// 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");