1/*
2 * DS1286 Real Time Clock interface for Linux
3 *
4 * Copyright (C) 1998, 1999, 2000 Ralf Baechle
5 *
6 * Based on code written by Paul Gortmaker.
7 *
8 * This driver allows use of the real time clock (built into nearly all
9 * computers) from user space. It exports the /dev/rtc interface supporting
10 * various ioctl() and also the /proc/rtc pseudo-file for status
11 * information.
12 *
13 * The ioctls can be used to set the interrupt behaviour and generation rate
14 * from the RTC via IRQ 8. Then the /dev/rtc interface can be used to make
15 * use of these timer interrupts, be they interval or alarm based.
16 *
17 * The /dev/rtc interface will block on reads until an interrupt has been
18 * received. If a RTC interrupt has already happened, it will output an
19 * unsigned long and then block. The output value contains the interrupt
20 * status in the low byte and the number of interrupts since the last read
21 * in the remaining high bytes. The /dev/rtc interface can also be used with
22 * the select(2) call.
23 *
24 * This program is free software; you can redistribute it and/or modify it
25 * under the terms of the GNU General Public License as published by the
26 * Free Software Foundation; either version 2 of the License, or (at your
27 * option) any later version.
28 */
29#include <linux/ds1286.h>
30#include <linux/types.h>
31#include <linux/errno.h>
32#include <linux/miscdevice.h>
33#include <linux/slab.h>
34#include <linux/ioport.h>
35#include <linux/fcntl.h>
36#include <linux/init.h>
37#include <linux/poll.h>
38#include <linux/rtc.h>
39#include <linux/spinlock.h>
40#include <linux/bcd.h>
41#include <linux/proc_fs.h>
42
43#include <asm/uaccess.h>
44#include <asm/system.h>
45
46#define DS1286_VERSION		"1.0"
47
48/*
49 *	We sponge a minor off of the misc major. No need slurping
50 *	up another valuable major dev number for this. If you add
51 *	an ioctl, make sure you don't conflict with SPARC's RTC
52 *	ioctls.
53 */
54
55static DECLARE_WAIT_QUEUE_HEAD(ds1286_wait);
56
57static ssize_t ds1286_read(struct file *file, char *buf,
58			size_t count, loff_t *ppos);
59
60static int ds1286_ioctl(struct inode *inode, struct file *file,
61                        unsigned int cmd, unsigned long arg);
62
63static unsigned int ds1286_poll(struct file *file, poll_table *wait);
64
65static void ds1286_get_alm_time (struct rtc_time *alm_tm);
66static void ds1286_get_time(struct rtc_time *rtc_tm);
67static int ds1286_set_time(struct rtc_time *rtc_tm);
68
69static inline unsigned char ds1286_is_updating(void);
70
71static DEFINE_SPINLOCK(ds1286_lock);
72
73static int ds1286_read_proc(char *page, char **start, off_t off,
74                            int count, int *eof, void *data);
75
76/*
77 *	Bits in rtc_status. (7 bits of room for future expansion)
78 */
79
80#define RTC_IS_OPEN		0x01	/* means /dev/rtc is in use	*/
81#define RTC_TIMER_ON		0x02	/* missed irq timer active	*/
82
83static unsigned char ds1286_status;	/* bitmapped status byte.	*/
84
85static unsigned char days_in_mo[] = {
86	0, 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31
87};
88
89/*
90 *	Now all the various file operations that we export.
91 */
92
93static ssize_t ds1286_read(struct file *file, char *buf,
94                           size_t count, loff_t *ppos)
95{
96	return -EIO;
97}
98
99static int ds1286_ioctl(struct inode *inode, struct file *file,
100                        unsigned int cmd, unsigned long arg)
101{
102	struct rtc_time wtime;
103
104	switch (cmd) {
105	case RTC_AIE_OFF:	/* Mask alarm int. enab. bit	*/
106	{
107		unsigned long flags;
108		unsigned char val;
109
110		if (!capable(CAP_SYS_TIME))
111			return -EACCES;
112
113		spin_lock_irqsave(&ds1286_lock, flags);
114		val = rtc_read(RTC_CMD);
115		val |=  RTC_TDM;
116		rtc_write(val, RTC_CMD);
117		spin_unlock_irqrestore(&ds1286_lock, flags);
118
119		return 0;
120	}
121	case RTC_AIE_ON:	/* Allow alarm interrupts.	*/
122	{
123		unsigned long flags;
124		unsigned char val;
125
126		if (!capable(CAP_SYS_TIME))
127			return -EACCES;
128
129		spin_lock_irqsave(&ds1286_lock, flags);
130		val = rtc_read(RTC_CMD);
131		val &=  ~RTC_TDM;
132		rtc_write(val, RTC_CMD);
133		spin_unlock_irqrestore(&ds1286_lock, flags);
134
135		return 0;
136	}
137	case RTC_WIE_OFF:	/* Mask watchdog int. enab. bit	*/
138	{
139		unsigned long flags;
140		unsigned char val;
141
142		if (!capable(CAP_SYS_TIME))
143			return -EACCES;
144
145		spin_lock_irqsave(&ds1286_lock, flags);
146		val = rtc_read(RTC_CMD);
147		val |= RTC_WAM;
148		rtc_write(val, RTC_CMD);
149		spin_unlock_irqrestore(&ds1286_lock, flags);
150
151		return 0;
152	}
153	case RTC_WIE_ON:	/* Allow watchdog interrupts.	*/
154	{
155		unsigned long flags;
156		unsigned char val;
157
158		if (!capable(CAP_SYS_TIME))
159			return -EACCES;
160
161		spin_lock_irqsave(&ds1286_lock, flags);
162		val = rtc_read(RTC_CMD);
163		val &= ~RTC_WAM;
164		rtc_write(val, RTC_CMD);
165		spin_unlock_irqrestore(&ds1286_lock, flags);
166
167		return 0;
168	}
169	case RTC_ALM_READ:	/* Read the present alarm time */
170	{
171		/*
172		 * This returns a struct rtc_time. Reading >= 0xc0
173		 * means "don't care" or "match all". Only the tm_hour,
174		 * tm_min, and tm_sec values are filled in.
175		 */
176
177		memset(&wtime, 0, sizeof(wtime));
178		ds1286_get_alm_time(&wtime);
179		break;
180	}
181	case RTC_ALM_SET:	/* Store a time into the alarm */
182	{
183		/*
184		 * This expects a struct rtc_time. Writing 0xff means
185		 * "don't care" or "match all". Only the tm_hour,
186		 * tm_min and tm_sec are used.
187		 */
188		unsigned char hrs, min, sec;
189		struct rtc_time alm_tm;
190
191		if (!capable(CAP_SYS_TIME))
192			return -EACCES;
193
194		if (copy_from_user(&alm_tm, (struct rtc_time*)arg,
195				   sizeof(struct rtc_time)))
196			return -EFAULT;
197
198		hrs = alm_tm.tm_hour;
199		min = alm_tm.tm_min;
200		sec = alm_tm.tm_sec;
201
202		if (hrs >= 24)
203			hrs = 0xff;
204
205		if (min >= 60)
206			min = 0xff;
207
208		if (sec != 0)
209			return -EINVAL;
210
211		min = BIN2BCD(min);
212		min = BIN2BCD(hrs);
213
214		spin_lock(&ds1286_lock);
215		rtc_write(hrs, RTC_HOURS_ALARM);
216		rtc_write(min, RTC_MINUTES_ALARM);
217		spin_unlock(&ds1286_lock);
218
219		return 0;
220	}
221	case RTC_RD_TIME:	/* Read the time/date from RTC	*/
222	{
223		memset(&wtime, 0, sizeof(wtime));
224		ds1286_get_time(&wtime);
225		break;
226	}
227	case RTC_SET_TIME:	/* Set the RTC */
228	{
229		struct rtc_time rtc_tm;
230
231		if (!capable(CAP_SYS_TIME))
232			return -EACCES;
233
234		if (copy_from_user(&rtc_tm, (struct rtc_time*)arg,
235				   sizeof(struct rtc_time)))
236			return -EFAULT;
237
238		return ds1286_set_time(&rtc_tm);
239	}
240	default:
241		return -EINVAL;
242	}
243	return copy_to_user((void *)arg, &wtime, sizeof wtime) ? -EFAULT : 0;
244}
245
246/*
247 *	We enforce only one user at a time here with the open/close.
248 *	Also clear the previous interrupt data on an open, and clean
249 *	up things on a close.
250 */
251
252static int ds1286_open(struct inode *inode, struct file *file)
253{
254	spin_lock_irq(&ds1286_lock);
255
256	if (ds1286_status & RTC_IS_OPEN)
257		goto out_busy;
258
259	ds1286_status |= RTC_IS_OPEN;
260
261	spin_unlock_irq(&ds1286_lock);
262	return 0;
263
264out_busy:
265	spin_lock_irq(&ds1286_lock);
266	return -EBUSY;
267}
268
269static int ds1286_release(struct inode *inode, struct file *file)
270{
271	ds1286_status &= ~RTC_IS_OPEN;
272
273	return 0;
274}
275
276static unsigned int ds1286_poll(struct file *file, poll_table *wait)
277{
278	poll_wait(file, &ds1286_wait, wait);
279
280	return 0;
281}
282
283/*
284 *	The various file operations we support.
285 */
286
287static const struct file_operations ds1286_fops = {
288	.llseek		= no_llseek,
289	.read		= ds1286_read,
290	.poll		= ds1286_poll,
291	.ioctl		= ds1286_ioctl,
292	.open		= ds1286_open,
293	.release	= ds1286_release,
294};
295
296static struct miscdevice ds1286_dev=
297{
298	.minor	= RTC_MINOR,
299	.name	= "rtc",
300	.fops	= &ds1286_fops,
301};
302
303static int __init ds1286_init(void)
304{
305	int err;
306
307	printk(KERN_INFO "DS1286 Real Time Clock Driver v%s\n", DS1286_VERSION);
308
309	err = misc_register(&ds1286_dev);
310	if (err)
311		goto out;
312
313	if (!create_proc_read_entry("driver/rtc", 0, 0, ds1286_read_proc, NULL)) {
314		err = -ENOMEM;
315
316		goto out_deregister;
317	}
318
319	return 0;
320
321out_deregister:
322	misc_deregister(&ds1286_dev);
323
324out:
325	return err;
326}
327
328static void __exit ds1286_exit(void)
329{
330	remove_proc_entry("driver/rtc", NULL);
331	misc_deregister(&ds1286_dev);
332}
333
334static char *days[] = {
335	"***", "Sun", "Mon", "Tue", "Wed", "Thu", "Fri", "Sat"
336};
337
338/*
339 *	Info exported via "/proc/rtc".
340 */
341static int ds1286_proc_output(char *buf)
342{
343	char *p, *s;
344	struct rtc_time tm;
345	unsigned char hundredth, month, cmd, amode;
346
347	p = buf;
348
349	ds1286_get_time(&tm);
350	hundredth = rtc_read(RTC_HUNDREDTH_SECOND);
351	BCD_TO_BIN(hundredth);
352
353	p += sprintf(p,
354	             "rtc_time\t: %02d:%02d:%02d.%02d\n"
355	             "rtc_date\t: %04d-%02d-%02d\n",
356		     tm.tm_hour, tm.tm_min, tm.tm_sec, hundredth,
357		     tm.tm_year + 1900, tm.tm_mon + 1, tm.tm_mday);
358
359	/*
360	 * We implicitly assume 24hr mode here. Alarm values >= 0xc0 will
361	 * match any value for that particular field. Values that are
362	 * greater than a valid time, but less than 0xc0 shouldn't appear.
363	 */
364	ds1286_get_alm_time(&tm);
365	p += sprintf(p, "alarm\t\t: %s ", days[tm.tm_wday]);
366	if (tm.tm_hour <= 24)
367		p += sprintf(p, "%02d:", tm.tm_hour);
368	else
369		p += sprintf(p, "**:");
370
371	if (tm.tm_min <= 59)
372		p += sprintf(p, "%02d\n", tm.tm_min);
373	else
374		p += sprintf(p, "**\n");
375
376	month = rtc_read(RTC_MONTH);
377	p += sprintf(p,
378	             "oscillator\t: %s\n"
379	             "square_wave\t: %s\n",
380	             (month & RTC_EOSC) ? "disabled" : "enabled",
381	             (month & RTC_ESQW) ? "disabled" : "enabled");
382
383	amode = ((rtc_read(RTC_MINUTES_ALARM) & 0x80) >> 5) |
384	        ((rtc_read(RTC_HOURS_ALARM) & 0x80) >> 6) |
385	        ((rtc_read(RTC_DAY_ALARM) & 0x80) >> 7);
386	if (amode == 7)      s = "each minute";
387	else if (amode == 3) s = "minutes match";
388	else if (amode == 1) s = "hours and minutes match";
389	else if (amode == 0) s = "days, hours and minutes match";
390	else                 s = "invalid";
391	p += sprintf(p, "alarm_mode\t: %s\n", s);
392
393	cmd = rtc_read(RTC_CMD);
394	p += sprintf(p,
395	             "alarm_enable\t: %s\n"
396	             "wdog_alarm\t: %s\n"
397	             "alarm_mask\t: %s\n"
398	             "wdog_alarm_mask\t: %s\n"
399	             "interrupt_mode\t: %s\n"
400	             "INTB_mode\t: %s_active\n"
401	             "interrupt_pins\t: %s\n",
402		     (cmd & RTC_TDF) ? "yes" : "no",
403		     (cmd & RTC_WAF) ? "yes" : "no",
404		     (cmd & RTC_TDM) ? "disabled" : "enabled",
405		     (cmd & RTC_WAM) ? "disabled" : "enabled",
406		     (cmd & RTC_PU_LVL) ? "pulse" : "level",
407		     (cmd & RTC_IBH_LO) ? "low" : "high",
408	             (cmd & RTC_IPSW) ? "unswapped" : "swapped");
409
410	return  p - buf;
411}
412
413static int ds1286_read_proc(char *page, char **start, off_t off,
414                         int count, int *eof, void *data)
415{
416	int len = ds1286_proc_output (page);
417	if (len <= off+count) *eof = 1;
418	*start = page + off;
419	len -= off;
420	if (len>count)
421		len = count;
422	if (len<0)
423		len = 0;
424
425	return len;
426}
427
428/*
429 * Returns true if a clock update is in progress
430 */
431static inline unsigned char ds1286_is_updating(void)
432{
433	return rtc_read(RTC_CMD) & RTC_TE;
434}
435
436
437static void ds1286_get_time(struct rtc_time *rtc_tm)
438{
439	unsigned char save_control;
440	unsigned long flags;
441	unsigned long uip_watchdog = jiffies;
442
443	/*
444	 * read RTC once any update in progress is done. The update
445	 * can take just over 2ms. We wait 10 to 20ms. There is no need to
446	 * to poll-wait (up to 1s - eeccch) for the falling edge of RTC_UIP.
447	 * If you need to know *exactly* when a second has started, enable
448	 * periodic update complete interrupts, (via ioctl) and then
449	 * immediately read /dev/rtc which will block until you get the IRQ.
450	 * Once the read clears, read the RTC time (again via ioctl). Easy.
451	 */
452
453	if (ds1286_is_updating() != 0)
454		while (jiffies - uip_watchdog < 2*HZ/100)
455			barrier();
456
457	/*
458	 * Only the values that we read from the RTC are set. We leave
459	 * tm_wday, tm_yday and tm_isdst untouched. Even though the
460	 * RTC has RTC_DAY_OF_WEEK, we ignore it, as it is only updated
461	 * by the RTC when initially set to a non-zero value.
462	 */
463	spin_lock_irqsave(&ds1286_lock, flags);
464	save_control = rtc_read(RTC_CMD);
465	rtc_write((save_control|RTC_TE), RTC_CMD);
466
467	rtc_tm->tm_sec = rtc_read(RTC_SECONDS);
468	rtc_tm->tm_min = rtc_read(RTC_MINUTES);
469	rtc_tm->tm_hour = rtc_read(RTC_HOURS) & 0x3f;
470	rtc_tm->tm_mday = rtc_read(RTC_DATE);
471	rtc_tm->tm_mon = rtc_read(RTC_MONTH) & 0x1f;
472	rtc_tm->tm_year = rtc_read(RTC_YEAR);
473
474	rtc_write(save_control, RTC_CMD);
475	spin_unlock_irqrestore(&ds1286_lock, flags);
476
477	BCD_TO_BIN(rtc_tm->tm_sec);
478	BCD_TO_BIN(rtc_tm->tm_min);
479	BCD_TO_BIN(rtc_tm->tm_hour);
480	BCD_TO_BIN(rtc_tm->tm_mday);
481	BCD_TO_BIN(rtc_tm->tm_mon);
482	BCD_TO_BIN(rtc_tm->tm_year);
483
484	/*
485	 * Account for differences between how the RTC uses the values
486	 * and how they are defined in a struct rtc_time;
487	 */
488	if (rtc_tm->tm_year < 45)
489		rtc_tm->tm_year += 30;
490	if ((rtc_tm->tm_year += 40) < 70)
491		rtc_tm->tm_year += 100;
492
493	rtc_tm->tm_mon--;
494}
495
496static int ds1286_set_time(struct rtc_time *rtc_tm)
497{
498	unsigned char mon, day, hrs, min, sec, leap_yr;
499	unsigned char save_control;
500	unsigned int yrs;
501	unsigned long flags;
502
503
504	yrs = rtc_tm->tm_year + 1900;
505	mon = rtc_tm->tm_mon + 1;   /* tm_mon starts at zero */
506	day = rtc_tm->tm_mday;
507	hrs = rtc_tm->tm_hour;
508	min = rtc_tm->tm_min;
509	sec = rtc_tm->tm_sec;
510
511	if (yrs < 1970)
512		return -EINVAL;
513
514	leap_yr = ((!(yrs % 4) && (yrs % 100)) || !(yrs % 400));
515
516	if ((mon > 12) || (day == 0))
517		return -EINVAL;
518
519	if (day > (days_in_mo[mon] + ((mon == 2) && leap_yr)))
520		return -EINVAL;
521
522	if ((hrs >= 24) || (min >= 60) || (sec >= 60))
523		return -EINVAL;
524
525	if ((yrs -= 1940) > 255)    /* They are unsigned */
526		return -EINVAL;
527
528	if (yrs >= 100)
529		yrs -= 100;
530
531	BIN_TO_BCD(sec);
532	BIN_TO_BCD(min);
533	BIN_TO_BCD(hrs);
534	BIN_TO_BCD(day);
535	BIN_TO_BCD(mon);
536	BIN_TO_BCD(yrs);
537
538	spin_lock_irqsave(&ds1286_lock, flags);
539	save_control = rtc_read(RTC_CMD);
540	rtc_write((save_control|RTC_TE), RTC_CMD);
541
542	rtc_write(yrs, RTC_YEAR);
543	rtc_write(mon, RTC_MONTH);
544	rtc_write(day, RTC_DATE);
545	rtc_write(hrs, RTC_HOURS);
546	rtc_write(min, RTC_MINUTES);
547	rtc_write(sec, RTC_SECONDS);
548	rtc_write(0, RTC_HUNDREDTH_SECOND);
549
550	rtc_write(save_control, RTC_CMD);
551	spin_unlock_irqrestore(&ds1286_lock, flags);
552
553	return 0;
554}
555
556static void ds1286_get_alm_time(struct rtc_time *alm_tm)
557{
558	unsigned char cmd;
559	unsigned long flags;
560
561	/*
562	 * Only the values that we read from the RTC are set. That
563	 * means only tm_wday, tm_hour, tm_min.
564	 */
565	spin_lock_irqsave(&ds1286_lock, flags);
566	alm_tm->tm_min = rtc_read(RTC_MINUTES_ALARM) & 0x7f;
567	alm_tm->tm_hour = rtc_read(RTC_HOURS_ALARM)  & 0x1f;
568	alm_tm->tm_wday = rtc_read(RTC_DAY_ALARM)    & 0x07;
569	cmd = rtc_read(RTC_CMD);
570	spin_unlock_irqrestore(&ds1286_lock, flags);
571
572	BCD_TO_BIN(alm_tm->tm_min);
573	BCD_TO_BIN(alm_tm->tm_hour);
574	alm_tm->tm_sec = 0;
575}
576
577module_init(ds1286_init);
578module_exit(ds1286_exit);
579
580MODULE_AUTHOR("Ralf Baechle");
581MODULE_LICENSE("GPL");
582MODULE_ALIAS_MISCDEV(RTC_MINOR);
583