// SPDX-License-Identifier: GPL-2.0-only
/*
 * tsys01.c - Support for Measurement-Specialties tsys01 temperature sensor
 *
 * Copyright (c) 2015 Measurement-Specialties
 *
 * Datasheet:
 *  http://www.meas-spec.com/downloads/TSYS01_Digital_Temperature_Sensor.pdf
 */

#include <linux/iio/iio.h>
#include <linux/iio/sysfs.h>
#include <linux/device.h>
#include <linux/mutex.h>
#include <linux/module.h>
#include <linux/mod_devicetable.h>
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/stat.h>
#include "../common/ms_sensors/ms_sensors_i2c.h"

/* TSYS01 Commands */
#define TSYS01_RESET                            0x1E
#define TSYS01_CONVERSION_START                 0x48
#define TSYS01_ADC_READ                         0x00
#define TSYS01_PROM_READ                        0xA0

#define TSYS01_PROM_WORDS_NB                    8

struct tsys01_dev {
        void *client;
        struct mutex lock; /* lock during conversion */

        int (*reset)(void *cli, u8 cmd, unsigned int delay);
        int (*convert_and_read)(void *cli, u8 conv, u8 rd,
                                unsigned int delay, u32 *adc);
        int (*read_prom_word)(void *cli, int cmd, u16 *word);

        u16 prom[TSYS01_PROM_WORDS_NB];
};

/* Multiplication coefficients for temperature computation */
static const int coeff_mul[] = { -1500000, 1000000, -2000000,
                                 4000000, -2000000 };

static int tsys01_read_temperature(struct iio_dev *indio_dev,
                                   s32 *temperature)
{
        int ret, i;
        u32 adc;
        s64 temp = 0;
        struct tsys01_dev *dev_data = iio_priv(indio_dev);

        mutex_lock(&dev_data->lock);
        ret = dev_data->convert_and_read(dev_data->client,
                                         TSYS01_CONVERSION_START,
                                         TSYS01_ADC_READ, 9000, &adc);
        mutex_unlock(&dev_data->lock);
        if (ret)
                return ret;

        adc >>= 8;

        /* Temperature algorithm */
        for (i = 4; i > 0; i--) {
                temp += coeff_mul[i] *
                        (s64)dev_data->prom[5 - i];
                temp *= (s64)adc;
                temp = div64_s64(temp, 100000);
        }
        temp *= 10;
        temp += coeff_mul[0] * (s64)dev_data->prom[5];
        temp = div64_s64(temp, 100000);

        *temperature = temp;

        return 0;
}

static int tsys01_read_raw(struct iio_dev *indio_dev,
                           struct iio_chan_spec const *channel, int *val,
                           int *val2, long mask)
{
        int ret;
        s32 temperature;

        switch (mask) {
        case IIO_CHAN_INFO_PROCESSED:
                switch (channel->type) {
                case IIO_TEMP:  /* in milli °C */
                        ret = tsys01_read_temperature(indio_dev, &temperature);
                        if (ret)
                                return ret;
                        *val = temperature;

                        return IIO_VAL_INT;
                default:
                        return -EINVAL;
                }
        default:
                return -EINVAL;
        }
}

static const struct iio_chan_spec tsys01_channels[] = {
        {
                .type = IIO_TEMP,
                .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_PROCESSED),
        }
};

static const struct iio_info tsys01_info = {
        .read_raw = tsys01_read_raw,
};

static bool tsys01_crc_valid(u16 *n_prom)
{
        u8 cnt;
        u8 sum = 0;

        for (cnt = 0; cnt < TSYS01_PROM_WORDS_NB; cnt++)
                sum += ((n_prom[0] >> 8) + (n_prom[0] & 0xFF));

        return (sum == 0);
}

static int tsys01_read_prom(struct iio_dev *indio_dev)
{
        int i, ret;
        struct tsys01_dev *dev_data = iio_priv(indio_dev);
        char buf[7 * TSYS01_PROM_WORDS_NB + 1];
        char *ptr = buf;

        for (i = 0; i < TSYS01_PROM_WORDS_NB; i++) {
                ret = dev_data->read_prom_word(dev_data->client,
                                               TSYS01_PROM_READ + (i << 1),
                                               &dev_data->prom[i]);
                if (ret)
                        return ret;

                ret = sprintf(ptr, "0x%04x ", dev_data->prom[i]);
                ptr += ret;
        }

        if (!tsys01_crc_valid(dev_data->prom)) {
                dev_err(&indio_dev->dev, "prom crc check error\n");
                return -ENODEV;
        }
        *ptr = 0;
        dev_info(&indio_dev->dev, "PROM coefficients : %s\n", buf);

        return 0;
}

static int tsys01_probe(struct iio_dev *indio_dev, struct device *dev)
{
        int ret;
        struct tsys01_dev *dev_data = iio_priv(indio_dev);

        mutex_init(&dev_data->lock);

        indio_dev->info = &tsys01_info;
        indio_dev->name = dev->driver->name;
        indio_dev->modes = INDIO_DIRECT_MODE;
        indio_dev->channels = tsys01_channels;
        indio_dev->num_channels = ARRAY_SIZE(tsys01_channels);

        ret = dev_data->reset(dev_data->client, TSYS01_RESET, 3000);
        if (ret)
                return ret;

        ret = tsys01_read_prom(indio_dev);
        if (ret)
                return ret;

        return devm_iio_device_register(dev, indio_dev);
}

static int tsys01_i2c_probe(struct i2c_client *client)
{
        struct tsys01_dev *dev_data;
        struct iio_dev *indio_dev;

        if (!i2c_check_functionality(client->adapter,
                                     I2C_FUNC_SMBUS_WORD_DATA |
                                     I2C_FUNC_SMBUS_WRITE_BYTE |
                                     I2C_FUNC_SMBUS_READ_I2C_BLOCK)) {
                dev_err(&client->dev,
                        "Adapter does not support some i2c transaction\n");
                return -EOPNOTSUPP;
        }

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

        dev_data = iio_priv(indio_dev);
        dev_data->client = client;
        dev_data->reset = ms_sensors_reset;
        dev_data->read_prom_word = ms_sensors_read_prom_word;
        dev_data->convert_and_read = ms_sensors_convert_and_read;

        i2c_set_clientdata(client, indio_dev);

        return tsys01_probe(indio_dev, &client->dev);
}

static const struct i2c_device_id tsys01_id[] = {
        { "tsys01" },
        { }
};
MODULE_DEVICE_TABLE(i2c, tsys01_id);

static const struct of_device_id tsys01_of_match[] = {
        { .compatible = "meas,tsys01", },
        { }
};
MODULE_DEVICE_TABLE(of, tsys01_of_match);

static struct i2c_driver tsys01_driver = {
        .probe = tsys01_i2c_probe,
        .id_table = tsys01_id,
        .driver = {
                   .name = "tsys01",
                   .of_match_table = tsys01_of_match,
                   },
};

module_i2c_driver(tsys01_driver);

MODULE_DESCRIPTION("Measurement-Specialties tsys01 temperature driver");
MODULE_AUTHOR("William Markezana <william.markezana@meas-spec.com>");
MODULE_AUTHOR("Ludovic Tancerel <ludovic.tancerel@maplehightech.com>");
MODULE_LICENSE("GPL v2");
MODULE_IMPORT_NS("IIO_MEAS_SPEC_SENSORS");