// SPDX-License-Identifier: GPL-2.0
/*
 * Lenovo WMI Camera Button Driver
 *
 * Author: Ai Chao <aichao@kylinos.cn>
 * Copyright (C) 2024 KylinSoft Corporation.
 */

#include <linux/acpi.h>
#include <linux/device.h>
#include <linux/input.h>
#include <linux/types.h>
#include <linux/module.h>
#include <linux/mutex.h>
#include <linux/wmi.h>
#include <linux/cleanup.h>

#define WMI_LENOVO_CAMERABUTTON_EVENT_GUID "50C76F1F-D8E4-D895-0A3D-62F4EA400013"

struct lenovo_wmi_priv {
        struct input_dev *idev;
        struct mutex notify_lock;       /* lenovo WMI camera button notify lock */
};

enum {
        SW_CAMERA_OFF   = 0,
        SW_CAMERA_ON    = 1,
};

static int camera_shutter_input_setup(struct wmi_device *wdev, u8 camera_mode)
{
        struct lenovo_wmi_priv *priv = dev_get_drvdata(&wdev->dev);
        int err;

        priv->idev = input_allocate_device();
        if (!priv->idev)
                return -ENOMEM;

        priv->idev->name = "Lenovo WMI Camera Button";
        priv->idev->phys = "wmi/input0";
        priv->idev->id.bustype = BUS_HOST;
        priv->idev->dev.parent = &wdev->dev;

        input_set_capability(priv->idev, EV_SW, SW_CAMERA_LENS_COVER);

        input_report_switch(priv->idev, SW_CAMERA_LENS_COVER,
                            camera_mode == SW_CAMERA_ON ? 0 : 1);
        input_sync(priv->idev);

        err = input_register_device(priv->idev);
        if (err) {
                input_free_device(priv->idev);
                priv->idev = NULL;
        }

        return err;
}

static void lenovo_wmi_notify(struct wmi_device *wdev, union acpi_object *obj)
{
        struct lenovo_wmi_priv *priv = dev_get_drvdata(&wdev->dev);
        u8 camera_mode;

        if (obj->type != ACPI_TYPE_BUFFER) {
                dev_err(&wdev->dev, "Bad response type %u\n", obj->type);
                return;
        }

        if (obj->buffer.length != 1) {
                dev_err(&wdev->dev, "Invalid buffer length %u\n", obj->buffer.length);
                return;
        }

        /*
         * obj->buffer.pointer[0] is camera mode:
         *      0 camera close
         *      1 camera open
         */
        camera_mode = obj->buffer.pointer[0];
        if (camera_mode > SW_CAMERA_ON) {
                dev_err(&wdev->dev, "Unknown camera mode %u\n", camera_mode);
                return;
        }

        guard(mutex)(&priv->notify_lock);

        if (!priv->idev) {
                if (camera_shutter_input_setup(wdev, camera_mode))
                        dev_warn(&wdev->dev, "Failed to register input device\n");
                return;
        }

        if (camera_mode == SW_CAMERA_ON)
                input_report_switch(priv->idev, SW_CAMERA_LENS_COVER, 0);
        else
                input_report_switch(priv->idev, SW_CAMERA_LENS_COVER, 1);
        input_sync(priv->idev);
}

static int lenovo_wmi_probe(struct wmi_device *wdev, const void *context)
{
        struct lenovo_wmi_priv *priv;

        priv = devm_kzalloc(&wdev->dev, sizeof(*priv), GFP_KERNEL);
        if (!priv)
                return -ENOMEM;

        dev_set_drvdata(&wdev->dev, priv);

        mutex_init(&priv->notify_lock);

        return 0;
}

static void lenovo_wmi_remove(struct wmi_device *wdev)
{
        struct lenovo_wmi_priv *priv = dev_get_drvdata(&wdev->dev);

        if (priv->idev)
                input_unregister_device(priv->idev);

        mutex_destroy(&priv->notify_lock);
}

static const struct wmi_device_id lenovo_wmi_id_table[] = {
        { .guid_string = WMI_LENOVO_CAMERABUTTON_EVENT_GUID },
        {  }
};
MODULE_DEVICE_TABLE(wmi, lenovo_wmi_id_table);

static struct wmi_driver lenovo_wmi_driver = {
        .driver = {
                .name = "lenovo-wmi-camera",
                .probe_type = PROBE_PREFER_ASYNCHRONOUS,
        },
        .id_table = lenovo_wmi_id_table,
        .no_singleton = true,
        .probe = lenovo_wmi_probe,
        .notify = lenovo_wmi_notify,
        .remove = lenovo_wmi_remove,
};
module_wmi_driver(lenovo_wmi_driver);

MODULE_AUTHOR("Ai Chao <aichao@kylinos.cn>");
MODULE_DESCRIPTION("Lenovo WMI Camera Button Driver");
MODULE_LICENSE("GPL");