Loading...
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#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 switch (cmd) {
278 case APM_IOC_SUSPEND:
279 mutex_lock(&state_lock);
280
281 as->suspend_result = -EINTR;
282
283 switch (as->suspend_state) {
284 case SUSPEND_READ:
285 /*
286 * If we read a suspend command from /dev/apm_bios,
287 * then the corresponding APM_IOC_SUSPEND ioctl is
288 * interpreted as an acknowledge.
289 */
290 as->suspend_state = SUSPEND_ACKED;
291 atomic_dec(&suspend_acks_pending);
292 mutex_unlock(&state_lock);
293
294 /*
295 * suspend_acks_pending changed, the notifier needs to
296 * be woken up for this
297 */
298 wake_up(&apm_suspend_waitqueue);
299
300 /*
301 * Wait for the suspend/resume to complete. If there
302 * are pending acknowledges, we wait here for them.
303 */
304 freezer_do_not_count();
305
306 wait_event(apm_suspend_waitqueue,
307 as->suspend_state == SUSPEND_DONE);
308
309 /*
310 * Since we are waiting until the suspend is done, the
311 * try_to_freeze() in freezer_count() will not trigger
312 */
313 freezer_count();
314 break;
315 case SUSPEND_ACKTO:
316 as->suspend_result = -ETIMEDOUT;
317 mutex_unlock(&state_lock);
318 break;
319 default:
320 as->suspend_state = SUSPEND_WAIT;
321 mutex_unlock(&state_lock);
322
323 /*
324 * Otherwise it is a request to suspend the system.
325 * Just invoke pm_suspend(), we'll handle it from
326 * there via the notifier.
327 */
328 as->suspend_result = pm_suspend(PM_SUSPEND_MEM);
329 }
330
331 mutex_lock(&state_lock);
332 err = as->suspend_result;
333 as->suspend_state = SUSPEND_NONE;
334 mutex_unlock(&state_lock);
335 break;
336 }
337
338 return err;
339}
340
341static int apm_release(struct inode * inode, struct file * filp)
342{
343 struct apm_user *as = filp->private_data;
344
345 filp->private_data = NULL;
346
347 down_write(&user_list_lock);
348 list_del(&as->list);
349 up_write(&user_list_lock);
350
351 /*
352 * We are now unhooked from the chain. As far as new
353 * events are concerned, we no longer exist.
354 */
355 mutex_lock(&state_lock);
356 if (as->suspend_state == SUSPEND_PENDING ||
357 as->suspend_state == SUSPEND_READ)
358 atomic_dec(&suspend_acks_pending);
359 mutex_unlock(&state_lock);
360
361 wake_up(&apm_suspend_waitqueue);
362
363 kfree(as);
364 return 0;
365}
366
367static int apm_open(struct inode * inode, struct file * filp)
368{
369 struct apm_user *as;
370
371 as = kzalloc(sizeof(*as), GFP_KERNEL);
372 if (as) {
373 /*
374 * XXX - this is a tiny bit broken, when we consider BSD
375 * process accounting. If the device is opened by root, we
376 * instantly flag that we used superuser privs. Who knows,
377 * we might close the device immediately without doing a
378 * privileged operation -- cevans
379 */
380 as->suser = capable(CAP_SYS_ADMIN);
381 as->writer = (filp->f_mode & FMODE_WRITE) == FMODE_WRITE;
382 as->reader = (filp->f_mode & FMODE_READ) == FMODE_READ;
383
384 down_write(&user_list_lock);
385 list_add(&as->list, &apm_user_list);
386 up_write(&user_list_lock);
387
388 filp->private_data = as;
389 }
390
391 return as ? 0 : -ENOMEM;
392}
393
394static const struct file_operations apm_bios_fops = {
395 .owner = THIS_MODULE,
396 .read = apm_read,
397 .poll = apm_poll,
398 .unlocked_ioctl = apm_ioctl,
399 .open = apm_open,
400 .release = apm_release,
401 .llseek = noop_llseek,
402};
403
404static struct miscdevice apm_device = {
405 .minor = APM_MINOR_DEV,
406 .name = "apm_bios",
407 .fops = &apm_bios_fops
408};
409
410
411#ifdef CONFIG_PROC_FS
412/*
413 * Arguments, with symbols from linux/apm_bios.h.
414 *
415 * 0) Linux driver version (this will change if format changes)
416 * 1) APM BIOS Version. Usually 1.0, 1.1 or 1.2.
417 * 2) APM flags from APM Installation Check (0x00):
418 * bit 0: APM_16_BIT_SUPPORT
419 * bit 1: APM_32_BIT_SUPPORT
420 * bit 2: APM_IDLE_SLOWS_CLOCK
421 * bit 3: APM_BIOS_DISABLED
422 * bit 4: APM_BIOS_DISENGAGED
423 * 3) AC line status
424 * 0x00: Off-line
425 * 0x01: On-line
426 * 0x02: On backup power (BIOS >= 1.1 only)
427 * 0xff: Unknown
428 * 4) Battery status
429 * 0x00: High
430 * 0x01: Low
431 * 0x02: Critical
432 * 0x03: Charging
433 * 0x04: Selected battery not present (BIOS >= 1.2 only)
434 * 0xff: Unknown
435 * 5) Battery flag
436 * bit 0: High
437 * bit 1: Low
438 * bit 2: Critical
439 * bit 3: Charging
440 * bit 7: No system battery
441 * 0xff: Unknown
442 * 6) Remaining battery life (percentage of charge):
443 * 0-100: valid
444 * -1: Unknown
445 * 7) Remaining battery life (time units):
446 * Number of remaining minutes or seconds
447 * -1: Unknown
448 * 8) min = minutes; sec = seconds
449 */
450static int proc_apm_show(struct seq_file *m, void *v)
451{
452 struct apm_power_info info;
453 char *units;
454
455 info.ac_line_status = 0xff;
456 info.battery_status = 0xff;
457 info.battery_flag = 0xff;
458 info.battery_life = -1;
459 info.time = -1;
460 info.units = -1;
461
462 if (apm_get_power_status)
463 apm_get_power_status(&info);
464
465 switch (info.units) {
466 default: units = "?"; break;
467 case 0: units = "min"; break;
468 case 1: units = "sec"; break;
469 }
470
471 seq_printf(m, "%s 1.2 0x%02x 0x%02x 0x%02x 0x%02x %d%% %d %s\n",
472 driver_version, APM_32_BIT_SUPPORT,
473 info.ac_line_status, info.battery_status,
474 info.battery_flag, info.battery_life,
475 info.time, units);
476
477 return 0;
478}
479
480static int proc_apm_open(struct inode *inode, struct file *file)
481{
482 return single_open(file, proc_apm_show, NULL);
483}
484
485static const struct file_operations apm_proc_fops = {
486 .owner = THIS_MODULE,
487 .open = proc_apm_open,
488 .read = seq_read,
489 .llseek = seq_lseek,
490 .release = single_release,
491};
492#endif
493
494static int kapmd(void *arg)
495{
496 do {
497 apm_event_t event;
498
499 wait_event_interruptible(kapmd_wait,
500 !queue_empty(&kapmd_queue) || kthread_should_stop());
501
502 if (kthread_should_stop())
503 break;
504
505 spin_lock_irq(&kapmd_queue_lock);
506 event = 0;
507 if (!queue_empty(&kapmd_queue))
508 event = queue_get_event(&kapmd_queue);
509 spin_unlock_irq(&kapmd_queue_lock);
510
511 switch (event) {
512 case 0:
513 break;
514
515 case APM_LOW_BATTERY:
516 case APM_POWER_STATUS_CHANGE:
517 queue_event(event);
518 break;
519
520 case APM_USER_SUSPEND:
521 case APM_SYS_SUSPEND:
522 pm_suspend(PM_SUSPEND_MEM);
523 break;
524
525 case APM_CRITICAL_SUSPEND:
526 atomic_inc(&userspace_notification_inhibit);
527 pm_suspend(PM_SUSPEND_MEM);
528 atomic_dec(&userspace_notification_inhibit);
529 break;
530 }
531 } while (1);
532
533 return 0;
534}
535
536static int apm_suspend_notifier(struct notifier_block *nb,
537 unsigned long event,
538 void *dummy)
539{
540 struct apm_user *as;
541 int err;
542
543 /* short-cut emergency suspends */
544 if (atomic_read(&userspace_notification_inhibit))
545 return NOTIFY_DONE;
546
547 switch (event) {
548 case PM_SUSPEND_PREPARE:
549 /*
550 * Queue an event to all "writer" users that we want
551 * to suspend and need their ack.
552 */
553 mutex_lock(&state_lock);
554 down_read(&user_list_lock);
555
556 list_for_each_entry(as, &apm_user_list, list) {
557 if (as->suspend_state != SUSPEND_WAIT && as->reader &&
558 as->writer && as->suser) {
559 as->suspend_state = SUSPEND_PENDING;
560 atomic_inc(&suspend_acks_pending);
561 queue_add_event(&as->queue, APM_USER_SUSPEND);
562 }
563 }
564
565 up_read(&user_list_lock);
566 mutex_unlock(&state_lock);
567 wake_up_interruptible(&apm_waitqueue);
568
569 /*
570 * Wait for the the suspend_acks_pending variable to drop to
571 * zero, meaning everybody acked the suspend event (or the
572 * process was killed.)
573 *
574 * If the app won't answer within a short while we assume it
575 * locked up and ignore it.
576 */
577 err = wait_event_interruptible_timeout(
578 apm_suspend_waitqueue,
579 atomic_read(&suspend_acks_pending) == 0,
580 5*HZ);
581
582 /* timed out */
583 if (err == 0) {
584 /*
585 * Move anybody who timed out to "ack timeout" state.
586 *
587 * We could time out and the userspace does the ACK
588 * right after we time out but before we enter the
589 * locked section here, but that's fine.
590 */
591 mutex_lock(&state_lock);
592 down_read(&user_list_lock);
593 list_for_each_entry(as, &apm_user_list, list) {
594 if (as->suspend_state == SUSPEND_PENDING ||
595 as->suspend_state == SUSPEND_READ) {
596 as->suspend_state = SUSPEND_ACKTO;
597 atomic_dec(&suspend_acks_pending);
598 }
599 }
600 up_read(&user_list_lock);
601 mutex_unlock(&state_lock);
602 }
603
604 /* let suspend proceed */
605 if (err >= 0)
606 return NOTIFY_OK;
607
608 /* interrupted by signal */
609 return notifier_from_errno(err);
610
611 case PM_POST_SUSPEND:
612 /*
613 * Anyone on the APM queues will think we're still suspended.
614 * Send a message so everyone knows we're now awake again.
615 */
616 queue_event(APM_NORMAL_RESUME);
617
618 /*
619 * Finally, wake up anyone who is sleeping on the suspend.
620 */
621 mutex_lock(&state_lock);
622 down_read(&user_list_lock);
623 list_for_each_entry(as, &apm_user_list, list) {
624 if (as->suspend_state == SUSPEND_ACKED) {
625 /*
626 * TODO: maybe grab error code, needs core
627 * changes to push the error to the notifier
628 * chain (could use the second parameter if
629 * implemented)
630 */
631 as->suspend_result = 0;
632 as->suspend_state = SUSPEND_DONE;
633 }
634 }
635 up_read(&user_list_lock);
636 mutex_unlock(&state_lock);
637
638 wake_up(&apm_suspend_waitqueue);
639 return NOTIFY_OK;
640
641 default:
642 return NOTIFY_DONE;
643 }
644}
645
646static struct notifier_block apm_notif_block = {
647 .notifier_call = apm_suspend_notifier,
648};
649
650static int __init apm_init(void)
651{
652 int ret;
653
654 if (apm_disabled) {
655 printk(KERN_NOTICE "apm: disabled on user request.\n");
656 return -ENODEV;
657 }
658
659 kapmd_tsk = kthread_create(kapmd, NULL, "kapmd");
660 if (IS_ERR(kapmd_tsk)) {
661 ret = PTR_ERR(kapmd_tsk);
662 kapmd_tsk = NULL;
663 goto out;
664 }
665 wake_up_process(kapmd_tsk);
666
667#ifdef CONFIG_PROC_FS
668 proc_create("apm", 0, NULL, &apm_proc_fops);
669#endif
670
671 ret = misc_register(&apm_device);
672 if (ret)
673 goto out_stop;
674
675 ret = register_pm_notifier(&apm_notif_block);
676 if (ret)
677 goto out_unregister;
678
679 return 0;
680
681 out_unregister:
682 misc_deregister(&apm_device);
683 out_stop:
684 remove_proc_entry("apm", NULL);
685 kthread_stop(kapmd_tsk);
686 out:
687 return ret;
688}
689
690static void __exit apm_exit(void)
691{
692 unregister_pm_notifier(&apm_notif_block);
693 misc_deregister(&apm_device);
694 remove_proc_entry("apm", NULL);
695
696 kthread_stop(kapmd_tsk);
697}
698
699module_init(apm_init);
700module_exit(apm_exit);
701
702MODULE_AUTHOR("Stephen Rothwell");
703MODULE_DESCRIPTION("Advanced Power Management");
704MODULE_LICENSE("GPL");
705
706#ifndef MODULE
707static int __init apm_setup(char *str)
708{
709 while ((str != NULL) && (*str != '\0')) {
710 if (strncmp(str, "off", 3) == 0)
711 apm_disabled = 1;
712 if (strncmp(str, "on", 2) == 0)
713 apm_disabled = 0;
714 str = strchr(str, ',');
715 if (str != NULL)
716 str += strspn(str, ", \t");
717 }
718 return 1;
719}
720
721__setup("apm=", apm_setup);
722#endif
723
724/**
725 * apm_queue_event - queue an APM event for kapmd
726 * @event: APM event
727 *
728 * Queue an APM event for kapmd to process and ultimately take the
729 * appropriate action. Only a subset of events are handled:
730 * %APM_LOW_BATTERY
731 * %APM_POWER_STATUS_CHANGE
732 * %APM_USER_SUSPEND
733 * %APM_SYS_SUSPEND
734 * %APM_CRITICAL_SUSPEND
735 */
736void apm_queue_event(apm_event_t event)
737{
738 unsigned long flags;
739
740 spin_lock_irqsave(&kapmd_queue_lock, flags);
741 queue_add_event(&kapmd_queue, event);
742 spin_unlock_irqrestore(&kapmd_queue_lock, flags);
743
744 wake_up_interruptible(&kapmd_wait);
745}
746EXPORT_SYMBOL(apm_queue_event);