summaryrefslogtreecommitdiff
path: root/drivers/acpi/button.c
blob: 3c35e57dd8549a92f1b694718480ca405862f631 (plain)
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
// SPDX-License-Identifier: GPL-2.0-or-later
/*
 *  button.c - ACPI Button Driver
 *
 *  Copyright (C) 2001, 2002 Andy Grover <andrew.grover@intel.com>
 *  Copyright (C) 2001, 2002 Paul Diefenbaugh <paul.s.diefenbaugh@intel.com>
 */

#define pr_fmt(fmt) "ACPI: button: " fmt

#include <linux/compiler.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/types.h>
#include <linux/proc_fs.h>
#include <linux/seq_file.h>
#include <linux/input.h>
#include <linux/slab.h>
#include <linux/acpi.h>
#include <linux/dmi.h>
#include <acpi/button.h>

#define PREFIX "ACPI: "

#define ACPI_BUTTON_CLASS		"button"
#define ACPI_BUTTON_FILE_STATE		"state"
#define ACPI_BUTTON_TYPE_UNKNOWN	0x00
#define ACPI_BUTTON_NOTIFY_STATUS	0x80

#define ACPI_BUTTON_SUBCLASS_POWER	"power"
#define ACPI_BUTTON_DEVICE_NAME_POWER	"Power Button"
#define ACPI_BUTTON_TYPE_POWER		0x01

#define ACPI_BUTTON_SUBCLASS_SLEEP	"sleep"
#define ACPI_BUTTON_DEVICE_NAME_SLEEP	"Sleep Button"
#define ACPI_BUTTON_TYPE_SLEEP		0x03

#define ACPI_BUTTON_SUBCLASS_LID	"lid"
#define ACPI_BUTTON_DEVICE_NAME_LID	"Lid Switch"
#define ACPI_BUTTON_TYPE_LID		0x05

enum {
	ACPI_BUTTON_LID_INIT_IGNORE,
	ACPI_BUTTON_LID_INIT_OPEN,
	ACPI_BUTTON_LID_INIT_METHOD,
	ACPI_BUTTON_LID_INIT_DISABLED,
};

static const char * const lid_init_state_str[] = {
	[ACPI_BUTTON_LID_INIT_IGNORE]		= "ignore",
	[ACPI_BUTTON_LID_INIT_OPEN]		= "open",
	[ACPI_BUTTON_LID_INIT_METHOD]		= "method",
	[ACPI_BUTTON_LID_INIT_DISABLED]		= "disabled",
};

#define _COMPONENT		ACPI_BUTTON_COMPONENT
ACPI_MODULE_NAME("button");

MODULE_AUTHOR("Paul Diefenbaugh");
MODULE_DESCRIPTION("ACPI Button Driver");
MODULE_LICENSE("GPL");

static const struct acpi_device_id button_device_ids[] = {
	{ACPI_BUTTON_HID_LID,    0},
	{ACPI_BUTTON_HID_SLEEP,  0},
	{ACPI_BUTTON_HID_SLEEPF, 0},
	{ACPI_BUTTON_HID_POWER,  0},
	{ACPI_BUTTON_HID_POWERF, 0},
	{"", 0},
};
MODULE_DEVICE_TABLE(acpi, button_device_ids);

/* Please keep this list sorted alphabetically by vendor and model */
static const struct dmi_system_id dmi_lid_quirks[] = {
	{
		/*
		 * Acer Switch 10 SW5-012. _LID method messes with home and
		 * power button GPIO IRQ settings causing an interrupt storm on
		 * both GPIOs. This is unfixable without a DSDT override, so we
		 * have to disable the lid-switch functionality altogether :|
		 */
		.matches = {
			DMI_MATCH(DMI_SYS_VENDOR, "Acer"),
			DMI_MATCH(DMI_PRODUCT_NAME, "Aspire SW5-012"),
		},
		.driver_data = (void *)(long)ACPI_BUTTON_LID_INIT_DISABLED,
	},
	{
		/* GP-electronic T701, _LID method points to a floating GPIO */
		.matches = {
			DMI_MATCH(DMI_SYS_VENDOR, "Insyde"),
			DMI_MATCH(DMI_PRODUCT_NAME, "T701"),
			DMI_MATCH(DMI_BIOS_VERSION, "BYT70A.YNCHENG.WIN.007"),
		},
		.driver_data = (void *)(long)ACPI_BUTTON_LID_INIT_DISABLED,
	},
	{
		/*
		 * Medion Akoya E2215T, notification of the LID device only
		 * happens on close, not on open and _LID always returns closed.
		 */
		.matches = {
			DMI_MATCH(DMI_SYS_VENDOR, "MEDION"),
			DMI_MATCH(DMI_PRODUCT_NAME, "E2215T MD60198"),
		},
		.driver_data = (void *)(long)ACPI_BUTTON_LID_INIT_OPEN,
	},
	{
		/*
		 * Razer Blade Stealth 13 late 2019, notification of the LID device
		 * only happens on close, not on open and _LID always returns closed.
		 */
		.matches = {
			DMI_MATCH(DMI_SYS_VENDOR, "Razer"),
			DMI_MATCH(DMI_PRODUCT_NAME, "Razer Blade Stealth 13 Late 2019"),
		},
		.driver_data = (void *)(long)ACPI_BUTTON_LID_INIT_OPEN,
	},
	{}
};

static int acpi_button_add(struct acpi_device *device);
static int acpi_button_remove(struct acpi_device *device);
static void acpi_button_notify(struct acpi_device *device, u32 event);

#ifdef CONFIG_PM_SLEEP
static int acpi_button_suspend(struct device *dev);
static int acpi_button_resume(struct device *dev);
#else
#define acpi_button_suspend NULL
#define acpi_button_resume NULL
#endif
static SIMPLE_DEV_PM_OPS(acpi_button_pm, acpi_button_suspend, acpi_button_resume);

static struct acpi_driver acpi_button_driver = {
	.name = "button",
	.class = ACPI_BUTTON_CLASS,
	.ids = button_device_ids,
	.ops = {
		.add = acpi_button_add,
		.remove = acpi_button_remove,
		.notify = acpi_button_notify,
	},
	.drv.pm = &acpi_button_pm,
};

struct acpi_button {
	unsigned int type;
	struct input_dev *input;
	char phys[32];			/* for input device */
	unsigned long pushed;
	int last_state;
	ktime_t last_time;
	bool suspended;
};

static struct acpi_device *lid_device;
static long lid_init_state = -1;

static unsigned long lid_report_interval __read_mostly = 500;
module_param(lid_report_interval, ulong, 0644);
MODULE_PARM_DESC(lid_report_interval, "Interval (ms) between lid key events");

/* --------------------------------------------------------------------------
                              FS Interface (/proc)
   -------------------------------------------------------------------------- */

static struct proc_dir_entry *acpi_button_dir;
static struct proc_dir_entry *acpi_lid_dir;

static int acpi_lid_evaluate_state(struct acpi_device *device)
{
	unsigned long long lid_state;
	acpi_status status;

	status = acpi_evaluate_integer(device->handle, "_LID", NULL, &lid_state);
	if (ACPI_FAILURE(status))
		return -ENODEV;

	return lid_state ? 1 : 0;
}

static int acpi_lid_notify_state(struct acpi_device *device, int state)
{
	struct acpi_button *button = acpi_driver_data(device);
	ktime_t next_report;
	bool do_update;

	/*
	 * In lid_init_state=ignore mode, if user opens/closes lid
	 * frequently with "open" missing, and "last_time" is also updated
	 * frequently, "close" cannot be delivered to the userspace.
	 * So "last_time" is only updated after a timeout or an actual
	 * switch.
	 */
	if (lid_init_state != ACPI_BUTTON_LID_INIT_IGNORE ||
	    button->last_state != !!state)
		do_update = true;
	else
		do_update = false;

	next_report = ktime_add(button->last_time,
				ms_to_ktime(lid_report_interval));
	if (button->last_state == !!state &&
	    ktime_after(ktime_get(), next_report)) {
		/* Complain the buggy firmware */
		pr_warn_once("The lid device is not compliant to SW_LID.\n");

		/*
		 * Send the unreliable complement switch event:
		 *
		 * On most platforms, the lid device is reliable. However
		 * there are exceptions:
		 * 1. Platforms returning initial lid state as "close" by
		 *    default after booting/resuming:
		 *     https://bugzilla.kernel.org/show_bug.cgi?id=89211
		 *     https://bugzilla.kernel.org/show_bug.cgi?id=106151
		 * 2. Platforms never reporting "open" events:
		 *     https://bugzilla.kernel.org/show_bug.cgi?id=106941
		 * On these buggy platforms, the usage model of the ACPI
		 * lid device actually is:
		 * 1. The initial returning value of _LID may not be
		 *    reliable.
		 * 2. The open event may not be reliable.
		 * 3. The close event is reliable.
		 *
		 * But SW_LID is typed as input switch event, the input
		 * layer checks if the event is redundant. Hence if the
		 * state is not switched, the userspace cannot see this
		 * platform triggered reliable event. By inserting a
		 * complement switch event, it then is guaranteed that the
		 * platform triggered reliable one can always be seen by
		 * the userspace.
		 */
		if (lid_init_state == ACPI_BUTTON_LID_INIT_IGNORE) {
			do_update = true;
			/*
			 * Do generate complement switch event for "close"
			 * as "close" is reliable and wrong "open" won't
			 * trigger unexpected behaviors.
			 * Do not generate complement switch event for
			 * "open" as "open" is not reliable and wrong
			 * "close" will trigger unexpected behaviors.
			 */
			if (!state) {
				input_report_switch(button->input,
						    SW_LID, state);
				input_sync(button->input);
			}
		}
	}
	/* Send the platform triggered reliable event */
	if (do_update) {
		acpi_handle_debug(device->handle, "ACPI LID %s\n",
				  state ? "open" : "closed");
		input_report_switch(button->input, SW_LID, !state);
		input_sync(button->input);
		button->last_state = !!state;
		button->last_time = ktime_get();
	}

	return 0;
}

static int __maybe_unused acpi_button_state_seq_show(struct seq_file *seq,
						     void *offset)
{
	struct acpi_device *device = seq->private;
	int state;

	state = acpi_lid_evaluate_state(device);
	seq_printf(seq, "state:      %s\n",
		   state < 0 ? "unsupported" : (state ? "open" : "closed"));
	return 0;
}

static int acpi_button_add_fs(struct acpi_device *device)
{
	struct acpi_button *button = acpi_driver_data(device);
	struct proc_dir_entry *entry = NULL;
	int ret = 0;

	/* procfs I/F for ACPI lid device only */
	if (button->type != ACPI_BUTTON_TYPE_LID)
		return 0;

	if (acpi_button_dir || acpi_lid_dir) {
		printk(KERN_ERR PREFIX "More than one Lid device found!\n");
		return -EEXIST;
	}

	/* create /proc/acpi/button */
	acpi_button_dir = proc_mkdir(ACPI_BUTTON_CLASS, acpi_root_dir);
	if (!acpi_button_dir)
		return -ENODEV;

	/* create /proc/acpi/button/lid */
	acpi_lid_dir = proc_mkdir(ACPI_BUTTON_SUBCLASS_LID, acpi_button_dir);
	if (!acpi_lid_dir) {
		ret = -ENODEV;
		goto remove_button_dir;
	}

	/* create /proc/acpi/button/lid/LID/ */
	acpi_device_dir(device) = proc_mkdir(acpi_device_bid(device), acpi_lid_dir);
	if (!acpi_device_dir(device)) {
		ret = -ENODEV;
		goto remove_lid_dir;
	}

	/* create /proc/acpi/button/lid/LID/state */
	entry = proc_create_single_data(ACPI_BUTTON_FILE_STATE, S_IRUGO,
			acpi_device_dir(device), acpi_button_state_seq_show,
			device);
	if (!entry) {
		ret = -ENODEV;
		goto remove_dev_dir;
	}

done:
	return ret;

remove_dev_dir:
	remove_proc_entry(acpi_device_bid(device),
			  acpi_lid_dir);
	acpi_device_dir(device) = NULL;
remove_lid_dir:
	remove_proc_entry(ACPI_BUTTON_SUBCLASS_LID, acpi_button_dir);
	acpi_lid_dir = NULL;
remove_button_dir:
	remove_proc_entry(ACPI_BUTTON_CLASS, acpi_root_dir);
	acpi_button_dir = NULL;
	goto done;
}

static int acpi_button_remove_fs(struct acpi_device *device)
{
	struct acpi_button *button = acpi_driver_data(device);

	if (button->type != ACPI_BUTTON_TYPE_LID)
		return 0;

	remove_proc_entry(ACPI_BUTTON_FILE_STATE,
			  acpi_device_dir(device));
	remove_proc_entry(acpi_device_bid(device),
			  acpi_lid_dir);
	acpi_device_dir(device) = NULL;
	remove_proc_entry(ACPI_BUTTON_SUBCLASS_LID, acpi_button_dir);
	acpi_lid_dir = NULL;
	remove_proc_entry(ACPI_BUTTON_CLASS, acpi_root_dir);
	acpi_button_dir = NULL;

	return 0;
}

/* --------------------------------------------------------------------------
                                Driver Interface
   -------------------------------------------------------------------------- */
int acpi_lid_open(void)
{
	if (!lid_device)
		return -ENODEV;

	return acpi_lid_evaluate_state(lid_device);
}
EXPORT_SYMBOL(acpi_lid_open);

static int acpi_lid_update_state(struct acpi_device *device,
				 bool signal_wakeup)
{
	int state;

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

	if (state && signal_wakeup)
		acpi_pm_wakeup_event(&device->dev);

	return acpi_lid_notify_state(device, state);
}

static void acpi_lid_initialize_state(struct acpi_device *device)
{
	switch (lid_init_state) {
	case ACPI_BUTTON_LID_INIT_OPEN:
		(void)acpi_lid_notify_state(device, 1);
		break;
	case ACPI_BUTTON_LID_INIT_METHOD:
		(void)acpi_lid_update_state(device, false);
		break;
	case ACPI_BUTTON_LID_INIT_IGNORE:
	default:
		break;
	}
}

static void acpi_button_notify(struct acpi_device *device, u32 event)
{
	struct acpi_button *button = acpi_driver_data(device);
	struct input_dev *input;
	int users;

	switch (event) {
	case ACPI_FIXED_HARDWARE_EVENT:
		event = ACPI_BUTTON_NOTIFY_STATUS;
		/* fall through */
	case ACPI_BUTTON_NOTIFY_STATUS:
		input = button->input;
		if (button->type == ACPI_BUTTON_TYPE_LID) {
			mutex_lock(&button->input->mutex);
			users = button->input->users;
			mutex_unlock(&button->input->mutex);
			if (users)
				acpi_lid_update_state(device, true);
		} else {
			int keycode;

			acpi_pm_wakeup_event(&device->dev);
			if (button->suspended)
				break;

			keycode = test_bit(KEY_SLEEP, input->keybit) ?
						KEY_SLEEP : KEY_POWER;
			input_report_key(input, keycode, 1);
			input_sync(input);
			input_report_key(input, keycode, 0);
			input_sync(input);

			acpi_bus_generate_netlink_event(
					device->pnp.device_class,
					dev_name(&device->dev),
					event, ++button->pushed);
		}
		break;
	default:
		ACPI_DEBUG_PRINT((ACPI_DB_INFO,
				  "Unsupported event [0x%x]\n", event));
		break;
	}
}

#ifdef CONFIG_PM_SLEEP
static int acpi_button_suspend(struct device *dev)
{
	struct acpi_device *device = to_acpi_device(dev);
	struct acpi_button *button = acpi_driver_data(device);

	button->suspended = true;
	return 0;
}

static int acpi_button_resume(struct device *dev)
{
	struct acpi_device *device = to_acpi_device(dev);
	struct acpi_button *button = acpi_driver_data(device);

	button->suspended = false;
	if (button->type == ACPI_BUTTON_TYPE_LID && button->input->users) {
		button->last_state = !!acpi_lid_evaluate_state(device);
		button->last_time = ktime_get();
		acpi_lid_initialize_state(device);
	}
	return 0;
}
#endif

static int acpi_lid_input_open(struct input_dev *input)
{
	struct acpi_device *device = input_get_drvdata(input);
	struct acpi_button *button = acpi_driver_data(device);

	button->last_state = !!acpi_lid_evaluate_state(device);
	button->last_time = ktime_get();
	acpi_lid_initialize_state(device);

	return 0;
}

static int acpi_button_add(struct acpi_device *device)
{
	struct acpi_button *button;
	struct input_dev *input;
	const char *hid = acpi_device_hid(device);
	char *name, *class;
	int error;

	if (!strcmp(hid, ACPI_BUTTON_HID_LID) &&
	     lid_init_state == ACPI_BUTTON_LID_INIT_DISABLED)
		return -ENODEV;

	button = kzalloc(sizeof(struct acpi_button), GFP_KERNEL);
	if (!button)
		return -ENOMEM;

	device->driver_data = button;

	button->input = input = input_allocate_device();
	if (!input) {
		error = -ENOMEM;
		goto err_free_button;
	}

	name = acpi_device_name(device);
	class = acpi_device_class(device);

	if (!strcmp(hid, ACPI_BUTTON_HID_POWER) ||
	    !strcmp(hid, ACPI_BUTTON_HID_POWERF)) {
		button->type = ACPI_BUTTON_TYPE_POWER;
		strcpy(name, ACPI_BUTTON_DEVICE_NAME_POWER);
		sprintf(class, "%s/%s",
			ACPI_BUTTON_CLASS, ACPI_BUTTON_SUBCLASS_POWER);
	} else if (!strcmp(hid, ACPI_BUTTON_HID_SLEEP) ||
		   !strcmp(hid, ACPI_BUTTON_HID_SLEEPF)) {
		button->type = ACPI_BUTTON_TYPE_SLEEP;
		strcpy(name, ACPI_BUTTON_DEVICE_NAME_SLEEP);
		sprintf(class, "%s/%s",
			ACPI_BUTTON_CLASS, ACPI_BUTTON_SUBCLASS_SLEEP);
	} else if (!strcmp(hid, ACPI_BUTTON_HID_LID)) {
		button->type = ACPI_BUTTON_TYPE_LID;
		strcpy(name, ACPI_BUTTON_DEVICE_NAME_LID);
		sprintf(class, "%s/%s",
			ACPI_BUTTON_CLASS, ACPI_BUTTON_SUBCLASS_LID);
		input->open = acpi_lid_input_open;
	} else {
		printk(KERN_ERR PREFIX "Unsupported hid [%s]\n", hid);
		error = -ENODEV;
		goto err_free_input;
	}

	error = acpi_button_add_fs(device);
	if (error)
		goto err_free_input;

	snprintf(button->phys, sizeof(button->phys), "%s/button/input0", hid);

	input->name = name;
	input->phys = button->phys;
	input->id.bustype = BUS_HOST;
	input->id.product = button->type;
	input->dev.parent = &device->dev;

	switch (button->type) {
	case ACPI_BUTTON_TYPE_POWER:
		input_set_capability(input, EV_KEY, KEY_POWER);
		break;

	case ACPI_BUTTON_TYPE_SLEEP:
		input_set_capability(input, EV_KEY, KEY_SLEEP);
		break;

	case ACPI_BUTTON_TYPE_LID:
		input_set_capability(input, EV_SW, SW_LID);
		break;
	}

	input_set_drvdata(input, device);
	error = input_register_device(input);
	if (error)
		goto err_remove_fs;
	if (button->type == ACPI_BUTTON_TYPE_LID) {
		/*
		 * This assumes there's only one lid device, or if there are
		 * more we only care about the last one...
		 */
		lid_device = device;
	}

	device_init_wakeup(&device->dev, true);
	printk(KERN_INFO PREFIX "%s [%s]\n", name, acpi_device_bid(device));
	return 0;

 err_remove_fs:
	acpi_button_remove_fs(device);
 err_free_input:
	input_free_device(input);
 err_free_button:
	kfree(button);
	return error;
}

static int acpi_button_remove(struct acpi_device *device)
{
	struct acpi_button *button = acpi_driver_data(device);

	acpi_button_remove_fs(device);
	input_unregister_device(button->input);
	kfree(button);
	return 0;
}

static int param_set_lid_init_state(const char *val,
				    const struct kernel_param *kp)
{
	int i;

	i = sysfs_match_string(lid_init_state_str, val);
	if (i < 0)
		return i;

	lid_init_state = i;
	pr_info("Initial lid state set to '%s'\n", lid_init_state_str[i]);
	return 0;
}

static int param_get_lid_init_state(char *buf, const struct kernel_param *kp)
{
	int i, c = 0;

	for (i = 0; i < ARRAY_SIZE(lid_init_state_str); i++)
		if (i == lid_init_state)
			c += sprintf(buf + c, "[%s] ", lid_init_state_str[i]);
		else
			c += sprintf(buf + c, "%s ", lid_init_state_str[i]);

	buf[c - 1] = '\n'; /* Replace the final space with a newline */

	return c;
}

module_param_call(lid_init_state,
		  param_set_lid_init_state, param_get_lid_init_state,
		  NULL, 0644);
MODULE_PARM_DESC(lid_init_state, "Behavior for reporting LID initial state");

static int acpi_button_register_driver(struct acpi_driver *driver)
{
	const struct dmi_system_id *dmi_id;

	if (lid_init_state == -1) {
		dmi_id = dmi_first_match(dmi_lid_quirks);
		if (dmi_id)
			lid_init_state = (long)dmi_id->driver_data;
		else
			lid_init_state = ACPI_BUTTON_LID_INIT_METHOD;
	}

	/*
	 * Modules such as nouveau.ko and i915.ko have a link time dependency
	 * on acpi_lid_open(), and would therefore not be loadable on ACPI
	 * capable kernels booted in non-ACPI mode if the return value of
	 * acpi_bus_register_driver() is returned from here with ACPI disabled
	 * when this driver is built as a module.
	 */
	if (acpi_disabled)
		return 0;

	return acpi_bus_register_driver(driver);
}

static void acpi_button_unregister_driver(struct acpi_driver *driver)
{
	if (!acpi_disabled)
		acpi_bus_unregister_driver(driver);
}

module_driver(acpi_button_driver, acpi_button_register_driver,
	       acpi_button_unregister_driver);