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>
46 #include <asm/processor.h>
47 #include <linux/dmi.h>
50 /* this is for "generic access to PC-style RTC" using CMOS_READ/CMOS_WRITE */
51 #include <linux/mc146818rtc.h>
55 * Use ACPI SCI to replace HPET interrupt for RTC Alarm event
57 * If cleared, ACPI SCI is only used to wake up the system from suspend
59 * If set, ACPI SCI is used to handle UIE/AIE and system wakeup
62 static bool use_acpi_alarm;
63 module_param(use_acpi_alarm, bool, 0444);
65 static inline int cmos_use_acpi_alarm(void)
67 return use_acpi_alarm;
69 #else /* !CONFIG_ACPI */
71 static inline int cmos_use_acpi_alarm(void)
78 struct rtc_device *rtc;
81 struct resource *iomem;
82 time64_t alarm_expires;
84 void (*wake_on)(struct device *);
85 void (*wake_off)(struct device *);
90 /* newer hardware extends the original register set */
95 struct rtc_wkalrm saved_wkalrm;
98 /* both platform and pnp busses use negative numbers for invalid irqs */
99 #define is_valid_irq(n) ((n) > 0)
101 static const char driver_name[] = "rtc_cmos";
103 /* The RTC_INTR register may have e.g. RTC_PF set even if RTC_PIE is clear;
104 * always mask it against the irq enable bits in RTC_CONTROL. Bit values
105 * are the same: PF==PIE, AF=AIE, UF=UIE; so RTC_IRQMASK works with both.
107 #define RTC_IRQMASK (RTC_PF | RTC_AF | RTC_UF)
109 static inline int is_intr(u8 rtc_intr)
111 if (!(rtc_intr & RTC_IRQF))
113 return rtc_intr & RTC_IRQMASK;
116 /*----------------------------------------------------------------*/
118 /* Much modern x86 hardware has HPETs (10+ MHz timers) which, because
119 * many BIOS programmers don't set up "sane mode" IRQ routing, are mostly
120 * used in a broken "legacy replacement" mode. The breakage includes
121 * HPET #1 hijacking the IRQ for this RTC, and being unavailable for
122 * other (better) use.
124 * When that broken mode is in use, platform glue provides a partial
125 * emulation of hardware RTC IRQ facilities using HPET #1. We don't
126 * want to use HPET for anything except those IRQs though...
128 #ifdef CONFIG_HPET_EMULATE_RTC
129 #include <asm/hpet.h>
132 static inline int is_hpet_enabled(void)
137 static inline int hpet_mask_rtc_irq_bit(unsigned long mask)
142 static inline int hpet_set_rtc_irq_bit(unsigned long mask)
148 hpet_set_alarm_time(unsigned char hrs, unsigned char min, unsigned char sec)
153 static inline int hpet_set_periodic_freq(unsigned long freq)
158 static inline int hpet_rtc_dropped_irq(void)
163 static inline int hpet_rtc_timer_init(void)
168 extern irq_handler_t hpet_rtc_interrupt;
170 static inline int hpet_register_irq_handler(irq_handler_t handler)
175 static inline int hpet_unregister_irq_handler(irq_handler_t handler)
182 /* Don't use HPET for RTC Alarm event if ACPI Fixed event is used */
183 static inline int use_hpet_alarm(void)
185 return is_hpet_enabled() && !cmos_use_acpi_alarm();
188 /*----------------------------------------------------------------*/
192 /* Most newer x86 systems have two register banks, the first used
193 * for RTC and NVRAM and the second only for NVRAM. Caller must
194 * own rtc_lock ... and we won't worry about access during NMI.
196 #define can_bank2 true
198 static inline unsigned char cmos_read_bank2(unsigned char addr)
200 outb(addr, RTC_PORT(2));
201 return inb(RTC_PORT(3));
204 static inline void cmos_write_bank2(unsigned char val, unsigned char addr)
206 outb(addr, RTC_PORT(2));
207 outb(val, RTC_PORT(3));
212 #define can_bank2 false
214 static inline unsigned char cmos_read_bank2(unsigned char addr)
219 static inline void cmos_write_bank2(unsigned char val, unsigned char addr)
225 /*----------------------------------------------------------------*/
227 static int cmos_read_time(struct device *dev, struct rtc_time *t)
230 * If pm_trace abused the RTC for storage, set the timespec to 0,
231 * which tells the caller that this RTC value is unusable.
233 if (!pm_trace_rtc_valid())
236 /* REVISIT: if the clock has a "century" register, use
237 * that instead of the heuristic in mc146818_get_time().
238 * That'll make Y3K compatility (year > 2070) easy!
240 mc146818_get_time(t);
244 static int cmos_set_time(struct device *dev, struct rtc_time *t)
246 /* REVISIT: set the "century" register if available
248 * NOTE: this ignores the issue whereby updating the seconds
249 * takes effect exactly 500ms after we write the register.
250 * (Also queueing and other delays before we get this far.)
252 return mc146818_set_time(t);
255 static int cmos_read_alarm(struct device *dev, struct rtc_wkalrm *t)
257 struct cmos_rtc *cmos = dev_get_drvdata(dev);
258 unsigned char rtc_control;
260 /* This not only a rtc_op, but also called directly */
261 if (!is_valid_irq(cmos->irq))
264 /* Basic alarms only support hour, minute, and seconds fields.
265 * Some also support day and month, for alarms up to a year in
269 spin_lock_irq(&rtc_lock);
270 t->time.tm_sec = CMOS_READ(RTC_SECONDS_ALARM);
271 t->time.tm_min = CMOS_READ(RTC_MINUTES_ALARM);
272 t->time.tm_hour = CMOS_READ(RTC_HOURS_ALARM);
274 if (cmos->day_alrm) {
275 /* ignore upper bits on readback per ACPI spec */
276 t->time.tm_mday = CMOS_READ(cmos->day_alrm) & 0x3f;
277 if (!t->time.tm_mday)
278 t->time.tm_mday = -1;
280 if (cmos->mon_alrm) {
281 t->time.tm_mon = CMOS_READ(cmos->mon_alrm);
287 rtc_control = CMOS_READ(RTC_CONTROL);
288 spin_unlock_irq(&rtc_lock);
290 if (!(rtc_control & RTC_DM_BINARY) || RTC_ALWAYS_BCD) {
291 if (((unsigned)t->time.tm_sec) < 0x60)
292 t->time.tm_sec = bcd2bin(t->time.tm_sec);
295 if (((unsigned)t->time.tm_min) < 0x60)
296 t->time.tm_min = bcd2bin(t->time.tm_min);
299 if (((unsigned)t->time.tm_hour) < 0x24)
300 t->time.tm_hour = bcd2bin(t->time.tm_hour);
302 t->time.tm_hour = -1;
304 if (cmos->day_alrm) {
305 if (((unsigned)t->time.tm_mday) <= 0x31)
306 t->time.tm_mday = bcd2bin(t->time.tm_mday);
308 t->time.tm_mday = -1;
310 if (cmos->mon_alrm) {
311 if (((unsigned)t->time.tm_mon) <= 0x12)
312 t->time.tm_mon = bcd2bin(t->time.tm_mon)-1;
319 t->enabled = !!(rtc_control & RTC_AIE);
325 static void cmos_checkintr(struct cmos_rtc *cmos, unsigned char rtc_control)
327 unsigned char rtc_intr;
329 /* NOTE after changing RTC_xIE bits we always read INTR_FLAGS;
330 * allegedly some older rtcs need that to handle irqs properly
332 rtc_intr = CMOS_READ(RTC_INTR_FLAGS);
334 if (use_hpet_alarm())
337 rtc_intr &= (rtc_control & RTC_IRQMASK) | RTC_IRQF;
338 if (is_intr(rtc_intr))
339 rtc_update_irq(cmos->rtc, 1, rtc_intr);
342 static void cmos_irq_enable(struct cmos_rtc *cmos, unsigned char mask)
344 unsigned char rtc_control;
346 /* flush any pending IRQ status, notably for update irqs,
347 * before we enable new IRQs
349 rtc_control = CMOS_READ(RTC_CONTROL);
350 cmos_checkintr(cmos, rtc_control);
353 CMOS_WRITE(rtc_control, RTC_CONTROL);
354 if (use_hpet_alarm())
355 hpet_set_rtc_irq_bit(mask);
357 if ((mask & RTC_AIE) && cmos_use_acpi_alarm()) {
359 cmos->wake_on(cmos->dev);
362 cmos_checkintr(cmos, rtc_control);
365 static void cmos_irq_disable(struct cmos_rtc *cmos, unsigned char mask)
367 unsigned char rtc_control;
369 rtc_control = CMOS_READ(RTC_CONTROL);
370 rtc_control &= ~mask;
371 CMOS_WRITE(rtc_control, RTC_CONTROL);
372 if (use_hpet_alarm())
373 hpet_mask_rtc_irq_bit(mask);
375 if ((mask & RTC_AIE) && cmos_use_acpi_alarm()) {
377 cmos->wake_off(cmos->dev);
380 cmos_checkintr(cmos, rtc_control);
383 static int cmos_validate_alarm(struct device *dev, struct rtc_wkalrm *t)
385 struct cmos_rtc *cmos = dev_get_drvdata(dev);
388 cmos_read_time(dev, &now);
390 if (!cmos->day_alrm) {
394 t_max_date = rtc_tm_to_time64(&now);
395 t_max_date += 24 * 60 * 60 - 1;
396 t_alrm = rtc_tm_to_time64(&t->time);
397 if (t_alrm > t_max_date) {
399 "Alarms can be up to one day in the future\n");
402 } else if (!cmos->mon_alrm) {
403 struct rtc_time max_date = now;
408 if (max_date.tm_mon == 11) {
410 max_date.tm_year += 1;
412 max_date.tm_mon += 1;
414 max_mday = rtc_month_days(max_date.tm_mon, max_date.tm_year);
415 if (max_date.tm_mday > max_mday)
416 max_date.tm_mday = max_mday;
418 t_max_date = rtc_tm_to_time64(&max_date);
420 t_alrm = rtc_tm_to_time64(&t->time);
421 if (t_alrm > t_max_date) {
423 "Alarms can be up to one month in the future\n");
427 struct rtc_time max_date = now;
432 max_date.tm_year += 1;
433 max_mday = rtc_month_days(max_date.tm_mon, max_date.tm_year);
434 if (max_date.tm_mday > max_mday)
435 max_date.tm_mday = max_mday;
437 t_max_date = rtc_tm_to_time64(&max_date);
439 t_alrm = rtc_tm_to_time64(&t->time);
440 if (t_alrm > t_max_date) {
442 "Alarms can be up to one year in the future\n");
450 static int cmos_set_alarm(struct device *dev, struct rtc_wkalrm *t)
452 struct cmos_rtc *cmos = dev_get_drvdata(dev);
453 unsigned char mon, mday, hrs, min, sec, rtc_control;
456 /* This not only a rtc_op, but also called directly */
457 if (!is_valid_irq(cmos->irq))
460 ret = cmos_validate_alarm(dev, t);
464 mon = t->time.tm_mon + 1;
465 mday = t->time.tm_mday;
466 hrs = t->time.tm_hour;
467 min = t->time.tm_min;
468 sec = t->time.tm_sec;
470 spin_lock_irq(&rtc_lock);
471 rtc_control = CMOS_READ(RTC_CONTROL);
472 spin_unlock_irq(&rtc_lock);
474 if (!(rtc_control & RTC_DM_BINARY) || RTC_ALWAYS_BCD) {
475 /* Writing 0xff means "don't care" or "match all". */
476 mon = (mon <= 12) ? bin2bcd(mon) : 0xff;
477 mday = (mday >= 1 && mday <= 31) ? bin2bcd(mday) : 0xff;
478 hrs = (hrs < 24) ? bin2bcd(hrs) : 0xff;
479 min = (min < 60) ? bin2bcd(min) : 0xff;
480 sec = (sec < 60) ? bin2bcd(sec) : 0xff;
483 spin_lock_irq(&rtc_lock);
485 /* next rtc irq must not be from previous alarm setting */
486 cmos_irq_disable(cmos, RTC_AIE);
489 CMOS_WRITE(hrs, RTC_HOURS_ALARM);
490 CMOS_WRITE(min, RTC_MINUTES_ALARM);
491 CMOS_WRITE(sec, RTC_SECONDS_ALARM);
493 /* the system may support an "enhanced" alarm */
494 if (cmos->day_alrm) {
495 CMOS_WRITE(mday, cmos->day_alrm);
497 CMOS_WRITE(mon, cmos->mon_alrm);
500 if (use_hpet_alarm()) {
502 * FIXME the HPET alarm glue currently ignores day_alrm
505 hpet_set_alarm_time(t->time.tm_hour, t->time.tm_min,
510 cmos_irq_enable(cmos, RTC_AIE);
512 spin_unlock_irq(&rtc_lock);
514 cmos->alarm_expires = rtc_tm_to_time64(&t->time);
519 static int cmos_alarm_irq_enable(struct device *dev, unsigned int enabled)
521 struct cmos_rtc *cmos = dev_get_drvdata(dev);
524 spin_lock_irqsave(&rtc_lock, flags);
527 cmos_irq_enable(cmos, RTC_AIE);
529 cmos_irq_disable(cmos, RTC_AIE);
531 spin_unlock_irqrestore(&rtc_lock, flags);
535 #if IS_ENABLED(CONFIG_RTC_INTF_PROC)
537 static int cmos_procfs(struct device *dev, struct seq_file *seq)
539 struct cmos_rtc *cmos = dev_get_drvdata(dev);
540 unsigned char rtc_control, valid;
542 spin_lock_irq(&rtc_lock);
543 rtc_control = CMOS_READ(RTC_CONTROL);
544 valid = CMOS_READ(RTC_VALID);
545 spin_unlock_irq(&rtc_lock);
547 /* NOTE: at least ICH6 reports battery status using a different
548 * (non-RTC) bit; and SQWE is ignored on many current systems.
551 "periodic_IRQ\t: %s\n"
553 "HPET_emulated\t: %s\n"
554 // "square_wave\t: %s\n"
557 "periodic_freq\t: %d\n"
558 "batt_status\t: %s\n",
559 (rtc_control & RTC_PIE) ? "yes" : "no",
560 (rtc_control & RTC_UIE) ? "yes" : "no",
561 use_hpet_alarm() ? "yes" : "no",
562 // (rtc_control & RTC_SQWE) ? "yes" : "no",
563 (rtc_control & RTC_DM_BINARY) ? "no" : "yes",
564 (rtc_control & RTC_DST_EN) ? "yes" : "no",
566 (valid & RTC_VRT) ? "okay" : "dead");
572 #define cmos_procfs NULL
575 static const struct rtc_class_ops cmos_rtc_ops = {
576 .read_time = cmos_read_time,
577 .set_time = cmos_set_time,
578 .read_alarm = cmos_read_alarm,
579 .set_alarm = cmos_set_alarm,
581 .alarm_irq_enable = cmos_alarm_irq_enable,
584 static const struct rtc_class_ops cmos_rtc_ops_no_alarm = {
585 .read_time = cmos_read_time,
586 .set_time = cmos_set_time,
590 /*----------------------------------------------------------------*/
593 * All these chips have at least 64 bytes of address space, shared by
594 * RTC registers and NVRAM. Most of those bytes of NVRAM are used
595 * by boot firmware. Modern chips have 128 or 256 bytes.
598 #define NVRAM_OFFSET (RTC_REG_D + 1)
600 static int cmos_nvram_read(void *priv, unsigned int off, void *val,
603 unsigned char *buf = val;
607 spin_lock_irq(&rtc_lock);
608 for (retval = 0; count; count--, off++, retval++) {
610 *buf++ = CMOS_READ(off);
612 *buf++ = cmos_read_bank2(off);
616 spin_unlock_irq(&rtc_lock);
621 static int cmos_nvram_write(void *priv, unsigned int off, void *val,
624 struct cmos_rtc *cmos = priv;
625 unsigned char *buf = val;
628 /* NOTE: on at least PCs and Ataris, the boot firmware uses a
629 * checksum on part of the NVRAM data. That's currently ignored
630 * here. If userspace is smart enough to know what fields of
631 * NVRAM to update, updating checksums is also part of its job.
634 spin_lock_irq(&rtc_lock);
635 for (retval = 0; count; count--, off++, retval++) {
636 /* don't trash RTC registers */
637 if (off == cmos->day_alrm
638 || off == cmos->mon_alrm
639 || off == cmos->century)
642 CMOS_WRITE(*buf++, off);
644 cmos_write_bank2(*buf++, off);
648 spin_unlock_irq(&rtc_lock);
653 /*----------------------------------------------------------------*/
655 static struct cmos_rtc cmos_rtc;
657 static irqreturn_t cmos_interrupt(int irq, void *p)
662 spin_lock(&rtc_lock);
664 /* When the HPET interrupt handler calls us, the interrupt
665 * status is passed as arg1 instead of the irq number. But
666 * always clear irq status, even when HPET is in the way.
668 * Note that HPET and RTC are almost certainly out of phase,
669 * giving different IRQ status ...
671 irqstat = CMOS_READ(RTC_INTR_FLAGS);
672 rtc_control = CMOS_READ(RTC_CONTROL);
673 if (use_hpet_alarm())
674 irqstat = (unsigned long)irq & 0xF0;
676 /* If we were suspended, RTC_CONTROL may not be accurate since the
677 * bios may have cleared it.
679 if (!cmos_rtc.suspend_ctrl)
680 irqstat &= (rtc_control & RTC_IRQMASK) | RTC_IRQF;
682 irqstat &= (cmos_rtc.suspend_ctrl & RTC_IRQMASK) | RTC_IRQF;
684 /* All Linux RTC alarms should be treated as if they were oneshot.
685 * Similar code may be needed in system wakeup paths, in case the
686 * alarm woke the system.
688 if (irqstat & RTC_AIE) {
689 cmos_rtc.suspend_ctrl &= ~RTC_AIE;
690 rtc_control &= ~RTC_AIE;
691 CMOS_WRITE(rtc_control, RTC_CONTROL);
692 if (use_hpet_alarm())
693 hpet_mask_rtc_irq_bit(RTC_AIE);
694 CMOS_READ(RTC_INTR_FLAGS);
696 spin_unlock(&rtc_lock);
698 if (is_intr(irqstat)) {
699 rtc_update_irq(p, 1, irqstat);
709 #define INITSECTION __init
712 static int INITSECTION
713 cmos_do_probe(struct device *dev, struct resource *ports, int rtc_irq)
715 struct cmos_rtc_board_info *info = dev_get_platdata(dev);
717 unsigned char rtc_control;
718 unsigned address_space;
720 struct nvmem_config nvmem_cfg = {
721 .name = "cmos_nvram",
724 .reg_read = cmos_nvram_read,
725 .reg_write = cmos_nvram_write,
729 /* there can be only one ... */
736 /* Claim I/O ports ASAP, minimizing conflict with legacy driver.
738 * REVISIT non-x86 systems may instead use memory space resources
739 * (needing ioremap etc), not i/o space resources like this ...
742 ports = request_region(ports->start, resource_size(ports),
745 ports = request_mem_region(ports->start, resource_size(ports),
748 dev_dbg(dev, "i/o registers already in use\n");
752 cmos_rtc.irq = rtc_irq;
753 cmos_rtc.iomem = ports;
755 /* Heuristic to deduce NVRAM size ... do what the legacy NVRAM
756 * driver did, but don't reject unknown configs. Old hardware
757 * won't address 128 bytes. Newer chips have multiple banks,
758 * though they may not be listed in one I/O resource.
760 #if defined(CONFIG_ATARI)
762 #elif defined(__i386__) || defined(__x86_64__) || defined(__arm__) \
763 || defined(__sparc__) || defined(__mips__) \
764 || defined(__powerpc__)
767 #warning Assuming 128 bytes of RTC+NVRAM address space, not 64 bytes.
770 if (can_bank2 && ports->end > (ports->start + 1))
773 /* For ACPI systems extension info comes from the FADT. On others,
774 * board specific setup provides it as appropriate. Systems where
775 * the alarm IRQ isn't automatically a wakeup IRQ (like ACPI, and
776 * some almost-clones) can provide hooks to make that behave.
778 * Note that ACPI doesn't preclude putting these registers into
779 * "extended" areas of the chip, including some that we won't yet
780 * expect CMOS_READ and friends to handle.
785 if (info->address_space)
786 address_space = info->address_space;
788 if (info->rtc_day_alarm && info->rtc_day_alarm < 128)
789 cmos_rtc.day_alrm = info->rtc_day_alarm;
790 if (info->rtc_mon_alarm && info->rtc_mon_alarm < 128)
791 cmos_rtc.mon_alrm = info->rtc_mon_alarm;
792 if (info->rtc_century && info->rtc_century < 128)
793 cmos_rtc.century = info->rtc_century;
795 if (info->wake_on && info->wake_off) {
796 cmos_rtc.wake_on = info->wake_on;
797 cmos_rtc.wake_off = info->wake_off;
802 dev_set_drvdata(dev, &cmos_rtc);
804 cmos_rtc.rtc = devm_rtc_allocate_device(dev);
805 if (IS_ERR(cmos_rtc.rtc)) {
806 retval = PTR_ERR(cmos_rtc.rtc);
810 rename_region(ports, dev_name(&cmos_rtc.rtc->dev));
812 spin_lock_irq(&rtc_lock);
814 if (!(flags & CMOS_RTC_FLAGS_NOFREQ)) {
815 /* force periodic irq to CMOS reset default of 1024Hz;
817 * REVISIT it's been reported that at least one x86_64 ALI
818 * mobo doesn't use 32KHz here ... for portability we might
819 * need to do something about other clock frequencies.
821 cmos_rtc.rtc->irq_freq = 1024;
822 if (use_hpet_alarm())
823 hpet_set_periodic_freq(cmos_rtc.rtc->irq_freq);
824 CMOS_WRITE(RTC_REF_CLCK_32KHZ | 0x06, RTC_FREQ_SELECT);
828 if (is_valid_irq(rtc_irq))
829 cmos_irq_disable(&cmos_rtc, RTC_PIE | RTC_AIE | RTC_UIE);
831 rtc_control = CMOS_READ(RTC_CONTROL);
833 spin_unlock_irq(&rtc_lock);
835 if (is_valid_irq(rtc_irq) && !(rtc_control & RTC_24H)) {
836 dev_warn(dev, "only 24-hr supported\n");
841 if (use_hpet_alarm())
842 hpet_rtc_timer_init();
844 if (is_valid_irq(rtc_irq)) {
845 irq_handler_t rtc_cmos_int_handler;
847 if (use_hpet_alarm()) {
848 rtc_cmos_int_handler = hpet_rtc_interrupt;
849 retval = hpet_register_irq_handler(cmos_interrupt);
851 hpet_mask_rtc_irq_bit(RTC_IRQMASK);
852 dev_warn(dev, "hpet_register_irq_handler "
853 " failed in rtc_init().");
857 rtc_cmos_int_handler = cmos_interrupt;
859 retval = request_irq(rtc_irq, rtc_cmos_int_handler,
860 0, dev_name(&cmos_rtc.rtc->dev),
863 dev_dbg(dev, "IRQ %d is already in use\n", rtc_irq);
867 cmos_rtc.rtc->ops = &cmos_rtc_ops;
869 cmos_rtc.rtc->ops = &cmos_rtc_ops_no_alarm;
872 cmos_rtc.rtc->nvram_old_abi = true;
873 retval = rtc_register_device(cmos_rtc.rtc);
877 /* export at least the first block of NVRAM */
878 nvmem_cfg.size = address_space - NVRAM_OFFSET;
879 if (rtc_nvmem_register(cmos_rtc.rtc, &nvmem_cfg))
880 dev_err(dev, "nvmem registration failed\n");
882 dev_info(dev, "%s%s, %d bytes nvram%s\n",
883 !is_valid_irq(rtc_irq) ? "no alarms" :
884 cmos_rtc.mon_alrm ? "alarms up to one year" :
885 cmos_rtc.day_alrm ? "alarms up to one month" :
886 "alarms up to one day",
887 cmos_rtc.century ? ", y3k" : "",
889 use_hpet_alarm() ? ", hpet irqs" : "");
894 if (is_valid_irq(rtc_irq))
895 free_irq(rtc_irq, cmos_rtc.rtc);
900 release_region(ports->start, resource_size(ports));
902 release_mem_region(ports->start, resource_size(ports));
906 static void cmos_do_shutdown(int rtc_irq)
908 spin_lock_irq(&rtc_lock);
909 if (is_valid_irq(rtc_irq))
910 cmos_irq_disable(&cmos_rtc, RTC_IRQMASK);
911 spin_unlock_irq(&rtc_lock);
914 static void cmos_do_remove(struct device *dev)
916 struct cmos_rtc *cmos = dev_get_drvdata(dev);
917 struct resource *ports;
919 cmos_do_shutdown(cmos->irq);
921 if (is_valid_irq(cmos->irq)) {
922 free_irq(cmos->irq, cmos->rtc);
923 if (use_hpet_alarm())
924 hpet_unregister_irq_handler(cmos_interrupt);
931 release_region(ports->start, resource_size(ports));
933 release_mem_region(ports->start, resource_size(ports));
939 static int cmos_aie_poweroff(struct device *dev)
941 struct cmos_rtc *cmos = dev_get_drvdata(dev);
945 unsigned char rtc_control;
947 if (!cmos->alarm_expires)
950 spin_lock_irq(&rtc_lock);
951 rtc_control = CMOS_READ(RTC_CONTROL);
952 spin_unlock_irq(&rtc_lock);
954 /* We only care about the situation where AIE is disabled. */
955 if (rtc_control & RTC_AIE)
958 cmos_read_time(dev, &now);
959 t_now = rtc_tm_to_time64(&now);
962 * When enabling "RTC wake-up" in BIOS setup, the machine reboots
963 * automatically right after shutdown on some buggy boxes.
964 * This automatic rebooting issue won't happen when the alarm
965 * time is larger than now+1 seconds.
967 * If the alarm time is equal to now+1 seconds, the issue can be
968 * prevented by cancelling the alarm.
970 if (cmos->alarm_expires == t_now + 1) {
971 struct rtc_wkalrm alarm;
973 /* Cancel the AIE timer by configuring the past time. */
974 rtc_time64_to_tm(t_now - 1, &alarm.time);
976 retval = cmos_set_alarm(dev, &alarm);
977 } else if (cmos->alarm_expires > t_now + 1) {
984 static int cmos_suspend(struct device *dev)
986 struct cmos_rtc *cmos = dev_get_drvdata(dev);
989 /* only the alarm might be a wakeup event source */
990 spin_lock_irq(&rtc_lock);
991 cmos->suspend_ctrl = tmp = CMOS_READ(RTC_CONTROL);
992 if (tmp & (RTC_PIE|RTC_AIE|RTC_UIE)) {
995 if (device_may_wakeup(dev))
996 mask = RTC_IRQMASK & ~RTC_AIE;
1000 CMOS_WRITE(tmp, RTC_CONTROL);
1001 if (use_hpet_alarm())
1002 hpet_mask_rtc_irq_bit(mask);
1003 cmos_checkintr(cmos, tmp);
1005 spin_unlock_irq(&rtc_lock);
1007 if ((tmp & RTC_AIE) && !cmos_use_acpi_alarm()) {
1008 cmos->enabled_wake = 1;
1012 enable_irq_wake(cmos->irq);
1015 cmos_read_alarm(dev, &cmos->saved_wkalrm);
1017 dev_dbg(dev, "suspend%s, ctrl %02x\n",
1018 (tmp & RTC_AIE) ? ", alarm may wake" : "",
1024 /* We want RTC alarms to wake us from e.g. ACPI G2/S5 "soft off", even
1025 * after a detour through G3 "mechanical off", although the ACPI spec
1026 * says wakeup should only work from G1/S4 "hibernate". To most users,
1027 * distinctions between S4 and S5 are pointless. So when the hardware
1028 * allows, don't draw that distinction.
1030 static inline int cmos_poweroff(struct device *dev)
1032 if (!IS_ENABLED(CONFIG_PM))
1035 return cmos_suspend(dev);
1038 static void cmos_check_wkalrm(struct device *dev)
1040 struct cmos_rtc *cmos = dev_get_drvdata(dev);
1041 struct rtc_wkalrm current_alarm;
1043 time64_t t_current_expires;
1044 time64_t t_saved_expires;
1045 struct rtc_time now;
1047 /* Check if we have RTC Alarm armed */
1048 if (!(cmos->suspend_ctrl & RTC_AIE))
1051 cmos_read_time(dev, &now);
1052 t_now = rtc_tm_to_time64(&now);
1055 * ACPI RTC wake event is cleared after resume from STR,
1056 * ACK the rtc irq here
1058 if (t_now >= cmos->alarm_expires && cmos_use_acpi_alarm()) {
1059 cmos_interrupt(0, (void *)cmos->rtc);
1063 cmos_read_alarm(dev, ¤t_alarm);
1064 t_current_expires = rtc_tm_to_time64(¤t_alarm.time);
1065 t_saved_expires = rtc_tm_to_time64(&cmos->saved_wkalrm.time);
1066 if (t_current_expires != t_saved_expires ||
1067 cmos->saved_wkalrm.enabled != current_alarm.enabled) {
1068 cmos_set_alarm(dev, &cmos->saved_wkalrm);
1072 static void cmos_check_acpi_rtc_status(struct device *dev,
1073 unsigned char *rtc_control);
1075 static int __maybe_unused cmos_resume(struct device *dev)
1077 struct cmos_rtc *cmos = dev_get_drvdata(dev);
1080 if (cmos->enabled_wake && !cmos_use_acpi_alarm()) {
1082 cmos->wake_off(dev);
1084 disable_irq_wake(cmos->irq);
1085 cmos->enabled_wake = 0;
1088 /* The BIOS might have changed the alarm, restore it */
1089 cmos_check_wkalrm(dev);
1091 spin_lock_irq(&rtc_lock);
1092 tmp = cmos->suspend_ctrl;
1093 cmos->suspend_ctrl = 0;
1094 /* re-enable any irqs previously active */
1095 if (tmp & RTC_IRQMASK) {
1098 if (device_may_wakeup(dev) && use_hpet_alarm())
1099 hpet_rtc_timer_init();
1102 CMOS_WRITE(tmp, RTC_CONTROL);
1103 if (use_hpet_alarm())
1104 hpet_set_rtc_irq_bit(tmp & RTC_IRQMASK);
1106 mask = CMOS_READ(RTC_INTR_FLAGS);
1107 mask &= (tmp & RTC_IRQMASK) | RTC_IRQF;
1108 if (!use_hpet_alarm() || !is_intr(mask))
1111 /* force one-shot behavior if HPET blocked
1112 * the wake alarm's irq
1114 rtc_update_irq(cmos->rtc, 1, mask);
1116 hpet_mask_rtc_irq_bit(RTC_AIE);
1117 } while (mask & RTC_AIE);
1120 cmos_check_acpi_rtc_status(dev, &tmp);
1122 spin_unlock_irq(&rtc_lock);
1124 dev_dbg(dev, "resume, ctrl %02x\n", tmp);
1129 static SIMPLE_DEV_PM_OPS(cmos_pm_ops, cmos_suspend, cmos_resume);
1131 /*----------------------------------------------------------------*/
1133 /* On non-x86 systems, a "CMOS" RTC lives most naturally on platform_bus.
1134 * ACPI systems always list these as PNPACPI devices, and pre-ACPI PCs
1135 * probably list them in similar PNPBIOS tables; so PNP is more common.
1137 * We don't use legacy "poke at the hardware" probing. Ancient PCs that
1138 * predate even PNPBIOS should set up platform_bus devices.
1143 #include <linux/acpi.h>
1145 static u32 rtc_handler(void *context)
1147 struct device *dev = context;
1148 struct cmos_rtc *cmos = dev_get_drvdata(dev);
1149 unsigned char rtc_control = 0;
1150 unsigned char rtc_intr;
1151 unsigned long flags;
1155 * Always update rtc irq when ACPI is used as RTC Alarm.
1156 * Or else, ACPI SCI is enabled during suspend/resume only,
1157 * update rtc irq in that case.
1159 if (cmos_use_acpi_alarm())
1160 cmos_interrupt(0, (void *)cmos->rtc);
1162 /* Fix me: can we use cmos_interrupt() here as well? */
1163 spin_lock_irqsave(&rtc_lock, flags);
1164 if (cmos_rtc.suspend_ctrl)
1165 rtc_control = CMOS_READ(RTC_CONTROL);
1166 if (rtc_control & RTC_AIE) {
1167 cmos_rtc.suspend_ctrl &= ~RTC_AIE;
1168 CMOS_WRITE(rtc_control, RTC_CONTROL);
1169 rtc_intr = CMOS_READ(RTC_INTR_FLAGS);
1170 rtc_update_irq(cmos->rtc, 1, rtc_intr);
1172 spin_unlock_irqrestore(&rtc_lock, flags);
1175 pm_wakeup_hard_event(dev);
1176 acpi_clear_event(ACPI_EVENT_RTC);
1177 acpi_disable_event(ACPI_EVENT_RTC, 0);
1178 return ACPI_INTERRUPT_HANDLED;
1181 static inline void rtc_wake_setup(struct device *dev)
1183 acpi_install_fixed_event_handler(ACPI_EVENT_RTC, rtc_handler, dev);
1185 * After the RTC handler is installed, the Fixed_RTC event should
1186 * be disabled. Only when the RTC alarm is set will it be enabled.
1188 acpi_clear_event(ACPI_EVENT_RTC);
1189 acpi_disable_event(ACPI_EVENT_RTC, 0);
1192 static void rtc_wake_on(struct device *dev)
1194 acpi_clear_event(ACPI_EVENT_RTC);
1195 acpi_enable_event(ACPI_EVENT_RTC, 0);
1198 static void rtc_wake_off(struct device *dev)
1200 acpi_disable_event(ACPI_EVENT_RTC, 0);
1204 /* Enable use_acpi_alarm mode for Intel platforms no earlier than 2015 */
1205 static void use_acpi_alarm_quirks(void)
1209 if (boot_cpu_data.x86_vendor != X86_VENDOR_INTEL)
1212 if (!(acpi_gbl_FADT.flags & ACPI_FADT_LOW_POWER_S0))
1215 if (!is_hpet_enabled())
1218 if (dmi_get_date(DMI_BIOS_DATE, &year, NULL, NULL) && year >= 2015)
1219 use_acpi_alarm = true;
1222 static inline void use_acpi_alarm_quirks(void) { }
1225 /* Every ACPI platform has a mc146818 compatible "cmos rtc". Here we find
1226 * its device node and pass extra config data. This helps its driver use
1227 * capabilities that the now-obsolete mc146818 didn't have, and informs it
1228 * that this board's RTC is wakeup-capable (per ACPI spec).
1230 static struct cmos_rtc_board_info acpi_rtc_info;
1232 static void cmos_wake_setup(struct device *dev)
1237 use_acpi_alarm_quirks();
1239 rtc_wake_setup(dev);
1240 acpi_rtc_info.wake_on = rtc_wake_on;
1241 acpi_rtc_info.wake_off = rtc_wake_off;
1243 /* workaround bug in some ACPI tables */
1244 if (acpi_gbl_FADT.month_alarm && !acpi_gbl_FADT.day_alarm) {
1245 dev_dbg(dev, "bogus FADT month_alarm (%d)\n",
1246 acpi_gbl_FADT.month_alarm);
1247 acpi_gbl_FADT.month_alarm = 0;
1250 acpi_rtc_info.rtc_day_alarm = acpi_gbl_FADT.day_alarm;
1251 acpi_rtc_info.rtc_mon_alarm = acpi_gbl_FADT.month_alarm;
1252 acpi_rtc_info.rtc_century = acpi_gbl_FADT.century;
1254 /* NOTE: S4_RTC_WAKE is NOT currently useful to Linux */
1255 if (acpi_gbl_FADT.flags & ACPI_FADT_S4_RTC_WAKE)
1256 dev_info(dev, "RTC can wake from S4\n");
1258 dev->platform_data = &acpi_rtc_info;
1260 /* RTC always wakes from S1/S2/S3, and often S4/STD */
1261 device_init_wakeup(dev, 1);
1264 static void cmos_check_acpi_rtc_status(struct device *dev,
1265 unsigned char *rtc_control)
1267 struct cmos_rtc *cmos = dev_get_drvdata(dev);
1268 acpi_event_status rtc_status;
1271 if (acpi_gbl_FADT.flags & ACPI_FADT_FIXED_RTC)
1274 status = acpi_get_event_status(ACPI_EVENT_RTC, &rtc_status);
1275 if (ACPI_FAILURE(status)) {
1276 dev_err(dev, "Could not get RTC status\n");
1277 } else if (rtc_status & ACPI_EVENT_FLAG_SET) {
1279 *rtc_control &= ~RTC_AIE;
1280 CMOS_WRITE(*rtc_control, RTC_CONTROL);
1281 mask = CMOS_READ(RTC_INTR_FLAGS);
1282 rtc_update_irq(cmos->rtc, 1, mask);
1288 static void cmos_wake_setup(struct device *dev)
1292 static void cmos_check_acpi_rtc_status(struct device *dev,
1293 unsigned char *rtc_control)
1301 #include <linux/pnp.h>
1303 static int cmos_pnp_probe(struct pnp_dev *pnp, const struct pnp_device_id *id)
1305 cmos_wake_setup(&pnp->dev);
1307 if (pnp_port_start(pnp, 0) == 0x70 && !pnp_irq_valid(pnp, 0)) {
1308 unsigned int irq = 0;
1310 /* Some machines contain a PNP entry for the RTC, but
1311 * don't define the IRQ. It should always be safe to
1312 * hardcode it on systems with a legacy PIC.
1314 if (nr_legacy_irqs())
1317 return cmos_do_probe(&pnp->dev,
1318 pnp_get_resource(pnp, IORESOURCE_IO, 0), irq);
1320 return cmos_do_probe(&pnp->dev,
1321 pnp_get_resource(pnp, IORESOURCE_IO, 0),
1326 static void cmos_pnp_remove(struct pnp_dev *pnp)
1328 cmos_do_remove(&pnp->dev);
1331 static void cmos_pnp_shutdown(struct pnp_dev *pnp)
1333 struct device *dev = &pnp->dev;
1334 struct cmos_rtc *cmos = dev_get_drvdata(dev);
1336 if (system_state == SYSTEM_POWER_OFF) {
1337 int retval = cmos_poweroff(dev);
1339 if (cmos_aie_poweroff(dev) < 0 && !retval)
1343 cmos_do_shutdown(cmos->irq);
1346 static const struct pnp_device_id rtc_ids[] = {
1347 { .id = "PNP0b00", },
1348 { .id = "PNP0b01", },
1349 { .id = "PNP0b02", },
1352 MODULE_DEVICE_TABLE(pnp, rtc_ids);
1354 static struct pnp_driver cmos_pnp_driver = {
1355 .name = (char *) driver_name,
1356 .id_table = rtc_ids,
1357 .probe = cmos_pnp_probe,
1358 .remove = cmos_pnp_remove,
1359 .shutdown = cmos_pnp_shutdown,
1361 /* flag ensures resume() gets called, and stops syslog spam */
1362 .flags = PNP_DRIVER_RES_DO_NOT_CHANGE,
1368 #endif /* CONFIG_PNP */
1371 static const struct of_device_id of_cmos_match[] = {
1373 .compatible = "motorola,mc146818",
1377 MODULE_DEVICE_TABLE(of, of_cmos_match);
1379 static __init void cmos_of_init(struct platform_device *pdev)
1381 struct device_node *node = pdev->dev.of_node;
1387 val = of_get_property(node, "ctrl-reg", NULL);
1389 CMOS_WRITE(be32_to_cpup(val), RTC_CONTROL);
1391 val = of_get_property(node, "freq-reg", NULL);
1393 CMOS_WRITE(be32_to_cpup(val), RTC_FREQ_SELECT);
1396 static inline void cmos_of_init(struct platform_device *pdev) {}
1398 /*----------------------------------------------------------------*/
1400 /* Platform setup should have set up an RTC device, when PNP is
1401 * unavailable ... this could happen even on (older) PCs.
1404 static int __init cmos_platform_probe(struct platform_device *pdev)
1406 struct resource *resource;
1410 cmos_wake_setup(&pdev->dev);
1413 resource = platform_get_resource(pdev, IORESOURCE_IO, 0);
1415 resource = platform_get_resource(pdev, IORESOURCE_MEM, 0);
1416 irq = platform_get_irq(pdev, 0);
1420 return cmos_do_probe(&pdev->dev, resource, irq);
1423 static int cmos_platform_remove(struct platform_device *pdev)
1425 cmos_do_remove(&pdev->dev);
1429 static void cmos_platform_shutdown(struct platform_device *pdev)
1431 struct device *dev = &pdev->dev;
1432 struct cmos_rtc *cmos = dev_get_drvdata(dev);
1434 if (system_state == SYSTEM_POWER_OFF) {
1435 int retval = cmos_poweroff(dev);
1437 if (cmos_aie_poweroff(dev) < 0 && !retval)
1441 cmos_do_shutdown(cmos->irq);
1444 /* work with hotplug and coldplug */
1445 MODULE_ALIAS("platform:rtc_cmos");
1447 static struct platform_driver cmos_platform_driver = {
1448 .remove = cmos_platform_remove,
1449 .shutdown = cmos_platform_shutdown,
1451 .name = driver_name,
1453 .of_match_table = of_match_ptr(of_cmos_match),
1458 static bool pnp_driver_registered;
1460 static bool platform_driver_registered;
1462 static int __init cmos_init(void)
1467 retval = pnp_register_driver(&cmos_pnp_driver);
1469 pnp_driver_registered = true;
1472 if (!cmos_rtc.dev) {
1473 retval = platform_driver_probe(&cmos_platform_driver,
1474 cmos_platform_probe);
1476 platform_driver_registered = true;
1483 if (pnp_driver_registered)
1484 pnp_unregister_driver(&cmos_pnp_driver);
1488 module_init(cmos_init);
1490 static void __exit cmos_exit(void)
1493 if (pnp_driver_registered)
1494 pnp_unregister_driver(&cmos_pnp_driver);
1496 if (platform_driver_registered)
1497 platform_driver_unregister(&cmos_platform_driver);
1499 module_exit(cmos_exit);
1502 MODULE_AUTHOR("David Brownell");
1503 MODULE_DESCRIPTION("Driver for PC-style 'CMOS' RTCs");
1504 MODULE_LICENSE("GPL");