2 * DS1286 Real Time Clock interface for Linux
4 * Copyright (C) 1998, 1999, 2000 Ralf Baechle
6 * Based on code written by Paul Gortmaker.
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
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.
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
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.
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 #include <linux/jiffies.h>
44 #include <asm/uaccess.h>
45 #include <asm/system.h>
47 #define DS1286_VERSION "1.0"
50 * We sponge a minor off of the misc major. No need slurping
51 * up another valuable major dev number for this. If you add
52 * an ioctl, make sure you don't conflict with SPARC's RTC
56 static DECLARE_WAIT_QUEUE_HEAD(ds1286_wait);
58 static ssize_t ds1286_read(struct file *file, char *buf,
59 size_t count, loff_t *ppos);
61 static int ds1286_ioctl(struct inode *inode, struct file *file,
62 unsigned int cmd, unsigned long arg);
64 static unsigned int ds1286_poll(struct file *file, poll_table *wait);
66 static void ds1286_get_alm_time (struct rtc_time *alm_tm);
67 static void ds1286_get_time(struct rtc_time *rtc_tm);
68 static int ds1286_set_time(struct rtc_time *rtc_tm);
70 static inline unsigned char ds1286_is_updating(void);
72 static DEFINE_SPINLOCK(ds1286_lock);
74 static int ds1286_read_proc(char *page, char **start, off_t off,
75 int count, int *eof, void *data);
78 * Bits in rtc_status. (7 bits of room for future expansion)
81 #define RTC_IS_OPEN 0x01 /* means /dev/rtc is in use */
82 #define RTC_TIMER_ON 0x02 /* missed irq timer active */
84 static unsigned char ds1286_status; /* bitmapped status byte. */
86 static unsigned char days_in_mo[] = {
87 0, 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31
91 * Now all the various file operations that we export.
94 static ssize_t ds1286_read(struct file *file, char *buf,
95 size_t count, loff_t *ppos)
100 static int ds1286_ioctl(struct inode *inode, struct file *file,
101 unsigned int cmd, unsigned long arg)
103 struct rtc_time wtime;
106 case RTC_AIE_OFF: /* Mask alarm int. enab. bit */
111 if (!capable(CAP_SYS_TIME))
114 spin_lock_irqsave(&ds1286_lock, flags);
115 val = rtc_read(RTC_CMD);
117 rtc_write(val, RTC_CMD);
118 spin_unlock_irqrestore(&ds1286_lock, flags);
122 case RTC_AIE_ON: /* Allow alarm interrupts. */
127 if (!capable(CAP_SYS_TIME))
130 spin_lock_irqsave(&ds1286_lock, flags);
131 val = rtc_read(RTC_CMD);
133 rtc_write(val, RTC_CMD);
134 spin_unlock_irqrestore(&ds1286_lock, flags);
138 case RTC_WIE_OFF: /* Mask watchdog int. enab. bit */
143 if (!capable(CAP_SYS_TIME))
146 spin_lock_irqsave(&ds1286_lock, flags);
147 val = rtc_read(RTC_CMD);
149 rtc_write(val, RTC_CMD);
150 spin_unlock_irqrestore(&ds1286_lock, flags);
154 case RTC_WIE_ON: /* Allow watchdog interrupts. */
159 if (!capable(CAP_SYS_TIME))
162 spin_lock_irqsave(&ds1286_lock, flags);
163 val = rtc_read(RTC_CMD);
165 rtc_write(val, RTC_CMD);
166 spin_unlock_irqrestore(&ds1286_lock, flags);
170 case RTC_ALM_READ: /* Read the present alarm time */
173 * This returns a struct rtc_time. Reading >= 0xc0
174 * means "don't care" or "match all". Only the tm_hour,
175 * tm_min, and tm_sec values are filled in.
178 memset(&wtime, 0, sizeof(wtime));
179 ds1286_get_alm_time(&wtime);
182 case RTC_ALM_SET: /* Store a time into the alarm */
185 * This expects a struct rtc_time. Writing 0xff means
186 * "don't care" or "match all". Only the tm_hour,
187 * tm_min and tm_sec are used.
189 unsigned char hrs, min, sec;
190 struct rtc_time alm_tm;
192 if (!capable(CAP_SYS_TIME))
195 if (copy_from_user(&alm_tm, (struct rtc_time*)arg,
196 sizeof(struct rtc_time)))
199 hrs = alm_tm.tm_hour;
215 spin_lock(&ds1286_lock);
216 rtc_write(hrs, RTC_HOURS_ALARM);
217 rtc_write(min, RTC_MINUTES_ALARM);
218 spin_unlock(&ds1286_lock);
222 case RTC_RD_TIME: /* Read the time/date from RTC */
224 memset(&wtime, 0, sizeof(wtime));
225 ds1286_get_time(&wtime);
228 case RTC_SET_TIME: /* Set the RTC */
230 struct rtc_time rtc_tm;
232 if (!capable(CAP_SYS_TIME))
235 if (copy_from_user(&rtc_tm, (struct rtc_time*)arg,
236 sizeof(struct rtc_time)))
239 return ds1286_set_time(&rtc_tm);
244 return copy_to_user((void *)arg, &wtime, sizeof wtime) ? -EFAULT : 0;
248 * We enforce only one user at a time here with the open/close.
249 * Also clear the previous interrupt data on an open, and clean
250 * up things on a close.
253 static int ds1286_open(struct inode *inode, struct file *file)
255 spin_lock_irq(&ds1286_lock);
257 if (ds1286_status & RTC_IS_OPEN)
260 ds1286_status |= RTC_IS_OPEN;
262 spin_unlock_irq(&ds1286_lock);
266 spin_lock_irq(&ds1286_lock);
270 static int ds1286_release(struct inode *inode, struct file *file)
272 ds1286_status &= ~RTC_IS_OPEN;
277 static unsigned int ds1286_poll(struct file *file, poll_table *wait)
279 poll_wait(file, &ds1286_wait, wait);
285 * The various file operations we support.
288 static const struct file_operations ds1286_fops = {
292 .ioctl = ds1286_ioctl,
294 .release = ds1286_release,
297 static struct miscdevice ds1286_dev=
301 .fops = &ds1286_fops,
304 static int __init ds1286_init(void)
308 printk(KERN_INFO "DS1286 Real Time Clock Driver v%s\n", DS1286_VERSION);
310 err = misc_register(&ds1286_dev);
314 if (!create_proc_read_entry("driver/rtc", 0, 0, ds1286_read_proc, NULL)) {
323 misc_deregister(&ds1286_dev);
329 static void __exit ds1286_exit(void)
331 remove_proc_entry("driver/rtc", NULL);
332 misc_deregister(&ds1286_dev);
335 static char *days[] = {
336 "***", "Sun", "Mon", "Tue", "Wed", "Thu", "Fri", "Sat"
340 * Info exported via "/proc/rtc".
342 static int ds1286_proc_output(char *buf)
346 unsigned char hundredth, month, cmd, amode;
350 ds1286_get_time(&tm);
351 hundredth = rtc_read(RTC_HUNDREDTH_SECOND);
352 BCD_TO_BIN(hundredth);
355 "rtc_time\t: %02d:%02d:%02d.%02d\n"
356 "rtc_date\t: %04d-%02d-%02d\n",
357 tm.tm_hour, tm.tm_min, tm.tm_sec, hundredth,
358 tm.tm_year + 1900, tm.tm_mon + 1, tm.tm_mday);
361 * We implicitly assume 24hr mode here. Alarm values >= 0xc0 will
362 * match any value for that particular field. Values that are
363 * greater than a valid time, but less than 0xc0 shouldn't appear.
365 ds1286_get_alm_time(&tm);
366 p += sprintf(p, "alarm\t\t: %s ", days[tm.tm_wday]);
367 if (tm.tm_hour <= 24)
368 p += sprintf(p, "%02d:", tm.tm_hour);
370 p += sprintf(p, "**:");
373 p += sprintf(p, "%02d\n", tm.tm_min);
375 p += sprintf(p, "**\n");
377 month = rtc_read(RTC_MONTH);
380 "square_wave\t: %s\n",
381 (month & RTC_EOSC) ? "disabled" : "enabled",
382 (month & RTC_ESQW) ? "disabled" : "enabled");
384 amode = ((rtc_read(RTC_MINUTES_ALARM) & 0x80) >> 5) |
385 ((rtc_read(RTC_HOURS_ALARM) & 0x80) >> 6) |
386 ((rtc_read(RTC_DAY_ALARM) & 0x80) >> 7);
387 if (amode == 7) s = "each minute";
388 else if (amode == 3) s = "minutes match";
389 else if (amode == 1) s = "hours and minutes match";
390 else if (amode == 0) s = "days, hours and minutes match";
392 p += sprintf(p, "alarm_mode\t: %s\n", s);
394 cmd = rtc_read(RTC_CMD);
396 "alarm_enable\t: %s\n"
399 "wdog_alarm_mask\t: %s\n"
400 "interrupt_mode\t: %s\n"
401 "INTB_mode\t: %s_active\n"
402 "interrupt_pins\t: %s\n",
403 (cmd & RTC_TDF) ? "yes" : "no",
404 (cmd & RTC_WAF) ? "yes" : "no",
405 (cmd & RTC_TDM) ? "disabled" : "enabled",
406 (cmd & RTC_WAM) ? "disabled" : "enabled",
407 (cmd & RTC_PU_LVL) ? "pulse" : "level",
408 (cmd & RTC_IBH_LO) ? "low" : "high",
409 (cmd & RTC_IPSW) ? "unswapped" : "swapped");
414 static int ds1286_read_proc(char *page, char **start, off_t off,
415 int count, int *eof, void *data)
417 int len = ds1286_proc_output (page);
418 if (len <= off+count) *eof = 1;
430 * Returns true if a clock update is in progress
432 static inline unsigned char ds1286_is_updating(void)
434 return rtc_read(RTC_CMD) & RTC_TE;
438 static void ds1286_get_time(struct rtc_time *rtc_tm)
440 unsigned char save_control;
442 unsigned long uip_watchdog = jiffies;
445 * read RTC once any update in progress is done. The update
446 * can take just over 2ms. We wait 10 to 20ms. There is no need to
447 * to poll-wait (up to 1s - eeccch) for the falling edge of RTC_UIP.
448 * If you need to know *exactly* when a second has started, enable
449 * periodic update complete interrupts, (via ioctl) and then
450 * immediately read /dev/rtc which will block until you get the IRQ.
451 * Once the read clears, read the RTC time (again via ioctl). Easy.
454 if (ds1286_is_updating() != 0)
455 while (time_before(jiffies, uip_watchdog + 2*HZ/100))
459 * Only the values that we read from the RTC are set. We leave
460 * tm_wday, tm_yday and tm_isdst untouched. Even though the
461 * RTC has RTC_DAY_OF_WEEK, we ignore it, as it is only updated
462 * by the RTC when initially set to a non-zero value.
464 spin_lock_irqsave(&ds1286_lock, flags);
465 save_control = rtc_read(RTC_CMD);
466 rtc_write((save_control|RTC_TE), RTC_CMD);
468 rtc_tm->tm_sec = rtc_read(RTC_SECONDS);
469 rtc_tm->tm_min = rtc_read(RTC_MINUTES);
470 rtc_tm->tm_hour = rtc_read(RTC_HOURS) & 0x3f;
471 rtc_tm->tm_mday = rtc_read(RTC_DATE);
472 rtc_tm->tm_mon = rtc_read(RTC_MONTH) & 0x1f;
473 rtc_tm->tm_year = rtc_read(RTC_YEAR);
475 rtc_write(save_control, RTC_CMD);
476 spin_unlock_irqrestore(&ds1286_lock, flags);
478 BCD_TO_BIN(rtc_tm->tm_sec);
479 BCD_TO_BIN(rtc_tm->tm_min);
480 BCD_TO_BIN(rtc_tm->tm_hour);
481 BCD_TO_BIN(rtc_tm->tm_mday);
482 BCD_TO_BIN(rtc_tm->tm_mon);
483 BCD_TO_BIN(rtc_tm->tm_year);
486 * Account for differences between how the RTC uses the values
487 * and how they are defined in a struct rtc_time;
489 if (rtc_tm->tm_year < 45)
490 rtc_tm->tm_year += 30;
491 if ((rtc_tm->tm_year += 40) < 70)
492 rtc_tm->tm_year += 100;
497 static int ds1286_set_time(struct rtc_time *rtc_tm)
499 unsigned char mon, day, hrs, min, sec, leap_yr;
500 unsigned char save_control;
505 yrs = rtc_tm->tm_year + 1900;
506 mon = rtc_tm->tm_mon + 1; /* tm_mon starts at zero */
507 day = rtc_tm->tm_mday;
508 hrs = rtc_tm->tm_hour;
509 min = rtc_tm->tm_min;
510 sec = rtc_tm->tm_sec;
515 leap_yr = ((!(yrs % 4) && (yrs % 100)) || !(yrs % 400));
517 if ((mon > 12) || (day == 0))
520 if (day > (days_in_mo[mon] + ((mon == 2) && leap_yr)))
523 if ((hrs >= 24) || (min >= 60) || (sec >= 60))
526 if ((yrs -= 1940) > 255) /* They are unsigned */
539 spin_lock_irqsave(&ds1286_lock, flags);
540 save_control = rtc_read(RTC_CMD);
541 rtc_write((save_control|RTC_TE), RTC_CMD);
543 rtc_write(yrs, RTC_YEAR);
544 rtc_write(mon, RTC_MONTH);
545 rtc_write(day, RTC_DATE);
546 rtc_write(hrs, RTC_HOURS);
547 rtc_write(min, RTC_MINUTES);
548 rtc_write(sec, RTC_SECONDS);
549 rtc_write(0, RTC_HUNDREDTH_SECOND);
551 rtc_write(save_control, RTC_CMD);
552 spin_unlock_irqrestore(&ds1286_lock, flags);
557 static void ds1286_get_alm_time(struct rtc_time *alm_tm)
563 * Only the values that we read from the RTC are set. That
564 * means only tm_wday, tm_hour, tm_min.
566 spin_lock_irqsave(&ds1286_lock, flags);
567 alm_tm->tm_min = rtc_read(RTC_MINUTES_ALARM) & 0x7f;
568 alm_tm->tm_hour = rtc_read(RTC_HOURS_ALARM) & 0x1f;
569 alm_tm->tm_wday = rtc_read(RTC_DAY_ALARM) & 0x07;
570 cmd = rtc_read(RTC_CMD);
571 spin_unlock_irqrestore(&ds1286_lock, flags);
573 BCD_TO_BIN(alm_tm->tm_min);
574 BCD_TO_BIN(alm_tm->tm_hour);
578 module_init(ds1286_init);
579 module_exit(ds1286_exit);
581 MODULE_AUTHOR("Ralf Baechle");
582 MODULE_LICENSE("GPL");
583 MODULE_ALIAS_MISCDEV(RTC_MINOR);