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/log2.h>
  16
  17 int rtc_read_time(struct rtc_device *rtc, struct rtc_time *tm)
  18 {
  19         int err;
  20
  21         err = mutex_lock_interruptible(&rtc->ops_lock);
  22         if (err)
  23                 return err;
  24
  25         if (!rtc->ops)
  26                 err = -ENODEV;
  27         else if (!rtc->ops->read_time)
  28                 err = -EINVAL;
  29         else {
  30                 memset(tm, 0, sizeof(struct rtc_time));
  31                 err = rtc->ops->read_time(rtc->dev.parent, tm);
  32         }
  33
  34         mutex_unlock(&rtc->ops_lock);
  35         return err;
  36 }
  37 EXPORT_SYMBOL_GPL(rtc_read_time);
  38
  39 int rtc_set_time(struct rtc_device *rtc, struct rtc_time *tm)
  40 {
  41         int err;
  42
  43         err = rtc_valid_tm(tm);
  44         if (err != 0)
  45                 return err;
  46
  47         err = mutex_lock_interruptible(&rtc->ops_lock);
  48         if (err)
  49                 return err;
  50
  51         if (!rtc->ops)
  52                 err = -ENODEV;
  53         else if (rtc->ops->set_time)
  54                 err = rtc->ops->set_time(rtc->dev.parent, tm);
  55         else if (rtc->ops->set_mmss) {
  56                 unsigned long secs;
  57                 err = rtc_tm_to_time(tm, &secs);
  58                 if (err == 0)
  59                         err = rtc->ops->set_mmss(rtc->dev.parent, secs);
  60         } else
  61                 err = -EINVAL;
  62
  63         mutex_unlock(&rtc->ops_lock);
  64         return err;
  65 }
  66 EXPORT_SYMBOL_GPL(rtc_set_time);
  67
  68 int rtc_set_mmss(struct rtc_device *rtc, unsigned long secs)
  69 {
  70         int err;
  71
  72         err = mutex_lock_interruptible(&rtc->ops_lock);
  73         if (err)
  74                 return err;
  75
  76         if (!rtc->ops)
  77                 err = -ENODEV;
  78         else if (rtc->ops->set_mmss)
  79                 err = rtc->ops->set_mmss(rtc->dev.parent, secs);
  80         else if (rtc->ops->read_time && rtc->ops->set_time) {
  81                 struct rtc_time new, old;
  82
  83                 err = rtc->ops->read_time(rtc->dev.parent, &old);
  84                 if (err == 0) {
  85                         rtc_time_to_tm(secs, &new);
  86
  87                         /*
  88                          * avoid writing when we're going to change the day of
  89                          * the month. We will retry in the next minute. This
  90                          * basically means that if the RTC must not drift
  91                          * by more than 1 minute in 11 minutes.
  92                          */
  93                         if (!((old.tm_hour == 23 && old.tm_min == 59) ||
  94                                 (new.tm_hour == 23 && new.tm_min == 59)))
  95                                 err = rtc->ops->set_time(rtc->dev.parent,
  96                                                 &new);
  97                 }
  98         }
  99         else
 100                 err = -EINVAL;
 101
 102         mutex_unlock(&rtc->ops_lock);
 103
 104         return err;
 105 }
 106 EXPORT_SYMBOL_GPL(rtc_set_mmss);
 107
 108 static int rtc_read_alarm_internal(struct rtc_device *rtc, struct rtc_wkalrm *alarm)
 109 {
 110         int err;
 111
 112         err = mutex_lock_interruptible(&rtc->ops_lock);
 113         if (err)
 114                 return err;
 115
 116         if (rtc->ops == NULL)
 117                 err = -ENODEV;
 118         else if (!rtc->ops->read_alarm)
 119                 err = -EINVAL;
 120         else {
 121                 memset(alarm, 0, sizeof(struct rtc_wkalrm));
 122                 err = rtc->ops->read_alarm(rtc->dev.parent, alarm);
 123         }
 124
 125         mutex_unlock(&rtc->ops_lock);
 126         return err;
 127 }
 128
 129 int rtc_read_alarm(struct rtc_device *rtc, struct rtc_wkalrm *alarm)
 130 {
 131         int err;
 132         struct rtc_time before, now;
 133         int first_time = 1;
 134         unsigned long t_now, t_alm;
 135         enum { none, day, month, year } missing = none;
 136         unsigned days;
 137
 138         /* The lower level RTC driver may return -1 in some fields,
 139          * creating invalid alarm->time values, for reasons like:
 140          *
 141          *   - The hardware may not be capable of filling them in;
 142          *     many alarms match only on time-of-day fields, not
 143          *     day/month/year calendar data.
 144          *
 145          *   - Some hardware uses illegal values as "wildcard" match
 146          *     values, which non-Linux firmware (like a BIOS) may try
 147          *     to set up as e.g. "alarm 15 minutes after each hour".
 148          *     Linux uses only oneshot alarms.
 149          *
 150          * When we see that here, we deal with it by using values from
 151          * a current RTC timestamp for any missing (-1) values.  The
 152          * RTC driver prevents "periodic alarm" modes.
 153          *
 154          * But this can be racey, because some fields of the RTC timestamp
 155          * may have wrapped in the interval since we read the RTC alarm,
 156          * which would lead to us inserting inconsistent values in place
 157          * of the -1 fields.
 158          *
 159          * Reading the alarm and timestamp in the reverse sequence
 160          * would have the same race condition, and not solve the issue.
 161          *
 162          * So, we must first read the RTC timestamp,
 163          * then read the RTC alarm value,
 164          * and then read a second RTC timestamp.
 165          *
 166          * If any fields of the second timestamp have changed
 167          * when compared with the first timestamp, then we know
 168          * our timestamp may be inconsistent with that used by
 169          * the low-level rtc_read_alarm_internal() function.
 170          *
 171          * So, when the two timestamps disagree, we just loop and do
 172          * the process again to get a fully consistent set of values.
 173          *
 174          * This could all instead be done in the lower level driver,
 175          * but since more than one lower level RTC implementation needs it,
 176          * then it's probably best best to do it here instead of there..
 177          */
 178
 179         /* Get the "before" timestamp */
 180         err = rtc_read_time(rtc, &before);
 181         if (err < 0)
 182                 return err;
 183         do {
 184                 if (!first_time)
 185                         memcpy(&before, &now, sizeof(struct rtc_time));
 186                 first_time = 0;
 187
 188                 /* get the RTC alarm values, which may be incomplete */
 189                 err = rtc_read_alarm_internal(rtc, alarm);
 190                 if (err)
 191                         return err;
 192                 if (!alarm->enabled)
 193                         return 0;
 194
 195                 /* full-function RTCs won't have such missing fields */
 196                 if (rtc_valid_tm(&alarm->time) == 0)
 197                         return 0;
 198
 199                 /* get the "after" timestamp, to detect wrapped fields */
 200                 err = rtc_read_time(rtc, &now);
 201                 if (err < 0)
 202                         return err;
 203
 204                 /* note that tm_sec is a "don't care" value here: */
 205         } while (   before.tm_min   != now.tm_min
 206                  || before.tm_hour  != now.tm_hour
 207                  || before.tm_mon   != now.tm_mon
 208                  || before.tm_year  != now.tm_year);
 209
 210         /* Fill in the missing alarm fields using the timestamp; we
 211          * know there's at least one since alarm->time is invalid.
 212          */
 213         if (alarm->time.tm_sec == -1)
 214                 alarm->time.tm_sec = now.tm_sec;
 215         if (alarm->time.tm_min == -1)
 216                 alarm->time.tm_min = now.tm_min;
 217         if (alarm->time.tm_hour == -1)
 218                 alarm->time.tm_hour = now.tm_hour;
 219
 220         /* For simplicity, only support date rollover for now */
 221         if (alarm->time.tm_mday == -1) {
 222                 alarm->time.tm_mday = now.tm_mday;
 223                 missing = day;
 224         }
 225         if (alarm->time.tm_mon == -1) {
 226                 alarm->time.tm_mon = now.tm_mon;
 227                 if (missing == none)
 228                         missing = month;
 229         }
 230         if (alarm->time.tm_year == -1) {
 231                 alarm->time.tm_year = now.tm_year;
 232                 if (missing == none)
 233                         missing = year;
 234         }
 235
 236         /* with luck, no rollover is needed */
 237         rtc_tm_to_time(&now, &t_now);
 238         rtc_tm_to_time(&alarm->time, &t_alm);
 239         if (t_now < t_alm)
 240                 goto done;
 241
 242         switch (missing) {
 243
 244         /* 24 hour rollover ... if it's now 10am Monday, an alarm that
 245          * that will trigger at 5am will do so at 5am Tuesday, which
 246          * could also be in the next month or year.  This is a common
 247          * case, especially for PCs.
 248          */
 249         case day:
 250                 dev_dbg(&rtc->dev, "alarm rollover: %s\n", "day");
 251                 t_alm += 24 * 60 * 60;
 252                 rtc_time_to_tm(t_alm, &alarm->time);
 253                 break;
 254
 255         /* Month rollover ... if it's the 31th, an alarm on the 3rd will
 256          * be next month.  An alarm matching on the 30th, 29th, or 28th
 257          * may end up in the month after that!  Many newer PCs support
 258          * this type of alarm.
 259          */
 260         case month:
 261                 dev_dbg(&rtc->dev, "alarm rollover: %s\n", "month");
 262                 do {
 263                         if (alarm->time.tm_mon < 11)
 264                                 alarm->time.tm_mon++;
 265                         else {
 266                                 alarm->time.tm_mon = 0;
 267                                 alarm->time.tm_year++;
 268                         }
 269                         days = rtc_month_days(alarm->time.tm_mon,
 270                                         alarm->time.tm_year);
 271                 } while (days < alarm->time.tm_mday);
 272                 break;
 273
 274         /* Year rollover ... easy except for leap years! */
 275         case year:
 276                 dev_dbg(&rtc->dev, "alarm rollover: %s\n", "year");
 277                 do {
 278                         alarm->time.tm_year++;
 279                 } while (rtc_valid_tm(&alarm->time) != 0);
 280                 break;
 281
 282         default:
 283                 dev_warn(&rtc->dev, "alarm rollover not handled\n");
 284         }
 285
 286 done:
 287         return 0;
 288 }
 289 EXPORT_SYMBOL_GPL(rtc_read_alarm);
 290
 291 int rtc_set_alarm(struct rtc_device *rtc, struct rtc_wkalrm *alarm)
 292 {
 293         int err;
 294
 295         err = rtc_valid_tm(&alarm->time);
 296         if (err != 0)
 297                 return err;
 298
 299         err = mutex_lock_interruptible(&rtc->ops_lock);
 300         if (err)
 301                 return err;
 302
 303         if (!rtc->ops)
 304                 err = -ENODEV;
 305         else if (!rtc->ops->set_alarm)
 306                 err = -EINVAL;
 307         else
 308                 err = rtc->ops->set_alarm(rtc->dev.parent, alarm);
 309
 310         mutex_unlock(&rtc->ops_lock);
 311         return err;
 312 }
 313 EXPORT_SYMBOL_GPL(rtc_set_alarm);
 314
 315 int rtc_alarm_irq_enable(struct rtc_device *rtc, unsigned int enabled)
 316 {
 317         int err = mutex_lock_interruptible(&rtc->ops_lock);
 318         if (err)
 319                 return err;
 320
 321         if (!rtc->ops)
 322                 err = -ENODEV;
 323         else if (!rtc->ops->alarm_irq_enable)
 324                 err = -EINVAL;
 325         else
 326                 err = rtc->ops->alarm_irq_enable(rtc->dev.parent, enabled);
 327
 328         mutex_unlock(&rtc->ops_lock);
 329         return err;
 330 }
 331 EXPORT_SYMBOL_GPL(rtc_alarm_irq_enable);
 332
 333 int rtc_update_irq_enable(struct rtc_device *rtc, unsigned int enabled)
 334 {
 335         int err = mutex_lock_interruptible(&rtc->ops_lock);
 336         if (err)
 337                 return err;
 338
 339 #ifdef CONFIG_RTC_INTF_DEV_UIE_EMUL
 340         if (enabled == 0 && rtc->uie_irq_active) {
 341                 mutex_unlock(&rtc->ops_lock);
 342                 return rtc_dev_update_irq_enable_emul(rtc, enabled);
 343         }
 344 #endif
 345
 346         if (!rtc->ops)
 347                 err = -ENODEV;
 348         else if (!rtc->ops->update_irq_enable)
 349                 err = -EINVAL;
 350         else
 351                 err = rtc->ops->update_irq_enable(rtc->dev.parent, enabled);
 352
 353         mutex_unlock(&rtc->ops_lock);
 354
 355 #ifdef CONFIG_RTC_INTF_DEV_UIE_EMUL
 356         /*
 357          * Enable emulation if the driver did not provide
 358          * the update_irq_enable function pointer or if returned
 359          * -EINVAL to signal that it has been configured without
 360          * interrupts or that are not available at the moment.
 361          */
 362         if (err == -EINVAL)
 363                 err = rtc_dev_update_irq_enable_emul(rtc, enabled);
 364 #endif
 365         return err;
 366 }
 367 EXPORT_SYMBOL_GPL(rtc_update_irq_enable);
 368
 369 /**
 370  * rtc_update_irq - report RTC periodic, alarm, and/or update irqs
 371  * @rtc: the rtc device
 372  * @num: how many irqs are being reported (usually one)
 373  * @events: mask of RTC_IRQF with one or more of RTC_PF, RTC_AF, RTC_UF
 374  * Context: any
 375  */
 376 void rtc_update_irq(struct rtc_device *rtc,
 377                 unsigned long num, unsigned long events)
 378 {
 379         unsigned long flags;
 380
 381         spin_lock_irqsave(&rtc->irq_lock, flags);
 382         rtc->irq_data = (rtc->irq_data + (num << 8)) | events;
 383         spin_unlock_irqrestore(&rtc->irq_lock, flags);
 384
 385         spin_lock_irqsave(&rtc->irq_task_lock, flags);
 386         if (rtc->irq_task)
 387                 rtc->irq_task->func(rtc->irq_task->private_data);
 388         spin_unlock_irqrestore(&rtc->irq_task_lock, flags);
 389
 390         wake_up_interruptible(&rtc->irq_queue);
 391         kill_fasync(&rtc->async_queue, SIGIO, POLL_IN);
 392 }
 393 EXPORT_SYMBOL_GPL(rtc_update_irq);
 394
 395 static int __rtc_match(struct device *dev, void *data)
 396 {
 397         char *name = (char *)data;
 398
 399         if (strcmp(dev_name(dev), name) == 0)
 400                 return 1;
 401         return 0;
 402 }
 403
 404 struct rtc_device *rtc_class_open(char *name)
 405 {
 406         struct device *dev;
 407         struct rtc_device *rtc = NULL;
 408
 409         dev = class_find_device(rtc_class, NULL, name, __rtc_match);
 410         if (dev)
 411                 rtc = to_rtc_device(dev);
 412
 413         if (rtc) {
 414                 if (!try_module_get(rtc->owner)) {
 415                         put_device(dev);
 416                         rtc = NULL;
 417                 }
 418         }
 419
 420         return rtc;
 421 }
 422 EXPORT_SYMBOL_GPL(rtc_class_open);
 423
 424 void rtc_class_close(struct rtc_device *rtc)
 425 {
 426         module_put(rtc->owner);
 427         put_device(&rtc->dev);
 428 }
 429 EXPORT_SYMBOL_GPL(rtc_class_close);
 430
 431 int rtc_irq_register(struct rtc_device *rtc, struct rtc_task *task)
 432 {
 433         int retval = -EBUSY;
 434
 435         if (task == NULL || task->func == NULL)
 436                 return -EINVAL;
 437
 438         /* Cannot register while the char dev is in use */
 439         if (test_and_set_bit_lock(RTC_DEV_BUSY, &rtc->flags))
 440                 return -EBUSY;
 441
 442         spin_lock_irq(&rtc->irq_task_lock);
 443         if (rtc->irq_task == NULL) {
 444                 rtc->irq_task = task;
 445                 retval = 0;
 446         }
 447         spin_unlock_irq(&rtc->irq_task_lock);
 448
 449         clear_bit_unlock(RTC_DEV_BUSY, &rtc->flags);
 450
 451         return retval;
 452 }
 453 EXPORT_SYMBOL_GPL(rtc_irq_register);
 454
 455 void rtc_irq_unregister(struct rtc_device *rtc, struct rtc_task *task)
 456 {
 457         spin_lock_irq(&rtc->irq_task_lock);
 458         if (rtc->irq_task == task)
 459                 rtc->irq_task = NULL;
 460         spin_unlock_irq(&rtc->irq_task_lock);
 461 }
 462 EXPORT_SYMBOL_GPL(rtc_irq_unregister);
 463
 464 /**
 465  * rtc_irq_set_state - enable/disable 2^N Hz periodic IRQs
 466  * @rtc: the rtc device
 467  * @task: currently registered with rtc_irq_register()
 468  * @enabled: true to enable periodic IRQs
 469  * Context: any
 470  *
 471  * Note that rtc_irq_set_freq() should previously have been used to
 472  * specify the desired frequency of periodic IRQ task->func() callbacks.
 473  */
 474 int rtc_irq_set_state(struct rtc_device *rtc, struct rtc_task *task, int enabled)
 475 {
 476         int err = 0;
 477         unsigned long flags;
 478
 479         if (rtc->ops->irq_set_state == NULL)
 480                 return -ENXIO;
 481
 482         spin_lock_irqsave(&rtc->irq_task_lock, flags);
 483         if (rtc->irq_task != NULL && task == NULL)
 484                 err = -EBUSY;
 485         if (rtc->irq_task != task)
 486                 err = -EACCES;
 487         spin_unlock_irqrestore(&rtc->irq_task_lock, flags);
 488
 489         if (err == 0)
 490                 err = rtc->ops->irq_set_state(rtc->dev.parent, enabled);
 491
 492         return err;
 493 }
 494 EXPORT_SYMBOL_GPL(rtc_irq_set_state);
 495
 496 /**
 497  * rtc_irq_set_freq - set 2^N Hz periodic IRQ frequency for IRQ
 498  * @rtc: the rtc device
 499  * @task: currently registered with rtc_irq_register()
 500  * @freq: positive frequency with which task->func() will be called
 501  * Context: any
 502  *
 503  * Note that rtc_irq_set_state() is used to enable or disable the
 504  * periodic IRQs.
 505  */
 506 int rtc_irq_set_freq(struct rtc_device *rtc, struct rtc_task *task, int freq)
 507 {
 508         int err = 0;
 509         unsigned long flags;
 510
 511         if (rtc->ops->irq_set_freq == NULL)
 512                 return -ENXIO;
 513
 514         spin_lock_irqsave(&rtc->irq_task_lock, flags);
 515         if (rtc->irq_task != NULL && task == NULL)
 516                 err = -EBUSY;
 517         if (rtc->irq_task != task)
 518                 err = -EACCES;
 519         spin_unlock_irqrestore(&rtc->irq_task_lock, flags);
 520
 521         if (err == 0) {
 522                 err = rtc->ops->irq_set_freq(rtc->dev.parent, freq);
 523                 if (err == 0)
 524                         rtc->irq_freq = freq;
 525         }
 526         return err;
 527 }
 528 EXPORT_SYMBOL_GPL(rtc_irq_set_freq);