// SPDX-License-Identifier: GPL-2.0+
/*
 * mp5926.c  - pmbus driver for mps mp5926
 *
 * Copyright 2025 Monolithic Power Systems, Inc
 *
 * Author: Yuxi Wang <Yuxi.Wang@monolithicpower.com>
 */

#include <linux/bitfield.h>
#include <linux/bits.h>
#include <linux/i2c.h>
#include <linux/module.h>
#include <linux/of_device.h>
#include <linux/pmbus.h>
#include "pmbus.h"

#define PAGE    0x01
#define EFUSE_CFG       0xCF
#define I_SCALE_SEL     0xC6
#define MP5926_FUNC     (PMBUS_HAVE_VIN | PMBUS_HAVE_VOUT | \
                        PMBUS_HAVE_IIN | PMBUS_HAVE_PIN | \
                        PMBUS_HAVE_TEMP | PMBUS_HAVE_STATUS_INPUT | \
                        PMBUS_HAVE_STATUS_TEMP | PMBUS_HAVE_STATUS_VOUT)

struct mp5926_data {
        struct pmbus_driver_info info;
        u8 vout_mode;
        u8 vout_linear_exponent;
};

#define to_mp5926_data(x)  container_of(x, struct mp5926_data, info)

static int mp5926_read_byte_data(struct i2c_client *client, int page,
                                 int reg)
{
        const struct pmbus_driver_info *info = pmbus_get_driver_info(client);
        struct mp5926_data *data = to_mp5926_data(info);
        int ret;

        switch (reg) {
        case PMBUS_VOUT_MODE:
                if (data->vout_mode == linear) {
                        /*
                         * The VOUT format used by the chip is linear11,
                         * not linear16. Report that VOUT is in linear mode
                         * and return exponent value extracted while probing
                         * the chip.
                         */
                        return data->vout_linear_exponent;
                }
                return PB_VOUT_MODE_DIRECT;
        default:
                ret = -ENODATA;
                break;
        }
        return ret;
}

static int mp5926_read_word_data(struct i2c_client *client, int page, int phase,
                                 int reg)
{
        const struct pmbus_driver_info *info = pmbus_get_driver_info(client);
        struct mp5926_data *data = to_mp5926_data(info);
        int ret;

        switch (reg) {
        case PMBUS_READ_VOUT:
                ret = pmbus_read_word_data(client, page, phase, reg);
                if (ret < 0)
                        return ret;
                /*
                 * Because the VOUT format used by the chip is linear11 and not
                 * linear16, we disregard bits[15:11]. The exponent is reported
                 * as part of the VOUT_MODE command.
                 */
                if (data->vout_mode == linear)
                        ret = ((s16)((ret & 0x7ff) << 5)) >> 5;
                break;
        default:
                ret = -ENODATA;
                break;
        }
        return ret;
}

static struct pmbus_driver_info mp5926_info = {
        .pages = PAGE,
        .format[PSC_VOLTAGE_IN] = direct,
        .format[PSC_CURRENT_IN] = direct,
        .format[PSC_VOLTAGE_OUT] = direct,
        .format[PSC_TEMPERATURE] = direct,
        .format[PSC_POWER] = direct,

        .m[PSC_VOLTAGE_IN] = 16,
        .b[PSC_VOLTAGE_IN] = 0,
        .R[PSC_VOLTAGE_IN] = 0,

        .m[PSC_CURRENT_IN] = 16,
        .b[PSC_CURRENT_IN] = 0,
        .R[PSC_CURRENT_IN] = 0,

        .m[PSC_VOLTAGE_OUT] = 16,
        .b[PSC_VOLTAGE_OUT] = 0,
        .R[PSC_VOLTAGE_OUT] = 0,

        .m[PSC_TEMPERATURE] = 4,
        .b[PSC_TEMPERATURE] = 0,
        .R[PSC_TEMPERATURE] = 0,

        .m[PSC_POWER] = 25,
        .b[PSC_POWER] = 0,
        .R[PSC_POWER] = -2,

        .read_word_data = mp5926_read_word_data,
        .read_byte_data = mp5926_read_byte_data,
        .func[0] = MP5926_FUNC,
};

static int mp5926_probe(struct i2c_client *client)
{
        struct mp5926_data *data;
        struct pmbus_driver_info *info;
        int ret;

        data = devm_kzalloc(&client->dev, sizeof(struct mp5926_data),
                            GFP_KERNEL);
        if (!data)
                return -ENOMEM;

        memcpy(&data->info, &mp5926_info, sizeof(*info));
        info = &data->info;
        ret = i2c_smbus_read_word_data(client, EFUSE_CFG);
        if (ret < 0)
                return ret;
        if (ret & BIT(12)) {
                data->vout_mode = linear;
                data->info.format[PSC_VOLTAGE_IN] = linear;
                data->info.format[PSC_CURRENT_IN] = linear;
                data->info.format[PSC_VOLTAGE_OUT] = linear;
                data->info.format[PSC_TEMPERATURE] = linear;
                data->info.format[PSC_POWER] = linear;
                ret = i2c_smbus_read_word_data(client, PMBUS_READ_VOUT);
                if (ret < 0)
                        return dev_err_probe(&client->dev, ret, "Can't get vout exponent.");
                data->vout_linear_exponent = (u8)((ret >> 11) & 0x1f);
        } else {
                data->vout_mode = direct;
                ret = i2c_smbus_read_word_data(client, I_SCALE_SEL);
                if (ret < 0)
                        return ret;
                if (ret & BIT(6))
                        data->info.m[PSC_CURRENT_IN] = 4;
        }

        return pmbus_do_probe(client, info);
}

static const struct i2c_device_id mp5926_id[] = {
        { "mp5926", 0 },
        {}
};
MODULE_DEVICE_TABLE(i2c, mp5926_id);

static const struct of_device_id mp5926_of_match[] = {
        { .compatible = "mps,mp5926" },
        {}
};
MODULE_DEVICE_TABLE(of, mp5926_of_match);

static struct i2c_driver mp5926_driver = {
        .probe = mp5926_probe,
        .driver = {
                        .name = "mp5926",
                        .of_match_table = mp5926_of_match,
                   },
        .id_table = mp5926_id,
};

module_i2c_driver(mp5926_driver);
MODULE_AUTHOR("Yuxi Wang <Yuxi.Wang@monolithicpower.com>");
MODULE_DESCRIPTION("MPS MP5926 pmbus driver");
MODULE_LICENSE("GPL");
MODULE_IMPORT_NS("PMBUS");