_INFO_RAW:
+		scoped_guard(mutex, &data->lock) {
+			ret = ens210_get_measurement(
+				indio_dev, channel->type == IIO_TEMP, val);
+			if (ret)
+				return ret;
+			return IIO_VAL_INT;
+		}
+		return -EINVAL; /* compiler warning workaround */
+	case IIO_CHAN_INFO_SCALE:
+		if (channel->type == IIO_TEMP) {
+			*val = 15;
+			*val2 = 625000;
+		} else {
+			*val = 1;
+			*val2 = 953125;
+		}
+		return IIO_VAL_INT_PLUS_MICRO;
+	case IIO_CHAN_INFO_OFFSET:
+		*val = -17481;
+		*val2 = 600000;
+		return IIO_VAL_INT_PLUS_MICRO;
+	default:
+		return -EINVAL;
+	}
+}
+
+static const struct iio_chan_spec ens210_channels[] = {
+	{
+		.type = IIO_TEMP,
+		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
+				      BIT(IIO_CHAN_INFO_SCALE) |
+				      BIT(IIO_CHAN_INFO_OFFSET),
+	},
+	{
+		.type = IIO_HUMIDITYRELATIVE,
+		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
+				      BIT(IIO_CHAN_INFO_SCALE),
+	}
+};
+
+static const struct iio_info ens210_info = {
+	.read_raw = ens210_read_raw,
+};
+
+static int ens210_probe(struct i2c_client *client)
+{
+	struct ens210_data *data;
+	struct iio_dev *indio_dev;
+	uint16_t part_id;
+	int ret;
+
+	if (!i2c_check_functionality(client->adapter,
+				     I2C_FUNC_SMBUS_WRITE_BYTE_DATA |
+				     I2C_FUNC_SMBUS_WRITE_BYTE |
+				     I2C_FUNC_SMBUS_READ_I2C_BLOCK)) {
+		return dev_err_probe(&client->dev, -EOPNOTSUPP,
+			"adapter does not support some i2c transactions\n");
+	}
+
+	indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*data));
+	if (!indio_dev)
+		return -ENOMEM;
+
+	data = iio_priv(indio_dev);
+	data->client = client;
+	mutex_init(&data->lock);
+	data->chip_info = i2c_get_match_data(client);
+
+	ret = devm_regulator_get_enable(&client->dev, "vdd");
+	if (ret)
+		return ret;
+
+	/* reset device */
+	ret = i2c_smbus_write_byte_data(client, ENS210_REG_SYS_CTRL,
+					ENS210_SYS_CTRL_SYS_RESET);
+	if (ret)
+		return ret;
+
+	/* wait for device to become active */
+	usleep_range(4000, 5000);
+
+	/* disable low power mode */
+	ret = i2c_smbus_write_byte_data(client, ENS210_REG_SYS_CTRL, 0x00);
+	if (ret)
+		return ret;
+
+	/* wait for device to finish */
+	usleep_range(4000, 5000);
+
+	/* get part_id */
+	ret = i2c_smbus_read_word_data(client, ENS210_REG_PART_ID);
+	if (ret < 0)
+		return ret;
+	part_id = ret;
+
+	if (part_id != data->chip_info->part_id) {
+		dev_info(&client->dev,
+			 "Part ID does not match (0x%04x != 0x%04x)\n", part_id,
+			 data->chip_info->part_id);
+	}
+
+	/* reenable low power */
+	ret = i2c_smbus_write_byte_data(client, ENS210_REG_SYS_CTRL,
+					ENS210_SYS_CTRL_LOW_POWER_ENABLE);
+	if (ret)
+		return ret;
+
+	indio_dev->name = data->chip_info->name;
+	indio_dev->modes = INDIO_DIRECT_MODE;
+	indio_dev->channels = ens210_channels;
+	indio_dev->num_channels = ARRAY_SIZE(ens210_channels);
+	indio_dev->info = &ens210_info;
+
+	return devm_iio_device_register(&client->dev, indio_dev);
+}
+
+static const struct ens210_chip_info ens210_chip_info_data = {
+	.name = "ens210",
+	.part_id = ENS210,
+	.conv_time_msec = 130,
+};
+
+static const struct ens210_chip_info ens210a_chip_info_data = {
+	.name = "ens210a",
+	.part_id = ENS210A,
+	.conv_time_msec = 130,
+};
+
+static const struct ens210_chip_info ens211_chip_info_data = {
+	.name = "ens211",
+	.part_id = ENS211,
+	.conv_time_msec = 32,
+};
+
+static const struct ens210_chip_info ens212_chip_info_data = {
+	.name = "ens212",
+	.part_id = ENS212,
+	.conv_time_msec = 32,
+};
+
+static const struct ens210_chip_info ens213a_chip_info_data = {
+	.name = "ens213a",
+	.part_id = ENS213A,
+	.conv_time_msec = 130,
+};
+
+static const struct ens210_chip_info ens215_chip_info_data = {
+	.name = "ens215",
+	.part_id = ENS215,
+	.conv_time_msec = 130,
+};
+
+static const struct of_device_id ens210_of_match[] = {
+	{ .compatible = "sciosense,ens210", .data = &ens210_chip_info_data },
+	{ .compatible = "sciosense,ens210a", .data = &ens210a_chip_info_data },
+	{ .compatible = "sciosense,ens211", .data = &ens211_chip_info_data },
+	{ .compatible = "sciosense,ens212", .data = &ens212_chip_info_data },
+	{ .compatible = "sciosense,ens213a", .data = &ens213a_chip_info_data },
+	{ .compatible = "sciosense,ens215", .data = &ens215_chip_info_data },
+	{ }
+};
+MODULE_DEVICE_TABLE(of, ens210_of_match);
+
+static const struct i2c_device_id ens210_id_table[] = {
+	{ "ens210", (kernel_ulong_t)&ens210_chip_info_data },
+	{ "ens210a", (kernel_ulong_t)&ens210a_chip_info_data },
+	{ "ens211", (kernel_ulong_t)&ens211_chip_info_data },
+	{ "ens212", (kernel_ulong_t)&ens212_chip_info_data },
+	{ "ens213a", (kernel_ulong_t)&ens213a_chip_info_data },
+	{ "ens215", (kernel_ulong_t)&ens215_chip_info_data },
+	{ }
+};
+MODULE_DEVICE_TABLE(i2c, ens210_id_table);
+
+static struct i2c_driver ens210_driver = {
+	.probe = ens210_probe,
+	.id_table = ens210_id_table,
+	.driver = {
+		.name = "ens210",
+		.of_match_table = ens210_of_match,
+	},
+};
+module_i2c_driver(ens210_driver);
+
+MODULE_DESCRIPTION("ScioSense ENS210 temperature and humidity sensor driver");
+MODULE_AUTHOR("Joshua Felmeden <[e-mail]>");
+MODULE_LICENSE("GPL");