text: // SPDX-License-Identifier: GPL-2.0-or-later
  /*
   *  Airplane mode button for HP & Xiaomi laptops
   *
   *  Copyright (C) 2014-2017 Alex Hung <alex.hung@canonical.com>
   */
  
  #include <linux/kernel.h>
  #include <linux/module.h>
  #include <linux/init.h>
  #include <linux/input.h>
  #include <linux/platform_device.h>
  #include <linux/acpi.h>
  #include <acpi/acpi_bus.h>
  
  MODULE_LICENSE("GPL");
  MODULE_AUTHOR("Alex Hung");
  MODULE_ALIAS("acpi*:HPQ6001:*");
  MODULE_ALIAS("acpi*:WSTADEF:*");
  
  static struct input_dev *hpwl_input_dev;
  
  static const struct acpi_device_id hpwl_ids[] = {
  	{"HPQ6001", 0},
  	{"WSTADEF", 0},
  	{"", 0},
  };
  
  static int hp_wireless_input_setup(void)
  {
  	int err;
  
  	hpwl_input_dev = input_allocate_device();
  	if (!hpwl_input_dev)
  		return -ENOMEM;
  
  	hpwl_input_dev->name = "HP Wireless hotkeys";
  	hpwl_input_dev->phys = "hpq6001/input0";
  	hpwl_input_dev->id.bustype = BUS_HOST;
  	hpwl_input_dev->evbit[0] = BIT(EV_KEY);
  	set_bit(KEY_RFKILL, hpwl_input_dev->keybit);
  
  	err = input_register_device(hpwl_input_dev);
  	if (err)
  		goto err_free_dev;
  
  	return 0;
  
  err_free_dev:
  	input_free_device(hpwl_input_dev);
  	return err;
  }
  
  static void hp_wireless_input_destroy(void)
  {
  	input_unregister_device(hpwl_input_dev);
  }
  
  static void hpwl_notify(struct acpi_device *acpi_dev, u32 event)
  {
  	if (event != 0x80) {
  		pr_info("Received unknown event (0x%x)\n", event);
  		return;
  	}
  
  	input_report_key(hpwl_input_dev, KEY_RFKILL, 1);
  	input_sync(hpwl_input_dev);
  	input_report_key(hpwl_input_dev, KEY_RFKILL, 0);
  	input_sync(hpwl_input_dev);
  }
  
  static int hpwl_add(struct acpi_device *device)
  {
  	int err;
  
  	err = hp_wireless_input_setup();
  	if (err)
  		pr_err("Failed to setup hp wireless hotkeys\n");
  
  	return err;
  }
  
  static int hpwl_remove(struct acpi_device *device)
  {
  	hp_wireless_input_destroy();
  	return 0;
  }
  
  static struct acpi_driver hpwl_driver = {
  	.name	= "hp-wireless",
  	.owner	= THIS_MODULE,
  	.ids	= hpwl_ids,
  	.ops	= {
  		.add	= hpwl_add,
  		.remove	= hpwl_remove,
  		.notify	= hpwl_notify,
  	},
  };
  
  module_acpi_driver(hpwl_driver);
  