// SPDX-License-Identifier: GPL-2.0-only
/*
 * IIO DAC driver for Analog Devices AD8801 DAC
 *
 * Copyright (C) 2016 Gwenhael Goavec-Merou
 */

#include <linux/iio/iio.h>
#include <linux/module.h>
#include <linux/regulator/consumer.h>
#include <linux/spi/spi.h>
#include <linux/sysfs.h>

#define AD8801_CFG_ADDR_OFFSET 8

enum ad8801_device_ids {
        ID_AD8801,
        ID_AD8803,
};

struct ad8801_state {
        struct spi_device *spi;
        unsigned char dac_cache[8]; /* Value write on each channel */
        unsigned int vrefh_mv;
        unsigned int vrefl_mv;

        __be16 data __aligned(IIO_DMA_MINALIGN);
};

static int ad8801_spi_write(struct ad8801_state *state,
        u8 channel, unsigned char value)
{
        state->data = cpu_to_be16((channel << AD8801_CFG_ADDR_OFFSET) | value);
        return spi_write(state->spi, &state->data, sizeof(state->data));
}

static int ad8801_write_raw(struct iio_dev *indio_dev,
        struct iio_chan_spec const *chan, int val, int val2, long mask)
{
        struct ad8801_state *state = iio_priv(indio_dev);
        int ret;

        switch (mask) {
        case IIO_CHAN_INFO_RAW:
                if (val >= 256 || val < 0)
                        return -EINVAL;

                ret = ad8801_spi_write(state, chan->channel, val);
                if (ret == 0)
                        state->dac_cache[chan->channel] = val;
                break;
        default:
                ret = -EINVAL;
        }

        return ret;
}

static int ad8801_read_raw(struct iio_dev *indio_dev,
        struct iio_chan_spec const *chan, int *val, int *val2, long info)
{
        struct ad8801_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->vrefh_mv - state->vrefl_mv;
                *val2 = 8;
                return IIO_VAL_FRACTIONAL_LOG2;
        case IIO_CHAN_INFO_OFFSET:
                *val = state->vrefl_mv;
                return IIO_VAL_INT;
        default:
                return -EINVAL;
        }

        return -EINVAL;
}

static const struct iio_info ad8801_info = {
        .read_raw = ad8801_read_raw,
        .write_raw = ad8801_write_raw,
};

#define AD8801_CHANNEL(chan) {          \
        .type = IIO_VOLTAGE,                    \
        .indexed = 1,                           \
        .output = 1,                            \
        .channel = chan,                        \
        .info_mask_separate = BIT(IIO_CHAN_INFO_RAW), \
        .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE) |  \
                BIT(IIO_CHAN_INFO_OFFSET), \
}

static const struct iio_chan_spec ad8801_channels[] = {
        AD8801_CHANNEL(0),
        AD8801_CHANNEL(1),
        AD8801_CHANNEL(2),
        AD8801_CHANNEL(3),
        AD8801_CHANNEL(4),
        AD8801_CHANNEL(5),
        AD8801_CHANNEL(6),
        AD8801_CHANNEL(7),
};

static int ad8801_probe(struct spi_device *spi)
{
        struct iio_dev *indio_dev;
        struct ad8801_state *state;
        const struct spi_device_id *id;
        int ret;

        indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*state));
        if (indio_dev == NULL)
                return -ENOMEM;

        state = iio_priv(indio_dev);
        state->spi = spi;
        id = spi_get_device_id(spi);

        ret = devm_regulator_get_enable_read_voltage(&spi->dev, "vrefh");
        if (ret < 0)
                return dev_err_probe(&spi->dev, ret,
                                     "failed to get Vrefh voltage\n");

        state->vrefh_mv = ret / 1000;

        if (id->driver_data == ID_AD8803) {
                ret = devm_regulator_get_enable_read_voltage(&spi->dev, "vrefl");
                if (ret < 0)
                        return dev_err_probe(&spi->dev, ret,
                                             "failed to get Vrefl voltage\n");

                state->vrefl_mv = ret / 1000;
        }

        indio_dev->info = &ad8801_info;
        indio_dev->modes = INDIO_DIRECT_MODE;
        indio_dev->channels = ad8801_channels;
        indio_dev->num_channels = ARRAY_SIZE(ad8801_channels);
        indio_dev->name = id->name;

        ret = devm_iio_device_register(&spi->dev, indio_dev);
        if (ret)
                return dev_err_probe(&spi->dev, ret,
                                     "Failed to register iio device\n");

        return 0;
}

static const struct spi_device_id ad8801_ids[] = {
        {"ad8801", ID_AD8801},
        {"ad8803", ID_AD8803},
        { }
};
MODULE_DEVICE_TABLE(spi, ad8801_ids);

static struct spi_driver ad8801_driver = {
        .driver = {
                .name   = "ad8801",
        },
        .probe          = ad8801_probe,
        .id_table       = ad8801_ids,
};
module_spi_driver(ad8801_driver);

MODULE_AUTHOR("Gwenhael Goavec-Merou <gwenhael.goavec-merou@trabucayre.com>");
MODULE_DESCRIPTION("Analog Devices AD8801/AD8803 DAC");
MODULE_LICENSE("GPL v2");