// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * mcp4922.c
 *
 * Driver for Microchip Digital to Analog Converters.
 * Supports MCP4902, MCP4912, and MCP4922.
 *
 * Copyright (c) 2014 EMAC Inc.
 */

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

#define MCP4922_NUM_CHANNELS    2
#define MCP4921_NUM_CHANNELS    1

enum mcp4922_supported_device_ids {
        ID_MCP4902,
        ID_MCP4912,
        ID_MCP4921,
        ID_MCP4922,
};

struct mcp4922_state {
        struct spi_device *spi;
        unsigned int value[MCP4922_NUM_CHANNELS];
        unsigned int vref_mv;
        u8 mosi[2] __aligned(IIO_DMA_MINALIGN);
};

#define MCP4922_CHAN(chan, bits) {                      \
        .type = IIO_VOLTAGE,                            \
        .output = 1,                                    \
        .indexed = 1,                                   \
        .channel = chan,                                \
        .info_mask_separate = BIT(IIO_CHAN_INFO_RAW),   \
        .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE),   \
        .scan_type = {                                  \
                .sign = 'u',                            \
                .realbits = (bits),                     \
                .storagebits = 16,                      \
                .shift = 12 - (bits),                   \
        },                                              \
}

static int mcp4922_spi_write(struct mcp4922_state *state, u8 addr, u32 val)
{
        state->mosi[1] = val & 0xff;
        state->mosi[0] = (addr == 0) ? 0x00 : 0x80;
        state->mosi[0] |= 0x30 | ((val >> 8) & 0x0f);

        return spi_write(state->spi, state->mosi, 2);
}

static int mcp4922_read_raw(struct iio_dev *indio_dev,
                struct iio_chan_spec const *chan,
                int *val,
                int *val2,
                long mask)
{
        struct mcp4922_state *state = iio_priv(indio_dev);

        switch (mask) {
        case IIO_CHAN_INFO_RAW:
                *val = state->value[chan->channel];
                return IIO_VAL_INT;
        case IIO_CHAN_INFO_SCALE:
                *val = state->vref_mv;
                *val2 = chan->scan_type.realbits;
                return IIO_VAL_FRACTIONAL_LOG2;
        default:
                return -EINVAL;
        }
}

static int mcp4922_write_raw(struct iio_dev *indio_dev,
                struct iio_chan_spec const *chan,
                int val,
                int val2,
                long mask)
{
        struct mcp4922_state *state = iio_priv(indio_dev);
        int ret;

        if (val2 != 0)
                return -EINVAL;

        switch (mask) {
        case IIO_CHAN_INFO_RAW:
                if (val < 0 || val > GENMASK(chan->scan_type.realbits - 1, 0))
                        return -EINVAL;
                val <<= chan->scan_type.shift;

                ret = mcp4922_spi_write(state, chan->channel, val);
                if (!ret)
                        state->value[chan->channel] = val;
                return ret;

        default:
                return -EINVAL;
        }
}

static const struct iio_chan_spec mcp4922_channels[4][MCP4922_NUM_CHANNELS] = {
        [ID_MCP4902] = { MCP4922_CHAN(0, 8),    MCP4922_CHAN(1, 8) },
        [ID_MCP4912] = { MCP4922_CHAN(0, 10),   MCP4922_CHAN(1, 10) },
        [ID_MCP4921] = { MCP4922_CHAN(0, 12),   {} },
        [ID_MCP4922] = { MCP4922_CHAN(0, 12),   MCP4922_CHAN(1, 12) },
};

static const struct iio_info mcp4922_info = {
        .read_raw = &mcp4922_read_raw,
        .write_raw = &mcp4922_write_raw,
};

static int mcp4922_probe(struct spi_device *spi)
{
        struct iio_dev *indio_dev;
        struct mcp4922_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;

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

        state->vref_mv = ret / 1000;

        id = spi_get_device_id(spi);
        indio_dev->info = &mcp4922_info;
        indio_dev->modes = INDIO_DIRECT_MODE;
        indio_dev->channels = mcp4922_channels[id->driver_data];
        if (id->driver_data == ID_MCP4921)
                indio_dev->num_channels = MCP4921_NUM_CHANNELS;
        else
                indio_dev->num_channels = MCP4922_NUM_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 mcp4922_id[] = {
        {"mcp4902", ID_MCP4902},
        {"mcp4912", ID_MCP4912},
        {"mcp4921", ID_MCP4921},
        {"mcp4922", ID_MCP4922},
        { }
};
MODULE_DEVICE_TABLE(spi, mcp4922_id);

static struct spi_driver mcp4922_driver = {
        .driver = {
                   .name = "mcp4922",
                   },
        .probe = mcp4922_probe,
        .id_table = mcp4922_id,
};
module_spi_driver(mcp4922_driver);

MODULE_AUTHOR("Michael Welling <mwelling@ieee.org>");
MODULE_DESCRIPTION("Microchip MCP4902, MCP4912, MCP4922 DAC");
MODULE_LICENSE("GPL v2");