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