/*
   *  dock.c - ACPI dock station driver
   *
   *  Copyright (C) 2006 Kristen Carlson Accardi <kristen.c.accardi@intel.com>
   *
   * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
   *
   *  This program is free software; you can redistribute it and/or modify
   *  it under the terms of the GNU General Public License as published by
   *  the Free Software Foundation; either version 2 of the License, or (at
   *  your option) any later version.
   *
   *  This program is distributed in the hope that it will be useful, but
   *  WITHOUT ANY WARRANTY; without even the implied warranty of
   *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   *  General Public License for more details.
   *
   *  You should have received a copy of the GNU General Public License along
   *  with this program; if not, write to the Free Software Foundation, Inc.,
   *  59 Temple Place, Suite 330, Boston, MA 02111-1307 USA.
   *
   * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
   */
  
  #include <linux/kernel.h>
  #include <linux/module.h>

  #include <linux/slab.h>

  #include <linux/init.h>
  #include <linux/types.h>
  #include <linux/notifier.h>

  #include <linux/platform_device.h>

  #include <linux/jiffies.h>

  #include <linux/stddef.h>

  #include <acpi/acpi_bus.h>
  #include <acpi/acpi_drivers.h>

  #define PREFIX "ACPI: "

  #define ACPI_DOCK_DRIVER_DESCRIPTION "ACPI Dock Station Driver"

  ACPI_MODULE_NAME("dock");

  MODULE_AUTHOR("Kristen Carlson Accardi");

  MODULE_DESCRIPTION(ACPI_DOCK_DRIVER_DESCRIPTION);

  MODULE_LICENSE("GPL");

  static bool immediate_undock = 1;

  module_param(immediate_undock, bool, 0644);
  MODULE_PARM_DESC(immediate_undock, "1 (default) will cause the driver to "
  	"undock immediately when the undock button is pressed, 0 will cause"
  	" the driver to wait for userspace to write the undock sysfs file "
  	" before undocking");

  static struct atomic_notifier_head dock_notifier_list;

  static const struct acpi_device_id dock_device_ids[] = {
  	{"LNXDOCK", 0},
  	{"", 0},
  };
  MODULE_DEVICE_TABLE(acpi, dock_device_ids);

  struct dock_station {
  	acpi_handle handle;
  	unsigned long last_dock_time;
  	u32 flags;
  	spinlock_t dd_lock;

  	struct mutex hp_lock;

  	struct list_head dependent_devices;
  	struct list_head hotplug_devices;

  	struct list_head sibling;

  	struct platform_device *dock_device;

  };

  static LIST_HEAD(dock_stations);
  static int dock_station_count;

  
  struct dock_dependent_device {
  	struct list_head list;
  	struct list_head hotplug_list;
  	acpi_handle handle;

  	const struct acpi_dock_ops *ops;

  	void *context;
  };
  
  #define DOCK_DOCKING	0x00000001

  #define DOCK_UNDOCKING  0x00000002

  #define DOCK_IS_DOCK	0x00000010
  #define DOCK_IS_ATA	0x00000020
  #define DOCK_IS_BAT	0x00000040

  #define DOCK_EVENT	3
  #define UNDOCK_EVENT	2

  /*****************************************************************************
   *                         Dock Dependent device functions                   *
   *****************************************************************************/
  /**

   * add_dock_dependent_device - associate a device with the dock station
   * @ds: The dock station
   * @handle: handle of the dependent device

   *

   * Add the dependent device to the dock's dependent device list.

   */

  static int
  add_dock_dependent_device(struct dock_station *ds, acpi_handle handle)

  {
  	struct dock_dependent_device *dd;
  
  	dd = kzalloc(sizeof(*dd), GFP_KERNEL);

  	if (!dd)
  		return -ENOMEM;
  
  	dd->handle = handle;
  	INIT_LIST_HEAD(&dd->list);
  	INIT_LIST_HEAD(&dd->hotplug_list);

  	spin_lock(&ds->dd_lock);
  	list_add_tail(&dd->list, &ds->dependent_devices);
  	spin_unlock(&ds->dd_lock);

  
  	return 0;

  }
  
  /**
   * dock_add_hotplug_device - associate a hotplug handler with the dock station
   * @ds: The dock station
   * @dd: The dependent device struct
   *
   * Add the dependent device to the dock's hotplug device list
   */
  static void
  dock_add_hotplug_device(struct dock_station *ds,
  			struct dock_dependent_device *dd)
  {

  	mutex_lock(&ds->hp_lock);

  	list_add_tail(&dd->hotplug_list, &ds->hotplug_devices);

  	mutex_unlock(&ds->hp_lock);

  }
  
  /**
   * dock_del_hotplug_device - remove a hotplug handler from the dock station
   * @ds: The dock station
   * @dd: the dependent device struct
   *
   * Delete the dependent device from the dock's hotplug device list
   */
  static void
  dock_del_hotplug_device(struct dock_station *ds,
  			struct dock_dependent_device *dd)
  {

  	mutex_lock(&ds->hp_lock);

  	list_del(&dd->hotplug_list);

  	mutex_unlock(&ds->hp_lock);

  }
  
  /**
   * find_dock_dependent_device - get a device dependent on this dock
   * @ds: the dock station
   * @handle: the acpi_handle of the device we want
   *
   * iterate over the dependent device list for this dock.  If the
   * dependent device matches the handle, return.
   */
  static struct dock_dependent_device *
  find_dock_dependent_device(struct dock_station *ds, acpi_handle handle)
  {
  	struct dock_dependent_device *dd;
  
  	spin_lock(&ds->dd_lock);
  	list_for_each_entry(dd, &ds->dependent_devices, list) {
  		if (handle == dd->handle) {
  			spin_unlock(&ds->dd_lock);
  			return dd;
  		}
  	}
  	spin_unlock(&ds->dd_lock);
  	return NULL;
  }
  
  /*****************************************************************************
   *                         Dock functions                                    *
   *****************************************************************************/
  /**
   * is_dock - see if a device is a dock station
   * @handle: acpi handle of the device
   *
   * If an acpi object has a _DCK method, then it is by definition a dock
   * station, so return true.
   */
  static int is_dock(acpi_handle handle)
  {
  	acpi_status status;
  	acpi_handle tmp;
  
  	status = acpi_get_handle(handle, "_DCK", &tmp);
  	if (ACPI_FAILURE(status))
  		return 0;
  	return 1;
  }

  static int is_ejectable(acpi_handle handle)
  {
  	acpi_status status;
  	acpi_handle tmp;
  
  	status = acpi_get_handle(handle, "_EJ0", &tmp);
  	if (ACPI_FAILURE(status))
  		return 0;
  	return 1;
  }
  
  static int is_ata(acpi_handle handle)
  {
  	acpi_handle tmp;
  
  	if ((ACPI_SUCCESS(acpi_get_handle(handle, "_GTF", &tmp))) ||
  	   (ACPI_SUCCESS(acpi_get_handle(handle, "_GTM", &tmp))) ||
  	   (ACPI_SUCCESS(acpi_get_handle(handle, "_STM", &tmp))) ||
  	   (ACPI_SUCCESS(acpi_get_handle(handle, "_SDD", &tmp))))
  		return 1;
  
  	return 0;
  }
  
  static int is_battery(acpi_handle handle)
  {
  	struct acpi_device_info *info;

  	int ret = 1;

  	if (!ACPI_SUCCESS(acpi_get_object_info(handle, &info)))

  		return 0;

  	if (!(info->valid & ACPI_VALID_HID))
  		ret = 0;
  	else

  		ret = !strcmp("PNP0C0A", info->hardware_id.string);

  	kfree(info);

  	return ret;
  }
  
  static int is_ejectable_bay(acpi_handle handle)
  {
  	acpi_handle phandle;

  	if (!is_ejectable(handle))
  		return 0;
  	if (is_battery(handle) || is_ata(handle))
  		return 1;
  	if (!acpi_get_parent(handle, &phandle) && is_ata(phandle))
  		return 1;
  	return 0;
  }

  /**
   * is_dock_device - see if a device is on a dock station
   * @handle: acpi handle of the device
   *
   * If this device is either the dock station itself,
   * or is a device dependent on the dock station, then it
   * is a dock device
   */
  int is_dock_device(acpi_handle handle)
  {

  	struct dock_station *dock_station;
  
  	if (!dock_station_count)

  		return 0;

  	if (is_dock(handle))

  		return 1;

  
  	list_for_each_entry(dock_station, &dock_stations, sibling)

  		if (find_dock_dependent_device(dock_station, handle))
  			return 1;

  
  	return 0;
  }

  EXPORT_SYMBOL_GPL(is_dock_device);
  
  /**
   * dock_present - see if the dock station is present.
   * @ds: the dock station
   *
   * execute the _STA method.  note that present does not
   * imply that we are docked.
   */
  static int dock_present(struct dock_station *ds)
  {

  	unsigned long long sta;

  	acpi_status status;
  
  	if (ds) {
  		status = acpi_evaluate_integer(ds->handle, "_STA", NULL, &sta);
  		if (ACPI_SUCCESS(status) && sta)
  			return 1;
  	}
  	return 0;
  }

  /**
   * dock_create_acpi_device - add new devices to acpi
   * @handle - handle of the device to add
   *
   *  This function will create a new acpi_device for the given
   *  handle if one does not exist already.  This should cause
   *  acpi to scan for drivers for the given devices, and call
   *  matching driver's add routine.
   *
   *  Returns a pointer to the acpi_device corresponding to the handle.
   */
  static struct acpi_device * dock_create_acpi_device(acpi_handle handle)
  {

  	struct acpi_device *device;

  	struct acpi_device *parent_device;
  	acpi_handle parent;
  	int ret;
  
  	if (acpi_bus_get_device(handle, &device)) {
  		/*
  		 * no device created for this object,
  		 * so we should create one.
  		 */
  		acpi_get_parent(handle, &parent);
  		if (acpi_bus_get_device(parent, &parent_device))
  			parent_device = NULL;
  
  		ret = acpi_bus_add(&device, parent_device, handle,
  			ACPI_BUS_TYPE_DEVICE);
  		if (ret) {

  			pr_debug("error adding bus, %x
  ", -ret);

  			return NULL;
  		}
  	}
  	return device;
  }
  
  /**
   * dock_remove_acpi_device - remove the acpi_device struct from acpi
   * @handle - the handle of the device to remove
   *
   *  Tell acpi to remove the acpi_device.  This should cause any loaded
   *  driver to have it's remove routine called.
   */
  static void dock_remove_acpi_device(acpi_handle handle)
  {
  	struct acpi_device *device;
  	int ret;
  
  	if (!acpi_bus_get_device(handle, &device)) {
  		ret = acpi_bus_trim(device, 1);
  		if (ret)
  			pr_debug("error removing bus, %x
  ", -ret);
  	}
  }

  /**
   * hotplug_dock_devices - insert or remove devices on the dock station
   * @ds: the dock station
   * @event: either bus check or eject request
   *
   * Some devices on the dock station need to have drivers called
   * to perform hotplug operations after a dock event has occurred.
   * Traverse the list of dock devices that have registered a
   * hotplug handler, and call the handler.
   */
  static void hotplug_dock_devices(struct dock_station *ds, u32 event)
  {
  	struct dock_dependent_device *dd;

  	mutex_lock(&ds->hp_lock);

  
  	/*
  	 * First call driver specific hotplug functions
  	 */

  	list_for_each_entry(dd, &ds->hotplug_devices, hotplug_list)

  		if (dd->ops && dd->ops->handler)
  			dd->ops->handler(dd->handle, event, dd->context);

  
  	/*
  	 * Now make sure that an acpi_device is created for each
  	 * dependent device, or removed if this is an eject request.
  	 * This will cause acpi_drivers to be stopped/started if they
  	 * exist
  	 */
  	list_for_each_entry(dd, &ds->dependent_devices, list) {
  		if (event == ACPI_NOTIFY_EJECT_REQUEST)
  			dock_remove_acpi_device(dd->handle);
  		else
  			dock_create_acpi_device(dd->handle);
  	}

  	mutex_unlock(&ds->hp_lock);

  }
  
  static void dock_event(struct dock_station *ds, u32 event, int num)
  {

  	struct device *dev = &ds->dock_device->dev;

  	char event_string[13];

  	char *envp[] = { event_string, NULL };

  	struct dock_dependent_device *dd;

  
  	if (num == UNDOCK_EVENT)

  		sprintf(event_string, "EVENT=undock");

  	else

  		sprintf(event_string, "EVENT=dock");

  	/*

  	 * Indicate that the status of the dock station has
  	 * changed.

  	 */

  	if (num == DOCK_EVENT)
  		kobject_uevent_env(&dev->kobj, KOBJ_CHANGE, envp);
  
  	list_for_each_entry(dd, &ds->hotplug_devices, hotplug_list)
  		if (dd->ops && dd->ops->uevent)
  			dd->ops->uevent(dd->handle, event, dd->context);

  	if (num != DOCK_EVENT)
  		kobject_uevent_env(&dev->kobj, KOBJ_CHANGE, envp);

  }
  
  /**
   * eject_dock - respond to a dock eject request
   * @ds: the dock station
   *
   * This is called after _DCK is called, to execute the dock station's
   * _EJ0 method.
   */
  static void eject_dock(struct dock_station *ds)
  {
  	struct acpi_object_list arg_list;
  	union acpi_object arg;
  	acpi_status status;
  	acpi_handle tmp;
  
  	/* all dock devices should have _EJ0, but check anyway */
  	status = acpi_get_handle(ds->handle, "_EJ0", &tmp);
  	if (ACPI_FAILURE(status)) {
  		pr_debug("No _EJ0 support for dock device
  ");
  		return;
  	}
  
  	arg_list.count = 1;
  	arg_list.pointer = &arg;
  	arg.type = ACPI_TYPE_INTEGER;
  	arg.integer.value = 1;

  	status = acpi_evaluate_object(ds->handle, "_EJ0", &arg_list, NULL);
  	if (ACPI_FAILURE(status))

  		pr_debug("Failed to evaluate _EJ0!
  ");
  }
  
  /**
   * handle_dock - handle a dock event
   * @ds: the dock station
   * @dock: to dock, or undock - that is the question
   *
   * Execute the _DCK method in response to an acpi event
   */
  static void handle_dock(struct dock_station *ds, int dock)
  {
  	acpi_status status;
  	struct acpi_object_list arg_list;
  	union acpi_object arg;
  	struct acpi_buffer buffer = { ACPI_ALLOCATE_BUFFER, NULL };
  	struct acpi_buffer name_buffer = { ACPI_ALLOCATE_BUFFER, NULL };

  
  	acpi_get_name(ds->handle, ACPI_FULL_PATHNAME, &name_buffer);

  	printk(KERN_INFO PREFIX "%s - %s
  ",
  		(char *)name_buffer.pointer, dock ? "docking" : "undocking");

  
  	/* _DCK method has one argument */
  	arg_list.count = 1;
  	arg_list.pointer = &arg;
  	arg.type = ACPI_TYPE_INTEGER;
  	arg.integer.value = dock;
  	status = acpi_evaluate_object(ds->handle, "_DCK", &arg_list, &buffer);

  	if (ACPI_FAILURE(status) && status != AE_NOT_FOUND)

  		ACPI_EXCEPTION((AE_INFO, status, "%s - failed to execute"
  			" _DCK
  ", (char *)name_buffer.pointer));

  	kfree(buffer.pointer);
  	kfree(name_buffer.pointer);
  }
  
  static inline void dock(struct dock_station *ds)
  {
  	handle_dock(ds, 1);
  }
  
  static inline void undock(struct dock_station *ds)
  {
  	handle_dock(ds, 0);
  }
  
  static inline void begin_dock(struct dock_station *ds)
  {
  	ds->flags |= DOCK_DOCKING;
  }
  
  static inline void complete_dock(struct dock_station *ds)
  {
  	ds->flags &= ~(DOCK_DOCKING);
  	ds->last_dock_time = jiffies;
  }

  static inline void begin_undock(struct dock_station *ds)
  {
  	ds->flags |= DOCK_UNDOCKING;
  }
  
  static inline void complete_undock(struct dock_station *ds)
  {
  	ds->flags &= ~(DOCK_UNDOCKING);
  }

  static void dock_lock(struct dock_station *ds, int lock)
  {
  	struct acpi_object_list arg_list;
  	union acpi_object arg;
  	acpi_status status;
  
  	arg_list.count = 1;
  	arg_list.pointer = &arg;
  	arg.type = ACPI_TYPE_INTEGER;
  	arg.integer.value = !!lock;
  	status = acpi_evaluate_object(ds->handle, "_LCK", &arg_list, NULL);
  	if (ACPI_FAILURE(status) && status != AE_NOT_FOUND) {
  		if (lock)
  			printk(KERN_WARNING PREFIX "Locking device failed
  ");
  		else
  			printk(KERN_WARNING PREFIX "Unlocking device failed
  ");
  	}
  }

  /**
   * dock_in_progress - see if we are in the middle of handling a dock event
   * @ds: the dock station
   *
   * Sometimes while docking, false dock events can be sent to the driver
   * because good connections aren't made or some other reason.  Ignore these
   * if we are in the middle of doing something.
   */
  static int dock_in_progress(struct dock_station *ds)
  {
  	if ((ds->flags & DOCK_DOCKING) ||
  	    time_before(jiffies, (ds->last_dock_time + HZ)))
  		return 1;
  	return 0;
  }
  
  /**
   * register_dock_notifier - add yourself to the dock notifier list
   * @nb: the callers notifier block
   *
   * If a driver wishes to be notified about dock events, they can
   * use this function to put a notifier block on the dock notifier list.
   * this notifier call chain will be called after a dock event, but
   * before hotplugging any new devices.
   */
  int register_dock_notifier(struct notifier_block *nb)
  {

  	if (!dock_station_count)

  		return -ENODEV;

  	return atomic_notifier_chain_register(&dock_notifier_list, nb);
  }

  EXPORT_SYMBOL_GPL(register_dock_notifier);
  
  /**
   * unregister_dock_notifier - remove yourself from the dock notifier list
   * @nb: the callers notifier block
   */
  void unregister_dock_notifier(struct notifier_block *nb)
  {

  	if (!dock_station_count)

  		return;

  	atomic_notifier_chain_unregister(&dock_notifier_list, nb);
  }

  EXPORT_SYMBOL_GPL(unregister_dock_notifier);
  
  /**
   * register_hotplug_dock_device - register a hotplug function
   * @handle: the handle of the device

   * @ops: handlers to call after docking

   * @context: device specific data
   *
   * If a driver would like to perform a hotplug operation after a dock
   * event, they can register an acpi_notifiy_handler to be called by
   * the dock driver after _DCK is executed.
   */
  int

  register_hotplug_dock_device(acpi_handle handle, const struct acpi_dock_ops *ops,

  			     void *context)
  {
  	struct dock_dependent_device *dd;

  	struct dock_station *dock_station;

  	int ret = -EINVAL;

  	if (!dock_station_count)

  		return -ENODEV;
  
  	/*
  	 * make sure this handle is for a device dependent on the dock,
  	 * this would include the dock station itself
  	 */

  	list_for_each_entry(dock_station, &dock_stations, sibling) {

  		/*
  		 * An ATA bay can be in a dock and itself can be ejected

  		 * separately, so there are two 'dock stations' which need the

  		 * ops
  		 */

  		dd = find_dock_dependent_device(dock_station, handle);
  		if (dd) {

  			dd->ops = ops;

  			dd->context = context;
  			dock_add_hotplug_device(dock_station, dd);

  			ret = 0;

  		}

  	}

  	return ret;

  }

  EXPORT_SYMBOL_GPL(register_hotplug_dock_device);
  
  /**
   * unregister_hotplug_dock_device - remove yourself from the hotplug list
   * @handle: the acpi handle of the device
   */
  void unregister_hotplug_dock_device(acpi_handle handle)
  {
  	struct dock_dependent_device *dd;

  	struct dock_station *dock_station;

  	if (!dock_station_count)

  		return;

  	list_for_each_entry(dock_station, &dock_stations, sibling) {

  		dd = find_dock_dependent_device(dock_station, handle);
  		if (dd)
  			dock_del_hotplug_device(dock_station, dd);
  	}

  }

  EXPORT_SYMBOL_GPL(unregister_hotplug_dock_device);
  
  /**

   * handle_eject_request - handle an undock request checking for error conditions
   *
   * Check to make sure the dock device is still present, then undock and
   * hotremove all the devices that may need removing.
   */
  static int handle_eject_request(struct dock_station *ds, u32 event)
  {

  	if (dock_in_progress(ds))
  		return -EBUSY;
  
  	/*
  	 * here we need to generate the undock
  	 * event prior to actually doing the undock
  	 * so that the device struct still exists.

  	 * Also, even send the dock event if the
  	 * device is not present anymore

  	 */
  	dock_event(ds, event, UNDOCK_EVENT);

  	hotplug_dock_devices(ds, ACPI_NOTIFY_EJECT_REQUEST);
  	undock(ds);

  	dock_lock(ds, 0);

  	eject_dock(ds);
  	if (dock_present(ds)) {
  		printk(KERN_ERR PREFIX "Unable to undock!
  ");
  		return -EBUSY;
  	}

  	complete_undock(ds);

  	return 0;
  }
  
  /**

   * dock_notify - act upon an acpi dock notification
   * @handle: the dock station handle
   * @event: the acpi event
   * @data: our driver data struct
   *
   * If we are notified to dock, then check to see if the dock is
   * present and then dock.  Notify all drivers of the dock event,

   * and then hotplug and devices that may need hotplugging.

   */
  static void dock_notify(acpi_handle handle, u32 event, void *data)
  {

  	struct dock_station *ds = data;

  	struct acpi_device *tmp;

  	int surprise_removal = 0;

  	/*
  	 * According to acpi spec 3.0a, if a DEVICE_CHECK notification
  	 * is sent and _DCK is present, it is assumed to mean an undock
  	 * request.
  	 */
  	if ((ds->flags & DOCK_IS_DOCK) && event == ACPI_NOTIFY_DEVICE_CHECK)
  		event = ACPI_NOTIFY_EJECT_REQUEST;
  
  	/*
  	 * dock station: BUS_CHECK - docked or surprise removal
  	 *		 DEVICE_CHECK - undocked
  	 * other device: BUS_CHECK/DEVICE_CHECK - added or surprise removal
  	 *
  	 * To simplify event handling, dock dependent device handler always
  	 * get ACPI_NOTIFY_BUS_CHECK/ACPI_NOTIFY_DEVICE_CHECK for add and
  	 * ACPI_NOTIFY_EJECT_REQUEST for removal
  	 */

  	switch (event) {
  	case ACPI_NOTIFY_BUS_CHECK:

  	case ACPI_NOTIFY_DEVICE_CHECK:

  		if (!dock_in_progress(ds) && acpi_bus_get_device(ds->handle,
  		   &tmp)) {

  			begin_dock(ds);
  			dock(ds);
  			if (!dock_present(ds)) {
  				printk(KERN_ERR PREFIX "Unable to dock!
  ");

  				complete_dock(ds);

  				break;
  			}
  			atomic_notifier_call_chain(&dock_notifier_list,
  						   event, NULL);
  			hotplug_dock_devices(ds, event);
  			complete_dock(ds);
  			dock_event(ds, event, DOCK_EVENT);

  			dock_lock(ds, 1);

  			acpi_update_all_gpes();

  			break;

  		}

  		if (dock_present(ds) || dock_in_progress(ds))
  			break;
  		/* This is a surprise removal */
  		surprise_removal = 1;
  		event = ACPI_NOTIFY_EJECT_REQUEST;
  		/* Fall back */

  	case ACPI_NOTIFY_EJECT_REQUEST:

  		begin_undock(ds);

  		if ((immediate_undock && !(ds->flags & DOCK_IS_ATA))
  		   || surprise_removal)

  			handle_eject_request(ds, event);
  		else
  			dock_event(ds, event, UNDOCK_EVENT);

  		break;
  	default:
  		printk(KERN_ERR PREFIX "Unknown dock event %d
  ", event);
  	}
  }

  struct dock_data {
  	acpi_handle handle;
  	unsigned long event;
  	struct dock_station *ds;
  };
  
  static void acpi_dock_deferred_cb(void *context)
  {

  	struct dock_data *data = context;

  
  	dock_notify(data->handle, data->event, data->ds);
  	kfree(data);
  }

  static int acpi_dock_notifier_call(struct notifier_block *this,
  	unsigned long event, void *data)
  {
  	struct dock_station *dock_station;

  	acpi_handle handle = data;

  
  	if (event != ACPI_NOTIFY_BUS_CHECK && event != ACPI_NOTIFY_DEVICE_CHECK
  	   && event != ACPI_NOTIFY_EJECT_REQUEST)
  		return 0;

  	list_for_each_entry(dock_station, &dock_stations, sibling) {

  		if (dock_station->handle == handle) {

  			struct dock_data *dd;

  			dd = kmalloc(sizeof(*dd), GFP_KERNEL);
  			if (!dd)

  				return 0;

  			dd->handle = handle;
  			dd->event = event;
  			dd->ds = dock_station;
  			acpi_os_hotplug_execute(acpi_dock_deferred_cb, dd);

  			return 0 ;
  		}
  	}
  	return 0;
  }
  
  static struct notifier_block dock_acpi_notifier = {
  	.notifier_call = acpi_dock_notifier_call,
  };

  /**
   * find_dock_devices - find devices on the dock station
   * @handle: the handle of the device we are examining
   * @lvl: unused
   * @context: the dock station private data
   * @rv: unused
   *
   * This function is called by acpi_walk_namespace.  It will
   * check to see if an object has an _EJD method.  If it does, then it
   * will see if it is dependent on the dock station.
   */
  static acpi_status
  find_dock_devices(acpi_handle handle, u32 lvl, void *context, void **rv)
  {
  	acpi_status status;

  	acpi_handle tmp, parent;

  	struct dock_station *ds = context;

  
  	status = acpi_bus_get_ejd(handle, &tmp);

  	if (ACPI_FAILURE(status)) {
  		/* try the parent device as well */
  		status = acpi_get_parent(handle, &parent);
  		if (ACPI_FAILURE(status))
  			goto fdd_out;
  		/* see if parent is dependent on dock */
  		status = acpi_bus_get_ejd(parent, &tmp);
  		if (ACPI_FAILURE(status))
  			goto fdd_out;
  	}

  	if (tmp == ds->handle)
  		add_dock_dependent_device(ds, handle);

  fdd_out:

  	return AE_OK;
  }

  /*
   * show_docked - read method for "docked" file in sysfs
   */
  static ssize_t show_docked(struct device *dev,
  			   struct device_attribute *attr, char *buf)
  {

  	struct acpi_device *tmp;

  	struct dock_station *dock_station = dev->platform_data;

  	if (ACPI_SUCCESS(acpi_bus_get_device(dock_station->handle, &tmp)))
  		return snprintf(buf, PAGE_SIZE, "1
  ");
  	return snprintf(buf, PAGE_SIZE, "0
  ");

  }

  static DEVICE_ATTR(docked, S_IRUGO, show_docked, NULL);

  
  /*

   * show_flags - read method for flags file in sysfs
   */
  static ssize_t show_flags(struct device *dev,
  			  struct device_attribute *attr, char *buf)
  {

  	struct dock_station *dock_station = dev->platform_data;

  	return snprintf(buf, PAGE_SIZE, "%d
  ", dock_station->flags);
  
  }

  static DEVICE_ATTR(flags, S_IRUGO, show_flags, NULL);

  
  /*

   * write_undock - write method for "undock" file in sysfs
   */
  static ssize_t write_undock(struct device *dev, struct device_attribute *attr,
  			   const char *buf, size_t count)
  {
  	int ret;

  	struct dock_station *dock_station = dev->platform_data;

  
  	if (!count)
  		return -EINVAL;

  	begin_undock(dock_station);

  	ret = handle_eject_request(dock_station, ACPI_NOTIFY_EJECT_REQUEST);
  	return ret ? ret: count;
  }

  static DEVICE_ATTR(undock, S_IWUSR, NULL, write_undock);

  /*
   * show_dock_uid - read method for "uid" file in sysfs
   */
  static ssize_t show_dock_uid(struct device *dev,
  			     struct device_attribute *attr, char *buf)
  {

  	unsigned long long lbuf;

  	struct dock_station *dock_station = dev->platform_data;

  	acpi_status status = acpi_evaluate_integer(dock_station->handle,
  					"_UID", NULL, &lbuf);
  	if (ACPI_FAILURE(status))

  	    return 0;

  	return snprintf(buf, PAGE_SIZE, "%llx
  ", lbuf);

  }

  static DEVICE_ATTR(uid, S_IRUGO, show_dock_uid, NULL);

  static ssize_t show_dock_type(struct device *dev,
  		struct device_attribute *attr, char *buf)
  {

  	struct dock_station *dock_station = dev->platform_data;

  	char *type;
  
  	if (dock_station->flags & DOCK_IS_DOCK)
  		type = "dock_station";
  	else if (dock_station->flags & DOCK_IS_ATA)
  		type = "ata_bay";
  	else if (dock_station->flags & DOCK_IS_BAT)
  		type = "battery_bay";
  	else
  		type = "unknown";
  
  	return snprintf(buf, PAGE_SIZE, "%s
  ", type);
  }
  static DEVICE_ATTR(type, S_IRUGO, show_dock_type, NULL);

  static struct attribute *dock_attributes[] = {
  	&dev_attr_docked.attr,
  	&dev_attr_flags.attr,
  	&dev_attr_undock.attr,
  	&dev_attr_uid.attr,
  	&dev_attr_type.attr,
  	NULL
  };
  
  static struct attribute_group dock_attribute_group = {
  	.attrs = dock_attributes
  };

  /**
   * dock_add - add a new dock station
   * @handle: the dock station handle
   *
   * allocated and initialize a new dock station device.  Find all devices
   * that are on the dock station, and register for dock event notifications.
   */

  static int __init dock_add(acpi_handle handle)

  {

  	int ret, id;
  	struct dock_station ds, *dock_station;

  	struct platform_device *dd;

  	id = dock_station_count;

  	memset(&ds, 0, sizeof(ds));

  	dd = platform_device_register_data(NULL, "dock", id, &ds, sizeof(ds));
  	if (IS_ERR(dd))
  		return PTR_ERR(dd);
  
  	dock_station = dd->dev.platform_data;

  	dock_station->handle = handle;

  	dock_station->dock_device = dd;

  	dock_station->last_dock_time = jiffies - HZ;

  	mutex_init(&dock_station->hp_lock);

  	spin_lock_init(&dock_station->dd_lock);
  	INIT_LIST_HEAD(&dock_station->sibling);
  	INIT_LIST_HEAD(&dock_station->hotplug_devices);

  	ATOMIC_INIT_NOTIFIER_HEAD(&dock_notifier_list);

  	INIT_LIST_HEAD(&dock_station->dependent_devices);

  	/* we want the dock device to send uevents */

  	dev_set_uevent_suppress(&dd->dev, 0);

  	if (is_dock(handle))
  		dock_station->flags |= DOCK_IS_DOCK;
  	if (is_ata(handle))
  		dock_station->flags |= DOCK_IS_ATA;
  	if (is_battery(handle))
  		dock_station->flags |= DOCK_IS_BAT;

  	ret = sysfs_create_group(&dd->dev.kobj, &dock_attribute_group);

  	if (ret)

  		goto err_unregister;

  	/* Find dependent devices */
  	acpi_walk_namespace(ACPI_TYPE_DEVICE, ACPI_ROOT_OBJECT,

  			    ACPI_UINT32_MAX, find_dock_devices, NULL,
  			    dock_station, NULL);

  
  	/* add the dock station as a device dependent on itself */

  	ret = add_dock_dependent_device(dock_station, handle);
  	if (ret)

  		goto err_rmgroup;

  	dock_station_count++;

  	list_add(&dock_station->sibling, &dock_stations);

  	return 0;

  err_rmgroup:

  	sysfs_remove_group(&dd->dev.kobj, &dock_attribute_group);

  err_unregister:

  	platform_device_unregister(dd);

  	printk(KERN_ERR "%s encountered error %d
  ", __func__, ret);

  	return ret;
  }
  
  /**
   * dock_remove - free up resources related to the dock station
   */

  static int dock_remove(struct dock_station *ds)

  {
  	struct dock_dependent_device *dd, *tmp;

  	struct platform_device *dock_device = ds->dock_device;

  	if (!dock_station_count)

  		return 0;
  
  	/* remove dependent devices */

  	list_for_each_entry_safe(dd, tmp, &ds->dependent_devices, list)
  		kfree(dd);

  	list_del(&ds->sibling);

  	/* cleanup sysfs */

  	sysfs_remove_group(&dock_device->dev.kobj, &dock_attribute_group);

  	platform_device_unregister(dock_device);

  	return 0;
  }
  
  /**
   * find_dock - look for a dock station
   * @handle: acpi handle of a device
   * @lvl: unused
   * @context: counter of dock stations found
   * @rv: unused
   *
   * This is called by acpi_walk_namespace to look for dock stations.
   */

  static __init acpi_status

  find_dock(acpi_handle handle, u32 lvl, void *context, void **rv)
  {

  	if (is_dock(handle))

  		dock_add(handle);

  	return AE_OK;

  }

  static __init acpi_status

  find_bay(acpi_handle handle, u32 lvl, void *context, void **rv)

  {

  	/* If bay is a dock, it's already handled */
  	if (is_ejectable_bay(handle) && !is_dock(handle))

  		dock_add(handle);
  	return AE_OK;
  }

  static int __init dock_init(void)
  {

  	if (acpi_disabled)
  		return 0;

  	/* look for a dock station */
  	acpi_walk_namespace(ACPI_TYPE_DEVICE, ACPI_ROOT_OBJECT,

  			    ACPI_UINT32_MAX, find_dock, NULL, NULL, NULL);

  	/* look for bay */
  	acpi_walk_namespace(ACPI_TYPE_DEVICE, ACPI_ROOT_OBJECT,

  			ACPI_UINT32_MAX, find_bay, NULL, NULL, NULL);

  	if (!dock_station_count) {
  		printk(KERN_INFO PREFIX "No dock devices found.
  ");
  		return 0;
  	}

  	register_acpi_bus_notifier(&dock_acpi_notifier);

  	printk(KERN_INFO PREFIX "%s: %d docks/bays found
  ",
  		ACPI_DOCK_DRIVER_DESCRIPTION, dock_station_count);

  	return 0;
  }
  
  static void __exit dock_exit(void)
  {

  	struct dock_station *tmp, *dock_station;

  	unregister_acpi_bus_notifier(&dock_acpi_notifier);

  	list_for_each_entry_safe(dock_station, tmp, &dock_stations, sibling)

  		dock_remove(dock_station);

  }

  /*
   * Must be called before drivers of devices in dock, otherwise we can't know
   * which devices are in a dock
   */
  subsys_initcall(dock_init);

  module_exit(dock_exit);