linux/drivers/iio/humidity/hdc3020.c

// SPDX-License-Identifier: GPL-2.0+
/*
 * hdc3020.c - Support for the TI HDC3020,HDC3021 and HDC3022
 * temperature + relative humidity sensors
 *
 * Copyright (C) 2023
 *
 * Copyright (C) 2024 Liebherr-Electronics and Drives GmbH
 *
 * Datasheet: https://www.ti.com/lit/ds/symlink/hdc3020.pdf
 */

#include <linux/bitfield.h>
#include <linux/bitops.h>
#include <linux/cleanup.h>
#include <linux/crc8.h>
#include <linux/delay.h>
#include <linux/gpio/consumer.h>
#include <linux/i2c.h>
#include <linux/init.h>
#include <linux/interrupt.h>
#include <linux/math64.h>
#include <linux/module.h>
#include <linux/mutex.h>
#include <linux/pm.h>
#include <linux/regulator/consumer.h>
#include <linux/units.h>

#include <linux/unaligned.h>

#include <linux/iio/events.h>
#include <linux/iio/iio.h>

#define HDC3020_S_AUTO_10HZ_MOD0	0x2737
#define HDC3020_S_STATUS		0x3041
#define HDC3020_HEATER_DISABLE		0x3066
#define HDC3020_HEATER_ENABLE		0x306D
#define HDC3020_HEATER_CONFIG		0x306E
#define HDC3020_EXIT_AUTO		0x3093
#define HDC3020_S_T_RH_THRESH_LOW	0x6100
#define HDC3020_S_T_RH_THRESH_LOW_CLR	0x610B
#define HDC3020_S_T_RH_THRESH_HIGH_CLR	0x6116
#define HDC3020_S_T_RH_THRESH_HIGH	0x611D
#define HDC3020_R_T_RH_AUTO		0xE000
#define HDC3020_R_T_LOW_AUTO		0xE002
#define HDC3020_R_T_HIGH_AUTO		0xE003
#define HDC3020_R_RH_LOW_AUTO		0xE004
#define HDC3020_R_RH_HIGH_AUTO		0xE005
#define HDC3020_R_T_RH_THRESH_LOW	0xE102
#define HDC3020_R_T_RH_THRESH_LOW_CLR	0xE109
#define HDC3020_R_T_RH_THRESH_HIGH_CLR	0xE114
#define HDC3020_R_T_RH_THRESH_HIGH	0xE11F
#define HDC3020_R_STATUS		0xF32D

#define HDC3020_THRESH_TEMP_MASK	GENMASK(8, 0)
#define HDC3020_THRESH_TEMP_TRUNC_SHIFT	7
#define HDC3020_THRESH_HUM_MASK		GENMASK(15, 9)
#define HDC3020_THRESH_HUM_TRUNC_SHIFT	9

#define HDC3020_STATUS_T_LOW_ALERT	BIT(6)
#define HDC3020_STATUS_T_HIGH_ALERT	BIT(7)
#define HDC3020_STATUS_RH_LOW_ALERT	BIT(8)
#define HDC3020_STATUS_RH_HIGH_ALERT	BIT(9)

#define HDC3020_READ_RETRY_TIMES	10
#define HDC3020_BUSY_DELAY_MS		10

#define HDC3020_CRC8_POLYNOMIAL		0x31

#define HDC3020_MIN_TEMP_MICRO		-39872968
#define HDC3020_MAX_TEMP_MICRO		124875639
#define HDC3020_MAX_TEMP_HYST_MICRO	164748607
#define HDC3020_MAX_HUM_MICRO		99220264

/* Divide 65535 from the datasheet by 5 to avoid overflows */
#define HDC3020_THRESH_FRACTION		(65535 / 5)

struct hdc3020_data {
	struct i2c_client *client;
	struct gpio_desc *reset_gpio;
	struct regulator *vdd_supply;
	/*
	 * Ensure that the sensor configuration (currently only heater is
	 * supported) will not be changed during the process of reading
	 * sensor data (this driver will try HDC3020_READ_RETRY_TIMES times
	 * if the device does not respond).
	 */
	struct mutex lock;
};

static const int hdc3020_heater_vals[] = {0, 1, 0x3FFF};

static const struct iio_event_spec hdc3020_t_rh_event[] = {
	{
		.type = IIO_EV_TYPE_THRESH,
		.dir = IIO_EV_DIR_RISING,
		.mask_separate = BIT(IIO_EV_INFO_VALUE) |
		BIT(IIO_EV_INFO_HYSTERESIS),
	},
	{
		.type = IIO_EV_TYPE_THRESH,
		.dir = IIO_EV_DIR_FALLING,
		.mask_separate = BIT(IIO_EV_INFO_VALUE) |
		BIT(IIO_EV_INFO_HYSTERESIS),
	},
};

static const struct iio_chan_spec hdc3020_channels[] = {
	{
		.type = IIO_TEMP,
		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
		BIT(IIO_CHAN_INFO_SCALE) | BIT(IIO_CHAN_INFO_PEAK) |
		BIT(IIO_CHAN_INFO_TROUGH) | BIT(IIO_CHAN_INFO_OFFSET),
		.event_spec = hdc3020_t_rh_event,
		.num_event_specs = ARRAY_SIZE(hdc3020_t_rh_event),
	},
	{
		.type = IIO_HUMIDITYRELATIVE,
		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
		BIT(IIO_CHAN_INFO_SCALE) | BIT(IIO_CHAN_INFO_PEAK) |
		BIT(IIO_CHAN_INFO_TROUGH),
		.event_spec = hdc3020_t_rh_event,
		.num_event_specs = ARRAY_SIZE(hdc3020_t_rh_event),
	},
	{
		/*
		 * For setting the internal heater, which can be switched on to
		 * prevent or remove any condensation that may develop when the
		 * ambient environment approaches its dew point temperature.
		 */
		.type = IIO_CURRENT,
		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
		.info_mask_separate_available = BIT(IIO_CHAN_INFO_RAW),
		.output = 1,
	},
};

DECLARE_CRC8_TABLE(hdc3020_crc8_table);

static int hdc3020_write_bytes(struct hdc3020_data *data, u8 *buf, u8 len)
{
	struct i2c_client *client = data->client;
	struct i2c_msg msg;
	int ret, cnt;

	msg.addr = client->addr;
	msg.flags = 0;
	msg.buf = buf;
	msg.len = len;

	/*
	 * During the measurement process, HDC3020 will not return data.
	 * So wait for a while and try again
	 */
	for (cnt = 0; cnt < HDC3020_READ_RETRY_TIMES; cnt++) {
		ret = i2c_transfer(client->adapter, &msg, 1);
		if (ret == 1)
			return 0;

		mdelay(HDC3020_BUSY_DELAY_MS);
	}
	dev_err(&client->dev, "Could not write sensor command\n");

	return -ETIMEDOUT;
}

static
int hdc3020_read_bytes(struct hdc3020_data *data, u16 reg, u8 *buf, int len)
{
	u8 reg_buf[2];
	int ret, cnt;
	struct i2c_client *client = data->client;
	struct i2c_msg msg[2] = {
		[0] = {
			.addr = client->addr,
			.flags = 0,
			.buf = reg_buf,
			.len = 2,
		},
		[1] = {
			.addr = client->addr,
			.flags = I2C_M_RD,
			.buf = buf,
			.len = len,
		},
	};

	put_unaligned_be16(reg, reg_buf);
	/*
	 * During the measurement process, HDC3020 will not return data.
	 * So wait for a while and try again
	 */
	for (cnt = 0; cnt < HDC3020_READ_RETRY_TIMES; cnt++) {
		ret = i2c_transfer(client->adapter, msg, 2);
		if (ret == 2)
			return 0;

		mdelay(HDC3020_BUSY_DELAY_MS);
	}
	dev_err(&client->dev, "Could not read sensor data\n");

	return -ETIMEDOUT;
}

static int hdc3020_read_be16(struct hdc3020_data *data, u16 reg)
{
	u8 crc, buf[3];
	int ret;

	ret = hdc3020_read_bytes(data, reg, buf, 3);
	if (ret < 0)
		return ret;

	crc = crc8(hdc3020_crc8_table, buf, 2, CRC8_INIT_VALUE);
	if (crc != buf[2])
		return -EINVAL;

	return get_unaligned_be16(buf);
}

static int hdc3020_exec_cmd(struct hdc3020_data *data, u16 reg)
{
	u8 reg_buf[2];

	put_unaligned_be16(reg, reg_buf);
	return hdc3020_write_bytes(data, reg_buf, 2);
}

static int hdc3020_read_measurement(struct hdc3020_data *data,
				    enum iio_chan_type type, int *val)
{
	u8 crc, buf[6];
	int ret;

	ret = hdc3020_read_bytes(data, HDC3020_R_T_RH_AUTO, buf, 6);
	if (ret < 0)
		return ret;

	/* CRC check of the temperature measurement */
	crc = crc8(hdc3020_crc8_table, buf, 2, CRC8_INIT_VALUE);
	if (crc != buf[2])
		return -EINVAL;

	/* CRC check of the relative humidity measurement */
	crc = crc8(hdc3020_crc8_table, buf + 3, 2, CRC8_INIT_VALUE);
	if (crc != buf[5])
		return -EINVAL;

	if (type == IIO_TEMP)
		*val = get_unaligned_be16(buf);
	else if (type == IIO_HUMIDITYRELATIVE)
		*val = get_unaligned_be16(&buf[3]);
	else
		return -EINVAL;

	return 0;
}

static int hdc3020_read_raw(struct iio_dev *indio_dev,
			    struct iio_chan_spec const *chan, int *val,
			    int *val2, long mask)
{
	struct hdc3020_data *data = iio_priv(indio_dev);
	int ret;

	if (chan->type != IIO_TEMP && chan->type != IIO_HUMIDITYRELATIVE)
		return -EINVAL;

	switch (mask) {
	case IIO_CHAN_INFO_RAW: {
		guard(mutex)(&data->lock);
		ret = hdc3020_read_measurement(data, chan->type, val);
		if (ret < 0)
			return ret;

		return IIO_VAL_INT;
	}
	case IIO_CHAN_INFO_PEAK: {
		guard(mutex)(&data->lock);
		if (chan->type == IIO_TEMP)
			ret = hdc3020_read_be16(data, HDC3020_R_T_HIGH_AUTO);
		else
			ret = hdc3020_read_be16(data, HDC3020_R_RH_HIGH_AUTO);

		if (ret < 0)
			return ret;

		*val = ret;
		return IIO_VAL_INT;
	}
	case IIO_CHAN_INFO_TROUGH: {
		guard(mutex)(&data->lock);
		if (chan->type == IIO_TEMP)
			ret = hdc3020_read_be16(data, HDC3020_R_T_LOW_AUTO);
		else
			ret = hdc3020_read_be16(data, HDC3020_R_RH_LOW_AUTO);

		if (ret < 0)
			return ret;

		*val = ret;
		return IIO_VAL_INT;
	}
	case IIO_CHAN_INFO_SCALE:
		*val2 = 65536;
		if (chan->type == IIO_TEMP)
			*val = 175 * MILLI;
		else
			*val = 100 * MILLI;
		return IIO_VAL_FRACTIONAL;

	case IIO_CHAN_INFO_OFFSET:
		if (chan->type != IIO_TEMP)
			return -EINVAL;

		*val = -16852;
		return IIO_VAL_INT;

	default:
		return -EINVAL;
	}
}

static int hdc3020_read_available(struct iio_dev *indio_dev,
				  struct iio_chan_spec const *chan,
				  const int **vals,
				  int *type, int *length, long mask)
{
	if (mask != IIO_CHAN_INFO_RAW || chan->type != IIO_CURRENT)
		return -EINVAL;

	*vals = hdc3020_heater_vals;
	*type = IIO_VAL_INT;

	return IIO_AVAIL_RANGE;
}

static int hdc3020_update_heater(struct hdc3020_data *data, int val)
{
	u8 buf[5];
	int ret;

	if (val < hdc3020_heater_vals[0] || val > hdc3020_heater_vals[2])
		return -EINVAL;

	if (!val)
		hdc3020_exec_cmd(data, HDC3020_HEATER_DISABLE);

	put_unaligned_be16(HDC3020_HEATER_CONFIG, buf);
	put_unaligned_be16(val & GENMASK(13, 0), &buf[2]);
	buf[4] = crc8(hdc3020_crc8_table, buf + 2, 2, CRC8_INIT_VALUE);
	ret = hdc3020_write_bytes(data, buf, 5);
	if (ret < 0)
		return ret;

	return hdc3020_exec_cmd(data, HDC3020_HEATER_ENABLE);
}

static int hdc3020_write_raw(struct iio_dev *indio_dev,
			     struct iio_chan_spec const *chan,
			     int val, int val2, long mask)
{
	struct hdc3020_data *data = iio_priv(indio_dev);

	switch (mask) {
	case IIO_CHAN_INFO_RAW:
		if (chan->type != IIO_CURRENT)
			return -EINVAL;

		guard(mutex)(&data->lock);
		return hdc3020_update_heater(data, val);
	}

	return -EINVAL;
}

static int hdc3020_thresh_get_temp(u16 thresh)
{
	int temp;

	/*
	 * Get the temperature threshold from 9 LSBs, shift them to get the
	 * truncated temperature threshold representation and calculate the
	 * threshold according to the explicit formula in the datasheet:
	 * T(C) = -45 + (175 * temp) / 65535.
	 * Additionally scale by HDC3020_THRESH_FRACTION to avoid precision loss
	 * when calculating threshold and hysteresis values. Result is degree
	 * celsius scaled by HDC3020_THRESH_FRACTION.
	 */
	temp = FIELD_GET(HDC3020_THRESH_TEMP_MASK, thresh) <<
	       HDC3020_THRESH_TEMP_TRUNC_SHIFT;

	return -2949075 / 5 + (175 / 5 * temp);
}

static int hdc3020_thresh_get_hum(u16 thresh)
{
	int hum;

	/*
	 * Get the humidity threshold from 7 MSBs, shift them to get the
	 * truncated humidity threshold representation and calculate the
	 * threshold according to the explicit formula in the datasheet:
	 * RH(%) = 100 * hum / 65535.
	 * Additionally scale by HDC3020_THRESH_FRACTION to avoid precision loss
	 * when calculating threshold and hysteresis values. Result is percent
	 * scaled by HDC3020_THRESH_FRACTION.
	 */
	hum = FIELD_GET(HDC3020_THRESH_HUM_MASK, thresh) <<
	      HDC3020_THRESH_HUM_TRUNC_SHIFT;

	return hum * 100 / 5;
}

static u16 hdc3020_thresh_set_temp(int s_temp, u16 curr_thresh)
{
	u64 temp;
	u16 thresh;

	/*
	 * Calculate temperature threshold, shift it down to get the
	 * truncated threshold representation in the 9LSBs while keeping
	 * the current humidity threshold in the 7 MSBs.
	 */
	temp = (u64)(s_temp + 45000000) * 65535ULL;
	temp = div_u64(temp, 1000000 * 175) >> HDC3020_THRESH_TEMP_TRUNC_SHIFT;
	thresh = FIELD_PREP(HDC3020_THRESH_TEMP_MASK, temp);
	thresh |= (FIELD_GET(HDC3020_THRESH_HUM_MASK, curr_thresh) <<
		  HDC3020_THRESH_HUM_TRUNC_SHIFT);

	return thresh;
}

static u16 hdc3020_thresh_set_hum(int s_hum, u16 curr_thresh)
{
	u64 hum;
	u16 thresh;

	/*
	 * Calculate humidity threshold, shift it down and up to get the
	 * truncated threshold representation in the 7MSBs while keeping
	 * the current temperature threshold in the 9 LSBs.
	 */
	hum = (u64)(s_hum) * 65535ULL;
	hum = div_u64(hum, 1000000 * 100) >> HDC3020_THRESH_HUM_TRUNC_SHIFT;
	thresh = FIELD_PREP(HDC3020_THRESH_HUM_MASK, hum);
	thresh |= FIELD_GET(HDC3020_THRESH_TEMP_MASK, curr_thresh);

	return thresh;
}

static
int hdc3020_thresh_clr(s64 s_thresh, s64 s_hyst, enum iio_event_direction dir)
{
	s64 s_clr;

	/*
	 * Include directions when calculation the clear value,
	 * since hysteresis is unsigned by definition and the
	 * clear value is an absolute value which is signed.
	 */
	if (dir == IIO_EV_DIR_RISING)
		s_clr = s_thresh - s_hyst;
	else
		s_clr = s_thresh + s_hyst;

	/* Divide by HDC3020_THRESH_FRACTION to get units of micro */
	return div_s64(s_clr, HDC3020_THRESH_FRACTION);
}

static int _hdc3020_write_thresh(struct hdc3020_data *data, u16 reg, u16 val)
{
	u8 buf[5];

	put_unaligned_be16(reg, buf);
	put_unaligned_be16(val, buf + 2);
	buf[4] = crc8(hdc3020_crc8_table, buf + 2, 2, CRC8_INIT_VALUE);

	return hdc3020_write_bytes(data, buf, 5);
}

static int hdc3020_write_thresh(struct iio_dev *indio_dev,
				const struct iio_chan_spec *chan,
				enum iio_event_type type,
				enum iio_event_direction dir,
				enum iio_event_info info,
				int val, int val2)
{
	struct hdc3020_data *data = iio_priv(indio_dev);
	u16 reg, reg_val, reg_thresh_rd, reg_clr_rd, reg_thresh_wr, reg_clr_wr;
	s64 s_thresh, s_hyst, s_clr;
	int s_val, thresh, clr, ret;

	/* Select threshold registers */
	if (dir == IIO_EV_DIR_RISING) {
		reg_thresh_rd = HDC3020_R_T_RH_THRESH_HIGH;
		reg_thresh_wr = HDC3020_S_T_RH_THRESH_HIGH;
		reg_clr_rd = HDC3020_R_T_RH_THRESH_HIGH_CLR;
		reg_clr_wr = HDC3020_S_T_RH_THRESH_HIGH_CLR;
	} else {
		reg_thresh_rd = HDC3020_R_T_RH_THRESH_LOW;
		reg_thresh_wr = HDC3020_S_T_RH_THRESH_LOW;
		reg_clr_rd = HDC3020_R_T_RH_THRESH_LOW_CLR;
		reg_clr_wr = HDC3020_S_T_RH_THRESH_LOW_CLR;
	}

	guard(mutex)(&data->lock);
	ret = hdc3020_read_be16(data, reg_thresh_rd);
	if (ret < 0)
		return ret;

	thresh = ret;
	ret = hdc3020_read_be16(data, reg_clr_rd);
	if (ret < 0)
		return ret;

	clr = ret;
	/* Scale value to include decimal part into calculations */
	s_val = (val < 0) ? (val * 1000 - val2) : (val * 1000 + val2);
	switch (chan->type) {
	case IIO_TEMP:
		switch (info) {
		case IIO_EV_INFO_VALUE:
			s_val = max(s_val, HDC3020_MIN_TEMP_MICRO);
			s_val = min(s_val, HDC3020_MAX_TEMP_MICRO);
			reg = reg_thresh_wr;
			reg_val = hdc3020_thresh_set_temp(s_val, thresh);
			ret = _hdc3020_write_thresh(data, reg, reg_val);
			if (ret < 0)
				return ret;

			/* Calculate old hysteresis */
			s_thresh = (s64)hdc3020_thresh_get_temp(thresh) * 1000000;
			s_clr = (s64)hdc3020_thresh_get_temp(clr) * 1000000;
			s_hyst = div_s64(abs(s_thresh - s_clr),
					 HDC3020_THRESH_FRACTION);
			/* Set new threshold */
			thresh = reg_val;
			/* Set old hysteresis */
			s_val = s_hyst;
			fallthrough;
		case IIO_EV_INFO_HYSTERESIS:
			/*
			 * Function hdc3020_thresh_get_temp returns temperature
			 * in degree celsius scaled by HDC3020_THRESH_FRACTION.
			 * Scale by 1000000 to be able to subtract scaled
			 * hysteresis value.
			 */
			s_thresh = (s64)hdc3020_thresh_get_temp(thresh) * 1000000;
			/*
			 * Units of s_val are in micro degree celsius, scale by
			 * HDC3020_THRESH_FRACTION to get same units as s_thresh.
			 */
			s_val = min(abs(s_val), HDC3020_MAX_TEMP_HYST_MICRO);
			s_hyst = (s64)s_val * HDC3020_THRESH_FRACTION;
			s_clr = hdc3020_thresh_clr(s_thresh, s_hyst, dir);
			s_clr = max(s_clr, HDC3020_MIN_TEMP_MICRO);
			s_clr = min(s_clr, HDC3020_MAX_TEMP_MICRO);
			reg = reg_clr_wr;
			reg_val = hdc3020_thresh_set_temp(s_clr, clr);
			break;
		default:
			return -EOPNOTSUPP;
		}
		break;
	case IIO_HUMIDITYRELATIVE:
		s_val = (s_val < 0) ? 0 : min(s_val, HDC3020_MAX_HUM_MICRO);
		switch (info) {
		case IIO_EV_INFO_VALUE:
			reg = reg_thresh_wr;
			reg_val = hdc3020_thresh_set_hum(s_val, thresh);
			ret = _hdc3020_write_thresh(data, reg, reg_val);
			if (ret < 0)
				return ret;

			/* Calculate old hysteresis */
			s_thresh = (s64)hdc3020_thresh_get_hum(thresh) * 1000000;
			s_clr = (s64)hdc3020_thresh_get_hum(clr) * 1000000;
			s_hyst = div_s64(abs(s_thresh - s_clr),
					 HDC3020_THRESH_FRACTION);
			/* Set new threshold */
			thresh = reg_val;
			/* Try to set old hysteresis */
			s_val = min(abs(s_hyst), HDC3020_MAX_HUM_MICRO);
			fallthrough;
		case IIO_EV_INFO_HYSTERESIS:
			/*
			 * Function hdc3020_thresh_get_hum returns relative
			 * humidity in percent scaled by HDC3020_THRESH_FRACTION.
			 * Scale by 1000000 to be able to subtract scaled
			 * hysteresis value.
			 */
			s_thresh = (s64)hdc3020_thresh_get_hum(thresh) * 1000000;
			/*
			 * Units of s_val are in micro percent, scale by
			 * HDC3020_THRESH_FRACTION to get same units as s_thresh.
			 */
			s_hyst = (s64)s_val * HDC3020_THRESH_FRACTION;
			s_clr = hdc3020_thresh_clr(s_thresh, s_hyst, dir);
			s_clr = max(s_clr, 0);
			s_clr = min(s_clr, HDC3020_MAX_HUM_MICRO);
			reg = reg_clr_wr;
			reg_val = hdc3020_thresh_set_hum(s_clr, clr);
			break;
		default:
			return -EOPNOTSUPP;
		}
		break;
	default:
		return -EOPNOTSUPP;
	}

	return _hdc3020_write_thresh(data, reg, reg_val);
}

static int hdc3020_read_thresh(struct iio_dev *indio_dev,
			       const struct iio_chan_spec *chan,
			       enum iio_event_type type,
			       enum iio_event_direction dir,
			       enum iio_event_info info,
			       int *val, int *val2)
{
	struct hdc3020_data *data = iio_priv(indio_dev);
	u16 reg_thresh, reg_clr;
	int thresh, clr, ret;

	/* Select threshold registers */
	if (dir == IIO_EV_DIR_RISING) {
		reg_thresh = HDC3020_R_T_RH_THRESH_HIGH;
		reg_clr = HDC3020_R_T_RH_THRESH_HIGH_CLR;
	} else {
		reg_thresh = HDC3020_R_T_RH_THRESH_LOW;
		reg_clr = HDC3020_R_T_RH_THRESH_LOW_CLR;
	}

	guard(mutex)(&data->lock);
	ret = hdc3020_read_be16(data, reg_thresh);
	if (ret < 0)
		return ret;

	switch (chan->type) {
	case IIO_TEMP:
		thresh = hdc3020_thresh_get_temp(ret);
		switch (info) {
		case IIO_EV_INFO_VALUE:
			*val = thresh * MILLI;
			break;
		case IIO_EV_INFO_HYSTERESIS:
			ret = hdc3020_read_be16(data, reg_clr);
			if (ret < 0)
				return ret;

			clr = hdc3020_thresh_get_temp(ret);
			*val = abs(thresh - clr) * MILLI;
			break;
		default:
			return -EOPNOTSUPP;
		}
		*val2 = HDC3020_THRESH_FRACTION;
		return IIO_VAL_FRACTIONAL;
	case IIO_HUMIDITYRELATIVE:
		thresh = hdc3020_thresh_get_hum(ret);
		switch (info) {
		case IIO_EV_INFO_VALUE:
			*val = thresh * MILLI;
			break;
		case IIO_EV_INFO_HYSTERESIS:
			ret = hdc3020_read_be16(data, reg_clr);
			if (ret < 0)
				return ret;

			clr = hdc3020_thresh_get_hum(ret);
			*val = abs(thresh - clr) * MILLI;
			break;
		default:
			return -EOPNOTSUPP;
		}
		*val2 = HDC3020_THRESH_FRACTION;
		return IIO_VAL_FRACTIONAL;
	default:
		return -EOPNOTSUPP;
	}
}

static irqreturn_t hdc3020_interrupt_handler(int irq, void *private)
{
	struct iio_dev *indio_dev = private;
	struct hdc3020_data *data;
	s64 time;
	int ret;

	data = iio_priv(indio_dev);
	ret = hdc3020_read_be16(data, HDC3020_R_STATUS);
	if (ret < 0)
		return IRQ_HANDLED;

	if (!(ret & (HDC3020_STATUS_T_HIGH_ALERT | HDC3020_STATUS_T_LOW_ALERT |
		HDC3020_STATUS_RH_HIGH_ALERT | HDC3020_STATUS_RH_LOW_ALERT)))
		return IRQ_NONE;

	time = iio_get_time_ns(indio_dev);
	if (ret & HDC3020_STATUS_T_HIGH_ALERT)
		iio_push_event(indio_dev,
			       IIO_MOD_EVENT_CODE(IIO_TEMP, 0,
						  IIO_NO_MOD,
						  IIO_EV_TYPE_THRESH,
						  IIO_EV_DIR_RISING),
						  time);

	if (ret & HDC3020_STATUS_T_LOW_ALERT)
		iio_push_event(indio_dev,
			       IIO_MOD_EVENT_CODE(IIO_TEMP, 0,
						  IIO_NO_MOD,
						  IIO_EV_TYPE_THRESH,
						  IIO_EV_DIR_FALLING),
						  time);

	if (ret & HDC3020_STATUS_RH_HIGH_ALERT)
		iio_push_event(indio_dev,
			       IIO_MOD_EVENT_CODE(IIO_HUMIDITYRELATIVE, 0,
						  IIO_NO_MOD,
						  IIO_EV_TYPE_THRESH,
						  IIO_EV_DIR_RISING),
						  time);

	if (ret & HDC3020_STATUS_RH_LOW_ALERT)
		iio_push_event(indio_dev,
			       IIO_MOD_EVENT_CODE(IIO_HUMIDITYRELATIVE, 0,
						  IIO_NO_MOD,
						  IIO_EV_TYPE_THRESH,
						  IIO_EV_DIR_FALLING),
						  time);

	return IRQ_HANDLED;
}

static const struct iio_info hdc3020_info = {
	.read_raw = hdc3020_read_raw,
	.write_raw = hdc3020_write_raw,
	.read_avail = hdc3020_read_available,
	.read_event_value = hdc3020_read_thresh,
	.write_event_value = hdc3020_write_thresh,
};

static int hdc3020_power_off(struct hdc3020_data *data)
{
	hdc3020_exec_cmd(data, HDC3020_EXIT_AUTO);

	if (data->reset_gpio)
		gpiod_set_value_cansleep(data->reset_gpio, 1);

	return regulator_disable(data->vdd_supply);
}

static int hdc3020_power_on(struct hdc3020_data *data)
{
	int ret;

	ret = regulator_enable(data->vdd_supply);
	if (ret)
		return ret;

	fsleep(5000);

	if (data->reset_gpio) {
		gpiod_set_value_cansleep(data->reset_gpio, 0);
		fsleep(3000);
	}

	if (data->client->irq) {
		/*
		 * The alert output is activated by default upon power up,
		 * hardware reset, and soft reset. Clear the status register.
		 */
		ret = hdc3020_exec_cmd(data, HDC3020_S_STATUS);
		if (ret) {
			hdc3020_power_off(data);
			return ret;
		}
	}

	ret = hdc3020_exec_cmd(data, HDC3020_S_AUTO_10HZ_MOD0);
	if (ret)
		hdc3020_power_off(data);

	return ret;
}

static void hdc3020_exit(void *data)
{
	hdc3020_power_off(data);
}

static int hdc3020_probe(struct i2c_client *client)
{
	struct iio_dev *indio_dev;
	struct hdc3020_data *data;
	int ret;

	if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C))
		return -EOPNOTSUPP;

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

	dev_set_drvdata(&client->dev, indio_dev);

	data = iio_priv(indio_dev);
	data->client = client;
	mutex_init(&data->lock);

	crc8_populate_msb(hdc3020_crc8_table, HDC3020_CRC8_POLYNOMIAL);

	indio_dev->name = "hdc3020";
	indio_dev->modes = INDIO_DIRECT_MODE;
	indio_dev->info = &hdc3020_info;
	indio_dev->channels = hdc3020_channels;
	indio_dev->num_channels = ARRAY_SIZE(hdc3020_channels);

	data->vdd_supply = devm_regulator_get(&client->dev, "vdd");
	if (IS_ERR(data->vdd_supply))
		return dev_err_probe(&client->dev, PTR_ERR(data->vdd_supply),
				     "Unable to get VDD regulator\n");

	data->reset_gpio = devm_gpiod_get_optional(&client->dev, "reset",
						   GPIOD_OUT_HIGH);
	if (IS_ERR(data->reset_gpio))
		return dev_err_probe(&client->dev, PTR_ERR(data->reset_gpio),
				     "Cannot get reset GPIO\n");

	ret = hdc3020_power_on(data);
	if (ret)
		return dev_err_probe(&client->dev, ret, "Power on failed\n");

	ret = devm_add_action_or_reset(&data->client->dev, hdc3020_exit, data);
	if (ret)
		return ret;

	if (client->irq) {
		ret = devm_request_threaded_irq(&client->dev, client->irq,
						NULL, hdc3020_interrupt_handler,
						IRQF_ONESHOT, "hdc3020",
						indio_dev);
		if (ret)
			return dev_err_probe(&client->dev, ret,
					     "Failed to request IRQ\n");
	}

	ret = devm_iio_device_register(&data->client->dev, indio_dev);
	if (ret)
		return dev_err_probe(&client->dev, ret, "Failed to add device");

	return 0;
}

static int hdc3020_suspend(struct device *dev)
{
	struct iio_dev *iio_dev = dev_get_drvdata(dev);
	struct hdc3020_data *data = iio_priv(iio_dev);

	return hdc3020_power_off(data);
}

static int hdc3020_resume(struct device *dev)
{
	struct iio_dev *iio_dev = dev_get_drvdata(dev);
	struct hdc3020_data *data = iio_priv(iio_dev);

	return hdc3020_power_on(data);
}

static DEFINE_SIMPLE_DEV_PM_OPS(hdc3020_pm_ops, hdc3020_suspend, hdc3020_resume);

static const struct i2c_device_id hdc3020_id[] = {
	{ "hdc3020" },
	{ "hdc3021" },
	{ "hdc3022" },
	{ }
};
MODULE_DEVICE_TABLE(i2c, hdc3020_id);

static const struct of_device_id hdc3020_dt_ids[] = {
	{ .compatible = "ti,hdc3020" },
	{ .compatible = "ti,hdc3021" },
	{ .compatible = "ti,hdc3022" },
	{ }
};
MODULE_DEVICE_TABLE(of, hdc3020_dt_ids);

static struct i2c_driver hdc3020_driver = {
	.driver = {
		.name = "hdc3020",
		.pm = pm_sleep_ptr(&hdc3020_pm_ops),
		.of_match_table = hdc3020_dt_ids,
	},
	.probe = hdc3020_probe,
	.id_table = hdc3020_id,
};
module_i2c_driver(hdc3020_driver);

MODULE_AUTHOR("Javier Carrasco <javier.carrasco.cruz@gmail.com>");
MODULE_AUTHOR("Li peiyu <579lpy@gmail.com>");
MODULE_DESCRIPTION("TI HDC3020 humidity and temperature sensor driver");
MODULE_LICENSE("GPL");