[PATCH] mark struct file_operations const 5
[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
17 static struct class *rtc_dev_class;
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         /* We keep the lock as long as the device is in use
30          * and return immediately if busy
31          */
32         if (!(mutex_trylock(&rtc->char_lock)))
33                 return -EBUSY;
34
35         file->private_data = &rtc->class_dev;
36
37         err = ops->open ? ops->open(rtc->class_dev.dev) : 0;
38         if (err == 0) {
39                 spin_lock_irq(&rtc->irq_lock);
40                 rtc->irq_data = 0;
41                 spin_unlock_irq(&rtc->irq_lock);
42
43                 return 0;
44         }
45
46         /* something has gone wrong, release the lock */
47         mutex_unlock(&rtc->char_lock);
48         return err;
49 }
50
51 #ifdef CONFIG_RTC_INTF_DEV_UIE_EMUL
52 /*
53  * Routine to poll RTC seconds field for change as often as possible,
54  * after first RTC_UIE use timer to reduce polling
55  */
56 static void rtc_uie_task(struct work_struct *work)
57 {
58         struct rtc_device *rtc =
59                 container_of(work, struct rtc_device, uie_task);
60         struct rtc_time tm;
61         int num = 0;
62         int err;
63
64         err = rtc_read_time(&rtc->class_dev, &tm);
65
66         local_irq_disable();
67         spin_lock(&rtc->irq_lock);
68         if (rtc->stop_uie_polling || err) {
69                 rtc->uie_task_active = 0;
70         } else if (rtc->oldsecs != tm.tm_sec) {
71                 num = (tm.tm_sec + 60 - rtc->oldsecs) % 60;
72                 rtc->oldsecs = tm.tm_sec;
73                 rtc->uie_timer.expires = jiffies + HZ - (HZ/10);
74                 rtc->uie_timer_active = 1;
75                 rtc->uie_task_active = 0;
76                 add_timer(&rtc->uie_timer);
77         } else if (schedule_work(&rtc->uie_task) == 0) {
78                 rtc->uie_task_active = 0;
79         }
80         spin_unlock(&rtc->irq_lock);
81         if (num)
82                 rtc_update_irq(&rtc->class_dev, num, RTC_UF | RTC_IRQF);
83         local_irq_enable();
84 }
85 static void rtc_uie_timer(unsigned long data)
86 {
87         struct rtc_device *rtc = (struct rtc_device *)data;
88         unsigned long flags;
89
90         spin_lock_irqsave(&rtc->irq_lock, flags);
91         rtc->uie_timer_active = 0;
92         rtc->uie_task_active = 1;
93         if ((schedule_work(&rtc->uie_task) == 0))
94                 rtc->uie_task_active = 0;
95         spin_unlock_irqrestore(&rtc->irq_lock, flags);
96 }
97
98 static void clear_uie(struct rtc_device *rtc)
99 {
100         spin_lock_irq(&rtc->irq_lock);
101         if (rtc->irq_active) {
102                 rtc->stop_uie_polling = 1;
103                 if (rtc->uie_timer_active) {
104                         spin_unlock_irq(&rtc->irq_lock);
105                         del_timer_sync(&rtc->uie_timer);
106                         spin_lock_irq(&rtc->irq_lock);
107                         rtc->uie_timer_active = 0;
108                 }
109                 if (rtc->uie_task_active) {
110                         spin_unlock_irq(&rtc->irq_lock);
111                         flush_scheduled_work();
112                         spin_lock_irq(&rtc->irq_lock);
113                 }
114                 rtc->irq_active = 0;
115         }
116         spin_unlock_irq(&rtc->irq_lock);
117 }
118
119 static int set_uie(struct rtc_device *rtc)
120 {
121         struct rtc_time tm;
122         int err;
123
124         err = rtc_read_time(&rtc->class_dev, &tm);
125         if (err)
126                 return err;
127         spin_lock_irq(&rtc->irq_lock);
128         if (!rtc->irq_active) {
129                 rtc->irq_active = 1;
130                 rtc->stop_uie_polling = 0;
131                 rtc->oldsecs = tm.tm_sec;
132                 rtc->uie_task_active = 1;
133                 if (schedule_work(&rtc->uie_task) == 0)
134                         rtc->uie_task_active = 0;
135         }
136         rtc->irq_data = 0;
137         spin_unlock_irq(&rtc->irq_lock);
138         return 0;
139 }
140 #endif /* CONFIG_RTC_INTF_DEV_UIE_EMUL */
141
142 static ssize_t
143 rtc_dev_read(struct file *file, char __user *buf, size_t count, loff_t *ppos)
144 {
145         struct rtc_device *rtc = to_rtc_device(file->private_data);
146
147         DECLARE_WAITQUEUE(wait, current);
148         unsigned long data;
149         ssize_t ret;
150
151         if (count != sizeof(unsigned int) && count < sizeof(unsigned long))
152                 return -EINVAL;
153
154         add_wait_queue(&rtc->irq_queue, &wait);
155         do {
156                 __set_current_state(TASK_INTERRUPTIBLE);
157
158                 spin_lock_irq(&rtc->irq_lock);
159                 data = rtc->irq_data;
160                 rtc->irq_data = 0;
161                 spin_unlock_irq(&rtc->irq_lock);
162
163                 if (data != 0) {
164                         ret = 0;
165                         break;
166                 }
167                 if (file->f_flags & O_NONBLOCK) {
168                         ret = -EAGAIN;
169                         break;
170                 }
171                 if (signal_pending(current)) {
172                         ret = -ERESTARTSYS;
173                         break;
174                 }
175                 schedule();
176         } while (1);
177         set_current_state(TASK_RUNNING);
178         remove_wait_queue(&rtc->irq_queue, &wait);
179
180         if (ret == 0) {
181                 /* Check for any data updates */
182                 if (rtc->ops->read_callback)
183                         data = rtc->ops->read_callback(rtc->class_dev.dev,
184                                                        data);
185
186                 if (sizeof(int) != sizeof(long) &&
187                     count == sizeof(unsigned int))
188                         ret = put_user(data, (unsigned int __user *)buf) ?:
189                                 sizeof(unsigned int);
190                 else
191                         ret = put_user(data, (unsigned long __user *)buf) ?:
192                                 sizeof(unsigned long);
193         }
194         return ret;
195 }
196
197 static unsigned int rtc_dev_poll(struct file *file, poll_table *wait)
198 {
199         struct rtc_device *rtc = to_rtc_device(file->private_data);
200         unsigned long data;
201
202         poll_wait(file, &rtc->irq_queue, wait);
203
204         data = rtc->irq_data;
205
206         return (data != 0) ? (POLLIN | POLLRDNORM) : 0;
207 }
208
209 static int rtc_dev_ioctl(struct inode *inode, struct file *file,
210                 unsigned int cmd, unsigned long arg)
211 {
212         int err = 0;
213         struct class_device *class_dev = file->private_data;
214         struct rtc_device *rtc = to_rtc_device(class_dev);
215         const struct rtc_class_ops *ops = rtc->ops;
216         struct rtc_time tm;
217         struct rtc_wkalrm alarm;
218         void __user *uarg = (void __user *) arg;
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                         return -EACCES;
229                 break;
230
231         case RTC_IRQP_SET:
232                 if (arg > rtc->max_user_freq && !capable(CAP_SYS_RESOURCE))
233                         return -EACCES;
234                 break;
235
236         case RTC_PIE_ON:
237                 if (!capable(CAP_SYS_RESOURCE))
238                         return -EACCES;
239                 break;
240         }
241
242         /* avoid conflicting IRQ users */
243         if (cmd == RTC_PIE_ON || cmd == RTC_PIE_OFF || cmd == RTC_IRQP_SET) {
244                 spin_lock_irq(&rtc->irq_task_lock);
245                 if (rtc->irq_task)
246                         err = -EBUSY;
247                 spin_unlock_irq(&rtc->irq_task_lock);
248
249                 if (err < 0)
250                         return err;
251         }
252
253         /* try the driver's ioctl interface */
254         if (ops->ioctl) {
255                 err = ops->ioctl(class_dev->dev, cmd, arg);
256                 if (err != -ENOIOCTLCMD)
257                         return err;
258         }
259
260         /* if the driver does not provide the ioctl interface
261          * or if that particular ioctl was not implemented
262          * (-ENOIOCTLCMD), we will try to emulate here.
263          */
264
265         switch (cmd) {
266         case RTC_ALM_READ:
267                 err = rtc_read_alarm(class_dev, &alarm);
268                 if (err < 0)
269                         return err;
270
271                 if (copy_to_user(uarg, &alarm.time, sizeof(tm)))
272                         return -EFAULT;
273                 break;
274
275         case RTC_ALM_SET:
276                 if (copy_from_user(&alarm.time, uarg, sizeof(tm)))
277                         return -EFAULT;
278
279                 alarm.enabled = 0;
280                 alarm.pending = 0;
281                 alarm.time.tm_mday = -1;
282                 alarm.time.tm_mon = -1;
283                 alarm.time.tm_year = -1;
284                 alarm.time.tm_wday = -1;
285                 alarm.time.tm_yday = -1;
286                 alarm.time.tm_isdst = -1;
287                 err = rtc_set_alarm(class_dev, &alarm);
288                 break;
289
290         case RTC_RD_TIME:
291                 err = rtc_read_time(class_dev, &tm);
292                 if (err < 0)
293                         return err;
294
295                 if (copy_to_user(uarg, &tm, sizeof(tm)))
296                         return -EFAULT;
297                 break;
298
299         case RTC_SET_TIME:
300                 if (copy_from_user(&tm, uarg, sizeof(tm)))
301                         return -EFAULT;
302
303                 err = rtc_set_time(class_dev, &tm);
304                 break;
305
306         case RTC_IRQP_READ:
307                 if (ops->irq_set_freq)
308                         err = put_user(rtc->irq_freq, (unsigned long __user *)uarg);
309                 break;
310
311         case RTC_IRQP_SET:
312                 if (ops->irq_set_freq)
313                         err = rtc_irq_set_freq(class_dev, rtc->irq_task, arg);
314                 break;
315
316 #if 0
317         case RTC_EPOCH_SET:
318 #ifndef rtc_epoch
319                 /*
320                  * There were no RTC clocks before 1900.
321                  */
322                 if (arg < 1900) {
323                         err = -EINVAL;
324                         break;
325                 }
326                 rtc_epoch = arg;
327                 err = 0;
328 #endif
329                 break;
330
331         case RTC_EPOCH_READ:
332                 err = put_user(rtc_epoch, (unsigned long __user *)uarg);
333                 break;
334 #endif
335         case RTC_WKALM_SET:
336                 if (copy_from_user(&alarm, uarg, sizeof(alarm)))
337                         return -EFAULT;
338
339                 err = rtc_set_alarm(class_dev, &alarm);
340                 break;
341
342         case RTC_WKALM_RD:
343                 err = rtc_read_alarm(class_dev, &alarm);
344                 if (err < 0)
345                         return err;
346
347                 if (copy_to_user(uarg, &alarm, sizeof(alarm)))
348                         return -EFAULT;
349                 break;
350
351 #ifdef CONFIG_RTC_INTF_DEV_UIE_EMUL
352         case RTC_UIE_OFF:
353                 clear_uie(rtc);
354                 return 0;
355
356         case RTC_UIE_ON:
357                 return set_uie(rtc);
358 #endif
359         default:
360                 err = -ENOTTY;
361                 break;
362         }
363
364         return err;
365 }
366
367 static int rtc_dev_release(struct inode *inode, struct file *file)
368 {
369         struct rtc_device *rtc = to_rtc_device(file->private_data);
370
371 #ifdef CONFIG_RTC_INTF_DEV_UIE_EMUL
372         clear_uie(rtc);
373 #endif
374         if (rtc->ops->release)
375                 rtc->ops->release(rtc->class_dev.dev);
376
377         mutex_unlock(&rtc->char_lock);
378         return 0;
379 }
380
381 static int rtc_dev_fasync(int fd, struct file *file, int on)
382 {
383         struct rtc_device *rtc = to_rtc_device(file->private_data);
384         return fasync_helper(fd, file, on, &rtc->async_queue);
385 }
386
387 static const struct file_operations rtc_dev_fops = {
388         .owner          = THIS_MODULE,
389         .llseek         = no_llseek,
390         .read           = rtc_dev_read,
391         .poll           = rtc_dev_poll,
392         .ioctl          = rtc_dev_ioctl,
393         .open           = rtc_dev_open,
394         .release        = rtc_dev_release,
395         .fasync         = rtc_dev_fasync,
396 };
397
398 /* insertion/removal hooks */
399
400 static int rtc_dev_add_device(struct class_device *class_dev,
401                                 struct class_interface *class_intf)
402 {
403         int err = 0;
404         struct rtc_device *rtc = to_rtc_device(class_dev);
405
406         if (rtc->id >= RTC_DEV_MAX) {
407                 dev_err(class_dev->dev, "too many RTCs\n");
408                 return -EINVAL;
409         }
410
411         mutex_init(&rtc->char_lock);
412         spin_lock_init(&rtc->irq_lock);
413         init_waitqueue_head(&rtc->irq_queue);
414 #ifdef CONFIG_RTC_INTF_DEV_UIE_EMUL
415         INIT_WORK(&rtc->uie_task, rtc_uie_task);
416         setup_timer(&rtc->uie_timer, rtc_uie_timer, (unsigned long)rtc);
417 #endif
418
419         cdev_init(&rtc->char_dev, &rtc_dev_fops);
420         rtc->char_dev.owner = rtc->owner;
421
422         if (cdev_add(&rtc->char_dev, MKDEV(MAJOR(rtc_devt), rtc->id), 1)) {
423                 dev_err(class_dev->dev,
424                         "failed to add char device %d:%d\n",
425                         MAJOR(rtc_devt), rtc->id);
426                 return -ENODEV;
427         }
428
429         rtc->rtc_dev = class_device_create(rtc_dev_class, NULL,
430                                                 MKDEV(MAJOR(rtc_devt), rtc->id),
431                                                 class_dev->dev, "rtc%d", rtc->id);
432         if (IS_ERR(rtc->rtc_dev)) {
433                 dev_err(class_dev->dev, "cannot create rtc_dev device\n");
434                 err = PTR_ERR(rtc->rtc_dev);
435                 goto err_cdev_del;
436         }
437
438         dev_dbg(class_dev->dev, "rtc intf: dev (%d:%d)\n",
439                 MAJOR(rtc->rtc_dev->devt),
440                 MINOR(rtc->rtc_dev->devt));
441
442         return 0;
443
444 err_cdev_del:
445
446         cdev_del(&rtc->char_dev);
447         return err;
448 }
449
450 static void rtc_dev_remove_device(struct class_device *class_dev,
451                                         struct class_interface *class_intf)
452 {
453         struct rtc_device *rtc = to_rtc_device(class_dev);
454
455         if (rtc->rtc_dev) {
456                 dev_dbg(class_dev->dev, "removing char %d:%d\n",
457                         MAJOR(rtc->rtc_dev->devt),
458                         MINOR(rtc->rtc_dev->devt));
459
460                 class_device_unregister(rtc->rtc_dev);
461                 cdev_del(&rtc->char_dev);
462         }
463 }
464
465 /* interface registration */
466
467 static struct class_interface rtc_dev_interface = {
468         .add = &rtc_dev_add_device,
469         .remove = &rtc_dev_remove_device,
470 };
471
472 static int __init rtc_dev_init(void)
473 {
474         int err;
475
476         rtc_dev_class = class_create(THIS_MODULE, "rtc-dev");
477         if (IS_ERR(rtc_dev_class))
478                 return PTR_ERR(rtc_dev_class);
479
480         err = alloc_chrdev_region(&rtc_devt, 0, RTC_DEV_MAX, "rtc");
481         if (err < 0) {
482                 printk(KERN_ERR "%s: failed to allocate char dev region\n",
483                         __FILE__);
484                 goto err_destroy_class;
485         }
486
487         err = rtc_interface_register(&rtc_dev_interface);
488         if (err < 0) {
489                 printk(KERN_ERR "%s: failed to register the interface\n",
490                         __FILE__);
491                 goto err_unregister_chrdev;
492         }
493
494         return 0;
495
496 err_unregister_chrdev:
497         unregister_chrdev_region(rtc_devt, RTC_DEV_MAX);
498
499 err_destroy_class:
500         class_destroy(rtc_dev_class);
501
502         return err;
503 }
504
505 static void __exit rtc_dev_exit(void)
506 {
507         class_interface_unregister(&rtc_dev_interface);
508         class_destroy(rtc_dev_class);
509         unregister_chrdev_region(rtc_devt, RTC_DEV_MAX);
510 }
511
512 subsys_initcall(rtc_dev_init);
513 module_exit(rtc_dev_exit);
514
515 MODULE_AUTHOR("Alessandro Zummo <a.zummo@towertech.it>");
516 MODULE_DESCRIPTION("RTC class dev interface");
517 MODULE_LICENSE("GPL");