1 /*
2 * button.c - ACPI Button Driver
3 *
4 * Copyright (C) 2001, 2002 Andy Grover <andrew.grover@intel.com>
5 * Copyright (C) 2001, 2002 Paul Diefenbaugh <paul.s.diefenbaugh@intel.com>
6 *
7 * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
8 *
9 * This program is free software; you can redistribute it and/or modify
10 * it under the terms of the GNU General Public License as published by
11 * the Free Software Foundation; either version 2 of the License, or (at
12 * your option) any later version.
13 *
14 * This program is distributed in the hope that it will be useful, but
15 * WITHOUT ANY WARRANTY; without even the implied warranty of
16 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
17 * General Public License for more details.
18 *
19 * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
20 */
21
22 #define pr_fmt(fmt) "ACPI: button: " fmt
23
24 #include <linux/compiler.h>
25 #include <linux/kernel.h>
26 #include <linux/module.h>
27 #include <linux/init.h>
28 #include <linux/types.h>
29 #include <linux/proc_fs.h>
30 #include <linux/seq_file.h>
31 #include <linux/input.h>
32 #include <linux/slab.h>
33 #include <linux/acpi.h>
34 #include <linux/dmi.h>
35 #include <acpi/button.h>
36
37 #define PREFIX "ACPI: "
38
39 #define ACPI_BUTTON_CLASS "button"
40 #define ACPI_BUTTON_FILE_INFO "info"
41 #define ACPI_BUTTON_FILE_STATE "state"
42 #define ACPI_BUTTON_TYPE_UNKNOWN 0x00
43 #define ACPI_BUTTON_NOTIFY_STATUS 0x80
44
45 #define ACPI_BUTTON_SUBCLASS_POWER "power"
46 #define ACPI_BUTTON_HID_POWER "PNP0C0C"
47 #define ACPI_BUTTON_DEVICE_NAME_POWER "Power Button"
48 #define ACPI_BUTTON_TYPE_POWER 0x01
49
50 #define ACPI_BUTTON_SUBCLASS_SLEEP "sleep"
51 #define ACPI_BUTTON_HID_SLEEP "PNP0C0E"
52 #define ACPI_BUTTON_DEVICE_NAME_SLEEP "Sleep Button"
53 #define ACPI_BUTTON_TYPE_SLEEP 0x03
54
55 #define ACPI_BUTTON_SUBCLASS_LID "lid"
56 #define ACPI_BUTTON_HID_LID "PNP0C0D"
57 #define ACPI_BUTTON_DEVICE_NAME_LID "Lid Switch"
58 #define ACPI_BUTTON_TYPE_LID 0x05
59
60 #define ACPI_BUTTON_LID_INIT_IGNORE 0x00
61 #define ACPI_BUTTON_LID_INIT_OPEN 0x01
62 #define ACPI_BUTTON_LID_INIT_METHOD 0x02
63
64 #define _COMPONENT ACPI_BUTTON_COMPONENT
65 ACPI_MODULE_NAME("button");
66
67 MODULE_AUTHOR("Paul Diefenbaugh");
68 MODULE_DESCRIPTION("ACPI Button Driver");
69 MODULE_LICENSE("GPL");
70
71 static const struct acpi_device_id button_device_ids[] = {
72 {ACPI_BUTTON_HID_LID, 0},
73 {ACPI_BUTTON_HID_SLEEP, 0},
74 {ACPI_BUTTON_HID_SLEEPF, 0},
75 {ACPI_BUTTON_HID_POWER, 0},
76 {ACPI_BUTTON_HID_POWERF, 0},
77 {"", 0},
78 };
79 MODULE_DEVICE_TABLE(acpi, button_device_ids);
80
81 /*
82 * Some devices which don't even have a lid in anyway have a broken _LID
83 * method (e.g. pointing to a floating gpio pin) causing spurious LID events.
84 */
85 static const struct dmi_system_id lid_blacklst[] = {
86 {
87 /* GP-electronic T701 */
88 .matches = {
89 DMI_MATCH(DMI_SYS_VENDOR, "Insyde"),
90 DMI_MATCH(DMI_PRODUCT_NAME, "T701"),
91 DMI_MATCH(DMI_BIOS_VERSION, "BYT70A.YNCHENG.WIN.007"),
92 },
93 },
94 {}
95 };
96
97 static int acpi_button_add(struct acpi_device *device);
98 static int acpi_button_remove(struct acpi_device *device);
99 static void acpi_button_notify(struct acpi_device *device, u32 event);
100
101 #ifdef CONFIG_PM_SLEEP
102 static int acpi_button_suspend(struct device *dev);
103 static int acpi_button_resume(struct device *dev);
104 #else
105 #define acpi_button_suspend NULL
106 #define acpi_button_resume NULL
107 #endif
108 static SIMPLE_DEV_PM_OPS(acpi_button_pm, acpi_button_suspend, acpi_button_resume);
109
110 static struct acpi_driver acpi_button_driver = {
111 .name = "button",
112 .class = ACPI_BUTTON_CLASS,
113 .ids = button_device_ids,
114 .ops = {
115 .add = acpi_button_add,
116 .remove = acpi_button_remove,
117 .notify = acpi_button_notify,
118 },
119 .drv.pm = &acpi_button_pm,
120 };
121
122 struct acpi_button {
123 unsigned int type;
124 struct input_dev *input;
125 char phys[32]; /* for input device */
126 unsigned long pushed;
127 int last_state;
128 ktime_t last_time;
129 bool suspended;
130 };
131
132 static BLOCKING_NOTIFIER_HEAD(acpi_lid_notifier);
133 static struct acpi_device *lid_device;
134 static u8 lid_init_state = ACPI_BUTTON_LID_INIT_METHOD;
135
136 static unsigned long lid_report_interval __read_mostly = 500;
137 module_param(lid_report_interval, ulong, 0644);
138 MODULE_PARM_DESC(lid_report_interval, "Interval (ms) between lid key events");
139
140 /* --------------------------------------------------------------------------
141 FS Interface (/proc)
142 -------------------------------------------------------------------------- */
143
144 static struct proc_dir_entry *acpi_button_dir;
145 static struct proc_dir_entry *acpi_lid_dir;
146
acpi_lid_evaluate_state(struct acpi_device * device)147 static int acpi_lid_evaluate_state(struct acpi_device *device)
148 {
149 unsigned long long lid_state;
150 acpi_status status;
151
152 status = acpi_evaluate_integer(device->handle, "_LID", NULL, &lid_state);
153 if (ACPI_FAILURE(status))
154 return -ENODEV;
155
156 return lid_state ? 1 : 0;
157 }
158
acpi_lid_notify_state(struct acpi_device * device,int state)159 static int acpi_lid_notify_state(struct acpi_device *device, int state)
160 {
161 struct acpi_button *button = acpi_driver_data(device);
162 int ret;
163 ktime_t next_report;
164 bool do_update;
165
166 /*
167 * In lid_init_state=ignore mode, if user opens/closes lid
168 * frequently with "open" missing, and "last_time" is also updated
169 * frequently, "close" cannot be delivered to the userspace.
170 * So "last_time" is only updated after a timeout or an actual
171 * switch.
172 */
173 if (lid_init_state != ACPI_BUTTON_LID_INIT_IGNORE ||
174 button->last_state != !!state)
175 do_update = true;
176 else
177 do_update = false;
178
179 next_report = ktime_add(button->last_time,
180 ms_to_ktime(lid_report_interval));
181 if (button->last_state == !!state &&
182 ktime_after(ktime_get(), next_report)) {
183 /* Complain the buggy firmware */
184 pr_warn_once("The lid device is not compliant to SW_LID.\n");
185
186 /*
187 * Send the unreliable complement switch event:
188 *
189 * On most platforms, the lid device is reliable. However
190 * there are exceptions:
191 * 1. Platforms returning initial lid state as "close" by
192 * default after booting/resuming:
193 * https://bugzilla.kernel.org/show_bug.cgi?id=89211
194 * https://bugzilla.kernel.org/show_bug.cgi?id=106151
195 * 2. Platforms never reporting "open" events:
196 * https://bugzilla.kernel.org/show_bug.cgi?id=106941
197 * On these buggy platforms, the usage model of the ACPI
198 * lid device actually is:
199 * 1. The initial returning value of _LID may not be
200 * reliable.
201 * 2. The open event may not be reliable.
202 * 3. The close event is reliable.
203 *
204 * But SW_LID is typed as input switch event, the input
205 * layer checks if the event is redundant. Hence if the
206 * state is not switched, the userspace cannot see this
207 * platform triggered reliable event. By inserting a
208 * complement switch event, it then is guaranteed that the
209 * platform triggered reliable one can always be seen by
210 * the userspace.
211 */
212 if (lid_init_state == ACPI_BUTTON_LID_INIT_IGNORE) {
213 do_update = true;
214 /*
215 * Do generate complement switch event for "close"
216 * as "close" is reliable and wrong "open" won't
217 * trigger unexpected behaviors.
218 * Do not generate complement switch event for
219 * "open" as "open" is not reliable and wrong
220 * "close" will trigger unexpected behaviors.
221 */
222 if (!state) {
223 input_report_switch(button->input,
224 SW_LID, state);
225 input_sync(button->input);
226 }
227 }
228 }
229 /* Send the platform triggered reliable event */
230 if (do_update) {
231 acpi_handle_debug(device->handle, "ACPI LID %s\n",
232 state ? "open" : "closed");
233 input_report_switch(button->input, SW_LID, !state);
234 input_sync(button->input);
235 button->last_state = !!state;
236 button->last_time = ktime_get();
237 }
238
239 ret = blocking_notifier_call_chain(&acpi_lid_notifier, state, device);
240 if (ret == NOTIFY_DONE)
241 ret = blocking_notifier_call_chain(&acpi_lid_notifier, state,
242 device);
243 if (ret == NOTIFY_DONE || ret == NOTIFY_OK) {
244 /*
245 * It is also regarded as success if the notifier_chain
246 * returns NOTIFY_OK or NOTIFY_DONE.
247 */
248 ret = 0;
249 }
250 return ret;
251 }
252
acpi_button_state_seq_show(struct seq_file * seq,void * offset)253 static int __maybe_unused acpi_button_state_seq_show(struct seq_file *seq,
254 void *offset)
255 {
256 struct acpi_device *device = seq->private;
257 int state;
258
259 state = acpi_lid_evaluate_state(device);
260 seq_printf(seq, "state: %s\n",
261 state < 0 ? "unsupported" : (state ? "open" : "closed"));
262 return 0;
263 }
264
acpi_button_add_fs(struct acpi_device * device)265 static int acpi_button_add_fs(struct acpi_device *device)
266 {
267 struct acpi_button *button = acpi_driver_data(device);
268 struct proc_dir_entry *entry = NULL;
269 int ret = 0;
270
271 /* procfs I/F for ACPI lid device only */
272 if (button->type != ACPI_BUTTON_TYPE_LID)
273 return 0;
274
275 if (acpi_button_dir || acpi_lid_dir) {
276 printk(KERN_ERR PREFIX "More than one Lid device found!\n");
277 return -EEXIST;
278 }
279
280 /* create /proc/acpi/button */
281 acpi_button_dir = proc_mkdir(ACPI_BUTTON_CLASS, acpi_root_dir);
282 if (!acpi_button_dir)
283 return -ENODEV;
284
285 /* create /proc/acpi/button/lid */
286 acpi_lid_dir = proc_mkdir(ACPI_BUTTON_SUBCLASS_LID, acpi_button_dir);
287 if (!acpi_lid_dir) {
288 ret = -ENODEV;
289 goto remove_button_dir;
290 }
291
292 /* create /proc/acpi/button/lid/LID/ */
293 acpi_device_dir(device) = proc_mkdir(acpi_device_bid(device), acpi_lid_dir);
294 if (!acpi_device_dir(device)) {
295 ret = -ENODEV;
296 goto remove_lid_dir;
297 }
298
299 /* create /proc/acpi/button/lid/LID/state */
300 entry = proc_create_single_data(ACPI_BUTTON_FILE_STATE, S_IRUGO,
301 acpi_device_dir(device), acpi_button_state_seq_show,
302 device);
303 if (!entry) {
304 ret = -ENODEV;
305 goto remove_dev_dir;
306 }
307
308 done:
309 return ret;
310
311 remove_dev_dir:
312 remove_proc_entry(acpi_device_bid(device),
313 acpi_lid_dir);
314 acpi_device_dir(device) = NULL;
315 remove_lid_dir:
316 remove_proc_entry(ACPI_BUTTON_SUBCLASS_LID, acpi_button_dir);
317 acpi_lid_dir = NULL;
318 remove_button_dir:
319 remove_proc_entry(ACPI_BUTTON_CLASS, acpi_root_dir);
320 acpi_button_dir = NULL;
321 goto done;
322 }
323
acpi_button_remove_fs(struct acpi_device * device)324 static int acpi_button_remove_fs(struct acpi_device *device)
325 {
326 struct acpi_button *button = acpi_driver_data(device);
327
328 if (button->type != ACPI_BUTTON_TYPE_LID)
329 return 0;
330
331 remove_proc_entry(ACPI_BUTTON_FILE_STATE,
332 acpi_device_dir(device));
333 remove_proc_entry(acpi_device_bid(device),
334 acpi_lid_dir);
335 acpi_device_dir(device) = NULL;
336 remove_proc_entry(ACPI_BUTTON_SUBCLASS_LID, acpi_button_dir);
337 acpi_lid_dir = NULL;
338 remove_proc_entry(ACPI_BUTTON_CLASS, acpi_root_dir);
339 acpi_button_dir = NULL;
340
341 return 0;
342 }
343
344 /* --------------------------------------------------------------------------
345 Driver Interface
346 -------------------------------------------------------------------------- */
acpi_lid_notifier_register(struct notifier_block * nb)347 int acpi_lid_notifier_register(struct notifier_block *nb)
348 {
349 return blocking_notifier_chain_register(&acpi_lid_notifier, nb);
350 }
351 EXPORT_SYMBOL(acpi_lid_notifier_register);
352
acpi_lid_notifier_unregister(struct notifier_block * nb)353 int acpi_lid_notifier_unregister(struct notifier_block *nb)
354 {
355 return blocking_notifier_chain_unregister(&acpi_lid_notifier, nb);
356 }
357 EXPORT_SYMBOL(acpi_lid_notifier_unregister);
358
acpi_lid_open(void)359 int acpi_lid_open(void)
360 {
361 if (!lid_device)
362 return -ENODEV;
363
364 return acpi_lid_evaluate_state(lid_device);
365 }
366 EXPORT_SYMBOL(acpi_lid_open);
367
acpi_lid_update_state(struct acpi_device * device,bool signal_wakeup)368 static int acpi_lid_update_state(struct acpi_device *device,
369 bool signal_wakeup)
370 {
371 int state;
372
373 state = acpi_lid_evaluate_state(device);
374 if (state < 0)
375 return state;
376
377 if (state && signal_wakeup)
378 acpi_pm_wakeup_event(&device->dev);
379
380 return acpi_lid_notify_state(device, state);
381 }
382
acpi_lid_initialize_state(struct acpi_device * device)383 static void acpi_lid_initialize_state(struct acpi_device *device)
384 {
385 switch (lid_init_state) {
386 case ACPI_BUTTON_LID_INIT_OPEN:
387 (void)acpi_lid_notify_state(device, 1);
388 break;
389 case ACPI_BUTTON_LID_INIT_METHOD:
390 (void)acpi_lid_update_state(device, false);
391 break;
392 case ACPI_BUTTON_LID_INIT_IGNORE:
393 default:
394 break;
395 }
396 }
397
acpi_button_notify(struct acpi_device * device,u32 event)398 static void acpi_button_notify(struct acpi_device *device, u32 event)
399 {
400 struct acpi_button *button = acpi_driver_data(device);
401 struct input_dev *input;
402 int users;
403
404 switch (event) {
405 case ACPI_FIXED_HARDWARE_EVENT:
406 event = ACPI_BUTTON_NOTIFY_STATUS;
407 /* fall through */
408 case ACPI_BUTTON_NOTIFY_STATUS:
409 input = button->input;
410 if (button->type == ACPI_BUTTON_TYPE_LID) {
411 mutex_lock(&button->input->mutex);
412 users = button->input->users;
413 mutex_unlock(&button->input->mutex);
414 if (users)
415 acpi_lid_update_state(device, true);
416 } else {
417 int keycode;
418
419 acpi_pm_wakeup_event(&device->dev);
420 if (button->suspended)
421 break;
422
423 keycode = test_bit(KEY_SLEEP, input->keybit) ?
424 KEY_SLEEP : KEY_POWER;
425 input_report_key(input, keycode, 1);
426 input_sync(input);
427 input_report_key(input, keycode, 0);
428 input_sync(input);
429
430 acpi_bus_generate_netlink_event(
431 device->pnp.device_class,
432 dev_name(&device->dev),
433 event, ++button->pushed);
434 }
435 break;
436 default:
437 ACPI_DEBUG_PRINT((ACPI_DB_INFO,
438 "Unsupported event [0x%x]\n", event));
439 break;
440 }
441 }
442
443 #ifdef CONFIG_PM_SLEEP
acpi_button_suspend(struct device * dev)444 static int acpi_button_suspend(struct device *dev)
445 {
446 struct acpi_device *device = to_acpi_device(dev);
447 struct acpi_button *button = acpi_driver_data(device);
448
449 button->suspended = true;
450 return 0;
451 }
452
acpi_button_resume(struct device * dev)453 static int acpi_button_resume(struct device *dev)
454 {
455 struct acpi_device *device = to_acpi_device(dev);
456 struct acpi_button *button = acpi_driver_data(device);
457
458 button->suspended = false;
459 if (button->type == ACPI_BUTTON_TYPE_LID && button->input->users)
460 acpi_lid_initialize_state(device);
461 return 0;
462 }
463 #endif
464
acpi_lid_input_open(struct input_dev * input)465 static int acpi_lid_input_open(struct input_dev *input)
466 {
467 struct acpi_device *device = input_get_drvdata(input);
468 struct acpi_button *button = acpi_driver_data(device);
469
470 button->last_state = !!acpi_lid_evaluate_state(device);
471 button->last_time = ktime_get();
472 acpi_lid_initialize_state(device);
473
474 return 0;
475 }
476
acpi_button_add(struct acpi_device * device)477 static int acpi_button_add(struct acpi_device *device)
478 {
479 struct acpi_button *button;
480 struct input_dev *input;
481 const char *hid = acpi_device_hid(device);
482 char *name, *class;
483 int error;
484
485 if (!strcmp(hid, ACPI_BUTTON_HID_LID) && dmi_check_system(lid_blacklst))
486 return -ENODEV;
487
488 button = kzalloc(sizeof(struct acpi_button), GFP_KERNEL);
489 if (!button)
490 return -ENOMEM;
491
492 device->driver_data = button;
493
494 button->input = input = input_allocate_device();
495 if (!input) {
496 error = -ENOMEM;
497 goto err_free_button;
498 }
499
500 name = acpi_device_name(device);
501 class = acpi_device_class(device);
502
503 if (!strcmp(hid, ACPI_BUTTON_HID_POWER) ||
504 !strcmp(hid, ACPI_BUTTON_HID_POWERF)) {
505 button->type = ACPI_BUTTON_TYPE_POWER;
506 strcpy(name, ACPI_BUTTON_DEVICE_NAME_POWER);
507 sprintf(class, "%s/%s",
508 ACPI_BUTTON_CLASS, ACPI_BUTTON_SUBCLASS_POWER);
509 } else if (!strcmp(hid, ACPI_BUTTON_HID_SLEEP) ||
510 !strcmp(hid, ACPI_BUTTON_HID_SLEEPF)) {
511 button->type = ACPI_BUTTON_TYPE_SLEEP;
512 strcpy(name, ACPI_BUTTON_DEVICE_NAME_SLEEP);
513 sprintf(class, "%s/%s",
514 ACPI_BUTTON_CLASS, ACPI_BUTTON_SUBCLASS_SLEEP);
515 } else if (!strcmp(hid, ACPI_BUTTON_HID_LID)) {
516 button->type = ACPI_BUTTON_TYPE_LID;
517 strcpy(name, ACPI_BUTTON_DEVICE_NAME_LID);
518 sprintf(class, "%s/%s",
519 ACPI_BUTTON_CLASS, ACPI_BUTTON_SUBCLASS_LID);
520 input->open = acpi_lid_input_open;
521 } else {
522 printk(KERN_ERR PREFIX "Unsupported hid [%s]\n", hid);
523 error = -ENODEV;
524 goto err_free_input;
525 }
526
527 error = acpi_button_add_fs(device);
528 if (error)
529 goto err_free_input;
530
531 snprintf(button->phys, sizeof(button->phys), "%s/button/input0", hid);
532
533 input->name = name;
534 input->phys = button->phys;
535 input->id.bustype = BUS_HOST;
536 input->id.product = button->type;
537 input->dev.parent = &device->dev;
538
539 switch (button->type) {
540 case ACPI_BUTTON_TYPE_POWER:
541 input_set_capability(input, EV_KEY, KEY_POWER);
542 break;
543
544 case ACPI_BUTTON_TYPE_SLEEP:
545 input_set_capability(input, EV_KEY, KEY_SLEEP);
546 break;
547
548 case ACPI_BUTTON_TYPE_LID:
549 input_set_capability(input, EV_SW, SW_LID);
550 break;
551 }
552
553 input_set_drvdata(input, device);
554 error = input_register_device(input);
555 if (error)
556 goto err_remove_fs;
557 if (button->type == ACPI_BUTTON_TYPE_LID) {
558 /*
559 * This assumes there's only one lid device, or if there are
560 * more we only care about the last one...
561 */
562 lid_device = device;
563 }
564
565 device_init_wakeup(&device->dev, true);
566 printk(KERN_INFO PREFIX "%s [%s]\n", name, acpi_device_bid(device));
567 return 0;
568
569 err_remove_fs:
570 acpi_button_remove_fs(device);
571 err_free_input:
572 input_free_device(input);
573 err_free_button:
574 kfree(button);
575 return error;
576 }
577
acpi_button_remove(struct acpi_device * device)578 static int acpi_button_remove(struct acpi_device *device)
579 {
580 struct acpi_button *button = acpi_driver_data(device);
581
582 acpi_button_remove_fs(device);
583 input_unregister_device(button->input);
584 kfree(button);
585 return 0;
586 }
587
param_set_lid_init_state(const char * val,const struct kernel_param * kp)588 static int param_set_lid_init_state(const char *val,
589 const struct kernel_param *kp)
590 {
591 int result = 0;
592
593 if (!strncmp(val, "open", sizeof("open") - 1)) {
594 lid_init_state = ACPI_BUTTON_LID_INIT_OPEN;
595 pr_info("Notify initial lid state as open\n");
596 } else if (!strncmp(val, "method", sizeof("method") - 1)) {
597 lid_init_state = ACPI_BUTTON_LID_INIT_METHOD;
598 pr_info("Notify initial lid state with _LID return value\n");
599 } else if (!strncmp(val, "ignore", sizeof("ignore") - 1)) {
600 lid_init_state = ACPI_BUTTON_LID_INIT_IGNORE;
601 pr_info("Do not notify initial lid state\n");
602 } else
603 result = -EINVAL;
604 return result;
605 }
606
param_get_lid_init_state(char * buffer,const struct kernel_param * kp)607 static int param_get_lid_init_state(char *buffer,
608 const struct kernel_param *kp)
609 {
610 switch (lid_init_state) {
611 case ACPI_BUTTON_LID_INIT_OPEN:
612 return sprintf(buffer, "open");
613 case ACPI_BUTTON_LID_INIT_METHOD:
614 return sprintf(buffer, "method");
615 case ACPI_BUTTON_LID_INIT_IGNORE:
616 return sprintf(buffer, "ignore");
617 default:
618 return sprintf(buffer, "invalid");
619 }
620 return 0;
621 }
622
623 module_param_call(lid_init_state,
624 param_set_lid_init_state, param_get_lid_init_state,
625 NULL, 0644);
626 MODULE_PARM_DESC(lid_init_state, "Behavior for reporting LID initial state");
627
acpi_button_register_driver(struct acpi_driver * driver)628 static int acpi_button_register_driver(struct acpi_driver *driver)
629 {
630 /*
631 * Modules such as nouveau.ko and i915.ko have a link time dependency
632 * on acpi_lid_open(), and would therefore not be loadable on ACPI
633 * capable kernels booted in non-ACPI mode if the return value of
634 * acpi_bus_register_driver() is returned from here with ACPI disabled
635 * when this driver is built as a module.
636 */
637 if (acpi_disabled)
638 return 0;
639
640 return acpi_bus_register_driver(driver);
641 }
642
acpi_button_unregister_driver(struct acpi_driver * driver)643 static void acpi_button_unregister_driver(struct acpi_driver *driver)
644 {
645 if (!acpi_disabled)
646 acpi_bus_unregister_driver(driver);
647 }
648
649 module_driver(acpi_button_driver, acpi_button_register_driver,
650 acpi_button_unregister_driver);
651
