// SPDX-License-Identifier: GPL-2.0
/*
 * Hardware monitoring driver for Analog Devices MAX20830
 *
 * Copyright (C) 2026 Analog Devices, Inc.
 */

#include <linux/errno.h>
#include <linux/i2c.h>
#include <linux/module.h>
#include <linux/string.h>
#include "pmbus.h"

#define MAX20830_IC_DEVICE_ID_LENGTH    9

static struct pmbus_driver_info max20830_info = {
        .pages = 1,
        .format[PSC_VOLTAGE_IN] = linear,
        .format[PSC_VOLTAGE_OUT] = linear,
        .format[PSC_CURRENT_OUT] = linear,
        .format[PSC_TEMPERATURE] = linear,
        .func[0] = PMBUS_HAVE_VIN | PMBUS_HAVE_VOUT | PMBUS_HAVE_IOUT |
                PMBUS_HAVE_TEMP |
                PMBUS_HAVE_STATUS_VOUT | PMBUS_HAVE_STATUS_IOUT |
                PMBUS_HAVE_STATUS_INPUT | PMBUS_HAVE_STATUS_TEMP,
};

static int max20830_probe(struct i2c_client *client)
{
        u8 buf[I2C_SMBUS_BLOCK_MAX + 1] = {};
        int ret;

        if (!i2c_check_functionality(client->adapter, I2C_FUNC_SMBUS_READ_BLOCK_DATA) &&
            !i2c_check_functionality(client->adapter, I2C_FUNC_SMBUS_READ_I2C_BLOCK))
                return -ENODEV;

        /*
         * Use i2c_smbus_read_block_data() if supported, otherwise fall back
         * to i2c_smbus_read_i2c_block_data() to support I2C controllers
         * which do not support SMBus block reads.
         */
        if (i2c_check_functionality(client->adapter, I2C_FUNC_SMBUS_READ_BLOCK_DATA)) {
                /* Reads 9 Data bytes from MAX20830 */
                ret = i2c_smbus_read_block_data(client, PMBUS_IC_DEVICE_ID, buf);
                if (ret < 0)
                        return dev_err_probe(&client->dev, ret,
                                             "Failed to read IC_DEVICE_ID\n");
        } else {
                /* Reads 1 length byte + 9 Data bytes from MAX20830 */
                ret = i2c_smbus_read_i2c_block_data(client, PMBUS_IC_DEVICE_ID,
                                                    MAX20830_IC_DEVICE_ID_LENGTH + 1,
                                                    buf);
                if (ret < 0)
                        return dev_err_probe(&client->dev, ret,
                                             "Failed to read IC_DEVICE_ID\n");
                /*
                 * Moves data forward, removing the length byte, this is to
                 * match the format of i2c_smbus_read_block_data().
                 * Also adjust return value to reflect length byte removal.
                 */
                memmove(buf, buf + 1, MAX20830_IC_DEVICE_ID_LENGTH);
                ret = ret - 1;
        }

        /*
         * MAX20830 IC_DEVICE_ID sends string data "MAX20830\0".
         * Return value should at least be 9 bytes of data.
         */
        if (ret < MAX20830_IC_DEVICE_ID_LENGTH)
                return dev_err_probe(&client->dev, -ENODEV,
                                     "IC_DEVICE_ID too short: expected at least 9 bytes, got %d\n",
                                     ret);

        /* 9 bytes of data, buf[0]-buf[7] = "MAX20830", buf[8] = '\0' */
        buf[MAX20830_IC_DEVICE_ID_LENGTH - 1] = '\0';
        if (strncmp(buf, "MAX20830", MAX20830_IC_DEVICE_ID_LENGTH - 1))
                return dev_err_probe(&client->dev, -ENODEV,
                                     "Unsupported device: '%s'\n", buf);

        return pmbus_do_probe(client, &max20830_info);
}

static const struct i2c_device_id max20830_id[] = {
        {"max20830"},
        { }
};
MODULE_DEVICE_TABLE(i2c, max20830_id);

static const struct of_device_id max20830_of_match[] = {
        { .compatible = "adi,max20830" },
        { }
};
MODULE_DEVICE_TABLE(of, max20830_of_match);

static struct i2c_driver max20830_driver = {
        .driver = {
                .name = "max20830",
                .of_match_table = max20830_of_match,
        },
        .probe = max20830_probe,
        .id_table = max20830_id,
};

module_i2c_driver(max20830_driver);

MODULE_AUTHOR("Alexis Czezar Torreno <alexisczezar.torreno@analog.com>");
MODULE_DESCRIPTION("PMBus driver for Analog Devices MAX20830");
MODULE_LICENSE("GPL");
MODULE_IMPORT_NS("PMBUS");