// SPDX-License-Identifier: GPL-2.0
/*
 * Industrial I/O driver for Microchip digital potentiometers
 * Copyright (c) 2018  Axentia Technologies AB
 * Author: Peter Rosin <peda@axentia.se>
 *
 * Datasheet: http://www.microchip.com/downloads/en/DeviceDoc/22147a.pdf
 *
 * DEVID        #Wipers #Positions      Resistor Opts (kOhm)
 * mcp4017      1       128             5, 10, 50, 100
 * mcp4018      1       128             5, 10, 50, 100
 * mcp4019      1       128             5, 10, 50, 100
 */

#include <linux/err.h>
#include <linux/i2c.h>
#include <linux/iio/iio.h>
#include <linux/module.h>
#include <linux/mod_devicetable.h>
#include <linux/property.h>

#define MCP4018_WIPER_MAX 127

struct mcp4018_cfg {
        int kohms;
};

enum mcp4018_type {
        MCP4018_502,
        MCP4018_103,
        MCP4018_503,
        MCP4018_104,
};

static const struct mcp4018_cfg mcp4018_cfg[] = {
        [MCP4018_502] = { .kohms =   5, },
        [MCP4018_103] = { .kohms =  10, },
        [MCP4018_503] = { .kohms =  50, },
        [MCP4018_104] = { .kohms = 100, },
};

struct mcp4018_data {
        struct i2c_client *client;
        const struct mcp4018_cfg *cfg;
};

static const struct iio_chan_spec mcp4018_channel = {
        .type = IIO_RESISTANCE,
        .indexed = 1,
        .output = 1,
        .channel = 0,
        .info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
        .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE),
};

static int mcp4018_read_raw(struct iio_dev *indio_dev,
                            struct iio_chan_spec const *chan,
                            int *val, int *val2, long mask)
{
        struct mcp4018_data *data = iio_priv(indio_dev);
        s32 ret;

        switch (mask) {
        case IIO_CHAN_INFO_RAW:
                ret = i2c_smbus_read_byte(data->client);
                if (ret < 0)
                        return ret;
                *val = ret;
                return IIO_VAL_INT;
        case IIO_CHAN_INFO_SCALE:
                *val = 1000 * data->cfg->kohms;
                *val2 = MCP4018_WIPER_MAX;
                return IIO_VAL_FRACTIONAL;
        }

        return -EINVAL;
}

static int mcp4018_write_raw(struct iio_dev *indio_dev,
                             struct iio_chan_spec const *chan,
                             int val, int val2, long mask)
{
        struct mcp4018_data *data = iio_priv(indio_dev);

        switch (mask) {
        case IIO_CHAN_INFO_RAW:
                if (val > MCP4018_WIPER_MAX || val < 0)
                        return -EINVAL;
                break;
        default:
                return -EINVAL;
        }

        return i2c_smbus_write_byte(data->client, val);
}

static const struct iio_info mcp4018_info = {
        .read_raw = mcp4018_read_raw,
        .write_raw = mcp4018_write_raw,
};

#define MCP4018_ID_TABLE(_name, cfg) {                          \
        .name = _name,                                          \
        .driver_data = (kernel_ulong_t)&mcp4018_cfg[cfg],       \
}

static const struct i2c_device_id mcp4018_id[] = {
        MCP4018_ID_TABLE("mcp4017-502", MCP4018_502),
        MCP4018_ID_TABLE("mcp4017-103", MCP4018_103),
        MCP4018_ID_TABLE("mcp4017-503", MCP4018_503),
        MCP4018_ID_TABLE("mcp4017-104", MCP4018_104),
        MCP4018_ID_TABLE("mcp4018-502", MCP4018_502),
        MCP4018_ID_TABLE("mcp4018-103", MCP4018_103),
        MCP4018_ID_TABLE("mcp4018-503", MCP4018_503),
        MCP4018_ID_TABLE("mcp4018-104", MCP4018_104),
        MCP4018_ID_TABLE("mcp4019-502", MCP4018_502),
        MCP4018_ID_TABLE("mcp4019-103", MCP4018_103),
        MCP4018_ID_TABLE("mcp4019-503", MCP4018_503),
        MCP4018_ID_TABLE("mcp4019-104", MCP4018_104),
        { }
};
MODULE_DEVICE_TABLE(i2c, mcp4018_id);

#define MCP4018_COMPATIBLE(of_compatible, cfg) {        \
        .compatible = of_compatible,                    \
        .data = &mcp4018_cfg[cfg],                      \
}

static const struct of_device_id mcp4018_of_match[] = {
        MCP4018_COMPATIBLE("microchip,mcp4017-502", MCP4018_502),
        MCP4018_COMPATIBLE("microchip,mcp4017-103", MCP4018_103),
        MCP4018_COMPATIBLE("microchip,mcp4017-503", MCP4018_503),
        MCP4018_COMPATIBLE("microchip,mcp4017-104", MCP4018_104),
        MCP4018_COMPATIBLE("microchip,mcp4018-502", MCP4018_502),
        MCP4018_COMPATIBLE("microchip,mcp4018-103", MCP4018_103),
        MCP4018_COMPATIBLE("microchip,mcp4018-503", MCP4018_503),
        MCP4018_COMPATIBLE("microchip,mcp4018-104", MCP4018_104),
        MCP4018_COMPATIBLE("microchip,mcp4019-502", MCP4018_502),
        MCP4018_COMPATIBLE("microchip,mcp4019-103", MCP4018_103),
        MCP4018_COMPATIBLE("microchip,mcp4019-503", MCP4018_503),
        MCP4018_COMPATIBLE("microchip,mcp4019-104", MCP4018_104),
        { }
};
MODULE_DEVICE_TABLE(of, mcp4018_of_match);

static int mcp4018_probe(struct i2c_client *client)
{
        struct device *dev = &client->dev;
        struct mcp4018_data *data;
        struct iio_dev *indio_dev;

        if (!i2c_check_functionality(client->adapter,
                                     I2C_FUNC_SMBUS_BYTE)) {
                dev_err(dev, "SMBUS Byte transfers not supported\n");
                return -EOPNOTSUPP;
        }

        indio_dev = devm_iio_device_alloc(dev, sizeof(*data));
        if (!indio_dev)
                return -ENOMEM;
        data = iio_priv(indio_dev);
        i2c_set_clientdata(client, indio_dev);
        data->client = client;

        data->cfg = i2c_get_match_data(client);

        indio_dev->info = &mcp4018_info;
        indio_dev->channels = &mcp4018_channel;
        indio_dev->num_channels = 1;
        indio_dev->name = client->name;

        return devm_iio_device_register(dev, indio_dev);
}

static struct i2c_driver mcp4018_driver = {
        .driver = {
                .name   = "mcp4018",
                .of_match_table = mcp4018_of_match,
        },
        .probe          = mcp4018_probe,
        .id_table       = mcp4018_id,
};

module_i2c_driver(mcp4018_driver);

MODULE_AUTHOR("Peter Rosin <peda@axentia.se>");
MODULE_DESCRIPTION("MCP4018 digital potentiometer");
MODULE_LICENSE("GPL v2");