2 * Real Time Clock interface for Linux
4 * Copyright (C) 1996 Paul Gortmaker
6 * This driver allows use of the real time clock (built into
7 * nearly all computers) from user space. It exports the /dev/rtc
8 * interface supporting various ioctl() and also the
9 * /proc/driver/rtc pseudo-file for status information.
11 * The ioctls can be used to set the interrupt behaviour and
12 * generation rate from the RTC via IRQ 8. Then the /dev/rtc
13 * interface can be used to make use of these timer interrupts,
14 * be they interval or alarm based.
16 * The /dev/rtc interface will block on reads until an interrupt
17 * has been received. If a RTC interrupt has already happened,
18 * it will output an unsigned long and then block. The output value
19 * contains the interrupt status in the low byte and the number of
20 * interrupts since the last read in the remaining high bytes. The
21 * /dev/rtc interface can also be used with the select(2) call.
23 * This program is free software; you can redistribute it and/or
24 * modify it under the terms of the GNU General Public License
25 * as published by the Free Software Foundation; either version
26 * 2 of the License, or (at your option) any later version.
28 * Based on other minimal char device drivers, like Alan's
29 * watchdog, Ted's random, etc. etc.
31 * 1.07 Paul Gortmaker.
32 * 1.08 Miquel van Smoorenburg: disallow certain things on the
33 * DEC Alpha as the CMOS clock is also used for other things.
34 * 1.09 Nikita Schmidt: epoch support and some Alpha cleanup.
35 * 1.09a Pete Zaitcev: Sun SPARC
36 * 1.09b Jeff Garzik: Modularize, init cleanup
37 * 1.09c Jeff Garzik: SMP cleanup
38 * 1.10 Paul Barton-Davis: add support for async I/O
39 * 1.10a Andrea Arcangeli: Alpha updates
40 * 1.10b Andrew Morton: SMP lock fix
41 * 1.10c Cesar Barros: SMP locking fixes and cleanup
42 * 1.10d Paul Gortmaker: delete paranoia check in rtc_exit
43 * 1.10e Maciej W. Rozycki: Handle DECstation's year weirdness.
44 * 1.11 Takashi Iwai: Kernel access functions
45 * rtc_register/rtc_unregister/rtc_control
46 * 1.11a Daniele Bellucci: Audit create_proc_read_entry in rtc_init
47 * 1.12 Venkatesh Pallipadi: Hooks for emulating rtc on HPET base-timer
48 * CONFIG_HPET_EMULATE_RTC
49 * 1.12a Maciej W. Rozycki: Handle memory-mapped chips properly.
50 * 1.12ac Alan Cox: Allow read access to the day of week register
53 #define RTC_VERSION "1.12ac"
56 * Note that *all* calls to CMOS_READ and CMOS_WRITE are done with
57 * interrupts disabled. Due to the index-port/data-port (0x70/0x71)
58 * design of the RTC, we don't want two different things trying to
59 * get to it at once. (e.g. the periodic 11 min sync from time.c vs.
63 #include <linux/interrupt.h>
64 #include <linux/module.h>
65 #include <linux/kernel.h>
66 #include <linux/types.h>
67 #include <linux/miscdevice.h>
68 #include <linux/ioport.h>
69 #include <linux/fcntl.h>
70 #include <linux/mc146818rtc.h>
71 #include <linux/init.h>
72 #include <linux/poll.h>
73 #include <linux/proc_fs.h>
74 #include <linux/seq_file.h>
75 #include <linux/spinlock.h>
76 #include <linux/sysctl.h>
77 #include <linux/wait.h>
78 #include <linux/bcd.h>
79 #include <linux/delay.h>
81 #include <asm/current.h>
82 #include <asm/uaccess.h>
83 #include <asm/system.h>
90 #include <linux/pci.h>
93 static unsigned long rtc_port;
94 static int rtc_irq = PCI_IRQ_NONE;
97 #ifdef CONFIG_HPET_RTC_IRQ
102 static int rtc_has_irq = 1;
105 #ifndef CONFIG_HPET_EMULATE_RTC
106 #define is_hpet_enabled() 0
107 #define hpet_set_alarm_time(hrs, min, sec) 0
108 #define hpet_set_periodic_freq(arg) 0
109 #define hpet_mask_rtc_irq_bit(arg) 0
110 #define hpet_set_rtc_irq_bit(arg) 0
111 #define hpet_rtc_timer_init() do { } while (0)
112 #define hpet_rtc_dropped_irq() 0
114 static irqreturn_t hpet_rtc_interrupt(int irq, void *dev_id)
120 extern irqreturn_t hpet_rtc_interrupt(int irq, void *dev_id);
124 * We sponge a minor off of the misc major. No need slurping
125 * up another valuable major dev number for this. If you add
126 * an ioctl, make sure you don't conflict with SPARC's RTC
130 static struct fasync_struct *rtc_async_queue;
132 static DECLARE_WAIT_QUEUE_HEAD(rtc_wait);
135 static void rtc_dropped_irq(unsigned long data);
137 static DEFINE_TIMER(rtc_irq_timer, rtc_dropped_irq, 0, 0);
140 static ssize_t rtc_read(struct file *file, char __user *buf,
141 size_t count, loff_t *ppos);
143 static int rtc_ioctl(struct inode *inode, struct file *file,
144 unsigned int cmd, unsigned long arg);
147 static unsigned int rtc_poll(struct file *file, poll_table *wait);
150 static void get_rtc_alm_time(struct rtc_time *alm_tm);
152 static void set_rtc_irq_bit_locked(unsigned char bit);
153 static void mask_rtc_irq_bit_locked(unsigned char bit);
155 static inline void set_rtc_irq_bit(unsigned char bit)
157 spin_lock_irq(&rtc_lock);
158 set_rtc_irq_bit_locked(bit);
159 spin_unlock_irq(&rtc_lock);
162 static void mask_rtc_irq_bit(unsigned char bit)
164 spin_lock_irq(&rtc_lock);
165 mask_rtc_irq_bit_locked(bit);
166 spin_unlock_irq(&rtc_lock);
170 #ifdef CONFIG_PROC_FS
171 static int rtc_proc_open(struct inode *inode, struct file *file);
175 * Bits in rtc_status. (6 bits of room for future expansion)
178 #define RTC_IS_OPEN 0x01 /* means /dev/rtc is in use */
179 #define RTC_TIMER_ON 0x02 /* missed irq timer active */
182 * rtc_status is never changed by rtc_interrupt, and ioctl/open/close is
183 * protected by the big kernel lock. However, ioctl can still disable the timer
184 * in rtc_status and then with del_timer after the interrupt has read
185 * rtc_status but before mod_timer is called, which would then reenable the
186 * timer (but you would need to have an awful timing before you'd trip on it)
188 static unsigned long rtc_status; /* bitmapped status byte. */
189 static unsigned long rtc_freq; /* Current periodic IRQ rate */
190 static unsigned long rtc_irq_data; /* our output to the world */
191 static unsigned long rtc_max_user_freq = 64; /* > this, need CAP_SYS_RESOURCE */
195 * rtc_task_lock nests inside rtc_lock.
197 static DEFINE_SPINLOCK(rtc_task_lock);
198 static rtc_task_t *rtc_callback;
202 * If this driver ever becomes modularised, it will be really nice
203 * to make the epoch retain its value across module reload...
206 static unsigned long epoch = 1900; /* year corresponding to 0x00 */
208 static const unsigned char days_in_mo[] =
209 {0, 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31};
212 * Returns true if a clock update is in progress
214 static inline unsigned char rtc_is_updating(void)
219 spin_lock_irqsave(&rtc_lock, flags);
220 uip = (CMOS_READ(RTC_FREQ_SELECT) & RTC_UIP);
221 spin_unlock_irqrestore(&rtc_lock, flags);
227 * A very tiny interrupt handler. It runs with IRQF_DISABLED set,
228 * but there is possibility of conflicting with the set_rtc_mmss()
229 * call (the rtc irq and the timer irq can easily run at the same
230 * time in two different CPUs). So we need to serialize
231 * accesses to the chip with the rtc_lock spinlock that each
232 * architecture should implement in the timer code.
233 * (See ./arch/XXXX/kernel/time.c for the set_rtc_mmss() function.)
236 irqreturn_t rtc_interrupt(int irq, void *dev_id)
239 * Can be an alarm interrupt, update complete interrupt,
240 * or a periodic interrupt. We store the status in the
241 * low byte and the number of interrupts received since
242 * the last read in the remainder of rtc_irq_data.
245 spin_lock(&rtc_lock);
246 rtc_irq_data += 0x100;
247 rtc_irq_data &= ~0xff;
248 if (is_hpet_enabled()) {
250 * In this case it is HPET RTC interrupt handler
251 * calling us, with the interrupt information
252 * passed as arg1, instead of irq.
254 rtc_irq_data |= (unsigned long)irq & 0xF0;
256 rtc_irq_data |= (CMOS_READ(RTC_INTR_FLAGS) & 0xF0);
259 if (rtc_status & RTC_TIMER_ON)
260 mod_timer(&rtc_irq_timer, jiffies + HZ/rtc_freq + 2*HZ/100);
262 spin_unlock(&rtc_lock);
264 /* Now do the rest of the actions */
265 spin_lock(&rtc_task_lock);
267 rtc_callback->func(rtc_callback->private_data);
268 spin_unlock(&rtc_task_lock);
269 wake_up_interruptible(&rtc_wait);
271 kill_fasync(&rtc_async_queue, SIGIO, POLL_IN);
278 * sysctl-tuning infrastructure.
280 static ctl_table rtc_table[] = {
282 .ctl_name = CTL_UNNUMBERED,
283 .procname = "max-user-freq",
284 .data = &rtc_max_user_freq,
285 .maxlen = sizeof(int),
287 .proc_handler = &proc_dointvec,
292 static ctl_table rtc_root[] = {
294 .ctl_name = CTL_UNNUMBERED,
302 static ctl_table dev_root[] = {
312 static struct ctl_table_header *sysctl_header;
314 static int __init init_sysctl(void)
316 sysctl_header = register_sysctl_table(dev_root);
320 static void __exit cleanup_sysctl(void)
322 unregister_sysctl_table(sysctl_header);
326 * Now all the various file operations that we export.
329 static ssize_t rtc_read(struct file *file, char __user *buf,
330 size_t count, loff_t *ppos)
335 DECLARE_WAITQUEUE(wait, current);
339 if (rtc_has_irq == 0)
343 * Historically this function used to assume that sizeof(unsigned long)
344 * is the same in userspace and kernelspace. This lead to problems
345 * for configurations with multiple ABIs such a the MIPS o32 and 64
346 * ABIs supported on the same kernel. So now we support read of both
347 * 4 and 8 bytes and assume that's the sizeof(unsigned long) in the
350 if (count != sizeof(unsigned int) && count != sizeof(unsigned long))
353 add_wait_queue(&rtc_wait, &wait);
356 /* First make it right. Then make it fast. Putting this whole
357 * block within the parentheses of a while would be too
358 * confusing. And no, xchg() is not the answer. */
360 __set_current_state(TASK_INTERRUPTIBLE);
362 spin_lock_irq(&rtc_lock);
365 spin_unlock_irq(&rtc_lock);
370 if (file->f_flags & O_NONBLOCK) {
374 if (signal_pending(current)) {
375 retval = -ERESTARTSYS;
381 if (count == sizeof(unsigned int)) {
382 retval = put_user(data,
383 (unsigned int __user *)buf) ?: sizeof(int);
385 retval = put_user(data,
386 (unsigned long __user *)buf) ?: sizeof(long);
391 __set_current_state(TASK_RUNNING);
392 remove_wait_queue(&rtc_wait, &wait);
398 static int rtc_do_ioctl(unsigned int cmd, unsigned long arg, int kernel)
400 struct rtc_time wtime;
403 if (rtc_has_irq == 0) {
420 case RTC_AIE_OFF: /* Mask alarm int. enab. bit */
422 mask_rtc_irq_bit(RTC_AIE);
425 case RTC_AIE_ON: /* Allow alarm interrupts. */
427 set_rtc_irq_bit(RTC_AIE);
430 case RTC_PIE_OFF: /* Mask periodic int. enab. bit */
432 /* can be called from isr via rtc_control() */
435 spin_lock_irqsave(&rtc_lock, flags);
436 mask_rtc_irq_bit_locked(RTC_PIE);
437 if (rtc_status & RTC_TIMER_ON) {
438 rtc_status &= ~RTC_TIMER_ON;
439 del_timer(&rtc_irq_timer);
441 spin_unlock_irqrestore(&rtc_lock, flags);
445 case RTC_PIE_ON: /* Allow periodic ints */
447 /* can be called from isr via rtc_control() */
451 * We don't really want Joe User enabling more
452 * than 64Hz of interrupts on a multi-user machine.
454 if (!kernel && (rtc_freq > rtc_max_user_freq) &&
455 (!capable(CAP_SYS_RESOURCE)))
458 spin_lock_irqsave(&rtc_lock, flags);
459 if (!(rtc_status & RTC_TIMER_ON)) {
460 mod_timer(&rtc_irq_timer, jiffies + HZ/rtc_freq +
462 rtc_status |= RTC_TIMER_ON;
464 set_rtc_irq_bit_locked(RTC_PIE);
465 spin_unlock_irqrestore(&rtc_lock, flags);
469 case RTC_UIE_OFF: /* Mask ints from RTC updates. */
471 mask_rtc_irq_bit(RTC_UIE);
474 case RTC_UIE_ON: /* Allow ints for RTC updates. */
476 set_rtc_irq_bit(RTC_UIE);
480 case RTC_ALM_READ: /* Read the present alarm time */
483 * This returns a struct rtc_time. Reading >= 0xc0
484 * means "don't care" or "match all". Only the tm_hour,
485 * tm_min, and tm_sec values are filled in.
487 memset(&wtime, 0, sizeof(struct rtc_time));
488 get_rtc_alm_time(&wtime);
491 case RTC_ALM_SET: /* Store a time into the alarm */
494 * This expects a struct rtc_time. Writing 0xff means
495 * "don't care" or "match all". Only the tm_hour,
496 * tm_min and tm_sec are used.
498 unsigned char hrs, min, sec;
499 struct rtc_time alm_tm;
501 if (copy_from_user(&alm_tm, (struct rtc_time __user *)arg,
502 sizeof(struct rtc_time)))
505 hrs = alm_tm.tm_hour;
509 spin_lock_irq(&rtc_lock);
510 if (hpet_set_alarm_time(hrs, min, sec)) {
512 * Fallthru and set alarm time in CMOS too,
513 * so that we will get proper value in RTC_ALM_READ
516 if (!(CMOS_READ(RTC_CONTROL) & RTC_DM_BINARY) ||
533 CMOS_WRITE(hrs, RTC_HOURS_ALARM);
534 CMOS_WRITE(min, RTC_MINUTES_ALARM);
535 CMOS_WRITE(sec, RTC_SECONDS_ALARM);
536 spin_unlock_irq(&rtc_lock);
540 case RTC_RD_TIME: /* Read the time/date from RTC */
542 memset(&wtime, 0, sizeof(struct rtc_time));
543 rtc_get_rtc_time(&wtime);
546 case RTC_SET_TIME: /* Set the RTC */
548 struct rtc_time rtc_tm;
549 unsigned char mon, day, hrs, min, sec, leap_yr;
550 unsigned char save_control, save_freq_select;
552 #ifdef CONFIG_MACH_DECSTATION
553 unsigned int real_yrs;
556 if (!capable(CAP_SYS_TIME))
559 if (copy_from_user(&rtc_tm, (struct rtc_time __user *)arg,
560 sizeof(struct rtc_time)))
563 yrs = rtc_tm.tm_year + 1900;
564 mon = rtc_tm.tm_mon + 1; /* tm_mon starts at zero */
565 day = rtc_tm.tm_mday;
566 hrs = rtc_tm.tm_hour;
573 leap_yr = ((!(yrs % 4) && (yrs % 100)) || !(yrs % 400));
575 if ((mon > 12) || (day == 0))
578 if (day > (days_in_mo[mon] + ((mon == 2) && leap_yr)))
581 if ((hrs >= 24) || (min >= 60) || (sec >= 60))
585 if (yrs > 255) /* They are unsigned */
588 spin_lock_irq(&rtc_lock);
589 #ifdef CONFIG_MACH_DECSTATION
594 * We want to keep the year set to 73 until March
595 * for non-leap years, so that Feb, 29th is handled
598 if (!leap_yr && mon < 3) {
603 /* These limits and adjustments are independent of
604 * whether the chip is in binary mode or not.
607 spin_unlock_irq(&rtc_lock);
613 if (!(CMOS_READ(RTC_CONTROL) & RTC_DM_BINARY)
623 save_control = CMOS_READ(RTC_CONTROL);
624 CMOS_WRITE((save_control|RTC_SET), RTC_CONTROL);
625 save_freq_select = CMOS_READ(RTC_FREQ_SELECT);
626 CMOS_WRITE((save_freq_select|RTC_DIV_RESET2), RTC_FREQ_SELECT);
628 #ifdef CONFIG_MACH_DECSTATION
629 CMOS_WRITE(real_yrs, RTC_DEC_YEAR);
631 CMOS_WRITE(yrs, RTC_YEAR);
632 CMOS_WRITE(mon, RTC_MONTH);
633 CMOS_WRITE(day, RTC_DAY_OF_MONTH);
634 CMOS_WRITE(hrs, RTC_HOURS);
635 CMOS_WRITE(min, RTC_MINUTES);
636 CMOS_WRITE(sec, RTC_SECONDS);
638 CMOS_WRITE(save_control, RTC_CONTROL);
639 CMOS_WRITE(save_freq_select, RTC_FREQ_SELECT);
641 spin_unlock_irq(&rtc_lock);
645 case RTC_IRQP_READ: /* Read the periodic IRQ rate. */
647 return put_user(rtc_freq, (unsigned long __user *)arg);
649 case RTC_IRQP_SET: /* Set periodic IRQ rate. */
653 /* can be called from isr via rtc_control() */
657 * The max we can do is 8192Hz.
659 if ((arg < 2) || (arg > 8192))
662 * We don't really want Joe User generating more
663 * than 64Hz of interrupts on a multi-user machine.
665 if (!kernel && (arg > rtc_max_user_freq) &&
666 !capable(CAP_SYS_RESOURCE))
669 while (arg > (1<<tmp))
673 * Check that the input was really a power of 2.
678 spin_lock_irqsave(&rtc_lock, flags);
679 if (hpet_set_periodic_freq(arg)) {
680 spin_unlock_irqrestore(&rtc_lock, flags);
685 val = CMOS_READ(RTC_FREQ_SELECT) & 0xf0;
687 CMOS_WRITE(val, RTC_FREQ_SELECT);
688 spin_unlock_irqrestore(&rtc_lock, flags);
692 case RTC_EPOCH_READ: /* Read the epoch. */
694 return put_user(epoch, (unsigned long __user *)arg);
696 case RTC_EPOCH_SET: /* Set the epoch. */
699 * There were no RTC clocks before 1900.
704 if (!capable(CAP_SYS_TIME))
713 return copy_to_user((void __user *)arg,
714 &wtime, sizeof wtime) ? -EFAULT : 0;
717 static int rtc_ioctl(struct inode *inode, struct file *file, unsigned int cmd,
720 return rtc_do_ioctl(cmd, arg, 0);
724 * We enforce only one user at a time here with the open/close.
725 * Also clear the previous interrupt data on an open, and clean
726 * up things on a close.
729 /* We use rtc_lock to protect against concurrent opens. So the BKL is not
730 * needed here. Or anywhere else in this driver. */
731 static int rtc_open(struct inode *inode, struct file *file)
733 spin_lock_irq(&rtc_lock);
735 if (rtc_status & RTC_IS_OPEN)
738 rtc_status |= RTC_IS_OPEN;
741 spin_unlock_irq(&rtc_lock);
745 spin_unlock_irq(&rtc_lock);
749 static int rtc_fasync(int fd, struct file *filp, int on)
751 return fasync_helper(fd, filp, on, &rtc_async_queue);
754 static int rtc_release(struct inode *inode, struct file *file)
759 if (rtc_has_irq == 0)
763 * Turn off all interrupts once the device is no longer
764 * in use, and clear the data.
767 spin_lock_irq(&rtc_lock);
768 if (!hpet_mask_rtc_irq_bit(RTC_PIE | RTC_AIE | RTC_UIE)) {
769 tmp = CMOS_READ(RTC_CONTROL);
773 CMOS_WRITE(tmp, RTC_CONTROL);
774 CMOS_READ(RTC_INTR_FLAGS);
776 if (rtc_status & RTC_TIMER_ON) {
777 rtc_status &= ~RTC_TIMER_ON;
778 del_timer(&rtc_irq_timer);
780 spin_unlock_irq(&rtc_lock);
782 if (file->f_flags & FASYNC)
783 rtc_fasync(-1, file, 0);
787 spin_lock_irq(&rtc_lock);
789 rtc_status &= ~RTC_IS_OPEN;
790 spin_unlock_irq(&rtc_lock);
796 /* Called without the kernel lock - fine */
797 static unsigned int rtc_poll(struct file *file, poll_table *wait)
801 if (rtc_has_irq == 0)
804 poll_wait(file, &rtc_wait, wait);
806 spin_lock_irq(&rtc_lock);
808 spin_unlock_irq(&rtc_lock);
811 return POLLIN | POLLRDNORM;
816 int rtc_register(rtc_task_t *task)
821 if (task == NULL || task->func == NULL)
823 spin_lock_irq(&rtc_lock);
824 if (rtc_status & RTC_IS_OPEN) {
825 spin_unlock_irq(&rtc_lock);
828 spin_lock(&rtc_task_lock);
830 spin_unlock(&rtc_task_lock);
831 spin_unlock_irq(&rtc_lock);
834 rtc_status |= RTC_IS_OPEN;
836 spin_unlock(&rtc_task_lock);
837 spin_unlock_irq(&rtc_lock);
841 EXPORT_SYMBOL(rtc_register);
843 int rtc_unregister(rtc_task_t *task)
850 spin_lock_irq(&rtc_lock);
851 spin_lock(&rtc_task_lock);
852 if (rtc_callback != task) {
853 spin_unlock(&rtc_task_lock);
854 spin_unlock_irq(&rtc_lock);
859 /* disable controls */
860 if (!hpet_mask_rtc_irq_bit(RTC_PIE | RTC_AIE | RTC_UIE)) {
861 tmp = CMOS_READ(RTC_CONTROL);
865 CMOS_WRITE(tmp, RTC_CONTROL);
866 CMOS_READ(RTC_INTR_FLAGS);
868 if (rtc_status & RTC_TIMER_ON) {
869 rtc_status &= ~RTC_TIMER_ON;
870 del_timer(&rtc_irq_timer);
872 rtc_status &= ~RTC_IS_OPEN;
873 spin_unlock(&rtc_task_lock);
874 spin_unlock_irq(&rtc_lock);
878 EXPORT_SYMBOL(rtc_unregister);
880 int rtc_control(rtc_task_t *task, unsigned int cmd, unsigned long arg)
886 if (cmd != RTC_PIE_ON && cmd != RTC_PIE_OFF && cmd != RTC_IRQP_SET)
888 spin_lock_irqsave(&rtc_task_lock, flags);
889 if (rtc_callback != task) {
890 spin_unlock_irqrestore(&rtc_task_lock, flags);
893 spin_unlock_irqrestore(&rtc_task_lock, flags);
894 return rtc_do_ioctl(cmd, arg, 1);
897 EXPORT_SYMBOL(rtc_control);
900 * The various file operations we support.
903 static const struct file_operations rtc_fops = {
904 .owner = THIS_MODULE,
912 .release = rtc_release,
913 .fasync = rtc_fasync,
916 static struct miscdevice rtc_dev = {
922 #ifdef CONFIG_PROC_FS
923 static const struct file_operations rtc_proc_fops = {
924 .owner = THIS_MODULE,
925 .open = rtc_proc_open,
928 .release = single_release,
932 static resource_size_t rtc_size;
934 static struct resource * __init rtc_request_region(resource_size_t size)
939 r = request_region(RTC_PORT(0), size, "rtc");
941 r = request_mem_region(RTC_PORT(0), size, "rtc");
949 static void rtc_release_region(void)
952 release_region(RTC_PORT(0), rtc_size);
954 release_mem_region(RTC_PORT(0), rtc_size);
957 static int __init rtc_init(void)
959 #ifdef CONFIG_PROC_FS
960 struct proc_dir_entry *ent;
962 #if defined(__alpha__) || defined(__mips__)
963 unsigned int year, ctrl;
966 #ifdef CONFIG_SPARC32
967 struct linux_ebus *ebus;
968 struct linux_ebus_device *edev;
972 irq_handler_t rtc_int_handler_ptr;
976 #ifdef CONFIG_SPARC32
977 for_each_ebus(ebus) {
978 for_each_ebusdev(edev, ebus) {
979 if (strcmp(edev->prom_node->name, "rtc") == 0) {
980 rtc_port = edev->resource[0].start;
981 rtc_irq = edev->irqs[0];
987 printk(KERN_ERR "rtc_init: no PC rtc found\n");
991 if (rtc_irq == PCI_IRQ_NONE) {
997 * XXX Interrupt pin #7 in Espresso is shared between RTC and
998 * PCI Slot 2 INTA# (and some INTx# in Slot 1).
1000 if (request_irq(rtc_irq, rtc_interrupt, IRQF_SHARED, "rtc",
1001 (void *)&rtc_port)) {
1003 printk(KERN_ERR "rtc: cannot register IRQ %d\n", rtc_irq);
1008 r = rtc_request_region(RTC_IO_EXTENT);
1011 * If we've already requested a smaller range (for example, because
1012 * PNPBIOS or ACPI told us how the device is configured), the request
1013 * above might fail because it's too big.
1015 * If so, request just the range we actually use.
1018 r = rtc_request_region(RTC_IO_EXTENT_USED);
1023 printk(KERN_ERR "rtc: I/O resource %lx is not free.\n",
1024 (long)(RTC_PORT(0)));
1029 if (is_hpet_enabled()) {
1030 rtc_int_handler_ptr = hpet_rtc_interrupt;
1032 rtc_int_handler_ptr = rtc_interrupt;
1035 if (request_irq(RTC_IRQ, rtc_int_handler_ptr, IRQF_DISABLED,
1037 /* Yeah right, seeing as irq 8 doesn't even hit the bus. */
1039 printk(KERN_ERR "rtc: IRQ %d is not free.\n", RTC_IRQ);
1040 rtc_release_region();
1044 hpet_rtc_timer_init();
1048 #endif /* CONFIG_SPARC32 vs. others */
1050 if (misc_register(&rtc_dev)) {
1052 free_irq(RTC_IRQ, NULL);
1055 rtc_release_region();
1059 #ifdef CONFIG_PROC_FS
1060 ent = create_proc_entry("driver/rtc", 0, NULL);
1062 ent->proc_fops = &rtc_proc_fops;
1064 printk(KERN_WARNING "rtc: Failed to register with procfs.\n");
1067 #if defined(__alpha__) || defined(__mips__)
1070 /* Each operating system on an Alpha uses its own epoch.
1071 Let's try to guess which one we are using now. */
1073 if (rtc_is_updating() != 0)
1076 spin_lock_irq(&rtc_lock);
1077 year = CMOS_READ(RTC_YEAR);
1078 ctrl = CMOS_READ(RTC_CONTROL);
1079 spin_unlock_irq(&rtc_lock);
1081 if (!(ctrl & RTC_DM_BINARY) || RTC_ALWAYS_BCD)
1082 BCD_TO_BIN(year); /* This should never happen... */
1086 guess = "SRM (post-2000)";
1087 } else if (year >= 20 && year < 48) {
1089 guess = "ARC console";
1090 } else if (year >= 48 && year < 72) {
1092 guess = "Digital UNIX";
1093 #if defined(__mips__)
1094 } else if (year >= 72 && year < 74) {
1096 guess = "Digital DECstation";
1098 } else if (year >= 70) {
1100 guess = "Standard PC (1900)";
1104 printk(KERN_INFO "rtc: %s epoch (%lu) detected\n",
1108 if (rtc_has_irq == 0)
1111 spin_lock_irq(&rtc_lock);
1113 if (!hpet_set_periodic_freq(rtc_freq)) {
1115 * Initialize periodic frequency to CMOS reset default,
1118 CMOS_WRITE(((CMOS_READ(RTC_FREQ_SELECT) & 0xF0) | 0x06),
1121 spin_unlock_irq(&rtc_lock);
1125 (void) init_sysctl();
1127 printk(KERN_INFO "Real Time Clock Driver v" RTC_VERSION "\n");
1132 static void __exit rtc_exit(void)
1135 remove_proc_entry("driver/rtc", NULL);
1136 misc_deregister(&rtc_dev);
1138 #ifdef CONFIG_SPARC32
1140 free_irq(rtc_irq, &rtc_port);
1142 rtc_release_region();
1145 free_irq(RTC_IRQ, NULL);
1147 #endif /* CONFIG_SPARC32 */
1150 module_init(rtc_init);
1151 module_exit(rtc_exit);
1155 * At IRQ rates >= 4096Hz, an interrupt may get lost altogether.
1156 * (usually during an IDE disk interrupt, with IRQ unmasking off)
1157 * Since the interrupt handler doesn't get called, the IRQ status
1158 * byte doesn't get read, and the RTC stops generating interrupts.
1159 * A timer is set, and will call this function if/when that happens.
1160 * To get it out of this stalled state, we just read the status.
1161 * At least a jiffy of interrupts (rtc_freq/HZ) will have been lost.
1162 * (You *really* shouldn't be trying to use a non-realtime system
1163 * for something that requires a steady > 1KHz signal anyways.)
1166 static void rtc_dropped_irq(unsigned long data)
1170 spin_lock_irq(&rtc_lock);
1172 if (hpet_rtc_dropped_irq()) {
1173 spin_unlock_irq(&rtc_lock);
1177 /* Just in case someone disabled the timer from behind our back... */
1178 if (rtc_status & RTC_TIMER_ON)
1179 mod_timer(&rtc_irq_timer, jiffies + HZ/rtc_freq + 2*HZ/100);
1181 rtc_irq_data += ((rtc_freq/HZ)<<8);
1182 rtc_irq_data &= ~0xff;
1183 rtc_irq_data |= (CMOS_READ(RTC_INTR_FLAGS) & 0xF0); /* restart */
1187 spin_unlock_irq(&rtc_lock);
1189 if (printk_ratelimit()) {
1190 printk(KERN_WARNING "rtc: lost some interrupts at %ldHz.\n",
1194 /* Now we have new data */
1195 wake_up_interruptible(&rtc_wait);
1197 kill_fasync(&rtc_async_queue, SIGIO, POLL_IN);
1201 #ifdef CONFIG_PROC_FS
1203 * Info exported via "/proc/driver/rtc".
1206 static int rtc_proc_show(struct seq_file *seq, void *v)
1208 #define YN(bit) ((ctrl & bit) ? "yes" : "no")
1209 #define NY(bit) ((ctrl & bit) ? "no" : "yes")
1211 unsigned char batt, ctrl;
1214 spin_lock_irq(&rtc_lock);
1215 batt = CMOS_READ(RTC_VALID) & RTC_VRT;
1216 ctrl = CMOS_READ(RTC_CONTROL);
1218 spin_unlock_irq(&rtc_lock);
1221 rtc_get_rtc_time(&tm);
1224 * There is no way to tell if the luser has the RTC set for local
1225 * time or for Universal Standard Time (GMT). Probably local though.
1228 "rtc_time\t: %02d:%02d:%02d\n"
1229 "rtc_date\t: %04d-%02d-%02d\n"
1230 "rtc_epoch\t: %04lu\n",
1231 tm.tm_hour, tm.tm_min, tm.tm_sec,
1232 tm.tm_year + 1900, tm.tm_mon + 1, tm.tm_mday, epoch);
1234 get_rtc_alm_time(&tm);
1237 * We implicitly assume 24hr mode here. Alarm values >= 0xc0 will
1238 * match any value for that particular field. Values that are
1239 * greater than a valid time, but less than 0xc0 shouldn't appear.
1241 seq_puts(seq, "alarm\t\t: ");
1242 if (tm.tm_hour <= 24)
1243 seq_printf(seq, "%02d:", tm.tm_hour);
1245 seq_puts(seq, "**:");
1247 if (tm.tm_min <= 59)
1248 seq_printf(seq, "%02d:", tm.tm_min);
1250 seq_puts(seq, "**:");
1252 if (tm.tm_sec <= 59)
1253 seq_printf(seq, "%02d\n", tm.tm_sec);
1255 seq_puts(seq, "**\n");
1258 "DST_enable\t: %s\n"
1261 "square_wave\t: %s\n"
1263 "update_IRQ\t: %s\n"
1264 "periodic_IRQ\t: %s\n"
1265 "periodic_freq\t: %ld\n"
1266 "batt_status\t: %s\n",
1275 batt ? "okay" : "dead");
1282 static int rtc_proc_open(struct inode *inode, struct file *file)
1284 return single_open(file, rtc_proc_show, NULL);
1288 void rtc_get_rtc_time(struct rtc_time *rtc_tm)
1290 unsigned long uip_watchdog = jiffies, flags;
1292 #ifdef CONFIG_MACH_DECSTATION
1293 unsigned int real_year;
1297 * read RTC once any update in progress is done. The update
1298 * can take just over 2ms. We wait 20ms. There is no need to
1299 * to poll-wait (up to 1s - eeccch) for the falling edge of RTC_UIP.
1300 * If you need to know *exactly* when a second has started, enable
1301 * periodic update complete interrupts, (via ioctl) and then
1302 * immediately read /dev/rtc which will block until you get the IRQ.
1303 * Once the read clears, read the RTC time (again via ioctl). Easy.
1306 while (rtc_is_updating() != 0 && jiffies - uip_watchdog < 2*HZ/100)
1310 * Only the values that we read from the RTC are set. We leave
1311 * tm_wday, tm_yday and tm_isdst untouched. Note that while the
1312 * RTC has RTC_DAY_OF_WEEK, we should usually ignore it, as it is
1313 * only updated by the RTC when initially set to a non-zero value.
1315 spin_lock_irqsave(&rtc_lock, flags);
1316 rtc_tm->tm_sec = CMOS_READ(RTC_SECONDS);
1317 rtc_tm->tm_min = CMOS_READ(RTC_MINUTES);
1318 rtc_tm->tm_hour = CMOS_READ(RTC_HOURS);
1319 rtc_tm->tm_mday = CMOS_READ(RTC_DAY_OF_MONTH);
1320 rtc_tm->tm_mon = CMOS_READ(RTC_MONTH);
1321 rtc_tm->tm_year = CMOS_READ(RTC_YEAR);
1322 /* Only set from 2.6.16 onwards */
1323 rtc_tm->tm_wday = CMOS_READ(RTC_DAY_OF_WEEK);
1325 #ifdef CONFIG_MACH_DECSTATION
1326 real_year = CMOS_READ(RTC_DEC_YEAR);
1328 ctrl = CMOS_READ(RTC_CONTROL);
1329 spin_unlock_irqrestore(&rtc_lock, flags);
1331 if (!(ctrl & RTC_DM_BINARY) || RTC_ALWAYS_BCD) {
1332 BCD_TO_BIN(rtc_tm->tm_sec);
1333 BCD_TO_BIN(rtc_tm->tm_min);
1334 BCD_TO_BIN(rtc_tm->tm_hour);
1335 BCD_TO_BIN(rtc_tm->tm_mday);
1336 BCD_TO_BIN(rtc_tm->tm_mon);
1337 BCD_TO_BIN(rtc_tm->tm_year);
1338 BCD_TO_BIN(rtc_tm->tm_wday);
1341 #ifdef CONFIG_MACH_DECSTATION
1342 rtc_tm->tm_year += real_year - 72;
1346 * Account for differences between how the RTC uses the values
1347 * and how they are defined in a struct rtc_time;
1349 rtc_tm->tm_year += epoch - 1900;
1350 if (rtc_tm->tm_year <= 69)
1351 rtc_tm->tm_year += 100;
1356 static void get_rtc_alm_time(struct rtc_time *alm_tm)
1361 * Only the values that we read from the RTC are set. That
1362 * means only tm_hour, tm_min, and tm_sec.
1364 spin_lock_irq(&rtc_lock);
1365 alm_tm->tm_sec = CMOS_READ(RTC_SECONDS_ALARM);
1366 alm_tm->tm_min = CMOS_READ(RTC_MINUTES_ALARM);
1367 alm_tm->tm_hour = CMOS_READ(RTC_HOURS_ALARM);
1368 ctrl = CMOS_READ(RTC_CONTROL);
1369 spin_unlock_irq(&rtc_lock);
1371 if (!(ctrl & RTC_DM_BINARY) || RTC_ALWAYS_BCD) {
1372 BCD_TO_BIN(alm_tm->tm_sec);
1373 BCD_TO_BIN(alm_tm->tm_min);
1374 BCD_TO_BIN(alm_tm->tm_hour);
1380 * Used to disable/enable interrupts for any one of UIE, AIE, PIE.
1381 * Rumour has it that if you frob the interrupt enable/disable
1382 * bits in RTC_CONTROL, you should read RTC_INTR_FLAGS, to
1383 * ensure you actually start getting interrupts. Probably for
1384 * compatibility with older/broken chipset RTC implementations.
1385 * We also clear out any old irq data after an ioctl() that
1386 * meddles with the interrupt enable/disable bits.
1389 static void mask_rtc_irq_bit_locked(unsigned char bit)
1393 if (hpet_mask_rtc_irq_bit(bit))
1395 val = CMOS_READ(RTC_CONTROL);
1397 CMOS_WRITE(val, RTC_CONTROL);
1398 CMOS_READ(RTC_INTR_FLAGS);
1403 static void set_rtc_irq_bit_locked(unsigned char bit)
1407 if (hpet_set_rtc_irq_bit(bit))
1409 val = CMOS_READ(RTC_CONTROL);
1411 CMOS_WRITE(val, RTC_CONTROL);
1412 CMOS_READ(RTC_INTR_FLAGS);
1418 MODULE_AUTHOR("Paul Gortmaker");
1419 MODULE_LICENSE("GPL");
1420 MODULE_ALIAS_MISCDEV(RTC_MINOR);