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 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
15
16 #include <linux/module.h>
17 #include <linux/rtc.h>
18 #include <linux/sched.h>
19 #include "rtc-core.h"
20
21 static dev_t rtc_devt;
22
23 #define RTC_DEV_MAX 16 /* 16 RTCs should be enough for everyone... */
24
rtc_dev_open(struct inode * inode,struct file * file)25 static int rtc_dev_open(struct inode *inode, struct file *file)
26 {
27 int err;
28 struct rtc_device *rtc = container_of(inode->i_cdev,
29 struct rtc_device, char_dev);
30 const struct rtc_class_ops *ops = rtc->ops;
31
32 if (test_and_set_bit_lock(RTC_DEV_BUSY, &rtc->flags))
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 */
47 clear_bit_unlock(RTC_DEV_BUSY, &rtc->flags);
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 */
rtc_uie_task(struct work_struct * work)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 spin_lock_irq(&rtc->irq_lock);
67 if (rtc->stop_uie_polling || err) {
68 rtc->uie_task_active = 0;
69 } else if (rtc->oldsecs != tm.tm_sec) {
70 num = (tm.tm_sec + 60 - rtc->oldsecs) % 60;
71 rtc->oldsecs = tm.tm_sec;
72 rtc->uie_timer.expires = jiffies + HZ - (HZ/10);
73 rtc->uie_timer_active = 1;
74 rtc->uie_task_active = 0;
75 add_timer(&rtc->uie_timer);
76 } else if (schedule_work(&rtc->uie_task) == 0) {
77 rtc->uie_task_active = 0;
78 }
79 spin_unlock_irq(&rtc->irq_lock);
80 if (num)
81 rtc_handle_legacy_irq(rtc, num, RTC_UF);
82 }
rtc_uie_timer(unsigned long data)83 static void rtc_uie_timer(unsigned long data)
84 {
85 struct rtc_device *rtc = (struct rtc_device *)data;
86 unsigned long flags;
87
88 spin_lock_irqsave(&rtc->irq_lock, flags);
89 rtc->uie_timer_active = 0;
90 rtc->uie_task_active = 1;
91 if ((schedule_work(&rtc->uie_task) == 0))
92 rtc->uie_task_active = 0;
93 spin_unlock_irqrestore(&rtc->irq_lock, flags);
94 }
95
clear_uie(struct rtc_device * rtc)96 static int clear_uie(struct rtc_device *rtc)
97 {
98 spin_lock_irq(&rtc->irq_lock);
99 if (rtc->uie_irq_active) {
100 rtc->stop_uie_polling = 1;
101 if (rtc->uie_timer_active) {
102 spin_unlock_irq(&rtc->irq_lock);
103 del_timer_sync(&rtc->uie_timer);
104 spin_lock_irq(&rtc->irq_lock);
105 rtc->uie_timer_active = 0;
106 }
107 if (rtc->uie_task_active) {
108 spin_unlock_irq(&rtc->irq_lock);
109 flush_scheduled_work();
110 spin_lock_irq(&rtc->irq_lock);
111 }
112 rtc->uie_irq_active = 0;
113 }
114 spin_unlock_irq(&rtc->irq_lock);
115 return 0;
116 }
117
set_uie(struct rtc_device * rtc)118 static int set_uie(struct rtc_device *rtc)
119 {
120 struct rtc_time tm;
121 int err;
122
123 err = rtc_read_time(rtc, &tm);
124 if (err)
125 return err;
126 spin_lock_irq(&rtc->irq_lock);
127 if (!rtc->uie_irq_active) {
128 rtc->uie_irq_active = 1;
129 rtc->stop_uie_polling = 0;
130 rtc->oldsecs = tm.tm_sec;
131 rtc->uie_task_active = 1;
132 if (schedule_work(&rtc->uie_task) == 0)
133 rtc->uie_task_active = 0;
134 }
135 rtc->irq_data = 0;
136 spin_unlock_irq(&rtc->irq_lock);
137 return 0;
138 }
139
rtc_dev_update_irq_enable_emul(struct rtc_device * rtc,unsigned int enabled)140 int rtc_dev_update_irq_enable_emul(struct rtc_device *rtc, unsigned int enabled)
141 {
142 if (enabled)
143 return set_uie(rtc);
144 else
145 return clear_uie(rtc);
146 }
147 EXPORT_SYMBOL(rtc_dev_update_irq_enable_emul);
148
149 #endif /* CONFIG_RTC_INTF_DEV_UIE_EMUL */
150
151 static ssize_t
rtc_dev_read(struct file * file,char __user * buf,size_t count,loff_t * ppos)152 rtc_dev_read(struct file *file, char __user *buf, size_t count, loff_t *ppos)
153 {
154 struct rtc_device *rtc = file->private_data;
155
156 DECLARE_WAITQUEUE(wait, current);
157 unsigned long data;
158 ssize_t ret;
159
160 if (count != sizeof(unsigned int) && count < sizeof(unsigned long))
161 return -EINVAL;
162
163 add_wait_queue(&rtc->irq_queue, &wait);
164 do {
165 __set_current_state(TASK_INTERRUPTIBLE);
166
167 spin_lock_irq(&rtc->irq_lock);
168 data = rtc->irq_data;
169 rtc->irq_data = 0;
170 spin_unlock_irq(&rtc->irq_lock);
171
172 if (data != 0) {
173 ret = 0;
174 break;
175 }
176 if (file->f_flags & O_NONBLOCK) {
177 ret = -EAGAIN;
178 break;
179 }
180 if (signal_pending(current)) {
181 ret = -ERESTARTSYS;
182 break;
183 }
184 schedule();
185 } while (1);
186 set_current_state(TASK_RUNNING);
187 remove_wait_queue(&rtc->irq_queue, &wait);
188
189 if (ret == 0) {
190 /* Check for any data updates */
191 if (rtc->ops->read_callback)
192 data = rtc->ops->read_callback(rtc->dev.parent,
193 data);
194
195 if (sizeof(int) != sizeof(long) &&
196 count == sizeof(unsigned int))
197 ret = put_user(data, (unsigned int __user *)buf) ?:
198 sizeof(unsigned int);
199 else
200 ret = put_user(data, (unsigned long __user *)buf) ?:
201 sizeof(unsigned long);
202 }
203 return ret;
204 }
205
rtc_dev_poll(struct file * file,poll_table * wait)206 static unsigned int rtc_dev_poll(struct file *file, poll_table *wait)
207 {
208 struct rtc_device *rtc = file->private_data;
209 unsigned long data;
210
211 poll_wait(file, &rtc->irq_queue, wait);
212
213 data = rtc->irq_data;
214
215 return (data != 0) ? (POLLIN | POLLRDNORM) : 0;
216 }
217
rtc_dev_ioctl(struct file * file,unsigned int cmd,unsigned long arg)218 static long rtc_dev_ioctl(struct file *file,
219 unsigned int cmd, unsigned long arg)
220 {
221 int err = 0;
222 struct rtc_device *rtc = file->private_data;
223 const struct rtc_class_ops *ops = rtc->ops;
224 struct rtc_time tm;
225 struct rtc_wkalrm alarm;
226 void __user *uarg = (void __user *) arg;
227
228 err = mutex_lock_interruptible(&rtc->ops_lock);
229 if (err)
230 return err;
231
232 /* check that the calling task has appropriate permissions
233 * for certain ioctls. doing this check here is useful
234 * to avoid duplicate code in each driver.
235 */
236 switch (cmd) {
237 case RTC_EPOCH_SET:
238 case RTC_SET_TIME:
239 if (!capable(CAP_SYS_TIME))
240 err = -EACCES;
241 break;
242
243 case RTC_IRQP_SET:
244 if (arg > rtc->max_user_freq && !capable(CAP_SYS_RESOURCE))
245 err = -EACCES;
246 break;
247
248 case RTC_PIE_ON:
249 if (rtc->irq_freq > rtc->max_user_freq &&
250 !capable(CAP_SYS_RESOURCE))
251 err = -EACCES;
252 break;
253 }
254
255 if (err)
256 goto done;
257
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_AIE_ON:
361 mutex_unlock(&rtc->ops_lock);
362 return rtc_alarm_irq_enable(rtc, 1);
363
364 case RTC_AIE_OFF:
365 mutex_unlock(&rtc->ops_lock);
366 return rtc_alarm_irq_enable(rtc, 0);
367
368 case RTC_UIE_ON:
369 mutex_unlock(&rtc->ops_lock);
370 return rtc_update_irq_enable(rtc, 1);
371
372 case RTC_UIE_OFF:
373 mutex_unlock(&rtc->ops_lock);
374 return rtc_update_irq_enable(rtc, 0);
375
376 case RTC_IRQP_SET:
377 err = rtc_irq_set_freq(rtc, NULL, arg);
378 break;
379
380 case RTC_IRQP_READ:
381 err = put_user(rtc->irq_freq, (unsigned long __user *)uarg);
382 break;
383
384 case RTC_WKALM_SET:
385 mutex_unlock(&rtc->ops_lock);
386 if (copy_from_user(&alarm, uarg, sizeof(alarm)))
387 return -EFAULT;
388
389 return rtc_set_alarm(rtc, &alarm);
390
391 case RTC_WKALM_RD:
392 mutex_unlock(&rtc->ops_lock);
393 err = rtc_read_alarm(rtc, &alarm);
394 if (err < 0)
395 return err;
396
397 if (copy_to_user(uarg, &alarm, sizeof(alarm)))
398 err = -EFAULT;
399 return err;
400
401 default:
402 /* Finally try the driver's ioctl interface */
403 if (ops->ioctl) {
404 err = ops->ioctl(rtc->dev.parent, cmd, arg);
405 if (err == -ENOIOCTLCMD)
406 err = -ENOTTY;
407 } else
408 err = -ENOTTY;
409 break;
410 }
411
412 done:
413 mutex_unlock(&rtc->ops_lock);
414 return err;
415 }
416
rtc_dev_fasync(int fd,struct file * file,int on)417 static int rtc_dev_fasync(int fd, struct file *file, int on)
418 {
419 struct rtc_device *rtc = file->private_data;
420 return fasync_helper(fd, file, on, &rtc->async_queue);
421 }
422
rtc_dev_release(struct inode * inode,struct file * file)423 static int rtc_dev_release(struct inode *inode, struct file *file)
424 {
425 struct rtc_device *rtc = file->private_data;
426
427 /* We shut down the repeating IRQs that userspace enabled,
428 * since nothing is listening to them.
429 * - Update (UIE) ... currently only managed through ioctls
430 * - Periodic (PIE) ... also used through rtc_*() interface calls
431 *
432 * Leave the alarm alone; it may be set to trigger a system wakeup
433 * later, or be used by kernel code, and is a one-shot event anyway.
434 */
435
436 /* Keep ioctl until all drivers are converted */
437 rtc_dev_ioctl(file, RTC_UIE_OFF, 0);
438 rtc_update_irq_enable(rtc, 0);
439 rtc_irq_set_state(rtc, NULL, 0);
440
441 if (rtc->ops->release)
442 rtc->ops->release(rtc->dev.parent);
443
444 clear_bit_unlock(RTC_DEV_BUSY, &rtc->flags);
445 return 0;
446 }
447
448 static const struct file_operations rtc_dev_fops = {
449 .owner = THIS_MODULE,
450 .llseek = no_llseek,
451 .read = rtc_dev_read,
452 .poll = rtc_dev_poll,
453 .unlocked_ioctl = rtc_dev_ioctl,
454 .open = rtc_dev_open,
455 .release = rtc_dev_release,
456 .fasync = rtc_dev_fasync,
457 };
458
459 /* insertion/removal hooks */
460
rtc_dev_prepare(struct rtc_device * rtc)461 void rtc_dev_prepare(struct rtc_device *rtc)
462 {
463 if (!rtc_devt)
464 return;
465
466 if (rtc->id >= RTC_DEV_MAX) {
467 dev_dbg(&rtc->dev, "%s: too many RTC devices\n", rtc->name);
468 return;
469 }
470
471 rtc->dev.devt = MKDEV(MAJOR(rtc_devt), rtc->id);
472
473 #ifdef CONFIG_RTC_INTF_DEV_UIE_EMUL
474 INIT_WORK(&rtc->uie_task, rtc_uie_task);
475 setup_timer(&rtc->uie_timer, rtc_uie_timer, (unsigned long)rtc);
476 #endif
477
478 cdev_init(&rtc->char_dev, &rtc_dev_fops);
479 rtc->char_dev.owner = rtc->owner;
480 }
481
rtc_dev_add_device(struct rtc_device * rtc)482 void rtc_dev_add_device(struct rtc_device *rtc)
483 {
484 if (cdev_add(&rtc->char_dev, rtc->dev.devt, 1))
485 dev_warn(&rtc->dev, "%s: failed to add char device %d:%d\n",
486 rtc->name, MAJOR(rtc_devt), rtc->id);
487 else
488 dev_dbg(&rtc->dev, "%s: dev (%d:%d)\n", rtc->name,
489 MAJOR(rtc_devt), rtc->id);
490 }
491
rtc_dev_del_device(struct rtc_device * rtc)492 void rtc_dev_del_device(struct rtc_device *rtc)
493 {
494 if (rtc->dev.devt)
495 cdev_del(&rtc->char_dev);
496 }
497
rtc_dev_init(void)498 void __init rtc_dev_init(void)
499 {
500 int err;
501
502 err = alloc_chrdev_region(&rtc_devt, 0, RTC_DEV_MAX, "rtc");
503 if (err < 0)
504 pr_err("failed to allocate char dev region\n");
505 }
506
rtc_dev_exit(void)507 void __exit rtc_dev_exit(void)
508 {
509 if (rtc_devt)
510 unregister_chrdev_region(rtc_devt, RTC_DEV_MAX);
511 }
512