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(struct work_struct *work)
  57 {
  58         struct rtc_device *rtc =
  59                 container_of(work, struct rtc_device, uie_task);
  60         struct rtc_time tm;
  61         int num = 0;
  62         int err;
  63
  64         err = rtc_read_time(&rtc->class_dev, &tm);
  65
  66         local_irq_disable();
  67         spin_lock(&rtc->irq_lock);
  68         if (rtc->stop_uie_polling || err) {
  69                 rtc->uie_task_active = 0;
  70         } else if (rtc->oldsecs != tm.tm_sec) {
  71                 num = (tm.tm_sec + 60 - rtc->oldsecs) % 60;
  72                 rtc->oldsecs = tm.tm_sec;
  73                 rtc->uie_timer.expires = jiffies + HZ - (HZ/10);
  74                 rtc->uie_timer_active = 1;
  75                 rtc->uie_task_active = 0;
  76                 add_timer(&rtc->uie_timer);
  77         } else if (schedule_work(&rtc->uie_task) == 0) {
  78                 rtc->uie_task_active = 0;
  79         }
  80         spin_unlock(&rtc->irq_lock);
  81         if (num)
  82                 rtc_update_irq(&rtc->class_dev, num, RTC_UF | RTC_IRQF);
  83         local_irq_enable();
  84 }
  85 static void rtc_uie_timer(unsigned long data)
  86 {
  87         struct rtc_device *rtc = (struct rtc_device *)data;
  88         unsigned long flags;
  89
  90         spin_lock_irqsave(&rtc->irq_lock, flags);
  91         rtc->uie_timer_active = 0;
  92         rtc->uie_task_active = 1;
  93         if ((schedule_work(&rtc->uie_task) == 0))
  94                 rtc->uie_task_active = 0;
  95         spin_unlock_irqrestore(&rtc->irq_lock, flags);
  96 }
  97
  98 static void clear_uie(struct rtc_device *rtc)
  99 {
 100         spin_lock_irq(&rtc->irq_lock);
 101         if (rtc->irq_active) {
 102                 rtc->stop_uie_polling = 1;
 103                 if (rtc->uie_timer_active) {
 104                         spin_unlock_irq(&rtc->irq_lock);
 105                         del_timer_sync(&rtc->uie_timer);
 106                         spin_lock_irq(&rtc->irq_lock);
 107                         rtc->uie_timer_active = 0;
 108                 }
 109                 if (rtc->uie_task_active) {
 110                         spin_unlock_irq(&rtc->irq_lock);
 111                         flush_scheduled_work();
 112                         spin_lock_irq(&rtc->irq_lock);
 113                 }
 114                 rtc->irq_active = 0;
 115         }
 116         spin_unlock_irq(&rtc->irq_lock);
 117 }
 118
 119 static int set_uie(struct rtc_device *rtc)
 120 {
 121         struct rtc_time tm;
 122         int err;
 123
 124         err = rtc_read_time(&rtc->class_dev, &tm);
 125         if (err)
 126                 return err;
 127         spin_lock_irq(&rtc->irq_lock);
 128         if (!rtc->irq_active) {
 129                 rtc->irq_active = 1;
 130                 rtc->stop_uie_polling = 0;
 131                 rtc->oldsecs = tm.tm_sec;
 132                 rtc->uie_task_active = 1;
 133                 if (schedule_work(&rtc->uie_task) == 0)
 134                         rtc->uie_task_active = 0;
 135         }
 136         rtc->irq_data = 0;
 137         spin_unlock_irq(&rtc->irq_lock);
 138         return 0;
 139 }
 140 #endif /* CONFIG_RTC_INTF_DEV_UIE_EMUL */
 141
 142 static ssize_t
 143 rtc_dev_read(struct file *file, char __user *buf, size_t count, loff_t *ppos)
 144 {
 145         struct rtc_device *rtc = to_rtc_device(file->private_data);
 146
 147         DECLARE_WAITQUEUE(wait, current);
 148         unsigned long data;
 149         ssize_t ret;
 150
 151         if (count != sizeof(unsigned int) && count < sizeof(unsigned long))
 152                 return -EINVAL;
 153
 154         add_wait_queue(&rtc->irq_queue, &wait);
 155         do {
 156                 __set_current_state(TASK_INTERRUPTIBLE);
 157
 158                 spin_lock_irq(&rtc->irq_lock);
 159                 data = rtc->irq_data;
 160                 rtc->irq_data = 0;
 161                 spin_unlock_irq(&rtc->irq_lock);
 162
 163                 if (data != 0) {
 164                         ret = 0;
 165                         break;
 166                 }
 167                 if (file->f_flags & O_NONBLOCK) {
 168                         ret = -EAGAIN;
 169                         break;
 170                 }
 171                 if (signal_pending(current)) {
 172                         ret = -ERESTARTSYS;
 173                         break;
 174                 }
 175                 schedule();
 176         } while (1);
 177         set_current_state(TASK_RUNNING);
 178         remove_wait_queue(&rtc->irq_queue, &wait);
 179
 180         if (ret == 0) {
 181                 /* Check for any data updates */
 182                 if (rtc->ops->read_callback)
 183                         data = rtc->ops->read_callback(rtc->class_dev.dev,
 184                                                        data);
 185
 186                 if (sizeof(int) != sizeof(long) &&
 187                     count == sizeof(unsigned int))
 188                         ret = put_user(data, (unsigned int __user *)buf) ?:
 189                                 sizeof(unsigned int);
 190                 else
 191                         ret = put_user(data, (unsigned long __user *)buf) ?:
 192                                 sizeof(unsigned long);
 193         }
 194         return ret;
 195 }
 196
 197 static unsigned int rtc_dev_poll(struct file *file, poll_table *wait)
 198 {
 199         struct rtc_device *rtc = to_rtc_device(file->private_data);
 200         unsigned long data;
 201
 202         poll_wait(file, &rtc->irq_queue, wait);
 203
 204         data = rtc->irq_data;
 205
 206         return (data != 0) ? (POLLIN | POLLRDNORM) : 0;
 207 }
 208
 209 static int rtc_dev_ioctl(struct inode *inode, struct file *file,
 210                 unsigned int cmd, unsigned long arg)
 211 {
 212         int err = 0;
 213         struct class_device *class_dev = file->private_data;
 214         struct rtc_device *rtc = to_rtc_device(class_dev);
 215         const struct rtc_class_ops *ops = rtc->ops;
 216         struct rtc_time tm;
 217         struct rtc_wkalrm alarm;
 218         void __user *uarg = (void __user *) arg;
 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                         return -EACCES;
 229                 break;
 230
 231         case RTC_IRQP_SET:
 232                 if (arg > rtc->max_user_freq && !capable(CAP_SYS_RESOURCE))
 233                         return -EACCES;
 234                 break;
 235
 236         case RTC_PIE_ON:
 237                 if (!capable(CAP_SYS_RESOURCE))
 238                         return -EACCES;
 239                 break;
 240         }
 241
 242         /* avoid conflicting IRQ users */
 243         if (cmd == RTC_PIE_ON || cmd == RTC_PIE_OFF || cmd == RTC_IRQP_SET) {
 244                 spin_lock_irq(&rtc->irq_task_lock);
 245                 if (rtc->irq_task)
 246                         err = -EBUSY;
 247                 spin_unlock_irq(&rtc->irq_task_lock);
 248
 249                 if (err < 0)
 250                         return err;
 251         }
 252
 253         /* try the driver's ioctl interface */
 254         if (ops->ioctl) {
 255                 err = ops->ioctl(class_dev->dev, cmd, arg);
 256                 if (err != -ENOIOCTLCMD)
 257                         return err;
 258         }
 259
 260         /* if the driver does not provide the ioctl interface
 261          * or if that particular ioctl was not implemented
 262          * (-ENOIOCTLCMD), we will try to emulate here.
 263          */
 264
 265         switch (cmd) {
 266         case RTC_ALM_READ:
 267                 err = rtc_read_alarm(class_dev, &alarm);
 268                 if (err < 0)
 269                         return err;
 270
 271                 if (copy_to_user(uarg, &alarm.time, sizeof(tm)))
 272                         return -EFAULT;
 273                 break;
 274
 275         case RTC_ALM_SET:
 276                 if (copy_from_user(&alarm.time, uarg, sizeof(tm)))
 277                         return -EFAULT;
 278
 279                 alarm.enabled = 0;
 280                 alarm.pending = 0;
 281                 alarm.time.tm_mday = -1;
 282                 alarm.time.tm_mon = -1;
 283                 alarm.time.tm_year = -1;
 284                 alarm.time.tm_wday = -1;
 285                 alarm.time.tm_yday = -1;
 286                 alarm.time.tm_isdst = -1;
 287                 err = rtc_set_alarm(class_dev, &alarm);
 288                 break;
 289
 290         case RTC_RD_TIME:
 291                 err = rtc_read_time(class_dev, &tm);
 292                 if (err < 0)
 293                         return err;
 294
 295                 if (copy_to_user(uarg, &tm, sizeof(tm)))
 296                         return -EFAULT;
 297                 break;
 298
 299         case RTC_SET_TIME:
 300                 if (copy_from_user(&tm, uarg, sizeof(tm)))
 301                         return -EFAULT;
 302
 303                 err = rtc_set_time(class_dev, &tm);
 304                 break;
 305
 306         case RTC_IRQP_READ:
 307                 if (ops->irq_set_freq)
 308                         err = put_user(rtc->irq_freq, (unsigned long __user *)uarg);
 309                 break;
 310
 311         case RTC_IRQP_SET:
 312                 if (ops->irq_set_freq)
 313                         err = rtc_irq_set_freq(class_dev, rtc->irq_task, arg);
 314                 break;
 315
 316 #if 0
 317         case RTC_EPOCH_SET:
 318 #ifndef rtc_epoch
 319                 /*
 320                  * There were no RTC clocks before 1900.
 321                  */
 322                 if (arg < 1900) {
 323                         err = -EINVAL;
 324                         break;
 325                 }
 326                 rtc_epoch = arg;
 327                 err = 0;
 328 #endif
 329                 break;
 330
 331         case RTC_EPOCH_READ:
 332                 err = put_user(rtc_epoch, (unsigned long __user *)uarg);
 333                 break;
 334 #endif
 335         case RTC_WKALM_SET:
 336                 if (copy_from_user(&alarm, uarg, sizeof(alarm)))
 337                         return -EFAULT;
 338
 339                 err = rtc_set_alarm(class_dev, &alarm);
 340                 break;
 341
 342         case RTC_WKALM_RD:
 343                 err = rtc_read_alarm(class_dev, &alarm);
 344                 if (err < 0)
 345                         return err;
 346
 347                 if (copy_to_user(uarg, &alarm, sizeof(alarm)))
 348                         return -EFAULT;
 349                 break;
 350
 351 #ifdef CONFIG_RTC_INTF_DEV_UIE_EMUL
 352         case RTC_UIE_OFF:
 353                 clear_uie(rtc);
 354                 return 0;
 355
 356         case RTC_UIE_ON:
 357                 return set_uie(rtc);
 358 #endif
 359         default:
 360                 err = -ENOTTY;
 361                 break;
 362         }
 363
 364         return err;
 365 }
 366
 367 static int rtc_dev_release(struct inode *inode, struct file *file)
 368 {
 369         struct rtc_device *rtc = to_rtc_device(file->private_data);
 370
 371 #ifdef CONFIG_RTC_INTF_DEV_UIE_EMUL
 372         clear_uie(rtc);
 373 #endif
 374         if (rtc->ops->release)
 375                 rtc->ops->release(rtc->class_dev.dev);
 376
 377         mutex_unlock(&rtc->char_lock);
 378         return 0;
 379 }
 380
 381 static int rtc_dev_fasync(int fd, struct file *file, int on)
 382 {
 383         struct rtc_device *rtc = to_rtc_device(file->private_data);
 384         return fasync_helper(fd, file, on, &rtc->async_queue);
 385 }
 386
 387 static const struct file_operations rtc_dev_fops = {
 388         .owner          = THIS_MODULE,
 389         .llseek         = no_llseek,
 390         .read           = rtc_dev_read,
 391         .poll           = rtc_dev_poll,
 392         .ioctl          = rtc_dev_ioctl,
 393         .open           = rtc_dev_open,
 394         .release        = rtc_dev_release,
 395         .fasync         = rtc_dev_fasync,
 396 };
 397
 398 /* insertion/removal hooks */
 399
 400 static int rtc_dev_add_device(struct class_device *class_dev,
 401                                 struct class_interface *class_intf)
 402 {
 403         int err = 0;
 404         struct rtc_device *rtc = to_rtc_device(class_dev);
 405
 406         if (rtc->id >= RTC_DEV_MAX) {
 407                 dev_err(class_dev->dev, "too many RTCs\n");
 408                 return -EINVAL;
 409         }
 410
 411         mutex_init(&rtc->char_lock);
 412         spin_lock_init(&rtc->irq_lock);
 413         init_waitqueue_head(&rtc->irq_queue);
 414 #ifdef CONFIG_RTC_INTF_DEV_UIE_EMUL
 415         INIT_WORK(&rtc->uie_task, rtc_uie_task);
 416         setup_timer(&rtc->uie_timer, rtc_uie_timer, (unsigned long)rtc);
 417 #endif
 418
 419         cdev_init(&rtc->char_dev, &rtc_dev_fops);
 420         rtc->char_dev.owner = rtc->owner;
 421
 422         if (cdev_add(&rtc->char_dev, MKDEV(MAJOR(rtc_devt), rtc->id), 1)) {
 423                 dev_err(class_dev->dev,
 424                         "failed to add char device %d:%d\n",
 425                         MAJOR(rtc_devt), rtc->id);
 426                 return -ENODEV;
 427         }
 428
 429         rtc->rtc_dev = class_device_create(rtc_dev_class, NULL,
 430                                                 MKDEV(MAJOR(rtc_devt), rtc->id),
 431                                                 class_dev->dev, "rtc%d", rtc->id);
 432         if (IS_ERR(rtc->rtc_dev)) {
 433                 dev_err(class_dev->dev, "cannot create rtc_dev device\n");
 434                 err = PTR_ERR(rtc->rtc_dev);
 435                 goto err_cdev_del;
 436         }
 437
 438         dev_dbg(class_dev->dev, "rtc intf: dev (%d:%d)\n",
 439                 MAJOR(rtc->rtc_dev->devt),
 440                 MINOR(rtc->rtc_dev->devt));
 441
 442         return 0;
 443
 444 err_cdev_del:
 445
 446         cdev_del(&rtc->char_dev);
 447         return err;
 448 }
 449
 450 static void rtc_dev_remove_device(struct class_device *class_dev,
 451                                         struct class_interface *class_intf)
 452 {
 453         struct rtc_device *rtc = to_rtc_device(class_dev);
 454
 455         if (rtc->rtc_dev) {
 456                 dev_dbg(class_dev->dev, "removing char %d:%d\n",
 457                         MAJOR(rtc->rtc_dev->devt),
 458                         MINOR(rtc->rtc_dev->devt));
 459
 460                 class_device_unregister(rtc->rtc_dev);
 461                 cdev_del(&rtc->char_dev);
 462         }
 463 }
 464
 465 /* interface registration */
 466
 467 static struct class_interface rtc_dev_interface = {
 468         .add = &rtc_dev_add_device,
 469         .remove = &rtc_dev_remove_device,
 470 };
 471
 472 static int __init rtc_dev_init(void)
 473 {
 474         int err;
 475
 476         rtc_dev_class = class_create(THIS_MODULE, "rtc-dev");
 477         if (IS_ERR(rtc_dev_class))
 478                 return PTR_ERR(rtc_dev_class);
 479
 480         err = alloc_chrdev_region(&rtc_devt, 0, RTC_DEV_MAX, "rtc");
 481         if (err < 0) {
 482                 printk(KERN_ERR "%s: failed to allocate char dev region\n",
 483                         __FILE__);
 484                 goto err_destroy_class;
 485         }
 486
 487         err = rtc_interface_register(&rtc_dev_interface);
 488         if (err < 0) {
 489                 printk(KERN_ERR "%s: failed to register the interface\n",
 490                         __FILE__);
 491                 goto err_unregister_chrdev;
 492         }
 493
 494         return 0;
 495
 496 err_unregister_chrdev:
 497         unregister_chrdev_region(rtc_devt, RTC_DEV_MAX);
 498
 499 err_destroy_class:
 500         class_destroy(rtc_dev_class);
 501
 502         return err;
 503 }
 504
 505 static void __exit rtc_dev_exit(void)
 506 {
 507         class_interface_unregister(&rtc_dev_interface);
 508         class_destroy(rtc_dev_class);
 509         unregister_chrdev_region(rtc_devt, RTC_DEV_MAX);
 510 }
 511
 512 subsys_initcall(rtc_dev_init);
 513 module_exit(rtc_dev_exit);
 514
 515 MODULE_AUTHOR("Alessandro Zummo <a.zummo@towertech.it>");
 516 MODULE_DESCRIPTION("RTC class dev interface");
 517 MODULE_LICENSE("GPL");