drivers/rtc/interface.c

   1 /*
   2  * RTC subsystem, interface functions
   3  *
   4  * Copyright (C) 2005 Tower Technologies
   5  * Author: Alessandro Zummo <a.zummo@towertech.it>
   6  *
   7  * based on arch/arm/common/rtctime.c
   8  *
   9  * This program is free software; you can redistribute it and/or modify
  10  * it under the terms of the GNU General Public License version 2 as
  11  * published by the Free Software Foundation.
  12 */
  13
  14 #include <linux/rtc.h>
  15 #include <linux/sched.h>
  16 #include <linux/module.h>
  17 #include <linux/log2.h>
  18 #include <linux/workqueue.h>
  19
  20 #define CREATE_TRACE_POINTS
  21 #include <trace/events/rtc.h>
  22
  23 static int rtc_timer_enqueue(struct rtc_device *rtc, struct rtc_timer *timer);
  24 static void rtc_timer_remove(struct rtc_device *rtc, struct rtc_timer *timer);
  25
  26 static void rtc_add_offset(struct rtc_device *rtc, struct rtc_time *tm)
  27 {
  28         time64_t secs;
  29
  30         if (!rtc->offset_secs)
  31                 return;
  32
  33         secs = rtc_tm_to_time64(tm);
  34
  35         /*
  36          * Since the reading time values from RTC device are always in the RTC
  37          * original valid range, but we need to skip the overlapped region
  38          * between expanded range and original range, which is no need to add
  39          * the offset.
  40          */
  41         if ((rtc->start_secs > rtc->range_min && secs >= rtc->start_secs) ||
  42             (rtc->start_secs < rtc->range_min &&
  43              secs <= (rtc->start_secs + rtc->range_max - rtc->range_min)))
  44                 return;
  45
  46         rtc_time64_to_tm(secs + rtc->offset_secs, tm);
  47 }
  48
  49 static void rtc_subtract_offset(struct rtc_device *rtc, struct rtc_time *tm)
  50 {
  51         time64_t secs;
  52
  53         if (!rtc->offset_secs)
  54                 return;
  55
  56         secs = rtc_tm_to_time64(tm);
  57
  58         /*
  59          * If the setting time values are in the valid range of RTC hardware
  60          * device, then no need to subtract the offset when setting time to RTC
  61          * device. Otherwise we need to subtract the offset to make the time
  62          * values are valid for RTC hardware device.
  63          */
  64         if (secs >= rtc->range_min && secs <= rtc->range_max)
  65                 return;
  66
  67         rtc_time64_to_tm(secs - rtc->offset_secs, tm);
  68 }
  69
  70 static int rtc_valid_range(struct rtc_device *rtc, struct rtc_time *tm)
  71 {
  72         if (rtc->range_min != rtc->range_max) {
  73                 time64_t time = rtc_tm_to_time64(tm);
  74                 time64_t range_min = rtc->set_start_time ? rtc->start_secs :
  75                         rtc->range_min;
  76                 time64_t range_max = rtc->set_start_time ?
  77                         (rtc->start_secs + rtc->range_max - rtc->range_min) :
  78                         rtc->range_max;
  79
  80                 if (time < range_min || time > range_max)
  81                         return -ERANGE;
  82         }
  83
  84         return 0;
  85 }
  86
  87 static int __rtc_read_time(struct rtc_device *rtc, struct rtc_time *tm)
  88 {
  89         int err;
  90         if (!rtc->ops)
  91                 err = -ENODEV;
  92         else if (!rtc->ops->read_time)
  93                 err = -EINVAL;
  94         else {
  95                 memset(tm, 0, sizeof(struct rtc_time));
  96                 err = rtc->ops->read_time(rtc->dev.parent, tm);
  97                 if (err < 0) {
  98                         dev_dbg(&rtc->dev, "read_time: fail to read: %d\n",
  99                                 err);
 100                         return err;
 101                 }
 102
 103                 rtc_add_offset(rtc, tm);
 104
 105                 err = rtc_valid_tm(tm);
 106                 if (err < 0)
 107                         dev_dbg(&rtc->dev, "read_time: rtc_time isn't valid\n");
 108         }
 109         return err;
 110 }
 111
 112 int rtc_read_time(struct rtc_device *rtc, struct rtc_time *tm)
 113 {
 114         int err;
 115
 116         err = mutex_lock_interruptible(&rtc->ops_lock);
 117         if (err)
 118                 return err;
 119
 120         err = __rtc_read_time(rtc, tm);
 121         mutex_unlock(&rtc->ops_lock);
 122
 123         trace_rtc_read_time(rtc_tm_to_time64(tm), err);
 124         return err;
 125 }
 126 EXPORT_SYMBOL_GPL(rtc_read_time);
 127
 128 int rtc_set_time(struct rtc_device *rtc, struct rtc_time *tm)
 129 {
 130         int err, uie;
 131
 132         err = rtc_valid_tm(tm);
 133         if (err != 0)
 134                 return err;
 135
 136         err = rtc_valid_range(rtc, tm);
 137         if (err)
 138                 return err;
 139
 140         rtc_subtract_offset(rtc, tm);
 141
 142 #ifdef CONFIG_RTC_INTF_DEV_UIE_EMUL
 143         uie = rtc->uie_rtctimer.enabled || rtc->uie_irq_active;
 144 #else
 145         uie = rtc->uie_rtctimer.enabled;
 146 #endif
 147         if (uie) {
 148                 err = rtc_update_irq_enable(rtc, 0);
 149                 if (err)
 150                         return err;
 151         }
 152
 153         err = mutex_lock_interruptible(&rtc->ops_lock);
 154         if (err)
 155                 return err;
 156
 157         if (!rtc->ops)
 158                 err = -ENODEV;
 159         else if (rtc->ops->set_time)
 160                 err = rtc->ops->set_time(rtc->dev.parent, tm);
 161         else if (rtc->ops->set_mmss64) {
 162                 time64_t secs64 = rtc_tm_to_time64(tm);
 163
 164                 err = rtc->ops->set_mmss64(rtc->dev.parent, secs64);
 165         } else if (rtc->ops->set_mmss) {
 166                 time64_t secs64 = rtc_tm_to_time64(tm);
 167                 err = rtc->ops->set_mmss(rtc->dev.parent, secs64);
 168         } else
 169                 err = -EINVAL;
 170
 171         pm_stay_awake(rtc->dev.parent);
 172         mutex_unlock(&rtc->ops_lock);
 173         /* A timer might have just expired */
 174         schedule_work(&rtc->irqwork);
 175
 176         if (uie) {
 177                 err = rtc_update_irq_enable(rtc, 1);
 178                 if (err)
 179                         return err;
 180         }
 181
 182         trace_rtc_set_time(rtc_tm_to_time64(tm), err);
 183         return err;
 184 }
 185 EXPORT_SYMBOL_GPL(rtc_set_time);
 186
 187 static int rtc_read_alarm_internal(struct rtc_device *rtc, struct rtc_wkalrm *alarm)
 188 {
 189         int err;
 190
 191         err = mutex_lock_interruptible(&rtc->ops_lock);
 192         if (err)
 193                 return err;
 194
 195         if (rtc->ops == NULL)
 196                 err = -ENODEV;
 197         else if (!rtc->ops->read_alarm)
 198                 err = -EINVAL;
 199         else {
 200                 alarm->enabled = 0;
 201                 alarm->pending = 0;
 202                 alarm->time.tm_sec = -1;
 203                 alarm->time.tm_min = -1;
 204                 alarm->time.tm_hour = -1;
 205                 alarm->time.tm_mday = -1;
 206                 alarm->time.tm_mon = -1;
 207                 alarm->time.tm_year = -1;
 208                 alarm->time.tm_wday = -1;
 209                 alarm->time.tm_yday = -1;
 210                 alarm->time.tm_isdst = -1;
 211                 err = rtc->ops->read_alarm(rtc->dev.parent, alarm);
 212         }
 213
 214         mutex_unlock(&rtc->ops_lock);
 215
 216         trace_rtc_read_alarm(rtc_tm_to_time64(&alarm->time), err);
 217         return err;
 218 }
 219
 220 int __rtc_read_alarm(struct rtc_device *rtc, struct rtc_wkalrm *alarm)
 221 {
 222         int err;
 223         struct rtc_time before, now;
 224         int first_time = 1;
 225         time64_t t_now, t_alm;
 226         enum { none, day, month, year } missing = none;
 227         unsigned days;
 228
 229         /* The lower level RTC driver may return -1 in some fields,
 230          * creating invalid alarm->time values, for reasons like:
 231          *
 232          *   - The hardware may not be capable of filling them in;
 233          *     many alarms match only on time-of-day fields, not
 234          *     day/month/year calendar data.
 235          *
 236          *   - Some hardware uses illegal values as "wildcard" match
 237          *     values, which non-Linux firmware (like a BIOS) may try
 238          *     to set up as e.g. "alarm 15 minutes after each hour".
 239          *     Linux uses only oneshot alarms.
 240          *
 241          * When we see that here, we deal with it by using values from
 242          * a current RTC timestamp for any missing (-1) values.  The
 243          * RTC driver prevents "periodic alarm" modes.
 244          *
 245          * But this can be racey, because some fields of the RTC timestamp
 246          * may have wrapped in the interval since we read the RTC alarm,
 247          * which would lead to us inserting inconsistent values in place
 248          * of the -1 fields.
 249          *
 250          * Reading the alarm and timestamp in the reverse sequence
 251          * would have the same race condition, and not solve the issue.
 252          *
 253          * So, we must first read the RTC timestamp,
 254          * then read the RTC alarm value,
 255          * and then read a second RTC timestamp.
 256          *
 257          * If any fields of the second timestamp have changed
 258          * when compared with the first timestamp, then we know
 259          * our timestamp may be inconsistent with that used by
 260          * the low-level rtc_read_alarm_internal() function.
 261          *
 262          * So, when the two timestamps disagree, we just loop and do
 263          * the process again to get a fully consistent set of values.
 264          *
 265          * This could all instead be done in the lower level driver,
 266          * but since more than one lower level RTC implementation needs it,
 267          * then it's probably best best to do it here instead of there..
 268          */
 269
 270         /* Get the "before" timestamp */
 271         err = rtc_read_time(rtc, &before);
 272         if (err < 0)
 273                 return err;
 274         do {
 275                 if (!first_time)
 276                         memcpy(&before, &now, sizeof(struct rtc_time));
 277                 first_time = 0;
 278
 279                 /* get the RTC alarm values, which may be incomplete */
 280                 err = rtc_read_alarm_internal(rtc, alarm);
 281                 if (err)
 282                         return err;
 283
 284                 /* full-function RTCs won't have such missing fields */
 285                 if (rtc_valid_tm(&alarm->time) == 0) {
 286                         rtc_add_offset(rtc, &alarm->time);
 287                         return 0;
 288                 }
 289
 290                 /* get the "after" timestamp, to detect wrapped fields */
 291                 err = rtc_read_time(rtc, &now);
 292                 if (err < 0)
 293                         return err;
 294
 295                 /* note that tm_sec is a "don't care" value here: */
 296         } while (   before.tm_min   != now.tm_min
 297                  || before.tm_hour  != now.tm_hour
 298                  || before.tm_mon   != now.tm_mon
 299                  || before.tm_year  != now.tm_year);
 300
 301         /* Fill in the missing alarm fields using the timestamp; we
 302          * know there's at least one since alarm->time is invalid.
 303          */
 304         if (alarm->time.tm_sec == -1)
 305                 alarm->time.tm_sec = now.tm_sec;
 306         if (alarm->time.tm_min == -1)
 307                 alarm->time.tm_min = now.tm_min;
 308         if (alarm->time.tm_hour == -1)
 309                 alarm->time.tm_hour = now.tm_hour;
 310
 311         /* For simplicity, only support date rollover for now */
 312         if (alarm->time.tm_mday < 1 || alarm->time.tm_mday > 31) {
 313                 alarm->time.tm_mday = now.tm_mday;
 314                 missing = day;
 315         }
 316         if ((unsigned)alarm->time.tm_mon >= 12) {
 317                 alarm->time.tm_mon = now.tm_mon;
 318                 if (missing == none)
 319                         missing = month;
 320         }
 321         if (alarm->time.tm_year == -1) {
 322                 alarm->time.tm_year = now.tm_year;
 323                 if (missing == none)
 324                         missing = year;
 325         }
 326
 327         /* Can't proceed if alarm is still invalid after replacing
 328          * missing fields.
 329          */
 330         err = rtc_valid_tm(&alarm->time);
 331         if (err)
 332                 goto done;
 333
 334         /* with luck, no rollover is needed */
 335         t_now = rtc_tm_to_time64(&now);
 336         t_alm = rtc_tm_to_time64(&alarm->time);
 337         if (t_now < t_alm)
 338                 goto done;
 339
 340         switch (missing) {
 341
 342         /* 24 hour rollover ... if it's now 10am Monday, an alarm that
 343          * that will trigger at 5am will do so at 5am Tuesday, which
 344          * could also be in the next month or year.  This is a common
 345          * case, especially for PCs.
 346          */
 347         case day:
 348                 dev_dbg(&rtc->dev, "alarm rollover: %s\n", "day");
 349                 t_alm += 24 * 60 * 60;
 350                 rtc_time64_to_tm(t_alm, &alarm->time);
 351                 break;
 352
 353         /* Month rollover ... if it's the 31th, an alarm on the 3rd will
 354          * be next month.  An alarm matching on the 30th, 29th, or 28th
 355          * may end up in the month after that!  Many newer PCs support
 356          * this type of alarm.
 357          */
 358         case month:
 359                 dev_dbg(&rtc->dev, "alarm rollover: %s\n", "month");
 360                 do {
 361                         if (alarm->time.tm_mon < 11)
 362                                 alarm->time.tm_mon++;
 363                         else {
 364                                 alarm->time.tm_mon = 0;
 365                                 alarm->time.tm_year++;
 366                         }
 367                         days = rtc_month_days(alarm->time.tm_mon,
 368                                         alarm->time.tm_year);
 369                 } while (days < alarm->time.tm_mday);
 370                 break;
 371
 372         /* Year rollover ... easy except for leap years! */
 373         case year:
 374                 dev_dbg(&rtc->dev, "alarm rollover: %s\n", "year");
 375                 do {
 376                         alarm->time.tm_year++;
 377                 } while (!is_leap_year(alarm->time.tm_year + 1900)
 378                         && rtc_valid_tm(&alarm->time) != 0);
 379                 break;
 380
 381         default:
 382                 dev_warn(&rtc->dev, "alarm rollover not handled\n");
 383         }
 384
 385         err = rtc_valid_tm(&alarm->time);
 386
 387 done:
 388         if (err) {
 389                 dev_warn(&rtc->dev, "invalid alarm value: %d-%d-%d %d:%d:%d\n",
 390                         alarm->time.tm_year + 1900, alarm->time.tm_mon + 1,
 391                         alarm->time.tm_mday, alarm->time.tm_hour, alarm->time.tm_min,
 392                         alarm->time.tm_sec);
 393         }
 394
 395         return err;
 396 }
 397
 398 int rtc_read_alarm(struct rtc_device *rtc, struct rtc_wkalrm *alarm)
 399 {
 400         int err;
 401
 402         err = mutex_lock_interruptible(&rtc->ops_lock);
 403         if (err)
 404                 return err;
 405         if (rtc->ops == NULL)
 406                 err = -ENODEV;
 407         else if (!rtc->ops->read_alarm)
 408                 err = -EINVAL;
 409         else {
 410                 memset(alarm, 0, sizeof(struct rtc_wkalrm));
 411                 alarm->enabled = rtc->aie_timer.enabled;
 412                 alarm->time = rtc_ktime_to_tm(rtc->aie_timer.node.expires);
 413         }
 414         mutex_unlock(&rtc->ops_lock);
 415
 416         trace_rtc_read_alarm(rtc_tm_to_time64(&alarm->time), err);
 417         return err;
 418 }
 419 EXPORT_SYMBOL_GPL(rtc_read_alarm);
 420
 421 static int __rtc_set_alarm(struct rtc_device *rtc, struct rtc_wkalrm *alarm)
 422 {
 423         struct rtc_time tm;
 424         time64_t now, scheduled;
 425         int err;
 426
 427         err = rtc_valid_tm(&alarm->time);
 428         if (err)
 429                 return err;
 430
 431         scheduled = rtc_tm_to_time64(&alarm->time);
 432
 433         /* Make sure we're not setting alarms in the past */
 434         err = __rtc_read_time(rtc, &tm);
 435         if (err)
 436                 return err;
 437         now = rtc_tm_to_time64(&tm);
 438         if (scheduled <= now)
 439                 return -ETIME;
 440         /*
 441          * XXX - We just checked to make sure the alarm time is not
 442          * in the past, but there is still a race window where if
 443          * the is alarm set for the next second and the second ticks
 444          * over right here, before we set the alarm.
 445          */
 446
 447         rtc_subtract_offset(rtc, &alarm->time);
 448
 449         if (!rtc->ops)
 450                 err = -ENODEV;
 451         else if (!rtc->ops->set_alarm)
 452                 err = -EINVAL;
 453         else
 454                 err = rtc->ops->set_alarm(rtc->dev.parent, alarm);
 455
 456         trace_rtc_set_alarm(rtc_tm_to_time64(&alarm->time), err);
 457         return err;
 458 }
 459
 460 int rtc_set_alarm(struct rtc_device *rtc, struct rtc_wkalrm *alarm)
 461 {
 462         int err;
 463
 464         if (!rtc->ops)
 465                 return -ENODEV;
 466         else if (!rtc->ops->set_alarm)
 467                 return -EINVAL;
 468
 469         err = rtc_valid_tm(&alarm->time);
 470         if (err != 0)
 471                 return err;
 472
 473         err = rtc_valid_range(rtc, &alarm->time);
 474         if (err)
 475                 return err;
 476
 477         err = mutex_lock_interruptible(&rtc->ops_lock);
 478         if (err)
 479                 return err;
 480         if (rtc->aie_timer.enabled)
 481                 rtc_timer_remove(rtc, &rtc->aie_timer);
 482
 483         rtc->aie_timer.node.expires = rtc_tm_to_ktime(alarm->time);
 484         rtc->aie_timer.period = 0;
 485         if (alarm->enabled)
 486                 err = rtc_timer_enqueue(rtc, &rtc->aie_timer);
 487
 488         mutex_unlock(&rtc->ops_lock);
 489
 490         return err;
 491 }
 492 EXPORT_SYMBOL_GPL(rtc_set_alarm);
 493
 494 /* Called once per device from rtc_device_register */
 495 int rtc_initialize_alarm(struct rtc_device *rtc, struct rtc_wkalrm *alarm)
 496 {
 497         int err;
 498         struct rtc_time now;
 499
 500         err = rtc_valid_tm(&alarm->time);
 501         if (err != 0)
 502                 return err;
 503
 504         err = rtc_read_time(rtc, &now);
 505         if (err)
 506                 return err;
 507
 508         err = mutex_lock_interruptible(&rtc->ops_lock);
 509         if (err)
 510                 return err;
 511
 512         rtc->aie_timer.node.expires = rtc_tm_to_ktime(alarm->time);
 513         rtc->aie_timer.period = 0;
 514
 515         /* Alarm has to be enabled & in the future for us to enqueue it */
 516         if (alarm->enabled && (rtc_tm_to_ktime(now) <
 517                          rtc->aie_timer.node.expires)) {
 518
 519                 rtc->aie_timer.enabled = 1;
 520                 timerqueue_add(&rtc->timerqueue, &rtc->aie_timer.node);
 521                 trace_rtc_timer_enqueue(&rtc->aie_timer);
 522         }
 523         mutex_unlock(&rtc->ops_lock);
 524         return err;
 525 }
 526 EXPORT_SYMBOL_GPL(rtc_initialize_alarm);
 527
 528 int rtc_alarm_irq_enable(struct rtc_device *rtc, unsigned int enabled)
 529 {
 530         int err = mutex_lock_interruptible(&rtc->ops_lock);
 531         if (err)
 532                 return err;
 533
 534         if (rtc->aie_timer.enabled != enabled) {
 535                 if (enabled)
 536                         err = rtc_timer_enqueue(rtc, &rtc->aie_timer);
 537                 else
 538                         rtc_timer_remove(rtc, &rtc->aie_timer);
 539         }
 540
 541         if (err)
 542                 /* nothing */;
 543         else if (!rtc->ops)
 544                 err = -ENODEV;
 545         else if (!rtc->ops->alarm_irq_enable)
 546                 err = -EINVAL;
 547         else
 548                 err = rtc->ops->alarm_irq_enable(rtc->dev.parent, enabled);
 549
 550         mutex_unlock(&rtc->ops_lock);
 551
 552         trace_rtc_alarm_irq_enable(enabled, err);
 553         return err;
 554 }
 555 EXPORT_SYMBOL_GPL(rtc_alarm_irq_enable);
 556
 557 int rtc_update_irq_enable(struct rtc_device *rtc, unsigned int enabled)
 558 {
 559         int err = mutex_lock_interruptible(&rtc->ops_lock);
 560         if (err)
 561                 return err;
 562
 563 #ifdef CONFIG_RTC_INTF_DEV_UIE_EMUL
 564         if (enabled == 0 && rtc->uie_irq_active) {
 565                 mutex_unlock(&rtc->ops_lock);
 566                 return rtc_dev_update_irq_enable_emul(rtc, 0);
 567         }
 568 #endif
 569         /* make sure we're changing state */
 570         if (rtc->uie_rtctimer.enabled == enabled)
 571                 goto out;
 572
 573         if (rtc->uie_unsupported) {
 574                 err = -EINVAL;
 575                 goto out;
 576         }
 577
 578         if (enabled) {
 579                 struct rtc_time tm;
 580                 ktime_t now, onesec;
 581
 582                 __rtc_read_time(rtc, &tm);
 583                 onesec = ktime_set(1, 0);
 584                 now = rtc_tm_to_ktime(tm);
 585                 rtc->uie_rtctimer.node.expires = ktime_add(now, onesec);
 586                 rtc->uie_rtctimer.period = ktime_set(1, 0);
 587                 err = rtc_timer_enqueue(rtc, &rtc->uie_rtctimer);
 588         } else
 589                 rtc_timer_remove(rtc, &rtc->uie_rtctimer);
 590
 591 out:
 592         mutex_unlock(&rtc->ops_lock);
 593 #ifdef CONFIG_RTC_INTF_DEV_UIE_EMUL
 594         /*
 595          * Enable emulation if the driver did not provide
 596          * the update_irq_enable function pointer or if returned
 597          * -EINVAL to signal that it has been configured without
 598          * interrupts or that are not available at the moment.
 599          */
 600         if (err == -EINVAL)
 601                 err = rtc_dev_update_irq_enable_emul(rtc, enabled);
 602 #endif
 603         return err;
 604
 605 }
 606 EXPORT_SYMBOL_GPL(rtc_update_irq_enable);
 607
 608
 609 /**
 610  * rtc_handle_legacy_irq - AIE, UIE and PIE event hook
 611  * @rtc: pointer to the rtc device
 612  *
 613  * This function is called when an AIE, UIE or PIE mode interrupt
 614  * has occurred (or been emulated).
 615  *
 616  * Triggers the registered irq_task function callback.
 617  */
 618 void rtc_handle_legacy_irq(struct rtc_device *rtc, int num, int mode)
 619 {
 620         unsigned long flags;
 621
 622         /* mark one irq of the appropriate mode */
 623         spin_lock_irqsave(&rtc->irq_lock, flags);
 624         rtc->irq_data = (rtc->irq_data + (num << 8)) | (RTC_IRQF|mode);
 625         spin_unlock_irqrestore(&rtc->irq_lock, flags);
 626
 627         wake_up_interruptible(&rtc->irq_queue);
 628         kill_fasync(&rtc->async_queue, SIGIO, POLL_IN);
 629 }
 630
 631
 632 /**
 633  * rtc_aie_update_irq - AIE mode rtctimer hook
 634  * @private: pointer to the rtc_device
 635  *
 636  * This functions is called when the aie_timer expires.
 637  */
 638 void rtc_aie_update_irq(void *private)
 639 {
 640         struct rtc_device *rtc = (struct rtc_device *)private;
 641         rtc_handle_legacy_irq(rtc, 1, RTC_AF);
 642 }
 643
 644
 645 /**
 646  * rtc_uie_update_irq - UIE mode rtctimer hook
 647  * @private: pointer to the rtc_device
 648  *
 649  * This functions is called when the uie_timer expires.
 650  */
 651 void rtc_uie_update_irq(void *private)
 652 {
 653         struct rtc_device *rtc = (struct rtc_device *)private;
 654         rtc_handle_legacy_irq(rtc, 1,  RTC_UF);
 655 }
 656
 657
 658 /**
 659  * rtc_pie_update_irq - PIE mode hrtimer hook
 660  * @timer: pointer to the pie mode hrtimer
 661  *
 662  * This function is used to emulate PIE mode interrupts
 663  * using an hrtimer. This function is called when the periodic
 664  * hrtimer expires.
 665  */
 666 enum hrtimer_restart rtc_pie_update_irq(struct hrtimer *timer)
 667 {
 668         struct rtc_device *rtc;
 669         ktime_t period;
 670         int count;
 671         rtc = container_of(timer, struct rtc_device, pie_timer);
 672
 673         period = NSEC_PER_SEC / rtc->irq_freq;
 674         count = hrtimer_forward_now(timer, period);
 675
 676         rtc_handle_legacy_irq(rtc, count, RTC_PF);
 677
 678         return HRTIMER_RESTART;
 679 }
 680
 681 /**
 682  * rtc_update_irq - Triggered when a RTC interrupt occurs.
 683  * @rtc: the rtc device
 684  * @num: how many irqs are being reported (usually one)
 685  * @events: mask of RTC_IRQF with one or more of RTC_PF, RTC_AF, RTC_UF
 686  * Context: any
 687  */
 688 void rtc_update_irq(struct rtc_device *rtc,
 689                 unsigned long num, unsigned long events)
 690 {
 691         if (IS_ERR_OR_NULL(rtc))
 692                 return;
 693
 694         pm_stay_awake(rtc->dev.parent);
 695         schedule_work(&rtc->irqwork);
 696 }
 697 EXPORT_SYMBOL_GPL(rtc_update_irq);
 698
 699 static int __rtc_match(struct device *dev, const void *data)
 700 {
 701         const char *name = data;
 702
 703         if (strcmp(dev_name(dev), name) == 0)
 704                 return 1;
 705         return 0;
 706 }
 707
 708 struct rtc_device *rtc_class_open(const char *name)
 709 {
 710         struct device *dev;
 711         struct rtc_device *rtc = NULL;
 712
 713         dev = class_find_device(rtc_class, NULL, name, __rtc_match);
 714         if (dev)
 715                 rtc = to_rtc_device(dev);
 716
 717         if (rtc) {
 718                 if (!try_module_get(rtc->owner)) {
 719                         put_device(dev);
 720                         rtc = NULL;
 721                 }
 722         }
 723
 724         return rtc;
 725 }
 726 EXPORT_SYMBOL_GPL(rtc_class_open);
 727
 728 void rtc_class_close(struct rtc_device *rtc)
 729 {
 730         module_put(rtc->owner);
 731         put_device(&rtc->dev);
 732 }
 733 EXPORT_SYMBOL_GPL(rtc_class_close);
 734
 735 static int rtc_update_hrtimer(struct rtc_device *rtc, int enabled)
 736 {
 737         /*
 738          * We always cancel the timer here first, because otherwise
 739          * we could run into BUG_ON(timer->state != HRTIMER_STATE_CALLBACK);
 740          * when we manage to start the timer before the callback
 741          * returns HRTIMER_RESTART.
 742          *
 743          * We cannot use hrtimer_cancel() here as a running callback
 744          * could be blocked on rtc->irq_task_lock and hrtimer_cancel()
 745          * would spin forever.
 746          */
 747         if (hrtimer_try_to_cancel(&rtc->pie_timer) < 0)
 748                 return -1;
 749
 750         if (enabled) {
 751                 ktime_t period = NSEC_PER_SEC / rtc->irq_freq;
 752
 753                 hrtimer_start(&rtc->pie_timer, period, HRTIMER_MODE_REL);
 754         }
 755         return 0;
 756 }
 757
 758 /**
 759  * rtc_irq_set_state - enable/disable 2^N Hz periodic IRQs
 760  * @rtc: the rtc device
 761  * @task: currently registered with rtc_irq_register()
 762  * @enabled: true to enable periodic IRQs
 763  * Context: any
 764  *
 765  * Note that rtc_irq_set_freq() should previously have been used to
 766  * specify the desired frequency of periodic IRQ.
 767  */
 768 int rtc_irq_set_state(struct rtc_device *rtc, int enabled)
 769 {
 770         int err = 0;
 771
 772         while (rtc_update_hrtimer(rtc, enabled) < 0)
 773                 cpu_relax();
 774
 775         rtc->pie_enabled = enabled;
 776
 777         trace_rtc_irq_set_state(enabled, err);
 778         return err;
 779 }
 780
 781 /**
 782  * rtc_irq_set_freq - set 2^N Hz periodic IRQ frequency for IRQ
 783  * @rtc: the rtc device
 784  * @task: currently registered with rtc_irq_register()
 785  * @freq: positive frequency
 786  * Context: any
 787  *
 788  * Note that rtc_irq_set_state() is used to enable or disable the
 789  * periodic IRQs.
 790  */
 791 int rtc_irq_set_freq(struct rtc_device *rtc, int freq)
 792 {
 793         int err = 0;
 794
 795         if (freq <= 0 || freq > RTC_MAX_FREQ)
 796                 return -EINVAL;
 797
 798         rtc->irq_freq = freq;
 799         while (rtc->pie_enabled && rtc_update_hrtimer(rtc, 1) < 0)
 800                 cpu_relax();
 801
 802         trace_rtc_irq_set_freq(freq, err);
 803         return err;
 804 }
 805
 806 /**
 807  * rtc_timer_enqueue - Adds a rtc_timer to the rtc_device timerqueue
 808  * @rtc rtc device
 809  * @timer timer being added.
 810  *
 811  * Enqueues a timer onto the rtc devices timerqueue and sets
 812  * the next alarm event appropriately.
 813  *
 814  * Sets the enabled bit on the added timer.
 815  *
 816  * Must hold ops_lock for proper serialization of timerqueue
 817  */
 818 static int rtc_timer_enqueue(struct rtc_device *rtc, struct rtc_timer *timer)
 819 {
 820         struct timerqueue_node *next = timerqueue_getnext(&rtc->timerqueue);
 821         struct rtc_time tm;
 822         ktime_t now;
 823
 824         timer->enabled = 1;
 825         __rtc_read_time(rtc, &tm);
 826         now = rtc_tm_to_ktime(tm);
 827
 828         /* Skip over expired timers */
 829         while (next) {
 830                 if (next->expires >= now)
 831                         break;
 832                 next = timerqueue_iterate_next(next);
 833         }
 834
 835         timerqueue_add(&rtc->timerqueue, &timer->node);
 836         trace_rtc_timer_enqueue(timer);
 837         if (!next || ktime_before(timer->node.expires, next->expires)) {
 838                 struct rtc_wkalrm alarm;
 839                 int err;
 840                 alarm.time = rtc_ktime_to_tm(timer->node.expires);
 841                 alarm.enabled = 1;
 842                 err = __rtc_set_alarm(rtc, &alarm);
 843                 if (err == -ETIME) {
 844                         pm_stay_awake(rtc->dev.parent);
 845                         schedule_work(&rtc->irqwork);
 846                 } else if (err) {
 847                         timerqueue_del(&rtc->timerqueue, &timer->node);
 848                         trace_rtc_timer_dequeue(timer);
 849                         timer->enabled = 0;
 850                         return err;
 851                 }
 852         }
 853         return 0;
 854 }
 855
 856 static void rtc_alarm_disable(struct rtc_device *rtc)
 857 {
 858         if (!rtc->ops || !rtc->ops->alarm_irq_enable)
 859                 return;
 860
 861         rtc->ops->alarm_irq_enable(rtc->dev.parent, false);
 862         trace_rtc_alarm_irq_enable(0, 0);
 863 }
 864
 865 /**
 866  * rtc_timer_remove - Removes a rtc_timer from the rtc_device timerqueue
 867  * @rtc rtc device
 868  * @timer timer being removed.
 869  *
 870  * Removes a timer onto the rtc devices timerqueue and sets
 871  * the next alarm event appropriately.
 872  *
 873  * Clears the enabled bit on the removed timer.
 874  *
 875  * Must hold ops_lock for proper serialization of timerqueue
 876  */
 877 static void rtc_timer_remove(struct rtc_device *rtc, struct rtc_timer *timer)
 878 {
 879         struct timerqueue_node *next = timerqueue_getnext(&rtc->timerqueue);
 880         timerqueue_del(&rtc->timerqueue, &timer->node);
 881         trace_rtc_timer_dequeue(timer);
 882         timer->enabled = 0;
 883         if (next == &timer->node) {
 884                 struct rtc_wkalrm alarm;
 885                 int err;
 886                 next = timerqueue_getnext(&rtc->timerqueue);
 887                 if (!next) {
 888                         rtc_alarm_disable(rtc);
 889                         return;
 890                 }
 891                 alarm.time = rtc_ktime_to_tm(next->expires);
 892                 alarm.enabled = 1;
 893                 err = __rtc_set_alarm(rtc, &alarm);
 894                 if (err == -ETIME) {
 895                         pm_stay_awake(rtc->dev.parent);
 896                         schedule_work(&rtc->irqwork);
 897                 }
 898         }
 899 }
 900
 901 /**
 902  * rtc_timer_do_work - Expires rtc timers
 903  * @rtc rtc device
 904  * @timer timer being removed.
 905  *
 906  * Expires rtc timers. Reprograms next alarm event if needed.
 907  * Called via worktask.
 908  *
 909  * Serializes access to timerqueue via ops_lock mutex
 910  */
 911 void rtc_timer_do_work(struct work_struct *work)
 912 {
 913         struct rtc_timer *timer;
 914         struct timerqueue_node *next;
 915         ktime_t now;
 916         struct rtc_time tm;
 917
 918         struct rtc_device *rtc =
 919                 container_of(work, struct rtc_device, irqwork);
 920
 921         mutex_lock(&rtc->ops_lock);
 922 again:
 923         __rtc_read_time(rtc, &tm);
 924         now = rtc_tm_to_ktime(tm);
 925         while ((next = timerqueue_getnext(&rtc->timerqueue))) {
 926                 if (next->expires > now)
 927                         break;
 928
 929                 /* expire timer */
 930                 timer = container_of(next, struct rtc_timer, node);
 931                 timerqueue_del(&rtc->timerqueue, &timer->node);
 932                 trace_rtc_timer_dequeue(timer);
 933                 timer->enabled = 0;
 934                 if (timer->func)
 935                         timer->func(timer->private_data);
 936
 937                 trace_rtc_timer_fired(timer);
 938                 /* Re-add/fwd periodic timers */
 939                 if (ktime_to_ns(timer->period)) {
 940                         timer->node.expires = ktime_add(timer->node.expires,
 941                                                         timer->period);
 942                         timer->enabled = 1;
 943                         timerqueue_add(&rtc->timerqueue, &timer->node);
 944                         trace_rtc_timer_enqueue(timer);
 945                 }
 946         }
 947
 948         /* Set next alarm */
 949         if (next) {
 950                 struct rtc_wkalrm alarm;
 951                 int err;
 952                 int retry = 3;
 953
 954                 alarm.time = rtc_ktime_to_tm(next->expires);
 955                 alarm.enabled = 1;
 956 reprogram:
 957                 err = __rtc_set_alarm(rtc, &alarm);
 958                 if (err == -ETIME)
 959                         goto again;
 960                 else if (err) {
 961                         if (retry-- > 0)
 962                                 goto reprogram;
 963
 964                         timer = container_of(next, struct rtc_timer, node);
 965                         timerqueue_del(&rtc->timerqueue, &timer->node);
 966                         trace_rtc_timer_dequeue(timer);
 967                         timer->enabled = 0;
 968                         dev_err(&rtc->dev, "__rtc_set_alarm: err=%d\n", err);
 969                         goto again;
 970                 }
 971         } else
 972                 rtc_alarm_disable(rtc);
 973
 974         pm_relax(rtc->dev.parent);
 975         mutex_unlock(&rtc->ops_lock);
 976 }
 977
 978
 979 /* rtc_timer_init - Initializes an rtc_timer
 980  * @timer: timer to be intiialized
 981  * @f: function pointer to be called when timer fires
 982  * @data: private data passed to function pointer
 983  *
 984  * Kernel interface to initializing an rtc_timer.
 985  */
 986 void rtc_timer_init(struct rtc_timer *timer, void (*f)(void *p), void *data)
 987 {
 988         timerqueue_init(&timer->node);
 989         timer->enabled = 0;
 990         timer->func = f;
 991         timer->private_data = data;
 992 }
 993
 994 /* rtc_timer_start - Sets an rtc_timer to fire in the future
 995  * @ rtc: rtc device to be used
 996  * @ timer: timer being set
 997  * @ expires: time at which to expire the timer
 998  * @ period: period that the timer will recur
 999  *
1000  * Kernel interface to set an rtc_timer
1001  */
1002 int rtc_timer_start(struct rtc_device *rtc, struct rtc_timer *timer,
1003                         ktime_t expires, ktime_t period)
1004 {
1005         int ret = 0;
1006         mutex_lock(&rtc->ops_lock);
1007         if (timer->enabled)
1008                 rtc_timer_remove(rtc, timer);
1009
1010         timer->node.expires = expires;
1011         timer->period = period;
1012
1013         ret = rtc_timer_enqueue(rtc, timer);
1014
1015         mutex_unlock(&rtc->ops_lock);
1016         return ret;
1017 }
1018
1019 /* rtc_timer_cancel - Stops an rtc_timer
1020  * @ rtc: rtc device to be used
1021  * @ timer: timer being set
1022  *
1023  * Kernel interface to cancel an rtc_timer
1024  */
1025 void rtc_timer_cancel(struct rtc_device *rtc, struct rtc_timer *timer)
1026 {
1027         mutex_lock(&rtc->ops_lock);
1028         if (timer->enabled)
1029                 rtc_timer_remove(rtc, timer);
1030         mutex_unlock(&rtc->ops_lock);
1031 }
1032
1033 /**
1034  * rtc_read_offset - Read the amount of rtc offset in parts per billion
1035  * @ rtc: rtc device to be used
1036  * @ offset: the offset in parts per billion
1037  *
1038  * see below for details.
1039  *
1040  * Kernel interface to read rtc clock offset
1041  * Returns 0 on success, or a negative number on error.
1042  * If read_offset() is not implemented for the rtc, return -EINVAL
1043  */
1044 int rtc_read_offset(struct rtc_device *rtc, long *offset)
1045 {
1046         int ret;
1047
1048         if (!rtc->ops)
1049                 return -ENODEV;
1050
1051         if (!rtc->ops->read_offset)
1052                 return -EINVAL;
1053
1054         mutex_lock(&rtc->ops_lock);
1055         ret = rtc->ops->read_offset(rtc->dev.parent, offset);
1056         mutex_unlock(&rtc->ops_lock);
1057
1058         trace_rtc_read_offset(*offset, ret);
1059         return ret;
1060 }
1061
1062 /**
1063  * rtc_set_offset - Adjusts the duration of the average second
1064  * @ rtc: rtc device to be used
1065  * @ offset: the offset in parts per billion
1066  *
1067  * Some rtc's allow an adjustment to the average duration of a second
1068  * to compensate for differences in the actual clock rate due to temperature,
1069  * the crystal, capacitor, etc.
1070  *
1071  * The adjustment applied is as follows:
1072  *   t = t0 * (1 + offset * 1e-9)
1073  * where t0 is the measured length of 1 RTC second with offset = 0
1074  *
1075  * Kernel interface to adjust an rtc clock offset.
1076  * Return 0 on success, or a negative number on error.
1077  * If the rtc offset is not setable (or not implemented), return -EINVAL
1078  */
1079 int rtc_set_offset(struct rtc_device *rtc, long offset)
1080 {
1081         int ret;
1082
1083         if (!rtc->ops)
1084                 return -ENODEV;
1085
1086         if (!rtc->ops->set_offset)
1087                 return -EINVAL;
1088
1089         mutex_lock(&rtc->ops_lock);
1090         ret = rtc->ops->set_offset(rtc->dev.parent, offset);
1091         mutex_unlock(&rtc->ops_lock);
1092
1093         trace_rtc_set_offset(offset, ret);
1094         return ret;
1095 }