root/drivers/regulator/max77838-regulator.c
// SPDX-License-Identifier: GPL-2.0-or-later
//
// regulator driver for Maxim MAX77838
//
// based on max77826-regulator.c
//
// Copyright (c) 2025, Ivaylo Ivanov <ivo.ivanov.ivanov1@gmail.com>

#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/err.h>
#include <linux/of.h>
#include <linux/platform_device.h>
#include <linux/regulator/driver.h>
#include <linux/regulator/of_regulator.h>
#include <linux/i2c.h>
#include <linux/regmap.h>

enum max77838_registers {
        MAX77838_REG_DEVICE_ID = 0x00,
        MAX77838_REG_TOPSYS_STAT,
        MAX77838_REG_STAT,
        MAX77838_REG_EN,
        MAX77838_REG_GPIO_PD_CTRL,
        MAX77838_REG_UVLO_CFG1,
        /* 0x06 - 0x0B: reserved */
        MAX77838_REG_I2C_CFG = 0x0C,
        /* 0x0D - 0x0F: reserved */
        MAX77838_REG_LDO1_CFG = 0x10,
        MAX77838_REG_LDO2_CFG,
        MAX77838_REG_LDO3_CFG,
        MAX77838_REG_LDO4_CFG,
        /* 0x14 - 0x1F: reserved */
        MAX77838_REG_BUCK_CFG1 = 0x20,
        MAX77838_REG_BUCK_VOUT,
};

enum max77838_regulators {
        MAX77838_LDO1 = 0,
        MAX77838_LDO2,
        MAX77838_LDO3,
        MAX77838_LDO4,
        MAX77838_BUCK,
        MAX77838_MAX_REGULATORS,
};

#define MAX77838_MASK_LDO               0x7f
#define MAX77838_MASK_BUCK              0xff

#define MAX77838_LDO1_EN                BIT(0)
#define MAX77838_LDO2_EN                BIT(1)
#define MAX77838_LDO3_EN                BIT(2)
#define MAX77838_LDO4_EN                BIT(3)
#define MAX77838_BUCK_EN                BIT(4)

#define MAX77838_BUCK_AD                BIT(3)
#define MAX77838_LDO_AD                 BIT(7)

#define MAX77838_LDO_VOLT_MIN           600000
#define MAX77838_LDO_VOLT_MAX           3775000
#define MAX77838_LDO_VOLT_STEP          25000

#define MAX77838_BUCK_VOLT_MIN          500000
#define MAX77838_BUCK_VOLT_MAX          2093750
#define MAX77838_BUCK_VOLT_STEP         6250

#define MAX77838_VOLT_RANGE(_type)                              \
        ((MAX77838_ ## _type ## _VOLT_MAX -                     \
          MAX77838_ ## _type ## _VOLT_MIN) /                    \
          MAX77838_ ## _type ## _VOLT_STEP + 1)

#define MAX77838_LDO(_id)                                                       \
        [MAX77838_LDO ## _id] = {                                               \
                .id = MAX77838_LDO ## _id,                                      \
                .name = "ldo"#_id,                                              \
                .of_match = of_match_ptr("ldo"#_id),                            \
                .regulators_node = "regulators",                                \
                .ops = &max77838_regulator_ops,                                 \
                .min_uV = MAX77838_LDO_VOLT_MIN,                                \
                .uV_step = MAX77838_LDO_VOLT_STEP,                              \
                .n_voltages = MAX77838_VOLT_RANGE(LDO),                         \
                .enable_reg = MAX77838_REG_EN,                                  \
                .enable_mask = MAX77838_LDO ## _id ## _EN,                      \
                .vsel_reg = MAX77838_REG_LDO ## _id ## _CFG,                    \
                .vsel_mask = MAX77838_MASK_LDO,                                 \
                .active_discharge_off = 0,                                      \
                .active_discharge_on = MAX77838_LDO_AD,                         \
                .active_discharge_mask = MAX77838_LDO_AD,                       \
                .active_discharge_reg = MAX77838_REG_LDO ## _id ## _CFG,        \
                .owner = THIS_MODULE,                                           \
        }

#define MAX77838_BUCK_DESC                                      \
        [MAX77838_BUCK] = {                                     \
                .id = MAX77838_BUCK,                            \
                .name = "buck",                                 \
                .of_match = of_match_ptr("buck"),               \
                .regulators_node = "regulators",                \
                .ops = &max77838_regulator_ops,                 \
                .min_uV = MAX77838_BUCK_VOLT_MIN,               \
                .uV_step = MAX77838_BUCK_VOLT_STEP,             \
                .n_voltages = MAX77838_VOLT_RANGE(BUCK),        \
                .enable_reg = MAX77838_REG_EN,                  \
                .enable_mask = MAX77838_BUCK_EN,                \
                .vsel_reg = MAX77838_REG_BUCK_VOUT,             \
                .vsel_mask = MAX77838_MASK_BUCK,                \
                .active_discharge_off = 0,                      \
                .active_discharge_on = MAX77838_BUCK_AD,        \
                .active_discharge_mask = MAX77838_BUCK_AD,      \
                .active_discharge_reg = MAX77838_REG_BUCK_CFG1, \
                .owner = THIS_MODULE,                           \
        }

struct max77838_regulator_info {
        struct regmap *regmap;
};

static const struct regmap_config max77838_regmap_config = {
        .reg_bits = 8,
        .val_bits = 8,
        .max_register = MAX77838_REG_BUCK_VOUT,
};

static const struct regulator_ops max77838_regulator_ops = {
        .enable                 = regulator_enable_regmap,
        .disable                = regulator_disable_regmap,
        .is_enabled             = regulator_is_enabled_regmap,
        .list_voltage           = regulator_list_voltage_linear,
        .map_voltage            = regulator_map_voltage_linear,
        .get_voltage_sel        = regulator_get_voltage_sel_regmap,
        .set_voltage_sel        = regulator_set_voltage_sel_regmap,
        .set_active_discharge   = regulator_set_active_discharge_regmap,
};

static const struct regulator_desc max77838_regulators_desc[] = {
        MAX77838_LDO(1),
        MAX77838_LDO(2),
        MAX77838_LDO(3),
        MAX77838_LDO(4),
        MAX77838_BUCK_DESC,
};

static int max77838_read_device_id(struct regmap *regmap, struct device *dev)
{
        unsigned int device_id;
        int ret;

        ret = regmap_read(regmap, MAX77838_REG_DEVICE_ID, &device_id);
        if (!ret)
                dev_dbg(dev, "DEVICE_ID: 0x%x\n", device_id);

        return ret;
}

static int max77838_i2c_probe(struct i2c_client *client)
{
        struct device *dev = &client->dev;
        struct max77838_regulator_info *info;
        struct regulator_config config = {};
        struct regulator_dev *rdev;
        struct regmap *regmap;
        int i;

        info = devm_kzalloc(dev, sizeof(struct max77838_regulator_info),
                            GFP_KERNEL);
        if (!info)
                return -ENOMEM;

        regmap = devm_regmap_init_i2c(client, &max77838_regmap_config);
        if (IS_ERR(regmap)) {
                dev_err(dev, "Failed to allocate regmap!\n");
                return PTR_ERR(regmap);
        }

        info->regmap = regmap;
        i2c_set_clientdata(client, info);

        config.dev = dev;
        config.regmap = regmap;
        config.driver_data = info;

        for (i = 0; i < MAX77838_MAX_REGULATORS; i++) {
                rdev = devm_regulator_register(dev,
                                               &max77838_regulators_desc[i],
                                               &config);
                if (IS_ERR(rdev)) {
                        dev_err(dev, "Failed to register regulator!\n");
                        return PTR_ERR(rdev);
                }
        }

        return max77838_read_device_id(regmap, dev);
}

static const struct of_device_id __maybe_unused max77838_of_match[] = {
        { .compatible = "maxim,max77838" },
        { /* sentinel */ }
};
MODULE_DEVICE_TABLE(of, max77838_of_match);

static const struct i2c_device_id max77838_id[] = {
        { "max77838-regulator" },
        { /* sentinel */ }
};
MODULE_DEVICE_TABLE(i2c, max77838_id);

static struct i2c_driver max77838_regulator_driver = {
        .driver = {
                .name = "max77838",
                .probe_type = PROBE_PREFER_ASYNCHRONOUS,
                .of_match_table = of_match_ptr(max77838_of_match),
        },
        .probe = max77838_i2c_probe,
        .id_table = max77838_id,
};
module_i2c_driver(max77838_regulator_driver);

MODULE_AUTHOR("Ivaylo Ivanov <ivo.ivanov.ivanov1@gmail.com>");
MODULE_DESCRIPTION("MAX77838 PMIC regulator driver");
MODULE_LICENSE("GPL");