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
  17 static struct class *rtc_dev_class;
  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         /* We keep the lock as long as the device is in use
  30          * and return immediately if busy
  31          */
  32         if (!(mutex_trylock(&rtc->char_lock)))
  33                 return -EBUSY;
  34
  35         file->private_data = &rtc->class_dev;
  36
  37         err = ops->open ? ops->open(rtc->class_dev.dev) : 0;
  38         if (err == 0) {
  39                 spin_lock_irq(&rtc->irq_lock);
  40                 rtc->irq_data = 0;
  41                 spin_unlock_irq(&rtc->irq_lock);
  42
  43                 return 0;
  44         }
  45
  46         /* something has gone wrong, release the lock */
  47         mutex_unlock(&rtc->char_lock);
  48         return err;
  49 }
  50
  51 #ifdef CONFIG_RTC_INTF_DEV_UIE_EMUL
  52 /*
  53  * Routine to poll RTC seconds field for change as often as possible,
  54  * after first RTC_UIE use timer to reduce polling
  55  */
  56 static void rtc_uie_task(void *data)
  57 {
  58         struct rtc_device *rtc = data;
  59         struct rtc_time tm;
  60         int num = 0;
  61         int err;
  62
  63         err = rtc_read_time(&rtc->class_dev, &tm);
  64         spin_lock_irq(&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_irq(&rtc->irq_lock);
  78         if (num)
  79                 rtc_update_irq(&rtc->class_dev, num, RTC_UF | RTC_IRQF);
  80 }
  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->class_dev, &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 = to_rtc_device(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->class_dev.dev,
 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 = to_rtc_device(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 int rtc_dev_ioctl(struct inode *inode, struct file *file,
 207                 unsigned int cmd, unsigned long arg)
 208 {
 209         int err = 0;
 210         struct class_device *class_dev = file->private_data;
 211         struct rtc_device *rtc = to_rtc_device(class_dev);
 212         const struct rtc_class_ops *ops = rtc->ops;
 213         struct rtc_time tm;
 214         struct rtc_wkalrm alarm;
 215         void __user *uarg = (void __user *) arg;
 216
 217         /* check that the calling task has appropriate permissions
 218          * for certain ioctls. doing this check here is useful
 219          * to avoid duplicate code in each driver.
 220          */
 221         switch (cmd) {
 222         case RTC_EPOCH_SET:
 223         case RTC_SET_TIME:
 224                 if (!capable(CAP_SYS_TIME))
 225                         return -EACCES;
 226                 break;
 227
 228         case RTC_IRQP_SET:
 229                 if (arg > rtc->max_user_freq && !capable(CAP_SYS_RESOURCE))
 230                         return -EACCES;
 231                 break;
 232
 233         case RTC_PIE_ON:
 234                 if (!capable(CAP_SYS_RESOURCE))
 235                         return -EACCES;
 236                 break;
 237         }
 238
 239         /* avoid conflicting IRQ users */
 240         if (cmd == RTC_PIE_ON || cmd == RTC_PIE_OFF || cmd == RTC_IRQP_SET) {
 241                 spin_lock(&rtc->irq_task_lock);
 242                 if (rtc->irq_task)
 243                         err = -EBUSY;
 244                 spin_unlock(&rtc->irq_task_lock);
 245
 246                 if (err < 0)
 247                         return err;
 248         }
 249
 250         /* try the driver's ioctl interface */
 251         if (ops->ioctl) {
 252                 err = ops->ioctl(class_dev->dev, cmd, arg);
 253                 if (err != -ENOIOCTLCMD)
 254                         return err;
 255         }
 256
 257         /* if the driver does not provide the ioctl interface
 258          * or if that particular ioctl was not implemented
 259          * (-ENOIOCTLCMD), we will try to emulate here.
 260          */
 261
 262         switch (cmd) {
 263         case RTC_ALM_READ:
 264                 err = rtc_read_alarm(class_dev, &alarm);
 265                 if (err < 0)
 266                         return err;
 267
 268                 if (copy_to_user(uarg, &alarm.time, sizeof(tm)))
 269                         return -EFAULT;
 270                 break;
 271
 272         case RTC_ALM_SET:
 273                 if (copy_from_user(&alarm.time, uarg, sizeof(tm)))
 274                         return -EFAULT;
 275
 276                 alarm.enabled = 0;
 277                 alarm.pending = 0;
 278                 alarm.time.tm_mday = -1;
 279                 alarm.time.tm_mon = -1;
 280                 alarm.time.tm_year = -1;
 281                 alarm.time.tm_wday = -1;
 282                 alarm.time.tm_yday = -1;
 283                 alarm.time.tm_isdst = -1;
 284                 err = rtc_set_alarm(class_dev, &alarm);
 285                 break;
 286
 287         case RTC_RD_TIME:
 288                 err = rtc_read_time(class_dev, &tm);
 289                 if (err < 0)
 290                         return err;
 291
 292                 if (copy_to_user(uarg, &tm, sizeof(tm)))
 293                         return -EFAULT;
 294                 break;
 295
 296         case RTC_SET_TIME:
 297                 if (copy_from_user(&tm, uarg, sizeof(tm)))
 298                         return -EFAULT;
 299
 300                 err = rtc_set_time(class_dev, &tm);
 301                 break;
 302
 303         case RTC_IRQP_READ:
 304                 if (ops->irq_set_freq)
 305                         err = put_user(rtc->irq_freq, (unsigned long *) arg);
 306                 break;
 307
 308         case RTC_IRQP_SET:
 309                 if (ops->irq_set_freq)
 310                         err = rtc_irq_set_freq(class_dev, rtc->irq_task, arg);
 311                 break;
 312
 313 #if 0
 314         case RTC_EPOCH_SET:
 315 #ifndef rtc_epoch
 316                 /*
 317                  * There were no RTC clocks before 1900.
 318                  */
 319                 if (arg < 1900) {
 320                         err = -EINVAL;
 321                         break;
 322                 }
 323                 rtc_epoch = arg;
 324                 err = 0;
 325 #endif
 326                 break;
 327
 328         case RTC_EPOCH_READ:
 329                 err = put_user(rtc_epoch, (unsigned long __user *)uarg);
 330                 break;
 331 #endif
 332         case RTC_WKALM_SET:
 333                 if (copy_from_user(&alarm, uarg, sizeof(alarm)))
 334                         return -EFAULT;
 335
 336                 err = rtc_set_alarm(class_dev, &alarm);
 337                 break;
 338
 339         case RTC_WKALM_RD:
 340                 err = rtc_read_alarm(class_dev, &alarm);
 341                 if (err < 0)
 342                         return err;
 343
 344                 if (copy_to_user(uarg, &alarm, sizeof(alarm)))
 345                         return -EFAULT;
 346                 break;
 347
 348 #ifdef CONFIG_RTC_INTF_DEV_UIE_EMUL
 349         case RTC_UIE_OFF:
 350                 clear_uie(rtc);
 351                 return 0;
 352
 353         case RTC_UIE_ON:
 354                 return set_uie(rtc);
 355 #endif
 356         default:
 357                 err = -ENOTTY;
 358                 break;
 359         }
 360
 361         return err;
 362 }
 363
 364 static int rtc_dev_release(struct inode *inode, struct file *file)
 365 {
 366         struct rtc_device *rtc = to_rtc_device(file->private_data);
 367
 368 #ifdef CONFIG_RTC_INTF_DEV_UIE_EMUL
 369         clear_uie(rtc);
 370 #endif
 371         if (rtc->ops->release)
 372                 rtc->ops->release(rtc->class_dev.dev);
 373
 374         mutex_unlock(&rtc->char_lock);
 375         return 0;
 376 }
 377
 378 static int rtc_dev_fasync(int fd, struct file *file, int on)
 379 {
 380         struct rtc_device *rtc = to_rtc_device(file->private_data);
 381         return fasync_helper(fd, file, on, &rtc->async_queue);
 382 }
 383
 384 static struct file_operations rtc_dev_fops = {
 385         .owner          = THIS_MODULE,
 386         .llseek         = no_llseek,
 387         .read           = rtc_dev_read,
 388         .poll           = rtc_dev_poll,
 389         .ioctl          = rtc_dev_ioctl,
 390         .open           = rtc_dev_open,
 391         .release        = rtc_dev_release,
 392         .fasync         = rtc_dev_fasync,
 393 };
 394
 395 /* insertion/removal hooks */
 396
 397 static int rtc_dev_add_device(struct class_device *class_dev,
 398                                 struct class_interface *class_intf)
 399 {
 400         int err = 0;
 401         struct rtc_device *rtc = to_rtc_device(class_dev);
 402
 403         if (rtc->id >= RTC_DEV_MAX) {
 404                 dev_err(class_dev->dev, "too many RTCs\n");
 405                 return -EINVAL;
 406         }
 407
 408         mutex_init(&rtc->char_lock);
 409         spin_lock_init(&rtc->irq_lock);
 410         init_waitqueue_head(&rtc->irq_queue);
 411 #ifdef CONFIG_RTC_INTF_DEV_UIE_EMUL
 412         INIT_WORK(&rtc->uie_task, rtc_uie_task, rtc);
 413         setup_timer(&rtc->uie_timer, rtc_uie_timer, (unsigned long)rtc);
 414 #endif
 415
 416         cdev_init(&rtc->char_dev, &rtc_dev_fops);
 417         rtc->char_dev.owner = rtc->owner;
 418
 419         if (cdev_add(&rtc->char_dev, MKDEV(MAJOR(rtc_devt), rtc->id), 1)) {
 420                 dev_err(class_dev->dev,
 421                         "failed to add char device %d:%d\n",
 422                         MAJOR(rtc_devt), rtc->id);
 423                 return -ENODEV;
 424         }
 425
 426         rtc->rtc_dev = class_device_create(rtc_dev_class, NULL,
 427                                                 MKDEV(MAJOR(rtc_devt), rtc->id),
 428                                                 class_dev->dev, "rtc%d", rtc->id);
 429         if (IS_ERR(rtc->rtc_dev)) {
 430                 dev_err(class_dev->dev, "cannot create rtc_dev device\n");
 431                 err = PTR_ERR(rtc->rtc_dev);
 432                 goto err_cdev_del;
 433         }
 434
 435         dev_info(class_dev->dev, "rtc intf: dev (%d:%d)\n",
 436                 MAJOR(rtc->rtc_dev->devt),
 437                 MINOR(rtc->rtc_dev->devt));
 438
 439         return 0;
 440
 441 err_cdev_del:
 442
 443         cdev_del(&rtc->char_dev);
 444         return err;
 445 }
 446
 447 static void rtc_dev_remove_device(struct class_device *class_dev,
 448                                         struct class_interface *class_intf)
 449 {
 450         struct rtc_device *rtc = to_rtc_device(class_dev);
 451
 452         if (rtc->rtc_dev) {
 453                 dev_dbg(class_dev->dev, "removing char %d:%d\n",
 454                         MAJOR(rtc->rtc_dev->devt),
 455                         MINOR(rtc->rtc_dev->devt));
 456
 457                 class_device_unregister(rtc->rtc_dev);
 458                 cdev_del(&rtc->char_dev);
 459         }
 460 }
 461
 462 /* interface registration */
 463
 464 static struct class_interface rtc_dev_interface = {
 465         .add = &rtc_dev_add_device,
 466         .remove = &rtc_dev_remove_device,
 467 };
 468
 469 static int __init rtc_dev_init(void)
 470 {
 471         int err;
 472
 473         rtc_dev_class = class_create(THIS_MODULE, "rtc-dev");
 474         if (IS_ERR(rtc_dev_class))
 475                 return PTR_ERR(rtc_dev_class);
 476
 477         err = alloc_chrdev_region(&rtc_devt, 0, RTC_DEV_MAX, "rtc");
 478         if (err < 0) {
 479                 printk(KERN_ERR "%s: failed to allocate char dev region\n",
 480                         __FILE__);
 481                 goto err_destroy_class;
 482         }
 483
 484         err = rtc_interface_register(&rtc_dev_interface);
 485         if (err < 0) {
 486                 printk(KERN_ERR "%s: failed to register the interface\n",
 487                         __FILE__);
 488                 goto err_unregister_chrdev;
 489         }
 490
 491         return 0;
 492
 493 err_unregister_chrdev:
 494         unregister_chrdev_region(rtc_devt, RTC_DEV_MAX);
 495
 496 err_destroy_class:
 497         class_destroy(rtc_dev_class);
 498
 499         return err;
 500 }
 501
 502 static void __exit rtc_dev_exit(void)
 503 {
 504         class_interface_unregister(&rtc_dev_interface);
 505         class_destroy(rtc_dev_class);
 506         unregister_chrdev_region(rtc_devt, RTC_DEV_MAX);
 507 }
 508
 509 subsys_initcall(rtc_dev_init);
 510 module_exit(rtc_dev_exit);
 511
 512 MODULE_AUTHOR("Alessandro Zummo <a.zummo@towertech.it>");
 513 MODULE_DESCRIPTION("RTC class dev interface");
 514 MODULE_LICENSE("GPL");