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.
31 #include <linux/kernel.h>
32 #include <linux/module.h>
33 #include <linux/init.h>
34 #include <linux/interrupt.h>
35 #include <linux/spinlock.h>
36 #include <linux/platform_device.h>
37 #include <linux/mod_devicetable.h>
39 /* this is for "generic access to PC-style RTC" using CMOS_READ/CMOS_WRITE */
40 #include <asm-generic/rtc.h>
44 struct rtc_device *rtc;
47 struct resource *iomem;
49 void (*wake_on)(struct device *);
50 void (*wake_off)(struct device *);
55 /* newer hardware extends the original register set */
61 /* both platform and pnp busses use negative numbers for invalid irqs */
62 #define is_valid_irq(n) ((n) >= 0)
64 static const char driver_name[] = "rtc_cmos";
66 /* The RTC_INTR register may have e.g. RTC_PF set even if RTC_PIE is clear;
67 * always mask it against the irq enable bits in RTC_CONTROL. Bit values
68 * are the same: PF==PIE, AF=AIE, UF=UIE; so RTC_IRQMASK works with both.
70 #define RTC_IRQMASK (RTC_PF | RTC_AF | RTC_UF)
72 static inline int is_intr(u8 rtc_intr)
74 if (!(rtc_intr & RTC_IRQF))
76 return rtc_intr & RTC_IRQMASK;
79 /*----------------------------------------------------------------*/
81 static int cmos_read_time(struct device *dev, struct rtc_time *t)
83 /* REVISIT: if the clock has a "century" register, use
84 * that instead of the heuristic in get_rtc_time().
85 * That'll make Y3K compatility (year > 2070) easy!
91 static int cmos_set_time(struct device *dev, struct rtc_time *t)
93 /* REVISIT: set the "century" register if available
95 * NOTE: this ignores the issue whereby updating the seconds
96 * takes effect exactly 500ms after we write the register.
97 * (Also queueing and other delays before we get this far.)
99 return set_rtc_time(t);
102 static int cmos_read_alarm(struct device *dev, struct rtc_wkalrm *t)
104 struct cmos_rtc *cmos = dev_get_drvdata(dev);
105 unsigned char rtc_control;
107 if (!is_valid_irq(cmos->irq))
110 /* Basic alarms only support hour, minute, and seconds fields.
111 * Some also support day and month, for alarms up to a year in
114 t->time.tm_mday = -1;
117 spin_lock_irq(&rtc_lock);
118 t->time.tm_sec = CMOS_READ(RTC_SECONDS_ALARM);
119 t->time.tm_min = CMOS_READ(RTC_MINUTES_ALARM);
120 t->time.tm_hour = CMOS_READ(RTC_HOURS_ALARM);
122 if (cmos->day_alrm) {
123 t->time.tm_mday = CMOS_READ(cmos->day_alrm);
124 if (!t->time.tm_mday)
125 t->time.tm_mday = -1;
127 if (cmos->mon_alrm) {
128 t->time.tm_mon = CMOS_READ(cmos->mon_alrm);
134 rtc_control = CMOS_READ(RTC_CONTROL);
135 spin_unlock_irq(&rtc_lock);
137 /* REVISIT this assumes PC style usage: always BCD */
139 if (((unsigned)t->time.tm_sec) < 0x60)
140 t->time.tm_sec = BCD2BIN(t->time.tm_sec);
143 if (((unsigned)t->time.tm_min) < 0x60)
144 t->time.tm_min = BCD2BIN(t->time.tm_min);
147 if (((unsigned)t->time.tm_hour) < 0x24)
148 t->time.tm_hour = BCD2BIN(t->time.tm_hour);
150 t->time.tm_hour = -1;
152 if (cmos->day_alrm) {
153 if (((unsigned)t->time.tm_mday) <= 0x31)
154 t->time.tm_mday = BCD2BIN(t->time.tm_mday);
156 t->time.tm_mday = -1;
157 if (cmos->mon_alrm) {
158 if (((unsigned)t->time.tm_mon) <= 0x12)
159 t->time.tm_mon = BCD2BIN(t->time.tm_mon) - 1;
164 t->time.tm_year = -1;
166 t->enabled = !!(rtc_control & RTC_AIE);
172 static int cmos_set_alarm(struct device *dev, struct rtc_wkalrm *t)
174 struct cmos_rtc *cmos = dev_get_drvdata(dev);
175 unsigned char mon, mday, hrs, min, sec;
176 unsigned char rtc_control, rtc_intr;
178 if (!is_valid_irq(cmos->irq))
181 /* REVISIT this assumes PC style usage: always BCD */
183 /* Writing 0xff means "don't care" or "match all". */
185 mon = t->time.tm_mon;
186 mon = (mon < 12) ? BIN2BCD(mon) : 0xff;
189 mday = t->time.tm_mday;
190 mday = (mday >= 1 && mday <= 31) ? BIN2BCD(mday) : 0xff;
192 hrs = t->time.tm_hour;
193 hrs = (hrs < 24) ? BIN2BCD(hrs) : 0xff;
195 min = t->time.tm_min;
196 min = (min < 60) ? BIN2BCD(min) : 0xff;
198 sec = t->time.tm_sec;
199 sec = (sec < 60) ? BIN2BCD(sec) : 0xff;
201 spin_lock_irq(&rtc_lock);
203 /* next rtc irq must not be from previous alarm setting */
204 rtc_control = CMOS_READ(RTC_CONTROL);
205 rtc_control &= ~RTC_AIE;
206 CMOS_WRITE(rtc_control, RTC_CONTROL);
207 rtc_intr = CMOS_READ(RTC_INTR_FLAGS);
208 rtc_intr &= (rtc_control & RTC_IRQMASK) | RTC_IRQF;
209 if (is_intr(rtc_intr))
210 rtc_update_irq(cmos->rtc, 1, rtc_intr);
213 CMOS_WRITE(hrs, RTC_HOURS_ALARM);
214 CMOS_WRITE(min, RTC_MINUTES_ALARM);
215 CMOS_WRITE(sec, RTC_SECONDS_ALARM);
217 /* the system may support an "enhanced" alarm */
218 if (cmos->day_alrm) {
219 CMOS_WRITE(mday, cmos->day_alrm);
221 CMOS_WRITE(mon, cmos->mon_alrm);
225 rtc_control |= RTC_AIE;
226 CMOS_WRITE(rtc_control, RTC_CONTROL);
227 rtc_intr = CMOS_READ(RTC_INTR_FLAGS);
228 rtc_intr &= (rtc_control & RTC_IRQMASK) | RTC_IRQF;
229 if (is_intr(rtc_intr))
230 rtc_update_irq(cmos->rtc, 1, rtc_intr);
233 spin_unlock_irq(&rtc_lock);
238 static int cmos_irq_set_freq(struct device *dev, int freq)
240 struct cmos_rtc *cmos = dev_get_drvdata(dev);
244 if (!is_valid_irq(cmos->irq))
247 /* 0 = no irqs; 1 = 2^15 Hz ... 15 = 2^0 Hz */
253 spin_lock_irqsave(&rtc_lock, flags);
254 CMOS_WRITE(RTC_REF_CLCK_32KHZ | f, RTC_FREQ_SELECT);
255 spin_unlock_irqrestore(&rtc_lock, flags);
260 static int cmos_irq_set_state(struct device *dev, int enabled)
262 struct cmos_rtc *cmos = dev_get_drvdata(dev);
263 unsigned char rtc_control, rtc_intr;
266 if (!is_valid_irq(cmos->irq))
269 spin_lock_irqsave(&rtc_lock, flags);
270 rtc_control = CMOS_READ(RTC_CONTROL);
273 rtc_control |= RTC_PIE;
275 rtc_control &= ~RTC_PIE;
277 CMOS_WRITE(rtc_control, RTC_CONTROL);
279 rtc_intr = CMOS_READ(RTC_INTR_FLAGS);
280 rtc_intr &= (rtc_control & RTC_IRQMASK) | RTC_IRQF;
281 if (is_intr(rtc_intr))
282 rtc_update_irq(cmos->rtc, 1, rtc_intr);
284 spin_unlock_irqrestore(&rtc_lock, flags);
288 #if defined(CONFIG_RTC_INTF_DEV) || defined(CONFIG_RTC_INTF_DEV_MODULE)
291 cmos_rtc_ioctl(struct device *dev, unsigned int cmd, unsigned long arg)
293 struct cmos_rtc *cmos = dev_get_drvdata(dev);
294 unsigned char rtc_control, rtc_intr;
304 if (!is_valid_irq(cmos->irq))
311 spin_lock_irqsave(&rtc_lock, flags);
312 rtc_control = CMOS_READ(RTC_CONTROL);
314 case RTC_AIE_OFF: /* alarm off */
315 rtc_control &= ~RTC_AIE;
317 case RTC_AIE_ON: /* alarm on */
318 rtc_control |= RTC_AIE;
320 case RTC_UIE_OFF: /* update off */
321 rtc_control &= ~RTC_UIE;
323 case RTC_UIE_ON: /* update on */
324 rtc_control |= RTC_UIE;
326 case RTC_PIE_OFF: /* periodic off */
327 rtc_control &= ~RTC_PIE;
329 case RTC_PIE_ON: /* periodic on */
330 rtc_control |= RTC_PIE;
333 CMOS_WRITE(rtc_control, RTC_CONTROL);
334 rtc_intr = CMOS_READ(RTC_INTR_FLAGS);
335 rtc_intr &= (rtc_control & RTC_IRQMASK) | RTC_IRQF;
336 if (is_intr(rtc_intr))
337 rtc_update_irq(cmos->rtc, 1, rtc_intr);
338 spin_unlock_irqrestore(&rtc_lock, flags);
343 #define cmos_rtc_ioctl NULL
346 #if defined(CONFIG_RTC_INTF_PROC) || defined(CONFIG_RTC_INTF_PROC_MODULE)
348 static int cmos_procfs(struct device *dev, struct seq_file *seq)
350 struct cmos_rtc *cmos = dev_get_drvdata(dev);
351 unsigned char rtc_control, valid;
353 spin_lock_irq(&rtc_lock);
354 rtc_control = CMOS_READ(RTC_CONTROL);
355 valid = CMOS_READ(RTC_VALID);
356 spin_unlock_irq(&rtc_lock);
358 /* NOTE: at least ICH6 reports battery status using a different
359 * (non-RTC) bit; and SQWE is ignored on many current systems.
361 return seq_printf(seq,
362 "periodic_IRQ\t: %s\n"
364 // "square_wave\t: %s\n"
367 "periodic_freq\t: %d\n"
368 "batt_status\t: %s\n",
369 (rtc_control & RTC_PIE) ? "yes" : "no",
370 (rtc_control & RTC_UIE) ? "yes" : "no",
371 // (rtc_control & RTC_SQWE) ? "yes" : "no",
372 // (rtc_control & RTC_DM_BINARY) ? "no" : "yes",
373 (rtc_control & RTC_DST_EN) ? "yes" : "no",
375 (valid & RTC_VRT) ? "okay" : "dead");
379 #define cmos_procfs NULL
382 static const struct rtc_class_ops cmos_rtc_ops = {
383 .ioctl = cmos_rtc_ioctl,
384 .read_time = cmos_read_time,
385 .set_time = cmos_set_time,
386 .read_alarm = cmos_read_alarm,
387 .set_alarm = cmos_set_alarm,
389 .irq_set_freq = cmos_irq_set_freq,
390 .irq_set_state = cmos_irq_set_state,
393 /*----------------------------------------------------------------*/
395 static struct cmos_rtc cmos_rtc;
397 static irqreturn_t cmos_interrupt(int irq, void *p)
401 spin_lock(&rtc_lock);
402 irqstat = CMOS_READ(RTC_INTR_FLAGS);
403 irqstat &= (CMOS_READ(RTC_CONTROL) & RTC_IRQMASK) | RTC_IRQF;
404 spin_unlock(&rtc_lock);
406 if (is_intr(irqstat)) {
407 rtc_update_irq(p, 1, irqstat);
419 #define INITSECTION __init
422 static int INITSECTION
423 cmos_do_probe(struct device *dev, struct resource *ports, int rtc_irq)
425 struct cmos_rtc_board_info *info = dev->platform_data;
427 unsigned char rtc_control;
429 /* there can be only one ... */
436 cmos_rtc.irq = rtc_irq;
437 cmos_rtc.iomem = ports;
439 /* For ACPI systems extension info comes from the FADT. On others,
440 * board specific setup provides it as appropriate. Systems where
441 * the alarm IRQ isn't automatically a wakeup IRQ (like ACPI, and
442 * some almost-clones) can provide hooks to make that behave.
445 cmos_rtc.day_alrm = info->rtc_day_alarm;
446 cmos_rtc.mon_alrm = info->rtc_mon_alarm;
447 cmos_rtc.century = info->rtc_century;
449 if (info->wake_on && info->wake_off) {
450 cmos_rtc.wake_on = info->wake_on;
451 cmos_rtc.wake_off = info->wake_off;
455 cmos_rtc.rtc = rtc_device_register(driver_name, dev,
456 &cmos_rtc_ops, THIS_MODULE);
457 if (IS_ERR(cmos_rtc.rtc))
458 return PTR_ERR(cmos_rtc.rtc);
461 dev_set_drvdata(dev, &cmos_rtc);
463 /* platform and pnp busses handle resources incompatibly.
465 * REVISIT for non-x86 systems we may need to handle io memory
466 * resources: ioremap them, and request_mem_region().
469 retval = request_resource(&ioport_resource, ports);
471 dev_dbg(dev, "i/o registers already in use\n");
475 rename_region(ports, cmos_rtc.rtc->dev.bus_id);
477 spin_lock_irq(&rtc_lock);
479 /* force periodic irq to CMOS reset default of 1024Hz;
481 * REVISIT it's been reported that at least one x86_64 ALI mobo
482 * doesn't use 32KHz here ... for portability we might need to
483 * do something about other clock frequencies.
485 CMOS_WRITE(RTC_REF_CLCK_32KHZ | 0x06, RTC_FREQ_SELECT);
486 cmos_rtc.rtc->irq_freq = 1024;
490 * NOTE after changing RTC_xIE bits we always read INTR_FLAGS;
491 * allegedly some older rtcs need that to handle irqs properly
493 rtc_control = CMOS_READ(RTC_CONTROL);
494 rtc_control &= ~(RTC_PIE | RTC_AIE | RTC_UIE);
495 CMOS_WRITE(rtc_control, RTC_CONTROL);
496 CMOS_READ(RTC_INTR_FLAGS);
498 spin_unlock_irq(&rtc_lock);
500 /* FIXME teach the alarm code how to handle binary mode;
501 * <asm-generic/rtc.h> doesn't know 12-hour mode either.
503 if (!(rtc_control & RTC_24H) || (rtc_control & (RTC_DM_BINARY))) {
504 dev_dbg(dev, "only 24-hr BCD mode supported\n");
509 if (is_valid_irq(rtc_irq))
510 retval = request_irq(rtc_irq, cmos_interrupt, IRQF_DISABLED,
511 cmos_rtc.rtc->dev.bus_id,
514 dev_dbg(dev, "IRQ %d is already in use\n", rtc_irq);
518 /* REVISIT optionally make 50 or 114 bytes NVRAM available,
519 * like rtc-ds1553, rtc-ds1742 ... this will often include
520 * registers for century, and day/month alarm.
523 pr_info("%s: alarms up to one %s%s\n",
524 cmos_rtc.rtc->dev.bus_id,
525 is_valid_irq(rtc_irq)
531 cmos_rtc.century ? ", y3k" : ""
537 rename_region(ports, NULL);
539 rtc_device_unregister(cmos_rtc.rtc);
543 static void cmos_do_shutdown(void)
545 unsigned char rtc_control;
547 spin_lock_irq(&rtc_lock);
548 rtc_control = CMOS_READ(RTC_CONTROL);
549 rtc_control &= ~(RTC_PIE|RTC_AIE|RTC_UIE);
550 CMOS_WRITE(rtc_control, RTC_CONTROL);
551 CMOS_READ(RTC_INTR_FLAGS);
552 spin_unlock_irq(&rtc_lock);
555 static void __exit cmos_do_remove(struct device *dev)
557 struct cmos_rtc *cmos = dev_get_drvdata(dev);
562 release_resource(cmos->iomem);
563 rename_region(cmos->iomem, NULL);
565 if (is_valid_irq(cmos->irq))
566 free_irq(cmos->irq, cmos_rtc.rtc);
568 rtc_device_unregister(cmos_rtc.rtc);
571 dev_set_drvdata(dev, NULL);
576 static int cmos_suspend(struct device *dev, pm_message_t mesg)
578 struct cmos_rtc *cmos = dev_get_drvdata(dev);
579 int do_wake = device_may_wakeup(dev);
582 /* only the alarm might be a wakeup event source */
583 spin_lock_irq(&rtc_lock);
584 cmos->suspend_ctrl = tmp = CMOS_READ(RTC_CONTROL);
585 if (tmp & (RTC_PIE|RTC_AIE|RTC_UIE)) {
586 unsigned char irqstat;
589 tmp &= ~(RTC_PIE|RTC_UIE);
591 tmp &= ~(RTC_PIE|RTC_AIE|RTC_UIE);
592 CMOS_WRITE(tmp, RTC_CONTROL);
593 irqstat = CMOS_READ(RTC_INTR_FLAGS);
594 irqstat &= (tmp & RTC_IRQMASK) | RTC_IRQF;
595 if (is_intr(irqstat))
596 rtc_update_irq(cmos->rtc, 1, irqstat);
598 spin_unlock_irq(&rtc_lock);
601 cmos->enabled_wake = 1;
605 enable_irq_wake(cmos->irq);
608 pr_debug("%s: suspend%s, ctrl %02x\n",
609 cmos_rtc.rtc->dev.bus_id,
610 (tmp & RTC_AIE) ? ", alarm may wake" : "",
616 static int cmos_resume(struct device *dev)
618 struct cmos_rtc *cmos = dev_get_drvdata(dev);
619 unsigned char tmp = cmos->suspend_ctrl;
621 /* re-enable any irqs previously active */
622 if (tmp & (RTC_PIE|RTC_AIE|RTC_UIE)) {
624 if (cmos->enabled_wake) {
628 disable_irq_wake(cmos->irq);
629 cmos->enabled_wake = 0;
632 spin_lock_irq(&rtc_lock);
633 CMOS_WRITE(tmp, RTC_CONTROL);
634 tmp = CMOS_READ(RTC_INTR_FLAGS);
635 tmp &= (cmos->suspend_ctrl & RTC_IRQMASK) | RTC_IRQF;
637 rtc_update_irq(cmos->rtc, 1, tmp);
638 spin_unlock_irq(&rtc_lock);
641 pr_debug("%s: resume, ctrl %02x\n",
642 cmos_rtc.rtc->dev.bus_id,
650 #define cmos_suspend NULL
651 #define cmos_resume NULL
654 /*----------------------------------------------------------------*/
656 /* The "CMOS" RTC normally lives on the platform_bus. On ACPI systems,
657 * the device node will always be created as a PNPACPI device.
662 #include <linux/pnp.h>
665 cmos_pnp_probe(struct pnp_dev *pnp, const struct pnp_device_id *id)
667 /* REVISIT paranoia argues for a shutdown notifier, since PNP
668 * drivers can't provide shutdown() methods to disable IRQs.
669 * Or better yet, fix PNP to allow those methods...
671 if (pnp_port_start(pnp,0) == 0x70 && !pnp_irq_valid(pnp,0))
672 /* Some machines contain a PNP entry for the RTC, but
673 * don't define the IRQ. It should always be safe to
674 * hardcode it in these cases
676 return cmos_do_probe(&pnp->dev, &pnp->res.port_resource[0], 8);
678 return cmos_do_probe(&pnp->dev,
679 &pnp->res.port_resource[0],
680 pnp->res.irq_resource[0].start);
683 static void __exit cmos_pnp_remove(struct pnp_dev *pnp)
685 cmos_do_remove(&pnp->dev);
690 static int cmos_pnp_suspend(struct pnp_dev *pnp, pm_message_t mesg)
692 return cmos_suspend(&pnp->dev, mesg);
695 static int cmos_pnp_resume(struct pnp_dev *pnp)
697 return cmos_resume(&pnp->dev);
701 #define cmos_pnp_suspend NULL
702 #define cmos_pnp_resume NULL
706 static const struct pnp_device_id rtc_ids[] = {
707 { .id = "PNP0b00", },
708 { .id = "PNP0b01", },
709 { .id = "PNP0b02", },
712 MODULE_DEVICE_TABLE(pnp, rtc_ids);
714 static struct pnp_driver cmos_pnp_driver = {
715 .name = (char *) driver_name,
717 .probe = cmos_pnp_probe,
718 .remove = __exit_p(cmos_pnp_remove),
720 /* flag ensures resume() gets called, and stops syslog spam */
721 .flags = PNP_DRIVER_RES_DO_NOT_CHANGE,
722 .suspend = cmos_pnp_suspend,
723 .resume = cmos_pnp_resume,
726 static int __init cmos_init(void)
728 return pnp_register_driver(&cmos_pnp_driver);
730 module_init(cmos_init);
732 static void __exit cmos_exit(void)
734 pnp_unregister_driver(&cmos_pnp_driver);
736 module_exit(cmos_exit);
740 /*----------------------------------------------------------------*/
742 /* Platform setup should have set up an RTC device, when PNP is
743 * unavailable ... this could happen even on (older) PCs.
746 static int __init cmos_platform_probe(struct platform_device *pdev)
748 return cmos_do_probe(&pdev->dev,
749 platform_get_resource(pdev, IORESOURCE_IO, 0),
750 platform_get_irq(pdev, 0));
753 static int __exit cmos_platform_remove(struct platform_device *pdev)
755 cmos_do_remove(&pdev->dev);
759 static void cmos_platform_shutdown(struct platform_device *pdev)
764 static struct platform_driver cmos_platform_driver = {
765 .remove = __exit_p(cmos_platform_remove),
766 .shutdown = cmos_platform_shutdown,
768 .name = (char *) driver_name,
769 .suspend = cmos_suspend,
770 .resume = cmos_resume,
774 static int __init cmos_init(void)
776 return platform_driver_probe(&cmos_platform_driver,
777 cmos_platform_probe);
779 module_init(cmos_init);
781 static void __exit cmos_exit(void)
783 platform_driver_unregister(&cmos_platform_driver);
785 module_exit(cmos_exit);
790 MODULE_AUTHOR("David Brownell");
791 MODULE_DESCRIPTION("Driver for PC-style 'CMOS' RTCs");
792 MODULE_LICENSE("GPL");