// SPDX-License-Identifier: GPL-2.0
/*
 * Generic battery driver using IIO
 * Copyright (C) 2012, Anish Kumar <yesanishhere@gmail.com>
 * Copyright (c) 2023, Sebastian Reichel <sre@kernel.org>
 */
#include <linux/interrupt.h>
#include <linux/platform_device.h>
#include <linux/power_supply.h>
#include <linux/gpio/consumer.h>
#include <linux/err.h>
#include <linux/timer.h>
#include <linux/jiffies.h>
#include <linux/errno.h>
#include <linux/init.h>
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/iio/consumer.h>
#include <linux/iio/types.h>
#include <linux/of.h>
#include <linux/devm-helpers.h>

#define JITTER_DEFAULT 10 /* hope 10ms is enough */

enum gab_chan_type {
        GAB_VOLTAGE = 0,
        GAB_CURRENT,
        GAB_POWER,
        GAB_TEMP,
        GAB_MAX_CHAN_TYPE
};

/*
 * gab_chan_name suggests the standard channel names for commonly used
 * channel types.
 */
static const char *const gab_chan_name[] = {
        [GAB_VOLTAGE]   = "voltage",
        [GAB_CURRENT]   = "current",
        [GAB_POWER]     = "power",
        [GAB_TEMP]      = "temperature",
};

struct gab {
        struct power_supply *psy;
        struct power_supply_desc psy_desc;
        struct iio_channel *channel[GAB_MAX_CHAN_TYPE];
        struct delayed_work bat_work;
        int status;
        struct gpio_desc *charge_finished;
};

static struct gab *to_generic_bat(struct power_supply *psy)
{
        return power_supply_get_drvdata(psy);
}

static void gab_ext_power_changed(struct power_supply *psy)
{
        struct gab *adc_bat = to_generic_bat(psy);

        schedule_delayed_work(&adc_bat->bat_work, msecs_to_jiffies(0));
}

static const enum power_supply_property gab_props[] = {
        POWER_SUPPLY_PROP_STATUS,
};

/*
 * This properties are set based on the received platform data and this
 * should correspond one-to-one with enum chan_type.
 */
static const enum power_supply_property gab_dyn_props[] = {
        POWER_SUPPLY_PROP_VOLTAGE_NOW,
        POWER_SUPPLY_PROP_CURRENT_NOW,
        POWER_SUPPLY_PROP_POWER_NOW,
        POWER_SUPPLY_PROP_TEMP,
};

static bool gab_charge_finished(struct gab *adc_bat)
{
        if (!adc_bat->charge_finished)
                return false;
        return gpiod_get_value(adc_bat->charge_finished);
}

static int gab_read_channel(struct gab *adc_bat, enum gab_chan_type channel,
                int *result)
{
        int ret;

        ret = iio_read_channel_processed(adc_bat->channel[channel], result);
        if (ret < 0)
                dev_err(&adc_bat->psy->dev, "read channel error: %d\n", ret);
        else
                *result *= 1000;

        return ret;
}

static int gab_get_property(struct power_supply *psy,
                enum power_supply_property psp, union power_supply_propval *val)
{
        struct gab *adc_bat = to_generic_bat(psy);

        switch (psp) {
        case POWER_SUPPLY_PROP_STATUS:
                val->intval = adc_bat->status;
                return 0;
        case POWER_SUPPLY_PROP_VOLTAGE_NOW:
                return gab_read_channel(adc_bat, GAB_VOLTAGE, &val->intval);
        case POWER_SUPPLY_PROP_CURRENT_NOW:
                return gab_read_channel(adc_bat, GAB_CURRENT, &val->intval);
        case POWER_SUPPLY_PROP_POWER_NOW:
                return gab_read_channel(adc_bat, GAB_POWER, &val->intval);
        case POWER_SUPPLY_PROP_TEMP:
                return gab_read_channel(adc_bat, GAB_TEMP, &val->intval);
        default:
                return -EINVAL;
        }
}

static void gab_work(struct work_struct *work)
{
        struct gab *adc_bat;
        struct delayed_work *delayed_work;
        int status;

        delayed_work = to_delayed_work(work);
        adc_bat = container_of(delayed_work, struct gab, bat_work);
        status = adc_bat->status;

        if (!power_supply_am_i_supplied(adc_bat->psy))
                adc_bat->status =  POWER_SUPPLY_STATUS_DISCHARGING;
        else if (gab_charge_finished(adc_bat))
                adc_bat->status = POWER_SUPPLY_STATUS_NOT_CHARGING;
        else
                adc_bat->status = POWER_SUPPLY_STATUS_CHARGING;

        if (status != adc_bat->status)
                power_supply_changed(adc_bat->psy);
}

static irqreturn_t gab_charged(int irq, void *dev_id)
{
        struct gab *adc_bat = dev_id;

        schedule_delayed_work(&adc_bat->bat_work,
                              msecs_to_jiffies(JITTER_DEFAULT));

        return IRQ_HANDLED;
}

static int gab_probe(struct platform_device *pdev)
{
        struct gab *adc_bat;
        struct power_supply_desc *psy_desc;
        struct power_supply_config psy_cfg = {};
        enum power_supply_property *properties;
        int ret = 0;
        int chan;
        int index = ARRAY_SIZE(gab_props);
        bool any = false;

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

        psy_cfg.fwnode = dev_fwnode(&pdev->dev);
        psy_cfg.drv_data = adc_bat;
        psy_desc = &adc_bat->psy_desc;
        psy_desc->name = dev_name(&pdev->dev);

        /* bootup default values for the battery */
        adc_bat->status = POWER_SUPPLY_STATUS_DISCHARGING;
        psy_desc->type = POWER_SUPPLY_TYPE_BATTERY;
        psy_desc->get_property = gab_get_property;
        psy_desc->external_power_changed = gab_ext_power_changed;

        /*
         * copying the static properties and allocating extra memory for holding
         * the extra configurable properties received from platform data.
         */
        properties = devm_kcalloc(&pdev->dev,
                                  ARRAY_SIZE(gab_props) +
                                  ARRAY_SIZE(gab_chan_name),
                                  sizeof(*properties),
                                  GFP_KERNEL);
        if (!properties)
                return -ENOMEM;

        memcpy(properties, gab_props, sizeof(gab_props));

        /*
         * getting channel from iio and copying the battery properties
         * based on the channel supported by consumer device.
         */
        for (chan = 0; chan < ARRAY_SIZE(gab_chan_name); chan++) {
                adc_bat->channel[chan] = devm_iio_channel_get(&pdev->dev, gab_chan_name[chan]);
                if (IS_ERR(adc_bat->channel[chan])) {
                        ret = PTR_ERR(adc_bat->channel[chan]);
                        if (ret != -ENODEV)
                                return dev_err_probe(&pdev->dev, ret, "Failed to get ADC channel %s\n", gab_chan_name[chan]);
                        adc_bat->channel[chan] = NULL;
                } else if (adc_bat->channel[chan]) {
                        /* copying properties for supported channels only */
                        int index2;

                        for (index2 = 0; index2 < index; index2++) {
                                if (properties[index2] == gab_dyn_props[chan])
                                        break;  /* already known */
                        }
                        if (index2 == index)    /* really new */
                                properties[index++] = gab_dyn_props[chan];
                        any = true;
                }
        }

        /* none of the channels are supported so let's bail out */
        if (!any)
                return dev_err_probe(&pdev->dev, -ENODEV, "Failed to get any ADC channel\n");

        /*
         * Total number of properties is equal to static properties
         * plus the dynamic properties.Some properties may not be set
         * as come channels may be not be supported by the device.So
         * we need to take care of that.
         */
        psy_desc->properties = properties;
        psy_desc->num_properties = index;

        adc_bat->psy = devm_power_supply_register(&pdev->dev, psy_desc, &psy_cfg);
        if (IS_ERR(adc_bat->psy))
                return dev_err_probe(&pdev->dev, PTR_ERR(adc_bat->psy), "Failed to register power-supply device\n");

        ret = devm_delayed_work_autocancel(&pdev->dev, &adc_bat->bat_work, gab_work);
        if (ret)
                return dev_err_probe(&pdev->dev, ret, "Failed to register delayed work\n");

        adc_bat->charge_finished = devm_gpiod_get_optional(&pdev->dev, "charged", GPIOD_IN);
        if (adc_bat->charge_finished) {
                int irq;

                irq = gpiod_to_irq(adc_bat->charge_finished);
                ret = devm_request_any_context_irq(&pdev->dev, irq, gab_charged,
                                IRQF_TRIGGER_RISING | IRQF_TRIGGER_FALLING,
                                "battery charged", adc_bat);
                if (ret < 0)
                        return dev_err_probe(&pdev->dev, ret, "Failed to register irq\n");
        }

        platform_set_drvdata(pdev, adc_bat);

        /* Schedule timer to check current status */
        schedule_delayed_work(&adc_bat->bat_work,
                        msecs_to_jiffies(0));
        return 0;
}

static int __maybe_unused gab_suspend(struct device *dev)
{
        struct gab *adc_bat = dev_get_drvdata(dev);

        cancel_delayed_work_sync(&adc_bat->bat_work);
        adc_bat->status = POWER_SUPPLY_STATUS_UNKNOWN;
        return 0;
}

static int __maybe_unused gab_resume(struct device *dev)
{
        struct gab *adc_bat = dev_get_drvdata(dev);

        /* Schedule timer to check current status */
        schedule_delayed_work(&adc_bat->bat_work,
                              msecs_to_jiffies(JITTER_DEFAULT));

        return 0;
}

static SIMPLE_DEV_PM_OPS(gab_pm_ops, gab_suspend, gab_resume);

static const struct of_device_id gab_match[] = {
        { .compatible = "adc-battery" },
        { }
};
MODULE_DEVICE_TABLE(of, gab_match);

static struct platform_driver gab_driver = {
        .driver         = {
                .name   = "generic-adc-battery",
                .pm     = &gab_pm_ops,
                .of_match_table = gab_match,
        },
        .probe          = gab_probe,
};
module_platform_driver(gab_driver);

MODULE_AUTHOR("anish kumar <yesanishhere@gmail.com>");
MODULE_DESCRIPTION("generic battery driver using IIO");
MODULE_LICENSE("GPL");