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#include <linux/module.h>
15#include <linux/rtc.h>
16#include <linux/sched.h>
17#include "rtc-core.h"
18
19static dev_t rtc_devt;
20
21#define RTC_DEV_MAX 16 /* 16 RTCs should be enough for everyone... */
22
23static int rtc_dev_open(struct inode *inode, struct file *file)
24{
25	int err;
26	struct rtc_device *rtc = container_of(inode->i_cdev,
27					struct rtc_device, char_dev);
28	const struct rtc_class_ops *ops = rtc->ops;
29
30	if (test_and_set_bit_lock(RTC_DEV_BUSY, &rtc->flags))
31		return -EBUSY;
32
33	file->private_data = rtc;
34
35	err = ops->open ? ops->open(rtc->dev.parent) : 0;
36	if (err == 0) {
37		spin_lock_irq(&rtc->irq_lock);
38		rtc->irq_data = 0;
39		spin_unlock_irq(&rtc->irq_lock);
40
41		return 0;
42	}
43
44	/* something has gone wrong */
45	clear_bit_unlock(RTC_DEV_BUSY, &rtc->flags);
46	return err;
47}
48
49#ifdef CONFIG_RTC_INTF_DEV_UIE_EMUL
50/*
51 * Routine to poll RTC seconds field for change as often as possible,
52 * after first RTC_UIE use timer to reduce polling
53 */
54static void rtc_uie_task(struct work_struct *work)
55{
56	struct rtc_device *rtc =
57		container_of(work, struct rtc_device, uie_task);
58	struct rtc_time tm;
59	int num = 0;
60	int err;
61
62	err = rtc_read_time(rtc, &tm);
63
64	spin_lock_irq(&rtc->irq_lock);
65	if (rtc->stop_uie_polling || err) {
66		rtc->uie_task_active = 0;
67	} else if (rtc->oldsecs != tm.tm_sec) {
68		num = (tm.tm_sec + 60 - rtc->oldsecs) % 60;
69		rtc->oldsecs = tm.tm_sec;
70		rtc->uie_timer.expires = jiffies + HZ - (HZ/10);
71		rtc->uie_timer_active = 1;
72		rtc->uie_task_active = 0;
73		add_timer(&rtc->uie_timer);
74	} else if (schedule_work(&rtc->uie_task) == 0) {
75		rtc->uie_task_active = 0;
76	}
77	spin_unlock_irq(&rtc->irq_lock);
78	if (num)
79		rtc_handle_legacy_irq(rtc, num, RTC_UF);
80}
81static void rtc_uie_timer(unsigned long data)
82{
83	struct rtc_device *rtc = (struct rtc_device *)data;
84	unsigned long flags;
85
86	spin_lock_irqsave(&rtc->irq_lock, flags);
87	rtc->uie_timer_active = 0;
88	rtc->uie_task_active = 1;
89	if ((schedule_work(&rtc->uie_task) == 0))
90		rtc->uie_task_active = 0;
91	spin_unlock_irqrestore(&rtc->irq_lock, flags);
92}
93
94static int clear_uie(struct rtc_device *rtc)
95{
96	spin_lock_irq(&rtc->irq_lock);
97	if (rtc->uie_irq_active) {
98		rtc->stop_uie_polling = 1;
99		if (rtc->uie_timer_active) {
100			spin_unlock_irq(&rtc->irq_lock);
101			del_timer_sync(&rtc->uie_timer);
102			spin_lock_irq(&rtc->irq_lock);
103			rtc->uie_timer_active = 0;
104		}
105		if (rtc->uie_task_active) {
106			spin_unlock_irq(&rtc->irq_lock);
107			flush_scheduled_work();
108			spin_lock_irq(&rtc->irq_lock);
109		}
110		rtc->uie_irq_active = 0;
111	}
112	spin_unlock_irq(&rtc->irq_lock);
113	return 0;
114}
115
116static int set_uie(struct rtc_device *rtc)
117{
118	struct rtc_time tm;
119	int err;
120
121	err = rtc_read_time(rtc, &tm);
122	if (err)
123		return err;
124	spin_lock_irq(&rtc->irq_lock);
125	if (!rtc->uie_irq_active) {
126		rtc->uie_irq_active = 1;
127		rtc->stop_uie_polling = 0;
128		rtc->oldsecs = tm.tm_sec;
129		rtc->uie_task_active = 1;
130		if (schedule_work(&rtc->uie_task) == 0)
131			rtc->uie_task_active = 0;
132	}
133	rtc->irq_data = 0;
134	spin_unlock_irq(&rtc->irq_lock);
135	return 0;
136}
137
138int rtc_dev_update_irq_enable_emul(struct rtc_device *rtc, unsigned int enabled)
139{
140	if (enabled)
141		return set_uie(rtc);
142	else
143		return clear_uie(rtc);
144}
145EXPORT_SYMBOL(rtc_dev_update_irq_enable_emul);
146
147#endif /* CONFIG_RTC_INTF_DEV_UIE_EMUL */
148
149static ssize_t
150rtc_dev_read(struct file *file, char __user *buf, size_t count, loff_t *ppos)
151{
152	struct rtc_device *rtc = file->private_data;
153
154	DECLARE_WAITQUEUE(wait, current);
155	unsigned long data;
156	ssize_t ret;
157
158	if (count != sizeof(unsigned int) && count < sizeof(unsigned long))
159		return -EINVAL;
160
161	add_wait_queue(&rtc->irq_queue, &wait);
162	do {
163		__set_current_state(TASK_INTERRUPTIBLE);
164
165		spin_lock_irq(&rtc->irq_lock);
166		data = rtc->irq_data;
167		rtc->irq_data = 0;
168		spin_unlock_irq(&rtc->irq_lock);
169
170		if (data != 0) {
171			ret = 0;
172			break;
173		}
174		if (file->f_flags & O_NONBLOCK) {
175			ret = -EAGAIN;
176			break;
177		}
178		if (signal_pending(current)) {
179			ret = -ERESTARTSYS;
180			break;
181		}
182		schedule();
183	} while (1);
184	set_current_state(TASK_RUNNING);
185	remove_wait_queue(&rtc->irq_queue, &wait);
186
187	if (ret == 0) {
188		/* Check for any data updates */
189		if (rtc->ops->read_callback)
190			data = rtc->ops->read_callback(rtc->dev.parent,
191						       data);
192
193		if (sizeof(int) != sizeof(long) &&
194		    count == sizeof(unsigned int))
195			ret = put_user(data, (unsigned int __user *)buf) ?:
196				sizeof(unsigned int);
197		else
198			ret = put_user(data, (unsigned long __user *)buf) ?:
199				sizeof(unsigned long);
200	}
201	return ret;
202}
203
204static unsigned int rtc_dev_poll(struct file *file, poll_table *wait)
205{
206	struct rtc_device *rtc = file->private_data;
207	unsigned long data;
208
209	poll_wait(file, &rtc->irq_queue, wait);
210
211	data = rtc->irq_data;
212
213	return (data != 0) ? (POLLIN | POLLRDNORM) : 0;
214}
215
216static long rtc_dev_ioctl(struct file *file,
217		unsigned int cmd, unsigned long arg)
218{
219	int err = 0;
220	struct rtc_device *rtc = file->private_data;
221	const struct rtc_class_ops *ops = rtc->ops;
222	struct rtc_time tm;
223	struct rtc_wkalrm alarm;
224	void __user *uarg = (void __user *) arg;
225
226	err = mutex_lock_interruptible(&rtc->ops_lock);
227	if (err)
228		return err;
229
230	/* check that the calling task has appropriate permissions
231	 * for certain ioctls. doing this check here is useful
232	 * to avoid duplicate code in each driver.
233	 */
234	switch (cmd) {
235	case RTC_EPOCH_SET:
236	case RTC_SET_TIME:
237		if (!capable(CAP_SYS_TIME))
238			err = -EACCES;
239		break;
240
241	case RTC_IRQP_SET:
242		if (arg > rtc->max_user_freq && !capable(CAP_SYS_RESOURCE))
243			err = -EACCES;
244		break;
245
246	case RTC_PIE_ON:
247		if (rtc->irq_freq > rtc->max_user_freq &&
248				!capable(CAP_SYS_RESOURCE))
249			err = -EACCES;
250		break;
251	}
252
253	if (err)
254		goto done;
255
256	/*
257	 * Drivers *SHOULD NOT* provide ioctl implementations
258	 * for these requests.  Instead, provide methods to
259	 * support the following code, so that the RTC's main
260	 * features are accessible without using ioctls.
261	 *
262	 * RTC and alarm times will be in UTC, by preference,
263	 * but dual-booting with MS-Windows implies RTCs must
264	 * use the local wall clock time.
265	 */
266
267	switch (cmd) {
268	case RTC_ALM_READ:
269		mutex_unlock(&rtc->ops_lock);
270
271		err = rtc_read_alarm(rtc, &alarm);
272		if (err < 0)
273			return err;
274
275		if (copy_to_user(uarg, &alarm.time, sizeof(tm)))
276			err = -EFAULT;
277		return err;
278
279	case RTC_ALM_SET:
280		mutex_unlock(&rtc->ops_lock);
281
282		if (copy_from_user(&alarm.time, uarg, sizeof(tm)))
283			return -EFAULT;
284
285		alarm.enabled = 0;
286		alarm.pending = 0;
287		alarm.time.tm_wday = -1;
288		alarm.time.tm_yday = -1;
289		alarm.time.tm_isdst = -1;
290
291		/* RTC_ALM_SET alarms may be up to 24 hours in the future.
292		 * Rather than expecting every RTC to implement "don't care"
293		 * for day/month/year fields, just force the alarm to have
294		 * the right values for those fields.
295		 *
296		 * RTC_WKALM_SET should be used instead.  Not only does it
297		 * eliminate the need for a separate RTC_AIE_ON call, it
298		 * doesn't have the "alarm 23:59:59 in the future" race.
299		 *
300		 * NOTE:  some legacy code may have used invalid fields as
301		 * wildcards, exposing hardware "periodic alarm" capabilities.
302		 * Not supported here.
303		 */
304		{
305			unsigned long now, then;
306
307			err = rtc_read_time(rtc, &tm);
308			if (err < 0)
309				return err;
310			rtc_tm_to_time(&tm, &now);
311
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			err  = rtc_valid_tm(&alarm.time);
316			if (err < 0)
317				return err;
318			rtc_tm_to_time(&alarm.time, &then);
319
320			/* alarm may need to wrap into tomorrow */
321			if (then < now) {
322				rtc_time_to_tm(now + 24 * 60 * 60, &tm);
323				alarm.time.tm_mday = tm.tm_mday;
324				alarm.time.tm_mon = tm.tm_mon;
325				alarm.time.tm_year = tm.tm_year;
326			}
327		}
328
329		return rtc_set_alarm(rtc, &alarm);
330
331	case RTC_RD_TIME:
332		mutex_unlock(&rtc->ops_lock);
333
334		err = rtc_read_time(rtc, &tm);
335		if (err < 0)
336			return err;
337
338		if (copy_to_user(uarg, &tm, sizeof(tm)))
339			err = -EFAULT;
340		return err;
341
342	case RTC_SET_TIME:
343		mutex_unlock(&rtc->ops_lock);
344
345		if (copy_from_user(&tm, uarg, sizeof(tm)))
346			return -EFAULT;
347
348		return rtc_set_time(rtc, &tm);
349
350	case RTC_PIE_ON:
351		err = rtc_irq_set_state(rtc, NULL, 1);
352		break;
353
354	case RTC_PIE_OFF:
355		err = rtc_irq_set_state(rtc, NULL, 0);
356		break;
357
358	case RTC_AIE_ON:
359		mutex_unlock(&rtc->ops_lock);
360		return rtc_alarm_irq_enable(rtc, 1);
361
362	case RTC_AIE_OFF:
363		mutex_unlock(&rtc->ops_lock);
364		return rtc_alarm_irq_enable(rtc, 0);
365
366	case RTC_UIE_ON:
367		mutex_unlock(&rtc->ops_lock);
368		return rtc_update_irq_enable(rtc, 1);
369
370	case RTC_UIE_OFF:
371		mutex_unlock(&rtc->ops_lock);
372		return rtc_update_irq_enable(rtc, 0);
373
374	case RTC_IRQP_SET:
375		err = rtc_irq_set_freq(rtc, NULL, arg);
376		break;
377
378	case RTC_IRQP_READ:
379		err = put_user(rtc->irq_freq, (unsigned long __user *)uarg);
380		break;
381
382#if 0
383	case RTC_EPOCH_SET:
384#ifndef rtc_epoch
385		/*
386		 * There were no RTC clocks before 1900.
387		 */
388		if (arg < 1900) {
389			err = -EINVAL;
390			break;
391		}
392		rtc_epoch = arg;
393		err = 0;
394#endif
395		break;
396
397	case RTC_EPOCH_READ:
398		err = put_user(rtc_epoch, (unsigned long __user *)uarg);
399		break;
400#endif
401	case RTC_WKALM_SET:
402		mutex_unlock(&rtc->ops_lock);
403		if (copy_from_user(&alarm, uarg, sizeof(alarm)))
404			return -EFAULT;
405
406		return rtc_set_alarm(rtc, &alarm);
407
408	case RTC_WKALM_RD:
409		mutex_unlock(&rtc->ops_lock);
410		err = rtc_read_alarm(rtc, &alarm);
411		if (err < 0)
412			return err;
413
414		if (copy_to_user(uarg, &alarm, sizeof(alarm)))
415			err = -EFAULT;
416		return err;
417
418	default:
419		/* Finally try the driver's ioctl interface */
420		if (ops->ioctl) {
421			err = ops->ioctl(rtc->dev.parent, cmd, arg);
422			if (err == -ENOIOCTLCMD)
423				err = -ENOTTY;
424		} else
425			err = -ENOTTY;
426		break;
427	}
428
429done:
430	mutex_unlock(&rtc->ops_lock);
431	return err;
432}
433
434static int rtc_dev_fasync(int fd, struct file *file, int on)
435{
436	struct rtc_device *rtc = file->private_data;
437	return fasync_helper(fd, file, on, &rtc->async_queue);
438}
439
440static int rtc_dev_release(struct inode *inode, struct file *file)
441{
442	struct rtc_device *rtc = file->private_data;
443
444	/* We shut down the repeating IRQs that userspace enabled,
445	 * since nothing is listening to them.
446	 *  - Update (UIE) ... currently only managed through ioctls
447	 *  - Periodic (PIE) ... also used through rtc_*() interface calls
448	 *
449	 * Leave the alarm alone; it may be set to trigger a system wakeup
450	 * later, or be used by kernel code, and is a one-shot event anyway.
451	 */
452
453	/* Keep ioctl until all drivers are converted */
454	rtc_dev_ioctl(file, RTC_UIE_OFF, 0);
455	rtc_update_irq_enable(rtc, 0);
456	rtc_irq_set_state(rtc, NULL, 0);
457
458	if (rtc->ops->release)
459		rtc->ops->release(rtc->dev.parent);
460
461	clear_bit_unlock(RTC_DEV_BUSY, &rtc->flags);
462	return 0;
463}
464
465static const struct file_operations rtc_dev_fops = {
466	.owner		= THIS_MODULE,
467	.llseek		= no_llseek,
468	.read		= rtc_dev_read,
469	.poll		= rtc_dev_poll,
470	.unlocked_ioctl	= rtc_dev_ioctl,
471	.open		= rtc_dev_open,
472	.release	= rtc_dev_release,
473	.fasync		= rtc_dev_fasync,
474};
475
476/* insertion/removal hooks */
477
478void rtc_dev_prepare(struct rtc_device *rtc)
479{
480	if (!rtc_devt)
481		return;
482
483	if (rtc->id >= RTC_DEV_MAX) {
484		pr_debug("%s: too many RTC devices\n", rtc->name);
485		return;
486	}
487
488	rtc->dev.devt = MKDEV(MAJOR(rtc_devt), rtc->id);
489
490#ifdef CONFIG_RTC_INTF_DEV_UIE_EMUL
491	INIT_WORK(&rtc->uie_task, rtc_uie_task);
492	setup_timer(&rtc->uie_timer, rtc_uie_timer, (unsigned long)rtc);
493#endif
494
495	cdev_init(&rtc->char_dev, &rtc_dev_fops);
496	rtc->char_dev.owner = rtc->owner;
497}
498
499void rtc_dev_add_device(struct rtc_device *rtc)
500{
501	if (cdev_add(&rtc->char_dev, rtc->dev.devt, 1))
502		printk(KERN_WARNING "%s: failed to add char device %d:%d\n",
503			rtc->name, MAJOR(rtc_devt), rtc->id);
504	else
505		pr_debug("%s: dev (%d:%d)\n", rtc->name,
506			MAJOR(rtc_devt), rtc->id);
507}
508
509void rtc_dev_del_device(struct rtc_device *rtc)
510{
511	if (rtc->dev.devt)
512		cdev_del(&rtc->char_dev);
513}
514
515void __init rtc_dev_init(void)
516{
517	int err;
518
519	err = alloc_chrdev_region(&rtc_devt, 0, RTC_DEV_MAX, "rtc");
520	if (err < 0)
521		printk(KERN_ERR "%s: failed to allocate char dev region\n",
522			__FILE__);
523}
524
525void __exit rtc_dev_exit(void)
526{
527	if (rtc_devt)
528		unregister_chrdev_region(rtc_devt, RTC_DEV_MAX);
529}
530