// SPDX-License-Identifier: GPL-2.0-only
/*
 * I2C client/driver for the Maxim/Dallas DS2782 Stand-Alone Fuel Gauge IC
 *
 * Copyright (C) 2009 Bluewater Systems Ltd
 *
 * Author: Ryan Mallon
 *
 * DS2786 added by Yulia Vilensky <vilensky@compulab.co.il>
 *
 * UEvent sending added by Evgeny Romanov <romanov@neurosoft.ru>
 */

#include <linux/devm-helpers.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/types.h>
#include <linux/errno.h>
#include <linux/swab.h>
#include <linux/i2c.h>
#include <linux/delay.h>
#include <linux/idr.h>
#include <linux/power_supply.h>
#include <linux/slab.h>
#include <linux/ds2782_battery.h>

#define DS2782_REG_RARC         0x06    /* Remaining active relative capacity */

#define DS278x_REG_VOLT_MSB     0x0c
#define DS278x_REG_TEMP_MSB     0x0a
#define DS278x_REG_CURRENT_MSB  0x0e

/* EEPROM Block */
#define DS2782_REG_RSNSP        0x69    /* Sense resistor value */

/* Current unit measurement in uA for a 1 milli-ohm sense resistor */
#define DS2782_CURRENT_UNITS    1563

#define DS2786_REG_RARC         0x02    /* Remaining active relative capacity */

#define DS2786_CURRENT_UNITS    25

#define DS278x_DELAY            1000

struct ds278x_info;

struct ds278x_battery_ops {
        int (*get_battery_current)(struct ds278x_info *info, int *current_uA);
        int (*get_battery_voltage)(struct ds278x_info *info, int *voltage_uV);
        int (*get_battery_capacity)(struct ds278x_info *info, int *capacity);
};

#define to_ds278x_info(x) power_supply_get_drvdata(x)

struct ds278x_info {
        struct i2c_client       *client;
        struct power_supply     *battery;
        struct power_supply_desc        battery_desc;
        const struct ds278x_battery_ops *ops;
        struct delayed_work     bat_work;
        int                     rsns;
        int                     capacity;
        int                     status;         /* State Of Charge */
};

static DEFINE_IDA(battery_id);

static inline int ds278x_read_reg(struct ds278x_info *info, int reg, u8 *val)
{
        int ret;

        ret = i2c_smbus_read_byte_data(info->client, reg);
        if (ret < 0) {
                dev_err(&info->client->dev, "register read failed\n");
                return ret;
        }

        *val = ret;
        return 0;
}

static inline int ds278x_read_reg16(struct ds278x_info *info, int reg_msb,
                                    s16 *val)
{
        int ret;

        ret = i2c_smbus_read_word_data(info->client, reg_msb);
        if (ret < 0) {
                dev_err(&info->client->dev, "register read failed\n");
                return ret;
        }

        *val = swab16(ret);
        return 0;
}

static int ds278x_get_temp(struct ds278x_info *info, int *temp)
{
        s16 raw;
        int err;

        /*
         * Temperature is measured in units of 0.125 degrees celcius, the
         * power_supply class measures temperature in tenths of degrees
         * celsius. The temperature value is stored as a 10 bit number, plus
         * sign in the upper bits of a 16 bit register.
         */
        err = ds278x_read_reg16(info, DS278x_REG_TEMP_MSB, &raw);
        if (err)
                return err;
        *temp = ((raw / 32) * 125) / 100;
        return 0;
}

static int ds2782_get_current(struct ds278x_info *info, int *current_uA)
{
        int sense_res;
        int err;
        u8 sense_res_raw;
        s16 raw;

        /*
         * The units of measurement for current are dependent on the value of
         * the sense resistor.
         */
        err = ds278x_read_reg(info, DS2782_REG_RSNSP, &sense_res_raw);
        if (err)
                return err;
        if (sense_res_raw == 0) {
                dev_err(&info->client->dev, "sense resistor value is 0\n");
                return -ENXIO;
        }
        sense_res = 1000 / sense_res_raw;

        dev_dbg(&info->client->dev, "sense resistor = %d milli-ohms\n",
                sense_res);
        err = ds278x_read_reg16(info, DS278x_REG_CURRENT_MSB, &raw);
        if (err)
                return err;
        *current_uA = raw * (DS2782_CURRENT_UNITS / sense_res);
        return 0;
}

static int ds2782_get_voltage(struct ds278x_info *info, int *voltage_uV)
{
        s16 raw;
        int err;

        /*
         * Voltage is measured in units of 4.88mV. The voltage is stored as
         * a 10-bit number plus sign, in the upper bits of a 16-bit register
         */
        err = ds278x_read_reg16(info, DS278x_REG_VOLT_MSB, &raw);
        if (err)
                return err;
        *voltage_uV = (raw / 32) * 4800;
        return 0;
}

static int ds2782_get_capacity(struct ds278x_info *info, int *capacity)
{
        int err;
        u8 raw;

        err = ds278x_read_reg(info, DS2782_REG_RARC, &raw);
        if (err)
                return err;
        *capacity = raw;
        return 0;
}

static int ds2786_get_current(struct ds278x_info *info, int *current_uA)
{
        int err;
        s16 raw;

        err = ds278x_read_reg16(info, DS278x_REG_CURRENT_MSB, &raw);
        if (err)
                return err;
        *current_uA = (raw / 16) * (DS2786_CURRENT_UNITS / info->rsns);
        return 0;
}

static int ds2786_get_voltage(struct ds278x_info *info, int *voltage_uV)
{
        s16 raw;
        int err;

        /*
         * Voltage is measured in units of 1.22mV. The voltage is stored as
         * a 12-bit number plus sign, in the upper bits of a 16-bit register
         */
        err = ds278x_read_reg16(info, DS278x_REG_VOLT_MSB, &raw);
        if (err)
                return err;
        *voltage_uV = (raw / 8) * 1220;
        return 0;
}

static int ds2786_get_capacity(struct ds278x_info *info, int *capacity)
{
        int err;
        u8 raw;

        err = ds278x_read_reg(info, DS2786_REG_RARC, &raw);
        if (err)
                return err;
        /* Relative capacity is displayed with resolution 0.5 % */
        *capacity = raw/2 ;
        return 0;
}

static int ds278x_get_status(struct ds278x_info *info, int *status)
{
        int err;
        int current_uA;
        int capacity;

        err = info->ops->get_battery_current(info, &current_uA);
        if (err)
                return err;

        err = info->ops->get_battery_capacity(info, &capacity);
        if (err)
                return err;

        info->capacity = capacity;

        if (capacity == 100)
                *status = POWER_SUPPLY_STATUS_FULL;
        else if (current_uA == 0)
                *status = POWER_SUPPLY_STATUS_NOT_CHARGING;
        else if (current_uA < 0)
                *status = POWER_SUPPLY_STATUS_DISCHARGING;
        else
                *status = POWER_SUPPLY_STATUS_CHARGING;

        return 0;
}

static int ds278x_battery_get_property(struct power_supply *psy,
                                       enum power_supply_property prop,
                                       union power_supply_propval *val)
{
        struct ds278x_info *info = to_ds278x_info(psy);
        int ret;

        switch (prop) {
        case POWER_SUPPLY_PROP_STATUS:
                ret = ds278x_get_status(info, &val->intval);
                break;

        case POWER_SUPPLY_PROP_CAPACITY:
                ret = info->ops->get_battery_capacity(info, &val->intval);
                break;

        case POWER_SUPPLY_PROP_VOLTAGE_NOW:
                ret = info->ops->get_battery_voltage(info, &val->intval);
                break;

        case POWER_SUPPLY_PROP_CURRENT_NOW:
                ret = info->ops->get_battery_current(info, &val->intval);
                break;

        case POWER_SUPPLY_PROP_TEMP:
                ret = ds278x_get_temp(info, &val->intval);
                break;

        default:
                ret = -EINVAL;
        }

        return ret;
}

static void ds278x_bat_update(struct ds278x_info *info)
{
        int old_status = info->status;
        int old_capacity = info->capacity;

        ds278x_get_status(info, &info->status);

        if ((old_status != info->status) || (old_capacity != info->capacity))
                power_supply_changed(info->battery);
}

static void ds278x_bat_work(struct work_struct *work)
{
        struct ds278x_info *info;

        info = container_of(work, struct ds278x_info, bat_work.work);
        ds278x_bat_update(info);

        schedule_delayed_work(&info->bat_work, DS278x_DELAY);
}

static enum power_supply_property ds278x_battery_props[] = {
        POWER_SUPPLY_PROP_STATUS,
        POWER_SUPPLY_PROP_CAPACITY,
        POWER_SUPPLY_PROP_VOLTAGE_NOW,
        POWER_SUPPLY_PROP_CURRENT_NOW,
        POWER_SUPPLY_PROP_TEMP,
};

static void ds278x_power_supply_init(struct power_supply_desc *battery)
{
        battery->type                   = POWER_SUPPLY_TYPE_BATTERY;
        battery->properties             = ds278x_battery_props;
        battery->num_properties         = ARRAY_SIZE(ds278x_battery_props);
        battery->get_property           = ds278x_battery_get_property;
        battery->external_power_changed = NULL;
}

#ifdef CONFIG_PM_SLEEP

static int ds278x_suspend(struct device *dev)
{
        struct i2c_client *client = to_i2c_client(dev);
        struct ds278x_info *info = i2c_get_clientdata(client);

        cancel_delayed_work(&info->bat_work);
        return 0;
}

static int ds278x_resume(struct device *dev)
{
        struct i2c_client *client = to_i2c_client(dev);
        struct ds278x_info *info = i2c_get_clientdata(client);

        schedule_delayed_work(&info->bat_work, DS278x_DELAY);
        return 0;
}
#endif /* CONFIG_PM_SLEEP */

static SIMPLE_DEV_PM_OPS(ds278x_battery_pm_ops, ds278x_suspend, ds278x_resume);

enum ds278x_num_id {
        DS2782 = 0,
        DS2786,
};

static const struct ds278x_battery_ops ds278x_ops[] = {
        [DS2782] = {
                .get_battery_current  = ds2782_get_current,
                .get_battery_voltage  = ds2782_get_voltage,
                .get_battery_capacity = ds2782_get_capacity,
        },
        [DS2786] = {
                .get_battery_current  = ds2786_get_current,
                .get_battery_voltage  = ds2786_get_voltage,
                .get_battery_capacity = ds2786_get_capacity,
        }
};

static void ds278x_free_ida(void *data)
{
        int num = (uintptr_t)data;

        ida_free(&battery_id, num);
}

static int ds278x_battery_probe(struct i2c_client *client)
{
        const struct i2c_device_id *id = i2c_client_get_device_id(client);
        struct ds278x_platform_data *pdata = client->dev.platform_data;
        struct power_supply_config psy_cfg = {};
        struct ds278x_info *info;
        int ret;
        int num;

        /*
         * ds2786 should have the sense resistor value set
         * in the platform data
         */
        if (id->driver_data == DS2786 && !pdata) {
                dev_err(&client->dev, "missing platform data for ds2786\n");
                return -EINVAL;
        }

        /* Get an ID for this battery */
        num = ida_alloc(&battery_id, GFP_KERNEL);
        if (num < 0)
                return num;
        ret = devm_add_action_or_reset(&client->dev, ds278x_free_ida, (void *)(uintptr_t)num);
        if (ret)
                return ret;

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

        info->battery_desc.name = devm_kasprintf(&client->dev, GFP_KERNEL,
                                                 "%s-%d", client->name, num);
        if (!info->battery_desc.name)
                return -ENOMEM;

        if (id->driver_data == DS2786)
                info->rsns = pdata->rsns;

        i2c_set_clientdata(client, info);
        info->client = client;
        info->ops  = &ds278x_ops[id->driver_data];
        ds278x_power_supply_init(&info->battery_desc);
        psy_cfg.drv_data = info;

        info->capacity = 100;
        info->status = POWER_SUPPLY_STATUS_FULL;

        info->battery = devm_power_supply_register(&client->dev,
                                                   &info->battery_desc,
                                                   &psy_cfg);
        if (IS_ERR(info->battery)) {
                dev_err(&client->dev, "failed to register battery\n");
                return PTR_ERR(info->battery);
        }

        ret = devm_delayed_work_autocancel(&client->dev, &info->bat_work, ds278x_bat_work);
        if (ret)
                return ret;
        schedule_delayed_work(&info->bat_work, DS278x_DELAY);

        return 0;
}

static const struct i2c_device_id ds278x_id[] = {
        { .name = "ds2782", .driver_data = DS2782 },
        { .name = "ds2786", .driver_data = DS2786 },
        { }
};
MODULE_DEVICE_TABLE(i2c, ds278x_id);

static struct i2c_driver ds278x_battery_driver = {
        .driver         = {
                .name   = "ds2782-battery",
                .pm     = &ds278x_battery_pm_ops,
        },
        .probe          = ds278x_battery_probe,
        .id_table       = ds278x_id,
};
module_i2c_driver(ds278x_battery_driver);

MODULE_AUTHOR("Ryan Mallon");
MODULE_DESCRIPTION("Maxim/Dallas DS2782 Stand-Alone Fuel Gauge IC driver");
MODULE_LICENSE("GPL");