// SPDX-License-Identifier: GPL-2.0+
/*
 * Copyright (c) 2021 Richtek Technology Corp.
 *
 * Author: ChiYuan Huang <cy_huang@richtek.com>
 */

#include <linux/gpio/consumer.h>
#include <linux/i2c.h>
#include <linux/kernel.h>
#include <linux/mfd/core.h>
#include <linux/module.h>
#include <linux/regmap.h>

#define RT4831_REG_REVISION     0x01
#define RT4831_REG_ENABLE       0x08
#define RT4831_REG_I2CPROT      0x15

#define RICHTEK_VENDOR_ID       0x03
#define RT4831_VID_MASK         GENMASK(1, 0)
#define RT4831_RESET_MASK       BIT(7)
#define RT4831_I2CSAFETMR_MASK  BIT(0)

static const struct mfd_cell rt4831_subdevs[] = {
        MFD_CELL_OF("rt4831-backlight", NULL, NULL, 0, 0, "richtek,rt4831-backlight"),
        MFD_CELL_NAME("rt4831-regulator")
};

static bool rt4831_is_accessible_reg(struct device *dev, unsigned int reg)
{
        if (reg >= RT4831_REG_REVISION && reg <= RT4831_REG_I2CPROT)
                return true;
        return false;
}

static const struct regmap_config rt4831_regmap_config = {
        .reg_bits = 8,
        .val_bits = 8,
        .max_register = RT4831_REG_I2CPROT,

        .readable_reg = rt4831_is_accessible_reg,
        .writeable_reg = rt4831_is_accessible_reg,
};

static int rt4831_probe(struct i2c_client *client)
{
        struct gpio_desc *enable_gpio;
        struct regmap *regmap;
        unsigned int chip_id;
        int ret;

        enable_gpio = devm_gpiod_get_optional(&client->dev, "enable", GPIOD_OUT_HIGH);
        if (IS_ERR(enable_gpio)) {
                dev_err(&client->dev, "Failed to get 'enable' GPIO\n");
                return PTR_ERR(enable_gpio);
        }

        regmap = devm_regmap_init_i2c(client, &rt4831_regmap_config);
        if (IS_ERR(regmap)) {
                dev_err(&client->dev, "Failed to initialize regmap\n");
                return PTR_ERR(regmap);
        }

        ret = regmap_read(regmap, RT4831_REG_REVISION, &chip_id);
        if (ret) {
                dev_err(&client->dev, "Failed to get H/W revision\n");
                return ret;
        }

        if ((chip_id & RT4831_VID_MASK) != RICHTEK_VENDOR_ID) {
                dev_err(&client->dev, "Chip vendor ID 0x%02x not matched\n", chip_id);
                return -ENODEV;
        }

        /*
         * Used to prevent the abnormal shutdown.
         * If SCL/SDA both keep low for one second to reset HW.
         */
        ret = regmap_update_bits(regmap, RT4831_REG_I2CPROT, RT4831_I2CSAFETMR_MASK,
                                 RT4831_I2CSAFETMR_MASK);
        if (ret) {
                dev_err(&client->dev, "Failed to enable I2C safety timer\n");
                return ret;
        }

        return devm_mfd_add_devices(&client->dev, PLATFORM_DEVID_AUTO, rt4831_subdevs,
                                    ARRAY_SIZE(rt4831_subdevs), NULL, 0, NULL);
}

static void rt4831_remove(struct i2c_client *client)
{
        struct regmap *regmap = dev_get_regmap(&client->dev, NULL);
        int ret;

        /* Disable WLED and DSV outputs */
        ret = regmap_update_bits(regmap, RT4831_REG_ENABLE, RT4831_RESET_MASK, RT4831_RESET_MASK);
        if (ret)
                dev_warn(&client->dev, "Failed to disable outputs (%pe)\n", ERR_PTR(ret));
}

static const struct of_device_id __maybe_unused rt4831_of_match[] = {
        { .compatible = "richtek,rt4831", },
        {}
};
MODULE_DEVICE_TABLE(of, rt4831_of_match);

static struct i2c_driver rt4831_driver = {
        .driver = {
                .name = "rt4831",
                .of_match_table = rt4831_of_match,
        },
        .probe = rt4831_probe,
        .remove = rt4831_remove,
};
module_i2c_driver(rt4831_driver);

MODULE_AUTHOR("ChiYuan Huang <cy_huang@richtek.com>");
MODULE_DESCRIPTION("Richtek RT4831 core driver");
MODULE_LICENSE("GPL v2");