// SPDX-License-Identifier: GPL-2.0+
/*
 * Battery driver for Acer Iconia Tab A500.
 *
 * Copyright 2020 GRATE-driver project.
 *
 * Based on downstream driver from Acer Inc.
 * Based on NVIDIA Gas Gauge driver for SBS Compliant Batteries.
 *
 * Copyright (c) 2010, NVIDIA Corporation.
 */

#include <linux/module.h>
#include <linux/platform_device.h>
#include <linux/power_supply.h>
#include <linux/regmap.h>
#include <linux/sched.h>
#include <linux/slab.h>
#include <linux/workqueue.h>
#include <linux/property.h>

enum {
        REG_CAPACITY,
        REG_VOLTAGE,
        REG_CURRENT,
        REG_DESIGN_CAPACITY,
        REG_TEMPERATURE,
};

#define EC_DATA(_reg, _psp) {                   \
        .psp = POWER_SUPPLY_PROP_ ## _psp,      \
        .reg = _reg,                            \
}

static const struct battery_register {
        enum power_supply_property psp;
        unsigned int reg;
} ec_data[] = {
        [REG_CAPACITY]          = EC_DATA(0x00, CAPACITY),
        [REG_VOLTAGE]           = EC_DATA(0x01, VOLTAGE_NOW),
        [REG_CURRENT]           = EC_DATA(0x03, CURRENT_NOW),
        [REG_DESIGN_CAPACITY]   = EC_DATA(0x08, CHARGE_FULL_DESIGN),
        [REG_TEMPERATURE]       = EC_DATA(0x0a, TEMP),
};

static const enum power_supply_property a500_battery_properties[] = {
        POWER_SUPPLY_PROP_CAPACITY,
        POWER_SUPPLY_PROP_CHARGE_FULL_DESIGN,
        POWER_SUPPLY_PROP_CURRENT_NOW,
        POWER_SUPPLY_PROP_PRESENT,
        POWER_SUPPLY_PROP_STATUS,
        POWER_SUPPLY_PROP_TECHNOLOGY,
        POWER_SUPPLY_PROP_TEMP,
        POWER_SUPPLY_PROP_VOLTAGE_NOW,
};

struct a500_battery {
        struct delayed_work poll_work;
        struct power_supply *psy;
        struct regmap *regmap;
        unsigned int capacity;
};

static bool a500_battery_update_capacity(struct a500_battery *bat)
{
        unsigned int capacity;
        int err;

        err = regmap_read(bat->regmap, ec_data[REG_CAPACITY].reg, &capacity);
        if (err)
                return false;

        /* capacity can be >100% even if max value is 100% */
        capacity = min(capacity, 100u);

        if (bat->capacity != capacity) {
                bat->capacity = capacity;
                return true;
        }

        return false;
}

static int a500_battery_get_status(struct a500_battery *bat)
{
        if (bat->capacity < 100) {
                if (power_supply_am_i_supplied(bat->psy))
                        return POWER_SUPPLY_STATUS_CHARGING;
                else
                        return POWER_SUPPLY_STATUS_DISCHARGING;
        }

        return POWER_SUPPLY_STATUS_FULL;
}

static void a500_battery_unit_adjustment(struct device *dev,
                                         enum power_supply_property psp,
                                         union power_supply_propval *val)
{
        const unsigned int base_unit_conversion = 1000;
        const unsigned int temp_kelvin_to_celsius = 2731;

        switch (psp) {
        case POWER_SUPPLY_PROP_CHARGE_FULL_DESIGN:
        case POWER_SUPPLY_PROP_CURRENT_NOW:
        case POWER_SUPPLY_PROP_VOLTAGE_NOW:
                val->intval *= base_unit_conversion;
                break;

        case POWER_SUPPLY_PROP_TEMP:
                val->intval -= temp_kelvin_to_celsius;
                break;

        case POWER_SUPPLY_PROP_PRESENT:
                val->intval = !!val->intval;
                break;

        default:
                dev_dbg(dev,
                        "%s: no need for unit conversion %d\n", __func__, psp);
        }
}

static int a500_battery_get_ec_data_index(struct device *dev,
                                          enum power_supply_property psp)
{
        unsigned int i;

        /*
         * DESIGN_CAPACITY register always returns a non-zero value if
         * battery is connected and zero if disconnected, hence we'll use
         * it for judging the battery presence.
         */
        if (psp == POWER_SUPPLY_PROP_PRESENT)
                psp = POWER_SUPPLY_PROP_CHARGE_FULL_DESIGN;

        for (i = 0; i < ARRAY_SIZE(ec_data); i++)
                if (psp == ec_data[i].psp)
                        return i;

        dev_dbg(dev, "%s: invalid property %u\n", __func__, psp);

        return -EINVAL;
}

static int a500_battery_get_property(struct power_supply *psy,
                                     enum power_supply_property psp,
                                     union power_supply_propval *val)
{
        struct a500_battery *bat = power_supply_get_drvdata(psy);
        struct device *dev = psy->dev.parent;
        int ret = 0;

        switch (psp) {
        case POWER_SUPPLY_PROP_STATUS:
                val->intval = a500_battery_get_status(bat);
                break;

        case POWER_SUPPLY_PROP_TECHNOLOGY:
                val->intval = POWER_SUPPLY_TECHNOLOGY_LION;
                break;

        case POWER_SUPPLY_PROP_CAPACITY:
                a500_battery_update_capacity(bat);
                val->intval = bat->capacity;
                break;

        case POWER_SUPPLY_PROP_CHARGE_FULL_DESIGN:
        case POWER_SUPPLY_PROP_CURRENT_NOW:
        case POWER_SUPPLY_PROP_VOLTAGE_NOW:
        case POWER_SUPPLY_PROP_PRESENT:
        case POWER_SUPPLY_PROP_TEMP:
                ret = a500_battery_get_ec_data_index(dev, psp);
                if (ret < 0)
                        break;

                ret = regmap_read(bat->regmap, ec_data[ret].reg, &val->intval);
                break;

        default:
                dev_err(dev, "%s: invalid property %u\n", __func__, psp);
                return -EINVAL;
        }

        if (!ret) {
                /* convert units to match requirements of power supply class */
                a500_battery_unit_adjustment(dev, psp, val);
        }

        dev_dbg(dev, "%s: property = %d, value = %x\n",
                __func__, psp, val->intval);

        /* return NODATA for properties if battery not presents */
        if (ret)
                return -ENODATA;

        return 0;
}

static void a500_battery_poll_work(struct work_struct *work)
{
        struct a500_battery *bat;
        bool capacity_changed;

        bat = container_of(work, struct a500_battery, poll_work.work);
        capacity_changed = a500_battery_update_capacity(bat);

        if (capacity_changed)
                power_supply_changed(bat->psy);

        /* continuously send uevent notification */
        schedule_delayed_work(&bat->poll_work, 30 * HZ);
}

static const struct power_supply_desc a500_battery_desc = {
        .name = "ec-battery",
        .type = POWER_SUPPLY_TYPE_BATTERY,
        .properties = a500_battery_properties,
        .get_property = a500_battery_get_property,
        .num_properties = ARRAY_SIZE(a500_battery_properties),
        .external_power_changed = power_supply_changed,
};

static int a500_battery_probe(struct platform_device *pdev)
{
        struct power_supply_config psy_cfg = {};
        struct a500_battery *bat;

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

        platform_set_drvdata(pdev, bat);

        psy_cfg.fwnode = dev_fwnode(pdev->dev.parent);
        psy_cfg.drv_data = bat;
        psy_cfg.no_wakeup_source = true;

        bat->regmap = dev_get_regmap(pdev->dev.parent, "KB930");
        if (!bat->regmap)
                return -EINVAL;

        bat->psy = devm_power_supply_register(&pdev->dev,
                                              &a500_battery_desc,
                                              &psy_cfg);
        if (IS_ERR(bat->psy))
                return dev_err_probe(&pdev->dev, PTR_ERR(bat->psy),
                                     "failed to register battery\n");

        INIT_DELAYED_WORK(&bat->poll_work, a500_battery_poll_work);
        schedule_delayed_work(&bat->poll_work, HZ);

        return 0;
}

static void a500_battery_remove(struct platform_device *pdev)
{
        struct a500_battery *bat = dev_get_drvdata(&pdev->dev);

        cancel_delayed_work_sync(&bat->poll_work);
}

static int __maybe_unused a500_battery_suspend(struct device *dev)
{
        struct a500_battery *bat = dev_get_drvdata(dev);

        cancel_delayed_work_sync(&bat->poll_work);

        return 0;
}

static int __maybe_unused a500_battery_resume(struct device *dev)
{
        struct a500_battery *bat = dev_get_drvdata(dev);

        schedule_delayed_work(&bat->poll_work, HZ);

        return 0;
}

static SIMPLE_DEV_PM_OPS(a500_battery_pm_ops,
                         a500_battery_suspend, a500_battery_resume);

static struct platform_driver a500_battery_driver = {
        .driver = {
                .name = "acer-a500-iconia-battery",
                .pm = &a500_battery_pm_ops,
        },
        .probe = a500_battery_probe,
        .remove = a500_battery_remove,
};
module_platform_driver(a500_battery_driver);

MODULE_DESCRIPTION("Battery gauge driver for Acer Iconia Tab A500");
MODULE_AUTHOR("Dmitry Osipenko <digetx@gmail.com>");
MODULE_ALIAS("platform:acer-a500-iconia-battery");
MODULE_LICENSE("GPL");