1 /*
2  * bios-less APM driver for ARM Linux
3  *  Jamey Hicks <jamey@crl.dec.com>
4  *  adapted from the APM BIOS driver for Linux by Stephen Rothwell (sfr@linuxcare.com)
5  *
6  * APM 1.2 Reference:
7  *   Intel Corporation, Microsoft Corporation. Advanced Power Management
8  *   (APM) BIOS Interface Specification, Revision 1.2, February 1996.
9  *
10  * This document is available from Microsoft at:
11  *    http://www.microsoft.com/whdc/archive/amp_12.mspx
12  */
13 #include <linux/module.h>
14 #include <linux/poll.h>
15 #include <linux/slab.h>
16 #include <linux/mutex.h>
17 #include <linux/proc_fs.h>
18 #include <linux/seq_file.h>
19 #include <linux/miscdevice.h>
20 #include <linux/apm_bios.h>
21 #include <linux/capability.h>
22 #include <linux/sched.h>
23 #include <linux/suspend.h>
24 #include <linux/apm-emulation.h>
25 #include <linux/freezer.h>
26 #include <linux/device.h>
27 #include <linux/kernel.h>
28 #include <linux/list.h>
29 #include <linux/init.h>
30 #include <linux/completion.h>
31 #include <linux/kthread.h>
32 #include <linux/delay.h>
33 
34 /*
35  * One option can be changed at boot time as follows:
36  *	apm=on/off			enable/disable APM
37  */
38 
39 /*
40  * Maximum number of events stored
41  */
42 #define APM_MAX_EVENTS		16
43 
44 struct apm_queue {
45 	unsigned int		event_head;
46 	unsigned int		event_tail;
47 	apm_event_t		events[APM_MAX_EVENTS];
48 };
49 
50 /*
51  * thread states (for threads using a writable /dev/apm_bios fd):
52  *
53  * SUSPEND_NONE:	nothing happening
54  * SUSPEND_PENDING:	suspend event queued for thread and pending to be read
55  * SUSPEND_READ:	suspend event read, pending acknowledgement
56  * SUSPEND_ACKED:	acknowledgement received from thread (via ioctl),
57  *			waiting for resume
58  * SUSPEND_ACKTO:	acknowledgement timeout
59  * SUSPEND_DONE:	thread had acked suspend and is now notified of
60  *			resume
61  *
62  * SUSPEND_WAIT:	this thread invoked suspend and is waiting for resume
63  *
64  * A thread migrates in one of three paths:
65  *	NONE -1-> PENDING -2-> READ -3-> ACKED -4-> DONE -5-> NONE
66  *				    -6-> ACKTO -7-> NONE
67  *	NONE -8-> WAIT -9-> NONE
68  *
69  * While in PENDING or READ, the thread is accounted for in the
70  * suspend_acks_pending counter.
71  *
72  * The transitions are invoked as follows:
73  *	1: suspend event is signalled from the core PM code
74  *	2: the suspend event is read from the fd by the userspace thread
75  *	3: userspace thread issues the APM_IOC_SUSPEND ioctl (as ack)
76  *	4: core PM code signals that we have resumed
77  *	5: APM_IOC_SUSPEND ioctl returns
78  *
79  *	6: the notifier invoked from the core PM code timed out waiting
80  *	   for all relevant threds to enter ACKED state and puts those
81  *	   that haven't into ACKTO
82  *	7: those threads issue APM_IOC_SUSPEND ioctl too late,
83  *	   get an error
84  *
85  *	8: userspace thread issues the APM_IOC_SUSPEND ioctl (to suspend),
86  *	   ioctl code invokes pm_suspend()
87  *	9: pm_suspend() returns indicating resume
88  */
89 enum apm_suspend_state {
90 	SUSPEND_NONE,
91 	SUSPEND_PENDING,
92 	SUSPEND_READ,
93 	SUSPEND_ACKED,
94 	SUSPEND_ACKTO,
95 	SUSPEND_WAIT,
96 	SUSPEND_DONE,
97 };
98 
99 /*
100  * The per-file APM data
101  */
102 struct apm_user {
103 	struct list_head	list;
104 
105 	unsigned int		suser: 1;
106 	unsigned int		writer: 1;
107 	unsigned int		reader: 1;
108 
109 	int			suspend_result;
110 	enum apm_suspend_state	suspend_state;
111 
112 	struct apm_queue	queue;
113 };
114 
115 /*
116  * Local variables
117  */
118 static atomic_t suspend_acks_pending = ATOMIC_INIT(0);
119 static atomic_t userspace_notification_inhibit = ATOMIC_INIT(0);
120 static int apm_disabled;
121 static struct task_struct *kapmd_tsk;
122 
123 static DECLARE_WAIT_QUEUE_HEAD(apm_waitqueue);
124 static DECLARE_WAIT_QUEUE_HEAD(apm_suspend_waitqueue);
125 
126 /*
127  * This is a list of everyone who has opened /dev/apm_bios
128  */
129 static DECLARE_RWSEM(user_list_lock);
130 static LIST_HEAD(apm_user_list);
131 
132 /*
133  * kapmd info.  kapmd provides us a process context to handle
134  * "APM" events within - specifically necessary if we're going
135  * to be suspending the system.
136  */
137 static DECLARE_WAIT_QUEUE_HEAD(kapmd_wait);
138 static DEFINE_SPINLOCK(kapmd_queue_lock);
139 static struct apm_queue kapmd_queue;
140 
141 static DEFINE_MUTEX(state_lock);
142 
143 static const char driver_version[] = "1.13";	/* no spaces */
144 
145 
146 
147 /*
148  * Compatibility cruft until the IPAQ people move over to the new
149  * interface.
150  */
__apm_get_power_status(struct apm_power_info * info)151 static void __apm_get_power_status(struct apm_power_info *info)
152 {
153 }
154 
155 /*
156  * This allows machines to provide their own "apm get power status" function.
157  */
158 void (*apm_get_power_status)(struct apm_power_info *) = __apm_get_power_status;
159 EXPORT_SYMBOL(apm_get_power_status);
160 
161 
162 /*
163  * APM event queue management.
164  */
queue_empty(struct apm_queue * q)165 static inline int queue_empty(struct apm_queue *q)
166 {
167 	return q->event_head == q->event_tail;
168 }
169 
queue_get_event(struct apm_queue * q)170 static inline apm_event_t queue_get_event(struct apm_queue *q)
171 {
172 	q->event_tail = (q->event_tail + 1) % APM_MAX_EVENTS;
173 	return q->events[q->event_tail];
174 }
175 
queue_add_event(struct apm_queue * q,apm_event_t event)176 static void queue_add_event(struct apm_queue *q, apm_event_t event)
177 {
178 	q->event_head = (q->event_head + 1) % APM_MAX_EVENTS;
179 	if (q->event_head == q->event_tail) {
180 		static int notified;
181 
182 		if (notified++ == 0)
183 		    printk(KERN_ERR "apm: an event queue overflowed\n");
184 		q->event_tail = (q->event_tail + 1) % APM_MAX_EVENTS;
185 	}
186 	q->events[q->event_head] = event;
187 }
188 
queue_event(apm_event_t event)189 static void queue_event(apm_event_t event)
190 {
191 	struct apm_user *as;
192 
193 	down_read(&user_list_lock);
194 	list_for_each_entry(as, &apm_user_list, list) {
195 		if (as->reader)
196 			queue_add_event(&as->queue, event);
197 	}
198 	up_read(&user_list_lock);
199 	wake_up_interruptible(&apm_waitqueue);
200 }
201 
apm_read(struct file * fp,char __user * buf,size_t count,loff_t * ppos)202 static ssize_t apm_read(struct file *fp, char __user *buf, size_t count, loff_t *ppos)
203 {
204 	struct apm_user *as = fp->private_data;
205 	apm_event_t event;
206 	int i = count, ret = 0;
207 
208 	if (count < sizeof(apm_event_t))
209 		return -EINVAL;
210 
211 	if (queue_empty(&as->queue) && fp->f_flags & O_NONBLOCK)
212 		return -EAGAIN;
213 
214 	wait_event_interruptible(apm_waitqueue, !queue_empty(&as->queue));
215 
216 	while ((i >= sizeof(event)) && !queue_empty(&as->queue)) {
217 		event = queue_get_event(&as->queue);
218 
219 		ret = -EFAULT;
220 		if (copy_to_user(buf, &event, sizeof(event)))
221 			break;
222 
223 		mutex_lock(&state_lock);
224 		if (as->suspend_state == SUSPEND_PENDING &&
225 		    (event == APM_SYS_SUSPEND || event == APM_USER_SUSPEND))
226 			as->suspend_state = SUSPEND_READ;
227 		mutex_unlock(&state_lock);
228 
229 		buf += sizeof(event);
230 		i -= sizeof(event);
231 	}
232 
233 	if (i < count)
234 		ret = count - i;
235 
236 	return ret;
237 }
238 
apm_poll(struct file * fp,poll_table * wait)239 static __poll_t apm_poll(struct file *fp, poll_table * wait)
240 {
241 	struct apm_user *as = fp->private_data;
242 
243 	poll_wait(fp, &apm_waitqueue, wait);
244 	return queue_empty(&as->queue) ? 0 : EPOLLIN | EPOLLRDNORM;
245 }
246 
247 /*
248  * apm_ioctl - handle APM ioctl
249  *
250  * APM_IOC_SUSPEND
251  *   This IOCTL is overloaded, and performs two functions.  It is used to:
252  *     - initiate a suspend
253  *     - acknowledge a suspend read from /dev/apm_bios.
254  *   Only when everyone who has opened /dev/apm_bios with write permission
255  *   has acknowledge does the actual suspend happen.
256  */
257 static long
apm_ioctl(struct file * filp,u_int cmd,u_long arg)258 apm_ioctl(struct file *filp, u_int cmd, u_long arg)
259 {
260 	struct apm_user *as = filp->private_data;
261 	int err = -EINVAL;
262 
263 	if (!as->suser || !as->writer)
264 		return -EPERM;
265 
266 	switch (cmd) {
267 	case APM_IOC_SUSPEND:
268 		mutex_lock(&state_lock);
269 
270 		as->suspend_result = -EINTR;
271 
272 		switch (as->suspend_state) {
273 		case SUSPEND_READ:
274 			/*
275 			 * If we read a suspend command from /dev/apm_bios,
276 			 * then the corresponding APM_IOC_SUSPEND ioctl is
277 			 * interpreted as an acknowledge.
278 			 */
279 			as->suspend_state = SUSPEND_ACKED;
280 			atomic_dec(&suspend_acks_pending);
281 			mutex_unlock(&state_lock);
282 
283 			/*
284 			 * suspend_acks_pending changed, the notifier needs to
285 			 * be woken up for this
286 			 */
287 			wake_up(&apm_suspend_waitqueue);
288 
289 			/*
290 			 * Wait for the suspend/resume to complete.  If there
291 			 * are pending acknowledges, we wait here for them.
292 			 * wait_event_freezable() is interruptible and pending
293 			 * signal can cause busy looping.  We aren't doing
294 			 * 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 			break;
300 		case SUSPEND_ACKTO:
301 			as->suspend_result = -ETIMEDOUT;
302 			mutex_unlock(&state_lock);
303 			break;
304 		default:
305 			as->suspend_state = SUSPEND_WAIT;
306 			mutex_unlock(&state_lock);
307 
308 			/*
309 			 * Otherwise it is a request to suspend the system.
310 			 * Just invoke pm_suspend(), we'll handle it from
311 			 * there via the notifier.
312 			 */
313 			as->suspend_result = pm_suspend(PM_SUSPEND_MEM);
314 		}
315 
316 		mutex_lock(&state_lock);
317 		err = as->suspend_result;
318 		as->suspend_state = SUSPEND_NONE;
319 		mutex_unlock(&state_lock);
320 		break;
321 	}
322 
323 	return err;
324 }
325 
apm_release(struct inode * inode,struct file * filp)326 static int apm_release(struct inode * inode, struct file * filp)
327 {
328 	struct apm_user *as = filp->private_data;
329 
330 	filp->private_data = NULL;
331 
332 	down_write(&user_list_lock);
333 	list_del(&as->list);
334 	up_write(&user_list_lock);
335 
336 	/*
337 	 * 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 	if (as->suspend_state == SUSPEND_PENDING ||
342 	    as->suspend_state == SUSPEND_READ)
343 		atomic_dec(&suspend_acks_pending);
344 	mutex_unlock(&state_lock);
345 
346 	wake_up(&apm_suspend_waitqueue);
347 
348 	kfree(as);
349 	return 0;
350 }
351 
apm_open(struct inode * inode,struct file * filp)352 static int apm_open(struct inode * inode, struct file * filp)
353 {
354 	struct apm_user *as;
355 
356 	as = kzalloc(sizeof(*as), GFP_KERNEL);
357 	if (as) {
358 		/*
359 		 * XXX - this is a tiny bit broken, when we consider BSD
360 		 * process accounting. If the device is opened by root, we
361 		 * instantly flag that we used superuser privs. Who knows,
362 		 * we might close the device immediately without doing a
363 		 * privileged operation -- cevans
364 		 */
365 		as->suser = capable(CAP_SYS_ADMIN);
366 		as->writer = (filp->f_mode & FMODE_WRITE) == FMODE_WRITE;
367 		as->reader = (filp->f_mode & FMODE_READ) == FMODE_READ;
368 
369 		down_write(&user_list_lock);
370 		list_add(&as->list, &apm_user_list);
371 		up_write(&user_list_lock);
372 
373 		filp->private_data = as;
374 	}
375 
376 	return as ? 0 : -ENOMEM;
377 }
378 
379 static const struct file_operations apm_bios_fops = {
380 	.owner		= THIS_MODULE,
381 	.read		= apm_read,
382 	.poll		= apm_poll,
383 	.unlocked_ioctl	= apm_ioctl,
384 	.open		= apm_open,
385 	.release	= apm_release,
386 	.llseek		= noop_llseek,
387 };
388 
389 static struct miscdevice apm_device = {
390 	.minor		= APM_MINOR_DEV,
391 	.name		= "apm_bios",
392 	.fops		= &apm_bios_fops
393 };
394 
395 
396 #ifdef CONFIG_PROC_FS
397 /*
398  * Arguments, with symbols from linux/apm_bios.h.
399  *
400  *   0) Linux driver version (this will change if format changes)
401  *   1) APM BIOS Version.  Usually 1.0, 1.1 or 1.2.
402  *   2) APM flags from APM Installation Check (0x00):
403  *	bit 0: APM_16_BIT_SUPPORT
404  *	bit 1: APM_32_BIT_SUPPORT
405  *	bit 2: APM_IDLE_SLOWS_CLOCK
406  *	bit 3: APM_BIOS_DISABLED
407  *	bit 4: APM_BIOS_DISENGAGED
408  *   3) AC line status
409  *	0x00: Off-line
410  *	0x01: On-line
411  *	0x02: On backup power (BIOS >= 1.1 only)
412  *	0xff: Unknown
413  *   4) Battery status
414  *	0x00: High
415  *	0x01: Low
416  *	0x02: Critical
417  *	0x03: Charging
418  *	0x04: Selected battery not present (BIOS >= 1.2 only)
419  *	0xff: Unknown
420  *   5) Battery flag
421  *	bit 0: High
422  *	bit 1: Low
423  *	bit 2: Critical
424  *	bit 3: Charging
425  *	bit 7: No system battery
426  *	0xff: Unknown
427  *   6) Remaining battery life (percentage of charge):
428  *	0-100: valid
429  *	-1: Unknown
430  *   7) Remaining battery life (time units):
431  *	Number of remaining minutes or seconds
432  *	-1: Unknown
433  *   8) min = minutes; sec = seconds
434  */
proc_apm_show(struct seq_file * m,void * v)435 static int proc_apm_show(struct seq_file *m, void *v)
436 {
437 	struct apm_power_info info;
438 	char *units;
439 
440 	info.ac_line_status = 0xff;
441 	info.battery_status = 0xff;
442 	info.battery_flag   = 0xff;
443 	info.battery_life   = -1;
444 	info.time	    = -1;
445 	info.units	    = -1;
446 
447 	if (apm_get_power_status)
448 		apm_get_power_status(&info);
449 
450 	switch (info.units) {
451 	default:	units = "?";	break;
452 	case 0: 	units = "min";	break;
453 	case 1: 	units = "sec";	break;
454 	}
455 
456 	seq_printf(m, "%s 1.2 0x%02x 0x%02x 0x%02x 0x%02x %d%% %d %s\n",
457 		     driver_version, APM_32_BIT_SUPPORT,
458 		     info.ac_line_status, info.battery_status,
459 		     info.battery_flag, info.battery_life,
460 		     info.time, units);
461 
462 	return 0;
463 }
464 #endif
465 
kapmd(void * arg)466 static int kapmd(void *arg)
467 {
468 	do {
469 		apm_event_t event;
470 
471 		wait_event_interruptible(kapmd_wait,
472 				!queue_empty(&kapmd_queue) || kthread_should_stop());
473 
474 		if (kthread_should_stop())
475 			break;
476 
477 		spin_lock_irq(&kapmd_queue_lock);
478 		event = 0;
479 		if (!queue_empty(&kapmd_queue))
480 			event = queue_get_event(&kapmd_queue);
481 		spin_unlock_irq(&kapmd_queue_lock);
482 
483 		switch (event) {
484 		case 0:
485 			break;
486 
487 		case APM_LOW_BATTERY:
488 		case APM_POWER_STATUS_CHANGE:
489 			queue_event(event);
490 			break;
491 
492 		case APM_USER_SUSPEND:
493 		case APM_SYS_SUSPEND:
494 			pm_suspend(PM_SUSPEND_MEM);
495 			break;
496 
497 		case APM_CRITICAL_SUSPEND:
498 			atomic_inc(&userspace_notification_inhibit);
499 			pm_suspend(PM_SUSPEND_MEM);
500 			atomic_dec(&userspace_notification_inhibit);
501 			break;
502 		}
503 	} while (1);
504 
505 	return 0;
506 }
507 
apm_suspend_notifier(struct notifier_block * nb,unsigned long event,void * dummy)508 static int apm_suspend_notifier(struct notifier_block *nb,
509 				unsigned long event,
510 				void *dummy)
511 {
512 	struct apm_user *as;
513 	int err;
514 	unsigned long apm_event;
515 
516 	/* short-cut emergency suspends */
517 	if (atomic_read(&userspace_notification_inhibit))
518 		return NOTIFY_DONE;
519 
520 	switch (event) {
521 	case PM_SUSPEND_PREPARE:
522 	case PM_HIBERNATION_PREPARE:
523 		apm_event = (event == PM_SUSPEND_PREPARE) ?
524 			APM_USER_SUSPEND : APM_USER_HIBERNATION;
525 		/*
526 		 * Queue an event to all "writer" users that we want
527 		 * to suspend and need their ack.
528 		 */
529 		mutex_lock(&state_lock);
530 		down_read(&user_list_lock);
531 
532 		list_for_each_entry(as, &apm_user_list, list) {
533 			if (as->suspend_state != SUSPEND_WAIT && as->reader &&
534 			    as->writer && as->suser) {
535 				as->suspend_state = SUSPEND_PENDING;
536 				atomic_inc(&suspend_acks_pending);
537 				queue_add_event(&as->queue, apm_event);
538 			}
539 		}
540 
541 		up_read(&user_list_lock);
542 		mutex_unlock(&state_lock);
543 		wake_up_interruptible(&apm_waitqueue);
544 
545 		/*
546 		 * Wait for the the suspend_acks_pending variable to drop to
547 		 * zero, meaning everybody acked the suspend event (or the
548 		 * process was killed.)
549 		 *
550 		 * If the app won't answer within a short while we assume it
551 		 * locked up and ignore it.
552 		 */
553 		err = wait_event_interruptible_timeout(
554 			apm_suspend_waitqueue,
555 			atomic_read(&suspend_acks_pending) == 0,
556 			5*HZ);
557 
558 		/* timed out */
559 		if (err == 0) {
560 			/*
561 			 * Move anybody who timed out to "ack timeout" state.
562 			 *
563 			 * We could time out and the userspace does the ACK
564 			 * right after we time out but before we enter the
565 			 * locked section here, but that's fine.
566 			 */
567 			mutex_lock(&state_lock);
568 			down_read(&user_list_lock);
569 			list_for_each_entry(as, &apm_user_list, list) {
570 				if (as->suspend_state == SUSPEND_PENDING ||
571 				    as->suspend_state == SUSPEND_READ) {
572 					as->suspend_state = SUSPEND_ACKTO;
573 					atomic_dec(&suspend_acks_pending);
574 				}
575 			}
576 			up_read(&user_list_lock);
577 			mutex_unlock(&state_lock);
578 		}
579 
580 		/* let suspend proceed */
581 		if (err >= 0)
582 			return NOTIFY_OK;
583 
584 		/* interrupted by signal */
585 		return notifier_from_errno(err);
586 
587 	case PM_POST_SUSPEND:
588 	case PM_POST_HIBERNATION:
589 		apm_event = (event == PM_POST_SUSPEND) ?
590 			APM_NORMAL_RESUME : APM_HIBERNATION_RESUME;
591 		/*
592 		 * Anyone on the APM queues will think we're still suspended.
593 		 * Send a message so everyone knows we're now awake again.
594 		 */
595 		queue_event(apm_event);
596 
597 		/*
598 		 * Finally, wake up anyone who is sleeping on the suspend.
599 		 */
600 		mutex_lock(&state_lock);
601 		down_read(&user_list_lock);
602 		list_for_each_entry(as, &apm_user_list, list) {
603 			if (as->suspend_state == SUSPEND_ACKED) {
604 				/*
605 				 * TODO: maybe grab error code, needs core
606 				 * changes to push the error to the notifier
607 				 * chain (could use the second parameter if
608 				 * implemented)
609 				 */
610 				as->suspend_result = 0;
611 				as->suspend_state = SUSPEND_DONE;
612 			}
613 		}
614 		up_read(&user_list_lock);
615 		mutex_unlock(&state_lock);
616 
617 		wake_up(&apm_suspend_waitqueue);
618 		return NOTIFY_OK;
619 
620 	default:
621 		return NOTIFY_DONE;
622 	}
623 }
624 
625 static struct notifier_block apm_notif_block = {
626 	.notifier_call = apm_suspend_notifier,
627 };
628 
apm_init(void)629 static int __init apm_init(void)
630 {
631 	int ret;
632 
633 	if (apm_disabled) {
634 		printk(KERN_NOTICE "apm: disabled on user request.\n");
635 		return -ENODEV;
636 	}
637 
638 	kapmd_tsk = kthread_create(kapmd, NULL, "kapmd");
639 	if (IS_ERR(kapmd_tsk)) {
640 		ret = PTR_ERR(kapmd_tsk);
641 		kapmd_tsk = NULL;
642 		goto out;
643 	}
644 	wake_up_process(kapmd_tsk);
645 
646 #ifdef CONFIG_PROC_FS
647 	proc_create_single("apm", 0, NULL, proc_apm_show);
648 #endif
649 
650 	ret = misc_register(&apm_device);
651 	if (ret)
652 		goto out_stop;
653 
654 	ret = register_pm_notifier(&apm_notif_block);
655 	if (ret)
656 		goto out_unregister;
657 
658 	return 0;
659 
660  out_unregister:
661 	misc_deregister(&apm_device);
662  out_stop:
663 	remove_proc_entry("apm", NULL);
664 	kthread_stop(kapmd_tsk);
665  out:
666 	return ret;
667 }
668 
apm_exit(void)669 static void __exit apm_exit(void)
670 {
671 	unregister_pm_notifier(&apm_notif_block);
672 	misc_deregister(&apm_device);
673 	remove_proc_entry("apm", NULL);
674 
675 	kthread_stop(kapmd_tsk);
676 }
677 
678 module_init(apm_init);
679 module_exit(apm_exit);
680 
681 MODULE_AUTHOR("Stephen Rothwell");
682 MODULE_DESCRIPTION("Advanced Power Management");
683 MODULE_LICENSE("GPL");
684 
685 #ifndef MODULE
apm_setup(char * str)686 static int __init apm_setup(char *str)
687 {
688 	while ((str != NULL) && (*str != '\0')) {
689 		if (strncmp(str, "off", 3) == 0)
690 			apm_disabled = 1;
691 		if (strncmp(str, "on", 2) == 0)
692 			apm_disabled = 0;
693 		str = strchr(str, ',');
694 		if (str != NULL)
695 			str += strspn(str, ", \t");
696 	}
697 	return 1;
698 }
699 
700 __setup("apm=", apm_setup);
701 #endif
702 
703 /**
704  * apm_queue_event - queue an APM event for kapmd
705  * @event: APM event
706  *
707  * Queue an APM event for kapmd to process and ultimately take the
708  * appropriate action.  Only a subset of events are handled:
709  *   %APM_LOW_BATTERY
710  *   %APM_POWER_STATUS_CHANGE
711  *   %APM_USER_SUSPEND
712  *   %APM_SYS_SUSPEND
713  *   %APM_CRITICAL_SUSPEND
714  */
apm_queue_event(apm_event_t event)715 void apm_queue_event(apm_event_t event)
716 {
717 	unsigned long flags;
718 
719 	spin_lock_irqsave(&kapmd_queue_lock, flags);
720 	queue_add_event(&kapmd_queue, event);
721 	spin_unlock_irqrestore(&kapmd_queue_lock, flags);
722 
723 	wake_up_interruptible(&kapmd_wait);
724 }
725 EXPORT_SYMBOL(apm_queue_event);
726