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Linux/drivers/rtc/rtc-cmos.c

  1 /*
  2  * RTC class driver for "CMOS RTC":  PCs, ACPI, etc
  3  *
  4  * Copyright (C) 1996 Paul Gortmaker (drivers/char/rtc.c)
  5  * Copyright (C) 2006 David Brownell (convert to new framework)
  6  *
  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.
 11  */
 12 
 13 /*
 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.
 20  *
 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).
 26  *
 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.
 30  */
 31 
 32 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
 33 
 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 
 45 /* this is for "generic access to PC-style RTC" using CMOS_READ/CMOS_WRITE */
 46 #include <linux/mc146818rtc.h>
 47 
 48 struct cmos_rtc {
 49         struct rtc_device       *rtc;
 50         struct device           *dev;
 51         int                     irq;
 52         struct resource         *iomem;
 53         time64_t                alarm_expires;
 54 
 55         void                    (*wake_on)(struct device *);
 56         void                    (*wake_off)(struct device *);
 57 
 58         u8                      enabled_wake;
 59         u8                      suspend_ctrl;
 60 
 61         /* newer hardware extends the original register set */
 62         u8                      day_alrm;
 63         u8                      mon_alrm;
 64         u8                      century;
 65 };
 66 
 67 /* both platform and pnp busses use negative numbers for invalid irqs */
 68 #define is_valid_irq(n)         ((n) > 0)
 69 
 70 static const char driver_name[] = "rtc_cmos";
 71 
 72 /* The RTC_INTR register may have e.g. RTC_PF set even if RTC_PIE is clear;
 73  * always mask it against the irq enable bits in RTC_CONTROL.  Bit values
 74  * are the same: PF==PIE, AF=AIE, UF=UIE; so RTC_IRQMASK works with both.
 75  */
 76 #define RTC_IRQMASK     (RTC_PF | RTC_AF | RTC_UF)
 77 
 78 static inline int is_intr(u8 rtc_intr)
 79 {
 80         if (!(rtc_intr & RTC_IRQF))
 81                 return 0;
 82         return rtc_intr & RTC_IRQMASK;
 83 }
 84 
 85 /*----------------------------------------------------------------*/
 86 
 87 /* Much modern x86 hardware has HPETs (10+ MHz timers) which, because
 88  * many BIOS programmers don't set up "sane mode" IRQ routing, are mostly
 89  * used in a broken "legacy replacement" mode.  The breakage includes
 90  * HPET #1 hijacking the IRQ for this RTC, and being unavailable for
 91  * other (better) use.
 92  *
 93  * When that broken mode is in use, platform glue provides a partial
 94  * emulation of hardware RTC IRQ facilities using HPET #1.  We don't
 95  * want to use HPET for anything except those IRQs though...
 96  */
 97 #ifdef CONFIG_HPET_EMULATE_RTC
 98 #include <asm/hpet.h>
 99 #else
100 
101 static inline int is_hpet_enabled(void)
102 {
103         return 0;
104 }
105 
106 static inline int hpet_mask_rtc_irq_bit(unsigned long mask)
107 {
108         return 0;
109 }
110 
111 static inline int hpet_set_rtc_irq_bit(unsigned long mask)
112 {
113         return 0;
114 }
115 
116 static inline int
117 hpet_set_alarm_time(unsigned char hrs, unsigned char min, unsigned char sec)
118 {
119         return 0;
120 }
121 
122 static inline int hpet_set_periodic_freq(unsigned long freq)
123 {
124         return 0;
125 }
126 
127 static inline int hpet_rtc_dropped_irq(void)
128 {
129         return 0;
130 }
131 
132 static inline int hpet_rtc_timer_init(void)
133 {
134         return 0;
135 }
136 
137 extern irq_handler_t hpet_rtc_interrupt;
138 
139 static inline int hpet_register_irq_handler(irq_handler_t handler)
140 {
141         return 0;
142 }
143 
144 static inline int hpet_unregister_irq_handler(irq_handler_t handler)
145 {
146         return 0;
147 }
148 
149 #endif
150 
151 /*----------------------------------------------------------------*/
152 
153 #ifdef RTC_PORT
154 
155 /* Most newer x86 systems have two register banks, the first used
156  * for RTC and NVRAM and the second only for NVRAM.  Caller must
157  * own rtc_lock ... and we won't worry about access during NMI.
158  */
159 #define can_bank2       true
160 
161 static inline unsigned char cmos_read_bank2(unsigned char addr)
162 {
163         outb(addr, RTC_PORT(2));
164         return inb(RTC_PORT(3));
165 }
166 
167 static inline void cmos_write_bank2(unsigned char val, unsigned char addr)
168 {
169         outb(addr, RTC_PORT(2));
170         outb(val, RTC_PORT(3));
171 }
172 
173 #else
174 
175 #define can_bank2       false
176 
177 static inline unsigned char cmos_read_bank2(unsigned char addr)
178 {
179         return 0;
180 }
181 
182 static inline void cmos_write_bank2(unsigned char val, unsigned char addr)
183 {
184 }
185 
186 #endif
187 
188 /*----------------------------------------------------------------*/
189 
190 static int cmos_read_time(struct device *dev, struct rtc_time *t)
191 {
192         /* REVISIT:  if the clock has a "century" register, use
193          * that instead of the heuristic in mc146818_get_time().
194          * That'll make Y3K compatility (year > 2070) easy!
195          */
196         mc146818_get_time(t);
197         return 0;
198 }
199 
200 static int cmos_set_time(struct device *dev, struct rtc_time *t)
201 {
202         /* REVISIT:  set the "century" register if available
203          *
204          * NOTE: this ignores the issue whereby updating the seconds
205          * takes effect exactly 500ms after we write the register.
206          * (Also queueing and other delays before we get this far.)
207          */
208         return mc146818_set_time(t);
209 }
210 
211 static int cmos_read_alarm(struct device *dev, struct rtc_wkalrm *t)
212 {
213         struct cmos_rtc *cmos = dev_get_drvdata(dev);
214         unsigned char   rtc_control;
215 
216         if (!is_valid_irq(cmos->irq))
217                 return -EIO;
218 
219         /* Basic alarms only support hour, minute, and seconds fields.
220          * Some also support day and month, for alarms up to a year in
221          * the future.
222          */
223 
224         spin_lock_irq(&rtc_lock);
225         t->time.tm_sec = CMOS_READ(RTC_SECONDS_ALARM);
226         t->time.tm_min = CMOS_READ(RTC_MINUTES_ALARM);
227         t->time.tm_hour = CMOS_READ(RTC_HOURS_ALARM);
228 
229         if (cmos->day_alrm) {
230                 /* ignore upper bits on readback per ACPI spec */
231                 t->time.tm_mday = CMOS_READ(cmos->day_alrm) & 0x3f;
232                 if (!t->time.tm_mday)
233                         t->time.tm_mday = -1;
234 
235                 if (cmos->mon_alrm) {
236                         t->time.tm_mon = CMOS_READ(cmos->mon_alrm);
237                         if (!t->time.tm_mon)
238                                 t->time.tm_mon = -1;
239                 }
240         }
241 
242         rtc_control = CMOS_READ(RTC_CONTROL);
243         spin_unlock_irq(&rtc_lock);
244 
245         if (!(rtc_control & RTC_DM_BINARY) || RTC_ALWAYS_BCD) {
246                 if (((unsigned)t->time.tm_sec) < 0x60)
247                         t->time.tm_sec = bcd2bin(t->time.tm_sec);
248                 else
249                         t->time.tm_sec = -1;
250                 if (((unsigned)t->time.tm_min) < 0x60)
251                         t->time.tm_min = bcd2bin(t->time.tm_min);
252                 else
253                         t->time.tm_min = -1;
254                 if (((unsigned)t->time.tm_hour) < 0x24)
255                         t->time.tm_hour = bcd2bin(t->time.tm_hour);
256                 else
257                         t->time.tm_hour = -1;
258 
259                 if (cmos->day_alrm) {
260                         if (((unsigned)t->time.tm_mday) <= 0x31)
261                                 t->time.tm_mday = bcd2bin(t->time.tm_mday);
262                         else
263                                 t->time.tm_mday = -1;
264 
265                         if (cmos->mon_alrm) {
266                                 if (((unsigned)t->time.tm_mon) <= 0x12)
267                                         t->time.tm_mon = bcd2bin(t->time.tm_mon)-1;
268                                 else
269                                         t->time.tm_mon = -1;
270                         }
271                 }
272         }
273 
274         t->enabled = !!(rtc_control & RTC_AIE);
275         t->pending = 0;
276 
277         return 0;
278 }
279 
280 static void cmos_checkintr(struct cmos_rtc *cmos, unsigned char rtc_control)
281 {
282         unsigned char   rtc_intr;
283 
284         /* NOTE after changing RTC_xIE bits we always read INTR_FLAGS;
285          * allegedly some older rtcs need that to handle irqs properly
286          */
287         rtc_intr = CMOS_READ(RTC_INTR_FLAGS);
288 
289         if (is_hpet_enabled())
290                 return;
291 
292         rtc_intr &= (rtc_control & RTC_IRQMASK) | RTC_IRQF;
293         if (is_intr(rtc_intr))
294                 rtc_update_irq(cmos->rtc, 1, rtc_intr);
295 }
296 
297 static void cmos_irq_enable(struct cmos_rtc *cmos, unsigned char mask)
298 {
299         unsigned char   rtc_control;
300 
301         /* flush any pending IRQ status, notably for update irqs,
302          * before we enable new IRQs
303          */
304         rtc_control = CMOS_READ(RTC_CONTROL);
305         cmos_checkintr(cmos, rtc_control);
306 
307         rtc_control |= mask;
308         CMOS_WRITE(rtc_control, RTC_CONTROL);
309         hpet_set_rtc_irq_bit(mask);
310 
311         cmos_checkintr(cmos, rtc_control);
312 }
313 
314 static void cmos_irq_disable(struct cmos_rtc *cmos, unsigned char mask)
315 {
316         unsigned char   rtc_control;
317 
318         rtc_control = CMOS_READ(RTC_CONTROL);
319         rtc_control &= ~mask;
320         CMOS_WRITE(rtc_control, RTC_CONTROL);
321         hpet_mask_rtc_irq_bit(mask);
322 
323         cmos_checkintr(cmos, rtc_control);
324 }
325 
326 static int cmos_set_alarm(struct device *dev, struct rtc_wkalrm *t)
327 {
328         struct cmos_rtc *cmos = dev_get_drvdata(dev);
329         unsigned char mon, mday, hrs, min, sec, rtc_control;
330 
331         if (!is_valid_irq(cmos->irq))
332                 return -EIO;
333 
334         mon = t->time.tm_mon + 1;
335         mday = t->time.tm_mday;
336         hrs = t->time.tm_hour;
337         min = t->time.tm_min;
338         sec = t->time.tm_sec;
339 
340         rtc_control = CMOS_READ(RTC_CONTROL);
341         if (!(rtc_control & RTC_DM_BINARY) || RTC_ALWAYS_BCD) {
342                 /* Writing 0xff means "don't care" or "match all".  */
343                 mon = (mon <= 12) ? bin2bcd(mon) : 0xff;
344                 mday = (mday >= 1 && mday <= 31) ? bin2bcd(mday) : 0xff;
345                 hrs = (hrs < 24) ? bin2bcd(hrs) : 0xff;
346                 min = (min < 60) ? bin2bcd(min) : 0xff;
347                 sec = (sec < 60) ? bin2bcd(sec) : 0xff;
348         }
349 
350         spin_lock_irq(&rtc_lock);
351 
352         /* next rtc irq must not be from previous alarm setting */
353         cmos_irq_disable(cmos, RTC_AIE);
354 
355         /* update alarm */
356         CMOS_WRITE(hrs, RTC_HOURS_ALARM);
357         CMOS_WRITE(min, RTC_MINUTES_ALARM);
358         CMOS_WRITE(sec, RTC_SECONDS_ALARM);
359 
360         /* the system may support an "enhanced" alarm */
361         if (cmos->day_alrm) {
362                 CMOS_WRITE(mday, cmos->day_alrm);
363                 if (cmos->mon_alrm)
364                         CMOS_WRITE(mon, cmos->mon_alrm);
365         }
366 
367         /* FIXME the HPET alarm glue currently ignores day_alrm
368          * and mon_alrm ...
369          */
370         hpet_set_alarm_time(t->time.tm_hour, t->time.tm_min, t->time.tm_sec);
371 
372         if (t->enabled)
373                 cmos_irq_enable(cmos, RTC_AIE);
374 
375         spin_unlock_irq(&rtc_lock);
376 
377         cmos->alarm_expires = rtc_tm_to_time64(&t->time);
378 
379         return 0;
380 }
381 
382 static int cmos_alarm_irq_enable(struct device *dev, unsigned int enabled)
383 {
384         struct cmos_rtc *cmos = dev_get_drvdata(dev);
385         unsigned long   flags;
386 
387         if (!is_valid_irq(cmos->irq))
388                 return -EINVAL;
389 
390         spin_lock_irqsave(&rtc_lock, flags);
391 
392         if (enabled)
393                 cmos_irq_enable(cmos, RTC_AIE);
394         else
395                 cmos_irq_disable(cmos, RTC_AIE);
396 
397         spin_unlock_irqrestore(&rtc_lock, flags);
398         return 0;
399 }
400 
401 #if IS_ENABLED(CONFIG_RTC_INTF_PROC)
402 
403 static int cmos_procfs(struct device *dev, struct seq_file *seq)
404 {
405         struct cmos_rtc *cmos = dev_get_drvdata(dev);
406         unsigned char   rtc_control, valid;
407 
408         spin_lock_irq(&rtc_lock);
409         rtc_control = CMOS_READ(RTC_CONTROL);
410         valid = CMOS_READ(RTC_VALID);
411         spin_unlock_irq(&rtc_lock);
412 
413         /* NOTE:  at least ICH6 reports battery status using a different
414          * (non-RTC) bit; and SQWE is ignored on many current systems.
415          */
416         seq_printf(seq,
417                    "periodic_IRQ\t: %s\n"
418                    "update_IRQ\t: %s\n"
419                    "HPET_emulated\t: %s\n"
420                    // "square_wave\t: %s\n"
421                    "BCD\t\t: %s\n"
422                    "DST_enable\t: %s\n"
423                    "periodic_freq\t: %d\n"
424                    "batt_status\t: %s\n",
425                    (rtc_control & RTC_PIE) ? "yes" : "no",
426                    (rtc_control & RTC_UIE) ? "yes" : "no",
427                    is_hpet_enabled() ? "yes" : "no",
428                    // (rtc_control & RTC_SQWE) ? "yes" : "no",
429                    (rtc_control & RTC_DM_BINARY) ? "no" : "yes",
430                    (rtc_control & RTC_DST_EN) ? "yes" : "no",
431                    cmos->rtc->irq_freq,
432                    (valid & RTC_VRT) ? "okay" : "dead");
433 
434         return 0;
435 }
436 
437 #else
438 #define cmos_procfs     NULL
439 #endif
440 
441 static const struct rtc_class_ops cmos_rtc_ops = {
442         .read_time              = cmos_read_time,
443         .set_time               = cmos_set_time,
444         .read_alarm             = cmos_read_alarm,
445         .set_alarm              = cmos_set_alarm,
446         .proc                   = cmos_procfs,
447         .alarm_irq_enable       = cmos_alarm_irq_enable,
448 };
449 
450 /*----------------------------------------------------------------*/
451 
452 /*
453  * All these chips have at least 64 bytes of address space, shared by
454  * RTC registers and NVRAM.  Most of those bytes of NVRAM are used
455  * by boot firmware.  Modern chips have 128 or 256 bytes.
456  */
457 
458 #define NVRAM_OFFSET    (RTC_REG_D + 1)
459 
460 static ssize_t
461 cmos_nvram_read(struct file *filp, struct kobject *kobj,
462                 struct bin_attribute *attr,
463                 char *buf, loff_t off, size_t count)
464 {
465         int     retval;
466 
467         off += NVRAM_OFFSET;
468         spin_lock_irq(&rtc_lock);
469         for (retval = 0; count; count--, off++, retval++) {
470                 if (off < 128)
471                         *buf++ = CMOS_READ(off);
472                 else if (can_bank2)
473                         *buf++ = cmos_read_bank2(off);
474                 else
475                         break;
476         }
477         spin_unlock_irq(&rtc_lock);
478 
479         return retval;
480 }
481 
482 static ssize_t
483 cmos_nvram_write(struct file *filp, struct kobject *kobj,
484                 struct bin_attribute *attr,
485                 char *buf, loff_t off, size_t count)
486 {
487         struct cmos_rtc *cmos;
488         int             retval;
489 
490         cmos = dev_get_drvdata(container_of(kobj, struct device, kobj));
491 
492         /* NOTE:  on at least PCs and Ataris, the boot firmware uses a
493          * checksum on part of the NVRAM data.  That's currently ignored
494          * here.  If userspace is smart enough to know what fields of
495          * NVRAM to update, updating checksums is also part of its job.
496          */
497         off += NVRAM_OFFSET;
498         spin_lock_irq(&rtc_lock);
499         for (retval = 0; count; count--, off++, retval++) {
500                 /* don't trash RTC registers */
501                 if (off == cmos->day_alrm
502                                 || off == cmos->mon_alrm
503                                 || off == cmos->century)
504                         buf++;
505                 else if (off < 128)
506                         CMOS_WRITE(*buf++, off);
507                 else if (can_bank2)
508                         cmos_write_bank2(*buf++, off);
509                 else
510                         break;
511         }
512         spin_unlock_irq(&rtc_lock);
513 
514         return retval;
515 }
516 
517 static struct bin_attribute nvram = {
518         .attr = {
519                 .name   = "nvram",
520                 .mode   = S_IRUGO | S_IWUSR,
521         },
522 
523         .read   = cmos_nvram_read,
524         .write  = cmos_nvram_write,
525         /* size gets set up later */
526 };
527 
528 /*----------------------------------------------------------------*/
529 
530 static struct cmos_rtc  cmos_rtc;
531 
532 static irqreturn_t cmos_interrupt(int irq, void *p)
533 {
534         u8              irqstat;
535         u8              rtc_control;
536 
537         spin_lock(&rtc_lock);
538 
539         /* When the HPET interrupt handler calls us, the interrupt
540          * status is passed as arg1 instead of the irq number.  But
541          * always clear irq status, even when HPET is in the way.
542          *
543          * Note that HPET and RTC are almost certainly out of phase,
544          * giving different IRQ status ...
545          */
546         irqstat = CMOS_READ(RTC_INTR_FLAGS);
547         rtc_control = CMOS_READ(RTC_CONTROL);
548         if (is_hpet_enabled())
549                 irqstat = (unsigned long)irq & 0xF0;
550 
551         /* If we were suspended, RTC_CONTROL may not be accurate since the
552          * bios may have cleared it.
553          */
554         if (!cmos_rtc.suspend_ctrl)
555                 irqstat &= (rtc_control & RTC_IRQMASK) | RTC_IRQF;
556         else
557                 irqstat &= (cmos_rtc.suspend_ctrl & RTC_IRQMASK) | RTC_IRQF;
558 
559         /* All Linux RTC alarms should be treated as if they were oneshot.
560          * Similar code may be needed in system wakeup paths, in case the
561          * alarm woke the system.
562          */
563         if (irqstat & RTC_AIE) {
564                 cmos_rtc.suspend_ctrl &= ~RTC_AIE;
565                 rtc_control &= ~RTC_AIE;
566                 CMOS_WRITE(rtc_control, RTC_CONTROL);
567                 hpet_mask_rtc_irq_bit(RTC_AIE);
568                 CMOS_READ(RTC_INTR_FLAGS);
569         }
570         spin_unlock(&rtc_lock);
571 
572         if (is_intr(irqstat)) {
573                 rtc_update_irq(p, 1, irqstat);
574                 return IRQ_HANDLED;
575         } else
576                 return IRQ_NONE;
577 }
578 
579 #ifdef  CONFIG_PNP
580 #define INITSECTION
581 
582 #else
583 #define INITSECTION     __init
584 #endif
585 
586 static int INITSECTION
587 cmos_do_probe(struct device *dev, struct resource *ports, int rtc_irq)
588 {
589         struct cmos_rtc_board_info      *info = dev_get_platdata(dev);
590         int                             retval = 0;
591         unsigned char                   rtc_control;
592         unsigned                        address_space;
593         u32                             flags = 0;
594 
595         /* there can be only one ... */
596         if (cmos_rtc.dev)
597                 return -EBUSY;
598 
599         if (!ports)
600                 return -ENODEV;
601 
602         /* Claim I/O ports ASAP, minimizing conflict with legacy driver.
603          *
604          * REVISIT non-x86 systems may instead use memory space resources
605          * (needing ioremap etc), not i/o space resources like this ...
606          */
607         if (RTC_IOMAPPED)
608                 ports = request_region(ports->start, resource_size(ports),
609                                        driver_name);
610         else
611                 ports = request_mem_region(ports->start, resource_size(ports),
612                                            driver_name);
613         if (!ports) {
614                 dev_dbg(dev, "i/o registers already in use\n");
615                 return -EBUSY;
616         }
617 
618         cmos_rtc.irq = rtc_irq;
619         cmos_rtc.iomem = ports;
620 
621         /* Heuristic to deduce NVRAM size ... do what the legacy NVRAM
622          * driver did, but don't reject unknown configs.   Old hardware
623          * won't address 128 bytes.  Newer chips have multiple banks,
624          * though they may not be listed in one I/O resource.
625          */
626 #if     defined(CONFIG_ATARI)
627         address_space = 64;
628 #elif defined(__i386__) || defined(__x86_64__) || defined(__arm__) \
629                         || defined(__sparc__) || defined(__mips__) \
630                         || defined(__powerpc__) || defined(CONFIG_MN10300)
631         address_space = 128;
632 #else
633 #warning Assuming 128 bytes of RTC+NVRAM address space, not 64 bytes.
634         address_space = 128;
635 #endif
636         if (can_bank2 && ports->end > (ports->start + 1))
637                 address_space = 256;
638 
639         /* For ACPI systems extension info comes from the FADT.  On others,
640          * board specific setup provides it as appropriate.  Systems where
641          * the alarm IRQ isn't automatically a wakeup IRQ (like ACPI, and
642          * some almost-clones) can provide hooks to make that behave.
643          *
644          * Note that ACPI doesn't preclude putting these registers into
645          * "extended" areas of the chip, including some that we won't yet
646          * expect CMOS_READ and friends to handle.
647          */
648         if (info) {
649                 if (info->flags)
650                         flags = info->flags;
651                 if (info->address_space)
652                         address_space = info->address_space;
653 
654                 if (info->rtc_day_alarm && info->rtc_day_alarm < 128)
655                         cmos_rtc.day_alrm = info->rtc_day_alarm;
656                 if (info->rtc_mon_alarm && info->rtc_mon_alarm < 128)
657                         cmos_rtc.mon_alrm = info->rtc_mon_alarm;
658                 if (info->rtc_century && info->rtc_century < 128)
659                         cmos_rtc.century = info->rtc_century;
660 
661                 if (info->wake_on && info->wake_off) {
662                         cmos_rtc.wake_on = info->wake_on;
663                         cmos_rtc.wake_off = info->wake_off;
664                 }
665         }
666 
667         cmos_rtc.dev = dev;
668         dev_set_drvdata(dev, &cmos_rtc);
669 
670         cmos_rtc.rtc = rtc_device_register(driver_name, dev,
671                                 &cmos_rtc_ops, THIS_MODULE);
672         if (IS_ERR(cmos_rtc.rtc)) {
673                 retval = PTR_ERR(cmos_rtc.rtc);
674                 goto cleanup0;
675         }
676 
677         rename_region(ports, dev_name(&cmos_rtc.rtc->dev));
678 
679         spin_lock_irq(&rtc_lock);
680 
681         if (!(flags & CMOS_RTC_FLAGS_NOFREQ)) {
682                 /* force periodic irq to CMOS reset default of 1024Hz;
683                  *
684                  * REVISIT it's been reported that at least one x86_64 ALI
685                  * mobo doesn't use 32KHz here ... for portability we might
686                  * need to do something about other clock frequencies.
687                  */
688                 cmos_rtc.rtc->irq_freq = 1024;
689                 hpet_set_periodic_freq(cmos_rtc.rtc->irq_freq);
690                 CMOS_WRITE(RTC_REF_CLCK_32KHZ | 0x06, RTC_FREQ_SELECT);
691         }
692 
693         /* disable irqs */
694         if (is_valid_irq(rtc_irq))
695                 cmos_irq_disable(&cmos_rtc, RTC_PIE | RTC_AIE | RTC_UIE);
696 
697         rtc_control = CMOS_READ(RTC_CONTROL);
698 
699         spin_unlock_irq(&rtc_lock);
700 
701         /* FIXME:
702          * <asm-generic/rtc.h> doesn't know 12-hour mode either.
703          */
704         if (is_valid_irq(rtc_irq) && !(rtc_control & RTC_24H)) {
705                 dev_warn(dev, "only 24-hr supported\n");
706                 retval = -ENXIO;
707                 goto cleanup1;
708         }
709 
710         if (is_valid_irq(rtc_irq)) {
711                 irq_handler_t rtc_cmos_int_handler;
712 
713                 if (is_hpet_enabled()) {
714                         rtc_cmos_int_handler = hpet_rtc_interrupt;
715                         retval = hpet_register_irq_handler(cmos_interrupt);
716                         if (retval) {
717                                 dev_warn(dev, "hpet_register_irq_handler "
718                                                 " failed in rtc_init().");
719                                 goto cleanup1;
720                         }
721                 } else
722                         rtc_cmos_int_handler = cmos_interrupt;
723 
724                 retval = request_irq(rtc_irq, rtc_cmos_int_handler,
725                                 IRQF_SHARED, dev_name(&cmos_rtc.rtc->dev),
726                                 cmos_rtc.rtc);
727                 if (retval < 0) {
728                         dev_dbg(dev, "IRQ %d is already in use\n", rtc_irq);
729                         goto cleanup1;
730                 }
731         }
732         hpet_rtc_timer_init();
733 
734         /* export at least the first block of NVRAM */
735         nvram.size = address_space - NVRAM_OFFSET;
736         retval = sysfs_create_bin_file(&dev->kobj, &nvram);
737         if (retval < 0) {
738                 dev_dbg(dev, "can't create nvram file? %d\n", retval);
739                 goto cleanup2;
740         }
741 
742         dev_info(dev, "%s%s, %zd bytes nvram%s\n",
743                 !is_valid_irq(rtc_irq) ? "no alarms" :
744                         cmos_rtc.mon_alrm ? "alarms up to one year" :
745                         cmos_rtc.day_alrm ? "alarms up to one month" :
746                         "alarms up to one day",
747                 cmos_rtc.century ? ", y3k" : "",
748                 nvram.size,
749                 is_hpet_enabled() ? ", hpet irqs" : "");
750 
751         return 0;
752 
753 cleanup2:
754         if (is_valid_irq(rtc_irq))
755                 free_irq(rtc_irq, cmos_rtc.rtc);
756 cleanup1:
757         cmos_rtc.dev = NULL;
758         rtc_device_unregister(cmos_rtc.rtc);
759 cleanup0:
760         if (RTC_IOMAPPED)
761                 release_region(ports->start, resource_size(ports));
762         else
763                 release_mem_region(ports->start, resource_size(ports));
764         return retval;
765 }
766 
767 static void cmos_do_shutdown(int rtc_irq)
768 {
769         spin_lock_irq(&rtc_lock);
770         if (is_valid_irq(rtc_irq))
771                 cmos_irq_disable(&cmos_rtc, RTC_IRQMASK);
772         spin_unlock_irq(&rtc_lock);
773 }
774 
775 static void __exit cmos_do_remove(struct device *dev)
776 {
777         struct cmos_rtc *cmos = dev_get_drvdata(dev);
778         struct resource *ports;
779 
780         cmos_do_shutdown(cmos->irq);
781 
782         sysfs_remove_bin_file(&dev->kobj, &nvram);
783 
784         if (is_valid_irq(cmos->irq)) {
785                 free_irq(cmos->irq, cmos->rtc);
786                 hpet_unregister_irq_handler(cmos_interrupt);
787         }
788 
789         rtc_device_unregister(cmos->rtc);
790         cmos->rtc = NULL;
791 
792         ports = cmos->iomem;
793         if (RTC_IOMAPPED)
794                 release_region(ports->start, resource_size(ports));
795         else
796                 release_mem_region(ports->start, resource_size(ports));
797         cmos->iomem = NULL;
798 
799         cmos->dev = NULL;
800 }
801 
802 static int cmos_aie_poweroff(struct device *dev)
803 {
804         struct cmos_rtc *cmos = dev_get_drvdata(dev);
805         struct rtc_time now;
806         time64_t t_now;
807         int retval = 0;
808         unsigned char rtc_control;
809 
810         if (!cmos->alarm_expires)
811                 return -EINVAL;
812 
813         spin_lock_irq(&rtc_lock);
814         rtc_control = CMOS_READ(RTC_CONTROL);
815         spin_unlock_irq(&rtc_lock);
816 
817         /* We only care about the situation where AIE is disabled. */
818         if (rtc_control & RTC_AIE)
819                 return -EBUSY;
820 
821         cmos_read_time(dev, &now);
822         t_now = rtc_tm_to_time64(&now);
823 
824         /*
825          * When enabling "RTC wake-up" in BIOS setup, the machine reboots
826          * automatically right after shutdown on some buggy boxes.
827          * This automatic rebooting issue won't happen when the alarm
828          * time is larger than now+1 seconds.
829          *
830          * If the alarm time is equal to now+1 seconds, the issue can be
831          * prevented by cancelling the alarm.
832          */
833         if (cmos->alarm_expires == t_now + 1) {
834                 struct rtc_wkalrm alarm;
835 
836                 /* Cancel the AIE timer by configuring the past time. */
837                 rtc_time64_to_tm(t_now - 1, &alarm.time);
838                 alarm.enabled = 0;
839                 retval = cmos_set_alarm(dev, &alarm);
840         } else if (cmos->alarm_expires > t_now + 1) {
841                 retval = -EBUSY;
842         }
843 
844         return retval;
845 }
846 
847 #ifdef CONFIG_PM
848 
849 static int cmos_suspend(struct device *dev)
850 {
851         struct cmos_rtc *cmos = dev_get_drvdata(dev);
852         unsigned char   tmp;
853 
854         /* only the alarm might be a wakeup event source */
855         spin_lock_irq(&rtc_lock);
856         cmos->suspend_ctrl = tmp = CMOS_READ(RTC_CONTROL);
857         if (tmp & (RTC_PIE|RTC_AIE|RTC_UIE)) {
858                 unsigned char   mask;
859 
860                 if (device_may_wakeup(dev))
861                         mask = RTC_IRQMASK & ~RTC_AIE;
862                 else
863                         mask = RTC_IRQMASK;
864                 tmp &= ~mask;
865                 CMOS_WRITE(tmp, RTC_CONTROL);
866                 hpet_mask_rtc_irq_bit(mask);
867 
868                 cmos_checkintr(cmos, tmp);
869         }
870         spin_unlock_irq(&rtc_lock);
871 
872         if (tmp & RTC_AIE) {
873                 cmos->enabled_wake = 1;
874                 if (cmos->wake_on)
875                         cmos->wake_on(dev);
876                 else
877                         enable_irq_wake(cmos->irq);
878         }
879 
880         dev_dbg(dev, "suspend%s, ctrl %02x\n",
881                         (tmp & RTC_AIE) ? ", alarm may wake" : "",
882                         tmp);
883 
884         return 0;
885 }
886 
887 /* We want RTC alarms to wake us from e.g. ACPI G2/S5 "soft off", even
888  * after a detour through G3 "mechanical off", although the ACPI spec
889  * says wakeup should only work from G1/S4 "hibernate".  To most users,
890  * distinctions between S4 and S5 are pointless.  So when the hardware
891  * allows, don't draw that distinction.
892  */
893 static inline int cmos_poweroff(struct device *dev)
894 {
895         return cmos_suspend(dev);
896 }
897 
898 #ifdef  CONFIG_PM_SLEEP
899 
900 static int cmos_resume(struct device *dev)
901 {
902         struct cmos_rtc *cmos = dev_get_drvdata(dev);
903         unsigned char tmp;
904 
905         if (cmos->enabled_wake) {
906                 if (cmos->wake_off)
907                         cmos->wake_off(dev);
908                 else
909                         disable_irq_wake(cmos->irq);
910                 cmos->enabled_wake = 0;
911         }
912 
913         spin_lock_irq(&rtc_lock);
914         tmp = cmos->suspend_ctrl;
915         cmos->suspend_ctrl = 0;
916         /* re-enable any irqs previously active */
917         if (tmp & RTC_IRQMASK) {
918                 unsigned char   mask;
919 
920                 if (device_may_wakeup(dev))
921                         hpet_rtc_timer_init();
922 
923                 do {
924                         CMOS_WRITE(tmp, RTC_CONTROL);
925                         hpet_set_rtc_irq_bit(tmp & RTC_IRQMASK);
926 
927                         mask = CMOS_READ(RTC_INTR_FLAGS);
928                         mask &= (tmp & RTC_IRQMASK) | RTC_IRQF;
929                         if (!is_hpet_enabled() || !is_intr(mask))
930                                 break;
931 
932                         /* force one-shot behavior if HPET blocked
933                          * the wake alarm's irq
934                          */
935                         rtc_update_irq(cmos->rtc, 1, mask);
936                         tmp &= ~RTC_AIE;
937                         hpet_mask_rtc_irq_bit(RTC_AIE);
938                 } while (mask & RTC_AIE);
939         }
940         spin_unlock_irq(&rtc_lock);
941 
942         dev_dbg(dev, "resume, ctrl %02x\n", tmp);
943 
944         return 0;
945 }
946 
947 #endif
948 #else
949 
950 static inline int cmos_poweroff(struct device *dev)
951 {
952         return -ENOSYS;
953 }
954 
955 #endif
956 
957 static SIMPLE_DEV_PM_OPS(cmos_pm_ops, cmos_suspend, cmos_resume);
958 
959 /*----------------------------------------------------------------*/
960 
961 /* On non-x86 systems, a "CMOS" RTC lives most naturally on platform_bus.
962  * ACPI systems always list these as PNPACPI devices, and pre-ACPI PCs
963  * probably list them in similar PNPBIOS tables; so PNP is more common.
964  *
965  * We don't use legacy "poke at the hardware" probing.  Ancient PCs that
966  * predate even PNPBIOS should set up platform_bus devices.
967  */
968 
969 #ifdef  CONFIG_ACPI
970 
971 #include <linux/acpi.h>
972 
973 static u32 rtc_handler(void *context)
974 {
975         struct device *dev = context;
976 
977         pm_wakeup_event(dev, 0);
978         acpi_clear_event(ACPI_EVENT_RTC);
979         acpi_disable_event(ACPI_EVENT_RTC, 0);
980         return ACPI_INTERRUPT_HANDLED;
981 }
982 
983 static inline void rtc_wake_setup(struct device *dev)
984 {
985         acpi_install_fixed_event_handler(ACPI_EVENT_RTC, rtc_handler, dev);
986         /*
987          * After the RTC handler is installed, the Fixed_RTC event should
988          * be disabled. Only when the RTC alarm is set will it be enabled.
989          */
990         acpi_clear_event(ACPI_EVENT_RTC);
991         acpi_disable_event(ACPI_EVENT_RTC, 0);
992 }
993 
994 static void rtc_wake_on(struct device *dev)
995 {
996         acpi_clear_event(ACPI_EVENT_RTC);
997         acpi_enable_event(ACPI_EVENT_RTC, 0);
998 }
999 
1000 static void rtc_wake_off(struct device *dev)
1001 {
1002         acpi_disable_event(ACPI_EVENT_RTC, 0);
1003 }
1004 
1005 /* Every ACPI platform has a mc146818 compatible "cmos rtc".  Here we find
1006  * its device node and pass extra config data.  This helps its driver use
1007  * capabilities that the now-obsolete mc146818 didn't have, and informs it
1008  * that this board's RTC is wakeup-capable (per ACPI spec).
1009  */
1010 static struct cmos_rtc_board_info acpi_rtc_info;
1011 
1012 static void cmos_wake_setup(struct device *dev)
1013 {
1014         if (acpi_disabled)
1015                 return;
1016 
1017         rtc_wake_setup(dev);
1018         acpi_rtc_info.wake_on = rtc_wake_on;
1019         acpi_rtc_info.wake_off = rtc_wake_off;
1020 
1021         /* workaround bug in some ACPI tables */
1022         if (acpi_gbl_FADT.month_alarm && !acpi_gbl_FADT.day_alarm) {
1023                 dev_dbg(dev, "bogus FADT month_alarm (%d)\n",
1024                         acpi_gbl_FADT.month_alarm);
1025                 acpi_gbl_FADT.month_alarm = 0;
1026         }
1027 
1028         acpi_rtc_info.rtc_day_alarm = acpi_gbl_FADT.day_alarm;
1029         acpi_rtc_info.rtc_mon_alarm = acpi_gbl_FADT.month_alarm;
1030         acpi_rtc_info.rtc_century = acpi_gbl_FADT.century;
1031 
1032         /* NOTE:  S4_RTC_WAKE is NOT currently useful to Linux */
1033         if (acpi_gbl_FADT.flags & ACPI_FADT_S4_RTC_WAKE)
1034                 dev_info(dev, "RTC can wake from S4\n");
1035 
1036         dev->platform_data = &acpi_rtc_info;
1037 
1038         /* RTC always wakes from S1/S2/S3, and often S4/STD */
1039         device_init_wakeup(dev, 1);
1040 }
1041 
1042 #else
1043 
1044 static void cmos_wake_setup(struct device *dev)
1045 {
1046 }
1047 
1048 #endif
1049 
1050 #ifdef  CONFIG_PNP
1051 
1052 #include <linux/pnp.h>
1053 
1054 static int cmos_pnp_probe(struct pnp_dev *pnp, const struct pnp_device_id *id)
1055 {
1056         cmos_wake_setup(&pnp->dev);
1057 
1058         if (pnp_port_start(pnp, 0) == 0x70 && !pnp_irq_valid(pnp, 0))
1059                 /* Some machines contain a PNP entry for the RTC, but
1060                  * don't define the IRQ. It should always be safe to
1061                  * hardcode it in these cases
1062                  */
1063                 return cmos_do_probe(&pnp->dev,
1064                                 pnp_get_resource(pnp, IORESOURCE_IO, 0), 8);
1065         else
1066                 return cmos_do_probe(&pnp->dev,
1067                                 pnp_get_resource(pnp, IORESOURCE_IO, 0),
1068                                 pnp_irq(pnp, 0));
1069 }
1070 
1071 static void __exit cmos_pnp_remove(struct pnp_dev *pnp)
1072 {
1073         cmos_do_remove(&pnp->dev);
1074 }
1075 
1076 static void cmos_pnp_shutdown(struct pnp_dev *pnp)
1077 {
1078         struct device *dev = &pnp->dev;
1079         struct cmos_rtc *cmos = dev_get_drvdata(dev);
1080 
1081         if (system_state == SYSTEM_POWER_OFF) {
1082                 int retval = cmos_poweroff(dev);
1083 
1084                 if (cmos_aie_poweroff(dev) < 0 && !retval)
1085                         return;
1086         }
1087 
1088         cmos_do_shutdown(cmos->irq);
1089 }
1090 
1091 static const struct pnp_device_id rtc_ids[] = {
1092         { .id = "PNP0b00", },
1093         { .id = "PNP0b01", },
1094         { .id = "PNP0b02", },
1095         { },
1096 };
1097 MODULE_DEVICE_TABLE(pnp, rtc_ids);
1098 
1099 static struct pnp_driver cmos_pnp_driver = {
1100         .name           = (char *) driver_name,
1101         .id_table       = rtc_ids,
1102         .probe          = cmos_pnp_probe,
1103         .remove         = __exit_p(cmos_pnp_remove),
1104         .shutdown       = cmos_pnp_shutdown,
1105 
1106         /* flag ensures resume() gets called, and stops syslog spam */
1107         .flags          = PNP_DRIVER_RES_DO_NOT_CHANGE,
1108         .driver         = {
1109                         .pm = &cmos_pm_ops,
1110         },
1111 };
1112 
1113 #endif  /* CONFIG_PNP */
1114 
1115 #ifdef CONFIG_OF
1116 static const struct of_device_id of_cmos_match[] = {
1117         {
1118                 .compatible = "motorola,mc146818",
1119         },
1120         { },
1121 };
1122 MODULE_DEVICE_TABLE(of, of_cmos_match);
1123 
1124 static __init void cmos_of_init(struct platform_device *pdev)
1125 {
1126         struct device_node *node = pdev->dev.of_node;
1127         struct rtc_time time;
1128         int ret;
1129         const __be32 *val;
1130 
1131         if (!node)
1132                 return;
1133 
1134         val = of_get_property(node, "ctrl-reg", NULL);
1135         if (val)
1136                 CMOS_WRITE(be32_to_cpup(val), RTC_CONTROL);
1137 
1138         val = of_get_property(node, "freq-reg", NULL);
1139         if (val)
1140                 CMOS_WRITE(be32_to_cpup(val), RTC_FREQ_SELECT);
1141 
1142         cmos_read_time(&pdev->dev, &time);
1143         ret = rtc_valid_tm(&time);
1144         if (ret) {
1145                 struct rtc_time def_time = {
1146                         .tm_year = 1,
1147                         .tm_mday = 1,
1148                 };
1149                 cmos_set_time(&pdev->dev, &def_time);
1150         }
1151 }
1152 #else
1153 static inline void cmos_of_init(struct platform_device *pdev) {}
1154 #endif
1155 /*----------------------------------------------------------------*/
1156 
1157 /* Platform setup should have set up an RTC device, when PNP is
1158  * unavailable ... this could happen even on (older) PCs.
1159  */
1160 
1161 static int __init cmos_platform_probe(struct platform_device *pdev)
1162 {
1163         struct resource *resource;
1164         int irq;
1165 
1166         cmos_of_init(pdev);
1167         cmos_wake_setup(&pdev->dev);
1168 
1169         if (RTC_IOMAPPED)
1170                 resource = platform_get_resource(pdev, IORESOURCE_IO, 0);
1171         else
1172                 resource = platform_get_resource(pdev, IORESOURCE_MEM, 0);
1173         irq = platform_get_irq(pdev, 0);
1174         if (irq < 0)
1175                 irq = -1;
1176 
1177         return cmos_do_probe(&pdev->dev, resource, irq);
1178 }
1179 
1180 static int __exit cmos_platform_remove(struct platform_device *pdev)
1181 {
1182         cmos_do_remove(&pdev->dev);
1183         return 0;
1184 }
1185 
1186 static void cmos_platform_shutdown(struct platform_device *pdev)
1187 {
1188         struct device *dev = &pdev->dev;
1189         struct cmos_rtc *cmos = dev_get_drvdata(dev);
1190 
1191         if (system_state == SYSTEM_POWER_OFF) {
1192                 int retval = cmos_poweroff(dev);
1193 
1194                 if (cmos_aie_poweroff(dev) < 0 && !retval)
1195                         return;
1196         }
1197 
1198         cmos_do_shutdown(cmos->irq);
1199 }
1200 
1201 /* work with hotplug and coldplug */
1202 MODULE_ALIAS("platform:rtc_cmos");
1203 
1204 static struct platform_driver cmos_platform_driver = {
1205         .remove         = __exit_p(cmos_platform_remove),
1206         .shutdown       = cmos_platform_shutdown,
1207         .driver = {
1208                 .name           = driver_name,
1209 #ifdef CONFIG_PM
1210                 .pm             = &cmos_pm_ops,
1211 #endif
1212                 .of_match_table = of_match_ptr(of_cmos_match),
1213         }
1214 };
1215 
1216 #ifdef CONFIG_PNP
1217 static bool pnp_driver_registered;
1218 #endif
1219 static bool platform_driver_registered;
1220 
1221 static int __init cmos_init(void)
1222 {
1223         int retval = 0;
1224 
1225 #ifdef  CONFIG_PNP
1226         retval = pnp_register_driver(&cmos_pnp_driver);
1227         if (retval == 0)
1228                 pnp_driver_registered = true;
1229 #endif
1230 
1231         if (!cmos_rtc.dev) {
1232                 retval = platform_driver_probe(&cmos_platform_driver,
1233                                                cmos_platform_probe);
1234                 if (retval == 0)
1235                         platform_driver_registered = true;
1236         }
1237 
1238         if (retval == 0)
1239                 return 0;
1240 
1241 #ifdef  CONFIG_PNP
1242         if (pnp_driver_registered)
1243                 pnp_unregister_driver(&cmos_pnp_driver);
1244 #endif
1245         return retval;
1246 }
1247 module_init(cmos_init);
1248 
1249 static void __exit cmos_exit(void)
1250 {
1251 #ifdef  CONFIG_PNP
1252         if (pnp_driver_registered)
1253                 pnp_unregister_driver(&cmos_pnp_driver);
1254 #endif
1255         if (platform_driver_registered)
1256                 platform_driver_unregister(&cmos_platform_driver);
1257 }
1258 module_exit(cmos_exit);
1259 
1260 
1261 MODULE_AUTHOR("David Brownell");
1262 MODULE_DESCRIPTION("Driver for PC-style 'CMOS' RTCs");
1263 MODULE_LICENSE("GPL");
1264 

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