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 #include <asm/i8259.h>
48 /* this is for "generic access to PC-style RTC" using CMOS_READ/CMOS_WRITE */
49 #include <linux/mc146818rtc.h>
52 struct rtc_device *rtc;
55 struct resource *iomem;
56 time64_t alarm_expires;
58 void (*wake_on)(struct device *);
59 void (*wake_off)(struct device *);
64 /* newer hardware extends the original register set */
69 struct rtc_wkalrm saved_wkalrm;
72 /* both platform and pnp busses use negative numbers for invalid irqs */
73 #define is_valid_irq(n) ((n) > 0)
75 static const char driver_name[] = "rtc_cmos";
77 /* The RTC_INTR register may have e.g. RTC_PF set even if RTC_PIE is clear;
78 * always mask it against the irq enable bits in RTC_CONTROL. Bit values
79 * are the same: PF==PIE, AF=AIE, UF=UIE; so RTC_IRQMASK works with both.
81 #define RTC_IRQMASK (RTC_PF | RTC_AF | RTC_UF)
83 static inline int is_intr(u8 rtc_intr)
85 if (!(rtc_intr & RTC_IRQF))
87 return rtc_intr & RTC_IRQMASK;
90 /*----------------------------------------------------------------*/
92 /* Much modern x86 hardware has HPETs (10+ MHz timers) which, because
93 * many BIOS programmers don't set up "sane mode" IRQ routing, are mostly
94 * used in a broken "legacy replacement" mode. The breakage includes
95 * HPET #1 hijacking the IRQ for this RTC, and being unavailable for
98 * When that broken mode is in use, platform glue provides a partial
99 * emulation of hardware RTC IRQ facilities using HPET #1. We don't
100 * want to use HPET for anything except those IRQs though...
102 #ifdef CONFIG_HPET_EMULATE_RTC
103 #include <asm/hpet.h>
106 static inline int is_hpet_enabled(void)
111 static inline int hpet_mask_rtc_irq_bit(unsigned long mask)
116 static inline int hpet_set_rtc_irq_bit(unsigned long mask)
122 hpet_set_alarm_time(unsigned char hrs, unsigned char min, unsigned char sec)
127 static inline int hpet_set_periodic_freq(unsigned long freq)
132 static inline int hpet_rtc_dropped_irq(void)
137 static inline int hpet_rtc_timer_init(void)
142 extern irq_handler_t hpet_rtc_interrupt;
144 static inline int hpet_register_irq_handler(irq_handler_t handler)
149 static inline int hpet_unregister_irq_handler(irq_handler_t handler)
156 /*----------------------------------------------------------------*/
160 /* Most newer x86 systems have two register banks, the first used
161 * for RTC and NVRAM and the second only for NVRAM. Caller must
162 * own rtc_lock ... and we won't worry about access during NMI.
164 #define can_bank2 true
166 static inline unsigned char cmos_read_bank2(unsigned char addr)
168 outb(addr, RTC_PORT(2));
169 return inb(RTC_PORT(3));
172 static inline void cmos_write_bank2(unsigned char val, unsigned char addr)
174 outb(addr, RTC_PORT(2));
175 outb(val, RTC_PORT(3));
180 #define can_bank2 false
182 static inline unsigned char cmos_read_bank2(unsigned char addr)
187 static inline void cmos_write_bank2(unsigned char val, unsigned char addr)
193 /*----------------------------------------------------------------*/
195 static int cmos_read_time(struct device *dev, struct rtc_time *t)
197 /* REVISIT: if the clock has a "century" register, use
198 * that instead of the heuristic in mc146818_get_time().
199 * That'll make Y3K compatility (year > 2070) easy!
201 mc146818_get_time(t);
205 static int cmos_set_time(struct device *dev, struct rtc_time *t)
207 /* REVISIT: set the "century" register if available
209 * NOTE: this ignores the issue whereby updating the seconds
210 * takes effect exactly 500ms after we write the register.
211 * (Also queueing and other delays before we get this far.)
213 return mc146818_set_time(t);
216 static int cmos_read_alarm(struct device *dev, struct rtc_wkalrm *t)
218 struct cmos_rtc *cmos = dev_get_drvdata(dev);
219 unsigned char rtc_control;
221 if (!is_valid_irq(cmos->irq))
224 /* Basic alarms only support hour, minute, and seconds fields.
225 * Some also support day and month, for alarms up to a year in
229 spin_lock_irq(&rtc_lock);
230 t->time.tm_sec = CMOS_READ(RTC_SECONDS_ALARM);
231 t->time.tm_min = CMOS_READ(RTC_MINUTES_ALARM);
232 t->time.tm_hour = CMOS_READ(RTC_HOURS_ALARM);
234 if (cmos->day_alrm) {
235 /* ignore upper bits on readback per ACPI spec */
236 t->time.tm_mday = CMOS_READ(cmos->day_alrm) & 0x3f;
237 if (!t->time.tm_mday)
238 t->time.tm_mday = -1;
240 if (cmos->mon_alrm) {
241 t->time.tm_mon = CMOS_READ(cmos->mon_alrm);
247 rtc_control = CMOS_READ(RTC_CONTROL);
248 spin_unlock_irq(&rtc_lock);
250 if (!(rtc_control & RTC_DM_BINARY) || RTC_ALWAYS_BCD) {
251 if (((unsigned)t->time.tm_sec) < 0x60)
252 t->time.tm_sec = bcd2bin(t->time.tm_sec);
255 if (((unsigned)t->time.tm_min) < 0x60)
256 t->time.tm_min = bcd2bin(t->time.tm_min);
259 if (((unsigned)t->time.tm_hour) < 0x24)
260 t->time.tm_hour = bcd2bin(t->time.tm_hour);
262 t->time.tm_hour = -1;
264 if (cmos->day_alrm) {
265 if (((unsigned)t->time.tm_mday) <= 0x31)
266 t->time.tm_mday = bcd2bin(t->time.tm_mday);
268 t->time.tm_mday = -1;
270 if (cmos->mon_alrm) {
271 if (((unsigned)t->time.tm_mon) <= 0x12)
272 t->time.tm_mon = bcd2bin(t->time.tm_mon)-1;
279 t->enabled = !!(rtc_control & RTC_AIE);
285 static void cmos_checkintr(struct cmos_rtc *cmos, unsigned char rtc_control)
287 unsigned char rtc_intr;
289 /* NOTE after changing RTC_xIE bits we always read INTR_FLAGS;
290 * allegedly some older rtcs need that to handle irqs properly
292 rtc_intr = CMOS_READ(RTC_INTR_FLAGS);
294 if (is_hpet_enabled())
297 rtc_intr &= (rtc_control & RTC_IRQMASK) | RTC_IRQF;
298 if (is_intr(rtc_intr))
299 rtc_update_irq(cmos->rtc, 1, rtc_intr);
302 static void cmos_irq_enable(struct cmos_rtc *cmos, unsigned char mask)
304 unsigned char rtc_control;
306 /* flush any pending IRQ status, notably for update irqs,
307 * before we enable new IRQs
309 rtc_control = CMOS_READ(RTC_CONTROL);
310 cmos_checkintr(cmos, rtc_control);
313 CMOS_WRITE(rtc_control, RTC_CONTROL);
314 hpet_set_rtc_irq_bit(mask);
316 cmos_checkintr(cmos, rtc_control);
319 static void cmos_irq_disable(struct cmos_rtc *cmos, unsigned char mask)
321 unsigned char rtc_control;
323 rtc_control = CMOS_READ(RTC_CONTROL);
324 rtc_control &= ~mask;
325 CMOS_WRITE(rtc_control, RTC_CONTROL);
326 hpet_mask_rtc_irq_bit(mask);
328 cmos_checkintr(cmos, rtc_control);
331 static int cmos_set_alarm(struct device *dev, struct rtc_wkalrm *t)
333 struct cmos_rtc *cmos = dev_get_drvdata(dev);
334 unsigned char mon, mday, hrs, min, sec, rtc_control;
336 if (!is_valid_irq(cmos->irq))
339 mon = t->time.tm_mon + 1;
340 mday = t->time.tm_mday;
341 hrs = t->time.tm_hour;
342 min = t->time.tm_min;
343 sec = t->time.tm_sec;
345 spin_lock_irq(&rtc_lock);
346 rtc_control = CMOS_READ(RTC_CONTROL);
347 spin_unlock_irq(&rtc_lock);
349 if (!(rtc_control & RTC_DM_BINARY) || RTC_ALWAYS_BCD) {
350 /* Writing 0xff means "don't care" or "match all". */
351 mon = (mon <= 12) ? bin2bcd(mon) : 0xff;
352 mday = (mday >= 1 && mday <= 31) ? bin2bcd(mday) : 0xff;
353 hrs = (hrs < 24) ? bin2bcd(hrs) : 0xff;
354 min = (min < 60) ? bin2bcd(min) : 0xff;
355 sec = (sec < 60) ? bin2bcd(sec) : 0xff;
358 spin_lock_irq(&rtc_lock);
360 /* next rtc irq must not be from previous alarm setting */
361 cmos_irq_disable(cmos, RTC_AIE);
364 CMOS_WRITE(hrs, RTC_HOURS_ALARM);
365 CMOS_WRITE(min, RTC_MINUTES_ALARM);
366 CMOS_WRITE(sec, RTC_SECONDS_ALARM);
368 /* the system may support an "enhanced" alarm */
369 if (cmos->day_alrm) {
370 CMOS_WRITE(mday, cmos->day_alrm);
372 CMOS_WRITE(mon, cmos->mon_alrm);
375 /* FIXME the HPET alarm glue currently ignores day_alrm
378 hpet_set_alarm_time(t->time.tm_hour, t->time.tm_min, t->time.tm_sec);
381 cmos_irq_enable(cmos, RTC_AIE);
383 spin_unlock_irq(&rtc_lock);
385 cmos->alarm_expires = rtc_tm_to_time64(&t->time);
390 static int cmos_alarm_irq_enable(struct device *dev, unsigned int enabled)
392 struct cmos_rtc *cmos = dev_get_drvdata(dev);
395 if (!is_valid_irq(cmos->irq))
398 spin_lock_irqsave(&rtc_lock, flags);
401 cmos_irq_enable(cmos, RTC_AIE);
403 cmos_irq_disable(cmos, RTC_AIE);
405 spin_unlock_irqrestore(&rtc_lock, flags);
409 #if IS_ENABLED(CONFIG_RTC_INTF_PROC)
411 static int cmos_procfs(struct device *dev, struct seq_file *seq)
413 struct cmos_rtc *cmos = dev_get_drvdata(dev);
414 unsigned char rtc_control, valid;
416 spin_lock_irq(&rtc_lock);
417 rtc_control = CMOS_READ(RTC_CONTROL);
418 valid = CMOS_READ(RTC_VALID);
419 spin_unlock_irq(&rtc_lock);
421 /* NOTE: at least ICH6 reports battery status using a different
422 * (non-RTC) bit; and SQWE is ignored on many current systems.
425 "periodic_IRQ\t: %s\n"
427 "HPET_emulated\t: %s\n"
428 // "square_wave\t: %s\n"
431 "periodic_freq\t: %d\n"
432 "batt_status\t: %s\n",
433 (rtc_control & RTC_PIE) ? "yes" : "no",
434 (rtc_control & RTC_UIE) ? "yes" : "no",
435 is_hpet_enabled() ? "yes" : "no",
436 // (rtc_control & RTC_SQWE) ? "yes" : "no",
437 (rtc_control & RTC_DM_BINARY) ? "no" : "yes",
438 (rtc_control & RTC_DST_EN) ? "yes" : "no",
440 (valid & RTC_VRT) ? "okay" : "dead");
446 #define cmos_procfs NULL
449 static const struct rtc_class_ops cmos_rtc_ops = {
450 .read_time = cmos_read_time,
451 .set_time = cmos_set_time,
452 .read_alarm = cmos_read_alarm,
453 .set_alarm = cmos_set_alarm,
455 .alarm_irq_enable = cmos_alarm_irq_enable,
458 /*----------------------------------------------------------------*/
461 * All these chips have at least 64 bytes of address space, shared by
462 * RTC registers and NVRAM. Most of those bytes of NVRAM are used
463 * by boot firmware. Modern chips have 128 or 256 bytes.
466 #define NVRAM_OFFSET (RTC_REG_D + 1)
469 cmos_nvram_read(struct file *filp, struct kobject *kobj,
470 struct bin_attribute *attr,
471 char *buf, loff_t off, size_t count)
476 spin_lock_irq(&rtc_lock);
477 for (retval = 0; count; count--, off++, retval++) {
479 *buf++ = CMOS_READ(off);
481 *buf++ = cmos_read_bank2(off);
485 spin_unlock_irq(&rtc_lock);
491 cmos_nvram_write(struct file *filp, struct kobject *kobj,
492 struct bin_attribute *attr,
493 char *buf, loff_t off, size_t count)
495 struct cmos_rtc *cmos;
498 cmos = dev_get_drvdata(container_of(kobj, struct device, kobj));
500 /* NOTE: on at least PCs and Ataris, the boot firmware uses a
501 * checksum on part of the NVRAM data. That's currently ignored
502 * here. If userspace is smart enough to know what fields of
503 * NVRAM to update, updating checksums is also part of its job.
506 spin_lock_irq(&rtc_lock);
507 for (retval = 0; count; count--, off++, retval++) {
508 /* don't trash RTC registers */
509 if (off == cmos->day_alrm
510 || off == cmos->mon_alrm
511 || off == cmos->century)
514 CMOS_WRITE(*buf++, off);
516 cmos_write_bank2(*buf++, off);
520 spin_unlock_irq(&rtc_lock);
525 static struct bin_attribute nvram = {
528 .mode = S_IRUGO | S_IWUSR,
531 .read = cmos_nvram_read,
532 .write = cmos_nvram_write,
533 /* size gets set up later */
536 /*----------------------------------------------------------------*/
538 static struct cmos_rtc cmos_rtc;
540 static irqreturn_t cmos_interrupt(int irq, void *p)
545 spin_lock(&rtc_lock);
547 /* When the HPET interrupt handler calls us, the interrupt
548 * status is passed as arg1 instead of the irq number. But
549 * always clear irq status, even when HPET is in the way.
551 * Note that HPET and RTC are almost certainly out of phase,
552 * giving different IRQ status ...
554 irqstat = CMOS_READ(RTC_INTR_FLAGS);
555 rtc_control = CMOS_READ(RTC_CONTROL);
556 if (is_hpet_enabled())
557 irqstat = (unsigned long)irq & 0xF0;
559 /* If we were suspended, RTC_CONTROL may not be accurate since the
560 * bios may have cleared it.
562 if (!cmos_rtc.suspend_ctrl)
563 irqstat &= (rtc_control & RTC_IRQMASK) | RTC_IRQF;
565 irqstat &= (cmos_rtc.suspend_ctrl & RTC_IRQMASK) | RTC_IRQF;
567 /* All Linux RTC alarms should be treated as if they were oneshot.
568 * Similar code may be needed in system wakeup paths, in case the
569 * alarm woke the system.
571 if (irqstat & RTC_AIE) {
572 cmos_rtc.suspend_ctrl &= ~RTC_AIE;
573 rtc_control &= ~RTC_AIE;
574 CMOS_WRITE(rtc_control, RTC_CONTROL);
575 hpet_mask_rtc_irq_bit(RTC_AIE);
576 CMOS_READ(RTC_INTR_FLAGS);
578 spin_unlock(&rtc_lock);
580 if (is_intr(irqstat)) {
581 rtc_update_irq(p, 1, irqstat);
591 #define INITSECTION __init
594 static int INITSECTION
595 cmos_do_probe(struct device *dev, struct resource *ports, int rtc_irq)
597 struct cmos_rtc_board_info *info = dev_get_platdata(dev);
599 unsigned char rtc_control;
600 unsigned address_space;
603 /* there can be only one ... */
610 /* Claim I/O ports ASAP, minimizing conflict with legacy driver.
612 * REVISIT non-x86 systems may instead use memory space resources
613 * (needing ioremap etc), not i/o space resources like this ...
616 ports = request_region(ports->start, resource_size(ports),
619 ports = request_mem_region(ports->start, resource_size(ports),
622 dev_dbg(dev, "i/o registers already in use\n");
626 cmos_rtc.irq = rtc_irq;
627 cmos_rtc.iomem = ports;
629 /* Heuristic to deduce NVRAM size ... do what the legacy NVRAM
630 * driver did, but don't reject unknown configs. Old hardware
631 * won't address 128 bytes. Newer chips have multiple banks,
632 * though they may not be listed in one I/O resource.
634 #if defined(CONFIG_ATARI)
636 #elif defined(__i386__) || defined(__x86_64__) || defined(__arm__) \
637 || defined(__sparc__) || defined(__mips__) \
638 || defined(__powerpc__) || defined(CONFIG_MN10300)
641 #warning Assuming 128 bytes of RTC+NVRAM address space, not 64 bytes.
644 if (can_bank2 && ports->end > (ports->start + 1))
647 /* For ACPI systems extension info comes from the FADT. On others,
648 * board specific setup provides it as appropriate. Systems where
649 * the alarm IRQ isn't automatically a wakeup IRQ (like ACPI, and
650 * some almost-clones) can provide hooks to make that behave.
652 * Note that ACPI doesn't preclude putting these registers into
653 * "extended" areas of the chip, including some that we won't yet
654 * expect CMOS_READ and friends to handle.
659 if (info->address_space)
660 address_space = info->address_space;
662 if (info->rtc_day_alarm && info->rtc_day_alarm < 128)
663 cmos_rtc.day_alrm = info->rtc_day_alarm;
664 if (info->rtc_mon_alarm && info->rtc_mon_alarm < 128)
665 cmos_rtc.mon_alrm = info->rtc_mon_alarm;
666 if (info->rtc_century && info->rtc_century < 128)
667 cmos_rtc.century = info->rtc_century;
669 if (info->wake_on && info->wake_off) {
670 cmos_rtc.wake_on = info->wake_on;
671 cmos_rtc.wake_off = info->wake_off;
676 dev_set_drvdata(dev, &cmos_rtc);
678 cmos_rtc.rtc = rtc_device_register(driver_name, dev,
679 &cmos_rtc_ops, THIS_MODULE);
680 if (IS_ERR(cmos_rtc.rtc)) {
681 retval = PTR_ERR(cmos_rtc.rtc);
685 rename_region(ports, dev_name(&cmos_rtc.rtc->dev));
687 spin_lock_irq(&rtc_lock);
689 if (!(flags & CMOS_RTC_FLAGS_NOFREQ)) {
690 /* force periodic irq to CMOS reset default of 1024Hz;
692 * REVISIT it's been reported that at least one x86_64 ALI
693 * mobo doesn't use 32KHz here ... for portability we might
694 * need to do something about other clock frequencies.
696 cmos_rtc.rtc->irq_freq = 1024;
697 hpet_set_periodic_freq(cmos_rtc.rtc->irq_freq);
698 CMOS_WRITE(RTC_REF_CLCK_32KHZ | 0x06, RTC_FREQ_SELECT);
702 if (is_valid_irq(rtc_irq))
703 cmos_irq_disable(&cmos_rtc, RTC_PIE | RTC_AIE | RTC_UIE);
705 rtc_control = CMOS_READ(RTC_CONTROL);
707 spin_unlock_irq(&rtc_lock);
710 * <asm-generic/rtc.h> doesn't know 12-hour mode either.
712 if (is_valid_irq(rtc_irq) && !(rtc_control & RTC_24H)) {
713 dev_warn(dev, "only 24-hr supported\n");
718 hpet_rtc_timer_init();
720 if (is_valid_irq(rtc_irq)) {
721 irq_handler_t rtc_cmos_int_handler;
723 if (is_hpet_enabled()) {
724 rtc_cmos_int_handler = hpet_rtc_interrupt;
725 retval = hpet_register_irq_handler(cmos_interrupt);
727 hpet_mask_rtc_irq_bit(RTC_IRQMASK);
728 dev_warn(dev, "hpet_register_irq_handler "
729 " failed in rtc_init().");
733 rtc_cmos_int_handler = cmos_interrupt;
735 retval = request_irq(rtc_irq, rtc_cmos_int_handler,
736 0, dev_name(&cmos_rtc.rtc->dev),
739 dev_dbg(dev, "IRQ %d is already in use\n", rtc_irq);
744 /* export at least the first block of NVRAM */
745 nvram.size = address_space - NVRAM_OFFSET;
746 retval = sysfs_create_bin_file(&dev->kobj, &nvram);
748 dev_dbg(dev, "can't create nvram file? %d\n", retval);
752 dev_info(dev, "%s%s, %zd bytes nvram%s\n",
753 !is_valid_irq(rtc_irq) ? "no alarms" :
754 cmos_rtc.mon_alrm ? "alarms up to one year" :
755 cmos_rtc.day_alrm ? "alarms up to one month" :
756 "alarms up to one day",
757 cmos_rtc.century ? ", y3k" : "",
759 is_hpet_enabled() ? ", hpet irqs" : "");
764 if (is_valid_irq(rtc_irq))
765 free_irq(rtc_irq, cmos_rtc.rtc);
768 rtc_device_unregister(cmos_rtc.rtc);
771 release_region(ports->start, resource_size(ports));
773 release_mem_region(ports->start, resource_size(ports));
777 static void cmos_do_shutdown(int rtc_irq)
779 spin_lock_irq(&rtc_lock);
780 if (is_valid_irq(rtc_irq))
781 cmos_irq_disable(&cmos_rtc, RTC_IRQMASK);
782 spin_unlock_irq(&rtc_lock);
785 static void cmos_do_remove(struct device *dev)
787 struct cmos_rtc *cmos = dev_get_drvdata(dev);
788 struct resource *ports;
790 cmos_do_shutdown(cmos->irq);
792 sysfs_remove_bin_file(&dev->kobj, &nvram);
794 if (is_valid_irq(cmos->irq)) {
795 free_irq(cmos->irq, cmos->rtc);
796 hpet_unregister_irq_handler(cmos_interrupt);
799 rtc_device_unregister(cmos->rtc);
804 release_region(ports->start, resource_size(ports));
806 release_mem_region(ports->start, resource_size(ports));
812 static int cmos_aie_poweroff(struct device *dev)
814 struct cmos_rtc *cmos = dev_get_drvdata(dev);
818 unsigned char rtc_control;
820 if (!cmos->alarm_expires)
823 spin_lock_irq(&rtc_lock);
824 rtc_control = CMOS_READ(RTC_CONTROL);
825 spin_unlock_irq(&rtc_lock);
827 /* We only care about the situation where AIE is disabled. */
828 if (rtc_control & RTC_AIE)
831 cmos_read_time(dev, &now);
832 t_now = rtc_tm_to_time64(&now);
835 * When enabling "RTC wake-up" in BIOS setup, the machine reboots
836 * automatically right after shutdown on some buggy boxes.
837 * This automatic rebooting issue won't happen when the alarm
838 * time is larger than now+1 seconds.
840 * If the alarm time is equal to now+1 seconds, the issue can be
841 * prevented by cancelling the alarm.
843 if (cmos->alarm_expires == t_now + 1) {
844 struct rtc_wkalrm alarm;
846 /* Cancel the AIE timer by configuring the past time. */
847 rtc_time64_to_tm(t_now - 1, &alarm.time);
849 retval = cmos_set_alarm(dev, &alarm);
850 } else if (cmos->alarm_expires > t_now + 1) {
857 static int cmos_suspend(struct device *dev)
859 struct cmos_rtc *cmos = dev_get_drvdata(dev);
862 /* only the alarm might be a wakeup event source */
863 spin_lock_irq(&rtc_lock);
864 cmos->suspend_ctrl = tmp = CMOS_READ(RTC_CONTROL);
865 if (tmp & (RTC_PIE|RTC_AIE|RTC_UIE)) {
868 if (device_may_wakeup(dev))
869 mask = RTC_IRQMASK & ~RTC_AIE;
873 CMOS_WRITE(tmp, RTC_CONTROL);
874 hpet_mask_rtc_irq_bit(mask);
876 cmos_checkintr(cmos, tmp);
878 spin_unlock_irq(&rtc_lock);
881 cmos->enabled_wake = 1;
885 enable_irq_wake(cmos->irq);
888 cmos_read_alarm(dev, &cmos->saved_wkalrm);
890 dev_dbg(dev, "suspend%s, ctrl %02x\n",
891 (tmp & RTC_AIE) ? ", alarm may wake" : "",
897 /* We want RTC alarms to wake us from e.g. ACPI G2/S5 "soft off", even
898 * after a detour through G3 "mechanical off", although the ACPI spec
899 * says wakeup should only work from G1/S4 "hibernate". To most users,
900 * distinctions between S4 and S5 are pointless. So when the hardware
901 * allows, don't draw that distinction.
903 static inline int cmos_poweroff(struct device *dev)
905 if (!IS_ENABLED(CONFIG_PM))
908 return cmos_suspend(dev);
911 static void cmos_check_wkalrm(struct device *dev)
913 struct cmos_rtc *cmos = dev_get_drvdata(dev);
914 struct rtc_wkalrm current_alarm;
915 time64_t t_current_expires;
916 time64_t t_saved_expires;
918 cmos_read_alarm(dev, ¤t_alarm);
919 t_current_expires = rtc_tm_to_time64(¤t_alarm.time);
920 t_saved_expires = rtc_tm_to_time64(&cmos->saved_wkalrm.time);
921 if (t_current_expires != t_saved_expires ||
922 cmos->saved_wkalrm.enabled != current_alarm.enabled) {
923 cmos_set_alarm(dev, &cmos->saved_wkalrm);
927 static void cmos_check_acpi_rtc_status(struct device *dev,
928 unsigned char *rtc_control);
930 static int __maybe_unused cmos_resume(struct device *dev)
932 struct cmos_rtc *cmos = dev_get_drvdata(dev);
935 if (cmos->enabled_wake) {
939 disable_irq_wake(cmos->irq);
940 cmos->enabled_wake = 0;
943 /* The BIOS might have changed the alarm, restore it */
944 cmos_check_wkalrm(dev);
946 spin_lock_irq(&rtc_lock);
947 tmp = cmos->suspend_ctrl;
948 cmos->suspend_ctrl = 0;
949 /* re-enable any irqs previously active */
950 if (tmp & RTC_IRQMASK) {
953 if (device_may_wakeup(dev))
954 hpet_rtc_timer_init();
957 CMOS_WRITE(tmp, RTC_CONTROL);
958 hpet_set_rtc_irq_bit(tmp & RTC_IRQMASK);
960 mask = CMOS_READ(RTC_INTR_FLAGS);
961 mask &= (tmp & RTC_IRQMASK) | RTC_IRQF;
962 if (!is_hpet_enabled() || !is_intr(mask))
965 /* force one-shot behavior if HPET blocked
966 * the wake alarm's irq
968 rtc_update_irq(cmos->rtc, 1, mask);
970 hpet_mask_rtc_irq_bit(RTC_AIE);
971 } while (mask & RTC_AIE);
974 cmos_check_acpi_rtc_status(dev, &tmp);
976 spin_unlock_irq(&rtc_lock);
978 dev_dbg(dev, "resume, ctrl %02x\n", tmp);
983 static SIMPLE_DEV_PM_OPS(cmos_pm_ops, cmos_suspend, cmos_resume);
985 /*----------------------------------------------------------------*/
987 /* On non-x86 systems, a "CMOS" RTC lives most naturally on platform_bus.
988 * ACPI systems always list these as PNPACPI devices, and pre-ACPI PCs
989 * probably list them in similar PNPBIOS tables; so PNP is more common.
991 * We don't use legacy "poke at the hardware" probing. Ancient PCs that
992 * predate even PNPBIOS should set up platform_bus devices.
997 #include <linux/acpi.h>
999 static u32 rtc_handler(void *context)
1001 struct device *dev = context;
1002 struct cmos_rtc *cmos = dev_get_drvdata(dev);
1003 unsigned char rtc_control = 0;
1004 unsigned char rtc_intr;
1005 unsigned long flags;
1007 spin_lock_irqsave(&rtc_lock, flags);
1008 if (cmos_rtc.suspend_ctrl)
1009 rtc_control = CMOS_READ(RTC_CONTROL);
1010 if (rtc_control & RTC_AIE) {
1011 cmos_rtc.suspend_ctrl &= ~RTC_AIE;
1012 CMOS_WRITE(rtc_control, RTC_CONTROL);
1013 rtc_intr = CMOS_READ(RTC_INTR_FLAGS);
1014 rtc_update_irq(cmos->rtc, 1, rtc_intr);
1016 spin_unlock_irqrestore(&rtc_lock, flags);
1018 pm_wakeup_event(dev, 0);
1019 acpi_clear_event(ACPI_EVENT_RTC);
1020 acpi_disable_event(ACPI_EVENT_RTC, 0);
1021 return ACPI_INTERRUPT_HANDLED;
1024 static inline void rtc_wake_setup(struct device *dev)
1026 acpi_install_fixed_event_handler(ACPI_EVENT_RTC, rtc_handler, dev);
1028 * After the RTC handler is installed, the Fixed_RTC event should
1029 * be disabled. Only when the RTC alarm is set will it be enabled.
1031 acpi_clear_event(ACPI_EVENT_RTC);
1032 acpi_disable_event(ACPI_EVENT_RTC, 0);
1035 static void rtc_wake_on(struct device *dev)
1037 acpi_clear_event(ACPI_EVENT_RTC);
1038 acpi_enable_event(ACPI_EVENT_RTC, 0);
1041 static void rtc_wake_off(struct device *dev)
1043 acpi_disable_event(ACPI_EVENT_RTC, 0);
1046 /* Every ACPI platform has a mc146818 compatible "cmos rtc". Here we find
1047 * its device node and pass extra config data. This helps its driver use
1048 * capabilities that the now-obsolete mc146818 didn't have, and informs it
1049 * that this board's RTC is wakeup-capable (per ACPI spec).
1051 static struct cmos_rtc_board_info acpi_rtc_info;
1053 static void cmos_wake_setup(struct device *dev)
1058 rtc_wake_setup(dev);
1059 acpi_rtc_info.wake_on = rtc_wake_on;
1060 acpi_rtc_info.wake_off = rtc_wake_off;
1062 /* workaround bug in some ACPI tables */
1063 if (acpi_gbl_FADT.month_alarm && !acpi_gbl_FADT.day_alarm) {
1064 dev_dbg(dev, "bogus FADT month_alarm (%d)\n",
1065 acpi_gbl_FADT.month_alarm);
1066 acpi_gbl_FADT.month_alarm = 0;
1069 acpi_rtc_info.rtc_day_alarm = acpi_gbl_FADT.day_alarm;
1070 acpi_rtc_info.rtc_mon_alarm = acpi_gbl_FADT.month_alarm;
1071 acpi_rtc_info.rtc_century = acpi_gbl_FADT.century;
1073 /* NOTE: S4_RTC_WAKE is NOT currently useful to Linux */
1074 if (acpi_gbl_FADT.flags & ACPI_FADT_S4_RTC_WAKE)
1075 dev_info(dev, "RTC can wake from S4\n");
1077 dev->platform_data = &acpi_rtc_info;
1079 /* RTC always wakes from S1/S2/S3, and often S4/STD */
1080 device_init_wakeup(dev, 1);
1083 static void cmos_check_acpi_rtc_status(struct device *dev,
1084 unsigned char *rtc_control)
1086 struct cmos_rtc *cmos = dev_get_drvdata(dev);
1087 acpi_event_status rtc_status;
1090 if (acpi_gbl_FADT.flags & ACPI_FADT_FIXED_RTC)
1093 status = acpi_get_event_status(ACPI_EVENT_RTC, &rtc_status);
1094 if (ACPI_FAILURE(status)) {
1095 dev_err(dev, "Could not get RTC status\n");
1096 } else if (rtc_status & ACPI_EVENT_FLAG_SET) {
1098 *rtc_control &= ~RTC_AIE;
1099 CMOS_WRITE(*rtc_control, RTC_CONTROL);
1100 mask = CMOS_READ(RTC_INTR_FLAGS);
1101 rtc_update_irq(cmos->rtc, 1, mask);
1107 static void cmos_wake_setup(struct device *dev)
1111 static void cmos_check_acpi_rtc_status(struct device *dev,
1112 unsigned char *rtc_control)
1120 #include <linux/pnp.h>
1122 static int cmos_pnp_probe(struct pnp_dev *pnp, const struct pnp_device_id *id)
1124 cmos_wake_setup(&pnp->dev);
1126 if (pnp_port_start(pnp, 0) == 0x70 && !pnp_irq_valid(pnp, 0)) {
1127 unsigned int irq = 0;
1129 /* Some machines contain a PNP entry for the RTC, but
1130 * don't define the IRQ. It should always be safe to
1131 * hardcode it on systems with a legacy PIC.
1133 if (nr_legacy_irqs())
1136 return cmos_do_probe(&pnp->dev,
1137 pnp_get_resource(pnp, IORESOURCE_IO, 0), irq);
1139 return cmos_do_probe(&pnp->dev,
1140 pnp_get_resource(pnp, IORESOURCE_IO, 0),
1145 static void cmos_pnp_remove(struct pnp_dev *pnp)
1147 cmos_do_remove(&pnp->dev);
1150 static void cmos_pnp_shutdown(struct pnp_dev *pnp)
1152 struct device *dev = &pnp->dev;
1153 struct cmos_rtc *cmos = dev_get_drvdata(dev);
1155 if (system_state == SYSTEM_POWER_OFF) {
1156 int retval = cmos_poweroff(dev);
1158 if (cmos_aie_poweroff(dev) < 0 && !retval)
1162 cmos_do_shutdown(cmos->irq);
1165 static const struct pnp_device_id rtc_ids[] = {
1166 { .id = "PNP0b00", },
1167 { .id = "PNP0b01", },
1168 { .id = "PNP0b02", },
1171 MODULE_DEVICE_TABLE(pnp, rtc_ids);
1173 static struct pnp_driver cmos_pnp_driver = {
1174 .name = (char *) driver_name,
1175 .id_table = rtc_ids,
1176 .probe = cmos_pnp_probe,
1177 .remove = cmos_pnp_remove,
1178 .shutdown = cmos_pnp_shutdown,
1180 /* flag ensures resume() gets called, and stops syslog spam */
1181 .flags = PNP_DRIVER_RES_DO_NOT_CHANGE,
1187 #endif /* CONFIG_PNP */
1190 static const struct of_device_id of_cmos_match[] = {
1192 .compatible = "motorola,mc146818",
1196 MODULE_DEVICE_TABLE(of, of_cmos_match);
1198 static __init void cmos_of_init(struct platform_device *pdev)
1200 struct device_node *node = pdev->dev.of_node;
1201 struct rtc_time time;
1208 val = of_get_property(node, "ctrl-reg", NULL);
1210 CMOS_WRITE(be32_to_cpup(val), RTC_CONTROL);
1212 val = of_get_property(node, "freq-reg", NULL);
1214 CMOS_WRITE(be32_to_cpup(val), RTC_FREQ_SELECT);
1216 cmos_read_time(&pdev->dev, &time);
1217 ret = rtc_valid_tm(&time);
1219 struct rtc_time def_time = {
1223 cmos_set_time(&pdev->dev, &def_time);
1227 static inline void cmos_of_init(struct platform_device *pdev) {}
1229 /*----------------------------------------------------------------*/
1231 /* Platform setup should have set up an RTC device, when PNP is
1232 * unavailable ... this could happen even on (older) PCs.
1235 static int __init cmos_platform_probe(struct platform_device *pdev)
1237 struct resource *resource;
1241 cmos_wake_setup(&pdev->dev);
1244 resource = platform_get_resource(pdev, IORESOURCE_IO, 0);
1246 resource = platform_get_resource(pdev, IORESOURCE_MEM, 0);
1247 irq = platform_get_irq(pdev, 0);
1251 return cmos_do_probe(&pdev->dev, resource, irq);
1254 static int cmos_platform_remove(struct platform_device *pdev)
1256 cmos_do_remove(&pdev->dev);
1260 static void cmos_platform_shutdown(struct platform_device *pdev)
1262 struct device *dev = &pdev->dev;
1263 struct cmos_rtc *cmos = dev_get_drvdata(dev);
1265 if (system_state == SYSTEM_POWER_OFF) {
1266 int retval = cmos_poweroff(dev);
1268 if (cmos_aie_poweroff(dev) < 0 && !retval)
1272 cmos_do_shutdown(cmos->irq);
1275 /* work with hotplug and coldplug */
1276 MODULE_ALIAS("platform:rtc_cmos");
1278 static struct platform_driver cmos_platform_driver = {
1279 .remove = cmos_platform_remove,
1280 .shutdown = cmos_platform_shutdown,
1282 .name = driver_name,
1284 .of_match_table = of_match_ptr(of_cmos_match),
1289 static bool pnp_driver_registered;
1291 static bool platform_driver_registered;
1293 static int __init cmos_init(void)
1298 retval = pnp_register_driver(&cmos_pnp_driver);
1300 pnp_driver_registered = true;
1303 if (!cmos_rtc.dev) {
1304 retval = platform_driver_probe(&cmos_platform_driver,
1305 cmos_platform_probe);
1307 platform_driver_registered = true;
1314 if (pnp_driver_registered)
1315 pnp_unregister_driver(&cmos_pnp_driver);
1319 module_init(cmos_init);
1321 static void __exit cmos_exit(void)
1324 if (pnp_driver_registered)
1325 pnp_unregister_driver(&cmos_pnp_driver);
1327 if (platform_driver_registered)
1328 platform_driver_unregister(&cmos_platform_driver);
1330 module_exit(cmos_exit);
1333 MODULE_AUTHOR("David Brownell");
1334 MODULE_DESCRIPTION("Driver for PC-style 'CMOS' RTCs");
1335 MODULE_LICENSE("GPL");