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
55 static DECLARE_WAIT_QUEUE_HEAD(ds1286_wait);
56
57 static ssize_t ds1286_read(struct file *file, char *buf,
58 size_t count, loff_t *ppos);
59
60 static int ds1286_ioctl(struct inode *inode, struct file *file,
61 unsigned int cmd, unsigned long arg);
62
63 static unsigned int ds1286_poll(struct file *file, poll_table *wait);
64
65 static void ds1286_get_alm_time (struct rtc_time *alm_tm);
66 static void ds1286_get_time(struct rtc_time *rtc_tm);
67 static int ds1286_set_time(struct rtc_time *rtc_tm);
68
69 static inline unsigned char ds1286_is_updating(void);
70
71 static DEFINE_SPINLOCK(ds1286_lock);
72
73 static 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
83 static unsigned char ds1286_status; /* bitmapped status byte. */
84
85 static 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
93 static ssize_t ds1286_read(struct file *file, char *buf,
94 size_t count, loff_t *ppos)
95 {
96 return -EIO;
97 }
98
99 static 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
252 static 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
264 out_busy:
265 spin_lock_irq(&ds1286_lock);
266 return -EBUSY;
267 }
268
269 static int ds1286_release(struct inode *inode, struct file *file)
270 {
271 ds1286_status &= ~RTC_IS_OPEN;
272
273 return 0;
274 }
275
276 static 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
287 static 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
296 static struct miscdevice ds1286_dev=
297 {
298 .minor = RTC_MINOR,
299 .name = "rtc",
300 .fops = &ds1286_fops,
301 };
302
303 static 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
321 out_deregister:
322 misc_deregister(&ds1286_dev);
323
324 out:
325 return err;
326 }
327
328 static void __exit ds1286_exit(void)
329 {
330 remove_proc_entry("driver/rtc", NULL);
331 misc_deregister(&ds1286_dev);
332 }
333
334 static char *days[] = {
335 "***", "Sun", "Mon", "Tue", "Wed", "Thu", "Fri", "Sat"
336 };
337
338 /*
339 * Info exported via "/proc/rtc".
340 */
341 static 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
413 static 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 */
431 static inline unsigned char ds1286_is_updating(void)
432 {
433 return rtc_read(RTC_CMD) & RTC_TE;
434 }
435
436
437 static 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
496 static 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
556 static 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
577 module_init(ds1286_init);
578 module_exit(ds1286_exit);
579
580 MODULE_AUTHOR("Ralf Baechle");
581 MODULE_LICENSE("GPL");
582 MODULE_ALIAS_MISCDEV(RTC_MINOR);
583
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