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

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