apm-emulation.c 17.5 KB
Newer Older
1 2 3 4 5 6 7 8 9
/*
 * 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.
 *
10 11
 * This document is available from Microsoft at:
 *    http://www.microsoft.com/whdc/archive/amp_12.mspx
12 13 14 15
 */
#include <linux/module.h>
#include <linux/poll.h>
#include <linux/slab.h>
16
#include <linux/mutex.h>
17
#include <linux/proc_fs.h>
18
#include <linux/seq_file.h>
19 20 21 22
#include <linux/miscdevice.h>
#include <linux/apm_bios.h>
#include <linux/capability.h>
#include <linux/sched.h>
23
#include <linux/suspend.h>
24
#include <linux/apm-emulation.h>
25
#include <linux/freezer.h>
26 27 28 29 30 31 32 33 34
#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>

/*
Paul Bolle's avatar
Paul Bolle committed
35
 * One option can be changed at boot time as follows:
36 37 38 39 40 41 42 43 44 45 46 47 48 49
 *	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];
};

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
/*
 * 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,
};

99 100 101 102 103 104 105 106 107 108 109
/*
 * 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;
110
	enum apm_suspend_state	suspend_state;
111 112 113 114 115 116 117

	struct apm_queue	queue;
};

/*
 * Local variables
 */
118 119
static atomic_t suspend_acks_pending = ATOMIC_INIT(0);
static atomic_t userspace_notification_inhibit = ATOMIC_INIT(0);
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
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.
 */
257 258
static long
apm_ioctl(struct file *filp, u_int cmd, u_long arg)
259 260 261 262 263 264 265 266 267 268 269 270 271
{
	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;

272 273
		switch (as->suspend_state) {
		case SUSPEND_READ:
274 275 276 277 278 279
			/*
			 * 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;
280
			atomic_dec(&suspend_acks_pending);
281 282 283
			mutex_unlock(&state_lock);

			/*
284 285
			 * suspend_acks_pending changed, the notifier needs to
			 * be woken up for this
286
			 */
287
			wake_up(&apm_suspend_waitqueue);
288 289 290 291

			/*
			 * Wait for the suspend/resume to complete.  If there
			 * are pending acknowledges, we wait here for them.
292 293 294
			 * wait_event_freezable() is interruptible and pending
			 * signal can cause busy looping.  We aren't doing
			 * anything critical, chill a bit on each iteration.
295
			 */
296
			while (wait_event_freezable(apm_suspend_waitqueue,
297
					as->suspend_state != SUSPEND_ACKED))
298
				msleep(10);
299 300 301 302 303 304
			break;
		case SUSPEND_ACKTO:
			as->suspend_result = -ETIMEDOUT;
			mutex_unlock(&state_lock);
			break;
		default:
305 306 307 308 309
			as->suspend_state = SUSPEND_WAIT;
			mutex_unlock(&state_lock);

			/*
			 * Otherwise it is a request to suspend the system.
310 311
			 * Just invoke pm_suspend(), we'll handle it from
			 * there via the notifier.
312
			 */
313
			as->suspend_result = pm_suspend(PM_SUSPEND_MEM);
314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337
		}

		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
338
	 * events are concerned, we no longer exist.
339 340
	 */
	mutex_lock(&state_lock);
341 342 343
	if (as->suspend_state == SUSPEND_PENDING ||
	    as->suspend_state == SUSPEND_READ)
		atomic_dec(&suspend_acks_pending);
344
	mutex_unlock(&state_lock);
345 346

	wake_up(&apm_suspend_waitqueue);
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

	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;
}

379
static const struct file_operations apm_bios_fops = {
380 381 382
	.owner		= THIS_MODULE,
	.read		= apm_read,
	.poll		= apm_poll,
383
	.unlocked_ioctl	= apm_ioctl,
384 385
	.open		= apm_open,
	.release	= apm_release,
386
	.llseek		= noop_llseek,
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
};

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
 */
435
static int proc_apm_show(struct seq_file *m, void *v)
436 437 438 439 440 441 442 443 444 445 446 447 448 449 450 451 452 453 454 455
{
	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;
	}

456
	seq_printf(m, "%s 1.2 0x%02x 0x%02x 0x%02x 0x%02x %d%% %d %s\n",
457 458 459 460 461
		     driver_version, APM_32_BIT_SUPPORT,
		     info.ac_line_status, info.battery_status,
		     info.battery_flag, info.battery_life,
		     info.time, units);

462
	return 0;
463
}
464 465 466 467 468 469 470 471 472 473 474 475 476

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,
};
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
#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:
507
			pm_suspend(PM_SUSPEND_MEM);
508 509 510
			break;

		case APM_CRITICAL_SUSPEND:
511 512 513
			atomic_inc(&userspace_notification_inhibit);
			pm_suspend(PM_SUSPEND_MEM);
			atomic_dec(&userspace_notification_inhibit);
514 515 516 517 518 519 520
			break;
		}
	} while (1);

	return 0;
}

521 522 523 524 525 526
static int apm_suspend_notifier(struct notifier_block *nb,
				unsigned long event,
				void *dummy)
{
	struct apm_user *as;
	int err;
527
	unsigned long apm_event;
528 529 530 531 532 533 534

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

	switch (event) {
	case PM_SUSPEND_PREPARE:
535 536 537
	case PM_HIBERNATION_PREPARE:
		apm_event = (event == PM_SUSPEND_PREPARE) ?
			APM_USER_SUSPEND : APM_USER_HIBERNATION;
538 539 540 541 542 543 544 545 546 547 548 549
		/*
		 * 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);
550
				queue_add_event(&as->queue, apm_event);
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
			}
		}

		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 */
598
		return notifier_from_errno(err);
599 600

	case PM_POST_SUSPEND:
601 602 603
	case PM_POST_HIBERNATION:
		apm_event = (event == PM_POST_SUSPEND) ?
			APM_NORMAL_RESUME : APM_HIBERNATION_RESUME;
604 605 606 607
		/*
		 * Anyone on the APM queues will think we're still suspended.
		 * Send a message so everyone knows we're now awake again.
		 */
608
		queue_event(apm_event);
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

		/*
		 * 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,
};

642 643 644 645 646 647 648 649 650 651 652 653 654
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;
655
		goto out;
656 657 658 659
	}
	wake_up_process(kapmd_tsk);

#ifdef CONFIG_PROC_FS
660
	proc_create("apm", 0, NULL, &apm_proc_fops);
661 662 663
#endif

	ret = misc_register(&apm_device);
664 665
	if (ret)
		goto out_stop;
666

667 668 669 670 671 672 673 674 675 676 677 678
	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:
679 680 681 682 683
	return ret;
}

static void __exit apm_exit(void)
{
684
	unregister_pm_notifier(&apm_notif_block);
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
	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);