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         local_irq_disable();
  64         spin_lock(&rtc->irq_lock);
  65         if (rtc->stop_uie_polling || err) {
  66                 rtc->uie_task_active = 0;
  67         } else if (rtc->oldsecs != tm.tm_sec) {
  68                 num = (tm.tm_sec + 60 - rtc->oldsecs) % 60;
  69                 rtc->oldsecs = tm.tm_sec;
  70                 rtc->uie_timer.expires = jiffies + HZ - (HZ/10);
  71                 rtc->uie_timer_active = 1;
  72                 rtc->uie_task_active = 0;
  73                 add_timer(&rtc->uie_timer);
  74         } else if (schedule_work(&rtc->uie_task) == 0) {
  75                 rtc->uie_task_active = 0;
  76         }
  77         spin_unlock(&rtc->irq_lock);
  78         if (num)
  79                 rtc_update_irq(rtc, num, RTC_UF | RTC_IRQF);
  80         local_irq_enable();
  81 }
  82 static void rtc_uie_timer(unsigned long data)
  83 {
  84         struct rtc_device *rtc = (struct rtc_device *)data;
  85         unsigned long flags;
  86
  87         spin_lock_irqsave(&rtc->irq_lock, flags);
  88         rtc->uie_timer_active = 0;
  89         rtc->uie_task_active = 1;
  90         if ((schedule_work(&rtc->uie_task) == 0))
  91                 rtc->uie_task_active = 0;
  92         spin_unlock_irqrestore(&rtc->irq_lock, flags);
  93 }
  94
  95 static int clear_uie(struct rtc_device *rtc)
  96 {
  97         spin_lock_irq(&rtc->irq_lock);
  98         if (rtc->uie_irq_active) {
  99                 rtc->stop_uie_polling = 1;
 100                 if (rtc->uie_timer_active) {
 101                         spin_unlock_irq(&rtc->irq_lock);
 102                         del_timer_sync(&rtc->uie_timer);
 103                         spin_lock_irq(&rtc->irq_lock);
 104                         rtc->uie_timer_active = 0;
 105                 }
 106                 if (rtc->uie_task_active) {
 107                         spin_unlock_irq(&rtc->irq_lock);
 108                         flush_scheduled_work();
 109                         spin_lock_irq(&rtc->irq_lock);
 110                 }
 111                 rtc->uie_irq_active = 0;
 112         }
 113         spin_unlock_irq(&rtc->irq_lock);
 114         return 0;
 115 }
 116
 117 static int set_uie(struct rtc_device *rtc)
 118 {
 119         struct rtc_time tm;
 120         int err;
 121
 122         err = rtc_read_time(rtc, &tm);
 123         if (err)
 124                 return err;
 125         spin_lock_irq(&rtc->irq_lock);
 126         if (!rtc->uie_irq_active) {
 127                 rtc->uie_irq_active = 1;
 128                 rtc->stop_uie_polling = 0;
 129                 rtc->oldsecs = tm.tm_sec;
 130                 rtc->uie_task_active = 1;
 131                 if (schedule_work(&rtc->uie_task) == 0)
 132                         rtc->uie_task_active = 0;
 133         }
 134         rtc->irq_data = 0;
 135         spin_unlock_irq(&rtc->irq_lock);
 136         return 0;
 137 }
 138
 139 int rtc_dev_update_irq_enable_emul(struct rtc_device *rtc, unsigned int enabled)
 140 {
 141         if (enabled)
 142                 return set_uie(rtc);
 143         else
 144                 return clear_uie(rtc);
 145 }
 146 EXPORT_SYMBOL(rtc_dev_update_irq_enable_emul);
 147
 148 #endif /* CONFIG_RTC_INTF_DEV_UIE_EMUL */
 149
 150 static ssize_t
 151 rtc_dev_read(struct file *file, char __user *buf, size_t count, loff_t *ppos)
 152 {
 153         struct rtc_device *rtc = file->private_data;
 154
 155         DECLARE_WAITQUEUE(wait, current);
 156         unsigned long data;
 157         ssize_t ret;
 158
 159         if (count != sizeof(unsigned int) && count < sizeof(unsigned long))
 160                 return -EINVAL;
 161
 162         add_wait_queue(&rtc->irq_queue, &wait);
 163         do {
 164                 __set_current_state(TASK_INTERRUPTIBLE);
 165
 166                 spin_lock_irq(&rtc->irq_lock);
 167                 data = rtc->irq_data;
 168                 rtc->irq_data = 0;
 169                 spin_unlock_irq(&rtc->irq_lock);
 170
 171                 if (data != 0) {
 172                         ret = 0;
 173                         break;
 174                 }
 175                 if (file->f_flags & O_NONBLOCK) {
 176                         ret = -EAGAIN;
 177                         break;
 178                 }
 179                 if (signal_pending(current)) {
 180                         ret = -ERESTARTSYS;
 181                         break;
 182                 }
 183                 schedule();
 184         } while (1);
 185         set_current_state(TASK_RUNNING);
 186         remove_wait_queue(&rtc->irq_queue, &wait);
 187
 188         if (ret == 0) {
 189                 /* Check for any data updates */
 190                 if (rtc->ops->read_callback)
 191                         data = rtc->ops->read_callback(rtc->dev.parent,
 192                                                        data);
 193
 194                 if (sizeof(int) != sizeof(long) &&
 195                     count == sizeof(unsigned int))
 196                         ret = put_user(data, (unsigned int __user *)buf) ?:
 197                                 sizeof(unsigned int);
 198                 else
 199                         ret = put_user(data, (unsigned long __user *)buf) ?:
 200                                 sizeof(unsigned long);
 201         }
 202         return ret;
 203 }
 204
 205 static unsigned int rtc_dev_poll(struct file *file, poll_table *wait)
 206 {
 207         struct rtc_device *rtc = file->private_data;
 208         unsigned long data;
 209
 210         poll_wait(file, &rtc->irq_queue, wait);
 211
 212         data = rtc->irq_data;
 213
 214         return (data != 0) ? (POLLIN | POLLRDNORM) : 0;
 215 }
 216
 217 static long rtc_dev_ioctl(struct file *file,
 218                 unsigned int cmd, unsigned long arg)
 219 {
 220         int err = 0;
 221         struct rtc_device *rtc = file->private_data;
 222         const struct rtc_class_ops *ops = rtc->ops;
 223         struct rtc_time tm;
 224         struct rtc_wkalrm alarm;
 225         void __user *uarg = (void __user *) arg;
 226
 227         err = mutex_lock_interruptible(&rtc->ops_lock);
 228         if (err)
 229                 return err;
 230
 231         /* check that the calling task has appropriate permissions
 232          * for certain ioctls. doing this check here is useful
 233          * to avoid duplicate code in each driver.
 234          */
 235         switch (cmd) {
 236         case RTC_EPOCH_SET:
 237         case RTC_SET_TIME:
 238                 if (!capable(CAP_SYS_TIME))
 239                         err = -EACCES;
 240                 break;
 241
 242         case RTC_IRQP_SET:
 243                 if (arg > rtc->max_user_freq && !capable(CAP_SYS_RESOURCE))
 244                         err = -EACCES;
 245                 break;
 246
 247         case RTC_PIE_ON:
 248                 if (rtc->irq_freq > rtc->max_user_freq &&
 249                                 !capable(CAP_SYS_RESOURCE))
 250                         err = -EACCES;
 251                 break;
 252         }
 253
 254         if (err)
 255                 goto done;
 256
 257         /* try the driver's ioctl interface */
 258         if (ops->ioctl) {
 259                 err = ops->ioctl(rtc->dev.parent, cmd, arg);
 260                 if (err != -ENOIOCTLCMD) {
 261                         mutex_unlock(&rtc->ops_lock);
 262                         return err;
 263                 }
 264         }
 265
 266         /* if the driver does not provide the ioctl interface
 267          * or if that particular ioctl was not implemented
 268          * (-ENOIOCTLCMD), we will try to emulate here.
 269          *
 270          * Drivers *SHOULD NOT* provide ioctl implementations
 271          * for these requests.  Instead, provide methods to
 272          * support the following code, so that the RTC's main
 273          * features are accessible without using ioctls.
 274          *
 275          * RTC and alarm times will be in UTC, by preference,
 276          * but dual-booting with MS-Windows implies RTCs must
 277          * use the local wall clock time.
 278          */
 279
 280         switch (cmd) {
 281         case RTC_ALM_READ:
 282                 mutex_unlock(&rtc->ops_lock);
 283
 284                 err = rtc_read_alarm(rtc, &alarm);
 285                 if (err < 0)
 286                         return err;
 287
 288                 if (copy_to_user(uarg, &alarm.time, sizeof(tm)))
 289                         err = -EFAULT;
 290                 return err;
 291
 292         case RTC_ALM_SET:
 293                 mutex_unlock(&rtc->ops_lock);
 294
 295                 if (copy_from_user(&alarm.time, uarg, sizeof(tm)))
 296                         return -EFAULT;
 297
 298                 alarm.enabled = 0;
 299                 alarm.pending = 0;
 300                 alarm.time.tm_wday = -1;
 301                 alarm.time.tm_yday = -1;
 302                 alarm.time.tm_isdst = -1;
 303
 304                 /* RTC_ALM_SET alarms may be up to 24 hours in the future.
 305                  * Rather than expecting every RTC to implement "don't care"
 306                  * for day/month/year fields, just force the alarm to have
 307                  * the right values for those fields.
 308                  *
 309                  * RTC_WKALM_SET should be used instead.  Not only does it
 310                  * eliminate the need for a separate RTC_AIE_ON call, it
 311                  * doesn't have the "alarm 23:59:59 in the future" race.
 312                  *
 313                  * NOTE:  some legacy code may have used invalid fields as
 314                  * wildcards, exposing hardware "periodic alarm" capabilities.
 315                  * Not supported here.
 316                  */
 317                 {
 318                         unsigned long now, then;
 319
 320                         err = rtc_read_time(rtc, &tm);
 321                         if (err < 0)
 322                                 return err;
 323                         rtc_tm_to_time(&tm, &now);
 324
 325                         alarm.time.tm_mday = tm.tm_mday;
 326                         alarm.time.tm_mon = tm.tm_mon;
 327                         alarm.time.tm_year = tm.tm_year;
 328                         err  = rtc_valid_tm(&alarm.time);
 329                         if (err < 0)
 330                                 return err;
 331                         rtc_tm_to_time(&alarm.time, &then);
 332
 333                         /* alarm may need to wrap into tomorrow */
 334                         if (then < now) {
 335                                 rtc_time_to_tm(now + 24 * 60 * 60, &tm);
 336                                 alarm.time.tm_mday = tm.tm_mday;
 337                                 alarm.time.tm_mon = tm.tm_mon;
 338                                 alarm.time.tm_year = tm.tm_year;
 339                         }
 340                 }
 341
 342                 return rtc_set_alarm(rtc, &alarm);
 343
 344         case RTC_RD_TIME:
 345                 mutex_unlock(&rtc->ops_lock);
 346
 347                 err = rtc_read_time(rtc, &tm);
 348                 if (err < 0)
 349                         return err;
 350
 351                 if (copy_to_user(uarg, &tm, sizeof(tm)))
 352                         err = -EFAULT;
 353                 return err;
 354
 355         case RTC_SET_TIME:
 356                 mutex_unlock(&rtc->ops_lock);
 357
 358                 if (copy_from_user(&tm, uarg, sizeof(tm)))
 359                         return -EFAULT;
 360
 361                 return rtc_set_time(rtc, &tm);
 362
 363         case RTC_PIE_ON:
 364                 err = rtc_irq_set_state(rtc, NULL, 1);
 365                 break;
 366
 367         case RTC_PIE_OFF:
 368                 err = rtc_irq_set_state(rtc, NULL, 0);
 369                 break;
 370
 371         case RTC_AIE_ON:
 372                 mutex_unlock(&rtc->ops_lock);
 373                 return rtc_alarm_irq_enable(rtc, 1);
 374
 375         case RTC_AIE_OFF:
 376                 mutex_unlock(&rtc->ops_lock);
 377                 return rtc_alarm_irq_enable(rtc, 0);
 378
 379         case RTC_UIE_ON:
 380                 mutex_unlock(&rtc->ops_lock);
 381                 return rtc_update_irq_enable(rtc, 1);
 382
 383         case RTC_UIE_OFF:
 384                 mutex_unlock(&rtc->ops_lock);
 385                 return rtc_update_irq_enable(rtc, 0);
 386
 387         case RTC_IRQP_SET:
 388                 err = rtc_irq_set_freq(rtc, NULL, arg);
 389                 break;
 390
 391         case RTC_IRQP_READ:
 392                 err = put_user(rtc->irq_freq, (unsigned long __user *)uarg);
 393                 break;
 394
 395 #if 0
 396         case RTC_EPOCH_SET:
 397 #ifndef rtc_epoch
 398                 /*
 399                  * There were no RTC clocks before 1900.
 400                  */
 401                 if (arg < 1900) {
 402                         err = -EINVAL;
 403                         break;
 404                 }
 405                 rtc_epoch = arg;
 406                 err = 0;
 407 #endif
 408                 break;
 409
 410         case RTC_EPOCH_READ:
 411                 err = put_user(rtc_epoch, (unsigned long __user *)uarg);
 412                 break;
 413 #endif
 414         case RTC_WKALM_SET:
 415                 mutex_unlock(&rtc->ops_lock);
 416                 if (copy_from_user(&alarm, uarg, sizeof(alarm)))
 417                         return -EFAULT;
 418
 419                 return rtc_set_alarm(rtc, &alarm);
 420
 421         case RTC_WKALM_RD:
 422                 mutex_unlock(&rtc->ops_lock);
 423                 err = rtc_read_alarm(rtc, &alarm);
 424                 if (err < 0)
 425                         return err;
 426
 427                 if (copy_to_user(uarg, &alarm, sizeof(alarm)))
 428                         err = -EFAULT;
 429                 return err;
 430
 431         default:
 432                 err = -ENOTTY;
 433                 break;
 434         }
 435
 436 done:
 437         mutex_unlock(&rtc->ops_lock);
 438         return err;
 439 }
 440
 441 static int rtc_dev_fasync(int fd, struct file *file, int on)
 442 {
 443         struct rtc_device *rtc = file->private_data;
 444         return fasync_helper(fd, file, on, &rtc->async_queue);
 445 }
 446
 447 static int rtc_dev_release(struct inode *inode, struct file *file)
 448 {
 449         struct rtc_device *rtc = file->private_data;
 450
 451         /* We shut down the repeating IRQs that userspace enabled,
 452          * since nothing is listening to them.
 453          *  - Update (UIE) ... currently only managed through ioctls
 454          *  - Periodic (PIE) ... also used through rtc_*() interface calls
 455          *
 456          * Leave the alarm alone; it may be set to trigger a system wakeup
 457          * later, or be used by kernel code, and is a one-shot event anyway.
 458          */
 459
 460         /* Keep ioctl until all drivers are converted */
 461         rtc_dev_ioctl(file, RTC_UIE_OFF, 0);
 462         rtc_update_irq_enable(rtc, 0);
 463         rtc_irq_set_state(rtc, NULL, 0);
 464
 465         if (rtc->ops->release)
 466                 rtc->ops->release(rtc->dev.parent);
 467
 468         clear_bit_unlock(RTC_DEV_BUSY, &rtc->flags);
 469         return 0;
 470 }
 471
 472 static const struct file_operations rtc_dev_fops = {
 473         .owner          = THIS_MODULE,
 474         .llseek         = no_llseek,
 475         .read           = rtc_dev_read,
 476         .poll           = rtc_dev_poll,
 477         .unlocked_ioctl = rtc_dev_ioctl,
 478         .open           = rtc_dev_open,
 479         .release        = rtc_dev_release,
 480         .fasync         = rtc_dev_fasync,
 481 };
 482
 483 /* insertion/removal hooks */
 484
 485 void rtc_dev_prepare(struct rtc_device *rtc)
 486 {
 487         if (!rtc_devt)
 488                 return;
 489
 490         if (rtc->id >= RTC_DEV_MAX) {
 491                 pr_debug("%s: too many RTC devices\n", rtc->name);
 492                 return;
 493         }
 494
 495         rtc->dev.devt = MKDEV(MAJOR(rtc_devt), rtc->id);
 496
 497 #ifdef CONFIG_RTC_INTF_DEV_UIE_EMUL
 498         INIT_WORK(&rtc->uie_task, rtc_uie_task);
 499         setup_timer(&rtc->uie_timer, rtc_uie_timer, (unsigned long)rtc);
 500 #endif
 501
 502         cdev_init(&rtc->char_dev, &rtc_dev_fops);
 503         rtc->char_dev.owner = rtc->owner;
 504 }
 505
 506 void rtc_dev_add_device(struct rtc_device *rtc)
 507 {
 508         if (cdev_add(&rtc->char_dev, rtc->dev.devt, 1))
 509                 printk(KERN_WARNING "%s: failed to add char device %d:%d\n",
 510                         rtc->name, MAJOR(rtc_devt), rtc->id);
 511         else
 512                 pr_debug("%s: dev (%d:%d)\n", rtc->name,
 513                         MAJOR(rtc_devt), rtc->id);
 514 }
 515
 516 void rtc_dev_del_device(struct rtc_device *rtc)
 517 {
 518         if (rtc->dev.devt)
 519                 cdev_del(&rtc->char_dev);
 520 }
 521
 522 void __init rtc_dev_init(void)
 523 {
 524         int err;
 525
 526         err = alloc_chrdev_region(&rtc_devt, 0, RTC_DEV_MAX, "rtc");
 527         if (err < 0)
 528                 printk(KERN_ERR "%s: failed to allocate char dev region\n",
 529                         __FILE__);
 530 }
 531
 532 void __exit rtc_dev_exit(void)
 533 {
 534         if (rtc_devt)
 535                 unregister_chrdev_region(rtc_devt, RTC_DEV_MAX);
 536 }