// SPDX-License-Identifier: GPL-2.0-only
/*
 * Maxim MAX5522
 * Dual, Ultra-Low-Power 10-Bit, Voltage-Output DACs
 *
 * Copyright 2022 Timesys Corp.
 */

#include <linux/device.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/regmap.h>
#include <linux/regulator/consumer.h>
#include <linux/slab.h>
#include <linux/spi/spi.h>
#include <linux/units.h>

#include <linux/iio/iio.h>

#define MAX5522_MAX_ADDR        15
#define MAX5522_CTRL_NONE       0
#define MAX5522_CTRL_LOAD_IN_A  9
#define MAX5522_CTRL_LOAD_IN_B  10

#define MAX5522_REG_DATA(x)     ((x) + MAX5522_CTRL_LOAD_IN_A)

struct max5522_chip_info {
        const char *name;
        const struct iio_chan_spec *channels;
        unsigned int num_channels;
};

struct max5522_state {
        struct regmap *regmap;
        const struct max5522_chip_info *chip_info;
        unsigned short dac_cache[2];
        int vref_mV;
};

#define MAX5522_CHANNEL(chan) { \
        .type = IIO_VOLTAGE, \
        .indexed = 1, \
        .output = 1, \
        .channel = chan, \
        .info_mask_separate = BIT(IIO_CHAN_INFO_RAW) | \
                              BIT(IIO_CHAN_INFO_SCALE), \
        .scan_type = { \
                .sign = 'u', \
                .realbits = 10, \
                .storagebits = 16, \
                .shift = 2, \
        } \
}

static const struct iio_chan_spec max5522_channels[] = {
        MAX5522_CHANNEL(0),
        MAX5522_CHANNEL(1),
};

enum max5522_type {
        ID_MAX5522,
};

static const struct max5522_chip_info max5522_chip_info_tbl[] = {
        [ID_MAX5522] = {
                .name = "max5522",
                .channels = max5522_channels,
                .num_channels = 2,
        },
};

static inline int max5522_info_to_reg(struct iio_chan_spec const *chan)
{
        return MAX5522_REG_DATA(chan->channel);
}

static int max5522_read_raw(struct iio_dev *indio_dev,
                            struct iio_chan_spec const *chan,
                            int *val, int *val2, long info)
{
        struct max5522_state *state = iio_priv(indio_dev);

        switch (info) {
        case IIO_CHAN_INFO_RAW:
                *val = state->dac_cache[chan->channel];
                return IIO_VAL_INT;
        case IIO_CHAN_INFO_SCALE:
                *val = state->vref_mV;
                *val2 = 10;
                return IIO_VAL_FRACTIONAL_LOG2;
        default:
                return -EINVAL;
        }

        return -EINVAL;
}

static int max5522_write_raw(struct iio_dev *indio_dev,
                             struct iio_chan_spec const *chan,
                             int val, int val2, long info)
{
        struct max5522_state *state = iio_priv(indio_dev);
        int rval;

        if (val > 1023 || val < 0)
                return -EINVAL;

        rval = regmap_write(state->regmap, max5522_info_to_reg(chan),
                            val << chan->scan_type.shift);
        if (rval < 0)
                return rval;

        state->dac_cache[chan->channel] = val;

        return 0;
}

static const struct iio_info max5522_info = {
        .read_raw = max5522_read_raw,
        .write_raw = max5522_write_raw,
};

static const struct regmap_config max5522_regmap_config = {
        .reg_bits = 4,
        .val_bits = 12,
        .max_register = MAX5522_MAX_ADDR,
};

static int max5522_spi_probe(struct spi_device *spi)
{
        struct iio_dev *indio_dev;
        struct max5522_state *state;
        int ret;

        indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*state));
        if (indio_dev == NULL) {
                dev_err(&spi->dev, "failed to allocate iio device\n");
                return  -ENOMEM;
        }

        state = iio_priv(indio_dev);
        state->chip_info = spi_get_device_match_data(spi);
        if (!state->chip_info)
                return -EINVAL;

        ret = devm_regulator_get_enable_read_voltage(&spi->dev, "vrefin");
        if (ret < 0)
                return dev_err_probe(&spi->dev, ret,
                                     "Failed to get vrefin regulator\n");
        state->vref_mV = ret / (MICRO / MILLI);

        state->regmap = devm_regmap_init_spi(spi, &max5522_regmap_config);

        if (IS_ERR(state->regmap))
                return PTR_ERR(state->regmap);

        indio_dev->info = &max5522_info;
        indio_dev->modes = INDIO_DIRECT_MODE;
        indio_dev->channels = max5522_channels;
        indio_dev->num_channels = ARRAY_SIZE(max5522_channels);
        indio_dev->name = max5522_chip_info_tbl[ID_MAX5522].name;

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

static const struct spi_device_id max5522_ids[] = {
        { "max5522", (kernel_ulong_t)&max5522_chip_info_tbl[ID_MAX5522] },
        { }
};
MODULE_DEVICE_TABLE(spi, max5522_ids);

static const struct of_device_id max5522_of_match[] = {
        {
                .compatible = "maxim,max5522",
                .data = &max5522_chip_info_tbl[ID_MAX5522],
        },
        { }
};
MODULE_DEVICE_TABLE(of, max5522_of_match);

static struct spi_driver max5522_spi_driver = {
        .driver = {
                .name = "max5522",
                .of_match_table = max5522_of_match,
        },
        .probe = max5522_spi_probe,
        .id_table = max5522_ids,
};
module_spi_driver(max5522_spi_driver);

MODULE_AUTHOR("Angelo Dureghello <angelo.dureghello@timesys.com");
MODULE_DESCRIPTION("MAX5522 DAC driver");
MODULE_LICENSE("GPL");