drivers/char: comment fix: CMOS RTC update code is now in kernel/time/ntp.c
[linux-2.6.git] / drivers / char / apm-emulation.c
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  * One option can be changed at boot time as follows:
44  *      apm=on/off                      enable/disable APM
45  */
46
47 /*
48  * Maximum number of events stored
49  */
50 #define APM_MAX_EVENTS          16
51
52 struct apm_queue {
53         unsigned int            event_head;
54         unsigned int            event_tail;
55         apm_event_t             events[APM_MAX_EVENTS];
56 };
57
58 /*
59  * thread states (for threads using a writable /dev/apm_bios fd):
60  *
61  * SUSPEND_NONE:        nothing happening
62  * SUSPEND_PENDING:     suspend event queued for thread and pending to be read
63  * SUSPEND_READ:        suspend event read, pending acknowledgement
64  * SUSPEND_ACKED:       acknowledgement received from thread (via ioctl),
65  *                      waiting for resume
66  * SUSPEND_ACKTO:       acknowledgement timeout
67  * SUSPEND_DONE:        thread had acked suspend and is now notified of
68  *                      resume
69  *
70  * SUSPEND_WAIT:        this thread invoked suspend and is waiting for resume
71  *
72  * A thread migrates in one of three paths:
73  *      NONE -1-> PENDING -2-> READ -3-> ACKED -4-> DONE -5-> NONE
74  *                                  -6-> ACKTO -7-> NONE
75  *      NONE -8-> WAIT -9-> NONE
76  *
77  * While in PENDING or READ, the thread is accounted for in the
78  * suspend_acks_pending counter.
79  *
80  * The transitions are invoked as follows:
81  *      1: suspend event is signalled from the core PM code
82  *      2: the suspend event is read from the fd by the userspace thread
83  *      3: userspace thread issues the APM_IOC_SUSPEND ioctl (as ack)
84  *      4: core PM code signals that we have resumed
85  *      5: APM_IOC_SUSPEND ioctl returns
86  *
87  *      6: the notifier invoked from the core PM code timed out waiting
88  *         for all relevant threds to enter ACKED state and puts those
89  *         that haven't into ACKTO
90  *      7: those threads issue APM_IOC_SUSPEND ioctl too late,
91  *         get an error
92  *
93  *      8: userspace thread issues the APM_IOC_SUSPEND ioctl (to suspend),
94  *         ioctl code invokes pm_suspend()
95  *      9: pm_suspend() returns indicating resume
96  */
97 enum apm_suspend_state {
98         SUSPEND_NONE,
99         SUSPEND_PENDING,
100         SUSPEND_READ,
101         SUSPEND_ACKED,
102         SUSPEND_ACKTO,
103         SUSPEND_WAIT,
104         SUSPEND_DONE,
105 };
106
107 /*
108  * The per-file APM data
109  */
110 struct apm_user {
111         struct list_head        list;
112
113         unsigned int            suser: 1;
114         unsigned int            writer: 1;
115         unsigned int            reader: 1;
116
117         int                     suspend_result;
118         enum apm_suspend_state  suspend_state;
119
120         struct apm_queue        queue;
121 };
122
123 /*
124  * Local variables
125  */
126 static atomic_t suspend_acks_pending = ATOMIC_INIT(0);
127 static atomic_t userspace_notification_inhibit = ATOMIC_INIT(0);
128 static int apm_disabled;
129 static struct task_struct *kapmd_tsk;
130
131 static DECLARE_WAIT_QUEUE_HEAD(apm_waitqueue);
132 static DECLARE_WAIT_QUEUE_HEAD(apm_suspend_waitqueue);
133
134 /*
135  * This is a list of everyone who has opened /dev/apm_bios
136  */
137 static DECLARE_RWSEM(user_list_lock);
138 static LIST_HEAD(apm_user_list);
139
140 /*
141  * kapmd info.  kapmd provides us a process context to handle
142  * "APM" events within - specifically necessary if we're going
143  * to be suspending the system.
144  */
145 static DECLARE_WAIT_QUEUE_HEAD(kapmd_wait);
146 static DEFINE_SPINLOCK(kapmd_queue_lock);
147 static struct apm_queue kapmd_queue;
148
149 static DEFINE_MUTEX(state_lock);
150
151 static const char driver_version[] = "1.13";    /* no spaces */
152
153
154
155 /*
156  * Compatibility cruft until the IPAQ people move over to the new
157  * interface.
158  */
159 static void __apm_get_power_status(struct apm_power_info *info)
160 {
161 }
162
163 /*
164  * This allows machines to provide their own "apm get power status" function.
165  */
166 void (*apm_get_power_status)(struct apm_power_info *) = __apm_get_power_status;
167 EXPORT_SYMBOL(apm_get_power_status);
168
169
170 /*
171  * APM event queue management.
172  */
173 static inline int queue_empty(struct apm_queue *q)
174 {
175         return q->event_head == q->event_tail;
176 }
177
178 static inline apm_event_t queue_get_event(struct apm_queue *q)
179 {
180         q->event_tail = (q->event_tail + 1) % APM_MAX_EVENTS;
181         return q->events[q->event_tail];
182 }
183
184 static void queue_add_event(struct apm_queue *q, apm_event_t event)
185 {
186         q->event_head = (q->event_head + 1) % APM_MAX_EVENTS;
187         if (q->event_head == q->event_tail) {
188                 static int notified;
189
190                 if (notified++ == 0)
191                     printk(KERN_ERR "apm: an event queue overflowed\n");
192                 q->event_tail = (q->event_tail + 1) % APM_MAX_EVENTS;
193         }
194         q->events[q->event_head] = event;
195 }
196
197 static void queue_event(apm_event_t event)
198 {
199         struct apm_user *as;
200
201         down_read(&user_list_lock);
202         list_for_each_entry(as, &apm_user_list, list) {
203                 if (as->reader)
204                         queue_add_event(&as->queue, event);
205         }
206         up_read(&user_list_lock);
207         wake_up_interruptible(&apm_waitqueue);
208 }
209
210 static ssize_t apm_read(struct file *fp, char __user *buf, size_t count, loff_t *ppos)
211 {
212         struct apm_user *as = fp->private_data;
213         apm_event_t event;
214         int i = count, ret = 0;
215
216         if (count < sizeof(apm_event_t))
217                 return -EINVAL;
218
219         if (queue_empty(&as->queue) && fp->f_flags & O_NONBLOCK)
220                 return -EAGAIN;
221
222         wait_event_interruptible(apm_waitqueue, !queue_empty(&as->queue));
223
224         while ((i >= sizeof(event)) && !queue_empty(&as->queue)) {
225                 event = queue_get_event(&as->queue);
226
227                 ret = -EFAULT;
228                 if (copy_to_user(buf, &event, sizeof(event)))
229                         break;
230
231                 mutex_lock(&state_lock);
232                 if (as->suspend_state == SUSPEND_PENDING &&
233                     (event == APM_SYS_SUSPEND || event == APM_USER_SUSPEND))
234                         as->suspend_state = SUSPEND_READ;
235                 mutex_unlock(&state_lock);
236
237                 buf += sizeof(event);
238                 i -= sizeof(event);
239         }
240
241         if (i < count)
242                 ret = count - i;
243
244         return ret;
245 }
246
247 static unsigned int apm_poll(struct file *fp, poll_table * wait)
248 {
249         struct apm_user *as = fp->private_data;
250
251         poll_wait(fp, &apm_waitqueue, wait);
252         return queue_empty(&as->queue) ? 0 : POLLIN | POLLRDNORM;
253 }
254
255 /*
256  * apm_ioctl - handle APM ioctl
257  *
258  * APM_IOC_SUSPEND
259  *   This IOCTL is overloaded, and performs two functions.  It is used to:
260  *     - initiate a suspend
261  *     - acknowledge a suspend read from /dev/apm_bios.
262  *   Only when everyone who has opened /dev/apm_bios with write permission
263  *   has acknowledge does the actual suspend happen.
264  */
265 static long
266 apm_ioctl(struct file *filp, u_int cmd, u_long arg)
267 {
268         struct apm_user *as = filp->private_data;
269         int err = -EINVAL;
270
271         if (!as->suser || !as->writer)
272                 return -EPERM;
273
274         switch (cmd) {
275         case APM_IOC_SUSPEND:
276                 mutex_lock(&state_lock);
277
278                 as->suspend_result = -EINTR;
279
280                 switch (as->suspend_state) {
281                 case SUSPEND_READ:
282                         /*
283                          * If we read a suspend command from /dev/apm_bios,
284                          * then the corresponding APM_IOC_SUSPEND ioctl is
285                          * interpreted as an acknowledge.
286                          */
287                         as->suspend_state = SUSPEND_ACKED;
288                         atomic_dec(&suspend_acks_pending);
289                         mutex_unlock(&state_lock);
290
291                         /*
292                          * suspend_acks_pending changed, the notifier needs to
293                          * be woken up for this
294                          */
295                         wake_up(&apm_suspend_waitqueue);
296
297                         /*
298                          * Wait for the suspend/resume to complete.  If there
299                          * are pending acknowledges, we wait here for them.
300                          * wait_event_freezable() is interruptible and pending
301                          * signal can cause busy looping.  We aren't doing
302                          * anything critical, chill a bit on each iteration.
303                          */
304                         while (wait_event_freezable(apm_suspend_waitqueue,
305                                         as->suspend_state == SUSPEND_DONE))
306                                 msleep(10);
307                         break;
308                 case SUSPEND_ACKTO:
309                         as->suspend_result = -ETIMEDOUT;
310                         mutex_unlock(&state_lock);
311                         break;
312                 default:
313                         as->suspend_state = SUSPEND_WAIT;
314                         mutex_unlock(&state_lock);
315
316                         /*
317                          * Otherwise it is a request to suspend the system.
318                          * Just invoke pm_suspend(), we'll handle it from
319                          * there via the notifier.
320                          */
321                         as->suspend_result = pm_suspend(PM_SUSPEND_MEM);
322                 }
323
324                 mutex_lock(&state_lock);
325                 err = as->suspend_result;
326                 as->suspend_state = SUSPEND_NONE;
327                 mutex_unlock(&state_lock);
328                 break;
329         }
330
331         return err;
332 }
333
334 static int apm_release(struct inode * inode, struct file * filp)
335 {
336         struct apm_user *as = filp->private_data;
337
338         filp->private_data = NULL;
339
340         down_write(&user_list_lock);
341         list_del(&as->list);
342         up_write(&user_list_lock);
343
344         /*
345          * We are now unhooked from the chain.  As far as new
346          * events are concerned, we no longer exist.
347          */
348         mutex_lock(&state_lock);
349         if (as->suspend_state == SUSPEND_PENDING ||
350             as->suspend_state == SUSPEND_READ)
351                 atomic_dec(&suspend_acks_pending);
352         mutex_unlock(&state_lock);
353
354         wake_up(&apm_suspend_waitqueue);
355
356         kfree(as);
357         return 0;
358 }
359
360 static int apm_open(struct inode * inode, struct file * filp)
361 {
362         struct apm_user *as;
363
364         as = kzalloc(sizeof(*as), GFP_KERNEL);
365         if (as) {
366                 /*
367                  * XXX - this is a tiny bit broken, when we consider BSD
368                  * process accounting. If the device is opened by root, we
369                  * instantly flag that we used superuser privs. Who knows,
370                  * we might close the device immediately without doing a
371                  * privileged operation -- cevans
372                  */
373                 as->suser = capable(CAP_SYS_ADMIN);
374                 as->writer = (filp->f_mode & FMODE_WRITE) == FMODE_WRITE;
375                 as->reader = (filp->f_mode & FMODE_READ) == FMODE_READ;
376
377                 down_write(&user_list_lock);
378                 list_add(&as->list, &apm_user_list);
379                 up_write(&user_list_lock);
380
381                 filp->private_data = as;
382         }
383
384         return as ? 0 : -ENOMEM;
385 }
386
387 static const struct file_operations apm_bios_fops = {
388         .owner          = THIS_MODULE,
389         .read           = apm_read,
390         .poll           = apm_poll,
391         .unlocked_ioctl = apm_ioctl,
392         .open           = apm_open,
393         .release        = apm_release,
394         .llseek         = noop_llseek,
395 };
396
397 static struct miscdevice apm_device = {
398         .minor          = APM_MINOR_DEV,
399         .name           = "apm_bios",
400         .fops           = &apm_bios_fops
401 };
402
403
404 #ifdef CONFIG_PROC_FS
405 /*
406  * Arguments, with symbols from linux/apm_bios.h.
407  *
408  *   0) Linux driver version (this will change if format changes)
409  *   1) APM BIOS Version.  Usually 1.0, 1.1 or 1.2.
410  *   2) APM flags from APM Installation Check (0x00):
411  *      bit 0: APM_16_BIT_SUPPORT
412  *      bit 1: APM_32_BIT_SUPPORT
413  *      bit 2: APM_IDLE_SLOWS_CLOCK
414  *      bit 3: APM_BIOS_DISABLED
415  *      bit 4: APM_BIOS_DISENGAGED
416  *   3) AC line status
417  *      0x00: Off-line
418  *      0x01: On-line
419  *      0x02: On backup power (BIOS >= 1.1 only)
420  *      0xff: Unknown
421  *   4) Battery status
422  *      0x00: High
423  *      0x01: Low
424  *      0x02: Critical
425  *      0x03: Charging
426  *      0x04: Selected battery not present (BIOS >= 1.2 only)
427  *      0xff: Unknown
428  *   5) Battery flag
429  *      bit 0: High
430  *      bit 1: Low
431  *      bit 2: Critical
432  *      bit 3: Charging
433  *      bit 7: No system battery
434  *      0xff: Unknown
435  *   6) Remaining battery life (percentage of charge):
436  *      0-100: valid
437  *      -1: Unknown
438  *   7) Remaining battery life (time units):
439  *      Number of remaining minutes or seconds
440  *      -1: Unknown
441  *   8) min = minutes; sec = seconds
442  */
443 static int proc_apm_show(struct seq_file *m, void *v)
444 {
445         struct apm_power_info info;
446         char *units;
447
448         info.ac_line_status = 0xff;
449         info.battery_status = 0xff;
450         info.battery_flag   = 0xff;
451         info.battery_life   = -1;
452         info.time           = -1;
453         info.units          = -1;
454
455         if (apm_get_power_status)
456                 apm_get_power_status(&info);
457
458         switch (info.units) {
459         default:        units = "?";    break;
460         case 0:         units = "min";  break;
461         case 1:         units = "sec";  break;
462         }
463
464         seq_printf(m, "%s 1.2 0x%02x 0x%02x 0x%02x 0x%02x %d%% %d %s\n",
465                      driver_version, APM_32_BIT_SUPPORT,
466                      info.ac_line_status, info.battery_status,
467                      info.battery_flag, info.battery_life,
468                      info.time, units);
469
470         return 0;
471 }
472
473 static int proc_apm_open(struct inode *inode, struct file *file)
474 {
475         return single_open(file, proc_apm_show, NULL);
476 }
477
478 static const struct file_operations apm_proc_fops = {
479         .owner          = THIS_MODULE,
480         .open           = proc_apm_open,
481         .read           = seq_read,
482         .llseek         = seq_lseek,
483         .release        = single_release,
484 };
485 #endif
486
487 static int kapmd(void *arg)
488 {
489         do {
490                 apm_event_t event;
491
492                 wait_event_interruptible(kapmd_wait,
493                                 !queue_empty(&kapmd_queue) || kthread_should_stop());
494
495                 if (kthread_should_stop())
496                         break;
497
498                 spin_lock_irq(&kapmd_queue_lock);
499                 event = 0;
500                 if (!queue_empty(&kapmd_queue))
501                         event = queue_get_event(&kapmd_queue);
502                 spin_unlock_irq(&kapmd_queue_lock);
503
504                 switch (event) {
505                 case 0:
506                         break;
507
508                 case APM_LOW_BATTERY:
509                 case APM_POWER_STATUS_CHANGE:
510                         queue_event(event);
511                         break;
512
513                 case APM_USER_SUSPEND:
514                 case APM_SYS_SUSPEND:
515                         pm_suspend(PM_SUSPEND_MEM);
516                         break;
517
518                 case APM_CRITICAL_SUSPEND:
519                         atomic_inc(&userspace_notification_inhibit);
520                         pm_suspend(PM_SUSPEND_MEM);
521                         atomic_dec(&userspace_notification_inhibit);
522                         break;
523                 }
524         } while (1);
525
526         return 0;
527 }
528
529 static int apm_suspend_notifier(struct notifier_block *nb,
530                                 unsigned long event,
531                                 void *dummy)
532 {
533         struct apm_user *as;
534         int err;
535
536         /* short-cut emergency suspends */
537         if (atomic_read(&userspace_notification_inhibit))
538                 return NOTIFY_DONE;
539
540         switch (event) {
541         case PM_SUSPEND_PREPARE:
542                 /*
543                  * Queue an event to all "writer" users that we want
544                  * to suspend and need their ack.
545                  */
546                 mutex_lock(&state_lock);
547                 down_read(&user_list_lock);
548
549                 list_for_each_entry(as, &apm_user_list, list) {
550                         if (as->suspend_state != SUSPEND_WAIT && as->reader &&
551                             as->writer && as->suser) {
552                                 as->suspend_state = SUSPEND_PENDING;
553                                 atomic_inc(&suspend_acks_pending);
554                                 queue_add_event(&as->queue, APM_USER_SUSPEND);
555                         }
556                 }
557
558                 up_read(&user_list_lock);
559                 mutex_unlock(&state_lock);
560                 wake_up_interruptible(&apm_waitqueue);
561
562                 /*
563                  * Wait for the the suspend_acks_pending variable to drop to
564                  * zero, meaning everybody acked the suspend event (or the
565                  * process was killed.)
566                  *
567                  * If the app won't answer within a short while we assume it
568                  * locked up and ignore it.
569                  */
570                 err = wait_event_interruptible_timeout(
571                         apm_suspend_waitqueue,
572                         atomic_read(&suspend_acks_pending) == 0,
573                         5*HZ);
574
575                 /* timed out */
576                 if (err == 0) {
577                         /*
578                          * Move anybody who timed out to "ack timeout" state.
579                          *
580                          * We could time out and the userspace does the ACK
581                          * right after we time out but before we enter the
582                          * locked section here, but that's fine.
583                          */
584                         mutex_lock(&state_lock);
585                         down_read(&user_list_lock);
586                         list_for_each_entry(as, &apm_user_list, list) {
587                                 if (as->suspend_state == SUSPEND_PENDING ||
588                                     as->suspend_state == SUSPEND_READ) {
589                                         as->suspend_state = SUSPEND_ACKTO;
590                                         atomic_dec(&suspend_acks_pending);
591                                 }
592                         }
593                         up_read(&user_list_lock);
594                         mutex_unlock(&state_lock);
595                 }
596
597                 /* let suspend proceed */
598                 if (err >= 0)
599                         return NOTIFY_OK;
600
601                 /* interrupted by signal */
602                 return notifier_from_errno(err);
603
604         case PM_POST_SUSPEND:
605                 /*
606                  * Anyone on the APM queues will think we're still suspended.
607                  * Send a message so everyone knows we're now awake again.
608                  */
609                 queue_event(APM_NORMAL_RESUME);
610
611                 /*
612                  * Finally, wake up anyone who is sleeping on the suspend.
613                  */
614                 mutex_lock(&state_lock);
615                 down_read(&user_list_lock);
616                 list_for_each_entry(as, &apm_user_list, list) {
617                         if (as->suspend_state == SUSPEND_ACKED) {
618                                 /*
619                                  * TODO: maybe grab error code, needs core
620                                  * changes to push the error to the notifier
621                                  * chain (could use the second parameter if
622                                  * implemented)
623                                  */
624                                 as->suspend_result = 0;
625                                 as->suspend_state = SUSPEND_DONE;
626                         }
627                 }
628                 up_read(&user_list_lock);
629                 mutex_unlock(&state_lock);
630
631                 wake_up(&apm_suspend_waitqueue);
632                 return NOTIFY_OK;
633
634         default:
635                 return NOTIFY_DONE;
636         }
637 }
638
639 static struct notifier_block apm_notif_block = {
640         .notifier_call = apm_suspend_notifier,
641 };
642
643 static int __init apm_init(void)
644 {
645         int ret;
646
647         if (apm_disabled) {
648                 printk(KERN_NOTICE "apm: disabled on user request.\n");
649                 return -ENODEV;
650         }
651
652         kapmd_tsk = kthread_create(kapmd, NULL, "kapmd");
653         if (IS_ERR(kapmd_tsk)) {
654                 ret = PTR_ERR(kapmd_tsk);
655                 kapmd_tsk = NULL;
656                 goto out;
657         }
658         wake_up_process(kapmd_tsk);
659
660 #ifdef CONFIG_PROC_FS
661         proc_create("apm", 0, NULL, &apm_proc_fops);
662 #endif
663
664         ret = misc_register(&apm_device);
665         if (ret)
666                 goto out_stop;
667
668         ret = register_pm_notifier(&apm_notif_block);
669         if (ret)
670                 goto out_unregister;
671
672         return 0;
673
674  out_unregister:
675         misc_deregister(&apm_device);
676  out_stop:
677         remove_proc_entry("apm", NULL);
678         kthread_stop(kapmd_tsk);
679  out:
680         return ret;
681 }
682
683 static void __exit apm_exit(void)
684 {
685         unregister_pm_notifier(&apm_notif_block);
686         misc_deregister(&apm_device);
687         remove_proc_entry("apm", NULL);
688
689         kthread_stop(kapmd_tsk);
690 }
691
692 module_init(apm_init);
693 module_exit(apm_exit);
694
695 MODULE_AUTHOR("Stephen Rothwell");
696 MODULE_DESCRIPTION("Advanced Power Management");
697 MODULE_LICENSE("GPL");
698
699 #ifndef MODULE
700 static int __init apm_setup(char *str)
701 {
702         while ((str != NULL) && (*str != '\0')) {
703                 if (strncmp(str, "off", 3) == 0)
704                         apm_disabled = 1;
705                 if (strncmp(str, "on", 2) == 0)
706                         apm_disabled = 0;
707                 str = strchr(str, ',');
708                 if (str != NULL)
709                         str += strspn(str, ", \t");
710         }
711         return 1;
712 }
713
714 __setup("apm=", apm_setup);
715 #endif
716
717 /**
718  * apm_queue_event - queue an APM event for kapmd
719  * @event: APM event
720  *
721  * Queue an APM event for kapmd to process and ultimately take the
722  * appropriate action.  Only a subset of events are handled:
723  *   %APM_LOW_BATTERY
724  *   %APM_POWER_STATUS_CHANGE
725  *   %APM_USER_SUSPEND
726  *   %APM_SYS_SUSPEND
727  *   %APM_CRITICAL_SUSPEND
728  */
729 void apm_queue_event(apm_event_t event)
730 {
731         unsigned long flags;
732
733         spin_lock_irqsave(&kapmd_queue_lock, flags);
734         queue_add_event(&kapmd_queue, event);
735         spin_unlock_irqrestore(&kapmd_queue_lock, flags);
736
737         wake_up_interruptible(&kapmd_wait);
738 }
739 EXPORT_SYMBOL(apm_queue_event);