// SPDX-License-Identifier: GPL-2.0
/*
 * Senseair Sunrise 006-0-0007 CO2 sensor driver.
 *
 * Copyright (C) 2021 Jacopo Mondi
 *
 * List of features not yet supported by the driver:
 * - controllable EN pin
 * - single-shot operations using the nDRY pin.
 * - ABC/target calibration
 */

#include <linux/bitops.h>
#include <linux/i2c.h>
#include <linux/kernel.h>
#include <linux/mod_devicetable.h>
#include <linux/module.h>
#include <linux/mutex.h>
#include <linux/regmap.h>
#include <linux/time64.h>

#include <linux/iio/iio.h>

#define DRIVER_NAME "sunrise_co2"

#define SUNRISE_ERROR_STATUS_REG		0x00
#define SUNRISE_CO2_FILTERED_COMP_REG		0x06
#define SUNRISE_CHIP_TEMPERATURE_REG		0x08
#define SUNRISE_CALIBRATION_STATUS_REG		0x81
#define SUNRISE_CALIBRATION_COMMAND_REG		0x82
#define SUNRISE_CALIBRATION_FACTORY_CMD		0x7c02
#define SUNRISE_CALIBRATION_BACKGROUND_CMD	0x7c06
/*
 * The calibration timeout is not characterized in the datasheet.
 * Use 30 seconds as a reasonable upper limit.
 */
#define SUNRISE_CALIBRATION_TIMEOUT_US		(30 * USEC_PER_SEC)

struct sunrise_dev {
	struct i2c_client *client;
	struct regmap *regmap;
	/* Protects access to IIO attributes. */
	struct mutex lock;
	bool ignore_nak;
};

/* Custom regmap read/write operations: perform unlocked access to the i2c bus. */

static int sunrise_regmap_read(void *context, const void *reg_buf,
			       size_t reg_size, void *val_buf, size_t val_size)
{
	struct i2c_client *client = context;
	struct sunrise_dev *sunrise = i2c_get_clientdata(client);
	union i2c_smbus_data data;
	int ret;

	if (reg_size != 1 || !val_size)
		return -EINVAL;

	memset(&data, 0, sizeof(data));
	data.block[0] = val_size;

	/*
	 * Wake up sensor by sending sensor address: START, sensor address,
	 * STOP. Sensor will not ACK this byte.
	 *
	 * The chip enters a low power state after 15ms without
	 * communications or after a complete read/write sequence.
	 */
	__i2c_smbus_xfer(client->adapter, client->addr,
			 sunrise->ignore_nak ? I2C_M_IGNORE_NAK : 0,
			 I2C_SMBUS_WRITE, 0, I2C_SMBUS_BYTE_DATA, &data);

	usleep_range(500, 1500);

	ret = __i2c_smbus_xfer(client->adapter, client->addr, client->flags,
			       I2C_SMBUS_READ, ((u8 *)reg_buf)[0],
			       I2C_SMBUS_I2C_BLOCK_DATA, &data);
	if (ret < 0)
		return ret;

	memcpy(val_buf, &data.block[1], data.block[0]);

	return 0;
}

static int sunrise_regmap_write(void *context, const void *val_buf, size_t count)
{
	struct i2c_client *client = context;
	struct sunrise_dev *sunrise = i2c_get_clientdata(client);
	union i2c_smbus_data data;

	/* Discard reg address from values count. */
	if (!count)
		return -EINVAL;
	count--;

	memset(&data, 0, sizeof(data));
	data.block[0] = count;
	memcpy(&data.block[1], (u8 *)val_buf + 1, count);

	__i2c_smbus_xfer(client->adapter, client->addr,
			 sunrise->ignore_nak ? I2C_M_IGNORE_NAK : 0,
			 I2C_SMBUS_WRITE, 0, I2C_SMBUS_BYTE_DATA, &data);

	usleep_range(500, 1500);

	return __i2c_smbus_xfer(client->adapter, client->addr, client->flags,
				I2C_SMBUS_WRITE, ((u8 *)val_buf)[0],
				I2C_SMBUS_I2C_BLOCK_DATA, &data);
}

/*
 * Sunrise i2c read/write operations: lock the i2c segment to avoid losing the
 * wake up session. Use custom regmap operations that perform unlocked access to
 * the i2c bus.
 */
static int sunrise_read_byte(struct sunrise_dev *sunrise, u8 reg)
{
	const struct i2c_client *client = sunrise->client;
	const struct device *dev = &client->dev;
	unsigned int val;
	int ret;

	i2c_lock_bus(client->adapter, I2C_LOCK_SEGMENT);
	ret = regmap_read(sunrise->regmap, reg, &val);
	i2c_unlock_bus(client->adapter, I2C_LOCK_SEGMENT);
	if (ret) {
		dev_err(dev, "Read byte failed: reg 0x%02x (%d)\n", reg, ret);
		return ret;
	}

	return val;
}

static int sunrise_read_word(struct sunrise_dev *sunrise, u8 reg, u16 *val)
{
	const struct i2c_client *client = sunrise->client;
	const struct device *dev = &client->dev;
	__be16 be_val;
	int ret;

	i2c_lock_bus(client->adapter, I2C_LOCK_SEGMENT);
	ret = regmap_bulk_read(sunrise->regmap, reg, &be_val, sizeof(be_val));
	i2c_unlock_bus(client->adapter, I2C_LOCK_SEGMENT);
	if (ret) {
		dev_err(dev, "Read word failed: reg 0x%02x (%d)\n", reg, ret);
		return ret;
	}

	*val = be16_to_cpu(be_val);

	return 0;
}

static int sunrise_write_byte(struct sunrise_dev *sunrise, u8 reg, u8 val)
{
	const struct i2c_client *client = sunrise->client;
	const struct device *dev = &client->dev;
	int ret;

	i2c_lock_bus(client->adapter, I2C_LOCK_SEGMENT);
	ret = regmap_write(sunrise->regmap, reg, val);
	i2c_unlock_bus(client->adapter, I2C_LOCK_SEGMENT);
	if (ret)
		dev_err(dev, "Write byte failed: reg 0x%02x (%d)\n", reg, ret);

	return ret;
}

static int sunrise_write_word(struct sunrise_dev *sunrise, u8 reg, u16 data)
{
	const struct i2c_client *client = sunrise->client;
	const struct device *dev = &client->dev;
	__be16 be_data = cpu_to_be16(data);
	int ret;

	i2c_lock_bus(client->adapter, I2C_LOCK_SEGMENT);
	ret = regmap_bulk_write(sunrise->regmap, reg, &be_data, sizeof(be_data));
	i2c_unlock_bus(client->adapter, I2C_LOCK_SEGMENT);
	if (ret)
		dev_err(dev, "Write word failed: reg 0x%02x (%d)\n", reg, ret);

	return ret;
}

/* Trigger a calibration cycle. */

enum {
	SUNRISE_CALIBRATION_FACTORY,
	SUNRISE_CALIBRATION_BACKGROUND,
};

static const struct sunrise_calib_data {
	u16 cmd;
	u8 bit;
	const char * const name;
} calib_data[] = {
	[SUNRISE_CALIBRATION_FACTORY] = {
		SUNRISE_CALIBRATION_FACTORY_CMD,
		BIT(2),
		"factory_calibration",
	},
	[SUNRISE_CALIBRATION_BACKGROUND] = {
		SUNRISE_CALIBRATION_BACKGROUND_CMD,
		BIT(5),
		"background_calibration",
	},
};

static int sunrise_calibrate(struct sunrise_dev *sunrise,
			     const struct sunrise_calib_data *data)
{
	unsigned int status;
	int ret;

	/* Reset the calibration status reg. */
	ret = sunrise_write_byte(sunrise, SUNRISE_CALIBRATION_STATUS_REG, 0x00);
	if (ret)
		return ret;

	/* Write a calibration command and poll the calibration status bit. */
	ret = sunrise_write_word(sunrise, SUNRISE_CALIBRATION_COMMAND_REG, data->cmd);
	if (ret)
		return ret;

	dev_dbg(&sunrise->client->dev, "%s in progress\n", data->name);

	/*
	 * Calibration takes several seconds, so the sleep time between reads
	 * can be pretty relaxed.
	 */
	return read_poll_timeout(sunrise_read_byte, status, status & data->bit,
				 200000, SUNRISE_CALIBRATION_TIMEOUT_US, false,
				 sunrise, SUNRISE_CALIBRATION_STATUS_REG);
}

static ssize_t sunrise_cal_factory_write(struct iio_dev *iiodev,
					 uintptr_t private,
					 const struct iio_chan_spec *chan,
					 const char *buf, size_t len)
{
	struct sunrise_dev *sunrise = iio_priv(iiodev);
	bool enable;
	int ret;

	ret = kstrtobool(buf, &enable);
	if (ret)
		return ret;

	if (!enable)
		return len;

	mutex_lock(&sunrise->lock);
	ret = sunrise_calibrate(sunrise, &calib_data[SUNRISE_CALIBRATION_FACTORY]);
	mutex_unlock(&sunrise->lock);
	if (ret)
		return ret;

	return len;
}

static ssize_t sunrise_cal_background_write(struct iio_dev *iiodev,
					    uintptr_t private,
					    const struct iio_chan_spec *chan,
					    const char *buf, size_t len)
{
	struct sunrise_dev *sunrise = iio_priv(iiodev);
	bool enable;
	int ret;

	ret = kstrtobool(buf, &enable);
	if (ret)
		return ret;

	if (!enable)
		return len;

	mutex_lock(&sunrise->lock);
	ret = sunrise_calibrate(sunrise, &calib_data[SUNRISE_CALIBRATION_BACKGROUND]);
	mutex_unlock(&sunrise->lock);
	if (ret)
		return ret;

	return len;
}

 /* Enumerate and retrieve the chip error status. */
enum {
	SUNRISE_ERROR_FATAL,
	SUNRISE_ERROR_I2C,
	SUNRISE_ERROR_ALGORITHM,
	SUNRISE_ERROR_CALIBRATION,
	SUNRISE_ERROR_SELF_DIAGNOSTIC,
	SUNRISE_ERROR_OUT_OF_RANGE,
	SUNRISE_ERROR_MEMORY,
	SUNRISE_ERROR_NO_MEASUREMENT,
	SUNRISE_ERROR_LOW_VOLTAGE,
	SUNRISE_ERROR_MEASUREMENT_TIMEOUT,
};

static const char * const sunrise_error_statuses[] = {
	[SUNRISE_ERROR_FATAL] = "error_fatal",
	[SUNRISE_ERROR_I2C] = "error_i2c",
	[SUNRISE_ERROR_ALGORITHM] = "error_algorithm",
	[SUNRISE_ERROR_CALIBRATION] = "error_calibration",
	[SUNRISE_ERROR_SELF_DIAGNOSTIC] = "error_self_diagnostic",
	[SUNRISE_ERROR_OUT_OF_RANGE] = "error_out_of_range",
	[SUNRISE_ERROR_MEMORY] = "error_memory",
	[SUNRISE_ERROR_NO_MEASUREMENT] = "error_no_measurement",
	[SUNRISE_ERROR_LOW_VOLTAGE] = "error_low_voltage",
	[SUNRISE_ERROR_MEASUREMENT_TIMEOUT] = "error_measurement_timeout",
};

static const struct iio_enum sunrise_error_statuses_enum = {
	.items = sunrise_error_statuses,
	.num_items = ARRAY_SIZE(sunrise_error_statuses),
};

static ssize_t sunrise_error_status_read(struct iio_dev *iiodev,
					 uintptr_t private,
					 const struct iio_chan_spec *chan,
					 char *buf)
{
	struct sunrise_dev *sunrise = iio_priv(iiodev);
	unsigned long errors;
	ssize_t len = 0;
	u16 value;
	int ret;
	u8 i;

	mutex_lock(&sunrise->lock);
	ret = sunrise_read_word(sunrise, SUNRISE_ERROR_STATUS_REG, &value);
	if (ret) {
		mutex_unlock(&sunrise->lock);
		return ret;
	}

	errors = value;
	for_each_set_bit(i, &errors, ARRAY_SIZE(sunrise_error_statuses))
		len += sysfs_emit_at(buf, len, "%s ", sunrise_error_statuses[i]);

	if (len)
		buf[len - 1] = '\n';

	mutex_unlock(&sunrise->lock);

	return len;
}

static const struct iio_chan_spec_ext_info sunrise_concentration_ext_info[] = {
	/* Calibration triggers. */
	{
		.name = "calibration_factory",
		.write = sunrise_cal_factory_write,
		.shared = IIO_SEPARATE,
	},
	{
		.name = "calibration_background",
		.write = sunrise_cal_background_write,
		.shared = IIO_SEPARATE,
	},

	/* Error statuses. */
	{
		.name = "error_status",
		.read = sunrise_error_status_read,
		.shared = IIO_SHARED_BY_ALL,
	},
	{
		.name = "error_status_available",
		.shared = IIO_SHARED_BY_ALL,
		.read = iio_enum_available_read,
		.private = (uintptr_t)&sunrise_error_statuses_enum,
	},
	{}
};

static const struct iio_chan_spec sunrise_channels[] = {
	{
		.type = IIO_CONCENTRATION,
		.modified = 1,
		.channel2 = IIO_MOD_CO2,
		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
				      BIT(IIO_CHAN_INFO_SCALE),
		.ext_info = sunrise_concentration_ext_info,
	},
	{
		.type = IIO_TEMP,
		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
				      BIT(IIO_CHAN_INFO_SCALE),
	},
};

static int sunrise_read_raw(struct iio_dev *iio_dev,
			    const struct iio_chan_spec *chan,
			    int *val, int *val2, long mask)
{
	struct sunrise_dev *sunrise = iio_priv(iio_dev);
	u16 value;
	int ret;

	switch (mask) {
	case IIO_CHAN_INFO_RAW:
		switch (chan->type) {
		case IIO_CONCENTRATION:
			mutex_lock(&sunrise->lock);
			ret = sunrise_read_word(sunrise, SUNRISE_CO2_FILTERED_COMP_REG,
						&value);
			*val = value;
			mutex_unlock(&sunrise->lock);

			if (ret)
				return ret;

			return IIO_VAL_INT;

		case IIO_TEMP:
			mutex_lock(&sunrise->lock);
			ret = sunrise_read_word(sunrise, SUNRISE_CHIP_TEMPERATURE_REG,
						&value);
			*val = value;
			mutex_unlock(&sunrise->lock);

			if (ret)
				return ret;

			return IIO_VAL_INT;

		default:
			return -EINVAL;
		}

	case IIO_CHAN_INFO_SCALE:
		switch (chan->type) {
		case IIO_CONCENTRATION:
			/*
			 * 1 / 10^4 to comply with IIO scale for CO2
			 * (percentage). The chip CO2 reading range is [400 -
			 * 5000] ppm which corresponds to [0,004 - 0,5] %.
			 */
			*val = 1;
			*val2 = 10000;
			return IIO_VAL_FRACTIONAL;

		case IIO_TEMP:
			/* x10 to comply with IIO scale (millidegrees celsius). */
			*val = 10;
			return IIO_VAL_INT;

		default:
			return -EINVAL;
		}

	default:
		return -EINVAL;
	}
}

static const struct iio_info sunrise_info = {
	.read_raw = sunrise_read_raw,
};

static const struct regmap_bus sunrise_regmap_bus = {
	.read = sunrise_regmap_read,
	.write = sunrise_regmap_write,
};

static const struct regmap_config sunrise_regmap_config = {
	.reg_bits = 8,
	.val_bits = 8,
};

static int sunrise_probe(struct i2c_client *client)
{
	struct sunrise_dev *sunrise;
	struct iio_dev *iio_dev;

	if (!i2c_check_functionality(client->adapter, I2C_FUNC_SMBUS_BYTE_DATA |
						      I2C_FUNC_SMBUS_BLOCK_DATA)) {
		dev_err(&client->dev,
			"Adapter does not support required functionalities\n");
		return -EOPNOTSUPP;
	}

	iio_dev = devm_iio_device_alloc(&client->dev, sizeof(*sunrise));
	if (!iio_dev)
		return -ENOMEM;

	sunrise = iio_priv(iio_dev);
	sunrise->client = client;
	mutex_init(&sunrise->lock);

	i2c_set_clientdata(client, sunrise);

	sunrise->regmap = devm_regmap_init(&client->dev, &sunrise_regmap_bus,
					   client, &sunrise_regmap_config);
	if (IS_ERR(sunrise->regmap)) {
		dev_err(&client->dev, "Failed to initialize regmap\n");
		return PTR_ERR(sunrise->regmap);
	}

	/*
	 * The chip nacks the wake up message. If the adapter does not support
	 * protocol mangling do not set the I2C_M_IGNORE_NAK flag at the expense
	 * of possible cruft in the logs.
	 */
	if (i2c_check_functionality(client->adapter, I2C_FUNC_PROTOCOL_MANGLING))
		sunrise->ignore_nak = true;

	iio_dev->info = &sunrise_info;
	iio_dev->name = DRIVER_NAME;
	iio_dev->channels = sunrise_channels;
	iio_dev->num_channels = ARRAY_SIZE(sunrise_channels);
	iio_dev->modes = INDIO_DIRECT_MODE;

	return devm_iio_device_register(&client->dev, iio_dev);
}

static const struct of_device_id sunrise_of_match[] = {
	{ .compatible = "senseair,sunrise-006-0-0007" },
	{}
};
MODULE_DEVICE_TABLE(of, sunrise_of_match);

static struct i2c_driver sunrise_driver = {
	.driver = {
		.name = DRIVER_NAME,
		.of_match_table = sunrise_of_match,
	},
	.probe_new = sunrise_probe,
};
module_i2c_driver(sunrise_driver);

MODULE_AUTHOR("Jacopo Mondi <jacopo@jmondi.org>");
MODULE_DESCRIPTION("Senseair Sunrise 006-0-0007 CO2 sensor IIO driver");
MODULE_LICENSE("GPL v2");