// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * Hardware monitoring driver for MPS Multi-phase Digital VR Controllers(MP2985)
 *
 * Copyright (C) 2026 MPS
 */

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

/*
 * Vender specific register READ_PIN_EST(0x93), READ_IIN_EST(0x8E),
 * MFR_VR_MULTI_CONFIG_R1(0x0D) and MFR_VR_MULTI_CONFIG_R2(0x1D).
 * The READ_PIN_EST is used to read pin telemetry, the READ_IIN_EST
 * is used to read iin telemetry and the MFR_VR_MULTI_CONFIG_R1,
 * MFR_VR_MULTI_CONFIG_R2 are used to obtain vid scale.
 */
#define READ_PIN_EST    0x93
#define READ_IIN_EST    0x8E
#define MFR_VR_MULTI_CONFIG_R1  0x0D
#define MFR_VR_MULTI_CONFIG_R2  0x1D

#define MP2985_VOUT_DIV 64
#define MP2985_VOUT_OVUV_UINT   125
#define MP2985_VOUT_OVUV_DIV    64

#define MP2985_PAGE_NUM 2

#define MP2985_RAIL1_FUNC       (PMBUS_HAVE_VIN | PMBUS_HAVE_PIN | \
                                                         PMBUS_HAVE_VOUT | PMBUS_HAVE_IOUT | \
                                                         PMBUS_HAVE_POUT | PMBUS_HAVE_TEMP | \
                                                         PMBUS_HAVE_STATUS_VOUT | \
                                                         PMBUS_HAVE_STATUS_IOUT | \
                                                         PMBUS_HAVE_STATUS_TEMP | \
                                                         PMBUS_HAVE_STATUS_INPUT)

#define MP2985_RAIL2_FUNC       (PMBUS_HAVE_PIN | PMBUS_HAVE_VOUT | \
                                                         PMBUS_HAVE_IOUT | PMBUS_HAVE_POUT | \
                                                         PMBUS_HAVE_TEMP | PMBUS_HAVE_IIN | \
                                                         PMBUS_HAVE_STATUS_VOUT | \
                                                         PMBUS_HAVE_STATUS_IOUT | \
                                                         PMBUS_HAVE_STATUS_TEMP | \
                                                         PMBUS_HAVE_STATUS_INPUT)

struct mp2985_data {
        struct pmbus_driver_info info;
        int vout_scale[MP2985_PAGE_NUM];
        int vid_offset[MP2985_PAGE_NUM];
};

#define to_mp2985_data(x) container_of(x, struct mp2985_data, info)

static u16 mp2985_linear_exp_transfer(u16 word, u16 expect_exponent)
{
        s16 exponent, mantissa, target_exponent;

        exponent = ((s16)word) >> 11;
        mantissa = ((s16)((word & 0x7ff) << 5)) >> 5;
        target_exponent = (s16)((expect_exponent & 0x1f) << 11) >> 11;

        /*
         * The MP2985 does not support negtive limit value, if a negtive
         * limit value is written, the limit value will become to 0. And
         * the maximum positive limit value is limitted to 0x3FF.
         */
        if (mantissa < 0) {
                mantissa = 0;
        } else {
                if (exponent > target_exponent) {
                        mantissa = (1023 >> (exponent - target_exponent)) >= mantissa ?
                                                mantissa << (exponent - target_exponent) :
                                                0x3FF;
                } else {
                        mantissa = clamp_val(mantissa >> (target_exponent - exponent),
                                             0, 0x3FF);
                }
        }

        return mantissa | ((expect_exponent << 11) & 0xf800);
}

static int mp2985_read_byte_data(struct i2c_client *client, int page, int reg)
{
        int ret;

        switch (reg) {
        case PMBUS_VOUT_MODE:
                /*
                 * The MP2985 does not follow standard PMBus protocol completely,
                 * and the calculation of vout in this driver is based on direct
                 * format. As a result, the format of vout is enforced to direct.
                 */
                ret = PB_VOUT_MODE_DIRECT;
                break;
        default:
                ret = -ENODATA;
                break;
        }

        return ret;
}

static int mp2985_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 mp2985_data *data = to_mp2985_data(info);
        int ret;

        switch (reg) {
        case PMBUS_READ_VOUT:
                ret = pmbus_read_word_data(client, page, phase, reg);
                if (ret < 0)
                        return ret;

                /*
                 * The MP2985 supports three vout mode, direct, linear11 and vid mode.
                 * In vid mode, the MP2985 vout telemetry has 49 vid step offset, but
                 * PMBUS_VOUT_OV_FAULT_LIMIT and PMBUS_VOUT_UV_FAULT_LIMIT do not take
                 * this into consideration, their resolution are 1.953125mV/LSB, as a
                 * result, format[PSC_VOLTAGE_OUT] can not be set to vid mode directly.
                 * Adding extra vid_offset variable for vout telemetry.
                 */
                ret = clamp_val(DIV_ROUND_CLOSEST(((ret & GENMASK(11, 0)) +
                                                                        data->vid_offset[page]) *
                                                        data->vout_scale[page], MP2985_VOUT_DIV),
                                                        0, 0x7FFF);
                break;
        case PMBUS_READ_IIN:
                /*
                 * The MP2985 has standard PMBUS_READ_IIN register(0x89), but this is
                 * not used to read the input current of per rail. The input current
                 * is read through the vender redefined register READ_IIN_EST(0x8E).
                 */
                ret = pmbus_read_word_data(client, page, phase, READ_IIN_EST);
                break;
        case PMBUS_READ_PIN:
                /*
                 * The MP2985 has standard PMBUS_READ_PIN register(0x97), but this
                 * is not used to read the input power of per rail. The input power
                 * of per rail is read through the vender redefined register
                 * READ_PIN_EST(0x93).
                 */
                ret = pmbus_read_word_data(client, page, phase, READ_PIN_EST);
                break;
        case PMBUS_VOUT_OV_FAULT_LIMIT:
        case PMBUS_VOUT_UV_FAULT_LIMIT:
                ret = pmbus_read_word_data(client, page, phase, reg);
                if (ret < 0)
                        return ret;

                ret = DIV_ROUND_CLOSEST((ret & GENMASK(11, 0)) * MP2985_VOUT_OVUV_UINT,
                                        MP2985_VOUT_OVUV_DIV);
                break;
        case PMBUS_STATUS_WORD:
        case PMBUS_READ_VIN:
        case PMBUS_READ_IOUT:
        case PMBUS_READ_POUT:
        case PMBUS_READ_TEMPERATURE_1:
        case PMBUS_VIN_OV_FAULT_LIMIT:
        case PMBUS_VIN_OV_WARN_LIMIT:
        case PMBUS_VIN_UV_WARN_LIMIT:
        case PMBUS_VIN_UV_FAULT_LIMIT:
        case PMBUS_IOUT_OC_FAULT_LIMIT:
        case PMBUS_IOUT_OC_WARN_LIMIT:
        case PMBUS_OT_FAULT_LIMIT:
        case PMBUS_OT_WARN_LIMIT:
                /*
                 * These register is not explicitly handled by the driver,
                 * as a result, return -ENODATA directly.
                 */
                ret = -ENODATA;
                break;
        default:
                /*
                 * The MP2985 do not support other telemetry and limit value
                 * reading, so, return -EINVAL directly.
                 */
                ret = -EINVAL;
                break;
        }

        return ret;
}

static int mp2985_write_word_data(struct i2c_client *client, int page, int reg,
                                  u16 word)
{
        int ret;

        switch (reg) {
        case PMBUS_VIN_OV_FAULT_LIMIT:
        case PMBUS_VIN_OV_WARN_LIMIT:
        case PMBUS_VIN_UV_WARN_LIMIT:
        case PMBUS_VIN_UV_FAULT_LIMIT:
                /*
                 * The PMBUS_VIN_OV_FAULT_LIMIT, PMBUS_VIN_OV_WARN_LIMIT,
                 * PMBUS_VIN_UV_WARN_LIMIT and PMBUS_VIN_UV_FAULT_LIMIT
                 * of MP2985 is linear11 format, and the exponent is a
                 * constant value(5'b11101), so the exponent of word
                 * parameter should be converted to 5'b11101(0x1D).
                 */
                ret = pmbus_write_word_data(client, page, reg,
                                            mp2985_linear_exp_transfer(word, 0x1D));
                break;
        case PMBUS_VOUT_OV_FAULT_LIMIT:
        case PMBUS_VOUT_UV_FAULT_LIMIT:
                /*
                 * The bit0-bit11 is the limit value, and bit12-bit15
                 * should not be changed.
                 */
                ret = pmbus_read_word_data(client, page, 0xff, reg);
                if (ret < 0)
                        return ret;

                ret = pmbus_write_word_data(client, page, reg,
                                            (ret & ~GENMASK(11, 0)) |
                                clamp_val(DIV_ROUND_CLOSEST(word * MP2985_VOUT_OVUV_DIV,
                                                            MP2985_VOUT_OVUV_UINT), 0, 0xFFF));
                break;
        case PMBUS_OT_FAULT_LIMIT:
        case PMBUS_OT_WARN_LIMIT:
                /*
                 * The PMBUS_OT_FAULT_LIMIT and PMBUS_OT_WARN_LIMIT of
                 * MP2985 is linear11 format, and the exponent is a
                 * constant value(5'b00000), so the exponent of word
                 * parameter should be converted to 5'b00000.
                 */
                ret = pmbus_write_word_data(client, page, reg,
                                            mp2985_linear_exp_transfer(word, 0x00));
                break;
        case PMBUS_IOUT_OC_FAULT_LIMIT:
        case PMBUS_IOUT_OC_WARN_LIMIT:
                /*
                 * The PMBUS_IOUT_OC_FAULT_LIMIT and PMBUS_IOUT_OC_WARN_LIMIT
                 * of MP2985 is linear11 format, and the exponent can not be
                 * changed.
                 */
                ret = pmbus_read_word_data(client, page, 0xff, reg);
                if (ret < 0)
                        return ret;

                ret = pmbus_write_word_data(client, page, reg,
                                            mp2985_linear_exp_transfer(word,
                                                                       FIELD_GET(GENMASK(15, 11),
                                                                                 ret)));
                break;
        default:
                /*
                 * The MP2985 do not support other limit value configuration,
                 * so, return -EINVAL directly.
                 */
                ret = -EINVAL;
                break;
        }

        return ret;
}

static int
mp2985_identify_vout_scale(struct i2c_client *client, struct pmbus_driver_info *info,
                           int page)
{
        struct mp2985_data *data = to_mp2985_data(info);
        int ret;

        ret = i2c_smbus_write_byte_data(client, PMBUS_PAGE, page);
        if (ret < 0)
                return ret;

        ret = i2c_smbus_read_byte_data(client, PMBUS_VOUT_MODE);
        if (ret < 0)
                return ret;

        /*
         * The MP2985 supports three vout mode. If PMBUS_VOUT_MODE
         * bit5 is 1, it is vid mode. If PMBUS PMBUS_VOUT_MODE bit4
         * is 1, it is linear11 mode, the vout scale is 1.953125mv/LSB.
         * If PMBUS PMBUS_VOUT_MODE bit6 is 1, it is direct mode, the
         * vout scale is 1mv/LSB. In vid mode, the MP2985 vout telemetry
         * has 49 vid step offset.
         */
        if (FIELD_GET(BIT(5), ret)) {
                ret = i2c_smbus_write_byte_data(client, PMBUS_PAGE, 2);
                if (ret < 0)
                        return ret;

                ret = i2c_smbus_read_word_data(client, page == 0 ?
                                                MFR_VR_MULTI_CONFIG_R1 :
                                                MFR_VR_MULTI_CONFIG_R2);
                if (ret < 0)
                        return ret;

                if (page == 0) {
                        if (FIELD_GET(BIT(4), ret))
                                data->vout_scale[page] = 320;
                        else
                                data->vout_scale[page] = 640;
                } else {
                        if (FIELD_GET(BIT(3), ret))
                                data->vout_scale[page] = 320;
                        else
                                data->vout_scale[page] = 640;
                }

                data->vid_offset[page] = 49;

                /*
                 * For vid mode, the MP2985 should be changed to page 2
                 * to obtain vout scale value, this may confuse the PMBus
                 * core. To avoid this, switch back to the previous page
                 * again.
                 */
                ret = i2c_smbus_write_byte_data(client, PMBUS_PAGE, page);
                if (ret < 0)
                        return ret;
        } else if (FIELD_GET(BIT(4), ret)) {
                data->vout_scale[page] = 125;
                data->vid_offset[page] = 0;
        } else {
                data->vout_scale[page] = 64;
                data->vid_offset[page] = 0;
        }

        return 0;
}

static int mp2985_identify(struct i2c_client *client, struct pmbus_driver_info *info)
{
        int ret;

        ret = mp2985_identify_vout_scale(client, info, 0);
        if (ret < 0)
                return ret;

        return mp2985_identify_vout_scale(client, info, 1);
}

static struct pmbus_driver_info mp2985_info = {
        .pages = MP2985_PAGE_NUM,
        .format[PSC_VOLTAGE_IN] = linear,
        .format[PSC_CURRENT_IN] = linear,
        .format[PSC_CURRENT_OUT] = linear,
        .format[PSC_POWER] = linear,
        .format[PSC_TEMPERATURE] = linear,
        .format[PSC_VOLTAGE_OUT] = direct,

        .m[PSC_VOLTAGE_OUT] = 1,
        .R[PSC_VOLTAGE_OUT] = 3,
        .b[PSC_VOLTAGE_OUT] = 0,

        .func[0] = MP2985_RAIL1_FUNC,
        .func[1] = MP2985_RAIL2_FUNC,
        .read_word_data = mp2985_read_word_data,
        .read_byte_data = mp2985_read_byte_data,
        .write_word_data = mp2985_write_word_data,
        .identify = mp2985_identify,
};

static int mp2985_probe(struct i2c_client *client)
{
        struct mp2985_data *data;

        data = devm_kzalloc(&client->dev, sizeof(struct mp2985_data), GFP_KERNEL);
        if (!data)
                return -ENOMEM;

        memcpy(&data->info, &mp2985_info, sizeof(mp2985_info));

        return pmbus_do_probe(client, &data->info);
}

static const struct i2c_device_id mp2985_id[] = {
        {"mp2985", 0},
        {}
};
MODULE_DEVICE_TABLE(i2c, mp2985_id);

static const struct of_device_id __maybe_unused mp2985_of_match[] = {
        {.compatible = "mps,mp2985"},
        {}
};
MODULE_DEVICE_TABLE(of, mp2985_of_match);

static struct i2c_driver mp2985_driver = {
        .driver = {
                .name = "mp2985",
                .of_match_table = mp2985_of_match,
        },
        .probe = mp2985_probe,
        .id_table = mp2985_id,
};

module_i2c_driver(mp2985_driver);

MODULE_AUTHOR("Wensheng Wang <wenswang@yeah.net>");
MODULE_DESCRIPTION("PMBus driver for MPS MP2985 device");
MODULE_LICENSE("GPL");
MODULE_IMPORT_NS("PMBUS");