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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         struct rtc_wkalrm       saved_wkalrm;
 67 };
 68 
 69 /* both platform and pnp busses use negative numbers for invalid irqs */
 70 #define is_valid_irq(n)         ((n) > 0)
 71 
 72 static const char driver_name[] = "rtc_cmos";
 73 
 74 /* The RTC_INTR register may have e.g. RTC_PF set even if RTC_PIE is clear;
 75  * always mask it against the irq enable bits in RTC_CONTROL.  Bit values
 76  * are the same: PF==PIE, AF=AIE, UF=UIE; so RTC_IRQMASK works with both.
 77  */
 78 #define RTC_IRQMASK     (RTC_PF | RTC_AF | RTC_UF)
 79 
 80 static inline int is_intr(u8 rtc_intr)
 81 {
 82         if (!(rtc_intr & RTC_IRQF))
 83                 return 0;
 84         return rtc_intr & RTC_IRQMASK;
 85 }
 86 
 87 /*----------------------------------------------------------------*/
 88 
 89 /* Much modern x86 hardware has HPETs (10+ MHz timers) which, because
 90  * many BIOS programmers don't set up "sane mode" IRQ routing, are mostly
 91  * used in a broken "legacy replacement" mode.  The breakage includes
 92  * HPET #1 hijacking the IRQ for this RTC, and being unavailable for
 93  * other (better) use.
 94  *
 95  * When that broken mode is in use, platform glue provides a partial
 96  * emulation of hardware RTC IRQ facilities using HPET #1.  We don't
 97  * want to use HPET for anything except those IRQs though...
 98  */
 99 #ifdef CONFIG_HPET_EMULATE_RTC
100 #include <asm/hpet.h>
101 #else
102 
103 static inline int is_hpet_enabled(void)
104 {
105         return 0;
106 }
107 
108 static inline int hpet_mask_rtc_irq_bit(unsigned long mask)
109 {
110         return 0;
111 }
112 
113 static inline int hpet_set_rtc_irq_bit(unsigned long mask)
114 {
115         return 0;
116 }
117 
118 static inline int
119 hpet_set_alarm_time(unsigned char hrs, unsigned char min, unsigned char sec)
120 {
121         return 0;
122 }
123 
124 static inline int hpet_set_periodic_freq(unsigned long freq)
125 {
126         return 0;
127 }
128 
129 static inline int hpet_rtc_dropped_irq(void)
130 {
131         return 0;
132 }
133 
134 static inline int hpet_rtc_timer_init(void)
135 {
136         return 0;
137 }
138 
139 extern irq_handler_t hpet_rtc_interrupt;
140 
141 static inline int hpet_register_irq_handler(irq_handler_t handler)
142 {
143         return 0;
144 }
145 
146 static inline int hpet_unregister_irq_handler(irq_handler_t handler)
147 {
148         return 0;
149 }
150 
151 #endif
152 
153 /*----------------------------------------------------------------*/
154 
155 #ifdef RTC_PORT
156 
157 /* Most newer x86 systems have two register banks, the first used
158  * for RTC and NVRAM and the second only for NVRAM.  Caller must
159  * own rtc_lock ... and we won't worry about access during NMI.
160  */
161 #define can_bank2       true
162 
163 static inline unsigned char cmos_read_bank2(unsigned char addr)
164 {
165         outb(addr, RTC_PORT(2));
166         return inb(RTC_PORT(3));
167 }
168 
169 static inline void cmos_write_bank2(unsigned char val, unsigned char addr)
170 {
171         outb(addr, RTC_PORT(2));
172         outb(val, RTC_PORT(3));
173 }
174 
175 #else
176 
177 #define can_bank2       false
178 
179 static inline unsigned char cmos_read_bank2(unsigned char addr)
180 {
181         return 0;
182 }
183 
184 static inline void cmos_write_bank2(unsigned char val, unsigned char addr)
185 {
186 }
187 
188 #endif
189 
190 /*----------------------------------------------------------------*/
191 
192 static int cmos_read_time(struct device *dev, struct rtc_time *t)
193 {
194         /* REVISIT:  if the clock has a "century" register, use
195          * that instead of the heuristic in mc146818_get_time().
196          * That'll make Y3K compatility (year > 2070) easy!
197          */
198         mc146818_get_time(t);
199         return 0;
200 }
201 
202 static int cmos_set_time(struct device *dev, struct rtc_time *t)
203 {
204         /* REVISIT:  set the "century" register if available
205          *
206          * NOTE: this ignores the issue whereby updating the seconds
207          * takes effect exactly 500ms after we write the register.
208          * (Also queueing and other delays before we get this far.)
209          */
210         return mc146818_set_time(t);
211 }
212 
213 static int cmos_read_alarm(struct device *dev, struct rtc_wkalrm *t)
214 {
215         struct cmos_rtc *cmos = dev_get_drvdata(dev);
216         unsigned char   rtc_control;
217 
218         if (!is_valid_irq(cmos->irq))
219                 return -EIO;
220 
221         /* Basic alarms only support hour, minute, and seconds fields.
222          * Some also support day and month, for alarms up to a year in
223          * the future.
224          */
225 
226         spin_lock_irq(&rtc_lock);
227         t->time.tm_sec = CMOS_READ(RTC_SECONDS_ALARM);
228         t->time.tm_min = CMOS_READ(RTC_MINUTES_ALARM);
229         t->time.tm_hour = CMOS_READ(RTC_HOURS_ALARM);
230 
231         if (cmos->day_alrm) {
232                 /* ignore upper bits on readback per ACPI spec */
233                 t->time.tm_mday = CMOS_READ(cmos->day_alrm) & 0x3f;
234                 if (!t->time.tm_mday)
235                         t->time.tm_mday = -1;
236 
237                 if (cmos->mon_alrm) {
238                         t->time.tm_mon = CMOS_READ(cmos->mon_alrm);
239                         if (!t->time.tm_mon)
240                                 t->time.tm_mon = -1;
241                 }
242         }
243 
244         rtc_control = CMOS_READ(RTC_CONTROL);
245         spin_unlock_irq(&rtc_lock);
246 
247         if (!(rtc_control & RTC_DM_BINARY) || RTC_ALWAYS_BCD) {
248                 if (((unsigned)t->time.tm_sec) < 0x60)
249                         t->time.tm_sec = bcd2bin(t->time.tm_sec);
250                 else
251                         t->time.tm_sec = -1;
252                 if (((unsigned)t->time.tm_min) < 0x60)
253                         t->time.tm_min = bcd2bin(t->time.tm_min);
254                 else
255                         t->time.tm_min = -1;
256                 if (((unsigned)t->time.tm_hour) < 0x24)
257                         t->time.tm_hour = bcd2bin(t->time.tm_hour);
258                 else
259                         t->time.tm_hour = -1;
260 
261                 if (cmos->day_alrm) {
262                         if (((unsigned)t->time.tm_mday) <= 0x31)
263                                 t->time.tm_mday = bcd2bin(t->time.tm_mday);
264                         else
265                                 t->time.tm_mday = -1;
266 
267                         if (cmos->mon_alrm) {
268                                 if (((unsigned)t->time.tm_mon) <= 0x12)
269                                         t->time.tm_mon = bcd2bin(t->time.tm_mon)-1;
270                                 else
271                                         t->time.tm_mon = -1;
272                         }
273                 }
274         }
275 
276         t->enabled = !!(rtc_control & RTC_AIE);
277         t->pending = 0;
278 
279         return 0;
280 }
281 
282 static void cmos_checkintr(struct cmos_rtc *cmos, unsigned char rtc_control)
283 {
284         unsigned char   rtc_intr;
285 
286         /* NOTE after changing RTC_xIE bits we always read INTR_FLAGS;
287          * allegedly some older rtcs need that to handle irqs properly
288          */
289         rtc_intr = CMOS_READ(RTC_INTR_FLAGS);
290 
291         if (is_hpet_enabled())
292                 return;
293 
294         rtc_intr &= (rtc_control & RTC_IRQMASK) | RTC_IRQF;
295         if (is_intr(rtc_intr))
296                 rtc_update_irq(cmos->rtc, 1, rtc_intr);
297 }
298 
299 static void cmos_irq_enable(struct cmos_rtc *cmos, unsigned char mask)
300 {
301         unsigned char   rtc_control;
302 
303         /* flush any pending IRQ status, notably for update irqs,
304          * before we enable new IRQs
305          */
306         rtc_control = CMOS_READ(RTC_CONTROL);
307         cmos_checkintr(cmos, rtc_control);
308 
309         rtc_control |= mask;
310         CMOS_WRITE(rtc_control, RTC_CONTROL);
311         hpet_set_rtc_irq_bit(mask);
312 
313         cmos_checkintr(cmos, rtc_control);
314 }
315 
316 static void cmos_irq_disable(struct cmos_rtc *cmos, unsigned char mask)
317 {
318         unsigned char   rtc_control;
319 
320         rtc_control = CMOS_READ(RTC_CONTROL);
321         rtc_control &= ~mask;
322         CMOS_WRITE(rtc_control, RTC_CONTROL);
323         hpet_mask_rtc_irq_bit(mask);
324 
325         cmos_checkintr(cmos, rtc_control);
326 }
327 
328 static int cmos_set_alarm(struct device *dev, struct rtc_wkalrm *t)
329 {
330         struct cmos_rtc *cmos = dev_get_drvdata(dev);
331         unsigned char mon, mday, hrs, min, sec, rtc_control;
332 
333         if (!is_valid_irq(cmos->irq))
334                 return -EIO;
335 
336         mon = t->time.tm_mon + 1;
337         mday = t->time.tm_mday;
338         hrs = t->time.tm_hour;
339         min = t->time.tm_min;
340         sec = t->time.tm_sec;
341 
342         rtc_control = CMOS_READ(RTC_CONTROL);
343         if (!(rtc_control & RTC_DM_BINARY) || RTC_ALWAYS_BCD) {
344                 /* Writing 0xff means "don't care" or "match all".  */
345                 mon = (mon <= 12) ? bin2bcd(mon) : 0xff;
346                 mday = (mday >= 1 && mday <= 31) ? bin2bcd(mday) : 0xff;
347                 hrs = (hrs < 24) ? bin2bcd(hrs) : 0xff;
348                 min = (min < 60) ? bin2bcd(min) : 0xff;
349                 sec = (sec < 60) ? bin2bcd(sec) : 0xff;
350         }
351 
352         spin_lock_irq(&rtc_lock);
353 
354         /* next rtc irq must not be from previous alarm setting */
355         cmos_irq_disable(cmos, RTC_AIE);
356 
357         /* update alarm */
358         CMOS_WRITE(hrs, RTC_HOURS_ALARM);
359         CMOS_WRITE(min, RTC_MINUTES_ALARM);
360         CMOS_WRITE(sec, RTC_SECONDS_ALARM);
361 
362         /* the system may support an "enhanced" alarm */
363         if (cmos->day_alrm) {
364                 CMOS_WRITE(mday, cmos->day_alrm);
365                 if (cmos->mon_alrm)
366                         CMOS_WRITE(mon, cmos->mon_alrm);
367         }
368 
369         /* FIXME the HPET alarm glue currently ignores day_alrm
370          * and mon_alrm ...
371          */
372         hpet_set_alarm_time(t->time.tm_hour, t->time.tm_min, t->time.tm_sec);
373 
374         if (t->enabled)
375                 cmos_irq_enable(cmos, RTC_AIE);
376 
377         spin_unlock_irq(&rtc_lock);
378 
379         cmos->alarm_expires = rtc_tm_to_time64(&t->time);
380 
381         return 0;
382 }
383 
384 static int cmos_alarm_irq_enable(struct device *dev, unsigned int enabled)
385 {
386         struct cmos_rtc *cmos = dev_get_drvdata(dev);
387         unsigned long   flags;
388 
389         if (!is_valid_irq(cmos->irq))
390                 return -EINVAL;
391 
392         spin_lock_irqsave(&rtc_lock, flags);
393 
394         if (enabled)
395                 cmos_irq_enable(cmos, RTC_AIE);
396         else
397                 cmos_irq_disable(cmos, RTC_AIE);
398 
399         spin_unlock_irqrestore(&rtc_lock, flags);
400         return 0;
401 }
402 
403 #if IS_ENABLED(CONFIG_RTC_INTF_PROC)
404 
405 static int cmos_procfs(struct device *dev, struct seq_file *seq)
406 {
407         struct cmos_rtc *cmos = dev_get_drvdata(dev);
408         unsigned char   rtc_control, valid;
409 
410         spin_lock_irq(&rtc_lock);
411         rtc_control = CMOS_READ(RTC_CONTROL);
412         valid = CMOS_READ(RTC_VALID);
413         spin_unlock_irq(&rtc_lock);
414 
415         /* NOTE:  at least ICH6 reports battery status using a different
416          * (non-RTC) bit; and SQWE is ignored on many current systems.
417          */
418         seq_printf(seq,
419                    "periodic_IRQ\t: %s\n"
420                    "update_IRQ\t: %s\n"
421                    "HPET_emulated\t: %s\n"
422                    // "square_wave\t: %s\n"
423                    "BCD\t\t: %s\n"
424                    "DST_enable\t: %s\n"
425                    "periodic_freq\t: %d\n"
426                    "batt_status\t: %s\n",
427                    (rtc_control & RTC_PIE) ? "yes" : "no",
428                    (rtc_control & RTC_UIE) ? "yes" : "no",
429                    is_hpet_enabled() ? "yes" : "no",
430                    // (rtc_control & RTC_SQWE) ? "yes" : "no",
431                    (rtc_control & RTC_DM_BINARY) ? "no" : "yes",
432                    (rtc_control & RTC_DST_EN) ? "yes" : "no",
433                    cmos->rtc->irq_freq,
434                    (valid & RTC_VRT) ? "okay" : "dead");
435 
436         return 0;
437 }
438 
439 #else
440 #define cmos_procfs     NULL
441 #endif
442 
443 static const struct rtc_class_ops cmos_rtc_ops = {
444         .read_time              = cmos_read_time,
445         .set_time               = cmos_set_time,
446         .read_alarm             = cmos_read_alarm,
447         .set_alarm              = cmos_set_alarm,
448         .proc                   = cmos_procfs,
449         .alarm_irq_enable       = cmos_alarm_irq_enable,
450 };
451 
452 /*----------------------------------------------------------------*/
453 
454 /*
455  * All these chips have at least 64 bytes of address space, shared by
456  * RTC registers and NVRAM.  Most of those bytes of NVRAM are used
457  * by boot firmware.  Modern chips have 128 or 256 bytes.
458  */
459 
460 #define NVRAM_OFFSET    (RTC_REG_D + 1)
461 
462 static ssize_t
463 cmos_nvram_read(struct file *filp, struct kobject *kobj,
464                 struct bin_attribute *attr,
465                 char *buf, loff_t off, size_t count)
466 {
467         int     retval;
468 
469         off += NVRAM_OFFSET;
470         spin_lock_irq(&rtc_lock);
471         for (retval = 0; count; count--, off++, retval++) {
472                 if (off < 128)
473                         *buf++ = CMOS_READ(off);
474                 else if (can_bank2)
475                         *buf++ = cmos_read_bank2(off);
476                 else
477                         break;
478         }
479         spin_unlock_irq(&rtc_lock);
480 
481         return retval;
482 }
483 
484 static ssize_t
485 cmos_nvram_write(struct file *filp, struct kobject *kobj,
486                 struct bin_attribute *attr,
487                 char *buf, loff_t off, size_t count)
488 {
489         struct cmos_rtc *cmos;
490         int             retval;
491 
492         cmos = dev_get_drvdata(container_of(kobj, struct device, kobj));
493 
494         /* NOTE:  on at least PCs and Ataris, the boot firmware uses a
495          * checksum on part of the NVRAM data.  That's currently ignored
496          * here.  If userspace is smart enough to know what fields of
497          * NVRAM to update, updating checksums is also part of its job.
498          */
499         off += NVRAM_OFFSET;
500         spin_lock_irq(&rtc_lock);
501         for (retval = 0; count; count--, off++, retval++) {
502                 /* don't trash RTC registers */
503                 if (off == cmos->day_alrm
504                                 || off == cmos->mon_alrm
505                                 || off == cmos->century)
506                         buf++;
507                 else if (off < 128)
508                         CMOS_WRITE(*buf++, off);
509                 else if (can_bank2)
510                         cmos_write_bank2(*buf++, off);
511                 else
512                         break;
513         }
514         spin_unlock_irq(&rtc_lock);
515 
516         return retval;
517 }
518 
519 static struct bin_attribute nvram = {
520         .attr = {
521                 .name   = "nvram",
522                 .mode   = S_IRUGO | S_IWUSR,
523         },
524 
525         .read   = cmos_nvram_read,
526         .write  = cmos_nvram_write,
527         /* size gets set up later */
528 };
529 
530 /*----------------------------------------------------------------*/
531 
532 static struct cmos_rtc  cmos_rtc;
533 
534 static irqreturn_t cmos_interrupt(int irq, void *p)
535 {
536         u8              irqstat;
537         u8              rtc_control;
538 
539         spin_lock(&rtc_lock);
540 
541         /* When the HPET interrupt handler calls us, the interrupt
542          * status is passed as arg1 instead of the irq number.  But
543          * always clear irq status, even when HPET is in the way.
544          *
545          * Note that HPET and RTC are almost certainly out of phase,
546          * giving different IRQ status ...
547          */
548         irqstat = CMOS_READ(RTC_INTR_FLAGS);
549         rtc_control = CMOS_READ(RTC_CONTROL);
550         if (is_hpet_enabled())
551                 irqstat = (unsigned long)irq & 0xF0;
552 
553         /* If we were suspended, RTC_CONTROL may not be accurate since the
554          * bios may have cleared it.
555          */
556         if (!cmos_rtc.suspend_ctrl)
557                 irqstat &= (rtc_control & RTC_IRQMASK) | RTC_IRQF;
558         else
559                 irqstat &= (cmos_rtc.suspend_ctrl & RTC_IRQMASK) | RTC_IRQF;
560 
561         /* All Linux RTC alarms should be treated as if they were oneshot.
562          * Similar code may be needed in system wakeup paths, in case the
563          * alarm woke the system.
564          */
565         if (irqstat & RTC_AIE) {
566                 cmos_rtc.suspend_ctrl &= ~RTC_AIE;
567                 rtc_control &= ~RTC_AIE;
568                 CMOS_WRITE(rtc_control, RTC_CONTROL);
569                 hpet_mask_rtc_irq_bit(RTC_AIE);
570                 CMOS_READ(RTC_INTR_FLAGS);
571         }
572         spin_unlock(&rtc_lock);
573 
574         if (is_intr(irqstat)) {
575                 rtc_update_irq(p, 1, irqstat);
576                 return IRQ_HANDLED;
577         } else
578                 return IRQ_NONE;
579 }
580 
581 #ifdef  CONFIG_PNP
582 #define INITSECTION
583 
584 #else
585 #define INITSECTION     __init
586 #endif
587 
588 static int INITSECTION
589 cmos_do_probe(struct device *dev, struct resource *ports, int rtc_irq)
590 {
591         struct cmos_rtc_board_info      *info = dev_get_platdata(dev);
592         int                             retval = 0;
593         unsigned char                   rtc_control;
594         unsigned                        address_space;
595         u32                             flags = 0;
596 
597         /* there can be only one ... */
598         if (cmos_rtc.dev)
599                 return -EBUSY;
600 
601         if (!ports)
602                 return -ENODEV;
603 
604         /* Claim I/O ports ASAP, minimizing conflict with legacy driver.
605          *
606          * REVISIT non-x86 systems may instead use memory space resources
607          * (needing ioremap etc), not i/o space resources like this ...
608          */
609         if (RTC_IOMAPPED)
610                 ports = request_region(ports->start, resource_size(ports),
611                                        driver_name);
612         else
613                 ports = request_mem_region(ports->start, resource_size(ports),
614                                            driver_name);
615         if (!ports) {
616                 dev_dbg(dev, "i/o registers already in use\n");
617                 return -EBUSY;
618         }
619 
620         cmos_rtc.irq = rtc_irq;
621         cmos_rtc.iomem = ports;
622 
623         /* Heuristic to deduce NVRAM size ... do what the legacy NVRAM
624          * driver did, but don't reject unknown configs.   Old hardware
625          * won't address 128 bytes.  Newer chips have multiple banks,
626          * though they may not be listed in one I/O resource.
627          */
628 #if     defined(CONFIG_ATARI)
629         address_space = 64;
630 #elif defined(__i386__) || defined(__x86_64__) || defined(__arm__) \
631                         || defined(__sparc__) || defined(__mips__) \
632                         || defined(__powerpc__) || defined(CONFIG_MN10300)
633         address_space = 128;
634 #else
635 #warning Assuming 128 bytes of RTC+NVRAM address space, not 64 bytes.
636         address_space = 128;
637 #endif
638         if (can_bank2 && ports->end > (ports->start + 1))
639                 address_space = 256;
640 
641         /* For ACPI systems extension info comes from the FADT.  On others,
642          * board specific setup provides it as appropriate.  Systems where
643          * the alarm IRQ isn't automatically a wakeup IRQ (like ACPI, and
644          * some almost-clones) can provide hooks to make that behave.
645          *
646          * Note that ACPI doesn't preclude putting these registers into
647          * "extended" areas of the chip, including some that we won't yet
648          * expect CMOS_READ and friends to handle.
649          */
650         if (info) {
651                 if (info->flags)
652                         flags = info->flags;
653                 if (info->address_space)
654                         address_space = info->address_space;
655 
656                 if (info->rtc_day_alarm && info->rtc_day_alarm < 128)
657                         cmos_rtc.day_alrm = info->rtc_day_alarm;
658                 if (info->rtc_mon_alarm && info->rtc_mon_alarm < 128)
659                         cmos_rtc.mon_alrm = info->rtc_mon_alarm;
660                 if (info->rtc_century && info->rtc_century < 128)
661                         cmos_rtc.century = info->rtc_century;
662 
663                 if (info->wake_on && info->wake_off) {
664                         cmos_rtc.wake_on = info->wake_on;
665                         cmos_rtc.wake_off = info->wake_off;
666                 }
667         }
668 
669         cmos_rtc.dev = dev;
670         dev_set_drvdata(dev, &cmos_rtc);
671 
672         cmos_rtc.rtc = rtc_device_register(driver_name, dev,
673                                 &cmos_rtc_ops, THIS_MODULE);
674         if (IS_ERR(cmos_rtc.rtc)) {
675                 retval = PTR_ERR(cmos_rtc.rtc);
676                 goto cleanup0;
677         }
678 
679         rename_region(ports, dev_name(&cmos_rtc.rtc->dev));
680 
681         spin_lock_irq(&rtc_lock);
682 
683         if (!(flags & CMOS_RTC_FLAGS_NOFREQ)) {
684                 /* force periodic irq to CMOS reset default of 1024Hz;
685                  *
686                  * REVISIT it's been reported that at least one x86_64 ALI
687                  * mobo doesn't use 32KHz here ... for portability we might
688                  * need to do something about other clock frequencies.
689                  */
690                 cmos_rtc.rtc->irq_freq = 1024;
691                 hpet_set_periodic_freq(cmos_rtc.rtc->irq_freq);
692                 CMOS_WRITE(RTC_REF_CLCK_32KHZ | 0x06, RTC_FREQ_SELECT);
693         }
694 
695         /* disable irqs */
696         if (is_valid_irq(rtc_irq))
697                 cmos_irq_disable(&cmos_rtc, RTC_PIE | RTC_AIE | RTC_UIE);
698 
699         rtc_control = CMOS_READ(RTC_CONTROL);
700 
701         spin_unlock_irq(&rtc_lock);
702 
703         /* FIXME:
704          * <asm-generic/rtc.h> doesn't know 12-hour mode either.
705          */
706         if (is_valid_irq(rtc_irq) && !(rtc_control & RTC_24H)) {
707                 dev_warn(dev, "only 24-hr supported\n");
708                 retval = -ENXIO;
709                 goto cleanup1;
710         }
711 
712         hpet_rtc_timer_init();
713 
714         if (is_valid_irq(rtc_irq)) {
715                 irq_handler_t rtc_cmos_int_handler;
716 
717                 if (is_hpet_enabled()) {
718                         rtc_cmos_int_handler = hpet_rtc_interrupt;
719                         retval = hpet_register_irq_handler(cmos_interrupt);
720                         if (retval) {
721                                 hpet_mask_rtc_irq_bit(RTC_IRQMASK);
722                                 dev_warn(dev, "hpet_register_irq_handler "
723                                                 " failed in rtc_init().");
724                                 goto cleanup1;
725                         }
726                 } else
727                         rtc_cmos_int_handler = cmos_interrupt;
728 
729                 retval = request_irq(rtc_irq, rtc_cmos_int_handler,
730                                 IRQF_SHARED, dev_name(&cmos_rtc.rtc->dev),
731                                 cmos_rtc.rtc);
732                 if (retval < 0) {
733                         dev_dbg(dev, "IRQ %d is already in use\n", rtc_irq);
734                         goto cleanup1;
735                 }
736         }
737 
738         /* export at least the first block of NVRAM */
739         nvram.size = address_space - NVRAM_OFFSET;
740         retval = sysfs_create_bin_file(&dev->kobj, &nvram);
741         if (retval < 0) {
742                 dev_dbg(dev, "can't create nvram file? %d\n", retval);
743                 goto cleanup2;
744         }
745 
746         dev_info(dev, "%s%s, %zd bytes nvram%s\n",
747                 !is_valid_irq(rtc_irq) ? "no alarms" :
748                         cmos_rtc.mon_alrm ? "alarms up to one year" :
749                         cmos_rtc.day_alrm ? "alarms up to one month" :
750                         "alarms up to one day",
751                 cmos_rtc.century ? ", y3k" : "",
752                 nvram.size,
753                 is_hpet_enabled() ? ", hpet irqs" : "");
754 
755         return 0;
756 
757 cleanup2:
758         if (is_valid_irq(rtc_irq))
759                 free_irq(rtc_irq, cmos_rtc.rtc);
760 cleanup1:
761         cmos_rtc.dev = NULL;
762         rtc_device_unregister(cmos_rtc.rtc);
763 cleanup0:
764         if (RTC_IOMAPPED)
765                 release_region(ports->start, resource_size(ports));
766         else
767                 release_mem_region(ports->start, resource_size(ports));
768         return retval;
769 }
770 
771 static void cmos_do_shutdown(int rtc_irq)
772 {
773         spin_lock_irq(&rtc_lock);
774         if (is_valid_irq(rtc_irq))
775                 cmos_irq_disable(&cmos_rtc, RTC_IRQMASK);
776         spin_unlock_irq(&rtc_lock);
777 }
778 
779 static void cmos_do_remove(struct device *dev)
780 {
781         struct cmos_rtc *cmos = dev_get_drvdata(dev);
782         struct resource *ports;
783 
784         cmos_do_shutdown(cmos->irq);
785 
786         sysfs_remove_bin_file(&dev->kobj, &nvram);
787 
788         if (is_valid_irq(cmos->irq)) {
789                 free_irq(cmos->irq, cmos->rtc);
790                 hpet_unregister_irq_handler(cmos_interrupt);
791         }
792 
793         rtc_device_unregister(cmos->rtc);
794         cmos->rtc = NULL;
795 
796         ports = cmos->iomem;
797         if (RTC_IOMAPPED)
798                 release_region(ports->start, resource_size(ports));
799         else
800                 release_mem_region(ports->start, resource_size(ports));
801         cmos->iomem = NULL;
802 
803         cmos->dev = NULL;
804 }
805 
806 static int cmos_aie_poweroff(struct device *dev)
807 {
808         struct cmos_rtc *cmos = dev_get_drvdata(dev);
809         struct rtc_time now;
810         time64_t t_now;
811         int retval = 0;
812         unsigned char rtc_control;
813 
814         if (!cmos->alarm_expires)
815                 return -EINVAL;
816 
817         spin_lock_irq(&rtc_lock);
818         rtc_control = CMOS_READ(RTC_CONTROL);
819         spin_unlock_irq(&rtc_lock);
820 
821         /* We only care about the situation where AIE is disabled. */
822         if (rtc_control & RTC_AIE)
823                 return -EBUSY;
824 
825         cmos_read_time(dev, &now);
826         t_now = rtc_tm_to_time64(&now);
827 
828         /*
829          * When enabling "RTC wake-up" in BIOS setup, the machine reboots
830          * automatically right after shutdown on some buggy boxes.
831          * This automatic rebooting issue won't happen when the alarm
832          * time is larger than now+1 seconds.
833          *
834          * If the alarm time is equal to now+1 seconds, the issue can be
835          * prevented by cancelling the alarm.
836          */
837         if (cmos->alarm_expires == t_now + 1) {
838                 struct rtc_wkalrm alarm;
839 
840                 /* Cancel the AIE timer by configuring the past time. */
841                 rtc_time64_to_tm(t_now - 1, &alarm.time);
842                 alarm.enabled = 0;
843                 retval = cmos_set_alarm(dev, &alarm);
844         } else if (cmos->alarm_expires > t_now + 1) {
845                 retval = -EBUSY;
846         }
847 
848         return retval;
849 }
850 
851 static int cmos_suspend(struct device *dev)
852 {
853         struct cmos_rtc *cmos = dev_get_drvdata(dev);
854         unsigned char   tmp;
855 
856         /* only the alarm might be a wakeup event source */
857         spin_lock_irq(&rtc_lock);
858         cmos->suspend_ctrl = tmp = CMOS_READ(RTC_CONTROL);
859         if (tmp & (RTC_PIE|RTC_AIE|RTC_UIE)) {
860                 unsigned char   mask;
861 
862                 if (device_may_wakeup(dev))
863                         mask = RTC_IRQMASK & ~RTC_AIE;
864                 else
865                         mask = RTC_IRQMASK;
866                 tmp &= ~mask;
867                 CMOS_WRITE(tmp, RTC_CONTROL);
868                 hpet_mask_rtc_irq_bit(mask);
869 
870                 cmos_checkintr(cmos, tmp);
871         }
872         spin_unlock_irq(&rtc_lock);
873 
874         if (tmp & RTC_AIE) {
875                 cmos->enabled_wake = 1;
876                 if (cmos->wake_on)
877                         cmos->wake_on(dev);
878                 else
879                         enable_irq_wake(cmos->irq);
880         }
881 
882         cmos_read_alarm(dev, &cmos->saved_wkalrm);
883 
884         dev_dbg(dev, "suspend%s, ctrl %02x\n",
885                         (tmp & RTC_AIE) ? ", alarm may wake" : "",
886                         tmp);
887 
888         return 0;
889 }
890 
891 /* We want RTC alarms to wake us from e.g. ACPI G2/S5 "soft off", even
892  * after a detour through G3 "mechanical off", although the ACPI spec
893  * says wakeup should only work from G1/S4 "hibernate".  To most users,
894  * distinctions between S4 and S5 are pointless.  So when the hardware
895  * allows, don't draw that distinction.
896  */
897 static inline int cmos_poweroff(struct device *dev)
898 {
899         if (!IS_ENABLED(CONFIG_PM))
900                 return -ENOSYS;
901 
902         return cmos_suspend(dev);
903 }
904 
905 static void cmos_check_wkalrm(struct device *dev)
906 {
907         struct cmos_rtc *cmos = dev_get_drvdata(dev);
908         struct rtc_wkalrm current_alarm;
909         time64_t t_current_expires;
910         time64_t t_saved_expires;
911 
912         cmos_read_alarm(dev, &current_alarm);
913         t_current_expires = rtc_tm_to_time64(&current_alarm.time);
914         t_saved_expires = rtc_tm_to_time64(&cmos->saved_wkalrm.time);
915         if (t_current_expires != t_saved_expires ||
916             cmos->saved_wkalrm.enabled != current_alarm.enabled) {
917                 cmos_set_alarm(dev, &cmos->saved_wkalrm);
918         }
919 }
920 
921 static void cmos_check_acpi_rtc_status(struct device *dev,
922                                        unsigned char *rtc_control);
923 
924 static int __maybe_unused cmos_resume(struct device *dev)
925 {
926         struct cmos_rtc *cmos = dev_get_drvdata(dev);
927         unsigned char tmp;
928 
929         if (cmos->enabled_wake) {
930                 if (cmos->wake_off)
931                         cmos->wake_off(dev);
932                 else
933                         disable_irq_wake(cmos->irq);
934                 cmos->enabled_wake = 0;
935         }
936 
937         /* The BIOS might have changed the alarm, restore it */
938         cmos_check_wkalrm(dev);
939 
940         spin_lock_irq(&rtc_lock);
941         tmp = cmos->suspend_ctrl;
942         cmos->suspend_ctrl = 0;
943         /* re-enable any irqs previously active */
944         if (tmp & RTC_IRQMASK) {
945                 unsigned char   mask;
946 
947                 if (device_may_wakeup(dev))
948                         hpet_rtc_timer_init();
949 
950                 do {
951                         CMOS_WRITE(tmp, RTC_CONTROL);
952                         hpet_set_rtc_irq_bit(tmp & RTC_IRQMASK);
953 
954                         mask = CMOS_READ(RTC_INTR_FLAGS);
955                         mask &= (tmp & RTC_IRQMASK) | RTC_IRQF;
956                         if (!is_hpet_enabled() || !is_intr(mask))
957                                 break;
958 
959                         /* force one-shot behavior if HPET blocked
960                          * the wake alarm's irq
961                          */
962                         rtc_update_irq(cmos->rtc, 1, mask);
963                         tmp &= ~RTC_AIE;
964                         hpet_mask_rtc_irq_bit(RTC_AIE);
965                 } while (mask & RTC_AIE);
966 
967                 if (tmp & RTC_AIE)
968                         cmos_check_acpi_rtc_status(dev, &tmp);
969         }
970         spin_unlock_irq(&rtc_lock);
971 
972         dev_dbg(dev, "resume, ctrl %02x\n", tmp);
973 
974         return 0;
975 }
976 
977 static SIMPLE_DEV_PM_OPS(cmos_pm_ops, cmos_suspend, cmos_resume);
978 
979 /*----------------------------------------------------------------*/
980 
981 /* On non-x86 systems, a "CMOS" RTC lives most naturally on platform_bus.
982  * ACPI systems always list these as PNPACPI devices, and pre-ACPI PCs
983  * probably list them in similar PNPBIOS tables; so PNP is more common.
984  *
985  * We don't use legacy "poke at the hardware" probing.  Ancient PCs that
986  * predate even PNPBIOS should set up platform_bus devices.
987  */
988 
989 #ifdef  CONFIG_ACPI
990 
991 #include <linux/acpi.h>
992 
993 static u32 rtc_handler(void *context)
994 {
995         struct device *dev = context;
996         struct cmos_rtc *cmos = dev_get_drvdata(dev);
997         unsigned char rtc_control = 0;
998         unsigned char rtc_intr;
999         unsigned long flags;
1000 
1001         spin_lock_irqsave(&rtc_lock, flags);
1002         if (cmos_rtc.suspend_ctrl)
1003                 rtc_control = CMOS_READ(RTC_CONTROL);
1004         if (rtc_control & RTC_AIE) {
1005                 cmos_rtc.suspend_ctrl &= ~RTC_AIE;
1006                 CMOS_WRITE(rtc_control, RTC_CONTROL);
1007                 rtc_intr = CMOS_READ(RTC_INTR_FLAGS);
1008                 rtc_update_irq(cmos->rtc, 1, rtc_intr);
1009         }
1010         spin_unlock_irqrestore(&rtc_lock, flags);
1011 
1012         pm_wakeup_event(dev, 0);
1013         acpi_clear_event(ACPI_EVENT_RTC);
1014         acpi_disable_event(ACPI_EVENT_RTC, 0);
1015         return ACPI_INTERRUPT_HANDLED;
1016 }
1017 
1018 static inline void rtc_wake_setup(struct device *dev)
1019 {
1020         acpi_install_fixed_event_handler(ACPI_EVENT_RTC, rtc_handler, dev);
1021         /*
1022          * After the RTC handler is installed, the Fixed_RTC event should
1023          * be disabled. Only when the RTC alarm is set will it be enabled.
1024          */
1025         acpi_clear_event(ACPI_EVENT_RTC);
1026         acpi_disable_event(ACPI_EVENT_RTC, 0);
1027 }
1028 
1029 static void rtc_wake_on(struct device *dev)
1030 {
1031         acpi_clear_event(ACPI_EVENT_RTC);
1032         acpi_enable_event(ACPI_EVENT_RTC, 0);
1033 }
1034 
1035 static void rtc_wake_off(struct device *dev)
1036 {
1037         acpi_disable_event(ACPI_EVENT_RTC, 0);
1038 }
1039 
1040 /* Every ACPI platform has a mc146818 compatible "cmos rtc".  Here we find
1041  * its device node and pass extra config data.  This helps its driver use
1042  * capabilities that the now-obsolete mc146818 didn't have, and informs it
1043  * that this board's RTC is wakeup-capable (per ACPI spec).
1044  */
1045 static struct cmos_rtc_board_info acpi_rtc_info;
1046 
1047 static void cmos_wake_setup(struct device *dev)
1048 {
1049         if (acpi_disabled)
1050                 return;
1051 
1052         rtc_wake_setup(dev);
1053         acpi_rtc_info.wake_on = rtc_wake_on;
1054         acpi_rtc_info.wake_off = rtc_wake_off;
1055 
1056         /* workaround bug in some ACPI tables */
1057         if (acpi_gbl_FADT.month_alarm && !acpi_gbl_FADT.day_alarm) {
1058                 dev_dbg(dev, "bogus FADT month_alarm (%d)\n",
1059                         acpi_gbl_FADT.month_alarm);
1060                 acpi_gbl_FADT.month_alarm = 0;
1061         }
1062 
1063         acpi_rtc_info.rtc_day_alarm = acpi_gbl_FADT.day_alarm;
1064         acpi_rtc_info.rtc_mon_alarm = acpi_gbl_FADT.month_alarm;
1065         acpi_rtc_info.rtc_century = acpi_gbl_FADT.century;
1066 
1067         /* NOTE:  S4_RTC_WAKE is NOT currently useful to Linux */
1068         if (acpi_gbl_FADT.flags & ACPI_FADT_S4_RTC_WAKE)
1069                 dev_info(dev, "RTC can wake from S4\n");
1070 
1071         dev->platform_data = &acpi_rtc_info;
1072 
1073         /* RTC always wakes from S1/S2/S3, and often S4/STD */
1074         device_init_wakeup(dev, 1);
1075 }
1076 
1077 static void cmos_check_acpi_rtc_status(struct device *dev,
1078                                        unsigned char *rtc_control)
1079 {
1080         struct cmos_rtc *cmos = dev_get_drvdata(dev);
1081         acpi_event_status rtc_status;
1082         acpi_status status;
1083 
1084         if (acpi_gbl_FADT.flags & ACPI_FADT_FIXED_RTC)
1085                 return;
1086 
1087         status = acpi_get_event_status(ACPI_EVENT_RTC, &rtc_status);
1088         if (ACPI_FAILURE(status)) {
1089                 dev_err(dev, "Could not get RTC status\n");
1090         } else if (rtc_status & ACPI_EVENT_FLAG_SET) {
1091                 unsigned char mask;
1092                 *rtc_control &= ~RTC_AIE;
1093                 CMOS_WRITE(*rtc_control, RTC_CONTROL);
1094                 mask = CMOS_READ(RTC_INTR_FLAGS);
1095                 rtc_update_irq(cmos->rtc, 1, mask);
1096         }
1097 }
1098 
1099 #else
1100 
1101 static void cmos_wake_setup(struct device *dev)
1102 {
1103 }
1104 
1105 static void cmos_check_acpi_rtc_status(struct device *dev,
1106                                        unsigned char *rtc_control)
1107 {
1108 }
1109 
1110 #endif
1111 
1112 #ifdef  CONFIG_PNP
1113 
1114 #include <linux/pnp.h>
1115 
1116 static int cmos_pnp_probe(struct pnp_dev *pnp, const struct pnp_device_id *id)
1117 {
1118         cmos_wake_setup(&pnp->dev);
1119 
1120         if (pnp_port_start(pnp, 0) == 0x70 && !pnp_irq_valid(pnp, 0))
1121                 /* Some machines contain a PNP entry for the RTC, but
1122                  * don't define the IRQ. It should always be safe to
1123                  * hardcode it in these cases
1124                  */
1125                 return cmos_do_probe(&pnp->dev,
1126                                 pnp_get_resource(pnp, IORESOURCE_IO, 0), 8);
1127         else
1128                 return cmos_do_probe(&pnp->dev,
1129                                 pnp_get_resource(pnp, IORESOURCE_IO, 0),
1130                                 pnp_irq(pnp, 0));
1131 }
1132 
1133 static void cmos_pnp_remove(struct pnp_dev *pnp)
1134 {
1135         cmos_do_remove(&pnp->dev);
1136 }
1137 
1138 static void cmos_pnp_shutdown(struct pnp_dev *pnp)
1139 {
1140         struct device *dev = &pnp->dev;
1141         struct cmos_rtc *cmos = dev_get_drvdata(dev);
1142 
1143         if (system_state == SYSTEM_POWER_OFF) {
1144                 int retval = cmos_poweroff(dev);
1145 
1146                 if (cmos_aie_poweroff(dev) < 0 && !retval)
1147                         return;
1148         }
1149 
1150         cmos_do_shutdown(cmos->irq);
1151 }
1152 
1153 static const struct pnp_device_id rtc_ids[] = {
1154         { .id = "PNP0b00", },
1155         { .id = "PNP0b01", },
1156         { .id = "PNP0b02", },
1157         { },
1158 };
1159 MODULE_DEVICE_TABLE(pnp, rtc_ids);
1160 
1161 static struct pnp_driver cmos_pnp_driver = {
1162         .name           = (char *) driver_name,
1163         .id_table       = rtc_ids,
1164         .probe          = cmos_pnp_probe,
1165         .remove         = cmos_pnp_remove,
1166         .shutdown       = cmos_pnp_shutdown,
1167 
1168         /* flag ensures resume() gets called, and stops syslog spam */
1169         .flags          = PNP_DRIVER_RES_DO_NOT_CHANGE,
1170         .driver         = {
1171                         .pm = &cmos_pm_ops,
1172         },
1173 };
1174 
1175 #endif  /* CONFIG_PNP */
1176 
1177 #ifdef CONFIG_OF
1178 static const struct of_device_id of_cmos_match[] = {
1179         {
1180                 .compatible = "motorola,mc146818",
1181         },
1182         { },
1183 };
1184 MODULE_DEVICE_TABLE(of, of_cmos_match);
1185 
1186 static __init void cmos_of_init(struct platform_device *pdev)
1187 {
1188         struct device_node *node = pdev->dev.of_node;
1189         struct rtc_time time;
1190         int ret;
1191         const __be32 *val;
1192 
1193         if (!node)
1194                 return;
1195 
1196         val = of_get_property(node, "ctrl-reg", NULL);
1197         if (val)
1198                 CMOS_WRITE(be32_to_cpup(val), RTC_CONTROL);
1199 
1200         val = of_get_property(node, "freq-reg", NULL);
1201         if (val)
1202                 CMOS_WRITE(be32_to_cpup(val), RTC_FREQ_SELECT);
1203 
1204         cmos_read_time(&pdev->dev, &time);
1205         ret = rtc_valid_tm(&time);
1206         if (ret) {
1207                 struct rtc_time def_time = {
1208                         .tm_year = 1,
1209                         .tm_mday = 1,
1210                 };
1211                 cmos_set_time(&pdev->dev, &def_time);
1212         }
1213 }
1214 #else
1215 static inline void cmos_of_init(struct platform_device *pdev) {}
1216 #endif
1217 /*----------------------------------------------------------------*/
1218 
1219 /* Platform setup should have set up an RTC device, when PNP is
1220  * unavailable ... this could happen even on (older) PCs.
1221  */
1222 
1223 static int __init cmos_platform_probe(struct platform_device *pdev)
1224 {
1225         struct resource *resource;
1226         int irq;
1227 
1228         cmos_of_init(pdev);
1229         cmos_wake_setup(&pdev->dev);
1230 
1231         if (RTC_IOMAPPED)
1232                 resource = platform_get_resource(pdev, IORESOURCE_IO, 0);
1233         else
1234                 resource = platform_get_resource(pdev, IORESOURCE_MEM, 0);
1235         irq = platform_get_irq(pdev, 0);
1236         if (irq < 0)
1237                 irq = -1;
1238 
1239         return cmos_do_probe(&pdev->dev, resource, irq);
1240 }
1241 
1242 static int cmos_platform_remove(struct platform_device *pdev)
1243 {
1244         cmos_do_remove(&pdev->dev);
1245         return 0;
1246 }
1247 
1248 static void cmos_platform_shutdown(struct platform_device *pdev)
1249 {
1250         struct device *dev = &pdev->dev;
1251         struct cmos_rtc *cmos = dev_get_drvdata(dev);
1252 
1253         if (system_state == SYSTEM_POWER_OFF) {
1254                 int retval = cmos_poweroff(dev);
1255 
1256                 if (cmos_aie_poweroff(dev) < 0 && !retval)
1257                         return;
1258         }
1259 
1260         cmos_do_shutdown(cmos->irq);
1261 }
1262 
1263 /* work with hotplug and coldplug */
1264 MODULE_ALIAS("platform:rtc_cmos");
1265 
1266 static struct platform_driver cmos_platform_driver = {
1267         .remove         = cmos_platform_remove,
1268         .shutdown       = cmos_platform_shutdown,
1269         .driver = {
1270                 .name           = driver_name,
1271                 .pm             = &cmos_pm_ops,
1272                 .of_match_table = of_match_ptr(of_cmos_match),
1273         }
1274 };
1275 
1276 #ifdef CONFIG_PNP
1277 static bool pnp_driver_registered;
1278 #endif
1279 static bool platform_driver_registered;
1280 
1281 static int __init cmos_init(void)
1282 {
1283         int retval = 0;
1284 
1285 #ifdef  CONFIG_PNP
1286         retval = pnp_register_driver(&cmos_pnp_driver);
1287         if (retval == 0)
1288                 pnp_driver_registered = true;
1289 #endif
1290 
1291         if (!cmos_rtc.dev) {
1292                 retval = platform_driver_probe(&cmos_platform_driver,
1293                                                cmos_platform_probe);
1294                 if (retval == 0)
1295                         platform_driver_registered = true;
1296         }
1297 
1298         if (retval == 0)
1299                 return 0;
1300 
1301 #ifdef  CONFIG_PNP
1302         if (pnp_driver_registered)
1303                 pnp_unregister_driver(&cmos_pnp_driver);
1304 #endif
1305         return retval;
1306 }
1307 module_init(cmos_init);
1308 
1309 static void __exit cmos_exit(void)
1310 {
1311 #ifdef  CONFIG_PNP
1312         if (pnp_driver_registered)
1313                 pnp_unregister_driver(&cmos_pnp_driver);
1314 #endif
1315         if (platform_driver_registered)
1316                 platform_driver_unregister(&cmos_platform_driver);
1317 }
1318 module_exit(cmos_exit);
1319 
1320 
1321 MODULE_AUTHOR("David Brownell");
1322 MODULE_DESCRIPTION("Driver for PC-style 'CMOS' RTCs");
1323 MODULE_LICENSE("GPL");
1324 

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