rtc: make rtc-ds1553 driver hotplug-aware
[linux-3.10.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         /* 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;
36
37         err = ops->open ? ops->open(rtc->dev.parent) : 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, &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, 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, &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 = 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->dev.parent,
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 = 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 rtc_device *rtc = file->private_data;
214         const struct rtc_class_ops *ops = rtc->ops;
215         struct rtc_time tm;
216         struct rtc_wkalrm alarm;
217         void __user *uarg = (void __user *) arg;
218
219         /* check that the calling task has appropriate permissions
220          * for certain ioctls. doing this check here is useful
221          * to avoid duplicate code in each driver.
222          */
223         switch (cmd) {
224         case RTC_EPOCH_SET:
225         case RTC_SET_TIME:
226                 if (!capable(CAP_SYS_TIME))
227                         return -EACCES;
228                 break;
229
230         case RTC_IRQP_SET:
231                 if (arg > rtc->max_user_freq && !capable(CAP_SYS_RESOURCE))
232                         return -EACCES;
233                 break;
234
235         case RTC_PIE_ON:
236                 if (!capable(CAP_SYS_RESOURCE))
237                         return -EACCES;
238                 break;
239         }
240
241         /* try the driver's ioctl interface */
242         if (ops->ioctl) {
243                 err = ops->ioctl(rtc->dev.parent, cmd, arg);
244                 if (err != -ENOIOCTLCMD)
245                         return err;
246         }
247
248         /* if the driver does not provide the ioctl interface
249          * or if that particular ioctl was not implemented
250          * (-ENOIOCTLCMD), we will try to emulate here.
251          */
252
253         switch (cmd) {
254         case RTC_ALM_READ:
255                 err = rtc_read_alarm(rtc, &alarm);
256                 if (err < 0)
257                         return err;
258
259                 if (copy_to_user(uarg, &alarm.time, sizeof(tm)))
260                         return -EFAULT;
261                 break;
262
263         case RTC_ALM_SET:
264                 if (copy_from_user(&alarm.time, uarg, sizeof(tm)))
265                         return -EFAULT;
266
267                 alarm.enabled = 0;
268                 alarm.pending = 0;
269                 alarm.time.tm_wday = -1;
270                 alarm.time.tm_yday = -1;
271                 alarm.time.tm_isdst = -1;
272
273                 /* RTC_ALM_SET alarms may be up to 24 hours in the future.
274                  * Rather than expecting every RTC to implement "don't care"
275                  * for day/month/year fields, just force the alarm to have
276                  * the right values for those fields.
277                  *
278                  * RTC_WKALM_SET should be used instead.  Not only does it
279                  * eliminate the need for a separate RTC_AIE_ON call, it
280                  * doesn't have the "alarm 23:59:59 in the future" race.
281                  *
282                  * NOTE:  some legacy code may have used invalid fields as
283                  * wildcards, exposing hardware "periodic alarm" capabilities.
284                  * Not supported here.
285                  */
286                 {
287                         unsigned long now, then;
288
289                         err = rtc_read_time(rtc, &tm);
290                         if (err < 0)
291                                 return err;
292                         rtc_tm_to_time(&tm, &now);
293
294                         alarm.time.tm_mday = tm.tm_mday;
295                         alarm.time.tm_mon = tm.tm_mon;
296                         alarm.time.tm_year = tm.tm_year;
297                         err  = rtc_valid_tm(&alarm.time);
298                         if (err < 0)
299                                 return err;
300                         rtc_tm_to_time(&alarm.time, &then);
301
302                         /* alarm may need to wrap into tomorrow */
303                         if (then < now) {
304                                 rtc_time_to_tm(now + 24 * 60 * 60, &tm);
305                                 alarm.time.tm_mday = tm.tm_mday;
306                                 alarm.time.tm_mon = tm.tm_mon;
307                                 alarm.time.tm_year = tm.tm_year;
308                         }
309                 }
310
311                 err = rtc_set_alarm(rtc, &alarm);
312                 break;
313
314         case RTC_RD_TIME:
315                 err = rtc_read_time(rtc, &tm);
316                 if (err < 0)
317                         return err;
318
319                 if (copy_to_user(uarg, &tm, sizeof(tm)))
320                         return -EFAULT;
321                 break;
322
323         case RTC_SET_TIME:
324                 if (copy_from_user(&tm, uarg, sizeof(tm)))
325                         return -EFAULT;
326
327                 err = rtc_set_time(rtc, &tm);
328                 break;
329
330         case RTC_PIE_ON:
331                 err = rtc_irq_set_state(rtc, NULL, 1);
332                 break;
333
334         case RTC_PIE_OFF:
335                 err = rtc_irq_set_state(rtc, NULL, 0);
336                 break;
337
338         case RTC_IRQP_SET:
339                 err = rtc_irq_set_freq(rtc, NULL, arg);
340                 break;
341
342         case RTC_IRQP_READ:
343                 err = put_user(rtc->irq_freq, (unsigned long __user *)uarg);
344                 break;
345
346 #if 0
347         case RTC_EPOCH_SET:
348 #ifndef rtc_epoch
349                 /*
350                  * There were no RTC clocks before 1900.
351                  */
352                 if (arg < 1900) {
353                         err = -EINVAL;
354                         break;
355                 }
356                 rtc_epoch = arg;
357                 err = 0;
358 #endif
359                 break;
360
361         case RTC_EPOCH_READ:
362                 err = put_user(rtc_epoch, (unsigned long __user *)uarg);
363                 break;
364 #endif
365         case RTC_WKALM_SET:
366                 if (copy_from_user(&alarm, uarg, sizeof(alarm)))
367                         return -EFAULT;
368
369                 err = rtc_set_alarm(rtc, &alarm);
370                 break;
371
372         case RTC_WKALM_RD:
373                 err = rtc_read_alarm(rtc, &alarm);
374                 if (err < 0)
375                         return err;
376
377                 if (copy_to_user(uarg, &alarm, sizeof(alarm)))
378                         return -EFAULT;
379                 break;
380
381 #ifdef CONFIG_RTC_INTF_DEV_UIE_EMUL
382         case RTC_UIE_OFF:
383                 clear_uie(rtc);
384                 return 0;
385
386         case RTC_UIE_ON:
387                 return set_uie(rtc);
388 #endif
389         default:
390                 err = -ENOTTY;
391                 break;
392         }
393
394         return err;
395 }
396
397 static int rtc_dev_release(struct inode *inode, struct file *file)
398 {
399         struct rtc_device *rtc = file->private_data;
400
401 #ifdef CONFIG_RTC_INTF_DEV_UIE_EMUL
402         clear_uie(rtc);
403 #endif
404         if (rtc->ops->release)
405                 rtc->ops->release(rtc->dev.parent);
406
407         mutex_unlock(&rtc->char_lock);
408         return 0;
409 }
410
411 static int rtc_dev_fasync(int fd, struct file *file, int on)
412 {
413         struct rtc_device *rtc = file->private_data;
414         return fasync_helper(fd, file, on, &rtc->async_queue);
415 }
416
417 static const struct file_operations rtc_dev_fops = {
418         .owner          = THIS_MODULE,
419         .llseek         = no_llseek,
420         .read           = rtc_dev_read,
421         .poll           = rtc_dev_poll,
422         .ioctl          = rtc_dev_ioctl,
423         .open           = rtc_dev_open,
424         .release        = rtc_dev_release,
425         .fasync         = rtc_dev_fasync,
426 };
427
428 /* insertion/removal hooks */
429
430 void rtc_dev_prepare(struct rtc_device *rtc)
431 {
432         if (!rtc_devt)
433                 return;
434
435         if (rtc->id >= RTC_DEV_MAX) {
436                 pr_debug("%s: too many RTC devices\n", rtc->name);
437                 return;
438         }
439
440         rtc->dev.devt = MKDEV(MAJOR(rtc_devt), rtc->id);
441
442         mutex_init(&rtc->char_lock);
443 #ifdef CONFIG_RTC_INTF_DEV_UIE_EMUL
444         INIT_WORK(&rtc->uie_task, rtc_uie_task);
445         setup_timer(&rtc->uie_timer, rtc_uie_timer, (unsigned long)rtc);
446 #endif
447
448         cdev_init(&rtc->char_dev, &rtc_dev_fops);
449         rtc->char_dev.owner = rtc->owner;
450 }
451
452 void rtc_dev_add_device(struct rtc_device *rtc)
453 {
454         if (cdev_add(&rtc->char_dev, rtc->dev.devt, 1))
455                 printk(KERN_WARNING "%s: failed to add char device %d:%d\n",
456                         rtc->name, MAJOR(rtc_devt), rtc->id);
457         else
458                 pr_debug("%s: dev (%d:%d)\n", rtc->name,
459                         MAJOR(rtc_devt), rtc->id);
460 }
461
462 void rtc_dev_del_device(struct rtc_device *rtc)
463 {
464         if (rtc->dev.devt)
465                 cdev_del(&rtc->char_dev);
466 }
467
468 void __init rtc_dev_init(void)
469 {
470         int err;
471
472         err = alloc_chrdev_region(&rtc_devt, 0, RTC_DEV_MAX, "rtc");
473         if (err < 0)
474                 printk(KERN_ERR "%s: failed to allocate char dev region\n",
475                         __FILE__);
476 }
477
478 void __exit rtc_dev_exit(void)
479 {
480         if (rtc_devt)
481                 unregister_chrdev_region(rtc_devt, RTC_DEV_MAX);
482 }