root/drivers/rtc/interface.c

DEFINITIONS

1. rtc_add_offset
2. rtc_subtract_offset
3. rtc_valid_range
4. __rtc_read_time
5. rtc_read_time
6. rtc_set_time
7. rtc_read_alarm_internal
8. __rtc_read_alarm
9. rtc_read_alarm
10. __rtc_set_alarm
11. rtc_set_alarm
12. rtc_initialize_alarm
13. rtc_alarm_irq_enable
14. rtc_update_irq_enable
15. rtc_handle_legacy_irq
16. rtc_aie_update_irq
17. rtc_uie_update_irq
18. rtc_pie_update_irq
19. rtc_update_irq
20. rtc_class_open
21. rtc_class_close
22. rtc_update_hrtimer
23. rtc_irq_set_state
24. rtc_irq_set_freq
25. rtc_timer_enqueue
26. rtc_alarm_disable
27. rtc_timer_remove
28. rtc_timer_do_work
29. rtc_timer_init
30. rtc_timer_start
31. rtc_timer_cancel
32. rtc_read_offset
33. rtc_set_offset

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * RTC subsystem, interface functions
   4  *
   5  * Copyright (C) 2005 Tower Technologies
   6  * Author: Alessandro Zummo <a.zummo@towertech.it>
   7  *
   8  * based on arch/arm/common/rtctime.c
   9  */
  10 
  11 #include <linux/rtc.h>
  12 #include <linux/sched.h>
  13 #include <linux/module.h>
  14 #include <linux/log2.h>
  15 #include <linux/workqueue.h>
  16 
  17 #define CREATE_TRACE_POINTS
  18 #include <trace/events/rtc.h>
  19 
  20 static int rtc_timer_enqueue(struct rtc_device *rtc, struct rtc_timer *timer);
  21 static void rtc_timer_remove(struct rtc_device *rtc, struct rtc_timer *timer);
  22 
  23 static void rtc_add_offset(struct rtc_device *rtc, struct rtc_time *tm)
  24 {
  25         time64_t secs;
  26 
  27         if (!rtc->offset_secs)
  28                 return;
  29 
  30         secs = rtc_tm_to_time64(tm);
  31 
  32         /*
  33          * Since the reading time values from RTC device are always in the RTC
  34          * original valid range, but we need to skip the overlapped region
  35          * between expanded range and original range, which is no need to add
  36          * the offset.
  37          */
  38         if ((rtc->start_secs > rtc->range_min && secs >= rtc->start_secs) ||
  39             (rtc->start_secs < rtc->range_min &&
  40              secs <= (rtc->start_secs + rtc->range_max - rtc->range_min)))
  41                 return;
  42 
  43         rtc_time64_to_tm(secs + rtc->offset_secs, tm);
  44 }
  45 
  46 static void rtc_subtract_offset(struct rtc_device *rtc, struct rtc_time *tm)
  47 {
  48         time64_t secs;
  49 
  50         if (!rtc->offset_secs)
  51                 return;
  52 
  53         secs = rtc_tm_to_time64(tm);
  54 
  55         /*
  56          * If the setting time values are in the valid range of RTC hardware
  57          * device, then no need to subtract the offset when setting time to RTC
  58          * device. Otherwise we need to subtract the offset to make the time
  59          * values are valid for RTC hardware device.
  60          */
  61         if (secs >= rtc->range_min && secs <= rtc->range_max)
  62                 return;
  63 
  64         rtc_time64_to_tm(secs - rtc->offset_secs, tm);
  65 }
  66 
  67 static int rtc_valid_range(struct rtc_device *rtc, struct rtc_time *tm)
  68 {
  69         if (rtc->range_min != rtc->range_max) {
  70                 time64_t time = rtc_tm_to_time64(tm);
  71                 time64_t range_min = rtc->set_start_time ? rtc->start_secs :
  72                         rtc->range_min;
  73                 time64_t range_max = rtc->set_start_time ?
  74                         (rtc->start_secs + rtc->range_max - rtc->range_min) :
  75                         rtc->range_max;
  76 
  77                 if (time < range_min || time > range_max)
  78                         return -ERANGE;
  79         }
  80 
  81         return 0;
  82 }
  83 
  84 static int __rtc_read_time(struct rtc_device *rtc, struct rtc_time *tm)
  85 {
  86         int err;
  87 
  88         if (!rtc->ops) {
  89                 err = -ENODEV;
  90         } else if (!rtc->ops->read_time) {
  91                 err = -EINVAL;
  92         } else {
  93                 memset(tm, 0, sizeof(struct rtc_time));
  94                 err = rtc->ops->read_time(rtc->dev.parent, tm);
  95                 if (err < 0) {
  96                         dev_dbg(&rtc->dev, "read_time: fail to read: %d\n",
  97                                 err);
  98                         return err;
  99                 }
 100 
 101                 rtc_add_offset(rtc, tm);
 102 
 103                 err = rtc_valid_tm(tm);
 104                 if (err < 0)
 105                         dev_dbg(&rtc->dev, "read_time: rtc_time isn't valid\n");
 106         }
 107         return err;
 108 }
 109 
 110 int rtc_read_time(struct rtc_device *rtc, struct rtc_time *tm)
 111 {
 112         int err;
 113 
 114         err = mutex_lock_interruptible(&rtc->ops_lock);
 115         if (err)
 116                 return err;
 117 
 118         err = __rtc_read_time(rtc, tm);
 119         mutex_unlock(&rtc->ops_lock);
 120 
 121         trace_rtc_read_time(rtc_tm_to_time64(tm), err);
 122         return err;
 123 }
 124 EXPORT_SYMBOL_GPL(rtc_read_time);
 125 
 126 int rtc_set_time(struct rtc_device *rtc, struct rtc_time *tm)
 127 {
 128         int err, uie;
 129 
 130         err = rtc_valid_tm(tm);
 131         if (err != 0)
 132                 return err;
 133 
 134         err = rtc_valid_range(rtc, tm);
 135         if (err)
 136                 return err;
 137 
 138         rtc_subtract_offset(rtc, tm);
 139 
 140 #ifdef CONFIG_RTC_INTF_DEV_UIE_EMUL
 141         uie = rtc->uie_rtctimer.enabled || rtc->uie_irq_active;
 142 #else
 143         uie = rtc->uie_rtctimer.enabled;
 144 #endif
 145         if (uie) {
 146                 err = rtc_update_irq_enable(rtc, 0);
 147                 if (err)
 148                         return err;
 149         }
 150 
 151         err = mutex_lock_interruptible(&rtc->ops_lock);
 152         if (err)
 153                 return err;
 154 
 155         if (!rtc->ops)
 156                 err = -ENODEV;
 157         else if (rtc->ops->set_time)
 158                 err = rtc->ops->set_time(rtc->dev.parent, tm);
 159         else
 160                 err = -EINVAL;
 161 
 162         pm_stay_awake(rtc->dev.parent);
 163         mutex_unlock(&rtc->ops_lock);
 164         /* A timer might have just expired */
 165         schedule_work(&rtc->irqwork);
 166 
 167         if (uie) {
 168                 err = rtc_update_irq_enable(rtc, 1);
 169                 if (err)
 170                         return err;
 171         }
 172 
 173         trace_rtc_set_time(rtc_tm_to_time64(tm), err);
 174         return err;
 175 }
 176 EXPORT_SYMBOL_GPL(rtc_set_time);
 177 
 178 static int rtc_read_alarm_internal(struct rtc_device *rtc,
 179                                    struct rtc_wkalrm *alarm)
 180 {
 181         int err;
 182 
 183         err = mutex_lock_interruptible(&rtc->ops_lock);
 184         if (err)
 185                 return err;
 186 
 187         if (!rtc->ops) {
 188                 err = -ENODEV;
 189         } else if (!rtc->ops->read_alarm) {
 190                 err = -EINVAL;
 191         } else {
 192                 alarm->enabled = 0;
 193                 alarm->pending = 0;
 194                 alarm->time.tm_sec = -1;
 195                 alarm->time.tm_min = -1;
 196                 alarm->time.tm_hour = -1;
 197                 alarm->time.tm_mday = -1;
 198                 alarm->time.tm_mon = -1;
 199                 alarm->time.tm_year = -1;
 200                 alarm->time.tm_wday = -1;
 201                 alarm->time.tm_yday = -1;
 202                 alarm->time.tm_isdst = -1;
 203                 err = rtc->ops->read_alarm(rtc->dev.parent, alarm);
 204         }
 205 
 206         mutex_unlock(&rtc->ops_lock);
 207 
 208         trace_rtc_read_alarm(rtc_tm_to_time64(&alarm->time), err);
 209         return err;
 210 }
 211 
 212 int __rtc_read_alarm(struct rtc_device *rtc, struct rtc_wkalrm *alarm)
 213 {
 214         int err;
 215         struct rtc_time before, now;
 216         int first_time = 1;
 217         time64_t t_now, t_alm;
 218         enum { none, day, month, year } missing = none;
 219         unsigned int days;
 220 
 221         /* The lower level RTC driver may return -1 in some fields,
 222          * creating invalid alarm->time values, for reasons like:
 223          *
 224          *   - The hardware may not be capable of filling them in;
 225          *     many alarms match only on time-of-day fields, not
 226          *     day/month/year calendar data.
 227          *
 228          *   - Some hardware uses illegal values as "wildcard" match
 229          *     values, which non-Linux firmware (like a BIOS) may try
 230          *     to set up as e.g. "alarm 15 minutes after each hour".
 231          *     Linux uses only oneshot alarms.
 232          *
 233          * When we see that here, we deal with it by using values from
 234          * a current RTC timestamp for any missing (-1) values.  The
 235          * RTC driver prevents "periodic alarm" modes.
 236          *
 237          * But this can be racey, because some fields of the RTC timestamp
 238          * may have wrapped in the interval since we read the RTC alarm,
 239          * which would lead to us inserting inconsistent values in place
 240          * of the -1 fields.
 241          *
 242          * Reading the alarm and timestamp in the reverse sequence
 243          * would have the same race condition, and not solve the issue.
 244          *
 245          * So, we must first read the RTC timestamp,
 246          * then read the RTC alarm value,
 247          * and then read a second RTC timestamp.
 248          *
 249          * If any fields of the second timestamp have changed
 250          * when compared with the first timestamp, then we know
 251          * our timestamp may be inconsistent with that used by
 252          * the low-level rtc_read_alarm_internal() function.
 253          *
 254          * So, when the two timestamps disagree, we just loop and do
 255          * the process again to get a fully consistent set of values.
 256          *
 257          * This could all instead be done in the lower level driver,
 258          * but since more than one lower level RTC implementation needs it,
 259          * then it's probably best best to do it here instead of there..
 260          */
 261 
 262         /* Get the "before" timestamp */
 263         err = rtc_read_time(rtc, &before);
 264         if (err < 0)
 265                 return err;
 266         do {
 267                 if (!first_time)
 268                         memcpy(&before, &now, sizeof(struct rtc_time));
 269                 first_time = 0;
 270 
 271                 /* get the RTC alarm values, which may be incomplete */
 272                 err = rtc_read_alarm_internal(rtc, alarm);
 273                 if (err)
 274                         return err;
 275 
 276                 /* full-function RTCs won't have such missing fields */
 277                 if (rtc_valid_tm(&alarm->time) == 0) {
 278                         rtc_add_offset(rtc, &alarm->time);
 279                         return 0;
 280                 }
 281 
 282                 /* get the "after" timestamp, to detect wrapped fields */
 283                 err = rtc_read_time(rtc, &now);
 284                 if (err < 0)
 285                         return err;
 286 
 287                 /* note that tm_sec is a "don't care" value here: */
 288         } while (before.tm_min  != now.tm_min ||
 289                  before.tm_hour != now.tm_hour ||
 290                  before.tm_mon  != now.tm_mon ||
 291                  before.tm_year != now.tm_year);
 292 
 293         /* Fill in the missing alarm fields using the timestamp; we
 294          * know there's at least one since alarm->time is invalid.
 295          */
 296         if (alarm->time.tm_sec == -1)
 297                 alarm->time.tm_sec = now.tm_sec;
 298         if (alarm->time.tm_min == -1)
 299                 alarm->time.tm_min = now.tm_min;
 300         if (alarm->time.tm_hour == -1)
 301                 alarm->time.tm_hour = now.tm_hour;
 302 
 303         /* For simplicity, only support date rollover for now */
 304         if (alarm->time.tm_mday < 1 || alarm->time.tm_mday > 31) {
 305                 alarm->time.tm_mday = now.tm_mday;
 306                 missing = day;
 307         }
 308         if ((unsigned int)alarm->time.tm_mon >= 12) {
 309                 alarm->time.tm_mon = now.tm_mon;
 310                 if (missing == none)
 311                         missing = month;
 312         }
 313         if (alarm->time.tm_year == -1) {
 314                 alarm->time.tm_year = now.tm_year;
 315                 if (missing == none)
 316                         missing = year;
 317         }
 318 
 319         /* Can't proceed if alarm is still invalid after replacing
 320          * missing fields.
 321          */
 322         err = rtc_valid_tm(&alarm->time);
 323         if (err)
 324                 goto done;
 325 
 326         /* with luck, no rollover is needed */
 327         t_now = rtc_tm_to_time64(&now);
 328         t_alm = rtc_tm_to_time64(&alarm->time);
 329         if (t_now < t_alm)
 330                 goto done;
 331 
 332         switch (missing) {
 333         /* 24 hour rollover ... if it's now 10am Monday, an alarm that
 334          * that will trigger at 5am will do so at 5am Tuesday, which
 335          * could also be in the next month or year.  This is a common
 336          * case, especially for PCs.
 337          */
 338         case day:
 339                 dev_dbg(&rtc->dev, "alarm rollover: %s\n", "day");
 340                 t_alm += 24 * 60 * 60;
 341                 rtc_time64_to_tm(t_alm, &alarm->time);
 342                 break;
 343 
 344         /* Month rollover ... if it's the 31th, an alarm on the 3rd will
 345          * be next month.  An alarm matching on the 30th, 29th, or 28th
 346          * may end up in the month after that!  Many newer PCs support
 347          * this type of alarm.
 348          */
 349         case month:
 350                 dev_dbg(&rtc->dev, "alarm rollover: %s\n", "month");
 351                 do {
 352                         if (alarm->time.tm_mon < 11) {
 353                                 alarm->time.tm_mon++;
 354                         } else {
 355                                 alarm->time.tm_mon = 0;
 356                                 alarm->time.tm_year++;
 357                         }
 358                         days = rtc_month_days(alarm->time.tm_mon,
 359                                               alarm->time.tm_year);
 360                 } while (days < alarm->time.tm_mday);
 361                 break;
 362 
 363         /* Year rollover ... easy except for leap years! */
 364         case year:
 365                 dev_dbg(&rtc->dev, "alarm rollover: %s\n", "year");
 366                 do {
 367                         alarm->time.tm_year++;
 368                 } while (!is_leap_year(alarm->time.tm_year + 1900) &&
 369                          rtc_valid_tm(&alarm->time) != 0);
 370                 break;
 371 
 372         default:
 373                 dev_warn(&rtc->dev, "alarm rollover not handled\n");
 374         }
 375 
 376         err = rtc_valid_tm(&alarm->time);
 377 
 378 done:
 379         if (err)
 380                 dev_warn(&rtc->dev, "invalid alarm value: %ptR\n",
 381                          &alarm->time);
 382 
 383         return err;
 384 }
 385 
 386 int rtc_read_alarm(struct rtc_device *rtc, struct rtc_wkalrm *alarm)
 387 {
 388         int err;
 389 
 390         err = mutex_lock_interruptible(&rtc->ops_lock);
 391         if (err)
 392                 return err;
 393         if (!rtc->ops) {
 394                 err = -ENODEV;
 395         } else if (!rtc->ops->read_alarm) {
 396                 err = -EINVAL;
 397         } else {
 398                 memset(alarm, 0, sizeof(struct rtc_wkalrm));
 399                 alarm->enabled = rtc->aie_timer.enabled;
 400                 alarm->time = rtc_ktime_to_tm(rtc->aie_timer.node.expires);
 401         }
 402         mutex_unlock(&rtc->ops_lock);
 403 
 404         trace_rtc_read_alarm(rtc_tm_to_time64(&alarm->time), err);
 405         return err;
 406 }
 407 EXPORT_SYMBOL_GPL(rtc_read_alarm);
 408 
 409 static int __rtc_set_alarm(struct rtc_device *rtc, struct rtc_wkalrm *alarm)
 410 {
 411         struct rtc_time tm;
 412         time64_t now, scheduled;
 413         int err;
 414 
 415         err = rtc_valid_tm(&alarm->time);
 416         if (err)
 417                 return err;
 418 
 419         scheduled = rtc_tm_to_time64(&alarm->time);
 420 
 421         /* Make sure we're not setting alarms in the past */
 422         err = __rtc_read_time(rtc, &tm);
 423         if (err)
 424                 return err;
 425         now = rtc_tm_to_time64(&tm);
 426         if (scheduled <= now)
 427                 return -ETIME;
 428         /*
 429          * XXX - We just checked to make sure the alarm time is not
 430          * in the past, but there is still a race window where if
 431          * the is alarm set for the next second and the second ticks
 432          * over right here, before we set the alarm.
 433          */
 434 
 435         rtc_subtract_offset(rtc, &alarm->time);
 436 
 437         if (!rtc->ops)
 438                 err = -ENODEV;
 439         else if (!rtc->ops->set_alarm)
 440                 err = -EINVAL;
 441         else
 442                 err = rtc->ops->set_alarm(rtc->dev.parent, alarm);
 443 
 444         trace_rtc_set_alarm(rtc_tm_to_time64(&alarm->time), err);
 445         return err;
 446 }
 447 
 448 int rtc_set_alarm(struct rtc_device *rtc, struct rtc_wkalrm *alarm)
 449 {
 450         int err;
 451 
 452         if (!rtc->ops)
 453                 return -ENODEV;
 454         else if (!rtc->ops->set_alarm)
 455                 return -EINVAL;
 456 
 457         err = rtc_valid_tm(&alarm->time);
 458         if (err != 0)
 459                 return err;
 460 
 461         err = rtc_valid_range(rtc, &alarm->time);
 462         if (err)
 463                 return err;
 464 
 465         err = mutex_lock_interruptible(&rtc->ops_lock);
 466         if (err)
 467                 return err;
 468         if (rtc->aie_timer.enabled)
 469                 rtc_timer_remove(rtc, &rtc->aie_timer);
 470 
 471         rtc->aie_timer.node.expires = rtc_tm_to_ktime(alarm->time);
 472         rtc->aie_timer.period = 0;
 473         if (alarm->enabled)
 474                 err = rtc_timer_enqueue(rtc, &rtc->aie_timer);
 475 
 476         mutex_unlock(&rtc->ops_lock);
 477 
 478         return err;
 479 }
 480 EXPORT_SYMBOL_GPL(rtc_set_alarm);
 481 
 482 /* Called once per device from rtc_device_register */
 483 int rtc_initialize_alarm(struct rtc_device *rtc, struct rtc_wkalrm *alarm)
 484 {
 485         int err;
 486         struct rtc_time now;
 487 
 488         err = rtc_valid_tm(&alarm->time);
 489         if (err != 0)
 490                 return err;
 491 
 492         err = rtc_read_time(rtc, &now);
 493         if (err)
 494                 return err;
 495 
 496         err = mutex_lock_interruptible(&rtc->ops_lock);
 497         if (err)
 498                 return err;
 499 
 500         rtc->aie_timer.node.expires = rtc_tm_to_ktime(alarm->time);
 501         rtc->aie_timer.period = 0;
 502 
 503         /* Alarm has to be enabled & in the future for us to enqueue it */
 504         if (alarm->enabled && (rtc_tm_to_ktime(now) <
 505                          rtc->aie_timer.node.expires)) {
 506                 rtc->aie_timer.enabled = 1;
 507                 timerqueue_add(&rtc->timerqueue, &rtc->aie_timer.node);
 508                 trace_rtc_timer_enqueue(&rtc->aie_timer);
 509         }
 510         mutex_unlock(&rtc->ops_lock);
 511         return err;
 512 }
 513 EXPORT_SYMBOL_GPL(rtc_initialize_alarm);
 514 
 515 int rtc_alarm_irq_enable(struct rtc_device *rtc, unsigned int enabled)
 516 {
 517         int err;
 518 
 519         err = mutex_lock_interruptible(&rtc->ops_lock);
 520         if (err)
 521                 return err;
 522 
 523         if (rtc->aie_timer.enabled != enabled) {
 524                 if (enabled)
 525                         err = rtc_timer_enqueue(rtc, &rtc->aie_timer);
 526                 else
 527                         rtc_timer_remove(rtc, &rtc->aie_timer);
 528         }
 529 
 530         if (err)
 531                 /* nothing */;
 532         else if (!rtc->ops)
 533                 err = -ENODEV;
 534         else if (!rtc->ops->alarm_irq_enable)
 535                 err = -EINVAL;
 536         else
 537                 err = rtc->ops->alarm_irq_enable(rtc->dev.parent, enabled);
 538 
 539         mutex_unlock(&rtc->ops_lock);
 540 
 541         trace_rtc_alarm_irq_enable(enabled, err);
 542         return err;
 543 }
 544 EXPORT_SYMBOL_GPL(rtc_alarm_irq_enable);
 545 
 546 int rtc_update_irq_enable(struct rtc_device *rtc, unsigned int enabled)
 547 {
 548         int err;
 549 
 550         err = mutex_lock_interruptible(&rtc->ops_lock);
 551         if (err)
 552                 return err;
 553 
 554 #ifdef CONFIG_RTC_INTF_DEV_UIE_EMUL
 555         if (enabled == 0 && rtc->uie_irq_active) {
 556                 mutex_unlock(&rtc->ops_lock);
 557                 return rtc_dev_update_irq_enable_emul(rtc, 0);
 558         }
 559 #endif
 560         /* make sure we're changing state */
 561         if (rtc->uie_rtctimer.enabled == enabled)
 562                 goto out;
 563 
 564         if (rtc->uie_unsupported) {
 565                 err = -EINVAL;
 566                 goto out;
 567         }
 568 
 569         if (enabled) {
 570                 struct rtc_time tm;
 571                 ktime_t now, onesec;
 572 
 573                 __rtc_read_time(rtc, &tm);
 574                 onesec = ktime_set(1, 0);
 575                 now = rtc_tm_to_ktime(tm);
 576                 rtc->uie_rtctimer.node.expires = ktime_add(now, onesec);
 577                 rtc->uie_rtctimer.period = ktime_set(1, 0);
 578                 err = rtc_timer_enqueue(rtc, &rtc->uie_rtctimer);
 579         } else {
 580                 rtc_timer_remove(rtc, &rtc->uie_rtctimer);
 581         }
 582 
 583 out:
 584         mutex_unlock(&rtc->ops_lock);
 585 #ifdef CONFIG_RTC_INTF_DEV_UIE_EMUL
 586         /*
 587          * Enable emulation if the driver returned -EINVAL to signal that it has
 588          * been configured without interrupts or they are not available at the
 589          * moment.
 590          */
 591         if (err == -EINVAL)
 592                 err = rtc_dev_update_irq_enable_emul(rtc, enabled);
 593 #endif
 594         return err;
 595 }
 596 EXPORT_SYMBOL_GPL(rtc_update_irq_enable);
 597 
 598 /**
 599  * rtc_handle_legacy_irq - AIE, UIE and PIE event hook
 600  * @rtc: pointer to the rtc device
 601  *
 602  * This function is called when an AIE, UIE or PIE mode interrupt
 603  * has occurred (or been emulated).
 604  *
 605  */
 606 void rtc_handle_legacy_irq(struct rtc_device *rtc, int num, int mode)
 607 {
 608         unsigned long flags;
 609 
 610         /* mark one irq of the appropriate mode */
 611         spin_lock_irqsave(&rtc->irq_lock, flags);
 612         rtc->irq_data = (rtc->irq_data + (num << 8)) | (RTC_IRQF | mode);
 613         spin_unlock_irqrestore(&rtc->irq_lock, flags);
 614 
 615         wake_up_interruptible(&rtc->irq_queue);
 616         kill_fasync(&rtc->async_queue, SIGIO, POLL_IN);
 617 }
 618 
 619 /**
 620  * rtc_aie_update_irq - AIE mode rtctimer hook
 621  * @rtc: pointer to the rtc_device
 622  *
 623  * This functions is called when the aie_timer expires.
 624  */
 625 void rtc_aie_update_irq(struct rtc_device *rtc)
 626 {
 627         rtc_handle_legacy_irq(rtc, 1, RTC_AF);
 628 }
 629 
 630 /**
 631  * rtc_uie_update_irq - UIE mode rtctimer hook
 632  * @rtc: pointer to the rtc_device
 633  *
 634  * This functions is called when the uie_timer expires.
 635  */
 636 void rtc_uie_update_irq(struct rtc_device *rtc)
 637 {
 638         rtc_handle_legacy_irq(rtc, 1,  RTC_UF);
 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         u64 count;
 654 
 655         rtc = container_of(timer, struct rtc_device, pie_timer);
 656 
 657         period = NSEC_PER_SEC / rtc->irq_freq;
 658         count = hrtimer_forward_now(timer, period);
 659 
 660         rtc_handle_legacy_irq(rtc, count, RTC_PF);
 661 
 662         return HRTIMER_RESTART;
 663 }
 664 
 665 /**
 666  * rtc_update_irq - Triggered when a RTC interrupt occurs.
 667  * @rtc: the rtc device
 668  * @num: how many irqs are being reported (usually one)
 669  * @events: mask of RTC_IRQF with one or more of RTC_PF, RTC_AF, RTC_UF
 670  * Context: any
 671  */
 672 void rtc_update_irq(struct rtc_device *rtc,
 673                     unsigned long num, unsigned long events)
 674 {
 675         if (IS_ERR_OR_NULL(rtc))
 676                 return;
 677 
 678         pm_stay_awake(rtc->dev.parent);
 679         schedule_work(&rtc->irqwork);
 680 }
 681 EXPORT_SYMBOL_GPL(rtc_update_irq);
 682 
 683 struct rtc_device *rtc_class_open(const char *name)
 684 {
 685         struct device *dev;
 686         struct rtc_device *rtc = NULL;
 687 
 688         dev = class_find_device_by_name(rtc_class, name);
 689         if (dev)
 690                 rtc = to_rtc_device(dev);
 691 
 692         if (rtc) {
 693                 if (!try_module_get(rtc->owner)) {
 694                         put_device(dev);
 695                         rtc = NULL;
 696                 }
 697         }
 698 
 699         return rtc;
 700 }
 701 EXPORT_SYMBOL_GPL(rtc_class_open);
 702 
 703 void rtc_class_close(struct rtc_device *rtc)
 704 {
 705         module_put(rtc->owner);
 706         put_device(&rtc->dev);
 707 }
 708 EXPORT_SYMBOL_GPL(rtc_class_close);
 709 
 710 static int rtc_update_hrtimer(struct rtc_device *rtc, int enabled)
 711 {
 712         /*
 713          * We always cancel the timer here first, because otherwise
 714          * we could run into BUG_ON(timer->state != HRTIMER_STATE_CALLBACK);
 715          * when we manage to start the timer before the callback
 716          * returns HRTIMER_RESTART.
 717          *
 718          * We cannot use hrtimer_cancel() here as a running callback
 719          * could be blocked on rtc->irq_task_lock and hrtimer_cancel()
 720          * would spin forever.
 721          */
 722         if (hrtimer_try_to_cancel(&rtc->pie_timer) < 0)
 723                 return -1;
 724 
 725         if (enabled) {
 726                 ktime_t period = NSEC_PER_SEC / rtc->irq_freq;
 727 
 728                 hrtimer_start(&rtc->pie_timer, period, HRTIMER_MODE_REL);
 729         }
 730         return 0;
 731 }
 732 
 733 /**
 734  * rtc_irq_set_state - enable/disable 2^N Hz periodic IRQs
 735  * @rtc: the rtc device
 736  * @enabled: true to enable periodic IRQs
 737  * Context: any
 738  *
 739  * Note that rtc_irq_set_freq() should previously have been used to
 740  * specify the desired frequency of periodic IRQ.
 741  */
 742 int rtc_irq_set_state(struct rtc_device *rtc, int enabled)
 743 {
 744         int err = 0;
 745 
 746         while (rtc_update_hrtimer(rtc, enabled) < 0)
 747                 cpu_relax();
 748 
 749         rtc->pie_enabled = enabled;
 750 
 751         trace_rtc_irq_set_state(enabled, err);
 752         return err;
 753 }
 754 
 755 /**
 756  * rtc_irq_set_freq - set 2^N Hz periodic IRQ frequency for IRQ
 757  * @rtc: the rtc device
 758  * @freq: positive frequency
 759  * Context: any
 760  *
 761  * Note that rtc_irq_set_state() is used to enable or disable the
 762  * periodic IRQs.
 763  */
 764 int rtc_irq_set_freq(struct rtc_device *rtc, int freq)
 765 {
 766         int err = 0;
 767 
 768         if (freq <= 0 || freq > RTC_MAX_FREQ)
 769                 return -EINVAL;
 770 
 771         rtc->irq_freq = freq;
 772         while (rtc->pie_enabled && rtc_update_hrtimer(rtc, 1) < 0)
 773                 cpu_relax();
 774 
 775         trace_rtc_irq_set_freq(freq, err);
 776         return err;
 777 }
 778 
 779 /**
 780  * rtc_timer_enqueue - Adds a rtc_timer to the rtc_device timerqueue
 781  * @rtc rtc device
 782  * @timer timer being added.
 783  *
 784  * Enqueues a timer onto the rtc devices timerqueue and sets
 785  * the next alarm event appropriately.
 786  *
 787  * Sets the enabled bit on the added timer.
 788  *
 789  * Must hold ops_lock for proper serialization of timerqueue
 790  */
 791 static int rtc_timer_enqueue(struct rtc_device *rtc, struct rtc_timer *timer)
 792 {
 793         struct timerqueue_node *next = timerqueue_getnext(&rtc->timerqueue);
 794         struct rtc_time tm;
 795         ktime_t now;
 796 
 797         timer->enabled = 1;
 798         __rtc_read_time(rtc, &tm);
 799         now = rtc_tm_to_ktime(tm);
 800 
 801         /* Skip over expired timers */
 802         while (next) {
 803                 if (next->expires >= now)
 804                         break;
 805                 next = timerqueue_iterate_next(next);
 806         }
 807 
 808         timerqueue_add(&rtc->timerqueue, &timer->node);
 809         trace_rtc_timer_enqueue(timer);
 810         if (!next || ktime_before(timer->node.expires, next->expires)) {
 811                 struct rtc_wkalrm alarm;
 812                 int err;
 813 
 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 
 855         timerqueue_del(&rtc->timerqueue, &timer->node);
 856         trace_rtc_timer_dequeue(timer);
 857         timer->enabled = 0;
 858         if (next == &timer->node) {
 859                 struct rtc_wkalrm alarm;
 860                 int err;
 861 
 862                 next = timerqueue_getnext(&rtc->timerqueue);
 863                 if (!next) {
 864                         rtc_alarm_disable(rtc);
 865                         return;
 866                 }
 867                 alarm.time = rtc_ktime_to_tm(next->expires);
 868                 alarm.enabled = 1;
 869                 err = __rtc_set_alarm(rtc, &alarm);
 870                 if (err == -ETIME) {
 871                         pm_stay_awake(rtc->dev.parent);
 872                         schedule_work(&rtc->irqwork);
 873                 }
 874         }
 875 }
 876 
 877 /**
 878  * rtc_timer_do_work - Expires rtc timers
 879  * @rtc rtc device
 880  * @timer timer being removed.
 881  *
 882  * Expires rtc timers. Reprograms next alarm event if needed.
 883  * Called via worktask.
 884  *
 885  * Serializes access to timerqueue via ops_lock mutex
 886  */
 887 void rtc_timer_do_work(struct work_struct *work)
 888 {
 889         struct rtc_timer *timer;
 890         struct timerqueue_node *next;
 891         ktime_t now;
 892         struct rtc_time tm;
 893 
 894         struct rtc_device *rtc =
 895                 container_of(work, struct rtc_device, irqwork);
 896 
 897         mutex_lock(&rtc->ops_lock);
 898 again:
 899         __rtc_read_time(rtc, &tm);
 900         now = rtc_tm_to_ktime(tm);
 901         while ((next = timerqueue_getnext(&rtc->timerqueue))) {
 902                 if (next->expires > now)
 903                         break;
 904 
 905                 /* expire timer */
 906                 timer = container_of(next, struct rtc_timer, node);
 907                 timerqueue_del(&rtc->timerqueue, &timer->node);
 908                 trace_rtc_timer_dequeue(timer);
 909                 timer->enabled = 0;
 910                 if (timer->func)
 911                         timer->func(timer->rtc);
 912 
 913                 trace_rtc_timer_fired(timer);
 914                 /* Re-add/fwd periodic timers */
 915                 if (ktime_to_ns(timer->period)) {
 916                         timer->node.expires = ktime_add(timer->node.expires,
 917                                                         timer->period);
 918                         timer->enabled = 1;
 919                         timerqueue_add(&rtc->timerqueue, &timer->node);
 920                         trace_rtc_timer_enqueue(timer);
 921                 }
 922         }
 923 
 924         /* Set next alarm */
 925         if (next) {
 926                 struct rtc_wkalrm alarm;
 927                 int err;
 928                 int retry = 3;
 929 
 930                 alarm.time = rtc_ktime_to_tm(next->expires);
 931                 alarm.enabled = 1;
 932 reprogram:
 933                 err = __rtc_set_alarm(rtc, &alarm);
 934                 if (err == -ETIME) {
 935                         goto again;
 936                 } else if (err) {
 937                         if (retry-- > 0)
 938                                 goto reprogram;
 939 
 940                         timer = container_of(next, struct rtc_timer, node);
 941                         timerqueue_del(&rtc->timerqueue, &timer->node);
 942                         trace_rtc_timer_dequeue(timer);
 943                         timer->enabled = 0;
 944                         dev_err(&rtc->dev, "__rtc_set_alarm: err=%d\n", err);
 945                         goto again;
 946                 }
 947         } else {
 948                 rtc_alarm_disable(rtc);
 949         }
 950 
 951         pm_relax(rtc->dev.parent);
 952         mutex_unlock(&rtc->ops_lock);
 953 }
 954 
 955 /* rtc_timer_init - Initializes an rtc_timer
 956  * @timer: timer to be intiialized
 957  * @f: function pointer to be called when timer fires
 958  * @rtc: pointer to the rtc_device
 959  *
 960  * Kernel interface to initializing an rtc_timer.
 961  */
 962 void rtc_timer_init(struct rtc_timer *timer, void (*f)(struct rtc_device *r),
 963                     struct rtc_device *rtc)
 964 {
 965         timerqueue_init(&timer->node);
 966         timer->enabled = 0;
 967         timer->func = f;
 968         timer->rtc = rtc;
 969 }
 970 
 971 /* rtc_timer_start - Sets an rtc_timer to fire in the future
 972  * @ rtc: rtc device to be used
 973  * @ timer: timer being set
 974  * @ expires: time at which to expire the timer
 975  * @ period: period that the timer will recur
 976  *
 977  * Kernel interface to set an rtc_timer
 978  */
 979 int rtc_timer_start(struct rtc_device *rtc, struct rtc_timer *timer,
 980                     ktime_t expires, ktime_t period)
 981 {
 982         int ret = 0;
 983 
 984         mutex_lock(&rtc->ops_lock);
 985         if (timer->enabled)
 986                 rtc_timer_remove(rtc, timer);
 987 
 988         timer->node.expires = expires;
 989         timer->period = period;
 990 
 991         ret = rtc_timer_enqueue(rtc, timer);
 992 
 993         mutex_unlock(&rtc->ops_lock);
 994         return ret;
 995 }
 996 
 997 /* rtc_timer_cancel - Stops an rtc_timer
 998  * @ rtc: rtc device to be used
 999  * @ timer: timer being set
1000  *
1001  * Kernel interface to cancel an rtc_timer
1002  */
1003 void rtc_timer_cancel(struct rtc_device *rtc, struct rtc_timer *timer)
1004 {
1005         mutex_lock(&rtc->ops_lock);
1006         if (timer->enabled)
1007                 rtc_timer_remove(rtc, timer);
1008         mutex_unlock(&rtc->ops_lock);
1009 }
1010 
1011 /**
1012  * rtc_read_offset - Read the amount of rtc offset in parts per billion
1013  * @ rtc: rtc device to be used
1014  * @ offset: the offset in parts per billion
1015  *
1016  * see below for details.
1017  *
1018  * Kernel interface to read rtc clock offset
1019  * Returns 0 on success, or a negative number on error.
1020  * If read_offset() is not implemented for the rtc, return -EINVAL
1021  */
1022 int rtc_read_offset(struct rtc_device *rtc, long *offset)
1023 {
1024         int ret;
1025 
1026         if (!rtc->ops)
1027                 return -ENODEV;
1028 
1029         if (!rtc->ops->read_offset)
1030                 return -EINVAL;
1031 
1032         mutex_lock(&rtc->ops_lock);
1033         ret = rtc->ops->read_offset(rtc->dev.parent, offset);
1034         mutex_unlock(&rtc->ops_lock);
1035 
1036         trace_rtc_read_offset(*offset, ret);
1037         return ret;
1038 }
1039 
1040 /**
1041  * rtc_set_offset - Adjusts the duration of the average second
1042  * @ rtc: rtc device to be used
1043  * @ offset: the offset in parts per billion
1044  *
1045  * Some rtc's allow an adjustment to the average duration of a second
1046  * to compensate for differences in the actual clock rate due to temperature,
1047  * the crystal, capacitor, etc.
1048  *
1049  * The adjustment applied is as follows:
1050  *   t = t0 * (1 + offset * 1e-9)
1051  * where t0 is the measured length of 1 RTC second with offset = 0
1052  *
1053  * Kernel interface to adjust an rtc clock offset.
1054  * Return 0 on success, or a negative number on error.
1055  * If the rtc offset is not setable (or not implemented), return -EINVAL
1056  */
1057 int rtc_set_offset(struct rtc_device *rtc, long offset)
1058 {
1059         int ret;
1060 
1061         if (!rtc->ops)
1062                 return -ENODEV;
1063 
1064         if (!rtc->ops->set_offset)
1065                 return -EINVAL;
1066 
1067         mutex_lock(&rtc->ops_lock);
1068         ret = rtc->ops->set_offset(rtc->dev.parent, offset);
1069         mutex_unlock(&rtc->ops_lock);
1070 
1071         trace_rtc_set_offset(offset, ret);
1072         return ret;
1073 }