// SPDX-License-Identifier: GPL-2.0-only
/*
 * drivers/macintosh/mac_hid.c
 *
 * HID support stuff for Macintosh computers.
 *
 * Copyright (C) 2000 Franz Sirl.
 *
 * This file will soon be removed in favor of an uinput userspace tool.
 */

#include <linux/init.h>
#include <linux/proc_fs.h>
#include <linux/sysctl.h>
#include <linux/input.h>
#include <linux/module.h>
#include <linux/slab.h>

MODULE_DESCRIPTION("Mouse button 2+3 emulation");
MODULE_LICENSE("GPL");

static int mouse_emulate_buttons;
static int mouse_button2_keycode = KEY_RIGHTCTRL;       /* right control key */
static int mouse_button3_keycode = KEY_RIGHTALT;        /* right option key */

static struct input_dev *mac_hid_emumouse_dev;

static DEFINE_MUTEX(mac_hid_emumouse_mutex);

static int mac_hid_create_emumouse(void)
{
        static struct lock_class_key mac_hid_emumouse_dev_event_class;
        static struct lock_class_key mac_hid_emumouse_dev_mutex_class;
        int err;

        mac_hid_emumouse_dev = input_allocate_device();
        if (!mac_hid_emumouse_dev)
                return -ENOMEM;

        lockdep_set_class(&mac_hid_emumouse_dev->event_lock,
                          &mac_hid_emumouse_dev_event_class);
        lockdep_set_class(&mac_hid_emumouse_dev->mutex,
                          &mac_hid_emumouse_dev_mutex_class);

        mac_hid_emumouse_dev->name = "Macintosh mouse button emulation";
        mac_hid_emumouse_dev->id.bustype = BUS_ADB;
        mac_hid_emumouse_dev->id.vendor = 0x0001;
        mac_hid_emumouse_dev->id.product = 0x0001;
        mac_hid_emumouse_dev->id.version = 0x0100;

        mac_hid_emumouse_dev->evbit[0] = BIT_MASK(EV_KEY) | BIT_MASK(EV_REL);
        mac_hid_emumouse_dev->keybit[BIT_WORD(BTN_MOUSE)] =
                BIT_MASK(BTN_LEFT) | BIT_MASK(BTN_MIDDLE) | BIT_MASK(BTN_RIGHT);
        mac_hid_emumouse_dev->relbit[0] = BIT_MASK(REL_X) | BIT_MASK(REL_Y);

        err = input_register_device(mac_hid_emumouse_dev);
        if (err) {
                input_free_device(mac_hid_emumouse_dev);
                mac_hid_emumouse_dev = NULL;
                return err;
        }

        return 0;
}

static void mac_hid_destroy_emumouse(void)
{
        input_unregister_device(mac_hid_emumouse_dev);
        mac_hid_emumouse_dev = NULL;
}

static bool mac_hid_emumouse_filter(struct input_handle *handle,
                                    unsigned int type, unsigned int code,
                                    int value)
{
        unsigned int btn;

        if (type != EV_KEY)
                return false;

        if (code == mouse_button2_keycode)
                btn = BTN_MIDDLE;
        else if (code == mouse_button3_keycode)
                btn = BTN_RIGHT;
        else
                return false;

        input_report_key(mac_hid_emumouse_dev, btn, value);
        input_sync(mac_hid_emumouse_dev);

        return true;
}

static int mac_hid_emumouse_connect(struct input_handler *handler,
                                    struct input_dev *dev,
                                    const struct input_device_id *id)
{
        struct input_handle *handle;
        int error;

        /* Don't bind to ourselves */
        if (dev == mac_hid_emumouse_dev)
                return -ENODEV;

        handle = kzalloc_obj(struct input_handle);
        if (!handle)
                return -ENOMEM;

        handle->dev = dev;
        handle->handler = handler;
        handle->name = "mac-button-emul";

        error = input_register_handle(handle);
        if (error) {
                printk(KERN_ERR
                        "mac_hid: Failed to register button emulation handle, "
                        "error %d\n", error);
                goto err_free;
        }

        error = input_open_device(handle);
        if (error) {
                printk(KERN_ERR
                        "mac_hid: Failed to open input device, error %d\n",
                        error);
                goto err_unregister;
        }

        return 0;

 err_unregister:
        input_unregister_handle(handle);
 err_free:
        kfree(handle);
        return error;
}

static void mac_hid_emumouse_disconnect(struct input_handle *handle)
{
        input_close_device(handle);
        input_unregister_handle(handle);
        kfree(handle);
}

static const struct input_device_id mac_hid_emumouse_ids[] = {
        {
                .flags = INPUT_DEVICE_ID_MATCH_EVBIT,
                .evbit = { BIT_MASK(EV_KEY) },
        },
        { },
};

MODULE_DEVICE_TABLE(input, mac_hid_emumouse_ids);

static struct input_handler mac_hid_emumouse_handler = {
        .filter         = mac_hid_emumouse_filter,
        .connect        = mac_hid_emumouse_connect,
        .disconnect     = mac_hid_emumouse_disconnect,
        .name           = "mac-button-emul",
        .id_table       = mac_hid_emumouse_ids,
};

static int mac_hid_start_emulation(void)
{
        int err;

        err = mac_hid_create_emumouse();
        if (err)
                return err;

        err = input_register_handler(&mac_hid_emumouse_handler);
        if (err) {
                mac_hid_destroy_emumouse();
                return err;
        }

        return 0;
}

static void mac_hid_stop_emulation(void)
{
        input_unregister_handler(&mac_hid_emumouse_handler);
        mac_hid_destroy_emumouse();
}

static int mac_hid_toggle_emumouse(const struct ctl_table *table, int write,
                                   void *buffer, size_t *lenp, loff_t *ppos)
{
        int *valp = table->data;
        int old_val;
        int rc;

        rc = mutex_lock_killable(&mac_hid_emumouse_mutex);
        if (rc)
                return rc;

        old_val = *valp;
        rc = proc_dointvec(table, write, buffer, lenp, ppos);

        if (rc == 0 && write && *valp != old_val) {
                if (*valp == 1)
                        rc = mac_hid_start_emulation();
                else if (*valp == 0)
                        mac_hid_stop_emulation();
                else
                        rc = -EINVAL;
        }

        /* Restore the old value in case of error */
        if (rc)
                *valp = old_val;

        mutex_unlock(&mac_hid_emumouse_mutex);

        return rc;
}

/* file(s) in /proc/sys/dev/mac_hid */
static const struct ctl_table mac_hid_files[] = {
        {
                .procname       = "mouse_button_emulation",
                .data           = &mouse_emulate_buttons,
                .maxlen         = sizeof(int),
                .mode           = 0644,
                .proc_handler   = mac_hid_toggle_emumouse,
        },
        {
                .procname       = "mouse_button2_keycode",
                .data           = &mouse_button2_keycode,
                .maxlen         = sizeof(int),
                .mode           = 0644,
                .proc_handler   = proc_dointvec,
        },
        {
                .procname       = "mouse_button3_keycode",
                .data           = &mouse_button3_keycode,
                .maxlen         = sizeof(int),
                .mode           = 0644,
                .proc_handler   = proc_dointvec,
        },
};

static struct ctl_table_header *mac_hid_sysctl_header;

static int __init mac_hid_init(void)
{
        mac_hid_sysctl_header = register_sysctl("dev/mac_hid", mac_hid_files);
        if (!mac_hid_sysctl_header)
                return -ENOMEM;

        return 0;
}
module_init(mac_hid_init);

static void __exit mac_hid_exit(void)
{
        unregister_sysctl_table(mac_hid_sysctl_header);

        if (mouse_emulate_buttons)
                mac_hid_stop_emulation();
}
module_exit(mac_hid_exit);