// SPDX-License-Identifier: GPL-2.0
/*
 * Copyright (c) 2016-2019 The Linux Foundation. All rights reserved.
 * Copyright (c) 2023, Linaro Limited
 */
#include <linux/delay.h>
#include <linux/i2c.h>
#include <linux/power_supply.h>
#include <linux/regmap.h>

#define REG_BATID                       0x00 /* This one is very unclear */
 #define BATID_101                      0x0101 /* 107kOhm */
 #define BATID_102                      0x0102 /* 10kOhm */
#define REG_TEMPERATURE                 0x06
#define REG_VOLTAGE                     0x08
#define REG_FLAGS                       0x0a
 #define MM8013_FLAG_OTC                BIT(15)
 #define MM8013_FLAG_OTD                BIT(14)
 #define MM8013_FLAG_BATHI              BIT(13)
 #define MM8013_FLAG_BATLOW             BIT(12)
 #define MM8013_FLAG_CHG_INH            BIT(11)
 #define MM8013_FLAG_FC                 BIT(9)
 #define MM8013_FLAG_CHG                BIT(8)
 #define MM8013_FLAG_OCC                BIT(6)
 #define MM8013_FLAG_ODC                BIT(5)
 #define MM8013_FLAG_OT                 BIT(4)
 #define MM8013_FLAG_UT                 BIT(3)
 #define MM8013_FLAG_DSG                BIT(0)
#define REG_FULL_CHARGE_CAPACITY        0x0e
#define REG_NOMINAL_CHARGE_CAPACITY     0x0c
#define REG_AVERAGE_CURRENT             0x14
#define REG_AVERAGE_TIME_TO_EMPTY       0x16
#define REG_AVERAGE_TIME_TO_FULL        0x18
#define REG_MAX_LOAD_CURRENT            0x1e
#define REG_CYCLE_COUNT                 0x2a
#define REG_STATE_OF_CHARGE             0x2c
#define REG_DESIGN_CAPACITY             0x3c
/* TODO: 0x62-0x68 seem to contain 'MM8013C' in a length-prefixed, non-terminated string */

#define DECIKELVIN_TO_DECIDEGC(t)       (t - 2731)

struct mm8013_chip {
        struct i2c_client *client;
        struct regmap *regmap;
};

static int mm8013_checkdevice(struct mm8013_chip *chip)
{
        int battery_id, ret;
        u32 val;

        ret = regmap_write(chip->regmap, REG_BATID, 0x0008);
        if (ret < 0)
                return ret;

        ret = regmap_read(chip->regmap, REG_BATID, &val);
        if (ret < 0)
                return ret;

        if (val == BATID_102)
                battery_id = 2;
        else if (val == BATID_101)
                battery_id = 1;
        else
                return -EINVAL;

        dev_dbg(&chip->client->dev, "battery_id: %d\n", battery_id);

        return 0;
}

static enum power_supply_property mm8013_battery_props[] = {
        POWER_SUPPLY_PROP_CAPACITY,
        POWER_SUPPLY_PROP_CHARGE_FULL,
        POWER_SUPPLY_PROP_CHARGE_FULL_DESIGN,
        POWER_SUPPLY_PROP_CHARGE_NOW,
        POWER_SUPPLY_PROP_CURRENT_MAX,
        POWER_SUPPLY_PROP_CURRENT_NOW,
        POWER_SUPPLY_PROP_CYCLE_COUNT,
        POWER_SUPPLY_PROP_HEALTH,
        POWER_SUPPLY_PROP_PRESENT,
        POWER_SUPPLY_PROP_STATUS,
        POWER_SUPPLY_PROP_TEMP,
        POWER_SUPPLY_PROP_TIME_TO_EMPTY_AVG,
        POWER_SUPPLY_PROP_TIME_TO_FULL_AVG,
        POWER_SUPPLY_PROP_VOLTAGE_NOW,
};

static int mm8013_get_property(struct power_supply *psy,
                               enum power_supply_property psp,
                               union power_supply_propval *val)
{
        struct mm8013_chip *chip = power_supply_get_drvdata(psy);
        int ret = 0;
        u32 regval;

        switch (psp) {
        case POWER_SUPPLY_PROP_CAPACITY:
                ret = regmap_read(chip->regmap, REG_STATE_OF_CHARGE, &regval);
                if (ret < 0)
                        return ret;

                val->intval = regval;
                break;
        case POWER_SUPPLY_PROP_CHARGE_FULL:
                ret = regmap_read(chip->regmap, REG_FULL_CHARGE_CAPACITY, &regval);
                if (ret < 0)
                        return ret;

                val->intval = 1000 * regval;
                break;
        case POWER_SUPPLY_PROP_CHARGE_FULL_DESIGN:
                ret = regmap_read(chip->regmap, REG_DESIGN_CAPACITY, &regval);
                if (ret < 0)
                        return ret;

                val->intval = 1000 * regval;
                break;
        case POWER_SUPPLY_PROP_CHARGE_NOW:
                ret = regmap_read(chip->regmap, REG_NOMINAL_CHARGE_CAPACITY, &regval);
                if (ret < 0)
                        return ret;

                val->intval = 1000 * regval;
                break;
        case POWER_SUPPLY_PROP_CURRENT_MAX:
                ret = regmap_read(chip->regmap, REG_MAX_LOAD_CURRENT, &regval);
                if (ret < 0)
                        return ret;

                val->intval = -1000 * (s16)regval;
                break;
        case POWER_SUPPLY_PROP_CURRENT_NOW:
                ret = regmap_read(chip->regmap, REG_AVERAGE_CURRENT, &regval);
                if (ret < 0)
                        return ret;

                val->intval = -1000 * (s16)regval;
                break;
        case POWER_SUPPLY_PROP_CYCLE_COUNT:
                ret = regmap_read(chip->regmap, REG_CYCLE_COUNT, &regval);
                if (ret < 0)
                        return ret;

                val->intval = regval;
                break;
        case POWER_SUPPLY_PROP_HEALTH:
                ret = regmap_read(chip->regmap, REG_FLAGS, &regval);
                if (ret < 0)
                        return ret;

                if (regval & MM8013_FLAG_UT)
                        val->intval = POWER_SUPPLY_HEALTH_COLD;
                else if (regval & (MM8013_FLAG_ODC | MM8013_FLAG_OCC))
                        val->intval = POWER_SUPPLY_HEALTH_OVERCURRENT;
                else if (regval & (MM8013_FLAG_BATLOW))
                        val->intval = POWER_SUPPLY_HEALTH_UNSPEC_FAILURE;
                else if (regval & MM8013_FLAG_BATHI)
                        val->intval = POWER_SUPPLY_HEALTH_OVERVOLTAGE;
                else if (regval & (MM8013_FLAG_OT | MM8013_FLAG_OTD | MM8013_FLAG_OTC))
                        val->intval = POWER_SUPPLY_HEALTH_OVERHEAT;
                else
                        val->intval = POWER_SUPPLY_HEALTH_GOOD;
                break;
        case POWER_SUPPLY_PROP_PRESENT:
                ret = regmap_read(chip->regmap, REG_TEMPERATURE, &regval);
                if (ret < 0)
                        return ret;

                val->intval = ((s16)regval > 0);
                break;
        case POWER_SUPPLY_PROP_STATUS:
                ret = regmap_read(chip->regmap, REG_FLAGS, &regval);
                if (ret < 0)
                        return ret;

                if (regval & MM8013_FLAG_DSG)
                        val->intval = POWER_SUPPLY_STATUS_DISCHARGING;
                else if (regval & MM8013_FLAG_CHG_INH)
                        val->intval = POWER_SUPPLY_STATUS_NOT_CHARGING;
                else if (regval & MM8013_FLAG_CHG)
                        val->intval = POWER_SUPPLY_STATUS_CHARGING;
                else if (regval & MM8013_FLAG_FC)
                        val->intval = POWER_SUPPLY_STATUS_FULL;
                else
                        val->intval = POWER_SUPPLY_STATUS_UNKNOWN;
                break;
        case POWER_SUPPLY_PROP_TEMP:
                ret = regmap_read(chip->regmap, REG_TEMPERATURE, &regval);
                if (ret < 0)
                        return ret;

                val->intval = DECIKELVIN_TO_DECIDEGC(regval);
                break;
        case POWER_SUPPLY_PROP_TIME_TO_EMPTY_AVG:
                ret = regmap_read(chip->regmap, REG_AVERAGE_TIME_TO_EMPTY, &regval);
                if (ret < 0)
                        return ret;

                /* The estimation is not yet ready */
                if (regval == U16_MAX)
                        return -ENODATA;

                val->intval = regval;
                break;
        case POWER_SUPPLY_PROP_TIME_TO_FULL_AVG:
                ret = regmap_read(chip->regmap, REG_AVERAGE_TIME_TO_FULL, &regval);
                if (ret < 0)
                        return ret;

                /* The estimation is not yet ready */
                if (regval == U16_MAX)
                        return -ENODATA;

                val->intval = regval;
                break;
        case POWER_SUPPLY_PROP_VOLTAGE_NOW:
                ret = regmap_read(chip->regmap, REG_VOLTAGE, &regval);
                if (ret < 0)
                        return ret;

                val->intval = 1000 * regval;
                break;
        default:
                return -EINVAL;
        }

        return 0;
}

static const struct power_supply_desc mm8013_desc = {
        .name                   = "mm8013",
        .type                   = POWER_SUPPLY_TYPE_BATTERY,
        .properties             = mm8013_battery_props,
        .num_properties         = ARRAY_SIZE(mm8013_battery_props),
        .get_property           = mm8013_get_property,
};

static const struct regmap_config mm8013_regmap_config = {
        .reg_bits = 8,
        .val_bits = 16,
        .max_register = 0x68,
        .use_single_read = true,
        .use_single_write = true,
        .val_format_endian = REGMAP_ENDIAN_LITTLE,
};

static int mm8013_probe(struct i2c_client *client)
{
        struct power_supply_config psy_cfg = {};
        struct device *dev = &client->dev;
        struct power_supply *psy;
        struct mm8013_chip *chip;
        int ret = 0;

        if (!i2c_check_functionality(client->adapter, I2C_FUNC_SMBUS_WORD_DATA))
                return dev_err_probe(dev, -EIO,
                                     "I2C_FUNC_SMBUS_WORD_DATA not supported\n");

        chip = devm_kzalloc(dev, sizeof(struct mm8013_chip), GFP_KERNEL);
        if (!chip)
                return -ENOMEM;

        chip->client = client;

        chip->regmap = devm_regmap_init_i2c(client, &mm8013_regmap_config);
        if (IS_ERR(chip->regmap)) {
                ret = PTR_ERR(chip->regmap);
                return dev_err_probe(dev, ret, "Couldn't initialize regmap\n");
        }

        ret = mm8013_checkdevice(chip);
        if (ret)
                return dev_err_probe(dev, ret, "MM8013 not found\n");

        psy_cfg.drv_data = chip;
        psy_cfg.fwnode = dev_fwnode(dev);

        psy = devm_power_supply_register(dev, &mm8013_desc, &psy_cfg);
        if (IS_ERR(psy))
                return PTR_ERR(psy);

        return 0;
}

static const struct i2c_device_id mm8013_id_table[] = {
        { "mm8013" },
        {}
};
MODULE_DEVICE_TABLE(i2c, mm8013_id_table);

static const struct of_device_id mm8013_match_table[] = {
        { .compatible = "mitsumi,mm8013" },
        {}
};

static struct i2c_driver mm8013_i2c_driver = {
        .probe = mm8013_probe,
        .id_table = mm8013_id_table,
        .driver = {
                .name = "mm8013",
                .of_match_table = mm8013_match_table,
        },
};
module_i2c_driver(mm8013_i2c_driver);

MODULE_DESCRIPTION("MM8013 fuel gauge driver");
MODULE_LICENSE("GPL");