rtc: fix kernel panic on second use of SIGIO nofitication
[linux-2.6.git] / drivers / rtc / rtc-dev.c
1 /*
2  * RTC subsystem, dev interface
3  *
4  * Copyright (C) 2005 Tower Technologies
5  * Author: Alessandro Zummo <a.zummo@towertech.it>
6  *
7  * based on arch/arm/common/rtctime.c
8  *
9  * This program is free software; you can redistribute it and/or modify
10  * it under the terms of the GNU General Public License version 2 as
11  * published by the Free Software Foundation.
12 */
13
14 #include <linux/module.h>
15 #include <linux/rtc.h>
16 #include "rtc-core.h"
17
18 static dev_t rtc_devt;
19
20 #define RTC_DEV_MAX 16 /* 16 RTCs should be enough for everyone... */
21
22 static int rtc_dev_open(struct inode *inode, struct file *file)
23 {
24         int err;
25         struct rtc_device *rtc = container_of(inode->i_cdev,
26                                         struct rtc_device, char_dev);
27         const struct rtc_class_ops *ops = rtc->ops;
28
29         if (test_and_set_bit_lock(RTC_DEV_BUSY, &rtc->flags))
30                 return -EBUSY;
31
32         file->private_data = rtc;
33
34         err = ops->open ? ops->open(rtc->dev.parent) : 0;
35         if (err == 0) {
36                 spin_lock_irq(&rtc->irq_lock);
37                 rtc->irq_data = 0;
38                 spin_unlock_irq(&rtc->irq_lock);
39
40                 return 0;
41         }
42
43         /* something has gone wrong */
44         clear_bit_unlock(RTC_DEV_BUSY, &rtc->flags);
45         return err;
46 }
47
48 #ifdef CONFIG_RTC_INTF_DEV_UIE_EMUL
49 /*
50  * Routine to poll RTC seconds field for change as often as possible,
51  * after first RTC_UIE use timer to reduce polling
52  */
53 static void rtc_uie_task(struct work_struct *work)
54 {
55         struct rtc_device *rtc =
56                 container_of(work, struct rtc_device, uie_task);
57         struct rtc_time tm;
58         int num = 0;
59         int err;
60
61         err = rtc_read_time(rtc, &tm);
62
63         local_irq_disable();
64         spin_lock(&rtc->irq_lock);
65         if (rtc->stop_uie_polling || err) {
66                 rtc->uie_task_active = 0;
67         } else if (rtc->oldsecs != tm.tm_sec) {
68                 num = (tm.tm_sec + 60 - rtc->oldsecs) % 60;
69                 rtc->oldsecs = tm.tm_sec;
70                 rtc->uie_timer.expires = jiffies + HZ - (HZ/10);
71                 rtc->uie_timer_active = 1;
72                 rtc->uie_task_active = 0;
73                 add_timer(&rtc->uie_timer);
74         } else if (schedule_work(&rtc->uie_task) == 0) {
75                 rtc->uie_task_active = 0;
76         }
77         spin_unlock(&rtc->irq_lock);
78         if (num)
79                 rtc_update_irq(rtc, num, RTC_UF | RTC_IRQF);
80         local_irq_enable();
81 }
82 static void rtc_uie_timer(unsigned long data)
83 {
84         struct rtc_device *rtc = (struct rtc_device *)data;
85         unsigned long flags;
86
87         spin_lock_irqsave(&rtc->irq_lock, flags);
88         rtc->uie_timer_active = 0;
89         rtc->uie_task_active = 1;
90         if ((schedule_work(&rtc->uie_task) == 0))
91                 rtc->uie_task_active = 0;
92         spin_unlock_irqrestore(&rtc->irq_lock, flags);
93 }
94
95 static void clear_uie(struct rtc_device *rtc)
96 {
97         spin_lock_irq(&rtc->irq_lock);
98         if (rtc->irq_active) {
99                 rtc->stop_uie_polling = 1;
100                 if (rtc->uie_timer_active) {
101                         spin_unlock_irq(&rtc->irq_lock);
102                         del_timer_sync(&rtc->uie_timer);
103                         spin_lock_irq(&rtc->irq_lock);
104                         rtc->uie_timer_active = 0;
105                 }
106                 if (rtc->uie_task_active) {
107                         spin_unlock_irq(&rtc->irq_lock);
108                         flush_scheduled_work();
109                         spin_lock_irq(&rtc->irq_lock);
110                 }
111                 rtc->irq_active = 0;
112         }
113         spin_unlock_irq(&rtc->irq_lock);
114 }
115
116 static int set_uie(struct rtc_device *rtc)
117 {
118         struct rtc_time tm;
119         int err;
120
121         err = rtc_read_time(rtc, &tm);
122         if (err)
123                 return err;
124         spin_lock_irq(&rtc->irq_lock);
125         if (!rtc->irq_active) {
126                 rtc->irq_active = 1;
127                 rtc->stop_uie_polling = 0;
128                 rtc->oldsecs = tm.tm_sec;
129                 rtc->uie_task_active = 1;
130                 if (schedule_work(&rtc->uie_task) == 0)
131                         rtc->uie_task_active = 0;
132         }
133         rtc->irq_data = 0;
134         spin_unlock_irq(&rtc->irq_lock);
135         return 0;
136 }
137 #endif /* CONFIG_RTC_INTF_DEV_UIE_EMUL */
138
139 static ssize_t
140 rtc_dev_read(struct file *file, char __user *buf, size_t count, loff_t *ppos)
141 {
142         struct rtc_device *rtc = file->private_data;
143
144         DECLARE_WAITQUEUE(wait, current);
145         unsigned long data;
146         ssize_t ret;
147
148         if (count != sizeof(unsigned int) && count < sizeof(unsigned long))
149                 return -EINVAL;
150
151         add_wait_queue(&rtc->irq_queue, &wait);
152         do {
153                 __set_current_state(TASK_INTERRUPTIBLE);
154
155                 spin_lock_irq(&rtc->irq_lock);
156                 data = rtc->irq_data;
157                 rtc->irq_data = 0;
158                 spin_unlock_irq(&rtc->irq_lock);
159
160                 if (data != 0) {
161                         ret = 0;
162                         break;
163                 }
164                 if (file->f_flags & O_NONBLOCK) {
165                         ret = -EAGAIN;
166                         break;
167                 }
168                 if (signal_pending(current)) {
169                         ret = -ERESTARTSYS;
170                         break;
171                 }
172                 schedule();
173         } while (1);
174         set_current_state(TASK_RUNNING);
175         remove_wait_queue(&rtc->irq_queue, &wait);
176
177         if (ret == 0) {
178                 /* Check for any data updates */
179                 if (rtc->ops->read_callback)
180                         data = rtc->ops->read_callback(rtc->dev.parent,
181                                                        data);
182
183                 if (sizeof(int) != sizeof(long) &&
184                     count == sizeof(unsigned int))
185                         ret = put_user(data, (unsigned int __user *)buf) ?:
186                                 sizeof(unsigned int);
187                 else
188                         ret = put_user(data, (unsigned long __user *)buf) ?:
189                                 sizeof(unsigned long);
190         }
191         return ret;
192 }
193
194 static unsigned int rtc_dev_poll(struct file *file, poll_table *wait)
195 {
196         struct rtc_device *rtc = file->private_data;
197         unsigned long data;
198
199         poll_wait(file, &rtc->irq_queue, wait);
200
201         data = rtc->irq_data;
202
203         return (data != 0) ? (POLLIN | POLLRDNORM) : 0;
204 }
205
206 static long rtc_dev_ioctl(struct file *file,
207                 unsigned int cmd, unsigned long arg)
208 {
209         int err = 0;
210         struct rtc_device *rtc = file->private_data;
211         const struct rtc_class_ops *ops = rtc->ops;
212         struct rtc_time tm;
213         struct rtc_wkalrm alarm;
214         void __user *uarg = (void __user *) arg;
215
216         err = mutex_lock_interruptible(&rtc->ops_lock);
217         if (err)
218                 return err;
219
220         /* check that the calling task has appropriate permissions
221          * for certain ioctls. doing this check here is useful
222          * to avoid duplicate code in each driver.
223          */
224         switch (cmd) {
225         case RTC_EPOCH_SET:
226         case RTC_SET_TIME:
227                 if (!capable(CAP_SYS_TIME))
228                         err = -EACCES;
229                 break;
230
231         case RTC_IRQP_SET:
232                 if (arg > rtc->max_user_freq && !capable(CAP_SYS_RESOURCE))
233                         err = -EACCES;
234                 break;
235
236         case RTC_PIE_ON:
237                 if (rtc->irq_freq > rtc->max_user_freq &&
238                                 !capable(CAP_SYS_RESOURCE))
239                         err = -EACCES;
240                 break;
241         }
242
243         if (err)
244                 goto done;
245
246         /* try the driver's ioctl interface */
247         if (ops->ioctl) {
248                 err = ops->ioctl(rtc->dev.parent, cmd, arg);
249                 if (err != -ENOIOCTLCMD) {
250                         mutex_unlock(&rtc->ops_lock);
251                         return err;
252                 }
253         }
254
255         /* if the driver does not provide the ioctl interface
256          * or if that particular ioctl was not implemented
257          * (-ENOIOCTLCMD), we will try to emulate here.
258          *
259          * Drivers *SHOULD NOT* provide ioctl implementations
260          * for these requests.  Instead, provide methods to
261          * support the following code, so that the RTC's main
262          * features are accessible without using ioctls.
263          *
264          * RTC and alarm times will be in UTC, by preference,
265          * but dual-booting with MS-Windows implies RTCs must
266          * use the local wall clock time.
267          */
268
269         switch (cmd) {
270         case RTC_ALM_READ:
271                 mutex_unlock(&rtc->ops_lock);
272
273                 err = rtc_read_alarm(rtc, &alarm);
274                 if (err < 0)
275                         return err;
276
277                 if (copy_to_user(uarg, &alarm.time, sizeof(tm)))
278                         err = -EFAULT;
279                 return err;
280
281         case RTC_ALM_SET:
282                 mutex_unlock(&rtc->ops_lock);
283
284                 if (copy_from_user(&alarm.time, uarg, sizeof(tm)))
285                         return -EFAULT;
286
287                 alarm.enabled = 0;
288                 alarm.pending = 0;
289                 alarm.time.tm_wday = -1;
290                 alarm.time.tm_yday = -1;
291                 alarm.time.tm_isdst = -1;
292
293                 /* RTC_ALM_SET alarms may be up to 24 hours in the future.
294                  * Rather than expecting every RTC to implement "don't care"
295                  * for day/month/year fields, just force the alarm to have
296                  * the right values for those fields.
297                  *
298                  * RTC_WKALM_SET should be used instead.  Not only does it
299                  * eliminate the need for a separate RTC_AIE_ON call, it
300                  * doesn't have the "alarm 23:59:59 in the future" race.
301                  *
302                  * NOTE:  some legacy code may have used invalid fields as
303                  * wildcards, exposing hardware "periodic alarm" capabilities.
304                  * Not supported here.
305                  */
306                 {
307                         unsigned long now, then;
308
309                         err = rtc_read_time(rtc, &tm);
310                         if (err < 0)
311                                 return err;
312                         rtc_tm_to_time(&tm, &now);
313
314                         alarm.time.tm_mday = tm.tm_mday;
315                         alarm.time.tm_mon = tm.tm_mon;
316                         alarm.time.tm_year = tm.tm_year;
317                         err  = rtc_valid_tm(&alarm.time);
318                         if (err < 0)
319                                 return err;
320                         rtc_tm_to_time(&alarm.time, &then);
321
322                         /* alarm may need to wrap into tomorrow */
323                         if (then < now) {
324                                 rtc_time_to_tm(now + 24 * 60 * 60, &tm);
325                                 alarm.time.tm_mday = tm.tm_mday;
326                                 alarm.time.tm_mon = tm.tm_mon;
327                                 alarm.time.tm_year = tm.tm_year;
328                         }
329                 }
330
331                 return rtc_set_alarm(rtc, &alarm);
332
333         case RTC_RD_TIME:
334                 mutex_unlock(&rtc->ops_lock);
335
336                 err = rtc_read_time(rtc, &tm);
337                 if (err < 0)
338                         return err;
339
340                 if (copy_to_user(uarg, &tm, sizeof(tm)))
341                         err = -EFAULT;
342                 return err;
343
344         case RTC_SET_TIME:
345                 mutex_unlock(&rtc->ops_lock);
346
347                 if (copy_from_user(&tm, uarg, sizeof(tm)))
348                         return -EFAULT;
349
350                 return rtc_set_time(rtc, &tm);
351
352         case RTC_PIE_ON:
353                 err = rtc_irq_set_state(rtc, NULL, 1);
354                 break;
355
356         case RTC_PIE_OFF:
357                 err = rtc_irq_set_state(rtc, NULL, 0);
358                 break;
359
360         case RTC_IRQP_SET:
361                 err = rtc_irq_set_freq(rtc, NULL, arg);
362                 break;
363
364         case RTC_IRQP_READ:
365                 err = put_user(rtc->irq_freq, (unsigned long __user *)uarg);
366                 break;
367
368 #if 0
369         case RTC_EPOCH_SET:
370 #ifndef rtc_epoch
371                 /*
372                  * There were no RTC clocks before 1900.
373                  */
374                 if (arg < 1900) {
375                         err = -EINVAL;
376                         break;
377                 }
378                 rtc_epoch = arg;
379                 err = 0;
380 #endif
381                 break;
382
383         case RTC_EPOCH_READ:
384                 err = put_user(rtc_epoch, (unsigned long __user *)uarg);
385                 break;
386 #endif
387         case RTC_WKALM_SET:
388                 mutex_unlock(&rtc->ops_lock);
389                 if (copy_from_user(&alarm, uarg, sizeof(alarm)))
390                         return -EFAULT;
391
392                 return rtc_set_alarm(rtc, &alarm);
393
394         case RTC_WKALM_RD:
395                 mutex_unlock(&rtc->ops_lock);
396                 err = rtc_read_alarm(rtc, &alarm);
397                 if (err < 0)
398                         return err;
399
400                 if (copy_to_user(uarg, &alarm, sizeof(alarm)))
401                         err = -EFAULT;
402                 return err;
403
404 #ifdef CONFIG_RTC_INTF_DEV_UIE_EMUL
405         case RTC_UIE_OFF:
406                 mutex_unlock(&rtc->ops_lock);
407                 clear_uie(rtc);
408                 return 0;
409
410         case RTC_UIE_ON:
411                 mutex_unlock(&rtc->ops_lock);
412                 err = set_uie(rtc);
413                 return err;
414 #endif
415         default:
416                 err = -ENOTTY;
417                 break;
418         }
419
420 done:
421         mutex_unlock(&rtc->ops_lock);
422         return err;
423 }
424
425 static int rtc_dev_fasync(int fd, struct file *file, int on)
426 {
427         struct rtc_device *rtc = file->private_data;
428         return fasync_helper(fd, file, on, &rtc->async_queue);
429 }
430
431 static int rtc_dev_release(struct inode *inode, struct file *file)
432 {
433         struct rtc_device *rtc = file->private_data;
434
435 #ifdef CONFIG_RTC_INTF_DEV_UIE_EMUL
436         clear_uie(rtc);
437 #endif
438         rtc_irq_set_state(rtc, NULL, 0);
439
440         if (rtc->ops->release)
441                 rtc->ops->release(rtc->dev.parent);
442
443         if (file->f_flags & FASYNC)
444                 rtc_dev_fasync(-1, file, 0);
445
446         clear_bit_unlock(RTC_DEV_BUSY, &rtc->flags);
447         return 0;
448 }
449
450 static const struct file_operations rtc_dev_fops = {
451         .owner          = THIS_MODULE,
452         .llseek         = no_llseek,
453         .read           = rtc_dev_read,
454         .poll           = rtc_dev_poll,
455         .unlocked_ioctl = rtc_dev_ioctl,
456         .open           = rtc_dev_open,
457         .release        = rtc_dev_release,
458         .fasync         = rtc_dev_fasync,
459 };
460
461 /* insertion/removal hooks */
462
463 void rtc_dev_prepare(struct rtc_device *rtc)
464 {
465         if (!rtc_devt)
466                 return;
467
468         if (rtc->id >= RTC_DEV_MAX) {
469                 pr_debug("%s: too many RTC devices\n", rtc->name);
470                 return;
471         }
472
473         rtc->dev.devt = MKDEV(MAJOR(rtc_devt), rtc->id);
474
475 #ifdef CONFIG_RTC_INTF_DEV_UIE_EMUL
476         INIT_WORK(&rtc->uie_task, rtc_uie_task);
477         setup_timer(&rtc->uie_timer, rtc_uie_timer, (unsigned long)rtc);
478 #endif
479
480         cdev_init(&rtc->char_dev, &rtc_dev_fops);
481         rtc->char_dev.owner = rtc->owner;
482 }
483
484 void rtc_dev_add_device(struct rtc_device *rtc)
485 {
486         if (cdev_add(&rtc->char_dev, rtc->dev.devt, 1))
487                 printk(KERN_WARNING "%s: failed to add char device %d:%d\n",
488                         rtc->name, MAJOR(rtc_devt), rtc->id);
489         else
490                 pr_debug("%s: dev (%d:%d)\n", rtc->name,
491                         MAJOR(rtc_devt), rtc->id);
492 }
493
494 void rtc_dev_del_device(struct rtc_device *rtc)
495 {
496         if (rtc->dev.devt)
497                 cdev_del(&rtc->char_dev);
498 }
499
500 void __init rtc_dev_init(void)
501 {
502         int err;
503
504         err = alloc_chrdev_region(&rtc_devt, 0, RTC_DEV_MAX, "rtc");
505         if (err < 0)
506                 printk(KERN_ERR "%s: failed to allocate char dev region\n",
507                         __FILE__);
508 }
509
510 void __exit rtc_dev_exit(void)
511 {
512         if (rtc_devt)
513                 unregister_chrdev_region(rtc_devt, RTC_DEV_MAX);
514 }