drivers/rtc/rtc-cmos.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  * RTC class driver for "CMOS RTC":  PCs, ACPI, etc
   4  *
   5  * Copyright (C) 1996 Paul Gortmaker (drivers/char/rtc.c)
   6  * Copyright (C) 2006 David Brownell (convert to new framework)
   7  */
   8
   9 /*
  10  * The original "cmos clock" chip was an MC146818 chip, now obsolete.
  11  * That defined the register interface now provided by all PCs, some
  12  * non-PC systems, and incorporated into ACPI.  Modern PC chipsets
  13  * integrate an MC146818 clone in their southbridge, and boards use
  14  * that instead of discrete clones like the DS12887 or M48T86.  There
  15  * are also clones that connect using the LPC bus.
  16  *
  17  * That register API is also used directly by various other drivers
  18  * (notably for integrated NVRAM), infrastructure (x86 has code to
  19  * bypass the RTC framework, directly reading the RTC during boot
  20  * and updating minutes/seconds for systems using NTP synch) and
  21  * utilities (like userspace 'hwclock', if no /dev node exists).
  22  *
  23  * So **ALL** calls to CMOS_READ and CMOS_WRITE must be done with
  24  * interrupts disabled, holding the global rtc_lock, to exclude those
  25  * other drivers and utilities on correctly configured systems.
  26  */
  27
  28 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  29
  30 #include <linux/kernel.h>
  31 #include <linux/module.h>
  32 #include <linux/init.h>
  33 #include <linux/interrupt.h>
  34 #include <linux/spinlock.h>
  35 #include <linux/platform_device.h>
  36 #include <linux/log2.h>
  37 #include <linux/pm.h>
  38 #include <linux/of.h>
  39 #include <linux/of_platform.h>
  40 #ifdef CONFIG_X86
  41 #include <asm/i8259.h>
  42 #include <asm/processor.h>
  43 #include <linux/dmi.h>
  44 #endif
  45
  46 /* this is for "generic access to PC-style RTC" using CMOS_READ/CMOS_WRITE */
  47 #include <linux/mc146818rtc.h>
  48
  49 #ifdef CONFIG_ACPI
  50 /*
  51  * Use ACPI SCI to replace HPET interrupt for RTC Alarm event
  52  *
  53  * If cleared, ACPI SCI is only used to wake up the system from suspend
  54  *
  55  * If set, ACPI SCI is used to handle UIE/AIE and system wakeup
  56  */
  57
  58 static bool use_acpi_alarm;
  59 module_param(use_acpi_alarm, bool, 0444);
  60
  61 static inline int cmos_use_acpi_alarm(void)
  62 {
  63         return use_acpi_alarm;
  64 }
  65 #else /* !CONFIG_ACPI */
  66
  67 static inline int cmos_use_acpi_alarm(void)
  68 {
  69         return 0;
  70 }
  71 #endif
  72
  73 struct cmos_rtc {
  74         struct rtc_device       *rtc;
  75         struct device           *dev;
  76         int                     irq;
  77         struct resource         *iomem;
  78         time64_t                alarm_expires;
  79
  80         void                    (*wake_on)(struct device *);
  81         void                    (*wake_off)(struct device *);
  82
  83         u8                      enabled_wake;
  84         u8                      suspend_ctrl;
  85
  86         /* newer hardware extends the original register set */
  87         u8                      day_alrm;
  88         u8                      mon_alrm;
  89         u8                      century;
  90
  91         struct rtc_wkalrm       saved_wkalrm;
  92 };
  93
  94 /* both platform and pnp busses use negative numbers for invalid irqs */
  95 #define is_valid_irq(n)         ((n) > 0)
  96
  97 static const char driver_name[] = "rtc_cmos";
  98
  99 /* The RTC_INTR register may have e.g. RTC_PF set even if RTC_PIE is clear;
 100  * always mask it against the irq enable bits in RTC_CONTROL.  Bit values
 101  * are the same: PF==PIE, AF=AIE, UF=UIE; so RTC_IRQMASK works with both.
 102  */
 103 #define RTC_IRQMASK     (RTC_PF | RTC_AF | RTC_UF)
 104
 105 static inline int is_intr(u8 rtc_intr)
 106 {
 107         if (!(rtc_intr & RTC_IRQF))
 108                 return 0;
 109         return rtc_intr & RTC_IRQMASK;
 110 }
 111
 112 /*----------------------------------------------------------------*/
 113
 114 /* Much modern x86 hardware has HPETs (10+ MHz timers) which, because
 115  * many BIOS programmers don't set up "sane mode" IRQ routing, are mostly
 116  * used in a broken "legacy replacement" mode.  The breakage includes
 117  * HPET #1 hijacking the IRQ for this RTC, and being unavailable for
 118  * other (better) use.
 119  *
 120  * When that broken mode is in use, platform glue provides a partial
 121  * emulation of hardware RTC IRQ facilities using HPET #1.  We don't
 122  * want to use HPET for anything except those IRQs though...
 123  */
 124 #ifdef CONFIG_HPET_EMULATE_RTC
 125 #include <asm/hpet.h>
 126 #else
 127
 128 static inline int is_hpet_enabled(void)
 129 {
 130         return 0;
 131 }
 132
 133 static inline int hpet_mask_rtc_irq_bit(unsigned long mask)
 134 {
 135         return 0;
 136 }
 137
 138 static inline int hpet_set_rtc_irq_bit(unsigned long mask)
 139 {
 140         return 0;
 141 }
 142
 143 static inline int
 144 hpet_set_alarm_time(unsigned char hrs, unsigned char min, unsigned char sec)
 145 {
 146         return 0;
 147 }
 148
 149 static inline int hpet_set_periodic_freq(unsigned long freq)
 150 {
 151         return 0;
 152 }
 153
 154 static inline int hpet_rtc_dropped_irq(void)
 155 {
 156         return 0;
 157 }
 158
 159 static inline int hpet_rtc_timer_init(void)
 160 {
 161         return 0;
 162 }
 163
 164 extern irq_handler_t hpet_rtc_interrupt;
 165
 166 static inline int hpet_register_irq_handler(irq_handler_t handler)
 167 {
 168         return 0;
 169 }
 170
 171 static inline int hpet_unregister_irq_handler(irq_handler_t handler)
 172 {
 173         return 0;
 174 }
 175
 176 #endif
 177
 178 /* Don't use HPET for RTC Alarm event if ACPI Fixed event is used */
 179 static inline int use_hpet_alarm(void)
 180 {
 181         return is_hpet_enabled() && !cmos_use_acpi_alarm();
 182 }
 183
 184 /*----------------------------------------------------------------*/
 185
 186 #ifdef RTC_PORT
 187
 188 /* Most newer x86 systems have two register banks, the first used
 189  * for RTC and NVRAM and the second only for NVRAM.  Caller must
 190  * own rtc_lock ... and we won't worry about access during NMI.
 191  */
 192 #define can_bank2       true
 193
 194 static inline unsigned char cmos_read_bank2(unsigned char addr)
 195 {
 196         outb(addr, RTC_PORT(2));
 197         return inb(RTC_PORT(3));
 198 }
 199
 200 static inline void cmos_write_bank2(unsigned char val, unsigned char addr)
 201 {
 202         outb(addr, RTC_PORT(2));
 203         outb(val, RTC_PORT(3));
 204 }
 205
 206 #else
 207
 208 #define can_bank2       false
 209
 210 static inline unsigned char cmos_read_bank2(unsigned char addr)
 211 {
 212         return 0;
 213 }
 214
 215 static inline void cmos_write_bank2(unsigned char val, unsigned char addr)
 216 {
 217 }
 218
 219 #endif
 220
 221 /*----------------------------------------------------------------*/
 222
 223 static int cmos_read_time(struct device *dev, struct rtc_time *t)
 224 {
 225         int ret;
 226
 227         /*
 228          * If pm_trace abused the RTC for storage, set the timespec to 0,
 229          * which tells the caller that this RTC value is unusable.
 230          */
 231         if (!pm_trace_rtc_valid())
 232                 return -EIO;
 233
 234         ret = mc146818_get_time(t, 1000);
 235         if (ret < 0) {
 236                 dev_err_ratelimited(dev, "unable to read current time\n");
 237                 return ret;
 238         }
 239
 240         return 0;
 241 }
 242
 243 static int cmos_set_time(struct device *dev, struct rtc_time *t)
 244 {
 245         /* NOTE: this ignores the issue whereby updating the seconds
 246          * takes effect exactly 500ms after we write the register.
 247          * (Also queueing and other delays before we get this far.)
 248          */
 249         return mc146818_set_time(t);
 250 }
 251
 252 struct cmos_read_alarm_callback_param {
 253         struct cmos_rtc *cmos;
 254         struct rtc_time *time;
 255         unsigned char   rtc_control;
 256 };
 257
 258 static void cmos_read_alarm_callback(unsigned char __always_unused seconds,
 259                                      void *param_in)
 260 {
 261         struct cmos_read_alarm_callback_param *p =
 262                 (struct cmos_read_alarm_callback_param *)param_in;
 263         struct rtc_time *time = p->time;
 264
 265         time->tm_sec = CMOS_READ(RTC_SECONDS_ALARM);
 266         time->tm_min = CMOS_READ(RTC_MINUTES_ALARM);
 267         time->tm_hour = CMOS_READ(RTC_HOURS_ALARM);
 268
 269         if (p->cmos->day_alrm) {
 270                 /* ignore upper bits on readback per ACPI spec */
 271                 time->tm_mday = CMOS_READ(p->cmos->day_alrm) & 0x3f;
 272                 if (!time->tm_mday)
 273                         time->tm_mday = -1;
 274
 275                 if (p->cmos->mon_alrm) {
 276                         time->tm_mon = CMOS_READ(p->cmos->mon_alrm);
 277                         if (!time->tm_mon)
 278                                 time->tm_mon = -1;
 279                 }
 280         }
 281
 282         p->rtc_control = CMOS_READ(RTC_CONTROL);
 283 }
 284
 285 static int cmos_read_alarm(struct device *dev, struct rtc_wkalrm *t)
 286 {
 287         struct cmos_rtc *cmos = dev_get_drvdata(dev);
 288         struct cmos_read_alarm_callback_param p = {
 289                 .cmos = cmos,
 290                 .time = &t->time,
 291         };
 292
 293         /* This not only a rtc_op, but also called directly */
 294         if (!is_valid_irq(cmos->irq))
 295                 return -ETIMEDOUT;
 296
 297         /* Basic alarms only support hour, minute, and seconds fields.
 298          * Some also support day and month, for alarms up to a year in
 299          * the future.
 300          */
 301
 302         /* Some Intel chipsets disconnect the alarm registers when the clock
 303          * update is in progress - during this time reads return bogus values
 304          * and writes may fail silently. See for example "7th Generation Intel®
 305          * Processor Family I/O for U/Y Platforms [...] Datasheet", section
 306          * 27.7.1
 307          *
 308          * Use the mc146818_avoid_UIP() function to avoid this.
 309          */
 310         if (!mc146818_avoid_UIP(cmos_read_alarm_callback, 10, &p))
 311                 return -EIO;
 312
 313         if (!(p.rtc_control & RTC_DM_BINARY) || RTC_ALWAYS_BCD) {
 314                 if (((unsigned)t->time.tm_sec) < 0x60)
 315                         t->time.tm_sec = bcd2bin(t->time.tm_sec);
 316                 else
 317                         t->time.tm_sec = -1;
 318                 if (((unsigned)t->time.tm_min) < 0x60)
 319                         t->time.tm_min = bcd2bin(t->time.tm_min);
 320                 else
 321                         t->time.tm_min = -1;
 322                 if (((unsigned)t->time.tm_hour) < 0x24)
 323                         t->time.tm_hour = bcd2bin(t->time.tm_hour);
 324                 else
 325                         t->time.tm_hour = -1;
 326
 327                 if (cmos->day_alrm) {
 328                         if (((unsigned)t->time.tm_mday) <= 0x31)
 329                                 t->time.tm_mday = bcd2bin(t->time.tm_mday);
 330                         else
 331                                 t->time.tm_mday = -1;
 332
 333                         if (cmos->mon_alrm) {
 334                                 if (((unsigned)t->time.tm_mon) <= 0x12)
 335                                         t->time.tm_mon = bcd2bin(t->time.tm_mon)-1;
 336                                 else
 337                                         t->time.tm_mon = -1;
 338                         }
 339                 }
 340         }
 341
 342         t->enabled = !!(p.rtc_control & RTC_AIE);
 343         t->pending = 0;
 344
 345         return 0;
 346 }
 347
 348 static void cmos_checkintr(struct cmos_rtc *cmos, unsigned char rtc_control)
 349 {
 350         unsigned char   rtc_intr;
 351
 352         /* NOTE after changing RTC_xIE bits we always read INTR_FLAGS;
 353          * allegedly some older rtcs need that to handle irqs properly
 354          */
 355         rtc_intr = CMOS_READ(RTC_INTR_FLAGS);
 356
 357         if (use_hpet_alarm())
 358                 return;
 359
 360         rtc_intr &= (rtc_control & RTC_IRQMASK) | RTC_IRQF;
 361         if (is_intr(rtc_intr))
 362                 rtc_update_irq(cmos->rtc, 1, rtc_intr);
 363 }
 364
 365 static void cmos_irq_enable(struct cmos_rtc *cmos, unsigned char mask)
 366 {
 367         unsigned char   rtc_control;
 368
 369         /* flush any pending IRQ status, notably for update irqs,
 370          * before we enable new IRQs
 371          */
 372         rtc_control = CMOS_READ(RTC_CONTROL);
 373         cmos_checkintr(cmos, rtc_control);
 374
 375         rtc_control |= mask;
 376         CMOS_WRITE(rtc_control, RTC_CONTROL);
 377         if (use_hpet_alarm())
 378                 hpet_set_rtc_irq_bit(mask);
 379
 380         if ((mask & RTC_AIE) && cmos_use_acpi_alarm()) {
 381                 if (cmos->wake_on)
 382                         cmos->wake_on(cmos->dev);
 383         }
 384
 385         cmos_checkintr(cmos, rtc_control);
 386 }
 387
 388 static void cmos_irq_disable(struct cmos_rtc *cmos, unsigned char mask)
 389 {
 390         unsigned char   rtc_control;
 391
 392         rtc_control = CMOS_READ(RTC_CONTROL);
 393         rtc_control &= ~mask;
 394         CMOS_WRITE(rtc_control, RTC_CONTROL);
 395         if (use_hpet_alarm())
 396                 hpet_mask_rtc_irq_bit(mask);
 397
 398         if ((mask & RTC_AIE) && cmos_use_acpi_alarm()) {
 399                 if (cmos->wake_off)
 400                         cmos->wake_off(cmos->dev);
 401         }
 402
 403         cmos_checkintr(cmos, rtc_control);
 404 }
 405
 406 static int cmos_validate_alarm(struct device *dev, struct rtc_wkalrm *t)
 407 {
 408         struct cmos_rtc *cmos = dev_get_drvdata(dev);
 409         struct rtc_time now;
 410
 411         cmos_read_time(dev, &now);
 412
 413         if (!cmos->day_alrm) {
 414                 time64_t t_max_date;
 415                 time64_t t_alrm;
 416
 417                 t_max_date = rtc_tm_to_time64(&now);
 418                 t_max_date += 24 * 60 * 60 - 1;
 419                 t_alrm = rtc_tm_to_time64(&t->time);
 420                 if (t_alrm > t_max_date) {
 421                         dev_err(dev,
 422                                 "Alarms can be up to one day in the future\n");
 423                         return -EINVAL;
 424                 }
 425         } else if (!cmos->mon_alrm) {
 426                 struct rtc_time max_date = now;
 427                 time64_t t_max_date;
 428                 time64_t t_alrm;
 429                 int max_mday;
 430
 431                 if (max_date.tm_mon == 11) {
 432                         max_date.tm_mon = 0;
 433                         max_date.tm_year += 1;
 434                 } else {
 435                         max_date.tm_mon += 1;
 436                 }
 437                 max_mday = rtc_month_days(max_date.tm_mon, max_date.tm_year);
 438                 if (max_date.tm_mday > max_mday)
 439                         max_date.tm_mday = max_mday;
 440
 441                 t_max_date = rtc_tm_to_time64(&max_date);
 442                 t_max_date -= 1;
 443                 t_alrm = rtc_tm_to_time64(&t->time);
 444                 if (t_alrm > t_max_date) {
 445                         dev_err(dev,
 446                                 "Alarms can be up to one month in the future\n");
 447                         return -EINVAL;
 448                 }
 449         } else {
 450                 struct rtc_time max_date = now;
 451                 time64_t t_max_date;
 452                 time64_t t_alrm;
 453                 int max_mday;
 454
 455                 max_date.tm_year += 1;
 456                 max_mday = rtc_month_days(max_date.tm_mon, max_date.tm_year);
 457                 if (max_date.tm_mday > max_mday)
 458                         max_date.tm_mday = max_mday;
 459
 460                 t_max_date = rtc_tm_to_time64(&max_date);
 461                 t_max_date -= 1;
 462                 t_alrm = rtc_tm_to_time64(&t->time);
 463                 if (t_alrm > t_max_date) {
 464                         dev_err(dev,
 465                                 "Alarms can be up to one year in the future\n");
 466                         return -EINVAL;
 467                 }
 468         }
 469
 470         return 0;
 471 }
 472
 473 struct cmos_set_alarm_callback_param {
 474         struct cmos_rtc *cmos;
 475         unsigned char mon, mday, hrs, min, sec;
 476         struct rtc_wkalrm *t;
 477 };
 478
 479 /* Note: this function may be executed by mc146818_avoid_UIP() more then
 480  *       once
 481  */
 482 static void cmos_set_alarm_callback(unsigned char __always_unused seconds,
 483                                     void *param_in)
 484 {
 485         struct cmos_set_alarm_callback_param *p =
 486                 (struct cmos_set_alarm_callback_param *)param_in;
 487
 488         /* next rtc irq must not be from previous alarm setting */
 489         cmos_irq_disable(p->cmos, RTC_AIE);
 490
 491         /* update alarm */
 492         CMOS_WRITE(p->hrs, RTC_HOURS_ALARM);
 493         CMOS_WRITE(p->min, RTC_MINUTES_ALARM);
 494         CMOS_WRITE(p->sec, RTC_SECONDS_ALARM);
 495
 496         /* the system may support an "enhanced" alarm */
 497         if (p->cmos->day_alrm) {
 498                 CMOS_WRITE(p->mday, p->cmos->day_alrm);
 499                 if (p->cmos->mon_alrm)
 500                         CMOS_WRITE(p->mon, p->cmos->mon_alrm);
 501         }
 502
 503         if (use_hpet_alarm()) {
 504                 /*
 505                  * FIXME the HPET alarm glue currently ignores day_alrm
 506                  * and mon_alrm ...
 507                  */
 508                 hpet_set_alarm_time(p->t->time.tm_hour, p->t->time.tm_min,
 509                                     p->t->time.tm_sec);
 510         }
 511
 512         if (p->t->enabled)
 513                 cmos_irq_enable(p->cmos, RTC_AIE);
 514 }
 515
 516 static int cmos_set_alarm(struct device *dev, struct rtc_wkalrm *t)
 517 {
 518         struct cmos_rtc *cmos = dev_get_drvdata(dev);
 519         struct cmos_set_alarm_callback_param p = {
 520                 .cmos = cmos,
 521                 .t = t
 522         };
 523         unsigned char rtc_control;
 524         int ret;
 525
 526         /* This not only a rtc_op, but also called directly */
 527         if (!is_valid_irq(cmos->irq))
 528                 return -EIO;
 529
 530         ret = cmos_validate_alarm(dev, t);
 531         if (ret < 0)
 532                 return ret;
 533
 534         p.mon = t->time.tm_mon + 1;
 535         p.mday = t->time.tm_mday;
 536         p.hrs = t->time.tm_hour;
 537         p.min = t->time.tm_min;
 538         p.sec = t->time.tm_sec;
 539
 540         spin_lock_irq(&rtc_lock);
 541         rtc_control = CMOS_READ(RTC_CONTROL);
 542         spin_unlock_irq(&rtc_lock);
 543
 544         if (!(rtc_control & RTC_DM_BINARY) || RTC_ALWAYS_BCD) {
 545                 /* Writing 0xff means "don't care" or "match all".  */
 546                 p.mon = (p.mon <= 12) ? bin2bcd(p.mon) : 0xff;
 547                 p.mday = (p.mday >= 1 && p.mday <= 31) ? bin2bcd(p.mday) : 0xff;
 548                 p.hrs = (p.hrs < 24) ? bin2bcd(p.hrs) : 0xff;
 549                 p.min = (p.min < 60) ? bin2bcd(p.min) : 0xff;
 550                 p.sec = (p.sec < 60) ? bin2bcd(p.sec) : 0xff;
 551         }
 552
 553         /*
 554          * Some Intel chipsets disconnect the alarm registers when the clock
 555          * update is in progress - during this time writes fail silently.
 556          *
 557          * Use mc146818_avoid_UIP() to avoid this.
 558          */
 559         if (!mc146818_avoid_UIP(cmos_set_alarm_callback, 10, &p))
 560                 return -ETIMEDOUT;
 561
 562         cmos->alarm_expires = rtc_tm_to_time64(&t->time);
 563
 564         return 0;
 565 }
 566
 567 static int cmos_alarm_irq_enable(struct device *dev, unsigned int enabled)
 568 {
 569         struct cmos_rtc *cmos = dev_get_drvdata(dev);
 570         unsigned long   flags;
 571
 572         spin_lock_irqsave(&rtc_lock, flags);
 573
 574         if (enabled)
 575                 cmos_irq_enable(cmos, RTC_AIE);
 576         else
 577                 cmos_irq_disable(cmos, RTC_AIE);
 578
 579         spin_unlock_irqrestore(&rtc_lock, flags);
 580         return 0;
 581 }
 582
 583 #if IS_ENABLED(CONFIG_RTC_INTF_PROC)
 584
 585 static int cmos_procfs(struct device *dev, struct seq_file *seq)
 586 {
 587         struct cmos_rtc *cmos = dev_get_drvdata(dev);
 588         unsigned char   rtc_control, valid;
 589
 590         spin_lock_irq(&rtc_lock);
 591         rtc_control = CMOS_READ(RTC_CONTROL);
 592         valid = CMOS_READ(RTC_VALID);
 593         spin_unlock_irq(&rtc_lock);
 594
 595         /* NOTE:  at least ICH6 reports battery status using a different
 596          * (non-RTC) bit; and SQWE is ignored on many current systems.
 597          */
 598         seq_printf(seq,
 599                    "periodic_IRQ\t: %s\n"
 600                    "update_IRQ\t: %s\n"
 601                    "HPET_emulated\t: %s\n"
 602                    // "square_wave\t: %s\n"
 603                    "BCD\t\t: %s\n"
 604                    "DST_enable\t: %s\n"
 605                    "periodic_freq\t: %d\n"
 606                    "batt_status\t: %s\n",
 607                    (rtc_control & RTC_PIE) ? "yes" : "no",
 608                    (rtc_control & RTC_UIE) ? "yes" : "no",
 609                    use_hpet_alarm() ? "yes" : "no",
 610                    // (rtc_control & RTC_SQWE) ? "yes" : "no",
 611                    (rtc_control & RTC_DM_BINARY) ? "no" : "yes",
 612                    (rtc_control & RTC_DST_EN) ? "yes" : "no",
 613                    cmos->rtc->irq_freq,
 614                    (valid & RTC_VRT) ? "okay" : "dead");
 615
 616         return 0;
 617 }
 618
 619 #else
 620 #define cmos_procfs     NULL
 621 #endif
 622
 623 static const struct rtc_class_ops cmos_rtc_ops = {
 624         .read_time              = cmos_read_time,
 625         .set_time               = cmos_set_time,
 626         .read_alarm             = cmos_read_alarm,
 627         .set_alarm              = cmos_set_alarm,
 628         .proc                   = cmos_procfs,
 629         .alarm_irq_enable       = cmos_alarm_irq_enable,
 630 };
 631
 632 /*----------------------------------------------------------------*/
 633
 634 /*
 635  * All these chips have at least 64 bytes of address space, shared by
 636  * RTC registers and NVRAM.  Most of those bytes of NVRAM are used
 637  * by boot firmware.  Modern chips have 128 or 256 bytes.
 638  */
 639
 640 #define NVRAM_OFFSET    (RTC_REG_D + 1)
 641
 642 static int cmos_nvram_read(void *priv, unsigned int off, void *val,
 643                            size_t count)
 644 {
 645         unsigned char *buf = val;
 646         int     retval;
 647
 648         off += NVRAM_OFFSET;
 649         spin_lock_irq(&rtc_lock);
 650         for (retval = 0; count; count--, off++, retval++) {
 651                 if (off < 128)
 652                         *buf++ = CMOS_READ(off);
 653                 else if (can_bank2)
 654                         *buf++ = cmos_read_bank2(off);
 655                 else
 656                         break;
 657         }
 658         spin_unlock_irq(&rtc_lock);
 659
 660         return retval;
 661 }
 662
 663 static int cmos_nvram_write(void *priv, unsigned int off, void *val,
 664                             size_t count)
 665 {
 666         struct cmos_rtc *cmos = priv;
 667         unsigned char   *buf = val;
 668         int             retval;
 669
 670         /* NOTE:  on at least PCs and Ataris, the boot firmware uses a
 671          * checksum on part of the NVRAM data.  That's currently ignored
 672          * here.  If userspace is smart enough to know what fields of
 673          * NVRAM to update, updating checksums is also part of its job.
 674          */
 675         off += NVRAM_OFFSET;
 676         spin_lock_irq(&rtc_lock);
 677         for (retval = 0; count; count--, off++, retval++) {
 678                 /* don't trash RTC registers */
 679                 if (off == cmos->day_alrm
 680                                 || off == cmos->mon_alrm
 681                                 || off == cmos->century)
 682                         buf++;
 683                 else if (off < 128)
 684                         CMOS_WRITE(*buf++, off);
 685                 else if (can_bank2)
 686                         cmos_write_bank2(*buf++, off);
 687                 else
 688                         break;
 689         }
 690         spin_unlock_irq(&rtc_lock);
 691
 692         return retval;
 693 }
 694
 695 /*----------------------------------------------------------------*/
 696
 697 static struct cmos_rtc  cmos_rtc;
 698
 699 static irqreturn_t cmos_interrupt(int irq, void *p)
 700 {
 701         u8              irqstat;
 702         u8              rtc_control;
 703
 704         spin_lock(&rtc_lock);
 705
 706         /* When the HPET interrupt handler calls us, the interrupt
 707          * status is passed as arg1 instead of the irq number.  But
 708          * always clear irq status, even when HPET is in the way.
 709          *
 710          * Note that HPET and RTC are almost certainly out of phase,
 711          * giving different IRQ status ...
 712          */
 713         irqstat = CMOS_READ(RTC_INTR_FLAGS);
 714         rtc_control = CMOS_READ(RTC_CONTROL);
 715         if (use_hpet_alarm())
 716                 irqstat = (unsigned long)irq & 0xF0;
 717
 718         /* If we were suspended, RTC_CONTROL may not be accurate since the
 719          * bios may have cleared it.
 720          */
 721         if (!cmos_rtc.suspend_ctrl)
 722                 irqstat &= (rtc_control & RTC_IRQMASK) | RTC_IRQF;
 723         else
 724                 irqstat &= (cmos_rtc.suspend_ctrl & RTC_IRQMASK) | RTC_IRQF;
 725
 726         /* All Linux RTC alarms should be treated as if they were oneshot.
 727          * Similar code may be needed in system wakeup paths, in case the
 728          * alarm woke the system.
 729          */
 730         if (irqstat & RTC_AIE) {
 731                 cmos_rtc.suspend_ctrl &= ~RTC_AIE;
 732                 rtc_control &= ~RTC_AIE;
 733                 CMOS_WRITE(rtc_control, RTC_CONTROL);
 734                 if (use_hpet_alarm())
 735                         hpet_mask_rtc_irq_bit(RTC_AIE);
 736                 CMOS_READ(RTC_INTR_FLAGS);
 737         }
 738         spin_unlock(&rtc_lock);
 739
 740         if (is_intr(irqstat)) {
 741                 rtc_update_irq(p, 1, irqstat);
 742                 return IRQ_HANDLED;
 743         } else
 744                 return IRQ_NONE;
 745 }
 746
 747 #ifdef  CONFIG_ACPI
 748
 749 #include <linux/acpi.h>
 750
 751 static u32 rtc_handler(void *context)
 752 {
 753         struct device *dev = context;
 754         struct cmos_rtc *cmos = dev_get_drvdata(dev);
 755         unsigned char rtc_control = 0;
 756         unsigned char rtc_intr;
 757         unsigned long flags;
 758
 759
 760         /*
 761          * Always update rtc irq when ACPI is used as RTC Alarm.
 762          * Or else, ACPI SCI is enabled during suspend/resume only,
 763          * update rtc irq in that case.
 764          */
 765         if (cmos_use_acpi_alarm())
 766                 cmos_interrupt(0, (void *)cmos->rtc);
 767         else {
 768                 /* Fix me: can we use cmos_interrupt() here as well? */
 769                 spin_lock_irqsave(&rtc_lock, flags);
 770                 if (cmos_rtc.suspend_ctrl)
 771                         rtc_control = CMOS_READ(RTC_CONTROL);
 772                 if (rtc_control & RTC_AIE) {
 773                         cmos_rtc.suspend_ctrl &= ~RTC_AIE;
 774                         CMOS_WRITE(rtc_control, RTC_CONTROL);
 775                         rtc_intr = CMOS_READ(RTC_INTR_FLAGS);
 776                         rtc_update_irq(cmos->rtc, 1, rtc_intr);
 777                 }
 778                 spin_unlock_irqrestore(&rtc_lock, flags);
 779         }
 780
 781         pm_wakeup_hard_event(dev);
 782         acpi_clear_event(ACPI_EVENT_RTC);
 783         acpi_disable_event(ACPI_EVENT_RTC, 0);
 784         return ACPI_INTERRUPT_HANDLED;
 785 }
 786
 787 static void acpi_rtc_event_setup(struct device *dev)
 788 {
 789         if (acpi_disabled)
 790                 return;
 791
 792         acpi_install_fixed_event_handler(ACPI_EVENT_RTC, rtc_handler, dev);
 793         /*
 794          * After the RTC handler is installed, the Fixed_RTC event should
 795          * be disabled. Only when the RTC alarm is set will it be enabled.
 796          */
 797         acpi_clear_event(ACPI_EVENT_RTC);
 798         acpi_disable_event(ACPI_EVENT_RTC, 0);
 799 }
 800
 801 static void acpi_rtc_event_cleanup(void)
 802 {
 803         if (acpi_disabled)
 804                 return;
 805
 806         acpi_remove_fixed_event_handler(ACPI_EVENT_RTC, rtc_handler);
 807 }
 808
 809 static void rtc_wake_on(struct device *dev)
 810 {
 811         acpi_clear_event(ACPI_EVENT_RTC);
 812         acpi_enable_event(ACPI_EVENT_RTC, 0);
 813 }
 814
 815 static void rtc_wake_off(struct device *dev)
 816 {
 817         acpi_disable_event(ACPI_EVENT_RTC, 0);
 818 }
 819
 820 #ifdef CONFIG_X86
 821 static void use_acpi_alarm_quirks(void)
 822 {
 823         switch (boot_cpu_data.x86_vendor) {
 824         case X86_VENDOR_INTEL:
 825                 if (dmi_get_bios_year() < 2015)
 826                         return;
 827                 break;
 828         case X86_VENDOR_AMD:
 829         case X86_VENDOR_HYGON:
 830                 if (dmi_get_bios_year() < 2021)
 831                         return;
 832                 break;
 833         default:
 834                 return;
 835         }
 836         if (!is_hpet_enabled())
 837                 return;
 838
 839         use_acpi_alarm = true;
 840 }
 841 #else
 842 static inline void use_acpi_alarm_quirks(void) { }
 843 #endif
 844
 845 static void acpi_cmos_wake_setup(struct device *dev)
 846 {
 847         if (acpi_disabled)
 848                 return;
 849
 850         use_acpi_alarm_quirks();
 851
 852         cmos_rtc.wake_on = rtc_wake_on;
 853         cmos_rtc.wake_off = rtc_wake_off;
 854
 855         /* ACPI tables bug workaround. */
 856         if (acpi_gbl_FADT.month_alarm && !acpi_gbl_FADT.day_alarm) {
 857                 dev_dbg(dev, "bogus FADT month_alarm (%d)\n",
 858                         acpi_gbl_FADT.month_alarm);
 859                 acpi_gbl_FADT.month_alarm = 0;
 860         }
 861
 862         cmos_rtc.day_alrm = acpi_gbl_FADT.day_alarm;
 863         cmos_rtc.mon_alrm = acpi_gbl_FADT.month_alarm;
 864         cmos_rtc.century = acpi_gbl_FADT.century;
 865
 866         if (acpi_gbl_FADT.flags & ACPI_FADT_S4_RTC_WAKE)
 867                 dev_info(dev, "RTC can wake from S4\n");
 868
 869         /* RTC always wakes from S1/S2/S3, and often S4/STD */
 870         device_init_wakeup(dev, 1);
 871 }
 872
 873 static void cmos_check_acpi_rtc_status(struct device *dev,
 874                                               unsigned char *rtc_control)
 875 {
 876         struct cmos_rtc *cmos = dev_get_drvdata(dev);
 877         acpi_event_status rtc_status;
 878         acpi_status status;
 879
 880         if (acpi_gbl_FADT.flags & ACPI_FADT_FIXED_RTC)
 881                 return;
 882
 883         status = acpi_get_event_status(ACPI_EVENT_RTC, &rtc_status);
 884         if (ACPI_FAILURE(status)) {
 885                 dev_err(dev, "Could not get RTC status\n");
 886         } else if (rtc_status & ACPI_EVENT_FLAG_SET) {
 887                 unsigned char mask;
 888                 *rtc_control &= ~RTC_AIE;
 889                 CMOS_WRITE(*rtc_control, RTC_CONTROL);
 890                 mask = CMOS_READ(RTC_INTR_FLAGS);
 891                 rtc_update_irq(cmos->rtc, 1, mask);
 892         }
 893 }
 894
 895 #else /* !CONFIG_ACPI */
 896
 897 static inline void acpi_rtc_event_setup(struct device *dev)
 898 {
 899 }
 900
 901 static inline void acpi_rtc_event_cleanup(void)
 902 {
 903 }
 904
 905 static inline void acpi_cmos_wake_setup(struct device *dev)
 906 {
 907 }
 908
 909 static inline void cmos_check_acpi_rtc_status(struct device *dev,
 910                                               unsigned char *rtc_control)
 911 {
 912 }
 913 #endif /* CONFIG_ACPI */
 914
 915 #ifdef  CONFIG_PNP
 916 #define INITSECTION
 917
 918 #else
 919 #define INITSECTION     __init
 920 #endif
 921
 922 #define SECS_PER_DAY    (24 * 60 * 60)
 923 #define SECS_PER_MONTH  (28 * SECS_PER_DAY)
 924 #define SECS_PER_YEAR   (365 * SECS_PER_DAY)
 925
 926 static int INITSECTION
 927 cmos_do_probe(struct device *dev, struct resource *ports, int rtc_irq)
 928 {
 929         struct cmos_rtc_board_info      *info = dev_get_platdata(dev);
 930         int                             retval = 0;
 931         unsigned char                   rtc_control;
 932         unsigned                        address_space;
 933         u32                             flags = 0;
 934         struct nvmem_config nvmem_cfg = {
 935                 .name = "cmos_nvram",
 936                 .word_size = 1,
 937                 .stride = 1,
 938                 .reg_read = cmos_nvram_read,
 939                 .reg_write = cmos_nvram_write,
 940                 .priv = &cmos_rtc,
 941         };
 942
 943         /* there can be only one ... */
 944         if (cmos_rtc.dev)
 945                 return -EBUSY;
 946
 947         if (!ports)
 948                 return -ENODEV;
 949
 950         /* Claim I/O ports ASAP, minimizing conflict with legacy driver.
 951          *
 952          * REVISIT non-x86 systems may instead use memory space resources
 953          * (needing ioremap etc), not i/o space resources like this ...
 954          */
 955         if (RTC_IOMAPPED)
 956                 ports = request_region(ports->start, resource_size(ports),
 957                                        driver_name);
 958         else
 959                 ports = request_mem_region(ports->start, resource_size(ports),
 960                                            driver_name);
 961         if (!ports) {
 962                 dev_dbg(dev, "i/o registers already in use\n");
 963                 return -EBUSY;
 964         }
 965
 966         cmos_rtc.irq = rtc_irq;
 967         cmos_rtc.iomem = ports;
 968
 969         /* Heuristic to deduce NVRAM size ... do what the legacy NVRAM
 970          * driver did, but don't reject unknown configs.   Old hardware
 971          * won't address 128 bytes.  Newer chips have multiple banks,
 972          * though they may not be listed in one I/O resource.
 973          */
 974 #if     defined(CONFIG_ATARI)
 975         address_space = 64;
 976 #elif defined(__i386__) || defined(__x86_64__) || defined(__arm__) \
 977                         || defined(__sparc__) || defined(__mips__) \
 978                         || defined(__powerpc__)
 979         address_space = 128;
 980 #else
 981 #warning Assuming 128 bytes of RTC+NVRAM address space, not 64 bytes.
 982         address_space = 128;
 983 #endif
 984         if (can_bank2 && ports->end > (ports->start + 1))
 985                 address_space = 256;
 986
 987         /* For ACPI systems extension info comes from the FADT.  On others,
 988          * board specific setup provides it as appropriate.  Systems where
 989          * the alarm IRQ isn't automatically a wakeup IRQ (like ACPI, and
 990          * some almost-clones) can provide hooks to make that behave.
 991          *
 992          * Note that ACPI doesn't preclude putting these registers into
 993          * "extended" areas of the chip, including some that we won't yet
 994          * expect CMOS_READ and friends to handle.
 995          */
 996         if (info) {
 997                 if (info->flags)
 998                         flags = info->flags;
 999                 if (info->address_space)
1000                         address_space = info->address_space;
1001
1002                 cmos_rtc.day_alrm = info->rtc_day_alarm;
1003                 cmos_rtc.mon_alrm = info->rtc_mon_alarm;
1004                 cmos_rtc.century = info->rtc_century;
1005
1006                 if (info->wake_on && info->wake_off) {
1007                         cmos_rtc.wake_on = info->wake_on;
1008                         cmos_rtc.wake_off = info->wake_off;
1009                 }
1010         } else {
1011                 acpi_cmos_wake_setup(dev);
1012         }
1013
1014         if (cmos_rtc.day_alrm >= 128)
1015                 cmos_rtc.day_alrm = 0;
1016
1017         if (cmos_rtc.mon_alrm >= 128)
1018                 cmos_rtc.mon_alrm = 0;
1019
1020         if (cmos_rtc.century >= 128)
1021                 cmos_rtc.century = 0;
1022
1023         cmos_rtc.dev = dev;
1024         dev_set_drvdata(dev, &cmos_rtc);
1025
1026         cmos_rtc.rtc = devm_rtc_allocate_device(dev);
1027         if (IS_ERR(cmos_rtc.rtc)) {
1028                 retval = PTR_ERR(cmos_rtc.rtc);
1029                 goto cleanup0;
1030         }
1031
1032         if (cmos_rtc.mon_alrm)
1033                 cmos_rtc.rtc->alarm_offset_max = SECS_PER_YEAR - 1;
1034         else if (cmos_rtc.day_alrm)
1035                 cmos_rtc.rtc->alarm_offset_max = SECS_PER_MONTH - 1;
1036         else
1037                 cmos_rtc.rtc->alarm_offset_max = SECS_PER_DAY - 1;
1038
1039         rename_region(ports, dev_name(&cmos_rtc.rtc->dev));
1040
1041         if (!mc146818_does_rtc_work()) {
1042                 dev_warn(dev, "broken or not accessible\n");
1043                 retval = -ENXIO;
1044                 goto cleanup1;
1045         }
1046
1047         spin_lock_irq(&rtc_lock);
1048
1049         if (!(flags & CMOS_RTC_FLAGS_NOFREQ)) {
1050                 /* force periodic irq to CMOS reset default of 1024Hz;
1051                  *
1052                  * REVISIT it's been reported that at least one x86_64 ALI
1053                  * mobo doesn't use 32KHz here ... for portability we might
1054                  * need to do something about other clock frequencies.
1055                  */
1056                 cmos_rtc.rtc->irq_freq = 1024;
1057                 if (use_hpet_alarm())
1058                         hpet_set_periodic_freq(cmos_rtc.rtc->irq_freq);
1059                 CMOS_WRITE(RTC_REF_CLCK_32KHZ | 0x06, RTC_FREQ_SELECT);
1060         }
1061
1062         /* disable irqs */
1063         if (is_valid_irq(rtc_irq))
1064                 cmos_irq_disable(&cmos_rtc, RTC_PIE | RTC_AIE | RTC_UIE);
1065
1066         rtc_control = CMOS_READ(RTC_CONTROL);
1067
1068         spin_unlock_irq(&rtc_lock);
1069
1070         if (is_valid_irq(rtc_irq) && !(rtc_control & RTC_24H)) {
1071                 dev_warn(dev, "only 24-hr supported\n");
1072                 retval = -ENXIO;
1073                 goto cleanup1;
1074         }
1075
1076         if (use_hpet_alarm())
1077                 hpet_rtc_timer_init();
1078
1079         if (is_valid_irq(rtc_irq)) {
1080                 irq_handler_t rtc_cmos_int_handler;
1081
1082                 if (use_hpet_alarm()) {
1083                         rtc_cmos_int_handler = hpet_rtc_interrupt;
1084                         retval = hpet_register_irq_handler(cmos_interrupt);
1085                         if (retval) {
1086                                 hpet_mask_rtc_irq_bit(RTC_IRQMASK);
1087                                 dev_warn(dev, "hpet_register_irq_handler "
1088                                                 " failed in rtc_init().");
1089                                 goto cleanup1;
1090                         }
1091                 } else
1092                         rtc_cmos_int_handler = cmos_interrupt;
1093
1094                 retval = request_irq(rtc_irq, rtc_cmos_int_handler,
1095                                 0, dev_name(&cmos_rtc.rtc->dev),
1096                                 cmos_rtc.rtc);
1097                 if (retval < 0) {
1098                         dev_dbg(dev, "IRQ %d is already in use\n", rtc_irq);
1099                         goto cleanup1;
1100                 }
1101         } else {
1102                 clear_bit(RTC_FEATURE_ALARM, cmos_rtc.rtc->features);
1103         }
1104
1105         cmos_rtc.rtc->ops = &cmos_rtc_ops;
1106
1107         retval = devm_rtc_register_device(cmos_rtc.rtc);
1108         if (retval)
1109                 goto cleanup2;
1110
1111         /* Set the sync offset for the periodic 11min update correct */
1112         cmos_rtc.rtc->set_offset_nsec = NSEC_PER_SEC / 2;
1113
1114         /* export at least the first block of NVRAM */
1115         nvmem_cfg.size = address_space - NVRAM_OFFSET;
1116         devm_rtc_nvmem_register(cmos_rtc.rtc, &nvmem_cfg);
1117
1118         /*
1119          * Everything has gone well so far, so by default register a handler for
1120          * the ACPI RTC fixed event.
1121          */
1122         if (!info)
1123                 acpi_rtc_event_setup(dev);
1124
1125         dev_info(dev, "%s%s, %d bytes nvram%s\n",
1126                  !is_valid_irq(rtc_irq) ? "no alarms" :
1127                  cmos_rtc.mon_alrm ? "alarms up to one year" :
1128                  cmos_rtc.day_alrm ? "alarms up to one month" :
1129                  "alarms up to one day",
1130                  cmos_rtc.century ? ", y3k" : "",
1131                  nvmem_cfg.size,
1132                  use_hpet_alarm() ? ", hpet irqs" : "");
1133
1134         return 0;
1135
1136 cleanup2:
1137         if (is_valid_irq(rtc_irq))
1138                 free_irq(rtc_irq, cmos_rtc.rtc);
1139 cleanup1:
1140         cmos_rtc.dev = NULL;
1141 cleanup0:
1142         if (RTC_IOMAPPED)
1143                 release_region(ports->start, resource_size(ports));
1144         else
1145                 release_mem_region(ports->start, resource_size(ports));
1146         return retval;
1147 }
1148
1149 static void cmos_do_shutdown(int rtc_irq)
1150 {
1151         spin_lock_irq(&rtc_lock);
1152         if (is_valid_irq(rtc_irq))
1153                 cmos_irq_disable(&cmos_rtc, RTC_IRQMASK);
1154         spin_unlock_irq(&rtc_lock);
1155 }
1156
1157 static void cmos_do_remove(struct device *dev)
1158 {
1159         struct cmos_rtc *cmos = dev_get_drvdata(dev);
1160         struct resource *ports;
1161
1162         cmos_do_shutdown(cmos->irq);
1163
1164         if (is_valid_irq(cmos->irq)) {
1165                 free_irq(cmos->irq, cmos->rtc);
1166                 if (use_hpet_alarm())
1167                         hpet_unregister_irq_handler(cmos_interrupt);
1168         }
1169
1170         if (!dev_get_platdata(dev))
1171                 acpi_rtc_event_cleanup();
1172
1173         cmos->rtc = NULL;
1174
1175         ports = cmos->iomem;
1176         if (RTC_IOMAPPED)
1177                 release_region(ports->start, resource_size(ports));
1178         else
1179                 release_mem_region(ports->start, resource_size(ports));
1180         cmos->iomem = NULL;
1181
1182         cmos->dev = NULL;
1183 }
1184
1185 static int cmos_aie_poweroff(struct device *dev)
1186 {
1187         struct cmos_rtc *cmos = dev_get_drvdata(dev);
1188         struct rtc_time now;
1189         time64_t t_now;
1190         int retval = 0;
1191         unsigned char rtc_control;
1192
1193         if (!cmos->alarm_expires)
1194                 return -EINVAL;
1195
1196         spin_lock_irq(&rtc_lock);
1197         rtc_control = CMOS_READ(RTC_CONTROL);
1198         spin_unlock_irq(&rtc_lock);
1199
1200         /* We only care about the situation where AIE is disabled. */
1201         if (rtc_control & RTC_AIE)
1202                 return -EBUSY;
1203
1204         cmos_read_time(dev, &now);
1205         t_now = rtc_tm_to_time64(&now);
1206
1207         /*
1208          * When enabling "RTC wake-up" in BIOS setup, the machine reboots
1209          * automatically right after shutdown on some buggy boxes.
1210          * This automatic rebooting issue won't happen when the alarm
1211          * time is larger than now+1 seconds.
1212          *
1213          * If the alarm time is equal to now+1 seconds, the issue can be
1214          * prevented by cancelling the alarm.
1215          */
1216         if (cmos->alarm_expires == t_now + 1) {
1217                 struct rtc_wkalrm alarm;
1218
1219                 /* Cancel the AIE timer by configuring the past time. */
1220                 rtc_time64_to_tm(t_now - 1, &alarm.time);
1221                 alarm.enabled = 0;
1222                 retval = cmos_set_alarm(dev, &alarm);
1223         } else if (cmos->alarm_expires > t_now + 1) {
1224                 retval = -EBUSY;
1225         }
1226
1227         return retval;
1228 }
1229
1230 static int cmos_suspend(struct device *dev)
1231 {
1232         struct cmos_rtc *cmos = dev_get_drvdata(dev);
1233         unsigned char   tmp;
1234
1235         /* only the alarm might be a wakeup event source */
1236         spin_lock_irq(&rtc_lock);
1237         cmos->suspend_ctrl = tmp = CMOS_READ(RTC_CONTROL);
1238         if (tmp & (RTC_PIE|RTC_AIE|RTC_UIE)) {
1239                 unsigned char   mask;
1240
1241                 if (device_may_wakeup(dev))
1242                         mask = RTC_IRQMASK & ~RTC_AIE;
1243                 else
1244                         mask = RTC_IRQMASK;
1245                 tmp &= ~mask;
1246                 CMOS_WRITE(tmp, RTC_CONTROL);
1247                 if (use_hpet_alarm())
1248                         hpet_mask_rtc_irq_bit(mask);
1249                 cmos_checkintr(cmos, tmp);
1250         }
1251         spin_unlock_irq(&rtc_lock);
1252
1253         if ((tmp & RTC_AIE) && !cmos_use_acpi_alarm()) {
1254                 cmos->enabled_wake = 1;
1255                 if (cmos->wake_on)
1256                         cmos->wake_on(dev);
1257                 else
1258                         enable_irq_wake(cmos->irq);
1259         }
1260
1261         memset(&cmos->saved_wkalrm, 0, sizeof(struct rtc_wkalrm));
1262         cmos_read_alarm(dev, &cmos->saved_wkalrm);
1263
1264         dev_dbg(dev, "suspend%s, ctrl %02x\n",
1265                         (tmp & RTC_AIE) ? ", alarm may wake" : "",
1266                         tmp);
1267
1268         return 0;
1269 }
1270
1271 /* We want RTC alarms to wake us from e.g. ACPI G2/S5 "soft off", even
1272  * after a detour through G3 "mechanical off", although the ACPI spec
1273  * says wakeup should only work from G1/S4 "hibernate".  To most users,
1274  * distinctions between S4 and S5 are pointless.  So when the hardware
1275  * allows, don't draw that distinction.
1276  */
1277 static inline int cmos_poweroff(struct device *dev)
1278 {
1279         if (!IS_ENABLED(CONFIG_PM))
1280                 return -ENOSYS;
1281
1282         return cmos_suspend(dev);
1283 }
1284
1285 static void cmos_check_wkalrm(struct device *dev)
1286 {
1287         struct cmos_rtc *cmos = dev_get_drvdata(dev);
1288         struct rtc_wkalrm current_alarm;
1289         time64_t t_now;
1290         time64_t t_current_expires;
1291         time64_t t_saved_expires;
1292         struct rtc_time now;
1293
1294         /* Check if we have RTC Alarm armed */
1295         if (!(cmos->suspend_ctrl & RTC_AIE))
1296                 return;
1297
1298         cmos_read_time(dev, &now);
1299         t_now = rtc_tm_to_time64(&now);
1300
1301         /*
1302          * ACPI RTC wake event is cleared after resume from STR,
1303          * ACK the rtc irq here
1304          */
1305         if (t_now >= cmos->alarm_expires && cmos_use_acpi_alarm()) {
1306                 local_irq_disable();
1307                 cmos_interrupt(0, (void *)cmos->rtc);
1308                 local_irq_enable();
1309                 return;
1310         }
1311
1312         memset(&current_alarm, 0, sizeof(struct rtc_wkalrm));
1313         cmos_read_alarm(dev, &current_alarm);
1314         t_current_expires = rtc_tm_to_time64(&current_alarm.time);
1315         t_saved_expires = rtc_tm_to_time64(&cmos->saved_wkalrm.time);
1316         if (t_current_expires != t_saved_expires ||
1317             cmos->saved_wkalrm.enabled != current_alarm.enabled) {
1318                 cmos_set_alarm(dev, &cmos->saved_wkalrm);
1319         }
1320 }
1321
1322 static int __maybe_unused cmos_resume(struct device *dev)
1323 {
1324         struct cmos_rtc *cmos = dev_get_drvdata(dev);
1325         unsigned char tmp;
1326
1327         if (cmos->enabled_wake && !cmos_use_acpi_alarm()) {
1328                 if (cmos->wake_off)
1329                         cmos->wake_off(dev);
1330                 else
1331                         disable_irq_wake(cmos->irq);
1332                 cmos->enabled_wake = 0;
1333         }
1334
1335         /* The BIOS might have changed the alarm, restore it */
1336         cmos_check_wkalrm(dev);
1337
1338         spin_lock_irq(&rtc_lock);
1339         tmp = cmos->suspend_ctrl;
1340         cmos->suspend_ctrl = 0;
1341         /* re-enable any irqs previously active */
1342         if (tmp & RTC_IRQMASK) {
1343                 unsigned char   mask;
1344
1345                 if (device_may_wakeup(dev) && use_hpet_alarm())
1346                         hpet_rtc_timer_init();
1347
1348                 do {
1349                         CMOS_WRITE(tmp, RTC_CONTROL);
1350                         if (use_hpet_alarm())
1351                                 hpet_set_rtc_irq_bit(tmp & RTC_IRQMASK);
1352
1353                         mask = CMOS_READ(RTC_INTR_FLAGS);
1354                         mask &= (tmp & RTC_IRQMASK) | RTC_IRQF;
1355                         if (!use_hpet_alarm() || !is_intr(mask))
1356                                 break;
1357
1358                         /* force one-shot behavior if HPET blocked
1359                          * the wake alarm's irq
1360                          */
1361                         rtc_update_irq(cmos->rtc, 1, mask);
1362                         tmp &= ~RTC_AIE;
1363                         hpet_mask_rtc_irq_bit(RTC_AIE);
1364                 } while (mask & RTC_AIE);
1365
1366                 if (tmp & RTC_AIE)
1367                         cmos_check_acpi_rtc_status(dev, &tmp);
1368         }
1369         spin_unlock_irq(&rtc_lock);
1370
1371         dev_dbg(dev, "resume, ctrl %02x\n", tmp);
1372
1373         return 0;
1374 }
1375
1376 static SIMPLE_DEV_PM_OPS(cmos_pm_ops, cmos_suspend, cmos_resume);
1377
1378 /*----------------------------------------------------------------*/
1379
1380 /* On non-x86 systems, a "CMOS" RTC lives most naturally on platform_bus.
1381  * ACPI systems always list these as PNPACPI devices, and pre-ACPI PCs
1382  * probably list them in similar PNPBIOS tables; so PNP is more common.
1383  *
1384  * We don't use legacy "poke at the hardware" probing.  Ancient PCs that
1385  * predate even PNPBIOS should set up platform_bus devices.
1386  */
1387
1388 #ifdef  CONFIG_PNP
1389
1390 #include <linux/pnp.h>
1391
1392 static int cmos_pnp_probe(struct pnp_dev *pnp, const struct pnp_device_id *id)
1393 {
1394         int irq;
1395
1396         if (pnp_port_start(pnp, 0) == 0x70 && !pnp_irq_valid(pnp, 0)) {
1397                 irq = 0;
1398 #ifdef CONFIG_X86
1399                 /* Some machines contain a PNP entry for the RTC, but
1400                  * don't define the IRQ. It should always be safe to
1401                  * hardcode it on systems with a legacy PIC.
1402                  */
1403                 if (nr_legacy_irqs())
1404                         irq = RTC_IRQ;
1405 #endif
1406         } else {
1407                 irq = pnp_irq(pnp, 0);
1408         }
1409
1410         return cmos_do_probe(&pnp->dev, pnp_get_resource(pnp, IORESOURCE_IO, 0), irq);
1411 }
1412
1413 static void cmos_pnp_remove(struct pnp_dev *pnp)
1414 {
1415         cmos_do_remove(&pnp->dev);
1416 }
1417
1418 static void cmos_pnp_shutdown(struct pnp_dev *pnp)
1419 {
1420         struct device *dev = &pnp->dev;
1421         struct cmos_rtc *cmos = dev_get_drvdata(dev);
1422
1423         if (system_state == SYSTEM_POWER_OFF) {
1424                 int retval = cmos_poweroff(dev);
1425
1426                 if (cmos_aie_poweroff(dev) < 0 && !retval)
1427                         return;
1428         }
1429
1430         cmos_do_shutdown(cmos->irq);
1431 }
1432
1433 static const struct pnp_device_id rtc_ids[] = {
1434         { .id = "PNP0b00", },
1435         { .id = "PNP0b01", },
1436         { .id = "PNP0b02", },
1437         { },
1438 };
1439 MODULE_DEVICE_TABLE(pnp, rtc_ids);
1440
1441 static struct pnp_driver cmos_pnp_driver = {
1442         .name           = driver_name,
1443         .id_table       = rtc_ids,
1444         .probe          = cmos_pnp_probe,
1445         .remove         = cmos_pnp_remove,
1446         .shutdown       = cmos_pnp_shutdown,
1447
1448         /* flag ensures resume() gets called, and stops syslog spam */
1449         .flags          = PNP_DRIVER_RES_DO_NOT_CHANGE,
1450         .driver         = {
1451                         .pm = &cmos_pm_ops,
1452         },
1453 };
1454
1455 #endif  /* CONFIG_PNP */
1456
1457 #ifdef CONFIG_OF
1458 static const struct of_device_id of_cmos_match[] = {
1459         {
1460                 .compatible = "motorola,mc146818",
1461         },
1462         { },
1463 };
1464 MODULE_DEVICE_TABLE(of, of_cmos_match);
1465
1466 static __init void cmos_of_init(struct platform_device *pdev)
1467 {
1468         struct device_node *node = pdev->dev.of_node;
1469         const __be32 *val;
1470
1471         if (!node)
1472                 return;
1473
1474         val = of_get_property(node, "ctrl-reg", NULL);
1475         if (val)
1476                 CMOS_WRITE(be32_to_cpup(val), RTC_CONTROL);
1477
1478         val = of_get_property(node, "freq-reg", NULL);
1479         if (val)
1480                 CMOS_WRITE(be32_to_cpup(val), RTC_FREQ_SELECT);
1481 }
1482 #else
1483 static inline void cmos_of_init(struct platform_device *pdev) {}
1484 #endif
1485 /*----------------------------------------------------------------*/
1486
1487 /* Platform setup should have set up an RTC device, when PNP is
1488  * unavailable ... this could happen even on (older) PCs.
1489  */
1490
1491 static int __init cmos_platform_probe(struct platform_device *pdev)
1492 {
1493         struct resource *resource;
1494         int irq;
1495
1496         cmos_of_init(pdev);
1497
1498         if (RTC_IOMAPPED)
1499                 resource = platform_get_resource(pdev, IORESOURCE_IO, 0);
1500         else
1501                 resource = platform_get_resource(pdev, IORESOURCE_MEM, 0);
1502         irq = platform_get_irq(pdev, 0);
1503         if (irq < 0)
1504                 irq = -1;
1505
1506         return cmos_do_probe(&pdev->dev, resource, irq);
1507 }
1508
1509 static void cmos_platform_remove(struct platform_device *pdev)
1510 {
1511         cmos_do_remove(&pdev->dev);
1512 }
1513
1514 static void cmos_platform_shutdown(struct platform_device *pdev)
1515 {
1516         struct device *dev = &pdev->dev;
1517         struct cmos_rtc *cmos = dev_get_drvdata(dev);
1518
1519         if (system_state == SYSTEM_POWER_OFF) {
1520                 int retval = cmos_poweroff(dev);
1521
1522                 if (cmos_aie_poweroff(dev) < 0 && !retval)
1523                         return;
1524         }
1525
1526         cmos_do_shutdown(cmos->irq);
1527 }
1528
1529 /* work with hotplug and coldplug */
1530 MODULE_ALIAS("platform:rtc_cmos");
1531
1532 static struct platform_driver cmos_platform_driver = {
1533         .remove_new     = cmos_platform_remove,
1534         .shutdown       = cmos_platform_shutdown,
1535         .driver = {
1536                 .name           = driver_name,
1537                 .pm             = &cmos_pm_ops,
1538                 .of_match_table = of_match_ptr(of_cmos_match),
1539         }
1540 };
1541
1542 #ifdef CONFIG_PNP
1543 static bool pnp_driver_registered;
1544 #endif
1545 static bool platform_driver_registered;
1546
1547 static int __init cmos_init(void)
1548 {
1549         int retval = 0;
1550
1551 #ifdef  CONFIG_PNP
1552         retval = pnp_register_driver(&cmos_pnp_driver);
1553         if (retval == 0)
1554                 pnp_driver_registered = true;
1555 #endif
1556
1557         if (!cmos_rtc.dev) {
1558                 retval = platform_driver_probe(&cmos_platform_driver,
1559                                                cmos_platform_probe);
1560                 if (retval == 0)
1561                         platform_driver_registered = true;
1562         }
1563
1564         if (retval == 0)
1565                 return 0;
1566
1567 #ifdef  CONFIG_PNP
1568         if (pnp_driver_registered)
1569                 pnp_unregister_driver(&cmos_pnp_driver);
1570 #endif
1571         return retval;
1572 }
1573 module_init(cmos_init);
1574
1575 static void __exit cmos_exit(void)
1576 {
1577 #ifdef  CONFIG_PNP
1578         if (pnp_driver_registered)
1579                 pnp_unregister_driver(&cmos_pnp_driver);
1580 #endif
1581         if (platform_driver_registered)
1582                 platform_driver_unregister(&cmos_platform_driver);
1583 }
1584 module_exit(cmos_exit);
1585
1586
1587 MODULE_AUTHOR("David Brownell");
1588 MODULE_DESCRIPTION("Driver for PC-style 'CMOS' RTCs");
1589 MODULE_LICENSE("GPL");