// SPDX-License-Identifier: GPL-2.0
/*
 * Hardware monitoring driver for Maxim MAX16508, MAX16600, MAX16601,
 * and MAX16602.
 *
 * Implementation notes:
 *
 * This chip series supports two rails, VCORE and VSA. Telemetry information
 * for the two rails is reported in two subsequent I2C addresses. The driver
 * instantiates a dummy I2C client at the second I2C address to report
 * information for the VSA rail in a single instance of the driver.
 * Telemetry for the VSA rail is reported to the PMBus core in PMBus page 2.
 *
 * The chip reports input current using two separate methods. The input current
 * reported with the standard READ_IIN command is derived from the output
 * current. The first method is reported to the PMBus core with PMBus page 0,
 * the second method is reported with PMBus page 1.
 *
 * The chip supports reading per-phase temperatures and per-phase input/output
 * currents for VCORE. Telemetry is reported in vendor specific registers.
 * The driver translates the vendor specific register values to PMBus standard
 * register values and reports per-phase information in PMBus page 0.
 *
 * Copyright 2019, 2020 Google LLC.
 */

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

#include "pmbus.h"

enum chips { max16508, max16600, max16601, max16602 };

#define REG_DEFAULT_NUM_POP     0xc4
#define REG_SETPT_DVID          0xd1
#define  DAC_10MV_MODE          BIT(4)
#define REG_IOUT_AVG_PK         0xee
#define REG_IIN_SENSOR          0xf1
#define REG_TOTAL_INPUT_POWER   0xf2
#define REG_PHASE_ID            0xf3
#define  CORE_RAIL_INDICATOR    BIT(7)
#define REG_PHASE_REPORTING     0xf4

#define MAX16601_NUM_PHASES     8

struct max16601_data {
        enum chips id;
        struct pmbus_driver_info info;
        struct i2c_client *vsa;
        int iout_avg_pkg;
};

#define to_max16601_data(x) container_of(x, struct max16601_data, info)

static int max16601_read_byte(struct i2c_client *client, int page, int reg)
{
        const struct pmbus_driver_info *info = pmbus_get_driver_info(client);
        struct max16601_data *data = to_max16601_data(info);

        if (page > 0) {
                if (page == 2)  /* VSA */
                        return i2c_smbus_read_byte_data(data->vsa, reg);
                return -EOPNOTSUPP;
        }
        return -ENODATA;
}

static int max16601_read_word(struct i2c_client *client, int page, int phase,
                              int reg)
{
        const struct pmbus_driver_info *info = pmbus_get_driver_info(client);
        struct max16601_data *data = to_max16601_data(info);
        u8 buf[I2C_SMBUS_BLOCK_MAX + 1];
        int ret;

        switch (page) {
        case 0:         /* VCORE */
                if (phase == 0xff)
                        return -ENODATA;
                switch (reg) {
                case PMBUS_READ_IIN:
                case PMBUS_READ_IOUT:
                case PMBUS_READ_TEMPERATURE_1:
                        ret = i2c_smbus_write_byte_data(client, REG_PHASE_ID,
                                                        phase);
                        if (ret)
                                return ret;
                        ret = i2c_smbus_read_block_data(client,
                                                        REG_PHASE_REPORTING,
                                                        buf);
                        if (ret < 0)
                                return ret;
                        if (ret < 6)
                                return -EIO;
                        switch (reg) {
                        case PMBUS_READ_TEMPERATURE_1:
                                return buf[1] << 8 | buf[0];
                        case PMBUS_READ_IOUT:
                                return buf[3] << 8 | buf[2];
                        case PMBUS_READ_IIN:
                                return buf[5] << 8 | buf[4];
                        default:
                                break;
                        }
                }
                return -EOPNOTSUPP;
        case 1:         /* VCORE, read IIN/PIN from sensor element */
                switch (reg) {
                case PMBUS_READ_IIN:
                        return i2c_smbus_read_word_data(client, REG_IIN_SENSOR);
                case PMBUS_READ_PIN:
                        return i2c_smbus_read_word_data(client,
                                                        REG_TOTAL_INPUT_POWER);
                default:
                        break;
                }
                return -EOPNOTSUPP;
        case 2:         /* VSA */
                switch (reg) {
                case PMBUS_VIRT_READ_IOUT_MAX:
                        ret = i2c_smbus_read_word_data(data->vsa,
                                                       REG_IOUT_AVG_PK);
                        if (ret < 0)
                                return ret;
                        if (sign_extend32(ret, 10) >
                            sign_extend32(data->iout_avg_pkg, 10))
                                data->iout_avg_pkg = ret;
                        return data->iout_avg_pkg;
                case PMBUS_VIRT_RESET_IOUT_HISTORY:
                        return 0;
                case PMBUS_IOUT_OC_FAULT_LIMIT:
                case PMBUS_IOUT_OC_WARN_LIMIT:
                case PMBUS_OT_FAULT_LIMIT:
                case PMBUS_OT_WARN_LIMIT:
                case PMBUS_READ_IIN:
                case PMBUS_READ_IOUT:
                case PMBUS_READ_TEMPERATURE_1:
                case PMBUS_STATUS_WORD:
                        return i2c_smbus_read_word_data(data->vsa, reg);
                default:
                        return -EOPNOTSUPP;
                }
        default:
                return -EOPNOTSUPP;
        }
}

static int max16601_write_byte(struct i2c_client *client, int page, u8 reg)
{
        const struct pmbus_driver_info *info = pmbus_get_driver_info(client);
        struct max16601_data *data = to_max16601_data(info);

        if (page == 2) {
                if (reg == PMBUS_CLEAR_FAULTS)
                        return i2c_smbus_write_byte(data->vsa, reg);
                return -EOPNOTSUPP;
        }
        return -ENODATA;
}

static int max16601_write_word(struct i2c_client *client, int page, int reg,
                               u16 value)
{
        const struct pmbus_driver_info *info = pmbus_get_driver_info(client);
        struct max16601_data *data = to_max16601_data(info);

        switch (page) {
        case 0:         /* VCORE */
                return -ENODATA;
        case 1:         /* VCORE IIN/PIN from sensor element */
        default:
                return -EOPNOTSUPP;
        case 2:         /* VSA */
                switch (reg) {
                case PMBUS_VIRT_RESET_IOUT_HISTORY:
                        data->iout_avg_pkg = 0xfc00;
                        return 0;
                case PMBUS_IOUT_OC_FAULT_LIMIT:
                case PMBUS_IOUT_OC_WARN_LIMIT:
                case PMBUS_OT_FAULT_LIMIT:
                case PMBUS_OT_WARN_LIMIT:
                        return i2c_smbus_write_word_data(data->vsa, reg, value);
                default:
                        return -EOPNOTSUPP;
                }
        }
}

static int max16601_identify(struct i2c_client *client,
                             struct pmbus_driver_info *info)
{
        struct max16601_data *data = to_max16601_data(info);
        int reg;

        reg = i2c_smbus_read_byte_data(client, REG_SETPT_DVID);
        if (reg < 0)
                return reg;
        if (reg & DAC_10MV_MODE)
                info->vrm_version[0] = vr13;
        else
                info->vrm_version[0] = vr12;

        if (data->id != max16600 && data->id != max16601 && data->id != max16602)
                return 0;

        reg = i2c_smbus_read_byte_data(client, REG_DEFAULT_NUM_POP);
        if (reg < 0)
                return reg;

        /*
         * If REG_DEFAULT_NUM_POP returns 0, we don't know how many phases
         * are populated. Stick with the default in that case.
         */
        reg &= 0x0f;
        if (reg && reg <= MAX16601_NUM_PHASES)
                info->phases[0] = reg;

        return 0;
}

static struct pmbus_driver_info max16601_info = {
        .pages = 3,
        .format[PSC_VOLTAGE_IN] = linear,
        .format[PSC_VOLTAGE_OUT] = vid,
        .format[PSC_CURRENT_IN] = linear,
        .format[PSC_CURRENT_OUT] = linear,
        .format[PSC_TEMPERATURE] = linear,
        .format[PSC_POWER] = linear,
        .func[0] = PMBUS_HAVE_VIN | PMBUS_HAVE_IIN | PMBUS_HAVE_PIN |
                PMBUS_HAVE_STATUS_INPUT |
                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_PAGE_VIRTUAL | PMBUS_PHASE_VIRTUAL,
        .func[1] = PMBUS_HAVE_IIN | PMBUS_HAVE_PIN | PMBUS_PAGE_VIRTUAL,
        .func[2] = PMBUS_HAVE_IIN | PMBUS_HAVE_STATUS_INPUT |
                PMBUS_HAVE_IOUT | PMBUS_HAVE_STATUS_IOUT |
                PMBUS_HAVE_TEMP | PMBUS_HAVE_STATUS_TEMP | PMBUS_PAGE_VIRTUAL,
        .phases[0] = MAX16601_NUM_PHASES,
        .pfunc[0] = PMBUS_HAVE_IIN | PMBUS_HAVE_IOUT | PMBUS_HAVE_TEMP,
        .pfunc[1] = PMBUS_HAVE_IIN | PMBUS_HAVE_IOUT,
        .pfunc[2] = PMBUS_HAVE_IIN | PMBUS_HAVE_IOUT | PMBUS_HAVE_TEMP,
        .pfunc[3] = PMBUS_HAVE_IIN | PMBUS_HAVE_IOUT,
        .pfunc[4] = PMBUS_HAVE_IIN | PMBUS_HAVE_IOUT | PMBUS_HAVE_TEMP,
        .pfunc[5] = PMBUS_HAVE_IIN | PMBUS_HAVE_IOUT,
        .pfunc[6] = PMBUS_HAVE_IIN | PMBUS_HAVE_IOUT | PMBUS_HAVE_TEMP,
        .pfunc[7] = PMBUS_HAVE_IIN | PMBUS_HAVE_IOUT,
        .identify = max16601_identify,
        .read_byte_data = max16601_read_byte,
        .read_word_data = max16601_read_word,
        .write_byte = max16601_write_byte,
        .write_word_data = max16601_write_word,
};

static void max16601_remove(void *_data)
{
        struct max16601_data *data = _data;

        i2c_unregister_device(data->vsa);
}

static const struct i2c_device_id max16601_id[] = {
        {"max16508", max16508},
        {"max16600", max16600},
        {"max16601", max16601},
        {"max16602", max16602},
        {}
};
MODULE_DEVICE_TABLE(i2c, max16601_id);

static int max16601_get_id(struct i2c_client *client)
{
        struct device *dev = &client->dev;
        u8 buf[I2C_SMBUS_BLOCK_MAX + 1];
        enum chips id;
        int ret;

        ret = i2c_smbus_read_block_data(client, PMBUS_IC_DEVICE_ID, buf);
        if (ret < 0 || ret < 11)
                return -ENODEV;

        /*
         * PMBUS_IC_DEVICE_ID is expected to return MAX1660[012]y.xx",
         * "MAX16500y.xx".cdxxcccccccccc, or "MAX16508y.xx".
         */
        if (!strncmp(buf, "MAX16500", 8) || !strncmp(buf, "MAX16508", 8)) {
                id = max16508;
        } else if (!strncmp(buf, "MAX16600", 8)) {
                id = max16600;
        } else if (!strncmp(buf, "MAX16601", 8)) {
                id = max16601;
        } else if (!strncmp(buf, "MAX16602", 8)) {
                id = max16602;
        } else {
                buf[ret] = '\0';
                dev_err(dev, "Unsupported chip '%s'\n", buf);
                return -ENODEV;
        }
        return id;
}

static int max16601_probe(struct i2c_client *client)
{
        struct device *dev = &client->dev;
        const struct i2c_device_id *id;
        struct max16601_data *data;
        int ret, chip_id;

        if (!i2c_check_functionality(client->adapter,
                                     I2C_FUNC_SMBUS_READ_BYTE_DATA |
                                     I2C_FUNC_SMBUS_READ_BLOCK_DATA))
                return -ENODEV;

        chip_id = max16601_get_id(client);
        if (chip_id < 0)
                return chip_id;

        id = i2c_match_id(max16601_id, client);
        if (chip_id != id->driver_data)
                dev_warn(&client->dev,
                         "Device mismatch: Configured %s (%d), detected %d\n",
                         id->name, (int) id->driver_data, chip_id);

        ret = i2c_smbus_read_byte_data(client, REG_PHASE_ID);
        if (ret < 0)
                return ret;
        if (!(ret & CORE_RAIL_INDICATOR)) {
                dev_err(dev,
                        "Driver must be instantiated on CORE rail I2C address\n");
                return -ENODEV;
        }

        data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL);
        if (!data)
                return -ENOMEM;

        data->id = chip_id;
        data->iout_avg_pkg = 0xfc00;
        data->vsa = i2c_new_dummy_device(client->adapter, client->addr + 1);
        if (IS_ERR(data->vsa)) {
                dev_err(dev, "Failed to register VSA client\n");
                return PTR_ERR(data->vsa);
        }
        ret = devm_add_action_or_reset(dev, max16601_remove, data);
        if (ret)
                return ret;

        data->info = max16601_info;

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

static struct i2c_driver max16601_driver = {
        .driver = {
                   .name = "max16601",
                   },
        .probe = max16601_probe,
        .id_table = max16601_id,
};

module_i2c_driver(max16601_driver);

MODULE_AUTHOR("Guenter Roeck <linux@roeck-us.net>");
MODULE_DESCRIPTION("PMBus driver for Maxim MAX16601");
MODULE_LICENSE("GPL v2");
MODULE_IMPORT_NS("PMBUS");