linux/drivers/rtc/interface.c
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   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
  20static int rtc_timer_enqueue(struct rtc_device *rtc, struct rtc_timer *timer);
  21static void rtc_timer_remove(struct rtc_device *rtc, struct rtc_timer *timer);
  22
  23static 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        }
  34        return err;
  35}
  36
  37int rtc_read_time(struct rtc_device *rtc, struct rtc_time *tm)
  38{
  39        int err;
  40
  41        err = mutex_lock_interruptible(&rtc->ops_lock);
  42        if (err)
  43                return err;
  44
  45        err = __rtc_read_time(rtc, tm);
  46        mutex_unlock(&rtc->ops_lock);
  47        return err;
  48}
  49EXPORT_SYMBOL_GPL(rtc_read_time);
  50
  51int rtc_set_time(struct rtc_device *rtc, struct rtc_time *tm)
  52{
  53        int err;
  54
  55        err = rtc_valid_tm(tm);
  56        if (err != 0)
  57                return err;
  58
  59        err = mutex_lock_interruptible(&rtc->ops_lock);
  60        if (err)
  61                return err;
  62
  63        if (!rtc->ops)
  64                err = -ENODEV;
  65        else if (rtc->ops->set_time)
  66                err = rtc->ops->set_time(rtc->dev.parent, tm);
  67        else if (rtc->ops->set_mmss) {
  68                unsigned long secs;
  69                err = rtc_tm_to_time(tm, &secs);
  70                if (err == 0)
  71                        err = rtc->ops->set_mmss(rtc->dev.parent, secs);
  72        } else
  73                err = -EINVAL;
  74
  75        mutex_unlock(&rtc->ops_lock);
  76        /* A timer might have just expired */
  77        schedule_work(&rtc->irqwork);
  78        return err;
  79}
  80EXPORT_SYMBOL_GPL(rtc_set_time);
  81
  82int rtc_set_mmss(struct rtc_device *rtc, unsigned long secs)
  83{
  84        int err;
  85
  86        err = mutex_lock_interruptible(&rtc->ops_lock);
  87        if (err)
  88                return err;
  89
  90        if (!rtc->ops)
  91                err = -ENODEV;
  92        else if (rtc->ops->set_mmss)
  93                err = rtc->ops->set_mmss(rtc->dev.parent, secs);
  94        else if (rtc->ops->read_time && rtc->ops->set_time) {
  95                struct rtc_time new, old;
  96
  97                err = rtc->ops->read_time(rtc->dev.parent, &old);
  98                if (err == 0) {
  99                        rtc_time_to_tm(secs, &new);
 100
 101                        /*
 102                         * avoid writing when we're going to change the day of
 103                         * the month. We will retry in the next minute. This
 104                         * basically means that if the RTC must not drift
 105                         * by more than 1 minute in 11 minutes.
 106                         */
 107                        if (!((old.tm_hour == 23 && old.tm_min == 59) ||
 108                                (new.tm_hour == 23 && new.tm_min == 59)))
 109                                err = rtc->ops->set_time(rtc->dev.parent,
 110                                                &new);
 111                }
 112        }
 113        else
 114                err = -EINVAL;
 115
 116        mutex_unlock(&rtc->ops_lock);
 117        /* A timer might have just expired */
 118        schedule_work(&rtc->irqwork);
 119
 120        return err;
 121}
 122EXPORT_SYMBOL_GPL(rtc_set_mmss);
 123
 124static int rtc_read_alarm_internal(struct rtc_device *rtc, struct rtc_wkalrm *alarm)
 125{
 126        int err;
 127
 128        err = mutex_lock_interruptible(&rtc->ops_lock);
 129        if (err)
 130                return err;
 131
 132        if (rtc->ops == NULL)
 133                err = -ENODEV;
 134        else if (!rtc->ops->read_alarm)
 135                err = -EINVAL;
 136        else {
 137                memset(alarm, 0, sizeof(struct rtc_wkalrm));
 138                err = rtc->ops->read_alarm(rtc->dev.parent, alarm);
 139        }
 140
 141        mutex_unlock(&rtc->ops_lock);
 142        return err;
 143}
 144
 145int __rtc_read_alarm(struct rtc_device *rtc, struct rtc_wkalrm *alarm)
 146{
 147        int err;
 148        struct rtc_time before, now;
 149        int first_time = 1;
 150        unsigned long t_now, t_alm;
 151        enum { none, day, month, year } missing = none;
 152        unsigned days;
 153
 154        /* The lower level RTC driver may return -1 in some fields,
 155         * creating invalid alarm->time values, for reasons like:
 156         *
 157         *   - The hardware may not be capable of filling them in;
 158         *     many alarms match only on time-of-day fields, not
 159         *     day/month/year calendar data.
 160         *
 161         *   - Some hardware uses illegal values as "wildcard" match
 162         *     values, which non-Linux firmware (like a BIOS) may try
 163         *     to set up as e.g. "alarm 15 minutes after each hour".
 164         *     Linux uses only oneshot alarms.
 165         *
 166         * When we see that here, we deal with it by using values from
 167         * a current RTC timestamp for any missing (-1) values.  The
 168         * RTC driver prevents "periodic alarm" modes.
 169         *
 170         * But this can be racey, because some fields of the RTC timestamp
 171         * may have wrapped in the interval since we read the RTC alarm,
 172         * which would lead to us inserting inconsistent values in place
 173         * of the -1 fields.
 174         *
 175         * Reading the alarm and timestamp in the reverse sequence
 176         * would have the same race condition, and not solve the issue.
 177         *
 178         * So, we must first read the RTC timestamp,
 179         * then read the RTC alarm value,
 180         * and then read a second RTC timestamp.
 181         *
 182         * If any fields of the second timestamp have changed
 183         * when compared with the first timestamp, then we know
 184         * our timestamp may be inconsistent with that used by
 185         * the low-level rtc_read_alarm_internal() function.
 186         *
 187         * So, when the two timestamps disagree, we just loop and do
 188         * the process again to get a fully consistent set of values.
 189         *
 190         * This could all instead be done in the lower level driver,
 191         * but since more than one lower level RTC implementation needs it,
 192         * then it's probably best best to do it here instead of there..
 193         */
 194
 195        /* Get the "before" timestamp */
 196        err = rtc_read_time(rtc, &before);
 197        if (err < 0)
 198                return err;
 199        do {
 200                if (!first_time)
 201                        memcpy(&before, &now, sizeof(struct rtc_time));
 202                first_time = 0;
 203
 204                /* get the RTC alarm values, which may be incomplete */
 205                err = rtc_read_alarm_internal(rtc, alarm);
 206                if (err)
 207                        return err;
 208
 209                /* full-function RTCs won't have such missing fields */
 210                if (rtc_valid_tm(&alarm->time) == 0)
 211                        return 0;
 212
 213                /* get the "after" timestamp, to detect wrapped fields */
 214                err = rtc_read_time(rtc, &now);
 215                if (err < 0)
 216                        return err;
 217
 218                /* note that tm_sec is a "don't care" value here: */
 219        } while (   before.tm_min   != now.tm_min
 220                 || before.tm_hour  != now.tm_hour
 221                 || before.tm_mon   != now.tm_mon
 222                 || before.tm_year  != now.tm_year);
 223
 224        /* Fill in the missing alarm fields using the timestamp; we
 225         * know there's at least one since alarm->time is invalid.
 226         */
 227        if (alarm->time.tm_sec == -1)
 228                alarm->time.tm_sec = now.tm_sec;
 229        if (alarm->time.tm_min == -1)
 230                alarm->time.tm_min = now.tm_min;
 231        if (alarm->time.tm_hour == -1)
 232                alarm->time.tm_hour = now.tm_hour;
 233
 234        /* For simplicity, only support date rollover for now */
 235        if (alarm->time.tm_mday < 1 || alarm->time.tm_mday > 31) {
 236                alarm->time.tm_mday = now.tm_mday;
 237                missing = day;
 238        }
 239        if ((unsigned)alarm->time.tm_mon >= 12) {
 240                alarm->time.tm_mon = now.tm_mon;
 241                if (missing == none)
 242                        missing = month;
 243        }
 244        if (alarm->time.tm_year == -1) {
 245                alarm->time.tm_year = now.tm_year;
 246                if (missing == none)
 247                        missing = year;
 248        }
 249
 250        /* with luck, no rollover is needed */
 251        rtc_tm_to_time(&now, &t_now);
 252        rtc_tm_to_time(&alarm->time, &t_alm);
 253        if (t_now < t_alm)
 254                goto done;
 255
 256        switch (missing) {
 257
 258        /* 24 hour rollover ... if it's now 10am Monday, an alarm that
 259         * that will trigger at 5am will do so at 5am Tuesday, which
 260         * could also be in the next month or year.  This is a common
 261         * case, especially for PCs.
 262         */
 263        case day:
 264                dev_dbg(&rtc->dev, "alarm rollover: %s\n", "day");
 265                t_alm += 24 * 60 * 60;
 266                rtc_time_to_tm(t_alm, &alarm->time);
 267                break;
 268
 269        /* Month rollover ... if it's the 31th, an alarm on the 3rd will
 270         * be next month.  An alarm matching on the 30th, 29th, or 28th
 271         * may end up in the month after that!  Many newer PCs support
 272         * this type of alarm.
 273         */
 274        case month:
 275                dev_dbg(&rtc->dev, "alarm rollover: %s\n", "month");
 276                do {
 277                        if (alarm->time.tm_mon < 11)
 278                                alarm->time.tm_mon++;
 279                        else {
 280                                alarm->time.tm_mon = 0;
 281                                alarm->time.tm_year++;
 282                        }
 283                        days = rtc_month_days(alarm->time.tm_mon,
 284                                        alarm->time.tm_year);
 285                } while (days < alarm->time.tm_mday);
 286                break;
 287
 288        /* Year rollover ... easy except for leap years! */
 289        case year:
 290                dev_dbg(&rtc->dev, "alarm rollover: %s\n", "year");
 291                do {
 292                        alarm->time.tm_year++;
 293                } while (rtc_valid_tm(&alarm->time) != 0);
 294                break;
 295
 296        default:
 297                dev_warn(&rtc->dev, "alarm rollover not handled\n");
 298        }
 299
 300done:
 301        return 0;
 302}
 303
 304int rtc_read_alarm(struct rtc_device *rtc, struct rtc_wkalrm *alarm)
 305{
 306        int err;
 307
 308        err = mutex_lock_interruptible(&rtc->ops_lock);
 309        if (err)
 310                return err;
 311        if (rtc->ops == NULL)
 312                err = -ENODEV;
 313        else if (!rtc->ops->read_alarm)
 314                err = -EINVAL;
 315        else {
 316                memset(alarm, 0, sizeof(struct rtc_wkalrm));
 317                alarm->enabled = rtc->aie_timer.enabled;
 318                alarm->time = rtc_ktime_to_tm(rtc->aie_timer.node.expires);
 319        }
 320        mutex_unlock(&rtc->ops_lock);
 321
 322        return err;
 323}
 324EXPORT_SYMBOL_GPL(rtc_read_alarm);
 325
 326static int __rtc_set_alarm(struct rtc_device *rtc, struct rtc_wkalrm *alarm)
 327{
 328        struct rtc_time tm;
 329        long now, scheduled;
 330        int err;
 331
 332        err = rtc_valid_tm(&alarm->time);
 333        if (err)
 334                return err;
 335        rtc_tm_to_time(&alarm->time, &scheduled);
 336
 337        /* Make sure we're not setting alarms in the past */
 338        err = __rtc_read_time(rtc, &tm);
 339        rtc_tm_to_time(&tm, &now);
 340        if (scheduled <= now)
 341                return -ETIME;
 342        /*
 343         * XXX - We just checked to make sure the alarm time is not
 344         * in the past, but there is still a race window where if
 345         * the is alarm set for the next second and the second ticks
 346         * over right here, before we set the alarm.
 347         */
 348
 349        if (!rtc->ops)
 350                err = -ENODEV;
 351        else if (!rtc->ops->set_alarm)
 352                err = -EINVAL;
 353        else
 354                err = rtc->ops->set_alarm(rtc->dev.parent, alarm);
 355
 356        return err;
 357}
 358
 359int rtc_set_alarm(struct rtc_device *rtc, struct rtc_wkalrm *alarm)
 360{
 361        int err;
 362
 363        err = rtc_valid_tm(&alarm->time);
 364        if (err != 0)
 365                return err;
 366
 367        err = mutex_lock_interruptible(&rtc->ops_lock);
 368        if (err)
 369                return err;
 370        if (rtc->aie_timer.enabled) {
 371                rtc_timer_remove(rtc, &rtc->aie_timer);
 372        }
 373        rtc->aie_timer.node.expires = rtc_tm_to_ktime(alarm->time);
 374        rtc->aie_timer.period = ktime_set(0, 0);
 375        if (alarm->enabled) {
 376                err = rtc_timer_enqueue(rtc, &rtc->aie_timer);
 377        }
 378        mutex_unlock(&rtc->ops_lock);
 379        return err;
 380}
 381EXPORT_SYMBOL_GPL(rtc_set_alarm);
 382
 383/* Called once per device from rtc_device_register */
 384int rtc_initialize_alarm(struct rtc_device *rtc, struct rtc_wkalrm *alarm)
 385{
 386        int err;
 387        struct rtc_time now;
 388
 389        err = rtc_valid_tm(&alarm->time);
 390        if (err != 0)
 391                return err;
 392
 393        err = rtc_read_time(rtc, &now);
 394        if (err)
 395                return err;
 396
 397        err = mutex_lock_interruptible(&rtc->ops_lock);
 398        if (err)
 399                return err;
 400
 401        rtc->aie_timer.node.expires = rtc_tm_to_ktime(alarm->time);
 402        rtc->aie_timer.period = ktime_set(0, 0);
 403
 404        /* Alarm has to be enabled & in the futrure for us to enqueue it */
 405        if (alarm->enabled && (rtc_tm_to_ktime(now).tv64 <
 406                         rtc->aie_timer.node.expires.tv64)) {
 407
 408                rtc->aie_timer.enabled = 1;
 409                timerqueue_add(&rtc->timerqueue, &rtc->aie_timer.node);
 410        }
 411        mutex_unlock(&rtc->ops_lock);
 412        return err;
 413}
 414EXPORT_SYMBOL_GPL(rtc_initialize_alarm);
 415
 416
 417
 418int rtc_alarm_irq_enable(struct rtc_device *rtc, unsigned int enabled)
 419{
 420        int err = mutex_lock_interruptible(&rtc->ops_lock);
 421        if (err)
 422                return err;
 423
 424        if (rtc->aie_timer.enabled != enabled) {
 425                if (enabled)
 426                        err = rtc_timer_enqueue(rtc, &rtc->aie_timer);
 427                else
 428                        rtc_timer_remove(rtc, &rtc->aie_timer);
 429        }
 430
 431        if (err)
 432                /* nothing */;
 433        else if (!rtc->ops)
 434                err = -ENODEV;
 435        else if (!rtc->ops->alarm_irq_enable)
 436                err = -EINVAL;
 437        else
 438                err = rtc->ops->alarm_irq_enable(rtc->dev.parent, enabled);
 439
 440        mutex_unlock(&rtc->ops_lock);
 441        return err;
 442}
 443EXPORT_SYMBOL_GPL(rtc_alarm_irq_enable);
 444
 445int rtc_update_irq_enable(struct rtc_device *rtc, unsigned int enabled)
 446{
 447        int err = mutex_lock_interruptible(&rtc->ops_lock);
 448        if (err)
 449                return err;
 450
 451#ifdef CONFIG_RTC_INTF_DEV_UIE_EMUL
 452        if (enabled == 0 && rtc->uie_irq_active) {
 453                mutex_unlock(&rtc->ops_lock);
 454                return rtc_dev_update_irq_enable_emul(rtc, 0);
 455        }
 456#endif
 457        /* make sure we're changing state */
 458        if (rtc->uie_rtctimer.enabled == enabled)
 459                goto out;
 460
 461        if (rtc->uie_unsupported) {
 462                err = -EINVAL;
 463                goto out;
 464        }
 465
 466        if (enabled) {
 467                struct rtc_time tm;
 468                ktime_t now, onesec;
 469
 470                __rtc_read_time(rtc, &tm);
 471                onesec = ktime_set(1, 0);
 472                now = rtc_tm_to_ktime(tm);
 473                rtc->uie_rtctimer.node.expires = ktime_add(now, onesec);
 474                rtc->uie_rtctimer.period = ktime_set(1, 0);
 475                err = rtc_timer_enqueue(rtc, &rtc->uie_rtctimer);
 476        } else
 477                rtc_timer_remove(rtc, &rtc->uie_rtctimer);
 478
 479out:
 480        mutex_unlock(&rtc->ops_lock);
 481#ifdef CONFIG_RTC_INTF_DEV_UIE_EMUL
 482        /*
 483         * Enable emulation if the driver did not provide
 484         * the update_irq_enable function pointer or if returned
 485         * -EINVAL to signal that it has been configured without
 486         * interrupts or that are not available at the moment.
 487         */
 488        if (err == -EINVAL)
 489                err = rtc_dev_update_irq_enable_emul(rtc, enabled);
 490#endif
 491        return err;
 492
 493}
 494EXPORT_SYMBOL_GPL(rtc_update_irq_enable);
 495
 496
 497/**
 498 * rtc_handle_legacy_irq - AIE, UIE and PIE event hook
 499 * @rtc: pointer to the rtc device
 500 *
 501 * This function is called when an AIE, UIE or PIE mode interrupt
 502 * has occurred (or been emulated).
 503 *
 504 * Triggers the registered irq_task function callback.
 505 */
 506void rtc_handle_legacy_irq(struct rtc_device *rtc, int num, int mode)
 507{
 508        unsigned long flags;
 509
 510        /* mark one irq of the appropriate mode */
 511        spin_lock_irqsave(&rtc->irq_lock, flags);
 512        rtc->irq_data = (rtc->irq_data + (num << 8)) | (RTC_IRQF|mode);
 513        spin_unlock_irqrestore(&rtc->irq_lock, flags);
 514
 515        /* call the task func */
 516        spin_lock_irqsave(&rtc->irq_task_lock, flags);
 517        if (rtc->irq_task)
 518                rtc->irq_task->func(rtc->irq_task->private_data);
 519        spin_unlock_irqrestore(&rtc->irq_task_lock, flags);
 520
 521        wake_up_interruptible(&rtc->irq_queue);
 522        kill_fasync(&rtc->async_queue, SIGIO, POLL_IN);
 523}
 524
 525
 526/**
 527 * rtc_aie_update_irq - AIE mode rtctimer hook
 528 * @private: pointer to the rtc_device
 529 *
 530 * This functions is called when the aie_timer expires.
 531 */
 532void rtc_aie_update_irq(void *private)
 533{
 534        struct rtc_device *rtc = (struct rtc_device *)private;
 535        rtc_handle_legacy_irq(rtc, 1, RTC_AF);
 536}
 537
 538
 539/**
 540 * rtc_uie_update_irq - UIE mode rtctimer hook
 541 * @private: pointer to the rtc_device
 542 *
 543 * This functions is called when the uie_timer expires.
 544 */
 545void rtc_uie_update_irq(void *private)
 546{
 547        struct rtc_device *rtc = (struct rtc_device *)private;
 548        rtc_handle_legacy_irq(rtc, 1,  RTC_UF);
 549}
 550
 551
 552/**
 553 * rtc_pie_update_irq - PIE mode hrtimer hook
 554 * @timer: pointer to the pie mode hrtimer
 555 *
 556 * This function is used to emulate PIE mode interrupts
 557 * using an hrtimer. This function is called when the periodic
 558 * hrtimer expires.
 559 */
 560enum hrtimer_restart rtc_pie_update_irq(struct hrtimer *timer)
 561{
 562        struct rtc_device *rtc;
 563        ktime_t period;
 564        int count;
 565        rtc = container_of(timer, struct rtc_device, pie_timer);
 566
 567        period = ktime_set(0, NSEC_PER_SEC/rtc->irq_freq);
 568        count = hrtimer_forward_now(timer, period);
 569
 570        rtc_handle_legacy_irq(rtc, count, RTC_PF);
 571
 572        return HRTIMER_RESTART;
 573}
 574
 575/**
 576 * rtc_update_irq - Triggered when a RTC interrupt occurs.
 577 * @rtc: the rtc device
 578 * @num: how many irqs are being reported (usually one)
 579 * @events: mask of RTC_IRQF with one or more of RTC_PF, RTC_AF, RTC_UF
 580 * Context: any
 581 */
 582void rtc_update_irq(struct rtc_device *rtc,
 583                unsigned long num, unsigned long events)
 584{
 585        pm_stay_awake(rtc->dev.parent);
 586        schedule_work(&rtc->irqwork);
 587}
 588EXPORT_SYMBOL_GPL(rtc_update_irq);
 589
 590static int __rtc_match(struct device *dev, void *data)
 591{
 592        char *name = (char *)data;
 593
 594        if (strcmp(dev_name(dev), name) == 0)
 595                return 1;
 596        return 0;
 597}
 598
 599struct rtc_device *rtc_class_open(char *name)
 600{
 601        struct device *dev;
 602        struct rtc_device *rtc = NULL;
 603
 604        dev = class_find_device(rtc_class, NULL, name, __rtc_match);
 605        if (dev)
 606                rtc = to_rtc_device(dev);
 607
 608        if (rtc) {
 609                if (!try_module_get(rtc->owner)) {
 610                        put_device(dev);
 611                        rtc = NULL;
 612                }
 613        }
 614
 615        return rtc;
 616}
 617EXPORT_SYMBOL_GPL(rtc_class_open);
 618
 619void rtc_class_close(struct rtc_device *rtc)
 620{
 621        module_put(rtc->owner);
 622        put_device(&rtc->dev);
 623}
 624EXPORT_SYMBOL_GPL(rtc_class_close);
 625
 626int rtc_irq_register(struct rtc_device *rtc, struct rtc_task *task)
 627{
 628        int retval = -EBUSY;
 629
 630        if (task == NULL || task->func == NULL)
 631                return -EINVAL;
 632
 633        /* Cannot register while the char dev is in use */
 634        if (test_and_set_bit_lock(RTC_DEV_BUSY, &rtc->flags))
 635                return -EBUSY;
 636
 637        spin_lock_irq(&rtc->irq_task_lock);
 638        if (rtc->irq_task == NULL) {
 639                rtc->irq_task = task;
 640                retval = 0;
 641        }
 642        spin_unlock_irq(&rtc->irq_task_lock);
 643
 644        clear_bit_unlock(RTC_DEV_BUSY, &rtc->flags);
 645
 646        return retval;
 647}
 648EXPORT_SYMBOL_GPL(rtc_irq_register);
 649
 650void rtc_irq_unregister(struct rtc_device *rtc, struct rtc_task *task)
 651{
 652        spin_lock_irq(&rtc->irq_task_lock);
 653        if (rtc->irq_task == task)
 654                rtc->irq_task = NULL;
 655        spin_unlock_irq(&rtc->irq_task_lock);
 656}
 657EXPORT_SYMBOL_GPL(rtc_irq_unregister);
 658
 659static int rtc_update_hrtimer(struct rtc_device *rtc, int enabled)
 660{
 661        /*
 662         * We always cancel the timer here first, because otherwise
 663         * we could run into BUG_ON(timer->state != HRTIMER_STATE_CALLBACK);
 664         * when we manage to start the timer before the callback
 665         * returns HRTIMER_RESTART.
 666         *
 667         * We cannot use hrtimer_cancel() here as a running callback
 668         * could be blocked on rtc->irq_task_lock and hrtimer_cancel()
 669         * would spin forever.
 670         */
 671        if (hrtimer_try_to_cancel(&rtc->pie_timer) < 0)
 672                return -1;
 673
 674        if (enabled) {
 675                ktime_t period = ktime_set(0, NSEC_PER_SEC / rtc->irq_freq);
 676
 677                hrtimer_start(&rtc->pie_timer, period, HRTIMER_MODE_REL);
 678        }
 679        return 0;
 680}
 681
 682/**
 683 * rtc_irq_set_state - enable/disable 2^N Hz periodic IRQs
 684 * @rtc: the rtc device
 685 * @task: currently registered with rtc_irq_register()
 686 * @enabled: true to enable periodic IRQs
 687 * Context: any
 688 *
 689 * Note that rtc_irq_set_freq() should previously have been used to
 690 * specify the desired frequency of periodic IRQ task->func() callbacks.
 691 */
 692int rtc_irq_set_state(struct rtc_device *rtc, struct rtc_task *task, int enabled)
 693{
 694        int err = 0;
 695        unsigned long flags;
 696
 697retry:
 698        spin_lock_irqsave(&rtc->irq_task_lock, flags);
 699        if (rtc->irq_task != NULL && task == NULL)
 700                err = -EBUSY;
 701        if (rtc->irq_task != task)
 702                err = -EACCES;
 703        if (!err) {
 704                if (rtc_update_hrtimer(rtc, enabled) < 0) {
 705                        spin_unlock_irqrestore(&rtc->irq_task_lock, flags);
 706                        cpu_relax();
 707                        goto retry;
 708                }
 709                rtc->pie_enabled = enabled;
 710        }
 711        spin_unlock_irqrestore(&rtc->irq_task_lock, flags);
 712        return err;
 713}
 714EXPORT_SYMBOL_GPL(rtc_irq_set_state);
 715
 716/**
 717 * rtc_irq_set_freq - set 2^N Hz periodic IRQ frequency for IRQ
 718 * @rtc: the rtc device
 719 * @task: currently registered with rtc_irq_register()
 720 * @freq: positive frequency with which task->func() will be called
 721 * Context: any
 722 *
 723 * Note that rtc_irq_set_state() is used to enable or disable the
 724 * periodic IRQs.
 725 */
 726int rtc_irq_set_freq(struct rtc_device *rtc, struct rtc_task *task, int freq)
 727{
 728        int err = 0;
 729        unsigned long flags;
 730
 731        if (freq <= 0 || freq > RTC_MAX_FREQ)
 732                return -EINVAL;
 733retry:
 734        spin_lock_irqsave(&rtc->irq_task_lock, flags);
 735        if (rtc->irq_task != NULL && task == NULL)
 736                err = -EBUSY;
 737        if (rtc->irq_task != task)
 738                err = -EACCES;
 739        if (!err) {
 740                rtc->irq_freq = freq;
 741                if (rtc->pie_enabled && rtc_update_hrtimer(rtc, 1) < 0) {
 742                        spin_unlock_irqrestore(&rtc->irq_task_lock, flags);
 743                        cpu_relax();
 744                        goto retry;
 745                }
 746        }
 747        spin_unlock_irqrestore(&rtc->irq_task_lock, flags);
 748        return err;
 749}
 750EXPORT_SYMBOL_GPL(rtc_irq_set_freq);
 751
 752/**
 753 * rtc_timer_enqueue - Adds a rtc_timer to the rtc_device timerqueue
 754 * @rtc rtc device
 755 * @timer timer being added.
 756 *
 757 * Enqueues a timer onto the rtc devices timerqueue and sets
 758 * the next alarm event appropriately.
 759 *
 760 * Sets the enabled bit on the added timer.
 761 *
 762 * Must hold ops_lock for proper serialization of timerqueue
 763 */
 764static int rtc_timer_enqueue(struct rtc_device *rtc, struct rtc_timer *timer)
 765{
 766        timer->enabled = 1;
 767        timerqueue_add(&rtc->timerqueue, &timer->node);
 768        if (&timer->node == timerqueue_getnext(&rtc->timerqueue)) {
 769                struct rtc_wkalrm alarm;
 770                int err;
 771                alarm.time = rtc_ktime_to_tm(timer->node.expires);
 772                alarm.enabled = 1;
 773                err = __rtc_set_alarm(rtc, &alarm);
 774                if (err == -ETIME)
 775                        schedule_work(&rtc->irqwork);
 776                else if (err) {
 777                        timerqueue_del(&rtc->timerqueue, &timer->node);
 778                        timer->enabled = 0;
 779                        return err;
 780                }
 781        }
 782        return 0;
 783}
 784
 785static void rtc_alarm_disable(struct rtc_device *rtc)
 786{
 787        if (!rtc->ops || !rtc->ops->alarm_irq_enable)
 788                return;
 789
 790        rtc->ops->alarm_irq_enable(rtc->dev.parent, false);
 791}
 792
 793/**
 794 * rtc_timer_remove - Removes a rtc_timer from the rtc_device timerqueue
 795 * @rtc rtc device
 796 * @timer timer being removed.
 797 *
 798 * Removes a timer onto the rtc devices timerqueue and sets
 799 * the next alarm event appropriately.
 800 *
 801 * Clears the enabled bit on the removed timer.
 802 *
 803 * Must hold ops_lock for proper serialization of timerqueue
 804 */
 805static void rtc_timer_remove(struct rtc_device *rtc, struct rtc_timer *timer)
 806{
 807        struct timerqueue_node *next = timerqueue_getnext(&rtc->timerqueue);
 808        timerqueue_del(&rtc->timerqueue, &timer->node);
 809        timer->enabled = 0;
 810        if (next == &timer->node) {
 811                struct rtc_wkalrm alarm;
 812                int err;
 813                next = timerqueue_getnext(&rtc->timerqueue);
 814                if (!next) {
 815                        rtc_alarm_disable(rtc);
 816                        return;
 817                }
 818                alarm.time = rtc_ktime_to_tm(next->expires);
 819                alarm.enabled = 1;
 820                err = __rtc_set_alarm(rtc, &alarm);
 821                if (err == -ETIME)
 822                        schedule_work(&rtc->irqwork);
 823        }
 824}
 825
 826/**
 827 * rtc_timer_do_work - Expires rtc timers
 828 * @rtc rtc device
 829 * @timer timer being removed.
 830 *
 831 * Expires rtc timers. Reprograms next alarm event if needed.
 832 * Called via worktask.
 833 *
 834 * Serializes access to timerqueue via ops_lock mutex
 835 */
 836void rtc_timer_do_work(struct work_struct *work)
 837{
 838        struct rtc_timer *timer;
 839        struct timerqueue_node *next;
 840        ktime_t now;
 841        struct rtc_time tm;
 842
 843        struct rtc_device *rtc =
 844                container_of(work, struct rtc_device, irqwork);
 845
 846        mutex_lock(&rtc->ops_lock);
 847again:
 848        pm_relax(rtc->dev.parent);
 849        __rtc_read_time(rtc, &tm);
 850        now = rtc_tm_to_ktime(tm);
 851        while ((next = timerqueue_getnext(&rtc->timerqueue))) {
 852                if (next->expires.tv64 > now.tv64)
 853                        break;
 854
 855                /* expire timer */
 856                timer = container_of(next, struct rtc_timer, node);
 857                timerqueue_del(&rtc->timerqueue, &timer->node);
 858                timer->enabled = 0;
 859                if (timer->task.func)
 860                        timer->task.func(timer->task.private_data);
 861
 862                /* Re-add/fwd periodic timers */
 863                if (ktime_to_ns(timer->period)) {
 864                        timer->node.expires = ktime_add(timer->node.expires,
 865                                                        timer->period);
 866                        timer->enabled = 1;
 867                        timerqueue_add(&rtc->timerqueue, &timer->node);
 868                }
 869        }
 870
 871        /* Set next alarm */
 872        if (next) {
 873                struct rtc_wkalrm alarm;
 874                int err;
 875                alarm.time = rtc_ktime_to_tm(next->expires);
 876                alarm.enabled = 1;
 877                err = __rtc_set_alarm(rtc, &alarm);
 878                if (err == -ETIME)
 879                        goto again;
 880        } else
 881                rtc_alarm_disable(rtc);
 882
 883        mutex_unlock(&rtc->ops_lock);
 884}
 885
 886
 887/* rtc_timer_init - Initializes an rtc_timer
 888 * @timer: timer to be intiialized
 889 * @f: function pointer to be called when timer fires
 890 * @data: private data passed to function pointer
 891 *
 892 * Kernel interface to initializing an rtc_timer.
 893 */
 894void rtc_timer_init(struct rtc_timer *timer, void (*f)(void* p), void* data)
 895{
 896        timerqueue_init(&timer->node);
 897        timer->enabled = 0;
 898        timer->task.func = f;
 899        timer->task.private_data = data;
 900}
 901
 902/* rtc_timer_start - Sets an rtc_timer to fire in the future
 903 * @ rtc: rtc device to be used
 904 * @ timer: timer being set
 905 * @ expires: time at which to expire the timer
 906 * @ period: period that the timer will recur
 907 *
 908 * Kernel interface to set an rtc_timer
 909 */
 910int rtc_timer_start(struct rtc_device *rtc, struct rtc_timer* timer,
 911                        ktime_t expires, ktime_t period)
 912{
 913        int ret = 0;
 914        mutex_lock(&rtc->ops_lock);
 915        if (timer->enabled)
 916                rtc_timer_remove(rtc, timer);
 917
 918        timer->node.expires = expires;
 919        timer->period = period;
 920
 921        ret = rtc_timer_enqueue(rtc, timer);
 922
 923        mutex_unlock(&rtc->ops_lock);
 924        return ret;
 925}
 926
 927/* rtc_timer_cancel - Stops an rtc_timer
 928 * @ rtc: rtc device to be used
 929 * @ timer: timer being set
 930 *
 931 * Kernel interface to cancel an rtc_timer
 932 */
 933int rtc_timer_cancel(struct rtc_device *rtc, struct rtc_timer* timer)
 934{
 935        int ret = 0;
 936        mutex_lock(&rtc->ops_lock);
 937        if (timer->enabled)
 938                rtc_timer_remove(rtc, timer);
 939        mutex_unlock(&rtc->ops_lock);
 940        return ret;
 941}
 942
 943
 944
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