xref: /openbmc/linux/drivers/acpi/button.c (revision a701d28e)
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 PREFIX "ACPI: "
25 
26 #define ACPI_BUTTON_CLASS		"button"
27 #define ACPI_BUTTON_FILE_STATE		"state"
28 #define ACPI_BUTTON_TYPE_UNKNOWN	0x00
29 #define ACPI_BUTTON_NOTIFY_STATUS	0x80
30 
31 #define ACPI_BUTTON_SUBCLASS_POWER	"power"
32 #define ACPI_BUTTON_DEVICE_NAME_POWER	"Power Button"
33 #define ACPI_BUTTON_TYPE_POWER		0x01
34 
35 #define ACPI_BUTTON_SUBCLASS_SLEEP	"sleep"
36 #define ACPI_BUTTON_DEVICE_NAME_SLEEP	"Sleep Button"
37 #define ACPI_BUTTON_TYPE_SLEEP		0x03
38 
39 #define ACPI_BUTTON_SUBCLASS_LID	"lid"
40 #define ACPI_BUTTON_DEVICE_NAME_LID	"Lid Switch"
41 #define ACPI_BUTTON_TYPE_LID		0x05
42 
43 enum {
44 	ACPI_BUTTON_LID_INIT_IGNORE,
45 	ACPI_BUTTON_LID_INIT_OPEN,
46 	ACPI_BUTTON_LID_INIT_METHOD,
47 	ACPI_BUTTON_LID_INIT_DISABLED,
48 };
49 
50 static const char * const lid_init_state_str[] = {
51 	[ACPI_BUTTON_LID_INIT_IGNORE]		= "ignore",
52 	[ACPI_BUTTON_LID_INIT_OPEN]		= "open",
53 	[ACPI_BUTTON_LID_INIT_METHOD]		= "method",
54 	[ACPI_BUTTON_LID_INIT_DISABLED]		= "disabled",
55 };
56 
57 #define _COMPONENT		ACPI_BUTTON_COMPONENT
58 ACPI_MODULE_NAME("button");
59 
60 MODULE_AUTHOR("Paul Diefenbaugh");
61 MODULE_DESCRIPTION("ACPI Button Driver");
62 MODULE_LICENSE("GPL");
63 
64 static const struct acpi_device_id button_device_ids[] = {
65 	{ACPI_BUTTON_HID_LID,    0},
66 	{ACPI_BUTTON_HID_SLEEP,  0},
67 	{ACPI_BUTTON_HID_SLEEPF, 0},
68 	{ACPI_BUTTON_HID_POWER,  0},
69 	{ACPI_BUTTON_HID_POWERF, 0},
70 	{"", 0},
71 };
72 MODULE_DEVICE_TABLE(acpi, button_device_ids);
73 
74 /* Please keep this list sorted alphabetically by vendor and model */
75 static const struct dmi_system_id dmi_lid_quirks[] = {
76 	{
77 		/* GP-electronic T701, _LID method points to a floating GPIO */
78 		.matches = {
79 			DMI_MATCH(DMI_SYS_VENDOR, "Insyde"),
80 			DMI_MATCH(DMI_PRODUCT_NAME, "T701"),
81 			DMI_MATCH(DMI_BIOS_VERSION, "BYT70A.YNCHENG.WIN.007"),
82 		},
83 		.driver_data = (void *)(long)ACPI_BUTTON_LID_INIT_DISABLED,
84 	},
85 	{
86 		/*
87 		 * Medion Akoya E2215T, notification of the LID device only
88 		 * happens on close, not on open and _LID always returns closed.
89 		 */
90 		.matches = {
91 			DMI_MATCH(DMI_SYS_VENDOR, "MEDION"),
92 			DMI_MATCH(DMI_PRODUCT_NAME, "E2215T MD60198"),
93 		},
94 		.driver_data = (void *)(long)ACPI_BUTTON_LID_INIT_OPEN,
95 	},
96 	{
97 		/*
98 		 * Razer Blade Stealth 13 late 2019, notification of the LID device
99 		 * only happens on close, not on open and _LID always returns closed.
100 		 */
101 		.matches = {
102 			DMI_MATCH(DMI_SYS_VENDOR, "Razer"),
103 			DMI_MATCH(DMI_PRODUCT_NAME, "Razer Blade Stealth 13 Late 2019"),
104 		},
105 		.driver_data = (void *)(long)ACPI_BUTTON_LID_INIT_OPEN,
106 	},
107 	{}
108 };
109 
110 static int acpi_button_add(struct acpi_device *device);
111 static int acpi_button_remove(struct acpi_device *device);
112 static void acpi_button_notify(struct acpi_device *device, u32 event);
113 
114 #ifdef CONFIG_PM_SLEEP
115 static int acpi_button_suspend(struct device *dev);
116 static int acpi_button_resume(struct device *dev);
117 #else
118 #define acpi_button_suspend NULL
119 #define acpi_button_resume NULL
120 #endif
121 static SIMPLE_DEV_PM_OPS(acpi_button_pm, acpi_button_suspend, acpi_button_resume);
122 
123 static struct acpi_driver acpi_button_driver = {
124 	.name = "button",
125 	.class = ACPI_BUTTON_CLASS,
126 	.ids = button_device_ids,
127 	.ops = {
128 		.add = acpi_button_add,
129 		.remove = acpi_button_remove,
130 		.notify = acpi_button_notify,
131 	},
132 	.drv.pm = &acpi_button_pm,
133 };
134 
135 struct acpi_button {
136 	unsigned int type;
137 	struct input_dev *input;
138 	char phys[32];			/* for input device */
139 	unsigned long pushed;
140 	int last_state;
141 	ktime_t last_time;
142 	bool suspended;
143 	bool lid_state_initialized;
144 };
145 
146 static struct acpi_device *lid_device;
147 static long lid_init_state = -1;
148 
149 static unsigned long lid_report_interval __read_mostly = 500;
150 module_param(lid_report_interval, ulong, 0644);
151 MODULE_PARM_DESC(lid_report_interval, "Interval (ms) between lid key events");
152 
153 /* --------------------------------------------------------------------------
154                               FS Interface (/proc)
155    -------------------------------------------------------------------------- */
156 
157 static struct proc_dir_entry *acpi_button_dir;
158 static struct proc_dir_entry *acpi_lid_dir;
159 
160 static int acpi_lid_evaluate_state(struct acpi_device *device)
161 {
162 	unsigned long long lid_state;
163 	acpi_status status;
164 
165 	status = acpi_evaluate_integer(device->handle, "_LID", NULL, &lid_state);
166 	if (ACPI_FAILURE(status))
167 		return -ENODEV;
168 
169 	return lid_state ? 1 : 0;
170 }
171 
172 static int acpi_lid_notify_state(struct acpi_device *device, int state)
173 {
174 	struct acpi_button *button = acpi_driver_data(device);
175 	ktime_t next_report;
176 	bool do_update;
177 
178 	/*
179 	 * In lid_init_state=ignore mode, if user opens/closes lid
180 	 * frequently with "open" missing, and "last_time" is also updated
181 	 * frequently, "close" cannot be delivered to the userspace.
182 	 * So "last_time" is only updated after a timeout or an actual
183 	 * switch.
184 	 */
185 	if (lid_init_state != ACPI_BUTTON_LID_INIT_IGNORE ||
186 	    button->last_state != !!state)
187 		do_update = true;
188 	else
189 		do_update = false;
190 
191 	next_report = ktime_add(button->last_time,
192 				ms_to_ktime(lid_report_interval));
193 	if (button->last_state == !!state &&
194 	    ktime_after(ktime_get(), next_report)) {
195 		/* Complain the buggy firmware */
196 		pr_warn_once("The lid device is not compliant to SW_LID.\n");
197 
198 		/*
199 		 * Send the unreliable complement switch event:
200 		 *
201 		 * On most platforms, the lid device is reliable. However
202 		 * there are exceptions:
203 		 * 1. Platforms returning initial lid state as "close" by
204 		 *    default after booting/resuming:
205 		 *     https://bugzilla.kernel.org/show_bug.cgi?id=89211
206 		 *     https://bugzilla.kernel.org/show_bug.cgi?id=106151
207 		 * 2. Platforms never reporting "open" events:
208 		 *     https://bugzilla.kernel.org/show_bug.cgi?id=106941
209 		 * On these buggy platforms, the usage model of the ACPI
210 		 * lid device actually is:
211 		 * 1. The initial returning value of _LID may not be
212 		 *    reliable.
213 		 * 2. The open event may not be reliable.
214 		 * 3. The close event is reliable.
215 		 *
216 		 * But SW_LID is typed as input switch event, the input
217 		 * layer checks if the event is redundant. Hence if the
218 		 * state is not switched, the userspace cannot see this
219 		 * platform triggered reliable event. By inserting a
220 		 * complement switch event, it then is guaranteed that the
221 		 * platform triggered reliable one can always be seen by
222 		 * the userspace.
223 		 */
224 		if (lid_init_state == ACPI_BUTTON_LID_INIT_IGNORE) {
225 			do_update = true;
226 			/*
227 			 * Do generate complement switch event for "close"
228 			 * as "close" is reliable and wrong "open" won't
229 			 * trigger unexpected behaviors.
230 			 * Do not generate complement switch event for
231 			 * "open" as "open" is not reliable and wrong
232 			 * "close" will trigger unexpected behaviors.
233 			 */
234 			if (!state) {
235 				input_report_switch(button->input,
236 						    SW_LID, state);
237 				input_sync(button->input);
238 			}
239 		}
240 	}
241 	/* Send the platform triggered reliable event */
242 	if (do_update) {
243 		acpi_handle_debug(device->handle, "ACPI LID %s\n",
244 				  state ? "open" : "closed");
245 		input_report_switch(button->input, SW_LID, !state);
246 		input_sync(button->input);
247 		button->last_state = !!state;
248 		button->last_time = ktime_get();
249 	}
250 
251 	return 0;
252 }
253 
254 static int __maybe_unused acpi_button_state_seq_show(struct seq_file *seq,
255 						     void *offset)
256 {
257 	struct acpi_device *device = seq->private;
258 	int state;
259 
260 	state = acpi_lid_evaluate_state(device);
261 	seq_printf(seq, "state:      %s\n",
262 		   state < 0 ? "unsupported" : (state ? "open" : "closed"));
263 	return 0;
264 }
265 
266 static int acpi_button_add_fs(struct acpi_device *device)
267 {
268 	struct acpi_button *button = acpi_driver_data(device);
269 	struct proc_dir_entry *entry = NULL;
270 	int ret = 0;
271 
272 	/* procfs I/F for ACPI lid device only */
273 	if (button->type != ACPI_BUTTON_TYPE_LID)
274 		return 0;
275 
276 	if (acpi_button_dir || acpi_lid_dir) {
277 		printk(KERN_ERR PREFIX "More than one Lid device found!\n");
278 		return -EEXIST;
279 	}
280 
281 	/* create /proc/acpi/button */
282 	acpi_button_dir = proc_mkdir(ACPI_BUTTON_CLASS, acpi_root_dir);
283 	if (!acpi_button_dir)
284 		return -ENODEV;
285 
286 	/* create /proc/acpi/button/lid */
287 	acpi_lid_dir = proc_mkdir(ACPI_BUTTON_SUBCLASS_LID, acpi_button_dir);
288 	if (!acpi_lid_dir) {
289 		ret = -ENODEV;
290 		goto remove_button_dir;
291 	}
292 
293 	/* create /proc/acpi/button/lid/LID/ */
294 	acpi_device_dir(device) = proc_mkdir(acpi_device_bid(device), acpi_lid_dir);
295 	if (!acpi_device_dir(device)) {
296 		ret = -ENODEV;
297 		goto remove_lid_dir;
298 	}
299 
300 	/* create /proc/acpi/button/lid/LID/state */
301 	entry = proc_create_single_data(ACPI_BUTTON_FILE_STATE, S_IRUGO,
302 			acpi_device_dir(device), acpi_button_state_seq_show,
303 			device);
304 	if (!entry) {
305 		ret = -ENODEV;
306 		goto remove_dev_dir;
307 	}
308 
309 done:
310 	return ret;
311 
312 remove_dev_dir:
313 	remove_proc_entry(acpi_device_bid(device),
314 			  acpi_lid_dir);
315 	acpi_device_dir(device) = NULL;
316 remove_lid_dir:
317 	remove_proc_entry(ACPI_BUTTON_SUBCLASS_LID, acpi_button_dir);
318 	acpi_lid_dir = NULL;
319 remove_button_dir:
320 	remove_proc_entry(ACPI_BUTTON_CLASS, acpi_root_dir);
321 	acpi_button_dir = NULL;
322 	goto done;
323 }
324 
325 static int acpi_button_remove_fs(struct acpi_device *device)
326 {
327 	struct acpi_button *button = acpi_driver_data(device);
328 
329 	if (button->type != ACPI_BUTTON_TYPE_LID)
330 		return 0;
331 
332 	remove_proc_entry(ACPI_BUTTON_FILE_STATE,
333 			  acpi_device_dir(device));
334 	remove_proc_entry(acpi_device_bid(device),
335 			  acpi_lid_dir);
336 	acpi_device_dir(device) = NULL;
337 	remove_proc_entry(ACPI_BUTTON_SUBCLASS_LID, acpi_button_dir);
338 	acpi_lid_dir = NULL;
339 	remove_proc_entry(ACPI_BUTTON_CLASS, acpi_root_dir);
340 	acpi_button_dir = NULL;
341 
342 	return 0;
343 }
344 
345 /* --------------------------------------------------------------------------
346                                 Driver Interface
347    -------------------------------------------------------------------------- */
348 int acpi_lid_open(void)
349 {
350 	if (!lid_device)
351 		return -ENODEV;
352 
353 	return acpi_lid_evaluate_state(lid_device);
354 }
355 EXPORT_SYMBOL(acpi_lid_open);
356 
357 static int acpi_lid_update_state(struct acpi_device *device,
358 				 bool signal_wakeup)
359 {
360 	int state;
361 
362 	state = acpi_lid_evaluate_state(device);
363 	if (state < 0)
364 		return state;
365 
366 	if (state && signal_wakeup)
367 		acpi_pm_wakeup_event(&device->dev);
368 
369 	return acpi_lid_notify_state(device, state);
370 }
371 
372 static void acpi_lid_initialize_state(struct acpi_device *device)
373 {
374 	struct acpi_button *button = acpi_driver_data(device);
375 
376 	switch (lid_init_state) {
377 	case ACPI_BUTTON_LID_INIT_OPEN:
378 		(void)acpi_lid_notify_state(device, 1);
379 		break;
380 	case ACPI_BUTTON_LID_INIT_METHOD:
381 		(void)acpi_lid_update_state(device, false);
382 		break;
383 	case ACPI_BUTTON_LID_INIT_IGNORE:
384 	default:
385 		break;
386 	}
387 
388 	button->lid_state_initialized = true;
389 }
390 
391 static void acpi_button_notify(struct acpi_device *device, u32 event)
392 {
393 	struct acpi_button *button = acpi_driver_data(device);
394 	struct input_dev *input;
395 
396 	switch (event) {
397 	case ACPI_FIXED_HARDWARE_EVENT:
398 		event = ACPI_BUTTON_NOTIFY_STATUS;
399 		fallthrough;
400 	case ACPI_BUTTON_NOTIFY_STATUS:
401 		input = button->input;
402 		if (button->type == ACPI_BUTTON_TYPE_LID) {
403 			if (button->lid_state_initialized)
404 				acpi_lid_update_state(device, true);
405 		} else {
406 			int keycode;
407 
408 			acpi_pm_wakeup_event(&device->dev);
409 			if (button->suspended)
410 				break;
411 
412 			keycode = test_bit(KEY_SLEEP, input->keybit) ?
413 						KEY_SLEEP : KEY_POWER;
414 			input_report_key(input, keycode, 1);
415 			input_sync(input);
416 			input_report_key(input, keycode, 0);
417 			input_sync(input);
418 
419 			acpi_bus_generate_netlink_event(
420 					device->pnp.device_class,
421 					dev_name(&device->dev),
422 					event, ++button->pushed);
423 		}
424 		break;
425 	default:
426 		ACPI_DEBUG_PRINT((ACPI_DB_INFO,
427 				  "Unsupported event [0x%x]\n", event));
428 		break;
429 	}
430 }
431 
432 #ifdef CONFIG_PM_SLEEP
433 static int acpi_button_suspend(struct device *dev)
434 {
435 	struct acpi_device *device = to_acpi_device(dev);
436 	struct acpi_button *button = acpi_driver_data(device);
437 
438 	button->suspended = true;
439 	return 0;
440 }
441 
442 static int acpi_button_resume(struct device *dev)
443 {
444 	struct acpi_device *device = to_acpi_device(dev);
445 	struct acpi_button *button = acpi_driver_data(device);
446 
447 	button->suspended = false;
448 	if (button->type == ACPI_BUTTON_TYPE_LID) {
449 		button->last_state = !!acpi_lid_evaluate_state(device);
450 		button->last_time = ktime_get();
451 		acpi_lid_initialize_state(device);
452 	}
453 	return 0;
454 }
455 #endif
456 
457 static int acpi_lid_input_open(struct input_dev *input)
458 {
459 	struct acpi_device *device = input_get_drvdata(input);
460 	struct acpi_button *button = acpi_driver_data(device);
461 
462 	button->last_state = !!acpi_lid_evaluate_state(device);
463 	button->last_time = ktime_get();
464 	acpi_lid_initialize_state(device);
465 
466 	return 0;
467 }
468 
469 static int acpi_button_add(struct acpi_device *device)
470 {
471 	struct acpi_button *button;
472 	struct input_dev *input;
473 	const char *hid = acpi_device_hid(device);
474 	char *name, *class;
475 	int error;
476 
477 	if (!strcmp(hid, ACPI_BUTTON_HID_LID) &&
478 	     lid_init_state == ACPI_BUTTON_LID_INIT_DISABLED)
479 		return -ENODEV;
480 
481 	button = kzalloc(sizeof(struct acpi_button), GFP_KERNEL);
482 	if (!button)
483 		return -ENOMEM;
484 
485 	device->driver_data = button;
486 
487 	button->input = input = input_allocate_device();
488 	if (!input) {
489 		error = -ENOMEM;
490 		goto err_free_button;
491 	}
492 
493 	name = acpi_device_name(device);
494 	class = acpi_device_class(device);
495 
496 	if (!strcmp(hid, ACPI_BUTTON_HID_POWER) ||
497 	    !strcmp(hid, ACPI_BUTTON_HID_POWERF)) {
498 		button->type = ACPI_BUTTON_TYPE_POWER;
499 		strcpy(name, ACPI_BUTTON_DEVICE_NAME_POWER);
500 		sprintf(class, "%s/%s",
501 			ACPI_BUTTON_CLASS, ACPI_BUTTON_SUBCLASS_POWER);
502 	} else if (!strcmp(hid, ACPI_BUTTON_HID_SLEEP) ||
503 		   !strcmp(hid, ACPI_BUTTON_HID_SLEEPF)) {
504 		button->type = ACPI_BUTTON_TYPE_SLEEP;
505 		strcpy(name, ACPI_BUTTON_DEVICE_NAME_SLEEP);
506 		sprintf(class, "%s/%s",
507 			ACPI_BUTTON_CLASS, ACPI_BUTTON_SUBCLASS_SLEEP);
508 	} else if (!strcmp(hid, ACPI_BUTTON_HID_LID)) {
509 		button->type = ACPI_BUTTON_TYPE_LID;
510 		strcpy(name, ACPI_BUTTON_DEVICE_NAME_LID);
511 		sprintf(class, "%s/%s",
512 			ACPI_BUTTON_CLASS, ACPI_BUTTON_SUBCLASS_LID);
513 		input->open = acpi_lid_input_open;
514 	} else {
515 		printk(KERN_ERR PREFIX "Unsupported hid [%s]\n", hid);
516 		error = -ENODEV;
517 		goto err_free_input;
518 	}
519 
520 	error = acpi_button_add_fs(device);
521 	if (error)
522 		goto err_free_input;
523 
524 	snprintf(button->phys, sizeof(button->phys), "%s/button/input0", hid);
525 
526 	input->name = name;
527 	input->phys = button->phys;
528 	input->id.bustype = BUS_HOST;
529 	input->id.product = button->type;
530 	input->dev.parent = &device->dev;
531 
532 	switch (button->type) {
533 	case ACPI_BUTTON_TYPE_POWER:
534 		input_set_capability(input, EV_KEY, KEY_POWER);
535 		break;
536 
537 	case ACPI_BUTTON_TYPE_SLEEP:
538 		input_set_capability(input, EV_KEY, KEY_SLEEP);
539 		break;
540 
541 	case ACPI_BUTTON_TYPE_LID:
542 		input_set_capability(input, EV_SW, SW_LID);
543 		break;
544 	}
545 
546 	input_set_drvdata(input, device);
547 	error = input_register_device(input);
548 	if (error)
549 		goto err_remove_fs;
550 	if (button->type == ACPI_BUTTON_TYPE_LID) {
551 		/*
552 		 * This assumes there's only one lid device, or if there are
553 		 * more we only care about the last one...
554 		 */
555 		lid_device = device;
556 	}
557 
558 	device_init_wakeup(&device->dev, true);
559 	printk(KERN_INFO PREFIX "%s [%s]\n", name, acpi_device_bid(device));
560 	return 0;
561 
562  err_remove_fs:
563 	acpi_button_remove_fs(device);
564  err_free_input:
565 	input_free_device(input);
566  err_free_button:
567 	kfree(button);
568 	return error;
569 }
570 
571 static int acpi_button_remove(struct acpi_device *device)
572 {
573 	struct acpi_button *button = acpi_driver_data(device);
574 
575 	acpi_button_remove_fs(device);
576 	input_unregister_device(button->input);
577 	kfree(button);
578 	return 0;
579 }
580 
581 static int param_set_lid_init_state(const char *val,
582 				    const struct kernel_param *kp)
583 {
584 	int i;
585 
586 	i = sysfs_match_string(lid_init_state_str, val);
587 	if (i < 0)
588 		return i;
589 
590 	lid_init_state = i;
591 	pr_info("Initial lid state set to '%s'\n", lid_init_state_str[i]);
592 	return 0;
593 }
594 
595 static int param_get_lid_init_state(char *buf, const struct kernel_param *kp)
596 {
597 	int i, c = 0;
598 
599 	for (i = 0; i < ARRAY_SIZE(lid_init_state_str); i++)
600 		if (i == lid_init_state)
601 			c += sprintf(buf + c, "[%s] ", lid_init_state_str[i]);
602 		else
603 			c += sprintf(buf + c, "%s ", lid_init_state_str[i]);
604 
605 	buf[c - 1] = '\n'; /* Replace the final space with a newline */
606 
607 	return c;
608 }
609 
610 module_param_call(lid_init_state,
611 		  param_set_lid_init_state, param_get_lid_init_state,
612 		  NULL, 0644);
613 MODULE_PARM_DESC(lid_init_state, "Behavior for reporting LID initial state");
614 
615 static int acpi_button_register_driver(struct acpi_driver *driver)
616 {
617 	const struct dmi_system_id *dmi_id;
618 
619 	if (lid_init_state == -1) {
620 		dmi_id = dmi_first_match(dmi_lid_quirks);
621 		if (dmi_id)
622 			lid_init_state = (long)dmi_id->driver_data;
623 		else
624 			lid_init_state = ACPI_BUTTON_LID_INIT_METHOD;
625 	}
626 
627 	/*
628 	 * Modules such as nouveau.ko and i915.ko have a link time dependency
629 	 * on acpi_lid_open(), and would therefore not be loadable on ACPI
630 	 * capable kernels booted in non-ACPI mode if the return value of
631 	 * acpi_bus_register_driver() is returned from here with ACPI disabled
632 	 * when this driver is built as a module.
633 	 */
634 	if (acpi_disabled)
635 		return 0;
636 
637 	return acpi_bus_register_driver(driver);
638 }
639 
640 static void acpi_button_unregister_driver(struct acpi_driver *driver)
641 {
642 	if (!acpi_disabled)
643 		acpi_bus_unregister_driver(driver);
644 }
645 
646 module_driver(acpi_button_driver, acpi_button_register_driver,
647 	       acpi_button_unregister_driver);
648