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 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 int __rtc_read_time(struct rtc_device *rtc, struct rtc_time *tm)
  24 {
  25         int err;
  26         if (!rtc->ops)
  27                 err = -ENODEV;
  28         else if (!rtc->ops->read_time)
  29                 err = -EINVAL;
  30         else {
  31                 memset(tm, 0, sizeof(struct rtc_time));
  32                 err = rtc->ops->read_time(rtc->dev.parent, tm);
  33                 if (err < 0) {
  34                         dev_err(&rtc->dev, "read_time: fail to read\n");
  35                         return err;
  36                 }
  37
  38                 err = rtc_valid_tm(tm);
  39                 if (err < 0)
  40                         dev_err(&rtc->dev, "read_time: rtc_time isn't valid\n");
  41         }
  42         return err;
  43 }
  44
  45 int rtc_read_time(struct rtc_device *rtc, struct rtc_time *tm)
  46 {
  47         int err;
  48
  49         err = mutex_lock_interruptible(&rtc->ops_lock);
  50         if (err)
  51                 return err;
  52
  53         err = __rtc_read_time(rtc, tm);
  54         mutex_unlock(&rtc->ops_lock);
  55         return err;
  56 }
  57 EXPORT_SYMBOL_GPL(rtc_read_time);
  58
  59 int rtc_set_time(struct rtc_device *rtc, struct rtc_time *tm)
  60 {
  61         int err;
  62
  63         err = rtc_valid_tm(tm);
  64         if (err != 0)
  65                 return err;
  66
  67         err = mutex_lock_interruptible(&rtc->ops_lock);
  68         if (err)
  69                 return err;
  70
  71         if (!rtc->ops)
  72                 err = -ENODEV;
  73         else if (rtc->ops->set_time)
  74                 err = rtc->ops->set_time(rtc->dev.parent, tm);
  75         else if (rtc->ops->set_mmss64) {
  76                 time64_t secs64 = rtc_tm_to_time64(tm);
  77
  78                 err = rtc->ops->set_mmss64(rtc->dev.parent, secs64);
  79         } else if (rtc->ops->set_mmss) {
  80                 time64_t secs64 = rtc_tm_to_time64(tm);
  81                 err = rtc->ops->set_mmss(rtc->dev.parent, secs64);
  82         } else
  83                 err = -EINVAL;
  84
  85         pm_stay_awake(rtc->dev.parent);
  86         mutex_unlock(&rtc->ops_lock);
  87         /* A timer might have just expired */
  88         schedule_work(&rtc->irqwork);
  89         return err;
  90 }
  91 EXPORT_SYMBOL_GPL(rtc_set_time);
  92
  93 int rtc_set_mmss(struct rtc_device *rtc, unsigned long secs)
  94 {
  95         int err;
  96
  97         err = mutex_lock_interruptible(&rtc->ops_lock);
  98         if (err)
  99                 return err;
 100
 101         if (!rtc->ops)
 102                 err = -ENODEV;
 103         else if (rtc->ops->set_mmss64)
 104                 err = rtc->ops->set_mmss64(rtc->dev.parent, secs);
 105         else if (rtc->ops->set_mmss)
 106                 err = rtc->ops->set_mmss(rtc->dev.parent, secs);
 107         else if (rtc->ops->read_time && rtc->ops->set_time) {
 108                 struct rtc_time new, old;
 109
 110                 err = rtc->ops->read_time(rtc->dev.parent, &old);
 111                 if (err == 0) {
 112                         rtc_time64_to_tm(secs, &new);
 113
 114                         /*
 115                          * avoid writing when we're going to change the day of
 116                          * the month. We will retry in the next minute. This
 117                          * basically means that if the RTC must not drift
 118                          * by more than 1 minute in 11 minutes.
 119                          */
 120                         if (!((old.tm_hour == 23 && old.tm_min == 59) ||
 121                                 (new.tm_hour == 23 && new.tm_min == 59)))
 122                                 err = rtc->ops->set_time(rtc->dev.parent,
 123                                                 &new);
 124                 }
 125         } else {
 126                 err = -EINVAL;
 127         }
 128
 129         pm_stay_awake(rtc->dev.parent);
 130         mutex_unlock(&rtc->ops_lock);
 131         /* A timer might have just expired */
 132         schedule_work(&rtc->irqwork);
 133
 134         return err;
 135 }
 136 EXPORT_SYMBOL_GPL(rtc_set_mmss);
 137
 138 static int rtc_read_alarm_internal(struct rtc_device *rtc, struct rtc_wkalrm *alarm)
 139 {
 140         int err;
 141
 142         err = mutex_lock_interruptible(&rtc->ops_lock);
 143         if (err)
 144                 return err;
 145
 146         if (rtc->ops == NULL)
 147                 err = -ENODEV;
 148         else if (!rtc->ops->read_alarm)
 149                 err = -EINVAL;
 150         else {
 151                 memset(alarm, 0, sizeof(struct rtc_wkalrm));
 152                 err = rtc->ops->read_alarm(rtc->dev.parent, alarm);
 153         }
 154
 155         mutex_unlock(&rtc->ops_lock);
 156         return err;
 157 }
 158
 159 int __rtc_read_alarm(struct rtc_device *rtc, struct rtc_wkalrm *alarm)
 160 {
 161         int err;
 162         struct rtc_time before, now;
 163         int first_time = 1;
 164         time64_t t_now, t_alm;
 165         enum { none, day, month, year } missing = none;
 166         unsigned days;
 167
 168         /* The lower level RTC driver may return -1 in some fields,
 169          * creating invalid alarm->time values, for reasons like:
 170          *
 171          *   - The hardware may not be capable of filling them in;
 172          *     many alarms match only on time-of-day fields, not
 173          *     day/month/year calendar data.
 174          *
 175          *   - Some hardware uses illegal values as "wildcard" match
 176          *     values, which non-Linux firmware (like a BIOS) may try
 177          *     to set up as e.g. "alarm 15 minutes after each hour".
 178          *     Linux uses only oneshot alarms.
 179          *
 180          * When we see that here, we deal with it by using values from
 181          * a current RTC timestamp for any missing (-1) values.  The
 182          * RTC driver prevents "periodic alarm" modes.
 183          *
 184          * But this can be racey, because some fields of the RTC timestamp
 185          * may have wrapped in the interval since we read the RTC alarm,
 186          * which would lead to us inserting inconsistent values in place
 187          * of the -1 fields.
 188          *
 189          * Reading the alarm and timestamp in the reverse sequence
 190          * would have the same race condition, and not solve the issue.
 191          *
 192          * So, we must first read the RTC timestamp,
 193          * then read the RTC alarm value,
 194          * and then read a second RTC timestamp.
 195          *
 196          * If any fields of the second timestamp have changed
 197          * when compared with the first timestamp, then we know
 198          * our timestamp may be inconsistent with that used by
 199          * the low-level rtc_read_alarm_internal() function.
 200          *
 201          * So, when the two timestamps disagree, we just loop and do
 202          * the process again to get a fully consistent set of values.
 203          *
 204          * This could all instead be done in the lower level driver,
 205          * but since more than one lower level RTC implementation needs it,
 206          * then it's probably best best to do it here instead of there..
 207          */
 208
 209         /* Get the "before" timestamp */
 210         err = rtc_read_time(rtc, &before);
 211         if (err < 0)
 212                 return err;
 213         do {
 214                 if (!first_time)
 215                         memcpy(&before, &now, sizeof(struct rtc_time));
 216                 first_time = 0;
 217
 218                 /* get the RTC alarm values, which may be incomplete */
 219                 err = rtc_read_alarm_internal(rtc, alarm);
 220                 if (err)
 221                         return err;
 222
 223                 /* full-function RTCs won't have such missing fields */
 224                 if (rtc_valid_tm(&alarm->time) == 0)
 225                         return 0;
 226
 227                 /* get the "after" timestamp, to detect wrapped fields */
 228                 err = rtc_read_time(rtc, &now);
 229                 if (err < 0)
 230                         return err;
 231
 232                 /* note that tm_sec is a "don't care" value here: */
 233         } while (   before.tm_min   != now.tm_min
 234                  || before.tm_hour  != now.tm_hour
 235                  || before.tm_mon   != now.tm_mon
 236                  || before.tm_year  != now.tm_year);
 237
 238         /* Fill in the missing alarm fields using the timestamp; we
 239          * know there's at least one since alarm->time is invalid.
 240          */
 241         if (alarm->time.tm_sec == -1)
 242                 alarm->time.tm_sec = now.tm_sec;
 243         if (alarm->time.tm_min == -1)
 244                 alarm->time.tm_min = now.tm_min;
 245         if (alarm->time.tm_hour == -1)
 246                 alarm->time.tm_hour = now.tm_hour;
 247
 248         /* For simplicity, only support date rollover for now */
 249         if (alarm->time.tm_mday < 1 || alarm->time.tm_mday > 31) {
 250                 alarm->time.tm_mday = now.tm_mday;
 251                 missing = day;
 252         }
 253         if ((unsigned)alarm->time.tm_mon >= 12) {
 254                 alarm->time.tm_mon = now.tm_mon;
 255                 if (missing == none)
 256                         missing = month;
 257         }
 258         if (alarm->time.tm_year == -1) {
 259                 alarm->time.tm_year = now.tm_year;
 260                 if (missing == none)
 261                         missing = year;
 262         }
 263
 264         /* with luck, no rollover is needed */
 265         t_now = rtc_tm_to_time64(&now);
 266         t_alm = rtc_tm_to_time64(&alarm->time);
 267         if (t_now < t_alm)
 268                 goto done;
 269
 270         switch (missing) {
 271
 272         /* 24 hour rollover ... if it's now 10am Monday, an alarm that
 273          * that will trigger at 5am will do so at 5am Tuesday, which
 274          * could also be in the next month or year.  This is a common
 275          * case, especially for PCs.
 276          */
 277         case day:
 278                 dev_dbg(&rtc->dev, "alarm rollover: %s\n", "day");
 279                 t_alm += 24 * 60 * 60;
 280                 rtc_time64_to_tm(t_alm, &alarm->time);
 281                 break;
 282
 283         /* Month rollover ... if it's the 31th, an alarm on the 3rd will
 284          * be next month.  An alarm matching on the 30th, 29th, or 28th
 285          * may end up in the month after that!  Many newer PCs support
 286          * this type of alarm.
 287          */
 288         case month:
 289                 dev_dbg(&rtc->dev, "alarm rollover: %s\n", "month");
 290                 do {
 291                         if (alarm->time.tm_mon < 11)
 292                                 alarm->time.tm_mon++;
 293                         else {
 294                                 alarm->time.tm_mon = 0;
 295                                 alarm->time.tm_year++;
 296                         }
 297                         days = rtc_month_days(alarm->time.tm_mon,
 298                                         alarm->time.tm_year);
 299                 } while (days < alarm->time.tm_mday);
 300                 break;
 301
 302         /* Year rollover ... easy except for leap years! */
 303         case year:
 304                 dev_dbg(&rtc->dev, "alarm rollover: %s\n", "year");
 305                 do {
 306                         alarm->time.tm_year++;
 307                 } while (!is_leap_year(alarm->time.tm_year + 1900)
 308                         && rtc_valid_tm(&alarm->time) != 0);
 309                 break;
 310
 311         default:
 312                 dev_warn(&rtc->dev, "alarm rollover not handled\n");
 313         }
 314
 315 done:
 316         err = rtc_valid_tm(&alarm->time);
 317
 318         if (err) {
 319                 dev_warn(&rtc->dev, "invalid alarm value: %d-%d-%d %d:%d:%d\n",
 320                         alarm->time.tm_year + 1900, alarm->time.tm_mon + 1,
 321                         alarm->time.tm_mday, alarm->time.tm_hour, alarm->time.tm_min,
 322                         alarm->time.tm_sec);
 323         }
 324
 325         return err;
 326 }
 327
 328 int rtc_read_alarm(struct rtc_device *rtc, struct rtc_wkalrm *alarm)
 329 {
 330         int err;
 331
 332         err = mutex_lock_interruptible(&rtc->ops_lock);
 333         if (err)
 334                 return err;
 335         if (rtc->ops == NULL)
 336                 err = -ENODEV;
 337         else if (!rtc->ops->read_alarm)
 338                 err = -EINVAL;
 339         else {
 340                 memset(alarm, 0, sizeof(struct rtc_wkalrm));
 341                 alarm->enabled = rtc->aie_timer.enabled;
 342                 alarm->time = rtc_ktime_to_tm(rtc->aie_timer.node.expires);
 343         }
 344         mutex_unlock(&rtc->ops_lock);
 345
 346         return err;
 347 }
 348 EXPORT_SYMBOL_GPL(rtc_read_alarm);
 349
 350 static int __rtc_set_alarm(struct rtc_device *rtc, struct rtc_wkalrm *alarm)
 351 {
 352         struct rtc_time tm;
 353         time64_t now, scheduled;
 354         int err;
 355
 356         err = rtc_valid_tm(&alarm->time);
 357         if (err)
 358                 return err;
 359         scheduled = rtc_tm_to_time64(&alarm->time);
 360
 361         /* Make sure we're not setting alarms in the past */
 362         err = __rtc_read_time(rtc, &tm);
 363         if (err)
 364                 return err;
 365         now = rtc_tm_to_time64(&tm);
 366         if (scheduled <= now)
 367                 return -ETIME;
 368         /*
 369          * XXX - We just checked to make sure the alarm time is not
 370          * in the past, but there is still a race window where if
 371          * the is alarm set for the next second and the second ticks
 372          * over right here, before we set the alarm.
 373          */
 374
 375         if (!rtc->ops)
 376                 err = -ENODEV;
 377         else if (!rtc->ops->set_alarm)
 378                 err = -EINVAL;
 379         else
 380                 err = rtc->ops->set_alarm(rtc->dev.parent, alarm);
 381
 382         return err;
 383 }
 384
 385 int rtc_set_alarm(struct rtc_device *rtc, struct rtc_wkalrm *alarm)
 386 {
 387         int err;
 388
 389         err = rtc_valid_tm(&alarm->time);
 390         if (err != 0)
 391                 return err;
 392
 393         err = mutex_lock_interruptible(&rtc->ops_lock);
 394         if (err)
 395                 return err;
 396         if (rtc->aie_timer.enabled)
 397                 rtc_timer_remove(rtc, &rtc->aie_timer);
 398
 399         rtc->aie_timer.node.expires = rtc_tm_to_ktime(alarm->time);
 400         rtc->aie_timer.period = ktime_set(0, 0);
 401         if (alarm->enabled)
 402                 err = rtc_timer_enqueue(rtc, &rtc->aie_timer);
 403
 404         mutex_unlock(&rtc->ops_lock);
 405         return err;
 406 }
 407 EXPORT_SYMBOL_GPL(rtc_set_alarm);
 408
 409 /* Called once per device from rtc_device_register */
 410 int rtc_initialize_alarm(struct rtc_device *rtc, struct rtc_wkalrm *alarm)
 411 {
 412         int err;
 413         struct rtc_time now;
 414
 415         err = rtc_valid_tm(&alarm->time);
 416         if (err != 0)
 417                 return err;
 418
 419         err = rtc_read_time(rtc, &now);
 420         if (err)
 421                 return err;
 422
 423         err = mutex_lock_interruptible(&rtc->ops_lock);
 424         if (err)
 425                 return err;
 426
 427         rtc->aie_timer.node.expires = rtc_tm_to_ktime(alarm->time);
 428         rtc->aie_timer.period = ktime_set(0, 0);
 429
 430         /* Alarm has to be enabled & in the futrure for us to enqueue it */
 431         if (alarm->enabled && (rtc_tm_to_ktime(now).tv64 <
 432                          rtc->aie_timer.node.expires.tv64)) {
 433
 434                 rtc->aie_timer.enabled = 1;
 435                 timerqueue_add(&rtc->timerqueue, &rtc->aie_timer.node);
 436         }
 437         mutex_unlock(&rtc->ops_lock);
 438         return err;
 439 }
 440 EXPORT_SYMBOL_GPL(rtc_initialize_alarm);
 441
 442
 443
 444 int rtc_alarm_irq_enable(struct rtc_device *rtc, unsigned int enabled)
 445 {
 446         int err = mutex_lock_interruptible(&rtc->ops_lock);
 447         if (err)
 448                 return err;
 449
 450         if (rtc->aie_timer.enabled != enabled) {
 451                 if (enabled)
 452                         err = rtc_timer_enqueue(rtc, &rtc->aie_timer);
 453                 else
 454                         rtc_timer_remove(rtc, &rtc->aie_timer);
 455         }
 456
 457         if (err)
 458                 /* nothing */;
 459         else if (!rtc->ops)
 460                 err = -ENODEV;
 461         else if (!rtc->ops->alarm_irq_enable)
 462                 err = -EINVAL;
 463         else
 464                 err = rtc->ops->alarm_irq_enable(rtc->dev.parent, enabled);
 465
 466         mutex_unlock(&rtc->ops_lock);
 467         return err;
 468 }
 469 EXPORT_SYMBOL_GPL(rtc_alarm_irq_enable);
 470
 471 int rtc_update_irq_enable(struct rtc_device *rtc, unsigned int enabled)
 472 {
 473         int err = mutex_lock_interruptible(&rtc->ops_lock);
 474         if (err)
 475                 return err;
 476
 477 #ifdef CONFIG_RTC_INTF_DEV_UIE_EMUL
 478         if (enabled == 0 && rtc->uie_irq_active) {
 479                 mutex_unlock(&rtc->ops_lock);
 480                 return rtc_dev_update_irq_enable_emul(rtc, 0);
 481         }
 482 #endif
 483         /* make sure we're changing state */
 484         if (rtc->uie_rtctimer.enabled == enabled)
 485                 goto out;
 486
 487         if (rtc->uie_unsupported) {
 488                 err = -EINVAL;
 489                 goto out;
 490         }
 491
 492         if (enabled) {
 493                 struct rtc_time tm;
 494                 ktime_t now, onesec;
 495
 496                 __rtc_read_time(rtc, &tm);
 497                 onesec = ktime_set(1, 0);
 498                 now = rtc_tm_to_ktime(tm);
 499                 rtc->uie_rtctimer.node.expires = ktime_add(now, onesec);
 500                 rtc->uie_rtctimer.period = ktime_set(1, 0);
 501                 err = rtc_timer_enqueue(rtc, &rtc->uie_rtctimer);
 502         } else
 503                 rtc_timer_remove(rtc, &rtc->uie_rtctimer);
 504
 505 out:
 506         mutex_unlock(&rtc->ops_lock);
 507 #ifdef CONFIG_RTC_INTF_DEV_UIE_EMUL
 508         /*
 509          * Enable emulation if the driver did not provide
 510          * the update_irq_enable function pointer or if returned
 511          * -EINVAL to signal that it has been configured without
 512          * interrupts or that are not available at the moment.
 513          */
 514         if (err == -EINVAL)
 515                 err = rtc_dev_update_irq_enable_emul(rtc, enabled);
 516 #endif
 517         return err;
 518
 519 }
 520 EXPORT_SYMBOL_GPL(rtc_update_irq_enable);
 521
 522
 523 /**
 524  * rtc_handle_legacy_irq - AIE, UIE and PIE event hook
 525  * @rtc: pointer to the rtc device
 526  *
 527  * This function is called when an AIE, UIE or PIE mode interrupt
 528  * has occurred (or been emulated).
 529  *
 530  * Triggers the registered irq_task function callback.
 531  */
 532 void rtc_handle_legacy_irq(struct rtc_device *rtc, int num, int mode)
 533 {
 534         unsigned long flags;
 535
 536         /* mark one irq of the appropriate mode */
 537         spin_lock_irqsave(&rtc->irq_lock, flags);
 538         rtc->irq_data = (rtc->irq_data + (num << 8)) | (RTC_IRQF|mode);
 539         spin_unlock_irqrestore(&rtc->irq_lock, flags);
 540
 541         /* call the task func */
 542         spin_lock_irqsave(&rtc->irq_task_lock, flags);
 543         if (rtc->irq_task)
 544                 rtc->irq_task->func(rtc->irq_task->private_data);
 545         spin_unlock_irqrestore(&rtc->irq_task_lock, flags);
 546
 547         wake_up_interruptible(&rtc->irq_queue);
 548         kill_fasync(&rtc->async_queue, SIGIO, POLL_IN);
 549 }
 550
 551
 552 /**
 553  * rtc_aie_update_irq - AIE mode rtctimer hook
 554  * @private: pointer to the rtc_device
 555  *
 556  * This functions is called when the aie_timer expires.
 557  */
 558 void rtc_aie_update_irq(void *private)
 559 {
 560         struct rtc_device *rtc = (struct rtc_device *)private;
 561         rtc_handle_legacy_irq(rtc, 1, RTC_AF);
 562 }
 563
 564
 565 /**
 566  * rtc_uie_update_irq - UIE mode rtctimer hook
 567  * @private: pointer to the rtc_device
 568  *
 569  * This functions is called when the uie_timer expires.
 570  */
 571 void rtc_uie_update_irq(void *private)
 572 {
 573         struct rtc_device *rtc = (struct rtc_device *)private;
 574         rtc_handle_legacy_irq(rtc, 1,  RTC_UF);
 575 }
 576
 577
 578 /**
 579  * rtc_pie_update_irq - PIE mode hrtimer hook
 580  * @timer: pointer to the pie mode hrtimer
 581  *
 582  * This function is used to emulate PIE mode interrupts
 583  * using an hrtimer. This function is called when the periodic
 584  * hrtimer expires.
 585  */
 586 enum hrtimer_restart rtc_pie_update_irq(struct hrtimer *timer)
 587 {
 588         struct rtc_device *rtc;
 589         ktime_t period;
 590         int count;
 591         rtc = container_of(timer, struct rtc_device, pie_timer);
 592
 593         period = ktime_set(0, NSEC_PER_SEC/rtc->irq_freq);
 594         count = hrtimer_forward_now(timer, period);
 595
 596         rtc_handle_legacy_irq(rtc, count, RTC_PF);
 597
 598         return HRTIMER_RESTART;
 599 }
 600
 601 /**
 602  * rtc_update_irq - Triggered when a RTC interrupt occurs.
 603  * @rtc: the rtc device
 604  * @num: how many irqs are being reported (usually one)
 605  * @events: mask of RTC_IRQF with one or more of RTC_PF, RTC_AF, RTC_UF
 606  * Context: any
 607  */
 608 void rtc_update_irq(struct rtc_device *rtc,
 609                 unsigned long num, unsigned long events)
 610 {
 611         if (unlikely(IS_ERR_OR_NULL(rtc)))
 612                 return;
 613
 614         pm_stay_awake(rtc->dev.parent);
 615         schedule_work(&rtc->irqwork);
 616 }
 617 EXPORT_SYMBOL_GPL(rtc_update_irq);
 618
 619 static int __rtc_match(struct device *dev, const void *data)
 620 {
 621         const char *name = data;
 622
 623         if (strcmp(dev_name(dev), name) == 0)
 624                 return 1;
 625         return 0;
 626 }
 627
 628 struct rtc_device *rtc_class_open(const char *name)
 629 {
 630         struct device *dev;
 631         struct rtc_device *rtc = NULL;
 632
 633         dev = class_find_device(rtc_class, NULL, name, __rtc_match);
 634         if (dev)
 635                 rtc = to_rtc_device(dev);
 636
 637         if (rtc) {
 638                 if (!try_module_get(rtc->owner)) {
 639                         put_device(dev);
 640                         rtc = NULL;
 641                 }
 642         }
 643
 644         return rtc;
 645 }
 646 EXPORT_SYMBOL_GPL(rtc_class_open);
 647
 648 void rtc_class_close(struct rtc_device *rtc)
 649 {
 650         module_put(rtc->owner);
 651         put_device(&rtc->dev);
 652 }
 653 EXPORT_SYMBOL_GPL(rtc_class_close);
 654
 655 int rtc_irq_register(struct rtc_device *rtc, struct rtc_task *task)
 656 {
 657         int retval = -EBUSY;
 658
 659         if (task == NULL || task->func == NULL)
 660                 return -EINVAL;
 661
 662         /* Cannot register while the char dev is in use */
 663         if (test_and_set_bit_lock(RTC_DEV_BUSY, &rtc->flags))
 664                 return -EBUSY;
 665
 666         spin_lock_irq(&rtc->irq_task_lock);
 667         if (rtc->irq_task == NULL) {
 668                 rtc->irq_task = task;
 669                 retval = 0;
 670         }
 671         spin_unlock_irq(&rtc->irq_task_lock);
 672
 673         clear_bit_unlock(RTC_DEV_BUSY, &rtc->flags);
 674
 675         return retval;
 676 }
 677 EXPORT_SYMBOL_GPL(rtc_irq_register);
 678
 679 void rtc_irq_unregister(struct rtc_device *rtc, struct rtc_task *task)
 680 {
 681         spin_lock_irq(&rtc->irq_task_lock);
 682         if (rtc->irq_task == task)
 683                 rtc->irq_task = NULL;
 684         spin_unlock_irq(&rtc->irq_task_lock);
 685 }
 686 EXPORT_SYMBOL_GPL(rtc_irq_unregister);
 687
 688 static int rtc_update_hrtimer(struct rtc_device *rtc, int enabled)
 689 {
 690         /*
 691          * We always cancel the timer here first, because otherwise
 692          * we could run into BUG_ON(timer->state != HRTIMER_STATE_CALLBACK);
 693          * when we manage to start the timer before the callback
 694          * returns HRTIMER_RESTART.
 695          *
 696          * We cannot use hrtimer_cancel() here as a running callback
 697          * could be blocked on rtc->irq_task_lock and hrtimer_cancel()
 698          * would spin forever.
 699          */
 700         if (hrtimer_try_to_cancel(&rtc->pie_timer) < 0)
 701                 return -1;
 702
 703         if (enabled) {
 704                 ktime_t period = ktime_set(0, NSEC_PER_SEC / rtc->irq_freq);
 705
 706                 hrtimer_start(&rtc->pie_timer, period, HRTIMER_MODE_REL);
 707         }
 708         return 0;
 709 }
 710
 711 /**
 712  * rtc_irq_set_state - enable/disable 2^N Hz periodic IRQs
 713  * @rtc: the rtc device
 714  * @task: currently registered with rtc_irq_register()
 715  * @enabled: true to enable periodic IRQs
 716  * Context: any
 717  *
 718  * Note that rtc_irq_set_freq() should previously have been used to
 719  * specify the desired frequency of periodic IRQ task->func() callbacks.
 720  */
 721 int rtc_irq_set_state(struct rtc_device *rtc, struct rtc_task *task, int enabled)
 722 {
 723         int err = 0;
 724         unsigned long flags;
 725
 726 retry:
 727         spin_lock_irqsave(&rtc->irq_task_lock, flags);
 728         if (rtc->irq_task != NULL && task == NULL)
 729                 err = -EBUSY;
 730         else if (rtc->irq_task != task)
 731                 err = -EACCES;
 732         else {
 733                 if (rtc_update_hrtimer(rtc, enabled) < 0) {
 734                         spin_unlock_irqrestore(&rtc->irq_task_lock, flags);
 735                         cpu_relax();
 736                         goto retry;
 737                 }
 738                 rtc->pie_enabled = enabled;
 739         }
 740         spin_unlock_irqrestore(&rtc->irq_task_lock, flags);
 741         return err;
 742 }
 743 EXPORT_SYMBOL_GPL(rtc_irq_set_state);
 744
 745 /**
 746  * rtc_irq_set_freq - set 2^N Hz periodic IRQ frequency for IRQ
 747  * @rtc: the rtc device
 748  * @task: currently registered with rtc_irq_register()
 749  * @freq: positive frequency with which task->func() will be called
 750  * Context: any
 751  *
 752  * Note that rtc_irq_set_state() is used to enable or disable the
 753  * periodic IRQs.
 754  */
 755 int rtc_irq_set_freq(struct rtc_device *rtc, struct rtc_task *task, int freq)
 756 {
 757         int err = 0;
 758         unsigned long flags;
 759
 760         if (freq <= 0 || freq > RTC_MAX_FREQ)
 761                 return -EINVAL;
 762 retry:
 763         spin_lock_irqsave(&rtc->irq_task_lock, flags);
 764         if (rtc->irq_task != NULL && task == NULL)
 765                 err = -EBUSY;
 766         else if (rtc->irq_task != task)
 767                 err = -EACCES;
 768         else {
 769                 rtc->irq_freq = freq;
 770                 if (rtc->pie_enabled && rtc_update_hrtimer(rtc, 1) < 0) {
 771                         spin_unlock_irqrestore(&rtc->irq_task_lock, flags);
 772                         cpu_relax();
 773                         goto retry;
 774                 }
 775         }
 776         spin_unlock_irqrestore(&rtc->irq_task_lock, flags);
 777         return err;
 778 }
 779 EXPORT_SYMBOL_GPL(rtc_irq_set_freq);
 780
 781 /**
 782  * rtc_timer_enqueue - Adds a rtc_timer to the rtc_device timerqueue
 783  * @rtc rtc device
 784  * @timer timer being added.
 785  *
 786  * Enqueues a timer onto the rtc devices timerqueue and sets
 787  * the next alarm event appropriately.
 788  *
 789  * Sets the enabled bit on the added timer.
 790  *
 791  * Must hold ops_lock for proper serialization of timerqueue
 792  */
 793 static int rtc_timer_enqueue(struct rtc_device *rtc, struct rtc_timer *timer)
 794 {
 795         timer->enabled = 1;
 796         timerqueue_add(&rtc->timerqueue, &timer->node);
 797         if (&timer->node == timerqueue_getnext(&rtc->timerqueue)) {
 798                 struct rtc_wkalrm alarm;
 799                 int err;
 800                 alarm.time = rtc_ktime_to_tm(timer->node.expires);
 801                 alarm.enabled = 1;
 802                 err = __rtc_set_alarm(rtc, &alarm);
 803                 if (err == -ETIME) {
 804                         pm_stay_awake(rtc->dev.parent);
 805                         schedule_work(&rtc->irqwork);
 806                 } else if (err) {
 807                         timerqueue_del(&rtc->timerqueue, &timer->node);
 808                         timer->enabled = 0;
 809                         return err;
 810                 }
 811         }
 812         return 0;
 813 }
 814
 815 static void rtc_alarm_disable(struct rtc_device *rtc)
 816 {
 817         if (!rtc->ops || !rtc->ops->alarm_irq_enable)
 818                 return;
 819
 820         rtc->ops->alarm_irq_enable(rtc->dev.parent, false);
 821 }
 822
 823 /**
 824  * rtc_timer_remove - Removes a rtc_timer from the rtc_device timerqueue
 825  * @rtc rtc device
 826  * @timer timer being removed.
 827  *
 828  * Removes a timer onto the rtc devices timerqueue and sets
 829  * the next alarm event appropriately.
 830  *
 831  * Clears the enabled bit on the removed timer.
 832  *
 833  * Must hold ops_lock for proper serialization of timerqueue
 834  */
 835 static void rtc_timer_remove(struct rtc_device *rtc, struct rtc_timer *timer)
 836 {
 837         struct timerqueue_node *next = timerqueue_getnext(&rtc->timerqueue);
 838         timerqueue_del(&rtc->timerqueue, &timer->node);
 839         timer->enabled = 0;
 840         if (next == &timer->node) {
 841                 struct rtc_wkalrm alarm;
 842                 int err;
 843                 next = timerqueue_getnext(&rtc->timerqueue);
 844                 if (!next) {
 845                         rtc_alarm_disable(rtc);
 846                         return;
 847                 }
 848                 alarm.time = rtc_ktime_to_tm(next->expires);
 849                 alarm.enabled = 1;
 850                 err = __rtc_set_alarm(rtc, &alarm);
 851                 if (err == -ETIME) {
 852                         pm_stay_awake(rtc->dev.parent);
 853                         schedule_work(&rtc->irqwork);
 854                 }
 855         }
 856 }
 857
 858 /**
 859  * rtc_timer_do_work - Expires rtc timers
 860  * @rtc rtc device
 861  * @timer timer being removed.
 862  *
 863  * Expires rtc timers. Reprograms next alarm event if needed.
 864  * Called via worktask.
 865  *
 866  * Serializes access to timerqueue via ops_lock mutex
 867  */
 868 void rtc_timer_do_work(struct work_struct *work)
 869 {
 870         struct rtc_timer *timer;
 871         struct timerqueue_node *next;
 872         ktime_t now;
 873         struct rtc_time tm;
 874
 875         struct rtc_device *rtc =
 876                 container_of(work, struct rtc_device, irqwork);
 877
 878         mutex_lock(&rtc->ops_lock);
 879 again:
 880         __rtc_read_time(rtc, &tm);
 881         now = rtc_tm_to_ktime(tm);
 882         while ((next = timerqueue_getnext(&rtc->timerqueue))) {
 883                 if (next->expires.tv64 > now.tv64)
 884                         break;
 885
 886                 /* expire timer */
 887                 timer = container_of(next, struct rtc_timer, node);
 888                 timerqueue_del(&rtc->timerqueue, &timer->node);
 889                 timer->enabled = 0;
 890                 if (timer->task.func)
 891                         timer->task.func(timer->task.private_data);
 892
 893                 /* Re-add/fwd periodic timers */
 894                 if (ktime_to_ns(timer->period)) {
 895                         timer->node.expires = ktime_add(timer->node.expires,
 896                                                         timer->period);
 897                         timer->enabled = 1;
 898                         timerqueue_add(&rtc->timerqueue, &timer->node);
 899                 }
 900         }
 901
 902         /* Set next alarm */
 903         if (next) {
 904                 struct rtc_wkalrm alarm;
 905                 int err;
 906                 int retry = 3;
 907
 908                 alarm.time = rtc_ktime_to_tm(next->expires);
 909                 alarm.enabled = 1;
 910 reprogram:
 911                 err = __rtc_set_alarm(rtc, &alarm);
 912                 if (err == -ETIME)
 913                         goto again;
 914                 else if (err) {
 915                         if (retry-- > 0)
 916                                 goto reprogram;
 917
 918                         timer = container_of(next, struct rtc_timer, node);
 919                         timerqueue_del(&rtc->timerqueue, &timer->node);
 920                         timer->enabled = 0;
 921                         dev_err(&rtc->dev, "__rtc_set_alarm: err=%d\n", err);
 922                         goto again;
 923                 }
 924         } else
 925                 rtc_alarm_disable(rtc);
 926
 927         pm_relax(rtc->dev.parent);
 928         mutex_unlock(&rtc->ops_lock);
 929 }
 930
 931
 932 /* rtc_timer_init - Initializes an rtc_timer
 933  * @timer: timer to be intiialized
 934  * @f: function pointer to be called when timer fires
 935  * @data: private data passed to function pointer
 936  *
 937  * Kernel interface to initializing an rtc_timer.
 938  */
 939 void rtc_timer_init(struct rtc_timer *timer, void (*f)(void *p), void *data)
 940 {
 941         timerqueue_init(&timer->node);
 942         timer->enabled = 0;
 943         timer->task.func = f;
 944         timer->task.private_data = data;
 945 }
 946
 947 /* rtc_timer_start - Sets an rtc_timer to fire in the future
 948  * @ rtc: rtc device to be used
 949  * @ timer: timer being set
 950  * @ expires: time at which to expire the timer
 951  * @ period: period that the timer will recur
 952  *
 953  * Kernel interface to set an rtc_timer
 954  */
 955 int rtc_timer_start(struct rtc_device *rtc, struct rtc_timer *timer,
 956                         ktime_t expires, ktime_t period)
 957 {
 958         int ret = 0;
 959         mutex_lock(&rtc->ops_lock);
 960         if (timer->enabled)
 961                 rtc_timer_remove(rtc, timer);
 962
 963         timer->node.expires = expires;
 964         timer->period = period;
 965
 966         ret = rtc_timer_enqueue(rtc, timer);
 967
 968         mutex_unlock(&rtc->ops_lock);
 969         return ret;
 970 }
 971
 972 /* rtc_timer_cancel - Stops an rtc_timer
 973  * @ rtc: rtc device to be used
 974  * @ timer: timer being set
 975  *
 976  * Kernel interface to cancel an rtc_timer
 977  */
 978 int rtc_timer_cancel(struct rtc_device *rtc, struct rtc_timer *timer)
 979 {
 980         int ret = 0;
 981         mutex_lock(&rtc->ops_lock);
 982         if (timer->enabled)
 983                 rtc_timer_remove(rtc, timer);
 984         mutex_unlock(&rtc->ops_lock);
 985         return ret;
 986 }
 987
 988