// SPDX-License-Identifier: GPL-2.0-or-later

#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"

/* LTC4286 register */
#define LTC4286_MFR_CONFIG1     0xF2

/* LTC4286 configuration */
#define VRANGE_SELECT_BIT       BIT(1)

#define LTC4286_MFR_ID_SIZE     3

/*
 * Initialize the MBR as default settings which is referred to LTC4286 datasheet
 * (March 22, 2022 version) table 3 page 16
 */
static struct pmbus_driver_info ltc4286_info = {
        .pages = 1,
        .format[PSC_VOLTAGE_IN] = direct,
        .format[PSC_VOLTAGE_OUT] = direct,
        .format[PSC_CURRENT_OUT] = direct,
        .format[PSC_POWER] = direct,
        .format[PSC_TEMPERATURE] = direct,
        .m[PSC_VOLTAGE_IN] = 32,
        .b[PSC_VOLTAGE_IN] = 0,
        .R[PSC_VOLTAGE_IN] = 1,
        .m[PSC_VOLTAGE_OUT] = 32,
        .b[PSC_VOLTAGE_OUT] = 0,
        .R[PSC_VOLTAGE_OUT] = 1,
        .m[PSC_CURRENT_OUT] = 1024,
        .b[PSC_CURRENT_OUT] = 0,
        /*
         * The rsense value used in MBR formula in LTC4286 datasheet should be ohm unit.
         * However, the rsense value that user input is micro ohm.
         * Thus, the MBR setting which involves rsense should be shifted by 6 digits.
         */
        .R[PSC_CURRENT_OUT] = 3 - 6,
        .m[PSC_POWER] = 1,
        .b[PSC_POWER] = 0,
        /*
         * The rsense value used in MBR formula in LTC4286 datasheet should be ohm unit.
         * However, the rsense value that user input is micro ohm.
         * Thus, the MBR setting which involves rsense should be shifted by 6 digits.
         */
        .R[PSC_POWER] = 4 - 6,
        .m[PSC_TEMPERATURE] = 1,
        .b[PSC_TEMPERATURE] = 273,
        .R[PSC_TEMPERATURE] = 0,
        .func[0] = PMBUS_HAVE_VIN | PMBUS_HAVE_VOUT | PMBUS_HAVE_IOUT |
                   PMBUS_HAVE_PIN | PMBUS_HAVE_TEMP | PMBUS_HAVE_STATUS_VOUT |
                   PMBUS_HAVE_STATUS_IOUT | PMBUS_HAVE_STATUS_TEMP,
};

static const struct i2c_device_id ltc4286_id[] = {
        { "ltc4286", },
        { "ltc4287", },
        {}
};
MODULE_DEVICE_TABLE(i2c, ltc4286_id);

static int ltc4286_probe(struct i2c_client *client)
{
        int ret;
        const struct i2c_device_id *mid;
        u8 block_buffer[I2C_SMBUS_BLOCK_MAX + 1];
        struct pmbus_driver_info *info;
        u32 rsense;
        int vrange_nval, vrange_oval;

        ret = i2c_smbus_read_block_data(client, PMBUS_MFR_ID, block_buffer);
        if (ret < 0) {
                return dev_err_probe(&client->dev, ret,
                                     "Failed to read manufacturer id\n");
        }

        /*
         * Refer to ltc4286 datasheet page 20
         * the manufacturer id is LTC
         */
        if (ret != LTC4286_MFR_ID_SIZE ||
            strncmp(block_buffer, "LTC", LTC4286_MFR_ID_SIZE)) {
                return dev_err_probe(&client->dev, -ENODEV,
                                     "Manufacturer id mismatch\n");
        }

        ret = i2c_smbus_read_block_data(client, PMBUS_MFR_MODEL, block_buffer);
        if (ret < 0) {
                return dev_err_probe(&client->dev, ret,
                                     "Failed to read manufacturer model\n");
        }

        for (mid = ltc4286_id; mid->name[0]; mid++) {
                if (!strncasecmp(mid->name, block_buffer, strlen(mid->name)))
                        break;
        }
        if (!mid->name[0])
                return dev_err_probe(&client->dev, -ENODEV,
                                     "Unsupported device\n");

        if (of_property_read_u32(client->dev.of_node,
                                 "shunt-resistor-micro-ohms", &rsense))
                rsense = 300; /* 0.3 mOhm if not set via DT */

        if (rsense == 0)
                return -EINVAL;

        /* Check for the latter MBR value won't overflow */
        if (rsense > (INT_MAX / 1024))
                return -EINVAL;

        info = devm_kmemdup(&client->dev, &ltc4286_info, sizeof(*info),
                            GFP_KERNEL);
        if (!info)
                return -ENOMEM;

        /* Check MFR1 CONFIG register bit 1 VRANGE_SELECT before driver loading */
        vrange_oval = i2c_smbus_read_word_data(client, LTC4286_MFR_CONFIG1);
        if (vrange_oval < 0)
                return dev_err_probe(&client->dev, vrange_oval,
                                     "Failed to read manufacturer configuration one\n");
        vrange_nval = vrange_oval;

        if (device_property_read_bool(&client->dev, "adi,vrange-low-enable")) {
                vrange_nval &=
                        ~VRANGE_SELECT_BIT; /* VRANGE_SELECT = 0, 25.6 volts */

                info->m[PSC_VOLTAGE_IN] = 128;
                info->m[PSC_VOLTAGE_OUT] = 128;
                info->m[PSC_POWER] = 4 * rsense;
        } else {
                vrange_nval |=
                        VRANGE_SELECT_BIT; /* VRANGE_SELECT = 1, 102.4 volts */

                info->m[PSC_POWER] = rsense;
        }
        if (vrange_nval != vrange_oval) {
                /* Set MFR1 CONFIG register bit 1 VRANGE_SELECT */
                ret = i2c_smbus_write_word_data(client, LTC4286_MFR_CONFIG1,
                                                vrange_nval);
                if (ret < 0)
                        return dev_err_probe(&client->dev, ret,
                                             "Failed to set vrange\n");
        }

        info->m[PSC_CURRENT_OUT] = 1024 * rsense;

        return pmbus_do_probe(client, info);
}

static const struct of_device_id ltc4286_of_match[] = {
        { .compatible = "lltc,ltc4286" },
        { .compatible = "lltc,ltc4287" },
        {}
};

static struct i2c_driver ltc4286_driver = {
        .driver = {
                .name = "ltc4286",
                .of_match_table = ltc4286_of_match,
        },
        .probe = ltc4286_probe,
        .id_table = ltc4286_id,
};

module_i2c_driver(ltc4286_driver);

MODULE_AUTHOR("Delphine CC Chiu <Delphine_CC_Chiu@wiwynn.com>");
MODULE_DESCRIPTION("PMBUS driver for LTC4286 and compatibles");
MODULE_LICENSE("GPL");
MODULE_IMPORT_NS("PMBUS");