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1// SPDX-License-Identifier: GPL-2.0-or-later
2/*
3 * Real Time Clock interface for Linux
4 *
5 * Copyright (C) 1996 Paul Gortmaker
6 *
7 * This driver allows use of the real time clock (built into
8 * nearly all computers) from user space. It exports the /dev/rtc
9 * interface supporting various ioctl() and also the
10 * /proc/driver/rtc pseudo-file for status information.
11 *
12 * The ioctls can be used to set the interrupt behaviour and
13 * generation rate from the RTC via IRQ 8. Then the /dev/rtc
14 * interface can be used to make use of these timer interrupts,
15 * be they interval or alarm based.
16 *
17 * The /dev/rtc interface will block on reads until an interrupt
18 * has been received. If a RTC interrupt has already happened,
19 * it will output an unsigned long and then block. The output value
20 * contains the interrupt status in the low byte and the number of
21 * interrupts since the last read in the remaining high bytes. The
22 * /dev/rtc interface can also be used with the select(2) call.
23 *
24 * Based on other minimal char device drivers, like Alan's
25 * watchdog, Ted's random, etc. etc.
26 *
27 * 1.07 Paul Gortmaker.
28 * 1.08 Miquel van Smoorenburg: disallow certain things on the
29 * DEC Alpha as the CMOS clock is also used for other things.
30 * 1.09 Nikita Schmidt: epoch support and some Alpha cleanup.
31 * 1.09a Pete Zaitcev: Sun SPARC
32 * 1.09b Jeff Garzik: Modularize, init cleanup
33 * 1.09c Jeff Garzik: SMP cleanup
34 * 1.10 Paul Barton-Davis: add support for async I/O
35 * 1.10a Andrea Arcangeli: Alpha updates
36 * 1.10b Andrew Morton: SMP lock fix
37 * 1.10c Cesar Barros: SMP locking fixes and cleanup
38 * 1.10d Paul Gortmaker: delete paranoia check in rtc_exit
39 * 1.10e Maciej W. Rozycki: Handle DECstation's year weirdness.
40 * 1.11 Takashi Iwai: Kernel access functions
41 * rtc_register/rtc_unregister/rtc_control
42 * 1.11a Daniele Bellucci: Audit create_proc_read_entry in rtc_init
43 * 1.12 Venkatesh Pallipadi: Hooks for emulating rtc on HPET base-timer
44 * CONFIG_HPET_EMULATE_RTC
45 * 1.12a Maciej W. Rozycki: Handle memory-mapped chips properly.
46 * 1.12ac Alan Cox: Allow read access to the day of week register
47 * 1.12b David John: Remove calls to the BKL.
48 */
49
50#define RTC_VERSION "1.12b"
51
52/*
53 * Note that *all* calls to CMOS_READ and CMOS_WRITE are done with
54 * interrupts disabled. Due to the index-port/data-port (0x70/0x71)
55 * design of the RTC, we don't want two different things trying to
56 * get to it at once. (e.g. the periodic 11 min sync from
57 * kernel/time/ntp.c vs. this driver.)
58 */
59
60#include <linux/interrupt.h>
61#include <linux/module.h>
62#include <linux/kernel.h>
63#include <linux/types.h>
64#include <linux/miscdevice.h>
65#include <linux/ioport.h>
66#include <linux/fcntl.h>
67#include <linux/mc146818rtc.h>
68#include <linux/init.h>
69#include <linux/poll.h>
70#include <linux/proc_fs.h>
71#include <linux/seq_file.h>
72#include <linux/spinlock.h>
73#include <linux/sched/signal.h>
74#include <linux/sysctl.h>
75#include <linux/wait.h>
76#include <linux/bcd.h>
77#include <linux/delay.h>
78#include <linux/uaccess.h>
79#include <linux/ratelimit.h>
80
81#include <asm/current.h>
82
83#ifdef CONFIG_X86
84#include <asm/hpet.h>
85#endif
86
87#ifdef CONFIG_SPARC32
88#include <linux/of.h>
89#include <linux/of_device.h>
90#include <asm/io.h>
91
92static unsigned long rtc_port;
93static int rtc_irq;
94#endif
95
96#ifdef CONFIG_HPET_EMULATE_RTC
97#undef RTC_IRQ
98#endif
99
100#ifdef RTC_IRQ
101static int rtc_has_irq = 1;
102#endif
103
104#ifndef CONFIG_HPET_EMULATE_RTC
105#define is_hpet_enabled() 0
106#define hpet_set_alarm_time(hrs, min, sec) 0
107#define hpet_set_periodic_freq(arg) 0
108#define hpet_mask_rtc_irq_bit(arg) 0
109#define hpet_set_rtc_irq_bit(arg) 0
110#define hpet_rtc_timer_init() do { } while (0)
111#define hpet_rtc_dropped_irq() 0
112#define hpet_register_irq_handler(h) ({ 0; })
113#define hpet_unregister_irq_handler(h) ({ 0; })
114#ifdef RTC_IRQ
115static irqreturn_t hpet_rtc_interrupt(int irq, void *dev_id)
116{
117 return 0;
118}
119#endif
120#endif
121
122/*
123 * We sponge a minor off of the misc major. No need slurping
124 * up another valuable major dev number for this. If you add
125 * an ioctl, make sure you don't conflict with SPARC's RTC
126 * ioctls.
127 */
128
129static struct fasync_struct *rtc_async_queue;
130
131static DECLARE_WAIT_QUEUE_HEAD(rtc_wait);
132
133#ifdef RTC_IRQ
134static void rtc_dropped_irq(struct timer_list *unused);
135
136static DEFINE_TIMER(rtc_irq_timer, rtc_dropped_irq);
137#endif
138
139static ssize_t rtc_read(struct file *file, char __user *buf,
140 size_t count, loff_t *ppos);
141
142static long rtc_ioctl(struct file *file, unsigned int cmd, unsigned long arg);
143static void rtc_get_rtc_time(struct rtc_time *rtc_tm);
144
145#ifdef RTC_IRQ
146static __poll_t rtc_poll(struct file *file, poll_table *wait);
147#endif
148
149static void get_rtc_alm_time(struct rtc_time *alm_tm);
150#ifdef RTC_IRQ
151static void set_rtc_irq_bit_locked(unsigned char bit);
152static void mask_rtc_irq_bit_locked(unsigned char bit);
153
154static inline void set_rtc_irq_bit(unsigned char bit)
155{
156 spin_lock_irq(&rtc_lock);
157 set_rtc_irq_bit_locked(bit);
158 spin_unlock_irq(&rtc_lock);
159}
160
161static void mask_rtc_irq_bit(unsigned char bit)
162{
163 spin_lock_irq(&rtc_lock);
164 mask_rtc_irq_bit_locked(bit);
165 spin_unlock_irq(&rtc_lock);
166}
167#endif
168
169#ifdef CONFIG_PROC_FS
170static int rtc_proc_show(struct seq_file *seq, void *v);
171#endif
172
173/*
174 * Bits in rtc_status. (6 bits of room for future expansion)
175 */
176
177#define RTC_IS_OPEN 0x01 /* means /dev/rtc is in use */
178#define RTC_TIMER_ON 0x02 /* missed irq timer active */
179
180/*
181 * rtc_status is never changed by rtc_interrupt, and ioctl/open/close is
182 * protected by the spin lock rtc_lock. However, ioctl can still disable the
183 * timer in rtc_status and then with del_timer after the interrupt has read
184 * rtc_status but before mod_timer is called, which would then reenable the
185 * timer (but you would need to have an awful timing before you'd trip on it)
186 */
187static unsigned long rtc_status; /* bitmapped status byte. */
188static unsigned long rtc_freq; /* Current periodic IRQ rate */
189static unsigned long rtc_irq_data; /* our output to the world */
190static unsigned long rtc_max_user_freq = 64; /* > this, need CAP_SYS_RESOURCE */
191
192/*
193 * If this driver ever becomes modularised, it will be really nice
194 * to make the epoch retain its value across module reload...
195 */
196
197static unsigned long epoch = 1900; /* year corresponding to 0x00 */
198
199static const unsigned char days_in_mo[] =
200{0, 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31};
201
202/*
203 * Returns true if a clock update is in progress
204 */
205static inline unsigned char rtc_is_updating(void)
206{
207 unsigned long flags;
208 unsigned char uip;
209
210 spin_lock_irqsave(&rtc_lock, flags);
211 uip = (CMOS_READ(RTC_FREQ_SELECT) & RTC_UIP);
212 spin_unlock_irqrestore(&rtc_lock, flags);
213 return uip;
214}
215
216#ifdef RTC_IRQ
217/*
218 * A very tiny interrupt handler. It runs with interrupts disabled,
219 * but there is possibility of conflicting with the set_rtc_mmss()
220 * call (the rtc irq and the timer irq can easily run at the same
221 * time in two different CPUs). So we need to serialize
222 * accesses to the chip with the rtc_lock spinlock that each
223 * architecture should implement in the timer code.
224 * (See ./arch/XXXX/kernel/time.c for the set_rtc_mmss() function.)
225 */
226
227static irqreturn_t rtc_interrupt(int irq, void *dev_id)
228{
229 /*
230 * Can be an alarm interrupt, update complete interrupt,
231 * or a periodic interrupt. We store the status in the
232 * low byte and the number of interrupts received since
233 * the last read in the remainder of rtc_irq_data.
234 */
235
236 spin_lock(&rtc_lock);
237 rtc_irq_data += 0x100;
238 rtc_irq_data &= ~0xff;
239 if (is_hpet_enabled()) {
240 /*
241 * In this case it is HPET RTC interrupt handler
242 * calling us, with the interrupt information
243 * passed as arg1, instead of irq.
244 */
245 rtc_irq_data |= (unsigned long)irq & 0xF0;
246 } else {
247 rtc_irq_data |= (CMOS_READ(RTC_INTR_FLAGS) & 0xF0);
248 }
249
250 if (rtc_status & RTC_TIMER_ON)
251 mod_timer(&rtc_irq_timer, jiffies + HZ/rtc_freq + 2*HZ/100);
252
253 spin_unlock(&rtc_lock);
254
255 wake_up_interruptible(&rtc_wait);
256
257 kill_fasync(&rtc_async_queue, SIGIO, POLL_IN);
258
259 return IRQ_HANDLED;
260}
261#endif
262
263/*
264 * sysctl-tuning infrastructure.
265 */
266static struct ctl_table rtc_table[] = {
267 {
268 .procname = "max-user-freq",
269 .data = &rtc_max_user_freq,
270 .maxlen = sizeof(int),
271 .mode = 0644,
272 .proc_handler = proc_dointvec,
273 },
274 { }
275};
276
277static struct ctl_table rtc_root[] = {
278 {
279 .procname = "rtc",
280 .mode = 0555,
281 .child = rtc_table,
282 },
283 { }
284};
285
286static struct ctl_table dev_root[] = {
287 {
288 .procname = "dev",
289 .mode = 0555,
290 .child = rtc_root,
291 },
292 { }
293};
294
295static struct ctl_table_header *sysctl_header;
296
297static int __init init_sysctl(void)
298{
299 sysctl_header = register_sysctl_table(dev_root);
300 return 0;
301}
302
303static void __exit cleanup_sysctl(void)
304{
305 unregister_sysctl_table(sysctl_header);
306}
307
308/*
309 * Now all the various file operations that we export.
310 */
311
312static ssize_t rtc_read(struct file *file, char __user *buf,
313 size_t count, loff_t *ppos)
314{
315#ifndef RTC_IRQ
316 return -EIO;
317#else
318 DECLARE_WAITQUEUE(wait, current);
319 unsigned long data;
320 ssize_t retval;
321
322 if (rtc_has_irq == 0)
323 return -EIO;
324
325 /*
326 * Historically this function used to assume that sizeof(unsigned long)
327 * is the same in userspace and kernelspace. This lead to problems
328 * for configurations with multiple ABIs such a the MIPS o32 and 64
329 * ABIs supported on the same kernel. So now we support read of both
330 * 4 and 8 bytes and assume that's the sizeof(unsigned long) in the
331 * userspace ABI.
332 */
333 if (count != sizeof(unsigned int) && count != sizeof(unsigned long))
334 return -EINVAL;
335
336 add_wait_queue(&rtc_wait, &wait);
337
338 do {
339 /* First make it right. Then make it fast. Putting this whole
340 * block within the parentheses of a while would be too
341 * confusing. And no, xchg() is not the answer. */
342
343 __set_current_state(TASK_INTERRUPTIBLE);
344
345 spin_lock_irq(&rtc_lock);
346 data = rtc_irq_data;
347 rtc_irq_data = 0;
348 spin_unlock_irq(&rtc_lock);
349
350 if (data != 0)
351 break;
352
353 if (file->f_flags & O_NONBLOCK) {
354 retval = -EAGAIN;
355 goto out;
356 }
357 if (signal_pending(current)) {
358 retval = -ERESTARTSYS;
359 goto out;
360 }
361 schedule();
362 } while (1);
363
364 if (count == sizeof(unsigned int)) {
365 retval = put_user(data,
366 (unsigned int __user *)buf) ?: sizeof(int);
367 } else {
368 retval = put_user(data,
369 (unsigned long __user *)buf) ?: sizeof(long);
370 }
371 if (!retval)
372 retval = count;
373 out:
374 __set_current_state(TASK_RUNNING);
375 remove_wait_queue(&rtc_wait, &wait);
376
377 return retval;
378#endif
379}
380
381static int rtc_do_ioctl(unsigned int cmd, unsigned long arg, int kernel)
382{
383 struct rtc_time wtime;
384
385#ifdef RTC_IRQ
386 if (rtc_has_irq == 0) {
387 switch (cmd) {
388 case RTC_AIE_OFF:
389 case RTC_AIE_ON:
390 case RTC_PIE_OFF:
391 case RTC_PIE_ON:
392 case RTC_UIE_OFF:
393 case RTC_UIE_ON:
394 case RTC_IRQP_READ:
395 case RTC_IRQP_SET:
396 return -EINVAL;
397 }
398 }
399#endif
400
401 switch (cmd) {
402#ifdef RTC_IRQ
403 case RTC_AIE_OFF: /* Mask alarm int. enab. bit */
404 {
405 mask_rtc_irq_bit(RTC_AIE);
406 return 0;
407 }
408 case RTC_AIE_ON: /* Allow alarm interrupts. */
409 {
410 set_rtc_irq_bit(RTC_AIE);
411 return 0;
412 }
413 case RTC_PIE_OFF: /* Mask periodic int. enab. bit */
414 {
415 /* can be called from isr via rtc_control() */
416 unsigned long flags;
417
418 spin_lock_irqsave(&rtc_lock, flags);
419 mask_rtc_irq_bit_locked(RTC_PIE);
420 if (rtc_status & RTC_TIMER_ON) {
421 rtc_status &= ~RTC_TIMER_ON;
422 del_timer(&rtc_irq_timer);
423 }
424 spin_unlock_irqrestore(&rtc_lock, flags);
425
426 return 0;
427 }
428 case RTC_PIE_ON: /* Allow periodic ints */
429 {
430 /* can be called from isr via rtc_control() */
431 unsigned long flags;
432
433 /*
434 * We don't really want Joe User enabling more
435 * than 64Hz of interrupts on a multi-user machine.
436 */
437 if (!kernel && (rtc_freq > rtc_max_user_freq) &&
438 (!capable(CAP_SYS_RESOURCE)))
439 return -EACCES;
440
441 spin_lock_irqsave(&rtc_lock, flags);
442 if (!(rtc_status & RTC_TIMER_ON)) {
443 mod_timer(&rtc_irq_timer, jiffies + HZ/rtc_freq +
444 2*HZ/100);
445 rtc_status |= RTC_TIMER_ON;
446 }
447 set_rtc_irq_bit_locked(RTC_PIE);
448 spin_unlock_irqrestore(&rtc_lock, flags);
449
450 return 0;
451 }
452 case RTC_UIE_OFF: /* Mask ints from RTC updates. */
453 {
454 mask_rtc_irq_bit(RTC_UIE);
455 return 0;
456 }
457 case RTC_UIE_ON: /* Allow ints for RTC updates. */
458 {
459 set_rtc_irq_bit(RTC_UIE);
460 return 0;
461 }
462#endif
463 case RTC_ALM_READ: /* Read the present alarm time */
464 {
465 /*
466 * This returns a struct rtc_time. Reading >= 0xc0
467 * means "don't care" or "match all". Only the tm_hour,
468 * tm_min, and tm_sec values are filled in.
469 */
470 memset(&wtime, 0, sizeof(struct rtc_time));
471 get_rtc_alm_time(&wtime);
472 break;
473 }
474 case RTC_ALM_SET: /* Store a time into the alarm */
475 {
476 /*
477 * This expects a struct rtc_time. Writing 0xff means
478 * "don't care" or "match all". Only the tm_hour,
479 * tm_min and tm_sec are used.
480 */
481 unsigned char hrs, min, sec;
482 struct rtc_time alm_tm;
483
484 if (copy_from_user(&alm_tm, (struct rtc_time __user *)arg,
485 sizeof(struct rtc_time)))
486 return -EFAULT;
487
488 hrs = alm_tm.tm_hour;
489 min = alm_tm.tm_min;
490 sec = alm_tm.tm_sec;
491
492 spin_lock_irq(&rtc_lock);
493 if (hpet_set_alarm_time(hrs, min, sec)) {
494 /*
495 * Fallthru and set alarm time in CMOS too,
496 * so that we will get proper value in RTC_ALM_READ
497 */
498 }
499 if (!(CMOS_READ(RTC_CONTROL) & RTC_DM_BINARY) ||
500 RTC_ALWAYS_BCD) {
501 if (sec < 60)
502 sec = bin2bcd(sec);
503 else
504 sec = 0xff;
505
506 if (min < 60)
507 min = bin2bcd(min);
508 else
509 min = 0xff;
510
511 if (hrs < 24)
512 hrs = bin2bcd(hrs);
513 else
514 hrs = 0xff;
515 }
516 CMOS_WRITE(hrs, RTC_HOURS_ALARM);
517 CMOS_WRITE(min, RTC_MINUTES_ALARM);
518 CMOS_WRITE(sec, RTC_SECONDS_ALARM);
519 spin_unlock_irq(&rtc_lock);
520
521 return 0;
522 }
523 case RTC_RD_TIME: /* Read the time/date from RTC */
524 {
525 memset(&wtime, 0, sizeof(struct rtc_time));
526 rtc_get_rtc_time(&wtime);
527 break;
528 }
529 case RTC_SET_TIME: /* Set the RTC */
530 {
531 struct rtc_time rtc_tm;
532 unsigned char mon, day, hrs, min, sec, leap_yr;
533 unsigned char save_control, save_freq_select;
534 unsigned int yrs;
535#ifdef CONFIG_MACH_DECSTATION
536 unsigned int real_yrs;
537#endif
538
539 if (!capable(CAP_SYS_TIME))
540 return -EACCES;
541
542 if (copy_from_user(&rtc_tm, (struct rtc_time __user *)arg,
543 sizeof(struct rtc_time)))
544 return -EFAULT;
545
546 yrs = rtc_tm.tm_year + 1900;
547 mon = rtc_tm.tm_mon + 1; /* tm_mon starts at zero */
548 day = rtc_tm.tm_mday;
549 hrs = rtc_tm.tm_hour;
550 min = rtc_tm.tm_min;
551 sec = rtc_tm.tm_sec;
552
553 if (yrs < 1970)
554 return -EINVAL;
555
556 leap_yr = ((!(yrs % 4) && (yrs % 100)) || !(yrs % 400));
557
558 if ((mon > 12) || (day == 0))
559 return -EINVAL;
560
561 if (day > (days_in_mo[mon] + ((mon == 2) && leap_yr)))
562 return -EINVAL;
563
564 if ((hrs >= 24) || (min >= 60) || (sec >= 60))
565 return -EINVAL;
566
567 yrs -= epoch;
568 if (yrs > 255) /* They are unsigned */
569 return -EINVAL;
570
571 spin_lock_irq(&rtc_lock);
572#ifdef CONFIG_MACH_DECSTATION
573 real_yrs = yrs;
574 yrs = 72;
575
576 /*
577 * We want to keep the year set to 73 until March
578 * for non-leap years, so that Feb, 29th is handled
579 * correctly.
580 */
581 if (!leap_yr && mon < 3) {
582 real_yrs--;
583 yrs = 73;
584 }
585#endif
586 /* These limits and adjustments are independent of
587 * whether the chip is in binary mode or not.
588 */
589 if (yrs > 169) {
590 spin_unlock_irq(&rtc_lock);
591 return -EINVAL;
592 }
593 if (yrs >= 100)
594 yrs -= 100;
595
596 if (!(CMOS_READ(RTC_CONTROL) & RTC_DM_BINARY)
597 || RTC_ALWAYS_BCD) {
598 sec = bin2bcd(sec);
599 min = bin2bcd(min);
600 hrs = bin2bcd(hrs);
601 day = bin2bcd(day);
602 mon = bin2bcd(mon);
603 yrs = bin2bcd(yrs);
604 }
605
606 save_control = CMOS_READ(RTC_CONTROL);
607 CMOS_WRITE((save_control|RTC_SET), RTC_CONTROL);
608 save_freq_select = CMOS_READ(RTC_FREQ_SELECT);
609 CMOS_WRITE((save_freq_select|RTC_DIV_RESET2), RTC_FREQ_SELECT);
610
611#ifdef CONFIG_MACH_DECSTATION
612 CMOS_WRITE(real_yrs, RTC_DEC_YEAR);
613#endif
614 CMOS_WRITE(yrs, RTC_YEAR);
615 CMOS_WRITE(mon, RTC_MONTH);
616 CMOS_WRITE(day, RTC_DAY_OF_MONTH);
617 CMOS_WRITE(hrs, RTC_HOURS);
618 CMOS_WRITE(min, RTC_MINUTES);
619 CMOS_WRITE(sec, RTC_SECONDS);
620
621 CMOS_WRITE(save_control, RTC_CONTROL);
622 CMOS_WRITE(save_freq_select, RTC_FREQ_SELECT);
623
624 spin_unlock_irq(&rtc_lock);
625 return 0;
626 }
627#ifdef RTC_IRQ
628 case RTC_IRQP_READ: /* Read the periodic IRQ rate. */
629 {
630 return put_user(rtc_freq, (unsigned long __user *)arg);
631 }
632 case RTC_IRQP_SET: /* Set periodic IRQ rate. */
633 {
634 int tmp = 0;
635 unsigned char val;
636 /* can be called from isr via rtc_control() */
637 unsigned long flags;
638
639 /*
640 * The max we can do is 8192Hz.
641 */
642 if ((arg < 2) || (arg > 8192))
643 return -EINVAL;
644 /*
645 * We don't really want Joe User generating more
646 * than 64Hz of interrupts on a multi-user machine.
647 */
648 if (!kernel && (arg > rtc_max_user_freq) &&
649 !capable(CAP_SYS_RESOURCE))
650 return -EACCES;
651
652 while (arg > (1<<tmp))
653 tmp++;
654
655 /*
656 * Check that the input was really a power of 2.
657 */
658 if (arg != (1<<tmp))
659 return -EINVAL;
660
661 rtc_freq = arg;
662
663 spin_lock_irqsave(&rtc_lock, flags);
664 if (hpet_set_periodic_freq(arg)) {
665 spin_unlock_irqrestore(&rtc_lock, flags);
666 return 0;
667 }
668
669 val = CMOS_READ(RTC_FREQ_SELECT) & 0xf0;
670 val |= (16 - tmp);
671 CMOS_WRITE(val, RTC_FREQ_SELECT);
672 spin_unlock_irqrestore(&rtc_lock, flags);
673 return 0;
674 }
675#endif
676 case RTC_EPOCH_READ: /* Read the epoch. */
677 {
678 return put_user(epoch, (unsigned long __user *)arg);
679 }
680 case RTC_EPOCH_SET: /* Set the epoch. */
681 {
682 /*
683 * There were no RTC clocks before 1900.
684 */
685 if (arg < 1900)
686 return -EINVAL;
687
688 if (!capable(CAP_SYS_TIME))
689 return -EACCES;
690
691 epoch = arg;
692 return 0;
693 }
694 default:
695 return -ENOTTY;
696 }
697 return copy_to_user((void __user *)arg,
698 &wtime, sizeof wtime) ? -EFAULT : 0;
699}
700
701static long rtc_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
702{
703 long ret;
704 ret = rtc_do_ioctl(cmd, arg, 0);
705 return ret;
706}
707
708/*
709 * We enforce only one user at a time here with the open/close.
710 * Also clear the previous interrupt data on an open, and clean
711 * up things on a close.
712 */
713static int rtc_open(struct inode *inode, struct file *file)
714{
715 spin_lock_irq(&rtc_lock);
716
717 if (rtc_status & RTC_IS_OPEN)
718 goto out_busy;
719
720 rtc_status |= RTC_IS_OPEN;
721
722 rtc_irq_data = 0;
723 spin_unlock_irq(&rtc_lock);
724 return 0;
725
726out_busy:
727 spin_unlock_irq(&rtc_lock);
728 return -EBUSY;
729}
730
731static int rtc_fasync(int fd, struct file *filp, int on)
732{
733 return fasync_helper(fd, filp, on, &rtc_async_queue);
734}
735
736static int rtc_release(struct inode *inode, struct file *file)
737{
738#ifdef RTC_IRQ
739 unsigned char tmp;
740
741 if (rtc_has_irq == 0)
742 goto no_irq;
743
744 /*
745 * Turn off all interrupts once the device is no longer
746 * in use, and clear the data.
747 */
748
749 spin_lock_irq(&rtc_lock);
750 if (!hpet_mask_rtc_irq_bit(RTC_PIE | RTC_AIE | RTC_UIE)) {
751 tmp = CMOS_READ(RTC_CONTROL);
752 tmp &= ~RTC_PIE;
753 tmp &= ~RTC_AIE;
754 tmp &= ~RTC_UIE;
755 CMOS_WRITE(tmp, RTC_CONTROL);
756 CMOS_READ(RTC_INTR_FLAGS);
757 }
758 if (rtc_status & RTC_TIMER_ON) {
759 rtc_status &= ~RTC_TIMER_ON;
760 del_timer(&rtc_irq_timer);
761 }
762 spin_unlock_irq(&rtc_lock);
763
764no_irq:
765#endif
766
767 spin_lock_irq(&rtc_lock);
768 rtc_irq_data = 0;
769 rtc_status &= ~RTC_IS_OPEN;
770 spin_unlock_irq(&rtc_lock);
771
772 return 0;
773}
774
775#ifdef RTC_IRQ
776static __poll_t rtc_poll(struct file *file, poll_table *wait)
777{
778 unsigned long l;
779
780 if (rtc_has_irq == 0)
781 return 0;
782
783 poll_wait(file, &rtc_wait, wait);
784
785 spin_lock_irq(&rtc_lock);
786 l = rtc_irq_data;
787 spin_unlock_irq(&rtc_lock);
788
789 if (l != 0)
790 return EPOLLIN | EPOLLRDNORM;
791 return 0;
792}
793#endif
794
795/*
796 * The various file operations we support.
797 */
798
799static const struct file_operations rtc_fops = {
800 .owner = THIS_MODULE,
801 .llseek = no_llseek,
802 .read = rtc_read,
803#ifdef RTC_IRQ
804 .poll = rtc_poll,
805#endif
806 .unlocked_ioctl = rtc_ioctl,
807 .open = rtc_open,
808 .release = rtc_release,
809 .fasync = rtc_fasync,
810};
811
812static struct miscdevice rtc_dev = {
813 .minor = RTC_MINOR,
814 .name = "rtc",
815 .fops = &rtc_fops,
816};
817
818static resource_size_t rtc_size;
819
820static struct resource * __init rtc_request_region(resource_size_t size)
821{
822 struct resource *r;
823
824 if (RTC_IOMAPPED)
825 r = request_region(RTC_PORT(0), size, "rtc");
826 else
827 r = request_mem_region(RTC_PORT(0), size, "rtc");
828
829 if (r)
830 rtc_size = size;
831
832 return r;
833}
834
835static void rtc_release_region(void)
836{
837 if (RTC_IOMAPPED)
838 release_region(RTC_PORT(0), rtc_size);
839 else
840 release_mem_region(RTC_PORT(0), rtc_size);
841}
842
843static int __init rtc_init(void)
844{
845#ifdef CONFIG_PROC_FS
846 struct proc_dir_entry *ent;
847#endif
848#if defined(__alpha__) || defined(__mips__)
849 unsigned int year, ctrl;
850 char *guess = NULL;
851#endif
852#ifdef CONFIG_SPARC32
853 struct device_node *ebus_dp;
854 struct platform_device *op;
855#else
856 void *r;
857#ifdef RTC_IRQ
858 irq_handler_t rtc_int_handler_ptr;
859#endif
860#endif
861
862#ifdef CONFIG_SPARC32
863 for_each_node_by_name(ebus_dp, "ebus") {
864 struct device_node *dp;
865 for_each_child_of_node(ebus_dp, dp) {
866 if (of_node_name_eq(dp, "rtc")) {
867 op = of_find_device_by_node(dp);
868 if (op) {
869 rtc_port = op->resource[0].start;
870 rtc_irq = op->irqs[0];
871 goto found;
872 }
873 }
874 }
875 }
876 rtc_has_irq = 0;
877 printk(KERN_ERR "rtc_init: no PC rtc found\n");
878 return -EIO;
879
880found:
881 if (!rtc_irq) {
882 rtc_has_irq = 0;
883 goto no_irq;
884 }
885
886 /*
887 * XXX Interrupt pin #7 in Espresso is shared between RTC and
888 * PCI Slot 2 INTA# (and some INTx# in Slot 1).
889 */
890 if (request_irq(rtc_irq, rtc_interrupt, IRQF_SHARED, "rtc",
891 (void *)&rtc_port)) {
892 rtc_has_irq = 0;
893 printk(KERN_ERR "rtc: cannot register IRQ %d\n", rtc_irq);
894 return -EIO;
895 }
896no_irq:
897#else
898 r = rtc_request_region(RTC_IO_EXTENT);
899
900 /*
901 * If we've already requested a smaller range (for example, because
902 * PNPBIOS or ACPI told us how the device is configured), the request
903 * above might fail because it's too big.
904 *
905 * If so, request just the range we actually use.
906 */
907 if (!r)
908 r = rtc_request_region(RTC_IO_EXTENT_USED);
909 if (!r) {
910#ifdef RTC_IRQ
911 rtc_has_irq = 0;
912#endif
913 printk(KERN_ERR "rtc: I/O resource %lx is not free.\n",
914 (long)(RTC_PORT(0)));
915 return -EIO;
916 }
917
918#ifdef RTC_IRQ
919 if (is_hpet_enabled()) {
920 int err;
921
922 rtc_int_handler_ptr = hpet_rtc_interrupt;
923 err = hpet_register_irq_handler(rtc_interrupt);
924 if (err != 0) {
925 printk(KERN_WARNING "hpet_register_irq_handler failed "
926 "in rtc_init().");
927 return err;
928 }
929 } else {
930 rtc_int_handler_ptr = rtc_interrupt;
931 }
932
933 if (request_irq(RTC_IRQ, rtc_int_handler_ptr, 0, "rtc", NULL)) {
934 /* Yeah right, seeing as irq 8 doesn't even hit the bus. */
935 rtc_has_irq = 0;
936 printk(KERN_ERR "rtc: IRQ %d is not free.\n", RTC_IRQ);
937 rtc_release_region();
938
939 return -EIO;
940 }
941 hpet_rtc_timer_init();
942
943#endif
944
945#endif /* CONFIG_SPARC32 vs. others */
946
947 if (misc_register(&rtc_dev)) {
948#ifdef RTC_IRQ
949 free_irq(RTC_IRQ, NULL);
950 hpet_unregister_irq_handler(rtc_interrupt);
951 rtc_has_irq = 0;
952#endif
953 rtc_release_region();
954 return -ENODEV;
955 }
956
957#ifdef CONFIG_PROC_FS
958 ent = proc_create_single("driver/rtc", 0, NULL, rtc_proc_show);
959 if (!ent)
960 printk(KERN_WARNING "rtc: Failed to register with procfs.\n");
961#endif
962
963#if defined(__alpha__) || defined(__mips__)
964 rtc_freq = HZ;
965
966 /* Each operating system on an Alpha uses its own epoch.
967 Let's try to guess which one we are using now. */
968
969 if (rtc_is_updating() != 0)
970 msleep(20);
971
972 spin_lock_irq(&rtc_lock);
973 year = CMOS_READ(RTC_YEAR);
974 ctrl = CMOS_READ(RTC_CONTROL);
975 spin_unlock_irq(&rtc_lock);
976
977 if (!(ctrl & RTC_DM_BINARY) || RTC_ALWAYS_BCD)
978 year = bcd2bin(year); /* This should never happen... */
979
980 if (year < 20) {
981 epoch = 2000;
982 guess = "SRM (post-2000)";
983 } else if (year >= 20 && year < 48) {
984 epoch = 1980;
985 guess = "ARC console";
986 } else if (year >= 48 && year < 72) {
987 epoch = 1952;
988 guess = "Digital UNIX";
989#if defined(__mips__)
990 } else if (year >= 72 && year < 74) {
991 epoch = 2000;
992 guess = "Digital DECstation";
993#else
994 } else if (year >= 70) {
995 epoch = 1900;
996 guess = "Standard PC (1900)";
997#endif
998 }
999 if (guess)
1000 printk(KERN_INFO "rtc: %s epoch (%lu) detected\n",
1001 guess, epoch);
1002#endif
1003#ifdef RTC_IRQ
1004 if (rtc_has_irq == 0)
1005 goto no_irq2;
1006
1007 spin_lock_irq(&rtc_lock);
1008 rtc_freq = 1024;
1009 if (!hpet_set_periodic_freq(rtc_freq)) {
1010 /*
1011 * Initialize periodic frequency to CMOS reset default,
1012 * which is 1024Hz
1013 */
1014 CMOS_WRITE(((CMOS_READ(RTC_FREQ_SELECT) & 0xF0) | 0x06),
1015 RTC_FREQ_SELECT);
1016 }
1017 spin_unlock_irq(&rtc_lock);
1018no_irq2:
1019#endif
1020
1021 (void) init_sysctl();
1022
1023 printk(KERN_INFO "Real Time Clock Driver v" RTC_VERSION "\n");
1024
1025 return 0;
1026}
1027
1028static void __exit rtc_exit(void)
1029{
1030 cleanup_sysctl();
1031 remove_proc_entry("driver/rtc", NULL);
1032 misc_deregister(&rtc_dev);
1033
1034#ifdef CONFIG_SPARC32
1035 if (rtc_has_irq)
1036 free_irq(rtc_irq, &rtc_port);
1037#else
1038 rtc_release_region();
1039#ifdef RTC_IRQ
1040 if (rtc_has_irq) {
1041 free_irq(RTC_IRQ, NULL);
1042 hpet_unregister_irq_handler(hpet_rtc_interrupt);
1043 }
1044#endif
1045#endif /* CONFIG_SPARC32 */
1046}
1047
1048module_init(rtc_init);
1049module_exit(rtc_exit);
1050
1051#ifdef RTC_IRQ
1052/*
1053 * At IRQ rates >= 4096Hz, an interrupt may get lost altogether.
1054 * (usually during an IDE disk interrupt, with IRQ unmasking off)
1055 * Since the interrupt handler doesn't get called, the IRQ status
1056 * byte doesn't get read, and the RTC stops generating interrupts.
1057 * A timer is set, and will call this function if/when that happens.
1058 * To get it out of this stalled state, we just read the status.
1059 * At least a jiffy of interrupts (rtc_freq/HZ) will have been lost.
1060 * (You *really* shouldn't be trying to use a non-realtime system
1061 * for something that requires a steady > 1KHz signal anyways.)
1062 */
1063
1064static void rtc_dropped_irq(struct timer_list *unused)
1065{
1066 unsigned long freq;
1067
1068 spin_lock_irq(&rtc_lock);
1069
1070 if (hpet_rtc_dropped_irq()) {
1071 spin_unlock_irq(&rtc_lock);
1072 return;
1073 }
1074
1075 /* Just in case someone disabled the timer from behind our back... */
1076 if (rtc_status & RTC_TIMER_ON)
1077 mod_timer(&rtc_irq_timer, jiffies + HZ/rtc_freq + 2*HZ/100);
1078
1079 rtc_irq_data += ((rtc_freq/HZ)<<8);
1080 rtc_irq_data &= ~0xff;
1081 rtc_irq_data |= (CMOS_READ(RTC_INTR_FLAGS) & 0xF0); /* restart */
1082
1083 freq = rtc_freq;
1084
1085 spin_unlock_irq(&rtc_lock);
1086
1087 printk_ratelimited(KERN_WARNING "rtc: lost some interrupts at %ldHz.\n",
1088 freq);
1089
1090 /* Now we have new data */
1091 wake_up_interruptible(&rtc_wait);
1092
1093 kill_fasync(&rtc_async_queue, SIGIO, POLL_IN);
1094}
1095#endif
1096
1097#ifdef CONFIG_PROC_FS
1098/*
1099 * Info exported via "/proc/driver/rtc".
1100 */
1101
1102static int rtc_proc_show(struct seq_file *seq, void *v)
1103{
1104#define YN(bit) ((ctrl & bit) ? "yes" : "no")
1105#define NY(bit) ((ctrl & bit) ? "no" : "yes")
1106 struct rtc_time tm;
1107 unsigned char batt, ctrl;
1108 unsigned long freq;
1109
1110 spin_lock_irq(&rtc_lock);
1111 batt = CMOS_READ(RTC_VALID) & RTC_VRT;
1112 ctrl = CMOS_READ(RTC_CONTROL);
1113 freq = rtc_freq;
1114 spin_unlock_irq(&rtc_lock);
1115
1116
1117 rtc_get_rtc_time(&tm);
1118
1119 /*
1120 * There is no way to tell if the luser has the RTC set for local
1121 * time or for Universal Standard Time (GMT). Probably local though.
1122 */
1123 seq_printf(seq,
1124 "rtc_time\t: %ptRt\n"
1125 "rtc_date\t: %ptRd\n"
1126 "rtc_epoch\t: %04lu\n",
1127 &tm, &tm, epoch);
1128
1129 get_rtc_alm_time(&tm);
1130
1131 /*
1132 * We implicitly assume 24hr mode here. Alarm values >= 0xc0 will
1133 * match any value for that particular field. Values that are
1134 * greater than a valid time, but less than 0xc0 shouldn't appear.
1135 */
1136 seq_puts(seq, "alarm\t\t: ");
1137 if (tm.tm_hour <= 24)
1138 seq_printf(seq, "%02d:", tm.tm_hour);
1139 else
1140 seq_puts(seq, "**:");
1141
1142 if (tm.tm_min <= 59)
1143 seq_printf(seq, "%02d:", tm.tm_min);
1144 else
1145 seq_puts(seq, "**:");
1146
1147 if (tm.tm_sec <= 59)
1148 seq_printf(seq, "%02d\n", tm.tm_sec);
1149 else
1150 seq_puts(seq, "**\n");
1151
1152 seq_printf(seq,
1153 "DST_enable\t: %s\n"
1154 "BCD\t\t: %s\n"
1155 "24hr\t\t: %s\n"
1156 "square_wave\t: %s\n"
1157 "alarm_IRQ\t: %s\n"
1158 "update_IRQ\t: %s\n"
1159 "periodic_IRQ\t: %s\n"
1160 "periodic_freq\t: %ld\n"
1161 "batt_status\t: %s\n",
1162 YN(RTC_DST_EN),
1163 NY(RTC_DM_BINARY),
1164 YN(RTC_24H),
1165 YN(RTC_SQWE),
1166 YN(RTC_AIE),
1167 YN(RTC_UIE),
1168 YN(RTC_PIE),
1169 freq,
1170 batt ? "okay" : "dead");
1171
1172 return 0;
1173#undef YN
1174#undef NY
1175}
1176#endif
1177
1178static void rtc_get_rtc_time(struct rtc_time *rtc_tm)
1179{
1180 unsigned long uip_watchdog = jiffies, flags;
1181 unsigned char ctrl;
1182#ifdef CONFIG_MACH_DECSTATION
1183 unsigned int real_year;
1184#endif
1185
1186 /*
1187 * read RTC once any update in progress is done. The update
1188 * can take just over 2ms. We wait 20ms. There is no need to
1189 * to poll-wait (up to 1s - eeccch) for the falling edge of RTC_UIP.
1190 * If you need to know *exactly* when a second has started, enable
1191 * periodic update complete interrupts, (via ioctl) and then
1192 * immediately read /dev/rtc which will block until you get the IRQ.
1193 * Once the read clears, read the RTC time (again via ioctl). Easy.
1194 */
1195
1196 while (rtc_is_updating() != 0 &&
1197 time_before(jiffies, uip_watchdog + 2*HZ/100))
1198 cpu_relax();
1199
1200 /*
1201 * Only the values that we read from the RTC are set. We leave
1202 * tm_wday, tm_yday and tm_isdst untouched. Note that while the
1203 * RTC has RTC_DAY_OF_WEEK, we should usually ignore it, as it is
1204 * only updated by the RTC when initially set to a non-zero value.
1205 */
1206 spin_lock_irqsave(&rtc_lock, flags);
1207 rtc_tm->tm_sec = CMOS_READ(RTC_SECONDS);
1208 rtc_tm->tm_min = CMOS_READ(RTC_MINUTES);
1209 rtc_tm->tm_hour = CMOS_READ(RTC_HOURS);
1210 rtc_tm->tm_mday = CMOS_READ(RTC_DAY_OF_MONTH);
1211 rtc_tm->tm_mon = CMOS_READ(RTC_MONTH);
1212 rtc_tm->tm_year = CMOS_READ(RTC_YEAR);
1213 /* Only set from 2.6.16 onwards */
1214 rtc_tm->tm_wday = CMOS_READ(RTC_DAY_OF_WEEK);
1215
1216#ifdef CONFIG_MACH_DECSTATION
1217 real_year = CMOS_READ(RTC_DEC_YEAR);
1218#endif
1219 ctrl = CMOS_READ(RTC_CONTROL);
1220 spin_unlock_irqrestore(&rtc_lock, flags);
1221
1222 if (!(ctrl & RTC_DM_BINARY) || RTC_ALWAYS_BCD) {
1223 rtc_tm->tm_sec = bcd2bin(rtc_tm->tm_sec);
1224 rtc_tm->tm_min = bcd2bin(rtc_tm->tm_min);
1225 rtc_tm->tm_hour = bcd2bin(rtc_tm->tm_hour);
1226 rtc_tm->tm_mday = bcd2bin(rtc_tm->tm_mday);
1227 rtc_tm->tm_mon = bcd2bin(rtc_tm->tm_mon);
1228 rtc_tm->tm_year = bcd2bin(rtc_tm->tm_year);
1229 rtc_tm->tm_wday = bcd2bin(rtc_tm->tm_wday);
1230 }
1231
1232#ifdef CONFIG_MACH_DECSTATION
1233 rtc_tm->tm_year += real_year - 72;
1234#endif
1235
1236 /*
1237 * Account for differences between how the RTC uses the values
1238 * and how they are defined in a struct rtc_time;
1239 */
1240 rtc_tm->tm_year += epoch - 1900;
1241 if (rtc_tm->tm_year <= 69)
1242 rtc_tm->tm_year += 100;
1243
1244 rtc_tm->tm_mon--;
1245}
1246
1247static void get_rtc_alm_time(struct rtc_time *alm_tm)
1248{
1249 unsigned char ctrl;
1250
1251 /*
1252 * Only the values that we read from the RTC are set. That
1253 * means only tm_hour, tm_min, and tm_sec.
1254 */
1255 spin_lock_irq(&rtc_lock);
1256 alm_tm->tm_sec = CMOS_READ(RTC_SECONDS_ALARM);
1257 alm_tm->tm_min = CMOS_READ(RTC_MINUTES_ALARM);
1258 alm_tm->tm_hour = CMOS_READ(RTC_HOURS_ALARM);
1259 ctrl = CMOS_READ(RTC_CONTROL);
1260 spin_unlock_irq(&rtc_lock);
1261
1262 if (!(ctrl & RTC_DM_BINARY) || RTC_ALWAYS_BCD) {
1263 alm_tm->tm_sec = bcd2bin(alm_tm->tm_sec);
1264 alm_tm->tm_min = bcd2bin(alm_tm->tm_min);
1265 alm_tm->tm_hour = bcd2bin(alm_tm->tm_hour);
1266 }
1267}
1268
1269#ifdef RTC_IRQ
1270/*
1271 * Used to disable/enable interrupts for any one of UIE, AIE, PIE.
1272 * Rumour has it that if you frob the interrupt enable/disable
1273 * bits in RTC_CONTROL, you should read RTC_INTR_FLAGS, to
1274 * ensure you actually start getting interrupts. Probably for
1275 * compatibility with older/broken chipset RTC implementations.
1276 * We also clear out any old irq data after an ioctl() that
1277 * meddles with the interrupt enable/disable bits.
1278 */
1279
1280static void mask_rtc_irq_bit_locked(unsigned char bit)
1281{
1282 unsigned char val;
1283
1284 if (hpet_mask_rtc_irq_bit(bit))
1285 return;
1286 val = CMOS_READ(RTC_CONTROL);
1287 val &= ~bit;
1288 CMOS_WRITE(val, RTC_CONTROL);
1289 CMOS_READ(RTC_INTR_FLAGS);
1290
1291 rtc_irq_data = 0;
1292}
1293
1294static void set_rtc_irq_bit_locked(unsigned char bit)
1295{
1296 unsigned char val;
1297
1298 if (hpet_set_rtc_irq_bit(bit))
1299 return;
1300 val = CMOS_READ(RTC_CONTROL);
1301 val |= bit;
1302 CMOS_WRITE(val, RTC_CONTROL);
1303 CMOS_READ(RTC_INTR_FLAGS);
1304
1305 rtc_irq_data = 0;
1306}
1307#endif
1308
1309MODULE_AUTHOR("Paul Gortmaker");
1310MODULE_LICENSE("GPL");
1311MODULE_ALIAS_MISCDEV(RTC_MINOR);