xref: /openbmc/linux/drivers/acpi/button.c (revision 28dce2c4)
1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3  *  button.c - ACPI Button Driver
4  *
5  *  Copyright (C) 2001, 2002 Andy Grover <andrew.grover@intel.com>
6  *  Copyright (C) 2001, 2002 Paul Diefenbaugh <paul.s.diefenbaugh@intel.com>
7  */
8 
9 #define pr_fmt(fmt) "ACPI: button: " fmt
10 
11 #include <linux/compiler.h>
12 #include <linux/kernel.h>
13 #include <linux/module.h>
14 #include <linux/init.h>
15 #include <linux/types.h>
16 #include <linux/proc_fs.h>
17 #include <linux/seq_file.h>
18 #include <linux/input.h>
19 #include <linux/slab.h>
20 #include <linux/acpi.h>
21 #include <linux/dmi.h>
22 #include <acpi/button.h>
23 
24 #define ACPI_BUTTON_CLASS		"button"
25 #define ACPI_BUTTON_FILE_STATE		"state"
26 #define ACPI_BUTTON_TYPE_UNKNOWN	0x00
27 #define ACPI_BUTTON_NOTIFY_STATUS	0x80
28 
29 #define ACPI_BUTTON_SUBCLASS_POWER	"power"
30 #define ACPI_BUTTON_DEVICE_NAME_POWER	"Power Button"
31 #define ACPI_BUTTON_TYPE_POWER		0x01
32 
33 #define ACPI_BUTTON_SUBCLASS_SLEEP	"sleep"
34 #define ACPI_BUTTON_DEVICE_NAME_SLEEP	"Sleep Button"
35 #define ACPI_BUTTON_TYPE_SLEEP		0x03
36 
37 #define ACPI_BUTTON_SUBCLASS_LID	"lid"
38 #define ACPI_BUTTON_DEVICE_NAME_LID	"Lid Switch"
39 #define ACPI_BUTTON_TYPE_LID		0x05
40 
41 enum {
42 	ACPI_BUTTON_LID_INIT_IGNORE,
43 	ACPI_BUTTON_LID_INIT_OPEN,
44 	ACPI_BUTTON_LID_INIT_METHOD,
45 	ACPI_BUTTON_LID_INIT_DISABLED,
46 };
47 
48 static const char * const lid_init_state_str[] = {
49 	[ACPI_BUTTON_LID_INIT_IGNORE]		= "ignore",
50 	[ACPI_BUTTON_LID_INIT_OPEN]		= "open",
51 	[ACPI_BUTTON_LID_INIT_METHOD]		= "method",
52 	[ACPI_BUTTON_LID_INIT_DISABLED]		= "disabled",
53 };
54 
55 MODULE_AUTHOR("Paul Diefenbaugh");
56 MODULE_DESCRIPTION("ACPI Button Driver");
57 MODULE_LICENSE("GPL");
58 
59 static const struct acpi_device_id button_device_ids[] = {
60 	{ACPI_BUTTON_HID_LID,    0},
61 	{ACPI_BUTTON_HID_SLEEP,  0},
62 	{ACPI_BUTTON_HID_SLEEPF, 0},
63 	{ACPI_BUTTON_HID_POWER,  0},
64 	{ACPI_BUTTON_HID_POWERF, 0},
65 	{"", 0},
66 };
67 MODULE_DEVICE_TABLE(acpi, button_device_ids);
68 
69 /* Please keep this list sorted alphabetically by vendor and model */
70 static const struct dmi_system_id dmi_lid_quirks[] = {
71 	{
72 		/* GP-electronic T701, _LID method points to a floating GPIO */
73 		.matches = {
74 			DMI_MATCH(DMI_SYS_VENDOR, "Insyde"),
75 			DMI_MATCH(DMI_PRODUCT_NAME, "T701"),
76 			DMI_MATCH(DMI_BIOS_VERSION, "BYT70A.YNCHENG.WIN.007"),
77 		},
78 		.driver_data = (void *)(long)ACPI_BUTTON_LID_INIT_DISABLED,
79 	},
80 	{
81 		/*
82 		 * Medion Akoya E2215T, notification of the LID device only
83 		 * happens on close, not on open and _LID always returns closed.
84 		 */
85 		.matches = {
86 			DMI_MATCH(DMI_SYS_VENDOR, "MEDION"),
87 			DMI_MATCH(DMI_PRODUCT_NAME, "E2215T"),
88 		},
89 		.driver_data = (void *)(long)ACPI_BUTTON_LID_INIT_OPEN,
90 	},
91 	{
92 		/*
93 		 * Medion Akoya E2228T, notification of the LID device only
94 		 * happens on close, not on open and _LID always returns closed.
95 		 */
96 		.matches = {
97 			DMI_MATCH(DMI_SYS_VENDOR, "MEDION"),
98 			DMI_MATCH(DMI_PRODUCT_NAME, "E2228T"),
99 		},
100 		.driver_data = (void *)(long)ACPI_BUTTON_LID_INIT_OPEN,
101 	},
102 	{
103 		/*
104 		 * Razer Blade Stealth 13 late 2019, notification of the LID device
105 		 * only happens on close, not on open and _LID always returns closed.
106 		 */
107 		.matches = {
108 			DMI_MATCH(DMI_SYS_VENDOR, "Razer"),
109 			DMI_MATCH(DMI_PRODUCT_NAME, "Razer Blade Stealth 13 Late 2019"),
110 		},
111 		.driver_data = (void *)(long)ACPI_BUTTON_LID_INIT_OPEN,
112 	},
113 	{}
114 };
115 
116 static int acpi_button_add(struct acpi_device *device);
117 static int acpi_button_remove(struct acpi_device *device);
118 static void acpi_button_notify(struct acpi_device *device, u32 event);
119 
120 #ifdef CONFIG_PM_SLEEP
121 static int acpi_button_suspend(struct device *dev);
122 static int acpi_button_resume(struct device *dev);
123 #else
124 #define acpi_button_suspend NULL
125 #define acpi_button_resume NULL
126 #endif
127 static SIMPLE_DEV_PM_OPS(acpi_button_pm, acpi_button_suspend, acpi_button_resume);
128 
129 static struct acpi_driver acpi_button_driver = {
130 	.name = "button",
131 	.class = ACPI_BUTTON_CLASS,
132 	.ids = button_device_ids,
133 	.ops = {
134 		.add = acpi_button_add,
135 		.remove = acpi_button_remove,
136 		.notify = acpi_button_notify,
137 	},
138 	.drv.pm = &acpi_button_pm,
139 };
140 
141 struct acpi_button {
142 	unsigned int type;
143 	struct input_dev *input;
144 	char phys[32];			/* for input device */
145 	unsigned long pushed;
146 	int last_state;
147 	ktime_t last_time;
148 	bool suspended;
149 	bool lid_state_initialized;
150 };
151 
152 static struct acpi_device *lid_device;
153 static long lid_init_state = -1;
154 
155 static unsigned long lid_report_interval __read_mostly = 500;
156 module_param(lid_report_interval, ulong, 0644);
157 MODULE_PARM_DESC(lid_report_interval, "Interval (ms) between lid key events");
158 
159 /* FS Interface (/proc) */
160 static struct proc_dir_entry *acpi_button_dir;
161 static struct proc_dir_entry *acpi_lid_dir;
162 
163 static int acpi_lid_evaluate_state(struct acpi_device *device)
164 {
165 	unsigned long long lid_state;
166 	acpi_status status;
167 
168 	status = acpi_evaluate_integer(device->handle, "_LID", NULL, &lid_state);
169 	if (ACPI_FAILURE(status))
170 		return -ENODEV;
171 
172 	return lid_state ? 1 : 0;
173 }
174 
175 static int acpi_lid_notify_state(struct acpi_device *device, int state)
176 {
177 	struct acpi_button *button = acpi_driver_data(device);
178 	ktime_t next_report;
179 	bool do_update;
180 
181 	/*
182 	 * In lid_init_state=ignore mode, if user opens/closes lid
183 	 * frequently with "open" missing, and "last_time" is also updated
184 	 * frequently, "close" cannot be delivered to the userspace.
185 	 * So "last_time" is only updated after a timeout or an actual
186 	 * switch.
187 	 */
188 	if (lid_init_state != ACPI_BUTTON_LID_INIT_IGNORE ||
189 	    button->last_state != !!state)
190 		do_update = true;
191 	else
192 		do_update = false;
193 
194 	next_report = ktime_add(button->last_time,
195 				ms_to_ktime(lid_report_interval));
196 	if (button->last_state == !!state &&
197 	    ktime_after(ktime_get(), next_report)) {
198 		/* Complain the buggy firmware */
199 		pr_warn_once("The lid device is not compliant to SW_LID.\n");
200 
201 		/*
202 		 * Send the unreliable complement switch event:
203 		 *
204 		 * On most platforms, the lid device is reliable. However
205 		 * there are exceptions:
206 		 * 1. Platforms returning initial lid state as "close" by
207 		 *    default after booting/resuming:
208 		 *     https://bugzilla.kernel.org/show_bug.cgi?id=89211
209 		 *     https://bugzilla.kernel.org/show_bug.cgi?id=106151
210 		 * 2. Platforms never reporting "open" events:
211 		 *     https://bugzilla.kernel.org/show_bug.cgi?id=106941
212 		 * On these buggy platforms, the usage model of the ACPI
213 		 * lid device actually is:
214 		 * 1. The initial returning value of _LID may not be
215 		 *    reliable.
216 		 * 2. The open event may not be reliable.
217 		 * 3. The close event is reliable.
218 		 *
219 		 * But SW_LID is typed as input switch event, the input
220 		 * layer checks if the event is redundant. Hence if the
221 		 * state is not switched, the userspace cannot see this
222 		 * platform triggered reliable event. By inserting a
223 		 * complement switch event, it then is guaranteed that the
224 		 * platform triggered reliable one can always be seen by
225 		 * the userspace.
226 		 */
227 		if (lid_init_state == ACPI_BUTTON_LID_INIT_IGNORE) {
228 			do_update = true;
229 			/*
230 			 * Do generate complement switch event for "close"
231 			 * as "close" is reliable and wrong "open" won't
232 			 * trigger unexpected behaviors.
233 			 * Do not generate complement switch event for
234 			 * "open" as "open" is not reliable and wrong
235 			 * "close" will trigger unexpected behaviors.
236 			 */
237 			if (!state) {
238 				input_report_switch(button->input,
239 						    SW_LID, state);
240 				input_sync(button->input);
241 			}
242 		}
243 	}
244 	/* Send the platform triggered reliable event */
245 	if (do_update) {
246 		acpi_handle_debug(device->handle, "ACPI LID %s\n",
247 				  state ? "open" : "closed");
248 		input_report_switch(button->input, SW_LID, !state);
249 		input_sync(button->input);
250 		button->last_state = !!state;
251 		button->last_time = ktime_get();
252 	}
253 
254 	return 0;
255 }
256 
257 static int __maybe_unused acpi_button_state_seq_show(struct seq_file *seq,
258 						     void *offset)
259 {
260 	struct acpi_device *device = seq->private;
261 	int state;
262 
263 	state = acpi_lid_evaluate_state(device);
264 	seq_printf(seq, "state:      %s\n",
265 		   state < 0 ? "unsupported" : (state ? "open" : "closed"));
266 	return 0;
267 }
268 
269 static int acpi_button_add_fs(struct acpi_device *device)
270 {
271 	struct acpi_button *button = acpi_driver_data(device);
272 	struct proc_dir_entry *entry = NULL;
273 	int ret = 0;
274 
275 	/* procfs I/F for ACPI lid device only */
276 	if (button->type != ACPI_BUTTON_TYPE_LID)
277 		return 0;
278 
279 	if (acpi_button_dir || acpi_lid_dir) {
280 		pr_info("More than one Lid device found!\n");
281 		return -EEXIST;
282 	}
283 
284 	/* create /proc/acpi/button */
285 	acpi_button_dir = proc_mkdir(ACPI_BUTTON_CLASS, acpi_root_dir);
286 	if (!acpi_button_dir)
287 		return -ENODEV;
288 
289 	/* create /proc/acpi/button/lid */
290 	acpi_lid_dir = proc_mkdir(ACPI_BUTTON_SUBCLASS_LID, acpi_button_dir);
291 	if (!acpi_lid_dir) {
292 		ret = -ENODEV;
293 		goto remove_button_dir;
294 	}
295 
296 	/* create /proc/acpi/button/lid/LID/ */
297 	acpi_device_dir(device) = proc_mkdir(acpi_device_bid(device), acpi_lid_dir);
298 	if (!acpi_device_dir(device)) {
299 		ret = -ENODEV;
300 		goto remove_lid_dir;
301 	}
302 
303 	/* create /proc/acpi/button/lid/LID/state */
304 	entry = proc_create_single_data(ACPI_BUTTON_FILE_STATE, S_IRUGO,
305 			acpi_device_dir(device), acpi_button_state_seq_show,
306 			device);
307 	if (!entry) {
308 		ret = -ENODEV;
309 		goto remove_dev_dir;
310 	}
311 
312 done:
313 	return ret;
314 
315 remove_dev_dir:
316 	remove_proc_entry(acpi_device_bid(device),
317 			  acpi_lid_dir);
318 	acpi_device_dir(device) = NULL;
319 remove_lid_dir:
320 	remove_proc_entry(ACPI_BUTTON_SUBCLASS_LID, acpi_button_dir);
321 	acpi_lid_dir = NULL;
322 remove_button_dir:
323 	remove_proc_entry(ACPI_BUTTON_CLASS, acpi_root_dir);
324 	acpi_button_dir = NULL;
325 	goto done;
326 }
327 
328 static int acpi_button_remove_fs(struct acpi_device *device)
329 {
330 	struct acpi_button *button = acpi_driver_data(device);
331 
332 	if (button->type != ACPI_BUTTON_TYPE_LID)
333 		return 0;
334 
335 	remove_proc_entry(ACPI_BUTTON_FILE_STATE,
336 			  acpi_device_dir(device));
337 	remove_proc_entry(acpi_device_bid(device),
338 			  acpi_lid_dir);
339 	acpi_device_dir(device) = NULL;
340 	remove_proc_entry(ACPI_BUTTON_SUBCLASS_LID, acpi_button_dir);
341 	acpi_lid_dir = NULL;
342 	remove_proc_entry(ACPI_BUTTON_CLASS, acpi_root_dir);
343 	acpi_button_dir = NULL;
344 
345 	return 0;
346 }
347 
348 /* Driver Interface */
349 int acpi_lid_open(void)
350 {
351 	if (!lid_device)
352 		return -ENODEV;
353 
354 	return acpi_lid_evaluate_state(lid_device);
355 }
356 EXPORT_SYMBOL(acpi_lid_open);
357 
358 static int acpi_lid_update_state(struct acpi_device *device,
359 				 bool signal_wakeup)
360 {
361 	int state;
362 
363 	state = acpi_lid_evaluate_state(device);
364 	if (state < 0)
365 		return state;
366 
367 	if (state && signal_wakeup)
368 		acpi_pm_wakeup_event(&device->dev);
369 
370 	return acpi_lid_notify_state(device, state);
371 }
372 
373 static void acpi_lid_initialize_state(struct acpi_device *device)
374 {
375 	struct acpi_button *button = acpi_driver_data(device);
376 
377 	switch (lid_init_state) {
378 	case ACPI_BUTTON_LID_INIT_OPEN:
379 		(void)acpi_lid_notify_state(device, 1);
380 		break;
381 	case ACPI_BUTTON_LID_INIT_METHOD:
382 		(void)acpi_lid_update_state(device, false);
383 		break;
384 	case ACPI_BUTTON_LID_INIT_IGNORE:
385 	default:
386 		break;
387 	}
388 
389 	button->lid_state_initialized = true;
390 }
391 
392 static void acpi_button_notify(struct acpi_device *device, u32 event)
393 {
394 	struct acpi_button *button = acpi_driver_data(device);
395 	struct input_dev *input;
396 
397 	switch (event) {
398 	case ACPI_FIXED_HARDWARE_EVENT:
399 		event = ACPI_BUTTON_NOTIFY_STATUS;
400 		fallthrough;
401 	case ACPI_BUTTON_NOTIFY_STATUS:
402 		input = button->input;
403 		if (button->type == ACPI_BUTTON_TYPE_LID) {
404 			if (button->lid_state_initialized)
405 				acpi_lid_update_state(device, true);
406 		} else {
407 			int keycode;
408 
409 			acpi_pm_wakeup_event(&device->dev);
410 			if (button->suspended)
411 				break;
412 
413 			keycode = test_bit(KEY_SLEEP, input->keybit) ?
414 						KEY_SLEEP : KEY_POWER;
415 			input_report_key(input, keycode, 1);
416 			input_sync(input);
417 			input_report_key(input, keycode, 0);
418 			input_sync(input);
419 
420 			acpi_bus_generate_netlink_event(
421 					device->pnp.device_class,
422 					dev_name(&device->dev),
423 					event, ++button->pushed);
424 		}
425 		break;
426 	default:
427 		acpi_handle_debug(device->handle, "Unsupported event [0x%x]\n",
428 				  event);
429 		break;
430 	}
431 }
432 
433 #ifdef CONFIG_PM_SLEEP
434 static int acpi_button_suspend(struct device *dev)
435 {
436 	struct acpi_device *device = to_acpi_device(dev);
437 	struct acpi_button *button = acpi_driver_data(device);
438 
439 	button->suspended = true;
440 	return 0;
441 }
442 
443 static int acpi_button_resume(struct device *dev)
444 {
445 	struct acpi_device *device = to_acpi_device(dev);
446 	struct acpi_button *button = acpi_driver_data(device);
447 
448 	button->suspended = false;
449 	if (button->type == ACPI_BUTTON_TYPE_LID) {
450 		button->last_state = !!acpi_lid_evaluate_state(device);
451 		button->last_time = ktime_get();
452 		acpi_lid_initialize_state(device);
453 	}
454 	return 0;
455 }
456 #endif
457 
458 static int acpi_lid_input_open(struct input_dev *input)
459 {
460 	struct acpi_device *device = input_get_drvdata(input);
461 	struct acpi_button *button = acpi_driver_data(device);
462 
463 	button->last_state = !!acpi_lid_evaluate_state(device);
464 	button->last_time = ktime_get();
465 	acpi_lid_initialize_state(device);
466 
467 	return 0;
468 }
469 
470 static int acpi_button_add(struct acpi_device *device)
471 {
472 	struct acpi_button *button;
473 	struct input_dev *input;
474 	const char *hid = acpi_device_hid(device);
475 	char *name, *class;
476 	int error;
477 
478 	if (!strcmp(hid, ACPI_BUTTON_HID_LID) &&
479 	     lid_init_state == ACPI_BUTTON_LID_INIT_DISABLED)
480 		return -ENODEV;
481 
482 	button = kzalloc(sizeof(struct acpi_button), GFP_KERNEL);
483 	if (!button)
484 		return -ENOMEM;
485 
486 	device->driver_data = button;
487 
488 	button->input = input = input_allocate_device();
489 	if (!input) {
490 		error = -ENOMEM;
491 		goto err_free_button;
492 	}
493 
494 	name = acpi_device_name(device);
495 	class = acpi_device_class(device);
496 
497 	if (!strcmp(hid, ACPI_BUTTON_HID_POWER) ||
498 	    !strcmp(hid, ACPI_BUTTON_HID_POWERF)) {
499 		button->type = ACPI_BUTTON_TYPE_POWER;
500 		strcpy(name, ACPI_BUTTON_DEVICE_NAME_POWER);
501 		sprintf(class, "%s/%s",
502 			ACPI_BUTTON_CLASS, ACPI_BUTTON_SUBCLASS_POWER);
503 	} else if (!strcmp(hid, ACPI_BUTTON_HID_SLEEP) ||
504 		   !strcmp(hid, ACPI_BUTTON_HID_SLEEPF)) {
505 		button->type = ACPI_BUTTON_TYPE_SLEEP;
506 		strcpy(name, ACPI_BUTTON_DEVICE_NAME_SLEEP);
507 		sprintf(class, "%s/%s",
508 			ACPI_BUTTON_CLASS, ACPI_BUTTON_SUBCLASS_SLEEP);
509 	} else if (!strcmp(hid, ACPI_BUTTON_HID_LID)) {
510 		button->type = ACPI_BUTTON_TYPE_LID;
511 		strcpy(name, ACPI_BUTTON_DEVICE_NAME_LID);
512 		sprintf(class, "%s/%s",
513 			ACPI_BUTTON_CLASS, ACPI_BUTTON_SUBCLASS_LID);
514 		input->open = acpi_lid_input_open;
515 	} else {
516 		pr_info("Unsupported hid [%s]\n", hid);
517 		error = -ENODEV;
518 		goto err_free_input;
519 	}
520 
521 	error = acpi_button_add_fs(device);
522 	if (error)
523 		goto err_free_input;
524 
525 	snprintf(button->phys, sizeof(button->phys), "%s/button/input0", hid);
526 
527 	input->name = name;
528 	input->phys = button->phys;
529 	input->id.bustype = BUS_HOST;
530 	input->id.product = button->type;
531 	input->dev.parent = &device->dev;
532 
533 	switch (button->type) {
534 	case ACPI_BUTTON_TYPE_POWER:
535 		input_set_capability(input, EV_KEY, KEY_POWER);
536 		break;
537 
538 	case ACPI_BUTTON_TYPE_SLEEP:
539 		input_set_capability(input, EV_KEY, KEY_SLEEP);
540 		break;
541 
542 	case ACPI_BUTTON_TYPE_LID:
543 		input_set_capability(input, EV_SW, SW_LID);
544 		break;
545 	}
546 
547 	input_set_drvdata(input, device);
548 	error = input_register_device(input);
549 	if (error)
550 		goto err_remove_fs;
551 	if (button->type == ACPI_BUTTON_TYPE_LID) {
552 		/*
553 		 * This assumes there's only one lid device, or if there are
554 		 * more we only care about the last one...
555 		 */
556 		lid_device = device;
557 	}
558 
559 	device_init_wakeup(&device->dev, true);
560 	pr_info("%s [%s]\n", name, acpi_device_bid(device));
561 	return 0;
562 
563  err_remove_fs:
564 	acpi_button_remove_fs(device);
565  err_free_input:
566 	input_free_device(input);
567  err_free_button:
568 	kfree(button);
569 	return error;
570 }
571 
572 static int acpi_button_remove(struct acpi_device *device)
573 {
574 	struct acpi_button *button = acpi_driver_data(device);
575 
576 	acpi_button_remove_fs(device);
577 	input_unregister_device(button->input);
578 	kfree(button);
579 	return 0;
580 }
581 
582 static int param_set_lid_init_state(const char *val,
583 				    const struct kernel_param *kp)
584 {
585 	int i;
586 
587 	i = sysfs_match_string(lid_init_state_str, val);
588 	if (i < 0)
589 		return i;
590 
591 	lid_init_state = i;
592 	pr_info("Initial lid state set to '%s'\n", lid_init_state_str[i]);
593 	return 0;
594 }
595 
596 static int param_get_lid_init_state(char *buf, const struct kernel_param *kp)
597 {
598 	int i, c = 0;
599 
600 	for (i = 0; i < ARRAY_SIZE(lid_init_state_str); i++)
601 		if (i == lid_init_state)
602 			c += sprintf(buf + c, "[%s] ", lid_init_state_str[i]);
603 		else
604 			c += sprintf(buf + c, "%s ", lid_init_state_str[i]);
605 
606 	buf[c - 1] = '\n'; /* Replace the final space with a newline */
607 
608 	return c;
609 }
610 
611 module_param_call(lid_init_state,
612 		  param_set_lid_init_state, param_get_lid_init_state,
613 		  NULL, 0644);
614 MODULE_PARM_DESC(lid_init_state, "Behavior for reporting LID initial state");
615 
616 static int acpi_button_register_driver(struct acpi_driver *driver)
617 {
618 	const struct dmi_system_id *dmi_id;
619 
620 	if (lid_init_state == -1) {
621 		dmi_id = dmi_first_match(dmi_lid_quirks);
622 		if (dmi_id)
623 			lid_init_state = (long)dmi_id->driver_data;
624 		else
625 			lid_init_state = ACPI_BUTTON_LID_INIT_METHOD;
626 	}
627 
628 	/*
629 	 * Modules such as nouveau.ko and i915.ko have a link time dependency
630 	 * on acpi_lid_open(), and would therefore not be loadable on ACPI
631 	 * capable kernels booted in non-ACPI mode if the return value of
632 	 * acpi_bus_register_driver() is returned from here with ACPI disabled
633 	 * when this driver is built as a module.
634 	 */
635 	if (acpi_disabled)
636 		return 0;
637 
638 	return acpi_bus_register_driver(driver);
639 }
640 
641 static void acpi_button_unregister_driver(struct acpi_driver *driver)
642 {
643 	if (!acpi_disabled)
644 		acpi_bus_unregister_driver(driver);
645 }
646 
647 module_driver(acpi_button_driver, acpi_button_register_driver,
648 	       acpi_button_unregister_driver);
649