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/*
36 * The apm_bios device is one of the misc char devices.
37 * This is its minor number.
38 */
39#define APM_MINOR_DEV	134
40
41/*
42 * One option can be changed at boot time as follows:
43 *	apm=on/off			enable/disable APM
44 */
45
46/*
47 * Maximum number of events stored
48 */
49#define APM_MAX_EVENTS		16
50
51struct apm_queue {
52	unsigned int		event_head;
53	unsigned int		event_tail;
54	apm_event_t		events[APM_MAX_EVENTS];
55};
56
57/*
58 * thread states (for threads using a writable /dev/apm_bios fd):
59 *
60 * SUSPEND_NONE:	nothing happening
61 * SUSPEND_PENDING:	suspend event queued for thread and pending to be read
62 * SUSPEND_READ:	suspend event read, pending acknowledgement
63 * SUSPEND_ACKED:	acknowledgement received from thread (via ioctl),
64 *			waiting for resume
65 * SUSPEND_ACKTO:	acknowledgement timeout
66 * SUSPEND_DONE:	thread had acked suspend and is now notified of
67 *			resume
68 *
69 * SUSPEND_WAIT:	this thread invoked suspend and is waiting for resume
70 *
71 * A thread migrates in one of three paths:
72 *	NONE -1-> PENDING -2-> READ -3-> ACKED -4-> DONE -5-> NONE
73 *				    -6-> ACKTO -7-> NONE
74 *	NONE -8-> WAIT -9-> NONE
75 *
76 * While in PENDING or READ, the thread is accounted for in the
77 * suspend_acks_pending counter.
78 *
79 * The transitions are invoked as follows:
80 *	1: suspend event is signalled from the core PM code
81 *	2: the suspend event is read from the fd by the userspace thread
82 *	3: userspace thread issues the APM_IOC_SUSPEND ioctl (as ack)
83 *	4: core PM code signals that we have resumed
84 *	5: APM_IOC_SUSPEND ioctl returns
85 *
86 *	6: the notifier invoked from the core PM code timed out waiting
87 *	   for all relevant threds to enter ACKED state and puts those
88 *	   that haven't into ACKTO
89 *	7: those threads issue APM_IOC_SUSPEND ioctl too late,
90 *	   get an error
91 *
92 *	8: userspace thread issues the APM_IOC_SUSPEND ioctl (to suspend),
93 *	   ioctl code invokes pm_suspend()
94 *	9: pm_suspend() returns indicating resume
95 */
96enum apm_suspend_state {
97	SUSPEND_NONE,
98	SUSPEND_PENDING,
99	SUSPEND_READ,
100	SUSPEND_ACKED,
101	SUSPEND_ACKTO,
102	SUSPEND_WAIT,
103	SUSPEND_DONE,
104};
105
106/*
107 * The per-file APM data
108 */
109struct apm_user {
110	struct list_head	list;
111
112	unsigned int		suser: 1;
113	unsigned int		writer: 1;
114	unsigned int		reader: 1;
115
116	int			suspend_result;
117	enum apm_suspend_state	suspend_state;
118
119	struct apm_queue	queue;
120};
121
122/*
123 * Local variables
124 */
125static atomic_t suspend_acks_pending = ATOMIC_INIT(0);
126static atomic_t userspace_notification_inhibit = ATOMIC_INIT(0);
127static int apm_disabled;
128static struct task_struct *kapmd_tsk;
129
130static DECLARE_WAIT_QUEUE_HEAD(apm_waitqueue);
131static DECLARE_WAIT_QUEUE_HEAD(apm_suspend_waitqueue);
132
133/*
134 * This is a list of everyone who has opened /dev/apm_bios
135 */
136static DECLARE_RWSEM(user_list_lock);
137static LIST_HEAD(apm_user_list);
138
139/*
140 * kapmd info.  kapmd provides us a process context to handle
141 * "APM" events within - specifically necessary if we're going
142 * to be suspending the system.
143 */
144static DECLARE_WAIT_QUEUE_HEAD(kapmd_wait);
145static DEFINE_SPINLOCK(kapmd_queue_lock);
146static struct apm_queue kapmd_queue;
147
148static DEFINE_MUTEX(state_lock);
149
150static const char driver_version[] = "1.13";	/* no spaces */
151
152
153
154/*
155 * Compatibility cruft until the IPAQ people move over to the new
156 * interface.
157 */
158static void __apm_get_power_status(struct apm_power_info *info)
159{
160}
161
162/*
163 * This allows machines to provide their own "apm get power status" function.
164 */
165void (*apm_get_power_status)(struct apm_power_info *) = __apm_get_power_status;
166EXPORT_SYMBOL(apm_get_power_status);
167
168
169/*
170 * APM event queue management.
171 */
172static inline int queue_empty(struct apm_queue *q)
173{
174	return q->event_head == q->event_tail;
175}
176
177static inline apm_event_t queue_get_event(struct apm_queue *q)
178{
179	q->event_tail = (q->event_tail + 1) % APM_MAX_EVENTS;
180	return q->events[q->event_tail];
181}
182
183static void queue_add_event(struct apm_queue *q, apm_event_t event)
184{
185	q->event_head = (q->event_head + 1) % APM_MAX_EVENTS;
186	if (q->event_head == q->event_tail) {
187		static int notified;
188
189		if (notified++ == 0)
190		    printk(KERN_ERR "apm: an event queue overflowed\n");
191		q->event_tail = (q->event_tail + 1) % APM_MAX_EVENTS;
192	}
193	q->events[q->event_head] = event;
194}
195
196static void queue_event(apm_event_t event)
197{
198	struct apm_user *as;
199
200	down_read(&user_list_lock);
201	list_for_each_entry(as, &apm_user_list, list) {
202		if (as->reader)
203			queue_add_event(&as->queue, event);
204	}
205	up_read(&user_list_lock);
206	wake_up_interruptible(&apm_waitqueue);
207}
208
209static ssize_t apm_read(struct file *fp, char __user *buf, size_t count, loff_t *ppos)
210{
211	struct apm_user *as = fp->private_data;
212	apm_event_t event;
213	int i = count, ret = 0;
214
215	if (count < sizeof(apm_event_t))
216		return -EINVAL;
217
218	if (queue_empty(&as->queue) && fp->f_flags & O_NONBLOCK)
219		return -EAGAIN;
220
221	wait_event_interruptible(apm_waitqueue, !queue_empty(&as->queue));
222
223	while ((i >= sizeof(event)) && !queue_empty(&as->queue)) {
224		event = queue_get_event(&as->queue);
225
226		ret = -EFAULT;
227		if (copy_to_user(buf, &event, sizeof(event)))
228			break;
229
230		mutex_lock(&state_lock);
231		if (as->suspend_state == SUSPEND_PENDING &&
232		    (event == APM_SYS_SUSPEND || event == APM_USER_SUSPEND))
233			as->suspend_state = SUSPEND_READ;
234		mutex_unlock(&state_lock);
235
236		buf += sizeof(event);
237		i -= sizeof(event);
238	}
239
240	if (i < count)
241		ret = count - i;
242
243	return ret;
244}
245
246static unsigned int apm_poll(struct file *fp, poll_table * wait)
247{
248	struct apm_user *as = fp->private_data;
249
250	poll_wait(fp, &apm_waitqueue, wait);
251	return queue_empty(&as->queue) ? 0 : POLLIN | POLLRDNORM;
252}
253
254/*
255 * apm_ioctl - handle APM ioctl
256 *
257 * APM_IOC_SUSPEND
258 *   This IOCTL is overloaded, and performs two functions.  It is used to:
259 *     - initiate a suspend
260 *     - acknowledge a suspend read from /dev/apm_bios.
261 *   Only when everyone who has opened /dev/apm_bios with write permission
262 *   has acknowledge does the actual suspend happen.
263 */
264static long
265apm_ioctl(struct file *filp, u_int cmd, u_long arg)
266{
267	struct apm_user *as = filp->private_data;
268	int err = -EINVAL;
269
270	if (!as->suser || !as->writer)
271		return -EPERM;
272
273	switch (cmd) {
274	case APM_IOC_SUSPEND:
275		mutex_lock(&state_lock);
276
277		as->suspend_result = -EINTR;
278
279		switch (as->suspend_state) {
280		case SUSPEND_READ:
281			/*
282			 * If we read a suspend command from /dev/apm_bios,
283			 * then the corresponding APM_IOC_SUSPEND ioctl is
284			 * interpreted as an acknowledge.
285			 */
286			as->suspend_state = SUSPEND_ACKED;
287			atomic_dec(&suspend_acks_pending);
288			mutex_unlock(&state_lock);
289
290			/*
291			 * suspend_acks_pending changed, the notifier needs to
292			 * be woken up for this
293			 */
294			wake_up(&apm_suspend_waitqueue);
295
296			/*
297			 * Wait for the suspend/resume to complete.  If there
298			 * are pending acknowledges, we wait here for them.
299			 * wait_event_freezable() is interruptible and pending
300			 * signal can cause busy looping.  We aren't doing
301			 * anything critical, chill a bit on each iteration.
302			 */
303			while (wait_event_freezable(apm_suspend_waitqueue,
304					as->suspend_state != SUSPEND_ACKED))
305				msleep(10);
306			break;
307		case SUSPEND_ACKTO:
308			as->suspend_result = -ETIMEDOUT;
309			mutex_unlock(&state_lock);
310			break;
311		default:
312			as->suspend_state = SUSPEND_WAIT;
313			mutex_unlock(&state_lock);
314
315			/*
316			 * Otherwise it is a request to suspend the system.
317			 * Just invoke pm_suspend(), we'll handle it from
318			 * there via the notifier.
319			 */
320			as->suspend_result = pm_suspend(PM_SUSPEND_MEM);
321		}
322
323		mutex_lock(&state_lock);
324		err = as->suspend_result;
325		as->suspend_state = SUSPEND_NONE;
326		mutex_unlock(&state_lock);
327		break;
328	}
329
330	return err;
331}
332
333static int apm_release(struct inode * inode, struct file * filp)
334{
335	struct apm_user *as = filp->private_data;
336
337	filp->private_data = NULL;
338
339	down_write(&user_list_lock);
340	list_del(&as->list);
341	up_write(&user_list_lock);
342
343	/*
344	 * We are now unhooked from the chain.  As far as new
345	 * events are concerned, we no longer exist.
346	 */
347	mutex_lock(&state_lock);
348	if (as->suspend_state == SUSPEND_PENDING ||
349	    as->suspend_state == SUSPEND_READ)
350		atomic_dec(&suspend_acks_pending);
351	mutex_unlock(&state_lock);
352
353	wake_up(&apm_suspend_waitqueue);
354
355	kfree(as);
356	return 0;
357}
358
359static int apm_open(struct inode * inode, struct file * filp)
360{
361	struct apm_user *as;
362
363	as = kzalloc(sizeof(*as), GFP_KERNEL);
364	if (as) {
365		/*
366		 * XXX - this is a tiny bit broken, when we consider BSD
367		 * process accounting. If the device is opened by root, we
368		 * instantly flag that we used superuser privs. Who knows,
369		 * we might close the device immediately without doing a
370		 * privileged operation -- cevans
371		 */
372		as->suser = capable(CAP_SYS_ADMIN);
373		as->writer = (filp->f_mode & FMODE_WRITE) == FMODE_WRITE;
374		as->reader = (filp->f_mode & FMODE_READ) == FMODE_READ;
375
376		down_write(&user_list_lock);
377		list_add(&as->list, &apm_user_list);
378		up_write(&user_list_lock);
379
380		filp->private_data = as;
381	}
382
383	return as ? 0 : -ENOMEM;
384}
385
386static const struct file_operations apm_bios_fops = {
387	.owner		= THIS_MODULE,
388	.read		= apm_read,
389	.poll		= apm_poll,
390	.unlocked_ioctl	= apm_ioctl,
391	.open		= apm_open,
392	.release	= apm_release,
393	.llseek		= noop_llseek,
394};
395
396static struct miscdevice apm_device = {
397	.minor		= APM_MINOR_DEV,
398	.name		= "apm_bios",
399	.fops		= &apm_bios_fops
400};
401
402
403#ifdef CONFIG_PROC_FS
404/*
405 * Arguments, with symbols from linux/apm_bios.h.
406 *
407 *   0) Linux driver version (this will change if format changes)
408 *   1) APM BIOS Version.  Usually 1.0, 1.1 or 1.2.
409 *   2) APM flags from APM Installation Check (0x00):
410 *	bit 0: APM_16_BIT_SUPPORT
411 *	bit 1: APM_32_BIT_SUPPORT
412 *	bit 2: APM_IDLE_SLOWS_CLOCK
413 *	bit 3: APM_BIOS_DISABLED
414 *	bit 4: APM_BIOS_DISENGAGED
415 *   3) AC line status
416 *	0x00: Off-line
417 *	0x01: On-line
418 *	0x02: On backup power (BIOS >= 1.1 only)
419 *	0xff: Unknown
420 *   4) Battery status
421 *	0x00: High
422 *	0x01: Low
423 *	0x02: Critical
424 *	0x03: Charging
425 *	0x04: Selected battery not present (BIOS >= 1.2 only)
426 *	0xff: Unknown
427 *   5) Battery flag
428 *	bit 0: High
429 *	bit 1: Low
430 *	bit 2: Critical
431 *	bit 3: Charging
432 *	bit 7: No system battery
433 *	0xff: Unknown
434 *   6) Remaining battery life (percentage of charge):
435 *	0-100: valid
436 *	-1: Unknown
437 *   7) Remaining battery life (time units):
438 *	Number of remaining minutes or seconds
439 *	-1: Unknown
440 *   8) min = minutes; sec = seconds
441 */
442static int proc_apm_show(struct seq_file *m, void *v)
443{
444	struct apm_power_info info;
445	char *units;
446
447	info.ac_line_status = 0xff;
448	info.battery_status = 0xff;
449	info.battery_flag   = 0xff;
450	info.battery_life   = -1;
451	info.time	    = -1;
452	info.units	    = -1;
453
454	if (apm_get_power_status)
455		apm_get_power_status(&info);
456
457	switch (info.units) {
458	default:	units = "?";	break;
459	case 0: 	units = "min";	break;
460	case 1: 	units = "sec";	break;
461	}
462
463	seq_printf(m, "%s 1.2 0x%02x 0x%02x 0x%02x 0x%02x %d%% %d %s\n",
464		     driver_version, APM_32_BIT_SUPPORT,
465		     info.ac_line_status, info.battery_status,
466		     info.battery_flag, info.battery_life,
467		     info.time, units);
468
469	return 0;
470}
471
472static int proc_apm_open(struct inode *inode, struct file *file)
473{
474	return single_open(file, proc_apm_show, NULL);
475}
476
477static const struct file_operations apm_proc_fops = {
478	.owner		= THIS_MODULE,
479	.open		= proc_apm_open,
480	.read		= seq_read,
481	.llseek		= seq_lseek,
482	.release	= single_release,
483};
484#endif
485
486static int kapmd(void *arg)
487{
488	do {
489		apm_event_t event;
490
491		wait_event_interruptible(kapmd_wait,
492				!queue_empty(&kapmd_queue) || kthread_should_stop());
493
494		if (kthread_should_stop())
495			break;
496
497		spin_lock_irq(&kapmd_queue_lock);
498		event = 0;
499		if (!queue_empty(&kapmd_queue))
500			event = queue_get_event(&kapmd_queue);
501		spin_unlock_irq(&kapmd_queue_lock);
502
503		switch (event) {
504		case 0:
505			break;
506
507		case APM_LOW_BATTERY:
508		case APM_POWER_STATUS_CHANGE:
509			queue_event(event);
510			break;
511
512		case APM_USER_SUSPEND:
513		case APM_SYS_SUSPEND:
514			pm_suspend(PM_SUSPEND_MEM);
515			break;
516
517		case APM_CRITICAL_SUSPEND:
518			atomic_inc(&userspace_notification_inhibit);
519			pm_suspend(PM_SUSPEND_MEM);
520			atomic_dec(&userspace_notification_inhibit);
521			break;
522		}
523	} while (1);
524
525	return 0;
526}
527
528static int apm_suspend_notifier(struct notifier_block *nb,
529				unsigned long event,
530				void *dummy)
531{
532	struct apm_user *as;
533	int err;
534
535	/* short-cut emergency suspends */
536	if (atomic_read(&userspace_notification_inhibit))
537		return NOTIFY_DONE;
538
539	switch (event) {
540	case PM_SUSPEND_PREPARE:
541		/*
542		 * Queue an event to all "writer" users that we want
543		 * to suspend and need their ack.
544		 */
545		mutex_lock(&state_lock);
546		down_read(&user_list_lock);
547
548		list_for_each_entry(as, &apm_user_list, list) {
549			if (as->suspend_state != SUSPEND_WAIT && as->reader &&
550			    as->writer && as->suser) {
551				as->suspend_state = SUSPEND_PENDING;
552				atomic_inc(&suspend_acks_pending);
553				queue_add_event(&as->queue, APM_USER_SUSPEND);
554			}
555		}
556
557		up_read(&user_list_lock);
558		mutex_unlock(&state_lock);
559		wake_up_interruptible(&apm_waitqueue);
560
561		/*
562		 * Wait for the the suspend_acks_pending variable to drop to
563		 * zero, meaning everybody acked the suspend event (or the
564		 * process was killed.)
565		 *
566		 * If the app won't answer within a short while we assume it
567		 * locked up and ignore it.
568		 */
569		err = wait_event_interruptible_timeout(
570			apm_suspend_waitqueue,
571			atomic_read(&suspend_acks_pending) == 0,
572			5*HZ);
573
574		/* timed out */
575		if (err == 0) {
576			/*
577			 * Move anybody who timed out to "ack timeout" state.
578			 *
579			 * We could time out and the userspace does the ACK
580			 * right after we time out but before we enter the
581			 * locked section here, but that's fine.
582			 */
583			mutex_lock(&state_lock);
584			down_read(&user_list_lock);
585			list_for_each_entry(as, &apm_user_list, list) {
586				if (as->suspend_state == SUSPEND_PENDING ||
587				    as->suspend_state == SUSPEND_READ) {
588					as->suspend_state = SUSPEND_ACKTO;
589					atomic_dec(&suspend_acks_pending);
590				}
591			}
592			up_read(&user_list_lock);
593			mutex_unlock(&state_lock);
594		}
595
596		/* let suspend proceed */
597		if (err >= 0)
598			return NOTIFY_OK;
599
600		/* interrupted by signal */
601		return notifier_from_errno(err);
602
603	case PM_POST_SUSPEND:
604		/*
605		 * Anyone on the APM queues will think we're still suspended.
606		 * Send a message so everyone knows we're now awake again.
607		 */
608		queue_event(APM_NORMAL_RESUME);
609
610		/*
611		 * Finally, wake up anyone who is sleeping on the suspend.
612		 */
613		mutex_lock(&state_lock);
614		down_read(&user_list_lock);
615		list_for_each_entry(as, &apm_user_list, list) {
616			if (as->suspend_state == SUSPEND_ACKED) {
617				/*
618				 * TODO: maybe grab error code, needs core
619				 * changes to push the error to the notifier
620				 * chain (could use the second parameter if
621				 * implemented)
622				 */
623				as->suspend_result = 0;
624				as->suspend_state = SUSPEND_DONE;
625			}
626		}
627		up_read(&user_list_lock);
628		mutex_unlock(&state_lock);
629
630		wake_up(&apm_suspend_waitqueue);
631		return NOTIFY_OK;
632
633	default:
634		return NOTIFY_DONE;
635	}
636}
637
638static struct notifier_block apm_notif_block = {
639	.notifier_call = apm_suspend_notifier,
640};
641
642static int __init apm_init(void)
643{
644	int ret;
645
646	if (apm_disabled) {
647		printk(KERN_NOTICE "apm: disabled on user request.\n");
648		return -ENODEV;
649	}
650
651	kapmd_tsk = kthread_create(kapmd, NULL, "kapmd");
652	if (IS_ERR(kapmd_tsk)) {
653		ret = PTR_ERR(kapmd_tsk);
654		kapmd_tsk = NULL;
655		goto out;
656	}
657	wake_up_process(kapmd_tsk);
658
659#ifdef CONFIG_PROC_FS
660	proc_create("apm", 0, NULL, &apm_proc_fops);
661#endif
662
663	ret = misc_register(&apm_device);
664	if (ret)
665		goto out_stop;
666
667	ret = register_pm_notifier(&apm_notif_block);
668	if (ret)
669		goto out_unregister;
670
671	return 0;
672
673 out_unregister:
674	misc_deregister(&apm_device);
675 out_stop:
676	remove_proc_entry("apm", NULL);
677	kthread_stop(kapmd_tsk);
678 out:
679	return ret;
680}
681
682static void __exit apm_exit(void)
683{
684	unregister_pm_notifier(&apm_notif_block);
685	misc_deregister(&apm_device);
686	remove_proc_entry("apm", NULL);
687
688	kthread_stop(kapmd_tsk);
689}
690
691module_init(apm_init);
692module_exit(apm_exit);
693
694MODULE_AUTHOR("Stephen Rothwell");
695MODULE_DESCRIPTION("Advanced Power Management");
696MODULE_LICENSE("GPL");
697
698#ifndef MODULE
699static int __init apm_setup(char *str)
700{
701	while ((str != NULL) && (*str != '\0')) {
702		if (strncmp(str, "off", 3) == 0)
703			apm_disabled = 1;
704		if (strncmp(str, "on", 2) == 0)
705			apm_disabled = 0;
706		str = strchr(str, ',');
707		if (str != NULL)
708			str += strspn(str, ", \t");
709	}
710	return 1;
711}
712
713__setup("apm=", apm_setup);
714#endif
715
716/**
717 * apm_queue_event - queue an APM event for kapmd
718 * @event: APM event
719 *
720 * Queue an APM event for kapmd to process and ultimately take the
721 * appropriate action.  Only a subset of events are handled:
722 *   %APM_LOW_BATTERY
723 *   %APM_POWER_STATUS_CHANGE
724 *   %APM_USER_SUSPEND
725 *   %APM_SYS_SUSPEND
726 *   %APM_CRITICAL_SUSPEND
727 */
728void apm_queue_event(apm_event_t event)
729{
730	unsigned long flags;
731
732	spin_lock_irqsave(&kapmd_queue_lock, flags);
733	queue_add_event(&kapmd_queue, event);
734	spin_unlock_irqrestore(&kapmd_queue_lock, flags);
735
736	wake_up_interruptible(&kapmd_wait);
737}
738EXPORT_SYMBOL(apm_queue_event);
739