// SPDX-License-Identifier: GPL-2.0
/*
 * BQ257XX Battery Charger Driver
 * Copyright (C) 2025 Chris Morgan <macromorgan@hotmail.com>
 */

#include <linux/bitfield.h>
#include <linux/err.h>
#include <linux/gpio/consumer.h>
#include <linux/mfd/bq257xx.h>
#include <linux/of.h>
#include <linux/platform_device.h>
#include <linux/regmap.h>
#include <linux/regulator/driver.h>
#include <linux/regulator/of_regulator.h>

struct bq257xx_reg_data {
        struct bq257xx_device *bq;
        struct regulator_dev *bq257xx_reg;
        struct gpio_desc *otg_en_gpio;
        struct regulator_desc desc;
};

static int bq25703_vbus_get_cur_limit(struct regulator_dev *rdev)
{
        struct bq257xx_reg_data *pdata = rdev_get_drvdata(rdev);
        int ret;
        unsigned int reg;

        ret = regmap_read(pdata->bq->regmap, BQ25703_OTG_CURRENT, &reg);
        if (ret)
                return ret;
        return FIELD_GET(BQ25703_OTG_CUR_MASK, reg) * BQ25703_OTG_CUR_STEP_UA;
}

/*
 * Check if the minimum current and maximum current requested are
 * sane values, then set the register accordingly.
 */
static int bq25703_vbus_set_cur_limit(struct regulator_dev *rdev,
                                      int min_uA, int max_uA)
{
        struct bq257xx_reg_data *pdata = rdev_get_drvdata(rdev);
        unsigned int reg;

        if ((min_uA > BQ25703_OTG_CUR_MAX_UA) || (max_uA < 0))
                return -EINVAL;

        reg = (max_uA / BQ25703_OTG_CUR_STEP_UA);

        /* Catch rounding errors since our step is 50000uA. */
        if ((reg * BQ25703_OTG_CUR_STEP_UA) < min_uA)
                return -EINVAL;

        return regmap_write(pdata->bq->regmap, BQ25703_OTG_CURRENT,
                            FIELD_PREP(BQ25703_OTG_CUR_MASK, reg));
}

static int bq25703_vbus_enable(struct regulator_dev *rdev)
{
        struct bq257xx_reg_data *pdata = rdev_get_drvdata(rdev);

        if (pdata->otg_en_gpio)
                gpiod_set_value_cansleep(pdata->otg_en_gpio, 1);
        return regulator_enable_regmap(rdev);
}

static int bq25703_vbus_disable(struct regulator_dev *rdev)
{
        struct bq257xx_reg_data *pdata = rdev_get_drvdata(rdev);

        if (pdata->otg_en_gpio)
                gpiod_set_value_cansleep(pdata->otg_en_gpio, 0);
        return regulator_disable_regmap(rdev);
}

static const struct regulator_ops bq25703_vbus_ops = {
        .enable = bq25703_vbus_enable,
        .disable = bq25703_vbus_disable,
        .is_enabled = regulator_is_enabled_regmap,
        .list_voltage = regulator_list_voltage_linear,
        .get_voltage_sel = regulator_get_voltage_sel_regmap,
        .set_voltage_sel = regulator_set_voltage_sel_regmap,
        .get_current_limit = bq25703_vbus_get_cur_limit,
        .set_current_limit = bq25703_vbus_set_cur_limit,
};

static const struct regulator_desc bq25703_vbus_desc = {
        .name = "vbus",
        .of_match = of_match_ptr("vbus"),
        .regulators_node = of_match_ptr("regulators"),
        .type = REGULATOR_VOLTAGE,
        .owner = THIS_MODULE,
        .ops = &bq25703_vbus_ops,
        .min_uV = BQ25703_OTG_VOLT_MIN_UV,
        .uV_step = BQ25703_OTG_VOLT_STEP_UV,
        .n_voltages = BQ25703_OTG_VOLT_NUM_VOLT,
        .enable_mask = BQ25703_EN_OTG_MASK,
        .enable_reg = BQ25703_CHARGE_OPTION_3,
        .enable_val = BQ25703_EN_OTG_MASK,
        .disable_val = 0,
        .vsel_reg = BQ25703_OTG_VOLT,
        .vsel_mask = BQ25703_OTG_VOLT_MASK,
};

/* Get optional GPIO for OTG regulator enable. */
static void bq257xx_reg_dt_parse_gpio(struct platform_device *pdev)
{
        struct device_node *child, *subchild;
        struct bq257xx_reg_data *pdata = platform_get_drvdata(pdev);

        child = of_get_child_by_name(pdev->dev.of_node,
                                     pdata->desc.regulators_node);
        if (!child)
                return;

        subchild = of_get_child_by_name(child, pdata->desc.of_match);
        of_node_put(child);
        if (!subchild)
                return;

        pdata->otg_en_gpio = devm_fwnode_gpiod_get_index(&pdev->dev,
                                                         of_fwnode_handle(subchild),
                                                         "enable", 0,
                                                         GPIOD_OUT_LOW,
                                                         pdata->desc.of_match);

        of_node_put(subchild);

        if (IS_ERR(pdata->otg_en_gpio)) {
                dev_err(&pdev->dev, "Error getting enable gpio: %ld\n",
                        PTR_ERR(pdata->otg_en_gpio));
                return;
        }
}

static int bq257xx_regulator_probe(struct platform_device *pdev)
{
        struct device *dev = &pdev->dev;
        struct bq257xx_device *bq = dev_get_drvdata(pdev->dev.parent);
        struct bq257xx_reg_data *pdata;
        struct device_node *np = dev->of_node;
        struct regulator_config cfg = {};

        pdev->dev.of_node = pdev->dev.parent->of_node;
        pdev->dev.of_node_reused = true;

        pdata = devm_kzalloc(&pdev->dev, sizeof(struct bq257xx_reg_data), GFP_KERNEL);
        if (!pdata)
                return -ENOMEM;

        pdata->bq = bq;
        pdata->desc = bq25703_vbus_desc;

        platform_set_drvdata(pdev, pdata);
        bq257xx_reg_dt_parse_gpio(pdev);

        cfg.dev = &pdev->dev;
        cfg.driver_data = pdata;
        cfg.of_node = np;
        cfg.regmap = dev_get_regmap(pdev->dev.parent, NULL);
        if (!cfg.regmap)
                return -ENODEV;

        pdata->bq257xx_reg = devm_regulator_register(dev, &pdata->desc, &cfg);
        if (IS_ERR(pdata->bq257xx_reg)) {
                return dev_err_probe(&pdev->dev, PTR_ERR(pdata->bq257xx_reg),
                                     "error registering bq257xx regulator");
        }

        return 0;
}

static struct platform_driver bq257xx_reg_driver = {
        .driver = {
                .name = "bq257xx-regulator",
        },
        .probe = bq257xx_regulator_probe,
};

module_platform_driver(bq257xx_reg_driver);

MODULE_DESCRIPTION("bq257xx regulator driver");
MODULE_AUTHOR("Chris Morgan <macromorgan@hotmail.com>");
MODULE_LICENSE("GPL");