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         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         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         /* avoid conflicting IRQ users */
 218         if (cmd == RTC_PIE_ON || cmd == RTC_PIE_OFF || cmd == RTC_IRQP_SET) {
 219                 spin_lock(&rtc->irq_task_lock);
 220                 if (rtc->irq_task)
 221                         err = -EBUSY;
 222                 spin_unlock(&rtc->irq_task_lock);
 223
 224                 if (err < 0)
 225                         return err;
 226         }
 227
 228         /* try the driver's ioctl interface */
 229         if (ops->ioctl) {
 230                 err = ops->ioctl(class_dev->dev, cmd, arg);
 231                 if (err != -ENOIOCTLCMD)
 232                         return err;
 233         }
 234
 235         /* if the driver does not provide the ioctl interface
 236          * or if that particular ioctl was not implemented
 237          * (-ENOIOCTLCMD), we will try to emulate here.
 238          */
 239
 240         switch (cmd) {
 241         case RTC_ALM_READ:
 242                 err = rtc_read_alarm(class_dev, &alarm);
 243                 if (err < 0)
 244                         return err;
 245
 246                 if (copy_to_user(uarg, &alarm.time, sizeof(tm)))
 247                         return -EFAULT;
 248                 break;
 249
 250         case RTC_ALM_SET:
 251                 if (copy_from_user(&alarm.time, uarg, sizeof(tm)))
 252                         return -EFAULT;
 253
 254                 alarm.enabled = 0;
 255                 alarm.pending = 0;
 256                 alarm.time.tm_mday = -1;
 257                 alarm.time.tm_mon = -1;
 258                 alarm.time.tm_year = -1;
 259                 alarm.time.tm_wday = -1;
 260                 alarm.time.tm_yday = -1;
 261                 alarm.time.tm_isdst = -1;
 262                 err = rtc_set_alarm(class_dev, &alarm);
 263                 break;
 264
 265         case RTC_RD_TIME:
 266                 err = rtc_read_time(class_dev, &tm);
 267                 if (err < 0)
 268                         return err;
 269
 270                 if (copy_to_user(uarg, &tm, sizeof(tm)))
 271                         return -EFAULT;
 272                 break;
 273
 274         case RTC_SET_TIME:
 275                 if (!capable(CAP_SYS_TIME))
 276                         return -EACCES;
 277
 278                 if (copy_from_user(&tm, uarg, sizeof(tm)))
 279                         return -EFAULT;
 280
 281                 err = rtc_set_time(class_dev, &tm);
 282                 break;
 283 #if 0
 284         case RTC_EPOCH_SET:
 285 #ifndef rtc_epoch
 286                 /*
 287                  * There were no RTC clocks before 1900.
 288                  */
 289                 if (arg < 1900) {
 290                         err = -EINVAL;
 291                         break;
 292                 }
 293                 if (!capable(CAP_SYS_TIME)) {
 294                         err = -EACCES;
 295                         break;
 296                 }
 297                 rtc_epoch = arg;
 298                 err = 0;
 299 #endif
 300                 break;
 301
 302         case RTC_EPOCH_READ:
 303                 err = put_user(rtc_epoch, (unsigned long __user *)uarg);
 304                 break;
 305 #endif
 306         case RTC_WKALM_SET:
 307                 if (copy_from_user(&alarm, uarg, sizeof(alarm)))
 308                         return -EFAULT;
 309
 310                 err = rtc_set_alarm(class_dev, &alarm);
 311                 break;
 312
 313         case RTC_WKALM_RD:
 314                 err = rtc_read_alarm(class_dev, &alarm);
 315                 if (err < 0)
 316                         return err;
 317
 318                 if (copy_to_user(uarg, &alarm, sizeof(alarm)))
 319                         return -EFAULT;
 320                 break;
 321
 322 #ifdef CONFIG_RTC_INTF_DEV_UIE_EMUL
 323         case RTC_UIE_OFF:
 324                 clear_uie(rtc);
 325                 return 0;
 326
 327         case RTC_UIE_ON:
 328                 return set_uie(rtc);
 329 #endif
 330         default:
 331                 err = -ENOTTY;
 332                 break;
 333         }
 334
 335         return err;
 336 }
 337
 338 static int rtc_dev_release(struct inode *inode, struct file *file)
 339 {
 340         struct rtc_device *rtc = to_rtc_device(file->private_data);
 341
 342 #ifdef CONFIG_RTC_INTF_DEV_UIE_EMUL
 343         clear_uie(rtc);
 344 #endif
 345         if (rtc->ops->release)
 346                 rtc->ops->release(rtc->class_dev.dev);
 347
 348         mutex_unlock(&rtc->char_lock);
 349         return 0;
 350 }
 351
 352 static int rtc_dev_fasync(int fd, struct file *file, int on)
 353 {
 354         struct rtc_device *rtc = to_rtc_device(file->private_data);
 355         return fasync_helper(fd, file, on, &rtc->async_queue);
 356 }
 357
 358 static struct file_operations rtc_dev_fops = {
 359         .owner          = THIS_MODULE,
 360         .llseek         = no_llseek,
 361         .read           = rtc_dev_read,
 362         .poll           = rtc_dev_poll,
 363         .ioctl          = rtc_dev_ioctl,
 364         .open           = rtc_dev_open,
 365         .release        = rtc_dev_release,
 366         .fasync         = rtc_dev_fasync,
 367 };
 368
 369 /* insertion/removal hooks */
 370
 371 static int rtc_dev_add_device(struct class_device *class_dev,
 372                                 struct class_interface *class_intf)
 373 {
 374         int err = 0;
 375         struct rtc_device *rtc = to_rtc_device(class_dev);
 376
 377         if (rtc->id >= RTC_DEV_MAX) {
 378                 dev_err(class_dev->dev, "too many RTCs\n");
 379                 return -EINVAL;
 380         }
 381
 382         mutex_init(&rtc->char_lock);
 383         spin_lock_init(&rtc->irq_lock);
 384         init_waitqueue_head(&rtc->irq_queue);
 385 #ifdef CONFIG_RTC_INTF_DEV_UIE_EMUL
 386         INIT_WORK(&rtc->uie_task, rtc_uie_task, rtc);
 387         setup_timer(&rtc->uie_timer, rtc_uie_timer, (unsigned long)rtc);
 388 #endif
 389
 390         cdev_init(&rtc->char_dev, &rtc_dev_fops);
 391         rtc->char_dev.owner = rtc->owner;
 392
 393         if (cdev_add(&rtc->char_dev, MKDEV(MAJOR(rtc_devt), rtc->id), 1)) {
 394                 cdev_del(&rtc->char_dev);
 395                 dev_err(class_dev->dev,
 396                         "failed to add char device %d:%d\n",
 397                         MAJOR(rtc_devt), rtc->id);
 398                 return -ENODEV;
 399         }
 400
 401         rtc->rtc_dev = class_device_create(rtc_dev_class, NULL,
 402                                                 MKDEV(MAJOR(rtc_devt), rtc->id),
 403                                                 class_dev->dev, "rtc%d", rtc->id);
 404         if (IS_ERR(rtc->rtc_dev)) {
 405                 dev_err(class_dev->dev, "cannot create rtc_dev device\n");
 406                 err = PTR_ERR(rtc->rtc_dev);
 407                 goto err_cdev_del;
 408         }
 409
 410         dev_info(class_dev->dev, "rtc intf: dev (%d:%d)\n",
 411                 MAJOR(rtc->rtc_dev->devt),
 412                 MINOR(rtc->rtc_dev->devt));
 413
 414         return 0;
 415
 416 err_cdev_del:
 417
 418         cdev_del(&rtc->char_dev);
 419         return err;
 420 }
 421
 422 static void rtc_dev_remove_device(struct class_device *class_dev,
 423                                         struct class_interface *class_intf)
 424 {
 425         struct rtc_device *rtc = to_rtc_device(class_dev);
 426
 427         if (rtc->rtc_dev) {
 428                 dev_dbg(class_dev->dev, "removing char %d:%d\n",
 429                         MAJOR(rtc->rtc_dev->devt),
 430                         MINOR(rtc->rtc_dev->devt));
 431
 432                 class_device_unregister(rtc->rtc_dev);
 433                 cdev_del(&rtc->char_dev);
 434         }
 435 }
 436
 437 /* interface registration */
 438
 439 static struct class_interface rtc_dev_interface = {
 440         .add = &rtc_dev_add_device,
 441         .remove = &rtc_dev_remove_device,
 442 };
 443
 444 static int __init rtc_dev_init(void)
 445 {
 446         int err;
 447
 448         rtc_dev_class = class_create(THIS_MODULE, "rtc-dev");
 449         if (IS_ERR(rtc_dev_class))
 450                 return PTR_ERR(rtc_dev_class);
 451
 452         err = alloc_chrdev_region(&rtc_devt, 0, RTC_DEV_MAX, "rtc");
 453         if (err < 0) {
 454                 printk(KERN_ERR "%s: failed to allocate char dev region\n",
 455                         __FILE__);
 456                 goto err_destroy_class;
 457         }
 458
 459         err = rtc_interface_register(&rtc_dev_interface);
 460         if (err < 0) {
 461                 printk(KERN_ERR "%s: failed to register the interface\n",
 462                         __FILE__);
 463                 goto err_unregister_chrdev;
 464         }
 465
 466         return 0;
 467
 468 err_unregister_chrdev:
 469         unregister_chrdev_region(rtc_devt, RTC_DEV_MAX);
 470
 471 err_destroy_class:
 472         class_destroy(rtc_dev_class);
 473
 474         return err;
 475 }
 476
 477 static void __exit rtc_dev_exit(void)
 478 {
 479         class_interface_unregister(&rtc_dev_interface);
 480         class_destroy(rtc_dev_class);
 481         unregister_chrdev_region(rtc_devt, RTC_DEV_MAX);
 482 }
 483
 484 module_init(rtc_dev_init);
 485 module_exit(rtc_dev_exit);
 486
 487 MODULE_AUTHOR("Alessandro Zummo <a.zummo@towertech.it>");
 488 MODULE_DESCRIPTION("RTC class dev interface");
 489 MODULE_LICENSE("GPL");