drivers/platform/x86/dell-rbtn.c - kernel/common - Git at Google

 // SPDX-License-Identifier: GPL-2.0-or-later
 /*
     Dell Airplane Mode Switch driver
     Copyright (C) 2014-2015  Pali Rohár <[email protected]>

 */

 #include <linux/module.h>
 #include <linux/acpi.h>
 #include <linux/rfkill.h>
 #include <linux/input.h>

 #include "dell-rbtn.h"

 enum rbtn_type {
 	RBTN_UNKNOWN,
 	RBTN_TOGGLE,
 	RBTN_SLIDER,
 };

 struct rbtn_data {
 	enum rbtn_type type;
 	struct rfkill *rfkill;
 	struct input_dev *input_dev;
 	bool suspended;
 };


 /*
  * acpi functions
  */

 static enum rbtn_type rbtn_check(struct acpi_device *device)
 {
 	unsigned long long output;
 	acpi_status status;

 	status = acpi_evaluate_integer(device->handle, "CRBT", NULL, &output);
 	if (ACPI_FAILURE(status))
 		return RBTN_UNKNOWN;

 	switch (output) {
 	case 0:
 	case 1:
 		return RBTN_TOGGLE;
 	case 2:
 	case 3:
 		return RBTN_SLIDER;
 	default:
 		return RBTN_UNKNOWN;
 	}
 }

 static int rbtn_get(struct acpi_device *device)
 {
 	unsigned long long output;
 	acpi_status status;

 	status = acpi_evaluate_integer(device->handle, "GRBT", NULL, &output);
 	if (ACPI_FAILURE(status))
 		return -EINVAL;

 	return !output;
 }

 static int rbtn_acquire(struct acpi_device *device, bool enable)
 {
 	struct acpi_object_list input;
 	union acpi_object param;
 	acpi_status status;

 	param.type = ACPI_TYPE_INTEGER;
 	param.integer.value = enable;
 	input.count = 1;
 	input.pointer = &param;

 	status = acpi_evaluate_object(device->handle, "ARBT", &input, NULL);
 	if (ACPI_FAILURE(status))
 		return -EINVAL;

 	return 0;
 }


 /*
  * rfkill device
  */

 static void rbtn_rfkill_query(struct rfkill *rfkill, void *data)
 {
 	struct acpi_device *device = data;
 	int state;

 	state = rbtn_get(device);
 	if (state < 0)
 		return;

 	rfkill_set_states(rfkill, state, state);
 }

 static int rbtn_rfkill_set_block(void *data, bool blocked)
 {
 	/* NOTE: setting soft rfkill state is not supported */
 	return -EINVAL;
 }

 static const struct rfkill_ops rbtn_ops = {
 	.query = rbtn_rfkill_query,
 	.set_block = rbtn_rfkill_set_block,
 };

 static int rbtn_rfkill_init(struct acpi_device *device)
 {
 	struct rbtn_data *rbtn_data = device->driver_data;
 	int ret;

 	if (rbtn_data->rfkill)
 		return 0;

 	/*
 	 * NOTE: rbtn controls all radio devices, not only WLAN
 	 *       but rfkill interface does not support "ANY" type
 	 *       so "WLAN" type is used
 	 */
 	rbtn_data->rfkill = rfkill_alloc("dell-rbtn", &device->dev,
 					 RFKILL_TYPE_WLAN, &rbtn_ops, device);
 	if (!rbtn_data->rfkill)
 		return -ENOMEM;

 	ret = rfkill_register(rbtn_data->rfkill);
 	if (ret) {
 		rfkill_destroy(rbtn_data->rfkill);
 		rbtn_data->rfkill = NULL;
 		return ret;
 	}

 	return 0;
 }

 static void rbtn_rfkill_exit(struct acpi_device *device)
 {
 	struct rbtn_data *rbtn_data = device->driver_data;

 	if (!rbtn_data->rfkill)
 		return;

 	rfkill_unregister(rbtn_data->rfkill);
 	rfkill_destroy(rbtn_data->rfkill);
 	rbtn_data->rfkill = NULL;
 }

 static void rbtn_rfkill_event(struct acpi_device *device)
 {
 	struct rbtn_data *rbtn_data = device->driver_data;

 	if (rbtn_data->rfkill)
 		rbtn_rfkill_query(rbtn_data->rfkill, device);
 }


 /*
  * input device
  */

 static int rbtn_input_init(struct rbtn_data *rbtn_data)
 {
 	int ret;

 	rbtn_data->input_dev = input_allocate_device();
 	if (!rbtn_data->input_dev)
 		return -ENOMEM;

 	rbtn_data->input_dev->name = "DELL Wireless hotkeys";
 	rbtn_data->input_dev->phys = "dellabce/input0";
 	rbtn_data->input_dev->id.bustype = BUS_HOST;
 	rbtn_data->input_dev->evbit[0] = BIT(EV_KEY);
 	set_bit(KEY_RFKILL, rbtn_data->input_dev->keybit);

 	ret = input_register_device(rbtn_data->input_dev);
 	if (ret) {
 		input_free_device(rbtn_data->input_dev);
 		rbtn_data->input_dev = NULL;
 		return ret;
 	}

 	return 0;
 }

 static void rbtn_input_exit(struct rbtn_data *rbtn_data)
 {
 	input_unregister_device(rbtn_data->input_dev);
 	rbtn_data->input_dev = NULL;
 }

 static void rbtn_input_event(struct rbtn_data *rbtn_data)
 {
 	input_report_key(rbtn_data->input_dev, KEY_RFKILL, 1);
 	input_sync(rbtn_data->input_dev);
 	input_report_key(rbtn_data->input_dev, KEY_RFKILL, 0);
 	input_sync(rbtn_data->input_dev);
 }


 /*
  * acpi driver
  */

 static int rbtn_add(struct acpi_device *device);
 static int rbtn_remove(struct acpi_device *device);
 static void rbtn_notify(struct acpi_device *device, u32 event);

 static const struct acpi_device_id rbtn_ids[] = {
 	{ "DELRBTN", 0 },
 	{ "DELLABCE", 0 },

 	/*
 	 * This driver can also handle the "DELLABC6" device that
 	 * appears on the XPS 13 9350, but that device is disabled by
 	 * the DSDT unless booted with acpi_osi="!Windows 2012"
 	 * acpi_osi="!Windows 2013".
 	 *
 	 * According to Mario at Dell:
 	 *
 	 *  DELLABC6 is a custom interface that was created solely to
 	 *  have airplane mode support for Windows 7.  For Windows 10
 	 *  the proper interface is to use that which is handled by
 	 *  intel-hid. A OEM airplane mode driver is not used.
 	 *
 	 *  Since the kernel doesn't identify as Windows 7 it would be
 	 *  incorrect to do attempt to use that interface.
 	 *
 	 * Even if we override _OSI and bind to DELLABC6, we end up with
 	 * inconsistent behavior in which userspace can get out of sync
 	 * with the rfkill state as it conflicts with events from
 	 * intel-hid.
 	 *
 	 * The upshot is that it is better to just ignore DELLABC6
 	 * devices.
 	 */

 	{ "", 0 },
 };

 #ifdef CONFIG_PM_SLEEP
 static void ACPI_SYSTEM_XFACE rbtn_clear_suspended_flag(void *context)
 {
 	struct rbtn_data *rbtn_data = context;

 	rbtn_data->suspended = false;
 }

 static int rbtn_suspend(struct device *dev)
 {
 	struct acpi_device *device = to_acpi_device(dev);
 	struct rbtn_data *rbtn_data = acpi_driver_data(device);

 	rbtn_data->suspended = true;

 	return 0;
 }

 static int rbtn_resume(struct device *dev)
 {
 	struct acpi_device *device = to_acpi_device(dev);
 	struct rbtn_data *rbtn_data = acpi_driver_data(device);
 	acpi_status status;

 	/*
 	 * Upon resume, some BIOSes send an ACPI notification thet triggers
 	 * an unwanted input event. In order to ignore it, we use a flag
 	 * that we set at suspend and clear once we have received the extra
 	 * ACPI notification. Since ACPI notifications are delivered
 	 * asynchronously to drivers, we clear the flag from the workqueue
 	 * used to deliver the notifications. This should be enough
 	 * to have the flag cleared only after we received the extra
 	 * notification, if any.
 	 */
 	status = acpi_os_execute(OSL_NOTIFY_HANDLER,
 			 rbtn_clear_suspended_flag, rbtn_data);
 	if (ACPI_FAILURE(status))
 		rbtn_clear_suspended_flag(rbtn_data);

 	return 0;
 }
 #endif

 static SIMPLE_DEV_PM_OPS(rbtn_pm_ops, rbtn_suspend, rbtn_resume);

 static struct acpi_driver rbtn_driver = {
 	.name = "dell-rbtn",
 	.ids = rbtn_ids,
 	.drv.pm = &rbtn_pm_ops,
 	.ops = {
 		.add = rbtn_add,
 		.remove = rbtn_remove,
 		.notify = rbtn_notify,
 	},
 	.owner = THIS_MODULE,
 };


 /*
  * notifier export functions
  */

 static bool auto_remove_rfkill = true;

 static ATOMIC_NOTIFIER_HEAD(rbtn_chain_head);

 static int rbtn_inc_count(struct device *dev, void *data)
 {
 	struct acpi_device *device = to_acpi_device(dev);
 	struct rbtn_data *rbtn_data = device->driver_data;
 	int *count = data;

 	if (rbtn_data->type == RBTN_SLIDER)
 		(*count)++;

 	return 0;
 }

 static int rbtn_switch_dev(struct device *dev, void *data)
 {
 	struct acpi_device *device = to_acpi_device(dev);
 	struct rbtn_data *rbtn_data = device->driver_data;
 	bool enable = data;

 	if (rbtn_data->type != RBTN_SLIDER)
 		return 0;

 	if (enable)
 		rbtn_rfkill_init(device);
 	else
 		rbtn_rfkill_exit(device);

 	return 0;
 }

 int dell_rbtn_notifier_register(struct notifier_block *nb)
 {
 	bool first;
 	int count;
 	int ret;

 	count = 0;
 	ret = driver_for_each_device(&rbtn_driver.drv, NULL, &count,
 				     rbtn_inc_count);
 	if (ret || count == 0)
 		return -ENODEV;

 	first = !rbtn_chain_head.head;

 	ret = atomic_notifier_chain_register(&rbtn_chain_head, nb);
 	if (ret != 0)
 		return ret;

 	if (auto_remove_rfkill && first)
 		ret = driver_for_each_device(&rbtn_driver.drv, NULL,
 					     (void *)false, rbtn_switch_dev);

 	return ret;
 }
 EXPORT_SYMBOL_GPL(dell_rbtn_notifier_register);

 int dell_rbtn_notifier_unregister(struct notifier_block *nb)
 {
 	int ret;

 	ret = atomic_notifier_chain_unregister(&rbtn_chain_head, nb);
 	if (ret != 0)
 		return ret;

 	if (auto_remove_rfkill && !rbtn_chain_head.head)
 		ret = driver_for_each_device(&rbtn_driver.drv, NULL,
 					     (void *)true, rbtn_switch_dev);

 	return ret;
 }
 EXPORT_SYMBOL_GPL(dell_rbtn_notifier_unregister);


 /*
  * acpi driver functions
  */

 static int rbtn_add(struct acpi_device *device)
 {
 	struct rbtn_data *rbtn_data;
 	enum rbtn_type type;
 	int ret = 0;

 	type = rbtn_check(device);
 	if (type == RBTN_UNKNOWN) {
 		dev_info(&device->dev, "Unknown device type\n");
 		return -EINVAL;
 	}

 	ret = rbtn_acquire(device, true);
 	if (ret < 0) {
 		dev_err(&device->dev, "Cannot enable device\n");
 		return ret;
 	}

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

 	rbtn_data->type = type;
 	device->driver_data = rbtn_data;

 	switch (rbtn_data->type) {
 	case RBTN_TOGGLE:
 		ret = rbtn_input_init(rbtn_data);
 		break;
 	case RBTN_SLIDER:
 		if (auto_remove_rfkill && rbtn_chain_head.head)
 			ret = 0;
 		else
 			ret = rbtn_rfkill_init(device);
 		break;
 	default:
 		ret = -EINVAL;
 	}

 	return ret;

 }

 static int rbtn_remove(struct acpi_device *device)
 {
 	struct rbtn_data *rbtn_data = device->driver_data;

 	switch (rbtn_data->type) {
 	case RBTN_TOGGLE:
 		rbtn_input_exit(rbtn_data);
 		break;
 	case RBTN_SLIDER:
 		rbtn_rfkill_exit(device);
 		break;
 	default:
 		break;
 	}

 	rbtn_acquire(device, false);
 	device->driver_data = NULL;

 	return 0;
 }

 static void rbtn_notify(struct acpi_device *device, u32 event)
 {
 	struct rbtn_data *rbtn_data = device->driver_data;

 	/*
 	 * Some BIOSes send a notification at resume.
 	 * Ignore it to prevent unwanted input events.
 	 */
 	if (rbtn_data->suspended) {
 		dev_dbg(&device->dev, "ACPI notification ignored\n");
 		return;
 	}

 	if (event != 0x80) {
 		dev_info(&device->dev, "Received unknown event (0x%x)\n",
 			 event);
 		return;
 	}

 	switch (rbtn_data->type) {
 	case RBTN_TOGGLE:
 		rbtn_input_event(rbtn_data);
 		break;
 	case RBTN_SLIDER:
 		rbtn_rfkill_event(device);
 		atomic_notifier_call_chain(&rbtn_chain_head, event, device);
 		break;
 	default:
 		break;
 	}
 }


 /*
  * module functions
  */

 module_acpi_driver(rbtn_driver);

 module_param(auto_remove_rfkill, bool, 0444);

 MODULE_PARM_DESC(auto_remove_rfkill, "Automatically remove rfkill devices when "
 				     "other modules start receiving events "
 				     "from this module and re-add them when "
 				     "the last module stops receiving events "
 				     "(default true)");
 MODULE_DEVICE_TABLE(acpi, rbtn_ids);
 MODULE_DESCRIPTION("Dell Airplane Mode Switch driver");
 MODULE_AUTHOR("Pali Rohár <[email protected]>");
 MODULE_LICENSE("GPL");
	// SPDX-License-Identifier: GPL-2.0-or-later
	/*
	Dell Airplane Mode Switch driver
	Copyright (C) 2014-2015 Pali Rohár <[email protected]>

	*/

	#include <linux/module.h>
	#include <linux/acpi.h>
	#include <linux/rfkill.h>
	#include <linux/input.h>

	#include "dell-rbtn.h"

	enum rbtn_type {
	RBTN_UNKNOWN,
	RBTN_TOGGLE,
	RBTN_SLIDER,
	};

	struct rbtn_data {
	enum rbtn_type type;
	struct rfkill *rfkill;
	struct input_dev *input_dev;
	bool suspended;
	};


	/*
	* acpi functions
	*/

	static enum rbtn_type rbtn_check(struct acpi_device *device)
	{
	unsigned long long output;
	acpi_status status;

	status = acpi_evaluate_integer(device->handle, "CRBT", NULL, &output);
	if (ACPI_FAILURE(status))
	return RBTN_UNKNOWN;

	switch (output) {
	case 0:
	case 1:
	return RBTN_TOGGLE;
	case 2:
	case 3:
	return RBTN_SLIDER;
	default:
	return RBTN_UNKNOWN;
	}
	}

	static int rbtn_get(struct acpi_device *device)
	{
	unsigned long long output;
	acpi_status status;

	status = acpi_evaluate_integer(device->handle, "GRBT", NULL, &output);
	if (ACPI_FAILURE(status))
	return -EINVAL;

	return !output;
	}

	static int rbtn_acquire(struct acpi_device *device, bool enable)
	{
	struct acpi_object_list input;
	union acpi_object param;
	acpi_status status;

	param.type = ACPI_TYPE_INTEGER;
	param.integer.value = enable;
	input.count = 1;
	input.pointer = &param;

	status = acpi_evaluate_object(device->handle, "ARBT", &input, NULL);
	if (ACPI_FAILURE(status))
	return -EINVAL;

	return 0;
	}


	/*
	* rfkill device
	*/

	static void rbtn_rfkill_query(struct rfkill rfkill, void data)
	{
	struct acpi_device *device = data;
	int state;

	state = rbtn_get(device);
	if (state < 0)
	return;

	rfkill_set_states(rfkill, state, state);
	}

	static int rbtn_rfkill_set_block(void *data, bool blocked)
	{
	/* NOTE: setting soft rfkill state is not supported */
	return -EINVAL;
	}

	static const struct rfkill_ops rbtn_ops = {
	.query = rbtn_rfkill_query,
	.set_block = rbtn_rfkill_set_block,
	};

	static int rbtn_rfkill_init(struct acpi_device *device)
	{
	struct rbtn_data *rbtn_data = device->driver_data;
	int ret;

	if (rbtn_data->rfkill)
	return 0;

	/*
	* NOTE: rbtn controls all radio devices, not only WLAN
	* but rfkill interface does not support "ANY" type
	* so "WLAN" type is used
	*/
	rbtn_data->rfkill = rfkill_alloc("dell-rbtn", &device->dev,
	RFKILL_TYPE_WLAN, &rbtn_ops, device);
	if (!rbtn_data->rfkill)
	return -ENOMEM;

	ret = rfkill_register(rbtn_data->rfkill);
	if (ret) {
	rfkill_destroy(rbtn_data->rfkill);
	rbtn_data->rfkill = NULL;
	return ret;
	}

	return 0;
	}

	static void rbtn_rfkill_exit(struct acpi_device *device)
	{
	struct rbtn_data *rbtn_data = device->driver_data;

	if (!rbtn_data->rfkill)
	return;

	rfkill_unregister(rbtn_data->rfkill);
	rfkill_destroy(rbtn_data->rfkill);
	rbtn_data->rfkill = NULL;
	}

	static void rbtn_rfkill_event(struct acpi_device *device)
	{
	struct rbtn_data *rbtn_data = device->driver_data;

	if (rbtn_data->rfkill)
	rbtn_rfkill_query(rbtn_data->rfkill, device);
	}


	/*
	* input device
	*/

	static int rbtn_input_init(struct rbtn_data *rbtn_data)
	{
	int ret;

	rbtn_data->input_dev = input_allocate_device();
	if (!rbtn_data->input_dev)
	return -ENOMEM;

	rbtn_data->input_dev->name = "DELL Wireless hotkeys";
	rbtn_data->input_dev->phys = "dellabce/input0";
	rbtn_data->input_dev->id.bustype = BUS_HOST;
	rbtn_data->input_dev->evbit[0] = BIT(EV_KEY);
	set_bit(KEY_RFKILL, rbtn_data->input_dev->keybit);

	ret = input_register_device(rbtn_data->input_dev);
	if (ret) {
	input_free_device(rbtn_data->input_dev);
	rbtn_data->input_dev = NULL;
	return ret;
	}

	return 0;
	}

	static void rbtn_input_exit(struct rbtn_data *rbtn_data)
	{
	input_unregister_device(rbtn_data->input_dev);
	rbtn_data->input_dev = NULL;
	}

	static void rbtn_input_event(struct rbtn_data *rbtn_data)
	{
	input_report_key(rbtn_data->input_dev, KEY_RFKILL, 1);
	input_sync(rbtn_data->input_dev);
	input_report_key(rbtn_data->input_dev, KEY_RFKILL, 0);
	input_sync(rbtn_data->input_dev);
	}


	/*
	* acpi driver
	*/

	static int rbtn_add(struct acpi_device *device);
	static int rbtn_remove(struct acpi_device *device);
	static void rbtn_notify(struct acpi_device *device, u32 event);

	static const struct acpi_device_id rbtn_ids[] = {
	{ "DELRBTN", 0 },
	{ "DELLABCE", 0 },

	/*
	* This driver can also handle the "DELLABC6" device that
	* appears on the XPS 13 9350, but that device is disabled by
	* the DSDT unless booted with acpi_osi="!Windows 2012"
	* acpi_osi="!Windows 2013".
	*
	* According to Mario at Dell:
	*
	* DELLABC6 is a custom interface that was created solely to
	* have airplane mode support for Windows 7. For Windows 10
	* the proper interface is to use that which is handled by
	* intel-hid. A OEM airplane mode driver is not used.
	*
	* Since the kernel doesn't identify as Windows 7 it would be
	* incorrect to do attempt to use that interface.
	*
	* Even if we override _OSI and bind to DELLABC6, we end up with
	* inconsistent behavior in which userspace can get out of sync
	* with the rfkill state as it conflicts with events from
	* intel-hid.
	*
	* The upshot is that it is better to just ignore DELLABC6
	* devices.
	*/

	{ "", 0 },
	};

	#ifdef CONFIG_PM_SLEEP
	static void ACPI_SYSTEM_XFACE rbtn_clear_suspended_flag(void *context)
	{
	struct rbtn_data *rbtn_data = context;

	rbtn_data->suspended = false;
	}

	static int rbtn_suspend(struct device *dev)
	{
	struct acpi_device *device = to_acpi_device(dev);
	struct rbtn_data *rbtn_data = acpi_driver_data(device);

	rbtn_data->suspended = true;

	return 0;
	}

	static int rbtn_resume(struct device *dev)
	{
	struct acpi_device *device = to_acpi_device(dev);
	struct rbtn_data *rbtn_data = acpi_driver_data(device);
	acpi_status status;

	/*
	* Upon resume, some BIOSes send an ACPI notification thet triggers
	* an unwanted input event. In order to ignore it, we use a flag
	* that we set at suspend and clear once we have received the extra
	* ACPI notification. Since ACPI notifications are delivered
	* asynchronously to drivers, we clear the flag from the workqueue
	* used to deliver the notifications. This should be enough
	* to have the flag cleared only after we received the extra
	* notification, if any.
	*/
	status = acpi_os_execute(OSL_NOTIFY_HANDLER,
	rbtn_clear_suspended_flag, rbtn_data);
	if (ACPI_FAILURE(status))
	rbtn_clear_suspended_flag(rbtn_data);

	return 0;
	}
	#endif

	static SIMPLE_DEV_PM_OPS(rbtn_pm_ops, rbtn_suspend, rbtn_resume);

	static struct acpi_driver rbtn_driver = {
	.name = "dell-rbtn",
	.ids = rbtn_ids,
	.drv.pm = &rbtn_pm_ops,
	.ops = {
	.add = rbtn_add,
	.remove = rbtn_remove,
	.notify = rbtn_notify,
	},
	.owner = THIS_MODULE,
	};


	/*
	* notifier export functions
	*/

	static bool auto_remove_rfkill = true;

	static ATOMIC_NOTIFIER_HEAD(rbtn_chain_head);

	static int rbtn_inc_count(struct device dev, void data)
	{
	struct acpi_device *device = to_acpi_device(dev);
	struct rbtn_data *rbtn_data = device->driver_data;
	int *count = data;

	if (rbtn_data->type == RBTN_SLIDER)
	(*count)++;

	return 0;
	}

	static int rbtn_switch_dev(struct device dev, void data)
	{
	struct acpi_device *device = to_acpi_device(dev);
	struct rbtn_data *rbtn_data = device->driver_data;
	bool enable = data;

	if (rbtn_data->type != RBTN_SLIDER)
	return 0;

	if (enable)
	rbtn_rfkill_init(device);
	else
	rbtn_rfkill_exit(device);

	return 0;
	}

	int dell_rbtn_notifier_register(struct notifier_block *nb)
	{
	bool first;
	int count;
	int ret;

	count = 0;
	ret = driver_for_each_device(&rbtn_driver.drv, NULL, &count,
	rbtn_inc_count);
	if (ret \|\| count == 0)
	return -ENODEV;

	first = !rbtn_chain_head.head;

	ret = atomic_notifier_chain_register(&rbtn_chain_head, nb);
	if (ret != 0)
	return ret;

	if (auto_remove_rfkill && first)
	ret = driver_for_each_device(&rbtn_driver.drv, NULL,
	(void *)false, rbtn_switch_dev);

	return ret;
	}
	EXPORT_SYMBOL_GPL(dell_rbtn_notifier_register);

	int dell_rbtn_notifier_unregister(struct notifier_block *nb)
	{
	int ret;

	ret = atomic_notifier_chain_unregister(&rbtn_chain_head, nb);
	if (ret != 0)
	return ret;

	if (auto_remove_rfkill && !rbtn_chain_head.head)
	ret = driver_for_each_device(&rbtn_driver.drv, NULL,
	(void *)true, rbtn_switch_dev);

	return ret;
	}
	EXPORT_SYMBOL_GPL(dell_rbtn_notifier_unregister);


	/*
	* acpi driver functions
	*/

	static int rbtn_add(struct acpi_device *device)
	{
	struct rbtn_data *rbtn_data;
	enum rbtn_type type;
	int ret = 0;

	type = rbtn_check(device);
	if (type == RBTN_UNKNOWN) {
	dev_info(&device->dev, "Unknown device type\n");
	return -EINVAL;
	}

	ret = rbtn_acquire(device, true);
	if (ret < 0) {
	dev_err(&device->dev, "Cannot enable device\n");
	return ret;
	}

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

	rbtn_data->type = type;
	device->driver_data = rbtn_data;

	switch (rbtn_data->type) {
	case RBTN_TOGGLE:
	ret = rbtn_input_init(rbtn_data);
	break;
	case RBTN_SLIDER:
	if (auto_remove_rfkill && rbtn_chain_head.head)
	ret = 0;
	else
	ret = rbtn_rfkill_init(device);
	break;
	default:
	ret = -EINVAL;
	}

	return ret;

	}

	static int rbtn_remove(struct acpi_device *device)
	{
	struct rbtn_data *rbtn_data = device->driver_data;

	switch (rbtn_data->type) {
	case RBTN_TOGGLE:
	rbtn_input_exit(rbtn_data);
	break;
	case RBTN_SLIDER:
	rbtn_rfkill_exit(device);
	break;
	default:
	break;
	}

	rbtn_acquire(device, false);
	device->driver_data = NULL;

	return 0;
	}

	static void rbtn_notify(struct acpi_device *device, u32 event)
	{
	struct rbtn_data *rbtn_data = device->driver_data;

	/*
	* Some BIOSes send a notification at resume.
	* Ignore it to prevent unwanted input events.
	*/
	if (rbtn_data->suspended) {
	dev_dbg(&device->dev, "ACPI notification ignored\n");
	return;
	}

	if (event != 0x80) {
	dev_info(&device->dev, "Received unknown event (0x%x)\n",
	event);
	return;
	}

	switch (rbtn_data->type) {
	case RBTN_TOGGLE:
	rbtn_input_event(rbtn_data);
	break;
	case RBTN_SLIDER:
	rbtn_rfkill_event(device);
	atomic_notifier_call_chain(&rbtn_chain_head, event, device);
	break;
	default:
	break;
	}
	}


	/*
	* module functions
	*/

	module_acpi_driver(rbtn_driver);

	module_param(auto_remove_rfkill, bool, 0444);

	MODULE_PARM_DESC(auto_remove_rfkill, "Automatically remove rfkill devices when "
	"other modules start receiving events "
	"from this module and re-add them when "
	"the last module stops receiving events "
	"(default true)");
	MODULE_DEVICE_TABLE(acpi, rbtn_ids);
	MODULE_DESCRIPTION("Dell Airplane Mode Switch driver");
	MODULE_AUTHOR("Pali Rohár <[email protected]>");
	MODULE_LICENSE("GPL");