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 | |
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, addr: &rtc->flags)) |
29 | return -EBUSY; |
30 | |
31 | file->private_data = rtc; |
32 | |
33 | spin_lock_irq(lock: &rtc->irq_lock); |
34 | rtc->irq_data = 0; |
35 | spin_unlock_irq(lock: &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 | */ |
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: &tm); |
54 | |
55 | spin_lock_irq(lock: &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(timer: &rtc->uie_timer); |
65 | } else if (schedule_work(work: &rtc->uie_task) == 0) { |
66 | rtc->uie_task_active = 0; |
67 | } |
68 | spin_unlock_irq(lock: &rtc->irq_lock); |
69 | if (num) |
70 | rtc_handle_legacy_irq(rtc, num, RTC_UF); |
71 | } |
72 | |
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(work: &rtc->uie_task) == 0)) |
82 | rtc->uie_task_active = 0; |
83 | spin_unlock_irqrestore(lock: &rtc->irq_lock, flags); |
84 | } |
85 | |
86 | static int clear_uie(struct rtc_device *rtc) |
87 | { |
88 | spin_lock_irq(lock: &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(lock: &rtc->irq_lock); |
93 | del_timer_sync(timer: &rtc->uie_timer); |
94 | spin_lock_irq(lock: &rtc->irq_lock); |
95 | rtc->uie_timer_active = 0; |
96 | } |
97 | if (rtc->uie_task_active) { |
98 | spin_unlock_irq(lock: &rtc->irq_lock); |
99 | flush_work(work: &rtc->uie_task); |
100 | spin_lock_irq(lock: &rtc->irq_lock); |
101 | } |
102 | rtc->uie_irq_active = 0; |
103 | } |
104 | spin_unlock_irq(lock: &rtc->irq_lock); |
105 | return 0; |
106 | } |
107 | |
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: &tm); |
114 | if (err) |
115 | return err; |
116 | spin_lock_irq(lock: &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(work: &rtc->uie_task) == 0) |
123 | rtc->uie_task_active = 0; |
124 | } |
125 | rtc->irq_data = 0; |
126 | spin_unlock_irq(lock: &rtc->irq_lock); |
127 | return 0; |
128 | } |
129 | |
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 |
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(wq_head: &rtc->irq_queue, wq_entry: &wait); |
154 | do { |
155 | __set_current_state(TASK_INTERRUPTIBLE); |
156 | |
157 | spin_lock_irq(lock: &rtc->irq_lock); |
158 | data = rtc->irq_data; |
159 | rtc->irq_data = 0; |
160 | spin_unlock_irq(lock: &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(wq_head: &rtc->irq_queue, wq_entry: &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 | |
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(filp: file, wait_address: &rtc->irq_queue, p: wait); |
197 | |
198 | data = rtc->irq_data; |
199 | |
200 | return (data != 0) ? (EPOLLIN | EPOLLRDNORM) : 0; |
201 | } |
202 | |
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(lock: &rtc->ops_lock); |
259 | |
260 | err = rtc_read_alarm(rtc, alrm: &alarm); |
261 | if (err < 0) |
262 | return err; |
263 | |
264 | if (copy_to_user(to: uarg, from: &alarm.time, n: sizeof(tm))) |
265 | err = -EFAULT; |
266 | return err; |
267 | |
268 | case RTC_ALM_SET: |
269 | mutex_unlock(lock: &rtc->ops_lock); |
270 | |
271 | if (copy_from_user(to: &alarm.time, from: uarg, n: 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: &tm); |
297 | if (err < 0) |
298 | return err; |
299 | now = rtc_tm_to_time64(tm: &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(tm: &alarm.time); |
305 | if (err < 0) |
306 | return err; |
307 | then = rtc_tm_to_time64(tm: &alarm.time); |
308 | |
309 | /* alarm may need to wrap into tomorrow */ |
310 | if (then < now) { |
311 | rtc_time64_to_tm(time: now + 24 * 60 * 60, tm: &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, alrm: &alarm); |
319 | |
320 | case RTC_RD_TIME: |
321 | mutex_unlock(lock: &rtc->ops_lock); |
322 | |
323 | err = rtc_read_time(rtc, tm: &tm); |
324 | if (err < 0) |
325 | return err; |
326 | |
327 | if (copy_to_user(to: uarg, from: &tm, n: sizeof(tm))) |
328 | err = -EFAULT; |
329 | return err; |
330 | |
331 | case RTC_SET_TIME: |
332 | mutex_unlock(lock: &rtc->ops_lock); |
333 | |
334 | if (copy_from_user(to: &tm, from: uarg, n: sizeof(tm))) |
335 | return -EFAULT; |
336 | |
337 | return rtc_set_time(rtc, tm: &tm); |
338 | |
339 | case RTC_PIE_ON: |
340 | err = rtc_irq_set_state(rtc, enabled: 1); |
341 | break; |
342 | |
343 | case RTC_PIE_OFF: |
344 | err = rtc_irq_set_state(rtc, enabled: 0); |
345 | break; |
346 | |
347 | case RTC_AIE_ON: |
348 | mutex_unlock(lock: &rtc->ops_lock); |
349 | return rtc_alarm_irq_enable(rtc, enabled: 1); |
350 | |
351 | case RTC_AIE_OFF: |
352 | mutex_unlock(lock: &rtc->ops_lock); |
353 | return rtc_alarm_irq_enable(rtc, enabled: 0); |
354 | |
355 | case RTC_UIE_ON: |
356 | mutex_unlock(lock: &rtc->ops_lock); |
357 | return rtc_update_irq_enable(rtc, enabled: 1); |
358 | |
359 | case RTC_UIE_OFF: |
360 | mutex_unlock(lock: &rtc->ops_lock); |
361 | return rtc_update_irq_enable(rtc, enabled: 0); |
362 | |
363 | case RTC_IRQP_SET: |
364 | err = rtc_irq_set_freq(rtc, freq: 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(lock: &rtc->ops_lock); |
372 | if (copy_from_user(to: &alarm, from: uarg, n: sizeof(alarm))) |
373 | return -EFAULT; |
374 | |
375 | return rtc_set_alarm(rtc, alrm: &alarm); |
376 | |
377 | case RTC_WKALM_RD: |
378 | mutex_unlock(lock: &rtc->ops_lock); |
379 | err = rtc_read_alarm(rtc, alrm: &alarm); |
380 | if (err < 0) |
381 | return err; |
382 | |
383 | if (copy_to_user(to: uarg, from: &alarm, n: sizeof(alarm))) |
384 | err = -EFAULT; |
385 | return err; |
386 | |
387 | case RTC_PARAM_GET: |
388 | if (copy_from_user(to: ¶m, from: uarg, n: sizeof(param))) { |
389 | mutex_unlock(lock: &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(lock: &rtc->ops_lock); |
403 | if (param.index != 0) |
404 | return -EINVAL; |
405 | err = rtc_read_offset(rtc, offset: &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(to: uarg, from: ¶m, n: sizeof(param))) |
420 | err = -EFAULT; |
421 | |
422 | break; |
423 | |
424 | case RTC_PARAM_SET: |
425 | if (copy_from_user(to: ¶m, from: uarg, n: sizeof(param))) { |
426 | mutex_unlock(lock: &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(lock: &rtc->ops_lock); |
437 | if (param.index != 0) |
438 | return -EINVAL; |
439 | return rtc_set_offset(rtc, offset: 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(lock: &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 | |
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(uptr: 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, arg: (unsigned long)uarg); |
492 | } |
493 | #endif |
494 | |
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 | |
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, arg: 0); |
517 | rtc_update_irq_enable(rtc, enabled: 0); |
518 | rtc_irq_set_state(rtc, enabled: 0); |
519 | |
520 | clear_bit_unlock(RTC_DEV_BUSY, addr: &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 | |
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 | |
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 | |