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: %ptR\n", &alarm->time);
 373
 374         return err;
 375 }
 376
 377 int rtc_read_alarm(struct rtc_device *rtc, struct rtc_wkalrm *alarm)
 378 {
 379         int err;
 380
 381         err = mutex_lock_interruptible(&rtc->ops_lock);
 382         if (err)
 383                 return err;
 384         if (rtc->ops == NULL)
 385                 err = -ENODEV;
 386         else if (!rtc->ops->read_alarm)
 387                 err = -EINVAL;
 388         else {
 389                 memset(alarm, 0, sizeof(struct rtc_wkalrm));
 390                 alarm->enabled = rtc->aie_timer.enabled;
 391                 alarm->time = rtc_ktime_to_tm(rtc->aie_timer.node.expires);
 392         }
 393         mutex_unlock(&rtc->ops_lock);
 394
 395         trace_rtc_read_alarm(rtc_tm_to_time64(&alarm->time), err);
 396         return err;
 397 }
 398 EXPORT_SYMBOL_GPL(rtc_read_alarm);
 399
 400 static int __rtc_set_alarm(struct rtc_device *rtc, struct rtc_wkalrm *alarm)
 401 {
 402         struct rtc_time tm;
 403         time64_t now, scheduled;
 404         int err;
 405
 406         err = rtc_valid_tm(&alarm->time);
 407         if (err)
 408                 return err;
 409
 410         scheduled = rtc_tm_to_time64(&alarm->time);
 411
 412         /* Make sure we're not setting alarms in the past */
 413         err = __rtc_read_time(rtc, &tm);
 414         if (err)
 415                 return err;
 416         now = rtc_tm_to_time64(&tm);
 417         if (scheduled <= now)
 418                 return -ETIME;
 419         /*
 420          * XXX - We just checked to make sure the alarm time is not
 421          * in the past, but there is still a race window where if
 422          * the is alarm set for the next second and the second ticks
 423          * over right here, before we set the alarm.
 424          */
 425
 426         rtc_subtract_offset(rtc, &alarm->time);
 427
 428         if (!rtc->ops)
 429                 err = -ENODEV;
 430         else if (!rtc->ops->set_alarm)
 431                 err = -EINVAL;
 432         else
 433                 err = rtc->ops->set_alarm(rtc->dev.parent, alarm);
 434
 435         trace_rtc_set_alarm(rtc_tm_to_time64(&alarm->time), err);
 436         return err;
 437 }
 438
 439 int rtc_set_alarm(struct rtc_device *rtc, struct rtc_wkalrm *alarm)
 440 {
 441         int err;
 442
 443         if (!rtc->ops)
 444                 return -ENODEV;
 445         else if (!rtc->ops->set_alarm)
 446                 return -EINVAL;
 447
 448         err = rtc_valid_tm(&alarm->time);
 449         if (err != 0)
 450                 return err;
 451
 452         err = rtc_valid_range(rtc, &alarm->time);
 453         if (err)
 454                 return err;
 455
 456         err = mutex_lock_interruptible(&rtc->ops_lock);
 457         if (err)
 458                 return err;
 459         if (rtc->aie_timer.enabled)
 460                 rtc_timer_remove(rtc, &rtc->aie_timer);
 461
 462         rtc->aie_timer.node.expires = rtc_tm_to_ktime(alarm->time);
 463         rtc->aie_timer.period = 0;
 464         if (alarm->enabled)
 465                 err = rtc_timer_enqueue(rtc, &rtc->aie_timer);
 466
 467         mutex_unlock(&rtc->ops_lock);
 468
 469         return err;
 470 }
 471 EXPORT_SYMBOL_GPL(rtc_set_alarm);
 472
 473 /* Called once per device from rtc_device_register */
 474 int rtc_initialize_alarm(struct rtc_device *rtc, struct rtc_wkalrm *alarm)
 475 {
 476         int err;
 477         struct rtc_time now;
 478
 479         err = rtc_valid_tm(&alarm->time);
 480         if (err != 0)
 481                 return err;
 482
 483         err = rtc_read_time(rtc, &now);
 484         if (err)
 485                 return err;
 486
 487         err = mutex_lock_interruptible(&rtc->ops_lock);
 488         if (err)
 489                 return err;
 490
 491         rtc->aie_timer.node.expires = rtc_tm_to_ktime(alarm->time);
 492         rtc->aie_timer.period = 0;
 493
 494         /* Alarm has to be enabled & in the future for us to enqueue it */
 495         if (alarm->enabled && (rtc_tm_to_ktime(now) <
 496                          rtc->aie_timer.node.expires)) {
 497
 498                 rtc->aie_timer.enabled = 1;
 499                 timerqueue_add(&rtc->timerqueue, &rtc->aie_timer.node);
 500                 trace_rtc_timer_enqueue(&rtc->aie_timer);
 501         }
 502         mutex_unlock(&rtc->ops_lock);
 503         return err;
 504 }
 505 EXPORT_SYMBOL_GPL(rtc_initialize_alarm);
 506
 507 int rtc_alarm_irq_enable(struct rtc_device *rtc, unsigned int enabled)
 508 {
 509         int err = mutex_lock_interruptible(&rtc->ops_lock);
 510         if (err)
 511                 return err;
 512
 513         if (rtc->aie_timer.enabled != enabled) {
 514                 if (enabled)
 515                         err = rtc_timer_enqueue(rtc, &rtc->aie_timer);
 516                 else
 517                         rtc_timer_remove(rtc, &rtc->aie_timer);
 518         }
 519
 520         if (err)
 521                 /* nothing */;
 522         else if (!rtc->ops)
 523                 err = -ENODEV;
 524         else if (!rtc->ops->alarm_irq_enable)
 525                 err = -EINVAL;
 526         else
 527                 err = rtc->ops->alarm_irq_enable(rtc->dev.parent, enabled);
 528
 529         mutex_unlock(&rtc->ops_lock);
 530
 531         trace_rtc_alarm_irq_enable(enabled, err);
 532         return err;
 533 }
 534 EXPORT_SYMBOL_GPL(rtc_alarm_irq_enable);
 535
 536 int rtc_update_irq_enable(struct rtc_device *rtc, unsigned int enabled)
 537 {
 538         int err = mutex_lock_interruptible(&rtc->ops_lock);
 539         if (err)
 540                 return err;
 541
 542 #ifdef CONFIG_RTC_INTF_DEV_UIE_EMUL
 543         if (enabled == 0 && rtc->uie_irq_active) {
 544                 mutex_unlock(&rtc->ops_lock);
 545                 return rtc_dev_update_irq_enable_emul(rtc, 0);
 546         }
 547 #endif
 548         /* make sure we're changing state */
 549         if (rtc->uie_rtctimer.enabled == enabled)
 550                 goto out;
 551
 552         if (rtc->uie_unsupported) {
 553                 err = -EINVAL;
 554                 goto out;
 555         }
 556
 557         if (enabled) {
 558                 struct rtc_time tm;
 559                 ktime_t now, onesec;
 560
 561                 __rtc_read_time(rtc, &tm);
 562                 onesec = ktime_set(1, 0);
 563                 now = rtc_tm_to_ktime(tm);
 564                 rtc->uie_rtctimer.node.expires = ktime_add(now, onesec);
 565                 rtc->uie_rtctimer.period = ktime_set(1, 0);
 566                 err = rtc_timer_enqueue(rtc, &rtc->uie_rtctimer);
 567         } else
 568                 rtc_timer_remove(rtc, &rtc->uie_rtctimer);
 569
 570 out:
 571         mutex_unlock(&rtc->ops_lock);
 572 #ifdef CONFIG_RTC_INTF_DEV_UIE_EMUL
 573         /*
 574          * Enable emulation if the driver did not provide
 575          * the update_irq_enable function pointer or if returned
 576          * -EINVAL to signal that it has been configured without
 577          * interrupts or that are not available at the moment.
 578          */
 579         if (err == -EINVAL)
 580                 err = rtc_dev_update_irq_enable_emul(rtc, enabled);
 581 #endif
 582         return err;
 583
 584 }
 585 EXPORT_SYMBOL_GPL(rtc_update_irq_enable);
 586
 587
 588 /**
 589  * rtc_handle_legacy_irq - AIE, UIE and PIE event hook
 590  * @rtc: pointer to the rtc device
 591  *
 592  * This function is called when an AIE, UIE or PIE mode interrupt
 593  * has occurred (or been emulated).
 594  *
 595  */
 596 void rtc_handle_legacy_irq(struct rtc_device *rtc, int num, int mode)
 597 {
 598         unsigned long flags;
 599
 600         /* mark one irq of the appropriate mode */
 601         spin_lock_irqsave(&rtc->irq_lock, flags);
 602         rtc->irq_data = (rtc->irq_data + (num << 8)) | (RTC_IRQF|mode);
 603         spin_unlock_irqrestore(&rtc->irq_lock, flags);
 604
 605         wake_up_interruptible(&rtc->irq_queue);
 606         kill_fasync(&rtc->async_queue, SIGIO, POLL_IN);
 607 }
 608
 609
 610 /**
 611  * rtc_aie_update_irq - AIE mode rtctimer hook
 612  * @rtc: pointer to the rtc_device
 613  *
 614  * This functions is called when the aie_timer expires.
 615  */
 616 void rtc_aie_update_irq(struct rtc_device *rtc)
 617 {
 618         rtc_handle_legacy_irq(rtc, 1, RTC_AF);
 619 }
 620
 621
 622 /**
 623  * rtc_uie_update_irq - UIE mode rtctimer hook
 624  * @rtc: pointer to the rtc_device
 625  *
 626  * This functions is called when the uie_timer expires.
 627  */
 628 void rtc_uie_update_irq(struct rtc_device *rtc)
 629 {
 630         rtc_handle_legacy_irq(rtc, 1,  RTC_UF);
 631 }
 632
 633
 634 /**
 635  * rtc_pie_update_irq - PIE mode hrtimer hook
 636  * @timer: pointer to the pie mode hrtimer
 637  *
 638  * This function is used to emulate PIE mode interrupts
 639  * using an hrtimer. This function is called when the periodic
 640  * hrtimer expires.
 641  */
 642 enum hrtimer_restart rtc_pie_update_irq(struct hrtimer *timer)
 643 {
 644         struct rtc_device *rtc;
 645         ktime_t period;
 646         int count;
 647         rtc = container_of(timer, struct rtc_device, pie_timer);
 648
 649         period = NSEC_PER_SEC / rtc->irq_freq;
 650         count = hrtimer_forward_now(timer, period);
 651
 652         rtc_handle_legacy_irq(rtc, count, RTC_PF);
 653
 654         return HRTIMER_RESTART;
 655 }
 656
 657 /**
 658  * rtc_update_irq - Triggered when a RTC interrupt occurs.
 659  * @rtc: the rtc device
 660  * @num: how many irqs are being reported (usually one)
 661  * @events: mask of RTC_IRQF with one or more of RTC_PF, RTC_AF, RTC_UF
 662  * Context: any
 663  */
 664 void rtc_update_irq(struct rtc_device *rtc,
 665                 unsigned long num, unsigned long events)
 666 {
 667         if (IS_ERR_OR_NULL(rtc))
 668                 return;
 669
 670         pm_stay_awake(rtc->dev.parent);
 671         schedule_work(&rtc->irqwork);
 672 }
 673 EXPORT_SYMBOL_GPL(rtc_update_irq);
 674
 675 static int __rtc_match(struct device *dev, const void *data)
 676 {
 677         const char *name = data;
 678
 679         if (strcmp(dev_name(dev), name) == 0)
 680                 return 1;
 681         return 0;
 682 }
 683
 684 struct rtc_device *rtc_class_open(const char *name)
 685 {
 686         struct device *dev;
 687         struct rtc_device *rtc = NULL;
 688
 689         dev = class_find_device(rtc_class, NULL, name, __rtc_match);
 690         if (dev)
 691                 rtc = to_rtc_device(dev);
 692
 693         if (rtc) {
 694                 if (!try_module_get(rtc->owner)) {
 695                         put_device(dev);
 696                         rtc = NULL;
 697                 }
 698         }
 699
 700         return rtc;
 701 }
 702 EXPORT_SYMBOL_GPL(rtc_class_open);
 703
 704 void rtc_class_close(struct rtc_device *rtc)
 705 {
 706         module_put(rtc->owner);
 707         put_device(&rtc->dev);
 708 }
 709 EXPORT_SYMBOL_GPL(rtc_class_close);
 710
 711 static int rtc_update_hrtimer(struct rtc_device *rtc, int enabled)
 712 {
 713         /*
 714          * We always cancel the timer here first, because otherwise
 715          * we could run into BUG_ON(timer->state != HRTIMER_STATE_CALLBACK);
 716          * when we manage to start the timer before the callback
 717          * returns HRTIMER_RESTART.
 718          *
 719          * We cannot use hrtimer_cancel() here as a running callback
 720          * could be blocked on rtc->irq_task_lock and hrtimer_cancel()
 721          * would spin forever.
 722          */
 723         if (hrtimer_try_to_cancel(&rtc->pie_timer) < 0)
 724                 return -1;
 725
 726         if (enabled) {
 727                 ktime_t period = NSEC_PER_SEC / rtc->irq_freq;
 728
 729                 hrtimer_start(&rtc->pie_timer, period, HRTIMER_MODE_REL);
 730         }
 731         return 0;
 732 }
 733
 734 /**
 735  * rtc_irq_set_state - enable/disable 2^N Hz periodic IRQs
 736  * @rtc: the rtc device
 737  * @enabled: true to enable periodic IRQs
 738  * Context: any
 739  *
 740  * Note that rtc_irq_set_freq() should previously have been used to
 741  * specify the desired frequency of periodic IRQ.
 742  */
 743 int rtc_irq_set_state(struct rtc_device *rtc, int enabled)
 744 {
 745         int err = 0;
 746
 747         while (rtc_update_hrtimer(rtc, enabled) < 0)
 748                 cpu_relax();
 749
 750         rtc->pie_enabled = enabled;
 751
 752         trace_rtc_irq_set_state(enabled, err);
 753         return err;
 754 }
 755
 756 /**
 757  * rtc_irq_set_freq - set 2^N Hz periodic IRQ frequency for IRQ
 758  * @rtc: the rtc device
 759  * @freq: positive frequency
 760  * Context: any
 761  *
 762  * Note that rtc_irq_set_state() is used to enable or disable the
 763  * periodic IRQs.
 764  */
 765 int rtc_irq_set_freq(struct rtc_device *rtc, int freq)
 766 {
 767         int err = 0;
 768
 769         if (freq <= 0 || freq > RTC_MAX_FREQ)
 770                 return -EINVAL;
 771
 772         rtc->irq_freq = freq;
 773         while (rtc->pie_enabled && rtc_update_hrtimer(rtc, 1) < 0)
 774                 cpu_relax();
 775
 776         trace_rtc_irq_set_freq(freq, err);
 777         return err;
 778 }
 779
 780 /**
 781  * rtc_timer_enqueue - Adds a rtc_timer to the rtc_device timerqueue
 782  * @rtc rtc device
 783  * @timer timer being added.
 784  *
 785  * Enqueues a timer onto the rtc devices timerqueue and sets
 786  * the next alarm event appropriately.
 787  *
 788  * Sets the enabled bit on the added timer.
 789  *
 790  * Must hold ops_lock for proper serialization of timerqueue
 791  */
 792 static int rtc_timer_enqueue(struct rtc_device *rtc, struct rtc_timer *timer)
 793 {
 794         struct timerqueue_node *next = timerqueue_getnext(&rtc->timerqueue);
 795         struct rtc_time tm;
 796         ktime_t now;
 797
 798         timer->enabled = 1;
 799         __rtc_read_time(rtc, &tm);
 800         now = rtc_tm_to_ktime(tm);
 801
 802         /* Skip over expired timers */
 803         while (next) {
 804                 if (next->expires >= now)
 805                         break;
 806                 next = timerqueue_iterate_next(next);
 807         }
 808
 809         timerqueue_add(&rtc->timerqueue, &timer->node);
 810         trace_rtc_timer_enqueue(timer);
 811         if (!next || ktime_before(timer->node.expires, next->expires)) {
 812                 struct rtc_wkalrm alarm;
 813                 int err;
 814                 alarm.time = rtc_ktime_to_tm(timer->node.expires);
 815                 alarm.enabled = 1;
 816                 err = __rtc_set_alarm(rtc, &alarm);
 817                 if (err == -ETIME) {
 818                         pm_stay_awake(rtc->dev.parent);
 819                         schedule_work(&rtc->irqwork);
 820                 } else if (err) {
 821                         timerqueue_del(&rtc->timerqueue, &timer->node);
 822                         trace_rtc_timer_dequeue(timer);
 823                         timer->enabled = 0;
 824                         return err;
 825                 }
 826         }
 827         return 0;
 828 }
 829
 830 static void rtc_alarm_disable(struct rtc_device *rtc)
 831 {
 832         if (!rtc->ops || !rtc->ops->alarm_irq_enable)
 833                 return;
 834
 835         rtc->ops->alarm_irq_enable(rtc->dev.parent, false);
 836         trace_rtc_alarm_irq_enable(0, 0);
 837 }
 838
 839 /**
 840  * rtc_timer_remove - Removes a rtc_timer from the rtc_device timerqueue
 841  * @rtc rtc device
 842  * @timer timer being removed.
 843  *
 844  * Removes a timer onto the rtc devices timerqueue and sets
 845  * the next alarm event appropriately.
 846  *
 847  * Clears the enabled bit on the removed timer.
 848  *
 849  * Must hold ops_lock for proper serialization of timerqueue
 850  */
 851 static void rtc_timer_remove(struct rtc_device *rtc, struct rtc_timer *timer)
 852 {
 853         struct timerqueue_node *next = timerqueue_getnext(&rtc->timerqueue);
 854         timerqueue_del(&rtc->timerqueue, &timer->node);
 855         trace_rtc_timer_dequeue(timer);
 856         timer->enabled = 0;
 857         if (next == &timer->node) {
 858                 struct rtc_wkalrm alarm;
 859                 int err;
 860                 next = timerqueue_getnext(&rtc->timerqueue);
 861                 if (!next) {
 862                         rtc_alarm_disable(rtc);
 863                         return;
 864                 }
 865                 alarm.time = rtc_ktime_to_tm(next->expires);
 866                 alarm.enabled = 1;
 867                 err = __rtc_set_alarm(rtc, &alarm);
 868                 if (err == -ETIME) {
 869                         pm_stay_awake(rtc->dev.parent);
 870                         schedule_work(&rtc->irqwork);
 871                 }
 872         }
 873 }
 874
 875 /**
 876  * rtc_timer_do_work - Expires rtc timers
 877  * @rtc rtc device
 878  * @timer timer being removed.
 879  *
 880  * Expires rtc timers. Reprograms next alarm event if needed.
 881  * Called via worktask.
 882  *
 883  * Serializes access to timerqueue via ops_lock mutex
 884  */
 885 void rtc_timer_do_work(struct work_struct *work)
 886 {
 887         struct rtc_timer *timer;
 888         struct timerqueue_node *next;
 889         ktime_t now;
 890         struct rtc_time tm;
 891
 892         struct rtc_device *rtc =
 893                 container_of(work, struct rtc_device, irqwork);
 894
 895         mutex_lock(&rtc->ops_lock);
 896 again:
 897         __rtc_read_time(rtc, &tm);
 898         now = rtc_tm_to_ktime(tm);
 899         while ((next = timerqueue_getnext(&rtc->timerqueue))) {
 900                 if (next->expires > now)
 901                         break;
 902
 903                 /* expire timer */
 904                 timer = container_of(next, struct rtc_timer, node);
 905                 timerqueue_del(&rtc->timerqueue, &timer->node);
 906                 trace_rtc_timer_dequeue(timer);
 907                 timer->enabled = 0;
 908                 if (timer->func)
 909                         timer->func(timer->rtc);
 910
 911                 trace_rtc_timer_fired(timer);
 912                 /* Re-add/fwd periodic timers */
 913                 if (ktime_to_ns(timer->period)) {
 914                         timer->node.expires = ktime_add(timer->node.expires,
 915                                                         timer->period);
 916                         timer->enabled = 1;
 917                         timerqueue_add(&rtc->timerqueue, &timer->node);
 918                         trace_rtc_timer_enqueue(timer);
 919                 }
 920         }
 921
 922         /* Set next alarm */
 923         if (next) {
 924                 struct rtc_wkalrm alarm;
 925                 int err;
 926                 int retry = 3;
 927
 928                 alarm.time = rtc_ktime_to_tm(next->expires);
 929                 alarm.enabled = 1;
 930 reprogram:
 931                 err = __rtc_set_alarm(rtc, &alarm);
 932                 if (err == -ETIME)
 933                         goto again;
 934                 else if (err) {
 935                         if (retry-- > 0)
 936                                 goto reprogram;
 937
 938                         timer = container_of(next, struct rtc_timer, node);
 939                         timerqueue_del(&rtc->timerqueue, &timer->node);
 940                         trace_rtc_timer_dequeue(timer);
 941                         timer->enabled = 0;
 942                         dev_err(&rtc->dev, "__rtc_set_alarm: err=%d\n", err);
 943                         goto again;
 944                 }
 945         } else
 946                 rtc_alarm_disable(rtc);
 947
 948         pm_relax(rtc->dev.parent);
 949         mutex_unlock(&rtc->ops_lock);
 950 }
 951
 952
 953 /* rtc_timer_init - Initializes an rtc_timer
 954  * @timer: timer to be intiialized
 955  * @f: function pointer to be called when timer fires
 956  * @rtc: pointer to the rtc_device
 957  *
 958  * Kernel interface to initializing an rtc_timer.
 959  */
 960 void rtc_timer_init(struct rtc_timer *timer, void (*f)(struct rtc_device *r),
 961                     struct rtc_device *rtc)
 962 {
 963         timerqueue_init(&timer->node);
 964         timer->enabled = 0;
 965         timer->func = f;
 966         timer->rtc = rtc;
 967 }
 968
 969 /* rtc_timer_start - Sets an rtc_timer to fire in the future
 970  * @ rtc: rtc device to be used
 971  * @ timer: timer being set
 972  * @ expires: time at which to expire the timer
 973  * @ period: period that the timer will recur
 974  *
 975  * Kernel interface to set an rtc_timer
 976  */
 977 int rtc_timer_start(struct rtc_device *rtc, struct rtc_timer *timer,
 978                         ktime_t expires, ktime_t period)
 979 {
 980         int ret = 0;
 981         mutex_lock(&rtc->ops_lock);
 982         if (timer->enabled)
 983                 rtc_timer_remove(rtc, timer);
 984
 985         timer->node.expires = expires;
 986         timer->period = period;
 987
 988         ret = rtc_timer_enqueue(rtc, timer);
 989
 990         mutex_unlock(&rtc->ops_lock);
 991         return ret;
 992 }
 993
 994 /* rtc_timer_cancel - Stops an rtc_timer
 995  * @ rtc: rtc device to be used
 996  * @ timer: timer being set
 997  *
 998  * Kernel interface to cancel an rtc_timer
 999  */
1000 void rtc_timer_cancel(struct rtc_device *rtc, struct rtc_timer *timer)
1001 {
1002         mutex_lock(&rtc->ops_lock);
1003         if (timer->enabled)
1004                 rtc_timer_remove(rtc, timer);
1005         mutex_unlock(&rtc->ops_lock);
1006 }
1007
1008 /**
1009  * rtc_read_offset - Read the amount of rtc offset in parts per billion
1010  * @ rtc: rtc device to be used
1011  * @ offset: the offset in parts per billion
1012  *
1013  * see below for details.
1014  *
1015  * Kernel interface to read rtc clock offset
1016  * Returns 0 on success, or a negative number on error.
1017  * If read_offset() is not implemented for the rtc, return -EINVAL
1018  */
1019 int rtc_read_offset(struct rtc_device *rtc, long *offset)
1020 {
1021         int ret;
1022
1023         if (!rtc->ops)
1024                 return -ENODEV;
1025
1026         if (!rtc->ops->read_offset)
1027                 return -EINVAL;
1028
1029         mutex_lock(&rtc->ops_lock);
1030         ret = rtc->ops->read_offset(rtc->dev.parent, offset);
1031         mutex_unlock(&rtc->ops_lock);
1032
1033         trace_rtc_read_offset(*offset, ret);
1034         return ret;
1035 }
1036
1037 /**
1038  * rtc_set_offset - Adjusts the duration of the average second
1039  * @ rtc: rtc device to be used
1040  * @ offset: the offset in parts per billion
1041  *
1042  * Some rtc's allow an adjustment to the average duration of a second
1043  * to compensate for differences in the actual clock rate due to temperature,
1044  * the crystal, capacitor, etc.
1045  *
1046  * The adjustment applied is as follows:
1047  *   t = t0 * (1 + offset * 1e-9)
1048  * where t0 is the measured length of 1 RTC second with offset = 0
1049  *
1050  * Kernel interface to adjust an rtc clock offset.
1051  * Return 0 on success, or a negative number on error.
1052  * If the rtc offset is not setable (or not implemented), return -EINVAL
1053  */
1054 int rtc_set_offset(struct rtc_device *rtc, long offset)
1055 {
1056         int ret;
1057
1058         if (!rtc->ops)
1059                 return -ENODEV;
1060
1061         if (!rtc->ops->set_offset)
1062                 return -EINVAL;
1063
1064         mutex_lock(&rtc->ops_lock);
1065         ret = rtc->ops->set_offset(rtc->dev.parent, offset);
1066         mutex_unlock(&rtc->ops_lock);
1067
1068         trace_rtc_set_offset(offset, ret);
1069         return ret;
1070 }