// SPDX-License-Identifier: GPL-2.0+
/*
 * atlas-ezo-sensor.c - Support for Atlas Scientific EZO sensors
 *
 * Copyright (C) 2020 Konsulko Group
 * Author: Matt Ranostay <matt.ranostay@konsulko.com>
 */

#include <linux/init.h>
#include <linux/delay.h>
#include <linux/mod_devicetable.h>
#include <linux/module.h>
#include <linux/mutex.h>
#include <linux/property.h>
#include <linux/err.h>
#include <linux/i2c.h>

#include <linux/iio/iio.h>

#define ATLAS_EZO_DRV_NAME              "atlas-ezo-sensor"
#define ATLAS_INT_TIME_IN_MS            950
#define ATLAS_INT_HUM_TIME_IN_MS        350

enum {
        ATLAS_CO2_EZO,
        ATLAS_O2_EZO,
        ATLAS_HUM_EZO,
};

struct atlas_ezo_device {
        const struct iio_chan_spec *channels;
        int num_channels;
        int delay;
};

struct atlas_ezo_data {
        struct i2c_client *client;
        const struct atlas_ezo_device *chip;

        /* lock to avoid multiple concurrent read calls */
        struct mutex lock;

        u8 buffer[8];
};

#define ATLAS_CONCENTRATION_CHANNEL(_modifier) \
        { \
                .type = IIO_CONCENTRATION, \
                .modified = 1,\
                .channel2 = _modifier, \
                .info_mask_separate = \
                        BIT(IIO_CHAN_INFO_RAW) | BIT(IIO_CHAN_INFO_SCALE), \
                .scan_index = 0, \
                .scan_type =  { \
                        .sign = 'u', \
                        .realbits = 32, \
                        .storagebits = 32, \
                        .endianness = IIO_CPU, \
                }, \
        }

static const struct iio_chan_spec atlas_co2_ezo_channels[] = {
        ATLAS_CONCENTRATION_CHANNEL(IIO_MOD_CO2),
};

static const struct iio_chan_spec atlas_o2_ezo_channels[] = {
        ATLAS_CONCENTRATION_CHANNEL(IIO_MOD_O2),
};

static const struct iio_chan_spec atlas_hum_ezo_channels[] = {
        {
                .type = IIO_HUMIDITYRELATIVE,
                .info_mask_separate =
                        BIT(IIO_CHAN_INFO_RAW) | BIT(IIO_CHAN_INFO_SCALE),
                .scan_index = 0,
                .scan_type =  {
                        .sign = 'u',
                        .realbits = 32,
                        .storagebits = 32,
                        .endianness = IIO_CPU,
                },
        },
};

static const struct atlas_ezo_device atlas_ezo_devices[] = {
        [ATLAS_CO2_EZO] = {
                .channels = atlas_co2_ezo_channels,
                .num_channels = 1,
                .delay = ATLAS_INT_TIME_IN_MS,
        },
        [ATLAS_O2_EZO] = {
                .channels = atlas_o2_ezo_channels,
                .num_channels = 1,
                .delay = ATLAS_INT_TIME_IN_MS,
        },
        [ATLAS_HUM_EZO] = {
                .channels = atlas_hum_ezo_channels,
                .num_channels = 1,
                .delay = ATLAS_INT_HUM_TIME_IN_MS,
        },
};

static void atlas_ezo_sanitize(char *buf)
{
        char *ptr = strchr(buf, '.');

        if (!ptr)
                return;

        memmove(ptr, ptr + 1, strlen(ptr));
}

static int atlas_ezo_read_raw(struct iio_dev *indio_dev,
                          struct iio_chan_spec const *chan,
                          int *val, int *val2, long mask)
{
        struct atlas_ezo_data *data = iio_priv(indio_dev);
        struct i2c_client *client = data->client;

        if (chan->type != IIO_CONCENTRATION)
                return -EINVAL;

        switch (mask) {
        case IIO_CHAN_INFO_RAW: {
                int ret;
                long tmp;

                mutex_lock(&data->lock);

                tmp = i2c_smbus_write_byte(client, 'R');

                if (tmp < 0) {
                        mutex_unlock(&data->lock);
                        return tmp;
                }

                msleep(data->chip->delay);

                tmp = i2c_master_recv(client, data->buffer, sizeof(data->buffer));

                if (tmp < 0 || data->buffer[0] != 1) {
                        mutex_unlock(&data->lock);
                        return -EBUSY;
                }

                /* removing floating point for fixed number representation */
                atlas_ezo_sanitize(data->buffer + 2);

                ret = kstrtol(data->buffer + 1, 10, &tmp);

                *val = tmp;

                mutex_unlock(&data->lock);

                return ret ? ret : IIO_VAL_INT;
        }
        case IIO_CHAN_INFO_SCALE:
                switch (chan->type) {
                case IIO_HUMIDITYRELATIVE:
                        *val = 10;
                        return IIO_VAL_INT;
                case IIO_CONCENTRATION:
                        break;
                default:
                        return -EINVAL;
                }

                /* IIO_CONCENTRATION modifiers */
                switch (chan->channel2) {
                case IIO_MOD_CO2:
                        *val = 0;
                        *val2 = 100; /* 0.0001 */
                        return IIO_VAL_INT_PLUS_MICRO;
                case IIO_MOD_O2:
                        *val = 100;
                        return IIO_VAL_INT;
                }
                return -EINVAL;
        }

        return 0;
}

static const struct iio_info atlas_info = {
        .read_raw = atlas_ezo_read_raw,
};

static const struct i2c_device_id atlas_ezo_id[] = {
        { "atlas-co2-ezo", (kernel_ulong_t)&atlas_ezo_devices[ATLAS_CO2_EZO] },
        { "atlas-o2-ezo", (kernel_ulong_t)&atlas_ezo_devices[ATLAS_O2_EZO] },
        { "atlas-hum-ezo", (kernel_ulong_t)&atlas_ezo_devices[ATLAS_HUM_EZO] },
        { }
};
MODULE_DEVICE_TABLE(i2c, atlas_ezo_id);

static const struct of_device_id atlas_ezo_dt_ids[] = {
        { .compatible = "atlas,co2-ezo", .data = &atlas_ezo_devices[ATLAS_CO2_EZO], },
        { .compatible = "atlas,o2-ezo", .data = &atlas_ezo_devices[ATLAS_O2_EZO], },
        { .compatible = "atlas,hum-ezo", .data = &atlas_ezo_devices[ATLAS_HUM_EZO], },
        { }
};
MODULE_DEVICE_TABLE(of, atlas_ezo_dt_ids);

static int atlas_ezo_probe(struct i2c_client *client)
{
        const struct atlas_ezo_device *chip;
        struct atlas_ezo_data *data;
        struct iio_dev *indio_dev;

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

        chip = i2c_get_match_data(client);
        if (!chip)
                return -EINVAL;

        indio_dev->info = &atlas_info;
        indio_dev->name = ATLAS_EZO_DRV_NAME;
        indio_dev->channels = chip->channels;
        indio_dev->num_channels = chip->num_channels;
        indio_dev->modes = INDIO_DIRECT_MODE;

        data = iio_priv(indio_dev);
        data->client = client;
        data->chip = chip;
        mutex_init(&data->lock);

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

static struct i2c_driver atlas_ezo_driver = {
        .driver = {
                .name   = ATLAS_EZO_DRV_NAME,
                .of_match_table = atlas_ezo_dt_ids,
        },
        .probe          = atlas_ezo_probe,
        .id_table       = atlas_ezo_id,
};
module_i2c_driver(atlas_ezo_driver);

MODULE_AUTHOR("Matt Ranostay <matt.ranostay@konsulko.com>");
MODULE_DESCRIPTION("Atlas Scientific EZO sensors");
MODULE_LICENSE("GPL");