// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * max8903_charger.c - Maxim 8903 USB/Adapter Charger Driver
 *
 * Copyright (C) 2011 Samsung Electronics
 * MyungJoo Ham <myungjoo.ham@samsung.com>
 */

#include <linux/gpio/consumer.h>
#include <linux/interrupt.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/slab.h>
#include <linux/power_supply.h>
#include <linux/platform_device.h>

struct max8903_data {
        struct device *dev;
        struct power_supply *psy;
        struct power_supply_desc psy_desc;
        /*
         * GPIOs
         * chg, flt, dcm and usus are optional.
         * dok or uok must be present.
         * If dok is present, cen must be present.
         */
        struct gpio_desc *cen; /* Charger Enable input */
        struct gpio_desc *dok; /* DC (Adapter) Power OK output */
        struct gpio_desc *uok; /* USB Power OK output */
        struct gpio_desc *chg; /* Charger status output */
        struct gpio_desc *flt; /* Fault output */
        struct gpio_desc *dcm; /* Current-Limit Mode input (1: DC, 2: USB) */
        struct gpio_desc *usus; /* USB Suspend Input (1: suspended) */
        bool fault;
        bool usb_in;
        bool ta_in;
};

static enum power_supply_property max8903_charger_props[] = {
        POWER_SUPPLY_PROP_STATUS, /* Charger status output */
        POWER_SUPPLY_PROP_ONLINE, /* External power source */
        POWER_SUPPLY_PROP_HEALTH, /* Fault or OK */
};

static int max8903_get_property(struct power_supply *psy,
                enum power_supply_property psp,
                union power_supply_propval *val)
{
        struct max8903_data *data = power_supply_get_drvdata(psy);

        switch (psp) {
        case POWER_SUPPLY_PROP_STATUS:
                val->intval = POWER_SUPPLY_STATUS_UNKNOWN;
                if (data->chg) {
                        if (gpiod_get_value(data->chg))
                                /* CHG asserted */
                                val->intval = POWER_SUPPLY_STATUS_CHARGING;
                        else if (data->usb_in || data->ta_in)
                                val->intval = POWER_SUPPLY_STATUS_NOT_CHARGING;
                        else
                                val->intval = POWER_SUPPLY_STATUS_DISCHARGING;
                }
                break;
        case POWER_SUPPLY_PROP_ONLINE:
                val->intval = 0;
                if (data->usb_in || data->ta_in)
                        val->intval = 1;
                break;
        case POWER_SUPPLY_PROP_HEALTH:
                val->intval = POWER_SUPPLY_HEALTH_GOOD;
                if (data->fault)
                        val->intval = POWER_SUPPLY_HEALTH_UNSPEC_FAILURE;
                break;
        default:
                return -EINVAL;
        }

        return 0;
}

static irqreturn_t max8903_dcin(int irq, void *_data)
{
        struct max8903_data *data = _data;
        bool ta_in;
        enum power_supply_type old_type;

        /*
         * This means the line is asserted.
         *
         * The signal is active low, but the inversion is handled in the GPIO
         * library as the line should be flagged GPIO_ACTIVE_LOW in the device
         * tree.
         */
        ta_in = gpiod_get_value(data->dok);

        if (ta_in == data->ta_in)
                return IRQ_HANDLED;

        data->ta_in = ta_in;

        /* Set Current-Limit-Mode 1:DC 0:USB */
        if (data->dcm)
                gpiod_set_value(data->dcm, ta_in);

        /* Charger Enable / Disable */
        if (data->cen) {
                int val;

                if (ta_in)
                        /* Certainly enable if DOK is asserted */
                        val = 1;
                else if (data->usb_in)
                        /* Enable if the USB charger is enabled */
                        val = 1;
                else
                        /* Else default-disable */
                        val = 0;

                gpiod_set_value(data->cen, val);
        }

        dev_dbg(data->dev, "TA(DC-IN) Charger %s.\n", ta_in ?
                        "Connected" : "Disconnected");

        old_type = data->psy_desc.type;

        if (data->ta_in)
                data->psy_desc.type = POWER_SUPPLY_TYPE_MAINS;
        else if (data->usb_in)
                data->psy_desc.type = POWER_SUPPLY_TYPE_USB;
        else
                data->psy_desc.type = POWER_SUPPLY_TYPE_BATTERY;

        if (old_type != data->psy_desc.type)
                power_supply_changed(data->psy);

        return IRQ_HANDLED;
}

static irqreturn_t max8903_usbin(int irq, void *_data)
{
        struct max8903_data *data = _data;
        bool usb_in;
        enum power_supply_type old_type;

        /*
         * This means the line is asserted.
         *
         * The signal is active low, but the inversion is handled in the GPIO
         * library as the line should be flagged GPIO_ACTIVE_LOW in the device
         * tree.
         */
        usb_in = gpiod_get_value(data->uok);

        if (usb_in == data->usb_in)
                return IRQ_HANDLED;

        data->usb_in = usb_in;

        /* Do not touch Current-Limit-Mode */

        /* Charger Enable / Disable */
        if (data->cen) {
                int val;

                if (usb_in)
                        /* Certainly enable if UOK is asserted */
                        val = 1;
                else if (data->ta_in)
                        /* Enable if the DC charger is enabled */
                        val = 1;
                else
                        /* Else default-disable */
                        val = 0;

                gpiod_set_value(data->cen, val);
        }

        dev_dbg(data->dev, "USB Charger %s.\n", usb_in ?
                        "Connected" : "Disconnected");

        old_type = data->psy_desc.type;

        if (data->ta_in)
                data->psy_desc.type = POWER_SUPPLY_TYPE_MAINS;
        else if (data->usb_in)
                data->psy_desc.type = POWER_SUPPLY_TYPE_USB;
        else
                data->psy_desc.type = POWER_SUPPLY_TYPE_BATTERY;

        if (old_type != data->psy_desc.type)
                power_supply_changed(data->psy);

        return IRQ_HANDLED;
}

static irqreturn_t max8903_fault(int irq, void *_data)
{
        struct max8903_data *data = _data;
        bool fault;

        /*
         * This means the line is asserted.
         *
         * The signal is active low, but the inversion is handled in the GPIO
         * library as the line should be flagged GPIO_ACTIVE_LOW in the device
         * tree.
         */
        fault = gpiod_get_value(data->flt);

        if (fault == data->fault)
                return IRQ_HANDLED;

        data->fault = fault;

        if (fault)
                dev_err(data->dev, "Charger suffers a fault and stops.\n");
        else
                dev_err(data->dev, "Charger recovered from a fault.\n");

        return IRQ_HANDLED;
}

static int max8903_setup_gpios(struct platform_device *pdev)
{
        struct max8903_data *data = platform_get_drvdata(pdev);
        struct device *dev = &pdev->dev;
        bool ta_in = false;
        bool usb_in = false;
        enum gpiod_flags flags;

        data->dok = devm_gpiod_get_optional(dev, "dok", GPIOD_IN);
        if (IS_ERR(data->dok))
                return dev_err_probe(dev, PTR_ERR(data->dok),
                                     "failed to get DOK GPIO");
        if (data->dok) {
                gpiod_set_consumer_name(data->dok, data->psy_desc.name);
                /*
                 * The DC OK is pulled up to 1 and goes low when a charger
                 * is plugged in (active low) but in the device tree the
                 * line is marked as GPIO_ACTIVE_LOW so we get a 1 (asserted)
                 * here if the DC charger is plugged in.
                 */
                ta_in = gpiod_get_value(data->dok);
        }

        data->uok = devm_gpiod_get_optional(dev, "uok", GPIOD_IN);
        if (IS_ERR(data->uok))
                return dev_err_probe(dev, PTR_ERR(data->uok),
                                     "failed to get UOK GPIO");
        if (data->uok) {
                gpiod_set_consumer_name(data->uok, data->psy_desc.name);
                /*
                 * The USB OK is pulled up to 1 and goes low when a USB charger
                 * is plugged in (active low) but in the device tree the
                 * line is marked as GPIO_ACTIVE_LOW so we get a 1 (asserted)
                 * here if the USB charger is plugged in.
                 */
                usb_in = gpiod_get_value(data->uok);
        }

        /* Either DC OK or USB OK must be provided */
        if (!data->dok && !data->uok) {
                dev_err(dev, "no valid power source\n");
                return -EINVAL;
        }

        /*
         * If either charger is already connected at this point,
         * assert the CEN line and enable charging from the start.
         *
         * The line is active low but also marked with GPIO_ACTIVE_LOW
         * in the device tree, so when we assert the line with
         * GPIOD_OUT_HIGH the line will be driven low.
         */
        flags = (ta_in || usb_in) ? GPIOD_OUT_HIGH : GPIOD_OUT_LOW;
        /*
         * If DC OK is provided, Charger Enable CEN is compulsory
         * so this is not optional here.
         */
        data->cen = devm_gpiod_get(dev, "cen", flags);
        if (IS_ERR(data->cen))
                return dev_err_probe(dev, PTR_ERR(data->cen),
                                     "failed to get CEN GPIO");
        gpiod_set_consumer_name(data->cen, data->psy_desc.name);

        /*
         * If the DC charger is connected, then select it.
         *
         * The DCM line should be marked GPIO_ACTIVE_HIGH in the
         * device tree. Driving it high will enable the DC charger
         * input over the USB charger input.
         */
        flags = ta_in ? GPIOD_OUT_HIGH : GPIOD_OUT_LOW;
        data->dcm = devm_gpiod_get_optional(dev, "dcm", flags);
        if (IS_ERR(data->dcm))
                return dev_err_probe(dev, PTR_ERR(data->dcm),
                                     "failed to get DCM GPIO");
        gpiod_set_consumer_name(data->dcm, data->psy_desc.name);

        data->chg = devm_gpiod_get_optional(dev, "chg", GPIOD_IN);
        if (IS_ERR(data->chg))
                return dev_err_probe(dev, PTR_ERR(data->chg),
                                     "failed to get CHG GPIO");
        gpiod_set_consumer_name(data->chg, data->psy_desc.name);

        data->flt = devm_gpiod_get_optional(dev, "flt", GPIOD_IN);
        if (IS_ERR(data->flt))
                return dev_err_probe(dev, PTR_ERR(data->flt),
                                     "failed to get FLT GPIO");
        gpiod_set_consumer_name(data->flt, data->psy_desc.name);

        data->usus = devm_gpiod_get_optional(dev, "usus", GPIOD_IN);
        if (IS_ERR(data->usus))
                return dev_err_probe(dev, PTR_ERR(data->usus),
                                     "failed to get USUS GPIO");
        gpiod_set_consumer_name(data->usus, data->psy_desc.name);

        data->fault = false;
        data->ta_in = ta_in;
        data->usb_in = usb_in;

        return 0;
}

static int max8903_probe(struct platform_device *pdev)
{
        struct max8903_data *data;
        struct device *dev = &pdev->dev;
        struct power_supply_config psy_cfg = {};
        int ret = 0;

        data = devm_kzalloc(dev, sizeof(struct max8903_data), GFP_KERNEL);
        if (!data)
                return -ENOMEM;

        data->dev = dev;
        platform_set_drvdata(pdev, data);

        ret = max8903_setup_gpios(pdev);
        if (ret)
                return ret;

        data->psy_desc.name = "max8903_charger";
        data->psy_desc.type = (data->ta_in) ? POWER_SUPPLY_TYPE_MAINS :
                        ((data->usb_in) ? POWER_SUPPLY_TYPE_USB :
                         POWER_SUPPLY_TYPE_BATTERY);
        data->psy_desc.get_property = max8903_get_property;
        data->psy_desc.properties = max8903_charger_props;
        data->psy_desc.num_properties = ARRAY_SIZE(max8903_charger_props);

        psy_cfg.fwnode = dev_fwnode(dev);
        psy_cfg.drv_data = data;

        data->psy = devm_power_supply_register(dev, &data->psy_desc, &psy_cfg);
        if (IS_ERR(data->psy)) {
                dev_err(dev, "failed: power supply register.\n");
                return PTR_ERR(data->psy);
        }

        if (data->dok) {
                ret = devm_request_threaded_irq(dev, gpiod_to_irq(data->dok),
                                        NULL, max8903_dcin,
                                        IRQF_TRIGGER_FALLING |
                                        IRQF_TRIGGER_RISING | IRQF_ONESHOT,
                                        "MAX8903 DC IN", data);
                if (ret) {
                        dev_err(dev, "Cannot request irq %d for DC (%d)\n",
                                        gpiod_to_irq(data->dok), ret);
                        return ret;
                }
        }

        if (data->uok) {
                ret = devm_request_threaded_irq(dev, gpiod_to_irq(data->uok),
                                        NULL, max8903_usbin,
                                        IRQF_TRIGGER_FALLING |
                                        IRQF_TRIGGER_RISING | IRQF_ONESHOT,
                                        "MAX8903 USB IN", data);
                if (ret) {
                        dev_err(dev, "Cannot request irq %d for USB (%d)\n",
                                        gpiod_to_irq(data->uok), ret);
                        return ret;
                }
        }

        if (data->flt) {
                ret = devm_request_threaded_irq(dev, gpiod_to_irq(data->flt),
                                        NULL, max8903_fault,
                                        IRQF_TRIGGER_FALLING |
                                        IRQF_TRIGGER_RISING | IRQF_ONESHOT,
                                        "MAX8903 Fault", data);
                if (ret) {
                        dev_err(dev, "Cannot request irq %d for Fault (%d)\n",
                                        gpiod_to_irq(data->flt), ret);
                        return ret;
                }
        }

        return 0;
}

static const struct of_device_id max8903_match_ids[] = {
        { .compatible = "maxim,max8903", },
        { /* sentinel */ }
};
MODULE_DEVICE_TABLE(of, max8903_match_ids);

static struct platform_driver max8903_driver = {
        .probe  = max8903_probe,
        .driver = {
                .name   = "max8903-charger",
                .of_match_table = max8903_match_ids
        },
};

module_platform_driver(max8903_driver);

MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("MAX8903 Charger Driver");
MODULE_AUTHOR("MyungJoo Ham <myungjoo.ham@samsung.com>");
MODULE_ALIAS("platform:max8903-charger");