hwmon: (stts751) buffer overrun on wrong chip configuration
[linux-2.6/btrfs-unstable.git] / drivers / rtc / rtc-cmos.c
blob9dca53df35845cc64366a5428d9927bff7f28220
1 /*
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>
41 #include <linux/pm.h>
42 #include <linux/of.h>
43 #include <linux/of_platform.h>
44 #ifdef CONFIG_X86
45 #include <asm/i8259.h>
46 #endif
48 /* this is for "generic access to PC-style RTC" using CMOS_READ/CMOS_WRITE */
49 #include <linux/mc146818rtc.h>
51 struct cmos_rtc {
52 struct rtc_device *rtc;
53 struct device *dev;
54 int irq;
55 struct resource *iomem;
56 time64_t alarm_expires;
58 void (*wake_on)(struct device *);
59 void (*wake_off)(struct device *);
61 u8 enabled_wake;
62 u8 suspend_ctrl;
64 /* newer hardware extends the original register set */
65 u8 day_alrm;
66 u8 mon_alrm;
67 u8 century;
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))
86 return 0;
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
96 * other (better) use.
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>
104 #else
106 static inline int is_hpet_enabled(void)
108 return 0;
111 static inline int hpet_mask_rtc_irq_bit(unsigned long mask)
113 return 0;
116 static inline int hpet_set_rtc_irq_bit(unsigned long mask)
118 return 0;
121 static inline int
122 hpet_set_alarm_time(unsigned char hrs, unsigned char min, unsigned char sec)
124 return 0;
127 static inline int hpet_set_periodic_freq(unsigned long freq)
129 return 0;
132 static inline int hpet_rtc_dropped_irq(void)
134 return 0;
137 static inline int hpet_rtc_timer_init(void)
139 return 0;
142 extern irq_handler_t hpet_rtc_interrupt;
144 static inline int hpet_register_irq_handler(irq_handler_t handler)
146 return 0;
149 static inline int hpet_unregister_irq_handler(irq_handler_t handler)
151 return 0;
154 #endif
156 /*----------------------------------------------------------------*/
158 #ifdef RTC_PORT
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));
178 #else
180 #define can_bank2 false
182 static inline unsigned char cmos_read_bank2(unsigned char addr)
184 return 0;
187 static inline void cmos_write_bank2(unsigned char val, unsigned char addr)
191 #endif
193 /*----------------------------------------------------------------*/
195 static int cmos_read_time(struct device *dev, struct rtc_time *t)
198 * If pm_trace abused the RTC for storage, set the timespec to 0,
199 * which tells the caller that this RTC value is unusable.
201 if (!pm_trace_rtc_valid())
202 return -EIO;
204 /* REVISIT: if the clock has a "century" register, use
205 * that instead of the heuristic in mc146818_get_time().
206 * That'll make Y3K compatility (year > 2070) easy!
208 mc146818_get_time(t);
209 return 0;
212 static int cmos_set_time(struct device *dev, struct rtc_time *t)
214 /* REVISIT: set the "century" register if available
216 * NOTE: this ignores the issue whereby updating the seconds
217 * takes effect exactly 500ms after we write the register.
218 * (Also queueing and other delays before we get this far.)
220 return mc146818_set_time(t);
223 static int cmos_read_alarm(struct device *dev, struct rtc_wkalrm *t)
225 struct cmos_rtc *cmos = dev_get_drvdata(dev);
226 unsigned char rtc_control;
228 if (!is_valid_irq(cmos->irq))
229 return -EIO;
231 /* Basic alarms only support hour, minute, and seconds fields.
232 * Some also support day and month, for alarms up to a year in
233 * the future.
236 spin_lock_irq(&rtc_lock);
237 t->time.tm_sec = CMOS_READ(RTC_SECONDS_ALARM);
238 t->time.tm_min = CMOS_READ(RTC_MINUTES_ALARM);
239 t->time.tm_hour = CMOS_READ(RTC_HOURS_ALARM);
241 if (cmos->day_alrm) {
242 /* ignore upper bits on readback per ACPI spec */
243 t->time.tm_mday = CMOS_READ(cmos->day_alrm) & 0x3f;
244 if (!t->time.tm_mday)
245 t->time.tm_mday = -1;
247 if (cmos->mon_alrm) {
248 t->time.tm_mon = CMOS_READ(cmos->mon_alrm);
249 if (!t->time.tm_mon)
250 t->time.tm_mon = -1;
254 rtc_control = CMOS_READ(RTC_CONTROL);
255 spin_unlock_irq(&rtc_lock);
257 if (!(rtc_control & RTC_DM_BINARY) || RTC_ALWAYS_BCD) {
258 if (((unsigned)t->time.tm_sec) < 0x60)
259 t->time.tm_sec = bcd2bin(t->time.tm_sec);
260 else
261 t->time.tm_sec = -1;
262 if (((unsigned)t->time.tm_min) < 0x60)
263 t->time.tm_min = bcd2bin(t->time.tm_min);
264 else
265 t->time.tm_min = -1;
266 if (((unsigned)t->time.tm_hour) < 0x24)
267 t->time.tm_hour = bcd2bin(t->time.tm_hour);
268 else
269 t->time.tm_hour = -1;
271 if (cmos->day_alrm) {
272 if (((unsigned)t->time.tm_mday) <= 0x31)
273 t->time.tm_mday = bcd2bin(t->time.tm_mday);
274 else
275 t->time.tm_mday = -1;
277 if (cmos->mon_alrm) {
278 if (((unsigned)t->time.tm_mon) <= 0x12)
279 t->time.tm_mon = bcd2bin(t->time.tm_mon)-1;
280 else
281 t->time.tm_mon = -1;
286 t->enabled = !!(rtc_control & RTC_AIE);
287 t->pending = 0;
289 return 0;
292 static void cmos_checkintr(struct cmos_rtc *cmos, unsigned char rtc_control)
294 unsigned char rtc_intr;
296 /* NOTE after changing RTC_xIE bits we always read INTR_FLAGS;
297 * allegedly some older rtcs need that to handle irqs properly
299 rtc_intr = CMOS_READ(RTC_INTR_FLAGS);
301 if (is_hpet_enabled())
302 return;
304 rtc_intr &= (rtc_control & RTC_IRQMASK) | RTC_IRQF;
305 if (is_intr(rtc_intr))
306 rtc_update_irq(cmos->rtc, 1, rtc_intr);
309 static void cmos_irq_enable(struct cmos_rtc *cmos, unsigned char mask)
311 unsigned char rtc_control;
313 /* flush any pending IRQ status, notably for update irqs,
314 * before we enable new IRQs
316 rtc_control = CMOS_READ(RTC_CONTROL);
317 cmos_checkintr(cmos, rtc_control);
319 rtc_control |= mask;
320 CMOS_WRITE(rtc_control, RTC_CONTROL);
321 hpet_set_rtc_irq_bit(mask);
323 cmos_checkintr(cmos, rtc_control);
326 static void cmos_irq_disable(struct cmos_rtc *cmos, unsigned char mask)
328 unsigned char rtc_control;
330 rtc_control = CMOS_READ(RTC_CONTROL);
331 rtc_control &= ~mask;
332 CMOS_WRITE(rtc_control, RTC_CONTROL);
333 hpet_mask_rtc_irq_bit(mask);
335 cmos_checkintr(cmos, rtc_control);
338 static int cmos_validate_alarm(struct device *dev, struct rtc_wkalrm *t)
340 struct cmos_rtc *cmos = dev_get_drvdata(dev);
341 struct rtc_time now;
343 cmos_read_time(dev, &now);
345 if (!cmos->day_alrm) {
346 time64_t t_max_date;
347 time64_t t_alrm;
349 t_max_date = rtc_tm_to_time64(&now);
350 t_max_date += 24 * 60 * 60 - 1;
351 t_alrm = rtc_tm_to_time64(&t->time);
352 if (t_alrm > t_max_date) {
353 dev_err(dev,
354 "Alarms can be up to one day in the future\n");
355 return -EINVAL;
357 } else if (!cmos->mon_alrm) {
358 struct rtc_time max_date = now;
359 time64_t t_max_date;
360 time64_t t_alrm;
361 int max_mday;
363 if (max_date.tm_mon == 11) {
364 max_date.tm_mon = 0;
365 max_date.tm_year += 1;
366 } else {
367 max_date.tm_mon += 1;
369 max_mday = rtc_month_days(max_date.tm_mon, max_date.tm_year);
370 if (max_date.tm_mday > max_mday)
371 max_date.tm_mday = max_mday;
373 t_max_date = rtc_tm_to_time64(&max_date);
374 t_max_date -= 1;
375 t_alrm = rtc_tm_to_time64(&t->time);
376 if (t_alrm > t_max_date) {
377 dev_err(dev,
378 "Alarms can be up to one month in the future\n");
379 return -EINVAL;
381 } else {
382 struct rtc_time max_date = now;
383 time64_t t_max_date;
384 time64_t t_alrm;
385 int max_mday;
387 max_date.tm_year += 1;
388 max_mday = rtc_month_days(max_date.tm_mon, max_date.tm_year);
389 if (max_date.tm_mday > max_mday)
390 max_date.tm_mday = max_mday;
392 t_max_date = rtc_tm_to_time64(&max_date);
393 t_max_date -= 1;
394 t_alrm = rtc_tm_to_time64(&t->time);
395 if (t_alrm > t_max_date) {
396 dev_err(dev,
397 "Alarms can be up to one year in the future\n");
398 return -EINVAL;
402 return 0;
405 static int cmos_set_alarm(struct device *dev, struct rtc_wkalrm *t)
407 struct cmos_rtc *cmos = dev_get_drvdata(dev);
408 unsigned char mon, mday, hrs, min, sec, rtc_control;
409 int ret;
411 if (!is_valid_irq(cmos->irq))
412 return -EIO;
414 ret = cmos_validate_alarm(dev, t);
415 if (ret < 0)
416 return ret;
418 mon = t->time.tm_mon + 1;
419 mday = t->time.tm_mday;
420 hrs = t->time.tm_hour;
421 min = t->time.tm_min;
422 sec = t->time.tm_sec;
424 rtc_control = CMOS_READ(RTC_CONTROL);
425 if (!(rtc_control & RTC_DM_BINARY) || RTC_ALWAYS_BCD) {
426 /* Writing 0xff means "don't care" or "match all". */
427 mon = (mon <= 12) ? bin2bcd(mon) : 0xff;
428 mday = (mday >= 1 && mday <= 31) ? bin2bcd(mday) : 0xff;
429 hrs = (hrs < 24) ? bin2bcd(hrs) : 0xff;
430 min = (min < 60) ? bin2bcd(min) : 0xff;
431 sec = (sec < 60) ? bin2bcd(sec) : 0xff;
434 spin_lock_irq(&rtc_lock);
436 /* next rtc irq must not be from previous alarm setting */
437 cmos_irq_disable(cmos, RTC_AIE);
439 /* update alarm */
440 CMOS_WRITE(hrs, RTC_HOURS_ALARM);
441 CMOS_WRITE(min, RTC_MINUTES_ALARM);
442 CMOS_WRITE(sec, RTC_SECONDS_ALARM);
444 /* the system may support an "enhanced" alarm */
445 if (cmos->day_alrm) {
446 CMOS_WRITE(mday, cmos->day_alrm);
447 if (cmos->mon_alrm)
448 CMOS_WRITE(mon, cmos->mon_alrm);
451 /* FIXME the HPET alarm glue currently ignores day_alrm
452 * and mon_alrm ...
454 hpet_set_alarm_time(t->time.tm_hour, t->time.tm_min, t->time.tm_sec);
456 if (t->enabled)
457 cmos_irq_enable(cmos, RTC_AIE);
459 spin_unlock_irq(&rtc_lock);
461 cmos->alarm_expires = rtc_tm_to_time64(&t->time);
463 return 0;
466 static int cmos_alarm_irq_enable(struct device *dev, unsigned int enabled)
468 struct cmos_rtc *cmos = dev_get_drvdata(dev);
469 unsigned long flags;
471 if (!is_valid_irq(cmos->irq))
472 return -EINVAL;
474 spin_lock_irqsave(&rtc_lock, flags);
476 if (enabled)
477 cmos_irq_enable(cmos, RTC_AIE);
478 else
479 cmos_irq_disable(cmos, RTC_AIE);
481 spin_unlock_irqrestore(&rtc_lock, flags);
482 return 0;
485 #if IS_ENABLED(CONFIG_RTC_INTF_PROC)
487 static int cmos_procfs(struct device *dev, struct seq_file *seq)
489 struct cmos_rtc *cmos = dev_get_drvdata(dev);
490 unsigned char rtc_control, valid;
492 spin_lock_irq(&rtc_lock);
493 rtc_control = CMOS_READ(RTC_CONTROL);
494 valid = CMOS_READ(RTC_VALID);
495 spin_unlock_irq(&rtc_lock);
497 /* NOTE: at least ICH6 reports battery status using a different
498 * (non-RTC) bit; and SQWE is ignored on many current systems.
500 seq_printf(seq,
501 "periodic_IRQ\t: %s\n"
502 "update_IRQ\t: %s\n"
503 "HPET_emulated\t: %s\n"
504 // "square_wave\t: %s\n"
505 "BCD\t\t: %s\n"
506 "DST_enable\t: %s\n"
507 "periodic_freq\t: %d\n"
508 "batt_status\t: %s\n",
509 (rtc_control & RTC_PIE) ? "yes" : "no",
510 (rtc_control & RTC_UIE) ? "yes" : "no",
511 is_hpet_enabled() ? "yes" : "no",
512 // (rtc_control & RTC_SQWE) ? "yes" : "no",
513 (rtc_control & RTC_DM_BINARY) ? "no" : "yes",
514 (rtc_control & RTC_DST_EN) ? "yes" : "no",
515 cmos->rtc->irq_freq,
516 (valid & RTC_VRT) ? "okay" : "dead");
518 return 0;
521 #else
522 #define cmos_procfs NULL
523 #endif
525 static const struct rtc_class_ops cmos_rtc_ops = {
526 .read_time = cmos_read_time,
527 .set_time = cmos_set_time,
528 .read_alarm = cmos_read_alarm,
529 .set_alarm = cmos_set_alarm,
530 .proc = cmos_procfs,
531 .alarm_irq_enable = cmos_alarm_irq_enable,
534 /*----------------------------------------------------------------*/
537 * All these chips have at least 64 bytes of address space, shared by
538 * RTC registers and NVRAM. Most of those bytes of NVRAM are used
539 * by boot firmware. Modern chips have 128 or 256 bytes.
542 #define NVRAM_OFFSET (RTC_REG_D + 1)
544 static ssize_t
545 cmos_nvram_read(struct file *filp, struct kobject *kobj,
546 struct bin_attribute *attr,
547 char *buf, loff_t off, size_t count)
549 int retval;
551 off += NVRAM_OFFSET;
552 spin_lock_irq(&rtc_lock);
553 for (retval = 0; count; count--, off++, retval++) {
554 if (off < 128)
555 *buf++ = CMOS_READ(off);
556 else if (can_bank2)
557 *buf++ = cmos_read_bank2(off);
558 else
559 break;
561 spin_unlock_irq(&rtc_lock);
563 return retval;
566 static ssize_t
567 cmos_nvram_write(struct file *filp, struct kobject *kobj,
568 struct bin_attribute *attr,
569 char *buf, loff_t off, size_t count)
571 struct cmos_rtc *cmos;
572 int retval;
574 cmos = dev_get_drvdata(container_of(kobj, struct device, kobj));
576 /* NOTE: on at least PCs and Ataris, the boot firmware uses a
577 * checksum on part of the NVRAM data. That's currently ignored
578 * here. If userspace is smart enough to know what fields of
579 * NVRAM to update, updating checksums is also part of its job.
581 off += NVRAM_OFFSET;
582 spin_lock_irq(&rtc_lock);
583 for (retval = 0; count; count--, off++, retval++) {
584 /* don't trash RTC registers */
585 if (off == cmos->day_alrm
586 || off == cmos->mon_alrm
587 || off == cmos->century)
588 buf++;
589 else if (off < 128)
590 CMOS_WRITE(*buf++, off);
591 else if (can_bank2)
592 cmos_write_bank2(*buf++, off);
593 else
594 break;
596 spin_unlock_irq(&rtc_lock);
598 return retval;
601 static struct bin_attribute nvram = {
602 .attr = {
603 .name = "nvram",
604 .mode = S_IRUGO | S_IWUSR,
607 .read = cmos_nvram_read,
608 .write = cmos_nvram_write,
609 /* size gets set up later */
612 /*----------------------------------------------------------------*/
614 static struct cmos_rtc cmos_rtc;
616 static irqreturn_t cmos_interrupt(int irq, void *p)
618 u8 irqstat;
619 u8 rtc_control;
621 spin_lock(&rtc_lock);
623 /* When the HPET interrupt handler calls us, the interrupt
624 * status is passed as arg1 instead of the irq number. But
625 * always clear irq status, even when HPET is in the way.
627 * Note that HPET and RTC are almost certainly out of phase,
628 * giving different IRQ status ...
630 irqstat = CMOS_READ(RTC_INTR_FLAGS);
631 rtc_control = CMOS_READ(RTC_CONTROL);
632 if (is_hpet_enabled())
633 irqstat = (unsigned long)irq & 0xF0;
635 /* If we were suspended, RTC_CONTROL may not be accurate since the
636 * bios may have cleared it.
638 if (!cmos_rtc.suspend_ctrl)
639 irqstat &= (rtc_control & RTC_IRQMASK) | RTC_IRQF;
640 else
641 irqstat &= (cmos_rtc.suspend_ctrl & RTC_IRQMASK) | RTC_IRQF;
643 /* All Linux RTC alarms should be treated as if they were oneshot.
644 * Similar code may be needed in system wakeup paths, in case the
645 * alarm woke the system.
647 if (irqstat & RTC_AIE) {
648 cmos_rtc.suspend_ctrl &= ~RTC_AIE;
649 rtc_control &= ~RTC_AIE;
650 CMOS_WRITE(rtc_control, RTC_CONTROL);
651 hpet_mask_rtc_irq_bit(RTC_AIE);
652 CMOS_READ(RTC_INTR_FLAGS);
654 spin_unlock(&rtc_lock);
656 if (is_intr(irqstat)) {
657 rtc_update_irq(p, 1, irqstat);
658 return IRQ_HANDLED;
659 } else
660 return IRQ_NONE;
663 #ifdef CONFIG_PNP
664 #define INITSECTION
666 #else
667 #define INITSECTION __init
668 #endif
670 static int INITSECTION
671 cmos_do_probe(struct device *dev, struct resource *ports, int rtc_irq)
673 struct cmos_rtc_board_info *info = dev_get_platdata(dev);
674 int retval = 0;
675 unsigned char rtc_control;
676 unsigned address_space;
677 u32 flags = 0;
679 /* there can be only one ... */
680 if (cmos_rtc.dev)
681 return -EBUSY;
683 if (!ports)
684 return -ENODEV;
686 /* Claim I/O ports ASAP, minimizing conflict with legacy driver.
688 * REVISIT non-x86 systems may instead use memory space resources
689 * (needing ioremap etc), not i/o space resources like this ...
691 if (RTC_IOMAPPED)
692 ports = request_region(ports->start, resource_size(ports),
693 driver_name);
694 else
695 ports = request_mem_region(ports->start, resource_size(ports),
696 driver_name);
697 if (!ports) {
698 dev_dbg(dev, "i/o registers already in use\n");
699 return -EBUSY;
702 cmos_rtc.irq = rtc_irq;
703 cmos_rtc.iomem = ports;
705 /* Heuristic to deduce NVRAM size ... do what the legacy NVRAM
706 * driver did, but don't reject unknown configs. Old hardware
707 * won't address 128 bytes. Newer chips have multiple banks,
708 * though they may not be listed in one I/O resource.
710 #if defined(CONFIG_ATARI)
711 address_space = 64;
712 #elif defined(__i386__) || defined(__x86_64__) || defined(__arm__) \
713 || defined(__sparc__) || defined(__mips__) \
714 || defined(__powerpc__) || defined(CONFIG_MN10300)
715 address_space = 128;
716 #else
717 #warning Assuming 128 bytes of RTC+NVRAM address space, not 64 bytes.
718 address_space = 128;
719 #endif
720 if (can_bank2 && ports->end > (ports->start + 1))
721 address_space = 256;
723 /* For ACPI systems extension info comes from the FADT. On others,
724 * board specific setup provides it as appropriate. Systems where
725 * the alarm IRQ isn't automatically a wakeup IRQ (like ACPI, and
726 * some almost-clones) can provide hooks to make that behave.
728 * Note that ACPI doesn't preclude putting these registers into
729 * "extended" areas of the chip, including some that we won't yet
730 * expect CMOS_READ and friends to handle.
732 if (info) {
733 if (info->flags)
734 flags = info->flags;
735 if (info->address_space)
736 address_space = info->address_space;
738 if (info->rtc_day_alarm && info->rtc_day_alarm < 128)
739 cmos_rtc.day_alrm = info->rtc_day_alarm;
740 if (info->rtc_mon_alarm && info->rtc_mon_alarm < 128)
741 cmos_rtc.mon_alrm = info->rtc_mon_alarm;
742 if (info->rtc_century && info->rtc_century < 128)
743 cmos_rtc.century = info->rtc_century;
745 if (info->wake_on && info->wake_off) {
746 cmos_rtc.wake_on = info->wake_on;
747 cmos_rtc.wake_off = info->wake_off;
751 cmos_rtc.dev = dev;
752 dev_set_drvdata(dev, &cmos_rtc);
754 cmos_rtc.rtc = rtc_device_register(driver_name, dev,
755 &cmos_rtc_ops, THIS_MODULE);
756 if (IS_ERR(cmos_rtc.rtc)) {
757 retval = PTR_ERR(cmos_rtc.rtc);
758 goto cleanup0;
761 rename_region(ports, dev_name(&cmos_rtc.rtc->dev));
763 spin_lock_irq(&rtc_lock);
765 if (!(flags & CMOS_RTC_FLAGS_NOFREQ)) {
766 /* force periodic irq to CMOS reset default of 1024Hz;
768 * REVISIT it's been reported that at least one x86_64 ALI
769 * mobo doesn't use 32KHz here ... for portability we might
770 * need to do something about other clock frequencies.
772 cmos_rtc.rtc->irq_freq = 1024;
773 hpet_set_periodic_freq(cmos_rtc.rtc->irq_freq);
774 CMOS_WRITE(RTC_REF_CLCK_32KHZ | 0x06, RTC_FREQ_SELECT);
777 /* disable irqs */
778 if (is_valid_irq(rtc_irq))
779 cmos_irq_disable(&cmos_rtc, RTC_PIE | RTC_AIE | RTC_UIE);
781 rtc_control = CMOS_READ(RTC_CONTROL);
783 spin_unlock_irq(&rtc_lock);
785 if (is_valid_irq(rtc_irq) && !(rtc_control & RTC_24H)) {
786 dev_warn(dev, "only 24-hr supported\n");
787 retval = -ENXIO;
788 goto cleanup1;
791 hpet_rtc_timer_init();
793 if (is_valid_irq(rtc_irq)) {
794 irq_handler_t rtc_cmos_int_handler;
796 if (is_hpet_enabled()) {
797 rtc_cmos_int_handler = hpet_rtc_interrupt;
798 retval = hpet_register_irq_handler(cmos_interrupt);
799 if (retval) {
800 hpet_mask_rtc_irq_bit(RTC_IRQMASK);
801 dev_warn(dev, "hpet_register_irq_handler "
802 " failed in rtc_init().");
803 goto cleanup1;
805 } else
806 rtc_cmos_int_handler = cmos_interrupt;
808 retval = request_irq(rtc_irq, rtc_cmos_int_handler,
809 IRQF_SHARED, dev_name(&cmos_rtc.rtc->dev),
810 cmos_rtc.rtc);
811 if (retval < 0) {
812 dev_dbg(dev, "IRQ %d is already in use\n", rtc_irq);
813 goto cleanup1;
817 /* export at least the first block of NVRAM */
818 nvram.size = address_space - NVRAM_OFFSET;
819 retval = sysfs_create_bin_file(&dev->kobj, &nvram);
820 if (retval < 0) {
821 dev_dbg(dev, "can't create nvram file? %d\n", retval);
822 goto cleanup2;
825 dev_info(dev, "%s%s, %zd bytes nvram%s\n",
826 !is_valid_irq(rtc_irq) ? "no alarms" :
827 cmos_rtc.mon_alrm ? "alarms up to one year" :
828 cmos_rtc.day_alrm ? "alarms up to one month" :
829 "alarms up to one day",
830 cmos_rtc.century ? ", y3k" : "",
831 nvram.size,
832 is_hpet_enabled() ? ", hpet irqs" : "");
834 return 0;
836 cleanup2:
837 if (is_valid_irq(rtc_irq))
838 free_irq(rtc_irq, cmos_rtc.rtc);
839 cleanup1:
840 cmos_rtc.dev = NULL;
841 rtc_device_unregister(cmos_rtc.rtc);
842 cleanup0:
843 if (RTC_IOMAPPED)
844 release_region(ports->start, resource_size(ports));
845 else
846 release_mem_region(ports->start, resource_size(ports));
847 return retval;
850 static void cmos_do_shutdown(int rtc_irq)
852 spin_lock_irq(&rtc_lock);
853 if (is_valid_irq(rtc_irq))
854 cmos_irq_disable(&cmos_rtc, RTC_IRQMASK);
855 spin_unlock_irq(&rtc_lock);
858 static void cmos_do_remove(struct device *dev)
860 struct cmos_rtc *cmos = dev_get_drvdata(dev);
861 struct resource *ports;
863 cmos_do_shutdown(cmos->irq);
865 sysfs_remove_bin_file(&dev->kobj, &nvram);
867 if (is_valid_irq(cmos->irq)) {
868 free_irq(cmos->irq, cmos->rtc);
869 hpet_unregister_irq_handler(cmos_interrupt);
872 rtc_device_unregister(cmos->rtc);
873 cmos->rtc = NULL;
875 ports = cmos->iomem;
876 if (RTC_IOMAPPED)
877 release_region(ports->start, resource_size(ports));
878 else
879 release_mem_region(ports->start, resource_size(ports));
880 cmos->iomem = NULL;
882 cmos->dev = NULL;
885 static int cmos_aie_poweroff(struct device *dev)
887 struct cmos_rtc *cmos = dev_get_drvdata(dev);
888 struct rtc_time now;
889 time64_t t_now;
890 int retval = 0;
891 unsigned char rtc_control;
893 if (!cmos->alarm_expires)
894 return -EINVAL;
896 spin_lock_irq(&rtc_lock);
897 rtc_control = CMOS_READ(RTC_CONTROL);
898 spin_unlock_irq(&rtc_lock);
900 /* We only care about the situation where AIE is disabled. */
901 if (rtc_control & RTC_AIE)
902 return -EBUSY;
904 cmos_read_time(dev, &now);
905 t_now = rtc_tm_to_time64(&now);
908 * When enabling "RTC wake-up" in BIOS setup, the machine reboots
909 * automatically right after shutdown on some buggy boxes.
910 * This automatic rebooting issue won't happen when the alarm
911 * time is larger than now+1 seconds.
913 * If the alarm time is equal to now+1 seconds, the issue can be
914 * prevented by cancelling the alarm.
916 if (cmos->alarm_expires == t_now + 1) {
917 struct rtc_wkalrm alarm;
919 /* Cancel the AIE timer by configuring the past time. */
920 rtc_time64_to_tm(t_now - 1, &alarm.time);
921 alarm.enabled = 0;
922 retval = cmos_set_alarm(dev, &alarm);
923 } else if (cmos->alarm_expires > t_now + 1) {
924 retval = -EBUSY;
927 return retval;
930 static int cmos_suspend(struct device *dev)
932 struct cmos_rtc *cmos = dev_get_drvdata(dev);
933 unsigned char tmp;
935 /* only the alarm might be a wakeup event source */
936 spin_lock_irq(&rtc_lock);
937 cmos->suspend_ctrl = tmp = CMOS_READ(RTC_CONTROL);
938 if (tmp & (RTC_PIE|RTC_AIE|RTC_UIE)) {
939 unsigned char mask;
941 if (device_may_wakeup(dev))
942 mask = RTC_IRQMASK & ~RTC_AIE;
943 else
944 mask = RTC_IRQMASK;
945 tmp &= ~mask;
946 CMOS_WRITE(tmp, RTC_CONTROL);
947 hpet_mask_rtc_irq_bit(mask);
949 cmos_checkintr(cmos, tmp);
951 spin_unlock_irq(&rtc_lock);
953 if (tmp & RTC_AIE) {
954 cmos->enabled_wake = 1;
955 if (cmos->wake_on)
956 cmos->wake_on(dev);
957 else
958 enable_irq_wake(cmos->irq);
961 cmos_read_alarm(dev, &cmos->saved_wkalrm);
963 dev_dbg(dev, "suspend%s, ctrl %02x\n",
964 (tmp & RTC_AIE) ? ", alarm may wake" : "",
965 tmp);
967 return 0;
970 /* We want RTC alarms to wake us from e.g. ACPI G2/S5 "soft off", even
971 * after a detour through G3 "mechanical off", although the ACPI spec
972 * says wakeup should only work from G1/S4 "hibernate". To most users,
973 * distinctions between S4 and S5 are pointless. So when the hardware
974 * allows, don't draw that distinction.
976 static inline int cmos_poweroff(struct device *dev)
978 if (!IS_ENABLED(CONFIG_PM))
979 return -ENOSYS;
981 return cmos_suspend(dev);
984 static void cmos_check_wkalrm(struct device *dev)
986 struct cmos_rtc *cmos = dev_get_drvdata(dev);
987 struct rtc_wkalrm current_alarm;
988 time64_t t_current_expires;
989 time64_t t_saved_expires;
991 cmos_read_alarm(dev, &current_alarm);
992 t_current_expires = rtc_tm_to_time64(&current_alarm.time);
993 t_saved_expires = rtc_tm_to_time64(&cmos->saved_wkalrm.time);
994 if (t_current_expires != t_saved_expires ||
995 cmos->saved_wkalrm.enabled != current_alarm.enabled) {
996 cmos_set_alarm(dev, &cmos->saved_wkalrm);
1000 static void cmos_check_acpi_rtc_status(struct device *dev,
1001 unsigned char *rtc_control);
1003 static int __maybe_unused cmos_resume(struct device *dev)
1005 struct cmos_rtc *cmos = dev_get_drvdata(dev);
1006 unsigned char tmp;
1008 if (cmos->enabled_wake) {
1009 if (cmos->wake_off)
1010 cmos->wake_off(dev);
1011 else
1012 disable_irq_wake(cmos->irq);
1013 cmos->enabled_wake = 0;
1016 /* The BIOS might have changed the alarm, restore it */
1017 cmos_check_wkalrm(dev);
1019 spin_lock_irq(&rtc_lock);
1020 tmp = cmos->suspend_ctrl;
1021 cmos->suspend_ctrl = 0;
1022 /* re-enable any irqs previously active */
1023 if (tmp & RTC_IRQMASK) {
1024 unsigned char mask;
1026 if (device_may_wakeup(dev))
1027 hpet_rtc_timer_init();
1029 do {
1030 CMOS_WRITE(tmp, RTC_CONTROL);
1031 hpet_set_rtc_irq_bit(tmp & RTC_IRQMASK);
1033 mask = CMOS_READ(RTC_INTR_FLAGS);
1034 mask &= (tmp & RTC_IRQMASK) | RTC_IRQF;
1035 if (!is_hpet_enabled() || !is_intr(mask))
1036 break;
1038 /* force one-shot behavior if HPET blocked
1039 * the wake alarm's irq
1041 rtc_update_irq(cmos->rtc, 1, mask);
1042 tmp &= ~RTC_AIE;
1043 hpet_mask_rtc_irq_bit(RTC_AIE);
1044 } while (mask & RTC_AIE);
1046 if (tmp & RTC_AIE)
1047 cmos_check_acpi_rtc_status(dev, &tmp);
1049 spin_unlock_irq(&rtc_lock);
1051 dev_dbg(dev, "resume, ctrl %02x\n", tmp);
1053 return 0;
1056 static SIMPLE_DEV_PM_OPS(cmos_pm_ops, cmos_suspend, cmos_resume);
1058 /*----------------------------------------------------------------*/
1060 /* On non-x86 systems, a "CMOS" RTC lives most naturally on platform_bus.
1061 * ACPI systems always list these as PNPACPI devices, and pre-ACPI PCs
1062 * probably list them in similar PNPBIOS tables; so PNP is more common.
1064 * We don't use legacy "poke at the hardware" probing. Ancient PCs that
1065 * predate even PNPBIOS should set up platform_bus devices.
1068 #ifdef CONFIG_ACPI
1070 #include <linux/acpi.h>
1072 static u32 rtc_handler(void *context)
1074 struct device *dev = context;
1075 struct cmos_rtc *cmos = dev_get_drvdata(dev);
1076 unsigned char rtc_control = 0;
1077 unsigned char rtc_intr;
1078 unsigned long flags;
1080 spin_lock_irqsave(&rtc_lock, flags);
1081 if (cmos_rtc.suspend_ctrl)
1082 rtc_control = CMOS_READ(RTC_CONTROL);
1083 if (rtc_control & RTC_AIE) {
1084 cmos_rtc.suspend_ctrl &= ~RTC_AIE;
1085 CMOS_WRITE(rtc_control, RTC_CONTROL);
1086 rtc_intr = CMOS_READ(RTC_INTR_FLAGS);
1087 rtc_update_irq(cmos->rtc, 1, rtc_intr);
1089 spin_unlock_irqrestore(&rtc_lock, flags);
1091 pm_wakeup_hard_event(dev);
1092 acpi_clear_event(ACPI_EVENT_RTC);
1093 acpi_disable_event(ACPI_EVENT_RTC, 0);
1094 return ACPI_INTERRUPT_HANDLED;
1097 static inline void rtc_wake_setup(struct device *dev)
1099 acpi_install_fixed_event_handler(ACPI_EVENT_RTC, rtc_handler, dev);
1101 * After the RTC handler is installed, the Fixed_RTC event should
1102 * be disabled. Only when the RTC alarm is set will it be enabled.
1104 acpi_clear_event(ACPI_EVENT_RTC);
1105 acpi_disable_event(ACPI_EVENT_RTC, 0);
1108 static void rtc_wake_on(struct device *dev)
1110 acpi_clear_event(ACPI_EVENT_RTC);
1111 acpi_enable_event(ACPI_EVENT_RTC, 0);
1114 static void rtc_wake_off(struct device *dev)
1116 acpi_disable_event(ACPI_EVENT_RTC, 0);
1119 /* Every ACPI platform has a mc146818 compatible "cmos rtc". Here we find
1120 * its device node and pass extra config data. This helps its driver use
1121 * capabilities that the now-obsolete mc146818 didn't have, and informs it
1122 * that this board's RTC is wakeup-capable (per ACPI spec).
1124 static struct cmos_rtc_board_info acpi_rtc_info;
1126 static void cmos_wake_setup(struct device *dev)
1128 if (acpi_disabled)
1129 return;
1131 rtc_wake_setup(dev);
1132 acpi_rtc_info.wake_on = rtc_wake_on;
1133 acpi_rtc_info.wake_off = rtc_wake_off;
1135 /* workaround bug in some ACPI tables */
1136 if (acpi_gbl_FADT.month_alarm && !acpi_gbl_FADT.day_alarm) {
1137 dev_dbg(dev, "bogus FADT month_alarm (%d)\n",
1138 acpi_gbl_FADT.month_alarm);
1139 acpi_gbl_FADT.month_alarm = 0;
1142 acpi_rtc_info.rtc_day_alarm = acpi_gbl_FADT.day_alarm;
1143 acpi_rtc_info.rtc_mon_alarm = acpi_gbl_FADT.month_alarm;
1144 acpi_rtc_info.rtc_century = acpi_gbl_FADT.century;
1146 /* NOTE: S4_RTC_WAKE is NOT currently useful to Linux */
1147 if (acpi_gbl_FADT.flags & ACPI_FADT_S4_RTC_WAKE)
1148 dev_info(dev, "RTC can wake from S4\n");
1150 dev->platform_data = &acpi_rtc_info;
1152 /* RTC always wakes from S1/S2/S3, and often S4/STD */
1153 device_init_wakeup(dev, 1);
1156 static void cmos_check_acpi_rtc_status(struct device *dev,
1157 unsigned char *rtc_control)
1159 struct cmos_rtc *cmos = dev_get_drvdata(dev);
1160 acpi_event_status rtc_status;
1161 acpi_status status;
1163 if (acpi_gbl_FADT.flags & ACPI_FADT_FIXED_RTC)
1164 return;
1166 status = acpi_get_event_status(ACPI_EVENT_RTC, &rtc_status);
1167 if (ACPI_FAILURE(status)) {
1168 dev_err(dev, "Could not get RTC status\n");
1169 } else if (rtc_status & ACPI_EVENT_FLAG_SET) {
1170 unsigned char mask;
1171 *rtc_control &= ~RTC_AIE;
1172 CMOS_WRITE(*rtc_control, RTC_CONTROL);
1173 mask = CMOS_READ(RTC_INTR_FLAGS);
1174 rtc_update_irq(cmos->rtc, 1, mask);
1178 #else
1180 static void cmos_wake_setup(struct device *dev)
1184 static void cmos_check_acpi_rtc_status(struct device *dev,
1185 unsigned char *rtc_control)
1189 #endif
1191 #ifdef CONFIG_PNP
1193 #include <linux/pnp.h>
1195 static int cmos_pnp_probe(struct pnp_dev *pnp, const struct pnp_device_id *id)
1197 cmos_wake_setup(&pnp->dev);
1199 if (pnp_port_start(pnp, 0) == 0x70 && !pnp_irq_valid(pnp, 0)) {
1200 unsigned int irq = 0;
1201 #ifdef CONFIG_X86
1202 /* Some machines contain a PNP entry for the RTC, but
1203 * don't define the IRQ. It should always be safe to
1204 * hardcode it on systems with a legacy PIC.
1206 if (nr_legacy_irqs())
1207 irq = 8;
1208 #endif
1209 return cmos_do_probe(&pnp->dev,
1210 pnp_get_resource(pnp, IORESOURCE_IO, 0), irq);
1211 } else {
1212 return cmos_do_probe(&pnp->dev,
1213 pnp_get_resource(pnp, IORESOURCE_IO, 0),
1214 pnp_irq(pnp, 0));
1218 static void cmos_pnp_remove(struct pnp_dev *pnp)
1220 cmos_do_remove(&pnp->dev);
1223 static void cmos_pnp_shutdown(struct pnp_dev *pnp)
1225 struct device *dev = &pnp->dev;
1226 struct cmos_rtc *cmos = dev_get_drvdata(dev);
1228 if (system_state == SYSTEM_POWER_OFF) {
1229 int retval = cmos_poweroff(dev);
1231 if (cmos_aie_poweroff(dev) < 0 && !retval)
1232 return;
1235 cmos_do_shutdown(cmos->irq);
1238 static const struct pnp_device_id rtc_ids[] = {
1239 { .id = "PNP0b00", },
1240 { .id = "PNP0b01", },
1241 { .id = "PNP0b02", },
1242 { },
1244 MODULE_DEVICE_TABLE(pnp, rtc_ids);
1246 static struct pnp_driver cmos_pnp_driver = {
1247 .name = (char *) driver_name,
1248 .id_table = rtc_ids,
1249 .probe = cmos_pnp_probe,
1250 .remove = cmos_pnp_remove,
1251 .shutdown = cmos_pnp_shutdown,
1253 /* flag ensures resume() gets called, and stops syslog spam */
1254 .flags = PNP_DRIVER_RES_DO_NOT_CHANGE,
1255 .driver = {
1256 .pm = &cmos_pm_ops,
1260 #endif /* CONFIG_PNP */
1262 #ifdef CONFIG_OF
1263 static const struct of_device_id of_cmos_match[] = {
1265 .compatible = "motorola,mc146818",
1267 { },
1269 MODULE_DEVICE_TABLE(of, of_cmos_match);
1271 static __init void cmos_of_init(struct platform_device *pdev)
1273 struct device_node *node = pdev->dev.of_node;
1274 struct rtc_time time;
1275 int ret;
1276 const __be32 *val;
1278 if (!node)
1279 return;
1281 val = of_get_property(node, "ctrl-reg", NULL);
1282 if (val)
1283 CMOS_WRITE(be32_to_cpup(val), RTC_CONTROL);
1285 val = of_get_property(node, "freq-reg", NULL);
1286 if (val)
1287 CMOS_WRITE(be32_to_cpup(val), RTC_FREQ_SELECT);
1289 cmos_read_time(&pdev->dev, &time);
1290 ret = rtc_valid_tm(&time);
1291 if (ret) {
1292 struct rtc_time def_time = {
1293 .tm_year = 1,
1294 .tm_mday = 1,
1296 cmos_set_time(&pdev->dev, &def_time);
1299 #else
1300 static inline void cmos_of_init(struct platform_device *pdev) {}
1301 #endif
1302 /*----------------------------------------------------------------*/
1304 /* Platform setup should have set up an RTC device, when PNP is
1305 * unavailable ... this could happen even on (older) PCs.
1308 static int __init cmos_platform_probe(struct platform_device *pdev)
1310 struct resource *resource;
1311 int irq;
1313 cmos_of_init(pdev);
1314 cmos_wake_setup(&pdev->dev);
1316 if (RTC_IOMAPPED)
1317 resource = platform_get_resource(pdev, IORESOURCE_IO, 0);
1318 else
1319 resource = platform_get_resource(pdev, IORESOURCE_MEM, 0);
1320 irq = platform_get_irq(pdev, 0);
1321 if (irq < 0)
1322 irq = -1;
1324 return cmos_do_probe(&pdev->dev, resource, irq);
1327 static int cmos_platform_remove(struct platform_device *pdev)
1329 cmos_do_remove(&pdev->dev);
1330 return 0;
1333 static void cmos_platform_shutdown(struct platform_device *pdev)
1335 struct device *dev = &pdev->dev;
1336 struct cmos_rtc *cmos = dev_get_drvdata(dev);
1338 if (system_state == SYSTEM_POWER_OFF) {
1339 int retval = cmos_poweroff(dev);
1341 if (cmos_aie_poweroff(dev) < 0 && !retval)
1342 return;
1345 cmos_do_shutdown(cmos->irq);
1348 /* work with hotplug and coldplug */
1349 MODULE_ALIAS("platform:rtc_cmos");
1351 static struct platform_driver cmos_platform_driver = {
1352 .remove = cmos_platform_remove,
1353 .shutdown = cmos_platform_shutdown,
1354 .driver = {
1355 .name = driver_name,
1356 .pm = &cmos_pm_ops,
1357 .of_match_table = of_match_ptr(of_cmos_match),
1361 #ifdef CONFIG_PNP
1362 static bool pnp_driver_registered;
1363 #endif
1364 static bool platform_driver_registered;
1366 static int __init cmos_init(void)
1368 int retval = 0;
1370 #ifdef CONFIG_PNP
1371 retval = pnp_register_driver(&cmos_pnp_driver);
1372 if (retval == 0)
1373 pnp_driver_registered = true;
1374 #endif
1376 if (!cmos_rtc.dev) {
1377 retval = platform_driver_probe(&cmos_platform_driver,
1378 cmos_platform_probe);
1379 if (retval == 0)
1380 platform_driver_registered = true;
1383 if (retval == 0)
1384 return 0;
1386 #ifdef CONFIG_PNP
1387 if (pnp_driver_registered)
1388 pnp_unregister_driver(&cmos_pnp_driver);
1389 #endif
1390 return retval;
1392 module_init(cmos_init);
1394 static void __exit cmos_exit(void)
1396 #ifdef CONFIG_PNP
1397 if (pnp_driver_registered)
1398 pnp_unregister_driver(&cmos_pnp_driver);
1399 #endif
1400 if (platform_driver_registered)
1401 platform_driver_unregister(&cmos_platform_driver);
1403 module_exit(cmos_exit);
1406 MODULE_AUTHOR("David Brownell");
1407 MODULE_DESCRIPTION("Driver for PC-style 'CMOS' RTCs");
1408 MODULE_LICENSE("GPL");