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/types.h>
30 #include <linux/errno.h>
31 #include <linux/miscdevice.h>
32 #include <linux/slab.h>
33 #include <linux/ioport.h>
34 #include <linux/fcntl.h>
35 #include <linux/init.h>
36 #include <linux/poll.h>
37 #include <linux/rtc.h>
38 #include <linux/spinlock.h>
40 #include <asm/ds1286.h>
42 #include <asm/uaccess.h>
43 #include <asm/system.h>
45 #define DS1286_VERSION "1.0"
48 * We sponge a minor off of the misc major. No need slurping
49 * up another valuable major dev number for this. If you add
50 * an ioctl, make sure you don't conflict with SPARC's RTC
54 static DECLARE_WAIT_QUEUE_HEAD(ds1286_wait);
56 static ssize_t ds1286_read(struct file *file, char *buf,
57 size_t count, loff_t *ppos);
59 static int ds1286_ioctl(struct inode *inode, struct file *file,
60 unsigned int cmd, unsigned long arg);
62 static unsigned int ds1286_poll(struct file *file, poll_table *wait);
64 void ds1286_get_alm_time (struct rtc_time *alm_tm);
65 void ds1286_get_time(struct rtc_time *rtc_tm);
66 int ds1286_set_time(struct rtc_time *rtc_tm);
68 void set_rtc_irq_bit(unsigned char bit);
69 void clear_rtc_irq_bit(unsigned char bit);
71 static inline unsigned char ds1286_is_updating(void);
73 static spinlock_t ds1286_lock = SPIN_LOCK_UNLOCKED;
76 * Bits in rtc_status. (7 bits of room for future expansion)
79 #define RTC_IS_OPEN 0x01 /* means /dev/rtc is in use */
80 #define RTC_TIMER_ON 0x02 /* missed irq timer active */
82 unsigned char ds1286_status; /* bitmapped status byte. */
83 unsigned long ds1286_freq; /* Current periodic IRQ rate */
85 unsigned char days_in_mo[] =
86 {0, 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31};
89 * Now all the various file operations that we export.
92 static ssize_t ds1286_read(struct file *file, char *buf,
93 size_t count, loff_t *ppos)
98 static int ds1286_ioctl(struct inode *inode, struct file *file,
99 unsigned int cmd, unsigned long arg)
102 struct rtc_time wtime;
105 case RTC_AIE_OFF: /* Mask alarm int. enab. bit */
110 if (!capable(CAP_SYS_TIME))
113 spin_lock_irqsave(&ds1286_lock, flags);
114 val = CMOS_READ(RTC_CMD);
116 CMOS_WRITE(val, RTC_CMD);
117 spin_unlock_irqrestore(&ds1286_lock, flags);
121 case RTC_AIE_ON: /* Allow alarm interrupts. */
126 if (!capable(CAP_SYS_TIME))
129 spin_lock_irqsave(&ds1286_lock, flags);
130 val = CMOS_READ(RTC_CMD);
132 CMOS_WRITE(val, RTC_CMD);
133 spin_unlock_irqrestore(&ds1286_lock, flags);
137 case RTC_WIE_OFF: /* Mask watchdog int. enab. bit */
142 if (!capable(CAP_SYS_TIME))
145 spin_lock_irqsave(&ds1286_lock, flags);
146 val = CMOS_READ(RTC_CMD);
148 CMOS_WRITE(val, RTC_CMD);
149 spin_unlock_irqrestore(&ds1286_lock, flags);
153 case RTC_WIE_ON: /* Allow watchdog interrupts. */
158 if (!capable(CAP_SYS_TIME))
161 spin_lock_irqsave(&ds1286_lock, flags);
162 val = CMOS_READ(RTC_CMD);
164 CMOS_WRITE(val, RTC_CMD);
165 spin_unlock_irqrestore(&ds1286_lock, flags);
169 case RTC_ALM_READ: /* Read the present alarm time */
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.
177 ds1286_get_alm_time(&wtime);
180 case RTC_ALM_SET: /* Store a time into the alarm */
183 * This expects a struct rtc_time. Writing 0xff means
184 * "don't care" or "match all". Only the tm_hour,
185 * tm_min and tm_sec are used.
187 unsigned char hrs, min, sec;
188 struct rtc_time alm_tm;
190 if (!capable(CAP_SYS_TIME))
193 if (copy_from_user(&alm_tm, (struct rtc_time*)arg,
194 sizeof(struct rtc_time)))
197 hrs = alm_tm.tm_hour;
210 spin_lock(&ds1286_lock);
211 CMOS_WRITE(hrs, RTC_HOURS_ALARM);
212 CMOS_WRITE(min, RTC_MINUTES_ALARM);
213 spin_unlock(&ds1286_lock);
217 case RTC_RD_TIME: /* Read the time/date from RTC */
219 ds1286_get_time(&wtime);
222 case RTC_SET_TIME: /* Set the RTC */
224 struct rtc_time rtc_tm;
226 if (!capable(CAP_SYS_TIME))
229 if (copy_from_user(&rtc_tm, (struct rtc_time*)arg,
230 sizeof(struct rtc_time)))
233 return ds1286_set_time(&rtc_tm);
238 return copy_to_user((void *)arg, &wtime, sizeof wtime) ? -EFAULT : 0;
242 * We enforce only one user at a time here with the open/close.
243 * Also clear the previous interrupt data on an open, and clean
244 * up things on a close.
247 static int ds1286_open(struct inode *inode, struct file *file)
249 spin_lock_irq(&ds1286_lock);
251 if (ds1286_status & RTC_IS_OPEN)
254 ds1286_status |= RTC_IS_OPEN;
256 spin_lock_irq(&ds1286_lock);
260 spin_lock_irq(&ds1286_lock);
264 static int ds1286_release(struct inode *inode, struct file *file)
266 ds1286_status &= ~RTC_IS_OPEN;
271 static unsigned int ds1286_poll(struct file *file, poll_table *wait)
273 poll_wait(file, &ds1286_wait, wait);
279 * The various file operations we support.
282 static struct file_operations ds1286_fops = {
288 release: ds1286_release,
291 static struct miscdevice ds1286_dev=
298 int __init ds1286_init(void)
300 printk(KERN_INFO "DS1286 Real Time Clock Driver v%s\n", DS1286_VERSION);
301 misc_register(&ds1286_dev);
306 static char *days[] = {
307 "***", "Sun", "Mon", "Tue", "Wed", "Thu", "Fri", "Sat"
311 * Info exported via "/proc/rtc".
313 int get_ds1286_status(char *buf)
317 unsigned char hundredth, month, cmd, amode;
321 ds1286_get_time(&tm);
322 hundredth = CMOS_READ(RTC_HUNDREDTH_SECOND);
323 BCD_TO_BIN(hundredth);
326 "rtc_time\t: %02d:%02d:%02d.%02d\n"
327 "rtc_date\t: %04d-%02d-%02d\n",
328 tm.tm_hour, tm.tm_min, tm.tm_sec, hundredth,
329 tm.tm_year + 1900, tm.tm_mon + 1, tm.tm_mday);
332 * We implicitly assume 24hr mode here. Alarm values >= 0xc0 will
333 * match any value for that particular field. Values that are
334 * greater than a valid time, but less than 0xc0 shouldn't appear.
336 ds1286_get_alm_time(&tm);
337 p += sprintf(p, "alarm\t\t: %s ", days[tm.tm_wday]);
338 if (tm.tm_hour <= 24)
339 p += sprintf(p, "%02d:", tm.tm_hour);
341 p += sprintf(p, "**:");
344 p += sprintf(p, "%02d\n", tm.tm_min);
346 p += sprintf(p, "**\n");
348 month = CMOS_READ(RTC_MONTH);
351 "square_wave\t: %s\n",
352 (month & RTC_EOSC) ? "disabled" : "enabled",
353 (month & RTC_ESQW) ? "disabled" : "enabled");
355 amode = ((CMOS_READ(RTC_MINUTES_ALARM) & 0x80) >> 5) |
356 ((CMOS_READ(RTC_HOURS_ALARM) & 0x80) >> 6) |
357 ((CMOS_READ(RTC_DAY_ALARM) & 0x80) >> 7);
358 if (amode == 7) s = "each minute";
359 else if (amode == 3) s = "minutes match";
360 else if (amode == 1) s = "hours and minutes match";
361 else if (amode == 0) s = "days, hours and minutes match";
363 p += sprintf(p, "alarm_mode\t: %s\n", s);
365 cmd = CMOS_READ(RTC_CMD);
367 "alarm_enable\t: %s\n"
370 "wdog_alarm_mask\t: %s\n"
371 "interrupt_mode\t: %s\n"
372 "INTB_mode\t: %s_active\n"
373 "interrupt_pins\t: %s\n",
374 (cmd & RTC_TDF) ? "yes" : "no",
375 (cmd & RTC_WAF) ? "yes" : "no",
376 (cmd & RTC_TDM) ? "disabled" : "enabled",
377 (cmd & RTC_WAM) ? "disabled" : "enabled",
378 (cmd & RTC_PU_LVL) ? "pulse" : "level",
379 (cmd & RTC_IBH_LO) ? "low" : "high",
380 (cmd & RTC_IPSW) ? "unswapped" : "swapped");
386 * Returns true if a clock update is in progress
388 static inline unsigned char ds1286_is_updating(void)
390 return CMOS_READ(RTC_CMD) & RTC_TE;
394 void ds1286_get_time(struct rtc_time *rtc_tm)
396 unsigned char save_control;
398 unsigned long uip_watchdog = jiffies;
401 * read RTC once any update in progress is done. The update
402 * can take just over 2ms. We wait 10 to 20ms. There is no need to
403 * to poll-wait (up to 1s - eeccch) for the falling edge of RTC_UIP.
404 * If you need to know *exactly* when a second has started, enable
405 * periodic update complete interrupts, (via ioctl) and then
406 * immediately read /dev/rtc which will block until you get the IRQ.
407 * Once the read clears, read the RTC time (again via ioctl). Easy.
410 if (ds1286_is_updating() != 0)
411 while (jiffies - uip_watchdog < 2*HZ/100)
415 * Only the values that we read from the RTC are set. We leave
416 * tm_wday, tm_yday and tm_isdst untouched. Even though the
417 * RTC has RTC_DAY_OF_WEEK, we ignore it, as it is only updated
418 * by the RTC when initially set to a non-zero value.
420 spin_lock_irqsave(&ds1286_lock, flags);
421 save_control = CMOS_READ(RTC_CMD);
422 CMOS_WRITE((save_control|RTC_TE), RTC_CMD);
424 rtc_tm->tm_sec = CMOS_READ(RTC_SECONDS);
425 rtc_tm->tm_min = CMOS_READ(RTC_MINUTES);
426 rtc_tm->tm_hour = CMOS_READ(RTC_HOURS) & 0x1f;
427 rtc_tm->tm_mday = CMOS_READ(RTC_DATE);
428 rtc_tm->tm_mon = CMOS_READ(RTC_MONTH) & 0x1f;
429 rtc_tm->tm_year = CMOS_READ(RTC_YEAR);
431 CMOS_WRITE(save_control, RTC_CMD);
432 spin_unlock_irqrestore(&ds1286_lock, flags);
434 BCD_TO_BIN(rtc_tm->tm_sec);
435 BCD_TO_BIN(rtc_tm->tm_min);
436 BCD_TO_BIN(rtc_tm->tm_hour);
437 BCD_TO_BIN(rtc_tm->tm_mday);
438 BCD_TO_BIN(rtc_tm->tm_mon);
439 BCD_TO_BIN(rtc_tm->tm_year);
442 * Account for differences between how the RTC uses the values
443 * and how they are defined in a struct rtc_time;
445 if (rtc_tm->tm_year < 45)
446 rtc_tm->tm_year += 30;
447 if ((rtc_tm->tm_year += 40) < 70)
448 rtc_tm->tm_year += 100;
453 int ds1286_set_time(struct rtc_time *rtc_tm)
455 unsigned char mon, day, hrs, min, sec, leap_yr;
456 unsigned char save_control;
457 unsigned int yrs, flags;
460 yrs = rtc_tm->tm_year + 1900;
461 mon = rtc_tm->tm_mon + 1; /* tm_mon starts at zero */
462 day = rtc_tm->tm_mday;
463 hrs = rtc_tm->tm_hour;
464 min = rtc_tm->tm_min;
465 sec = rtc_tm->tm_sec;
470 leap_yr = ((!(yrs % 4) && (yrs % 100)) || !(yrs % 400));
472 if ((mon > 12) || (day == 0))
475 if (day > (days_in_mo[mon] + ((mon == 2) && leap_yr)))
478 if ((hrs >= 24) || (min >= 60) || (sec >= 60))
481 if ((yrs -= 1940) > 255) /* They are unsigned */
494 spin_lock_irqsave(&ds1286_lock, flags);
495 save_control = CMOS_READ(RTC_CMD);
496 CMOS_WRITE((save_control|RTC_TE), RTC_CMD);
498 CMOS_WRITE(yrs, RTC_YEAR);
499 CMOS_WRITE(mon, RTC_MONTH);
500 CMOS_WRITE(day, RTC_DATE);
501 CMOS_WRITE(hrs, RTC_HOURS);
502 CMOS_WRITE(min, RTC_MINUTES);
503 CMOS_WRITE(sec, RTC_SECONDS);
504 CMOS_WRITE(0, RTC_HUNDREDTH_SECOND);
506 CMOS_WRITE(save_control, RTC_CMD);
507 spin_unlock_irqrestore(&ds1286_lock, flags);
512 void ds1286_get_alm_time(struct rtc_time *alm_tm)
518 * Only the values that we read from the RTC are set. That
519 * means only tm_wday, tm_hour, tm_min.
521 spin_lock_irqsave(&ds1286_lock, flags);
522 alm_tm->tm_min = CMOS_READ(RTC_MINUTES_ALARM) & 0x7f;
523 alm_tm->tm_hour = CMOS_READ(RTC_HOURS_ALARM) & 0x1f;
524 alm_tm->tm_wday = CMOS_READ(RTC_DAY_ALARM) & 0x07;
525 cmd = CMOS_READ(RTC_CMD);
526 spin_unlock_irqrestore(&ds1286_lock, flags);
528 BCD_TO_BIN(alm_tm->tm_min);
529 BCD_TO_BIN(alm_tm->tm_hour);