aboutsummaryrefslogtreecommitdiffstats
path: root/drivers/acpi/dock.c
blob: 510a9452429848d20abae91b47a9005aa95c4b8f (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
/*
 *  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/init.h>
#include <linux/types.h>
#include <linux/notifier.h>
#include <acpi/acpi_bus.h>
#include <acpi/acpi_drivers.h>

#define ACPI_DOCK_DRIVER_NAME "ACPI Dock Station Driver"

ACPI_MODULE_NAME("dock")
MODULE_AUTHOR("Kristen Carlson Accardi");
MODULE_DESCRIPTION(ACPI_DOCK_DRIVER_NAME);
MODULE_LICENSE("GPL");

static struct atomic_notifier_head dock_notifier_list;

struct dock_station {
	acpi_handle handle;
	unsigned long last_dock_time;
	u32 flags;
	spinlock_t dd_lock;
	spinlock_t hp_lock;
	struct list_head dependent_devices;
	struct list_head hotplug_devices;
};

struct dock_dependent_device {
	struct list_head list;
	struct list_head hotplug_list;
	acpi_handle handle;
	acpi_notify_handler handler;
	void *context;
};

#define DOCK_DOCKING	0x00000001
#define DOCK_EVENT	KOBJ_DOCK
#define UNDOCK_EVENT	KOBJ_UNDOCK

static struct dock_station *dock_station;

/*****************************************************************************
 *                         Dock Dependent device functions                   *
 *****************************************************************************/
/**
 *  alloc_dock_dependent_device - allocate and init a dependent device
 *  @handle: the acpi_handle of the dependent device
 *
 *  Allocate memory for a dependent device structure for a device referenced
 *  by the acpi handle
 */
static struct dock_dependent_device *
alloc_dock_dependent_device(acpi_handle handle)
{
	struct dock_dependent_device *dd;

	dd = kzalloc(sizeof(*dd), GFP_KERNEL);
	if (dd) {
		dd->handle = handle;
		INIT_LIST_HEAD(&dd->list);
		INIT_LIST_HEAD(&dd->hotplug_list);
	}
	return dd;
}

/**
 * add_dock_dependent_device - associate a device with the dock station
 * @ds: The dock station
 * @dd: The dependent device
 *
 * Add the dependent device to the dock's dependent device list.
 */
static void
add_dock_dependent_device(struct dock_station *ds,
			  struct dock_dependent_device *dd)
{
	spin_lock(&ds->dd_lock);
	list_add_tail(&dd->list, &ds->dependent_devices);
	spin_unlock(&ds->dd_lock);
}

/**
 * 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)
{
	spin_lock(&ds->hp_lock);
	list_add_tail(&dd->hotplug_list, &ds->hotplug_devices);
	spin_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)
{
	spin_lock(&ds->hp_lock);
	list_del(&dd->hotplug_list);
	spin_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;
}

/**
 * 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)
{
	if (!dock_station)
		return 0;

	if (is_dock(handle) || 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 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 = NULL;
	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\n",
				-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\n", -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;

	spin_lock(&ds->hp_lock);

	/*
	 * First call driver specific hotplug functions
	 */
	list_for_each_entry(dd, &ds->hotplug_devices, hotplug_list) {
		if (dd->handler)
			dd->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);
	}
	spin_unlock(&ds->hp_lock);
}

static void dock_event(struct dock_station *ds, u32 event, int num)
{
	struct acpi_device *device;

	device = dock_create_acpi_device(ds->handle);
	if (device)
		kobject_uevent(&device->kobj, num);
}

/**
 * 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\n");
		return;
	}

	arg_list.count = 1;
	arg_list.pointer = &arg;
	arg.type = ACPI_TYPE_INTEGER;
	arg.integer.value = 1;

	if (ACPI_FAILURE(acpi_evaluate_object(ds->handle, "_EJ0",
					      &arg_list, NULL)))
		pr_debug("Failed to evaluate _EJ0!\n");
}

/**
 * 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 };
	union acpi_object *obj;

	acpi_get_name(ds->handle, ACPI_FULL_PATHNAME, &name_buffer);
	obj = name_buffer.pointer;

	printk(KERN_INFO PREFIX "%s\n", 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))
		pr_debug("%s: failed to execute _DCK\n", obj->string.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;
}

/**
 * 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)
{
	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)
{
	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
 * @handler: the acpi_notifier_handler 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, acpi_notify_handler handler,
			     void *context)
{
	struct dock_dependent_device *dd;

	if (!dock_station)
		return -ENODEV;

	/*
	 * make sure this handle is for a device dependent on the dock,
	 * this would include the dock station itself
	 */
	dd = find_dock_dependent_device(dock_station, handle);
	if (dd) {
		dd->handler = handler;
		dd->context = context;
		dock_add_hotplug_device(dock_station, dd);
		return 0;
	}

	return -EINVAL;
}

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;

	if (!dock_station)
		return;

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

EXPORT_SYMBOL_GPL(unregister_hotplug_dock_device);

/**
 * 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.  For undock
 * check to make sure the dock device is still present, then undock
 * and hotremove all the devices that may need removing.
 */
static void dock_notify(acpi_handle handle, u32 event, void *data)
{
	struct dock_station *ds = (struct dock_station *)data;

	switch (event) {
	case ACPI_NOTIFY_BUS_CHECK:
		if (!dock_in_progress(ds) && dock_present(ds)) {
			begin_dock(ds);
			dock(ds);
			if (!dock_present(ds)) {
				printk(KERN_ERR PREFIX "Unable to dock!\n");
				break;
			}
			atomic_notifier_call_chain(&dock_notifier_list,
						   event, NULL);
			hotplug_dock_devices(ds, event);
			complete_dock(ds);
			dock_event(ds, event, DOCK_EVENT);
		}
		break;
	case ACPI_NOTIFY_DEVICE_CHECK:
	/*
         * 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.  This notify routine will only be called
         * for objects defining _DCK, so we will fall through to eject
         * request here.  However, we will pass an eject request through
	 * to the driver who wish to hotplug.
         */
	case ACPI_NOTIFY_EJECT_REQUEST:
		if (!dock_in_progress(ds) && dock_present(ds)) {
			/*
			 * here we need to generate the undock
			 * event prior to actually doing the undock
			 * so that the device struct still exists.
			 */
			dock_event(ds, event, UNDOCK_EVENT);
			hotplug_dock_devices(ds, ACPI_NOTIFY_EJECT_REQUEST);
			undock(ds);
			eject_dock(ds);
			if (dock_present(ds))
				printk(KERN_ERR PREFIX "Unable to undock!\n");
		}
		break;
	default:
		printk(KERN_ERR PREFIX "Unknown dock event %d\n", event);
	}
}

/**
 * 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;
	struct dock_station *ds = (struct dock_station *)context;
	struct dock_dependent_device *dd;

	status = acpi_bus_get_ejd(handle, &tmp);
	if (ACPI_FAILURE(status))
		return AE_OK;

	if (tmp == ds->handle) {
		dd = alloc_dock_dependent_device(handle);
		if (dd)
			add_dock_dependent_device(ds, dd);
	}

	return AE_OK;
}

/**
 * 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 dock_add(acpi_handle handle)
{
	int ret;
	acpi_status status;
	struct dock_dependent_device *dd;

	/* allocate & initialize the dock_station private data */
	dock_station = kzalloc(sizeof(*dock_station), GFP_KERNEL);
	if (!dock_station)
		return -ENOMEM;
	dock_station->handle = handle;
	dock_station->last_dock_time = jiffies - HZ;
	INIT_LIST_HEAD(&dock_station->dependent_devices);
	INIT_LIST_HEAD(&dock_station->hotplug_devices);
	spin_lock_init(&dock_station->dd_lock);
	spin_lock_init(&dock_station->hp_lock);

	/* Find dependent devices */
	acpi_walk_namespace(ACPI_TYPE_DEVICE, ACPI_ROOT_OBJECT,
			    ACPI_UINT32_MAX, find_dock_devices, dock_station,
			    NULL);

	/* add the dock station as a device dependent on itself */
	dd = alloc_dock_dependent_device(handle);
	if (!dd) {
		kfree(dock_station);
		return -ENOMEM;
	}
	add_dock_dependent_device(dock_station, dd);

	/* register for dock events */
	status = acpi_install_notify_handler(dock_station->handle,
					     ACPI_SYSTEM_NOTIFY,
					     dock_notify, dock_station);

	if (ACPI_FAILURE(status)) {
		printk(KERN_ERR PREFIX "Error installing notify handler\n");
		ret = -ENODEV;
		goto dock_add_err;
	}

	printk(KERN_INFO PREFIX "%s \n", ACPI_DOCK_DRIVER_NAME);

	return 0;

dock_add_err:
	kfree(dock_station);
	kfree(dd);
	return ret;
}

/**
 * dock_remove - free up resources related to the dock station
 */
static int dock_remove(void)
{
	struct dock_dependent_device *dd, *tmp;
	acpi_status status;

	if (!dock_station)
		return 0;

	/* remove dependent devices */
	list_for_each_entry_safe(dd, tmp, &dock_station->dependent_devices,
				 list)
	    kfree(dd);

	/* remove dock notify handler */
	status = acpi_remove_notify_handler(dock_station->handle,
					    ACPI_SYSTEM_NOTIFY,
					    dock_notify);
	if (ACPI_FAILURE(status))
		printk(KERN_ERR "Error removing notify handler\n");

	/* free dock station memory */
	kfree(dock_station);
	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 acpi_status
find_dock(acpi_handle handle, u32 lvl, void *context, void **rv)
{
	int *count = (int *)context;
	acpi_status status = AE_OK;

	if (is_dock(handle)) {
		if (dock_add(handle) >= 0) {
			(*count)++;
			status = AE_CTRL_TERMINATE;
		}
	}
	return status;
}

static int __init dock_init(void)
{
	int num = 0;

	dock_station = NULL;

	/* look for a dock station */
	acpi_walk_namespace(ACPI_TYPE_DEVICE, ACPI_ROOT_OBJECT,
			    ACPI_UINT32_MAX, find_dock, &num, NULL);

	if (!num)
		return -ENODEV;

	return 0;
}

static void __exit dock_exit(void)
{
	dock_remove();
}

postcore_initcall(dock_init);
module_exit(dock_exit);