drivers/rtc/interface.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * RTC subsystem, interface functions
   4  *
   5  * Copyright (C) 2005 Tower Technologies
   6  * Author: Alessandro Zummo <a.zummo@towertech.it>
   7  *
   8  * based on arch/arm/common/rtctime.c
   9  */
  10
  11 #include <linux/rtc.h>
  12 #include <linux/sched.h>
  13 #include <linux/module.h>
  14 #include <linux/log2.h>
  15 #include <linux/workqueue.h>
  16
  17 #define CREATE_TRACE_POINTS
  18 #include <trace/events/rtc.h>
  19
  20 static int rtc_timer_enqueue(struct rtc_device *rtc, struct rtc_timer *timer);
  21 static void rtc_timer_remove(struct rtc_device *rtc, struct rtc_timer *timer);
  22
  23 static void rtc_add_offset(struct rtc_device *rtc, struct rtc_time *tm)
  24 {
  25         time64_t secs;
  26
  27         if (!rtc->offset_secs)
  28                 return;
  29
  30         secs = rtc_tm_to_time64(tm);
  31
  32         /*
  33          * Since the reading time values from RTC device are always in the RTC
  34          * original valid range, but we need to skip the overlapped region
  35          * between expanded range and original range, which is no need to add
  36          * the offset.
  37          */
  38         if ((rtc->start_secs > rtc->range_min && secs >= rtc->start_secs) ||
  39             (rtc->start_secs < rtc->range_min &&
  40              secs <= (rtc->start_secs + rtc->range_max - rtc->range_min)))
  41                 return;
  42
  43         rtc_time64_to_tm(secs + rtc->offset_secs, tm);
  44 }
  45
  46 static void rtc_subtract_offset(struct rtc_device *rtc, struct rtc_time *tm)
  47 {
  48         time64_t secs;
  49
  50         if (!rtc->offset_secs)
  51                 return;
  52
  53         secs = rtc_tm_to_time64(tm);
  54
  55         /*
  56          * If the setting time values are in the valid range of RTC hardware
  57          * device, then no need to subtract the offset when setting time to RTC
  58          * device. Otherwise we need to subtract the offset to make the time
  59          * values are valid for RTC hardware device.
  60          */
  61         if (secs >= rtc->range_min && secs <= rtc->range_max)
  62                 return;
  63
  64         rtc_time64_to_tm(secs - rtc->offset_secs, tm);
  65 }
  66
  67 static int rtc_valid_range(struct rtc_device *rtc, struct rtc_time *tm)
  68 {
  69         if (rtc->range_min != rtc->range_max) {
  70                 time64_t time = rtc_tm_to_time64(tm);
  71                 time64_t range_min = rtc->set_start_time ? rtc->start_secs :
  72                         rtc->range_min;
  73                 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;
 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         err = mutex_lock_interruptible(&rtc->ops_lock);
 141         if (err)
 142                 return err;
 143
 144         if (!rtc->ops)
 145                 err = -ENODEV;
 146         else if (rtc->ops->set_time)
 147                 err = rtc->ops->set_time(rtc->dev.parent, tm);
 148         else
 149                 err = -EINVAL;
 150
 151         pm_stay_awake(rtc->dev.parent);
 152         mutex_unlock(&rtc->ops_lock);
 153         /* A timer might have just expired */
 154         schedule_work(&rtc->irqwork);
 155
 156         trace_rtc_set_time(rtc_tm_to_time64(tm), err);
 157         return err;
 158 }
 159 EXPORT_SYMBOL_GPL(rtc_set_time);
 160
 161 static int rtc_read_alarm_internal(struct rtc_device *rtc,
 162                                    struct rtc_wkalrm *alarm)
 163 {
 164         int err;
 165
 166         err = mutex_lock_interruptible(&rtc->ops_lock);
 167         if (err)
 168                 return err;
 169
 170         if (!rtc->ops) {
 171                 err = -ENODEV;
 172         } else if (!rtc->ops->read_alarm) {
 173                 err = -EINVAL;
 174         } else {
 175                 alarm->enabled = 0;
 176                 alarm->pending = 0;
 177                 alarm->time.tm_sec = -1;
 178                 alarm->time.tm_min = -1;
 179                 alarm->time.tm_hour = -1;
 180                 alarm->time.tm_mday = -1;
 181                 alarm->time.tm_mon = -1;
 182                 alarm->time.tm_year = -1;
 183                 alarm->time.tm_wday = -1;
 184                 alarm->time.tm_yday = -1;
 185                 alarm->time.tm_isdst = -1;
 186                 err = rtc->ops->read_alarm(rtc->dev.parent, alarm);
 187         }
 188
 189         mutex_unlock(&rtc->ops_lock);
 190
 191         trace_rtc_read_alarm(rtc_tm_to_time64(&alarm->time), err);
 192         return err;
 193 }
 194
 195 int __rtc_read_alarm(struct rtc_device *rtc, struct rtc_wkalrm *alarm)
 196 {
 197         int err;
 198         struct rtc_time before, now;
 199         int first_time = 1;
 200         time64_t t_now, t_alm;
 201         enum { none, day, month, year } missing = none;
 202         unsigned int days;
 203
 204         /* The lower level RTC driver may return -1 in some fields,
 205          * creating invalid alarm->time values, for reasons like:
 206          *
 207          *   - The hardware may not be capable of filling them in;
 208          *     many alarms match only on time-of-day fields, not
 209          *     day/month/year calendar data.
 210          *
 211          *   - Some hardware uses illegal values as "wildcard" match
 212          *     values, which non-Linux firmware (like a BIOS) may try
 213          *     to set up as e.g. "alarm 15 minutes after each hour".
 214          *     Linux uses only oneshot alarms.
 215          *
 216          * When we see that here, we deal with it by using values from
 217          * a current RTC timestamp for any missing (-1) values.  The
 218          * RTC driver prevents "periodic alarm" modes.
 219          *
 220          * But this can be racey, because some fields of the RTC timestamp
 221          * may have wrapped in the interval since we read the RTC alarm,
 222          * which would lead to us inserting inconsistent values in place
 223          * of the -1 fields.
 224          *
 225          * Reading the alarm and timestamp in the reverse sequence
 226          * would have the same race condition, and not solve the issue.
 227          *
 228          * So, we must first read the RTC timestamp,
 229          * then read the RTC alarm value,
 230          * and then read a second RTC timestamp.
 231          *
 232          * If any fields of the second timestamp have changed
 233          * when compared with the first timestamp, then we know
 234          * our timestamp may be inconsistent with that used by
 235          * the low-level rtc_read_alarm_internal() function.
 236          *
 237          * So, when the two timestamps disagree, we just loop and do
 238          * the process again to get a fully consistent set of values.
 239          *
 240          * This could all instead be done in the lower level driver,
 241          * but since more than one lower level RTC implementation needs it,
 242          * then it's probably best best to do it here instead of there..
 243          */
 244
 245         /* Get the "before" timestamp */
 246         err = rtc_read_time(rtc, &before);
 247         if (err < 0)
 248                 return err;
 249         do {
 250                 if (!first_time)
 251                         memcpy(&before, &now, sizeof(struct rtc_time));
 252                 first_time = 0;
 253
 254                 /* get the RTC alarm values, which may be incomplete */
 255                 err = rtc_read_alarm_internal(rtc, alarm);
 256                 if (err)
 257                         return err;
 258
 259                 /* full-function RTCs won't have such missing fields */
 260                 if (rtc_valid_tm(&alarm->time) == 0) {
 261                         rtc_add_offset(rtc, &alarm->time);
 262                         return 0;
 263                 }
 264
 265                 /* get the "after" timestamp, to detect wrapped fields */
 266                 err = rtc_read_time(rtc, &now);
 267                 if (err < 0)
 268                         return err;
 269
 270                 /* note that tm_sec is a "don't care" value here: */
 271         } while (before.tm_min  != now.tm_min ||
 272                  before.tm_hour != now.tm_hour ||
 273                  before.tm_mon  != now.tm_mon ||
 274                  before.tm_year != now.tm_year);
 275
 276         /* Fill in the missing alarm fields using the timestamp; we
 277          * know there's at least one since alarm->time is invalid.
 278          */
 279         if (alarm->time.tm_sec == -1)
 280                 alarm->time.tm_sec = now.tm_sec;
 281         if (alarm->time.tm_min == -1)
 282                 alarm->time.tm_min = now.tm_min;
 283         if (alarm->time.tm_hour == -1)
 284                 alarm->time.tm_hour = now.tm_hour;
 285
 286         /* For simplicity, only support date rollover for now */
 287         if (alarm->time.tm_mday < 1 || alarm->time.tm_mday > 31) {
 288                 alarm->time.tm_mday = now.tm_mday;
 289                 missing = day;
 290         }
 291         if ((unsigned int)alarm->time.tm_mon >= 12) {
 292                 alarm->time.tm_mon = now.tm_mon;
 293                 if (missing == none)
 294                         missing = month;
 295         }
 296         if (alarm->time.tm_year == -1) {
 297                 alarm->time.tm_year = now.tm_year;
 298                 if (missing == none)
 299                         missing = year;
 300         }
 301
 302         /* Can't proceed if alarm is still invalid after replacing
 303          * missing fields.
 304          */
 305         err = rtc_valid_tm(&alarm->time);
 306         if (err)
 307                 goto done;
 308
 309         /* with luck, no rollover is needed */
 310         t_now = rtc_tm_to_time64(&now);
 311         t_alm = rtc_tm_to_time64(&alarm->time);
 312         if (t_now < t_alm)
 313                 goto done;
 314
 315         switch (missing) {
 316         /* 24 hour rollover ... if it's now 10am Monday, an alarm that
 317          * that will trigger at 5am will do so at 5am Tuesday, which
 318          * could also be in the next month or year.  This is a common
 319          * case, especially for PCs.
 320          */
 321         case day:
 322                 dev_dbg(&rtc->dev, "alarm rollover: %s\n", "day");
 323                 t_alm += 24 * 60 * 60;
 324                 rtc_time64_to_tm(t_alm, &alarm->time);
 325                 break;
 326
 327         /* Month rollover ... if it's the 31th, an alarm on the 3rd will
 328          * be next month.  An alarm matching on the 30th, 29th, or 28th
 329          * may end up in the month after that!  Many newer PCs support
 330          * this type of alarm.
 331          */
 332         case month:
 333                 dev_dbg(&rtc->dev, "alarm rollover: %s\n", "month");
 334                 do {
 335                         if (alarm->time.tm_mon < 11) {
 336                                 alarm->time.tm_mon++;
 337                         } else {
 338                                 alarm->time.tm_mon = 0;
 339                                 alarm->time.tm_year++;
 340                         }
 341                         days = rtc_month_days(alarm->time.tm_mon,
 342                                               alarm->time.tm_year);
 343                 } while (days < alarm->time.tm_mday);
 344                 break;
 345
 346         /* Year rollover ... easy except for leap years! */
 347         case year:
 348                 dev_dbg(&rtc->dev, "alarm rollover: %s\n", "year");
 349                 do {
 350                         alarm->time.tm_year++;
 351                 } while (!is_leap_year(alarm->time.tm_year + 1900) &&
 352                          rtc_valid_tm(&alarm->time) != 0);
 353                 break;
 354
 355         default:
 356                 dev_warn(&rtc->dev, "alarm rollover not handled\n");
 357         }
 358
 359         err = rtc_valid_tm(&alarm->time);
 360
 361 done:
 362         if (err)
 363                 dev_warn(&rtc->dev, "invalid alarm value: %ptR\n",
 364                          &alarm->time);
 365
 366         return err;
 367 }
 368
 369 int rtc_read_alarm(struct rtc_device *rtc, struct rtc_wkalrm *alarm)
 370 {
 371         int err;
 372
 373         err = mutex_lock_interruptible(&rtc->ops_lock);
 374         if (err)
 375                 return err;
 376         if (!rtc->ops) {
 377                 err = -ENODEV;
 378         } else if (!rtc->ops->read_alarm) {
 379                 err = -EINVAL;
 380         } else {
 381                 memset(alarm, 0, sizeof(struct rtc_wkalrm));
 382                 alarm->enabled = rtc->aie_timer.enabled;
 383                 alarm->time = rtc_ktime_to_tm(rtc->aie_timer.node.expires);
 384         }
 385         mutex_unlock(&rtc->ops_lock);
 386
 387         trace_rtc_read_alarm(rtc_tm_to_time64(&alarm->time), err);
 388         return err;
 389 }
 390 EXPORT_SYMBOL_GPL(rtc_read_alarm);
 391
 392 static int __rtc_set_alarm(struct rtc_device *rtc, struct rtc_wkalrm *alarm)
 393 {
 394         struct rtc_time tm;
 395         time64_t now, scheduled;
 396         int err;
 397
 398         err = rtc_valid_tm(&alarm->time);
 399         if (err)
 400                 return err;
 401
 402         scheduled = rtc_tm_to_time64(&alarm->time);
 403
 404         /* Make sure we're not setting alarms in the past */
 405         err = __rtc_read_time(rtc, &tm);
 406         if (err)
 407                 return err;
 408         now = rtc_tm_to_time64(&tm);
 409         if (scheduled <= now)
 410                 return -ETIME;
 411         /*
 412          * XXX - We just checked to make sure the alarm time is not
 413          * in the past, but there is still a race window where if
 414          * the is alarm set for the next second and the second ticks
 415          * over right here, before we set the alarm.
 416          */
 417
 418         rtc_subtract_offset(rtc, &alarm->time);
 419
 420         if (!rtc->ops)
 421                 err = -ENODEV;
 422         else if (!rtc->ops->set_alarm)
 423                 err = -EINVAL;
 424         else
 425                 err = rtc->ops->set_alarm(rtc->dev.parent, alarm);
 426
 427         trace_rtc_set_alarm(rtc_tm_to_time64(&alarm->time), err);
 428         return err;
 429 }
 430
 431 int rtc_set_alarm(struct rtc_device *rtc, struct rtc_wkalrm *alarm)
 432 {
 433         int err;
 434
 435         if (!rtc->ops)
 436                 return -ENODEV;
 437         else if (!rtc->ops->set_alarm)
 438                 return -EINVAL;
 439
 440         err = rtc_valid_tm(&alarm->time);
 441         if (err != 0)
 442                 return err;
 443
 444         err = rtc_valid_range(rtc, &alarm->time);
 445         if (err)
 446                 return err;
 447
 448         err = mutex_lock_interruptible(&rtc->ops_lock);
 449         if (err)
 450                 return err;
 451         if (rtc->aie_timer.enabled)
 452                 rtc_timer_remove(rtc, &rtc->aie_timer);
 453
 454         rtc->aie_timer.node.expires = rtc_tm_to_ktime(alarm->time);
 455         rtc->aie_timer.period = 0;
 456         if (alarm->enabled)
 457                 err = rtc_timer_enqueue(rtc, &rtc->aie_timer);
 458
 459         mutex_unlock(&rtc->ops_lock);
 460
 461         return err;
 462 }
 463 EXPORT_SYMBOL_GPL(rtc_set_alarm);
 464
 465 /* Called once per device from rtc_device_register */
 466 int rtc_initialize_alarm(struct rtc_device *rtc, struct rtc_wkalrm *alarm)
 467 {
 468         int err;
 469         struct rtc_time now;
 470
 471         err = rtc_valid_tm(&alarm->time);
 472         if (err != 0)
 473                 return err;
 474
 475         err = rtc_read_time(rtc, &now);
 476         if (err)
 477                 return err;
 478
 479         err = mutex_lock_interruptible(&rtc->ops_lock);
 480         if (err)
 481                 return err;
 482
 483         rtc->aie_timer.node.expires = rtc_tm_to_ktime(alarm->time);
 484         rtc->aie_timer.period = 0;
 485
 486         /* Alarm has to be enabled & in the future for us to enqueue it */
 487         if (alarm->enabled && (rtc_tm_to_ktime(now) <
 488                          rtc->aie_timer.node.expires)) {
 489                 rtc->aie_timer.enabled = 1;
 490                 timerqueue_add(&rtc->timerqueue, &rtc->aie_timer.node);
 491                 trace_rtc_timer_enqueue(&rtc->aie_timer);
 492         }
 493         mutex_unlock(&rtc->ops_lock);
 494         return err;
 495 }
 496 EXPORT_SYMBOL_GPL(rtc_initialize_alarm);
 497
 498 int rtc_alarm_irq_enable(struct rtc_device *rtc, unsigned int enabled)
 499 {
 500         int err;
 501
 502         err = mutex_lock_interruptible(&rtc->ops_lock);
 503         if (err)
 504                 return err;
 505
 506         if (rtc->aie_timer.enabled != enabled) {
 507                 if (enabled)
 508                         err = rtc_timer_enqueue(rtc, &rtc->aie_timer);
 509                 else
 510                         rtc_timer_remove(rtc, &rtc->aie_timer);
 511         }
 512
 513         if (err)
 514                 /* nothing */;
 515         else if (!rtc->ops)
 516                 err = -ENODEV;
 517         else if (!rtc->ops->alarm_irq_enable)
 518                 err = -EINVAL;
 519         else
 520                 err = rtc->ops->alarm_irq_enable(rtc->dev.parent, enabled);
 521
 522         mutex_unlock(&rtc->ops_lock);
 523
 524         trace_rtc_alarm_irq_enable(enabled, err);
 525         return err;
 526 }
 527 EXPORT_SYMBOL_GPL(rtc_alarm_irq_enable);
 528
 529 int rtc_update_irq_enable(struct rtc_device *rtc, unsigned int enabled)
 530 {
 531         int err;
 532
 533         err = mutex_lock_interruptible(&rtc->ops_lock);
 534         if (err)
 535                 return err;
 536
 537 #ifdef CONFIG_RTC_INTF_DEV_UIE_EMUL
 538         if (enabled == 0 && rtc->uie_irq_active) {
 539                 mutex_unlock(&rtc->ops_lock);
 540                 return rtc_dev_update_irq_enable_emul(rtc, 0);
 541         }
 542 #endif
 543         /* make sure we're changing state */
 544         if (rtc->uie_rtctimer.enabled == enabled)
 545                 goto out;
 546
 547         if (rtc->uie_unsupported) {
 548                 err = -EINVAL;
 549                 goto out;
 550         }
 551
 552         if (enabled) {
 553                 struct rtc_time tm;
 554                 ktime_t now, onesec;
 555
 556                 __rtc_read_time(rtc, &tm);
 557                 onesec = ktime_set(1, 0);
 558                 now = rtc_tm_to_ktime(tm);
 559                 rtc->uie_rtctimer.node.expires = ktime_add(now, onesec);
 560                 rtc->uie_rtctimer.period = ktime_set(1, 0);
 561                 err = rtc_timer_enqueue(rtc, &rtc->uie_rtctimer);
 562         } else {
 563                 rtc_timer_remove(rtc, &rtc->uie_rtctimer);
 564         }
 565
 566 out:
 567         mutex_unlock(&rtc->ops_lock);
 568 #ifdef CONFIG_RTC_INTF_DEV_UIE_EMUL
 569         /*
 570          * Enable emulation if the driver returned -EINVAL to signal that it has
 571          * been configured without interrupts or they are not available at the
 572          * moment.
 573          */
 574         if (err == -EINVAL)
 575                 err = rtc_dev_update_irq_enable_emul(rtc, enabled);
 576 #endif
 577         return err;
 578 }
 579 EXPORT_SYMBOL_GPL(rtc_update_irq_enable);
 580
 581 /**
 582  * rtc_handle_legacy_irq - AIE, UIE and PIE event hook
 583  * @rtc: pointer to the rtc device
 584  *
 585  * This function is called when an AIE, UIE or PIE mode interrupt
 586  * has occurred (or been emulated).
 587  *
 588  */
 589 void rtc_handle_legacy_irq(struct rtc_device *rtc, int num, int mode)
 590 {
 591         unsigned long flags;
 592
 593         /* mark one irq of the appropriate mode */
 594         spin_lock_irqsave(&rtc->irq_lock, flags);
 595         rtc->irq_data = (rtc->irq_data + (num << 8)) | (RTC_IRQF | mode);
 596         spin_unlock_irqrestore(&rtc->irq_lock, flags);
 597
 598         wake_up_interruptible(&rtc->irq_queue);
 599         kill_fasync(&rtc->async_queue, SIGIO, POLL_IN);
 600 }
 601
 602 /**
 603  * rtc_aie_update_irq - AIE mode rtctimer hook
 604  * @rtc: pointer to the rtc_device
 605  *
 606  * This functions is called when the aie_timer expires.
 607  */
 608 void rtc_aie_update_irq(struct rtc_device *rtc)
 609 {
 610         rtc_handle_legacy_irq(rtc, 1, RTC_AF);
 611 }
 612
 613 /**
 614  * rtc_uie_update_irq - UIE mode rtctimer hook
 615  * @rtc: pointer to the rtc_device
 616  *
 617  * This functions is called when the uie_timer expires.
 618  */
 619 void rtc_uie_update_irq(struct rtc_device *rtc)
 620 {
 621         rtc_handle_legacy_irq(rtc, 1,  RTC_UF);
 622 }
 623
 624 /**
 625  * rtc_pie_update_irq - PIE mode hrtimer hook
 626  * @timer: pointer to the pie mode hrtimer
 627  *
 628  * This function is used to emulate PIE mode interrupts
 629  * using an hrtimer. This function is called when the periodic
 630  * hrtimer expires.
 631  */
 632 enum hrtimer_restart rtc_pie_update_irq(struct hrtimer *timer)
 633 {
 634         struct rtc_device *rtc;
 635         ktime_t period;
 636         int count;
 637
 638         rtc = container_of(timer, struct rtc_device, pie_timer);
 639
 640         period = NSEC_PER_SEC / rtc->irq_freq;
 641         count = hrtimer_forward_now(timer, period);
 642
 643         rtc_handle_legacy_irq(rtc, count, RTC_PF);
 644
 645         return HRTIMER_RESTART;
 646 }
 647
 648 /**
 649  * rtc_update_irq - Triggered when a RTC interrupt occurs.
 650  * @rtc: the rtc device
 651  * @num: how many irqs are being reported (usually one)
 652  * @events: mask of RTC_IRQF with one or more of RTC_PF, RTC_AF, RTC_UF
 653  * Context: any
 654  */
 655 void rtc_update_irq(struct rtc_device *rtc,
 656                     unsigned long num, unsigned long events)
 657 {
 658         if (IS_ERR_OR_NULL(rtc))
 659                 return;
 660
 661         pm_stay_awake(rtc->dev.parent);
 662         schedule_work(&rtc->irqwork);
 663 }
 664 EXPORT_SYMBOL_GPL(rtc_update_irq);
 665
 666 static int __rtc_match(struct device *dev, const void *data)
 667 {
 668         const char *name = data;
 669
 670         if (strcmp(dev_name(dev), name) == 0)
 671                 return 1;
 672         return 0;
 673 }
 674
 675 struct rtc_device *rtc_class_open(const char *name)
 676 {
 677         struct device *dev;
 678         struct rtc_device *rtc = NULL;
 679
 680         dev = class_find_device(rtc_class, NULL, name, __rtc_match);
 681         if (dev)
 682                 rtc = to_rtc_device(dev);
 683
 684         if (rtc) {
 685                 if (!try_module_get(rtc->owner)) {
 686                         put_device(dev);
 687                         rtc = NULL;
 688                 }
 689         }
 690
 691         return rtc;
 692 }
 693 EXPORT_SYMBOL_GPL(rtc_class_open);
 694
 695 void rtc_class_close(struct rtc_device *rtc)
 696 {
 697         module_put(rtc->owner);
 698         put_device(&rtc->dev);
 699 }
 700 EXPORT_SYMBOL_GPL(rtc_class_close);
 701
 702 static int rtc_update_hrtimer(struct rtc_device *rtc, int enabled)
 703 {
 704         /*
 705          * We always cancel the timer here first, because otherwise
 706          * we could run into BUG_ON(timer->state != HRTIMER_STATE_CALLBACK);
 707          * when we manage to start the timer before the callback
 708          * returns HRTIMER_RESTART.
 709          *
 710          * We cannot use hrtimer_cancel() here as a running callback
 711          * could be blocked on rtc->irq_task_lock and hrtimer_cancel()
 712          * would spin forever.
 713          */
 714         if (hrtimer_try_to_cancel(&rtc->pie_timer) < 0)
 715                 return -1;
 716
 717         if (enabled) {
 718                 ktime_t period = NSEC_PER_SEC / rtc->irq_freq;
 719
 720                 hrtimer_start(&rtc->pie_timer, period, HRTIMER_MODE_REL);
 721         }
 722         return 0;
 723 }
 724
 725 /**
 726  * rtc_irq_set_state - enable/disable 2^N Hz periodic IRQs
 727  * @rtc: the rtc device
 728  * @enabled: true to enable periodic IRQs
 729  * Context: any
 730  *
 731  * Note that rtc_irq_set_freq() should previously have been used to
 732  * specify the desired frequency of periodic IRQ.
 733  */
 734 int rtc_irq_set_state(struct rtc_device *rtc, int enabled)
 735 {
 736         int err = 0;
 737
 738         while (rtc_update_hrtimer(rtc, enabled) < 0)
 739                 cpu_relax();
 740
 741         rtc->pie_enabled = enabled;
 742
 743         trace_rtc_irq_set_state(enabled, err);
 744         return err;
 745 }
 746
 747 /**
 748  * rtc_irq_set_freq - set 2^N Hz periodic IRQ frequency for IRQ
 749  * @rtc: the rtc device
 750  * @freq: positive frequency
 751  * Context: any
 752  *
 753  * Note that rtc_irq_set_state() is used to enable or disable the
 754  * periodic IRQs.
 755  */
 756 int rtc_irq_set_freq(struct rtc_device *rtc, int freq)
 757 {
 758         int err = 0;
 759
 760         if (freq <= 0 || freq > RTC_MAX_FREQ)
 761                 return -EINVAL;
 762
 763         rtc->irq_freq = freq;
 764         while (rtc->pie_enabled && rtc_update_hrtimer(rtc, 1) < 0)
 765                 cpu_relax();
 766
 767         trace_rtc_irq_set_freq(freq, err);
 768         return err;
 769 }
 770
 771 /**
 772  * rtc_timer_enqueue - Adds a rtc_timer to the rtc_device timerqueue
 773  * @rtc rtc device
 774  * @timer timer being added.
 775  *
 776  * Enqueues a timer onto the rtc devices timerqueue and sets
 777  * the next alarm event appropriately.
 778  *
 779  * Sets the enabled bit on the added timer.
 780  *
 781  * Must hold ops_lock for proper serialization of timerqueue
 782  */
 783 static int rtc_timer_enqueue(struct rtc_device *rtc, struct rtc_timer *timer)
 784 {
 785         struct timerqueue_node *next = timerqueue_getnext(&rtc->timerqueue);
 786         struct rtc_time tm;
 787         ktime_t now;
 788
 789         timer->enabled = 1;
 790         __rtc_read_time(rtc, &tm);
 791         now = rtc_tm_to_ktime(tm);
 792
 793         /* Skip over expired timers */
 794         while (next) {
 795                 if (next->expires >= now)
 796                         break;
 797                 next = timerqueue_iterate_next(next);
 798         }
 799
 800         timerqueue_add(&rtc->timerqueue, &timer->node);
 801         trace_rtc_timer_enqueue(timer);
 802         if (!next || ktime_before(timer->node.expires, next->expires)) {
 803                 struct rtc_wkalrm alarm;
 804                 int err;
 805
 806                 alarm.time = rtc_ktime_to_tm(timer->node.expires);
 807                 alarm.enabled = 1;
 808                 err = __rtc_set_alarm(rtc, &alarm);
 809                 if (err == -ETIME) {
 810                         pm_stay_awake(rtc->dev.parent);
 811                         schedule_work(&rtc->irqwork);
 812                 } else if (err) {
 813                         timerqueue_del(&rtc->timerqueue, &timer->node);
 814                         trace_rtc_timer_dequeue(timer);
 815                         timer->enabled = 0;
 816                         return err;
 817                 }
 818         }
 819         return 0;
 820 }
 821
 822 static void rtc_alarm_disable(struct rtc_device *rtc)
 823 {
 824         if (!rtc->ops || !rtc->ops->alarm_irq_enable)
 825                 return;
 826
 827         rtc->ops->alarm_irq_enable(rtc->dev.parent, false);
 828         trace_rtc_alarm_irq_enable(0, 0);
 829 }
 830
 831 /**
 832  * rtc_timer_remove - Removes a rtc_timer from the rtc_device timerqueue
 833  * @rtc rtc device
 834  * @timer timer being removed.
 835  *
 836  * Removes a timer onto the rtc devices timerqueue and sets
 837  * the next alarm event appropriately.
 838  *
 839  * Clears the enabled bit on the removed timer.
 840  *
 841  * Must hold ops_lock for proper serialization of timerqueue
 842  */
 843 static void rtc_timer_remove(struct rtc_device *rtc, struct rtc_timer *timer)
 844 {
 845         struct timerqueue_node *next = timerqueue_getnext(&rtc->timerqueue);
 846
 847         timerqueue_del(&rtc->timerqueue, &timer->node);
 848         trace_rtc_timer_dequeue(timer);
 849         timer->enabled = 0;
 850         if (next == &timer->node) {
 851                 struct rtc_wkalrm alarm;
 852                 int err;
 853
 854                 next = timerqueue_getnext(&rtc->timerqueue);
 855                 if (!next) {
 856                         rtc_alarm_disable(rtc);
 857                         return;
 858                 }
 859                 alarm.time = rtc_ktime_to_tm(next->expires);
 860                 alarm.enabled = 1;
 861                 err = __rtc_set_alarm(rtc, &alarm);
 862                 if (err == -ETIME) {
 863                         pm_stay_awake(rtc->dev.parent);
 864                         schedule_work(&rtc->irqwork);
 865                 }
 866         }
 867 }
 868
 869 /**
 870  * rtc_timer_do_work - Expires rtc timers
 871  * @rtc rtc device
 872  * @timer timer being removed.
 873  *
 874  * Expires rtc timers. Reprograms next alarm event if needed.
 875  * Called via worktask.
 876  *
 877  * Serializes access to timerqueue via ops_lock mutex
 878  */
 879 void rtc_timer_do_work(struct work_struct *work)
 880 {
 881         struct rtc_timer *timer;
 882         struct timerqueue_node *next;
 883         ktime_t now;
 884         struct rtc_time tm;
 885
 886         struct rtc_device *rtc =
 887                 container_of(work, struct rtc_device, irqwork);
 888
 889         mutex_lock(&rtc->ops_lock);
 890 again:
 891         __rtc_read_time(rtc, &tm);
 892         now = rtc_tm_to_ktime(tm);
 893         while ((next = timerqueue_getnext(&rtc->timerqueue))) {
 894                 if (next->expires > now)
 895                         break;
 896
 897                 /* expire timer */
 898                 timer = container_of(next, struct rtc_timer, node);
 899                 timerqueue_del(&rtc->timerqueue, &timer->node);
 900                 trace_rtc_timer_dequeue(timer);
 901                 timer->enabled = 0;
 902                 if (timer->func)
 903                         timer->func(timer->rtc);
 904
 905                 trace_rtc_timer_fired(timer);
 906                 /* Re-add/fwd periodic timers */
 907                 if (ktime_to_ns(timer->period)) {
 908                         timer->node.expires = ktime_add(timer->node.expires,
 909                                                         timer->period);
 910                         timer->enabled = 1;
 911                         timerqueue_add(&rtc->timerqueue, &timer->node);
 912                         trace_rtc_timer_enqueue(timer);
 913                 }
 914         }
 915
 916         /* Set next alarm */
 917         if (next) {
 918                 struct rtc_wkalrm alarm;
 919                 int err;
 920                 int retry = 3;
 921
 922                 alarm.time = rtc_ktime_to_tm(next->expires);
 923                 alarm.enabled = 1;
 924 reprogram:
 925                 err = __rtc_set_alarm(rtc, &alarm);
 926                 if (err == -ETIME) {
 927                         goto again;
 928                 } else if (err) {
 929                         if (retry-- > 0)
 930                                 goto reprogram;
 931
 932                         timer = container_of(next, struct rtc_timer, node);
 933                         timerqueue_del(&rtc->timerqueue, &timer->node);
 934                         trace_rtc_timer_dequeue(timer);
 935                         timer->enabled = 0;
 936                         dev_err(&rtc->dev, "__rtc_set_alarm: err=%d\n", err);
 937                         goto again;
 938                 }
 939         } else {
 940                 rtc_alarm_disable(rtc);
 941         }
 942
 943         pm_relax(rtc->dev.parent);
 944         mutex_unlock(&rtc->ops_lock);
 945 }
 946
 947 /* rtc_timer_init - Initializes an rtc_timer
 948  * @timer: timer to be intiialized
 949  * @f: function pointer to be called when timer fires
 950  * @rtc: pointer to the rtc_device
 951  *
 952  * Kernel interface to initializing an rtc_timer.
 953  */
 954 void rtc_timer_init(struct rtc_timer *timer, void (*f)(struct rtc_device *r),
 955                     struct rtc_device *rtc)
 956 {
 957         timerqueue_init(&timer->node);
 958         timer->enabled = 0;
 959         timer->func = f;
 960         timer->rtc = rtc;
 961 }
 962
 963 /* rtc_timer_start - Sets an rtc_timer to fire in the future
 964  * @ rtc: rtc device to be used
 965  * @ timer: timer being set
 966  * @ expires: time at which to expire the timer
 967  * @ period: period that the timer will recur
 968  *
 969  * Kernel interface to set an rtc_timer
 970  */
 971 int rtc_timer_start(struct rtc_device *rtc, struct rtc_timer *timer,
 972                     ktime_t expires, ktime_t period)
 973 {
 974         int ret = 0;
 975
 976         mutex_lock(&rtc->ops_lock);
 977         if (timer->enabled)
 978                 rtc_timer_remove(rtc, timer);
 979
 980         timer->node.expires = expires;
 981         timer->period = period;
 982
 983         ret = rtc_timer_enqueue(rtc, timer);
 984
 985         mutex_unlock(&rtc->ops_lock);
 986         return ret;
 987 }
 988
 989 /* rtc_timer_cancel - Stops an rtc_timer
 990  * @ rtc: rtc device to be used
 991  * @ timer: timer being set
 992  *
 993  * Kernel interface to cancel an rtc_timer
 994  */
 995 void rtc_timer_cancel(struct rtc_device *rtc, struct rtc_timer *timer)
 996 {
 997         mutex_lock(&rtc->ops_lock);
 998         if (timer->enabled)
 999                 rtc_timer_remove(rtc, timer);
1000         mutex_unlock(&rtc->ops_lock);
1001 }
1002
1003 /**
1004  * rtc_read_offset - Read the amount of rtc offset in parts per billion
1005  * @ rtc: rtc device to be used
1006  * @ offset: the offset in parts per billion
1007  *
1008  * see below for details.
1009  *
1010  * Kernel interface to read rtc clock offset
1011  * Returns 0 on success, or a negative number on error.
1012  * If read_offset() is not implemented for the rtc, return -EINVAL
1013  */
1014 int rtc_read_offset(struct rtc_device *rtc, long *offset)
1015 {
1016         int ret;
1017
1018         if (!rtc->ops)
1019                 return -ENODEV;
1020
1021         if (!rtc->ops->read_offset)
1022                 return -EINVAL;
1023
1024         mutex_lock(&rtc->ops_lock);
1025         ret = rtc->ops->read_offset(rtc->dev.parent, offset);
1026         mutex_unlock(&rtc->ops_lock);
1027
1028         trace_rtc_read_offset(*offset, ret);
1029         return ret;
1030 }
1031
1032 /**
1033  * rtc_set_offset - Adjusts the duration of the average second
1034  * @ rtc: rtc device to be used
1035  * @ offset: the offset in parts per billion
1036  *
1037  * Some rtc's allow an adjustment to the average duration of a second
1038  * to compensate for differences in the actual clock rate due to temperature,
1039  * the crystal, capacitor, etc.
1040  *
1041  * The adjustment applied is as follows:
1042  *   t = t0 * (1 + offset * 1e-9)
1043  * where t0 is the measured length of 1 RTC second with offset = 0
1044  *
1045  * Kernel interface to adjust an rtc clock offset.
1046  * Return 0 on success, or a negative number on error.
1047  * If the rtc offset is not setable (or not implemented), return -EINVAL
1048  */
1049 int rtc_set_offset(struct rtc_device *rtc, long offset)
1050 {
1051         int ret;
1052
1053         if (!rtc->ops)
1054                 return -ENODEV;
1055
1056         if (!rtc->ops->set_offset)
1057                 return -EINVAL;
1058
1059         mutex_lock(&rtc->ops_lock);
1060         ret = rtc->ops->set_offset(rtc->dev.parent, offset);
1061         mutex_unlock(&rtc->ops_lock);
1062
1063         trace_rtc_set_offset(offset, ret);
1064         return ret;
1065 }