1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * RTC subsystem, dev interface
4 *
5 * Copyright (C) 2005 Tower Technologies
6 * Author: Alessandro Zummo <a.zummo@towertech.it>
7 *
8 * based on arch/arm/common/rtctime.c
9 */
10
11 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
12
13 #include <linux/compat.h>
14 #include <linux/module.h>
15 #include <linux/rtc.h>
16 #include <linux/sched/signal.h>
17 #include "rtc-core.h"
18
19 static dev_t rtc_devt;
20
21 #define RTC_DEV_MAX 16 /* 16 RTCs should be enough for everyone... */
22
rtc_dev_open(struct inode * inode,struct file * file)23 static int rtc_dev_open(struct inode *inode, struct file *file)
24 {
25 struct rtc_device *rtc = container_of(inode->i_cdev,
26 struct rtc_device, char_dev);
27
28 if (test_and_set_bit_lock(RTC_DEV_BUSY, &rtc->flags))
29 return -EBUSY;
30
31 file->private_data = rtc;
32
33 spin_lock_irq(&rtc->irq_lock);
34 rtc->irq_data = 0;
35 spin_unlock_irq(&rtc->irq_lock);
36
37 return 0;
38 }
39
40 #ifdef CONFIG_RTC_INTF_DEV_UIE_EMUL
41 /*
42 * Routine to poll RTC seconds field for change as often as possible,
43 * after first RTC_UIE use timer to reduce polling
44 */
rtc_uie_task(struct work_struct * work)45 static void rtc_uie_task(struct work_struct *work)
46 {
47 struct rtc_device *rtc =
48 container_of(work, struct rtc_device, uie_task);
49 struct rtc_time tm;
50 int num = 0;
51 int err;
52
53 err = rtc_read_time(rtc, &tm);
54
55 spin_lock_irq(&rtc->irq_lock);
56 if (rtc->stop_uie_polling || err) {
57 rtc->uie_task_active = 0;
58 } else if (rtc->oldsecs != tm.tm_sec) {
59 num = (tm.tm_sec + 60 - rtc->oldsecs) % 60;
60 rtc->oldsecs = tm.tm_sec;
61 rtc->uie_timer.expires = jiffies + HZ - (HZ / 10);
62 rtc->uie_timer_active = 1;
63 rtc->uie_task_active = 0;
64 add_timer(&rtc->uie_timer);
65 } else if (schedule_work(&rtc->uie_task) == 0) {
66 rtc->uie_task_active = 0;
67 }
68 spin_unlock_irq(&rtc->irq_lock);
69 if (num)
70 rtc_handle_legacy_irq(rtc, num, RTC_UF);
71 }
72
rtc_uie_timer(struct timer_list * t)73 static void rtc_uie_timer(struct timer_list *t)
74 {
75 struct rtc_device *rtc = from_timer(rtc, t, uie_timer);
76 unsigned long flags;
77
78 spin_lock_irqsave(&rtc->irq_lock, flags);
79 rtc->uie_timer_active = 0;
80 rtc->uie_task_active = 1;
81 if ((schedule_work(&rtc->uie_task) == 0))
82 rtc->uie_task_active = 0;
83 spin_unlock_irqrestore(&rtc->irq_lock, flags);
84 }
85
clear_uie(struct rtc_device * rtc)86 static int clear_uie(struct rtc_device *rtc)
87 {
88 spin_lock_irq(&rtc->irq_lock);
89 if (rtc->uie_irq_active) {
90 rtc->stop_uie_polling = 1;
91 if (rtc->uie_timer_active) {
92 spin_unlock_irq(&rtc->irq_lock);
93 del_timer_sync(&rtc->uie_timer);
94 spin_lock_irq(&rtc->irq_lock);
95 rtc->uie_timer_active = 0;
96 }
97 if (rtc->uie_task_active) {
98 spin_unlock_irq(&rtc->irq_lock);
99 flush_work(&rtc->uie_task);
100 spin_lock_irq(&rtc->irq_lock);
101 }
102 rtc->uie_irq_active = 0;
103 }
104 spin_unlock_irq(&rtc->irq_lock);
105 return 0;
106 }
107
set_uie(struct rtc_device * rtc)108 static int set_uie(struct rtc_device *rtc)
109 {
110 struct rtc_time tm;
111 int err;
112
113 err = rtc_read_time(rtc, &tm);
114 if (err)
115 return err;
116 spin_lock_irq(&rtc->irq_lock);
117 if (!rtc->uie_irq_active) {
118 rtc->uie_irq_active = 1;
119 rtc->stop_uie_polling = 0;
120 rtc->oldsecs = tm.tm_sec;
121 rtc->uie_task_active = 1;
122 if (schedule_work(&rtc->uie_task) == 0)
123 rtc->uie_task_active = 0;
124 }
125 rtc->irq_data = 0;
126 spin_unlock_irq(&rtc->irq_lock);
127 return 0;
128 }
129
rtc_dev_update_irq_enable_emul(struct rtc_device * rtc,unsigned int enabled)130 int rtc_dev_update_irq_enable_emul(struct rtc_device *rtc, unsigned int enabled)
131 {
132 if (enabled)
133 return set_uie(rtc);
134 else
135 return clear_uie(rtc);
136 }
137 EXPORT_SYMBOL(rtc_dev_update_irq_enable_emul);
138
139 #endif /* CONFIG_RTC_INTF_DEV_UIE_EMUL */
140
141 static ssize_t
rtc_dev_read(struct file * file,char __user * buf,size_t count,loff_t * ppos)142 rtc_dev_read(struct file *file, char __user *buf, size_t count, loff_t *ppos)
143 {
144 struct rtc_device *rtc = file->private_data;
145
146 DECLARE_WAITQUEUE(wait, current);
147 unsigned long data;
148 ssize_t ret;
149
150 if (count != sizeof(unsigned int) && count < sizeof(unsigned long))
151 return -EINVAL;
152
153 add_wait_queue(&rtc->irq_queue, &wait);
154 do {
155 __set_current_state(TASK_INTERRUPTIBLE);
156
157 spin_lock_irq(&rtc->irq_lock);
158 data = rtc->irq_data;
159 rtc->irq_data = 0;
160 spin_unlock_irq(&rtc->irq_lock);
161
162 if (data != 0) {
163 ret = 0;
164 break;
165 }
166 if (file->f_flags & O_NONBLOCK) {
167 ret = -EAGAIN;
168 break;
169 }
170 if (signal_pending(current)) {
171 ret = -ERESTARTSYS;
172 break;
173 }
174 schedule();
175 } while (1);
176 set_current_state(TASK_RUNNING);
177 remove_wait_queue(&rtc->irq_queue, &wait);
178
179 if (ret == 0) {
180 if (sizeof(int) != sizeof(long) &&
181 count == sizeof(unsigned int))
182 ret = put_user(data, (unsigned int __user *)buf) ?:
183 sizeof(unsigned int);
184 else
185 ret = put_user(data, (unsigned long __user *)buf) ?:
186 sizeof(unsigned long);
187 }
188 return ret;
189 }
190
rtc_dev_poll(struct file * file,poll_table * wait)191 static __poll_t rtc_dev_poll(struct file *file, poll_table *wait)
192 {
193 struct rtc_device *rtc = file->private_data;
194 unsigned long data;
195
196 poll_wait(file, &rtc->irq_queue, wait);
197
198 data = rtc->irq_data;
199
200 return (data != 0) ? (EPOLLIN | EPOLLRDNORM) : 0;
201 }
202
rtc_dev_ioctl(struct file * file,unsigned int cmd,unsigned long arg)203 static long rtc_dev_ioctl(struct file *file,
204 unsigned int cmd, unsigned long arg)
205 {
206 int err = 0;
207 struct rtc_device *rtc = file->private_data;
208 const struct rtc_class_ops *ops = rtc->ops;
209 struct rtc_time tm;
210 struct rtc_wkalrm alarm;
211 struct rtc_param param;
212 void __user *uarg = (void __user *)arg;
213
214 err = mutex_lock_interruptible(&rtc->ops_lock);
215 if (err)
216 return err;
217
218 /* check that the calling task has appropriate permissions
219 * for certain ioctls. doing this check here is useful
220 * to avoid duplicate code in each driver.
221 */
222 switch (cmd) {
223 case RTC_EPOCH_SET:
224 case RTC_SET_TIME:
225 case RTC_PARAM_SET:
226 if (!capable(CAP_SYS_TIME))
227 err = -EACCES;
228 break;
229
230 case RTC_IRQP_SET:
231 if (arg > rtc->max_user_freq && !capable(CAP_SYS_RESOURCE))
232 err = -EACCES;
233 break;
234
235 case RTC_PIE_ON:
236 if (rtc->irq_freq > rtc->max_user_freq &&
237 !capable(CAP_SYS_RESOURCE))
238 err = -EACCES;
239 break;
240 }
241
242 if (err)
243 goto done;
244
245 /*
246 * Drivers *SHOULD NOT* provide ioctl implementations
247 * for these requests. Instead, provide methods to
248 * support the following code, so that the RTC's main
249 * features are accessible without using ioctls.
250 *
251 * RTC and alarm times will be in UTC, by preference,
252 * but dual-booting with MS-Windows implies RTCs must
253 * use the local wall clock time.
254 */
255
256 switch (cmd) {
257 case RTC_ALM_READ:
258 mutex_unlock(&rtc->ops_lock);
259
260 err = rtc_read_alarm(rtc, &alarm);
261 if (err < 0)
262 return err;
263
264 if (copy_to_user(uarg, &alarm.time, sizeof(tm)))
265 err = -EFAULT;
266 return err;
267
268 case RTC_ALM_SET:
269 mutex_unlock(&rtc->ops_lock);
270
271 if (copy_from_user(&alarm.time, uarg, sizeof(tm)))
272 return -EFAULT;
273
274 alarm.enabled = 0;
275 alarm.pending = 0;
276 alarm.time.tm_wday = -1;
277 alarm.time.tm_yday = -1;
278 alarm.time.tm_isdst = -1;
279
280 /* RTC_ALM_SET alarms may be up to 24 hours in the future.
281 * Rather than expecting every RTC to implement "don't care"
282 * for day/month/year fields, just force the alarm to have
283 * the right values for those fields.
284 *
285 * RTC_WKALM_SET should be used instead. Not only does it
286 * eliminate the need for a separate RTC_AIE_ON call, it
287 * doesn't have the "alarm 23:59:59 in the future" race.
288 *
289 * NOTE: some legacy code may have used invalid fields as
290 * wildcards, exposing hardware "periodic alarm" capabilities.
291 * Not supported here.
292 */
293 {
294 time64_t now, then;
295
296 err = rtc_read_time(rtc, &tm);
297 if (err < 0)
298 return err;
299 now = rtc_tm_to_time64(&tm);
300
301 alarm.time.tm_mday = tm.tm_mday;
302 alarm.time.tm_mon = tm.tm_mon;
303 alarm.time.tm_year = tm.tm_year;
304 err = rtc_valid_tm(&alarm.time);
305 if (err < 0)
306 return err;
307 then = rtc_tm_to_time64(&alarm.time);
308
309 /* alarm may need to wrap into tomorrow */
310 if (then < now) {
311 rtc_time64_to_tm(now + 24 * 60 * 60, &tm);
312 alarm.time.tm_mday = tm.tm_mday;
313 alarm.time.tm_mon = tm.tm_mon;
314 alarm.time.tm_year = tm.tm_year;
315 }
316 }
317
318 return rtc_set_alarm(rtc, &alarm);
319
320 case RTC_RD_TIME:
321 mutex_unlock(&rtc->ops_lock);
322
323 err = rtc_read_time(rtc, &tm);
324 if (err < 0)
325 return err;
326
327 if (copy_to_user(uarg, &tm, sizeof(tm)))
328 err = -EFAULT;
329 return err;
330
331 case RTC_SET_TIME:
332 mutex_unlock(&rtc->ops_lock);
333
334 if (copy_from_user(&tm, uarg, sizeof(tm)))
335 return -EFAULT;
336
337 return rtc_set_time(rtc, &tm);
338
339 case RTC_PIE_ON:
340 err = rtc_irq_set_state(rtc, 1);
341 break;
342
343 case RTC_PIE_OFF:
344 err = rtc_irq_set_state(rtc, 0);
345 break;
346
347 case RTC_AIE_ON:
348 mutex_unlock(&rtc->ops_lock);
349 return rtc_alarm_irq_enable(rtc, 1);
350
351 case RTC_AIE_OFF:
352 mutex_unlock(&rtc->ops_lock);
353 return rtc_alarm_irq_enable(rtc, 0);
354
355 case RTC_UIE_ON:
356 mutex_unlock(&rtc->ops_lock);
357 return rtc_update_irq_enable(rtc, 1);
358
359 case RTC_UIE_OFF:
360 mutex_unlock(&rtc->ops_lock);
361 return rtc_update_irq_enable(rtc, 0);
362
363 case RTC_IRQP_SET:
364 err = rtc_irq_set_freq(rtc, arg);
365 break;
366 case RTC_IRQP_READ:
367 err = put_user(rtc->irq_freq, (unsigned long __user *)uarg);
368 break;
369
370 case RTC_WKALM_SET:
371 mutex_unlock(&rtc->ops_lock);
372 if (copy_from_user(&alarm, uarg, sizeof(alarm)))
373 return -EFAULT;
374
375 return rtc_set_alarm(rtc, &alarm);
376
377 case RTC_WKALM_RD:
378 mutex_unlock(&rtc->ops_lock);
379 err = rtc_read_alarm(rtc, &alarm);
380 if (err < 0)
381 return err;
382
383 if (copy_to_user(uarg, &alarm, sizeof(alarm)))
384 err = -EFAULT;
385 return err;
386
387 case RTC_PARAM_GET:
388 if (copy_from_user(¶m, uarg, sizeof(param))) {
389 mutex_unlock(&rtc->ops_lock);
390 return -EFAULT;
391 }
392
393 switch(param.param) {
394 case RTC_PARAM_FEATURES:
395 if (param.index != 0)
396 err = -EINVAL;
397 param.uvalue = rtc->features[0];
398 break;
399
400 case RTC_PARAM_CORRECTION: {
401 long offset;
402 mutex_unlock(&rtc->ops_lock);
403 if (param.index != 0)
404 return -EINVAL;
405 err = rtc_read_offset(rtc, &offset);
406 mutex_lock(&rtc->ops_lock);
407 if (err == 0)
408 param.svalue = offset;
409 break;
410 }
411 default:
412 if (rtc->ops->param_get)
413 err = rtc->ops->param_get(rtc->dev.parent, ¶m);
414 else
415 err = -EINVAL;
416 }
417
418 if (!err)
419 if (copy_to_user(uarg, ¶m, sizeof(param)))
420 err = -EFAULT;
421
422 break;
423
424 case RTC_PARAM_SET:
425 if (copy_from_user(¶m, uarg, sizeof(param))) {
426 mutex_unlock(&rtc->ops_lock);
427 return -EFAULT;
428 }
429
430 switch(param.param) {
431 case RTC_PARAM_FEATURES:
432 err = -EINVAL;
433 break;
434
435 case RTC_PARAM_CORRECTION:
436 mutex_unlock(&rtc->ops_lock);
437 if (param.index != 0)
438 return -EINVAL;
439 return rtc_set_offset(rtc, param.svalue);
440
441 default:
442 if (rtc->ops->param_set)
443 err = rtc->ops->param_set(rtc->dev.parent, ¶m);
444 else
445 err = -EINVAL;
446 }
447
448 break;
449
450 default:
451 /* Finally try the driver's ioctl interface */
452 if (ops->ioctl) {
453 err = ops->ioctl(rtc->dev.parent, cmd, arg);
454 if (err == -ENOIOCTLCMD)
455 err = -ENOTTY;
456 } else {
457 err = -ENOTTY;
458 }
459 break;
460 }
461
462 done:
463 mutex_unlock(&rtc->ops_lock);
464 return err;
465 }
466
467 #ifdef CONFIG_COMPAT
468 #define RTC_IRQP_SET32 _IOW('p', 0x0c, __u32)
469 #define RTC_IRQP_READ32 _IOR('p', 0x0b, __u32)
470 #define RTC_EPOCH_SET32 _IOW('p', 0x0e, __u32)
471
rtc_dev_compat_ioctl(struct file * file,unsigned int cmd,unsigned long arg)472 static long rtc_dev_compat_ioctl(struct file *file,
473 unsigned int cmd, unsigned long arg)
474 {
475 struct rtc_device *rtc = file->private_data;
476 void __user *uarg = compat_ptr(arg);
477
478 switch (cmd) {
479 case RTC_IRQP_READ32:
480 return put_user(rtc->irq_freq, (__u32 __user *)uarg);
481
482 case RTC_IRQP_SET32:
483 /* arg is a plain integer, not pointer */
484 return rtc_dev_ioctl(file, RTC_IRQP_SET, arg);
485
486 case RTC_EPOCH_SET32:
487 /* arg is a plain integer, not pointer */
488 return rtc_dev_ioctl(file, RTC_EPOCH_SET, arg);
489 }
490
491 return rtc_dev_ioctl(file, cmd, (unsigned long)uarg);
492 }
493 #endif
494
rtc_dev_fasync(int fd,struct file * file,int on)495 static int rtc_dev_fasync(int fd, struct file *file, int on)
496 {
497 struct rtc_device *rtc = file->private_data;
498
499 return fasync_helper(fd, file, on, &rtc->async_queue);
500 }
501
rtc_dev_release(struct inode * inode,struct file * file)502 static int rtc_dev_release(struct inode *inode, struct file *file)
503 {
504 struct rtc_device *rtc = file->private_data;
505
506 /* We shut down the repeating IRQs that userspace enabled,
507 * since nothing is listening to them.
508 * - Update (UIE) ... currently only managed through ioctls
509 * - Periodic (PIE) ... also used through rtc_*() interface calls
510 *
511 * Leave the alarm alone; it may be set to trigger a system wakeup
512 * later, or be used by kernel code, and is a one-shot event anyway.
513 */
514
515 /* Keep ioctl until all drivers are converted */
516 rtc_dev_ioctl(file, RTC_UIE_OFF, 0);
517 rtc_update_irq_enable(rtc, 0);
518 rtc_irq_set_state(rtc, 0);
519
520 clear_bit_unlock(RTC_DEV_BUSY, &rtc->flags);
521 return 0;
522 }
523
524 static const struct file_operations rtc_dev_fops = {
525 .owner = THIS_MODULE,
526 .llseek = no_llseek,
527 .read = rtc_dev_read,
528 .poll = rtc_dev_poll,
529 .unlocked_ioctl = rtc_dev_ioctl,
530 #ifdef CONFIG_COMPAT
531 .compat_ioctl = rtc_dev_compat_ioctl,
532 #endif
533 .open = rtc_dev_open,
534 .release = rtc_dev_release,
535 .fasync = rtc_dev_fasync,
536 };
537
538 /* insertion/removal hooks */
539
rtc_dev_prepare(struct rtc_device * rtc)540 void rtc_dev_prepare(struct rtc_device *rtc)
541 {
542 if (!rtc_devt)
543 return;
544
545 if (rtc->id >= RTC_DEV_MAX) {
546 dev_dbg(&rtc->dev, "too many RTC devices\n");
547 return;
548 }
549
550 rtc->dev.devt = MKDEV(MAJOR(rtc_devt), rtc->id);
551
552 #ifdef CONFIG_RTC_INTF_DEV_UIE_EMUL
553 INIT_WORK(&rtc->uie_task, rtc_uie_task);
554 timer_setup(&rtc->uie_timer, rtc_uie_timer, 0);
555 #endif
556
557 cdev_init(&rtc->char_dev, &rtc_dev_fops);
558 rtc->char_dev.owner = rtc->owner;
559 }
560
rtc_dev_init(void)561 void __init rtc_dev_init(void)
562 {
563 int err;
564
565 err = alloc_chrdev_region(&rtc_devt, 0, RTC_DEV_MAX, "rtc");
566 if (err < 0)
567 pr_err("failed to allocate char dev region\n");
568 }
569