// SPDX-License-Identifier: GPL-2.0-only
// SPDX-FileCopyrightText: 2024 CERN (home.cern)
/*
 * Hardware monitoring driver for Hi-Tron HAC300S PSU.
 *
 * NOTE: The HAC300S device does not support the PMBUS_VOUT_MODE register.
 * On top of that, it returns the Voltage output values in Linear11 which is
 * not adhering to the PMBus specifications. (PMBus Specification Part II,
 * Section 7.1-7.3). For that reason the PMBUS_VOUT_MODE register is being faked
 * and returns the exponent value of the READ_VOUT register. The exponent part
 * of the VOUT_* registers is being cleared in order to return the mantissa to
 * the pmbus core.
 */

#include <linux/bitfield.h>
#include <linux/bits.h>
#include <linux/err.h>
#include <linux/i2c.h>
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/pmbus.h>

#include "pmbus.h"

#define LINEAR11_EXPONENT_MASK GENMASK(15, 11)
#define LINEAR11_MANTISSA_MASK GENMASK(10, 0)

#define to_hac300s_data(x) container_of(x, struct hac300s_data, info)

struct hac300s_data {
        struct pmbus_driver_info info;
        s8 exponent;
};

static int hac300s_read_byte_data(struct i2c_client *client, int page, int reg)
{
        const struct pmbus_driver_info *info = pmbus_get_driver_info(client);
        struct hac300s_data *data = to_hac300s_data(info);

        if (reg == PMBUS_VOUT_MODE)
                return data->exponent;

        return -ENODATA;
}

static int hac300s_read_word_data(struct i2c_client *client, int page,
                                  int phase, int reg)
{
        int rv;

        switch (reg) {
        case PMBUS_VOUT_OV_WARN_LIMIT:
        case PMBUS_VOUT_UV_WARN_LIMIT:
        case PMBUS_VOUT_OV_FAULT_LIMIT:
        case PMBUS_VOUT_UV_FAULT_LIMIT:
        case PMBUS_MFR_VOUT_MAX:
        case PMBUS_MFR_VOUT_MIN:
        case PMBUS_READ_VOUT:
                rv = pmbus_read_word_data(client, page, phase, reg);
                if (rv < 0)
                        return rv;
                return FIELD_GET(LINEAR11_MANTISSA_MASK, rv);
        default:
                return -ENODATA;
        }
}

static struct pmbus_driver_info hac300s_info = {
        .pages = 1,
        .func[0] = PMBUS_HAVE_TEMP | PMBUS_HAVE_TEMP2 | \
                   PMBUS_HAVE_VOUT | PMBUS_HAVE_STATUS_VOUT | \
                   PMBUS_HAVE_IOUT | PMBUS_HAVE_STATUS_IOUT | \
                   PMBUS_HAVE_POUT | PMBUS_HAVE_STATUS_TEMP,
        .read_byte_data = hac300s_read_byte_data,
        .read_word_data = hac300s_read_word_data,
        .format[PSC_VOLTAGE_OUT] = linear,
};

static struct pmbus_platform_data hac300s_pdata = {
        .flags = PMBUS_NO_CAPABILITY,
};

static int hac300s_probe(struct i2c_client *client)
{
        struct hac300s_data *data;
        int rv;

        data = devm_kzalloc(&client->dev, sizeof(struct hac300s_data), GFP_KERNEL);
        if (!data)
                return -ENOMEM;

        if (!i2c_check_functionality(client->adapter,
                                     I2C_FUNC_SMBUS_READ_BYTE_DATA |
                                     I2C_FUNC_SMBUS_READ_WORD_DATA))
                return -ENODEV;

        rv = i2c_smbus_read_word_data(client, PMBUS_READ_VOUT);
        if (rv < 0)
                return dev_err_probe(&client->dev, rv, "Failed to read vout_mode\n");

        data->exponent = FIELD_GET(LINEAR11_EXPONENT_MASK, rv);
        data->info = hac300s_info;
        client->dev.platform_data = &hac300s_pdata;
        return pmbus_do_probe(client, &data->info);
}

static const struct of_device_id hac300s_of_match[] = {
        { .compatible = "hitron,hac300s" },
        {}
};
MODULE_DEVICE_TABLE(of, hac300s_of_match);

static const struct i2c_device_id hac300s_id[] = {
        {"hac300s", 0},
        {}
};
MODULE_DEVICE_TABLE(i2c, hac300s_id);

static struct i2c_driver hac300s_driver = {
        .driver = {
                   .name = "hac300s",
                   .of_match_table = hac300s_of_match,
        },
        .probe = hac300s_probe,
        .id_table = hac300s_id,

};
module_i2c_driver(hac300s_driver);

MODULE_AUTHOR("Vasileios Amoiridis");
MODULE_DESCRIPTION("PMBus driver for Hi-Tron HAC300S PSU");
MODULE_LICENSE("GPL");
MODULE_IMPORT_NS("PMBUS");