// SPDX-License-Identifier: GPL-2.0-only
/*
 * Support for Microchip MCP4728
 *
 * Copyright (C) 2023 Andrea Collamati <andrea.collamati@gmail.com>
 *
 * Based on mcp4725 by Peter Meerwald <pmeerw@pmeerw.net>
 *
 * Driver for the Microchip I2C 12-bit digital-to-analog quad channels
 * converter (DAC).
 *
 * (7-bit I2C slave address 0x60, the three LSBs can be configured in
 * hardware)
 */

#include <linux/bitfield.h>
#include <linux/delay.h>
#include <linux/err.h>
#include <linux/i2c.h>
#include <linux/iio/iio.h>
#include <linux/iio/sysfs.h>
#include <linux/module.h>
#include <linux/mod_devicetable.h>
#include <linux/property.h>
#include <linux/regulator/consumer.h>

#define MCP4728_RESOLUTION        12
#define MCP4728_N_CHANNELS        4

#define MCP4728_CMD_MASK          GENMASK(7, 3)
#define MCP4728_CHSEL_MASK        GENMASK(2, 1)
#define MCP4728_UDAC_MASK         BIT(0)

#define MCP4728_VREF_MASK         BIT(7)
#define MCP4728_PDMODE_MASK       GENMASK(6, 5)
#define MCP4728_GAIN_MASK         BIT(4)

#define MCP4728_DAC_H_MASK        GENMASK(3, 0)
#define MCP4728_DAC_L_MASK        GENMASK(7, 0)

#define MCP4728_RDY_MASK          BIT(7)

#define MCP4728_MW_CMD            0x08 /* Multiwrite Command */
#define MCP4728_SW_CMD            0x0A /* Sequential Write Command with EEPROM */

#define MCP4728_READ_RESPONSE_LEN (MCP4728_N_CHANNELS * 3 * 2)
#define MCP4728_WRITE_EEPROM_LEN  (1 + MCP4728_N_CHANNELS * 2)

enum vref_mode {
        MCP4728_VREF_EXTERNAL_VDD    = 0,
        MCP4728_VREF_INTERNAL_2048mV = 1,
};

enum gain_mode {
        MCP4728_GAIN_X1 = 0,
        MCP4728_GAIN_X2 = 1,
};

enum iio_powerdown_mode {
        MCP4728_IIO_1K,
        MCP4728_IIO_100K,
        MCP4728_IIO_500K,
};

struct mcp4728_channel_data {
        enum vref_mode ref_mode;
        enum iio_powerdown_mode pd_mode;
        enum gain_mode g_mode;
        u16 dac_value;
};

/* MCP4728 Full Scale Ranges
 * the device available ranges are
 * - VREF = VDD                         FSR = from 0.0V to VDD
 * - VREF = Internal    Gain = 1        FSR = from 0.0V to VREF
 * - VREF = Internal    Gain = 2        FSR = from 0.0V to 2*VREF
 */
enum mcp4728_scale {
        MCP4728_SCALE_VDD,
        MCP4728_SCALE_VINT_NO_GAIN,
        MCP4728_SCALE_VINT_GAIN_X2,
        MCP4728_N_SCALES
};

struct mcp4728_data {
        struct i2c_client *client;
        bool powerdown;
        int scales_avail[MCP4728_N_SCALES * 2];
        struct mcp4728_channel_data chdata[MCP4728_N_CHANNELS];
};

#define MCP4728_CHAN(chan) {                                            \
        .type = IIO_VOLTAGE,                                            \
        .output = 1,                                                    \
        .indexed = 1,                                                   \
        .channel = chan,                                                \
        .info_mask_separate = BIT(IIO_CHAN_INFO_RAW)    |               \
                              BIT(IIO_CHAN_INFO_SCALE),                 \
        .info_mask_shared_by_type_available = BIT(IIO_CHAN_INFO_SCALE), \
        .ext_info = mcp4728_ext_info,                                   \
}

static int mcp4728_suspend(struct device *dev);
static int mcp4728_resume(struct device *dev);

static ssize_t mcp4728_store_eeprom(struct device *dev,
                                    struct device_attribute *attr,
                                    const char *buf, size_t len)
{
        struct iio_dev *indio_dev = dev_to_iio_dev(dev);
        struct mcp4728_data *data = iio_priv(indio_dev);
        u8 outbuf[MCP4728_WRITE_EEPROM_LEN];
        int tries = 20;
        u8 inbuf[3];
        bool state;
        int ret;
        unsigned int i;

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

        if (!state)
                return 0;

        outbuf[0] = FIELD_PREP(MCP4728_CMD_MASK, MCP4728_SW_CMD);

        for (i = 0; i < MCP4728_N_CHANNELS; i++) {
                struct mcp4728_channel_data *ch = &data->chdata[i];
                int offset                      = 1 + i * 2;

                outbuf[offset] = FIELD_PREP(MCP4728_VREF_MASK, ch->ref_mode);

                if (data->powerdown) {
                        u8 mcp4728_pd_mode = ch->pd_mode + 1;

                        outbuf[offset] |= FIELD_PREP(MCP4728_PDMODE_MASK,
                                                     mcp4728_pd_mode);
                }

                outbuf[offset] |= FIELD_PREP(MCP4728_GAIN_MASK, ch->g_mode);
                outbuf[offset] |=
                        FIELD_PREP(MCP4728_DAC_H_MASK, ch->dac_value >> 8);
                outbuf[offset + 1] =
                        FIELD_PREP(MCP4728_DAC_L_MASK, ch->dac_value);
        }

        ret = i2c_master_send(data->client, outbuf, MCP4728_WRITE_EEPROM_LEN);
        if (ret < 0)
                return ret;
        else if (ret != MCP4728_WRITE_EEPROM_LEN)
                return -EIO;

        /* wait RDY signal for write complete, takes up to 50ms */
        while (tries--) {
                msleep(20);
                ret = i2c_master_recv(data->client, inbuf, 3);
                if (ret < 0)
                        return ret;
                else if (ret != 3)
                        return -EIO;

                if (FIELD_GET(MCP4728_RDY_MASK, inbuf[0]))
                        break;
        }

        if (tries < 0) {
                dev_err(&data->client->dev, "%s failed, incomplete\n",
                        __func__);
                return -EIO;
        }
        return len;
}

static IIO_DEVICE_ATTR(store_eeprom, 0200, NULL, mcp4728_store_eeprom, 0);

static struct attribute *mcp4728_attributes[] = {
        &iio_dev_attr_store_eeprom.dev_attr.attr,
        NULL,
};

static const struct attribute_group mcp4728_attribute_group = {
        .attrs = mcp4728_attributes,
};

static int mcp4728_program_channel_cfg(int channel, struct iio_dev *indio_dev)
{
        struct mcp4728_data *data       = iio_priv(indio_dev);
        struct mcp4728_channel_data *ch = &data->chdata[channel];
        u8 outbuf[3];
        int ret;

        outbuf[0] = FIELD_PREP(MCP4728_CMD_MASK, MCP4728_MW_CMD);
        outbuf[0] |= FIELD_PREP(MCP4728_CHSEL_MASK, channel);
        outbuf[0] |= FIELD_PREP(MCP4728_UDAC_MASK, 0);

        outbuf[1] = FIELD_PREP(MCP4728_VREF_MASK, ch->ref_mode);

        if (data->powerdown)
                outbuf[1] |= FIELD_PREP(MCP4728_PDMODE_MASK, ch->pd_mode + 1);

        outbuf[1] |= FIELD_PREP(MCP4728_GAIN_MASK, ch->g_mode);
        outbuf[1] |= FIELD_PREP(MCP4728_DAC_H_MASK, ch->dac_value >> 8);
        outbuf[2] = FIELD_PREP(MCP4728_DAC_L_MASK, ch->dac_value);

        ret = i2c_master_send(data->client, outbuf, 3);
        if (ret < 0)
                return ret;
        else if (ret != 3)
                return -EIO;

        return 0;
}

static const char *const mcp4728_powerdown_modes[] = { "1kohm_to_gnd",
                                                       "100kohm_to_gnd",
                                                       "500kohm_to_gnd" };

static int mcp4728_get_powerdown_mode(struct iio_dev *indio_dev,
                                      const struct iio_chan_spec *chan)
{
        struct mcp4728_data *data = iio_priv(indio_dev);

        return data->chdata[chan->channel].pd_mode;
}

static int mcp4728_set_powerdown_mode(struct iio_dev *indio_dev,
                                      const struct iio_chan_spec *chan,
                                      unsigned int mode)
{
        struct mcp4728_data *data = iio_priv(indio_dev);

        data->chdata[chan->channel].pd_mode = mode;

        return 0;
}

static ssize_t mcp4728_read_powerdown(struct iio_dev *indio_dev,
                                      uintptr_t private,
                                      const struct iio_chan_spec *chan,
                                      char *buf)
{
        struct mcp4728_data *data = iio_priv(indio_dev);

        return sysfs_emit(buf, "%d\n", data->powerdown);
}

static ssize_t mcp4728_write_powerdown(struct iio_dev *indio_dev,
                                       uintptr_t private,
                                       const struct iio_chan_spec *chan,
                                       const char *buf, size_t len)
{
        struct mcp4728_data *data = iio_priv(indio_dev);
        bool state;
        int ret;

        ret = kstrtobool(buf, &state);
        if (ret)
                return ret;

        if (state)
                ret = mcp4728_suspend(&data->client->dev);
        else
                ret = mcp4728_resume(&data->client->dev);

        if (ret < 0)
                return ret;

        return len;
}

static const struct iio_enum mcp4728_powerdown_mode_enum = {
        .items     = mcp4728_powerdown_modes,
        .num_items = ARRAY_SIZE(mcp4728_powerdown_modes),
        .get       = mcp4728_get_powerdown_mode,
        .set       = mcp4728_set_powerdown_mode,
};

static const struct iio_chan_spec_ext_info mcp4728_ext_info[] = {
        {
                .name   = "powerdown",
                .read   = mcp4728_read_powerdown,
                .write  = mcp4728_write_powerdown,
                .shared = IIO_SEPARATE,
        },
        IIO_ENUM("powerdown_mode", IIO_SEPARATE, &mcp4728_powerdown_mode_enum),
        IIO_ENUM_AVAILABLE("powerdown_mode", IIO_SHARED_BY_TYPE,
                           &mcp4728_powerdown_mode_enum),
        { }
};

static const struct iio_chan_spec mcp4728_channels[MCP4728_N_CHANNELS] = {
        MCP4728_CHAN(0),
        MCP4728_CHAN(1),
        MCP4728_CHAN(2),
        MCP4728_CHAN(3),
};

static void mcp4728_get_scale_avail(enum mcp4728_scale scale,
                                    struct mcp4728_data *data, int *val,
                                    int *val2)
{
        *val  = data->scales_avail[scale * 2];
        *val2 = data->scales_avail[scale * 2 + 1];
}

static void mcp4728_get_scale(int channel, struct mcp4728_data *data, int *val,
                              int *val2)
{
        int ref_mode = data->chdata[channel].ref_mode;
        int g_mode   = data->chdata[channel].g_mode;

        if (ref_mode == MCP4728_VREF_EXTERNAL_VDD) {
                mcp4728_get_scale_avail(MCP4728_SCALE_VDD, data, val, val2);
        } else {
                if (g_mode == MCP4728_GAIN_X1) {
                        mcp4728_get_scale_avail(MCP4728_SCALE_VINT_NO_GAIN,
                                                data, val, val2);
                } else {
                        mcp4728_get_scale_avail(MCP4728_SCALE_VINT_GAIN_X2,
                                                data, val, val2);
                }
        }
}

static int mcp4728_find_matching_scale(struct mcp4728_data *data, int val,
                                       int val2)
{
        for (int i = 0; i < MCP4728_N_SCALES; i++) {
                if (data->scales_avail[i * 2] == val &&
                    data->scales_avail[i * 2 + 1] == val2)
                        return i;
        }
        return -EINVAL;
}

static int mcp4728_set_scale(int channel, struct mcp4728_data *data, int val,
                             int val2)
{
        int scale = mcp4728_find_matching_scale(data, val, val2);

        if (scale < 0)
                return scale;

        switch (scale) {
        case MCP4728_SCALE_VDD:
                data->chdata[channel].ref_mode = MCP4728_VREF_EXTERNAL_VDD;
                return 0;
        case MCP4728_SCALE_VINT_NO_GAIN:
                data->chdata[channel].ref_mode = MCP4728_VREF_INTERNAL_2048mV;
                data->chdata[channel].g_mode   = MCP4728_GAIN_X1;
                return 0;
        case MCP4728_SCALE_VINT_GAIN_X2:
                data->chdata[channel].ref_mode = MCP4728_VREF_INTERNAL_2048mV;
                data->chdata[channel].g_mode   = MCP4728_GAIN_X2;
                return 0;
        default:
                return -EINVAL;
        }
}

static int mcp4728_read_raw(struct iio_dev *indio_dev,
                            struct iio_chan_spec const *chan, int *val,
                            int *val2, long mask)
{
        struct mcp4728_data *data = iio_priv(indio_dev);

        switch (mask) {
        case IIO_CHAN_INFO_RAW:
                *val = data->chdata[chan->channel].dac_value;
                return IIO_VAL_INT;
        case IIO_CHAN_INFO_SCALE:
                mcp4728_get_scale(chan->channel, data, val, val2);
                return IIO_VAL_INT_PLUS_MICRO;
        }
        return -EINVAL;
}

static int mcp4728_write_raw(struct iio_dev *indio_dev,
                             struct iio_chan_spec const *chan, int val,
                             int val2, long mask)
{
        struct mcp4728_data *data = iio_priv(indio_dev);
        int ret;

        switch (mask) {
        case IIO_CHAN_INFO_RAW:
                if (val < 0 || val > GENMASK(MCP4728_RESOLUTION - 1, 0))
                        return -EINVAL;
                data->chdata[chan->channel].dac_value = val;
                return mcp4728_program_channel_cfg(chan->channel, indio_dev);
        case IIO_CHAN_INFO_SCALE:
                ret = mcp4728_set_scale(chan->channel, data, val, val2);
                if (ret)
                        return ret;

                return mcp4728_program_channel_cfg(chan->channel, indio_dev);
        default:
                return -EINVAL;
        }
}

static void mcp4728_init_scale_avail(enum mcp4728_scale scale, int vref_mv,
                                     struct mcp4728_data *data)
{
        s64 tmp;
        int value_micro;
        int value_int;

        tmp       = (s64)vref_mv * 1000000LL >> MCP4728_RESOLUTION;
        value_int = div_s64_rem(tmp, 1000000LL, &value_micro);

        data->scales_avail[scale * 2]     = value_int;
        data->scales_avail[scale * 2 + 1] = value_micro;
}

static int mcp4728_init_scales_avail(struct mcp4728_data *data, int vdd_mv)
{
        mcp4728_init_scale_avail(MCP4728_SCALE_VDD, vdd_mv, data);
        mcp4728_init_scale_avail(MCP4728_SCALE_VINT_NO_GAIN, 2048, data);
        mcp4728_init_scale_avail(MCP4728_SCALE_VINT_GAIN_X2, 4096, data);

        return 0;
}

static int mcp4728_read_avail(struct iio_dev *indio_dev,
                              struct iio_chan_spec const *chan,
                              const int **vals, int *type, int *length,
                              long info)
{
        struct mcp4728_data *data = iio_priv(indio_dev);

        switch (info) {
        case IIO_CHAN_INFO_SCALE:
                *type = IIO_VAL_INT_PLUS_MICRO;

                switch (chan->type) {
                case IIO_VOLTAGE:
                        *vals   = data->scales_avail;
                        *length = MCP4728_N_SCALES * 2;
                        return IIO_AVAIL_LIST;
                default:
                        return -EINVAL;
                }
        default:
                return -EINVAL;
        }
}

static const struct iio_info mcp4728_info = {
        .read_raw   = mcp4728_read_raw,
        .write_raw  = mcp4728_write_raw,
        .read_avail = &mcp4728_read_avail,
        .attrs      = &mcp4728_attribute_group,
};

static int mcp4728_suspend(struct device *dev)
{
        struct iio_dev *indio_dev = dev_get_drvdata(dev);
        struct mcp4728_data *data = iio_priv(indio_dev);
        unsigned int i;

        data->powerdown = true;

        for (i = 0; i < MCP4728_N_CHANNELS; i++) {
                int err = mcp4728_program_channel_cfg(i, indio_dev);

                if (err)
                        return err;
        }
        return 0;
}

static int mcp4728_resume(struct device *dev)
{
        struct iio_dev *indio_dev = dev_get_drvdata(dev);
        struct mcp4728_data *data = iio_priv(indio_dev);
        int err                   = 0;
        unsigned int i;

        data->powerdown = false;

        for (i = 0; i < MCP4728_N_CHANNELS; i++) {
                int ret = mcp4728_program_channel_cfg(i, indio_dev);

                if (ret)
                        err = ret;
        }
        return err;
}

static DEFINE_SIMPLE_DEV_PM_OPS(mcp4728_pm_ops, mcp4728_suspend,
                                mcp4728_resume);

static int mcp4728_init_channels_data(struct mcp4728_data *data)
{
        u8 inbuf[MCP4728_READ_RESPONSE_LEN];
        int ret;
        unsigned int i;

        ret = i2c_master_recv(data->client, inbuf, MCP4728_READ_RESPONSE_LEN);
        if (ret < 0) {
                return dev_err_probe(&data->client->dev, ret,
                                     "failed to read mcp4728 conf.\n");
        } else if (ret != MCP4728_READ_RESPONSE_LEN) {
                return dev_err_probe(&data->client->dev, -EIO,
                        "failed to read mcp4728 conf. Wrong Response Len ret=%d\n",
                        ret);
        }

        for (i = 0; i < MCP4728_N_CHANNELS; i++) {
                struct mcp4728_channel_data *ch = &data->chdata[i];
                u8 r2                           = inbuf[i * 6 + 1];
                u8 r3                           = inbuf[i * 6 + 2];

                ch->dac_value = FIELD_GET(MCP4728_DAC_H_MASK, r2) << 8 |
                                FIELD_GET(MCP4728_DAC_L_MASK, r3);
                ch->ref_mode = FIELD_GET(MCP4728_VREF_MASK, r2);
                ch->pd_mode  = FIELD_GET(MCP4728_PDMODE_MASK, r2);
                ch->g_mode   = FIELD_GET(MCP4728_GAIN_MASK, r2);
        }

        return 0;
}

static int mcp4728_probe(struct i2c_client *client)
{
        const struct i2c_device_id *id = i2c_client_get_device_id(client);
        struct mcp4728_data *data;
        struct iio_dev *indio_dev;
        int ret, vdd_mv;

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

        data = iio_priv(indio_dev);
        i2c_set_clientdata(client, indio_dev);
        data->client = client;

        ret = devm_regulator_get_enable_read_voltage(&client->dev, "vdd");
        if (ret < 0)
                return ret;

        vdd_mv = ret / 1000;

        /*
         * MCP4728 has internal EEPROM that save each channel boot
         * configuration. It means that device configuration is unknown to the
         * driver at kernel boot. mcp4728_init_channels_data() reads back DAC
         * settings and stores them in data structure.
         */
        ret = mcp4728_init_channels_data(data);
        if (ret) {
                return dev_err_probe(&client->dev, ret,
                        "failed to read mcp4728 current configuration\n");
        }

        ret = mcp4728_init_scales_avail(data, vdd_mv);
        if (ret) {
                return dev_err_probe(&client->dev, ret,
                                     "failed to init scales\n");
        }

        indio_dev->name         = id->name;
        indio_dev->info         = &mcp4728_info;
        indio_dev->channels     = mcp4728_channels;
        indio_dev->num_channels = MCP4728_N_CHANNELS;
        indio_dev->modes        = INDIO_DIRECT_MODE;

        return devm_iio_device_register(&client->dev, indio_dev);
}

static const struct i2c_device_id mcp4728_id[] = {
        { "mcp4728" },
        { }
};
MODULE_DEVICE_TABLE(i2c, mcp4728_id);

static const struct of_device_id mcp4728_of_match[] = {
        { .compatible = "microchip,mcp4728" },
        { }
};
MODULE_DEVICE_TABLE(of, mcp4728_of_match);

static struct i2c_driver mcp4728_driver = {
        .driver = {
                .name = "mcp4728",
                .of_match_table = mcp4728_of_match,
                .pm = pm_sleep_ptr(&mcp4728_pm_ops),
        },
        .probe = mcp4728_probe,
        .id_table = mcp4728_id,
};
module_i2c_driver(mcp4728_driver);

MODULE_AUTHOR("Andrea Collamati <andrea.collamati@gmail.com>");
MODULE_DESCRIPTION("MCP4728 12-bit DAC");
MODULE_LICENSE("GPL");