drivers/rtc/rtc-dev.c

   1 /*
   2  * RTC subsystem, dev interface
   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/module.h>
  15 #include <linux/rtc.h>
  16 #include "rtc-core.h"
  17
  18 static dev_t rtc_devt;
  19
  20 #define RTC_DEV_MAX 16 /* 16 RTCs should be enough for everyone... */
  21
  22 static int rtc_dev_open(struct inode *inode, struct file *file)
  23 {
  24         int err;
  25         struct rtc_device *rtc = container_of(inode->i_cdev,
  26                                         struct rtc_device, char_dev);
  27         const struct rtc_class_ops *ops = rtc->ops;
  28
  29         if (test_and_set_bit_lock(RTC_DEV_BUSY, &rtc->flags))
  30                 return -EBUSY;
  31
  32         file->private_data = rtc;
  33
  34         err = ops->open ? ops->open(rtc->dev.parent) : 0;
  35         if (err == 0) {
  36                 spin_lock_irq(&rtc->irq_lock);
  37                 rtc->irq_data = 0;
  38                 spin_unlock_irq(&rtc->irq_lock);
  39
  40                 return 0;
  41         }
  42
  43         /* something has gone wrong */
  44         clear_bit_unlock(RTC_DEV_BUSY, &rtc->flags);
  45         return err;
  46 }
  47
  48 #ifdef CONFIG_RTC_INTF_DEV_UIE_EMUL
  49 /*
  50  * Routine to poll RTC seconds field for change as often as possible,
  51  * after first RTC_UIE use timer to reduce polling
  52  */
  53 static void rtc_uie_task(struct work_struct *work)
  54 {
  55         struct rtc_device *rtc =
  56                 container_of(work, struct rtc_device, uie_task);
  57         struct rtc_time tm;
  58         int num = 0;
  59         int err;
  60
  61         err = rtc_read_time(rtc, &tm);
  62
  63         spin_lock_irq(&rtc->irq_lock);
  64         if (rtc->stop_uie_polling || err) {
  65                 rtc->uie_task_active = 0;
  66         } else if (rtc->oldsecs != tm.tm_sec) {
  67                 num = (tm.tm_sec + 60 - rtc->oldsecs) % 60;
  68                 rtc->oldsecs = tm.tm_sec;
  69                 rtc->uie_timer.expires = jiffies + HZ - (HZ/10);
  70                 rtc->uie_timer_active = 1;
  71                 rtc->uie_task_active = 0;
  72                 add_timer(&rtc->uie_timer);
  73         } else if (schedule_work(&rtc->uie_task) == 0) {
  74                 rtc->uie_task_active = 0;
  75         }
  76         spin_unlock_irq(&rtc->irq_lock);
  77         if (num)
  78                 rtc_update_irq(rtc, num, RTC_UF | RTC_IRQF);
  79 }
  80 static void rtc_uie_timer(unsigned long data)
  81 {
  82         struct rtc_device *rtc = (struct rtc_device *)data;
  83         unsigned long flags;
  84
  85         spin_lock_irqsave(&rtc->irq_lock, flags);
  86         rtc->uie_timer_active = 0;
  87         rtc->uie_task_active = 1;
  88         if ((schedule_work(&rtc->uie_task) == 0))
  89                 rtc->uie_task_active = 0;
  90         spin_unlock_irqrestore(&rtc->irq_lock, flags);
  91 }
  92
  93 static int clear_uie(struct rtc_device *rtc)
  94 {
  95         spin_lock_irq(&rtc->irq_lock);
  96         if (rtc->uie_irq_active) {
  97                 rtc->stop_uie_polling = 1;
  98                 if (rtc->uie_timer_active) {
  99                         spin_unlock_irq(&rtc->irq_lock);
 100                         del_timer_sync(&rtc->uie_timer);
 101                         spin_lock_irq(&rtc->irq_lock);
 102                         rtc->uie_timer_active = 0;
 103                 }
 104                 if (rtc->uie_task_active) {
 105                         spin_unlock_irq(&rtc->irq_lock);
 106                         flush_scheduled_work();
 107                         spin_lock_irq(&rtc->irq_lock);
 108                 }
 109                 rtc->uie_irq_active = 0;
 110         }
 111         spin_unlock_irq(&rtc->irq_lock);
 112         return 0;
 113 }
 114
 115 static int set_uie(struct rtc_device *rtc)
 116 {
 117         struct rtc_time tm;
 118         int err;
 119
 120         err = rtc_read_time(rtc, &tm);
 121         if (err)
 122                 return err;
 123         spin_lock_irq(&rtc->irq_lock);
 124         if (!rtc->uie_irq_active) {
 125                 rtc->uie_irq_active = 1;
 126                 rtc->stop_uie_polling = 0;
 127                 rtc->oldsecs = tm.tm_sec;
 128                 rtc->uie_task_active = 1;
 129                 if (schedule_work(&rtc->uie_task) == 0)
 130                         rtc->uie_task_active = 0;
 131         }
 132         rtc->irq_data = 0;
 133         spin_unlock_irq(&rtc->irq_lock);
 134         return 0;
 135 }
 136
 137 int rtc_dev_update_irq_enable_emul(struct rtc_device *rtc, unsigned int enabled)
 138 {
 139         if (enabled)
 140                 return set_uie(rtc);
 141         else
 142                 return clear_uie(rtc);
 143 }
 144 EXPORT_SYMBOL(rtc_dev_update_irq_enable_emul);
 145
 146 #endif /* CONFIG_RTC_INTF_DEV_UIE_EMUL */
 147
 148 static ssize_t
 149 rtc_dev_read(struct file *file, char __user *buf, size_t count, loff_t *ppos)
 150 {
 151         struct rtc_device *rtc = file->private_data;
 152
 153         DECLARE_WAITQUEUE(wait, current);
 154         unsigned long data;
 155         ssize_t ret;
 156
 157         if (count != sizeof(unsigned int) && count < sizeof(unsigned long))
 158                 return -EINVAL;
 159
 160         add_wait_queue(&rtc->irq_queue, &wait);
 161         do {
 162                 __set_current_state(TASK_INTERRUPTIBLE);
 163
 164                 spin_lock_irq(&rtc->irq_lock);
 165                 data = rtc->irq_data;
 166                 rtc->irq_data = 0;
 167                 spin_unlock_irq(&rtc->irq_lock);
 168
 169                 if (data != 0) {
 170                         ret = 0;
 171                         break;
 172                 }
 173                 if (file->f_flags & O_NONBLOCK) {
 174                         ret = -EAGAIN;
 175                         break;
 176                 }
 177                 if (signal_pending(current)) {
 178                         ret = -ERESTARTSYS;
 179                         break;
 180                 }
 181                 schedule();
 182         } while (1);
 183         set_current_state(TASK_RUNNING);
 184         remove_wait_queue(&rtc->irq_queue, &wait);
 185
 186         if (ret == 0) {
 187                 /* Check for any data updates */
 188                 if (rtc->ops->read_callback)
 189                         data = rtc->ops->read_callback(rtc->dev.parent,
 190                                                        data);
 191
 192                 if (sizeof(int) != sizeof(long) &&
 193                     count == sizeof(unsigned int))
 194                         ret = put_user(data, (unsigned int __user *)buf) ?:
 195                                 sizeof(unsigned int);
 196                 else
 197                         ret = put_user(data, (unsigned long __user *)buf) ?:
 198                                 sizeof(unsigned long);
 199         }
 200         return ret;
 201 }
 202
 203 static unsigned int rtc_dev_poll(struct file *file, poll_table *wait)
 204 {
 205         struct rtc_device *rtc = file->private_data;
 206         unsigned long data;
 207
 208         poll_wait(file, &rtc->irq_queue, wait);
 209
 210         data = rtc->irq_data;
 211
 212         return (data != 0) ? (POLLIN | POLLRDNORM) : 0;
 213 }
 214
 215 static long rtc_dev_ioctl(struct file *file,
 216                 unsigned int cmd, unsigned long arg)
 217 {
 218         int err = 0;
 219         struct rtc_device *rtc = file->private_data;
 220         const struct rtc_class_ops *ops = rtc->ops;
 221         struct rtc_time tm;
 222         struct rtc_wkalrm alarm;
 223         void __user *uarg = (void __user *) arg;
 224
 225         err = mutex_lock_interruptible(&rtc->ops_lock);
 226         if (err)
 227                 return err;
 228
 229         /* check that the calling task has appropriate permissions
 230          * for certain ioctls. doing this check here is useful
 231          * to avoid duplicate code in each driver.
 232          */
 233         switch (cmd) {
 234         case RTC_EPOCH_SET:
 235         case RTC_SET_TIME:
 236                 if (!capable(CAP_SYS_TIME))
 237                         err = -EACCES;
 238                 break;
 239
 240         case RTC_IRQP_SET:
 241                 if (arg > rtc->max_user_freq && !capable(CAP_SYS_RESOURCE))
 242                         err = -EACCES;
 243                 break;
 244
 245         case RTC_PIE_ON:
 246                 if (rtc->irq_freq > rtc->max_user_freq &&
 247                                 !capable(CAP_SYS_RESOURCE))
 248                         err = -EACCES;
 249                 break;
 250         }
 251
 252         if (err)
 253                 goto done;
 254
 255         /* try the driver's ioctl interface */
 256         if (ops->ioctl) {
 257                 err = ops->ioctl(rtc->dev.parent, cmd, arg);
 258                 if (err != -ENOIOCTLCMD) {
 259                         mutex_unlock(&rtc->ops_lock);
 260                         return err;
 261                 }
 262         }
 263
 264         /* if the driver does not provide the ioctl interface
 265          * or if that particular ioctl was not implemented
 266          * (-ENOIOCTLCMD), we will try to emulate here.
 267          *
 268          * Drivers *SHOULD NOT* provide ioctl implementations
 269          * for these requests.  Instead, provide methods to
 270          * support the following code, so that the RTC's main
 271          * features are accessible without using ioctls.
 272          *
 273          * RTC and alarm times will be in UTC, by preference,
 274          * but dual-booting with MS-Windows implies RTCs must
 275          * use the local wall clock time.
 276          */
 277
 278         switch (cmd) {
 279         case RTC_ALM_READ:
 280                 mutex_unlock(&rtc->ops_lock);
 281
 282                 err = rtc_read_alarm(rtc, &alarm);
 283                 if (err < 0)
 284                         return err;
 285
 286                 if (copy_to_user(uarg, &alarm.time, sizeof(tm)))
 287                         err = -EFAULT;
 288                 return err;
 289
 290         case RTC_ALM_SET:
 291                 mutex_unlock(&rtc->ops_lock);
 292
 293                 if (copy_from_user(&alarm.time, uarg, sizeof(tm)))
 294                         return -EFAULT;
 295
 296                 alarm.enabled = 0;
 297                 alarm.pending = 0;
 298                 alarm.time.tm_wday = -1;
 299                 alarm.time.tm_yday = -1;
 300                 alarm.time.tm_isdst = -1;
 301
 302                 /* RTC_ALM_SET alarms may be up to 24 hours in the future.
 303                  * Rather than expecting every RTC to implement "don't care"
 304                  * for day/month/year fields, just force the alarm to have
 305                  * the right values for those fields.
 306                  *
 307                  * RTC_WKALM_SET should be used instead.  Not only does it
 308                  * eliminate the need for a separate RTC_AIE_ON call, it
 309                  * doesn't have the "alarm 23:59:59 in the future" race.
 310                  *
 311                  * NOTE:  some legacy code may have used invalid fields as
 312                  * wildcards, exposing hardware "periodic alarm" capabilities.
 313                  * Not supported here.
 314                  */
 315                 {
 316                         unsigned long now, then;
 317
 318                         err = rtc_read_time(rtc, &tm);
 319                         if (err < 0)
 320                                 return err;
 321                         rtc_tm_to_time(&tm, &now);
 322
 323                         alarm.time.tm_mday = tm.tm_mday;
 324                         alarm.time.tm_mon = tm.tm_mon;
 325                         alarm.time.tm_year = tm.tm_year;
 326                         err  = rtc_valid_tm(&alarm.time);
 327                         if (err < 0)
 328                                 return err;
 329                         rtc_tm_to_time(&alarm.time, &then);
 330
 331                         /* alarm may need to wrap into tomorrow */
 332                         if (then < now) {
 333                                 rtc_time_to_tm(now + 24 * 60 * 60, &tm);
 334                                 alarm.time.tm_mday = tm.tm_mday;
 335                                 alarm.time.tm_mon = tm.tm_mon;
 336                                 alarm.time.tm_year = tm.tm_year;
 337                         }
 338                 }
 339
 340                 return rtc_set_alarm(rtc, &alarm);
 341
 342         case RTC_RD_TIME:
 343                 mutex_unlock(&rtc->ops_lock);
 344
 345                 err = rtc_read_time(rtc, &tm);
 346                 if (err < 0)
 347                         return err;
 348
 349                 if (copy_to_user(uarg, &tm, sizeof(tm)))
 350                         err = -EFAULT;
 351                 return err;
 352
 353         case RTC_SET_TIME:
 354                 mutex_unlock(&rtc->ops_lock);
 355
 356                 if (copy_from_user(&tm, uarg, sizeof(tm)))
 357                         return -EFAULT;
 358
 359                 return rtc_set_time(rtc, &tm);
 360
 361         case RTC_PIE_ON:
 362                 err = rtc_irq_set_state(rtc, NULL, 1);
 363                 break;
 364
 365         case RTC_PIE_OFF:
 366                 err = rtc_irq_set_state(rtc, NULL, 0);
 367                 break;
 368
 369         case RTC_AIE_ON:
 370                 mutex_unlock(&rtc->ops_lock);
 371                 return rtc_alarm_irq_enable(rtc, 1);
 372
 373         case RTC_AIE_OFF:
 374                 mutex_unlock(&rtc->ops_lock);
 375                 return rtc_alarm_irq_enable(rtc, 0);
 376
 377         case RTC_UIE_ON:
 378                 mutex_unlock(&rtc->ops_lock);
 379                 return rtc_update_irq_enable(rtc, 1);
 380
 381         case RTC_UIE_OFF:
 382                 mutex_unlock(&rtc->ops_lock);
 383                 return rtc_update_irq_enable(rtc, 0);
 384
 385         case RTC_IRQP_SET:
 386                 err = rtc_irq_set_freq(rtc, NULL, arg);
 387                 break;
 388
 389         case RTC_IRQP_READ:
 390                 err = put_user(rtc->irq_freq, (unsigned long __user *)uarg);
 391                 break;
 392
 393 #if 0
 394         case RTC_EPOCH_SET:
 395 #ifndef rtc_epoch
 396                 /*
 397                  * There were no RTC clocks before 1900.
 398                  */
 399                 if (arg < 1900) {
 400                         err = -EINVAL;
 401                         break;
 402                 }
 403                 rtc_epoch = arg;
 404                 err = 0;
 405 #endif
 406                 break;
 407
 408         case RTC_EPOCH_READ:
 409                 err = put_user(rtc_epoch, (unsigned long __user *)uarg);
 410                 break;
 411 #endif
 412         case RTC_WKALM_SET:
 413                 mutex_unlock(&rtc->ops_lock);
 414                 if (copy_from_user(&alarm, uarg, sizeof(alarm)))
 415                         return -EFAULT;
 416
 417                 return rtc_set_alarm(rtc, &alarm);
 418
 419         case RTC_WKALM_RD:
 420                 mutex_unlock(&rtc->ops_lock);
 421                 err = rtc_read_alarm(rtc, &alarm);
 422                 if (err < 0)
 423                         return err;
 424
 425                 if (copy_to_user(uarg, &alarm, sizeof(alarm)))
 426                         err = -EFAULT;
 427                 return err;
 428
 429         default:
 430                 err = -ENOTTY;
 431                 break;
 432         }
 433
 434 done:
 435         mutex_unlock(&rtc->ops_lock);
 436         return err;
 437 }
 438
 439 static int rtc_dev_fasync(int fd, struct file *file, int on)
 440 {
 441         struct rtc_device *rtc = file->private_data;
 442         return fasync_helper(fd, file, on, &rtc->async_queue);
 443 }
 444
 445 static int rtc_dev_release(struct inode *inode, struct file *file)
 446 {
 447         struct rtc_device *rtc = file->private_data;
 448
 449         /* We shut down the repeating IRQs that userspace enabled,
 450          * since nothing is listening to them.
 451          *  - Update (UIE) ... currently only managed through ioctls
 452          *  - Periodic (PIE) ... also used through rtc_*() interface calls
 453          *
 454          * Leave the alarm alone; it may be set to trigger a system wakeup
 455          * later, or be used by kernel code, and is a one-shot event anyway.
 456          */
 457
 458         /* Keep ioctl until all drivers are converted */
 459         rtc_dev_ioctl(file, RTC_UIE_OFF, 0);
 460         rtc_update_irq_enable(rtc, 0);
 461         rtc_irq_set_state(rtc, NULL, 0);
 462
 463         if (rtc->ops->release)
 464                 rtc->ops->release(rtc->dev.parent);
 465
 466         clear_bit_unlock(RTC_DEV_BUSY, &rtc->flags);
 467         return 0;
 468 }
 469
 470 static const struct file_operations rtc_dev_fops = {
 471         .owner          = THIS_MODULE,
 472         .llseek         = no_llseek,
 473         .read           = rtc_dev_read,
 474         .poll           = rtc_dev_poll,
 475         .unlocked_ioctl = rtc_dev_ioctl,
 476         .open           = rtc_dev_open,
 477         .release        = rtc_dev_release,
 478         .fasync         = rtc_dev_fasync,
 479 };
 480
 481 /* insertion/removal hooks */
 482
 483 void rtc_dev_prepare(struct rtc_device *rtc)
 484 {
 485         if (!rtc_devt)
 486                 return;
 487
 488         if (rtc->id >= RTC_DEV_MAX) {
 489                 pr_debug("%s: too many RTC devices\n", rtc->name);
 490                 return;
 491         }
 492
 493         rtc->dev.devt = MKDEV(MAJOR(rtc_devt), rtc->id);
 494
 495 #ifdef CONFIG_RTC_INTF_DEV_UIE_EMUL
 496         INIT_WORK(&rtc->uie_task, rtc_uie_task);
 497         setup_timer(&rtc->uie_timer, rtc_uie_timer, (unsigned long)rtc);
 498 #endif
 499
 500         cdev_init(&rtc->char_dev, &rtc_dev_fops);
 501         rtc->char_dev.owner = rtc->owner;
 502 }
 503
 504 void rtc_dev_add_device(struct rtc_device *rtc)
 505 {
 506         if (cdev_add(&rtc->char_dev, rtc->dev.devt, 1))
 507                 printk(KERN_WARNING "%s: failed to add char device %d:%d\n",
 508                         rtc->name, MAJOR(rtc_devt), rtc->id);
 509         else
 510                 pr_debug("%s: dev (%d:%d)\n", rtc->name,
 511                         MAJOR(rtc_devt), rtc->id);
 512 }
 513
 514 void rtc_dev_del_device(struct rtc_device *rtc)
 515 {
 516         if (rtc->dev.devt)
 517                 cdev_del(&rtc->char_dev);
 518 }
 519
 520 void __init rtc_dev_init(void)
 521 {
 522         int err;
 523
 524         err = alloc_chrdev_region(&rtc_devt, 0, RTC_DEV_MAX, "rtc");
 525         if (err < 0)
 526                 printk(KERN_ERR "%s: failed to allocate char dev region\n",
 527                         __FILE__);
 528 }
 529
 530 void __exit rtc_dev_exit(void)
 531 {
 532         if (rtc_devt)
 533                 unregister_chrdev_region(rtc_devt, RTC_DEV_MAX);
 534 }