// SPDX-License-Identifier: GPL-2.0
/*
 * stc3117_fuel_gauge.c - STMicroelectronics STC3117 Fuel Gauge Driver
 *
 * Copyright (c) 2024 Silicon Signals Pvt Ltd.
 * Author:      Hardevsinh Palaniya <hardevsinh.palaniya@siliconsignals.io>
 *              Bhavin Sharma <bhavin.sharma@siliconsignals.io>
 */

#include <linux/crc8.h>
#include <linux/devm-helpers.h>
#include <linux/i2c.h>
#include <linux/power_supply.h>
#include <linux/regmap.h>
#include <linux/workqueue.h>

#define STC3117_ADDR_MODE                      0x00
#define STC3117_ADDR_CTRL                      0x01
#define STC3117_ADDR_SOC_L                     0x02
#define STC3117_ADDR_SOC_H                     0x03
#define STC3117_ADDR_COUNTER_L                 0x04
#define STC3117_ADDR_COUNTER_H                 0x05
#define STC3117_ADDR_CURRENT_L                 0x06
#define STC3117_ADDR_CURRENT_H                 0x07
#define STC3117_ADDR_VOLTAGE_L                 0x08
#define STC3117_ADDR_VOLTAGE_H                 0x09
#define STC3117_ADDR_TEMPERATURE               0x0A
#define STC3117_ADDR_AVG_CURRENT_L             0x0B
#define STC3117_ADDR_AVG_CURRENT_H             0x0C
#define STC3117_ADDR_OCV_L                     0x0D
#define STC3117_ADDR_OCV_H                     0x0E
#define STC3117_ADDR_CC_CNF_L                  0x0F
#define STC3117_ADDR_CC_CNF_H                  0x10
#define STC3117_ADDR_VM_CNF_L                  0x11
#define STC3117_ADDR_VM_CNF_H                  0x12
#define STC3117_ADDR_ALARM_soc                 0x13
#define STC3117_ADDR_ALARM_VOLTAGE             0x14
#define STC3117_ADDR_ID                        0x18
#define STC3117_ADDR_CC_ADJ_L                   0x1B
#define STC3117_ADDR_CC_ADJ_H                   0x1C
#define STC3117_ADDR_VM_ADJ_L                   0x1D
#define STC3117_ADDR_VM_ADJ_H                   0x1E
#define STC3117_ADDR_RAM                        0x20
#define STC3117_ADDR_OCV_TABLE                  0x30
#define STC3117_ADDR_SOC_TABLE                  0x30

/* Bit mask definition */
#define STC3117_ID                              0x16
#define STC3117_MIXED_MODE                      0x00
#define STC3117_VMODE                           BIT(0)
#define STC3117_GG_RUN                          BIT(4)
#define STC3117_CC_MODE                 BIT(5)
#define STC3117_BATFAIL                 BIT(3)
#define STC3117_PORDET                          BIT(4)
#define STC3117_RAM_SIZE                        16
#define STC3117_OCV_TABLE_SIZE                  16
#define STC3117_RAM_TESTWORD                    0x53A9
#define STC3117_SOFT_RESET                     0x11
#define STC3117_NOMINAL_CAPACITY                2600

#define VOLTAGE_LSB_VALUE                       9011
#define CURRENT_LSB_VALUE                       24084
#define APP_CUTOFF_VOLTAGE                      2500
#define MAX_HRSOC                               51200
#define MAX_SOC                         1000
#define CHG_MIN_CURRENT                 200
#define CHG_END_CURRENT                 20
#define APP_MIN_CURRENT                 (-5)
#define BATTERY_FULL                            95
#define CRC8_POLYNOMIAL                 0x07
#define CRC8_INIT                               0x00

DECLARE_CRC8_TABLE(stc3117_crc_table);

enum stc3117_state {
        STC3117_INIT,
        STC3117_RUNNING,
        STC3117_POWERDN,
};

/* Default ocv curve Li-ion battery */
static const int ocv_value[16] = {
        3400, 3582, 3669, 3676, 3699, 3737, 3757, 3774,
        3804, 3844, 3936, 3984, 4028, 4131, 4246, 4320
};

union stc3117_internal_ram {
        u8 ram_bytes[STC3117_RAM_SIZE];
        struct {
        u16 testword;   /* 0-1    Bytes */
        u16 hrsoc;      /* 2-3    Bytes */
        u16 cc_cnf;     /* 4-5    Bytes */
        u16 vm_cnf;     /* 6-7    Bytes */
        u8 soc;         /* 8      Byte  */
        u8 state;       /* 9      Byte  */
        u8 unused[5];   /* 10-14  Bytes */
        u8 crc;         /* 15     Byte  */
        } reg;
};

struct stc3117_battery_info {
        int voltage_min_mv;
        int voltage_max_mv;
        int battery_capacity_mah;
        int sense_resistor;
};

struct stc3117_data {
        struct i2c_client *client;
        struct regmap *regmap;
        struct delayed_work update_work;
        struct power_supply *battery;
        union stc3117_internal_ram ram_data;
        struct stc3117_battery_info battery_info;

        u8 soc_tab[16];
        int cc_cnf;
        int vm_cnf;
        int cc_adj;
        int vm_adj;
        int avg_current;
        int avg_voltage;
        int batt_current;
        int voltage;
        int temp;
        int soc;
        int ocv;
        int hrsoc;
        int presence;
};

static int stc3117_convert(int value, int factor)
{
        value = (value * factor) / 4096;
        return value * 1000;
}

static int stc3117_get_battery_data(struct stc3117_data *data)
{
        u8 reg_list[16];
        u8 data_adjust[4];
        int value, mode;

        regmap_bulk_read(data->regmap, STC3117_ADDR_MODE,
                         reg_list, sizeof(reg_list));

        /* soc */
        value = (reg_list[3] << 8) + reg_list[2];
        data->hrsoc = value;
        data->soc = (value * 10 + 256) / 512;

        /* current in uA*/
        value = (reg_list[7] << 8) + reg_list[6];
        data->batt_current = stc3117_convert(value,
                        CURRENT_LSB_VALUE / data->battery_info.sense_resistor);

        /* voltage in uV */
        value = (reg_list[9] << 8) + reg_list[8];
        data->voltage = stc3117_convert(value, VOLTAGE_LSB_VALUE);

        /* temp in 1/10 °C */
        data->temp = reg_list[10] * 10;

        /* Avg current in uA */
        value = (reg_list[12] << 8) + reg_list[11];
        regmap_read(data->regmap, STC3117_ADDR_MODE, &mode);
        if (!(mode & STC3117_VMODE)) {
                value = stc3117_convert(value,
                        CURRENT_LSB_VALUE / data->battery_info.sense_resistor);
                value = value / 4;
        } else {
                value = stc3117_convert(value, 36 * STC3117_NOMINAL_CAPACITY);
        }
        data->avg_current = value;

        /* ocv in uV */
        value = (reg_list[14] << 8) + reg_list[13];
        value = stc3117_convert(value, VOLTAGE_LSB_VALUE);
        value = (value + 2) / 4;
        data->ocv = value;

        /* CC & VM adjustment counters */
        regmap_bulk_read(data->regmap, STC3117_ADDR_CC_ADJ_L,
                         data_adjust, sizeof(data_adjust));
        value = (data_adjust[1] << 8) + data_adjust[0];
        data->cc_adj = value;

        value = (data_adjust[3] << 8) + data_adjust[2];
        data->vm_adj = value;

        return 0;
}

static int ram_write(struct stc3117_data *data)
{
        int ret;

        ret = regmap_bulk_write(data->regmap, STC3117_ADDR_RAM,
                                data->ram_data.ram_bytes, STC3117_RAM_SIZE);
        if (ret)
                return ret;

        return 0;
};

static int ram_read(struct stc3117_data *data)
{
        int ret;

        ret = regmap_bulk_read(data->regmap, STC3117_ADDR_RAM,
                               data->ram_data.ram_bytes, STC3117_RAM_SIZE);
        if (ret)
                return ret;

        return 0;
};

static int stc3117_set_para(struct stc3117_data *data)
{
        int ret;

        ret = regmap_write(data->regmap, STC3117_ADDR_MODE, STC3117_VMODE);

        for (int i = 0; i < STC3117_OCV_TABLE_SIZE; i++)
                ret |= regmap_write(data->regmap, STC3117_ADDR_OCV_TABLE + i,
                             ocv_value[i] * 100 / 55);
        if (data->soc_tab[1] != 0)
                ret |= regmap_bulk_write(data->regmap, STC3117_ADDR_SOC_TABLE,
                                  data->soc_tab, STC3117_OCV_TABLE_SIZE);

        ret |= regmap_write(data->regmap, STC3117_ADDR_CC_CNF_H,
                                (data->ram_data.reg.cc_cnf >> 8) & 0xFF);

        ret |= regmap_write(data->regmap, STC3117_ADDR_CC_CNF_L,
                                        data->ram_data.reg.cc_cnf & 0xFF);

        ret |= regmap_write(data->regmap, STC3117_ADDR_VM_CNF_H,
                                (data->ram_data.reg.vm_cnf >> 8) & 0xFF);

        ret |= regmap_write(data->regmap, STC3117_ADDR_VM_CNF_L,
                                        data->ram_data.reg.vm_cnf & 0xFF);

        ret |= regmap_write(data->regmap, STC3117_ADDR_CTRL, 0x03);

        ret |= regmap_write(data->regmap, STC3117_ADDR_MODE,
                                        STC3117_MIXED_MODE | STC3117_GG_RUN);

        return ret;
};

static int stc3117_init(struct stc3117_data *data)
{
        int id, ret;
        int ctrl;
        int ocv_m, ocv_l;

        regmap_read(data->regmap, STC3117_ADDR_ID, &id);
        if (id != STC3117_ID)
                return -EINVAL;

        data->cc_cnf = (data->battery_info.battery_capacity_mah *
                        data->battery_info.sense_resistor * 250 + 6194) / 12389;
        data->vm_cnf = (data->battery_info.battery_capacity_mah
                                                * 200 * 50 + 24444) / 48889;

        /* Battery has not been removed */
        data->presence = 1;

        /* Read RAM data */
        ret = ram_read(data);
        if (ret)
                return ret;

        if (data->ram_data.reg.testword != STC3117_RAM_TESTWORD ||
            (crc8(stc3117_crc_table, data->ram_data.ram_bytes,
                                        STC3117_RAM_SIZE, CRC8_INIT)) != 0) {
                data->ram_data.reg.testword = STC3117_RAM_TESTWORD;
                data->ram_data.reg.cc_cnf = data->cc_cnf;
                data->ram_data.reg.vm_cnf = data->vm_cnf;
                data->ram_data.reg.crc = crc8(stc3117_crc_table,
                                                data->ram_data.ram_bytes,
                                                STC3117_RAM_SIZE - 1, CRC8_INIT);

                ret = regmap_read(data->regmap, STC3117_ADDR_OCV_H, &ocv_m);

                ret |= regmap_read(data->regmap, STC3117_ADDR_OCV_L, &ocv_l);

                ret |= stc3117_set_para(data);

                ret |= regmap_write(data->regmap, STC3117_ADDR_OCV_H, ocv_m);

                ret |= regmap_write(data->regmap, STC3117_ADDR_OCV_L, ocv_l);
                if (ret)
                        return ret;
        } else {
                ret = regmap_read(data->regmap, STC3117_ADDR_CTRL, &ctrl);
                if (ret)
                        return ret;

                if ((ctrl & STC3117_BATFAIL) != 0  ||
                    (ctrl & STC3117_PORDET) != 0) {
                        ret = regmap_read(data->regmap,
                                          STC3117_ADDR_OCV_H, &ocv_m);

                        ret |= regmap_read(data->regmap,
                                                STC3117_ADDR_OCV_L, &ocv_l);

                        ret |= stc3117_set_para(data);

                        ret |= regmap_write(data->regmap,
                                                STC3117_ADDR_OCV_H, ocv_m);

                        ret |= regmap_write(data->regmap,
                                                STC3117_ADDR_OCV_L, ocv_l);
                        if (ret)
                                return ret;
                } else {
                        ret = stc3117_set_para(data);
                        ret |= regmap_write(data->regmap, STC3117_ADDR_SOC_H,
                                     (data->ram_data.reg.hrsoc >> 8 & 0xFF));
                        ret |= regmap_write(data->regmap, STC3117_ADDR_SOC_L,
                                     (data->ram_data.reg.hrsoc & 0xFF));
                        if (ret)
                                return ret;
                }
        }

        data->ram_data.reg.state = STC3117_INIT;
        data->ram_data.reg.crc = crc8(stc3117_crc_table,
                                        data->ram_data.ram_bytes,
                                        STC3117_RAM_SIZE - 1, CRC8_INIT);
        ret = ram_write(data);
        if (ret)
                return ret;

        return 0;
};

static int stc3117_task(struct stc3117_data *data)
{
        int id, mode, ret;
        int count_l, count_m;
        int ocv_l, ocv_m;

        regmap_read(data->regmap, STC3117_ADDR_ID, &id);
        if (id != STC3117_ID) {
                data->presence = 0;
                return -EINVAL;
        }

        stc3117_get_battery_data(data);

        /* Read RAM data */
        ret = ram_read(data);
        if (ret)
                return ret;

        if (data->ram_data.reg.testword != STC3117_RAM_TESTWORD ||
            (crc8(stc3117_crc_table, data->ram_data.ram_bytes,
                                        STC3117_RAM_SIZE, CRC8_INIT) != 0)) {
                data->ram_data.reg.testword = STC3117_RAM_TESTWORD;
                data->ram_data.reg.cc_cnf = data->cc_cnf;
                data->ram_data.reg.vm_cnf = data->vm_cnf;
                data->ram_data.reg.crc = crc8(stc3117_crc_table,
                                                data->ram_data.ram_bytes,
                                                STC3117_RAM_SIZE - 1, CRC8_INIT);
                data->ram_data.reg.state = STC3117_INIT;
        }

        /* check battery presence status */
        ret = regmap_read(data->regmap, STC3117_ADDR_CTRL, &mode);
        if ((mode & STC3117_BATFAIL) != 0) {
                data->presence = 0;
                data->ram_data.reg.testword = 0;
                data->ram_data.reg.state = STC3117_INIT;
                ret = ram_write(data);
                ret |= regmap_write(data->regmap, STC3117_ADDR_CTRL, STC3117_PORDET);
                if (ret)
                        return ret;
        }

        data->presence = 1;

        ret = regmap_read(data->regmap, STC3117_ADDR_MODE, &mode);
        if (ret)
                return ret;
        if ((mode & STC3117_GG_RUN) == 0) {
                if (data->ram_data.reg.state > STC3117_INIT) {
                        ret = stc3117_set_para(data);

                        ret |= regmap_write(data->regmap, STC3117_ADDR_SOC_H,
                                        (data->ram_data.reg.hrsoc >> 8 & 0xFF));
                        ret |= regmap_write(data->regmap, STC3117_ADDR_SOC_L,
                                        (data->ram_data.reg.hrsoc & 0xFF));
                        if (ret)
                                return ret;
                } else {
                        ret = regmap_read(data->regmap, STC3117_ADDR_OCV_H, &ocv_m);

                        ret |= regmap_read(data->regmap, STC3117_ADDR_OCV_L, &ocv_l);

                        ret |= stc3117_set_para(data);

                        ret |= regmap_write(data->regmap, STC3117_ADDR_OCV_H, ocv_m);

                        ret |= regmap_write(data->regmap, STC3117_ADDR_OCV_L, ocv_l);
                        if (ret)
                                return ret;
                }
                data->ram_data.reg.state = STC3117_INIT;
        }

        regmap_read(data->regmap, STC3117_ADDR_COUNTER_L, &count_l);
        regmap_read(data->regmap, STC3117_ADDR_COUNTER_H, &count_m);

        count_m = (count_m << 8) + count_l;

        /* INIT state, wait for batt_current & temperature value available: */
        if (data->ram_data.reg.state == STC3117_INIT && count_m > 4) {
                data->avg_voltage = data->voltage;
                data->avg_current = data->batt_current;
                data->ram_data.reg.state = STC3117_RUNNING;
        }

        if (data->ram_data.reg.state != STC3117_RUNNING) {
                data->batt_current = -ENODATA;
                data->temp = -ENODATA;
        } else {
                if (data->voltage < APP_CUTOFF_VOLTAGE)
                        data->soc = -ENODATA;

                if (mode & STC3117_VMODE) {
                        data->avg_current = -ENODATA;
                        data->batt_current = -ENODATA;
                }
        }

        data->ram_data.reg.hrsoc = data->hrsoc;
        data->ram_data.reg.soc = (data->soc + 5) / 10;
        data->ram_data.reg.crc = crc8(stc3117_crc_table,
                                        data->ram_data.ram_bytes,
                                        STC3117_RAM_SIZE - 1, CRC8_INIT);

        ret = ram_write(data);
        if (ret)
                return ret;
        return 0;
};

static void fuel_gauge_update_work(struct work_struct *work)
{
        struct stc3117_data *data =
                container_of(work, struct stc3117_data, update_work.work);

        stc3117_task(data);

        /* Schedule the work to run again in 2 seconds */
        schedule_delayed_work(&data->update_work, msecs_to_jiffies(2000));
}

static int stc3117_get_property(struct power_supply *psy,
        enum power_supply_property psp, union power_supply_propval *val)
{
        struct stc3117_data *data = power_supply_get_drvdata(psy);

        switch (psp) {
        case POWER_SUPPLY_PROP_STATUS:
                if (data->soc > BATTERY_FULL)
                        val->intval = POWER_SUPPLY_STATUS_FULL;
                else if (data->batt_current < 0)
                        val->intval = POWER_SUPPLY_STATUS_CHARGING;
                else if (data->batt_current > 0)
                        val->intval = POWER_SUPPLY_STATUS_DISCHARGING;
                else
                        val->intval = POWER_SUPPLY_STATUS_NOT_CHARGING;
                break;
        case POWER_SUPPLY_PROP_VOLTAGE_NOW:
                val->intval = data->voltage;
                break;
        case POWER_SUPPLY_PROP_CURRENT_NOW:
                val->intval = data->batt_current;
                break;
        case POWER_SUPPLY_PROP_VOLTAGE_OCV:
                val->intval = data->ocv;
                break;
        case POWER_SUPPLY_PROP_CURRENT_AVG:
                val->intval = data->avg_current;
                break;
        case POWER_SUPPLY_PROP_CAPACITY:
                val->intval = data->soc;
                break;
        case POWER_SUPPLY_PROP_TEMP:
                val->intval = data->temp;
                break;
        case POWER_SUPPLY_PROP_PRESENT:
                val->intval = data->presence;
                break;
        default:
                return -EINVAL;
        }
        return 0;
}

static enum power_supply_property stc3117_battery_props[] = {
        POWER_SUPPLY_PROP_STATUS,
        POWER_SUPPLY_PROP_VOLTAGE_NOW,
        POWER_SUPPLY_PROP_CURRENT_NOW,
        POWER_SUPPLY_PROP_VOLTAGE_OCV,
        POWER_SUPPLY_PROP_CURRENT_AVG,
        POWER_SUPPLY_PROP_CAPACITY,
        POWER_SUPPLY_PROP_TEMP,
        POWER_SUPPLY_PROP_PRESENT,
};

static const struct power_supply_desc stc3117_battery_desc = {
        .name = "stc3117-battery",
        .type = POWER_SUPPLY_TYPE_BATTERY,
        .get_property = stc3117_get_property,
        .properties = stc3117_battery_props,
        .num_properties = ARRAY_SIZE(stc3117_battery_props),
};

static const struct regmap_config stc3117_regmap_config = {
        .reg_bits       = 8,
        .val_bits       = 8,
};

static int stc3117_probe(struct i2c_client *client)
{
        struct stc3117_data *data;
        struct power_supply_config psy_cfg = {};
        struct power_supply_battery_info *info;
        int ret;

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

        data->client = client;
        data->regmap = devm_regmap_init_i2c(client, &stc3117_regmap_config);
        if (IS_ERR(data->regmap))
                return PTR_ERR(data->regmap);

        psy_cfg.drv_data = data;
        psy_cfg.fwnode = dev_fwnode(&client->dev);

        crc8_populate_msb(stc3117_crc_table, CRC8_POLYNOMIAL);

        data->battery = devm_power_supply_register(&client->dev,
                                        &stc3117_battery_desc, &psy_cfg);
        if (IS_ERR(data->battery))
                return dev_err_probe(&client->dev, PTR_ERR(data->battery),
                                        "failed to register battery\n");

        ret = device_property_read_u32(&client->dev, "shunt-resistor-micro-ohms",
                                        &data->battery_info.sense_resistor);
        if (ret)
                return dev_err_probe(&client->dev, ret,
                                "failed to get shunt-resistor-micro-ohms\n");
        data->battery_info.sense_resistor = data->battery_info.sense_resistor / 1000;

        ret = power_supply_get_battery_info(data->battery, &info);
        if (ret)
                return dev_err_probe(&client->dev, ret,
                                        "failed to get battery information\n");

        data->battery_info.battery_capacity_mah = info->charge_full_design_uah / 1000;
        data->battery_info.voltage_min_mv = info->voltage_min_design_uv / 1000;
        data->battery_info.voltage_max_mv = info->voltage_max_design_uv / 1000;

        ret = stc3117_init(data);
        if (ret)
                return dev_err_probe(&client->dev, ret,
                                "failed to initialize of stc3117\n");

        ret = devm_delayed_work_autocancel(&client->dev, &data->update_work,
                                           fuel_gauge_update_work);
        if (ret)
                return ret;

        schedule_delayed_work(&data->update_work, 0);

        return 0;
}

static const struct i2c_device_id stc3117_id[] = {
        { .name = "stc3117", .driver_data = 0 },
        { }
};
MODULE_DEVICE_TABLE(i2c, stc3117_id);

static const struct of_device_id stc3117_of_match[] = {
        { .compatible = "st,stc3117" },
        { }
};
MODULE_DEVICE_TABLE(of, stc3117_of_match);

static struct i2c_driver stc3117_i2c_driver = {
        .driver = {
                .name = "stc3117_i2c_driver",
                .of_match_table = stc3117_of_match,
        },
        .probe = stc3117_probe,
        .id_table = stc3117_id,
};

module_i2c_driver(stc3117_i2c_driver);

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Hardevsinh Palaniya <hardevsinh.palaniya@siliconsignals.io>");
MODULE_AUTHOR("Bhavin Sharma <bhavin.sharma@siliconsignals.io>");
MODULE_DESCRIPTION("STC3117 Fuel Gauge Driver");