// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * Copyright (C) 2017 IBM Corp.
 *
 * Driver for the Nuvoton W83773G SMBus temperature sensor IC.
 * Supported models: W83773G
 */

#include <linux/module.h>
#include <linux/init.h>
#include <linux/i2c.h>
#include <linux/hwmon.h>
#include <linux/hwmon-sysfs.h>
#include <linux/err.h>
#include <linux/of.h>
#include <linux/regmap.h>

/* W83773 has 3 channels */
#define W83773_CHANNELS                         3

/* The W83773 registers */
#define W83773_CONVERSION_RATE_REG_READ         0x04
#define W83773_CONVERSION_RATE_REG_WRITE        0x0A
#define W83773_MANUFACTURER_ID_REG              0xFE
#define W83773_LOCAL_TEMP                       0x00

static const u8 W83773_STATUS[2] = { 0x02, 0x17 };

static const u8 W83773_TEMP_LSB[2] = { 0x10, 0x25 };
static const u8 W83773_TEMP_MSB[2] = { 0x01, 0x24 };

static const u8 W83773_OFFSET_LSB[2] = { 0x12, 0x16 };
static const u8 W83773_OFFSET_MSB[2] = { 0x11, 0x15 };

/* this is the number of sensors in the device */
static const struct i2c_device_id w83773_id[] = {
        { "w83773g" },
        { }
};

MODULE_DEVICE_TABLE(i2c, w83773_id);

static const struct of_device_id __maybe_unused w83773_of_match[] = {
        {
                .compatible = "nuvoton,w83773g"
        },
        { },
};
MODULE_DEVICE_TABLE(of, w83773_of_match);

static inline long temp_of_local(s8 reg)
{
        return reg * 1000;
}

static inline long temp_of_remote(s8 hb, u8 lb)
{
        return (hb << 3 | lb >> 5) * 125;
}

static int get_local_temp(struct regmap *regmap, long *val)
{
        unsigned int regval;
        int ret;

        ret = regmap_read(regmap, W83773_LOCAL_TEMP, &regval);
        if (ret < 0)
                return ret;

        *val = temp_of_local(regval);
        return 0;
}

static int get_remote_temp(struct regmap *regmap, int index, long *val)
{
        unsigned int regval_high;
        unsigned int regval_low;
        int ret;

        ret = regmap_read(regmap, W83773_TEMP_MSB[index], &regval_high);
        if (ret < 0)
                return ret;

        ret = regmap_read(regmap, W83773_TEMP_LSB[index], &regval_low);
        if (ret < 0)
                return ret;

        *val = temp_of_remote(regval_high, regval_low);
        return 0;
}

static int get_fault(struct regmap *regmap, int index, long *val)
{
        unsigned int regval;
        int ret;

        ret = regmap_read(regmap, W83773_STATUS[index], &regval);
        if (ret < 0)
                return ret;

        *val = (regval & 0x04) >> 2;
        return 0;
}

static int get_offset(struct regmap *regmap, int index, long *val)
{
        unsigned int regval_high;
        unsigned int regval_low;
        int ret;

        ret = regmap_read(regmap, W83773_OFFSET_MSB[index], &regval_high);
        if (ret < 0)
                return ret;

        ret = regmap_read(regmap, W83773_OFFSET_LSB[index], &regval_low);
        if (ret < 0)
                return ret;

        *val = temp_of_remote(regval_high, regval_low);
        return 0;
}

static int set_offset(struct regmap *regmap, int index, long val)
{
        int ret;
        u8 high_byte;
        u8 low_byte;

        val = clamp_val(val, -127825, 127825);
        /* offset value equals to (high_byte << 3 | low_byte >> 5) * 125 */
        val /= 125;
        high_byte = val >> 3;
        low_byte = (val & 0x07) << 5;

        ret = regmap_write(regmap, W83773_OFFSET_MSB[index], high_byte);
        if (ret < 0)
                return ret;

        return regmap_write(regmap, W83773_OFFSET_LSB[index], low_byte);
}

static int get_update_interval(struct regmap *regmap, long *val)
{
        unsigned int regval;
        int ret;

        ret = regmap_read(regmap, W83773_CONVERSION_RATE_REG_READ, &regval);
        if (ret < 0)
                return ret;

        *val = 16000 >> regval;
        return 0;
}

static int set_update_interval(struct regmap *regmap, long val)
{
        int rate;

        /*
         * For valid rates, interval can be calculated as
         *      interval = (1 << (8 - rate)) * 62.5;
         * Rounded rate is therefore
         *      rate = 8 - __fls(interval * 8 / (62.5 * 7));
         * Use clamp_val() to avoid overflows, and to ensure valid input
         * for __fls.
         */
        val = clamp_val(val, 62, 16000) * 10;
        rate = 8 - __fls((val * 8 / (625 * 7)));
        return regmap_write(regmap, W83773_CONVERSION_RATE_REG_WRITE, rate);
}

static int w83773_read(struct device *dev, enum hwmon_sensor_types type,
                       u32 attr, int channel, long *val)
{
        struct regmap *regmap = dev_get_drvdata(dev);

        if (type == hwmon_chip) {
                if (attr == hwmon_chip_update_interval)
                        return get_update_interval(regmap, val);
                return -EOPNOTSUPP;
        }

        switch (attr) {
        case hwmon_temp_input:
                if (channel == 0)
                        return get_local_temp(regmap, val);
                return get_remote_temp(regmap, channel - 1, val);
        case hwmon_temp_fault:
                return get_fault(regmap, channel - 1, val);
        case hwmon_temp_offset:
                return get_offset(regmap, channel - 1, val);
        default:
                return -EOPNOTSUPP;
        }
}

static int w83773_write(struct device *dev, enum hwmon_sensor_types type,
                        u32 attr, int channel, long val)
{
        struct regmap *regmap = dev_get_drvdata(dev);

        if (type == hwmon_chip && attr == hwmon_chip_update_interval)
                return set_update_interval(regmap, val);

        if (type == hwmon_temp && attr == hwmon_temp_offset)
                return set_offset(regmap, channel - 1, val);

        return -EOPNOTSUPP;
}

static umode_t w83773_is_visible(const void *data, enum hwmon_sensor_types type,
                                 u32 attr, int channel)
{
        switch (type) {
        case hwmon_chip:
                switch (attr) {
                case hwmon_chip_update_interval:
                        return 0644;
                }
                break;
        case hwmon_temp:
                switch (attr) {
                case hwmon_temp_input:
                case hwmon_temp_fault:
                        return 0444;
                case hwmon_temp_offset:
                        return 0644;
                }
                break;
        default:
                break;
        }
        return 0;
}

static const struct hwmon_channel_info * const w83773_info[] = {
        HWMON_CHANNEL_INFO(chip,
                           HWMON_C_REGISTER_TZ | HWMON_C_UPDATE_INTERVAL),
        HWMON_CHANNEL_INFO(temp,
                           HWMON_T_INPUT,
                           HWMON_T_INPUT | HWMON_T_FAULT | HWMON_T_OFFSET,
                           HWMON_T_INPUT | HWMON_T_FAULT | HWMON_T_OFFSET),
        NULL
};

static const struct hwmon_ops w83773_ops = {
        .is_visible = w83773_is_visible,
        .read = w83773_read,
        .write = w83773_write,
};

static const struct hwmon_chip_info w83773_chip_info = {
        .ops = &w83773_ops,
        .info = w83773_info,
};

static const struct regmap_config w83773_regmap_config = {
        .reg_bits = 8,
        .val_bits = 8,
};

static int w83773_probe(struct i2c_client *client)
{
        struct device *dev = &client->dev;
        struct device *hwmon_dev;
        struct regmap *regmap;
        int ret;

        regmap = devm_regmap_init_i2c(client, &w83773_regmap_config);
        if (IS_ERR(regmap)) {
                dev_err(dev, "failed to allocate register map\n");
                return PTR_ERR(regmap);
        }

        /* Set the conversion rate to 2 Hz */
        ret = regmap_write(regmap, W83773_CONVERSION_RATE_REG_WRITE, 0x05);
        if (ret < 0) {
                dev_err(&client->dev, "error writing config rate register\n");
                return ret;
        }

        i2c_set_clientdata(client, regmap);

        hwmon_dev = devm_hwmon_device_register_with_info(dev,
                                                         client->name,
                                                         regmap,
                                                         &w83773_chip_info,
                                                         NULL);
        return PTR_ERR_OR_ZERO(hwmon_dev);
}

static struct i2c_driver w83773_driver = {
        .driver = {
                .name   = "w83773g",
                .of_match_table = of_match_ptr(w83773_of_match),
        },
        .probe = w83773_probe,
        .id_table = w83773_id,
};

module_i2c_driver(w83773_driver);

MODULE_AUTHOR("Lei YU <mine260309@gmail.com>");
MODULE_DESCRIPTION("W83773G temperature sensor driver");
MODULE_LICENSE("GPL");