summaryrefslogtreecommitdiffstats
path: root/drivers/char/ds1286.c
blob: ea35ab2c9909490bb490bb51eae47d39c31661b3 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
/*
 * DS1286 Real Time Clock interface for Linux
 *
 * Copyright (C) 1998, 1999, 2000 Ralf Baechle
 *
 * Based on code written by Paul Gortmaker.
 *
 * This driver allows use of the real time clock (built into nearly all
 * computers) from user space. It exports the /dev/rtc interface supporting
 * various ioctl() and also the /proc/rtc pseudo-file for status
 * information.
 *
 * The ioctls can be used to set the interrupt behaviour and generation rate
 * from the RTC via IRQ 8. Then the /dev/rtc interface can be used to make
 * use of these timer interrupts, be they interval or alarm based.
 *
 * The /dev/rtc interface will block on reads until an interrupt has been
 * received. If a RTC interrupt has already happened, it will output an
 * unsigned long and then block. The output value contains the interrupt
 * status in the low byte and the number of interrupts since the last read
 * in the remaining high bytes. The /dev/rtc interface can also be used with
 * the select(2) call.
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License as published by the
 * Free Software Foundation; either version 2 of the License, or (at your
 * option) any later version.
 */
#include <linux/ds1286.h>
#include <linux/types.h>
#include <linux/errno.h>
#include <linux/miscdevice.h>
#include <linux/slab.h>
#include <linux/ioport.h>
#include <linux/fcntl.h>
#include <linux/init.h>
#include <linux/poll.h>
#include <linux/rtc.h>
#include <linux/spinlock.h>
#include <linux/bcd.h>
#include <linux/proc_fs.h>
#include <linux/jiffies.h>

#include <asm/uaccess.h>
#include <asm/system.h>

#define DS1286_VERSION		"1.0"

/*
 *	We sponge a minor off of the misc major. No need slurping
 *	up another valuable major dev number for this. If you add
 *	an ioctl, make sure you don't conflict with SPARC's RTC
 *	ioctls.
 */

static DECLARE_WAIT_QUEUE_HEAD(ds1286_wait);

static ssize_t ds1286_read(struct file *file, char *buf,
			size_t count, loff_t *ppos);

static int ds1286_ioctl(struct inode *inode, struct file *file,
                        unsigned int cmd, unsigned long arg);

static unsigned int ds1286_poll(struct file *file, poll_table *wait);

static void ds1286_get_alm_time (struct rtc_time *alm_tm);
static void ds1286_get_time(struct rtc_time *rtc_tm);
static int ds1286_set_time(struct rtc_time *rtc_tm);

static inline unsigned char ds1286_is_updating(void);

static DEFINE_SPINLOCK(ds1286_lock);

static int ds1286_read_proc(char *page, char **start, off_t off,
                            int count, int *eof, void *data);

/*
 *	Bits in rtc_status. (7 bits of room for future expansion)
 */

#define RTC_IS_OPEN		0x01	/* means /dev/rtc is in use	*/
#define RTC_TIMER_ON		0x02	/* missed irq timer active	*/

static unsigned char ds1286_status;	/* bitmapped status byte.	*/

static unsigned char days_in_mo[] = {
	0, 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31
};

/*
 *	Now all the various file operations that we export.
 */

static ssize_t ds1286_read(struct file *file, char *buf,
                           size_t count, loff_t *ppos)
{
	return -EIO;
}

static int ds1286_ioctl(struct inode *inode, struct file *file,
                        unsigned int cmd, unsigned long arg)
{
	struct rtc_time wtime;

	switch (cmd) {
	case RTC_AIE_OFF:	/* Mask alarm int. enab. bit	*/
	{
		unsigned long flags;
		unsigned char val;

		if (!capable(CAP_SYS_TIME))
			return -EACCES;

		spin_lock_irqsave(&ds1286_lock, flags);
		val = rtc_read(RTC_CMD);
		val |=  RTC_TDM;
		rtc_write(val, RTC_CMD);
		spin_unlock_irqrestore(&ds1286_lock, flags);

		return 0;
	}
	case RTC_AIE_ON:	/* Allow alarm interrupts.	*/
	{
		unsigned long flags;
		unsigned char val;

		if (!capable(CAP_SYS_TIME))
			return -EACCES;

		spin_lock_irqsave(&ds1286_lock, flags);
		val = rtc_read(RTC_CMD);
		val &=  ~RTC_TDM;
		rtc_write(val, RTC_CMD);
		spin_unlock_irqrestore(&ds1286_lock, flags);

		return 0;
	}
	case RTC_WIE_OFF:	/* Mask watchdog int. enab. bit	*/
	{
		unsigned long flags;
		unsigned char val;

		if (!capable(CAP_SYS_TIME))
			return -EACCES;

		spin_lock_irqsave(&ds1286_lock, flags);
		val = rtc_read(RTC_CMD);
		val |= RTC_WAM;
		rtc_write(val, RTC_CMD);
		spin_unlock_irqrestore(&ds1286_lock, flags);

		return 0;
	}
	case RTC_WIE_ON:	/* Allow watchdog interrupts.	*/
	{
		unsigned long flags;
		unsigned char val;

		if (!capable(CAP_SYS_TIME))
			return -EACCES;

		spin_lock_irqsave(&ds1286_lock, flags);
		val = rtc_read(RTC_CMD);
		val &= ~RTC_WAM;
		rtc_write(val, RTC_CMD);
		spin_unlock_irqrestore(&ds1286_lock, flags);

		return 0;
	}
	case RTC_ALM_READ:	/* Read the present alarm time */
	{
		/*
		 * This returns a struct rtc_time. Reading >= 0xc0
		 * means "don't care" or "match all". Only the tm_hour,
		 * tm_min, and tm_sec values are filled in.
		 */

		memset(&wtime, 0, sizeof(wtime));
		ds1286_get_alm_time(&wtime);
		break;
	}
	case RTC_ALM_SET:	/* Store a time into the alarm */
	{
		/*
		 * This expects a struct rtc_time. Writing 0xff means
		 * "don't care" or "match all". Only the tm_hour,
		 * tm_min and tm_sec are used.
		 */
		unsigned char hrs, min, sec;
		struct rtc_time alm_tm;

		if (!capable(CAP_SYS_TIME))
			return -EACCES;

		if (copy_from_user(&alm_tm, (struct rtc_time*)arg,
				   sizeof(struct rtc_time)))
			return -EFAULT;

		hrs = alm_tm.tm_hour;
		min = alm_tm.tm_min;
		sec = alm_tm.tm_sec;

		if (hrs >= 24)
			hrs = 0xff;

		if (min >= 60)
			min = 0xff;

		if (sec != 0)
			return -EINVAL;

		min = BIN2BCD(min);
		min = BIN2BCD(hrs);

		spin_lock(&ds1286_lock);
		rtc_write(hrs, RTC_HOURS_ALARM);
		rtc_write(min, RTC_MINUTES_ALARM);
		spin_unlock(&ds1286_lock);

		return 0;
	}
	case RTC_RD_TIME:	/* Read the time/date from RTC	*/
	{
		memset(&wtime, 0, sizeof(wtime));
		ds1286_get_time(&wtime);
		break;
	}
	case RTC_SET_TIME:	/* Set the RTC */
	{
		struct rtc_time rtc_tm;

		if (!capable(CAP_SYS_TIME))
			return -EACCES;

		if (copy_from_user(&rtc_tm, (struct rtc_time*)arg,
				   sizeof(struct rtc_time)))
			return -EFAULT;

		return ds1286_set_time(&rtc_tm);
	}
	default:
		return -EINVAL;
	}
	return copy_to_user((void *)arg, &wtime, sizeof wtime) ? -EFAULT : 0;
}

/*
 *	We enforce only one user at a time here with the open/close.
 *	Also clear the previous interrupt data on an open, and clean
 *	up things on a close.
 */

static int ds1286_open(struct inode *inode, struct file *file)
{
	spin_lock_irq(&ds1286_lock);

	if (ds1286_status & RTC_IS_OPEN)
		goto out_busy;

	ds1286_status |= RTC_IS_OPEN;

	spin_unlock_irq(&ds1286_lock);
	return 0;

out_busy:
	spin_lock_irq(&ds1286_lock);
	return -EBUSY;
}

static int ds1286_release(struct inode *inode, struct file *file)
{
	ds1286_status &= ~RTC_IS_OPEN;

	return 0;
}

static unsigned int ds1286_poll(struct file *file, poll_table *wait)
{
	poll_wait(file, &ds1286_wait, wait);

	return 0;
}

/*
 *	The various file operations we support.
 */

static const struct file_operations ds1286_fops = {
	.llseek		= no_llseek,
	.read		= ds1286_read,
	.poll		= ds1286_poll,
	.ioctl		= ds1286_ioctl,
	.open		= ds1286_open,
	.release	= ds1286_release,
};

static struct miscdevice ds1286_dev=
{
	.minor	= RTC_MINOR,
	.name	= "rtc",
	.fops	= &ds1286_fops,
};

static int __init ds1286_init(void)
{
	int err;

	printk(KERN_INFO "DS1286 Real Time Clock Driver v%s\n", DS1286_VERSION);

	err = misc_register(&ds1286_dev);
	if (err)
		goto out;

	if (!create_proc_read_entry("driver/rtc", 0, 0, ds1286_read_proc, NULL)) {
		err = -ENOMEM;

		goto out_deregister;
	}

	return 0;

out_deregister:
	misc_deregister(&ds1286_dev);

out:
	return err;
}

static void __exit ds1286_exit(void)
{
	remove_proc_entry("driver/rtc", NULL);
	misc_deregister(&ds1286_dev);
}

static char *days[] = {
	"***", "Sun", "Mon", "Tue", "Wed", "Thu", "Fri", "Sat"
};

/*
 *	Info exported via "/proc/rtc".
 */
static int ds1286_proc_output(char *buf)
{
	char *p, *s;
	struct rtc_time tm;
	unsigned char hundredth, month, cmd, amode;

	p = buf;

	ds1286_get_time(&tm);
	hundredth = rtc_read(RTC_HUNDREDTH_SECOND);
	BCD_TO_BIN(hundredth);

	p += sprintf(p,
	             "rtc_time\t: %02d:%02d:%02d.%02d\n"
	             "rtc_date\t: %04d-%02d-%02d\n",
		     tm.tm_hour, tm.tm_min, tm.tm_sec, hundredth,
		     tm.tm_year + 1900, tm.tm_mon + 1, tm.tm_mday);

	/*
	 * We implicitly assume 24hr mode here. Alarm values >= 0xc0 will
	 * match any value for that particular field. Values that are
	 * greater than a valid time, but less than 0xc0 shouldn't appear.
	 */
	ds1286_get_alm_time(&tm);
	p += sprintf(p, "alarm\t\t: %s ", days[tm.tm_wday]);
	if (tm.tm_hour <= 24)
		p += sprintf(p, "%02d:", tm.tm_hour);
	else
		p += sprintf(p, "**:");

	if (tm.tm_min <= 59)
		p += sprintf(p, "%02d\n", tm.tm_min);
	else
		p += sprintf(p, "**\n");

	month = rtc_read(RTC_MONTH);
	p += sprintf(p,
	             "oscillator\t: %s\n"
	             "square_wave\t: %s\n",
	             (month & RTC_EOSC) ? "disabled" : "enabled",
	             (month & RTC_ESQW) ? "disabled" : "enabled");

	amode = ((rtc_read(RTC_MINUTES_ALARM) & 0x80) >> 5) |
	        ((rtc_read(RTC_HOURS_ALARM) & 0x80) >> 6) |
	        ((rtc_read(RTC_DAY_ALARM) & 0x80) >> 7);
	if (amode == 7)      s = "each minute";
	else if (amode == 3) s = "minutes match";
	else if (amode == 1) s = "hours and minutes match";
	else if (amode == 0) s = "days, hours and minutes match";
	else                 s = "invalid";
	p += sprintf(p, "alarm_mode\t: %s\n", s);

	cmd = rtc_read(RTC_CMD);
	p += sprintf(p,
	             "alarm_enable\t: %s\n"
	             "wdog_alarm\t: %s\n"
	             "alarm_mask\t: %s\n"
	             "wdog_alarm_mask\t: %s\n"
	             "interrupt_mode\t: %s\n"
	             "INTB_mode\t: %s_active\n"
	             "interrupt_pins\t: %s\n",
		     (cmd & RTC_TDF) ? "yes" : "no",
		     (cmd & RTC_WAF) ? "yes" : "no",
		     (cmd & RTC_TDM) ? "disabled" : "enabled",
		     (cmd & RTC_WAM) ? "disabled" : "enabled",
		     (cmd & RTC_PU_LVL) ? "pulse" : "level",
		     (cmd & RTC_IBH_LO) ? "low" : "high",
	             (cmd & RTC_IPSW) ? "unswapped" : "swapped");

	return  p - buf;
}

static int ds1286_read_proc(char *page, char **start, off_t off,
                         int count, int *eof, void *data)
{
	int len = ds1286_proc_output (page);
	if (len <= off+count) *eof = 1;
	*start = page + off;
	len -= off;
	if (len>count)
		len = count;
	if (len<0)
		len = 0;

	return len;
}

/*
 * Returns true if a clock update is in progress
 */
static inline unsigned char ds1286_is_updating(void)
{
	return rtc_read(RTC_CMD) & RTC_TE;
}


static void ds1286_get_time(struct rtc_time *rtc_tm)
{
	unsigned char save_control;
	unsigned long flags;
	unsigned long uip_watchdog = jiffies;

	/*
	 * read RTC once any update in progress is done. The update
	 * can take just over 2ms. We wait 10 to 20ms. There is no need to
	 * to poll-wait (up to 1s - eeccch) for the falling edge of RTC_UIP.
	 * If you need to know *exactly* when a second has started, enable
	 * periodic update complete interrupts, (via ioctl) and then
	 * immediately read /dev/rtc which will block until you get the IRQ.
	 * Once the read clears, read the RTC time (again via ioctl). Easy.
	 */

	if (ds1286_is_updating() != 0)
		while (time_before(jiffies, uip_watchdog + 2*HZ/100))
			barrier();

	/*
	 * Only the values that we read from the RTC are set. We leave
	 * tm_wday, tm_yday and tm_isdst untouched. Even though the
	 * RTC has RTC_DAY_OF_WEEK, we ignore it, as it is only updated
	 * by the RTC when initially set to a non-zero value.
	 */
	spin_lock_irqsave(&ds1286_lock, flags);
	save_control = rtc_read(RTC_CMD);
	rtc_write((save_control|RTC_TE), RTC_CMD);

	rtc_tm->tm_sec = rtc_read(RTC_SECONDS);
	rtc_tm->tm_min = rtc_read(RTC_MINUTES);
	rtc_tm->tm_hour = rtc_read(RTC_HOURS) & 0x3f;
	rtc_tm->tm_mday = rtc_read(RTC_DATE);
	rtc_tm->tm_mon = rtc_read(RTC_MONTH) & 0x1f;
	rtc_tm->tm_year = rtc_read(RTC_YEAR);

	rtc_write(save_control, RTC_CMD);
	spin_unlock_irqrestore(&ds1286_lock, flags);

	BCD_TO_BIN(rtc_tm->tm_sec);
	BCD_TO_BIN(rtc_tm->tm_min);
	BCD_TO_BIN(rtc_tm->tm_hour);
	BCD_TO_BIN(rtc_tm->tm_mday);
	BCD_TO_BIN(rtc_tm->tm_mon);
	BCD_TO_BIN(rtc_tm->tm_year);

	/*
	 * Account for differences between how the RTC uses the values
	 * and how they are defined in a struct rtc_time;
	 */
	if (rtc_tm->tm_year < 45)
		rtc_tm->tm_year += 30;
	if ((rtc_tm->tm_year += 40) < 70)
		rtc_tm->tm_year += 100;

	rtc_tm->tm_mon--;
}

static int ds1286_set_time(struct rtc_time *rtc_tm)
{
	unsigned char mon, day, hrs, min, sec, leap_yr;
	unsigned char save_control;
	unsigned int yrs;
	unsigned long flags;


	yrs = rtc_tm->tm_year + 1900;
	mon = rtc_tm->tm_mon + 1;   /* tm_mon starts at zero */
	day = rtc_tm->tm_mday;
	hrs = rtc_tm->tm_hour;
	min = rtc_tm->tm_min;
	sec = rtc_tm->tm_sec;

	if (yrs < 1970)
		return -EINVAL;

	leap_yr = ((!(yrs % 4) && (yrs % 100)) || !(yrs % 400));

	if ((mon > 12) || (day == 0))
		return -EINVAL;

	if (day > (days_in_mo[mon] + ((mon == 2) && leap_yr)))
		return -EINVAL;

	if ((hrs >= 24) || (min >= 60) || (sec >= 60))
		return -EINVAL;

	if ((yrs -= 1940) > 255)    /* They are unsigned */
		return -EINVAL;

	if (yrs >= 100)
		yrs -= 100;

	BIN_TO_BCD(sec);
	BIN_TO_BCD(min);
	BIN_TO_BCD(hrs);
	BIN_TO_BCD(day);
	BIN_TO_BCD(mon);
	BIN_TO_BCD(yrs);

	spin_lock_irqsave(&ds1286_lock, flags);
	save_control = rtc_read(RTC_CMD);
	rtc_write((save_control|RTC_TE), RTC_CMD);

	rtc_write(yrs, RTC_YEAR);
	rtc_write(mon, RTC_MONTH);
	rtc_write(day, RTC_DATE);
	rtc_write(hrs, RTC_HOURS);
	rtc_write(min, RTC_MINUTES);
	rtc_write(sec, RTC_SECONDS);
	rtc_write(0, RTC_HUNDREDTH_SECOND);

	rtc_write(save_control, RTC_CMD);
	spin_unlock_irqrestore(&ds1286_lock, flags);

	return 0;
}

static void ds1286_get_alm_time(struct rtc_time *alm_tm)
{
	unsigned char cmd;
	unsigned long flags;

	/*
	 * Only the values that we read from the RTC are set. That
	 * means only tm_wday, tm_hour, tm_min.
	 */
	spin_lock_irqsave(&ds1286_lock, flags);
	alm_tm->tm_min = rtc_read(RTC_MINUTES_ALARM) & 0x7f;
	alm_tm->tm_hour = rtc_read(RTC_HOURS_ALARM)  & 0x1f;
	alm_tm->tm_wday = rtc_read(RTC_DAY_ALARM)    & 0x07;
	cmd = rtc_read(RTC_CMD);
	spin_unlock_irqrestore(&ds1286_lock, flags);

	BCD_TO_BIN(alm_tm->tm_min);
	BCD_TO_BIN(alm_tm->tm_hour);
	alm_tm->tm_sec = 0;
}

module_init(ds1286_init);
module_exit(ds1286_exit);

MODULE_AUTHOR("Ralf Baechle");
MODULE_LICENSE("GPL");
MODULE_ALIAS_MISCDEV(RTC_MINOR);
OpenPOWER on IntegriCloud