root/drivers/iio/adc/mcp3911.c
// SPDX-License-Identifier: GPL-2.0
/*
 * Driver for Microchip MCP3911, Two-channel Analog Front End
 *
 * Copyright (C) 2018 Marcus Folkesson <marcus.folkesson@gmail.com>
 * Copyright (C) 2018 Kent Gustavsson <kent@minoris.se>
 */
#include <linux/bitfield.h>
#include <linux/bitops.h>
#include <linux/cleanup.h>
#include <linux/clk.h>
#include <linux/delay.h>
#include <linux/dev_printk.h>
#include <linux/err.h>
#include <linux/gpio/consumer.h>
#include <linux/module.h>
#include <linux/mod_devicetable.h>
#include <linux/property.h>
#include <linux/regulator/consumer.h>
#include <linux/spi/spi.h>

#include <linux/iio/iio.h>
#include <linux/iio/buffer.h>
#include <linux/iio/triggered_buffer.h>
#include <linux/iio/trigger_consumer.h>
#include <linux/iio/trigger.h>

#include <linux/unaligned.h>

#define MCP3911_REG_CHANNEL0            0x00
#define MCP3911_REG_CHANNEL1            0x03
#define MCP3911_REG_MOD                 0x06
#define MCP3911_REG_PHASE               0x07
#define MCP3911_REG_GAIN                0x09
#define MCP3911_GAIN_MASK(ch)           (GENMASK(2, 0) << 3 * (ch))
#define MCP3911_GAIN_VAL(ch, val)      ((val << 3 * (ch)) & MCP3911_GAIN_MASK(ch))

#define MCP3911_REG_STATUSCOM           0x0a
#define MCP3911_STATUSCOM_DRHIZ         BIT(12)
#define MCP3911_STATUSCOM_READ          GENMASK(7, 6)
#define MCP3911_STATUSCOM_CH1_24WIDTH   BIT(4)
#define MCP3911_STATUSCOM_CH0_24WIDTH   BIT(3)
#define MCP3911_STATUSCOM_EN_OFFCAL     BIT(2)
#define MCP3911_STATUSCOM_EN_GAINCAL    BIT(1)

#define MCP3911_REG_CONFIG              0x0c
#define MCP3911_CONFIG_CLKEXT           BIT(1)
#define MCP3911_CONFIG_VREFEXT          BIT(2)
#define MCP3911_CONFIG_OSR              GENMASK(13, 11)

#define MCP3911_REG_OFFCAL_CH0          0x0e
#define MCP3911_REG_GAINCAL_CH0         0x11
#define MCP3911_REG_OFFCAL_CH1          0x14
#define MCP3911_REG_GAINCAL_CH1         0x17
#define MCP3911_REG_VREFCAL             0x1a

#define MCP3911_CHANNEL(ch)             (MCP3911_REG_CHANNEL0 + (ch) * 3)
#define MCP3911_OFFCAL(ch)              (MCP3911_REG_OFFCAL_CH0 + (ch) * 6)

/* Internal voltage reference in mV */
#define MCP3911_INT_VREF_MV             1200

#define MCP3911_REG_READ(reg, id)       ((((reg) << 1) | ((id) << 6) | (1 << 0)) & 0xff)
#define MCP3911_REG_WRITE(reg, id)      ((((reg) << 1) | ((id) << 6) | (0 << 0)) & 0xff)
#define MCP3911_REG_MASK                GENMASK(4, 1)

#define MCP3911_NUM_SCALES              6

/* Registers compatible with MCP3910 */
#define MCP3910_REG_STATUSCOM           0x0c
#define MCP3910_STATUSCOM_READ          GENMASK(23, 22)
#define MCP3910_STATUSCOM_DRHIZ         BIT(20)

#define MCP3910_REG_GAIN                0x0b

#define MCP3910_REG_CONFIG0             0x0d
#define MCP3910_CONFIG0_EN_OFFCAL       BIT(23)
#define MCP3910_CONFIG0_OSR             GENMASK(15, 13)

#define MCP3910_REG_CONFIG1             0x0e
#define MCP3910_CONFIG1_CLKEXT          BIT(6)
#define MCP3910_CONFIG1_VREFEXT         BIT(7)

#define MCP3910_CHANNEL(ch)             (MCP3911_REG_CHANNEL0 + (ch))

#define MCP3910_REG_OFFCAL_CH0          0x0f
#define MCP3910_OFFCAL(ch)              (MCP3910_REG_OFFCAL_CH0 + (ch) * 6)

/* Maximal number of channels used by the MCP39XX family */
#define MCP39XX_MAX_NUM_CHANNELS        8

static const int mcp3911_osr_table[] = { 32, 64, 128, 256, 512, 1024, 2048, 4096 };
static u32 mcp3911_scale_table[MCP3911_NUM_SCALES][2];

enum mcp3911_id {
        MCP3910,
        MCP3911,
        MCP3912,
        MCP3913,
        MCP3914,
        MCP3918,
        MCP3919,
};

struct mcp3911;
struct mcp3911_chip_info {
        const struct iio_chan_spec *channels;
        unsigned int num_channels;

        int (*config)(struct mcp3911 *adc, bool external_vref);
        int (*get_osr)(struct mcp3911 *adc, u32 *val);
        int (*set_osr)(struct mcp3911 *adc, u32 val);
        int (*enable_offset)(struct mcp3911 *adc, bool enable);
        int (*get_offset)(struct mcp3911 *adc, int channel, int *val);
        int (*set_offset)(struct mcp3911 *adc, int channel, int val);
        int (*set_scale)(struct mcp3911 *adc, int channel, u32 val);
        int (*get_raw)(struct mcp3911 *adc, int channel, int *val);
};

struct mcp3911 {
        struct spi_device *spi;
        struct mutex lock;
        struct clk *clki;
        u32 dev_addr;
        struct iio_trigger *trig;
        u32 gain[MCP39XX_MAX_NUM_CHANNELS];
        const struct mcp3911_chip_info *chip;
        struct {
                u32 channels[MCP39XX_MAX_NUM_CHANNELS];
                aligned_s64 ts;
        } scan;

        u8 tx_buf __aligned(IIO_DMA_MINALIGN);
        u8 rx_buf[MCP39XX_MAX_NUM_CHANNELS * 3];
};

static int mcp3911_read(struct mcp3911 *adc, u8 reg, u32 *val, u8 len)
{
        int ret;

        reg = MCP3911_REG_READ(reg, adc->dev_addr);
        ret = spi_write_then_read(adc->spi, &reg, 1, val, len);
        if (ret < 0)
                return ret;

        be32_to_cpus(val);
        *val >>= ((4 - len) * 8);
        dev_dbg(&adc->spi->dev, "reading 0x%x from register 0x%lx\n", *val,
                FIELD_GET(MCP3911_REG_MASK, reg));
        return ret;
}

static int mcp3911_write(struct mcp3911 *adc, u8 reg, u32 val, u8 len)
{
        dev_dbg(&adc->spi->dev, "writing 0x%x to register 0x%x\n", val, reg);

        val <<= (3 - len) * 8;
        cpu_to_be32s(&val);
        val |= MCP3911_REG_WRITE(reg, adc->dev_addr);

        return spi_write(adc->spi, &val, len + 1);
}

static int mcp3911_update(struct mcp3911 *adc, u8 reg, u32 mask, u32 val, u8 len)
{
        u32 tmp;
        int ret;

        ret = mcp3911_read(adc, reg, &tmp, len);
        if (ret)
                return ret;

        val &= mask;
        val |= tmp & ~mask;
        return mcp3911_write(adc, reg, val, len);
}

static int mcp3911_read_s24(struct mcp3911 *const adc, u8 const reg, s32 *const val)
{
        u32 uval;
        int const ret = mcp3911_read(adc, reg, &uval, 3);

        if (ret)
                return ret;

        *val = sign_extend32(uval, 23);
        return ret;
}

static int mcp3910_enable_offset(struct mcp3911 *adc, bool enable)
{
        unsigned int mask = MCP3910_CONFIG0_EN_OFFCAL;
        unsigned int value = enable ? mask : 0;

        return mcp3911_update(adc, MCP3910_REG_CONFIG0, mask, value, 3);
}

static int mcp3910_get_offset(struct mcp3911 *adc, int channel, int *val)
{
        return mcp3911_read(adc, MCP3910_OFFCAL(channel), val, 3);
}

static int mcp3910_set_offset(struct mcp3911 *adc, int channel, int val)
{
        int ret;

        ret = mcp3911_write(adc, MCP3910_OFFCAL(channel), val, 3);
        if (ret)
                return ret;

        return adc->chip->enable_offset(adc, 1);
}

static int mcp3910_get_raw(struct mcp3911 *adc, int channel, s32 *val)
{
        return mcp3911_read_s24(adc, MCP3910_CHANNEL(channel), val);
}

static int mcp3911_enable_offset(struct mcp3911 *adc, bool enable)
{
        unsigned int mask = MCP3911_STATUSCOM_EN_OFFCAL;
        unsigned int value = enable ? mask : 0;

        return mcp3911_update(adc, MCP3911_REG_STATUSCOM, mask, value, 2);
}

static int mcp3911_get_offset(struct mcp3911 *adc, int channel, int *val)
{
        return mcp3911_read(adc, MCP3911_OFFCAL(channel), val, 3);
}

static int mcp3911_set_offset(struct mcp3911 *adc, int channel, int val)
{
        int ret;

        ret = mcp3911_write(adc, MCP3911_OFFCAL(channel), val, 3);
        if (ret)
                return ret;

        return adc->chip->enable_offset(adc, 1);
}

static int mcp3911_get_raw(struct mcp3911 *adc, int channel, s32 *val)
{
        return mcp3911_read_s24(adc, MCP3911_CHANNEL(channel), val);
}

static int mcp3910_get_osr(struct mcp3911 *adc, u32 *val)
{
        int ret;
        unsigned int osr;

        ret = mcp3911_read(adc, MCP3910_REG_CONFIG0, val, 3);
        if (ret)
                return ret;

        osr = FIELD_GET(MCP3910_CONFIG0_OSR, *val);
        *val = 32 << osr;
        return 0;
}

static int mcp3910_set_osr(struct mcp3911 *adc, u32 val)
{
        unsigned int osr = FIELD_PREP(MCP3910_CONFIG0_OSR, val);
        unsigned int mask = MCP3910_CONFIG0_OSR;

        return mcp3911_update(adc, MCP3910_REG_CONFIG0, mask, osr, 3);
}

static int mcp3911_set_osr(struct mcp3911 *adc, u32 val)
{
        unsigned int osr = FIELD_PREP(MCP3911_CONFIG_OSR, val);
        unsigned int mask = MCP3911_CONFIG_OSR;

        return mcp3911_update(adc, MCP3911_REG_CONFIG, mask, osr, 2);
}

static int mcp3911_get_osr(struct mcp3911 *adc, u32 *val)
{
        int ret;
        unsigned int osr;

        ret = mcp3911_read(adc, MCP3911_REG_CONFIG, val, 2);
        if (ret)
                return ret;

        osr = FIELD_GET(MCP3911_CONFIG_OSR, *val);
        *val = 32 << osr;
        return ret;
}

static int mcp3910_set_scale(struct mcp3911 *adc, int channel, u32 val)
{
        return mcp3911_update(adc, MCP3910_REG_GAIN,
                              MCP3911_GAIN_MASK(channel),
                              MCP3911_GAIN_VAL(channel, val), 3);
}

static int mcp3911_set_scale(struct mcp3911 *adc, int channel, u32 val)
{
        return mcp3911_update(adc, MCP3911_REG_GAIN,
                              MCP3911_GAIN_MASK(channel),
                              MCP3911_GAIN_VAL(channel, val), 1);
}

static int mcp3911_write_raw_get_fmt(struct iio_dev *indio_dev,
                                     struct iio_chan_spec const *chan,
                                     long mask)
{
        switch (mask) {
        case IIO_CHAN_INFO_SCALE:
                return IIO_VAL_INT_PLUS_NANO;
        case IIO_CHAN_INFO_OVERSAMPLING_RATIO:
                return IIO_VAL_INT;
        default:
                return IIO_VAL_INT_PLUS_NANO;
        }
}

static int mcp3911_read_avail(struct iio_dev *indio_dev,
                              struct iio_chan_spec const *chan,
                              const int **vals, int *type, int *length,
                              long info)
{
        switch (info) {
        case IIO_CHAN_INFO_OVERSAMPLING_RATIO:
                *type = IIO_VAL_INT;
                *vals = mcp3911_osr_table;
                *length = ARRAY_SIZE(mcp3911_osr_table);
                return IIO_AVAIL_LIST;
        case IIO_CHAN_INFO_SCALE:
                *type = IIO_VAL_INT_PLUS_NANO;
                *vals = (int *)mcp3911_scale_table;
                *length = ARRAY_SIZE(mcp3911_scale_table) * 2;
                return IIO_AVAIL_LIST;
        default:
                return -EINVAL;
        }
}

static int mcp3911_read_raw(struct iio_dev *indio_dev,
                            struct iio_chan_spec const *channel, int *val,
                            int *val2, long mask)
{
        struct mcp3911 *adc = iio_priv(indio_dev);
        int ret;

        guard(mutex)(&adc->lock);
        switch (mask) {
        case IIO_CHAN_INFO_RAW:
                ret = adc->chip->get_raw(adc, channel->channel, val);
                if (ret)
                        return ret;
                return IIO_VAL_INT;
        case IIO_CHAN_INFO_OFFSET:
                ret = adc->chip->get_offset(adc, channel->channel, val);
                if (ret)
                        return ret;

                return IIO_VAL_INT;
        case IIO_CHAN_INFO_OVERSAMPLING_RATIO:
                ret = adc->chip->get_osr(adc, val);
                if (ret)
                        return ret;

                return IIO_VAL_INT;
        case IIO_CHAN_INFO_SCALE:
                *val = mcp3911_scale_table[ilog2(adc->gain[channel->channel])][0];
                *val2 = mcp3911_scale_table[ilog2(adc->gain[channel->channel])][1];
                return IIO_VAL_INT_PLUS_NANO;
        default:
                return -EINVAL;
        }
}

static int mcp3911_write_raw(struct iio_dev *indio_dev,
                             struct iio_chan_spec const *channel, int val,
                             int val2, long mask)
{
        struct mcp3911 *adc = iio_priv(indio_dev);

        guard(mutex)(&adc->lock);
        switch (mask) {
        case IIO_CHAN_INFO_SCALE:
                for (int i = 0; i < MCP3911_NUM_SCALES; i++) {
                        if (val == mcp3911_scale_table[i][0] &&
                            val2 == mcp3911_scale_table[i][1]) {

                                adc->gain[channel->channel] = BIT(i);
                                return adc->chip->set_scale(adc, channel->channel, i);
                        }
                }
                return -EINVAL;
        case IIO_CHAN_INFO_OFFSET:
                if (val2 != 0)
                        return -EINVAL;

                return adc->chip->set_offset(adc, channel->channel, val);
        case IIO_CHAN_INFO_OVERSAMPLING_RATIO:
                for (int i = 0; i < ARRAY_SIZE(mcp3911_osr_table); i++) {
                        if (val == mcp3911_osr_table[i]) {
                                return adc->chip->set_osr(adc, i);
                        }
                }
                return -EINVAL;
        default:
                return -EINVAL;
        }
}

static int mcp3911_calc_scale_table(u32 vref_mv)
{
        u32 div;
        u64 tmp;

        /*
         * For 24-bit Conversion
         * Raw = ((Voltage)/(Vref) * 2^23 * Gain * 1.5
         * Voltage = Raw * (Vref)/(2^23 * Gain * 1.5)
         *
         * ref = Reference voltage
         * div = (2^23 * 1.5 * gain) = 12582912 * gain
         */
        for (int i = 0; i < MCP3911_NUM_SCALES; i++) {
                div = 12582912 * BIT(i);
                tmp = div_s64((s64)vref_mv * 1000000000LL, div);

                mcp3911_scale_table[i][0] = 0;
                mcp3911_scale_table[i][1] = tmp;
        }

        return 0;
}

#define MCP3911_CHAN(idx) {                                     \
                .type = IIO_VOLTAGE,                            \
                .indexed = 1,                                   \
                .channel = idx,                                 \
                .scan_index = idx,                              \
                .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_OVERSAMPLING_RATIO), \
                .info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |  \
                        BIT(IIO_CHAN_INFO_OFFSET) |             \
                        BIT(IIO_CHAN_INFO_SCALE),               \
                .info_mask_shared_by_type_available =           \
                        BIT(IIO_CHAN_INFO_OVERSAMPLING_RATIO),  \
                .info_mask_separate_available =                 \
                        BIT(IIO_CHAN_INFO_SCALE),               \
                .scan_type = {                                  \
                        .sign = 's',                            \
                        .realbits = 24,                         \
                        .storagebits = 32,                      \
                        .endianness = IIO_BE,                   \
                },                                              \
}

static const struct iio_chan_spec mcp3910_channels[] = {
        MCP3911_CHAN(0),
        MCP3911_CHAN(1),
        IIO_CHAN_SOFT_TIMESTAMP(2),
};

static const struct iio_chan_spec mcp3911_channels[] = {
        MCP3911_CHAN(0),
        MCP3911_CHAN(1),
        IIO_CHAN_SOFT_TIMESTAMP(2),
};

static const struct iio_chan_spec mcp3912_channels[] = {
        MCP3911_CHAN(0),
        MCP3911_CHAN(1),
        MCP3911_CHAN(2),
        MCP3911_CHAN(3),
        IIO_CHAN_SOFT_TIMESTAMP(4),
};

static const struct iio_chan_spec mcp3913_channels[] = {
        MCP3911_CHAN(0),
        MCP3911_CHAN(1),
        MCP3911_CHAN(2),
        MCP3911_CHAN(3),
        MCP3911_CHAN(4),
        MCP3911_CHAN(5),
        IIO_CHAN_SOFT_TIMESTAMP(6),
};

static const struct iio_chan_spec mcp3914_channels[] = {
        MCP3911_CHAN(0),
        MCP3911_CHAN(1),
        MCP3911_CHAN(2),
        MCP3911_CHAN(3),
        MCP3911_CHAN(4),
        MCP3911_CHAN(5),
        MCP3911_CHAN(6),
        MCP3911_CHAN(7),
        IIO_CHAN_SOFT_TIMESTAMP(8),
};

static const struct iio_chan_spec mcp3918_channels[] = {
        MCP3911_CHAN(0),
        IIO_CHAN_SOFT_TIMESTAMP(1),
};

static const struct iio_chan_spec mcp3919_channels[] = {
        MCP3911_CHAN(0),
        MCP3911_CHAN(1),
        MCP3911_CHAN(2),
        IIO_CHAN_SOFT_TIMESTAMP(3),
};

static irqreturn_t mcp3911_trigger_handler(int irq, void *p)
{
        struct iio_poll_func *pf = p;
        struct iio_dev *indio_dev = pf->indio_dev;
        struct mcp3911 *adc = iio_priv(indio_dev);
        struct device *dev = &adc->spi->dev;
        struct spi_transfer xfer[] = {
                {
                        .tx_buf = &adc->tx_buf,
                        .len = 1,
                }, {
                        .rx_buf = adc->rx_buf,
                        .len = (adc->chip->num_channels - 1) * 3,
                },
        };
        int scan_index;
        int i = 0;
        int ret;

        guard(mutex)(&adc->lock);
        adc->tx_buf = MCP3911_REG_READ(MCP3911_CHANNEL(0), adc->dev_addr);
        ret = spi_sync_transfer(adc->spi, xfer, ARRAY_SIZE(xfer));
        if (ret < 0) {
                dev_warn(dev, "failed to get conversion data\n");
                goto out;
        }

        iio_for_each_active_channel(indio_dev, scan_index) {
                const struct iio_chan_spec *scan_chan = &indio_dev->channels[scan_index];

                adc->scan.channels[i] = get_unaligned_be24(&adc->rx_buf[scan_chan->channel * 3]);
                i++;
        }
        iio_push_to_buffers_with_ts(indio_dev, &adc->scan, sizeof(adc->scan),
                                    iio_get_time_ns(indio_dev));
out:
        iio_trigger_notify_done(indio_dev->trig);

        return IRQ_HANDLED;
}

static const struct iio_info mcp3911_info = {
        .read_raw = mcp3911_read_raw,
        .write_raw = mcp3911_write_raw,
        .read_avail = mcp3911_read_avail,
        .write_raw_get_fmt = mcp3911_write_raw_get_fmt,
};

static int mcp3911_config(struct mcp3911 *adc, bool external_vref)
{
        struct device *dev = &adc->spi->dev;
        u32 regval;
        int ret;

        ret = mcp3911_read(adc, MCP3911_REG_CONFIG, &regval, 2);
        if (ret)
                return ret;

        regval &= ~MCP3911_CONFIG_VREFEXT;
        if (external_vref) {
                dev_dbg(dev, "use external voltage reference\n");
                regval |= FIELD_PREP(MCP3911_CONFIG_VREFEXT, 1);
        } else {
                dev_dbg(dev, "use internal voltage reference (1.2V)\n");
                regval |= FIELD_PREP(MCP3911_CONFIG_VREFEXT, 0);
        }

        regval &= ~MCP3911_CONFIG_CLKEXT;
        if (adc->clki) {
                dev_dbg(dev, "use external clock as clocksource\n");
                regval |= FIELD_PREP(MCP3911_CONFIG_CLKEXT, 1);
        } else {
                dev_dbg(dev, "use crystal oscillator as clocksource\n");
                regval |= FIELD_PREP(MCP3911_CONFIG_CLKEXT, 0);
        }

        ret = mcp3911_write(adc, MCP3911_REG_CONFIG, regval, 2);
        if (ret)
                return ret;

        ret = mcp3911_read(adc, MCP3911_REG_STATUSCOM, &regval, 2);
        if (ret)
                return ret;

        /* Address counter incremented, cycle through register types */
        regval &= ~MCP3911_STATUSCOM_READ;
        regval |= FIELD_PREP(MCP3911_STATUSCOM_READ, 0x02);

        regval &= ~MCP3911_STATUSCOM_DRHIZ;
        if (device_property_read_bool(dev, "microchip,data-ready-hiz"))
                regval |= FIELD_PREP(MCP3911_STATUSCOM_DRHIZ, 0);
        else
                regval |= FIELD_PREP(MCP3911_STATUSCOM_DRHIZ, 1);

        /* Disable offset to ignore any old values in offset register */
        regval &= ~MCP3911_STATUSCOM_EN_OFFCAL;

        ret =  mcp3911_write(adc, MCP3911_REG_STATUSCOM, regval, 2);
        if (ret)
                return ret;

        /* Set gain to 1 for all channels */
        ret = mcp3911_read(adc, MCP3911_REG_GAIN, &regval, 1);
        if (ret)
                return ret;

        for (int i = 0; i < adc->chip->num_channels - 1; i++) {
                adc->gain[i] = 1;
                regval &= ~MCP3911_GAIN_MASK(i);
        }

        return mcp3911_write(adc, MCP3911_REG_GAIN, regval, 1);
}

static int mcp3910_config(struct mcp3911 *adc, bool external_vref)
{
        struct device *dev = &adc->spi->dev;
        u32 regval;
        int ret;

        ret = mcp3911_read(adc, MCP3910_REG_CONFIG1, &regval, 3);
        if (ret)
                return ret;

        regval &= ~MCP3910_CONFIG1_VREFEXT;
        if (external_vref) {
                dev_dbg(dev, "use external voltage reference\n");
                regval |= FIELD_PREP(MCP3910_CONFIG1_VREFEXT, 1);
        } else {
                dev_dbg(dev, "use internal voltage reference (1.2V)\n");
                regval |= FIELD_PREP(MCP3910_CONFIG1_VREFEXT, 0);
        }

        regval &= ~MCP3910_CONFIG1_CLKEXT;
        if (adc->clki) {
                dev_dbg(dev, "use external clock as clocksource\n");
                regval |= FIELD_PREP(MCP3910_CONFIG1_CLKEXT, 1);
        } else {
                dev_dbg(dev, "use crystal oscillator as clocksource\n");
                regval |= FIELD_PREP(MCP3910_CONFIG1_CLKEXT, 0);
        }

        ret = mcp3911_write(adc, MCP3910_REG_CONFIG1, regval, 3);
        if (ret)
                return ret;

        ret = mcp3911_read(adc, MCP3910_REG_STATUSCOM, &regval, 3);
        if (ret)
                return ret;

        /* Address counter incremented, cycle through register types */
        regval &= ~MCP3910_STATUSCOM_READ;
        regval |= FIELD_PREP(MCP3910_STATUSCOM_READ, 0x02);

        regval &= ~MCP3910_STATUSCOM_DRHIZ;
        if (device_property_read_bool(dev, "microchip,data-ready-hiz"))
                regval |= FIELD_PREP(MCP3910_STATUSCOM_DRHIZ, 0);
        else
                regval |= FIELD_PREP(MCP3910_STATUSCOM_DRHIZ, 1);

        ret = mcp3911_write(adc, MCP3910_REG_STATUSCOM, regval, 3);
        if (ret)
                return ret;

        /* Set gain to 1 for all channels */
        ret = mcp3911_read(adc, MCP3910_REG_GAIN, &regval, 3);
        if (ret)
                return ret;

        for (int i = 0; i < adc->chip->num_channels - 1; i++) {
                adc->gain[i] = 1;
                regval &= ~MCP3911_GAIN_MASK(i);
        }
        ret = mcp3911_write(adc, MCP3910_REG_GAIN, regval, 3);
        if (ret)
                return ret;

        /* Disable offset to ignore any old values in offset register */
        return adc->chip->enable_offset(adc, 0);
}

static int mcp3911_set_trigger_state(struct iio_trigger *trig, bool enable)
{
        struct mcp3911 *adc = iio_trigger_get_drvdata(trig);

        if (enable)
                enable_irq(adc->spi->irq);
        else
                disable_irq(adc->spi->irq);

        return 0;
}

static const struct iio_trigger_ops mcp3911_trigger_ops = {
        .validate_device = iio_trigger_validate_own_device,
        .set_trigger_state = mcp3911_set_trigger_state,
};

static int mcp3911_probe(struct spi_device *spi)
{
        struct device *dev = &spi->dev;
        struct gpio_desc *gpio_reset;
        struct iio_dev *indio_dev;
        struct mcp3911 *adc;
        bool external_vref;
        u32 vref_mv;
        int ret;

        indio_dev = devm_iio_device_alloc(dev, sizeof(*adc));
        if (!indio_dev)
                return -ENOMEM;

        adc = iio_priv(indio_dev);
        adc->spi = spi;
        adc->chip = spi_get_device_match_data(spi);

        ret = devm_regulator_get_enable_read_voltage(dev, "vref");
        if (ret < 0 && ret != -ENODEV)
                return dev_err_probe(dev, ret, "failed to get vref voltage\n");

        external_vref = ret != -ENODEV;
        vref_mv = external_vref ? ret / 1000 : MCP3911_INT_VREF_MV;

        adc->clki = devm_clk_get_enabled(dev, NULL);
        if (IS_ERR(adc->clki)) {
                if (PTR_ERR(adc->clki) == -ENOENT) {
                        adc->clki = NULL;
                } else {
                        return dev_err_probe(dev, PTR_ERR(adc->clki), "failed to get adc clk\n");
                }
        }

        /*
         * Fallback to "device-addr" due to historical mismatch between
         * dt-bindings and implementation.
         */
        ret = device_property_read_u32(dev, "microchip,device-addr", &adc->dev_addr);
        if (ret)
                device_property_read_u32(dev, "device-addr", &adc->dev_addr);
        if (adc->dev_addr > 3) {
                return dev_err_probe(dev, -EINVAL,
                                     "invalid device address (%i). Must be in range 0-3.\n",
                                     adc->dev_addr);
        }
        dev_dbg(dev, "use device address %i\n", adc->dev_addr);

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

        if (gpio_reset) {
                gpiod_set_value_cansleep(gpio_reset, 0);

                /*
                 * Settling time after Hard Reset Mode (determined experimentally):
                 * 330 micro-seconds are too few; 470 micro-seconds are sufficient.
                 * Just in case, we add some safety factor...
                 */
                fsleep(600);
        }

        ret = adc->chip->config(adc, external_vref);
        if (ret)
                return ret;

        ret = mcp3911_calc_scale_table(vref_mv);
        if (ret)
                return ret;

        /* Set gain to 1 for all channels */
        for (int i = 0; i < adc->chip->num_channels - 1; i++) {
                adc->gain[i] = 1;
                ret = mcp3911_update(adc, MCP3911_REG_GAIN,
                                     MCP3911_GAIN_MASK(i),
                                     MCP3911_GAIN_VAL(i, 0), 1);
                if (ret)
                        return ret;
        }

        indio_dev->name = spi_get_device_id(spi)->name;
        indio_dev->modes = INDIO_DIRECT_MODE;
        indio_dev->info = &mcp3911_info;
        spi_set_drvdata(spi, indio_dev);

        indio_dev->channels = adc->chip->channels;
        indio_dev->num_channels = adc->chip->num_channels;

        mutex_init(&adc->lock);

        if (spi->irq > 0) {
                adc->trig = devm_iio_trigger_alloc(dev, "%s-dev%d", indio_dev->name,
                                                   iio_device_id(indio_dev));
                if (!adc->trig)
                        return -ENOMEM;

                adc->trig->ops = &mcp3911_trigger_ops;
                iio_trigger_set_drvdata(adc->trig, adc);
                ret = devm_iio_trigger_register(dev, adc->trig);
                if (ret)
                        return ret;

                /*
                 * The device generates interrupts as long as it is powered up.
                 * Some platforms might not allow the option to power it down so
                 * don't enable the interrupt to avoid extra load on the system.
                 */
                ret = devm_request_irq(dev, spi->irq, &iio_trigger_generic_data_rdy_poll,
                                       IRQF_NO_AUTOEN | IRQF_NO_THREAD,
                                       indio_dev->name, adc->trig);
                if (ret)
                        return ret;
        }

        ret = devm_iio_triggered_buffer_setup(dev, indio_dev, NULL,
                                              mcp3911_trigger_handler, NULL);
        if (ret)
                return ret;

        return devm_iio_device_register(dev, indio_dev);
}

static const struct mcp3911_chip_info mcp3911_chip_info[] = {
        [MCP3910] = {
                .channels = mcp3910_channels,
                .num_channels = ARRAY_SIZE(mcp3910_channels),
                .config = mcp3910_config,
                .get_osr = mcp3910_get_osr,
                .set_osr = mcp3910_set_osr,
                .enable_offset = mcp3910_enable_offset,
                .get_offset = mcp3910_get_offset,
                .set_offset = mcp3910_set_offset,
                .set_scale = mcp3910_set_scale,
                .get_raw = mcp3910_get_raw,
        },
        [MCP3911] = {
                .channels = mcp3911_channels,
                .num_channels = ARRAY_SIZE(mcp3911_channels),
                .config = mcp3911_config,
                .get_osr = mcp3911_get_osr,
                .set_osr = mcp3911_set_osr,
                .enable_offset = mcp3911_enable_offset,
                .get_offset = mcp3911_get_offset,
                .set_offset = mcp3911_set_offset,
                .set_scale = mcp3911_set_scale,
                .get_raw = mcp3911_get_raw,
        },
        [MCP3912] = {
                .channels = mcp3912_channels,
                .num_channels = ARRAY_SIZE(mcp3912_channels),
                .config = mcp3910_config,
                .get_osr = mcp3910_get_osr,
                .set_osr = mcp3910_set_osr,
                .enable_offset = mcp3910_enable_offset,
                .get_offset = mcp3910_get_offset,
                .set_offset = mcp3910_set_offset,
                .set_scale = mcp3910_set_scale,
                .get_raw = mcp3910_get_raw,
        },
        [MCP3913] = {
                .channels = mcp3913_channels,
                .num_channels = ARRAY_SIZE(mcp3913_channels),
                .config = mcp3910_config,
                .get_osr = mcp3910_get_osr,
                .set_osr = mcp3910_set_osr,
                .enable_offset = mcp3910_enable_offset,
                .get_offset = mcp3910_get_offset,
                .set_offset = mcp3910_set_offset,
                .set_scale = mcp3910_set_scale,
                .get_raw = mcp3910_get_raw,
        },
        [MCP3914] = {
                .channels = mcp3914_channels,
                .num_channels = ARRAY_SIZE(mcp3914_channels),
                .config = mcp3910_config,
                .get_osr = mcp3910_get_osr,
                .set_osr = mcp3910_set_osr,
                .enable_offset = mcp3910_enable_offset,
                .get_offset = mcp3910_get_offset,
                .set_offset = mcp3910_set_offset,
                .set_scale = mcp3910_set_scale,
                .get_raw = mcp3910_get_raw,
        },
        [MCP3918] = {
                .channels = mcp3918_channels,
                .num_channels = ARRAY_SIZE(mcp3918_channels),
                .config = mcp3910_config,
                .get_osr = mcp3910_get_osr,
                .set_osr = mcp3910_set_osr,
                .enable_offset = mcp3910_enable_offset,
                .get_offset = mcp3910_get_offset,
                .set_offset = mcp3910_set_offset,
                .set_scale = mcp3910_set_scale,
                .get_raw = mcp3910_get_raw,
        },
        [MCP3919] = {
                .channels = mcp3919_channels,
                .num_channels = ARRAY_SIZE(mcp3919_channels),
                .config = mcp3910_config,
                .get_osr = mcp3910_get_osr,
                .set_osr = mcp3910_set_osr,
                .enable_offset = mcp3910_enable_offset,
                .get_offset = mcp3910_get_offset,
                .set_offset = mcp3910_set_offset,
                .set_scale = mcp3910_set_scale,
                .get_raw = mcp3910_get_raw,
        },
};
static const struct of_device_id mcp3911_dt_ids[] = {
        { .compatible = "microchip,mcp3910", .data = &mcp3911_chip_info[MCP3910] },
        { .compatible = "microchip,mcp3911", .data = &mcp3911_chip_info[MCP3911] },
        { .compatible = "microchip,mcp3912", .data = &mcp3911_chip_info[MCP3912] },
        { .compatible = "microchip,mcp3913", .data = &mcp3911_chip_info[MCP3913] },
        { .compatible = "microchip,mcp3914", .data = &mcp3911_chip_info[MCP3914] },
        { .compatible = "microchip,mcp3918", .data = &mcp3911_chip_info[MCP3918] },
        { .compatible = "microchip,mcp3919", .data = &mcp3911_chip_info[MCP3919] },
        { }
};
MODULE_DEVICE_TABLE(of, mcp3911_dt_ids);

static const struct spi_device_id mcp3911_id[] = {
        { "mcp3910", (kernel_ulong_t)&mcp3911_chip_info[MCP3910] },
        { "mcp3911", (kernel_ulong_t)&mcp3911_chip_info[MCP3911] },
        { "mcp3912", (kernel_ulong_t)&mcp3911_chip_info[MCP3912] },
        { "mcp3913", (kernel_ulong_t)&mcp3911_chip_info[MCP3913] },
        { "mcp3914", (kernel_ulong_t)&mcp3911_chip_info[MCP3914] },
        { "mcp3918", (kernel_ulong_t)&mcp3911_chip_info[MCP3918] },
        { "mcp3919", (kernel_ulong_t)&mcp3911_chip_info[MCP3919] },
        { }
};
MODULE_DEVICE_TABLE(spi, mcp3911_id);

static struct spi_driver mcp3911_driver = {
        .driver = {
                .name = "mcp3911",
                .of_match_table = mcp3911_dt_ids,
        },
        .probe = mcp3911_probe,
        .id_table = mcp3911_id,
};
module_spi_driver(mcp3911_driver);

MODULE_AUTHOR("Marcus Folkesson <marcus.folkesson@gmail.com>");
MODULE_AUTHOR("Kent Gustavsson <kent@minoris.se>");
MODULE_DESCRIPTION("Microchip Technology MCP3911");
MODULE_LICENSE("GPL v2");