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");