drivers/rtc/interface.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * RTC subsystem, interface functions
   4  *
   5  * Copyright (C) 2005 Tower Technologies
   6  * Author: Alessandro Zummo <a.zummo@towertech.it>
   7  *
   8  * based on arch/arm/common/rtctime.c
   9  */
  10
  11 #include <linux/rtc.h>
  12 #include <linux/sched.h>
  13 #include <linux/module.h>
  14 #include <linux/log2.h>
  15 #include <linux/workqueue.h>
  16
  17 #define CREATE_TRACE_POINTS
  18 #include <trace/events/rtc.h>
  19
  20 static int rtc_timer_enqueue(struct rtc_device *rtc, struct rtc_timer *timer);
  21 static void rtc_timer_remove(struct rtc_device *rtc, struct rtc_timer *timer);
  22
  23 static void rtc_add_offset(struct rtc_device *rtc, struct rtc_time *tm)
  24 {
  25         time64_t secs;
  26
  27         if (!rtc->offset_secs)
  28                 return;
  29
  30         secs = rtc_tm_to_time64(tm);
  31
  32         /*
  33          * Since the reading time values from RTC device are always in the RTC
  34          * original valid range, but we need to skip the overlapped region
  35          * between expanded range and original range, which is no need to add
  36          * the offset.
  37          */
  38         if ((rtc->start_secs > rtc->range_min && secs >= rtc->start_secs) ||
  39             (rtc->start_secs < rtc->range_min &&
  40              secs <= (rtc->start_secs + rtc->range_max - rtc->range_min)))
  41                 return;
  42
  43         rtc_time64_to_tm(secs + rtc->offset_secs, tm);
  44 }
  45
  46 static void rtc_subtract_offset(struct rtc_device *rtc, struct rtc_time *tm)
  47 {
  48         time64_t secs;
  49
  50         if (!rtc->offset_secs)
  51                 return;
  52
  53         secs = rtc_tm_to_time64(tm);
  54
  55         /*
  56          * If the setting time values are in the valid range of RTC hardware
  57          * device, then no need to subtract the offset when setting time to RTC
  58          * device. Otherwise we need to subtract the offset to make the time
  59          * values are valid for RTC hardware device.
  60          */
  61         if (secs >= rtc->range_min && secs <= rtc->range_max)
  62                 return;
  63
  64         rtc_time64_to_tm(secs - rtc->offset_secs, tm);
  65 }
  66
  67 static int rtc_valid_range(struct rtc_device *rtc, struct rtc_time *tm)
  68 {
  69         if (rtc->range_min != rtc->range_max) {
  70                 time64_t time = rtc_tm_to_time64(tm);
  71                 time64_t range_min = rtc->set_start_time ? rtc->start_secs :
  72                         rtc->range_min;
  73                 timeu64_t range_max = rtc->set_start_time ?
  74                         (rtc->start_secs + rtc->range_max - rtc->range_min) :
  75                         rtc->range_max;
  76
  77                 if (time < range_min || time > range_max)
  78                         return -ERANGE;
  79         }
  80
  81         return 0;
  82 }
  83
  84 static int __rtc_read_time(struct rtc_device *rtc, struct rtc_time *tm)
  85 {
  86         int err;
  87
  88         if (!rtc->ops) {
  89                 err = -ENODEV;
  90         } else if (!rtc->ops->read_time) {
  91                 err = -EINVAL;
  92         } else {
  93                 memset(tm, 0, sizeof(struct rtc_time));
  94                 err = rtc->ops->read_time(rtc->dev.parent, tm);
  95                 if (err < 0) {
  96                         dev_dbg(&rtc->dev, "read_time: fail to read: %d\n",
  97                                 err);
  98                         return err;
  99                 }
 100
 101                 rtc_add_offset(rtc, tm);
 102
 103                 err = rtc_valid_tm(tm);
 104                 if (err < 0)
 105                         dev_dbg(&rtc->dev, "read_time: rtc_time isn't valid\n");
 106         }
 107         return err;
 108 }
 109
 110 int rtc_read_time(struct rtc_device *rtc, struct rtc_time *tm)
 111 {
 112         int err;
 113
 114         err = mutex_lock_interruptible(&rtc->ops_lock);
 115         if (err)
 116                 return err;
 117
 118         err = __rtc_read_time(rtc, tm);
 119         mutex_unlock(&rtc->ops_lock);
 120
 121         trace_rtc_read_time(rtc_tm_to_time64(tm), err);
 122         return err;
 123 }
 124 EXPORT_SYMBOL_GPL(rtc_read_time);
 125
 126 int rtc_set_time(struct rtc_device *rtc, struct rtc_time *tm)
 127 {
 128         int err, uie;
 129
 130         err = rtc_valid_tm(tm);
 131         if (err != 0)
 132                 return err;
 133
 134         err = rtc_valid_range(rtc, tm);
 135         if (err)
 136                 return err;
 137
 138         rtc_subtract_offset(rtc, tm);
 139
 140 #ifdef CONFIG_RTC_INTF_DEV_UIE_EMUL
 141         uie = rtc->uie_rtctimer.enabled || rtc->uie_irq_active;
 142 #else
 143         uie = rtc->uie_rtctimer.enabled;
 144 #endif
 145         if (uie) {
 146                 err = rtc_update_irq_enable(rtc, 0);
 147                 if (err)
 148                         return err;
 149         }
 150
 151         err = mutex_lock_interruptible(&rtc->ops_lock);
 152         if (err)
 153                 return err;
 154
 155         if (!rtc->ops)
 156                 err = -ENODEV;
 157         else if (rtc->ops->set_time)
 158                 err = rtc->ops->set_time(rtc->dev.parent, tm);
 159         else
 160                 err = -EINVAL;
 161
 162         pm_stay_awake(rtc->dev.parent);
 163         mutex_unlock(&rtc->ops_lock);
 164         /* A timer might have just expired */
 165         schedule_work(&rtc->irqwork);
 166
 167         if (uie) {
 168                 err = rtc_update_irq_enable(rtc, 1);
 169                 if (err)
 170                         return err;
 171         }
 172
 173         trace_rtc_set_time(rtc_tm_to_time64(tm), err);
 174         return err;
 175 }
 176 EXPORT_SYMBOL_GPL(rtc_set_time);
 177
 178 static int rtc_read_alarm_internal(struct rtc_device *rtc,
 179                                    struct rtc_wkalrm *alarm)
 180 {
 181         int err;
 182
 183         err = mutex_lock_interruptible(&rtc->ops_lock);
 184         if (err)
 185                 return err;
 186
 187         if (!rtc->ops) {
 188                 err = -ENODEV;
 189         } else if (!test_bit(RTC_FEATURE_ALARM, rtc->features) || !rtc->ops->read_alarm) {
 190                 err = -EINVAL;
 191         } else {
 192                 alarm->enabled = 0;
 193                 alarm->pending = 0;
 194                 alarm->time.tm_sec = -1;
 195                 alarm->time.tm_min = -1;
 196                 alarm->time.tm_hour = -1;
 197                 alarm->time.tm_mday = -1;
 198                 alarm->time.tm_mon = -1;
 199                 alarm->time.tm_year = -1;
 200                 alarm->time.tm_wday = -1;
 201                 alarm->time.tm_yday = -1;
 202                 alarm->time.tm_isdst = -1;
 203                 err = rtc->ops->read_alarm(rtc->dev.parent, alarm);
 204         }
 205
 206         mutex_unlock(&rtc->ops_lock);
 207
 208         trace_rtc_read_alarm(rtc_tm_to_time64(&alarm->time), err);
 209         return err;
 210 }
 211
 212 int __rtc_read_alarm(struct rtc_device *rtc, struct rtc_wkalrm *alarm)
 213 {
 214         int err;
 215         struct rtc_time before, now;
 216         int first_time = 1;
 217         time64_t t_now, t_alm;
 218         enum { none, day, month, year } missing = none;
 219         unsigned int days;
 220
 221         /* The lower level RTC driver may return -1 in some fields,
 222          * creating invalid alarm->time values, for reasons like:
 223          *
 224          *   - The hardware may not be capable of filling them in;
 225          *     many alarms match only on time-of-day fields, not
 226          *     day/month/year calendar data.
 227          *
 228          *   - Some hardware uses illegal values as "wildcard" match
 229          *     values, which non-Linux firmware (like a BIOS) may try
 230          *     to set up as e.g. "alarm 15 minutes after each hour".
 231          *     Linux uses only oneshot alarms.
 232          *
 233          * When we see that here, we deal with it by using values from
 234          * a current RTC timestamp for any missing (-1) values.  The
 235          * RTC driver prevents "periodic alarm" modes.
 236          *
 237          * But this can be racey, because some fields of the RTC timestamp
 238          * may have wrapped in the interval since we read the RTC alarm,
 239          * which would lead to us inserting inconsistent values in place
 240          * of the -1 fields.
 241          *
 242          * Reading the alarm and timestamp in the reverse sequence
 243          * would have the same race condition, and not solve the issue.
 244          *
 245          * So, we must first read the RTC timestamp,
 246          * then read the RTC alarm value,
 247          * and then read a second RTC timestamp.
 248          *
 249          * If any fields of the second timestamp have changed
 250          * when compared with the first timestamp, then we know
 251          * our timestamp may be inconsistent with that used by
 252          * the low-level rtc_read_alarm_internal() function.
 253          *
 254          * So, when the two timestamps disagree, we just loop and do
 255          * the process again to get a fully consistent set of values.
 256          *
 257          * This could all instead be done in the lower level driver,
 258          * but since more than one lower level RTC implementation needs it,
 259          * then it's probably best to do it here instead of there..
 260          */
 261
 262         /* Get the "before" timestamp */
 263         err = rtc_read_time(rtc, &before);
 264         if (err < 0)
 265                 return err;
 266         do {
 267                 if (!first_time)
 268                         memcpy(&before, &now, sizeof(struct rtc_time));
 269                 first_time = 0;
 270
 271                 /* get the RTC alarm values, which may be incomplete */
 272                 err = rtc_read_alarm_internal(rtc, alarm);
 273                 if (err)
 274                         return err;
 275
 276                 /* full-function RTCs won't have such missing fields */
 277                 err = rtc_valid_tm(&alarm->time);
 278                 if (!err)
 279                         goto done;
 280
 281                 /* get the "after" timestamp, to detect wrapped fields */
 282                 err = rtc_read_time(rtc, &now);
 283                 if (err < 0)
 284                         return err;
 285
 286                 /* note that tm_sec is a "don't care" value here: */
 287         } while (before.tm_min  != now.tm_min ||
 288                  before.tm_hour != now.tm_hour ||
 289                  before.tm_mon  != now.tm_mon ||
 290                  before.tm_year != now.tm_year);
 291
 292         /* Fill in the missing alarm fields using the timestamp; we
 293          * know there's at least one since alarm->time is invalid.
 294          */
 295         if (alarm->time.tm_sec == -1)
 296                 alarm->time.tm_sec = now.tm_sec;
 297         if (alarm->time.tm_min == -1)
 298                 alarm->time.tm_min = now.tm_min;
 299         if (alarm->time.tm_hour == -1)
 300                 alarm->time.tm_hour = now.tm_hour;
 301
 302         /* For simplicity, only support date rollover for now */
 303         if (alarm->time.tm_mday < 1 || alarm->time.tm_mday > 31) {
 304                 alarm->time.tm_mday = now.tm_mday;
 305                 missing = day;
 306         }
 307         if ((unsigned int)alarm->time.tm_mon >= 12) {
 308                 alarm->time.tm_mon = now.tm_mon;
 309                 if (missing == none)
 310                         missing = month;
 311         }
 312         if (alarm->time.tm_year == -1) {
 313                 alarm->time.tm_year = now.tm_year;
 314                 if (missing == none)
 315                         missing = year;
 316         }
 317
 318         /* Can't proceed if alarm is still invalid after replacing
 319          * missing fields.
 320          */
 321         err = rtc_valid_tm(&alarm->time);
 322         if (err)
 323                 goto done;
 324
 325         /* with luck, no rollover is needed */
 326         t_now = rtc_tm_to_time64(&now);
 327         t_alm = rtc_tm_to_time64(&alarm->time);
 328         if (t_now < t_alm)
 329                 goto done;
 330
 331         switch (missing) {
 332         /* 24 hour rollover ... if it's now 10am Monday, an alarm that
 333          * that will trigger at 5am will do so at 5am Tuesday, which
 334          * could also be in the next month or year.  This is a common
 335          * case, especially for PCs.
 336          */
 337         case day:
 338                 dev_dbg(&rtc->dev, "alarm rollover: %s\n", "day");
 339                 t_alm += 24 * 60 * 60;
 340                 rtc_time64_to_tm(t_alm, &alarm->time);
 341                 break;
 342
 343         /* Month rollover ... if it's the 31th, an alarm on the 3rd will
 344          * be next month.  An alarm matching on the 30th, 29th, or 28th
 345          * may end up in the month after that!  Many newer PCs support
 346          * this type of alarm.
 347          */
 348         case month:
 349                 dev_dbg(&rtc->dev, "alarm rollover: %s\n", "month");
 350                 do {
 351                         if (alarm->time.tm_mon < 11) {
 352                                 alarm->time.tm_mon++;
 353                         } else {
 354                                 alarm->time.tm_mon = 0;
 355                                 alarm->time.tm_year++;
 356                         }
 357                         days = rtc_month_days(alarm->time.tm_mon,
 358                                               alarm->time.tm_year);
 359                 } while (days < alarm->time.tm_mday);
 360                 break;
 361
 362         /* Year rollover ... easy except for leap years! */
 363         case year:
 364                 dev_dbg(&rtc->dev, "alarm rollover: %s\n", "year");
 365                 do {
 366                         alarm->time.tm_year++;
 367                 } while (!is_leap_year(alarm->time.tm_year + 1900) &&
 368                          rtc_valid_tm(&alarm->time) != 0);
 369                 break;
 370
 371         default:
 372                 dev_warn(&rtc->dev, "alarm rollover not handled\n");
 373         }
 374
 375         err = rtc_valid_tm(&alarm->time);
 376
 377 done:
 378         if (err && alarm->enabled)
 379                 dev_warn(&rtc->dev, "invalid alarm value: %ptR\n",
 380                          &alarm->time);
 381         else
 382                 rtc_add_offset(rtc, &alarm->time);
 383
 384         return err;
 385 }
 386
 387 int rtc_read_alarm(struct rtc_device *rtc, struct rtc_wkalrm *alarm)
 388 {
 389         int err;
 390
 391         err = mutex_lock_interruptible(&rtc->ops_lock);
 392         if (err)
 393                 return err;
 394         if (!rtc->ops) {
 395                 err = -ENODEV;
 396         } else if (!test_bit(RTC_FEATURE_ALARM, rtc->features)) {
 397                 err = -EINVAL;
 398         } else {
 399                 memset(alarm, 0, sizeof(struct rtc_wkalrm));
 400                 alarm->enabled = rtc->aie_timer.enabled;
 401                 alarm->time = rtc_ktime_to_tm(rtc->aie_timer.node.expires);
 402         }
 403         mutex_unlock(&rtc->ops_lock);
 404
 405         trace_rtc_read_alarm(rtc_tm_to_time64(&alarm->time), err);
 406         return err;
 407 }
 408 EXPORT_SYMBOL_GPL(rtc_read_alarm);
 409
 410 static int __rtc_set_alarm(struct rtc_device *rtc, struct rtc_wkalrm *alarm)
 411 {
 412         struct rtc_time tm;
 413         time64_t now, scheduled;
 414         int err;
 415
 416         err = rtc_valid_tm(&alarm->time);
 417         if (err)
 418                 return err;
 419
 420         scheduled = rtc_tm_to_time64(&alarm->time);
 421
 422         /* Make sure we're not setting alarms in the past */
 423         err = __rtc_read_time(rtc, &tm);
 424         if (err)
 425                 return err;
 426         now = rtc_tm_to_time64(&tm);
 427
 428         if (scheduled <= now)
 429                 return -ETIME;
 430         /*
 431          * XXX - We just checked to make sure the alarm time is not
 432          * in the past, but there is still a race window where if
 433          * the is alarm set for the next second and the second ticks
 434          * over right here, before we set the alarm.
 435          */
 436
 437         rtc_subtract_offset(rtc, &alarm->time);
 438
 439         if (!rtc->ops)
 440                 err = -ENODEV;
 441         else if (!test_bit(RTC_FEATURE_ALARM, rtc->features))
 442                 err = -EINVAL;
 443         else
 444                 err = rtc->ops->set_alarm(rtc->dev.parent, alarm);
 445
 446         trace_rtc_set_alarm(rtc_tm_to_time64(&alarm->time), err);
 447         return err;
 448 }
 449
 450 int rtc_set_alarm(struct rtc_device *rtc, struct rtc_wkalrm *alarm)
 451 {
 452         ktime_t alarm_time;
 453         int err;
 454
 455         if (!rtc->ops)
 456                 return -ENODEV;
 457         else if (!test_bit(RTC_FEATURE_ALARM, rtc->features))
 458                 return -EINVAL;
 459
 460         err = rtc_valid_tm(&alarm->time);
 461         if (err != 0)
 462                 return err;
 463
 464         err = rtc_valid_range(rtc, &alarm->time);
 465         if (err)
 466                 return err;
 467
 468         err = mutex_lock_interruptible(&rtc->ops_lock);
 469         if (err)
 470                 return err;
 471         if (rtc->aie_timer.enabled)
 472                 rtc_timer_remove(rtc, &rtc->aie_timer);
 473
 474         alarm_time = rtc_tm_to_ktime(alarm->time);
 475         /*
 476          * Round down so we never miss a deadline, checking for past deadline is
 477          * done in __rtc_set_alarm
 478          */
 479         if (test_bit(RTC_FEATURE_ALARM_RES_MINUTE, rtc->features))
 480                 alarm_time = ktime_sub_ns(alarm_time, (u64)alarm->time.tm_sec * NSEC_PER_SEC);
 481
 482         rtc->aie_timer.node.expires = alarm_time;
 483         rtc->aie_timer.period = 0;
 484         if (alarm->enabled)
 485                 err = rtc_timer_enqueue(rtc, &rtc->aie_timer);
 486
 487         mutex_unlock(&rtc->ops_lock);
 488
 489         return err;
 490 }
 491 EXPORT_SYMBOL_GPL(rtc_set_alarm);
 492
 493 /* Called once per device from rtc_device_register */
 494 int rtc_initialize_alarm(struct rtc_device *rtc, struct rtc_wkalrm *alarm)
 495 {
 496         int err;
 497         struct rtc_time now;
 498
 499         err = rtc_valid_tm(&alarm->time);
 500         if (err != 0)
 501                 return err;
 502
 503         err = rtc_read_time(rtc, &now);
 504         if (err)
 505                 return err;
 506
 507         err = mutex_lock_interruptible(&rtc->ops_lock);
 508         if (err)
 509                 return err;
 510
 511         rtc->aie_timer.node.expires = rtc_tm_to_ktime(alarm->time);
 512         rtc->aie_timer.period = 0;
 513
 514         /* Alarm has to be enabled & in the future for us to enqueue it */
 515         if (alarm->enabled && (rtc_tm_to_ktime(now) <
 516                          rtc->aie_timer.node.expires)) {
 517                 rtc->aie_timer.enabled = 1;
 518                 timerqueue_add(&rtc->timerqueue, &rtc->aie_timer.node);
 519                 trace_rtc_timer_enqueue(&rtc->aie_timer);
 520         }
 521         mutex_unlock(&rtc->ops_lock);
 522         return err;
 523 }
 524 EXPORT_SYMBOL_GPL(rtc_initialize_alarm);
 525
 526 int rtc_alarm_irq_enable(struct rtc_device *rtc, unsigned int enabled)
 527 {
 528         int err;
 529
 530         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 (!test_bit(RTC_FEATURE_ALARM, rtc->features) || !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;
 560
 561         err = mutex_lock_interruptible(&rtc->ops_lock);
 562         if (err)
 563                 return err;
 564
 565 #ifdef CONFIG_RTC_INTF_DEV_UIE_EMUL
 566         if (enabled == 0 && rtc->uie_irq_active) {
 567                 mutex_unlock(&rtc->ops_lock);
 568                 return rtc_dev_update_irq_enable_emul(rtc, 0);
 569         }
 570 #endif
 571         /* make sure we're changing state */
 572         if (rtc->uie_rtctimer.enabled == enabled)
 573                 goto out;
 574
 575         if (!test_bit(RTC_FEATURE_UPDATE_INTERRUPT, rtc->features) ||
 576             !test_bit(RTC_FEATURE_ALARM, rtc->features)) {
 577                 mutex_unlock(&rtc->ops_lock);
 578 #ifdef CONFIG_RTC_INTF_DEV_UIE_EMUL
 579                 return rtc_dev_update_irq_enable_emul(rtc, enabled);
 580 #else
 581                 return -EINVAL;
 582 #endif
 583         }
 584
 585         if (enabled) {
 586                 struct rtc_time tm;
 587                 ktime_t now, onesec;
 588
 589                 err = __rtc_read_time(rtc, &tm);
 590                 if (err)
 591                         goto out;
 592                 onesec = ktime_set(1, 0);
 593                 now = rtc_tm_to_ktime(tm);
 594                 rtc->uie_rtctimer.node.expires = ktime_add(now, onesec);
 595                 rtc->uie_rtctimer.period = ktime_set(1, 0);
 596                 err = rtc_timer_enqueue(rtc, &rtc->uie_rtctimer);
 597         } else {
 598                 rtc_timer_remove(rtc, &rtc->uie_rtctimer);
 599         }
 600
 601 out:
 602         mutex_unlock(&rtc->ops_lock);
 603
 604         return err;
 605 }
 606 EXPORT_SYMBOL_GPL(rtc_update_irq_enable);
 607
 608 /**
 609  * rtc_handle_legacy_irq - AIE, UIE and PIE event hook
 610  * @rtc: pointer to the rtc device
 611  * @num: number of occurence of the event
 612  * @mode: type of the event, RTC_AF, RTC_UF of RTC_PF
 613  *
 614  * This function is called when an AIE, UIE or PIE mode interrupt
 615  * has occurred (or been emulated).
 616  *
 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  * rtc_aie_update_irq - AIE mode rtctimer hook
 633  * @rtc: pointer to the rtc_device
 634  *
 635  * This functions is called when the aie_timer expires.
 636  */
 637 void rtc_aie_update_irq(struct rtc_device *rtc)
 638 {
 639         rtc_handle_legacy_irq(rtc, 1, RTC_AF);
 640 }
 641
 642 /**
 643  * rtc_uie_update_irq - UIE mode rtctimer hook
 644  * @rtc: pointer to the rtc_device
 645  *
 646  * This functions is called when the uie_timer expires.
 647  */
 648 void rtc_uie_update_irq(struct rtc_device *rtc)
 649 {
 650         rtc_handle_legacy_irq(rtc, 1,  RTC_UF);
 651 }
 652
 653 /**
 654  * rtc_pie_update_irq - PIE mode hrtimer hook
 655  * @timer: pointer to the pie mode hrtimer
 656  *
 657  * This function is used to emulate PIE mode interrupts
 658  * using an hrtimer. This function is called when the periodic
 659  * hrtimer expires.
 660  */
 661 enum hrtimer_restart rtc_pie_update_irq(struct hrtimer *timer)
 662 {
 663         struct rtc_device *rtc;
 664         ktime_t period;
 665         u64 count;
 666
 667         rtc = container_of(timer, struct rtc_device, pie_timer);
 668
 669         period = NSEC_PER_SEC / rtc->irq_freq;
 670         count = hrtimer_forward_now(timer, period);
 671
 672         rtc_handle_legacy_irq(rtc, count, RTC_PF);
 673
 674         return HRTIMER_RESTART;
 675 }
 676
 677 /**
 678  * rtc_update_irq - Triggered when a RTC interrupt occurs.
 679  * @rtc: the rtc device
 680  * @num: how many irqs are being reported (usually one)
 681  * @events: mask of RTC_IRQF with one or more of RTC_PF, RTC_AF, RTC_UF
 682  * Context: any
 683  */
 684 void rtc_update_irq(struct rtc_device *rtc,
 685                     unsigned long num, unsigned long events)
 686 {
 687         if (IS_ERR_OR_NULL(rtc))
 688                 return;
 689
 690         pm_stay_awake(rtc->dev.parent);
 691         schedule_work(&rtc->irqwork);
 692 }
 693 EXPORT_SYMBOL_GPL(rtc_update_irq);
 694
 695 struct rtc_device *rtc_class_open(const char *name)
 696 {
 697         struct device *dev;
 698         struct rtc_device *rtc = NULL;
 699
 700         dev = class_find_device_by_name(&rtc_class, name);
 701         if (dev)
 702                 rtc = to_rtc_device(dev);
 703
 704         if (rtc) {
 705                 if (!try_module_get(rtc->owner)) {
 706                         put_device(dev);
 707                         rtc = NULL;
 708                 }
 709         }
 710
 711         return rtc;
 712 }
 713 EXPORT_SYMBOL_GPL(rtc_class_open);
 714
 715 void rtc_class_close(struct rtc_device *rtc)
 716 {
 717         module_put(rtc->owner);
 718         put_device(&rtc->dev);
 719 }
 720 EXPORT_SYMBOL_GPL(rtc_class_close);
 721
 722 static int rtc_update_hrtimer(struct rtc_device *rtc, int enabled)
 723 {
 724         /*
 725          * We always cancel the timer here first, because otherwise
 726          * we could run into BUG_ON(timer->state != HRTIMER_STATE_CALLBACK);
 727          * when we manage to start the timer before the callback
 728          * returns HRTIMER_RESTART.
 729          *
 730          * We cannot use hrtimer_cancel() here as a running callback
 731          * could be blocked on rtc->irq_task_lock and hrtimer_cancel()
 732          * would spin forever.
 733          */
 734         if (hrtimer_try_to_cancel(&rtc->pie_timer) < 0)
 735                 return -1;
 736
 737         if (enabled) {
 738                 ktime_t period = NSEC_PER_SEC / rtc->irq_freq;
 739
 740                 hrtimer_start(&rtc->pie_timer, period, HRTIMER_MODE_REL);
 741         }
 742         return 0;
 743 }
 744
 745 /**
 746  * rtc_irq_set_state - enable/disable 2^N Hz periodic IRQs
 747  * @rtc: the rtc device
 748  * @enabled: true to enable periodic IRQs
 749  * Context: any
 750  *
 751  * Note that rtc_irq_set_freq() should previously have been used to
 752  * specify the desired frequency of periodic IRQ.
 753  */
 754 int rtc_irq_set_state(struct rtc_device *rtc, int enabled)
 755 {
 756         int err = 0;
 757
 758         while (rtc_update_hrtimer(rtc, enabled) < 0)
 759                 cpu_relax();
 760
 761         rtc->pie_enabled = enabled;
 762
 763         trace_rtc_irq_set_state(enabled, err);
 764         return err;
 765 }
 766
 767 /**
 768  * rtc_irq_set_freq - set 2^N Hz periodic IRQ frequency for IRQ
 769  * @rtc: the rtc device
 770  * @freq: positive frequency
 771  * Context: any
 772  *
 773  * Note that rtc_irq_set_state() is used to enable or disable the
 774  * periodic IRQs.
 775  */
 776 int rtc_irq_set_freq(struct rtc_device *rtc, int freq)
 777 {
 778         int err = 0;
 779
 780         if (freq <= 0 || freq > RTC_MAX_FREQ)
 781                 return -EINVAL;
 782
 783         rtc->irq_freq = freq;
 784         while (rtc->pie_enabled && rtc_update_hrtimer(rtc, 1) < 0)
 785                 cpu_relax();
 786
 787         trace_rtc_irq_set_freq(freq, err);
 788         return err;
 789 }
 790
 791 /**
 792  * rtc_timer_enqueue - Adds a rtc_timer to the rtc_device timerqueue
 793  * @rtc: rtc device
 794  * @timer: timer being added.
 795  *
 796  * Enqueues a timer onto the rtc devices timerqueue and sets
 797  * the next alarm event appropriately.
 798  *
 799  * Sets the enabled bit on the added timer.
 800  *
 801  * Must hold ops_lock for proper serialization of timerqueue
 802  */
 803 static int rtc_timer_enqueue(struct rtc_device *rtc, struct rtc_timer *timer)
 804 {
 805         struct timerqueue_node *next = timerqueue_getnext(&rtc->timerqueue);
 806         struct rtc_time tm;
 807         ktime_t now;
 808         int err;
 809
 810         err = __rtc_read_time(rtc, &tm);
 811         if (err)
 812                 return err;
 813
 814         timer->enabled = 1;
 815         now = rtc_tm_to_ktime(tm);
 816
 817         /* Skip over expired timers */
 818         while (next) {
 819                 if (next->expires >= now)
 820                         break;
 821                 next = timerqueue_iterate_next(next);
 822         }
 823
 824         timerqueue_add(&rtc->timerqueue, &timer->node);
 825         trace_rtc_timer_enqueue(timer);
 826         if (!next || ktime_before(timer->node.expires, next->expires)) {
 827                 struct rtc_wkalrm alarm;
 828
 829                 alarm.time = rtc_ktime_to_tm(timer->node.expires);
 830                 alarm.enabled = 1;
 831                 err = __rtc_set_alarm(rtc, &alarm);
 832                 if (err == -ETIME) {
 833                         pm_stay_awake(rtc->dev.parent);
 834                         schedule_work(&rtc->irqwork);
 835                 } else if (err) {
 836                         timerqueue_del(&rtc->timerqueue, &timer->node);
 837                         trace_rtc_timer_dequeue(timer);
 838                         timer->enabled = 0;
 839                         return err;
 840                 }
 841         }
 842         return 0;
 843 }
 844
 845 static void rtc_alarm_disable(struct rtc_device *rtc)
 846 {
 847         if (!rtc->ops || !test_bit(RTC_FEATURE_ALARM, rtc->features) || !rtc->ops->alarm_irq_enable)
 848                 return;
 849
 850         rtc->ops->alarm_irq_enable(rtc->dev.parent, false);
 851         trace_rtc_alarm_irq_enable(0, 0);
 852 }
 853
 854 /**
 855  * rtc_timer_remove - Removes a rtc_timer from the rtc_device timerqueue
 856  * @rtc: rtc device
 857  * @timer: timer being removed.
 858  *
 859  * Removes a timer onto the rtc devices timerqueue and sets
 860  * the next alarm event appropriately.
 861  *
 862  * Clears the enabled bit on the removed timer.
 863  *
 864  * Must hold ops_lock for proper serialization of timerqueue
 865  */
 866 static void rtc_timer_remove(struct rtc_device *rtc, struct rtc_timer *timer)
 867 {
 868         struct timerqueue_node *next = timerqueue_getnext(&rtc->timerqueue);
 869
 870         timerqueue_del(&rtc->timerqueue, &timer->node);
 871         trace_rtc_timer_dequeue(timer);
 872         timer->enabled = 0;
 873         if (next == &timer->node) {
 874                 struct rtc_wkalrm alarm;
 875                 int err;
 876
 877                 next = timerqueue_getnext(&rtc->timerqueue);
 878                 if (!next) {
 879                         rtc_alarm_disable(rtc);
 880                         return;
 881                 }
 882                 alarm.time = rtc_ktime_to_tm(next->expires);
 883                 alarm.enabled = 1;
 884                 err = __rtc_set_alarm(rtc, &alarm);
 885                 if (err == -ETIME) {
 886                         pm_stay_awake(rtc->dev.parent);
 887                         schedule_work(&rtc->irqwork);
 888                 }
 889         }
 890 }
 891
 892 /**
 893  * rtc_timer_do_work - Expires rtc timers
 894  * @work: work item
 895  *
 896  * Expires rtc timers. Reprograms next alarm event if needed.
 897  * Called via worktask.
 898  *
 899  * Serializes access to timerqueue via ops_lock mutex
 900  */
 901 void rtc_timer_do_work(struct work_struct *work)
 902 {
 903         struct rtc_timer *timer;
 904         struct timerqueue_node *next;
 905         ktime_t now;
 906         struct rtc_time tm;
 907         int err;
 908
 909         struct rtc_device *rtc =
 910                 container_of(work, struct rtc_device, irqwork);
 911
 912         mutex_lock(&rtc->ops_lock);
 913 again:
 914         err = __rtc_read_time(rtc, &tm);
 915         if (err) {
 916                 mutex_unlock(&rtc->ops_lock);
 917                 return;
 918         }
 919         now = rtc_tm_to_ktime(tm);
 920         while ((next = timerqueue_getnext(&rtc->timerqueue))) {
 921                 if (next->expires > now)
 922                         break;
 923
 924                 /* expire timer */
 925                 timer = container_of(next, struct rtc_timer, node);
 926                 timerqueue_del(&rtc->timerqueue, &timer->node);
 927                 trace_rtc_timer_dequeue(timer);
 928                 timer->enabled = 0;
 929                 if (timer->func)
 930                         timer->func(timer->rtc);
 931
 932                 trace_rtc_timer_fired(timer);
 933                 /* Re-add/fwd periodic timers */
 934                 if (ktime_to_ns(timer->period)) {
 935                         timer->node.expires = ktime_add(timer->node.expires,
 936                                                         timer->period);
 937                         timer->enabled = 1;
 938                         timerqueue_add(&rtc->timerqueue, &timer->node);
 939                         trace_rtc_timer_enqueue(timer);
 940                 }
 941         }
 942
 943         /* Set next alarm */
 944         if (next) {
 945                 struct rtc_wkalrm alarm;
 946                 int err;
 947                 int retry = 3;
 948
 949                 alarm.time = rtc_ktime_to_tm(next->expires);
 950                 alarm.enabled = 1;
 951 reprogram:
 952                 err = __rtc_set_alarm(rtc, &alarm);
 953                 if (err == -ETIME) {
 954                         goto again;
 955                 } else if (err) {
 956                         if (retry-- > 0)
 957                                 goto reprogram;
 958
 959                         timer = container_of(next, struct rtc_timer, node);
 960                         timerqueue_del(&rtc->timerqueue, &timer->node);
 961                         trace_rtc_timer_dequeue(timer);
 962                         timer->enabled = 0;
 963                         dev_err(&rtc->dev, "__rtc_set_alarm: err=%d\n", err);
 964                         goto again;
 965                 }
 966         } else {
 967                 rtc_alarm_disable(rtc);
 968         }
 969
 970         pm_relax(rtc->dev.parent);
 971         mutex_unlock(&rtc->ops_lock);
 972 }
 973
 974 /* rtc_timer_init - Initializes an rtc_timer
 975  * @timer: timer to be intiialized
 976  * @f: function pointer to be called when timer fires
 977  * @rtc: pointer to the rtc_device
 978  *
 979  * Kernel interface to initializing an rtc_timer.
 980  */
 981 void rtc_timer_init(struct rtc_timer *timer, void (*f)(struct rtc_device *r),
 982                     struct rtc_device *rtc)
 983 {
 984         timerqueue_init(&timer->node);
 985         timer->enabled = 0;
 986         timer->func = f;
 987         timer->rtc = rtc;
 988 }
 989
 990 /* rtc_timer_start - Sets an rtc_timer to fire in the future
 991  * @ rtc: rtc device to be used
 992  * @ timer: timer being set
 993  * @ expires: time at which to expire the timer
 994  * @ period: period that the timer will recur
 995  *
 996  * Kernel interface to set an rtc_timer
 997  */
 998 int rtc_timer_start(struct rtc_device *rtc, struct rtc_timer *timer,
 999                     ktime_t expires, ktime_t period)
1000 {
1001         int ret = 0;
1002
1003         mutex_lock(&rtc->ops_lock);
1004         if (timer->enabled)
1005                 rtc_timer_remove(rtc, timer);
1006
1007         timer->node.expires = expires;
1008         timer->period = period;
1009
1010         ret = rtc_timer_enqueue(rtc, timer);
1011
1012         mutex_unlock(&rtc->ops_lock);
1013         return ret;
1014 }
1015
1016 /* rtc_timer_cancel - Stops an rtc_timer
1017  * @ rtc: rtc device to be used
1018  * @ timer: timer being set
1019  *
1020  * Kernel interface to cancel an rtc_timer
1021  */
1022 void rtc_timer_cancel(struct rtc_device *rtc, struct rtc_timer *timer)
1023 {
1024         mutex_lock(&rtc->ops_lock);
1025         if (timer->enabled)
1026                 rtc_timer_remove(rtc, timer);
1027         mutex_unlock(&rtc->ops_lock);
1028 }
1029
1030 /**
1031  * rtc_read_offset - Read the amount of rtc offset in parts per billion
1032  * @rtc: rtc device to be used
1033  * @offset: the offset in parts per billion
1034  *
1035  * see below for details.
1036  *
1037  * Kernel interface to read rtc clock offset
1038  * Returns 0 on success, or a negative number on error.
1039  * If read_offset() is not implemented for the rtc, return -EINVAL
1040  */
1041 int rtc_read_offset(struct rtc_device *rtc, long *offset)
1042 {
1043         int ret;
1044
1045         if (!rtc->ops)
1046                 return -ENODEV;
1047
1048         if (!rtc->ops->read_offset)
1049                 return -EINVAL;
1050
1051         mutex_lock(&rtc->ops_lock);
1052         ret = rtc->ops->read_offset(rtc->dev.parent, offset);
1053         mutex_unlock(&rtc->ops_lock);
1054
1055         trace_rtc_read_offset(*offset, ret);
1056         return ret;
1057 }
1058
1059 /**
1060  * rtc_set_offset - Adjusts the duration of the average second
1061  * @rtc: rtc device to be used
1062  * @offset: the offset in parts per billion
1063  *
1064  * Some rtc's allow an adjustment to the average duration of a second
1065  * to compensate for differences in the actual clock rate due to temperature,
1066  * the crystal, capacitor, etc.
1067  *
1068  * The adjustment applied is as follows:
1069  *   t = t0 * (1 + offset * 1e-9)
1070  * where t0 is the measured length of 1 RTC second with offset = 0
1071  *
1072  * Kernel interface to adjust an rtc clock offset.
1073  * Return 0 on success, or a negative number on error.
1074  * If the rtc offset is not setable (or not implemented), return -EINVAL
1075  */
1076 int rtc_set_offset(struct rtc_device *rtc, long offset)
1077 {
1078         int ret;
1079
1080         if (!rtc->ops)
1081                 return -ENODEV;
1082
1083         if (!rtc->ops->set_offset)
1084                 return -EINVAL;
1085
1086         mutex_lock(&rtc->ops_lock);
1087         ret = rtc->ops->set_offset(rtc->dev.parent, offset);
1088         mutex_unlock(&rtc->ops_lock);
1089
1090         trace_rtc_set_offset(offset, ret);
1091         return ret;
1092 }