// SPDX-License-Identifier: GPL-2.0-only
/*
 * Copyright (c) 2021, The Linux Foundation. All rights reserved.
 * Copyright (c) 2022, Linaro Ltd.
 */

#include <linux/bitfield.h>
#include <linux/gpio/consumer.h>
#include <linux/i2c.h>
#include <linux/module.h>
#include <linux/of_platform.h>
#include <linux/regmap.h>
#include <linux/regulator/driver.h>
#include <linux/regulator/machine.h>
#include <linux/regulator/of_regulator.h>

#define MAX20411_UV_STEP                6250
#define MAX20411_BASE_UV                243750
#define MAX20411_MIN_SEL                41 /* 0.5V */
#define MAX20411_MAX_SEL                165 /* 1.275V */
#define MAX20411_VID_OFFSET             0x7
#define MAX20411_VID_MASK               0xff
#define MAX20411_SLEW_OFFSET            0x6
#define MAX20411_SLEW_DVS_MASK          0xc
#define MAX20411_SLEW_SR_MASK           0x3

struct max20411 {
        struct device *dev;
        struct device_node *of_node;
        struct regulator_desc desc;
        struct regulator_dev *rdev;
        struct regmap *regmap;
};

static const unsigned int max20411_slew_rates[] = { 13100, 6600, 3300, 1600 };

static int max20411_enable_time(struct regulator_dev *rdev)
{
        int voltage, rate, ret;
        unsigned int val;

        /* get voltage */
        ret = regmap_read(rdev->regmap, rdev->desc->vsel_reg, &val);
        if (ret)
                return ret;

        val &= rdev->desc->vsel_mask;
        voltage = regulator_list_voltage_linear(rdev, val);

        /* get rate */
        ret = regmap_read(rdev->regmap, MAX20411_SLEW_OFFSET, &val);
        if (ret)
                return ret;

        val = FIELD_GET(MAX20411_SLEW_SR_MASK, val);
        rate = max20411_slew_rates[val];

        return DIV_ROUND_UP(voltage, rate);
}

static const struct regmap_config max20411_regmap_config = {
        .reg_bits               = 8,
        .val_bits               = 8,
        .max_register           = 0xe,
};

static const struct regulator_ops max20411_ops = {
        .get_voltage_sel        = regulator_get_voltage_sel_regmap,
        .set_voltage_sel        = regulator_set_voltage_sel_regmap,
        .list_voltage           = regulator_list_voltage_linear,
        .enable_time            = max20411_enable_time,
};

static const struct regulator_desc max20411_desc = {
        .ops = &max20411_ops,
        .owner = THIS_MODULE,
        .type = REGULATOR_VOLTAGE,
        .supply_name = "vin",
        .name = "max20411",

        /*
         * voltage = 0.24375V + selector * 6.25mV
         * with valid selector between 41 to 165 (0.5V to 1.275V)
         */
        .min_uV = MAX20411_BASE_UV,
        .uV_step = MAX20411_UV_STEP,
        .linear_min_sel = MAX20411_MIN_SEL,
        .n_voltages = MAX20411_MAX_SEL + 1,

        .vsel_reg = MAX20411_VID_OFFSET,
        .vsel_mask = MAX20411_VID_MASK,

        .ramp_reg = MAX20411_SLEW_OFFSET,
        .ramp_mask = MAX20411_SLEW_DVS_MASK,
        .ramp_delay_table = max20411_slew_rates,
        .n_ramp_values = ARRAY_SIZE(max20411_slew_rates),
};

static int max20411_probe(struct i2c_client *client)
{
        struct regulator_init_data *init_data;
        struct device *dev = &client->dev;
        struct regulator_config cfg = {};
        struct max20411 *max20411;

        max20411 = devm_kzalloc(dev, sizeof(*max20411), GFP_KERNEL);
        if (!max20411)
                return -ENOMEM;

        max20411->regmap = devm_regmap_init_i2c(client, &max20411_regmap_config);
        if (IS_ERR(max20411->regmap)) {
                dev_err(dev, "Failed to allocate regmap!\n");
                return PTR_ERR(max20411->regmap);
        }

        max20411->dev = dev;
        max20411->of_node = dev->of_node;

        max20411->desc = max20411_desc;
        init_data = of_get_regulator_init_data(max20411->dev, max20411->of_node, &max20411->desc);
        if (!init_data)
                return -ENODATA;

        cfg.dev = max20411->dev;
        cfg.init_data = init_data;
        cfg.of_node = max20411->of_node;
        cfg.driver_data = max20411;

        cfg.ena_gpiod = gpiod_get(max20411->dev, "enable", GPIOD_ASIS);
        if (IS_ERR(cfg.ena_gpiod))
                return dev_err_probe(dev, PTR_ERR(cfg.ena_gpiod),
                                     "unable to acquire enable gpio\n");

        max20411->rdev = devm_regulator_register(max20411->dev, &max20411->desc, &cfg);
        if (IS_ERR(max20411->rdev))
                dev_err(max20411->dev, "Failed to register regulator\n");

        return PTR_ERR_OR_ZERO(max20411->rdev);
}

static const struct of_device_id of_max20411_match_tbl[] = {
        { .compatible = "maxim,max20411", },
        { },
};
MODULE_DEVICE_TABLE(of, of_max20411_match_tbl);

static const struct i2c_device_id max20411_id[] = {
        { "max20411" },
        { }
};
MODULE_DEVICE_TABLE(i2c, max20411_id);

static struct i2c_driver max20411_i2c_driver = {
        .driver = {
                .name = "max20411",
                .probe_type = PROBE_PREFER_ASYNCHRONOUS,
                .of_match_table = of_max20411_match_tbl,
        },
        .probe = max20411_probe,
        .id_table = max20411_id,
};
module_i2c_driver(max20411_i2c_driver);

MODULE_DESCRIPTION("Maxim MAX20411 High-Efficiency Single Step-Down Converter driver");
MODULE_LICENSE("GPL");