// SPDX-License-Identifier: GPL-2.0-or-later
/*
 *  Copyright (C) 2021 Thomas Weißschuh <linux@weissschuh.net>
 */
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/acpi.h>
#include <linux/hwmon.h>
#include <linux/module.h>
#include <linux/wmi.h>

#define GIGABYTE_WMI_GUID       "DEADBEEF-2001-0000-00A0-C90629100000"
#define NUM_TEMPERATURE_SENSORS 6

static u8 usable_sensors_mask;

enum gigabyte_wmi_commandtype {
        GIGABYTE_WMI_BUILD_DATE_QUERY       =   0x1,
        GIGABYTE_WMI_MAINBOARD_TYPE_QUERY   =   0x2,
        GIGABYTE_WMI_FIRMWARE_VERSION_QUERY =   0x4,
        GIGABYTE_WMI_MAINBOARD_NAME_QUERY   =   0x5,
        GIGABYTE_WMI_TEMPERATURE_QUERY      = 0x125,
};

struct gigabyte_wmi_args {
        u32 arg1;
};

static int gigabyte_wmi_perform_query(struct wmi_device *wdev,
                                      enum gigabyte_wmi_commandtype command,
                                      struct gigabyte_wmi_args *args, struct acpi_buffer *out)
{
        const struct acpi_buffer in = {
                .length = sizeof(*args),
                .pointer = args,
        };

        acpi_status ret = wmidev_evaluate_method(wdev, 0x0, command, &in, out);

        if (ACPI_FAILURE(ret))
                return -EIO;

        return 0;
}

static int gigabyte_wmi_query_integer(struct wmi_device *wdev,
                                      enum gigabyte_wmi_commandtype command,
                                      struct gigabyte_wmi_args *args, u64 *res)
{
        union acpi_object *obj;
        struct acpi_buffer result = { ACPI_ALLOCATE_BUFFER, NULL };
        int ret;

        ret = gigabyte_wmi_perform_query(wdev, command, args, &result);
        if (ret)
                return ret;
        obj = result.pointer;
        if (obj && obj->type == ACPI_TYPE_INTEGER)
                *res = obj->integer.value;
        else
                ret = -EIO;
        kfree(result.pointer);
        return ret;
}

static int gigabyte_wmi_temperature(struct wmi_device *wdev, u8 sensor, long *res)
{
        struct gigabyte_wmi_args args = {
                .arg1 = sensor,
        };
        u64 temp;
        acpi_status ret;

        ret = gigabyte_wmi_query_integer(wdev, GIGABYTE_WMI_TEMPERATURE_QUERY, &args, &temp);
        if (ret == 0) {
                if (temp == 0)
                        return -ENODEV;
                *res = (s8)temp * 1000; // value is a signed 8-bit integer
        }
        return ret;
}

static int gigabyte_wmi_hwmon_read(struct device *dev, enum hwmon_sensor_types type,
                                   u32 attr, int channel, long *val)
{
        struct wmi_device *wdev = dev_get_drvdata(dev);

        return gigabyte_wmi_temperature(wdev, channel, val);
}

static umode_t gigabyte_wmi_hwmon_is_visible(const void *data, enum hwmon_sensor_types type,
                                             u32 attr, int channel)
{
        return usable_sensors_mask & BIT(channel) ? 0444  : 0;
}

static const struct hwmon_channel_info * const gigabyte_wmi_hwmon_info[] = {
        HWMON_CHANNEL_INFO(temp,
                           HWMON_T_INPUT,
                           HWMON_T_INPUT,
                           HWMON_T_INPUT,
                           HWMON_T_INPUT,
                           HWMON_T_INPUT,
                           HWMON_T_INPUT),
        NULL
};

static const struct hwmon_ops gigabyte_wmi_hwmon_ops = {
        .read = gigabyte_wmi_hwmon_read,
        .is_visible = gigabyte_wmi_hwmon_is_visible,
};

static const struct hwmon_chip_info gigabyte_wmi_hwmon_chip_info = {
        .ops = &gigabyte_wmi_hwmon_ops,
        .info = gigabyte_wmi_hwmon_info,
};

static u8 gigabyte_wmi_detect_sensor_usability(struct wmi_device *wdev)
{
        int i;
        long temp;
        u8 r = 0;

        for (i = 0; i < NUM_TEMPERATURE_SENSORS; i++) {
                if (!gigabyte_wmi_temperature(wdev, i, &temp))
                        r |= BIT(i);
        }
        return r;
}

static int gigabyte_wmi_probe(struct wmi_device *wdev, const void *context)
{
        struct device *hwmon_dev;

        usable_sensors_mask = gigabyte_wmi_detect_sensor_usability(wdev);
        if (!usable_sensors_mask) {
                dev_info(&wdev->dev, "No temperature sensors usable");
                return -ENODEV;
        }

        hwmon_dev = devm_hwmon_device_register_with_info(&wdev->dev, "gigabyte_wmi", wdev,
                                                         &gigabyte_wmi_hwmon_chip_info, NULL);

        return PTR_ERR_OR_ZERO(hwmon_dev);
}

static const struct wmi_device_id gigabyte_wmi_id_table[] = {
        { GIGABYTE_WMI_GUID, NULL },
        { }
};

static struct wmi_driver gigabyte_wmi_driver = {
        .driver = {
                .name = "gigabyte-wmi",
        },
        .id_table = gigabyte_wmi_id_table,
        .probe = gigabyte_wmi_probe,
};
module_wmi_driver(gigabyte_wmi_driver);

MODULE_DEVICE_TABLE(wmi, gigabyte_wmi_id_table);
MODULE_AUTHOR("Thomas Weißschuh <linux@weissschuh.net>");
MODULE_DESCRIPTION("Gigabyte WMI temperature driver");
MODULE_LICENSE("GPL");