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
21static dev_t rtc_devt;
22
23#define RTC_DEV_MAX 16 /* 16 RTCs should be enough for everyone... */
24
25static 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 */
56static 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}
83static 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
96static 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
118static 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
140int 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}
147EXPORT_SYMBOL(rtc_dev_update_irq_enable_emul);
148
149#endif /* CONFIG_RTC_INTF_DEV_UIE_EMUL */
150
151static ssize_t
152rtc_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
206static 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
218static 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
412done:
413	mutex_unlock(&rtc->ops_lock);
414	return err;
415}
416
417static 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
423static 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
448static 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
461void 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
482void 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
492void rtc_dev_del_device(struct rtc_device *rtc)
493{
494	if (rtc->dev.devt)
495		cdev_del(&rtc->char_dev);
496}
497
498void __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
507void __exit rtc_dev_exit(void)
508{
509	if (rtc_devt)
510		unregister_chrdev_region(rtc_devt, RTC_DEV_MAX);
511}
512