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 * Lenovo Yoga 9 14ITL5, initial notification of the LID device
83 * never happens.
84 */
85 .matches = {
86 DMI_MATCH(DMI_SYS_VENDOR, "LENOVO"),
87 DMI_MATCH(DMI_PRODUCT_NAME, "82BG"),
88 },
89 .driver_data = (void *)(long)ACPI_BUTTON_LID_INIT_OPEN,
90 },
91 {
92 /*
93 * Medion Akoya E2215T, 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, "E2215T"),
99 },
100 .driver_data = (void *)(long)ACPI_BUTTON_LID_INIT_OPEN,
101 },
102 {
103 /*
104 * Medion Akoya E2228T, notification of the LID device only
105 * happens on close, not on open and _LID always returns closed.
106 */
107 .matches = {
108 DMI_MATCH(DMI_SYS_VENDOR, "MEDION"),
109 DMI_MATCH(DMI_PRODUCT_NAME, "E2228T"),
110 },
111 .driver_data = (void *)(long)ACPI_BUTTON_LID_INIT_OPEN,
112 },
113 {
114 /*
115 * Razer Blade Stealth 13 late 2019, notification of the LID device
116 * only happens on close, not on open and _LID always returns closed.
117 */
118 .matches = {
119 DMI_MATCH(DMI_SYS_VENDOR, "Razer"),
120 DMI_MATCH(DMI_PRODUCT_NAME, "Razer Blade Stealth 13 Late 2019"),
121 },
122 .driver_data = (void *)(long)ACPI_BUTTON_LID_INIT_OPEN,
123 },
124 {}
125 };
126
127 static int acpi_button_add(struct acpi_device *device);
128 static int acpi_button_remove(struct acpi_device *device);
129 static void acpi_button_notify(struct acpi_device *device, u32 event);
130
131 #ifdef CONFIG_PM_SLEEP
132 static int acpi_button_suspend(struct device *dev);
133 static int acpi_button_resume(struct device *dev);
134 #else
135 #define acpi_button_suspend NULL
136 #define acpi_button_resume NULL
137 #endif
138 static SIMPLE_DEV_PM_OPS(acpi_button_pm, acpi_button_suspend, acpi_button_resume);
139
140 static struct acpi_driver acpi_button_driver = {
141 .name = "button",
142 .class = ACPI_BUTTON_CLASS,
143 .ids = button_device_ids,
144 .ops = {
145 .add = acpi_button_add,
146 .remove = acpi_button_remove,
147 .notify = acpi_button_notify,
148 },
149 .drv.pm = &acpi_button_pm,
150 };
151
152 struct acpi_button {
153 unsigned int type;
154 struct input_dev *input;
155 char phys[32]; /* for input device */
156 unsigned long pushed;
157 int last_state;
158 ktime_t last_time;
159 bool suspended;
160 bool lid_state_initialized;
161 };
162
163 static struct acpi_device *lid_device;
164 static long lid_init_state = -1;
165
166 static unsigned long lid_report_interval __read_mostly = 500;
167 module_param(lid_report_interval, ulong, 0644);
168 MODULE_PARM_DESC(lid_report_interval, "Interval (ms) between lid key events");
169
170 /* FS Interface (/proc) */
171 static struct proc_dir_entry *acpi_button_dir;
172 static struct proc_dir_entry *acpi_lid_dir;
173
acpi_lid_evaluate_state(struct acpi_device * device)174 static int acpi_lid_evaluate_state(struct acpi_device *device)
175 {
176 unsigned long long lid_state;
177 acpi_status status;
178
179 status = acpi_evaluate_integer(device->handle, "_LID", NULL, &lid_state);
180 if (ACPI_FAILURE(status))
181 return -ENODEV;
182
183 return lid_state ? 1 : 0;
184 }
185
acpi_lid_notify_state(struct acpi_device * device,int state)186 static int acpi_lid_notify_state(struct acpi_device *device, int state)
187 {
188 struct acpi_button *button = acpi_driver_data(device);
189 ktime_t next_report;
190 bool do_update;
191
192 /*
193 * In lid_init_state=ignore mode, if user opens/closes lid
194 * frequently with "open" missing, and "last_time" is also updated
195 * frequently, "close" cannot be delivered to the userspace.
196 * So "last_time" is only updated after a timeout or an actual
197 * switch.
198 */
199 if (lid_init_state != ACPI_BUTTON_LID_INIT_IGNORE ||
200 button->last_state != !!state)
201 do_update = true;
202 else
203 do_update = false;
204
205 next_report = ktime_add(button->last_time,
206 ms_to_ktime(lid_report_interval));
207 if (button->last_state == !!state &&
208 ktime_after(ktime_get(), next_report)) {
209 /* Complain the buggy firmware */
210 pr_warn_once("The lid device is not compliant to SW_LID.\n");
211
212 /*
213 * Send the unreliable complement switch event:
214 *
215 * On most platforms, the lid device is reliable. However
216 * there are exceptions:
217 * 1. Platforms returning initial lid state as "close" by
218 * default after booting/resuming:
219 * https://bugzilla.kernel.org/show_bug.cgi?id=89211
220 * https://bugzilla.kernel.org/show_bug.cgi?id=106151
221 * 2. Platforms never reporting "open" events:
222 * https://bugzilla.kernel.org/show_bug.cgi?id=106941
223 * On these buggy platforms, the usage model of the ACPI
224 * lid device actually is:
225 * 1. The initial returning value of _LID may not be
226 * reliable.
227 * 2. The open event may not be reliable.
228 * 3. The close event is reliable.
229 *
230 * But SW_LID is typed as input switch event, the input
231 * layer checks if the event is redundant. Hence if the
232 * state is not switched, the userspace cannot see this
233 * platform triggered reliable event. By inserting a
234 * complement switch event, it then is guaranteed that the
235 * platform triggered reliable one can always be seen by
236 * the userspace.
237 */
238 if (lid_init_state == ACPI_BUTTON_LID_INIT_IGNORE) {
239 do_update = true;
240 /*
241 * Do generate complement switch event for "close"
242 * as "close" is reliable and wrong "open" won't
243 * trigger unexpected behaviors.
244 * Do not generate complement switch event for
245 * "open" as "open" is not reliable and wrong
246 * "close" will trigger unexpected behaviors.
247 */
248 if (!state) {
249 input_report_switch(button->input,
250 SW_LID, state);
251 input_sync(button->input);
252 }
253 }
254 }
255 /* Send the platform triggered reliable event */
256 if (do_update) {
257 acpi_handle_debug(device->handle, "ACPI LID %s\n",
258 state ? "open" : "closed");
259 input_report_switch(button->input, SW_LID, !state);
260 input_sync(button->input);
261 button->last_state = !!state;
262 button->last_time = ktime_get();
263 }
264
265 return 0;
266 }
267
acpi_button_state_seq_show(struct seq_file * seq,void * offset)268 static int __maybe_unused acpi_button_state_seq_show(struct seq_file *seq,
269 void *offset)
270 {
271 struct acpi_device *device = seq->private;
272 int state;
273
274 state = acpi_lid_evaluate_state(device);
275 seq_printf(seq, "state: %s\n",
276 state < 0 ? "unsupported" : (state ? "open" : "closed"));
277 return 0;
278 }
279
acpi_button_add_fs(struct acpi_device * device)280 static int acpi_button_add_fs(struct acpi_device *device)
281 {
282 struct acpi_button *button = acpi_driver_data(device);
283 struct proc_dir_entry *entry = NULL;
284 int ret = 0;
285
286 /* procfs I/F for ACPI lid device only */
287 if (button->type != ACPI_BUTTON_TYPE_LID)
288 return 0;
289
290 if (acpi_button_dir || acpi_lid_dir) {
291 pr_info("More than one Lid device found!\n");
292 return -EEXIST;
293 }
294
295 /* create /proc/acpi/button */
296 acpi_button_dir = proc_mkdir(ACPI_BUTTON_CLASS, acpi_root_dir);
297 if (!acpi_button_dir)
298 return -ENODEV;
299
300 /* create /proc/acpi/button/lid */
301 acpi_lid_dir = proc_mkdir(ACPI_BUTTON_SUBCLASS_LID, acpi_button_dir);
302 if (!acpi_lid_dir) {
303 ret = -ENODEV;
304 goto remove_button_dir;
305 }
306
307 /* create /proc/acpi/button/lid/LID/ */
308 acpi_device_dir(device) = proc_mkdir(acpi_device_bid(device), acpi_lid_dir);
309 if (!acpi_device_dir(device)) {
310 ret = -ENODEV;
311 goto remove_lid_dir;
312 }
313
314 /* create /proc/acpi/button/lid/LID/state */
315 entry = proc_create_single_data(ACPI_BUTTON_FILE_STATE, S_IRUGO,
316 acpi_device_dir(device), acpi_button_state_seq_show,
317 device);
318 if (!entry) {
319 ret = -ENODEV;
320 goto remove_dev_dir;
321 }
322
323 done:
324 return ret;
325
326 remove_dev_dir:
327 remove_proc_entry(acpi_device_bid(device),
328 acpi_lid_dir);
329 acpi_device_dir(device) = NULL;
330 remove_lid_dir:
331 remove_proc_entry(ACPI_BUTTON_SUBCLASS_LID, acpi_button_dir);
332 acpi_lid_dir = NULL;
333 remove_button_dir:
334 remove_proc_entry(ACPI_BUTTON_CLASS, acpi_root_dir);
335 acpi_button_dir = NULL;
336 goto done;
337 }
338
acpi_button_remove_fs(struct acpi_device * device)339 static int acpi_button_remove_fs(struct acpi_device *device)
340 {
341 struct acpi_button *button = acpi_driver_data(device);
342
343 if (button->type != ACPI_BUTTON_TYPE_LID)
344 return 0;
345
346 remove_proc_entry(ACPI_BUTTON_FILE_STATE,
347 acpi_device_dir(device));
348 remove_proc_entry(acpi_device_bid(device),
349 acpi_lid_dir);
350 acpi_device_dir(device) = NULL;
351 remove_proc_entry(ACPI_BUTTON_SUBCLASS_LID, acpi_button_dir);
352 acpi_lid_dir = NULL;
353 remove_proc_entry(ACPI_BUTTON_CLASS, acpi_root_dir);
354 acpi_button_dir = NULL;
355
356 return 0;
357 }
358
359 /* Driver Interface */
acpi_lid_open(void)360 int acpi_lid_open(void)
361 {
362 if (!lid_device)
363 return -ENODEV;
364
365 return acpi_lid_evaluate_state(lid_device);
366 }
367 EXPORT_SYMBOL(acpi_lid_open);
368
acpi_lid_update_state(struct acpi_device * device,bool signal_wakeup)369 static int acpi_lid_update_state(struct acpi_device *device,
370 bool signal_wakeup)
371 {
372 int state;
373
374 state = acpi_lid_evaluate_state(device);
375 if (state < 0)
376 return state;
377
378 if (state && signal_wakeup)
379 acpi_pm_wakeup_event(&device->dev);
380
381 return acpi_lid_notify_state(device, state);
382 }
383
acpi_lid_initialize_state(struct acpi_device * device)384 static void acpi_lid_initialize_state(struct acpi_device *device)
385 {
386 struct acpi_button *button = acpi_driver_data(device);
387
388 switch (lid_init_state) {
389 case ACPI_BUTTON_LID_INIT_OPEN:
390 (void)acpi_lid_notify_state(device, 1);
391 break;
392 case ACPI_BUTTON_LID_INIT_METHOD:
393 (void)acpi_lid_update_state(device, false);
394 break;
395 case ACPI_BUTTON_LID_INIT_IGNORE:
396 default:
397 break;
398 }
399
400 button->lid_state_initialized = true;
401 }
402
acpi_button_notify(struct acpi_device * device,u32 event)403 static void acpi_button_notify(struct acpi_device *device, u32 event)
404 {
405 struct acpi_button *button = acpi_driver_data(device);
406 struct input_dev *input;
407
408 switch (event) {
409 case ACPI_FIXED_HARDWARE_EVENT:
410 event = ACPI_BUTTON_NOTIFY_STATUS;
411 fallthrough;
412 case ACPI_BUTTON_NOTIFY_STATUS:
413 input = button->input;
414 if (button->type == ACPI_BUTTON_TYPE_LID) {
415 if (button->lid_state_initialized)
416 acpi_lid_update_state(device, true);
417 } else {
418 int keycode;
419
420 acpi_pm_wakeup_event(&device->dev);
421 if (button->suspended)
422 break;
423
424 keycode = test_bit(KEY_SLEEP, input->keybit) ?
425 KEY_SLEEP : KEY_POWER;
426 input_report_key(input, keycode, 1);
427 input_sync(input);
428 input_report_key(input, keycode, 0);
429 input_sync(input);
430
431 acpi_bus_generate_netlink_event(
432 device->pnp.device_class,
433 dev_name(&device->dev),
434 event, ++button->pushed);
435 }
436 break;
437 default:
438 acpi_handle_debug(device->handle, "Unsupported event [0x%x]\n",
439 event);
440 break;
441 }
442 }
443
444 #ifdef CONFIG_PM_SLEEP
acpi_button_suspend(struct device * dev)445 static int acpi_button_suspend(struct device *dev)
446 {
447 struct acpi_device *device = to_acpi_device(dev);
448 struct acpi_button *button = acpi_driver_data(device);
449
450 button->suspended = true;
451 return 0;
452 }
453
acpi_button_resume(struct device * dev)454 static int acpi_button_resume(struct device *dev)
455 {
456 struct acpi_device *device = to_acpi_device(dev);
457 struct acpi_button *button = acpi_driver_data(device);
458
459 button->suspended = false;
460 if (button->type == ACPI_BUTTON_TYPE_LID) {
461 button->last_state = !!acpi_lid_evaluate_state(device);
462 button->last_time = ktime_get();
463 acpi_lid_initialize_state(device);
464 }
465 return 0;
466 }
467 #endif
468
acpi_lid_input_open(struct input_dev * input)469 static int acpi_lid_input_open(struct input_dev *input)
470 {
471 struct acpi_device *device = input_get_drvdata(input);
472 struct acpi_button *button = acpi_driver_data(device);
473
474 button->last_state = !!acpi_lid_evaluate_state(device);
475 button->last_time = ktime_get();
476 acpi_lid_initialize_state(device);
477
478 return 0;
479 }
480
acpi_button_add(struct acpi_device * device)481 static int acpi_button_add(struct acpi_device *device)
482 {
483 struct acpi_button *button;
484 struct input_dev *input;
485 const char *hid = acpi_device_hid(device);
486 char *name, *class;
487 int error;
488
489 if (!strcmp(hid, ACPI_BUTTON_HID_LID) &&
490 lid_init_state == ACPI_BUTTON_LID_INIT_DISABLED)
491 return -ENODEV;
492
493 button = kzalloc(sizeof(struct acpi_button), GFP_KERNEL);
494 if (!button)
495 return -ENOMEM;
496
497 device->driver_data = button;
498
499 button->input = input = input_allocate_device();
500 if (!input) {
501 error = -ENOMEM;
502 goto err_free_button;
503 }
504
505 name = acpi_device_name(device);
506 class = acpi_device_class(device);
507
508 if (!strcmp(hid, ACPI_BUTTON_HID_POWER) ||
509 !strcmp(hid, ACPI_BUTTON_HID_POWERF)) {
510 button->type = ACPI_BUTTON_TYPE_POWER;
511 strcpy(name, ACPI_BUTTON_DEVICE_NAME_POWER);
512 sprintf(class, "%s/%s",
513 ACPI_BUTTON_CLASS, ACPI_BUTTON_SUBCLASS_POWER);
514 } else if (!strcmp(hid, ACPI_BUTTON_HID_SLEEP) ||
515 !strcmp(hid, ACPI_BUTTON_HID_SLEEPF)) {
516 button->type = ACPI_BUTTON_TYPE_SLEEP;
517 strcpy(name, ACPI_BUTTON_DEVICE_NAME_SLEEP);
518 sprintf(class, "%s/%s",
519 ACPI_BUTTON_CLASS, ACPI_BUTTON_SUBCLASS_SLEEP);
520 } else if (!strcmp(hid, ACPI_BUTTON_HID_LID)) {
521 button->type = ACPI_BUTTON_TYPE_LID;
522 strcpy(name, ACPI_BUTTON_DEVICE_NAME_LID);
523 sprintf(class, "%s/%s",
524 ACPI_BUTTON_CLASS, ACPI_BUTTON_SUBCLASS_LID);
525 input->open = acpi_lid_input_open;
526 } else {
527 pr_info("Unsupported hid [%s]\n", hid);
528 error = -ENODEV;
529 goto err_free_input;
530 }
531
532 error = acpi_button_add_fs(device);
533 if (error)
534 goto err_free_input;
535
536 snprintf(button->phys, sizeof(button->phys), "%s/button/input0", hid);
537
538 input->name = name;
539 input->phys = button->phys;
540 input->id.bustype = BUS_HOST;
541 input->id.product = button->type;
542 input->dev.parent = &device->dev;
543
544 switch (button->type) {
545 case ACPI_BUTTON_TYPE_POWER:
546 input_set_capability(input, EV_KEY, KEY_POWER);
547 break;
548
549 case ACPI_BUTTON_TYPE_SLEEP:
550 input_set_capability(input, EV_KEY, KEY_SLEEP);
551 break;
552
553 case ACPI_BUTTON_TYPE_LID:
554 input_set_capability(input, EV_SW, SW_LID);
555 break;
556 }
557
558 input_set_drvdata(input, device);
559 error = input_register_device(input);
560 if (error)
561 goto err_remove_fs;
562 if (button->type == ACPI_BUTTON_TYPE_LID) {
563 /*
564 * This assumes there's only one lid device, or if there are
565 * more we only care about the last one...
566 */
567 lid_device = device;
568 }
569
570 device_init_wakeup(&device->dev, true);
571 pr_info("%s [%s]\n", name, acpi_device_bid(device));
572 return 0;
573
574 err_remove_fs:
575 acpi_button_remove_fs(device);
576 err_free_input:
577 input_free_device(input);
578 err_free_button:
579 kfree(button);
580 return error;
581 }
582
acpi_button_remove(struct acpi_device * device)583 static int acpi_button_remove(struct acpi_device *device)
584 {
585 struct acpi_button *button = acpi_driver_data(device);
586
587 acpi_button_remove_fs(device);
588 input_unregister_device(button->input);
589 kfree(button);
590 return 0;
591 }
592
param_set_lid_init_state(const char * val,const struct kernel_param * kp)593 static int param_set_lid_init_state(const char *val,
594 const struct kernel_param *kp)
595 {
596 int i;
597
598 i = sysfs_match_string(lid_init_state_str, val);
599 if (i < 0)
600 return i;
601
602 lid_init_state = i;
603 pr_info("Initial lid state set to '%s'\n", lid_init_state_str[i]);
604 return 0;
605 }
606
param_get_lid_init_state(char * buf,const struct kernel_param * kp)607 static int param_get_lid_init_state(char *buf, const struct kernel_param *kp)
608 {
609 int i, c = 0;
610
611 for (i = 0; i < ARRAY_SIZE(lid_init_state_str); i++)
612 if (i == lid_init_state)
613 c += sprintf(buf + c, "[%s] ", lid_init_state_str[i]);
614 else
615 c += sprintf(buf + c, "%s ", lid_init_state_str[i]);
616
617 buf[c - 1] = '\n'; /* Replace the final space with a newline */
618
619 return c;
620 }
621
622 module_param_call(lid_init_state,
623 param_set_lid_init_state, param_get_lid_init_state,
624 NULL, 0644);
625 MODULE_PARM_DESC(lid_init_state, "Behavior for reporting LID initial state");
626
acpi_button_register_driver(struct acpi_driver * driver)627 static int acpi_button_register_driver(struct acpi_driver *driver)
628 {
629 const struct dmi_system_id *dmi_id;
630
631 if (lid_init_state == -1) {
632 dmi_id = dmi_first_match(dmi_lid_quirks);
633 if (dmi_id)
634 lid_init_state = (long)dmi_id->driver_data;
635 else
636 lid_init_state = ACPI_BUTTON_LID_INIT_METHOD;
637 }
638
639 /*
640 * Modules such as nouveau.ko and i915.ko have a link time dependency
641 * on acpi_lid_open(), and would therefore not be loadable on ACPI
642 * capable kernels booted in non-ACPI mode if the return value of
643 * acpi_bus_register_driver() is returned from here with ACPI disabled
644 * when this driver is built as a module.
645 */
646 if (acpi_disabled)
647 return 0;
648
649 return acpi_bus_register_driver(driver);
650 }
651
acpi_button_unregister_driver(struct acpi_driver * driver)652 static void acpi_button_unregister_driver(struct acpi_driver *driver)
653 {
654 if (!acpi_disabled)
655 acpi_bus_unregister_driver(driver);
656 }
657
658 module_driver(acpi_button_driver, acpi_button_register_driver,
659 acpi_button_unregister_driver);
660