aboutsummaryrefslogtreecommitdiff
path: root/drivers/char/apm-emulation.c
blob: f4837a893dfad64dcd0f49b5a73fb61f76b948b6 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
/*
 * bios-less APM driver for ARM Linux
 *  Jamey Hicks <jamey@crl.dec.com>
 *  adapted from the APM BIOS driver for Linux by Stephen Rothwell (sfr@linuxcare.com)
 *
 * APM 1.2 Reference:
 *   Intel Corporation, Microsoft Corporation. Advanced Power Management
 *   (APM) BIOS Interface Specification, Revision 1.2, February 1996.
 *
 * This document is available from Microsoft at:
 *    http://www.microsoft.com/whdc/archive/amp_12.mspx
 */
#include <linux/module.h>
#include <linux/poll.h>
#include <linux/slab.h>
#include <linux/mutex.h>
#include <linux/proc_fs.h>
#include <linux/seq_file.h>
#include <linux/miscdevice.h>
#include <linux/apm_bios.h>
#include <linux/capability.h>
#include <linux/sched.h>
#include <linux/suspend.h>
#include <linux/apm-emulation.h>
#include <linux/freezer.h>
#include <linux/device.h>
#include <linux/kernel.h>
#include <linux/list.h>
#include <linux/init.h>
#include <linux/completion.h>
#include <linux/kthread.h>
#include <linux/delay.h>

#include <asm/system.h>

/*
 * The apm_bios device is one of the misc char devices.
 * This is its minor number.
 */
#define APM_MINOR_DEV	134

/*
 * One option can be changed at boot time as follows:
 *	apm=on/off			enable/disable APM
 */

/*
 * Maximum number of events stored
 */
#define APM_MAX_EVENTS		16

struct apm_queue {
	unsigned int		event_head;
	unsigned int		event_tail;
	apm_event_t		events[APM_MAX_EVENTS];
};

/*
 * thread states (for threads using a writable /dev/apm_bios fd):
 *
 * SUSPEND_NONE:	nothing happening
 * SUSPEND_PENDING:	suspend event queued for thread and pending to be read
 * SUSPEND_READ:	suspend event read, pending acknowledgement
 * SUSPEND_ACKED:	acknowledgement received from thread (via ioctl),
 *			waiting for resume
 * SUSPEND_ACKTO:	acknowledgement timeout
 * SUSPEND_DONE:	thread had acked suspend and is now notified of
 *			resume
 *
 * SUSPEND_WAIT:	this thread invoked suspend and is waiting for resume
 *
 * A thread migrates in one of three paths:
 *	NONE -1-> PENDING -2-> READ -3-> ACKED -4-> DONE -5-> NONE
 *				    -6-> ACKTO -7-> NONE
 *	NONE -8-> WAIT -9-> NONE
 *
 * While in PENDING or READ, the thread is accounted for in the
 * suspend_acks_pending counter.
 *
 * The transitions are invoked as follows:
 *	1: suspend event is signalled from the core PM code
 *	2: the suspend event is read from the fd by the userspace thread
 *	3: userspace thread issues the APM_IOC_SUSPEND ioctl (as ack)
 *	4: core PM code signals that we have resumed
 *	5: APM_IOC_SUSPEND ioctl returns
 *
 *	6: the notifier invoked from the core PM code timed out waiting
 *	   for all relevant threds to enter ACKED state and puts those
 *	   that haven't into ACKTO
 *	7: those threads issue APM_IOC_SUSPEND ioctl too late,
 *	   get an error
 *
 *	8: userspace thread issues the APM_IOC_SUSPEND ioctl (to suspend),
 *	   ioctl code invokes pm_suspend()
 *	9: pm_suspend() returns indicating resume
 */
enum apm_suspend_state {
	SUSPEND_NONE,
	SUSPEND_PENDING,
	SUSPEND_READ,
	SUSPEND_ACKED,
	SUSPEND_ACKTO,
	SUSPEND_WAIT,
	SUSPEND_DONE,
};

/*
 * The per-file APM data
 */
struct apm_user {
	struct list_head	list;

	unsigned int		suser: 1;
	unsigned int		writer: 1;
	unsigned int		reader: 1;

	int			suspend_result;
	enum apm_suspend_state	suspend_state;

	struct apm_queue	queue;
};

/*
 * Local variables
 */
static atomic_t suspend_acks_pending = ATOMIC_INIT(0);
static atomic_t userspace_notification_inhibit = ATOMIC_INIT(0);
static int apm_disabled;
static struct task_struct *kapmd_tsk;

static DECLARE_WAIT_QUEUE_HEAD(apm_waitqueue);
static DECLARE_WAIT_QUEUE_HEAD(apm_suspend_waitqueue);

/*
 * This is a list of everyone who has opened /dev/apm_bios
 */
static DECLARE_RWSEM(user_list_lock);
static LIST_HEAD(apm_user_list);

/*
 * kapmd info.  kapmd provides us a process context to handle
 * "APM" events within - specifically necessary if we're going
 * to be suspending the system.
 */
static DECLARE_WAIT_QUEUE_HEAD(kapmd_wait);
static DEFINE_SPINLOCK(kapmd_queue_lock);
static struct apm_queue kapmd_queue;

static DEFINE_MUTEX(state_lock);

static const char driver_version[] = "1.13";	/* no spaces */



/*
 * Compatibility cruft until the IPAQ people move over to the new
 * interface.
 */
static void __apm_get_power_status(struct apm_power_info *info)
{
}

/*
 * This allows machines to provide their own "apm get power status" function.
 */
void (*apm_get_power_status)(struct apm_power_info *) = __apm_get_power_status;
EXPORT_SYMBOL(apm_get_power_status);


/*
 * APM event queue management.
 */
static inline int queue_empty(struct apm_queue *q)
{
	return q->event_head == q->event_tail;
}

static inline apm_event_t queue_get_event(struct apm_queue *q)
{
	q->event_tail = (q->event_tail + 1) % APM_MAX_EVENTS;
	return q->events[q->event_tail];
}

static void queue_add_event(struct apm_queue *q, apm_event_t event)
{
	q->event_head = (q->event_head + 1) % APM_MAX_EVENTS;
	if (q->event_head == q->event_tail) {
		static int notified;

		if (notified++ == 0)
		    printk(KERN_ERR "apm: an event queue overflowed\n");
		q->event_tail = (q->event_tail + 1) % APM_MAX_EVENTS;
	}
	q->events[q->event_head] = event;
}

static void queue_event(apm_event_t event)
{
	struct apm_user *as;

	down_read(&user_list_lock);
	list_for_each_entry(as, &apm_user_list, list) {
		if (as->reader)
			queue_add_event(&as->queue, event);
	}
	up_read(&user_list_lock);
	wake_up_interruptible(&apm_waitqueue);
}

static ssize_t apm_read(struct file *fp, char __user *buf, size_t count, loff_t *ppos)
{
	struct apm_user *as = fp->private_data;
	apm_event_t event;
	int i = count, ret = 0;

	if (count < sizeof(apm_event_t))
		return -EINVAL;

	if (queue_empty(&as->queue) && fp->f_flags & O_NONBLOCK)
		return -EAGAIN;

	wait_event_interruptible(apm_waitqueue, !queue_empty(&as->queue));

	while ((i >= sizeof(event)) && !queue_empty(&as->queue)) {
		event = queue_get_event(&as->queue);

		ret = -EFAULT;
		if (copy_to_user(buf, &event, sizeof(event)))
			break;

		mutex_lock(&state_lock);
		if (as->suspend_state == SUSPEND_PENDING &&
		    (event == APM_SYS_SUSPEND || event == APM_USER_SUSPEND))
			as->suspend_state = SUSPEND_READ;
		mutex_unlock(&state_lock);

		buf += sizeof(event);
		i -= sizeof(event);
	}

	if (i < count)
		ret = count - i;

	return ret;
}

static unsigned int apm_poll(struct file *fp, poll_table * wait)
{
	struct apm_user *as = fp->private_data;

	poll_wait(fp, &apm_waitqueue, wait);
	return queue_empty(&as->queue) ? 0 : POLLIN | POLLRDNORM;
}

/*
 * apm_ioctl - handle APM ioctl
 *
 * APM_IOC_SUSPEND
 *   This IOCTL is overloaded, and performs two functions.  It is used to:
 *     - initiate a suspend
 *     - acknowledge a suspend read from /dev/apm_bios.
 *   Only when everyone who has opened /dev/apm_bios with write permission
 *   has acknowledge does the actual suspend happen.
 */
static long
apm_ioctl(struct file *filp, u_int cmd, u_long arg)
{
	struct apm_user *as = filp->private_data;
	int err = -EINVAL;

	if (!as->suser || !as->writer)
		return -EPERM;

	switch (cmd) {
	case APM_IOC_SUSPEND:
		mutex_lock(&state_lock);

		as->suspend_result = -EINTR;

		switch (as->suspend_state) {
		case SUSPEND_READ:
			/*
			 * If we read a suspend command from /dev/apm_bios,
			 * then the corresponding APM_IOC_SUSPEND ioctl is
			 * interpreted as an acknowledge.
			 */
			as->suspend_state = SUSPEND_ACKED;
			atomic_dec(&suspend_acks_pending);
			mutex_unlock(&state_lock);

			/*
			 * suspend_acks_pending changed, the notifier needs to
			 * be woken up for this
			 */
			wake_up(&apm_suspend_waitqueue);

			/*
			 * Wait for the suspend/resume to complete.  If there
			 * are pending acknowledges, we wait here for them.
			 * wait_event_freezable() is interruptible and pending
			 * signal can cause busy looping.  We aren't doing
			 * anything critical, chill a bit on each iteration.
			 */
			while (wait_event_freezable(apm_suspend_waitqueue,
					as->suspend_state == SUSPEND_DONE))
				msleep(10);
			break;
		case SUSPEND_ACKTO:
			as->suspend_result = -ETIMEDOUT;
			mutex_unlock(&state_lock);
			break;
		default:
			as->suspend_state = SUSPEND_WAIT;
			mutex_unlock(&state_lock);

			/*
			 * Otherwise it is a request to suspend the system.
			 * Just invoke pm_suspend(), we'll handle it from
			 * there via the notifier.
			 */
			as->suspend_result = pm_suspend(PM_SUSPEND_MEM);
		}

		mutex_lock(&state_lock);
		err = as->suspend_result;
		as->suspend_state = SUSPEND_NONE;
		mutex_unlock(&state_lock);
		break;
	}

	return err;
}

static int apm_release(struct inode * inode, struct file * filp)
{
	struct apm_user *as = filp->private_data;

	filp->private_data = NULL;

	down_write(&user_list_lock);
	list_del(&as->list);
	up_write(&user_list_lock);

	/*
	 * We are now unhooked from the chain.  As far as new
	 * events are concerned, we no longer exist.
	 */
	mutex_lock(&state_lock);
	if (as->suspend_state == SUSPEND_PENDING ||
	    as->suspend_state == SUSPEND_READ)
		atomic_dec(&suspend_acks_pending);
	mutex_unlock(&state_lock);

	wake_up(&apm_suspend_waitqueue);

	kfree(as);
	return 0;
}

static int apm_open(struct inode * inode, struct file * filp)
{
	struct apm_user *as;

	as = kzalloc(sizeof(*as), GFP_KERNEL);
	if (as) {
		/*
		 * XXX - this is a tiny bit broken, when we consider BSD
		 * process accounting. If the device is opened by root, we
		 * instantly flag that we used superuser privs. Who knows,
		 * we might close the device immediately without doing a
		 * privileged operation -- cevans
		 */
		as->suser = capable(CAP_SYS_ADMIN);
		as->writer = (filp->f_mode & FMODE_WRITE) == FMODE_WRITE;
		as->reader = (filp->f_mode & FMODE_READ) == FMODE_READ;

		down_write(&user_list_lock);
		list_add(&as->list, &apm_user_list);
		up_write(&user_list_lock);

		filp->private_data = as;
	}

	return as ? 0 : -ENOMEM;
}

static const struct file_operations apm_bios_fops = {
	.owner		= THIS_MODULE,
	.read		= apm_read,
	.poll		= apm_poll,
	.unlocked_ioctl	= apm_ioctl,
	.open		= apm_open,
	.release	= apm_release,
	.llseek		= noop_llseek,
};

static struct miscdevice apm_device = {
	.minor		= APM_MINOR_DEV,
	.name		= "apm_bios",
	.fops		= &apm_bios_fops
};


#ifdef CONFIG_PROC_FS
/*
 * Arguments, with symbols from linux/apm_bios.h.
 *
 *   0) Linux driver version (this will change if format changes)
 *   1) APM BIOS Version.  Usually 1.0, 1.1 or 1.2.
 *   2) APM flags from APM Installation Check (0x00):
 *	bit 0: APM_16_BIT_SUPPORT
 *	bit 1: APM_32_BIT_SUPPORT
 *	bit 2: APM_IDLE_SLOWS_CLOCK
 *	bit 3: APM_BIOS_DISABLED
 *	bit 4: APM_BIOS_DISENGAGED
 *   3) AC line status
 *	0x00: Off-line
 *	0x01: On-line
 *	0x02: On backup power (BIOS >= 1.1 only)
 *	0xff: Unknown
 *   4) Battery status
 *	0x00: High
 *	0x01: Low
 *	0x02: Critical
 *	0x03: Charging
 *	0x04: Selected battery not present (BIOS >= 1.2 only)
 *	0xff: Unknown
 *   5) Battery flag
 *	bit 0: High
 *	bit 1: Low
 *	bit 2: Critical
 *	bit 3: Charging
 *	bit 7: No system battery
 *	0xff: Unknown
 *   6) Remaining battery life (percentage of charge):
 *	0-100: valid
 *	-1: Unknown
 *   7) Remaining battery life (time units):
 *	Number of remaining minutes or seconds
 *	-1: Unknown
 *   8) min = minutes; sec = seconds
 */
static int proc_apm_show(struct seq_file *m, void *v)
{
	struct apm_power_info info;
	char *units;

	info.ac_line_status = 0xff;
	info.battery_status = 0xff;
	info.battery_flag   = 0xff;
	info.battery_life   = -1;
	info.time	    = -1;
	info.units	    = -1;

	if (apm_get_power_status)
		apm_get_power_status(&info);

	switch (info.units) {
	default:	units = "?";	break;
	case 0: 	units = "min";	break;
	case 1: 	units = "sec";	break;
	}

	seq_printf(m, "%s 1.2 0x%02x 0x%02x 0x%02x 0x%02x %d%% %d %s\n",
		     driver_version, APM_32_BIT_SUPPORT,
		     info.ac_line_status, info.battery_status,
		     info.battery_flag, info.battery_life,
		     info.time, units);

	return 0;
}

static int proc_apm_open(struct inode *inode, struct file *file)
{
	return single_open(file, proc_apm_show, NULL);
}

static const struct file_operations apm_proc_fops = {
	.owner		= THIS_MODULE,
	.open		= proc_apm_open,
	.read		= seq_read,
	.llseek		= seq_lseek,
	.release	= single_release,
};
#endif

static int kapmd(void *arg)
{
	do {
		apm_event_t event;

		wait_event_interruptible(kapmd_wait,
				!queue_empty(&kapmd_queue) || kthread_should_stop());

		if (kthread_should_stop())
			break;

		spin_lock_irq(&kapmd_queue_lock);
		event = 0;
		if (!queue_empty(&kapmd_queue))
			event = queue_get_event(&kapmd_queue);
		spin_unlock_irq(&kapmd_queue_lock);

		switch (event) {
		case 0:
			break;

		case APM_LOW_BATTERY:
		case APM_POWER_STATUS_CHANGE:
			queue_event(event);
			break;

		case APM_USER_SUSPEND:
		case APM_SYS_SUSPEND:
			pm_suspend(PM_SUSPEND_MEM);
			break;

		case APM_CRITICAL_SUSPEND:
			atomic_inc(&userspace_notification_inhibit);
			pm_suspend(PM_SUSPEND_MEM);
			atomic_dec(&userspace_notification_inhibit);
			break;
		}
	} while (1);

	return 0;
}

static int apm_suspend_notifier(struct notifier_block *nb,
				unsigned long event,
				void *dummy)
{
	struct apm_user *as;
	int err;

	/* short-cut emergency suspends */
	if (atomic_read(&userspace_notification_inhibit))
		return NOTIFY_DONE;

	switch (event) {
	case PM_SUSPEND_PREPARE:
		/*
		 * Queue an event to all "writer" users that we want
		 * to suspend and need their ack.
		 */
		mutex_lock(&state_lock);
		down_read(&user_list_lock);

		list_for_each_entry(as, &apm_user_list, list) {
			if (as->suspend_state != SUSPEND_WAIT && as->reader &&
			    as->writer && as->suser) {
				as->suspend_state = SUSPEND_PENDING;
				atomic_inc(&suspend_acks_pending);
				queue_add_event(&as->queue, APM_USER_SUSPEND);
			}
		}

		up_read(&user_list_lock);
		mutex_unlock(&state_lock);
		wake_up_interruptible(&apm_waitqueue);

		/*
		 * Wait for the the suspend_acks_pending variable to drop to
		 * zero, meaning everybody acked the suspend event (or the
		 * process was killed.)
		 *
		 * If the app won't answer within a short while we assume it
		 * locked up and ignore it.
		 */
		err = wait_event_interruptible_timeout(
			apm_suspend_waitqueue,
			atomic_read(&suspend_acks_pending) == 0,
			5*HZ);

		/* timed out */
		if (err == 0) {
			/*
			 * Move anybody who timed out to "ack timeout" state.
			 *
			 * We could time out and the userspace does the ACK
			 * right after we time out but before we enter the
			 * locked section here, but that's fine.
			 */
			mutex_lock(&state_lock);
			down_read(&user_list_lock);
			list_for_each_entry(as, &apm_user_list, list) {
				if (as->suspend_state == SUSPEND_PENDING ||
				    as->suspend_state == SUSPEND_READ) {
					as->suspend_state = SUSPEND_ACKTO;
					atomic_dec(&suspend_acks_pending);
				}
			}
			up_read(&user_list_lock);
			mutex_unlock(&state_lock);
		}

		/* let suspend proceed */
		if (err >= 0)
			return NOTIFY_OK;

		/* interrupted by signal */
		return notifier_from_errno(err);

	case PM_POST_SUSPEND:
		/*
		 * Anyone on the APM queues will think we're still suspended.
		 * Send a message so everyone knows we're now awake again.
		 */
		queue_event(APM_NORMAL_RESUME);

		/*
		 * Finally, wake up anyone who is sleeping on the suspend.
		 */
		mutex_lock(&state_lock);
		down_read(&user_list_lock);
		list_for_each_entry(as, &apm_user_list, list) {
			if (as->suspend_state == SUSPEND_ACKED) {
				/*
				 * TODO: maybe grab error code, needs core
				 * changes to push the error to the notifier
				 * chain (could use the second parameter if
				 * implemented)
				 */
				as->suspend_result = 0;
				as->suspend_state = SUSPEND_DONE;
			}
		}
		up_read(&user_list_lock);
		mutex_unlock(&state_lock);

		wake_up(&apm_suspend_waitqueue);
		return NOTIFY_OK;

	default:
		return NOTIFY_DONE;
	}
}

static struct notifier_block apm_notif_block = {
	.notifier_call = apm_suspend_notifier,
};

static int __init apm_init(void)
{
	int ret;

	if (apm_disabled) {
		printk(KERN_NOTICE "apm: disabled on user request.\n");
		return -ENODEV;
	}

	kapmd_tsk = kthread_create(kapmd, NULL, "kapmd");
	if (IS_ERR(kapmd_tsk)) {
		ret = PTR_ERR(kapmd_tsk);
		kapmd_tsk = NULL;
		goto out;
	}
	wake_up_process(kapmd_tsk);

#ifdef CONFIG_PROC_FS
	proc_create("apm", 0, NULL, &apm_proc_fops);
#endif

	ret = misc_register(&apm_device);
	if (ret)
		goto out_stop;

	ret = register_pm_notifier(&apm_notif_block);
	if (ret)
		goto out_unregister;

	return 0;

 out_unregister:
	misc_deregister(&apm_device);
 out_stop:
	remove_proc_entry("apm", NULL);
	kthread_stop(kapmd_tsk);
 out:
	return ret;
}

static void __exit apm_exit(void)
{
	unregister_pm_notifier(&apm_notif_block);
	misc_deregister(&apm_device);
	remove_proc_entry("apm", NULL);

	kthread_stop(kapmd_tsk);
}

module_init(apm_init);
module_exit(apm_exit);

MODULE_AUTHOR("Stephen Rothwell");
MODULE_DESCRIPTION("Advanced Power Management");
MODULE_LICENSE("GPL");

#ifndef MODULE
static int __init apm_setup(char *str)
{
	while ((str != NULL) && (*str != '\0')) {
		if (strncmp(str, "off", 3) == 0)
			apm_disabled = 1;
		if (strncmp(str, "on", 2) == 0)
			apm_disabled = 0;
		str = strchr(str, ',');
		if (str != NULL)
			str += strspn(str, ", \t");
	}
	return 1;
}

__setup("apm=", apm_setup);
#endif

/**
 * apm_queue_event - queue an APM event for kapmd
 * @event: APM event
 *
 * Queue an APM event for kapmd to process and ultimately take the
 * appropriate action.  Only a subset of events are handled:
 *   %APM_LOW_BATTERY
 *   %APM_POWER_STATUS_CHANGE
 *   %APM_USER_SUSPEND
 *   %APM_SYS_SUSPEND
 *   %APM_CRITICAL_SUSPEND
 */
void apm_queue_event(apm_event_t event)
{
	unsigned long flags;

	spin_lock_irqsave(&kapmd_queue_lock, flags);
	queue_add_event(&kapmd_queue, event);
	spin_unlock_irqrestore(&kapmd_queue_lock, flags);

	wake_up_interruptible(&kapmd_wait);
}
EXPORT_SYMBOL(apm_queue_event);