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_INFO "info"
28 #define ACPI_BUTTON_FILE_STATE "state"
29 #define ACPI_BUTTON_TYPE_UNKNOWN 0x00
30 #define ACPI_BUTTON_NOTIFY_STATUS 0x80
31
32 #define ACPI_BUTTON_SUBCLASS_POWER "power"
33 #define ACPI_BUTTON_HID_POWER "PNP0C0C"
34 #define ACPI_BUTTON_DEVICE_NAME_POWER "Power Button"
35 #define ACPI_BUTTON_TYPE_POWER 0x01
36
37 #define ACPI_BUTTON_SUBCLASS_SLEEP "sleep"
38 #define ACPI_BUTTON_HID_SLEEP "PNP0C0E"
39 #define ACPI_BUTTON_DEVICE_NAME_SLEEP "Sleep Button"
40 #define ACPI_BUTTON_TYPE_SLEEP 0x03
41
42 #define ACPI_BUTTON_SUBCLASS_LID "lid"
43 #define ACPI_BUTTON_HID_LID "PNP0C0D"
44 #define ACPI_BUTTON_DEVICE_NAME_LID "Lid Switch"
45 #define ACPI_BUTTON_TYPE_LID 0x05
46
47 #define ACPI_BUTTON_LID_INIT_IGNORE 0x00
48 #define ACPI_BUTTON_LID_INIT_OPEN 0x01
49 #define ACPI_BUTTON_LID_INIT_METHOD 0x02
50
51 #define _COMPONENT ACPI_BUTTON_COMPONENT
52 ACPI_MODULE_NAME("button");
53
54 MODULE_AUTHOR("Paul Diefenbaugh");
55 MODULE_DESCRIPTION("ACPI Button Driver");
56 MODULE_LICENSE("GPL");
57
58 static const struct acpi_device_id button_device_ids[] = {
59 {ACPI_BUTTON_HID_LID, 0},
60 {ACPI_BUTTON_HID_SLEEP, 0},
61 {ACPI_BUTTON_HID_SLEEPF, 0},
62 {ACPI_BUTTON_HID_POWER, 0},
63 {ACPI_BUTTON_HID_POWERF, 0},
64 {"", 0},
65 };
66 MODULE_DEVICE_TABLE(acpi, button_device_ids);
67
68 /*
69 * Some devices which don't even have a lid in anyway have a broken _LID
70 * method (e.g. pointing to a floating gpio pin) causing spurious LID events.
71 */
72 static const struct dmi_system_id lid_blacklst[] = {
73 {
74 /* GP-electronic T701 */
75 .matches = {
76 DMI_MATCH(DMI_SYS_VENDOR, "Insyde"),
77 DMI_MATCH(DMI_PRODUCT_NAME, "T701"),
78 DMI_MATCH(DMI_BIOS_VERSION, "BYT70A.YNCHENG.WIN.007"),
79 },
80 },
81 {
82 /*
83 * Medion Akoya E2215T, notification of the LID device only
84 * happens on close, not on open and _LID always returns closed.
85 */
86 .matches = {
87 DMI_MATCH(DMI_SYS_VENDOR, "MEDION"),
88 DMI_MATCH(DMI_PRODUCT_NAME, "E2215T MD60198"),
89 },
90 .driver_data = (void *)(long)ACPI_BUTTON_LID_INIT_OPEN,
91 },
92 {}
93 };
94
95 static int acpi_button_add(struct acpi_device *device);
96 static int acpi_button_remove(struct acpi_device *device);
97 static void acpi_button_notify(struct acpi_device *device, u32 event);
98
99 #ifdef CONFIG_PM_SLEEP
100 static int acpi_button_suspend(struct device *dev);
101 static int acpi_button_resume(struct device *dev);
102 #else
103 #define acpi_button_suspend NULL
104 #define acpi_button_resume NULL
105 #endif
106 static SIMPLE_DEV_PM_OPS(acpi_button_pm, acpi_button_suspend, acpi_button_resume);
107
108 static struct acpi_driver acpi_button_driver = {
109 .name = "button",
110 .class = ACPI_BUTTON_CLASS,
111 .ids = button_device_ids,
112 .ops = {
113 .add = acpi_button_add,
114 .remove = acpi_button_remove,
115 .notify = acpi_button_notify,
116 },
117 .drv.pm = &acpi_button_pm,
118 };
119
120 struct acpi_button {
121 unsigned int type;
122 struct input_dev *input;
123 char phys[32]; /* for input device */
124 unsigned long pushed;
125 int last_state;
126 ktime_t last_time;
127 bool suspended;
128 };
129
130 static BLOCKING_NOTIFIER_HEAD(acpi_lid_notifier);
131 static struct acpi_device *lid_device;
132 static u8 lid_init_state = ACPI_BUTTON_LID_INIT_METHOD;
133
134 static unsigned long lid_report_interval __read_mostly = 500;
135 module_param(lid_report_interval, ulong, 0644);
136 MODULE_PARM_DESC(lid_report_interval, "Interval (ms) between lid key events");
137
138 /* --------------------------------------------------------------------------
139 FS Interface (/proc)
140 -------------------------------------------------------------------------- */
141
142 static struct proc_dir_entry *acpi_button_dir;
143 static struct proc_dir_entry *acpi_lid_dir;
144
acpi_lid_evaluate_state(struct acpi_device * device)145 static int acpi_lid_evaluate_state(struct acpi_device *device)
146 {
147 unsigned long long lid_state;
148 acpi_status status;
149
150 status = acpi_evaluate_integer(device->handle, "_LID", NULL, &lid_state);
151 if (ACPI_FAILURE(status))
152 return -ENODEV;
153
154 return lid_state ? 1 : 0;
155 }
156
acpi_lid_notify_state(struct acpi_device * device,int state)157 static int acpi_lid_notify_state(struct acpi_device *device, int state)
158 {
159 struct acpi_button *button = acpi_driver_data(device);
160 int ret;
161 ktime_t next_report;
162 bool do_update;
163
164 /*
165 * In lid_init_state=ignore mode, if user opens/closes lid
166 * frequently with "open" missing, and "last_time" is also updated
167 * frequently, "close" cannot be delivered to the userspace.
168 * So "last_time" is only updated after a timeout or an actual
169 * switch.
170 */
171 if (lid_init_state != ACPI_BUTTON_LID_INIT_IGNORE ||
172 button->last_state != !!state)
173 do_update = true;
174 else
175 do_update = false;
176
177 next_report = ktime_add(button->last_time,
178 ms_to_ktime(lid_report_interval));
179 if (button->last_state == !!state &&
180 ktime_after(ktime_get(), next_report)) {
181 /* Complain the buggy firmware */
182 pr_warn_once("The lid device is not compliant to SW_LID.\n");
183
184 /*
185 * Send the unreliable complement switch event:
186 *
187 * On most platforms, the lid device is reliable. However
188 * there are exceptions:
189 * 1. Platforms returning initial lid state as "close" by
190 * default after booting/resuming:
191 * https://bugzilla.kernel.org/show_bug.cgi?id=89211
192 * https://bugzilla.kernel.org/show_bug.cgi?id=106151
193 * 2. Platforms never reporting "open" events:
194 * https://bugzilla.kernel.org/show_bug.cgi?id=106941
195 * On these buggy platforms, the usage model of the ACPI
196 * lid device actually is:
197 * 1. The initial returning value of _LID may not be
198 * reliable.
199 * 2. The open event may not be reliable.
200 * 3. The close event is reliable.
201 *
202 * But SW_LID is typed as input switch event, the input
203 * layer checks if the event is redundant. Hence if the
204 * state is not switched, the userspace cannot see this
205 * platform triggered reliable event. By inserting a
206 * complement switch event, it then is guaranteed that the
207 * platform triggered reliable one can always be seen by
208 * the userspace.
209 */
210 if (lid_init_state == ACPI_BUTTON_LID_INIT_IGNORE) {
211 do_update = true;
212 /*
213 * Do generate complement switch event for "close"
214 * as "close" is reliable and wrong "open" won't
215 * trigger unexpected behaviors.
216 * Do not generate complement switch event for
217 * "open" as "open" is not reliable and wrong
218 * "close" will trigger unexpected behaviors.
219 */
220 if (!state) {
221 input_report_switch(button->input,
222 SW_LID, state);
223 input_sync(button->input);
224 }
225 }
226 }
227 /* Send the platform triggered reliable event */
228 if (do_update) {
229 acpi_handle_debug(device->handle, "ACPI LID %s\n",
230 state ? "open" : "closed");
231 input_report_switch(button->input, SW_LID, !state);
232 input_sync(button->input);
233 button->last_state = !!state;
234 button->last_time = ktime_get();
235 }
236
237 ret = blocking_notifier_call_chain(&acpi_lid_notifier, state, device);
238 if (ret == NOTIFY_DONE)
239 ret = blocking_notifier_call_chain(&acpi_lid_notifier, state,
240 device);
241 if (ret == NOTIFY_DONE || ret == NOTIFY_OK) {
242 /*
243 * It is also regarded as success if the notifier_chain
244 * returns NOTIFY_OK or NOTIFY_DONE.
245 */
246 ret = 0;
247 }
248 return ret;
249 }
250
acpi_button_state_seq_show(struct seq_file * seq,void * offset)251 static int __maybe_unused acpi_button_state_seq_show(struct seq_file *seq,
252 void *offset)
253 {
254 struct acpi_device *device = seq->private;
255 int state;
256
257 state = acpi_lid_evaluate_state(device);
258 seq_printf(seq, "state: %s\n",
259 state < 0 ? "unsupported" : (state ? "open" : "closed"));
260 return 0;
261 }
262
acpi_button_add_fs(struct acpi_device * device)263 static int acpi_button_add_fs(struct acpi_device *device)
264 {
265 struct acpi_button *button = acpi_driver_data(device);
266 struct proc_dir_entry *entry = NULL;
267 int ret = 0;
268
269 /* procfs I/F for ACPI lid device only */
270 if (button->type != ACPI_BUTTON_TYPE_LID)
271 return 0;
272
273 if (acpi_button_dir || acpi_lid_dir) {
274 printk(KERN_ERR PREFIX "More than one Lid device found!\n");
275 return -EEXIST;
276 }
277
278 /* create /proc/acpi/button */
279 acpi_button_dir = proc_mkdir(ACPI_BUTTON_CLASS, acpi_root_dir);
280 if (!acpi_button_dir)
281 return -ENODEV;
282
283 /* create /proc/acpi/button/lid */
284 acpi_lid_dir = proc_mkdir(ACPI_BUTTON_SUBCLASS_LID, acpi_button_dir);
285 if (!acpi_lid_dir) {
286 ret = -ENODEV;
287 goto remove_button_dir;
288 }
289
290 /* create /proc/acpi/button/lid/LID/ */
291 acpi_device_dir(device) = proc_mkdir(acpi_device_bid(device), acpi_lid_dir);
292 if (!acpi_device_dir(device)) {
293 ret = -ENODEV;
294 goto remove_lid_dir;
295 }
296
297 /* create /proc/acpi/button/lid/LID/state */
298 entry = proc_create_single_data(ACPI_BUTTON_FILE_STATE, S_IRUGO,
299 acpi_device_dir(device), acpi_button_state_seq_show,
300 device);
301 if (!entry) {
302 ret = -ENODEV;
303 goto remove_dev_dir;
304 }
305
306 done:
307 return ret;
308
309 remove_dev_dir:
310 remove_proc_entry(acpi_device_bid(device),
311 acpi_lid_dir);
312 acpi_device_dir(device) = NULL;
313 remove_lid_dir:
314 remove_proc_entry(ACPI_BUTTON_SUBCLASS_LID, acpi_button_dir);
315 acpi_lid_dir = NULL;
316 remove_button_dir:
317 remove_proc_entry(ACPI_BUTTON_CLASS, acpi_root_dir);
318 acpi_button_dir = NULL;
319 goto done;
320 }
321
acpi_button_remove_fs(struct acpi_device * device)322 static int acpi_button_remove_fs(struct acpi_device *device)
323 {
324 struct acpi_button *button = acpi_driver_data(device);
325
326 if (button->type != ACPI_BUTTON_TYPE_LID)
327 return 0;
328
329 remove_proc_entry(ACPI_BUTTON_FILE_STATE,
330 acpi_device_dir(device));
331 remove_proc_entry(acpi_device_bid(device),
332 acpi_lid_dir);
333 acpi_device_dir(device) = NULL;
334 remove_proc_entry(ACPI_BUTTON_SUBCLASS_LID, acpi_button_dir);
335 acpi_lid_dir = NULL;
336 remove_proc_entry(ACPI_BUTTON_CLASS, acpi_root_dir);
337 acpi_button_dir = NULL;
338
339 return 0;
340 }
341
342 /* --------------------------------------------------------------------------
343 Driver Interface
344 -------------------------------------------------------------------------- */
acpi_lid_notifier_register(struct notifier_block * nb)345 int acpi_lid_notifier_register(struct notifier_block *nb)
346 {
347 return blocking_notifier_chain_register(&acpi_lid_notifier, nb);
348 }
349 EXPORT_SYMBOL(acpi_lid_notifier_register);
350
acpi_lid_notifier_unregister(struct notifier_block * nb)351 int acpi_lid_notifier_unregister(struct notifier_block *nb)
352 {
353 return blocking_notifier_chain_unregister(&acpi_lid_notifier, nb);
354 }
355 EXPORT_SYMBOL(acpi_lid_notifier_unregister);
356
acpi_lid_open(void)357 int acpi_lid_open(void)
358 {
359 if (!lid_device)
360 return -ENODEV;
361
362 return acpi_lid_evaluate_state(lid_device);
363 }
364 EXPORT_SYMBOL(acpi_lid_open);
365
acpi_lid_update_state(struct acpi_device * device,bool signal_wakeup)366 static int acpi_lid_update_state(struct acpi_device *device,
367 bool signal_wakeup)
368 {
369 int state;
370
371 state = acpi_lid_evaluate_state(device);
372 if (state < 0)
373 return state;
374
375 if (state && signal_wakeup)
376 acpi_pm_wakeup_event(&device->dev);
377
378 return acpi_lid_notify_state(device, state);
379 }
380
acpi_lid_initialize_state(struct acpi_device * device)381 static void acpi_lid_initialize_state(struct acpi_device *device)
382 {
383 switch (lid_init_state) {
384 case ACPI_BUTTON_LID_INIT_OPEN:
385 (void)acpi_lid_notify_state(device, 1);
386 break;
387 case ACPI_BUTTON_LID_INIT_METHOD:
388 (void)acpi_lid_update_state(device, false);
389 break;
390 case ACPI_BUTTON_LID_INIT_IGNORE:
391 default:
392 break;
393 }
394 }
395
acpi_button_notify(struct acpi_device * device,u32 event)396 static void acpi_button_notify(struct acpi_device *device, u32 event)
397 {
398 struct acpi_button *button = acpi_driver_data(device);
399 struct input_dev *input;
400 int users;
401
402 switch (event) {
403 case ACPI_FIXED_HARDWARE_EVENT:
404 event = ACPI_BUTTON_NOTIFY_STATUS;
405 /* fall through */
406 case ACPI_BUTTON_NOTIFY_STATUS:
407 input = button->input;
408 if (button->type == ACPI_BUTTON_TYPE_LID) {
409 mutex_lock(&button->input->mutex);
410 users = button->input->users;
411 mutex_unlock(&button->input->mutex);
412 if (users)
413 acpi_lid_update_state(device, true);
414 } else {
415 int keycode;
416
417 acpi_pm_wakeup_event(&device->dev);
418 if (button->suspended)
419 break;
420
421 keycode = test_bit(KEY_SLEEP, input->keybit) ?
422 KEY_SLEEP : KEY_POWER;
423 input_report_key(input, keycode, 1);
424 input_sync(input);
425 input_report_key(input, keycode, 0);
426 input_sync(input);
427
428 acpi_bus_generate_netlink_event(
429 device->pnp.device_class,
430 dev_name(&device->dev),
431 event, ++button->pushed);
432 }
433 break;
434 default:
435 ACPI_DEBUG_PRINT((ACPI_DB_INFO,
436 "Unsupported event [0x%x]\n", event));
437 break;
438 }
439 }
440
441 #ifdef CONFIG_PM_SLEEP
acpi_button_suspend(struct device * dev)442 static int acpi_button_suspend(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 = true;
448 return 0;
449 }
450
acpi_button_resume(struct device * dev)451 static int acpi_button_resume(struct device *dev)
452 {
453 struct acpi_device *device = to_acpi_device(dev);
454 struct acpi_button *button = acpi_driver_data(device);
455
456 button->suspended = false;
457 if (button->type == ACPI_BUTTON_TYPE_LID && button->input->users) {
458 button->last_state = !!acpi_lid_evaluate_state(device);
459 button->last_time = ktime_get();
460 acpi_lid_initialize_state(device);
461 }
462 return 0;
463 }
464 #endif
465
acpi_lid_input_open(struct input_dev * input)466 static int acpi_lid_input_open(struct input_dev *input)
467 {
468 struct acpi_device *device = input_get_drvdata(input);
469 struct acpi_button *button = acpi_driver_data(device);
470
471 button->last_state = !!acpi_lid_evaluate_state(device);
472 button->last_time = ktime_get();
473 acpi_lid_initialize_state(device);
474
475 return 0;
476 }
477
acpi_button_add(struct acpi_device * device)478 static int acpi_button_add(struct acpi_device *device)
479 {
480 struct acpi_button *button;
481 struct input_dev *input;
482 const char *hid = acpi_device_hid(device);
483 char *name, *class;
484 int error;
485
486 if (!strcmp(hid, ACPI_BUTTON_HID_LID) && dmi_check_system(lid_blacklst))
487 return -ENODEV;
488
489 button = kzalloc(sizeof(struct acpi_button), GFP_KERNEL);
490 if (!button)
491 return -ENOMEM;
492
493 device->driver_data = button;
494
495 button->input = input = input_allocate_device();
496 if (!input) {
497 error = -ENOMEM;
498 goto err_free_button;
499 }
500
501 name = acpi_device_name(device);
502 class = acpi_device_class(device);
503
504 if (!strcmp(hid, ACPI_BUTTON_HID_POWER) ||
505 !strcmp(hid, ACPI_BUTTON_HID_POWERF)) {
506 button->type = ACPI_BUTTON_TYPE_POWER;
507 strcpy(name, ACPI_BUTTON_DEVICE_NAME_POWER);
508 sprintf(class, "%s/%s",
509 ACPI_BUTTON_CLASS, ACPI_BUTTON_SUBCLASS_POWER);
510 } else if (!strcmp(hid, ACPI_BUTTON_HID_SLEEP) ||
511 !strcmp(hid, ACPI_BUTTON_HID_SLEEPF)) {
512 button->type = ACPI_BUTTON_TYPE_SLEEP;
513 strcpy(name, ACPI_BUTTON_DEVICE_NAME_SLEEP);
514 sprintf(class, "%s/%s",
515 ACPI_BUTTON_CLASS, ACPI_BUTTON_SUBCLASS_SLEEP);
516 } else if (!strcmp(hid, ACPI_BUTTON_HID_LID)) {
517 button->type = ACPI_BUTTON_TYPE_LID;
518 strcpy(name, ACPI_BUTTON_DEVICE_NAME_LID);
519 sprintf(class, "%s/%s",
520 ACPI_BUTTON_CLASS, ACPI_BUTTON_SUBCLASS_LID);
521 input->open = acpi_lid_input_open;
522 } else {
523 printk(KERN_ERR PREFIX "Unsupported hid [%s]\n", hid);
524 error = -ENODEV;
525 goto err_free_input;
526 }
527
528 error = acpi_button_add_fs(device);
529 if (error)
530 goto err_free_input;
531
532 snprintf(button->phys, sizeof(button->phys), "%s/button/input0", hid);
533
534 input->name = name;
535 input->phys = button->phys;
536 input->id.bustype = BUS_HOST;
537 input->id.product = button->type;
538 input->dev.parent = &device->dev;
539
540 switch (button->type) {
541 case ACPI_BUTTON_TYPE_POWER:
542 input_set_capability(input, EV_KEY, KEY_POWER);
543 break;
544
545 case ACPI_BUTTON_TYPE_SLEEP:
546 input_set_capability(input, EV_KEY, KEY_SLEEP);
547 break;
548
549 case ACPI_BUTTON_TYPE_LID:
550 input_set_capability(input, EV_SW, SW_LID);
551 break;
552 }
553
554 input_set_drvdata(input, device);
555 error = input_register_device(input);
556 if (error)
557 goto err_remove_fs;
558 if (button->type == ACPI_BUTTON_TYPE_LID) {
559 /*
560 * This assumes there's only one lid device, or if there are
561 * more we only care about the last one...
562 */
563 lid_device = device;
564 }
565
566 device_init_wakeup(&device->dev, true);
567 printk(KERN_INFO PREFIX "%s [%s]\n", name, acpi_device_bid(device));
568 return 0;
569
570 err_remove_fs:
571 acpi_button_remove_fs(device);
572 err_free_input:
573 input_free_device(input);
574 err_free_button:
575 kfree(button);
576 return error;
577 }
578
acpi_button_remove(struct acpi_device * device)579 static int acpi_button_remove(struct acpi_device *device)
580 {
581 struct acpi_button *button = acpi_driver_data(device);
582
583 acpi_button_remove_fs(device);
584 input_unregister_device(button->input);
585 kfree(button);
586 return 0;
587 }
588
param_set_lid_init_state(const char * val,const struct kernel_param * kp)589 static int param_set_lid_init_state(const char *val,
590 const struct kernel_param *kp)
591 {
592 int result = 0;
593
594 if (!strncmp(val, "open", sizeof("open") - 1)) {
595 lid_init_state = ACPI_BUTTON_LID_INIT_OPEN;
596 pr_info("Notify initial lid state as open\n");
597 } else if (!strncmp(val, "method", sizeof("method") - 1)) {
598 lid_init_state = ACPI_BUTTON_LID_INIT_METHOD;
599 pr_info("Notify initial lid state with _LID return value\n");
600 } else if (!strncmp(val, "ignore", sizeof("ignore") - 1)) {
601 lid_init_state = ACPI_BUTTON_LID_INIT_IGNORE;
602 pr_info("Do not notify initial lid state\n");
603 } else
604 result = -EINVAL;
605 return result;
606 }
607
param_get_lid_init_state(char * buffer,const struct kernel_param * kp)608 static int param_get_lid_init_state(char *buffer,
609 const struct kernel_param *kp)
610 {
611 switch (lid_init_state) {
612 case ACPI_BUTTON_LID_INIT_OPEN:
613 return sprintf(buffer, "open");
614 case ACPI_BUTTON_LID_INIT_METHOD:
615 return sprintf(buffer, "method");
616 case ACPI_BUTTON_LID_INIT_IGNORE:
617 return sprintf(buffer, "ignore");
618 default:
619 return sprintf(buffer, "invalid");
620 }
621 return 0;
622 }
623
624 module_param_call(lid_init_state,
625 param_set_lid_init_state, param_get_lid_init_state,
626 NULL, 0644);
627 MODULE_PARM_DESC(lid_init_state, "Behavior for reporting LID initial state");
628
acpi_button_register_driver(struct acpi_driver * driver)629 static int acpi_button_register_driver(struct acpi_driver *driver)
630 {
631 /*
632 * Modules such as nouveau.ko and i915.ko have a link time dependency
633 * on acpi_lid_open(), and would therefore not be loadable on ACPI
634 * capable kernels booted in non-ACPI mode if the return value of
635 * acpi_bus_register_driver() is returned from here with ACPI disabled
636 * when this driver is built as a module.
637 */
638 if (acpi_disabled)
639 return 0;
640
641 return acpi_bus_register_driver(driver);
642 }
643
acpi_button_unregister_driver(struct acpi_driver * driver)644 static void acpi_button_unregister_driver(struct acpi_driver *driver)
645 {
646 if (!acpi_disabled)
647 acpi_bus_unregister_driver(driver);
648 }
649
650 module_driver(acpi_button_driver, acpi_button_register_driver,
651 acpi_button_unregister_driver);
652