// SPDX-License-Identifier: GPL-2.0+

#include <linux/bitops.h>
#include <linux/delay.h>
#include <linux/gpio/consumer.h>
#include <linux/i2c.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/regmap.h>
#include <linux/regulator/driver.h>
#include <linux/regulator/of_regulator.h>

#define RT6245_VIRT_OCLIMIT     0x00
#define RT6245_VIRT_OTLEVEL     0x01
#define RT6245_VIRT_PGDLYTIME   0x02
#define RT6245_VIRT_SLEWRATE    0x03
#define RT6245_VIRT_SWFREQ      0x04
#define RT6245_VIRT_VOUT        0x05

#define RT6245_VOUT_MASK        GENMASK(6, 0)
#define RT6245_SLEW_MASK        GENMASK(2, 0)
#define RT6245_CHKSUM_MASK      BIT(7)
#define RT6245_CODE_MASK        GENMASK(6, 0)

/* HW Enable + Soft start time */
#define RT6245_ENTIME_IN_US     5000

#define RT6245_VOUT_MINUV       437500
#define RT6245_VOUT_MAXUV       1387500
#define RT6245_VOUT_STEPUV      12500
#define RT6245_NUM_VOUT         ((RT6245_VOUT_MAXUV - RT6245_VOUT_MINUV) / RT6245_VOUT_STEPUV + 1)

struct rt6245_priv {
        struct gpio_desc *enable_gpio;
        bool enable_state;
};

static int rt6245_enable(struct regulator_dev *rdev)
{
        struct rt6245_priv *priv = rdev_get_drvdata(rdev);
        struct regmap *regmap = rdev_get_regmap(rdev);
        int ret;

        if (!priv->enable_gpio)
                return 0;

        gpiod_direction_output(priv->enable_gpio, 1);
        usleep_range(RT6245_ENTIME_IN_US, RT6245_ENTIME_IN_US + 1000);

        regcache_cache_only(regmap, false);
        ret = regcache_sync(regmap);
        if (ret)
                return ret;

        priv->enable_state = true;
        return 0;
}

static int rt6245_disable(struct regulator_dev *rdev)
{
        struct rt6245_priv *priv = rdev_get_drvdata(rdev);
        struct regmap *regmap = rdev_get_regmap(rdev);

        if (!priv->enable_gpio)
                return -EINVAL;

        regcache_cache_only(regmap, true);
        regcache_mark_dirty(regmap);

        gpiod_direction_output(priv->enable_gpio, 0);

        priv->enable_state = false;
        return 0;
}

static int rt6245_is_enabled(struct regulator_dev *rdev)
{
        struct rt6245_priv *priv = rdev_get_drvdata(rdev);

        return priv->enable_state ? 1 : 0;
}

static const struct regulator_ops rt6245_regulator_ops = {
        .list_voltage = regulator_list_voltage_linear,
        .set_voltage_sel = regulator_set_voltage_sel_regmap,
        .get_voltage_sel = regulator_get_voltage_sel_regmap,
        .set_ramp_delay = regulator_set_ramp_delay_regmap,
        .enable = rt6245_enable,
        .disable = rt6245_disable,
        .is_enabled = rt6245_is_enabled,
};

/* ramp delay dividend is 12500 uV/uS, and divisor from 1 to 8 */
static const unsigned int rt6245_ramp_delay_table[] = {
        12500, 6250, 4167, 3125, 2500, 2083, 1786, 1562
};

static const struct regulator_desc rt6245_regulator_desc = {
        .name = "rt6245-regulator",
        .ops = &rt6245_regulator_ops,
        .type = REGULATOR_VOLTAGE,
        .min_uV = RT6245_VOUT_MINUV,
        .uV_step = RT6245_VOUT_STEPUV,
        .n_voltages = RT6245_NUM_VOUT,
        .ramp_delay_table = rt6245_ramp_delay_table,
        .n_ramp_values = ARRAY_SIZE(rt6245_ramp_delay_table),
        .owner = THIS_MODULE,
        .vsel_reg = RT6245_VIRT_VOUT,
        .vsel_mask = RT6245_VOUT_MASK,
        .ramp_reg = RT6245_VIRT_SLEWRATE,
        .ramp_mask = RT6245_SLEW_MASK,
};

static int rt6245_init_device_properties(struct device *dev)
{
        const struct {
                const char *name;
                unsigned int reg;
        } rt6245_props[] = {
                { "richtek,oc-level-select",  RT6245_VIRT_OCLIMIT },
                { "richtek,ot-level-select", RT6245_VIRT_OTLEVEL },
                { "richtek,pgdly-time-select", RT6245_VIRT_PGDLYTIME },
                { "richtek,switch-freq-select", RT6245_VIRT_SWFREQ }
        };
        struct regmap *regmap = dev_get_regmap(dev, NULL);
        u8 propval;
        int i, ret;

        for (i = 0; i < ARRAY_SIZE(rt6245_props); i++) {
                ret = device_property_read_u8(dev, rt6245_props[i].name, &propval);
                if (ret)
                        continue;

                ret = regmap_write(regmap, rt6245_props[i].reg, propval);
                if (ret) {
                        dev_err(dev, "Fail to apply [%s:%d]\n", rt6245_props[i].name, propval);
                        return ret;
                }
        }

        return 0;
}

static int rt6245_reg_write(void *context, unsigned int reg, unsigned int val)
{
        struct i2c_client *i2c = context;
        static const u8 func_base[] = { 0x6F, 0x73, 0x78, 0x61, 0x7C, 0 };
        unsigned int code, bit_count;

        code = func_base[reg];
        code += val;

        /* xor checksum for bit 6 to 0 */
        bit_count = hweight8(code & RT6245_CODE_MASK);
        if (bit_count % 2)
                code |= RT6245_CHKSUM_MASK;
        else
                code &= ~RT6245_CHKSUM_MASK;

        return i2c_smbus_write_byte(i2c, code);
}

static const struct reg_default rt6245_reg_defaults[] = {
        /* Default over current 14A */
        { RT6245_VIRT_OCLIMIT, 2 },
        /* Default over temperature 150'c */
        { RT6245_VIRT_OTLEVEL, 0 },
        /* Default power good delay time 10us */
        { RT6245_VIRT_PGDLYTIME, 1 },
        /* Default slewrate 12.5mV/uS */
        { RT6245_VIRT_SLEWRATE, 0 },
        /* Default switch frequency 800KHz */
        { RT6245_VIRT_SWFREQ, 1 },
        /* Default voltage 750mV */
        { RT6245_VIRT_VOUT, 0x19 }
};

static const struct regmap_config rt6245_regmap_config = {
        .reg_bits = 8,
        .val_bits = 8,
        .max_register = RT6245_VIRT_VOUT,
        .cache_type = REGCACHE_FLAT,
        .reg_defaults = rt6245_reg_defaults,
        .num_reg_defaults = ARRAY_SIZE(rt6245_reg_defaults),
        .reg_write = rt6245_reg_write,
};

static int rt6245_probe(struct i2c_client *i2c)
{
        struct rt6245_priv *priv;
        struct regmap *regmap;
        struct regulator_config regulator_cfg = {};
        struct regulator_dev *rdev;
        int ret;

        priv = devm_kzalloc(&i2c->dev, sizeof(*priv), GFP_KERNEL);
        if (!priv)
                return -ENOMEM;

        priv->enable_state = true;

        priv->enable_gpio = devm_gpiod_get_optional(&i2c->dev, "enable", GPIOD_OUT_HIGH);
        if (IS_ERR(priv->enable_gpio)) {
                dev_err(&i2c->dev, "Failed to get 'enable' gpio\n");
                return PTR_ERR(priv->enable_gpio);
        }

        usleep_range(RT6245_ENTIME_IN_US, RT6245_ENTIME_IN_US + 1000);

        regmap = devm_regmap_init(&i2c->dev, NULL, i2c, &rt6245_regmap_config);
        if (IS_ERR(regmap)) {
                dev_err(&i2c->dev, "Failed to initialize the regmap\n");
                return PTR_ERR(regmap);
        }

        ret = rt6245_init_device_properties(&i2c->dev);
        if (ret) {
                dev_err(&i2c->dev, "Failed to initialize device properties\n");
                return ret;
        }

        regulator_cfg.dev = &i2c->dev;
        regulator_cfg.of_node = i2c->dev.of_node;
        regulator_cfg.regmap = regmap;
        regulator_cfg.driver_data = priv;
        regulator_cfg.init_data = of_get_regulator_init_data(&i2c->dev, i2c->dev.of_node,
                                                             &rt6245_regulator_desc);
        rdev = devm_regulator_register(&i2c->dev, &rt6245_regulator_desc, &regulator_cfg);
        if (IS_ERR(rdev)) {
                dev_err(&i2c->dev, "Failed to register regulator\n");
                return PTR_ERR(rdev);
        }

        return 0;
}

static const struct of_device_id __maybe_unused rt6245_of_match_table[] = {
        { .compatible = "richtek,rt6245", },
        {}
};
MODULE_DEVICE_TABLE(of, rt6245_of_match_table);

static struct i2c_driver rt6245_driver = {
        .driver = {
                .name = "rt6245",
                .probe_type = PROBE_PREFER_ASYNCHRONOUS,
                .of_match_table = rt6245_of_match_table,
        },
        .probe = rt6245_probe,
};
module_i2c_driver(rt6245_driver);

MODULE_AUTHOR("ChiYuan Huang <cy_huang@richtek.com>");
MODULE_DESCRIPTION("Richtek RT6245 Regulator Driver");
MODULE_LICENSE("GPL v2");