// SPDX-License-Identifier: GPL-2.0+
//
// Functions to access SY3686A power management chip voltages
//
// Copyright (C) 2019 reMarkable AS - http://www.remarkable.com/
//
// Authors: Lars Ivar Miljeteig <lars.ivar.miljeteig@remarkable.com>
//          Alistair Francis <alistair@alistair23.me>

#include <linux/gpio/consumer.h>
#include <linux/i2c.h>
#include <linux/mfd/sy7636a.h>
#include <linux/module.h>
#include <linux/platform_device.h>
#include <linux/regulator/consumer.h>
#include <linux/regulator/driver.h>
#include <linux/regulator/machine.h>
#include <linux/regmap.h>

struct sy7636a_data {
        struct regmap *regmap;
        struct gpio_desc *pgood_gpio;
        struct gpio_desc *en_gpio;
        struct gpio_desc *vcom_en_gpio;
};

static int sy7636a_get_vcom_voltage_op(struct regulator_dev *rdev)
{
        int ret;
        unsigned int val, val_h;

        ret = regmap_read(rdev->regmap, SY7636A_REG_VCOM_ADJUST_CTRL_L, &val);
        if (ret)
                return ret;

        ret = regmap_read(rdev->regmap, SY7636A_REG_VCOM_ADJUST_CTRL_H, &val_h);
        if (ret)
                return ret;

        val |= (val_h << VCOM_ADJUST_CTRL_SHIFT);

        return (val & VCOM_ADJUST_CTRL_MASK) * VCOM_ADJUST_CTRL_SCAL;
}

static int sy7636a_get_status(struct regulator_dev *rdev)
{
        struct sy7636a_data *data = dev_get_drvdata(rdev->dev.parent);
        int ret = 0;

        ret = gpiod_get_value_cansleep(data->pgood_gpio);
        if (ret < 0)
                dev_err(&rdev->dev, "Failed to read pgood gpio: %d\n", ret);

        return ret;
}

static const struct regulator_ops sy7636a_vcom_volt_ops = {
        .get_voltage = sy7636a_get_vcom_voltage_op,
        .enable = regulator_enable_regmap,
        .disable = regulator_disable_regmap,
        .is_enabled = regulator_is_enabled_regmap,
        .get_status = sy7636a_get_status,
};

static const struct regulator_desc desc = {
        .name = "vcom",
        .id = 0,
        .ops = &sy7636a_vcom_volt_ops,
        .type = REGULATOR_VOLTAGE,
        .owner = THIS_MODULE,
        .enable_reg = SY7636A_REG_OPERATION_MODE_CRL,
        .enable_mask = SY7636A_OPERATION_MODE_CRL_ONOFF,
        .regulators_node = of_match_ptr("regulators"),
        .of_match = of_match_ptr("vcom"),
};

static int sy7636a_regulator_probe(struct platform_device *pdev)
{
        struct regmap *regmap = dev_get_regmap(pdev->dev.parent, NULL);
        struct regulator_config config = { };
        struct regulator_dev *rdev;
        struct gpio_desc *gdp;
        struct sy7636a_data *data;
        int ret;

        if (!regmap)
                return -EPROBE_DEFER;

        device_set_of_node_from_dev(&pdev->dev, pdev->dev.parent);

        gdp = devm_gpiod_get(&pdev->dev, "epd-pwr-good", GPIOD_IN);
        if (IS_ERR(gdp)) {
                dev_err(&pdev->dev, "Power good GPIO fault %ld\n", PTR_ERR(gdp));
                return PTR_ERR(gdp);
        }

        data = devm_kzalloc(&pdev->dev, sizeof(struct sy7636a_data), GFP_KERNEL);
        if (!data)
                return -ENOMEM;

        data->regmap = regmap;
        data->pgood_gpio = gdp;

        ret = devm_regulator_get_enable_optional(&pdev->dev, "vin");
        if (ret)
                return dev_err_probe(&pdev->dev, ret,
                                     "failed to get vin regulator\n");

        data->en_gpio = devm_gpiod_get_optional(&pdev->dev, "enable",
                                                GPIOD_OUT_HIGH);
        if (IS_ERR(data->en_gpio))
                return dev_err_probe(&pdev->dev,
                                     PTR_ERR(data->en_gpio),
                                     "failed to get en gpio\n");

        /* Let VCOM just follow the default power on sequence */
        data->vcom_en_gpio = devm_gpiod_get_optional(&pdev->dev,
                                                     "vcom-en", GPIOD_OUT_LOW);
        if (IS_ERR(data->vcom_en_gpio))
                return dev_err_probe(&pdev->dev,
                                     PTR_ERR(data->vcom_en_gpio),
                                     "failed to get vcom-en gpio\n");

        /* if chip was not enabled, give it time to wake up */
        if (data->en_gpio)
                usleep_range(2500, 4000);

        platform_set_drvdata(pdev, data);

        ret = regmap_write(regmap, SY7636A_REG_POWER_ON_DELAY_TIME, 0x0);
        if (ret) {
                dev_err(pdev->dev.parent, "Failed to initialize regulator: %d\n", ret);
                return ret;
        }

        config.dev = &pdev->dev;
        config.regmap = regmap;

        rdev = devm_regulator_register(&pdev->dev, &desc, &config);
        if (IS_ERR(rdev)) {
                dev_err(pdev->dev.parent, "Failed to register %s regulator\n",
                        pdev->name);
                return PTR_ERR(rdev);
        }

        return 0;
}

static const struct platform_device_id sy7636a_regulator_id_table[] = {
        { "sy7636a-regulator", },
        { }
};
MODULE_DEVICE_TABLE(platform, sy7636a_regulator_id_table);

static struct platform_driver sy7636a_regulator_driver = {
        .driver = {
                .name = "sy7636a-regulator",
                .probe_type = PROBE_PREFER_ASYNCHRONOUS,
        },
        .probe = sy7636a_regulator_probe,
        .id_table = sy7636a_regulator_id_table,
};
module_platform_driver(sy7636a_regulator_driver);

MODULE_AUTHOR("Lars Ivar Miljeteig <lars.ivar.miljeteig@remarkable.com>");
MODULE_DESCRIPTION("SY7636A voltage regulator driver");
MODULE_LICENSE("GPL v2");