/drivers/char/apm-emulation.c
C | 749 lines | 418 code | 113 blank | 218 comment | 65 complexity | b665246e2e583d3696657caaf09f1708 MD5 | raw file
Possible License(s): LGPL-2.0, AGPL-1.0, GPL-2.0
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/hwdev/busbios/amp_12.htm]
12 */
13#include <linux/module.h>
14#include <linux/poll.h>
15#include <linux/slab.h>
16#include <linux/smp_lock.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#include <asm/system.h>
35
36/*
37 * The apm_bios device is one of the misc char devices.
38 * This is its minor number.
39 */
40#define APM_MINOR_DEV 134
41
42/*
43 * See Documentation/Config.help for the configuration options.
44 *
45 * Various options can be changed at boot time as follows:
46 * (We allow underscores for compatibility with the modules code)
47 * apm=on/off enable/disable APM
48 */
49
50/*
51 * Maximum number of events stored
52 */
53#define APM_MAX_EVENTS 16
54
55struct apm_queue {
56 unsigned int event_head;
57 unsigned int event_tail;
58 apm_event_t events[APM_MAX_EVENTS];
59};
60
61/*
62 * thread states (for threads using a writable /dev/apm_bios fd):
63 *
64 * SUSPEND_NONE: nothing happening
65 * SUSPEND_PENDING: suspend event queued for thread and pending to be read
66 * SUSPEND_READ: suspend event read, pending acknowledgement
67 * SUSPEND_ACKED: acknowledgement received from thread (via ioctl),
68 * waiting for resume
69 * SUSPEND_ACKTO: acknowledgement timeout
70 * SUSPEND_DONE: thread had acked suspend and is now notified of
71 * resume
72 *
73 * SUSPEND_WAIT: this thread invoked suspend and is waiting for resume
74 *
75 * A thread migrates in one of three paths:
76 * NONE -1-> PENDING -2-> READ -3-> ACKED -4-> DONE -5-> NONE
77 * -6-> ACKTO -7-> NONE
78 * NONE -8-> WAIT -9-> NONE
79 *
80 * While in PENDING or READ, the thread is accounted for in the
81 * suspend_acks_pending counter.
82 *
83 * The transitions are invoked as follows:
84 * 1: suspend event is signalled from the core PM code
85 * 2: the suspend event is read from the fd by the userspace thread
86 * 3: userspace thread issues the APM_IOC_SUSPEND ioctl (as ack)
87 * 4: core PM code signals that we have resumed
88 * 5: APM_IOC_SUSPEND ioctl returns
89 *
90 * 6: the notifier invoked from the core PM code timed out waiting
91 * for all relevant threds to enter ACKED state and puts those
92 * that haven't into ACKTO
93 * 7: those threads issue APM_IOC_SUSPEND ioctl too late,
94 * get an error
95 *
96 * 8: userspace thread issues the APM_IOC_SUSPEND ioctl (to suspend),
97 * ioctl code invokes pm_suspend()
98 * 9: pm_suspend() returns indicating resume
99 */
100enum apm_suspend_state {
101 SUSPEND_NONE,
102 SUSPEND_PENDING,
103 SUSPEND_READ,
104 SUSPEND_ACKED,
105 SUSPEND_ACKTO,
106 SUSPEND_WAIT,
107 SUSPEND_DONE,
108};
109
110/*
111 * The per-file APM data
112 */
113struct apm_user {
114 struct list_head list;
115
116 unsigned int suser: 1;
117 unsigned int writer: 1;
118 unsigned int reader: 1;
119
120 int suspend_result;
121 enum apm_suspend_state suspend_state;
122
123 struct apm_queue queue;
124};
125
126/*
127 * Local variables
128 */
129static atomic_t suspend_acks_pending = ATOMIC_INIT(0);
130static atomic_t userspace_notification_inhibit = ATOMIC_INIT(0);
131static int apm_disabled;
132static struct task_struct *kapmd_tsk;
133
134static DECLARE_WAIT_QUEUE_HEAD(apm_waitqueue);
135static DECLARE_WAIT_QUEUE_HEAD(apm_suspend_waitqueue);
136
137/*
138 * This is a list of everyone who has opened /dev/apm_bios
139 */
140static DECLARE_RWSEM(user_list_lock);
141static LIST_HEAD(apm_user_list);
142
143/*
144 * kapmd info. kapmd provides us a process context to handle
145 * "APM" events within - specifically necessary if we're going
146 * to be suspending the system.
147 */
148static DECLARE_WAIT_QUEUE_HEAD(kapmd_wait);
149static DEFINE_SPINLOCK(kapmd_queue_lock);
150static struct apm_queue kapmd_queue;
151
152static DEFINE_MUTEX(state_lock);
153
154static const char driver_version[] = "1.13"; /* no spaces */
155
156
157
158/*
159 * Compatibility cruft until the IPAQ people move over to the new
160 * interface.
161 */
162static void __apm_get_power_status(struct apm_power_info *info)
163{
164}
165
166/*
167 * This allows machines to provide their own "apm get power status" function.
168 */
169void (*apm_get_power_status)(struct apm_power_info *) = __apm_get_power_status;
170EXPORT_SYMBOL(apm_get_power_status);
171
172
173/*
174 * APM event queue management.
175 */
176static inline int queue_empty(struct apm_queue *q)
177{
178 return q->event_head == q->event_tail;
179}
180
181static inline apm_event_t queue_get_event(struct apm_queue *q)
182{
183 q->event_tail = (q->event_tail + 1) % APM_MAX_EVENTS;
184 return q->events[q->event_tail];
185}
186
187static void queue_add_event(struct apm_queue *q, apm_event_t event)
188{
189 q->event_head = (q->event_head + 1) % APM_MAX_EVENTS;
190 if (q->event_head == q->event_tail) {
191 static int notified;
192
193 if (notified++ == 0)
194 printk(KERN_ERR "apm: an event queue overflowed\n");
195 q->event_tail = (q->event_tail + 1) % APM_MAX_EVENTS;
196 }
197 q->events[q->event_head] = event;
198}
199
200static void queue_event(apm_event_t event)
201{
202 struct apm_user *as;
203
204 down_read(&user_list_lock);
205 list_for_each_entry(as, &apm_user_list, list) {
206 if (as->reader)
207 queue_add_event(&as->queue, event);
208 }
209 up_read(&user_list_lock);
210 wake_up_interruptible(&apm_waitqueue);
211}
212
213static ssize_t apm_read(struct file *fp, char __user *buf, size_t count, loff_t *ppos)
214{
215 struct apm_user *as = fp->private_data;
216 apm_event_t event;
217 int i = count, ret = 0;
218
219 if (count < sizeof(apm_event_t))
220 return -EINVAL;
221
222 if (queue_empty(&as->queue) && fp->f_flags & O_NONBLOCK)
223 return -EAGAIN;
224
225 wait_event_interruptible(apm_waitqueue, !queue_empty(&as->queue));
226
227 while ((i >= sizeof(event)) && !queue_empty(&as->queue)) {
228 event = queue_get_event(&as->queue);
229
230 ret = -EFAULT;
231 if (copy_to_user(buf, &event, sizeof(event)))
232 break;
233
234 mutex_lock(&state_lock);
235 if (as->suspend_state == SUSPEND_PENDING &&
236 (event == APM_SYS_SUSPEND || event == APM_USER_SUSPEND))
237 as->suspend_state = SUSPEND_READ;
238 mutex_unlock(&state_lock);
239
240 buf += sizeof(event);
241 i -= sizeof(event);
242 }
243
244 if (i < count)
245 ret = count - i;
246
247 return ret;
248}
249
250static unsigned int apm_poll(struct file *fp, poll_table * wait)
251{
252 struct apm_user *as = fp->private_data;
253
254 poll_wait(fp, &apm_waitqueue, wait);
255 return queue_empty(&as->queue) ? 0 : POLLIN | POLLRDNORM;
256}
257
258/*
259 * apm_ioctl - handle APM ioctl
260 *
261 * APM_IOC_SUSPEND
262 * This IOCTL is overloaded, and performs two functions. It is used to:
263 * - initiate a suspend
264 * - acknowledge a suspend read from /dev/apm_bios.
265 * Only when everyone who has opened /dev/apm_bios with write permission
266 * has acknowledge does the actual suspend happen.
267 */
268static long
269apm_ioctl(struct file *filp, u_int cmd, u_long arg)
270{
271 struct apm_user *as = filp->private_data;
272 int err = -EINVAL;
273
274 if (!as->suser || !as->writer)
275 return -EPERM;
276
277 lock_kernel();
278 switch (cmd) {
279 case APM_IOC_SUSPEND:
280 mutex_lock(&state_lock);
281
282 as->suspend_result = -EINTR;
283
284 switch (as->suspend_state) {
285 case SUSPEND_READ:
286 /*
287 * If we read a suspend command from /dev/apm_bios,
288 * then the corresponding APM_IOC_SUSPEND ioctl is
289 * interpreted as an acknowledge.
290 */
291 as->suspend_state = SUSPEND_ACKED;
292 atomic_dec(&suspend_acks_pending);
293 mutex_unlock(&state_lock);
294
295 /*
296 * suspend_acks_pending changed, the notifier needs to
297 * be woken up for this
298 */
299 wake_up(&apm_suspend_waitqueue);
300
301 /*
302 * Wait for the suspend/resume to complete. If there
303 * are pending acknowledges, we wait here for them.
304 */
305 freezer_do_not_count();
306
307 wait_event(apm_suspend_waitqueue,
308 as->suspend_state == SUSPEND_DONE);
309
310 /*
311 * Since we are waiting until the suspend is done, the
312 * try_to_freeze() in freezer_count() will not trigger
313 */
314 freezer_count();
315 break;
316 case SUSPEND_ACKTO:
317 as->suspend_result = -ETIMEDOUT;
318 mutex_unlock(&state_lock);
319 break;
320 default:
321 as->suspend_state = SUSPEND_WAIT;
322 mutex_unlock(&state_lock);
323
324 /*
325 * Otherwise it is a request to suspend the system.
326 * Just invoke pm_suspend(), we'll handle it from
327 * there via the notifier.
328 */
329 as->suspend_result = pm_suspend(PM_SUSPEND_MEM);
330 }
331
332 mutex_lock(&state_lock);
333 err = as->suspend_result;
334 as->suspend_state = SUSPEND_NONE;
335 mutex_unlock(&state_lock);
336 break;
337 }
338 unlock_kernel();
339
340 return err;
341}
342
343static int apm_release(struct inode * inode, struct file * filp)
344{
345 struct apm_user *as = filp->private_data;
346
347 filp->private_data = NULL;
348
349 down_write(&user_list_lock);
350 list_del(&as->list);
351 up_write(&user_list_lock);
352
353 /*
354 * We are now unhooked from the chain. As far as new
355 * events are concerned, we no longer exist.
356 */
357 mutex_lock(&state_lock);
358 if (as->suspend_state == SUSPEND_PENDING ||
359 as->suspend_state == SUSPEND_READ)
360 atomic_dec(&suspend_acks_pending);
361 mutex_unlock(&state_lock);
362
363 wake_up(&apm_suspend_waitqueue);
364
365 kfree(as);
366 return 0;
367}
368
369static int apm_open(struct inode * inode, struct file * filp)
370{
371 struct apm_user *as;
372
373 lock_kernel();
374 as = kzalloc(sizeof(*as), GFP_KERNEL);
375 if (as) {
376 /*
377 * XXX - this is a tiny bit broken, when we consider BSD
378 * process accounting. If the device is opened by root, we
379 * instantly flag that we used superuser privs. Who knows,
380 * we might close the device immediately without doing a
381 * privileged operation -- cevans
382 */
383 as->suser = capable(CAP_SYS_ADMIN);
384 as->writer = (filp->f_mode & FMODE_WRITE) == FMODE_WRITE;
385 as->reader = (filp->f_mode & FMODE_READ) == FMODE_READ;
386
387 down_write(&user_list_lock);
388 list_add(&as->list, &apm_user_list);
389 up_write(&user_list_lock);
390
391 filp->private_data = as;
392 }
393 unlock_kernel();
394
395 return as ? 0 : -ENOMEM;
396}
397
398static const struct file_operations apm_bios_fops = {
399 .owner = THIS_MODULE,
400 .read = apm_read,
401 .poll = apm_poll,
402 .unlocked_ioctl = apm_ioctl,
403 .open = apm_open,
404 .release = apm_release,
405};
406
407static struct miscdevice apm_device = {
408 .minor = APM_MINOR_DEV,
409 .name = "apm_bios",
410 .fops = &apm_bios_fops
411};
412
413
414#ifdef CONFIG_PROC_FS
415/*
416 * Arguments, with symbols from linux/apm_bios.h.
417 *
418 * 0) Linux driver version (this will change if format changes)
419 * 1) APM BIOS Version. Usually 1.0, 1.1 or 1.2.
420 * 2) APM flags from APM Installation Check (0x00):
421 * bit 0: APM_16_BIT_SUPPORT
422 * bit 1: APM_32_BIT_SUPPORT
423 * bit 2: APM_IDLE_SLOWS_CLOCK
424 * bit 3: APM_BIOS_DISABLED
425 * bit 4: APM_BIOS_DISENGAGED
426 * 3) AC line status
427 * 0x00: Off-line
428 * 0x01: On-line
429 * 0x02: On backup power (BIOS >= 1.1 only)
430 * 0xff: Unknown
431 * 4) Battery status
432 * 0x00: High
433 * 0x01: Low
434 * 0x02: Critical
435 * 0x03: Charging
436 * 0x04: Selected battery not present (BIOS >= 1.2 only)
437 * 0xff: Unknown
438 * 5) Battery flag
439 * bit 0: High
440 * bit 1: Low
441 * bit 2: Critical
442 * bit 3: Charging
443 * bit 7: No system battery
444 * 0xff: Unknown
445 * 6) Remaining battery life (percentage of charge):
446 * 0-100: valid
447 * -1: Unknown
448 * 7) Remaining battery life (time units):
449 * Number of remaining minutes or seconds
450 * -1: Unknown
451 * 8) min = minutes; sec = seconds
452 */
453static int proc_apm_show(struct seq_file *m, void *v)
454{
455 struct apm_power_info info;
456 char *units;
457
458 info.ac_line_status = 0xff;
459 info.battery_status = 0xff;
460 info.battery_flag = 0xff;
461 info.battery_life = -1;
462 info.time = -1;
463 info.units = -1;
464
465 if (apm_get_power_status)
466 apm_get_power_status(&info);
467
468 switch (info.units) {
469 default: units = "?"; break;
470 case 0: units = "min"; break;
471 case 1: units = "sec"; break;
472 }
473
474 seq_printf(m, "%s 1.2 0x%02x 0x%02x 0x%02x 0x%02x %d%% %d %s\n",
475 driver_version, APM_32_BIT_SUPPORT,
476 info.ac_line_status, info.battery_status,
477 info.battery_flag, info.battery_life,
478 info.time, units);
479
480 return 0;
481}
482
483static int proc_apm_open(struct inode *inode, struct file *file)
484{
485 return single_open(file, proc_apm_show, NULL);
486}
487
488static const struct file_operations apm_proc_fops = {
489 .owner = THIS_MODULE,
490 .open = proc_apm_open,
491 .read = seq_read,
492 .llseek = seq_lseek,
493 .release = single_release,
494};
495#endif
496
497static int kapmd(void *arg)
498{
499 do {
500 apm_event_t event;
501
502 wait_event_interruptible(kapmd_wait,
503 !queue_empty(&kapmd_queue) || kthread_should_stop());
504
505 if (kthread_should_stop())
506 break;
507
508 spin_lock_irq(&kapmd_queue_lock);
509 event = 0;
510 if (!queue_empty(&kapmd_queue))
511 event = queue_get_event(&kapmd_queue);
512 spin_unlock_irq(&kapmd_queue_lock);
513
514 switch (event) {
515 case 0:
516 break;
517
518 case APM_LOW_BATTERY:
519 case APM_POWER_STATUS_CHANGE:
520 queue_event(event);
521 break;
522
523 case APM_USER_SUSPEND:
524 case APM_SYS_SUSPEND:
525 pm_suspend(PM_SUSPEND_MEM);
526 break;
527
528 case APM_CRITICAL_SUSPEND:
529 atomic_inc(&userspace_notification_inhibit);
530 pm_suspend(PM_SUSPEND_MEM);
531 atomic_dec(&userspace_notification_inhibit);
532 break;
533 }
534 } while (1);
535
536 return 0;
537}
538
539static int apm_suspend_notifier(struct notifier_block *nb,
540 unsigned long event,
541 void *dummy)
542{
543 struct apm_user *as;
544 int err;
545
546 /* short-cut emergency suspends */
547 if (atomic_read(&userspace_notification_inhibit))
548 return NOTIFY_DONE;
549
550 switch (event) {
551 case PM_SUSPEND_PREPARE:
552 /*
553 * Queue an event to all "writer" users that we want
554 * to suspend and need their ack.
555 */
556 mutex_lock(&state_lock);
557 down_read(&user_list_lock);
558
559 list_for_each_entry(as, &apm_user_list, list) {
560 if (as->suspend_state != SUSPEND_WAIT && as->reader &&
561 as->writer && as->suser) {
562 as->suspend_state = SUSPEND_PENDING;
563 atomic_inc(&suspend_acks_pending);
564 queue_add_event(&as->queue, APM_USER_SUSPEND);
565 }
566 }
567
568 up_read(&user_list_lock);
569 mutex_unlock(&state_lock);
570 wake_up_interruptible(&apm_waitqueue);
571
572 /*
573 * Wait for the the suspend_acks_pending variable to drop to
574 * zero, meaning everybody acked the suspend event (or the
575 * process was killed.)
576 *
577 * If the app won't answer within a short while we assume it
578 * locked up and ignore it.
579 */
580 err = wait_event_interruptible_timeout(
581 apm_suspend_waitqueue,
582 atomic_read(&suspend_acks_pending) == 0,
583 5*HZ);
584
585 /* timed out */
586 if (err == 0) {
587 /*
588 * Move anybody who timed out to "ack timeout" state.
589 *
590 * We could time out and the userspace does the ACK
591 * right after we time out but before we enter the
592 * locked section here, but that's fine.
593 */
594 mutex_lock(&state_lock);
595 down_read(&user_list_lock);
596 list_for_each_entry(as, &apm_user_list, list) {
597 if (as->suspend_state == SUSPEND_PENDING ||
598 as->suspend_state == SUSPEND_READ) {
599 as->suspend_state = SUSPEND_ACKTO;
600 atomic_dec(&suspend_acks_pending);
601 }
602 }
603 up_read(&user_list_lock);
604 mutex_unlock(&state_lock);
605 }
606
607 /* let suspend proceed */
608 if (err >= 0)
609 return NOTIFY_OK;
610
611 /* interrupted by signal */
612 return NOTIFY_BAD;
613
614 case PM_POST_SUSPEND:
615 /*
616 * Anyone on the APM queues will think we're still suspended.
617 * Send a message so everyone knows we're now awake again.
618 */
619 queue_event(APM_NORMAL_RESUME);
620
621 /*
622 * Finally, wake up anyone who is sleeping on the suspend.
623 */
624 mutex_lock(&state_lock);
625 down_read(&user_list_lock);
626 list_for_each_entry(as, &apm_user_list, list) {
627 if (as->suspend_state == SUSPEND_ACKED) {
628 /*
629 * TODO: maybe grab error code, needs core
630 * changes to push the error to the notifier
631 * chain (could use the second parameter if
632 * implemented)
633 */
634 as->suspend_result = 0;
635 as->suspend_state = SUSPEND_DONE;
636 }
637 }
638 up_read(&user_list_lock);
639 mutex_unlock(&state_lock);
640
641 wake_up(&apm_suspend_waitqueue);
642 return NOTIFY_OK;
643
644 default:
645 return NOTIFY_DONE;
646 }
647}
648
649static struct notifier_block apm_notif_block = {
650 .notifier_call = apm_suspend_notifier,
651};
652
653static int __init apm_init(void)
654{
655 int ret;
656
657 if (apm_disabled) {
658 printk(KERN_NOTICE "apm: disabled on user request.\n");
659 return -ENODEV;
660 }
661
662 kapmd_tsk = kthread_create(kapmd, NULL, "kapmd");
663 if (IS_ERR(kapmd_tsk)) {
664 ret = PTR_ERR(kapmd_tsk);
665 kapmd_tsk = NULL;
666 goto out;
667 }
668 wake_up_process(kapmd_tsk);
669
670#ifdef CONFIG_PROC_FS
671 proc_create("apm", 0, NULL, &apm_proc_fops);
672#endif
673
674 ret = misc_register(&apm_device);
675 if (ret)
676 goto out_stop;
677
678 ret = register_pm_notifier(&apm_notif_block);
679 if (ret)
680 goto out_unregister;
681
682 return 0;
683
684 out_unregister:
685 misc_deregister(&apm_device);
686 out_stop:
687 remove_proc_entry("apm", NULL);
688 kthread_stop(kapmd_tsk);
689 out:
690 return ret;
691}
692
693static void __exit apm_exit(void)
694{
695 unregister_pm_notifier(&apm_notif_block);
696 misc_deregister(&apm_device);
697 remove_proc_entry("apm", NULL);
698
699 kthread_stop(kapmd_tsk);
700}
701
702module_init(apm_init);
703module_exit(apm_exit);
704
705MODULE_AUTHOR("Stephen Rothwell");
706MODULE_DESCRIPTION("Advanced Power Management");
707MODULE_LICENSE("GPL");
708
709#ifndef MODULE
710static int __init apm_setup(char *str)
711{
712 while ((str != NULL) && (*str != '\0')) {
713 if (strncmp(str, "off", 3) == 0)
714 apm_disabled = 1;
715 if (strncmp(str, "on", 2) == 0)
716 apm_disabled = 0;
717 str = strchr(str, ',');
718 if (str != NULL)
719 str += strspn(str, ", \t");
720 }
721 return 1;
722}
723
724__setup("apm=", apm_setup);
725#endif
726
727/**
728 * apm_queue_event - queue an APM event for kapmd
729 * @event: APM event
730 *
731 * Queue an APM event for kapmd to process and ultimately take the
732 * appropriate action. Only a subset of events are handled:
733 * %APM_LOW_BATTERY
734 * %APM_POWER_STATUS_CHANGE
735 * %APM_USER_SUSPEND
736 * %APM_SYS_SUSPEND
737 * %APM_CRITICAL_SUSPEND
738 */
739void apm_queue_event(apm_event_t event)
740{
741 unsigned long flags;
742
743 spin_lock_irqsave(&kapmd_queue_lock, flags);
744 queue_add_event(&kapmd_queue, event);
745 spin_unlock_irqrestore(&kapmd_queue_lock, flags);
746
747 wake_up_interruptible(&kapmd_wait);
748}
749EXPORT_SYMBOL(apm_queue_event);