Merge branch 'for-next' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/trivial
[linux-2.6/linux-acpi-2.6/ibm-acpi-2.6.git] / drivers / char / apm-emulation.c
blob45b987c9889e704e4d31aba542a63200edac5f16
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)
6 * APM 1.2 Reference:
7 * Intel Corporation, Microsoft Corporation. Advanced Power Management
8 * (APM) BIOS Interface Specification, Revision 1.2, February 1996.
10 * This document is available from Microsoft at:
11 * http://www.microsoft.com/whdc/archive/amp_12.mspx
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>
34 #include <asm/system.h>
37 * The apm_bios device is one of the misc char devices.
38 * This is its minor number.
40 #define APM_MINOR_DEV 134
43 * See Documentation/Config.help for the configuration options.
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
51 * Maximum number of events stored
53 #define APM_MAX_EVENTS 16
55 struct apm_queue {
56 unsigned int event_head;
57 unsigned int event_tail;
58 apm_event_t events[APM_MAX_EVENTS];
62 * thread states (for threads using a writable /dev/apm_bios fd):
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
73 * SUSPEND_WAIT: this thread invoked suspend and is waiting for resume
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
80 * While in PENDING or READ, the thread is accounted for in the
81 * suspend_acks_pending counter.
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
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
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
100 enum apm_suspend_state {
101 SUSPEND_NONE,
102 SUSPEND_PENDING,
103 SUSPEND_READ,
104 SUSPEND_ACKED,
105 SUSPEND_ACKTO,
106 SUSPEND_WAIT,
107 SUSPEND_DONE,
111 * The per-file APM data
113 struct apm_user {
114 struct list_head list;
116 unsigned int suser: 1;
117 unsigned int writer: 1;
118 unsigned int reader: 1;
120 int suspend_result;
121 enum apm_suspend_state suspend_state;
123 struct apm_queue queue;
127 * Local variables
129 static DEFINE_MUTEX(apm_mutex);
130 static atomic_t suspend_acks_pending = ATOMIC_INIT(0);
131 static atomic_t userspace_notification_inhibit = ATOMIC_INIT(0);
132 static int apm_disabled;
133 static struct task_struct *kapmd_tsk;
135 static DECLARE_WAIT_QUEUE_HEAD(apm_waitqueue);
136 static DECLARE_WAIT_QUEUE_HEAD(apm_suspend_waitqueue);
139 * This is a list of everyone who has opened /dev/apm_bios
141 static DECLARE_RWSEM(user_list_lock);
142 static LIST_HEAD(apm_user_list);
145 * kapmd info. kapmd provides us a process context to handle
146 * "APM" events within - specifically necessary if we're going
147 * to be suspending the system.
149 static DECLARE_WAIT_QUEUE_HEAD(kapmd_wait);
150 static DEFINE_SPINLOCK(kapmd_queue_lock);
151 static struct apm_queue kapmd_queue;
153 static DEFINE_MUTEX(state_lock);
155 static const char driver_version[] = "1.13"; /* no spaces */
160 * Compatibility cruft until the IPAQ people move over to the new
161 * interface.
163 static void __apm_get_power_status(struct apm_power_info *info)
168 * This allows machines to provide their own "apm get power status" function.
170 void (*apm_get_power_status)(struct apm_power_info *) = __apm_get_power_status;
171 EXPORT_SYMBOL(apm_get_power_status);
175 * APM event queue management.
177 static inline int queue_empty(struct apm_queue *q)
179 return q->event_head == q->event_tail;
182 static inline apm_event_t queue_get_event(struct apm_queue *q)
184 q->event_tail = (q->event_tail + 1) % APM_MAX_EVENTS;
185 return q->events[q->event_tail];
188 static void queue_add_event(struct apm_queue *q, apm_event_t event)
190 q->event_head = (q->event_head + 1) % APM_MAX_EVENTS;
191 if (q->event_head == q->event_tail) {
192 static int notified;
194 if (notified++ == 0)
195 printk(KERN_ERR "apm: an event queue overflowed\n");
196 q->event_tail = (q->event_tail + 1) % APM_MAX_EVENTS;
198 q->events[q->event_head] = event;
201 static void queue_event(apm_event_t event)
203 struct apm_user *as;
205 down_read(&user_list_lock);
206 list_for_each_entry(as, &apm_user_list, list) {
207 if (as->reader)
208 queue_add_event(&as->queue, event);
210 up_read(&user_list_lock);
211 wake_up_interruptible(&apm_waitqueue);
214 static ssize_t apm_read(struct file *fp, char __user *buf, size_t count, loff_t *ppos)
216 struct apm_user *as = fp->private_data;
217 apm_event_t event;
218 int i = count, ret = 0;
220 if (count < sizeof(apm_event_t))
221 return -EINVAL;
223 if (queue_empty(&as->queue) && fp->f_flags & O_NONBLOCK)
224 return -EAGAIN;
226 wait_event_interruptible(apm_waitqueue, !queue_empty(&as->queue));
228 while ((i >= sizeof(event)) && !queue_empty(&as->queue)) {
229 event = queue_get_event(&as->queue);
231 ret = -EFAULT;
232 if (copy_to_user(buf, &event, sizeof(event)))
233 break;
235 mutex_lock(&state_lock);
236 if (as->suspend_state == SUSPEND_PENDING &&
237 (event == APM_SYS_SUSPEND || event == APM_USER_SUSPEND))
238 as->suspend_state = SUSPEND_READ;
239 mutex_unlock(&state_lock);
241 buf += sizeof(event);
242 i -= sizeof(event);
245 if (i < count)
246 ret = count - i;
248 return ret;
251 static unsigned int apm_poll(struct file *fp, poll_table * wait)
253 struct apm_user *as = fp->private_data;
255 poll_wait(fp, &apm_waitqueue, wait);
256 return queue_empty(&as->queue) ? 0 : POLLIN | POLLRDNORM;
260 * apm_ioctl - handle APM ioctl
262 * APM_IOC_SUSPEND
263 * This IOCTL is overloaded, and performs two functions. It is used to:
264 * - initiate a suspend
265 * - acknowledge a suspend read from /dev/apm_bios.
266 * Only when everyone who has opened /dev/apm_bios with write permission
267 * has acknowledge does the actual suspend happen.
269 static long
270 apm_ioctl(struct file *filp, u_int cmd, u_long arg)
272 struct apm_user *as = filp->private_data;
273 int err = -EINVAL;
275 if (!as->suser || !as->writer)
276 return -EPERM;
278 mutex_lock(&apm_mutex);
279 switch (cmd) {
280 case APM_IOC_SUSPEND:
281 mutex_lock(&state_lock);
283 as->suspend_result = -EINTR;
285 switch (as->suspend_state) {
286 case SUSPEND_READ:
288 * If we read a suspend command from /dev/apm_bios,
289 * then the corresponding APM_IOC_SUSPEND ioctl is
290 * interpreted as an acknowledge.
292 as->suspend_state = SUSPEND_ACKED;
293 atomic_dec(&suspend_acks_pending);
294 mutex_unlock(&state_lock);
297 * suspend_acks_pending changed, the notifier needs to
298 * be woken up for this
300 wake_up(&apm_suspend_waitqueue);
303 * Wait for the suspend/resume to complete. If there
304 * are pending acknowledges, we wait here for them.
306 freezer_do_not_count();
308 wait_event(apm_suspend_waitqueue,
309 as->suspend_state == SUSPEND_DONE);
312 * Since we are waiting until the suspend is done, the
313 * try_to_freeze() in freezer_count() will not trigger
315 freezer_count();
316 break;
317 case SUSPEND_ACKTO:
318 as->suspend_result = -ETIMEDOUT;
319 mutex_unlock(&state_lock);
320 break;
321 default:
322 as->suspend_state = SUSPEND_WAIT;
323 mutex_unlock(&state_lock);
326 * Otherwise it is a request to suspend the system.
327 * Just invoke pm_suspend(), we'll handle it from
328 * there via the notifier.
330 as->suspend_result = pm_suspend(PM_SUSPEND_MEM);
333 mutex_lock(&state_lock);
334 err = as->suspend_result;
335 as->suspend_state = SUSPEND_NONE;
336 mutex_unlock(&state_lock);
337 break;
339 mutex_unlock(&apm_mutex);
341 return err;
344 static int apm_release(struct inode * inode, struct file * filp)
346 struct apm_user *as = filp->private_data;
348 filp->private_data = NULL;
350 down_write(&user_list_lock);
351 list_del(&as->list);
352 up_write(&user_list_lock);
355 * We are now unhooked from the chain. As far as new
356 * events are concerned, we no longer exist.
358 mutex_lock(&state_lock);
359 if (as->suspend_state == SUSPEND_PENDING ||
360 as->suspend_state == SUSPEND_READ)
361 atomic_dec(&suspend_acks_pending);
362 mutex_unlock(&state_lock);
364 wake_up(&apm_suspend_waitqueue);
366 kfree(as);
367 return 0;
370 static int apm_open(struct inode * inode, struct file * filp)
372 struct apm_user *as;
374 mutex_lock(&apm_mutex);
375 as = kzalloc(sizeof(*as), GFP_KERNEL);
376 if (as) {
378 * XXX - this is a tiny bit broken, when we consider BSD
379 * process accounting. If the device is opened by root, we
380 * instantly flag that we used superuser privs. Who knows,
381 * we might close the device immediately without doing a
382 * privileged operation -- cevans
384 as->suser = capable(CAP_SYS_ADMIN);
385 as->writer = (filp->f_mode & FMODE_WRITE) == FMODE_WRITE;
386 as->reader = (filp->f_mode & FMODE_READ) == FMODE_READ;
388 down_write(&user_list_lock);
389 list_add(&as->list, &apm_user_list);
390 up_write(&user_list_lock);
392 filp->private_data = as;
394 mutex_unlock(&apm_mutex);
396 return as ? 0 : -ENOMEM;
399 static const struct file_operations apm_bios_fops = {
400 .owner = THIS_MODULE,
401 .read = apm_read,
402 .poll = apm_poll,
403 .unlocked_ioctl = apm_ioctl,
404 .open = apm_open,
405 .release = apm_release,
406 .llseek = noop_llseek,
409 static struct miscdevice apm_device = {
410 .minor = APM_MINOR_DEV,
411 .name = "apm_bios",
412 .fops = &apm_bios_fops
416 #ifdef CONFIG_PROC_FS
418 * Arguments, with symbols from linux/apm_bios.h.
420 * 0) Linux driver version (this will change if format changes)
421 * 1) APM BIOS Version. Usually 1.0, 1.1 or 1.2.
422 * 2) APM flags from APM Installation Check (0x00):
423 * bit 0: APM_16_BIT_SUPPORT
424 * bit 1: APM_32_BIT_SUPPORT
425 * bit 2: APM_IDLE_SLOWS_CLOCK
426 * bit 3: APM_BIOS_DISABLED
427 * bit 4: APM_BIOS_DISENGAGED
428 * 3) AC line status
429 * 0x00: Off-line
430 * 0x01: On-line
431 * 0x02: On backup power (BIOS >= 1.1 only)
432 * 0xff: Unknown
433 * 4) Battery status
434 * 0x00: High
435 * 0x01: Low
436 * 0x02: Critical
437 * 0x03: Charging
438 * 0x04: Selected battery not present (BIOS >= 1.2 only)
439 * 0xff: Unknown
440 * 5) Battery flag
441 * bit 0: High
442 * bit 1: Low
443 * bit 2: Critical
444 * bit 3: Charging
445 * bit 7: No system battery
446 * 0xff: Unknown
447 * 6) Remaining battery life (percentage of charge):
448 * 0-100: valid
449 * -1: Unknown
450 * 7) Remaining battery life (time units):
451 * Number of remaining minutes or seconds
452 * -1: Unknown
453 * 8) min = minutes; sec = seconds
455 static int proc_apm_show(struct seq_file *m, void *v)
457 struct apm_power_info info;
458 char *units;
460 info.ac_line_status = 0xff;
461 info.battery_status = 0xff;
462 info.battery_flag = 0xff;
463 info.battery_life = -1;
464 info.time = -1;
465 info.units = -1;
467 if (apm_get_power_status)
468 apm_get_power_status(&info);
470 switch (info.units) {
471 default: units = "?"; break;
472 case 0: units = "min"; break;
473 case 1: units = "sec"; break;
476 seq_printf(m, "%s 1.2 0x%02x 0x%02x 0x%02x 0x%02x %d%% %d %s\n",
477 driver_version, APM_32_BIT_SUPPORT,
478 info.ac_line_status, info.battery_status,
479 info.battery_flag, info.battery_life,
480 info.time, units);
482 return 0;
485 static int proc_apm_open(struct inode *inode, struct file *file)
487 return single_open(file, proc_apm_show, NULL);
490 static const struct file_operations apm_proc_fops = {
491 .owner = THIS_MODULE,
492 .open = proc_apm_open,
493 .read = seq_read,
494 .llseek = seq_lseek,
495 .release = single_release,
497 #endif
499 static int kapmd(void *arg)
501 do {
502 apm_event_t event;
504 wait_event_interruptible(kapmd_wait,
505 !queue_empty(&kapmd_queue) || kthread_should_stop());
507 if (kthread_should_stop())
508 break;
510 spin_lock_irq(&kapmd_queue_lock);
511 event = 0;
512 if (!queue_empty(&kapmd_queue))
513 event = queue_get_event(&kapmd_queue);
514 spin_unlock_irq(&kapmd_queue_lock);
516 switch (event) {
517 case 0:
518 break;
520 case APM_LOW_BATTERY:
521 case APM_POWER_STATUS_CHANGE:
522 queue_event(event);
523 break;
525 case APM_USER_SUSPEND:
526 case APM_SYS_SUSPEND:
527 pm_suspend(PM_SUSPEND_MEM);
528 break;
530 case APM_CRITICAL_SUSPEND:
531 atomic_inc(&userspace_notification_inhibit);
532 pm_suspend(PM_SUSPEND_MEM);
533 atomic_dec(&userspace_notification_inhibit);
534 break;
536 } while (1);
538 return 0;
541 static int apm_suspend_notifier(struct notifier_block *nb,
542 unsigned long event,
543 void *dummy)
545 struct apm_user *as;
546 int err;
548 /* short-cut emergency suspends */
549 if (atomic_read(&userspace_notification_inhibit))
550 return NOTIFY_DONE;
552 switch (event) {
553 case PM_SUSPEND_PREPARE:
555 * Queue an event to all "writer" users that we want
556 * to suspend and need their ack.
558 mutex_lock(&state_lock);
559 down_read(&user_list_lock);
561 list_for_each_entry(as, &apm_user_list, list) {
562 if (as->suspend_state != SUSPEND_WAIT && as->reader &&
563 as->writer && as->suser) {
564 as->suspend_state = SUSPEND_PENDING;
565 atomic_inc(&suspend_acks_pending);
566 queue_add_event(&as->queue, APM_USER_SUSPEND);
570 up_read(&user_list_lock);
571 mutex_unlock(&state_lock);
572 wake_up_interruptible(&apm_waitqueue);
575 * Wait for the the suspend_acks_pending variable to drop to
576 * zero, meaning everybody acked the suspend event (or the
577 * process was killed.)
579 * If the app won't answer within a short while we assume it
580 * locked up and ignore it.
582 err = wait_event_interruptible_timeout(
583 apm_suspend_waitqueue,
584 atomic_read(&suspend_acks_pending) == 0,
585 5*HZ);
587 /* timed out */
588 if (err == 0) {
590 * Move anybody who timed out to "ack timeout" state.
592 * We could time out and the userspace does the ACK
593 * right after we time out but before we enter the
594 * locked section here, but that's fine.
596 mutex_lock(&state_lock);
597 down_read(&user_list_lock);
598 list_for_each_entry(as, &apm_user_list, list) {
599 if (as->suspend_state == SUSPEND_PENDING ||
600 as->suspend_state == SUSPEND_READ) {
601 as->suspend_state = SUSPEND_ACKTO;
602 atomic_dec(&suspend_acks_pending);
605 up_read(&user_list_lock);
606 mutex_unlock(&state_lock);
609 /* let suspend proceed */
610 if (err >= 0)
611 return NOTIFY_OK;
613 /* interrupted by signal */
614 return NOTIFY_BAD;
616 case PM_POST_SUSPEND:
618 * Anyone on the APM queues will think we're still suspended.
619 * Send a message so everyone knows we're now awake again.
621 queue_event(APM_NORMAL_RESUME);
624 * Finally, wake up anyone who is sleeping on the suspend.
626 mutex_lock(&state_lock);
627 down_read(&user_list_lock);
628 list_for_each_entry(as, &apm_user_list, list) {
629 if (as->suspend_state == SUSPEND_ACKED) {
631 * TODO: maybe grab error code, needs core
632 * changes to push the error to the notifier
633 * chain (could use the second parameter if
634 * implemented)
636 as->suspend_result = 0;
637 as->suspend_state = SUSPEND_DONE;
640 up_read(&user_list_lock);
641 mutex_unlock(&state_lock);
643 wake_up(&apm_suspend_waitqueue);
644 return NOTIFY_OK;
646 default:
647 return NOTIFY_DONE;
651 static struct notifier_block apm_notif_block = {
652 .notifier_call = apm_suspend_notifier,
655 static int __init apm_init(void)
657 int ret;
659 if (apm_disabled) {
660 printk(KERN_NOTICE "apm: disabled on user request.\n");
661 return -ENODEV;
664 kapmd_tsk = kthread_create(kapmd, NULL, "kapmd");
665 if (IS_ERR(kapmd_tsk)) {
666 ret = PTR_ERR(kapmd_tsk);
667 kapmd_tsk = NULL;
668 goto out;
670 wake_up_process(kapmd_tsk);
672 #ifdef CONFIG_PROC_FS
673 proc_create("apm", 0, NULL, &apm_proc_fops);
674 #endif
676 ret = misc_register(&apm_device);
677 if (ret)
678 goto out_stop;
680 ret = register_pm_notifier(&apm_notif_block);
681 if (ret)
682 goto out_unregister;
684 return 0;
686 out_unregister:
687 misc_deregister(&apm_device);
688 out_stop:
689 remove_proc_entry("apm", NULL);
690 kthread_stop(kapmd_tsk);
691 out:
692 return ret;
695 static void __exit apm_exit(void)
697 unregister_pm_notifier(&apm_notif_block);
698 misc_deregister(&apm_device);
699 remove_proc_entry("apm", NULL);
701 kthread_stop(kapmd_tsk);
704 module_init(apm_init);
705 module_exit(apm_exit);
707 MODULE_AUTHOR("Stephen Rothwell");
708 MODULE_DESCRIPTION("Advanced Power Management");
709 MODULE_LICENSE("GPL");
711 #ifndef MODULE
712 static int __init apm_setup(char *str)
714 while ((str != NULL) && (*str != '\0')) {
715 if (strncmp(str, "off", 3) == 0)
716 apm_disabled = 1;
717 if (strncmp(str, "on", 2) == 0)
718 apm_disabled = 0;
719 str = strchr(str, ',');
720 if (str != NULL)
721 str += strspn(str, ", \t");
723 return 1;
726 __setup("apm=", apm_setup);
727 #endif
730 * apm_queue_event - queue an APM event for kapmd
731 * @event: APM event
733 * Queue an APM event for kapmd to process and ultimately take the
734 * appropriate action. Only a subset of events are handled:
735 * %APM_LOW_BATTERY
736 * %APM_POWER_STATUS_CHANGE
737 * %APM_USER_SUSPEND
738 * %APM_SYS_SUSPEND
739 * %APM_CRITICAL_SUSPEND
741 void apm_queue_event(apm_event_t event)
743 unsigned long flags;
745 spin_lock_irqsave(&kapmd_queue_lock, flags);
746 queue_add_event(&kapmd_queue, event);
747 spin_unlock_irqrestore(&kapmd_queue_lock, flags);
749 wake_up_interruptible(&kapmd_wait);
751 EXPORT_SYMBOL(apm_queue_event);