// SPDX-License-Identifier: GPL-2.0-only
/*
 * Copyright (c) 2010 Christoph Mair <christoph.mair@gmail.com>
 * Copyright (c) 2012 Bosch Sensortec GmbH
 * Copyright (c) 2012 Unixphere AB
 * Copyright (c) 2014 Intel Corporation
 * Copyright (c) 2016 Linus Walleij <linus.walleij@linaro.org>
 *
 * Driver for Bosch Sensortec BMP180 and BMP280 digital pressure sensor.
 *
 * Datasheet:
 * https://ae-bst.resource.bosch.com/media/_tech/media/datasheets/BST-BMP180-DS000-121.pdf
 * https://ae-bst.resource.bosch.com/media/_tech/media/datasheets/BST-BMP280-DS001-12.pdf
 * https://ae-bst.resource.bosch.com/media/_tech/media/datasheets/BST-BME280_DS001-11.pdf
 */

#define pr_fmt(fmt) "bmp280: " fmt

#include <linux/device.h>
#include <linux/module.h>
#include <linux/regmap.h>
#include <linux/delay.h>
#include <linux/iio/iio.h>
#include <linux/iio/sysfs.h>
#include <linux/gpio/consumer.h>
#include <linux/regulator/consumer.h>
#include <linux/interrupt.h>
#include <linux/irq.h> /* For irq_get_irq_data() */
#include <linux/completion.h>
#include <linux/pm_runtime.h>
#include <linux/random.h>

#include "bmp280.h"

/*
 * These enums are used for indexing into the array of calibration
 * coefficients for BMP180.
 */
enum { AC1, AC2, AC3, AC4, AC5, AC6, B1, B2, MB, MC, MD };

struct bmp180_calib {
        s16 AC1;
        s16 AC2;
        s16 AC3;
        u16 AC4;
        u16 AC5;
        u16 AC6;
        s16 B1;
        s16 B2;
        s16 MB;
        s16 MC;
        s16 MD;
};

/* See datasheet Section 4.2.2. */
struct bmp280_calib {
        u16 T1;
        s16 T2;
        s16 T3;
        u16 P1;
        s16 P2;
        s16 P3;
        s16 P4;
        s16 P5;
        s16 P6;
        s16 P7;
        s16 P8;
        s16 P9;
        u8  H1;
        s16 H2;
        u8  H3;
        s16 H4;
        s16 H5;
        s8  H6;
};

static const char *const bmp280_supply_names[] = {
        "vddd", "vdda"
};

#define BMP280_NUM_SUPPLIES ARRAY_SIZE(bmp280_supply_names)

struct bmp280_data {
        struct device *dev;
        struct mutex lock;
        struct regmap *regmap;
        struct completion done;
        bool use_eoc;
        const struct bmp280_chip_info *chip_info;
        union {
                struct bmp180_calib bmp180;
                struct bmp280_calib bmp280;
        } calib;
        struct regulator_bulk_data supplies[BMP280_NUM_SUPPLIES];
        unsigned int start_up_time; /* in microseconds */

        /* log of base 2 of oversampling rate */
        u8 oversampling_press;
        u8 oversampling_temp;
        u8 oversampling_humid;

        /*
         * Carryover value from temperature conversion, used in pressure
         * calculation.
         */
        s32 t_fine;
};

struct bmp280_chip_info {
        const int *oversampling_temp_avail;
        int num_oversampling_temp_avail;

        const int *oversampling_press_avail;
        int num_oversampling_press_avail;

        const int *oversampling_humid_avail;
        int num_oversampling_humid_avail;

        int (*chip_config)(struct bmp280_data *);
        int (*read_temp)(struct bmp280_data *, int *);
        int (*read_press)(struct bmp280_data *, int *, int *);
        int (*read_humid)(struct bmp280_data *, int *, int *);
};

/*
 * These enums are used for indexing into the array of compensation
 * parameters for BMP280.
 */
enum { T1, T2, T3 };
enum { P1, P2, P3, P4, P5, P6, P7, P8, P9 };

static const struct iio_chan_spec bmp280_channels[] = {
        {
                .type = IIO_PRESSURE,
                .info_mask_separate = BIT(IIO_CHAN_INFO_PROCESSED) |
                                      BIT(IIO_CHAN_INFO_OVERSAMPLING_RATIO),
        },
        {
                .type = IIO_TEMP,
                .info_mask_separate = BIT(IIO_CHAN_INFO_PROCESSED) |
                                      BIT(IIO_CHAN_INFO_OVERSAMPLING_RATIO),
        },
        {
                .type = IIO_HUMIDITYRELATIVE,
                .info_mask_separate = BIT(IIO_CHAN_INFO_PROCESSED) |
                                      BIT(IIO_CHAN_INFO_OVERSAMPLING_RATIO),
        },
};

static int bmp280_read_calib(struct bmp280_data *data,
                             struct bmp280_calib *calib,
                             unsigned int chip)
{
        int ret;
        unsigned int tmp;
        __le16 l16;
        __be16 b16;
        struct device *dev = data->dev;
        __le16 t_buf[BMP280_COMP_TEMP_REG_COUNT / 2];
        __le16 p_buf[BMP280_COMP_PRESS_REG_COUNT / 2];

        /* Read temperature calibration values. */
        ret = regmap_bulk_read(data->regmap, BMP280_REG_COMP_TEMP_START,
                               t_buf, BMP280_COMP_TEMP_REG_COUNT);
        if (ret < 0) {
                dev_err(data->dev,
                        "failed to read temperature calibration parameters\n");
                return ret;
        }

        /* Toss the temperature calibration data into the entropy pool */
        add_device_randomness(t_buf, sizeof(t_buf));

        calib->T1 = le16_to_cpu(t_buf[T1]);
        calib->T2 = le16_to_cpu(t_buf[T2]);
        calib->T3 = le16_to_cpu(t_buf[T3]);

        /* Read pressure calibration values. */
        ret = regmap_bulk_read(data->regmap, BMP280_REG_COMP_PRESS_START,
                               p_buf, BMP280_COMP_PRESS_REG_COUNT);
        if (ret < 0) {
                dev_err(data->dev,
                        "failed to read pressure calibration parameters\n");
                return ret;
        }

        /* Toss the pressure calibration data into the entropy pool */
        add_device_randomness(p_buf, sizeof(p_buf));

        calib->P1 = le16_to_cpu(p_buf[P1]);
        calib->P2 = le16_to_cpu(p_buf[P2]);
        calib->P3 = le16_to_cpu(p_buf[P3]);
        calib->P4 = le16_to_cpu(p_buf[P4]);
        calib->P5 = le16_to_cpu(p_buf[P5]);
        calib->P6 = le16_to_cpu(p_buf[P6]);
        calib->P7 = le16_to_cpu(p_buf[P7]);
        calib->P8 = le16_to_cpu(p_buf[P8]);
        calib->P9 = le16_to_cpu(p_buf[P9]);

        /*
         * Read humidity calibration values.
         * Due to some odd register addressing we cannot just
         * do a big bulk read. Instead, we have to read each Hx
         * value separately and sometimes do some bit shifting...
         * Humidity data is only available on BME280.
         */
        if (chip != BME280_CHIP_ID)
                return 0;

        ret = regmap_read(data->regmap, BMP280_REG_COMP_H1, &tmp);
        if (ret < 0) {
                dev_err(dev, "failed to read H1 comp value\n");
                return ret;
        }
        calib->H1 = tmp;

        ret = regmap_bulk_read(data->regmap, BMP280_REG_COMP_H2, &l16, 2);
        if (ret < 0) {
                dev_err(dev, "failed to read H2 comp value\n");
                return ret;
        }
        calib->H2 = sign_extend32(le16_to_cpu(l16), 15);

        ret = regmap_read(data->regmap, BMP280_REG_COMP_H3, &tmp);
        if (ret < 0) {
                dev_err(dev, "failed to read H3 comp value\n");
                return ret;
        }
        calib->H3 = tmp;

        ret = regmap_bulk_read(data->regmap, BMP280_REG_COMP_H4, &b16, 2);
        if (ret < 0) {
                dev_err(dev, "failed to read H4 comp value\n");
                return ret;
        }
        calib->H4 = sign_extend32(((be16_to_cpu(b16) >> 4) & 0xff0) |
                                  (be16_to_cpu(b16) & 0xf), 11);

        ret = regmap_bulk_read(data->regmap, BMP280_REG_COMP_H5, &l16, 2);
        if (ret < 0) {
                dev_err(dev, "failed to read H5 comp value\n");
                return ret;
        }
        calib->H5 = sign_extend32(((le16_to_cpu(l16) >> 4) & 0xfff), 11);

        ret = regmap_read(data->regmap, BMP280_REG_COMP_H6, &tmp);
        if (ret < 0) {
                dev_err(dev, "failed to read H6 comp value\n");
                return ret;
        }
        calib->H6 = sign_extend32(tmp, 7);

        return 0;
}
/*
 * Returns humidity in percent, resolution is 0.01 percent. Output value of
 * "47445" represents 47445/1024 = 46.333 %RH.
 *
 * Taken from BME280 datasheet, Section 4.2.3, "Compensation formula".
 */
static u32 bmp280_compensate_humidity(struct bmp280_data *data,
                                      s32 adc_humidity)
{
        s32 var;
        struct bmp280_calib *calib = &data->calib.bmp280;

        var = ((s32)data->t_fine) - (s32)76800;
        var = ((((adc_humidity << 14) - (calib->H4 << 20) - (calib->H5 * var))
                + (s32)16384) >> 15) * (((((((var * calib->H6) >> 10)
                * (((var * (s32)calib->H3) >> 11) + (s32)32768)) >> 10)
                + (s32)2097152) * calib->H2 + 8192) >> 14);
        var -= ((((var >> 15) * (var >> 15)) >> 7) * (s32)calib->H1) >> 4;

        var = clamp_val(var, 0, 419430400);

        return var >> 12;
};

/*
 * Returns temperature in DegC, resolution is 0.01 DegC.  Output value of
 * "5123" equals 51.23 DegC.  t_fine carries fine temperature as global
 * value.
 *
 * Taken from datasheet, Section 3.11.3, "Compensation formula".
 */
static s32 bmp280_compensate_temp(struct bmp280_data *data,
                                  s32 adc_temp)
{
        s32 var1, var2;
        struct bmp280_calib *calib = &data->calib.bmp280;

        var1 = (((adc_temp >> 3) - ((s32)calib->T1 << 1)) *
                ((s32)calib->T2)) >> 11;
        var2 = (((((adc_temp >> 4) - ((s32)calib->T1)) *
                  ((adc_temp >> 4) - ((s32)calib->T1))) >> 12) *
                ((s32)calib->T3)) >> 14;
        data->t_fine = var1 + var2;

        return (data->t_fine * 5 + 128) >> 8;
}

/*
 * Returns pressure in Pa as unsigned 32 bit integer in Q24.8 format (24
 * integer bits and 8 fractional bits).  Output value of "24674867"
 * represents 24674867/256 = 96386.2 Pa = 963.862 hPa
 *
 * Taken from datasheet, Section 3.11.3, "Compensation formula".
 */
static u32 bmp280_compensate_press(struct bmp280_data *data,
                                   s32 adc_press)
{
        s64 var1, var2, p;
        struct bmp280_calib *calib = &data->calib.bmp280;

        var1 = ((s64)data->t_fine) - 128000;
        var2 = var1 * var1 * (s64)calib->P6;
        var2 += (var1 * (s64)calib->P5) << 17;
        var2 += ((s64)calib->P4) << 35;
        var1 = ((var1 * var1 * (s64)calib->P3) >> 8) +
                ((var1 * (s64)calib->P2) << 12);
        var1 = ((((s64)1) << 47) + var1) * ((s64)calib->P1) >> 33;

        if (var1 == 0)
                return 0;

        p = ((((s64)1048576 - adc_press) << 31) - var2) * 3125;
        p = div64_s64(p, var1);
        var1 = (((s64)calib->P9) * (p >> 13) * (p >> 13)) >> 25;
        var2 = ((s64)(calib->P8) * p) >> 19;
        p = ((p + var1 + var2) >> 8) + (((s64)calib->P7) << 4);

        return (u32)p;
}

static int bmp280_read_temp(struct bmp280_data *data,
                            int *val)
{
        int ret;
        __be32 tmp = 0;
        s32 adc_temp, comp_temp;

        ret = regmap_bulk_read(data->regmap, BMP280_REG_TEMP_MSB, &tmp, 3);
        if (ret < 0) {
                dev_err(data->dev, "failed to read temperature\n");
                return ret;
        }

        adc_temp = be32_to_cpu(tmp) >> 12;
        if (adc_temp == BMP280_TEMP_SKIPPED) {
                /* reading was skipped */
                dev_err(data->dev, "reading temperature skipped\n");
                return -EIO;
        }
        comp_temp = bmp280_compensate_temp(data, adc_temp);

        /*
         * val might be NULL if we're called by the read_press routine,
         * who only cares about the carry over t_fine value.
         */
        if (val) {
                *val = comp_temp * 10;
                return IIO_VAL_INT;
        }

        return 0;
}

static int bmp280_read_press(struct bmp280_data *data,
                             int *val, int *val2)
{
        int ret;
        __be32 tmp = 0;
        s32 adc_press;
        u32 comp_press;

        /* Read and compensate temperature so we get a reading of t_fine. */
        ret = bmp280_read_temp(data, NULL);
        if (ret < 0)
                return ret;

        ret = regmap_bulk_read(data->regmap, BMP280_REG_PRESS_MSB, &tmp, 3);
        if (ret < 0) {
                dev_err(data->dev, "failed to read pressure\n");
                return ret;
        }

        adc_press = be32_to_cpu(tmp) >> 12;
        if (adc_press == BMP280_PRESS_SKIPPED) {
                /* reading was skipped */
                dev_err(data->dev, "reading pressure skipped\n");
                return -EIO;
        }
        comp_press = bmp280_compensate_press(data, adc_press);

        *val = comp_press;
        *val2 = 256000;

        return IIO_VAL_FRACTIONAL;
}

static int bmp280_read_humid(struct bmp280_data *data, int *val, int *val2)
{
        __be16 tmp;
        int ret;
        s32 adc_humidity;
        u32 comp_humidity;

        /* Read and compensate temperature so we get a reading of t_fine. */
        ret = bmp280_read_temp(data, NULL);
        if (ret < 0)
                return ret;

        ret = regmap_bulk_read(data->regmap, BMP280_REG_HUMIDITY_MSB, &tmp, 2);
        if (ret < 0) {
                dev_err(data->dev, "failed to read humidity\n");
                return ret;
        }

        adc_humidity = be16_to_cpu(tmp);
        if (adc_humidity == BMP280_HUMIDITY_SKIPPED) {
                /* reading was skipped */
                dev_err(data->dev, "reading humidity skipped\n");
                return -EIO;
        }
        comp_humidity = bmp280_compensate_humidity(data, adc_humidity);

        *val = comp_humidity * 1000 / 1024;

        return IIO_VAL_INT;
}

static int bmp280_read_raw(struct iio_dev *indio_dev,
                           struct iio_chan_spec const *chan,
                           int *val, int *val2, long mask)
{
        int ret;
        struct bmp280_data *data = iio_priv(indio_dev);

        pm_runtime_get_sync(data->dev);
        mutex_lock(&data->lock);

        switch (mask) {
        case IIO_CHAN_INFO_PROCESSED:
                switch (chan->type) {
                case IIO_HUMIDITYRELATIVE:
                        ret = data->chip_info->read_humid(data, val, val2);
                        break;
                case IIO_PRESSURE:
                        ret = data->chip_info->read_press(data, val, val2);
                        break;
                case IIO_TEMP:
                        ret = data->chip_info->read_temp(data, val);
                        break;
                default:
                        ret = -EINVAL;
                        break;
                }
                break;
        case IIO_CHAN_INFO_OVERSAMPLING_RATIO:
                switch (chan->type) {
                case IIO_HUMIDITYRELATIVE:
                        *val = 1 << data->oversampling_humid;
                        ret = IIO_VAL_INT;
                        break;
                case IIO_PRESSURE:
                        *val = 1 << data->oversampling_press;
                        ret = IIO_VAL_INT;
                        break;
                case IIO_TEMP:
                        *val = 1 << data->oversampling_temp;
                        ret = IIO_VAL_INT;
                        break;
                default:
                        ret = -EINVAL;
                        break;
                }
                break;
        default:
                ret = -EINVAL;
                break;
        }

        mutex_unlock(&data->lock);
        pm_runtime_mark_last_busy(data->dev);
        pm_runtime_put_autosuspend(data->dev);

        return ret;
}

static int bmp280_write_oversampling_ratio_humid(struct bmp280_data *data,
                                               int val)
{
        int i;
        const int *avail = data->chip_info->oversampling_humid_avail;
        const int n = data->chip_info->num_oversampling_humid_avail;

        for (i = 0; i < n; i++) {
                if (avail[i] == val) {
                        data->oversampling_humid = ilog2(val);

                        return data->chip_info->chip_config(data);
                }
        }
        return -EINVAL;
}

static int bmp280_write_oversampling_ratio_temp(struct bmp280_data *data,
                                               int val)
{
        int i;
        const int *avail = data->chip_info->oversampling_temp_avail;
        const int n = data->chip_info->num_oversampling_temp_avail;

        for (i = 0; i < n; i++) {
                if (avail[i] == val) {
                        data->oversampling_temp = ilog2(val);

                        return data->chip_info->chip_config(data);
                }
        }
        return -EINVAL;
}

static int bmp280_write_oversampling_ratio_press(struct bmp280_data *data,
                                               int val)
{
        int i;
        const int *avail = data->chip_info->oversampling_press_avail;
        const int n = data->chip_info->num_oversampling_press_avail;

        for (i = 0; i < n; i++) {
                if (avail[i] == val) {
                        data->oversampling_press = ilog2(val);

                        return data->chip_info->chip_config(data);
                }
        }
        return -EINVAL;
}

static int bmp280_write_raw(struct iio_dev *indio_dev,
                            struct iio_chan_spec const *chan,
                            int val, int val2, long mask)
{
        int ret = 0;
        struct bmp280_data *data = iio_priv(indio_dev);

        switch (mask) {
        case IIO_CHAN_INFO_OVERSAMPLING_RATIO:
                pm_runtime_get_sync(data->dev);
                mutex_lock(&data->lock);
                switch (chan->type) {
                case IIO_HUMIDITYRELATIVE:
                        ret = bmp280_write_oversampling_ratio_humid(data, val);
                        break;
                case IIO_PRESSURE:
                        ret = bmp280_write_oversampling_ratio_press(data, val);
                        break;
                case IIO_TEMP:
                        ret = bmp280_write_oversampling_ratio_temp(data, val);
                        break;
                default:
                        ret = -EINVAL;
                        break;
                }
                mutex_unlock(&data->lock);
                pm_runtime_mark_last_busy(data->dev);
                pm_runtime_put_autosuspend(data->dev);
                break;
        default:
                return -EINVAL;
        }

        return ret;
}

static int bmp280_read_avail(struct iio_dev *indio_dev,
                             struct iio_chan_spec const *chan,
                             const int **vals, int *type, int *length,
                             long mask)
{
        struct bmp280_data *data = iio_priv(indio_dev);

        switch (mask) {
        case IIO_CHAN_INFO_OVERSAMPLING_RATIO:
                switch (chan->type) {
                case IIO_PRESSURE:
                        *vals = data->chip_info->oversampling_press_avail;
                        *length = data->chip_info->num_oversampling_press_avail;
                        break;
                case IIO_TEMP:
                        *vals = data->chip_info->oversampling_temp_avail;
                        *length = data->chip_info->num_oversampling_temp_avail;
                        break;
                default:
                        return -EINVAL;
                }
                *type = IIO_VAL_INT;
                return IIO_AVAIL_LIST;
        default:
                return -EINVAL;
        }
}

static const struct iio_info bmp280_info = {
        .read_raw = &bmp280_read_raw,
        .read_avail = &bmp280_read_avail,
        .write_raw = &bmp280_write_raw,
};

static int bmp280_chip_config(struct bmp280_data *data)
{
        int ret;
        u8 osrs = BMP280_OSRS_TEMP_X(data->oversampling_temp + 1) |
                  BMP280_OSRS_PRESS_X(data->oversampling_press + 1);

        ret = regmap_write_bits(data->regmap, BMP280_REG_CTRL_MEAS,
                                 BMP280_OSRS_TEMP_MASK |
                                 BMP280_OSRS_PRESS_MASK |
                                 BMP280_MODE_MASK,
                                 osrs | BMP280_MODE_NORMAL);
        if (ret < 0) {
                dev_err(data->dev,
                        "failed to write ctrl_meas register\n");
                return ret;
        }

        ret = regmap_update_bits(data->regmap, BMP280_REG_CONFIG,
                                 BMP280_FILTER_MASK,
                                 BMP280_FILTER_4X);
        if (ret < 0) {
                dev_err(data->dev,
                        "failed to write config register\n");
                return ret;
        }

        return ret;
}

static const int bmp280_oversampling_avail[] = { 1, 2, 4, 8, 16 };

static const struct bmp280_chip_info bmp280_chip_info = {
        .oversampling_temp_avail = bmp280_oversampling_avail,
        .num_oversampling_temp_avail = ARRAY_SIZE(bmp280_oversampling_avail),

        .oversampling_press_avail = bmp280_oversampling_avail,
        .num_oversampling_press_avail = ARRAY_SIZE(bmp280_oversampling_avail),

        .chip_config = bmp280_chip_config,
        .read_temp = bmp280_read_temp,
        .read_press = bmp280_read_press,
};

static int bme280_chip_config(struct bmp280_data *data)
{
        int ret;
        u8 osrs = BMP280_OSRS_HUMIDITIY_X(data->oversampling_humid + 1);

        /*
         * Oversampling of humidity must be set before oversampling of
         * temperature/pressure is set to become effective.
         */
        ret = regmap_update_bits(data->regmap, BMP280_REG_CTRL_HUMIDITY,
                                  BMP280_OSRS_HUMIDITY_MASK, osrs);

        if (ret < 0)
                return ret;

        return bmp280_chip_config(data);
}

static const struct bmp280_chip_info bme280_chip_info = {
        .oversampling_temp_avail = bmp280_oversampling_avail,
        .num_oversampling_temp_avail = ARRAY_SIZE(bmp280_oversampling_avail),

        .oversampling_press_avail = bmp280_oversampling_avail,
        .num_oversampling_press_avail = ARRAY_SIZE(bmp280_oversampling_avail),

        .oversampling_humid_avail = bmp280_oversampling_avail,
        .num_oversampling_humid_avail = ARRAY_SIZE(bmp280_oversampling_avail),

        .chip_config = bme280_chip_config,
        .read_temp = bmp280_read_temp,
        .read_press = bmp280_read_press,
        .read_humid = bmp280_read_humid,
};

static int bmp180_measure(struct bmp280_data *data, u8 ctrl_meas)
{
        int ret;
        const int conversion_time_max[] = { 4500, 7500, 13500, 25500 };
        unsigned int delay_us;
        unsigned int ctrl;

        if (data->use_eoc)
                reinit_completion(&data->done);

        ret = regmap_write(data->regmap, BMP280_REG_CTRL_MEAS, ctrl_meas);
        if (ret)
                return ret;

        if (data->use_eoc) {
                /*
                 * If we have a completion interrupt, use it, wait up to
                 * 100ms. The longest conversion time listed is 76.5 ms for
                 * advanced resolution mode.
                 */
                ret = wait_for_completion_timeout(&data->done,
                                                  1 + msecs_to_jiffies(100));
                if (!ret)
                        dev_err(data->dev, "timeout waiting for completion\n");
        } else {
                if (ctrl_meas == BMP180_MEAS_TEMP)
                        delay_us = 4500;
                else
                        delay_us =
                                conversion_time_max[data->oversampling_press];

                usleep_range(delay_us, delay_us + 1000);
        }

        ret = regmap_read(data->regmap, BMP280_REG_CTRL_MEAS, &ctrl);
        if (ret)
                return ret;

        /* The value of this bit reset to "0" after conversion is complete */
        if (ctrl & BMP180_MEAS_SCO)
                return -EIO;

        return 0;
}

static int bmp180_read_adc_temp(struct bmp280_data *data, int *val)
{
        __be16 tmp;
        int ret;

        ret = bmp180_measure(data, BMP180_MEAS_TEMP);
        if (ret)
                return ret;

        ret = regmap_bulk_read(data->regmap, BMP180_REG_OUT_MSB, &tmp, 2);
        if (ret)
                return ret;

        *val = be16_to_cpu(tmp);

        return 0;
}

static int bmp180_read_calib(struct bmp280_data *data,
                             struct bmp180_calib *calib)
{
        int ret;
        int i;
        __be16 buf[BMP180_REG_CALIB_COUNT / 2];

        ret = regmap_bulk_read(data->regmap, BMP180_REG_CALIB_START, buf,
                               sizeof(buf));

        if (ret < 0)
                return ret;

        /* None of the words has the value 0 or 0xFFFF */
        for (i = 0; i < ARRAY_SIZE(buf); i++) {
                if (buf[i] == cpu_to_be16(0) || buf[i] == cpu_to_be16(0xffff))
                        return -EIO;
        }

        /* Toss the calibration data into the entropy pool */
        add_device_randomness(buf, sizeof(buf));

        calib->AC1 = be16_to_cpu(buf[AC1]);
        calib->AC2 = be16_to_cpu(buf[AC2]);
        calib->AC3 = be16_to_cpu(buf[AC3]);
        calib->AC4 = be16_to_cpu(buf[AC4]);
        calib->AC5 = be16_to_cpu(buf[AC5]);
        calib->AC6 = be16_to_cpu(buf[AC6]);
        calib->B1 = be16_to_cpu(buf[B1]);
        calib->B2 = be16_to_cpu(buf[B2]);
        calib->MB = be16_to_cpu(buf[MB]);
        calib->MC = be16_to_cpu(buf[MC]);
        calib->MD = be16_to_cpu(buf[MD]);

        return 0;
}

/*
 * Returns temperature in DegC, resolution is 0.1 DegC.
 * t_fine carries fine temperature as global value.
 *
 * Taken from datasheet, Section 3.5, "Calculating pressure and temperature".
 */
static s32 bmp180_compensate_temp(struct bmp280_data *data, s32 adc_temp)
{
        s32 x1, x2;
        struct bmp180_calib *calib = &data->calib.bmp180;

        x1 = ((adc_temp - calib->AC6) * calib->AC5) >> 15;
        x2 = (calib->MC << 11) / (x1 + calib->MD);
        data->t_fine = x1 + x2;

        return (data->t_fine + 8) >> 4;
}

static int bmp180_read_temp(struct bmp280_data *data, int *val)
{
        int ret;
        s32 adc_temp, comp_temp;

        ret = bmp180_read_adc_temp(data, &adc_temp);
        if (ret)
                return ret;

        comp_temp = bmp180_compensate_temp(data, adc_temp);

        /*
         * val might be NULL if we're called by the read_press routine,
         * who only cares about the carry over t_fine value.
         */
        if (val) {
                *val = comp_temp * 100;
                return IIO_VAL_INT;
        }

        return 0;
}

static int bmp180_read_adc_press(struct bmp280_data *data, int *val)
{
        int ret;
        __be32 tmp = 0;
        u8 oss = data->oversampling_press;

        ret = bmp180_measure(data, BMP180_MEAS_PRESS_X(oss));
        if (ret)
                return ret;

        ret = regmap_bulk_read(data->regmap, BMP180_REG_OUT_MSB, &tmp, 3);
        if (ret)
                return ret;

        *val = (be32_to_cpu(tmp) >> 8) >> (8 - oss);

        return 0;
}

/*
 * Returns pressure in Pa, resolution is 1 Pa.
 *
 * Taken from datasheet, Section 3.5, "Calculating pressure and temperature".
 */
static u32 bmp180_compensate_press(struct bmp280_data *data, s32 adc_press)
{
        s32 x1, x2, x3, p;
        s32 b3, b6;
        u32 b4, b7;
        s32 oss = data->oversampling_press;
        struct bmp180_calib *calib = &data->calib.bmp180;

        b6 = data->t_fine - 4000;
        x1 = (calib->B2 * (b6 * b6 >> 12)) >> 11;
        x2 = calib->AC2 * b6 >> 11;
        x3 = x1 + x2;
        b3 = ((((s32)calib->AC1 * 4 + x3) << oss) + 2) / 4;
        x1 = calib->AC3 * b6 >> 13;
        x2 = (calib->B1 * ((b6 * b6) >> 12)) >> 16;
        x3 = (x1 + x2 + 2) >> 2;
        b4 = calib->AC4 * (u32)(x3 + 32768) >> 15;
        b7 = ((u32)adc_press - b3) * (50000 >> oss);
        if (b7 < 0x80000000)
                p = (b7 * 2) / b4;
        else
                p = (b7 / b4) * 2;

        x1 = (p >> 8) * (p >> 8);
        x1 = (x1 * 3038) >> 16;
        x2 = (-7357 * p) >> 16;

        return p + ((x1 + x2 + 3791) >> 4);
}

static int bmp180_read_press(struct bmp280_data *data,
                             int *val, int *val2)
{
        int ret;
        s32 adc_press;
        u32 comp_press;

        /* Read and compensate temperature so we get a reading of t_fine. */
        ret = bmp180_read_temp(data, NULL);
        if (ret)
                return ret;

        ret = bmp180_read_adc_press(data, &adc_press);
        if (ret)
                return ret;

        comp_press = bmp180_compensate_press(data, adc_press);

        *val = comp_press;
        *val2 = 1000;

        return IIO_VAL_FRACTIONAL;
}

static int bmp180_chip_config(struct bmp280_data *data)
{
        return 0;
}

static const int bmp180_oversampling_temp_avail[] = { 1 };
static const int bmp180_oversampling_press_avail[] = { 1, 2, 4, 8 };

static const struct bmp280_chip_info bmp180_chip_info = {
        .oversampling_temp_avail = bmp180_oversampling_temp_avail,
        .num_oversampling_temp_avail =
                ARRAY_SIZE(bmp180_oversampling_temp_avail),

        .oversampling_press_avail = bmp180_oversampling_press_avail,
        .num_oversampling_press_avail =
                ARRAY_SIZE(bmp180_oversampling_press_avail),

        .chip_config = bmp180_chip_config,
        .read_temp = bmp180_read_temp,
        .read_press = bmp180_read_press,
};

static irqreturn_t bmp085_eoc_irq(int irq, void *d)
{
        struct bmp280_data *data = d;

        complete(&data->done);

        return IRQ_HANDLED;
}

static int bmp085_fetch_eoc_irq(struct device *dev,
                                const char *name,
                                int irq,
                                struct bmp280_data *data)
{
        unsigned long irq_trig;
        int ret;

        irq_trig = irqd_get_trigger_type(irq_get_irq_data(irq));
        if (irq_trig != IRQF_TRIGGER_RISING) {
                dev_err(dev, "non-rising trigger given for EOC interrupt, trying to enforce it\n");
                irq_trig = IRQF_TRIGGER_RISING;
        }

        init_completion(&data->done);

        ret = devm_request_threaded_irq(dev,
                        irq,
                        bmp085_eoc_irq,
                        NULL,
                        irq_trig,
                        name,
                        data);
        if (ret) {
                /* Bail out without IRQ but keep the driver in place */
                dev_err(dev, "unable to request DRDY IRQ\n");
                return 0;
        }

        data->use_eoc = true;
        return 0;
}

static void bmp280_pm_disable(void *data)
{
        struct device *dev = data;

        pm_runtime_get_sync(dev);
        pm_runtime_put_noidle(dev);
        pm_runtime_disable(dev);
}

static void bmp280_regulators_disable(void *data)
{
        struct regulator_bulk_data *supplies = data;

        regulator_bulk_disable(BMP280_NUM_SUPPLIES, supplies);
}

int bmp280_common_probe(struct device *dev,
                        struct regmap *regmap,
                        unsigned int chip,
                        const char *name,
                        int irq)
{
        int ret;
        struct iio_dev *indio_dev;
        struct bmp280_data *data;
        unsigned int chip_id;
        struct gpio_desc *gpiod;

        indio_dev = devm_iio_device_alloc(dev, sizeof(*data));
        if (!indio_dev)

                return -ENOMEM;

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

        indio_dev->name = name;
        indio_dev->channels = bmp280_channels;
        indio_dev->info = &bmp280_info;
        indio_dev->modes = INDIO_DIRECT_MODE;

        switch (chip) {
        case BMP180_CHIP_ID:
                indio_dev->num_channels = 2;
                data->chip_info = &bmp180_chip_info;
                data->oversampling_press = ilog2(8);
                data->oversampling_temp = ilog2(1);
                data->start_up_time = 10000;
                break;
        case BMP280_CHIP_ID:
                indio_dev->num_channels = 2;
                data->chip_info = &bmp280_chip_info;
                data->oversampling_press = ilog2(16);
                data->oversampling_temp = ilog2(2);
                data->start_up_time = 2000;
                break;
        case BME280_CHIP_ID:
                indio_dev->num_channels = 3;
                data->chip_info = &bme280_chip_info;
                data->oversampling_press = ilog2(16);
                data->oversampling_humid = ilog2(16);
                data->oversampling_temp = ilog2(2);
                data->start_up_time = 2000;
                break;
        default:
                return -EINVAL;
        }

        /* Bring up regulators */
        regulator_bulk_set_supply_names(data->supplies,
                                        bmp280_supply_names,
                                        BMP280_NUM_SUPPLIES);

        ret = devm_regulator_bulk_get(dev,
                                      BMP280_NUM_SUPPLIES, data->supplies);
        if (ret) {
                dev_err(dev, "failed to get regulators\n");
                return ret;
        }

        ret = regulator_bulk_enable(BMP280_NUM_SUPPLIES, data->supplies);
        if (ret) {
                dev_err(dev, "failed to enable regulators\n");
                return ret;
        }

        ret = devm_add_action_or_reset(dev, bmp280_regulators_disable,
                                       data->supplies);
        if (ret)
                return ret;

        /* Wait to make sure we started up properly */
        usleep_range(data->start_up_time, data->start_up_time + 100);

        /* Bring chip out of reset if there is an assigned GPIO line */
        gpiod = devm_gpiod_get_optional(dev, "reset", GPIOD_OUT_HIGH);
        /* Deassert the signal */
        if (gpiod) {
                dev_info(dev, "release reset\n");
                gpiod_set_value(gpiod, 0);
        }

        data->regmap = regmap;
        ret = regmap_read(regmap, BMP280_REG_ID, &chip_id);
        if (ret < 0)
                return ret;
        if (chip_id != chip) {
                dev_err(dev, "bad chip id: expected %x got %x\n",
                        chip, chip_id);
                return -EINVAL;
        }

        ret = data->chip_info->chip_config(data);
        if (ret < 0)
                return ret;

        dev_set_drvdata(dev, indio_dev);

        /*
         * Some chips have calibration parameters "programmed into the devices'
         * non-volatile memory during production". Let's read them out at probe
         * time once. They will not change.
         */
        if (chip_id  == BMP180_CHIP_ID) {
                ret = bmp180_read_calib(data, &data->calib.bmp180);
                if (ret < 0) {
                        dev_err(data->dev,
                                "failed to read calibration coefficients\n");
                        return ret;
                }
        } else if (chip_id == BMP280_CHIP_ID || chip_id == BME280_CHIP_ID) {
                ret = bmp280_read_calib(data, &data->calib.bmp280, chip_id);
                if (ret < 0) {
                        dev_err(data->dev,
                                "failed to read calibration coefficients\n");
                        return ret;
                }
        }

        /*
         * Attempt to grab an optional EOC IRQ - only the BMP085 has this
         * however as it happens, the BMP085 shares the chip ID of BMP180
         * so we look for an IRQ if we have that.
         */
        if (irq > 0 || (chip_id  == BMP180_CHIP_ID)) {
                ret = bmp085_fetch_eoc_irq(dev, name, irq, data);
                if (ret)
                        return ret;
        }

        /* Enable runtime PM */
        pm_runtime_get_noresume(dev);
        pm_runtime_set_active(dev);
        pm_runtime_enable(dev);
        /*
         * Set autosuspend to two orders of magnitude larger than the
         * start-up time.
         */
        pm_runtime_set_autosuspend_delay(dev, data->start_up_time / 10);
        pm_runtime_use_autosuspend(dev);
        pm_runtime_put(dev);

        ret = devm_add_action_or_reset(dev, bmp280_pm_disable, dev);
        if (ret)
                return ret;

        return devm_iio_device_register(dev, indio_dev);
}
EXPORT_SYMBOL(bmp280_common_probe);

#ifdef CONFIG_PM
static int bmp280_runtime_suspend(struct device *dev)
{
        struct iio_dev *indio_dev = dev_get_drvdata(dev);
        struct bmp280_data *data = iio_priv(indio_dev);

        return regulator_bulk_disable(BMP280_NUM_SUPPLIES, data->supplies);
}

static int bmp280_runtime_resume(struct device *dev)
{
        struct iio_dev *indio_dev = dev_get_drvdata(dev);
        struct bmp280_data *data = iio_priv(indio_dev);
        int ret;

        ret = regulator_bulk_enable(BMP280_NUM_SUPPLIES, data->supplies);
        if (ret)
                return ret;
        usleep_range(data->start_up_time, data->start_up_time + 100);
        return data->chip_info->chip_config(data);
}
#endif /* CONFIG_PM */

const struct dev_pm_ops bmp280_dev_pm_ops = {
        SET_SYSTEM_SLEEP_PM_OPS(pm_runtime_force_suspend,
                                pm_runtime_force_resume)
        SET_RUNTIME_PM_OPS(bmp280_runtime_suspend,
                           bmp280_runtime_resume, NULL)
};
EXPORT_SYMBOL(bmp280_dev_pm_ops);

MODULE_AUTHOR("Vlad Dogaru <vlad.dogaru@intel.com>");
MODULE_DESCRIPTION("Driver for Bosch Sensortec BMP180/BMP280 pressure and temperature sensor");
MODULE_LICENSE("GPL v2");