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1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * bios-less APM driver for ARM Linux
4 * Jamey Hicks <jamey@crl.dec.com>
5 * adapted from the APM BIOS driver for Linux by Stephen Rothwell (sfr@linuxcare.com)
6 *
7 * APM 1.2 Reference:
8 * Intel Corporation, Microsoft Corporation. Advanced Power Management
9 * (APM) BIOS Interface Specification, Revision 1.2, February 1996.
10 *
11 * This document is available from Microsoft at:
12 * http://www.microsoft.com/whdc/archive/amp_12.mspx
13 */
14#include <linux/module.h>
15#include <linux/poll.h>
16#include <linux/slab.h>
17#include <linux/mutex.h>
18#include <linux/proc_fs.h>
19#include <linux/seq_file.h>
20#include <linux/miscdevice.h>
21#include <linux/apm_bios.h>
22#include <linux/capability.h>
23#include <linux/sched.h>
24#include <linux/suspend.h>
25#include <linux/apm-emulation.h>
26#include <linux/freezer.h>
27#include <linux/device.h>
28#include <linux/kernel.h>
29#include <linux/list.h>
30#include <linux/init.h>
31#include <linux/completion.h>
32#include <linux/kthread.h>
33#include <linux/delay.h>
34
35/*
36 * One option can be changed at boot time as follows:
37 * apm=on/off enable/disable APM
38 */
39
40/*
41 * Maximum number of events stored
42 */
43#define APM_MAX_EVENTS 16
44
45struct apm_queue {
46 unsigned int event_head;
47 unsigned int event_tail;
48 apm_event_t events[APM_MAX_EVENTS];
49};
50
51/*
52 * thread states (for threads using a writable /dev/apm_bios fd):
53 *
54 * SUSPEND_NONE: nothing happening
55 * SUSPEND_PENDING: suspend event queued for thread and pending to be read
56 * SUSPEND_READ: suspend event read, pending acknowledgement
57 * SUSPEND_ACKED: acknowledgement received from thread (via ioctl),
58 * waiting for resume
59 * SUSPEND_ACKTO: acknowledgement timeout
60 * SUSPEND_DONE: thread had acked suspend and is now notified of
61 * resume
62 *
63 * SUSPEND_WAIT: this thread invoked suspend and is waiting for resume
64 *
65 * A thread migrates in one of three paths:
66 * NONE -1-> PENDING -2-> READ -3-> ACKED -4-> DONE -5-> NONE
67 * -6-> ACKTO -7-> NONE
68 * NONE -8-> WAIT -9-> NONE
69 *
70 * While in PENDING or READ, the thread is accounted for in the
71 * suspend_acks_pending counter.
72 *
73 * The transitions are invoked as follows:
74 * 1: suspend event is signalled from the core PM code
75 * 2: the suspend event is read from the fd by the userspace thread
76 * 3: userspace thread issues the APM_IOC_SUSPEND ioctl (as ack)
77 * 4: core PM code signals that we have resumed
78 * 5: APM_IOC_SUSPEND ioctl returns
79 *
80 * 6: the notifier invoked from the core PM code timed out waiting
81 * for all relevant threds to enter ACKED state and puts those
82 * that haven't into ACKTO
83 * 7: those threads issue APM_IOC_SUSPEND ioctl too late,
84 * get an error
85 *
86 * 8: userspace thread issues the APM_IOC_SUSPEND ioctl (to suspend),
87 * ioctl code invokes pm_suspend()
88 * 9: pm_suspend() returns indicating resume
89 */
90enum apm_suspend_state {
91 SUSPEND_NONE,
92 SUSPEND_PENDING,
93 SUSPEND_READ,
94 SUSPEND_ACKED,
95 SUSPEND_ACKTO,
96 SUSPEND_WAIT,
97 SUSPEND_DONE,
98};
99
100/*
101 * The per-file APM data
102 */
103struct apm_user {
104 struct list_head list;
105
106 unsigned int suser: 1;
107 unsigned int writer: 1;
108 unsigned int reader: 1;
109
110 int suspend_result;
111 enum apm_suspend_state suspend_state;
112
113 struct apm_queue queue;
114};
115
116/*
117 * Local variables
118 */
119static atomic_t suspend_acks_pending = ATOMIC_INIT(0);
120static atomic_t userspace_notification_inhibit = ATOMIC_INIT(0);
121static int apm_disabled;
122static struct task_struct *kapmd_tsk;
123
124static DECLARE_WAIT_QUEUE_HEAD(apm_waitqueue);
125static DECLARE_WAIT_QUEUE_HEAD(apm_suspend_waitqueue);
126
127/*
128 * This is a list of everyone who has opened /dev/apm_bios
129 */
130static DECLARE_RWSEM(user_list_lock);
131static LIST_HEAD(apm_user_list);
132
133/*
134 * kapmd info. kapmd provides us a process context to handle
135 * "APM" events within - specifically necessary if we're going
136 * to be suspending the system.
137 */
138static DECLARE_WAIT_QUEUE_HEAD(kapmd_wait);
139static DEFINE_SPINLOCK(kapmd_queue_lock);
140static struct apm_queue kapmd_queue;
141
142static DEFINE_MUTEX(state_lock);
143
144static const char driver_version[] = "1.13"; /* no spaces */
145
146
147
148/*
149 * Compatibility cruft until the IPAQ people move over to the new
150 * interface.
151 */
152static void __apm_get_power_status(struct apm_power_info *info)
153{
154}
155
156/*
157 * This allows machines to provide their own "apm get power status" function.
158 */
159void (*apm_get_power_status)(struct apm_power_info *) = __apm_get_power_status;
160EXPORT_SYMBOL(apm_get_power_status);
161
162
163/*
164 * APM event queue management.
165 */
166static inline int queue_empty(struct apm_queue *q)
167{
168 return q->event_head == q->event_tail;
169}
170
171static inline apm_event_t queue_get_event(struct apm_queue *q)
172{
173 q->event_tail = (q->event_tail + 1) % APM_MAX_EVENTS;
174 return q->events[q->event_tail];
175}
176
177static void queue_add_event(struct apm_queue *q, apm_event_t event)
178{
179 q->event_head = (q->event_head + 1) % APM_MAX_EVENTS;
180 if (q->event_head == q->event_tail) {
181 static int notified;
182
183 if (notified++ == 0)
184 printk(KERN_ERR "apm: an event queue overflowed\n");
185 q->event_tail = (q->event_tail + 1) % APM_MAX_EVENTS;
186 }
187 q->events[q->event_head] = event;
188}
189
190static void queue_event(apm_event_t event)
191{
192 struct apm_user *as;
193
194 down_read(&user_list_lock);
195 list_for_each_entry(as, &apm_user_list, list) {
196 if (as->reader)
197 queue_add_event(&as->queue, event);
198 }
199 up_read(&user_list_lock);
200 wake_up_interruptible(&apm_waitqueue);
201}
202
203static ssize_t apm_read(struct file *fp, char __user *buf, size_t count, loff_t *ppos)
204{
205 struct apm_user *as = fp->private_data;
206 apm_event_t event;
207 int i = count, ret = 0;
208
209 if (count < sizeof(apm_event_t))
210 return -EINVAL;
211
212 if (queue_empty(&as->queue) && fp->f_flags & O_NONBLOCK)
213 return -EAGAIN;
214
215 wait_event_interruptible(apm_waitqueue, !queue_empty(&as->queue));
216
217 while ((i >= sizeof(event)) && !queue_empty(&as->queue)) {
218 event = queue_get_event(&as->queue);
219
220 ret = -EFAULT;
221 if (copy_to_user(buf, &event, sizeof(event)))
222 break;
223
224 mutex_lock(&state_lock);
225 if (as->suspend_state == SUSPEND_PENDING &&
226 (event == APM_SYS_SUSPEND || event == APM_USER_SUSPEND))
227 as->suspend_state = SUSPEND_READ;
228 mutex_unlock(&state_lock);
229
230 buf += sizeof(event);
231 i -= sizeof(event);
232 }
233
234 if (i < count)
235 ret = count - i;
236
237 return ret;
238}
239
240static __poll_t apm_poll(struct file *fp, poll_table * wait)
241{
242 struct apm_user *as = fp->private_data;
243
244 poll_wait(fp, &apm_waitqueue, wait);
245 return queue_empty(&as->queue) ? 0 : EPOLLIN | EPOLLRDNORM;
246}
247
248/*
249 * apm_ioctl - handle APM ioctl
250 *
251 * APM_IOC_SUSPEND
252 * This IOCTL is overloaded, and performs two functions. It is used to:
253 * - initiate a suspend
254 * - acknowledge a suspend read from /dev/apm_bios.
255 * Only when everyone who has opened /dev/apm_bios with write permission
256 * has acknowledge does the actual suspend happen.
257 */
258static long
259apm_ioctl(struct file *filp, u_int cmd, u_long arg)
260{
261 struct apm_user *as = filp->private_data;
262 int err = -EINVAL;
263
264 if (!as->suser || !as->writer)
265 return -EPERM;
266
267 switch (cmd) {
268 case APM_IOC_SUSPEND:
269 mutex_lock(&state_lock);
270
271 as->suspend_result = -EINTR;
272
273 switch (as->suspend_state) {
274 case SUSPEND_READ:
275 /*
276 * If we read a suspend command from /dev/apm_bios,
277 * then the corresponding APM_IOC_SUSPEND ioctl is
278 * interpreted as an acknowledge.
279 */
280 as->suspend_state = SUSPEND_ACKED;
281 atomic_dec(&suspend_acks_pending);
282 mutex_unlock(&state_lock);
283
284 /*
285 * suspend_acks_pending changed, the notifier needs to
286 * be woken up for this
287 */
288 wake_up(&apm_suspend_waitqueue);
289
290 /*
291 * Wait for the suspend/resume to complete. If there
292 * are pending acknowledges, we wait here for them.
293 * wait_event_freezable() is interruptible and pending
294 * signal can cause busy looping. We aren't doing
295 * anything critical, chill a bit on each iteration.
296 */
297 while (wait_event_freezable(apm_suspend_waitqueue,
298 as->suspend_state != SUSPEND_ACKED))
299 msleep(10);
300 break;
301 case SUSPEND_ACKTO:
302 as->suspend_result = -ETIMEDOUT;
303 mutex_unlock(&state_lock);
304 break;
305 default:
306 as->suspend_state = SUSPEND_WAIT;
307 mutex_unlock(&state_lock);
308
309 /*
310 * Otherwise it is a request to suspend the system.
311 * Just invoke pm_suspend(), we'll handle it from
312 * there via the notifier.
313 */
314 as->suspend_result = pm_suspend(PM_SUSPEND_MEM);
315 }
316
317 mutex_lock(&state_lock);
318 err = as->suspend_result;
319 as->suspend_state = SUSPEND_NONE;
320 mutex_unlock(&state_lock);
321 break;
322 }
323
324 return err;
325}
326
327static int apm_release(struct inode * inode, struct file * filp)
328{
329 struct apm_user *as = filp->private_data;
330
331 filp->private_data = NULL;
332
333 down_write(&user_list_lock);
334 list_del(&as->list);
335 up_write(&user_list_lock);
336
337 /*
338 * We are now unhooked from the chain. As far as new
339 * events are concerned, we no longer exist.
340 */
341 mutex_lock(&state_lock);
342 if (as->suspend_state == SUSPEND_PENDING ||
343 as->suspend_state == SUSPEND_READ)
344 atomic_dec(&suspend_acks_pending);
345 mutex_unlock(&state_lock);
346
347 wake_up(&apm_suspend_waitqueue);
348
349 kfree(as);
350 return 0;
351}
352
353static int apm_open(struct inode * inode, struct file * filp)
354{
355 struct apm_user *as;
356
357 as = kzalloc(sizeof(*as), GFP_KERNEL);
358 if (as) {
359 /*
360 * XXX - this is a tiny bit broken, when we consider BSD
361 * process accounting. If the device is opened by root, we
362 * instantly flag that we used superuser privs. Who knows,
363 * we might close the device immediately without doing a
364 * privileged operation -- cevans
365 */
366 as->suser = capable(CAP_SYS_ADMIN);
367 as->writer = (filp->f_mode & FMODE_WRITE) == FMODE_WRITE;
368 as->reader = (filp->f_mode & FMODE_READ) == FMODE_READ;
369
370 down_write(&user_list_lock);
371 list_add(&as->list, &apm_user_list);
372 up_write(&user_list_lock);
373
374 filp->private_data = as;
375 }
376
377 return as ? 0 : -ENOMEM;
378}
379
380static const struct file_operations apm_bios_fops = {
381 .owner = THIS_MODULE,
382 .read = apm_read,
383 .poll = apm_poll,
384 .unlocked_ioctl = apm_ioctl,
385 .open = apm_open,
386 .release = apm_release,
387 .llseek = noop_llseek,
388};
389
390static struct miscdevice apm_device = {
391 .minor = APM_MINOR_DEV,
392 .name = "apm_bios",
393 .fops = &apm_bios_fops
394};
395
396
397#ifdef CONFIG_PROC_FS
398/*
399 * Arguments, with symbols from linux/apm_bios.h.
400 *
401 * 0) Linux driver version (this will change if format changes)
402 * 1) APM BIOS Version. Usually 1.0, 1.1 or 1.2.
403 * 2) APM flags from APM Installation Check (0x00):
404 * bit 0: APM_16_BIT_SUPPORT
405 * bit 1: APM_32_BIT_SUPPORT
406 * bit 2: APM_IDLE_SLOWS_CLOCK
407 * bit 3: APM_BIOS_DISABLED
408 * bit 4: APM_BIOS_DISENGAGED
409 * 3) AC line status
410 * 0x00: Off-line
411 * 0x01: On-line
412 * 0x02: On backup power (BIOS >= 1.1 only)
413 * 0xff: Unknown
414 * 4) Battery status
415 * 0x00: High
416 * 0x01: Low
417 * 0x02: Critical
418 * 0x03: Charging
419 * 0x04: Selected battery not present (BIOS >= 1.2 only)
420 * 0xff: Unknown
421 * 5) Battery flag
422 * bit 0: High
423 * bit 1: Low
424 * bit 2: Critical
425 * bit 3: Charging
426 * bit 7: No system battery
427 * 0xff: Unknown
428 * 6) Remaining battery life (percentage of charge):
429 * 0-100: valid
430 * -1: Unknown
431 * 7) Remaining battery life (time units):
432 * Number of remaining minutes or seconds
433 * -1: Unknown
434 * 8) min = minutes; sec = seconds
435 */
436static int proc_apm_show(struct seq_file *m, void *v)
437{
438 struct apm_power_info info;
439 char *units;
440
441 info.ac_line_status = 0xff;
442 info.battery_status = 0xff;
443 info.battery_flag = 0xff;
444 info.battery_life = -1;
445 info.time = -1;
446 info.units = -1;
447
448 if (apm_get_power_status)
449 apm_get_power_status(&info);
450
451 switch (info.units) {
452 default: units = "?"; break;
453 case 0: units = "min"; break;
454 case 1: units = "sec"; break;
455 }
456
457 seq_printf(m, "%s 1.2 0x%02x 0x%02x 0x%02x 0x%02x %d%% %d %s\n",
458 driver_version, APM_32_BIT_SUPPORT,
459 info.ac_line_status, info.battery_status,
460 info.battery_flag, info.battery_life,
461 info.time, units);
462
463 return 0;
464}
465#endif
466
467static int kapmd(void *arg)
468{
469 do {
470 apm_event_t event;
471
472 wait_event_interruptible(kapmd_wait,
473 !queue_empty(&kapmd_queue) || kthread_should_stop());
474
475 if (kthread_should_stop())
476 break;
477
478 spin_lock_irq(&kapmd_queue_lock);
479 event = 0;
480 if (!queue_empty(&kapmd_queue))
481 event = queue_get_event(&kapmd_queue);
482 spin_unlock_irq(&kapmd_queue_lock);
483
484 switch (event) {
485 case 0:
486 break;
487
488 case APM_LOW_BATTERY:
489 case APM_POWER_STATUS_CHANGE:
490 queue_event(event);
491 break;
492
493 case APM_USER_SUSPEND:
494 case APM_SYS_SUSPEND:
495 pm_suspend(PM_SUSPEND_MEM);
496 break;
497
498 case APM_CRITICAL_SUSPEND:
499 atomic_inc(&userspace_notification_inhibit);
500 pm_suspend(PM_SUSPEND_MEM);
501 atomic_dec(&userspace_notification_inhibit);
502 break;
503 }
504 } while (1);
505
506 return 0;
507}
508
509static int apm_suspend_notifier(struct notifier_block *nb,
510 unsigned long event,
511 void *dummy)
512{
513 struct apm_user *as;
514 int err;
515 unsigned long apm_event;
516
517 /* short-cut emergency suspends */
518 if (atomic_read(&userspace_notification_inhibit))
519 return NOTIFY_DONE;
520
521 switch (event) {
522 case PM_SUSPEND_PREPARE:
523 case PM_HIBERNATION_PREPARE:
524 apm_event = (event == PM_SUSPEND_PREPARE) ?
525 APM_USER_SUSPEND : APM_USER_HIBERNATION;
526 /*
527 * Queue an event to all "writer" users that we want
528 * to suspend and need their ack.
529 */
530 mutex_lock(&state_lock);
531 down_read(&user_list_lock);
532
533 list_for_each_entry(as, &apm_user_list, list) {
534 if (as->suspend_state != SUSPEND_WAIT && as->reader &&
535 as->writer && as->suser) {
536 as->suspend_state = SUSPEND_PENDING;
537 atomic_inc(&suspend_acks_pending);
538 queue_add_event(&as->queue, apm_event);
539 }
540 }
541
542 up_read(&user_list_lock);
543 mutex_unlock(&state_lock);
544 wake_up_interruptible(&apm_waitqueue);
545
546 /*
547 * Wait for the suspend_acks_pending variable to drop to
548 * zero, meaning everybody acked the suspend event (or the
549 * process was killed.)
550 *
551 * If the app won't answer within a short while we assume it
552 * locked up and ignore it.
553 */
554 err = wait_event_interruptible_timeout(
555 apm_suspend_waitqueue,
556 atomic_read(&suspend_acks_pending) == 0,
557 5*HZ);
558
559 /* timed out */
560 if (err == 0) {
561 /*
562 * Move anybody who timed out to "ack timeout" state.
563 *
564 * We could time out and the userspace does the ACK
565 * right after we time out but before we enter the
566 * locked section here, but that's fine.
567 */
568 mutex_lock(&state_lock);
569 down_read(&user_list_lock);
570 list_for_each_entry(as, &apm_user_list, list) {
571 if (as->suspend_state == SUSPEND_PENDING ||
572 as->suspend_state == SUSPEND_READ) {
573 as->suspend_state = SUSPEND_ACKTO;
574 atomic_dec(&suspend_acks_pending);
575 }
576 }
577 up_read(&user_list_lock);
578 mutex_unlock(&state_lock);
579 }
580
581 /* let suspend proceed */
582 if (err >= 0)
583 return NOTIFY_OK;
584
585 /* interrupted by signal */
586 return notifier_from_errno(err);
587
588 case PM_POST_SUSPEND:
589 case PM_POST_HIBERNATION:
590 apm_event = (event == PM_POST_SUSPEND) ?
591 APM_NORMAL_RESUME : APM_HIBERNATION_RESUME;
592 /*
593 * Anyone on the APM queues will think we're still suspended.
594 * Send a message so everyone knows we're now awake again.
595 */
596 queue_event(apm_event);
597
598 /*
599 * Finally, wake up anyone who is sleeping on the suspend.
600 */
601 mutex_lock(&state_lock);
602 down_read(&user_list_lock);
603 list_for_each_entry(as, &apm_user_list, list) {
604 if (as->suspend_state == SUSPEND_ACKED) {
605 /*
606 * TODO: maybe grab error code, needs core
607 * changes to push the error to the notifier
608 * chain (could use the second parameter if
609 * implemented)
610 */
611 as->suspend_result = 0;
612 as->suspend_state = SUSPEND_DONE;
613 }
614 }
615 up_read(&user_list_lock);
616 mutex_unlock(&state_lock);
617
618 wake_up(&apm_suspend_waitqueue);
619 return NOTIFY_OK;
620
621 default:
622 return NOTIFY_DONE;
623 }
624}
625
626static struct notifier_block apm_notif_block = {
627 .notifier_call = apm_suspend_notifier,
628};
629
630static int __init apm_init(void)
631{
632 int ret;
633
634 if (apm_disabled) {
635 printk(KERN_NOTICE "apm: disabled on user request.\n");
636 return -ENODEV;
637 }
638
639 kapmd_tsk = kthread_create(kapmd, NULL, "kapmd");
640 if (IS_ERR(kapmd_tsk)) {
641 ret = PTR_ERR(kapmd_tsk);
642 kapmd_tsk = NULL;
643 goto out;
644 }
645 wake_up_process(kapmd_tsk);
646
647#ifdef CONFIG_PROC_FS
648 proc_create_single("apm", 0, NULL, proc_apm_show);
649#endif
650
651 ret = misc_register(&apm_device);
652 if (ret)
653 goto out_stop;
654
655 ret = register_pm_notifier(&apm_notif_block);
656 if (ret)
657 goto out_unregister;
658
659 return 0;
660
661 out_unregister:
662 misc_deregister(&apm_device);
663 out_stop:
664 remove_proc_entry("apm", NULL);
665 kthread_stop(kapmd_tsk);
666 out:
667 return ret;
668}
669
670static void __exit apm_exit(void)
671{
672 unregister_pm_notifier(&apm_notif_block);
673 misc_deregister(&apm_device);
674 remove_proc_entry("apm", NULL);
675
676 kthread_stop(kapmd_tsk);
677}
678
679module_init(apm_init);
680module_exit(apm_exit);
681
682MODULE_AUTHOR("Stephen Rothwell");
683MODULE_DESCRIPTION("Advanced Power Management");
684MODULE_LICENSE("GPL");
685
686#ifndef MODULE
687static int __init apm_setup(char *str)
688{
689 while ((str != NULL) && (*str != '\0')) {
690 if (strncmp(str, "off", 3) == 0)
691 apm_disabled = 1;
692 if (strncmp(str, "on", 2) == 0)
693 apm_disabled = 0;
694 str = strchr(str, ',');
695 if (str != NULL)
696 str += strspn(str, ", \t");
697 }
698 return 1;
699}
700
701__setup("apm=", apm_setup);
702#endif
703
704/**
705 * apm_queue_event - queue an APM event for kapmd
706 * @event: APM event
707 *
708 * Queue an APM event for kapmd to process and ultimately take the
709 * appropriate action. Only a subset of events are handled:
710 * %APM_LOW_BATTERY
711 * %APM_POWER_STATUS_CHANGE
712 * %APM_USER_SUSPEND
713 * %APM_SYS_SUSPEND
714 * %APM_CRITICAL_SUSPEND
715 */
716void apm_queue_event(apm_event_t event)
717{
718 unsigned long flags;
719
720 spin_lock_irqsave(&kapmd_queue_lock, flags);
721 queue_add_event(&kapmd_queue, event);
722 spin_unlock_irqrestore(&kapmd_queue_lock, flags);
723
724 wake_up_interruptible(&kapmd_wait);
725}
726EXPORT_SYMBOL(apm_queue_event);
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
44struct 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 */
89enum 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 */
102struct 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 */
118static atomic_t suspend_acks_pending = ATOMIC_INIT(0);
119static atomic_t userspace_notification_inhibit = ATOMIC_INIT(0);
120static int apm_disabled;
121static struct task_struct *kapmd_tsk;
122
123static DECLARE_WAIT_QUEUE_HEAD(apm_waitqueue);
124static DECLARE_WAIT_QUEUE_HEAD(apm_suspend_waitqueue);
125
126/*
127 * This is a list of everyone who has opened /dev/apm_bios
128 */
129static DECLARE_RWSEM(user_list_lock);
130static 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 */
137static DECLARE_WAIT_QUEUE_HEAD(kapmd_wait);
138static DEFINE_SPINLOCK(kapmd_queue_lock);
139static struct apm_queue kapmd_queue;
140
141static DEFINE_MUTEX(state_lock);
142
143static 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 */
151static 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 */
158void (*apm_get_power_status)(struct apm_power_info *) = __apm_get_power_status;
159EXPORT_SYMBOL(apm_get_power_status);
160
161
162/*
163 * APM event queue management.
164 */
165static inline int queue_empty(struct apm_queue *q)
166{
167 return q->event_head == q->event_tail;
168}
169
170static 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
176static 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
189static 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
202static 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
239static __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 */
257static long
258apm_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
326static 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
352static 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
379static 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
389static 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 */
435static 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
465static int proc_apm_open(struct inode *inode, struct file *file)
466{
467 return single_open(file, proc_apm_show, NULL);
468}
469
470static const struct file_operations apm_proc_fops = {
471 .owner = THIS_MODULE,
472 .open = proc_apm_open,
473 .read = seq_read,
474 .llseek = seq_lseek,
475 .release = single_release,
476};
477#endif
478
479static int kapmd(void *arg)
480{
481 do {
482 apm_event_t event;
483
484 wait_event_interruptible(kapmd_wait,
485 !queue_empty(&kapmd_queue) || kthread_should_stop());
486
487 if (kthread_should_stop())
488 break;
489
490 spin_lock_irq(&kapmd_queue_lock);
491 event = 0;
492 if (!queue_empty(&kapmd_queue))
493 event = queue_get_event(&kapmd_queue);
494 spin_unlock_irq(&kapmd_queue_lock);
495
496 switch (event) {
497 case 0:
498 break;
499
500 case APM_LOW_BATTERY:
501 case APM_POWER_STATUS_CHANGE:
502 queue_event(event);
503 break;
504
505 case APM_USER_SUSPEND:
506 case APM_SYS_SUSPEND:
507 pm_suspend(PM_SUSPEND_MEM);
508 break;
509
510 case APM_CRITICAL_SUSPEND:
511 atomic_inc(&userspace_notification_inhibit);
512 pm_suspend(PM_SUSPEND_MEM);
513 atomic_dec(&userspace_notification_inhibit);
514 break;
515 }
516 } while (1);
517
518 return 0;
519}
520
521static int apm_suspend_notifier(struct notifier_block *nb,
522 unsigned long event,
523 void *dummy)
524{
525 struct apm_user *as;
526 int err;
527 unsigned long apm_event;
528
529 /* short-cut emergency suspends */
530 if (atomic_read(&userspace_notification_inhibit))
531 return NOTIFY_DONE;
532
533 switch (event) {
534 case PM_SUSPEND_PREPARE:
535 case PM_HIBERNATION_PREPARE:
536 apm_event = (event == PM_SUSPEND_PREPARE) ?
537 APM_USER_SUSPEND : APM_USER_HIBERNATION;
538 /*
539 * Queue an event to all "writer" users that we want
540 * to suspend and need their ack.
541 */
542 mutex_lock(&state_lock);
543 down_read(&user_list_lock);
544
545 list_for_each_entry(as, &apm_user_list, list) {
546 if (as->suspend_state != SUSPEND_WAIT && as->reader &&
547 as->writer && as->suser) {
548 as->suspend_state = SUSPEND_PENDING;
549 atomic_inc(&suspend_acks_pending);
550 queue_add_event(&as->queue, apm_event);
551 }
552 }
553
554 up_read(&user_list_lock);
555 mutex_unlock(&state_lock);
556 wake_up_interruptible(&apm_waitqueue);
557
558 /*
559 * Wait for the the suspend_acks_pending variable to drop to
560 * zero, meaning everybody acked the suspend event (or the
561 * process was killed.)
562 *
563 * If the app won't answer within a short while we assume it
564 * locked up and ignore it.
565 */
566 err = wait_event_interruptible_timeout(
567 apm_suspend_waitqueue,
568 atomic_read(&suspend_acks_pending) == 0,
569 5*HZ);
570
571 /* timed out */
572 if (err == 0) {
573 /*
574 * Move anybody who timed out to "ack timeout" state.
575 *
576 * We could time out and the userspace does the ACK
577 * right after we time out but before we enter the
578 * locked section here, but that's fine.
579 */
580 mutex_lock(&state_lock);
581 down_read(&user_list_lock);
582 list_for_each_entry(as, &apm_user_list, list) {
583 if (as->suspend_state == SUSPEND_PENDING ||
584 as->suspend_state == SUSPEND_READ) {
585 as->suspend_state = SUSPEND_ACKTO;
586 atomic_dec(&suspend_acks_pending);
587 }
588 }
589 up_read(&user_list_lock);
590 mutex_unlock(&state_lock);
591 }
592
593 /* let suspend proceed */
594 if (err >= 0)
595 return NOTIFY_OK;
596
597 /* interrupted by signal */
598 return notifier_from_errno(err);
599
600 case PM_POST_SUSPEND:
601 case PM_POST_HIBERNATION:
602 apm_event = (event == PM_POST_SUSPEND) ?
603 APM_NORMAL_RESUME : APM_HIBERNATION_RESUME;
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_event);
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);