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  * Triggers the registered irq_task function callback.
 600  */
 601 void rtc_handle_legacy_irq(struct rtc_device *rtc, int num, int mode)
 602 {
 603         unsigned long flags;
 604
 605         /* mark one irq of the appropriate mode */
 606         spin_lock_irqsave(&rtc->irq_lock, flags);
 607         rtc->irq_data = (rtc->irq_data + (num << 8)) | (RTC_IRQF|mode);
 608         spin_unlock_irqrestore(&rtc->irq_lock, flags);
 609
 610         wake_up_interruptible(&rtc->irq_queue);
 611         kill_fasync(&rtc->async_queue, SIGIO, POLL_IN);
 612 }
 613
 614
 615 /**
 616  * rtc_aie_update_irq - AIE mode rtctimer hook
 617  * @private: pointer to the rtc_device
 618  *
 619  * This functions is called when the aie_timer expires.
 620  */
 621 void rtc_aie_update_irq(void *private)
 622 {
 623         struct rtc_device *rtc = (struct rtc_device *)private;
 624         rtc_handle_legacy_irq(rtc, 1, RTC_AF);
 625 }
 626
 627
 628 /**
 629  * rtc_uie_update_irq - UIE mode rtctimer hook
 630  * @private: pointer to the rtc_device
 631  *
 632  * This functions is called when the uie_timer expires.
 633  */
 634 void rtc_uie_update_irq(void *private)
 635 {
 636         struct rtc_device *rtc = (struct rtc_device *)private;
 637         rtc_handle_legacy_irq(rtc, 1,  RTC_UF);
 638 }
 639
 640
 641 /**
 642  * rtc_pie_update_irq - PIE mode hrtimer hook
 643  * @timer: pointer to the pie mode hrtimer
 644  *
 645  * This function is used to emulate PIE mode interrupts
 646  * using an hrtimer. This function is called when the periodic
 647  * hrtimer expires.
 648  */
 649 enum hrtimer_restart rtc_pie_update_irq(struct hrtimer *timer)
 650 {
 651         struct rtc_device *rtc;
 652         ktime_t period;
 653         int count;
 654         rtc = container_of(timer, struct rtc_device, pie_timer);
 655
 656         period = NSEC_PER_SEC / rtc->irq_freq;
 657         count = hrtimer_forward_now(timer, period);
 658
 659         rtc_handle_legacy_irq(rtc, count, RTC_PF);
 660
 661         return HRTIMER_RESTART;
 662 }
 663
 664 /**
 665  * rtc_update_irq - Triggered when a RTC interrupt occurs.
 666  * @rtc: the rtc device
 667  * @num: how many irqs are being reported (usually one)
 668  * @events: mask of RTC_IRQF with one or more of RTC_PF, RTC_AF, RTC_UF
 669  * Context: any
 670  */
 671 void rtc_update_irq(struct rtc_device *rtc,
 672                 unsigned long num, unsigned long events)
 673 {
 674         if (IS_ERR_OR_NULL(rtc))
 675                 return;
 676
 677         pm_stay_awake(rtc->dev.parent);
 678         schedule_work(&rtc->irqwork);
 679 }
 680 EXPORT_SYMBOL_GPL(rtc_update_irq);
 681
 682 static int __rtc_match(struct device *dev, const void *data)
 683 {
 684         const char *name = data;
 685
 686         if (strcmp(dev_name(dev), name) == 0)
 687                 return 1;
 688         return 0;
 689 }
 690
 691 struct rtc_device *rtc_class_open(const char *name)
 692 {
 693         struct device *dev;
 694         struct rtc_device *rtc = NULL;
 695
 696         dev = class_find_device(rtc_class, NULL, name, __rtc_match);
 697         if (dev)
 698                 rtc = to_rtc_device(dev);
 699
 700         if (rtc) {
 701                 if (!try_module_get(rtc->owner)) {
 702                         put_device(dev);
 703                         rtc = NULL;
 704                 }
 705         }
 706
 707         return rtc;
 708 }
 709 EXPORT_SYMBOL_GPL(rtc_class_open);
 710
 711 void rtc_class_close(struct rtc_device *rtc)
 712 {
 713         module_put(rtc->owner);
 714         put_device(&rtc->dev);
 715 }
 716 EXPORT_SYMBOL_GPL(rtc_class_close);
 717
 718 static int rtc_update_hrtimer(struct rtc_device *rtc, int enabled)
 719 {
 720         /*
 721          * We always cancel the timer here first, because otherwise
 722          * we could run into BUG_ON(timer->state != HRTIMER_STATE_CALLBACK);
 723          * when we manage to start the timer before the callback
 724          * returns HRTIMER_RESTART.
 725          *
 726          * We cannot use hrtimer_cancel() here as a running callback
 727          * could be blocked on rtc->irq_task_lock and hrtimer_cancel()
 728          * would spin forever.
 729          */
 730         if (hrtimer_try_to_cancel(&rtc->pie_timer) < 0)
 731                 return -1;
 732
 733         if (enabled) {
 734                 ktime_t period = NSEC_PER_SEC / rtc->irq_freq;
 735
 736                 hrtimer_start(&rtc->pie_timer, period, HRTIMER_MODE_REL);
 737         }
 738         return 0;
 739 }
 740
 741 /**
 742  * rtc_irq_set_state - enable/disable 2^N Hz periodic IRQs
 743  * @rtc: the rtc device
 744  * @task: currently registered with rtc_irq_register()
 745  * @enabled: true to enable periodic IRQs
 746  * Context: any
 747  *
 748  * Note that rtc_irq_set_freq() should previously have been used to
 749  * specify the desired frequency of periodic IRQ.
 750  */
 751 int rtc_irq_set_state(struct rtc_device *rtc, int enabled)
 752 {
 753         int err = 0;
 754
 755         while (rtc_update_hrtimer(rtc, enabled) < 0)
 756                 cpu_relax();
 757
 758         rtc->pie_enabled = enabled;
 759
 760         trace_rtc_irq_set_state(enabled, err);
 761         return err;
 762 }
 763
 764 /**
 765  * rtc_irq_set_freq - set 2^N Hz periodic IRQ frequency for IRQ
 766  * @rtc: the rtc device
 767  * @task: currently registered with rtc_irq_register()
 768  * @freq: positive frequency
 769  * Context: any
 770  *
 771  * Note that rtc_irq_set_state() is used to enable or disable the
 772  * periodic IRQs.
 773  */
 774 int rtc_irq_set_freq(struct rtc_device *rtc, int freq)
 775 {
 776         int err = 0;
 777
 778         if (freq <= 0 || freq > RTC_MAX_FREQ)
 779                 return -EINVAL;
 780
 781         rtc->irq_freq = freq;
 782         while (rtc->pie_enabled && rtc_update_hrtimer(rtc, 1) < 0)
 783                 cpu_relax();
 784
 785         trace_rtc_irq_set_freq(freq, err);
 786         return err;
 787 }
 788
 789 /**
 790  * rtc_timer_enqueue - Adds a rtc_timer to the rtc_device timerqueue
 791  * @rtc rtc device
 792  * @timer timer being added.
 793  *
 794  * Enqueues a timer onto the rtc devices timerqueue and sets
 795  * the next alarm event appropriately.
 796  *
 797  * Sets the enabled bit on the added timer.
 798  *
 799  * Must hold ops_lock for proper serialization of timerqueue
 800  */
 801 static int rtc_timer_enqueue(struct rtc_device *rtc, struct rtc_timer *timer)
 802 {
 803         struct timerqueue_node *next = timerqueue_getnext(&rtc->timerqueue);
 804         struct rtc_time tm;
 805         ktime_t now;
 806
 807         timer->enabled = 1;
 808         __rtc_read_time(rtc, &tm);
 809         now = rtc_tm_to_ktime(tm);
 810
 811         /* Skip over expired timers */
 812         while (next) {
 813                 if (next->expires >= now)
 814                         break;
 815                 next = timerqueue_iterate_next(next);
 816         }
 817
 818         timerqueue_add(&rtc->timerqueue, &timer->node);
 819         trace_rtc_timer_enqueue(timer);
 820         if (!next || ktime_before(timer->node.expires, next->expires)) {
 821                 struct rtc_wkalrm alarm;
 822                 int err;
 823                 alarm.time = rtc_ktime_to_tm(timer->node.expires);
 824                 alarm.enabled = 1;
 825                 err = __rtc_set_alarm(rtc, &alarm);
 826                 if (err == -ETIME) {
 827                         pm_stay_awake(rtc->dev.parent);
 828                         schedule_work(&rtc->irqwork);
 829                 } else if (err) {
 830                         timerqueue_del(&rtc->timerqueue, &timer->node);
 831                         trace_rtc_timer_dequeue(timer);
 832                         timer->enabled = 0;
 833                         return err;
 834                 }
 835         }
 836         return 0;
 837 }
 838
 839 static void rtc_alarm_disable(struct rtc_device *rtc)
 840 {
 841         if (!rtc->ops || !rtc->ops->alarm_irq_enable)
 842                 return;
 843
 844         rtc->ops->alarm_irq_enable(rtc->dev.parent, false);
 845         trace_rtc_alarm_irq_enable(0, 0);
 846 }
 847
 848 /**
 849  * rtc_timer_remove - Removes a rtc_timer from the rtc_device timerqueue
 850  * @rtc rtc device
 851  * @timer timer being removed.
 852  *
 853  * Removes a timer onto the rtc devices timerqueue and sets
 854  * the next alarm event appropriately.
 855  *
 856  * Clears the enabled bit on the removed timer.
 857  *
 858  * Must hold ops_lock for proper serialization of timerqueue
 859  */
 860 static void rtc_timer_remove(struct rtc_device *rtc, struct rtc_timer *timer)
 861 {
 862         struct timerqueue_node *next = timerqueue_getnext(&rtc->timerqueue);
 863         timerqueue_del(&rtc->timerqueue, &timer->node);
 864         trace_rtc_timer_dequeue(timer);
 865         timer->enabled = 0;
 866         if (next == &timer->node) {
 867                 struct rtc_wkalrm alarm;
 868                 int err;
 869                 next = timerqueue_getnext(&rtc->timerqueue);
 870                 if (!next) {
 871                         rtc_alarm_disable(rtc);
 872                         return;
 873                 }
 874                 alarm.time = rtc_ktime_to_tm(next->expires);
 875                 alarm.enabled = 1;
 876                 err = __rtc_set_alarm(rtc, &alarm);
 877                 if (err == -ETIME) {
 878                         pm_stay_awake(rtc->dev.parent);
 879                         schedule_work(&rtc->irqwork);
 880                 }
 881         }
 882 }
 883
 884 /**
 885  * rtc_timer_do_work - Expires rtc timers
 886  * @rtc rtc device
 887  * @timer timer being removed.
 888  *
 889  * Expires rtc timers. Reprograms next alarm event if needed.
 890  * Called via worktask.
 891  *
 892  * Serializes access to timerqueue via ops_lock mutex
 893  */
 894 void rtc_timer_do_work(struct work_struct *work)
 895 {
 896         struct rtc_timer *timer;
 897         struct timerqueue_node *next;
 898         ktime_t now;
 899         struct rtc_time tm;
 900
 901         struct rtc_device *rtc =
 902                 container_of(work, struct rtc_device, irqwork);
 903
 904         mutex_lock(&rtc->ops_lock);
 905 again:
 906         __rtc_read_time(rtc, &tm);
 907         now = rtc_tm_to_ktime(tm);
 908         while ((next = timerqueue_getnext(&rtc->timerqueue))) {
 909                 if (next->expires > now)
 910                         break;
 911
 912                 /* expire timer */
 913                 timer = container_of(next, struct rtc_timer, node);
 914                 timerqueue_del(&rtc->timerqueue, &timer->node);
 915                 trace_rtc_timer_dequeue(timer);
 916                 timer->enabled = 0;
 917                 if (timer->func)
 918                         timer->func(timer->private_data);
 919
 920                 trace_rtc_timer_fired(timer);
 921                 /* Re-add/fwd periodic timers */
 922                 if (ktime_to_ns(timer->period)) {
 923                         timer->node.expires = ktime_add(timer->node.expires,
 924                                                         timer->period);
 925                         timer->enabled = 1;
 926                         timerqueue_add(&rtc->timerqueue, &timer->node);
 927                         trace_rtc_timer_enqueue(timer);
 928                 }
 929         }
 930
 931         /* Set next alarm */
 932         if (next) {
 933                 struct rtc_wkalrm alarm;
 934                 int err;
 935                 int retry = 3;
 936
 937                 alarm.time = rtc_ktime_to_tm(next->expires);
 938                 alarm.enabled = 1;
 939 reprogram:
 940                 err = __rtc_set_alarm(rtc, &alarm);
 941                 if (err == -ETIME)
 942                         goto again;
 943                 else if (err) {
 944                         if (retry-- > 0)
 945                                 goto reprogram;
 946
 947                         timer = container_of(next, struct rtc_timer, node);
 948                         timerqueue_del(&rtc->timerqueue, &timer->node);
 949                         trace_rtc_timer_dequeue(timer);
 950                         timer->enabled = 0;
 951                         dev_err(&rtc->dev, "__rtc_set_alarm: err=%d\n", err);
 952                         goto again;
 953                 }
 954         } else
 955                 rtc_alarm_disable(rtc);
 956
 957         pm_relax(rtc->dev.parent);
 958         mutex_unlock(&rtc->ops_lock);
 959 }
 960
 961
 962 /* rtc_timer_init - Initializes an rtc_timer
 963  * @timer: timer to be intiialized
 964  * @f: function pointer to be called when timer fires
 965  * @data: private data passed to function pointer
 966  *
 967  * Kernel interface to initializing an rtc_timer.
 968  */
 969 void rtc_timer_init(struct rtc_timer *timer, void (*f)(void *p), void *data)
 970 {
 971         timerqueue_init(&timer->node);
 972         timer->enabled = 0;
 973         timer->func = f;
 974         timer->private_data = data;
 975 }
 976
 977 /* rtc_timer_start - Sets an rtc_timer to fire in the future
 978  * @ rtc: rtc device to be used
 979  * @ timer: timer being set
 980  * @ expires: time at which to expire the timer
 981  * @ period: period that the timer will recur
 982  *
 983  * Kernel interface to set an rtc_timer
 984  */
 985 int rtc_timer_start(struct rtc_device *rtc, struct rtc_timer *timer,
 986                         ktime_t expires, ktime_t period)
 987 {
 988         int ret = 0;
 989         mutex_lock(&rtc->ops_lock);
 990         if (timer->enabled)
 991                 rtc_timer_remove(rtc, timer);
 992
 993         timer->node.expires = expires;
 994         timer->period = period;
 995
 996         ret = rtc_timer_enqueue(rtc, timer);
 997
 998         mutex_unlock(&rtc->ops_lock);
 999         return ret;
1000 }
1001
1002 /* rtc_timer_cancel - Stops an rtc_timer
1003  * @ rtc: rtc device to be used
1004  * @ timer: timer being set
1005  *
1006  * Kernel interface to cancel an rtc_timer
1007  */
1008 void rtc_timer_cancel(struct rtc_device *rtc, struct rtc_timer *timer)
1009 {
1010         mutex_lock(&rtc->ops_lock);
1011         if (timer->enabled)
1012                 rtc_timer_remove(rtc, timer);
1013         mutex_unlock(&rtc->ops_lock);
1014 }
1015
1016 /**
1017  * rtc_read_offset - Read the amount of rtc offset in parts per billion
1018  * @ rtc: rtc device to be used
1019  * @ offset: the offset in parts per billion
1020  *
1021  * see below for details.
1022  *
1023  * Kernel interface to read rtc clock offset
1024  * Returns 0 on success, or a negative number on error.
1025  * If read_offset() is not implemented for the rtc, return -EINVAL
1026  */
1027 int rtc_read_offset(struct rtc_device *rtc, long *offset)
1028 {
1029         int ret;
1030
1031         if (!rtc->ops)
1032                 return -ENODEV;
1033
1034         if (!rtc->ops->read_offset)
1035                 return -EINVAL;
1036
1037         mutex_lock(&rtc->ops_lock);
1038         ret = rtc->ops->read_offset(rtc->dev.parent, offset);
1039         mutex_unlock(&rtc->ops_lock);
1040
1041         trace_rtc_read_offset(*offset, ret);
1042         return ret;
1043 }
1044
1045 /**
1046  * rtc_set_offset - Adjusts the duration of the average second
1047  * @ rtc: rtc device to be used
1048  * @ offset: the offset in parts per billion
1049  *
1050  * Some rtc's allow an adjustment to the average duration of a second
1051  * to compensate for differences in the actual clock rate due to temperature,
1052  * the crystal, capacitor, etc.
1053  *
1054  * The adjustment applied is as follows:
1055  *   t = t0 * (1 + offset * 1e-9)
1056  * where t0 is the measured length of 1 RTC second with offset = 0
1057  *
1058  * Kernel interface to adjust an rtc clock offset.
1059  * Return 0 on success, or a negative number on error.
1060  * If the rtc offset is not setable (or not implemented), return -EINVAL
1061  */
1062 int rtc_set_offset(struct rtc_device *rtc, long offset)
1063 {
1064         int ret;
1065
1066         if (!rtc->ops)
1067                 return -ENODEV;
1068
1069         if (!rtc->ops->set_offset)
1070                 return -EINVAL;
1071
1072         mutex_lock(&rtc->ops_lock);
1073         ret = rtc->ops->set_offset(rtc->dev.parent, offset);
1074         mutex_unlock(&rtc->ops_lock);
1075
1076         trace_rtc_set_offset(offset, ret);
1077         return ret;
1078 }