root/drivers/iio/cdc/ad7746.c
// SPDX-License-Identifier: GPL-2.0
/*
 * AD7746 capacitive sensor driver supporting AD7745, AD7746 and AD7747
 *
 * Copyright 2011 Analog Devices Inc.
 */

#include <linux/bitfield.h>
#include <linux/delay.h>
#include <linux/device.h>
#include <linux/i2c.h>
#include <linux/interrupt.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/stat.h>
#include <linux/sysfs.h>

#include <linux/unaligned.h>

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

/* AD7746 Register Definition */

#define AD7746_REG_STATUS               0
#define AD7746_REG_CAP_DATA_HIGH        1
#define AD7746_REG_VT_DATA_HIGH         4
#define AD7746_REG_CAP_SETUP            7
#define AD7746_REG_VT_SETUP             8
#define AD7746_REG_EXC_SETUP            9
#define AD7746_REG_CFG                  10
#define AD7746_REG_CAPDACA              11
#define AD7746_REG_CAPDACB              12
#define AD7746_REG_CAP_OFFH             13
#define AD7746_REG_CAP_GAINH            15
#define AD7746_REG_VOLT_GAINH           17

/* Status Register Bit Designations (AD7746_REG_STATUS) */
#define AD7746_STATUS_EXCERR            BIT(3)
#define AD7746_STATUS_RDY               BIT(2)
#define AD7746_STATUS_RDYVT             BIT(1)
#define AD7746_STATUS_RDYCAP            BIT(0)

/* Capacitive Channel Setup Register Bit Designations (AD7746_REG_CAP_SETUP) */
#define AD7746_CAPSETUP_CAPEN           BIT(7)
#define AD7746_CAPSETUP_CIN2            BIT(6) /* AD7746 only */
#define AD7746_CAPSETUP_CAPDIFF         BIT(5)
#define AD7746_CAPSETUP_CACHOP          BIT(0)

/* Voltage/Temperature Setup Register Bit Designations (AD7746_REG_VT_SETUP) */
#define AD7746_VTSETUP_VTEN             BIT(7)
#define AD7746_VTSETUP_VTMD_MASK        GENMASK(6, 5)
#define AD7746_VTSETUP_VTMD_INT_TEMP    0
#define AD7746_VTSETUP_VTMD_EXT_TEMP    1
#define AD7746_VTSETUP_VTMD_VDD_MON     2
#define AD7746_VTSETUP_VTMD_EXT_VIN     3
#define AD7746_VTSETUP_EXTREF           BIT(4)
#define AD7746_VTSETUP_VTSHORT          BIT(1)
#define AD7746_VTSETUP_VTCHOP           BIT(0)

/* Excitation Setup Register Bit Designations (AD7746_REG_EXC_SETUP) */
#define AD7746_EXCSETUP_CLKCTRL         BIT(7)
#define AD7746_EXCSETUP_EXCON           BIT(6)
#define AD7746_EXCSETUP_EXCB            BIT(5)
#define AD7746_EXCSETUP_NEXCB           BIT(4)
#define AD7746_EXCSETUP_EXCA            BIT(3)
#define AD7746_EXCSETUP_NEXCA           BIT(2)
#define AD7746_EXCSETUP_EXCLVL_MASK     GENMASK(1, 0)

/* Config Register Bit Designations (AD7746_REG_CFG) */
#define AD7746_CONF_VTFS_MASK           GENMASK(7, 6)
#define AD7746_CONF_CAPFS_MASK          GENMASK(5, 3)
#define AD7746_CONF_MODE_MASK           GENMASK(2, 0)
#define AD7746_CONF_MODE_IDLE           0
#define AD7746_CONF_MODE_CONT_CONV      1
#define AD7746_CONF_MODE_SINGLE_CONV    2
#define AD7746_CONF_MODE_PWRDN          3
#define AD7746_CONF_MODE_OFFS_CAL       5
#define AD7746_CONF_MODE_GAIN_CAL       6

/* CAPDAC Register Bit Designations (AD7746_REG_CAPDACx) */
#define AD7746_CAPDAC_DACEN             BIT(7)
#define AD7746_CAPDAC_DACP_MASK         GENMASK(6, 0)

struct ad7746_chip_info {
        struct i2c_client *client;
        struct mutex lock; /* protect sensor state */
        /*
         * Capacitive channel digital filter setup;
         * conversion time/update rate setup per channel
         */
        u8      config;
        u8      cap_setup;
        u8      vt_setup;
        u8      capdac[2][2];
        s8      capdac_set;
};

enum ad7746_chan {
        VIN,
        VIN_VDD,
        TEMP_INT,
        TEMP_EXT,
        CIN1,
        CIN1_DIFF,
        CIN2,
        CIN2_DIFF,
};

struct ad7746_chan_info {
        u8 addr;
        union {
                u8 vtmd;
                struct { /* CAP SETUP fields */
                        unsigned int cin2 : 1;
                        unsigned int capdiff : 1;
                };
        };
};

static const struct ad7746_chan_info ad7746_chan_info[] = {
        [VIN] = {
                .addr = AD7746_REG_VT_DATA_HIGH,
                .vtmd = AD7746_VTSETUP_VTMD_EXT_VIN,
        },
        [VIN_VDD] = {
                .addr = AD7746_REG_VT_DATA_HIGH,
                .vtmd = AD7746_VTSETUP_VTMD_VDD_MON,
        },
        [TEMP_INT] = {
                .addr = AD7746_REG_VT_DATA_HIGH,
                .vtmd = AD7746_VTSETUP_VTMD_INT_TEMP,
        },
        [TEMP_EXT] = {
                .addr = AD7746_REG_VT_DATA_HIGH,
                .vtmd = AD7746_VTSETUP_VTMD_EXT_TEMP,
        },
        [CIN1] = {
                .addr = AD7746_REG_CAP_DATA_HIGH,
        },
        [CIN1_DIFF] = {
                .addr =  AD7746_REG_CAP_DATA_HIGH,
                .capdiff = 1,
        },
        [CIN2] = {
                .addr = AD7746_REG_CAP_DATA_HIGH,
                .cin2 = 1,
        },
        [CIN2_DIFF] = {
                .addr = AD7746_REG_CAP_DATA_HIGH,
                .cin2 = 1,
                .capdiff = 1,
        },
};

static const struct iio_chan_spec ad7746_channels[] = {
        [VIN] = {
                .type = IIO_VOLTAGE,
                .indexed = 1,
                .channel = 0,
                .info_mask_separate = BIT(IIO_CHAN_INFO_RAW) | BIT(IIO_CHAN_INFO_SCALE),
                .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SAMP_FREQ),
                .info_mask_shared_by_type_available = BIT(IIO_CHAN_INFO_SAMP_FREQ),
                .address = VIN,
        },
        [VIN_VDD] = {
                .type = IIO_VOLTAGE,
                .indexed = 1,
                .channel = 1,
                .extend_name = "supply",
                .info_mask_separate = BIT(IIO_CHAN_INFO_RAW) | BIT(IIO_CHAN_INFO_SCALE),
                .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SAMP_FREQ),
                .info_mask_shared_by_type_available = BIT(IIO_CHAN_INFO_SAMP_FREQ),
                .address = VIN_VDD,
        },
        [TEMP_INT] = {
                .type = IIO_TEMP,
                .indexed = 1,
                .channel = 0,
                .info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
                .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE),
                .address = TEMP_INT,
        },
        [TEMP_EXT] = {
                .type = IIO_TEMP,
                .indexed = 1,
                .channel = 1,
                .info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
                .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE),
                .address = TEMP_EXT,
        },
        [CIN1] = {
                .type = IIO_CAPACITANCE,
                .indexed = 1,
                .channel = 0,
                .info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
                BIT(IIO_CHAN_INFO_CALIBSCALE) | BIT(IIO_CHAN_INFO_OFFSET),
                .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_CALIBBIAS) |
                BIT(IIO_CHAN_INFO_SCALE) | BIT(IIO_CHAN_INFO_SAMP_FREQ),
                .info_mask_shared_by_type_available = BIT(IIO_CHAN_INFO_SAMP_FREQ),
                .address = CIN1,
        },
        [CIN1_DIFF] = {
                .type = IIO_CAPACITANCE,
                .differential = 1,
                .indexed = 1,
                .channel = 0,
                .channel2 = 2,
                .info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
                BIT(IIO_CHAN_INFO_CALIBSCALE) | BIT(IIO_CHAN_INFO_ZEROPOINT),
                .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_CALIBBIAS) |
                BIT(IIO_CHAN_INFO_SCALE) | BIT(IIO_CHAN_INFO_SAMP_FREQ),
                .info_mask_shared_by_type_available = BIT(IIO_CHAN_INFO_SAMP_FREQ),
                .address = CIN1_DIFF,
        },
        [CIN2] = {
                .type = IIO_CAPACITANCE,
                .indexed = 1,
                .channel = 1,
                .info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
                BIT(IIO_CHAN_INFO_CALIBSCALE) | BIT(IIO_CHAN_INFO_OFFSET),
                .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_CALIBBIAS) |
                BIT(IIO_CHAN_INFO_SCALE) | BIT(IIO_CHAN_INFO_SAMP_FREQ),
                .info_mask_shared_by_type_available = BIT(IIO_CHAN_INFO_SAMP_FREQ),
                .address = CIN2,
        },
        [CIN2_DIFF] = {
                .type = IIO_CAPACITANCE,
                .differential = 1,
                .indexed = 1,
                .channel = 1,
                .channel2 = 3,
                .info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
                BIT(IIO_CHAN_INFO_CALIBSCALE) | BIT(IIO_CHAN_INFO_ZEROPOINT),
                .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_CALIBBIAS) |
                BIT(IIO_CHAN_INFO_SCALE) | BIT(IIO_CHAN_INFO_SAMP_FREQ),
                .info_mask_shared_by_type_available = BIT(IIO_CHAN_INFO_SAMP_FREQ),
                .address = CIN2_DIFF,
        }
};

/* Values are Update Rate (Hz), Conversion Time (ms) + 1*/
static const unsigned char ad7746_vt_filter_rate_table[][2] = {
        { 50, 20 + 1 }, { 31, 32 + 1 }, { 16, 62 + 1 }, { 8, 122 + 1 },
};

static const unsigned char ad7746_cap_filter_rate_table[][2] = {
        { 91, 11 + 1 }, { 84, 12 + 1 }, { 50, 20 + 1 }, { 26, 38 + 1 },
        { 16, 62 + 1 }, { 13, 77 + 1 }, { 11, 92 + 1 }, { 9, 110 + 1 },
};

static int ad7746_set_capdac(struct ad7746_chip_info *chip, int channel)
{
        int ret = i2c_smbus_write_byte_data(chip->client,
                                            AD7746_REG_CAPDACA,
                                            chip->capdac[channel][0]);
        if (ret < 0)
                return ret;

        return i2c_smbus_write_byte_data(chip->client,
                                          AD7746_REG_CAPDACB,
                                          chip->capdac[channel][1]);
}

static int ad7746_select_channel(struct iio_dev *indio_dev,
                                 struct iio_chan_spec const *chan)
{
        struct ad7746_chip_info *chip = iio_priv(indio_dev);
        u8 vt_setup, cap_setup;
        int ret, delay, idx;

        switch (chan->type) {
        case IIO_CAPACITANCE:
                cap_setup = FIELD_PREP(AD7746_CAPSETUP_CIN2,
                                       ad7746_chan_info[chan->address].cin2) |
                        FIELD_PREP(AD7746_CAPSETUP_CAPDIFF,
                                   ad7746_chan_info[chan->address].capdiff) |
                        FIELD_PREP(AD7746_CAPSETUP_CAPEN, 1);
                vt_setup = chip->vt_setup & ~AD7746_VTSETUP_VTEN;
                idx = FIELD_GET(AD7746_CONF_CAPFS_MASK, chip->config);
                delay = ad7746_cap_filter_rate_table[idx][1];

                ret = ad7746_set_capdac(chip, chan->channel);
                if (ret < 0)
                        return ret;

                chip->capdac_set = chan->channel;
                break;
        case IIO_VOLTAGE:
        case IIO_TEMP:
                vt_setup = FIELD_PREP(AD7746_VTSETUP_VTMD_MASK,
                                      ad7746_chan_info[chan->address].vtmd) |
                        FIELD_PREP(AD7746_VTSETUP_VTEN, 1);
                cap_setup = chip->cap_setup & ~AD7746_CAPSETUP_CAPEN;
                idx = FIELD_GET(AD7746_CONF_VTFS_MASK, chip->config);
                delay = ad7746_cap_filter_rate_table[idx][1];
                break;
        default:
                return -EINVAL;
        }

        if (chip->cap_setup != cap_setup) {
                ret = i2c_smbus_write_byte_data(chip->client,
                                                AD7746_REG_CAP_SETUP,
                                                cap_setup);
                if (ret < 0)
                        return ret;

                chip->cap_setup = cap_setup;
        }

        if (chip->vt_setup != vt_setup) {
                ret = i2c_smbus_write_byte_data(chip->client,
                                                AD7746_REG_VT_SETUP,
                                                vt_setup);
                if (ret < 0)
                        return ret;

                chip->vt_setup = vt_setup;
        }

        return delay;
}

static inline ssize_t ad7746_start_calib(struct device *dev,
                                         struct device_attribute *attr,
                                         const char *buf,
                                         size_t len,
                                         u8 regval)
{
        struct iio_dev *indio_dev = dev_to_iio_dev(dev);
        struct ad7746_chip_info *chip = iio_priv(indio_dev);
        int ret, timeout = 10;
        bool doit;

        ret = kstrtobool(buf, &doit);
        if (ret < 0)
                return ret;

        if (!doit)
                return 0;

        mutex_lock(&chip->lock);
        regval |= chip->config;
        ret = i2c_smbus_write_byte_data(chip->client, AD7746_REG_CFG, regval);
        if (ret < 0)
                goto unlock;

        do {
                msleep(20);
                ret = i2c_smbus_read_byte_data(chip->client, AD7746_REG_CFG);
                if (ret < 0)
                        goto unlock;

        } while ((ret == regval) && timeout--);

        mutex_unlock(&chip->lock);

        return len;

unlock:
        mutex_unlock(&chip->lock);
        return ret;
}

static ssize_t ad7746_start_offset_calib(struct device *dev,
                                         struct device_attribute *attr,
                                         const char *buf,
                                         size_t len)
{
        struct iio_dev *indio_dev = dev_to_iio_dev(dev);
        int ret = ad7746_select_channel(indio_dev,
                              &ad7746_channels[to_iio_dev_attr(attr)->address]);
        if (ret < 0)
                return ret;

        return ad7746_start_calib(dev, attr, buf, len,
                                  FIELD_PREP(AD7746_CONF_MODE_MASK,
                                             AD7746_CONF_MODE_OFFS_CAL));
}

static ssize_t ad7746_start_gain_calib(struct device *dev,
                                       struct device_attribute *attr,
                                       const char *buf,
                                       size_t len)
{
        struct iio_dev *indio_dev = dev_to_iio_dev(dev);
        int ret = ad7746_select_channel(indio_dev,
                              &ad7746_channels[to_iio_dev_attr(attr)->address]);
        if (ret < 0)
                return ret;

        return ad7746_start_calib(dev, attr, buf, len,
                                  FIELD_PREP(AD7746_CONF_MODE_MASK,
                                             AD7746_CONF_MODE_GAIN_CAL));
}

static IIO_DEVICE_ATTR(in_capacitance0_calibbias_calibration,
                       0200, NULL, ad7746_start_offset_calib, CIN1);
static IIO_DEVICE_ATTR(in_capacitance1_calibbias_calibration,
                       0200, NULL, ad7746_start_offset_calib, CIN2);
static IIO_DEVICE_ATTR(in_capacitance0_calibscale_calibration,
                       0200, NULL, ad7746_start_gain_calib, CIN1);
static IIO_DEVICE_ATTR(in_capacitance1_calibscale_calibration,
                       0200, NULL, ad7746_start_gain_calib, CIN2);
static IIO_DEVICE_ATTR(in_voltage0_calibscale_calibration,
                       0200, NULL, ad7746_start_gain_calib, VIN);

static int ad7746_store_cap_filter_rate_setup(struct ad7746_chip_info *chip,
                                              int val)
{
        int i;

        for (i = 0; i < ARRAY_SIZE(ad7746_cap_filter_rate_table); i++)
                if (val >= ad7746_cap_filter_rate_table[i][0])
                        break;

        if (i >= ARRAY_SIZE(ad7746_cap_filter_rate_table))
                i = ARRAY_SIZE(ad7746_cap_filter_rate_table) - 1;

        chip->config &= ~AD7746_CONF_CAPFS_MASK;
        chip->config |= FIELD_PREP(AD7746_CONF_CAPFS_MASK, i);

        return 0;
}

static int ad7746_store_vt_filter_rate_setup(struct ad7746_chip_info *chip,
                                             int val)
{
        int i;

        for (i = 0; i < ARRAY_SIZE(ad7746_vt_filter_rate_table); i++)
                if (val >= ad7746_vt_filter_rate_table[i][0])
                        break;

        if (i >= ARRAY_SIZE(ad7746_vt_filter_rate_table))
                i = ARRAY_SIZE(ad7746_vt_filter_rate_table) - 1;

        chip->config &= ~AD7746_CONF_VTFS_MASK;
        chip->config |= FIELD_PREP(AD7746_CONF_VTFS_MASK, i);

        return 0;
}

static struct attribute *ad7746_attributes[] = {
        &iio_dev_attr_in_capacitance0_calibbias_calibration.dev_attr.attr,
        &iio_dev_attr_in_capacitance0_calibscale_calibration.dev_attr.attr,
        &iio_dev_attr_in_capacitance1_calibscale_calibration.dev_attr.attr,
        &iio_dev_attr_in_capacitance1_calibbias_calibration.dev_attr.attr,
        &iio_dev_attr_in_voltage0_calibscale_calibration.dev_attr.attr,
        NULL,
};

static const struct attribute_group ad7746_attribute_group = {
        .attrs = ad7746_attributes,
};

static int ad7746_write_raw(struct iio_dev *indio_dev,
                            struct iio_chan_spec const *chan,
                            int val,
                            int val2,
                            long mask)
{
        struct ad7746_chip_info *chip = iio_priv(indio_dev);
        int ret, reg;

        switch (mask) {
        case IIO_CHAN_INFO_CALIBSCALE:
                if (val != 1)
                        return -EINVAL;

                val = (val2 * 1024) / 15625;

                switch (chan->type) {
                case IIO_CAPACITANCE:
                        reg = AD7746_REG_CAP_GAINH;
                        break;
                case IIO_VOLTAGE:
                        reg = AD7746_REG_VOLT_GAINH;
                        break;
                default:
                        return -EINVAL;
                }

                mutex_lock(&chip->lock);
                ret = i2c_smbus_write_word_swapped(chip->client, reg, val);
                mutex_unlock(&chip->lock);
                if (ret < 0)
                        return ret;

                return 0;
        case IIO_CHAN_INFO_CALIBBIAS:
                if (val < 0 || val > 0xFFFF)
                        return -EINVAL;

                mutex_lock(&chip->lock);
                ret = i2c_smbus_write_word_swapped(chip->client,
                                                   AD7746_REG_CAP_OFFH, val);
                mutex_unlock(&chip->lock);
                if (ret < 0)
                        return ret;

                return 0;
        case IIO_CHAN_INFO_OFFSET:
        case IIO_CHAN_INFO_ZEROPOINT:
                if (val < 0 || val > 43008000) /* 21pF */
                        return -EINVAL;

                /*
                 * CAPDAC Scale = 21pF_typ / 127
                 * CIN Scale = 8.192pF / 2^24
                 * Offset Scale = CAPDAC Scale / CIN Scale = 338646
                 */

                val /= 338646;
                mutex_lock(&chip->lock);
                chip->capdac[chan->channel][chan->differential] = val > 0 ?
                        FIELD_PREP(AD7746_CAPDAC_DACP_MASK, val) | AD7746_CAPDAC_DACEN : 0;

                ret = ad7746_set_capdac(chip, chan->channel);
                if (ret < 0) {
                        mutex_unlock(&chip->lock);
                        return ret;
                }

                chip->capdac_set = chan->channel;
                mutex_unlock(&chip->lock);

                return 0;
        case IIO_CHAN_INFO_SAMP_FREQ:
                if (val2)
                        return -EINVAL;

                switch (chan->type) {
                case IIO_CAPACITANCE:
                        mutex_lock(&chip->lock);
                        ret = ad7746_store_cap_filter_rate_setup(chip, val);
                        mutex_unlock(&chip->lock);
                        return ret;
                case IIO_VOLTAGE:
                        mutex_lock(&chip->lock);
                        ret = ad7746_store_vt_filter_rate_setup(chip, val);
                        mutex_unlock(&chip->lock);
                        return ret;
                default:
                        return -EINVAL;
                }
        default:
                return -EINVAL;
        }
}

static const int ad7746_v_samp_freq[] = { 50, 31, 16, 8, };
static const int ad7746_cap_samp_freq[] = { 91, 84, 50, 26, 16, 13, 11, 9, };

static int ad7746_read_avail(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_SAMP_FREQ)
                return -EINVAL;

        switch (chan->type) {
        case IIO_VOLTAGE:
                *vals = ad7746_v_samp_freq;
                *length = ARRAY_SIZE(ad7746_v_samp_freq);
                break;
        case IIO_CAPACITANCE:
                *vals = ad7746_cap_samp_freq;
                *length = ARRAY_SIZE(ad7746_cap_samp_freq);
                break;
        default:
                return -EINVAL;
        }
        *type = IIO_VAL_INT;
        return IIO_AVAIL_LIST;
}

static int ad7746_read_channel(struct iio_dev *indio_dev,
                               struct iio_chan_spec const *chan,
                               int *val)
{
        struct ad7746_chip_info *chip = iio_priv(indio_dev);
        int ret, delay;
        u8 data[3];
        u8 regval;

        ret = ad7746_select_channel(indio_dev, chan);
        if (ret < 0)
                return ret;
        delay = ret;

        regval = chip->config | FIELD_PREP(AD7746_CONF_MODE_MASK,
                                           AD7746_CONF_MODE_SINGLE_CONV);
        ret = i2c_smbus_write_byte_data(chip->client, AD7746_REG_CFG, regval);
        if (ret < 0)
                return ret;

        msleep(delay);
        /* Now read the actual register */
        ret = i2c_smbus_read_i2c_block_data(chip->client,
                                            ad7746_chan_info[chan->address].addr,
                                            sizeof(data), data);
        if (ret < 0)
                return ret;

        /*
         * Offset applied internally becaue the _offset userspace interface is
         * needed for the CAP DACs which apply a controllable offset.
         */
        *val = get_unaligned_be24(data) - 0x800000;

        return 0;
}

static int ad7746_read_raw(struct iio_dev *indio_dev,
                           struct iio_chan_spec const *chan,
                           int *val, int *val2,
                           long mask)
{
        struct ad7746_chip_info *chip = iio_priv(indio_dev);
        int ret, idx;
        u8 reg;

        switch (mask) {
        case IIO_CHAN_INFO_RAW:
                mutex_lock(&chip->lock);
                ret = ad7746_read_channel(indio_dev, chan, val);
                mutex_unlock(&chip->lock);
                if (ret < 0)
                        return ret;

                return IIO_VAL_INT;
        case IIO_CHAN_INFO_CALIBSCALE:
                switch (chan->type) {
                case IIO_CAPACITANCE:
                        reg = AD7746_REG_CAP_GAINH;
                        break;
                case IIO_VOLTAGE:
                        reg = AD7746_REG_VOLT_GAINH;
                        break;
                default:
                        return -EINVAL;
                }

                mutex_lock(&chip->lock);
                ret = i2c_smbus_read_word_swapped(chip->client, reg);
                mutex_unlock(&chip->lock);
                if (ret < 0)
                        return ret;
                /* 1 + gain_val / 2^16 */
                *val = 1;
                *val2 = (15625 * ret) / 1024;

                return IIO_VAL_INT_PLUS_MICRO;
        case IIO_CHAN_INFO_CALIBBIAS:
                mutex_lock(&chip->lock);
                ret = i2c_smbus_read_word_swapped(chip->client,
                                                  AD7746_REG_CAP_OFFH);
                mutex_unlock(&chip->lock);
                if (ret < 0)
                        return ret;
                *val = ret;

                return IIO_VAL_INT;
        case IIO_CHAN_INFO_OFFSET:
        case IIO_CHAN_INFO_ZEROPOINT:
                *val = FIELD_GET(AD7746_CAPDAC_DACP_MASK,
                                 chip->capdac[chan->channel][chan->differential]) * 338646;

                return IIO_VAL_INT;
        case IIO_CHAN_INFO_SCALE:
                switch (chan->type) {
                case IIO_CAPACITANCE:
                        /* 8.192pf / 2^24 */
                        *val =  0;
                        *val2 = 488;
                        return IIO_VAL_INT_PLUS_NANO;
                case IIO_VOLTAGE:
                        /* 1170mV / 2^23 */
                        *val = 1170;
                        if (chan->channel == 1)
                                *val *= 6;
                        *val2 = 23;
                        return IIO_VAL_FRACTIONAL_LOG2;
                case IIO_TEMP:
                        *val = 125;
                        *val2 = 8;
                        return IIO_VAL_FRACTIONAL_LOG2;
                default:
                        return -EINVAL;
                }
        case IIO_CHAN_INFO_SAMP_FREQ:
                switch (chan->type) {
                case IIO_CAPACITANCE:
                        idx = FIELD_GET(AD7746_CONF_CAPFS_MASK, chip->config);
                        *val = ad7746_cap_filter_rate_table[idx][0];
                        return IIO_VAL_INT;
                case IIO_VOLTAGE:
                        idx = FIELD_GET(AD7746_CONF_VTFS_MASK, chip->config);
                        *val = ad7746_vt_filter_rate_table[idx][0];
                        return IIO_VAL_INT;
                default:
                        return -EINVAL;
                }
        default:
                return -EINVAL;
        }
}

static const struct iio_info ad7746_info = {
        .attrs = &ad7746_attribute_group,
        .read_raw = ad7746_read_raw,
        .read_avail = ad7746_read_avail,
        .write_raw = ad7746_write_raw,
};

static int ad7746_probe(struct i2c_client *client)
{
        const struct i2c_device_id *id = i2c_client_get_device_id(client);
        struct device *dev = &client->dev;
        struct ad7746_chip_info *chip;
        struct iio_dev *indio_dev;
        unsigned char regval = 0;
        unsigned int vdd_permille;
        int ret;

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

        chip = iio_priv(indio_dev);
        mutex_init(&chip->lock);

        chip->client = client;
        chip->capdac_set = -1;

        indio_dev->name = id->name;
        indio_dev->info = &ad7746_info;
        indio_dev->channels = ad7746_channels;
        if (id->driver_data == 7746)
                indio_dev->num_channels = ARRAY_SIZE(ad7746_channels);
        else
                indio_dev->num_channels =  ARRAY_SIZE(ad7746_channels) - 2;
        indio_dev->modes = INDIO_DIRECT_MODE;

        if (device_property_read_bool(dev, "adi,exca-output-en")) {
                if (device_property_read_bool(dev, "adi,exca-output-invert"))
                        regval |= AD7746_EXCSETUP_NEXCA;
                else
                        regval |= AD7746_EXCSETUP_EXCA;
        }

        if (device_property_read_bool(dev, "adi,excb-output-en")) {
                if (device_property_read_bool(dev, "adi,excb-output-invert"))
                        regval |= AD7746_EXCSETUP_NEXCB;
                else
                        regval |= AD7746_EXCSETUP_EXCB;
        }

        ret = device_property_read_u32(dev, "adi,excitation-vdd-permille",
                                       &vdd_permille);
        if (!ret) {
                switch (vdd_permille) {
                case 125:
                        regval |= FIELD_PREP(AD7746_EXCSETUP_EXCLVL_MASK, 0);
                        break;
                case 250:
                        regval |= FIELD_PREP(AD7746_EXCSETUP_EXCLVL_MASK, 1);
                        break;
                case 375:
                        regval |= FIELD_PREP(AD7746_EXCSETUP_EXCLVL_MASK, 2);
                        break;
                case 500:
                        regval |= FIELD_PREP(AD7746_EXCSETUP_EXCLVL_MASK, 3);
                        break;
                default:
                        break;
                }
        }

        ret = i2c_smbus_write_byte_data(chip->client, AD7746_REG_EXC_SETUP,
                                        regval);
        if (ret < 0)
                return ret;

        return devm_iio_device_register(indio_dev->dev.parent, indio_dev);
}

static const struct i2c_device_id ad7746_id[] = {
        { "ad7745", 7745 },
        { "ad7746", 7746 },
        { "ad7747", 7747 },
        { }
};
MODULE_DEVICE_TABLE(i2c, ad7746_id);

static const struct of_device_id ad7746_of_match[] = {
        { .compatible = "adi,ad7745" },
        { .compatible = "adi,ad7746" },
        { .compatible = "adi,ad7747" },
        { }
};
MODULE_DEVICE_TABLE(of, ad7746_of_match);

static struct i2c_driver ad7746_driver = {
        .driver = {
                .name = KBUILD_MODNAME,
                .of_match_table = ad7746_of_match,
        },
        .probe = ad7746_probe,
        .id_table = ad7746_id,
};
module_i2c_driver(ad7746_driver);

MODULE_AUTHOR("Michael Hennerich <michael.hennerich@analog.com>");
MODULE_DESCRIPTION("Analog Devices AD7746/5/7 capacitive sensor driver");
MODULE_LICENSE("GPL v2");