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
  65         local_irq_disable();
  66         spin_lock(&rtc->irq_lock);
  67         if (rtc->stop_uie_polling || err) {
  68                 rtc->uie_task_active = 0;
  69         } else if (rtc->oldsecs != tm.tm_sec) {
  70                 num = (tm.tm_sec + 60 - rtc->oldsecs) % 60;
  71                 rtc->oldsecs = tm.tm_sec;
  72                 rtc->uie_timer.expires = jiffies + HZ - (HZ/10);
  73                 rtc->uie_timer_active = 1;
  74                 rtc->uie_task_active = 0;
  75                 add_timer(&rtc->uie_timer);
  76         } else if (schedule_work(&rtc->uie_task) == 0) {
  77                 rtc->uie_task_active = 0;
  78         }
  79         spin_unlock(&rtc->irq_lock);
  80         if (num)
  81                 rtc_update_irq(&rtc->class_dev, num, RTC_UF | RTC_IRQF);
  82         local_irq_enable();
  83 }
  84 static void rtc_uie_timer(unsigned long data)
  85 {
  86         struct rtc_device *rtc = (struct rtc_device *)data;
  87         unsigned long flags;
  88
  89         spin_lock_irqsave(&rtc->irq_lock, flags);
  90         rtc->uie_timer_active = 0;
  91         rtc->uie_task_active = 1;
  92         if ((schedule_work(&rtc->uie_task) == 0))
  93                 rtc->uie_task_active = 0;
  94         spin_unlock_irqrestore(&rtc->irq_lock, flags);
  95 }
  96
  97 static void clear_uie(struct rtc_device *rtc)
  98 {
  99         spin_lock_irq(&rtc->irq_lock);
 100         if (rtc->irq_active) {
 101                 rtc->stop_uie_polling = 1;
 102                 if (rtc->uie_timer_active) {
 103                         spin_unlock_irq(&rtc->irq_lock);
 104                         del_timer_sync(&rtc->uie_timer);
 105                         spin_lock_irq(&rtc->irq_lock);
 106                         rtc->uie_timer_active = 0;
 107                 }
 108                 if (rtc->uie_task_active) {
 109                         spin_unlock_irq(&rtc->irq_lock);
 110                         flush_scheduled_work();
 111                         spin_lock_irq(&rtc->irq_lock);
 112                 }
 113                 rtc->irq_active = 0;
 114         }
 115         spin_unlock_irq(&rtc->irq_lock);
 116 }
 117
 118 static int set_uie(struct rtc_device *rtc)
 119 {
 120         struct rtc_time tm;
 121         int err;
 122
 123         err = rtc_read_time(&rtc->class_dev, &tm);
 124         if (err)
 125                 return err;
 126         spin_lock_irq(&rtc->irq_lock);
 127         if (!rtc->irq_active) {
 128                 rtc->irq_active = 1;
 129                 rtc->stop_uie_polling = 0;
 130                 rtc->oldsecs = tm.tm_sec;
 131                 rtc->uie_task_active = 1;
 132                 if (schedule_work(&rtc->uie_task) == 0)
 133                         rtc->uie_task_active = 0;
 134         }
 135         rtc->irq_data = 0;
 136         spin_unlock_irq(&rtc->irq_lock);
 137         return 0;
 138 }
 139 #endif /* CONFIG_RTC_INTF_DEV_UIE_EMUL */
 140
 141 static ssize_t
 142 rtc_dev_read(struct file *file, char __user *buf, size_t count, loff_t *ppos)
 143 {
 144         struct rtc_device *rtc = to_rtc_device(file->private_data);
 145
 146         DECLARE_WAITQUEUE(wait, current);
 147         unsigned long data;
 148         ssize_t ret;
 149
 150         if (count != sizeof(unsigned int) && count < sizeof(unsigned long))
 151                 return -EINVAL;
 152
 153         add_wait_queue(&rtc->irq_queue, &wait);
 154         do {
 155                 __set_current_state(TASK_INTERRUPTIBLE);
 156
 157                 spin_lock_irq(&rtc->irq_lock);
 158                 data = rtc->irq_data;
 159                 rtc->irq_data = 0;
 160                 spin_unlock_irq(&rtc->irq_lock);
 161
 162                 if (data != 0) {
 163                         ret = 0;
 164                         break;
 165                 }
 166                 if (file->f_flags & O_NONBLOCK) {
 167                         ret = -EAGAIN;
 168                         break;
 169                 }
 170                 if (signal_pending(current)) {
 171                         ret = -ERESTARTSYS;
 172                         break;
 173                 }
 174                 schedule();
 175         } while (1);
 176         set_current_state(TASK_RUNNING);
 177         remove_wait_queue(&rtc->irq_queue, &wait);
 178
 179         if (ret == 0) {
 180                 /* Check for any data updates */
 181                 if (rtc->ops->read_callback)
 182                         data = rtc->ops->read_callback(rtc->class_dev.dev,
 183                                                        data);
 184
 185                 if (sizeof(int) != sizeof(long) &&
 186                     count == sizeof(unsigned int))
 187                         ret = put_user(data, (unsigned int __user *)buf) ?:
 188                                 sizeof(unsigned int);
 189                 else
 190                         ret = put_user(data, (unsigned long __user *)buf) ?:
 191                                 sizeof(unsigned long);
 192         }
 193         return ret;
 194 }
 195
 196 static unsigned int rtc_dev_poll(struct file *file, poll_table *wait)
 197 {
 198         struct rtc_device *rtc = to_rtc_device(file->private_data);
 199         unsigned long data;
 200
 201         poll_wait(file, &rtc->irq_queue, wait);
 202
 203         data = rtc->irq_data;
 204
 205         return (data != 0) ? (POLLIN | POLLRDNORM) : 0;
 206 }
 207
 208 static int rtc_dev_ioctl(struct inode *inode, struct file *file,
 209                 unsigned int cmd, unsigned long arg)
 210 {
 211         int err = 0;
 212         struct class_device *class_dev = file->private_data;
 213         struct rtc_device *rtc = to_rtc_device(class_dev);
 214         const struct rtc_class_ops *ops = rtc->ops;
 215         struct rtc_time tm;
 216         struct rtc_wkalrm alarm;
 217         void __user *uarg = (void __user *) arg;
 218
 219         /* check that the calling task has appropriate permissions
 220          * for certain ioctls. doing this check here is useful
 221          * to avoid duplicate code in each driver.
 222          */
 223         switch (cmd) {
 224         case RTC_EPOCH_SET:
 225         case RTC_SET_TIME:
 226                 if (!capable(CAP_SYS_TIME))
 227                         return -EACCES;
 228                 break;
 229
 230         case RTC_IRQP_SET:
 231                 if (arg > rtc->max_user_freq && !capable(CAP_SYS_RESOURCE))
 232                         return -EACCES;
 233                 break;
 234
 235         case RTC_PIE_ON:
 236                 if (!capable(CAP_SYS_RESOURCE))
 237                         return -EACCES;
 238                 break;
 239         }
 240
 241         /* avoid conflicting IRQ users */
 242         if (cmd == RTC_PIE_ON || cmd == RTC_PIE_OFF || cmd == RTC_IRQP_SET) {
 243                 spin_lock_irq(&rtc->irq_task_lock);
 244                 if (rtc->irq_task)
 245                         err = -EBUSY;
 246                 spin_unlock_irq(&rtc->irq_task_lock);
 247
 248                 if (err < 0)
 249                         return err;
 250         }
 251
 252         /* try the driver's ioctl interface */
 253         if (ops->ioctl) {
 254                 err = ops->ioctl(class_dev->dev, cmd, arg);
 255                 if (err != -ENOIOCTLCMD)
 256                         return err;
 257         }
 258
 259         /* if the driver does not provide the ioctl interface
 260          * or if that particular ioctl was not implemented
 261          * (-ENOIOCTLCMD), we will try to emulate here.
 262          */
 263
 264         switch (cmd) {
 265         case RTC_ALM_READ:
 266                 err = rtc_read_alarm(class_dev, &alarm);
 267                 if (err < 0)
 268                         return err;
 269
 270                 if (copy_to_user(uarg, &alarm.time, sizeof(tm)))
 271                         return -EFAULT;
 272                 break;
 273
 274         case RTC_ALM_SET:
 275                 if (copy_from_user(&alarm.time, uarg, sizeof(tm)))
 276                         return -EFAULT;
 277
 278                 alarm.enabled = 0;
 279                 alarm.pending = 0;
 280                 alarm.time.tm_mday = -1;
 281                 alarm.time.tm_mon = -1;
 282                 alarm.time.tm_year = -1;
 283                 alarm.time.tm_wday = -1;
 284                 alarm.time.tm_yday = -1;
 285                 alarm.time.tm_isdst = -1;
 286                 err = rtc_set_alarm(class_dev, &alarm);
 287                 break;
 288
 289         case RTC_RD_TIME:
 290                 err = rtc_read_time(class_dev, &tm);
 291                 if (err < 0)
 292                         return err;
 293
 294                 if (copy_to_user(uarg, &tm, sizeof(tm)))
 295                         return -EFAULT;
 296                 break;
 297
 298         case RTC_SET_TIME:
 299                 if (copy_from_user(&tm, uarg, sizeof(tm)))
 300                         return -EFAULT;
 301
 302                 err = rtc_set_time(class_dev, &tm);
 303                 break;
 304
 305         case RTC_IRQP_READ:
 306                 if (ops->irq_set_freq)
 307                         err = put_user(rtc->irq_freq, (unsigned long *) arg);
 308                 break;
 309
 310         case RTC_IRQP_SET:
 311                 if (ops->irq_set_freq)
 312                         err = rtc_irq_set_freq(class_dev, rtc->irq_task, arg);
 313                 break;
 314
 315 #if 0
 316         case RTC_EPOCH_SET:
 317 #ifndef rtc_epoch
 318                 /*
 319                  * There were no RTC clocks before 1900.
 320                  */
 321                 if (arg < 1900) {
 322                         err = -EINVAL;
 323                         break;
 324                 }
 325                 rtc_epoch = arg;
 326                 err = 0;
 327 #endif
 328                 break;
 329
 330         case RTC_EPOCH_READ:
 331                 err = put_user(rtc_epoch, (unsigned long __user *)uarg);
 332                 break;
 333 #endif
 334         case RTC_WKALM_SET:
 335                 if (copy_from_user(&alarm, uarg, sizeof(alarm)))
 336                         return -EFAULT;
 337
 338                 err = rtc_set_alarm(class_dev, &alarm);
 339                 break;
 340
 341         case RTC_WKALM_RD:
 342                 err = rtc_read_alarm(class_dev, &alarm);
 343                 if (err < 0)
 344                         return err;
 345
 346                 if (copy_to_user(uarg, &alarm, sizeof(alarm)))
 347                         return -EFAULT;
 348                 break;
 349
 350 #ifdef CONFIG_RTC_INTF_DEV_UIE_EMUL
 351         case RTC_UIE_OFF:
 352                 clear_uie(rtc);
 353                 return 0;
 354
 355         case RTC_UIE_ON:
 356                 return set_uie(rtc);
 357 #endif
 358         default:
 359                 err = -ENOTTY;
 360                 break;
 361         }
 362
 363         return err;
 364 }
 365
 366 static int rtc_dev_release(struct inode *inode, struct file *file)
 367 {
 368         struct rtc_device *rtc = to_rtc_device(file->private_data);
 369
 370 #ifdef CONFIG_RTC_INTF_DEV_UIE_EMUL
 371         clear_uie(rtc);
 372 #endif
 373         if (rtc->ops->release)
 374                 rtc->ops->release(rtc->class_dev.dev);
 375
 376         mutex_unlock(&rtc->char_lock);
 377         return 0;
 378 }
 379
 380 static int rtc_dev_fasync(int fd, struct file *file, int on)
 381 {
 382         struct rtc_device *rtc = to_rtc_device(file->private_data);
 383         return fasync_helper(fd, file, on, &rtc->async_queue);
 384 }
 385
 386 static struct file_operations rtc_dev_fops = {
 387         .owner          = THIS_MODULE,
 388         .llseek         = no_llseek,
 389         .read           = rtc_dev_read,
 390         .poll           = rtc_dev_poll,
 391         .ioctl          = rtc_dev_ioctl,
 392         .open           = rtc_dev_open,
 393         .release        = rtc_dev_release,
 394         .fasync         = rtc_dev_fasync,
 395 };
 396
 397 /* insertion/removal hooks */
 398
 399 static int rtc_dev_add_device(struct class_device *class_dev,
 400                                 struct class_interface *class_intf)
 401 {
 402         int err = 0;
 403         struct rtc_device *rtc = to_rtc_device(class_dev);
 404
 405         if (rtc->id >= RTC_DEV_MAX) {
 406                 dev_err(class_dev->dev, "too many RTCs\n");
 407                 return -EINVAL;
 408         }
 409
 410         mutex_init(&rtc->char_lock);
 411         spin_lock_init(&rtc->irq_lock);
 412         init_waitqueue_head(&rtc->irq_queue);
 413 #ifdef CONFIG_RTC_INTF_DEV_UIE_EMUL
 414         INIT_WORK(&rtc->uie_task, rtc_uie_task, rtc);
 415         setup_timer(&rtc->uie_timer, rtc_uie_timer, (unsigned long)rtc);
 416 #endif
 417
 418         cdev_init(&rtc->char_dev, &rtc_dev_fops);
 419         rtc->char_dev.owner = rtc->owner;
 420
 421         if (cdev_add(&rtc->char_dev, MKDEV(MAJOR(rtc_devt), rtc->id), 1)) {
 422                 dev_err(class_dev->dev,
 423                         "failed to add char device %d:%d\n",
 424                         MAJOR(rtc_devt), rtc->id);
 425                 return -ENODEV;
 426         }
 427
 428         rtc->rtc_dev = class_device_create(rtc_dev_class, NULL,
 429                                                 MKDEV(MAJOR(rtc_devt), rtc->id),
 430                                                 class_dev->dev, "rtc%d", rtc->id);
 431         if (IS_ERR(rtc->rtc_dev)) {
 432                 dev_err(class_dev->dev, "cannot create rtc_dev device\n");
 433                 err = PTR_ERR(rtc->rtc_dev);
 434                 goto err_cdev_del;
 435         }
 436
 437         dev_info(class_dev->dev, "rtc intf: dev (%d:%d)\n",
 438                 MAJOR(rtc->rtc_dev->devt),
 439                 MINOR(rtc->rtc_dev->devt));
 440
 441         return 0;
 442
 443 err_cdev_del:
 444
 445         cdev_del(&rtc->char_dev);
 446         return err;
 447 }
 448
 449 static void rtc_dev_remove_device(struct class_device *class_dev,
 450                                         struct class_interface *class_intf)
 451 {
 452         struct rtc_device *rtc = to_rtc_device(class_dev);
 453
 454         if (rtc->rtc_dev) {
 455                 dev_dbg(class_dev->dev, "removing char %d:%d\n",
 456                         MAJOR(rtc->rtc_dev->devt),
 457                         MINOR(rtc->rtc_dev->devt));
 458
 459                 class_device_unregister(rtc->rtc_dev);
 460                 cdev_del(&rtc->char_dev);
 461         }
 462 }
 463
 464 /* interface registration */
 465
 466 static struct class_interface rtc_dev_interface = {
 467         .add = &rtc_dev_add_device,
 468         .remove = &rtc_dev_remove_device,
 469 };
 470
 471 static int __init rtc_dev_init(void)
 472 {
 473         int err;
 474
 475         rtc_dev_class = class_create(THIS_MODULE, "rtc-dev");
 476         if (IS_ERR(rtc_dev_class))
 477                 return PTR_ERR(rtc_dev_class);
 478
 479         err = alloc_chrdev_region(&rtc_devt, 0, RTC_DEV_MAX, "rtc");
 480         if (err < 0) {
 481                 printk(KERN_ERR "%s: failed to allocate char dev region\n",
 482                         __FILE__);
 483                 goto err_destroy_class;
 484         }
 485
 486         err = rtc_interface_register(&rtc_dev_interface);
 487         if (err < 0) {
 488                 printk(KERN_ERR "%s: failed to register the interface\n",
 489                         __FILE__);
 490                 goto err_unregister_chrdev;
 491         }
 492
 493         return 0;
 494
 495 err_unregister_chrdev:
 496         unregister_chrdev_region(rtc_devt, RTC_DEV_MAX);
 497
 498 err_destroy_class:
 499         class_destroy(rtc_dev_class);
 500
 501         return err;
 502 }
 503
 504 static void __exit rtc_dev_exit(void)
 505 {
 506         class_interface_unregister(&rtc_dev_interface);
 507         class_destroy(rtc_dev_class);
 508         unregister_chrdev_region(rtc_devt, RTC_DEV_MAX);
 509 }
 510
 511 subsys_initcall(rtc_dev_init);
 512 module_exit(rtc_dev_exit);
 513
 514 MODULE_AUTHOR("Alessandro Zummo <a.zummo@towertech.it>");
 515 MODULE_DESCRIPTION("RTC class dev interface");
 516 MODULE_LICENSE("GPL");