xref: /openbmc/linux/drivers/rtc/dev.c (revision 33740c7f)
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(&param, 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, &param);
414 			else
415 				err = -EINVAL;
416 		}
417 
418 		if (!err)
419 			if (copy_to_user(uarg, &param, sizeof(param)))
420 				err = -EFAULT;
421 
422 		break;
423 
424 	case RTC_PARAM_SET:
425 		if (copy_from_user(&param, 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, &param);
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