root/drivers/power/supply/s2mu005-battery.c
// SPDX-License-Identifier: GPL-2.0
/*
 * Battery Fuel Gauge Driver for Samsung S2MU005 PMIC.
 *
 * Copyright (C) 2015 Samsung Electronics
 * Copyright (C) 2023 Yassine Oudjana <y.oudjana@protonmail.com>
 * Copyright (C) 2025 Kaustabh Chakraborty <kauschluss@disroot.org>
 */

#include <linux/delay.h>
#include <linux/i2c.h>
#include <linux/interrupt.h>
#include <linux/mutex.h>
#include <linux/power_supply.h>
#include <linux/property.h>
#include <linux/regmap.h>
#include <linux/units.h>

#define S2MU005_FG_REG_STATUS           0x00
#define S2MU005_FG_REG_IRQ              0x02
#define S2MU005_FG_REG_RVBAT            0x04
#define S2MU005_FG_REG_RCURCC           0x06
#define S2MU005_FG_REG_RSOC             0x08
#define S2MU005_FG_REG_MONOUT           0x0a
#define S2MU005_FG_REG_MONOUTSEL        0x0c
#define S2MU005_FG_REG_RBATCAP          0x0e
#define S2MU005_FG_REG_RZADJ            0x12
#define S2MU005_FG_REG_RBATZ0           0x16
#define S2MU005_FG_REG_RBATZ1           0x18
#define S2MU005_FG_REG_IRQLVL           0x1a
#define S2MU005_FG_REG_START            0x1e

#define S2MU005_FG_MONOUTSEL_AVGCURRENT         0x26
#define S2MU005_FG_MONOUTSEL_AVGVOLTAGE         0x27

struct s2mu005_fg {
        struct device *dev;
        struct regmap *regmap;
        struct power_supply *psy;
        struct mutex monout_mutex;
};

static const struct regmap_config s2mu005_fg_regmap_config = {
        .reg_bits = 8,
        .val_bits = 16,
        .val_format_endian = REGMAP_ENDIAN_LITTLE,
};

static irqreturn_t s2mu005_handle_irq(int irq, void *data)
{
        struct s2mu005_fg *priv = data;

        msleep(100);
        power_supply_changed(priv->psy);

        return IRQ_HANDLED;
}

static int s2mu005_fg_get_voltage_now(struct s2mu005_fg *priv, int *value)
{
        struct regmap *regmap = priv->regmap;
        u32 val;
        int ret;

        ret = regmap_read(regmap, S2MU005_FG_REG_RVBAT, &val);
        if (ret < 0) {
                dev_err(priv->dev, "failed to read voltage register (%d)\n", ret);
                return ret;
        }

        *value = (val * MICRO) >> 13;

        return 0;
}

static int s2mu005_fg_get_voltage_avg(struct s2mu005_fg *priv, int *value)
{
        struct regmap *regmap = priv->regmap;
        u32 val;
        int ret;

        mutex_lock(&priv->monout_mutex);

        ret = regmap_write(regmap, S2MU005_FG_REG_MONOUTSEL,
                           S2MU005_FG_MONOUTSEL_AVGVOLTAGE);
        if (ret < 0) {
                dev_err(priv->dev, "failed to enable average voltage monitoring (%d)\n",
                        ret);
                goto unlock;
        }

        ret = regmap_read(regmap, S2MU005_FG_REG_MONOUT, &val);
        if (ret < 0) {
                dev_err(priv->dev, "failed to read current register (%d)\n", ret);
                goto unlock;
        }

        *value = (val * MICRO) >> 12;

unlock:
        mutex_unlock(&priv->monout_mutex);

        return ret;
}
static int s2mu005_fg_get_current_now(struct s2mu005_fg *priv, int *value)
{
        struct regmap *regmap = priv->regmap;
        u32 val;
        int ret;

        ret = regmap_read(regmap, S2MU005_FG_REG_RCURCC, &val);
        if (ret < 0) {
                dev_err(priv->dev, "failed to read current register (%d)\n", ret);
                return ret;
        }

        *value = -((s16)val * MICRO) >> 12;

        return 0;
}

static int s2mu005_fg_get_current_avg(struct s2mu005_fg *priv, int *value)
{
        struct regmap *regmap = priv->regmap;
        u32 val;
        int ret;

        mutex_lock(&priv->monout_mutex);

        ret = regmap_write(regmap, S2MU005_FG_REG_MONOUTSEL,
                           S2MU005_FG_MONOUTSEL_AVGCURRENT);
        if (ret < 0) {
                dev_err(priv->dev, "failed to enable average current monitoring (%d)\n",
                        ret);
                goto unlock;
        }

        ret = regmap_read(regmap, S2MU005_FG_REG_MONOUT, &val);
        if (ret < 0) {
                dev_err(priv->dev, "failed to read current register (%d)\n", ret);
                goto unlock;
        }

        *value = -((s16)val * MICRO) >> 12;

unlock:
        mutex_unlock(&priv->monout_mutex);

        return ret;
}

static int s2mu005_fg_get_capacity(struct s2mu005_fg *priv, int *value)
{
        struct regmap *regmap = priv->regmap;
        u32 val;
        int ret;

        ret = regmap_read(regmap, S2MU005_FG_REG_RSOC, &val);
        if (ret < 0) {
                dev_err(priv->dev, "failed to read capacity register (%d)\n", ret);
                return ret;
        }

        *value = (val * CENTI) >> 14;

        return 0;
}

static int s2mu005_fg_get_status(struct s2mu005_fg *priv, int *value)
{
        int current_now, current_avg, capacity;
        int ret;

        ret = s2mu005_fg_get_current_now(priv, &current_now);
        if (ret < 0)
                return ret;

        ret = s2mu005_fg_get_current_avg(priv, &current_avg);
        if (ret < 0)
                return ret;

        /*
         * Verify both current values reported to reduce inaccuracies due to
         * internal hysteresis.
         */
        if (current_now < 0 && current_avg < 0) {
                *value = POWER_SUPPLY_STATUS_DISCHARGING;
        } else if (current_now == 0) {
                *value = POWER_SUPPLY_STATUS_NOT_CHARGING;
        } else {
                *value = POWER_SUPPLY_STATUS_CHARGING;

                ret = s2mu005_fg_get_capacity(priv, &capacity);
                if (!ret && capacity > 98)
                        *value = POWER_SUPPLY_STATUS_FULL;
                return ret;
        }

        return 0;
}

static const enum power_supply_property s2mu005_fg_properties[] = {
        POWER_SUPPLY_PROP_VOLTAGE_NOW,
        POWER_SUPPLY_PROP_VOLTAGE_AVG,
        POWER_SUPPLY_PROP_CURRENT_NOW,
        POWER_SUPPLY_PROP_CURRENT_AVG,
        POWER_SUPPLY_PROP_CAPACITY,
        POWER_SUPPLY_PROP_STATUS,
};

static int s2mu005_fg_get_property(struct power_supply *psy,
                                   enum power_supply_property psp,
                                   union power_supply_propval *val)
{
        struct s2mu005_fg *priv = power_supply_get_drvdata(psy);

        switch (psp) {
        case POWER_SUPPLY_PROP_VOLTAGE_NOW:
                return s2mu005_fg_get_voltage_now(priv, &val->intval);
        case POWER_SUPPLY_PROP_VOLTAGE_AVG:
                return s2mu005_fg_get_voltage_avg(priv, &val->intval);
        case POWER_SUPPLY_PROP_CURRENT_NOW:
                return s2mu005_fg_get_current_now(priv, &val->intval);
        case POWER_SUPPLY_PROP_CURRENT_AVG:
                return s2mu005_fg_get_current_avg(priv, &val->intval);
        case POWER_SUPPLY_PROP_CAPACITY:
                return s2mu005_fg_get_capacity(priv, &val->intval);
        case POWER_SUPPLY_PROP_STATUS:
                return s2mu005_fg_get_status(priv, &val->intval);
        default:
                return -EINVAL;
        }
}

static const struct power_supply_desc s2mu005_fg_desc = {
        .name = "s2mu005-fuel-gauge",
        .type = POWER_SUPPLY_TYPE_BATTERY,
        .properties = s2mu005_fg_properties,
        .num_properties = ARRAY_SIZE(s2mu005_fg_properties),
        .get_property = s2mu005_fg_get_property,
};

static int s2mu005_fg_i2c_probe(struct i2c_client *client)
{
        struct device *dev = &client->dev;
        struct s2mu005_fg *priv;
        struct power_supply_config psy_cfg = {};
        const struct power_supply_desc *psy_desc;
        int ret;

        priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
        if (!priv)
                return -ENOMEM;

        dev_set_drvdata(dev, priv);
        priv->dev = dev;

        priv->regmap = devm_regmap_init_i2c(client, &s2mu005_fg_regmap_config);
        if (IS_ERR(priv->regmap))
                return dev_err_probe(dev, PTR_ERR(priv->regmap),
                                     "failed to initialize regmap\n");

        ret = devm_mutex_init(dev, &priv->monout_mutex);
        if (ret)
                dev_err_probe(dev, ret, "failed to initialize MONOUT mutex\n");

        psy_desc = device_get_match_data(dev);

        psy_cfg.drv_data = priv;
        psy_cfg.fwnode = dev_fwnode(dev);
        priv->psy = devm_power_supply_register(priv->dev, psy_desc, &psy_cfg);
        if (IS_ERR(priv->psy))
                return dev_err_probe(dev, PTR_ERR(priv->psy),
                                     "failed to register power supply subsystem\n");

        ret = devm_request_threaded_irq(priv->dev, client->irq, NULL,
                                        s2mu005_handle_irq, IRQF_ONESHOT,
                                        psy_desc->name, priv);
        if (ret)
                dev_err_probe(dev, ret, "failed to request IRQ\n");

        return 0;
}

static const struct of_device_id s2mu005_fg_of_match_table[] = {
        {
                .compatible = "samsung,s2mu005-fuel-gauge",
                .data = &s2mu005_fg_desc,
        },
        { }
};
MODULE_DEVICE_TABLE(of, s2mu005_fg_of_match_table);

static struct i2c_driver s2mu005_fg_i2c_driver = {
        .probe = s2mu005_fg_i2c_probe,
        .driver = {
                .name = "s2mu005-fuel-gauge",
                .of_match_table = s2mu005_fg_of_match_table,
        },
};
module_i2c_driver(s2mu005_fg_i2c_driver);

MODULE_DESCRIPTION("Samsung S2MU005 PMIC Battery Fuel Gauge Driver");
MODULE_AUTHOR("Yassine Oudjana <y.oudjana@protonmail.com>");
MODULE_AUTHOR("Kaustabh Chakraborty <kauschluss@disroot.org>");
MODULE_LICENSE("GPL");