// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * rmi-i2c.c - Side band RMI over I2C support for AMD out
 *             of band management
 *
 * Copyright (C) 2024 Advanced Micro Devices, Inc.
 */

#include <linux/delay.h>
#include <linux/err.h>
#include <linux/i2c.h>
#include <linux/i3c/device.h>
#include <linux/i3c/master.h>
#include <linux/init.h>
#include <linux/module.h>
#include <linux/mutex.h>
#include <linux/of.h>
#include <linux/regmap.h>
#include "rmi-core.h"

#define REV_TWO_BYTE_ADDR       0x21

static int sbrmi_enable_alert(struct sbrmi_data *data)
{
        int ctrl, ret;

        /*
         * Enable the SB-RMI Software alert status
         * by writing 0 to bit 4 of Control register(0x1)
         */
        ret = regmap_read(data->regmap, SBRMI_CTRL, &ctrl);
        if (ret < 0)
                return ret;

        if (ctrl & 0x10) {
                ctrl &= ~0x10;
                return regmap_write(data->regmap, SBRMI_CTRL, ctrl);
        }

        return 0;
}

static int sbrmi_get_max_pwr_limit(struct sbrmi_data *data)
{
        struct apml_mbox_msg msg = { 0 };
        int ret;

        msg.cmd = SBRMI_READ_PKG_MAX_PWR_LIMIT;
        ret = rmi_mailbox_xfer(data, &msg);
        if (ret < 0)
                return ret;
        data->pwr_limit_max = msg.mb_in_out;

        return ret;
}

static int sbrmi_common_probe(struct device *dev, struct regmap *regmap, uint8_t address)
{
        struct sbrmi_data *data;
        int ret;

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

        data->regmap = regmap;
        mutex_init(&data->lock);

        /* Enable alert for SB-RMI sequence */
        ret = sbrmi_enable_alert(data);
        if (ret < 0)
                return ret;

        /* Cache maximum power limit */
        ret = sbrmi_get_max_pwr_limit(data);
        if (ret < 0)
                return ret;

        data->dev_static_addr = address;

        dev_set_drvdata(dev, data);

        ret = create_hwmon_sensor_device(dev, data);
        if (ret < 0)
                return ret;
        return create_misc_rmi_device(data, dev);
}

static struct regmap_config sbrmi_regmap_config = {
        .reg_bits = 8,
        .val_bits = 8,
};

static struct regmap_config sbrmi_regmap_config_ext = {
        .reg_bits = 16,
        .val_bits = 8,
        .reg_format_endian = REGMAP_ENDIAN_LITTLE,
};

static int sbrmi_i2c_probe(struct i2c_client *client)
{
        struct device *dev = &client->dev;
        struct regmap *regmap;
        int rev, ret;

        regmap = devm_regmap_init_i2c(client, &sbrmi_regmap_config);
        if (IS_ERR(regmap))
                return PTR_ERR(regmap);

        ret = regmap_read(regmap, SBRMI_REV, &rev);
        if (ret)
                return ret;

        /*
         * For Turin and newer platforms, revision is 0x21 or later. This is
         * to identify the two byte register address size. However, one
         * byte transaction can be successful.
         * Verify if revision is 0x21 or later, if yes, switch to 2 byte
         * address size.
         * Continuously using 1 byte address for revision 0x21 or later can lead
         * to bus corruption.
         */
        if (rev >= REV_TWO_BYTE_ADDR) {
                regmap = devm_regmap_init_i2c(client, &sbrmi_regmap_config_ext);
                if (IS_ERR(regmap))
                        return PTR_ERR(regmap);
        }
        return sbrmi_common_probe(dev, regmap, client->addr);
}

static void sbrmi_i2c_remove(struct i2c_client *client)
{
        struct sbrmi_data *data = dev_get_drvdata(&client->dev);

        misc_deregister(&data->sbrmi_misc_dev);
        /* Assign fops and parent of misc dev to NULL */
        data->sbrmi_misc_dev.fops = NULL;
        data->sbrmi_misc_dev.parent = NULL;
        dev_info(&client->dev, "Removed sbrmi-i2c driver\n");
        return;
}

static const struct i2c_device_id sbrmi_id[] = {
        {"sbrmi-i2c"},
        {}
};
MODULE_DEVICE_TABLE(i2c, sbrmi_id);

static const struct of_device_id __maybe_unused sbrmi_of_match[] = {
        {
                .compatible = "amd,sbrmi",
        },
        { },
};
MODULE_DEVICE_TABLE(of, sbrmi_of_match);

static struct i2c_driver sbrmi_driver = {
        .driver = {
                .name = "sbrmi-i2c",
                .of_match_table = of_match_ptr(sbrmi_of_match),
        },
        .probe = sbrmi_i2c_probe,
        .remove = sbrmi_i2c_remove,
        .id_table = sbrmi_id,
};

static int sbrmi_i3c_probe(struct i3c_device *i3cdev)
{
        struct device *dev = i3cdev_to_dev(i3cdev);
        struct regmap *regmap;
        int rev, ret;

        regmap = devm_regmap_init_i3c(i3cdev, &sbrmi_regmap_config);
        if (IS_ERR(regmap))
                return PTR_ERR(regmap);

        ret = regmap_read(regmap, SBRMI_REV, &rev);
        if (ret)
                return ret;

        /*
         * For Turin and newer platforms, revision is 0x21 or later. This is
         * to identify the two byte register address size. However, one
         * byte transaction can be successful.
         * Verify if revision is 0x21 or later, if yes, switch to 2 byte
         * address size.
         * Continuously using 1 byte address for revision 0x21 or later can lead
         * to bus corruption.
         */
        if (rev >= REV_TWO_BYTE_ADDR) {
                regmap = devm_regmap_init_i3c(i3cdev, &sbrmi_regmap_config_ext);
                if (IS_ERR(regmap))
                        return PTR_ERR(regmap);
        }

        /*
         * AMD APML I3C devices support static address.
         * If static address is defined, dynamic address is same as static address.
         * In case static address is not defined, I3C master controller defined
         * dynamic address is used.
         */
        return sbrmi_common_probe(dev, regmap, i3cdev->desc->info.dyn_addr);
}

static void sbrmi_i3c_remove(struct i3c_device *i3cdev)
{
        struct sbrmi_data *data = dev_get_drvdata(&i3cdev->dev);

        misc_deregister(&data->sbrmi_misc_dev);
}

static const struct i3c_device_id sbrmi_i3c_id[] = {
        /* PID for AMD SBRMI device */
        I3C_DEVICE_EXTRA_INFO(0x112, 0x0, 0x2, NULL),
        {}
};
MODULE_DEVICE_TABLE(i3c, sbrmi_i3c_id);

static struct i3c_driver sbrmi_i3c_driver = {
        .driver = {
                .name = "sbrmi-i3c",
        },
        .probe = sbrmi_i3c_probe,
        .remove = sbrmi_i3c_remove,
        .id_table = sbrmi_i3c_id,
};

module_i3c_i2c_driver(sbrmi_i3c_driver, &sbrmi_driver);

MODULE_AUTHOR("Akshay Gupta <akshay.gupta@amd.com>");
MODULE_AUTHOR("Naveen Krishna Chatradhi <naveenkrishna.chatradhi@amd.com>");
MODULE_DESCRIPTION("Hwmon driver for AMD SB-RMI emulated sensor");
MODULE_LICENSE("GPL");