2 * RTC class driver for "CMOS RTC": PCs, ACPI, etc
4 * Copyright (C) 1996 Paul Gortmaker (drivers/char/rtc.c)
5 * Copyright (C) 2006 David Brownell (convert to new framework)
7 * This program is free software; you can redistribute it and/or
8 * modify it under the terms of the GNU General Public License
9 * as published by the Free Software Foundation; either version
10 * 2 of the License, or (at your option) any later version.
14 * The original "cmos clock" chip was an MC146818 chip, now obsolete.
15 * That defined the register interface now provided by all PCs, some
16 * non-PC systems, and incorporated into ACPI. Modern PC chipsets
17 * integrate an MC146818 clone in their southbridge, and boards use
18 * that instead of discrete clones like the DS12887 or M48T86. There
19 * are also clones that connect using the LPC bus.
21 * That register API is also used directly by various other drivers
22 * (notably for integrated NVRAM), infrastructure (x86 has code to
23 * bypass the RTC framework, directly reading the RTC during boot
24 * and updating minutes/seconds for systems using NTP synch) and
25 * utilities (like userspace 'hwclock', if no /dev node exists).
27 * So **ALL** calls to CMOS_READ and CMOS_WRITE must be done with
28 * interrupts disabled, holding the global rtc_lock, to exclude those
29 * other drivers and utilities on correctly configured systems.
32 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
34 #include <linux/kernel.h>
35 #include <linux/module.h>
36 #include <linux/init.h>
37 #include <linux/interrupt.h>
38 #include <linux/spinlock.h>
39 #include <linux/platform_device.h>
40 #include <linux/log2.h>
43 #include <linux/of_platform.h>
45 /* this is for "generic access to PC-style RTC" using CMOS_READ/CMOS_WRITE */
46 #include <linux/mc146818rtc.h>
49 struct rtc_device *rtc;
52 struct resource *iomem;
53 time64_t alarm_expires;
55 void (*wake_on)(struct device *);
56 void (*wake_off)(struct device *);
61 /* newer hardware extends the original register set */
66 struct rtc_wkalrm saved_wkalrm;
69 /* both platform and pnp busses use negative numbers for invalid irqs */
70 #define is_valid_irq(n) ((n) > 0)
72 static const char driver_name[] = "rtc_cmos";
74 /* The RTC_INTR register may have e.g. RTC_PF set even if RTC_PIE is clear;
75 * always mask it against the irq enable bits in RTC_CONTROL. Bit values
76 * are the same: PF==PIE, AF=AIE, UF=UIE; so RTC_IRQMASK works with both.
78 #define RTC_IRQMASK (RTC_PF | RTC_AF | RTC_UF)
80 static inline int is_intr(u8 rtc_intr)
82 if (!(rtc_intr & RTC_IRQF))
84 return rtc_intr & RTC_IRQMASK;
87 /*----------------------------------------------------------------*/
89 /* Much modern x86 hardware has HPETs (10+ MHz timers) which, because
90 * many BIOS programmers don't set up "sane mode" IRQ routing, are mostly
91 * used in a broken "legacy replacement" mode. The breakage includes
92 * HPET #1 hijacking the IRQ for this RTC, and being unavailable for
95 * When that broken mode is in use, platform glue provides a partial
96 * emulation of hardware RTC IRQ facilities using HPET #1. We don't
97 * want to use HPET for anything except those IRQs though...
99 #ifdef CONFIG_HPET_EMULATE_RTC
100 #include <asm/hpet.h>
103 static inline int is_hpet_enabled(void)
108 static inline int hpet_mask_rtc_irq_bit(unsigned long mask)
113 static inline int hpet_set_rtc_irq_bit(unsigned long mask)
119 hpet_set_alarm_time(unsigned char hrs, unsigned char min, unsigned char sec)
124 static inline int hpet_set_periodic_freq(unsigned long freq)
129 static inline int hpet_rtc_dropped_irq(void)
134 static inline int hpet_rtc_timer_init(void)
139 extern irq_handler_t hpet_rtc_interrupt;
141 static inline int hpet_register_irq_handler(irq_handler_t handler)
146 static inline int hpet_unregister_irq_handler(irq_handler_t handler)
153 /*----------------------------------------------------------------*/
157 /* Most newer x86 systems have two register banks, the first used
158 * for RTC and NVRAM and the second only for NVRAM. Caller must
159 * own rtc_lock ... and we won't worry about access during NMI.
161 #define can_bank2 true
163 static inline unsigned char cmos_read_bank2(unsigned char addr)
165 outb(addr, RTC_PORT(2));
166 return inb(RTC_PORT(3));
169 static inline void cmos_write_bank2(unsigned char val, unsigned char addr)
171 outb(addr, RTC_PORT(2));
172 outb(val, RTC_PORT(3));
177 #define can_bank2 false
179 static inline unsigned char cmos_read_bank2(unsigned char addr)
184 static inline void cmos_write_bank2(unsigned char val, unsigned char addr)
190 /*----------------------------------------------------------------*/
192 static int cmos_read_time(struct device *dev, struct rtc_time *t)
194 /* REVISIT: if the clock has a "century" register, use
195 * that instead of the heuristic in mc146818_get_time().
196 * That'll make Y3K compatility (year > 2070) easy!
198 mc146818_get_time(t);
202 static int cmos_set_time(struct device *dev, struct rtc_time *t)
204 /* REVISIT: set the "century" register if available
206 * NOTE: this ignores the issue whereby updating the seconds
207 * takes effect exactly 500ms after we write the register.
208 * (Also queueing and other delays before we get this far.)
210 return mc146818_set_time(t);
213 static int cmos_read_alarm(struct device *dev, struct rtc_wkalrm *t)
215 struct cmos_rtc *cmos = dev_get_drvdata(dev);
216 unsigned char rtc_control;
218 if (!is_valid_irq(cmos->irq))
221 /* Basic alarms only support hour, minute, and seconds fields.
222 * Some also support day and month, for alarms up to a year in
226 spin_lock_irq(&rtc_lock);
227 t->time.tm_sec = CMOS_READ(RTC_SECONDS_ALARM);
228 t->time.tm_min = CMOS_READ(RTC_MINUTES_ALARM);
229 t->time.tm_hour = CMOS_READ(RTC_HOURS_ALARM);
231 if (cmos->day_alrm) {
232 /* ignore upper bits on readback per ACPI spec */
233 t->time.tm_mday = CMOS_READ(cmos->day_alrm) & 0x3f;
234 if (!t->time.tm_mday)
235 t->time.tm_mday = -1;
237 if (cmos->mon_alrm) {
238 t->time.tm_mon = CMOS_READ(cmos->mon_alrm);
244 rtc_control = CMOS_READ(RTC_CONTROL);
245 spin_unlock_irq(&rtc_lock);
247 if (!(rtc_control & RTC_DM_BINARY) || RTC_ALWAYS_BCD) {
248 if (((unsigned)t->time.tm_sec) < 0x60)
249 t->time.tm_sec = bcd2bin(t->time.tm_sec);
252 if (((unsigned)t->time.tm_min) < 0x60)
253 t->time.tm_min = bcd2bin(t->time.tm_min);
256 if (((unsigned)t->time.tm_hour) < 0x24)
257 t->time.tm_hour = bcd2bin(t->time.tm_hour);
259 t->time.tm_hour = -1;
261 if (cmos->day_alrm) {
262 if (((unsigned)t->time.tm_mday) <= 0x31)
263 t->time.tm_mday = bcd2bin(t->time.tm_mday);
265 t->time.tm_mday = -1;
267 if (cmos->mon_alrm) {
268 if (((unsigned)t->time.tm_mon) <= 0x12)
269 t->time.tm_mon = bcd2bin(t->time.tm_mon)-1;
276 t->enabled = !!(rtc_control & RTC_AIE);
282 static void cmos_checkintr(struct cmos_rtc *cmos, unsigned char rtc_control)
284 unsigned char rtc_intr;
286 /* NOTE after changing RTC_xIE bits we always read INTR_FLAGS;
287 * allegedly some older rtcs need that to handle irqs properly
289 rtc_intr = CMOS_READ(RTC_INTR_FLAGS);
291 if (is_hpet_enabled())
294 rtc_intr &= (rtc_control & RTC_IRQMASK) | RTC_IRQF;
295 if (is_intr(rtc_intr))
296 rtc_update_irq(cmos->rtc, 1, rtc_intr);
299 static void cmos_irq_enable(struct cmos_rtc *cmos, unsigned char mask)
301 unsigned char rtc_control;
303 /* flush any pending IRQ status, notably for update irqs,
304 * before we enable new IRQs
306 rtc_control = CMOS_READ(RTC_CONTROL);
307 cmos_checkintr(cmos, rtc_control);
310 CMOS_WRITE(rtc_control, RTC_CONTROL);
311 hpet_set_rtc_irq_bit(mask);
313 cmos_checkintr(cmos, rtc_control);
316 static void cmos_irq_disable(struct cmos_rtc *cmos, unsigned char mask)
318 unsigned char rtc_control;
320 rtc_control = CMOS_READ(RTC_CONTROL);
321 rtc_control &= ~mask;
322 CMOS_WRITE(rtc_control, RTC_CONTROL);
323 hpet_mask_rtc_irq_bit(mask);
325 cmos_checkintr(cmos, rtc_control);
328 static int cmos_set_alarm(struct device *dev, struct rtc_wkalrm *t)
330 struct cmos_rtc *cmos = dev_get_drvdata(dev);
331 unsigned char mon, mday, hrs, min, sec, rtc_control;
333 if (!is_valid_irq(cmos->irq))
336 mon = t->time.tm_mon + 1;
337 mday = t->time.tm_mday;
338 hrs = t->time.tm_hour;
339 min = t->time.tm_min;
340 sec = t->time.tm_sec;
342 rtc_control = CMOS_READ(RTC_CONTROL);
343 if (!(rtc_control & RTC_DM_BINARY) || RTC_ALWAYS_BCD) {
344 /* Writing 0xff means "don't care" or "match all". */
345 mon = (mon <= 12) ? bin2bcd(mon) : 0xff;
346 mday = (mday >= 1 && mday <= 31) ? bin2bcd(mday) : 0xff;
347 hrs = (hrs < 24) ? bin2bcd(hrs) : 0xff;
348 min = (min < 60) ? bin2bcd(min) : 0xff;
349 sec = (sec < 60) ? bin2bcd(sec) : 0xff;
352 spin_lock_irq(&rtc_lock);
354 /* next rtc irq must not be from previous alarm setting */
355 cmos_irq_disable(cmos, RTC_AIE);
358 CMOS_WRITE(hrs, RTC_HOURS_ALARM);
359 CMOS_WRITE(min, RTC_MINUTES_ALARM);
360 CMOS_WRITE(sec, RTC_SECONDS_ALARM);
362 /* the system may support an "enhanced" alarm */
363 if (cmos->day_alrm) {
364 CMOS_WRITE(mday, cmos->day_alrm);
366 CMOS_WRITE(mon, cmos->mon_alrm);
369 /* FIXME the HPET alarm glue currently ignores day_alrm
372 hpet_set_alarm_time(t->time.tm_hour, t->time.tm_min, t->time.tm_sec);
375 cmos_irq_enable(cmos, RTC_AIE);
377 spin_unlock_irq(&rtc_lock);
379 cmos->alarm_expires = rtc_tm_to_time64(&t->time);
384 static int cmos_alarm_irq_enable(struct device *dev, unsigned int enabled)
386 struct cmos_rtc *cmos = dev_get_drvdata(dev);
389 if (!is_valid_irq(cmos->irq))
392 spin_lock_irqsave(&rtc_lock, flags);
395 cmos_irq_enable(cmos, RTC_AIE);
397 cmos_irq_disable(cmos, RTC_AIE);
399 spin_unlock_irqrestore(&rtc_lock, flags);
403 #if IS_ENABLED(CONFIG_RTC_INTF_PROC)
405 static int cmos_procfs(struct device *dev, struct seq_file *seq)
407 struct cmos_rtc *cmos = dev_get_drvdata(dev);
408 unsigned char rtc_control, valid;
410 spin_lock_irq(&rtc_lock);
411 rtc_control = CMOS_READ(RTC_CONTROL);
412 valid = CMOS_READ(RTC_VALID);
413 spin_unlock_irq(&rtc_lock);
415 /* NOTE: at least ICH6 reports battery status using a different
416 * (non-RTC) bit; and SQWE is ignored on many current systems.
419 "periodic_IRQ\t: %s\n"
421 "HPET_emulated\t: %s\n"
422 // "square_wave\t: %s\n"
425 "periodic_freq\t: %d\n"
426 "batt_status\t: %s\n",
427 (rtc_control & RTC_PIE) ? "yes" : "no",
428 (rtc_control & RTC_UIE) ? "yes" : "no",
429 is_hpet_enabled() ? "yes" : "no",
430 // (rtc_control & RTC_SQWE) ? "yes" : "no",
431 (rtc_control & RTC_DM_BINARY) ? "no" : "yes",
432 (rtc_control & RTC_DST_EN) ? "yes" : "no",
434 (valid & RTC_VRT) ? "okay" : "dead");
440 #define cmos_procfs NULL
443 static const struct rtc_class_ops cmos_rtc_ops = {
444 .read_time = cmos_read_time,
445 .set_time = cmos_set_time,
446 .read_alarm = cmos_read_alarm,
447 .set_alarm = cmos_set_alarm,
449 .alarm_irq_enable = cmos_alarm_irq_enable,
452 /*----------------------------------------------------------------*/
455 * All these chips have at least 64 bytes of address space, shared by
456 * RTC registers and NVRAM. Most of those bytes of NVRAM are used
457 * by boot firmware. Modern chips have 128 or 256 bytes.
460 #define NVRAM_OFFSET (RTC_REG_D + 1)
463 cmos_nvram_read(struct file *filp, struct kobject *kobj,
464 struct bin_attribute *attr,
465 char *buf, loff_t off, size_t count)
470 spin_lock_irq(&rtc_lock);
471 for (retval = 0; count; count--, off++, retval++) {
473 *buf++ = CMOS_READ(off);
475 *buf++ = cmos_read_bank2(off);
479 spin_unlock_irq(&rtc_lock);
485 cmos_nvram_write(struct file *filp, struct kobject *kobj,
486 struct bin_attribute *attr,
487 char *buf, loff_t off, size_t count)
489 struct cmos_rtc *cmos;
492 cmos = dev_get_drvdata(container_of(kobj, struct device, kobj));
494 /* NOTE: on at least PCs and Ataris, the boot firmware uses a
495 * checksum on part of the NVRAM data. That's currently ignored
496 * here. If userspace is smart enough to know what fields of
497 * NVRAM to update, updating checksums is also part of its job.
500 spin_lock_irq(&rtc_lock);
501 for (retval = 0; count; count--, off++, retval++) {
502 /* don't trash RTC registers */
503 if (off == cmos->day_alrm
504 || off == cmos->mon_alrm
505 || off == cmos->century)
508 CMOS_WRITE(*buf++, off);
510 cmos_write_bank2(*buf++, off);
514 spin_unlock_irq(&rtc_lock);
519 static struct bin_attribute nvram = {
522 .mode = S_IRUGO | S_IWUSR,
525 .read = cmos_nvram_read,
526 .write = cmos_nvram_write,
527 /* size gets set up later */
530 /*----------------------------------------------------------------*/
532 static struct cmos_rtc cmos_rtc;
534 static irqreturn_t cmos_interrupt(int irq, void *p)
539 spin_lock(&rtc_lock);
541 /* When the HPET interrupt handler calls us, the interrupt
542 * status is passed as arg1 instead of the irq number. But
543 * always clear irq status, even when HPET is in the way.
545 * Note that HPET and RTC are almost certainly out of phase,
546 * giving different IRQ status ...
548 irqstat = CMOS_READ(RTC_INTR_FLAGS);
549 rtc_control = CMOS_READ(RTC_CONTROL);
550 if (is_hpet_enabled())
551 irqstat = (unsigned long)irq & 0xF0;
553 /* If we were suspended, RTC_CONTROL may not be accurate since the
554 * bios may have cleared it.
556 if (!cmos_rtc.suspend_ctrl)
557 irqstat &= (rtc_control & RTC_IRQMASK) | RTC_IRQF;
559 irqstat &= (cmos_rtc.suspend_ctrl & RTC_IRQMASK) | RTC_IRQF;
561 /* All Linux RTC alarms should be treated as if they were oneshot.
562 * Similar code may be needed in system wakeup paths, in case the
563 * alarm woke the system.
565 if (irqstat & RTC_AIE) {
566 cmos_rtc.suspend_ctrl &= ~RTC_AIE;
567 rtc_control &= ~RTC_AIE;
568 CMOS_WRITE(rtc_control, RTC_CONTROL);
569 hpet_mask_rtc_irq_bit(RTC_AIE);
570 CMOS_READ(RTC_INTR_FLAGS);
572 spin_unlock(&rtc_lock);
574 if (is_intr(irqstat)) {
575 rtc_update_irq(p, 1, irqstat);
585 #define INITSECTION __init
588 static int INITSECTION
589 cmos_do_probe(struct device *dev, struct resource *ports, int rtc_irq)
591 struct cmos_rtc_board_info *info = dev_get_platdata(dev);
593 unsigned char rtc_control;
594 unsigned address_space;
597 /* there can be only one ... */
604 /* Claim I/O ports ASAP, minimizing conflict with legacy driver.
606 * REVISIT non-x86 systems may instead use memory space resources
607 * (needing ioremap etc), not i/o space resources like this ...
610 ports = request_region(ports->start, resource_size(ports),
613 ports = request_mem_region(ports->start, resource_size(ports),
616 dev_dbg(dev, "i/o registers already in use\n");
620 cmos_rtc.irq = rtc_irq;
621 cmos_rtc.iomem = ports;
623 /* Heuristic to deduce NVRAM size ... do what the legacy NVRAM
624 * driver did, but don't reject unknown configs. Old hardware
625 * won't address 128 bytes. Newer chips have multiple banks,
626 * though they may not be listed in one I/O resource.
628 #if defined(CONFIG_ATARI)
630 #elif defined(__i386__) || defined(__x86_64__) || defined(__arm__) \
631 || defined(__sparc__) || defined(__mips__) \
632 || defined(__powerpc__) || defined(CONFIG_MN10300)
635 #warning Assuming 128 bytes of RTC+NVRAM address space, not 64 bytes.
638 if (can_bank2 && ports->end > (ports->start + 1))
641 /* For ACPI systems extension info comes from the FADT. On others,
642 * board specific setup provides it as appropriate. Systems where
643 * the alarm IRQ isn't automatically a wakeup IRQ (like ACPI, and
644 * some almost-clones) can provide hooks to make that behave.
646 * Note that ACPI doesn't preclude putting these registers into
647 * "extended" areas of the chip, including some that we won't yet
648 * expect CMOS_READ and friends to handle.
653 if (info->address_space)
654 address_space = info->address_space;
656 if (info->rtc_day_alarm && info->rtc_day_alarm < 128)
657 cmos_rtc.day_alrm = info->rtc_day_alarm;
658 if (info->rtc_mon_alarm && info->rtc_mon_alarm < 128)
659 cmos_rtc.mon_alrm = info->rtc_mon_alarm;
660 if (info->rtc_century && info->rtc_century < 128)
661 cmos_rtc.century = info->rtc_century;
663 if (info->wake_on && info->wake_off) {
664 cmos_rtc.wake_on = info->wake_on;
665 cmos_rtc.wake_off = info->wake_off;
670 dev_set_drvdata(dev, &cmos_rtc);
672 cmos_rtc.rtc = rtc_device_register(driver_name, dev,
673 &cmos_rtc_ops, THIS_MODULE);
674 if (IS_ERR(cmos_rtc.rtc)) {
675 retval = PTR_ERR(cmos_rtc.rtc);
679 rename_region(ports, dev_name(&cmos_rtc.rtc->dev));
681 spin_lock_irq(&rtc_lock);
683 if (!(flags & CMOS_RTC_FLAGS_NOFREQ)) {
684 /* force periodic irq to CMOS reset default of 1024Hz;
686 * REVISIT it's been reported that at least one x86_64 ALI
687 * mobo doesn't use 32KHz here ... for portability we might
688 * need to do something about other clock frequencies.
690 cmos_rtc.rtc->irq_freq = 1024;
691 hpet_set_periodic_freq(cmos_rtc.rtc->irq_freq);
692 CMOS_WRITE(RTC_REF_CLCK_32KHZ | 0x06, RTC_FREQ_SELECT);
696 if (is_valid_irq(rtc_irq))
697 cmos_irq_disable(&cmos_rtc, RTC_PIE | RTC_AIE | RTC_UIE);
699 rtc_control = CMOS_READ(RTC_CONTROL);
701 spin_unlock_irq(&rtc_lock);
704 * <asm-generic/rtc.h> doesn't know 12-hour mode either.
706 if (is_valid_irq(rtc_irq) && !(rtc_control & RTC_24H)) {
707 dev_warn(dev, "only 24-hr supported\n");
712 hpet_rtc_timer_init();
714 if (is_valid_irq(rtc_irq)) {
715 irq_handler_t rtc_cmos_int_handler;
717 if (is_hpet_enabled()) {
718 rtc_cmos_int_handler = hpet_rtc_interrupt;
719 retval = hpet_register_irq_handler(cmos_interrupt);
721 hpet_mask_rtc_irq_bit(RTC_IRQMASK);
722 dev_warn(dev, "hpet_register_irq_handler "
723 " failed in rtc_init().");
727 rtc_cmos_int_handler = cmos_interrupt;
729 retval = request_irq(rtc_irq, rtc_cmos_int_handler,
730 IRQF_SHARED, dev_name(&cmos_rtc.rtc->dev),
733 dev_dbg(dev, "IRQ %d is already in use\n", rtc_irq);
738 /* export at least the first block of NVRAM */
739 nvram.size = address_space - NVRAM_OFFSET;
740 retval = sysfs_create_bin_file(&dev->kobj, &nvram);
742 dev_dbg(dev, "can't create nvram file? %d\n", retval);
746 dev_info(dev, "%s%s, %zd bytes nvram%s\n",
747 !is_valid_irq(rtc_irq) ? "no alarms" :
748 cmos_rtc.mon_alrm ? "alarms up to one year" :
749 cmos_rtc.day_alrm ? "alarms up to one month" :
750 "alarms up to one day",
751 cmos_rtc.century ? ", y3k" : "",
753 is_hpet_enabled() ? ", hpet irqs" : "");
758 if (is_valid_irq(rtc_irq))
759 free_irq(rtc_irq, cmos_rtc.rtc);
762 rtc_device_unregister(cmos_rtc.rtc);
765 release_region(ports->start, resource_size(ports));
767 release_mem_region(ports->start, resource_size(ports));
771 static void cmos_do_shutdown(int rtc_irq)
773 spin_lock_irq(&rtc_lock);
774 if (is_valid_irq(rtc_irq))
775 cmos_irq_disable(&cmos_rtc, RTC_IRQMASK);
776 spin_unlock_irq(&rtc_lock);
779 static void __exit cmos_do_remove(struct device *dev)
781 struct cmos_rtc *cmos = dev_get_drvdata(dev);
782 struct resource *ports;
784 cmos_do_shutdown(cmos->irq);
786 sysfs_remove_bin_file(&dev->kobj, &nvram);
788 if (is_valid_irq(cmos->irq)) {
789 free_irq(cmos->irq, cmos->rtc);
790 hpet_unregister_irq_handler(cmos_interrupt);
793 rtc_device_unregister(cmos->rtc);
798 release_region(ports->start, resource_size(ports));
800 release_mem_region(ports->start, resource_size(ports));
806 static int cmos_aie_poweroff(struct device *dev)
808 struct cmos_rtc *cmos = dev_get_drvdata(dev);
812 unsigned char rtc_control;
814 if (!cmos->alarm_expires)
817 spin_lock_irq(&rtc_lock);
818 rtc_control = CMOS_READ(RTC_CONTROL);
819 spin_unlock_irq(&rtc_lock);
821 /* We only care about the situation where AIE is disabled. */
822 if (rtc_control & RTC_AIE)
825 cmos_read_time(dev, &now);
826 t_now = rtc_tm_to_time64(&now);
829 * When enabling "RTC wake-up" in BIOS setup, the machine reboots
830 * automatically right after shutdown on some buggy boxes.
831 * This automatic rebooting issue won't happen when the alarm
832 * time is larger than now+1 seconds.
834 * If the alarm time is equal to now+1 seconds, the issue can be
835 * prevented by cancelling the alarm.
837 if (cmos->alarm_expires == t_now + 1) {
838 struct rtc_wkalrm alarm;
840 /* Cancel the AIE timer by configuring the past time. */
841 rtc_time64_to_tm(t_now - 1, &alarm.time);
843 retval = cmos_set_alarm(dev, &alarm);
844 } else if (cmos->alarm_expires > t_now + 1) {
851 static int cmos_suspend(struct device *dev)
853 struct cmos_rtc *cmos = dev_get_drvdata(dev);
856 /* only the alarm might be a wakeup event source */
857 spin_lock_irq(&rtc_lock);
858 cmos->suspend_ctrl = tmp = CMOS_READ(RTC_CONTROL);
859 if (tmp & (RTC_PIE|RTC_AIE|RTC_UIE)) {
862 if (device_may_wakeup(dev))
863 mask = RTC_IRQMASK & ~RTC_AIE;
867 CMOS_WRITE(tmp, RTC_CONTROL);
868 hpet_mask_rtc_irq_bit(mask);
870 cmos_checkintr(cmos, tmp);
872 spin_unlock_irq(&rtc_lock);
875 cmos->enabled_wake = 1;
879 enable_irq_wake(cmos->irq);
882 cmos_read_alarm(dev, &cmos->saved_wkalrm);
884 dev_dbg(dev, "suspend%s, ctrl %02x\n",
885 (tmp & RTC_AIE) ? ", alarm may wake" : "",
891 /* We want RTC alarms to wake us from e.g. ACPI G2/S5 "soft off", even
892 * after a detour through G3 "mechanical off", although the ACPI spec
893 * says wakeup should only work from G1/S4 "hibernate". To most users,
894 * distinctions between S4 and S5 are pointless. So when the hardware
895 * allows, don't draw that distinction.
897 static inline int cmos_poweroff(struct device *dev)
899 if (!IS_ENABLED(CONFIG_PM))
902 return cmos_suspend(dev);
905 static void cmos_check_wkalrm(struct device *dev)
907 struct cmos_rtc *cmos = dev_get_drvdata(dev);
908 struct rtc_wkalrm current_alarm;
909 time64_t t_current_expires;
910 time64_t t_saved_expires;
912 cmos_read_alarm(dev, ¤t_alarm);
913 t_current_expires = rtc_tm_to_time64(¤t_alarm.time);
914 t_saved_expires = rtc_tm_to_time64(&cmos->saved_wkalrm.time);
915 if (t_current_expires != t_saved_expires ||
916 cmos->saved_wkalrm.enabled != current_alarm.enabled) {
917 cmos_set_alarm(dev, &cmos->saved_wkalrm);
921 static void cmos_check_acpi_rtc_status(struct device *dev,
922 unsigned char *rtc_control);
924 static int __maybe_unused cmos_resume(struct device *dev)
926 struct cmos_rtc *cmos = dev_get_drvdata(dev);
929 if (cmos->enabled_wake) {
933 disable_irq_wake(cmos->irq);
934 cmos->enabled_wake = 0;
937 /* The BIOS might have changed the alarm, restore it */
938 cmos_check_wkalrm(dev);
940 spin_lock_irq(&rtc_lock);
941 tmp = cmos->suspend_ctrl;
942 cmos->suspend_ctrl = 0;
943 /* re-enable any irqs previously active */
944 if (tmp & RTC_IRQMASK) {
947 if (device_may_wakeup(dev))
948 hpet_rtc_timer_init();
951 CMOS_WRITE(tmp, RTC_CONTROL);
952 hpet_set_rtc_irq_bit(tmp & RTC_IRQMASK);
954 mask = CMOS_READ(RTC_INTR_FLAGS);
955 mask &= (tmp & RTC_IRQMASK) | RTC_IRQF;
956 if (!is_hpet_enabled() || !is_intr(mask))
959 /* force one-shot behavior if HPET blocked
960 * the wake alarm's irq
962 rtc_update_irq(cmos->rtc, 1, mask);
964 hpet_mask_rtc_irq_bit(RTC_AIE);
965 } while (mask & RTC_AIE);
968 cmos_check_acpi_rtc_status(dev, &tmp);
970 spin_unlock_irq(&rtc_lock);
972 dev_dbg(dev, "resume, ctrl %02x\n", tmp);
977 static SIMPLE_DEV_PM_OPS(cmos_pm_ops, cmos_suspend, cmos_resume);
979 /*----------------------------------------------------------------*/
981 /* On non-x86 systems, a "CMOS" RTC lives most naturally on platform_bus.
982 * ACPI systems always list these as PNPACPI devices, and pre-ACPI PCs
983 * probably list them in similar PNPBIOS tables; so PNP is more common.
985 * We don't use legacy "poke at the hardware" probing. Ancient PCs that
986 * predate even PNPBIOS should set up platform_bus devices.
991 #include <linux/acpi.h>
993 static u32 rtc_handler(void *context)
995 struct device *dev = context;
996 struct cmos_rtc *cmos = dev_get_drvdata(dev);
997 unsigned char rtc_control = 0;
998 unsigned char rtc_intr;
1000 spin_lock_irq(&rtc_lock);
1001 if (cmos_rtc.suspend_ctrl)
1002 rtc_control = CMOS_READ(RTC_CONTROL);
1003 if (rtc_control & RTC_AIE) {
1004 cmos_rtc.suspend_ctrl &= ~RTC_AIE;
1005 CMOS_WRITE(rtc_control, RTC_CONTROL);
1006 rtc_intr = CMOS_READ(RTC_INTR_FLAGS);
1007 rtc_update_irq(cmos->rtc, 1, rtc_intr);
1009 spin_unlock_irq(&rtc_lock);
1011 pm_wakeup_event(dev, 0);
1012 acpi_clear_event(ACPI_EVENT_RTC);
1013 acpi_disable_event(ACPI_EVENT_RTC, 0);
1014 return ACPI_INTERRUPT_HANDLED;
1017 static inline void rtc_wake_setup(struct device *dev)
1019 acpi_install_fixed_event_handler(ACPI_EVENT_RTC, rtc_handler, dev);
1021 * After the RTC handler is installed, the Fixed_RTC event should
1022 * be disabled. Only when the RTC alarm is set will it be enabled.
1024 acpi_clear_event(ACPI_EVENT_RTC);
1025 acpi_disable_event(ACPI_EVENT_RTC, 0);
1028 static void rtc_wake_on(struct device *dev)
1030 acpi_clear_event(ACPI_EVENT_RTC);
1031 acpi_enable_event(ACPI_EVENT_RTC, 0);
1034 static void rtc_wake_off(struct device *dev)
1036 acpi_disable_event(ACPI_EVENT_RTC, 0);
1039 /* Every ACPI platform has a mc146818 compatible "cmos rtc". Here we find
1040 * its device node and pass extra config data. This helps its driver use
1041 * capabilities that the now-obsolete mc146818 didn't have, and informs it
1042 * that this board's RTC is wakeup-capable (per ACPI spec).
1044 static struct cmos_rtc_board_info acpi_rtc_info;
1046 static void cmos_wake_setup(struct device *dev)
1051 rtc_wake_setup(dev);
1052 acpi_rtc_info.wake_on = rtc_wake_on;
1053 acpi_rtc_info.wake_off = rtc_wake_off;
1055 /* workaround bug in some ACPI tables */
1056 if (acpi_gbl_FADT.month_alarm && !acpi_gbl_FADT.day_alarm) {
1057 dev_dbg(dev, "bogus FADT month_alarm (%d)\n",
1058 acpi_gbl_FADT.month_alarm);
1059 acpi_gbl_FADT.month_alarm = 0;
1062 acpi_rtc_info.rtc_day_alarm = acpi_gbl_FADT.day_alarm;
1063 acpi_rtc_info.rtc_mon_alarm = acpi_gbl_FADT.month_alarm;
1064 acpi_rtc_info.rtc_century = acpi_gbl_FADT.century;
1066 /* NOTE: S4_RTC_WAKE is NOT currently useful to Linux */
1067 if (acpi_gbl_FADT.flags & ACPI_FADT_S4_RTC_WAKE)
1068 dev_info(dev, "RTC can wake from S4\n");
1070 dev->platform_data = &acpi_rtc_info;
1072 /* RTC always wakes from S1/S2/S3, and often S4/STD */
1073 device_init_wakeup(dev, 1);
1076 static void cmos_check_acpi_rtc_status(struct device *dev,
1077 unsigned char *rtc_control)
1079 struct cmos_rtc *cmos = dev_get_drvdata(dev);
1080 acpi_event_status rtc_status;
1083 if (acpi_gbl_FADT.flags & ACPI_FADT_FIXED_RTC)
1086 status = acpi_get_event_status(ACPI_EVENT_RTC, &rtc_status);
1087 if (ACPI_FAILURE(status)) {
1088 dev_err(dev, "Could not get RTC status\n");
1089 } else if (rtc_status & ACPI_EVENT_FLAG_SET) {
1091 *rtc_control &= ~RTC_AIE;
1092 CMOS_WRITE(*rtc_control, RTC_CONTROL);
1093 mask = CMOS_READ(RTC_INTR_FLAGS);
1094 rtc_update_irq(cmos->rtc, 1, mask);
1100 static void cmos_wake_setup(struct device *dev)
1104 static void cmos_check_acpi_rtc_status(struct device *dev,
1105 unsigned char *rtc_control)
1113 #include <linux/pnp.h>
1115 static int cmos_pnp_probe(struct pnp_dev *pnp, const struct pnp_device_id *id)
1117 cmos_wake_setup(&pnp->dev);
1119 if (pnp_port_start(pnp, 0) == 0x70 && !pnp_irq_valid(pnp, 0))
1120 /* Some machines contain a PNP entry for the RTC, but
1121 * don't define the IRQ. It should always be safe to
1122 * hardcode it in these cases
1124 return cmos_do_probe(&pnp->dev,
1125 pnp_get_resource(pnp, IORESOURCE_IO, 0), 8);
1127 return cmos_do_probe(&pnp->dev,
1128 pnp_get_resource(pnp, IORESOURCE_IO, 0),
1132 static void __exit cmos_pnp_remove(struct pnp_dev *pnp)
1134 cmos_do_remove(&pnp->dev);
1137 static void cmos_pnp_shutdown(struct pnp_dev *pnp)
1139 struct device *dev = &pnp->dev;
1140 struct cmos_rtc *cmos = dev_get_drvdata(dev);
1142 if (system_state == SYSTEM_POWER_OFF) {
1143 int retval = cmos_poweroff(dev);
1145 if (cmos_aie_poweroff(dev) < 0 && !retval)
1149 cmos_do_shutdown(cmos->irq);
1152 static const struct pnp_device_id rtc_ids[] = {
1153 { .id = "PNP0b00", },
1154 { .id = "PNP0b01", },
1155 { .id = "PNP0b02", },
1158 MODULE_DEVICE_TABLE(pnp, rtc_ids);
1160 static struct pnp_driver cmos_pnp_driver = {
1161 .name = (char *) driver_name,
1162 .id_table = rtc_ids,
1163 .probe = cmos_pnp_probe,
1164 .remove = __exit_p(cmos_pnp_remove),
1165 .shutdown = cmos_pnp_shutdown,
1167 /* flag ensures resume() gets called, and stops syslog spam */
1168 .flags = PNP_DRIVER_RES_DO_NOT_CHANGE,
1174 #endif /* CONFIG_PNP */
1177 static const struct of_device_id of_cmos_match[] = {
1179 .compatible = "motorola,mc146818",
1183 MODULE_DEVICE_TABLE(of, of_cmos_match);
1185 static __init void cmos_of_init(struct platform_device *pdev)
1187 struct device_node *node = pdev->dev.of_node;
1188 struct rtc_time time;
1195 val = of_get_property(node, "ctrl-reg", NULL);
1197 CMOS_WRITE(be32_to_cpup(val), RTC_CONTROL);
1199 val = of_get_property(node, "freq-reg", NULL);
1201 CMOS_WRITE(be32_to_cpup(val), RTC_FREQ_SELECT);
1203 cmos_read_time(&pdev->dev, &time);
1204 ret = rtc_valid_tm(&time);
1206 struct rtc_time def_time = {
1210 cmos_set_time(&pdev->dev, &def_time);
1214 static inline void cmos_of_init(struct platform_device *pdev) {}
1216 /*----------------------------------------------------------------*/
1218 /* Platform setup should have set up an RTC device, when PNP is
1219 * unavailable ... this could happen even on (older) PCs.
1222 static int __init cmos_platform_probe(struct platform_device *pdev)
1224 struct resource *resource;
1228 cmos_wake_setup(&pdev->dev);
1231 resource = platform_get_resource(pdev, IORESOURCE_IO, 0);
1233 resource = platform_get_resource(pdev, IORESOURCE_MEM, 0);
1234 irq = platform_get_irq(pdev, 0);
1238 return cmos_do_probe(&pdev->dev, resource, irq);
1241 static int __exit cmos_platform_remove(struct platform_device *pdev)
1243 cmos_do_remove(&pdev->dev);
1247 static void cmos_platform_shutdown(struct platform_device *pdev)
1249 struct device *dev = &pdev->dev;
1250 struct cmos_rtc *cmos = dev_get_drvdata(dev);
1252 if (system_state == SYSTEM_POWER_OFF) {
1253 int retval = cmos_poweroff(dev);
1255 if (cmos_aie_poweroff(dev) < 0 && !retval)
1259 cmos_do_shutdown(cmos->irq);
1262 /* work with hotplug and coldplug */
1263 MODULE_ALIAS("platform:rtc_cmos");
1265 static struct platform_driver cmos_platform_driver = {
1266 .remove = __exit_p(cmos_platform_remove),
1267 .shutdown = cmos_platform_shutdown,
1269 .name = driver_name,
1271 .of_match_table = of_match_ptr(of_cmos_match),
1276 static bool pnp_driver_registered;
1278 static bool platform_driver_registered;
1280 static int __init cmos_init(void)
1285 retval = pnp_register_driver(&cmos_pnp_driver);
1287 pnp_driver_registered = true;
1290 if (!cmos_rtc.dev) {
1291 retval = platform_driver_probe(&cmos_platform_driver,
1292 cmos_platform_probe);
1294 platform_driver_registered = true;
1301 if (pnp_driver_registered)
1302 pnp_unregister_driver(&cmos_pnp_driver);
1306 module_init(cmos_init);
1308 static void __exit cmos_exit(void)
1311 if (pnp_driver_registered)
1312 pnp_unregister_driver(&cmos_pnp_driver);
1314 if (platform_driver_registered)
1315 platform_driver_unregister(&cmos_platform_driver);
1317 module_exit(cmos_exit);
1320 MODULE_AUTHOR("David Brownell");
1321 MODULE_DESCRIPTION("Driver for PC-style 'CMOS' RTCs");
1322 MODULE_LICENSE("GPL");