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