// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * Hardware monitoring driver for MPS Multi-phase Digital VR Controllers
 *
 * Copyright (C) 2020 Nvidia Technologies Ltd.
 */

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

/* Vendor specific registers. */
#define MP2888_MFR_SYS_CONFIG   0x44
#define MP2888_MFR_READ_CS1_2   0x73
#define MP2888_MFR_READ_CS3_4   0x74
#define MP2888_MFR_READ_CS5_6   0x75
#define MP2888_MFR_READ_CS7_8   0x76
#define MP2888_MFR_READ_CS9_10  0x77
#define MP2888_MFR_VR_CONFIG1   0xe1

#define MP2888_TOTAL_CURRENT_RESOLUTION BIT(3)
#define MP2888_PHASE_CURRENT_RESOLUTION BIT(4)
#define MP2888_DRMOS_KCS                GENMASK(2, 0)
#define MP2888_TEMP_UNIT                10
#define MP2888_MAX_PHASE                10

struct mp2888_data {
        struct pmbus_driver_info info;
        int total_curr_resolution;
        int phase_curr_resolution;
        int curr_sense_gain;
};

#define to_mp2888_data(x)       container_of(x, struct mp2888_data, info)

static int mp2888_read_byte_data(struct i2c_client *client, int page, int reg)
{
        switch (reg) {
        case PMBUS_VOUT_MODE:
                /* Enforce VOUT direct format. */
                return PB_VOUT_MODE_DIRECT;
        default:
                return -ENODATA;
        }
}

static int
mp2888_current_sense_gain_and_resolution_get(struct i2c_client *client, struct mp2888_data *data)
{
        int ret;

        /*
         * Obtain DrMOS current sense gain of power stage from the register
         * , bits 0-2. The value is selected as below:
         * 00b - 5µA/A, 01b - 8.5µA/A, 10b - 9.7µA/A, 11b - 10µA/A. Other
         * values are reserved.
         */
        ret = i2c_smbus_read_word_data(client, MP2888_MFR_SYS_CONFIG);
        if (ret < 0)
                return ret;

        switch (ret & MP2888_DRMOS_KCS) {
        case 0:
                data->curr_sense_gain = 85;
                break;
        case 1:
                data->curr_sense_gain = 97;
                break;
        case 2:
                data->curr_sense_gain = 100;
                break;
        case 3:
                data->curr_sense_gain = 50;
                break;
        default:
                return -EINVAL;
        }

        /*
         * Obtain resolution selector for total and phase current report and protection.
         * 0: original resolution; 1: half resolution (in such case phase current value should
         * be doubled.
         */
        data->total_curr_resolution = (ret & MP2888_TOTAL_CURRENT_RESOLUTION) >> 3;
        data->phase_curr_resolution = (ret & MP2888_PHASE_CURRENT_RESOLUTION) >> 4;

        return 0;
}

static int
mp2888_read_phase(struct i2c_client *client, struct mp2888_data *data, int page, int phase, u8 reg)
{
        int ret;

        ret = pmbus_read_word_data(client, page, phase, reg);
        if (ret < 0)
                return ret;

        if (!((phase + 1) % 2))
                ret >>= 8;
        ret &= 0xff;

        /*
         * Output value is calculated as: (READ_CSx / 80 – 1.23) / (Kcs * Rcs)
         * where:
         * - Kcs is the DrMOS current sense gain of power stage, which is obtained from the
         *   register MP2888_MFR_VR_CONFIG1, bits 13-12 with the following selection of DrMOS
         *   (data->curr_sense_gain):
         *   00b - 8.5µA/A, 01b - 9.7µA/A, 1b - 10µA/A, 11b - 5µA/A.
         * - Rcs is the internal phase current sense resistor. This parameter depends on hardware
         *   assembly. By default it is set to 1kΩ. In case of different assembly, user should
         *   scale this parameter by dividing it by Rcs.
         * If phase current resolution bit is set to 1, READ_CSx value should be doubled.
         * Note, that current phase sensing, providing by the device is not accurate. This is
         * because sampling of current occurrence of bit weight has a big deviation, especially for
         * light load.
         */
        ret = DIV_ROUND_CLOSEST(ret * 200 - 19600, data->curr_sense_gain);
        /* Scale according to total current resolution. */
        ret = (data->total_curr_resolution) ? ret * 2 : ret;
        return ret;
}

static int
mp2888_read_phases(struct i2c_client *client, struct mp2888_data *data, int page, int phase)
{
        int ret;

        switch (phase) {
        case 0 ... 1:
                ret = mp2888_read_phase(client, data, page, phase, MP2888_MFR_READ_CS1_2);
                break;
        case 2 ... 3:
                ret = mp2888_read_phase(client, data, page, phase, MP2888_MFR_READ_CS3_4);
                break;
        case 4 ... 5:
                ret = mp2888_read_phase(client, data, page, phase, MP2888_MFR_READ_CS5_6);
                break;
        case 6 ... 7:
                ret = mp2888_read_phase(client, data, page, phase, MP2888_MFR_READ_CS7_8);
                break;
        case 8 ... 9:
                ret = mp2888_read_phase(client, data, page, phase, MP2888_MFR_READ_CS9_10);
                break;
        default:
                return -ENODATA;
        }
        return ret;
}

static int mp2888_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 mp2888_data *data = to_mp2888_data(info);
        int ret;

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

                /*
                 * READ_VIN requires fixup to scale it to linear11 format. Register data format
                 * provides 10 bits for mantissa and 6 bits for exponent. Bits 15:10 are set with
                 * the fixed value 111011b.
                 */
                ret = (ret & GENMASK(9, 0)) | ((ret & GENMASK(31, 10)) << 1);
                break;
        case PMBUS_OT_WARN_LIMIT:
                ret = pmbus_read_word_data(client, page, phase, reg);
                if (ret < 0)
                        return ret;
                /*
                 * Chip reports limits in degrees C, but the actual temperature in 10th of
                 * degrees C - scaling is needed to match both.
                 */
                ret *= MP2888_TEMP_UNIT;
                break;
        case PMBUS_READ_IOUT:
                if (phase != 0xff)
                        return mp2888_read_phases(client, data, page, phase);

                ret = pmbus_read_word_data(client, page, phase, reg);
                if (ret < 0)
                        return ret;
                /*
                 * READ_IOUT register has unused bits 15:12 with fixed value 1110b. Clear these
                 * bits and scale with total current resolution. Data is provided in direct format.
                 */
                ret &= GENMASK(11, 0);
                ret = data->total_curr_resolution ? ret * 2 : ret;
                break;
        case PMBUS_IOUT_OC_WARN_LIMIT:
                ret = pmbus_read_word_data(client, page, phase, reg);
                if (ret < 0)
                        return ret;
                ret &= GENMASK(9, 0);
                /*
                 * Chip reports limits with resolution 1A or 2A, if total current resolution bit is
                 * set 1. Actual current is reported with 0.25A or respectively 0.5A resolution.
                 * Scaling is needed to match both.
                 */
                ret = data->total_curr_resolution ? ret * 8 : ret * 4;
                break;
        case PMBUS_READ_POUT:
        case PMBUS_READ_PIN:
                ret = pmbus_read_word_data(client, page, phase, reg);
                if (ret < 0)
                        return ret;
                ret = data->total_curr_resolution ? ret : DIV_ROUND_CLOSEST(ret, 2);
                break;
        case PMBUS_POUT_OP_WARN_LIMIT:
                ret = pmbus_read_word_data(client, page, phase, reg);
                if (ret < 0)
                        return ret;
                /*
                 * Chip reports limits with resolution 1W or 2W, if total current resolution bit is
                 * set 1. Actual power is reported with 0.5W or 1W respectively resolution. Scaling
                 * is needed to match both.
                 */
                ret = data->total_curr_resolution ? ret * 2 : ret;
                break;
        /*
         * The below registers are not implemented by device or implemented not according to the
         * spec. Skip all of them to avoid exposing non-relevant inputs to sysfs.
         */
        case PMBUS_OT_FAULT_LIMIT:
        case PMBUS_UT_WARN_LIMIT:
        case PMBUS_UT_FAULT_LIMIT:
        case PMBUS_VIN_UV_FAULT_LIMIT:
        case PMBUS_VOUT_UV_WARN_LIMIT:
        case PMBUS_VOUT_OV_WARN_LIMIT:
        case PMBUS_VOUT_UV_FAULT_LIMIT:
        case PMBUS_VOUT_OV_FAULT_LIMIT:
        case PMBUS_VIN_OV_WARN_LIMIT:
        case PMBUS_IOUT_OC_LV_FAULT_LIMIT:
        case PMBUS_IOUT_OC_FAULT_LIMIT:
        case PMBUS_POUT_MAX:
        case PMBUS_IOUT_UC_FAULT_LIMIT:
        case PMBUS_POUT_OP_FAULT_LIMIT:
        case PMBUS_PIN_OP_WARN_LIMIT:
        case PMBUS_MFR_VIN_MIN:
        case PMBUS_MFR_VOUT_MIN:
        case PMBUS_MFR_VIN_MAX:
        case PMBUS_MFR_VOUT_MAX:
        case PMBUS_MFR_IIN_MAX:
        case PMBUS_MFR_IOUT_MAX:
        case PMBUS_MFR_PIN_MAX:
        case PMBUS_MFR_POUT_MAX:
        case PMBUS_MFR_MAX_TEMP_1:
                return -ENXIO;
        default:
                return -ENODATA;
        }

        return ret;
}

static int mp2888_write_word_data(struct i2c_client *client, int page, int reg, u16 word)
{
        const struct pmbus_driver_info *info = pmbus_get_driver_info(client);
        struct mp2888_data *data = to_mp2888_data(info);

        switch (reg) {
        case PMBUS_OT_WARN_LIMIT:
                word = DIV_ROUND_CLOSEST(word, MP2888_TEMP_UNIT);
                /* Drop unused bits 15:8. */
                word = clamp_val(word, 0, GENMASK(7, 0));
                break;
        case PMBUS_IOUT_OC_WARN_LIMIT:
                /* Fix limit according to total curent resolution. */
                word = data->total_curr_resolution ? DIV_ROUND_CLOSEST(word, 8) :
                       DIV_ROUND_CLOSEST(word, 4);
                /* Drop unused bits 15:10. */
                word = clamp_val(word, 0, GENMASK(9, 0));
                break;
        case PMBUS_POUT_OP_WARN_LIMIT:
                /* Fix limit according to total curent resolution. */
                word = data->total_curr_resolution ? DIV_ROUND_CLOSEST(word, 4) :
                       DIV_ROUND_CLOSEST(word, 2);
                /* Drop unused bits 15:10. */
                word = clamp_val(word, 0, GENMASK(9, 0));
                break;
        default:
                return -ENODATA;
        }
        return pmbus_write_word_data(client, page, reg, word);
}

static int
mp2888_identify_multiphase(struct i2c_client *client, struct mp2888_data *data,
                           struct pmbus_driver_info *info)
{
        int ret;

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

        /* Identify multiphase number - could be from 1 to 10. */
        ret = i2c_smbus_read_word_data(client, MP2888_MFR_VR_CONFIG1);
        if (ret <= 0)
                return ret;

        info->phases[0] = ret & GENMASK(3, 0);

        /*
         * The device provides a total of 10 PWM pins, and can be configured to different phase
         * count applications for rail.
         */
        if (info->phases[0] > MP2888_MAX_PHASE)
                return -EINVAL;

        return 0;
}

static struct pmbus_driver_info mp2888_info = {
        .pages = 1,
        .format[PSC_VOLTAGE_IN] = linear,
        .format[PSC_VOLTAGE_OUT] = direct,
        .format[PSC_TEMPERATURE] = direct,
        .format[PSC_CURRENT_IN] = linear,
        .format[PSC_CURRENT_OUT] = direct,
        .format[PSC_POWER] = direct,
        .m[PSC_TEMPERATURE] = 1,
        .R[PSC_TEMPERATURE] = 1,
        .m[PSC_VOLTAGE_OUT] = 1,
        .R[PSC_VOLTAGE_OUT] = 3,
        .m[PSC_CURRENT_OUT] = 4,
        .m[PSC_POWER] = 1,
        .func[0] = PMBUS_HAVE_VIN | PMBUS_HAVE_VOUT | PMBUS_HAVE_STATUS_VOUT | PMBUS_HAVE_IOUT |
                   PMBUS_HAVE_STATUS_IOUT | PMBUS_HAVE_TEMP | PMBUS_HAVE_STATUS_TEMP |
                   PMBUS_HAVE_POUT | PMBUS_HAVE_PIN | PMBUS_HAVE_STATUS_INPUT |
                   PMBUS_PHASE_VIRTUAL,
        .pfunc[0] = PMBUS_HAVE_IOUT,
        .pfunc[1] = PMBUS_HAVE_IOUT,
        .pfunc[2] = PMBUS_HAVE_IOUT,
        .pfunc[3] = PMBUS_HAVE_IOUT,
        .pfunc[4] = PMBUS_HAVE_IOUT,
        .pfunc[5] = PMBUS_HAVE_IOUT,
        .pfunc[6] = PMBUS_HAVE_IOUT,
        .pfunc[7] = PMBUS_HAVE_IOUT,
        .pfunc[8] = PMBUS_HAVE_IOUT,
        .pfunc[9] = PMBUS_HAVE_IOUT,
        .read_byte_data = mp2888_read_byte_data,
        .read_word_data = mp2888_read_word_data,
        .write_word_data = mp2888_write_word_data,
};

static int mp2888_probe(struct i2c_client *client)
{
        struct pmbus_driver_info *info;
        struct mp2888_data *data;
        int ret;

        data = devm_kzalloc(&client->dev, sizeof(struct mp2888_data), GFP_KERNEL);
        if (!data)
                return -ENOMEM;

        memcpy(&data->info, &mp2888_info, sizeof(*info));
        info = &data->info;

        /* Identify multiphase configuration. */
        ret = mp2888_identify_multiphase(client, data, info);
        if (ret)
                return ret;

        /* Obtain current sense gain of power stage and current resolution. */
        ret = mp2888_current_sense_gain_and_resolution_get(client, data);
        if (ret)
                return ret;

        return pmbus_do_probe(client, info);
}

static const struct i2c_device_id mp2888_id[] = {
        {"mp2888"},
        {}
};

MODULE_DEVICE_TABLE(i2c, mp2888_id);

static const struct of_device_id __maybe_unused mp2888_of_match[] = {
        {.compatible = "mps,mp2888"},
        {}
};
MODULE_DEVICE_TABLE(of, mp2888_of_match);

static struct i2c_driver mp2888_driver = {
        .driver = {
                .name = "mp2888",
                .of_match_table = of_match_ptr(mp2888_of_match),
        },
        .probe = mp2888_probe,
        .id_table = mp2888_id,
};

module_i2c_driver(mp2888_driver);

MODULE_AUTHOR("Vadim Pasternak <vadimp@nvidia.com>");
MODULE_DESCRIPTION("PMBus driver for MPS MP2888 device");
MODULE_LICENSE("GPL");
MODULE_IMPORT_NS("PMBUS");