llseek: automatically add .llseek fop
[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/hwdev/busbios/amp_12.htm]
12  */
13 #include <linux/module.h>
14 #include <linux/poll.h>
15 #include <linux/slab.h>
16 #include <linux/smp_lock.h>
17 #include <linux/proc_fs.h>
18 #include <linux/seq_file.h>
19 #include <linux/miscdevice.h>
20 #include <linux/apm_bios.h>
21 #include <linux/capability.h>
22 #include <linux/sched.h>
23 #include <linux/suspend.h>
24 #include <linux/apm-emulation.h>
25 #include <linux/freezer.h>
26 #include <linux/device.h>
27 #include <linux/kernel.h>
28 #include <linux/list.h>
29 #include <linux/init.h>
30 #include <linux/completion.h>
31 #include <linux/kthread.h>
32 #include <linux/delay.h>
33
34 #include <asm/system.h>
35
36 /*
37  * The apm_bios device is one of the misc char devices.
38  * This is its minor number.
39  */
40 #define APM_MINOR_DEV   134
41
42 /*
43  * See Documentation/Config.help for the configuration options.
44  *
45  * Various options can be changed at boot time as follows:
46  * (We allow underscores for compatibility with the modules code)
47  *      apm=on/off                      enable/disable APM
48  */
49
50 /*
51  * Maximum number of events stored
52  */
53 #define APM_MAX_EVENTS          16
54
55 struct 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  */
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,
108 };
109
110 /*
111  * The per-file APM data
112  */
113 struct 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  */
129 static atomic_t suspend_acks_pending = ATOMIC_INIT(0);
130 static atomic_t userspace_notification_inhibit = ATOMIC_INIT(0);
131 static int apm_disabled;
132 static struct task_struct *kapmd_tsk;
133
134 static DECLARE_WAIT_QUEUE_HEAD(apm_waitqueue);
135 static DECLARE_WAIT_QUEUE_HEAD(apm_suspend_waitqueue);
136
137 /*
138  * This is a list of everyone who has opened /dev/apm_bios
139  */
140 static DECLARE_RWSEM(user_list_lock);
141 static 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  */
148 static DECLARE_WAIT_QUEUE_HEAD(kapmd_wait);
149 static DEFINE_SPINLOCK(kapmd_queue_lock);
150 static struct apm_queue kapmd_queue;
151
152 static DEFINE_MUTEX(state_lock);
153
154 static 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  */
162 static 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  */
169 void (*apm_get_power_status)(struct apm_power_info *) = __apm_get_power_status;
170 EXPORT_SYMBOL(apm_get_power_status);
171
172
173 /*
174  * APM event queue management.
175  */
176 static inline int queue_empty(struct apm_queue *q)
177 {
178         return q->event_head == q->event_tail;
179 }
180
181 static 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
187 static 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
200 static 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
213 static 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
250 static 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  */
268 static long
269 apm_ioctl(struct file *filp, u_int cmd, u_long arg)
270 {
271         struct apm_user *as = filp->private_data;
272         int err = -EINVAL;
273
274         if (!as->suser || !as->writer)
275                 return -EPERM;
276
277         lock_kernel();
278         switch (cmd) {
279         case APM_IOC_SUSPEND:
280                 mutex_lock(&state_lock);
281
282                 as->suspend_result = -EINTR;
283
284                 switch (as->suspend_state) {
285                 case SUSPEND_READ:
286                         /*
287                          * If we read a suspend command from /dev/apm_bios,
288                          * then the corresponding APM_IOC_SUSPEND ioctl is
289                          * interpreted as an acknowledge.
290                          */
291                         as->suspend_state = SUSPEND_ACKED;
292                         atomic_dec(&suspend_acks_pending);
293                         mutex_unlock(&state_lock);
294
295                         /*
296                          * suspend_acks_pending changed, the notifier needs to
297                          * be woken up for this
298                          */
299                         wake_up(&apm_suspend_waitqueue);
300
301                         /*
302                          * Wait for the suspend/resume to complete.  If there
303                          * are pending acknowledges, we wait here for them.
304                          */
305                         freezer_do_not_count();
306
307                         wait_event(apm_suspend_waitqueue,
308                                    as->suspend_state == SUSPEND_DONE);
309
310                         /*
311                          * Since we are waiting until the suspend is done, the
312                          * try_to_freeze() in freezer_count() will not trigger
313                          */
314                         freezer_count();
315                         break;
316                 case SUSPEND_ACKTO:
317                         as->suspend_result = -ETIMEDOUT;
318                         mutex_unlock(&state_lock);
319                         break;
320                 default:
321                         as->suspend_state = SUSPEND_WAIT;
322                         mutex_unlock(&state_lock);
323
324                         /*
325                          * Otherwise it is a request to suspend the system.
326                          * Just invoke pm_suspend(), we'll handle it from
327                          * there via the notifier.
328                          */
329                         as->suspend_result = pm_suspend(PM_SUSPEND_MEM);
330                 }
331
332                 mutex_lock(&state_lock);
333                 err = as->suspend_result;
334                 as->suspend_state = SUSPEND_NONE;
335                 mutex_unlock(&state_lock);
336                 break;
337         }
338         unlock_kernel();
339
340         return err;
341 }
342
343 static int apm_release(struct inode * inode, struct file * filp)
344 {
345         struct apm_user *as = filp->private_data;
346
347         filp->private_data = NULL;
348
349         down_write(&user_list_lock);
350         list_del(&as->list);
351         up_write(&user_list_lock);
352
353         /*
354          * We are now unhooked from the chain.  As far as new
355          * events are concerned, we no longer exist.
356          */
357         mutex_lock(&state_lock);
358         if (as->suspend_state == SUSPEND_PENDING ||
359             as->suspend_state == SUSPEND_READ)
360                 atomic_dec(&suspend_acks_pending);
361         mutex_unlock(&state_lock);
362
363         wake_up(&apm_suspend_waitqueue);
364
365         kfree(as);
366         return 0;
367 }
368
369 static int apm_open(struct inode * inode, struct file * filp)
370 {
371         struct apm_user *as;
372
373         lock_kernel();
374         as = kzalloc(sizeof(*as), GFP_KERNEL);
375         if (as) {
376                 /*
377                  * XXX - this is a tiny bit broken, when we consider BSD
378                  * process accounting. If the device is opened by root, we
379                  * instantly flag that we used superuser privs. Who knows,
380                  * we might close the device immediately without doing a
381                  * privileged operation -- cevans
382                  */
383                 as->suser = capable(CAP_SYS_ADMIN);
384                 as->writer = (filp->f_mode & FMODE_WRITE) == FMODE_WRITE;
385                 as->reader = (filp->f_mode & FMODE_READ) == FMODE_READ;
386
387                 down_write(&user_list_lock);
388                 list_add(&as->list, &apm_user_list);
389                 up_write(&user_list_lock);
390
391                 filp->private_data = as;
392         }
393         unlock_kernel();
394
395         return as ? 0 : -ENOMEM;
396 }
397
398 static const struct file_operations apm_bios_fops = {
399         .owner          = THIS_MODULE,
400         .read           = apm_read,
401         .poll           = apm_poll,
402         .unlocked_ioctl = apm_ioctl,
403         .open           = apm_open,
404         .release        = apm_release,
405         .llseek         = noop_llseek,
406 };
407
408 static struct miscdevice apm_device = {
409         .minor          = APM_MINOR_DEV,
410         .name           = "apm_bios",
411         .fops           = &apm_bios_fops
412 };
413
414
415 #ifdef CONFIG_PROC_FS
416 /*
417  * Arguments, with symbols from linux/apm_bios.h.
418  *
419  *   0) Linux driver version (this will change if format changes)
420  *   1) APM BIOS Version.  Usually 1.0, 1.1 or 1.2.
421  *   2) APM flags from APM Installation Check (0x00):
422  *      bit 0: APM_16_BIT_SUPPORT
423  *      bit 1: APM_32_BIT_SUPPORT
424  *      bit 2: APM_IDLE_SLOWS_CLOCK
425  *      bit 3: APM_BIOS_DISABLED
426  *      bit 4: APM_BIOS_DISENGAGED
427  *   3) AC line status
428  *      0x00: Off-line
429  *      0x01: On-line
430  *      0x02: On backup power (BIOS >= 1.1 only)
431  *      0xff: Unknown
432  *   4) Battery status
433  *      0x00: High
434  *      0x01: Low
435  *      0x02: Critical
436  *      0x03: Charging
437  *      0x04: Selected battery not present (BIOS >= 1.2 only)
438  *      0xff: Unknown
439  *   5) Battery flag
440  *      bit 0: High
441  *      bit 1: Low
442  *      bit 2: Critical
443  *      bit 3: Charging
444  *      bit 7: No system battery
445  *      0xff: Unknown
446  *   6) Remaining battery life (percentage of charge):
447  *      0-100: valid
448  *      -1: Unknown
449  *   7) Remaining battery life (time units):
450  *      Number of remaining minutes or seconds
451  *      -1: Unknown
452  *   8) min = minutes; sec = seconds
453  */
454 static int proc_apm_show(struct seq_file *m, void *v)
455 {
456         struct apm_power_info info;
457         char *units;
458
459         info.ac_line_status = 0xff;
460         info.battery_status = 0xff;
461         info.battery_flag   = 0xff;
462         info.battery_life   = -1;
463         info.time           = -1;
464         info.units          = -1;
465
466         if (apm_get_power_status)
467                 apm_get_power_status(&info);
468
469         switch (info.units) {
470         default:        units = "?";    break;
471         case 0:         units = "min";  break;
472         case 1:         units = "sec";  break;
473         }
474
475         seq_printf(m, "%s 1.2 0x%02x 0x%02x 0x%02x 0x%02x %d%% %d %s\n",
476                      driver_version, APM_32_BIT_SUPPORT,
477                      info.ac_line_status, info.battery_status,
478                      info.battery_flag, info.battery_life,
479                      info.time, units);
480
481         return 0;
482 }
483
484 static int proc_apm_open(struct inode *inode, struct file *file)
485 {
486         return single_open(file, proc_apm_show, NULL);
487 }
488
489 static const struct file_operations apm_proc_fops = {
490         .owner          = THIS_MODULE,
491         .open           = proc_apm_open,
492         .read           = seq_read,
493         .llseek         = seq_lseek,
494         .release        = single_release,
495 };
496 #endif
497
498 static int kapmd(void *arg)
499 {
500         do {
501                 apm_event_t event;
502
503                 wait_event_interruptible(kapmd_wait,
504                                 !queue_empty(&kapmd_queue) || kthread_should_stop());
505
506                 if (kthread_should_stop())
507                         break;
508
509                 spin_lock_irq(&kapmd_queue_lock);
510                 event = 0;
511                 if (!queue_empty(&kapmd_queue))
512                         event = queue_get_event(&kapmd_queue);
513                 spin_unlock_irq(&kapmd_queue_lock);
514
515                 switch (event) {
516                 case 0:
517                         break;
518
519                 case APM_LOW_BATTERY:
520                 case APM_POWER_STATUS_CHANGE:
521                         queue_event(event);
522                         break;
523
524                 case APM_USER_SUSPEND:
525                 case APM_SYS_SUSPEND:
526                         pm_suspend(PM_SUSPEND_MEM);
527                         break;
528
529                 case APM_CRITICAL_SUSPEND:
530                         atomic_inc(&userspace_notification_inhibit);
531                         pm_suspend(PM_SUSPEND_MEM);
532                         atomic_dec(&userspace_notification_inhibit);
533                         break;
534                 }
535         } while (1);
536
537         return 0;
538 }
539
540 static int apm_suspend_notifier(struct notifier_block *nb,
541                                 unsigned long event,
542                                 void *dummy)
543 {
544         struct apm_user *as;
545         int err;
546
547         /* short-cut emergency suspends */
548         if (atomic_read(&userspace_notification_inhibit))
549                 return NOTIFY_DONE;
550
551         switch (event) {
552         case PM_SUSPEND_PREPARE:
553                 /*
554                  * Queue an event to all "writer" users that we want
555                  * to suspend and need their ack.
556                  */
557                 mutex_lock(&state_lock);
558                 down_read(&user_list_lock);
559
560                 list_for_each_entry(as, &apm_user_list, list) {
561                         if (as->suspend_state != SUSPEND_WAIT && as->reader &&
562                             as->writer && as->suser) {
563                                 as->suspend_state = SUSPEND_PENDING;
564                                 atomic_inc(&suspend_acks_pending);
565                                 queue_add_event(&as->queue, APM_USER_SUSPEND);
566                         }
567                 }
568
569                 up_read(&user_list_lock);
570                 mutex_unlock(&state_lock);
571                 wake_up_interruptible(&apm_waitqueue);
572
573                 /*
574                  * Wait for the the suspend_acks_pending variable to drop to
575                  * zero, meaning everybody acked the suspend event (or the
576                  * process was killed.)
577                  *
578                  * If the app won't answer within a short while we assume it
579                  * locked up and ignore it.
580                  */
581                 err = wait_event_interruptible_timeout(
582                         apm_suspend_waitqueue,
583                         atomic_read(&suspend_acks_pending) == 0,
584                         5*HZ);
585
586                 /* timed out */
587                 if (err == 0) {
588                         /*
589                          * Move anybody who timed out to "ack timeout" state.
590                          *
591                          * We could time out and the userspace does the ACK
592                          * right after we time out but before we enter the
593                          * locked section here, but that's fine.
594                          */
595                         mutex_lock(&state_lock);
596                         down_read(&user_list_lock);
597                         list_for_each_entry(as, &apm_user_list, list) {
598                                 if (as->suspend_state == SUSPEND_PENDING ||
599                                     as->suspend_state == SUSPEND_READ) {
600                                         as->suspend_state = SUSPEND_ACKTO;
601                                         atomic_dec(&suspend_acks_pending);
602                                 }
603                         }
604                         up_read(&user_list_lock);
605                         mutex_unlock(&state_lock);
606                 }
607
608                 /* let suspend proceed */
609                 if (err >= 0)
610                         return NOTIFY_OK;
611
612                 /* interrupted by signal */
613                 return NOTIFY_BAD;
614
615         case PM_POST_SUSPEND:
616                 /*
617                  * Anyone on the APM queues will think we're still suspended.
618                  * Send a message so everyone knows we're now awake again.
619                  */
620                 queue_event(APM_NORMAL_RESUME);
621
622                 /*
623                  * Finally, wake up anyone who is sleeping on the suspend.
624                  */
625                 mutex_lock(&state_lock);
626                 down_read(&user_list_lock);
627                 list_for_each_entry(as, &apm_user_list, list) {
628                         if (as->suspend_state == SUSPEND_ACKED) {
629                                 /*
630                                  * TODO: maybe grab error code, needs core
631                                  * changes to push the error to the notifier
632                                  * chain (could use the second parameter if
633                                  * implemented)
634                                  */
635                                 as->suspend_result = 0;
636                                 as->suspend_state = SUSPEND_DONE;
637                         }
638                 }
639                 up_read(&user_list_lock);
640                 mutex_unlock(&state_lock);
641
642                 wake_up(&apm_suspend_waitqueue);
643                 return NOTIFY_OK;
644
645         default:
646                 return NOTIFY_DONE;
647         }
648 }
649
650 static struct notifier_block apm_notif_block = {
651         .notifier_call = apm_suspend_notifier,
652 };
653
654 static int __init apm_init(void)
655 {
656         int ret;
657
658         if (apm_disabled) {
659                 printk(KERN_NOTICE "apm: disabled on user request.\n");
660                 return -ENODEV;
661         }
662
663         kapmd_tsk = kthread_create(kapmd, NULL, "kapmd");
664         if (IS_ERR(kapmd_tsk)) {
665                 ret = PTR_ERR(kapmd_tsk);
666                 kapmd_tsk = NULL;
667                 goto out;
668         }
669         wake_up_process(kapmd_tsk);
670
671 #ifdef CONFIG_PROC_FS
672         proc_create("apm", 0, NULL, &apm_proc_fops);
673 #endif
674
675         ret = misc_register(&apm_device);
676         if (ret)
677                 goto out_stop;
678
679         ret = register_pm_notifier(&apm_notif_block);
680         if (ret)
681                 goto out_unregister;
682
683         return 0;
684
685  out_unregister:
686         misc_deregister(&apm_device);
687  out_stop:
688         remove_proc_entry("apm", NULL);
689         kthread_stop(kapmd_tsk);
690  out:
691         return ret;
692 }
693
694 static void __exit apm_exit(void)
695 {
696         unregister_pm_notifier(&apm_notif_block);
697         misc_deregister(&apm_device);
698         remove_proc_entry("apm", NULL);
699
700         kthread_stop(kapmd_tsk);
701 }
702
703 module_init(apm_init);
704 module_exit(apm_exit);
705
706 MODULE_AUTHOR("Stephen Rothwell");
707 MODULE_DESCRIPTION("Advanced Power Management");
708 MODULE_LICENSE("GPL");
709
710 #ifndef MODULE
711 static int __init apm_setup(char *str)
712 {
713         while ((str != NULL) && (*str != '\0')) {
714                 if (strncmp(str, "off", 3) == 0)
715                         apm_disabled = 1;
716                 if (strncmp(str, "on", 2) == 0)
717                         apm_disabled = 0;
718                 str = strchr(str, ',');
719                 if (str != NULL)
720                         str += strspn(str, ", \t");
721         }
722         return 1;
723 }
724
725 __setup("apm=", apm_setup);
726 #endif
727
728 /**
729  * apm_queue_event - queue an APM event for kapmd
730  * @event: APM event
731  *
732  * Queue an APM event for kapmd to process and ultimately take the
733  * appropriate action.  Only a subset of events are handled:
734  *   %APM_LOW_BATTERY
735  *   %APM_POWER_STATUS_CHANGE
736  *   %APM_USER_SUSPEND
737  *   %APM_SYS_SUSPEND
738  *   %APM_CRITICAL_SUSPEND
739  */
740 void apm_queue_event(apm_event_t event)
741 {
742         unsigned long flags;
743
744         spin_lock_irqsave(&kapmd_queue_lock, flags);
745         queue_add_event(&kapmd_queue, event);
746         spin_unlock_irqrestore(&kapmd_queue_lock, flags);
747
748         wake_up_interruptible(&kapmd_wait);
749 }
750 EXPORT_SYMBOL(apm_queue_event);