Line data Source code
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 0 : static int rtc_dev_open(struct inode *inode, struct file *file)
24 : {
25 0 : struct rtc_device *rtc = container_of(inode->i_cdev,
26 : struct rtc_device, char_dev);
27 :
28 0 : if (test_and_set_bit_lock(RTC_DEV_BUSY, &rtc->flags))
29 : return -EBUSY;
30 :
31 0 : file->private_data = rtc;
32 :
33 0 : spin_lock_irq(&rtc->irq_lock);
34 0 : rtc->irq_data = 0;
35 0 : spin_unlock_irq(&rtc->irq_lock);
36 :
37 0 : 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);
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 :
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 :
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_scheduled_work();
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 :
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 :
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 0 : rtc_dev_read(struct file *file, char __user *buf, size_t count, loff_t *ppos)
143 : {
144 0 : struct rtc_device *rtc = file->private_data;
145 :
146 0 : DECLARE_WAITQUEUE(wait, current);
147 0 : unsigned long data;
148 0 : ssize_t ret;
149 :
150 0 : if (count != sizeof(unsigned int) && count < sizeof(unsigned long))
151 : return -EINVAL;
152 :
153 0 : add_wait_queue(&rtc->irq_queue, &wait);
154 0 : do {
155 0 : __set_current_state(TASK_INTERRUPTIBLE);
156 :
157 0 : spin_lock_irq(&rtc->irq_lock);
158 0 : data = rtc->irq_data;
159 0 : rtc->irq_data = 0;
160 0 : spin_unlock_irq(&rtc->irq_lock);
161 :
162 0 : if (data != 0) {
163 : ret = 0;
164 : break;
165 : }
166 0 : if (file->f_flags & O_NONBLOCK) {
167 : ret = -EAGAIN;
168 : break;
169 : }
170 0 : if (signal_pending(current)) {
171 : ret = -ERESTARTSYS;
172 : break;
173 : }
174 0 : schedule();
175 0 : } while (1);
176 0 : set_current_state(TASK_RUNNING);
177 0 : remove_wait_queue(&rtc->irq_queue, &wait);
178 :
179 0 : if (ret == 0) {
180 0 : if (sizeof(int) != sizeof(long) &&
181 : count == sizeof(unsigned int))
182 0 : ret = put_user(data, (unsigned int __user *)buf) ?:
183 : sizeof(unsigned int);
184 : else
185 0 : ret = put_user(data, (unsigned long __user *)buf) ?:
186 : sizeof(unsigned long);
187 : }
188 : return ret;
189 : }
190 :
191 0 : static __poll_t rtc_dev_poll(struct file *file, poll_table *wait)
192 : {
193 0 : struct rtc_device *rtc = file->private_data;
194 0 : unsigned long data;
195 :
196 0 : poll_wait(file, &rtc->irq_queue, wait);
197 :
198 0 : data = rtc->irq_data;
199 :
200 0 : return (data != 0) ? (EPOLLIN | EPOLLRDNORM) : 0;
201 : }
202 :
203 0 : static long rtc_dev_ioctl(struct file *file,
204 : unsigned int cmd, unsigned long arg)
205 : {
206 0 : int err = 0;
207 0 : struct rtc_device *rtc = file->private_data;
208 0 : const struct rtc_class_ops *ops = rtc->ops;
209 0 : struct rtc_time tm;
210 0 : struct rtc_wkalrm alarm;
211 0 : void __user *uarg = (void __user *)arg;
212 :
213 0 : err = mutex_lock_interruptible(&rtc->ops_lock);
214 0 : if (err)
215 0 : return err;
216 :
217 : /* check that the calling task has appropriate permissions
218 : * for certain ioctls. doing this check here is useful
219 : * to avoid duplicate code in each driver.
220 : */
221 0 : switch (cmd) {
222 0 : case RTC_EPOCH_SET:
223 : case RTC_SET_TIME:
224 0 : if (!capable(CAP_SYS_TIME))
225 : err = -EACCES;
226 : break;
227 :
228 0 : case RTC_IRQP_SET:
229 0 : if (arg > rtc->max_user_freq && !capable(CAP_SYS_RESOURCE))
230 : err = -EACCES;
231 : break;
232 :
233 0 : case RTC_PIE_ON:
234 0 : if (rtc->irq_freq > rtc->max_user_freq &&
235 0 : !capable(CAP_SYS_RESOURCE))
236 : err = -EACCES;
237 : break;
238 : }
239 :
240 0 : if (err)
241 0 : goto done;
242 :
243 : /*
244 : * Drivers *SHOULD NOT* provide ioctl implementations
245 : * for these requests. Instead, provide methods to
246 : * support the following code, so that the RTC's main
247 : * features are accessible without using ioctls.
248 : *
249 : * RTC and alarm times will be in UTC, by preference,
250 : * but dual-booting with MS-Windows implies RTCs must
251 : * use the local wall clock time.
252 : */
253 :
254 0 : switch (cmd) {
255 0 : case RTC_ALM_READ:
256 0 : mutex_unlock(&rtc->ops_lock);
257 :
258 0 : err = rtc_read_alarm(rtc, &alarm);
259 0 : if (err < 0)
260 0 : return err;
261 :
262 0 : if (copy_to_user(uarg, &alarm.time, sizeof(tm)))
263 0 : err = -EFAULT;
264 0 : return err;
265 :
266 0 : case RTC_ALM_SET:
267 0 : mutex_unlock(&rtc->ops_lock);
268 :
269 0 : if (copy_from_user(&alarm.time, uarg, sizeof(tm)))
270 : return -EFAULT;
271 :
272 0 : alarm.enabled = 0;
273 0 : alarm.pending = 0;
274 0 : alarm.time.tm_wday = -1;
275 0 : alarm.time.tm_yday = -1;
276 0 : alarm.time.tm_isdst = -1;
277 :
278 : /* RTC_ALM_SET alarms may be up to 24 hours in the future.
279 : * Rather than expecting every RTC to implement "don't care"
280 : * for day/month/year fields, just force the alarm to have
281 : * the right values for those fields.
282 : *
283 : * RTC_WKALM_SET should be used instead. Not only does it
284 : * eliminate the need for a separate RTC_AIE_ON call, it
285 : * doesn't have the "alarm 23:59:59 in the future" race.
286 : *
287 : * NOTE: some legacy code may have used invalid fields as
288 : * wildcards, exposing hardware "periodic alarm" capabilities.
289 : * Not supported here.
290 : */
291 : {
292 0 : time64_t now, then;
293 :
294 0 : err = rtc_read_time(rtc, &tm);
295 0 : if (err < 0)
296 0 : return err;
297 0 : now = rtc_tm_to_time64(&tm);
298 :
299 0 : alarm.time.tm_mday = tm.tm_mday;
300 0 : alarm.time.tm_mon = tm.tm_mon;
301 0 : alarm.time.tm_year = tm.tm_year;
302 0 : err = rtc_valid_tm(&alarm.time);
303 0 : if (err < 0)
304 0 : return err;
305 0 : then = rtc_tm_to_time64(&alarm.time);
306 :
307 : /* alarm may need to wrap into tomorrow */
308 0 : if (then < now) {
309 0 : rtc_time64_to_tm(now + 24 * 60 * 60, &tm);
310 0 : alarm.time.tm_mday = tm.tm_mday;
311 0 : alarm.time.tm_mon = tm.tm_mon;
312 0 : alarm.time.tm_year = tm.tm_year;
313 : }
314 : }
315 :
316 0 : return rtc_set_alarm(rtc, &alarm);
317 :
318 0 : case RTC_RD_TIME:
319 0 : mutex_unlock(&rtc->ops_lock);
320 :
321 0 : err = rtc_read_time(rtc, &tm);
322 0 : if (err < 0)
323 0 : return err;
324 :
325 0 : if (copy_to_user(uarg, &tm, sizeof(tm)))
326 0 : err = -EFAULT;
327 0 : return err;
328 :
329 0 : case RTC_SET_TIME:
330 0 : mutex_unlock(&rtc->ops_lock);
331 :
332 0 : if (copy_from_user(&tm, uarg, sizeof(tm)))
333 : return -EFAULT;
334 :
335 0 : return rtc_set_time(rtc, &tm);
336 :
337 0 : case RTC_PIE_ON:
338 0 : err = rtc_irq_set_state(rtc, 1);
339 0 : break;
340 :
341 0 : case RTC_PIE_OFF:
342 0 : err = rtc_irq_set_state(rtc, 0);
343 0 : break;
344 :
345 0 : case RTC_AIE_ON:
346 0 : mutex_unlock(&rtc->ops_lock);
347 0 : return rtc_alarm_irq_enable(rtc, 1);
348 :
349 0 : case RTC_AIE_OFF:
350 0 : mutex_unlock(&rtc->ops_lock);
351 0 : return rtc_alarm_irq_enable(rtc, 0);
352 :
353 0 : case RTC_UIE_ON:
354 0 : mutex_unlock(&rtc->ops_lock);
355 0 : return rtc_update_irq_enable(rtc, 1);
356 :
357 0 : case RTC_UIE_OFF:
358 0 : mutex_unlock(&rtc->ops_lock);
359 0 : return rtc_update_irq_enable(rtc, 0);
360 :
361 0 : case RTC_IRQP_SET:
362 0 : err = rtc_irq_set_freq(rtc, arg);
363 0 : break;
364 0 : case RTC_IRQP_READ:
365 0 : err = put_user(rtc->irq_freq, (unsigned long __user *)uarg);
366 0 : break;
367 :
368 0 : case RTC_WKALM_SET:
369 0 : mutex_unlock(&rtc->ops_lock);
370 0 : if (copy_from_user(&alarm, uarg, sizeof(alarm)))
371 : return -EFAULT;
372 :
373 0 : return rtc_set_alarm(rtc, &alarm);
374 :
375 0 : case RTC_WKALM_RD:
376 0 : mutex_unlock(&rtc->ops_lock);
377 0 : err = rtc_read_alarm(rtc, &alarm);
378 0 : if (err < 0)
379 0 : return err;
380 :
381 0 : if (copy_to_user(uarg, &alarm, sizeof(alarm)))
382 0 : err = -EFAULT;
383 0 : return err;
384 :
385 0 : default:
386 : /* Finally try the driver's ioctl interface */
387 0 : if (ops->ioctl) {
388 0 : err = ops->ioctl(rtc->dev.parent, cmd, arg);
389 0 : if (err == -ENOIOCTLCMD)
390 0 : err = -ENOTTY;
391 : } else {
392 : err = -ENOTTY;
393 : }
394 : break;
395 : }
396 :
397 0 : done:
398 0 : mutex_unlock(&rtc->ops_lock);
399 0 : return err;
400 : }
401 :
402 : #ifdef CONFIG_COMPAT
403 : #define RTC_IRQP_SET32 _IOW('p', 0x0c, __u32)
404 : #define RTC_IRQP_READ32 _IOR('p', 0x0b, __u32)
405 : #define RTC_EPOCH_SET32 _IOW('p', 0x0e, __u32)
406 :
407 0 : static long rtc_dev_compat_ioctl(struct file *file,
408 : unsigned int cmd, unsigned long arg)
409 : {
410 0 : struct rtc_device *rtc = file->private_data;
411 0 : void __user *uarg = compat_ptr(arg);
412 :
413 0 : switch (cmd) {
414 0 : case RTC_IRQP_READ32:
415 0 : return put_user(rtc->irq_freq, (__u32 __user *)uarg);
416 :
417 0 : case RTC_IRQP_SET32:
418 : /* arg is a plain integer, not pointer */
419 0 : return rtc_dev_ioctl(file, RTC_IRQP_SET, arg);
420 :
421 0 : case RTC_EPOCH_SET32:
422 : /* arg is a plain integer, not pointer */
423 0 : return rtc_dev_ioctl(file, RTC_EPOCH_SET, arg);
424 : }
425 :
426 0 : return rtc_dev_ioctl(file, cmd, (unsigned long)uarg);
427 : }
428 : #endif
429 :
430 0 : static int rtc_dev_fasync(int fd, struct file *file, int on)
431 : {
432 0 : struct rtc_device *rtc = file->private_data;
433 :
434 0 : return fasync_helper(fd, file, on, &rtc->async_queue);
435 : }
436 :
437 0 : static int rtc_dev_release(struct inode *inode, struct file *file)
438 : {
439 0 : struct rtc_device *rtc = file->private_data;
440 :
441 : /* We shut down the repeating IRQs that userspace enabled,
442 : * since nothing is listening to them.
443 : * - Update (UIE) ... currently only managed through ioctls
444 : * - Periodic (PIE) ... also used through rtc_*() interface calls
445 : *
446 : * Leave the alarm alone; it may be set to trigger a system wakeup
447 : * later, or be used by kernel code, and is a one-shot event anyway.
448 : */
449 :
450 : /* Keep ioctl until all drivers are converted */
451 0 : rtc_dev_ioctl(file, RTC_UIE_OFF, 0);
452 0 : rtc_update_irq_enable(rtc, 0);
453 0 : rtc_irq_set_state(rtc, 0);
454 :
455 0 : clear_bit_unlock(RTC_DEV_BUSY, &rtc->flags);
456 0 : return 0;
457 : }
458 :
459 : static const struct file_operations rtc_dev_fops = {
460 : .owner = THIS_MODULE,
461 : .llseek = no_llseek,
462 : .read = rtc_dev_read,
463 : .poll = rtc_dev_poll,
464 : .unlocked_ioctl = rtc_dev_ioctl,
465 : #ifdef CONFIG_COMPAT
466 : .compat_ioctl = rtc_dev_compat_ioctl,
467 : #endif
468 : .open = rtc_dev_open,
469 : .release = rtc_dev_release,
470 : .fasync = rtc_dev_fasync,
471 : };
472 :
473 : /* insertion/removal hooks */
474 :
475 0 : void rtc_dev_prepare(struct rtc_device *rtc)
476 : {
477 0 : if (!rtc_devt)
478 : return;
479 :
480 0 : if (rtc->id >= RTC_DEV_MAX) {
481 : dev_dbg(&rtc->dev, "too many RTC devices\n");
482 : return;
483 : }
484 :
485 0 : rtc->dev.devt = MKDEV(MAJOR(rtc_devt), rtc->id);
486 :
487 : #ifdef CONFIG_RTC_INTF_DEV_UIE_EMUL
488 : INIT_WORK(&rtc->uie_task, rtc_uie_task);
489 : timer_setup(&rtc->uie_timer, rtc_uie_timer, 0);
490 : #endif
491 :
492 0 : cdev_init(&rtc->char_dev, &rtc_dev_fops);
493 0 : rtc->char_dev.owner = rtc->owner;
494 : }
495 :
496 1 : void __init rtc_dev_init(void)
497 : {
498 1 : int err;
499 :
500 1 : err = alloc_chrdev_region(&rtc_devt, 0, RTC_DEV_MAX, "rtc");
501 1 : if (err < 0)
502 0 : pr_err("failed to allocate char dev region\n");
503 1 : }
504 :
505 0 : void __exit rtc_dev_exit(void)
506 : {
507 0 : if (rtc_devt)
508 0 : unregister_chrdev_region(rtc_devt, RTC_DEV_MAX);
509 0 : }
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