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