// SPDX-License-Identifier: GPL-2.0-or-later
//
// max20086-regulator.c - MAX20086-MAX20089 camera power protector driver
//
// Copyright (C) 2022 Laurent Pinchart <laurent.pinchart@idesonboard.com>
// Copyright (C) 2018 Avnet, Inc.

#include <linux/cleanup.h>
#include <linux/err.h>
#include <linux/gpio/consumer.h>
#include <linux/i2c.h>
#include <linux/module.h>
#include <linux/regmap.h>
#include <linux/regulator/driver.h>
#include <linux/regulator/machine.h>
#include <linux/regulator/of_regulator.h>
#include <linux/slab.h>

/* Register Offset */
#define MAX20086_REG_MASK               0x00
#define MAX20086_REG_CONFIG             0x01
#define MAX20086_REG_ID                 0x02
#define MAX20086_REG_STAT1              0x03
#define MAX20086_REG_STAT2_L            0x04
#define MAX20086_REG_STAT2_H            0x05
#define MAX20086_REG_ADC1               0x06
#define MAX20086_REG_ADC2               0x07
#define MAX20086_REG_ADC3               0x08
#define MAX20086_REG_ADC4               0x09

/* DEVICE IDs */
#define MAX20086_DEVICE_ID_MAX20086     0x30
#define MAX20086_DEVICE_ID_MAX20087     0x20
#define MAX20086_DEVICE_ID_MAX20088     0x10
#define MAX20086_DEVICE_ID_MAX20089     0x00
#define DEVICE_ID_MASK                  0xf0

/* Register bits */
#define MAX20086_EN_MASK                0x0f
#define MAX20086_EN_OUT1                0x01
#define MAX20086_EN_OUT2                0x02
#define MAX20086_EN_OUT3                0x04
#define MAX20086_EN_OUT4                0x08
#define MAX20086_INT_DISABLE_ALL        0x3f

#define MAX20086_MAX_REGULATORS         4

struct max20086_chip_info {
        u8 id;
        unsigned int num_outputs;
};

struct max20086_regulator {
        struct device_node *of_node;
        struct regulator_init_data *init_data;
        const struct regulator_desc *desc;
        struct regulator_dev *rdev;
};

struct max20086 {
        struct device *dev;
        struct regmap *regmap;
        struct gpio_desc *ena_gpiod;

        const struct max20086_chip_info *info;

        struct max20086_regulator regulators[MAX20086_MAX_REGULATORS];
};

static const struct regulator_ops max20086_buck_ops = {
        .enable = regulator_enable_regmap,
        .disable = regulator_disable_regmap,
        .is_enabled = regulator_is_enabled_regmap,
};

#define MAX20086_REGULATOR_DESC(n)              \
{                                               \
        .name = "OUT"#n,                        \
        .supply_name = "in",                    \
        .id = (n) - 1,                          \
        .ops = &max20086_buck_ops,              \
        .type = REGULATOR_VOLTAGE,              \
        .owner = THIS_MODULE,                   \
        .enable_reg = MAX20086_REG_CONFIG,      \
        .enable_mask = 1 << ((n) - 1),          \
        .enable_val = 1 << ((n) - 1),           \
        .disable_val = 0,                       \
}

static const char * const max20086_output_names[] = {
        "OUT1",
        "OUT2",
        "OUT3",
        "OUT4",
};

static const struct regulator_desc max20086_regulators[] = {
        MAX20086_REGULATOR_DESC(1),
        MAX20086_REGULATOR_DESC(2),
        MAX20086_REGULATOR_DESC(3),
        MAX20086_REGULATOR_DESC(4),
};

static int max20086_regulators_register(struct max20086 *chip)
{
        unsigned int i;

        for (i = 0; i < chip->info->num_outputs; i++) {
                struct max20086_regulator *reg = &chip->regulators[i];
                struct regulator_config config = { };
                struct regulator_dev *rdev;

                config.dev = chip->dev;
                config.init_data = reg->init_data;
                config.driver_data = chip;
                config.of_node = reg->of_node;
                config.regmap = chip->regmap;
                config.ena_gpiod = chip->ena_gpiod;

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

                reg->rdev = rdev;
        }

        return 0;
}

static int max20086_parse_regulators_dt(struct max20086 *chip, bool *boot_on)
{
        struct of_regulator_match *matches;
        unsigned int i;
        int ret;

        struct device_node *node __free(device_node) =
                of_get_child_by_name(chip->dev->of_node, "regulators");
        if (!node) {
                dev_err(chip->dev, "regulators node not found\n");
                return -ENODEV;
        }

        matches = devm_kcalloc(chip->dev, chip->info->num_outputs,
                               sizeof(*matches), GFP_KERNEL);
        if (!matches)
                return -ENOMEM;

        for (i = 0; i < chip->info->num_outputs; ++i)
                matches[i].name = max20086_output_names[i];

        ret = of_regulator_match(chip->dev, node, matches,
                                 chip->info->num_outputs);
        if (ret < 0) {
                dev_err(chip->dev, "Failed to match regulators\n");
                return -EINVAL;
        }

        *boot_on = false;

        for (i = 0; i < chip->info->num_outputs; i++) {
                struct max20086_regulator *reg = &chip->regulators[i];

                reg->init_data = matches[i].init_data;
                reg->of_node = matches[i].of_node;
                reg->desc = &max20086_regulators[i];

                if (reg->init_data) {
                        if (reg->init_data->constraints.always_on ||
                            reg->init_data->constraints.boot_on)
                                *boot_on = true;
                }
        }

        return 0;
}

static int max20086_detect(struct max20086 *chip)
{
        unsigned int data;
        int ret;

        ret = regmap_read(chip->regmap, MAX20086_REG_ID, &data);
        if (ret < 0) {
                dev_err(chip->dev, "Failed to read DEVICE_ID reg: %d\n", ret);
                return ret;
        }

        if ((data & DEVICE_ID_MASK) != chip->info->id) {
                dev_err(chip->dev, "Invalid device ID 0x%02x\n", data);
                return -ENXIO;
        }

        return 0;
}

static bool max20086_gen_is_writeable_reg(struct device *dev, unsigned int reg)
{
        switch (reg) {
        case MAX20086_REG_MASK:
        case MAX20086_REG_CONFIG:
                return true;
        default:
                return false;
        }
}

static const struct regmap_config max20086_regmap_config = {
        .reg_bits = 8,
        .val_bits = 8,
        .writeable_reg = max20086_gen_is_writeable_reg,
        .max_register = 0x9,
        .cache_type = REGCACHE_NONE,
};

static int max20086_i2c_probe(struct i2c_client *i2c)
{
        struct max20086 *chip;
        enum gpiod_flags flags;
        bool boot_on;
        int ret;

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

        chip->dev = &i2c->dev;
        chip->info = i2c_get_match_data(i2c);

        i2c_set_clientdata(i2c, chip);

        chip->regmap = devm_regmap_init_i2c(i2c, &max20086_regmap_config);
        if (IS_ERR(chip->regmap)) {
                ret = PTR_ERR(chip->regmap);
                dev_err(chip->dev, "Failed to allocate register map: %d\n", ret);
                return ret;
        }

        ret = max20086_parse_regulators_dt(chip, &boot_on);
        if (ret < 0)
                return ret;

        ret = max20086_detect(chip);
        if (ret < 0)
                return ret;

        /* Until IRQ support is added, just disable all interrupts. */
        ret = regmap_update_bits(chip->regmap, MAX20086_REG_MASK,
                                 MAX20086_INT_DISABLE_ALL,
                                 MAX20086_INT_DISABLE_ALL);
        if (ret < 0) {
                dev_err(chip->dev, "Failed to disable interrupts: %d\n", ret);
                return ret;
        }

        /*
         * Get the enable GPIO. If any of the outputs is marked as being
         * enabled at boot, request the GPIO with an initial high state to
         * avoid disabling outputs that may have been turned on by the boot
         * loader. Otherwise, request it with a low state to enter lower-power
         * shutdown.
         */
        flags = boot_on ? GPIOD_OUT_HIGH : GPIOD_OUT_LOW;
        chip->ena_gpiod = devm_gpiod_get_optional(chip->dev, "enable", flags);
        if (IS_ERR(chip->ena_gpiod)) {
                ret = PTR_ERR(chip->ena_gpiod);
                dev_err(chip->dev, "Failed to get enable GPIO: %d\n", ret);
                return ret;
        }

        ret = max20086_regulators_register(chip);
        if (ret < 0) {
                dev_err(chip->dev, "Failed to register regulators: %d\n", ret);
                return ret;
        }

        return 0;
}

static const struct max20086_chip_info max20086_chip_info = {
        .id = MAX20086_DEVICE_ID_MAX20086,
        .num_outputs = 4,
};

static const struct max20086_chip_info max20087_chip_info = {
        .id = MAX20086_DEVICE_ID_MAX20087,
        .num_outputs = 4,
};

static const struct max20086_chip_info max20088_chip_info = {
        .id = MAX20086_DEVICE_ID_MAX20088,
        .num_outputs = 2,
};

static const struct max20086_chip_info max20089_chip_info = {
        .id = MAX20086_DEVICE_ID_MAX20089,
        .num_outputs = 2,
};

static const struct i2c_device_id max20086_i2c_id[] = {
        { "max20086", (kernel_ulong_t)&max20086_chip_info },
        { "max20087", (kernel_ulong_t)&max20087_chip_info },
        { "max20088", (kernel_ulong_t)&max20088_chip_info },
        { "max20089", (kernel_ulong_t)&max20089_chip_info },
        { /* Sentinel */ }
};
MODULE_DEVICE_TABLE(i2c, max20086_i2c_id);

static const struct of_device_id max20086_dt_ids[] __maybe_unused = {
        { .compatible = "maxim,max20086", .data = &max20086_chip_info },
        { .compatible = "maxim,max20087", .data = &max20087_chip_info },
        { .compatible = "maxim,max20088", .data = &max20088_chip_info },
        { .compatible = "maxim,max20089", .data = &max20089_chip_info },
        { /* Sentinel */ }
};
MODULE_DEVICE_TABLE(of, max20086_dt_ids);

static struct i2c_driver max20086_regulator_driver = {
        .driver = {
                .name = "max20086",
                .probe_type = PROBE_PREFER_ASYNCHRONOUS,
                .of_match_table = of_match_ptr(max20086_dt_ids),
        },
        .probe = max20086_i2c_probe,
        .id_table = max20086_i2c_id,
};

module_i2c_driver(max20086_regulator_driver);

MODULE_AUTHOR("Watson Chow <watson.chow@avnet.com>");
MODULE_DESCRIPTION("MAX20086-MAX20089 Camera Power Protector Driver");
MODULE_LICENSE("GPL");