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 /* Nextbook Ares 8A tablet, _LID device always reports lid closed */
87 .matches = {
88 DMI_MATCH(DMI_SYS_VENDOR, "Insyde"),
89 DMI_MATCH(DMI_PRODUCT_NAME, "CherryTrail"),
90 DMI_MATCH(DMI_BIOS_VERSION, "M882"),
91 },
92 .driver_data = (void *)(long)ACPI_BUTTON_LID_INIT_DISABLED,
93 },
94 {
95 /*
96 * Medion Akoya E2215T, notification of the LID device only
97 * happens on close, not on open and _LID always returns closed.
98 */
99 .matches = {
100 DMI_MATCH(DMI_SYS_VENDOR, "MEDION"),
101 DMI_MATCH(DMI_PRODUCT_NAME, "E2215T"),
102 },
103 .driver_data = (void *)(long)ACPI_BUTTON_LID_INIT_OPEN,
104 },
105 {
106 /*
107 * Medion Akoya E2228T, notification of the LID device only
108 * happens on close, not on open and _LID always returns closed.
109 */
110 .matches = {
111 DMI_MATCH(DMI_SYS_VENDOR, "MEDION"),
112 DMI_MATCH(DMI_PRODUCT_NAME, "E2228T"),
113 },
114 .driver_data = (void *)(long)ACPI_BUTTON_LID_INIT_OPEN,
115 },
116 {
117 /*
118 * Razer Blade Stealth 13 late 2019, notification of the LID device
119 * only happens on close, not on open and _LID always returns closed.
120 */
121 .matches = {
122 DMI_MATCH(DMI_SYS_VENDOR, "Razer"),
123 DMI_MATCH(DMI_PRODUCT_NAME, "Razer Blade Stealth 13 Late 2019"),
124 },
125 .driver_data = (void *)(long)ACPI_BUTTON_LID_INIT_OPEN,
126 },
127 {}
128 };
129
130 static int acpi_button_add(struct acpi_device *device);
131 static int acpi_button_remove(struct acpi_device *device);
132 static void acpi_button_notify(struct acpi_device *device, u32 event);
133
134 #ifdef CONFIG_PM_SLEEP
135 static int acpi_button_suspend(struct device *dev);
136 static int acpi_button_resume(struct device *dev);
137 #else
138 #define acpi_button_suspend NULL
139 #define acpi_button_resume NULL
140 #endif
141 static SIMPLE_DEV_PM_OPS(acpi_button_pm, acpi_button_suspend, acpi_button_resume);
142
143 static struct acpi_driver acpi_button_driver = {
144 .name = "button",
145 .class = ACPI_BUTTON_CLASS,
146 .ids = button_device_ids,
147 .ops = {
148 .add = acpi_button_add,
149 .remove = acpi_button_remove,
150 .notify = acpi_button_notify,
151 },
152 .drv.pm = &acpi_button_pm,
153 };
154
155 struct acpi_button {
156 unsigned int type;
157 struct input_dev *input;
158 char phys[32]; /* for input device */
159 unsigned long pushed;
160 int last_state;
161 ktime_t last_time;
162 bool suspended;
163 bool lid_state_initialized;
164 };
165
166 static struct acpi_device *lid_device;
167 static long lid_init_state = -1;
168
169 static unsigned long lid_report_interval __read_mostly = 500;
170 module_param(lid_report_interval, ulong, 0644);
171 MODULE_PARM_DESC(lid_report_interval, "Interval (ms) between lid key events");
172
173 /* --------------------------------------------------------------------------
174 FS Interface (/proc)
175 -------------------------------------------------------------------------- */
176
177 static struct proc_dir_entry *acpi_button_dir;
178 static struct proc_dir_entry *acpi_lid_dir;
179
acpi_lid_evaluate_state(struct acpi_device * device)180 static int acpi_lid_evaluate_state(struct acpi_device *device)
181 {
182 unsigned long long lid_state;
183 acpi_status status;
184
185 status = acpi_evaluate_integer(device->handle, "_LID", NULL, &lid_state);
186 if (ACPI_FAILURE(status))
187 return -ENODEV;
188
189 return lid_state ? 1 : 0;
190 }
191
acpi_lid_notify_state(struct acpi_device * device,int state)192 static int acpi_lid_notify_state(struct acpi_device *device, int state)
193 {
194 struct acpi_button *button = acpi_driver_data(device);
195 ktime_t next_report;
196 bool do_update;
197
198 /*
199 * In lid_init_state=ignore mode, if user opens/closes lid
200 * frequently with "open" missing, and "last_time" is also updated
201 * frequently, "close" cannot be delivered to the userspace.
202 * So "last_time" is only updated after a timeout or an actual
203 * switch.
204 */
205 if (lid_init_state != ACPI_BUTTON_LID_INIT_IGNORE ||
206 button->last_state != !!state)
207 do_update = true;
208 else
209 do_update = false;
210
211 next_report = ktime_add(button->last_time,
212 ms_to_ktime(lid_report_interval));
213 if (button->last_state == !!state &&
214 ktime_after(ktime_get(), next_report)) {
215 /* Complain the buggy firmware */
216 pr_warn_once("The lid device is not compliant to SW_LID.\n");
217
218 /*
219 * Send the unreliable complement switch event:
220 *
221 * On most platforms, the lid device is reliable. However
222 * there are exceptions:
223 * 1. Platforms returning initial lid state as "close" by
224 * default after booting/resuming:
225 * https://bugzilla.kernel.org/show_bug.cgi?id=89211
226 * https://bugzilla.kernel.org/show_bug.cgi?id=106151
227 * 2. Platforms never reporting "open" events:
228 * https://bugzilla.kernel.org/show_bug.cgi?id=106941
229 * On these buggy platforms, the usage model of the ACPI
230 * lid device actually is:
231 * 1. The initial returning value of _LID may not be
232 * reliable.
233 * 2. The open event may not be reliable.
234 * 3. The close event is reliable.
235 *
236 * But SW_LID is typed as input switch event, the input
237 * layer checks if the event is redundant. Hence if the
238 * state is not switched, the userspace cannot see this
239 * platform triggered reliable event. By inserting a
240 * complement switch event, it then is guaranteed that the
241 * platform triggered reliable one can always be seen by
242 * the userspace.
243 */
244 if (lid_init_state == ACPI_BUTTON_LID_INIT_IGNORE) {
245 do_update = true;
246 /*
247 * Do generate complement switch event for "close"
248 * as "close" is reliable and wrong "open" won't
249 * trigger unexpected behaviors.
250 * Do not generate complement switch event for
251 * "open" as "open" is not reliable and wrong
252 * "close" will trigger unexpected behaviors.
253 */
254 if (!state) {
255 input_report_switch(button->input,
256 SW_LID, state);
257 input_sync(button->input);
258 }
259 }
260 }
261 /* Send the platform triggered reliable event */
262 if (do_update) {
263 acpi_handle_debug(device->handle, "ACPI LID %s\n",
264 state ? "open" : "closed");
265 input_report_switch(button->input, SW_LID, !state);
266 input_sync(button->input);
267 button->last_state = !!state;
268 button->last_time = ktime_get();
269 }
270
271 return 0;
272 }
273
acpi_button_state_seq_show(struct seq_file * seq,void * offset)274 static int __maybe_unused acpi_button_state_seq_show(struct seq_file *seq,
275 void *offset)
276 {
277 struct acpi_device *device = seq->private;
278 int state;
279
280 state = acpi_lid_evaluate_state(device);
281 seq_printf(seq, "state: %s\n",
282 state < 0 ? "unsupported" : (state ? "open" : "closed"));
283 return 0;
284 }
285
acpi_button_add_fs(struct acpi_device * device)286 static int acpi_button_add_fs(struct acpi_device *device)
287 {
288 struct acpi_button *button = acpi_driver_data(device);
289 struct proc_dir_entry *entry = NULL;
290 int ret = 0;
291
292 /* procfs I/F for ACPI lid device only */
293 if (button->type != ACPI_BUTTON_TYPE_LID)
294 return 0;
295
296 if (acpi_button_dir || acpi_lid_dir) {
297 printk(KERN_ERR PREFIX "More than one Lid device found!\n");
298 return -EEXIST;
299 }
300
301 /* create /proc/acpi/button */
302 acpi_button_dir = proc_mkdir(ACPI_BUTTON_CLASS, acpi_root_dir);
303 if (!acpi_button_dir)
304 return -ENODEV;
305
306 /* create /proc/acpi/button/lid */
307 acpi_lid_dir = proc_mkdir(ACPI_BUTTON_SUBCLASS_LID, acpi_button_dir);
308 if (!acpi_lid_dir) {
309 ret = -ENODEV;
310 goto remove_button_dir;
311 }
312
313 /* create /proc/acpi/button/lid/LID/ */
314 acpi_device_dir(device) = proc_mkdir(acpi_device_bid(device), acpi_lid_dir);
315 if (!acpi_device_dir(device)) {
316 ret = -ENODEV;
317 goto remove_lid_dir;
318 }
319
320 /* create /proc/acpi/button/lid/LID/state */
321 entry = proc_create_single_data(ACPI_BUTTON_FILE_STATE, S_IRUGO,
322 acpi_device_dir(device), acpi_button_state_seq_show,
323 device);
324 if (!entry) {
325 ret = -ENODEV;
326 goto remove_dev_dir;
327 }
328
329 done:
330 return ret;
331
332 remove_dev_dir:
333 remove_proc_entry(acpi_device_bid(device),
334 acpi_lid_dir);
335 acpi_device_dir(device) = NULL;
336 remove_lid_dir:
337 remove_proc_entry(ACPI_BUTTON_SUBCLASS_LID, acpi_button_dir);
338 acpi_lid_dir = NULL;
339 remove_button_dir:
340 remove_proc_entry(ACPI_BUTTON_CLASS, acpi_root_dir);
341 acpi_button_dir = NULL;
342 goto done;
343 }
344
acpi_button_remove_fs(struct acpi_device * device)345 static int acpi_button_remove_fs(struct acpi_device *device)
346 {
347 struct acpi_button *button = acpi_driver_data(device);
348
349 if (button->type != ACPI_BUTTON_TYPE_LID)
350 return 0;
351
352 remove_proc_entry(ACPI_BUTTON_FILE_STATE,
353 acpi_device_dir(device));
354 remove_proc_entry(acpi_device_bid(device),
355 acpi_lid_dir);
356 acpi_device_dir(device) = NULL;
357 remove_proc_entry(ACPI_BUTTON_SUBCLASS_LID, acpi_button_dir);
358 acpi_lid_dir = NULL;
359 remove_proc_entry(ACPI_BUTTON_CLASS, acpi_root_dir);
360 acpi_button_dir = NULL;
361
362 return 0;
363 }
364
365 /* --------------------------------------------------------------------------
366 Driver Interface
367 -------------------------------------------------------------------------- */
acpi_lid_open(void)368 int acpi_lid_open(void)
369 {
370 if (!lid_device)
371 return -ENODEV;
372
373 return acpi_lid_evaluate_state(lid_device);
374 }
375 EXPORT_SYMBOL(acpi_lid_open);
376
acpi_lid_update_state(struct acpi_device * device,bool signal_wakeup)377 static int acpi_lid_update_state(struct acpi_device *device,
378 bool signal_wakeup)
379 {
380 int state;
381
382 state = acpi_lid_evaluate_state(device);
383 if (state < 0)
384 return state;
385
386 if (state && signal_wakeup)
387 acpi_pm_wakeup_event(&device->dev);
388
389 return acpi_lid_notify_state(device, state);
390 }
391
acpi_lid_initialize_state(struct acpi_device * device)392 static void acpi_lid_initialize_state(struct acpi_device *device)
393 {
394 struct acpi_button *button = acpi_driver_data(device);
395
396 switch (lid_init_state) {
397 case ACPI_BUTTON_LID_INIT_OPEN:
398 (void)acpi_lid_notify_state(device, 1);
399 break;
400 case ACPI_BUTTON_LID_INIT_METHOD:
401 (void)acpi_lid_update_state(device, false);
402 break;
403 case ACPI_BUTTON_LID_INIT_IGNORE:
404 default:
405 break;
406 }
407
408 button->lid_state_initialized = true;
409 }
410
acpi_button_notify(struct acpi_device * device,u32 event)411 static void acpi_button_notify(struct acpi_device *device, u32 event)
412 {
413 struct acpi_button *button = acpi_driver_data(device);
414 struct input_dev *input;
415
416 switch (event) {
417 case ACPI_FIXED_HARDWARE_EVENT:
418 event = ACPI_BUTTON_NOTIFY_STATUS;
419 fallthrough;
420 case ACPI_BUTTON_NOTIFY_STATUS:
421 input = button->input;
422 if (button->type == ACPI_BUTTON_TYPE_LID) {
423 if (button->lid_state_initialized)
424 acpi_lid_update_state(device, true);
425 } else {
426 int keycode;
427
428 acpi_pm_wakeup_event(&device->dev);
429 if (button->suspended)
430 break;
431
432 keycode = test_bit(KEY_SLEEP, input->keybit) ?
433 KEY_SLEEP : KEY_POWER;
434 input_report_key(input, keycode, 1);
435 input_sync(input);
436 input_report_key(input, keycode, 0);
437 input_sync(input);
438
439 acpi_bus_generate_netlink_event(
440 device->pnp.device_class,
441 dev_name(&device->dev),
442 event, ++button->pushed);
443 }
444 break;
445 default:
446 ACPI_DEBUG_PRINT((ACPI_DB_INFO,
447 "Unsupported event [0x%x]\n", event));
448 break;
449 }
450 }
451
452 #ifdef CONFIG_PM_SLEEP
acpi_button_suspend(struct device * dev)453 static int acpi_button_suspend(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 = true;
459 return 0;
460 }
461
acpi_button_resume(struct device * dev)462 static int acpi_button_resume(struct device *dev)
463 {
464 struct acpi_device *device = to_acpi_device(dev);
465 struct acpi_button *button = acpi_driver_data(device);
466
467 button->suspended = false;
468 if (button->type == ACPI_BUTTON_TYPE_LID) {
469 button->last_state = !!acpi_lid_evaluate_state(device);
470 button->last_time = ktime_get();
471 acpi_lid_initialize_state(device);
472 }
473 return 0;
474 }
475 #endif
476
acpi_lid_input_open(struct input_dev * input)477 static int acpi_lid_input_open(struct input_dev *input)
478 {
479 struct acpi_device *device = input_get_drvdata(input);
480 struct acpi_button *button = acpi_driver_data(device);
481
482 button->last_state = !!acpi_lid_evaluate_state(device);
483 button->last_time = ktime_get();
484 acpi_lid_initialize_state(device);
485
486 return 0;
487 }
488
acpi_button_add(struct acpi_device * device)489 static int acpi_button_add(struct acpi_device *device)
490 {
491 struct acpi_button *button;
492 struct input_dev *input;
493 const char *hid = acpi_device_hid(device);
494 char *name, *class;
495 int error;
496
497 if (!strcmp(hid, ACPI_BUTTON_HID_LID) &&
498 lid_init_state == ACPI_BUTTON_LID_INIT_DISABLED)
499 return -ENODEV;
500
501 button = kzalloc(sizeof(struct acpi_button), GFP_KERNEL);
502 if (!button)
503 return -ENOMEM;
504
505 device->driver_data = button;
506
507 button->input = input = input_allocate_device();
508 if (!input) {
509 error = -ENOMEM;
510 goto err_free_button;
511 }
512
513 name = acpi_device_name(device);
514 class = acpi_device_class(device);
515
516 if (!strcmp(hid, ACPI_BUTTON_HID_POWER) ||
517 !strcmp(hid, ACPI_BUTTON_HID_POWERF)) {
518 button->type = ACPI_BUTTON_TYPE_POWER;
519 strcpy(name, ACPI_BUTTON_DEVICE_NAME_POWER);
520 sprintf(class, "%s/%s",
521 ACPI_BUTTON_CLASS, ACPI_BUTTON_SUBCLASS_POWER);
522 } else if (!strcmp(hid, ACPI_BUTTON_HID_SLEEP) ||
523 !strcmp(hid, ACPI_BUTTON_HID_SLEEPF)) {
524 button->type = ACPI_BUTTON_TYPE_SLEEP;
525 strcpy(name, ACPI_BUTTON_DEVICE_NAME_SLEEP);
526 sprintf(class, "%s/%s",
527 ACPI_BUTTON_CLASS, ACPI_BUTTON_SUBCLASS_SLEEP);
528 } else if (!strcmp(hid, ACPI_BUTTON_HID_LID)) {
529 button->type = ACPI_BUTTON_TYPE_LID;
530 strcpy(name, ACPI_BUTTON_DEVICE_NAME_LID);
531 sprintf(class, "%s/%s",
532 ACPI_BUTTON_CLASS, ACPI_BUTTON_SUBCLASS_LID);
533 input->open = acpi_lid_input_open;
534 } else {
535 printk(KERN_ERR PREFIX "Unsupported hid [%s]\n", hid);
536 error = -ENODEV;
537 goto err_free_input;
538 }
539
540 error = acpi_button_add_fs(device);
541 if (error)
542 goto err_free_input;
543
544 snprintf(button->phys, sizeof(button->phys), "%s/button/input0", hid);
545
546 input->name = name;
547 input->phys = button->phys;
548 input->id.bustype = BUS_HOST;
549 input->id.product = button->type;
550 input->dev.parent = &device->dev;
551
552 switch (button->type) {
553 case ACPI_BUTTON_TYPE_POWER:
554 input_set_capability(input, EV_KEY, KEY_POWER);
555 break;
556
557 case ACPI_BUTTON_TYPE_SLEEP:
558 input_set_capability(input, EV_KEY, KEY_SLEEP);
559 break;
560
561 case ACPI_BUTTON_TYPE_LID:
562 input_set_capability(input, EV_SW, SW_LID);
563 break;
564 }
565
566 input_set_drvdata(input, device);
567 error = input_register_device(input);
568 if (error)
569 goto err_remove_fs;
570 if (button->type == ACPI_BUTTON_TYPE_LID) {
571 /*
572 * This assumes there's only one lid device, or if there are
573 * more we only care about the last one...
574 */
575 lid_device = device;
576 }
577
578 device_init_wakeup(&device->dev, true);
579 printk(KERN_INFO PREFIX "%s [%s]\n", name, acpi_device_bid(device));
580 return 0;
581
582 err_remove_fs:
583 acpi_button_remove_fs(device);
584 err_free_input:
585 input_free_device(input);
586 err_free_button:
587 kfree(button);
588 return error;
589 }
590
acpi_button_remove(struct acpi_device * device)591 static int acpi_button_remove(struct acpi_device *device)
592 {
593 struct acpi_button *button = acpi_driver_data(device);
594
595 acpi_button_remove_fs(device);
596 input_unregister_device(button->input);
597 kfree(button);
598 return 0;
599 }
600
param_set_lid_init_state(const char * val,const struct kernel_param * kp)601 static int param_set_lid_init_state(const char *val,
602 const struct kernel_param *kp)
603 {
604 int i;
605
606 i = sysfs_match_string(lid_init_state_str, val);
607 if (i < 0)
608 return i;
609
610 lid_init_state = i;
611 pr_info("Initial lid state set to '%s'\n", lid_init_state_str[i]);
612 return 0;
613 }
614
param_get_lid_init_state(char * buf,const struct kernel_param * kp)615 static int param_get_lid_init_state(char *buf, const struct kernel_param *kp)
616 {
617 int i, c = 0;
618
619 for (i = 0; i < ARRAY_SIZE(lid_init_state_str); i++)
620 if (i == lid_init_state)
621 c += sprintf(buf + c, "[%s] ", lid_init_state_str[i]);
622 else
623 c += sprintf(buf + c, "%s ", lid_init_state_str[i]);
624
625 buf[c - 1] = '\n'; /* Replace the final space with a newline */
626
627 return c;
628 }
629
630 module_param_call(lid_init_state,
631 param_set_lid_init_state, param_get_lid_init_state,
632 NULL, 0644);
633 MODULE_PARM_DESC(lid_init_state, "Behavior for reporting LID initial state");
634
acpi_button_register_driver(struct acpi_driver * driver)635 static int acpi_button_register_driver(struct acpi_driver *driver)
636 {
637 const struct dmi_system_id *dmi_id;
638
639 if (lid_init_state == -1) {
640 dmi_id = dmi_first_match(dmi_lid_quirks);
641 if (dmi_id)
642 lid_init_state = (long)dmi_id->driver_data;
643 else
644 lid_init_state = ACPI_BUTTON_LID_INIT_METHOD;
645 }
646
647 /*
648 * Modules such as nouveau.ko and i915.ko have a link time dependency
649 * on acpi_lid_open(), and would therefore not be loadable on ACPI
650 * capable kernels booted in non-ACPI mode if the return value of
651 * acpi_bus_register_driver() is returned from here with ACPI disabled
652 * when this driver is built as a module.
653 */
654 if (acpi_disabled)
655 return 0;
656
657 return acpi_bus_register_driver(driver);
658 }
659
acpi_button_unregister_driver(struct acpi_driver * driver)660 static void acpi_button_unregister_driver(struct acpi_driver *driver)
661 {
662 if (!acpi_disabled)
663 acpi_bus_unregister_driver(driver);
664 }
665
666 module_driver(acpi_button_driver, acpi_button_register_driver,
667 acpi_button_unregister_driver);
668