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 <linux/smp_lock.h>
  17 #include "rtc-core.h"
  18
  19 static dev_t rtc_devt;
  20
  21 #define RTC_DEV_MAX 16 /* 16 RTCs should be enough for everyone... */
  22
  23 static int rtc_dev_open(struct inode *inode, struct file *file)
  24 {
  25         int err;
  26         struct rtc_device *rtc = container_of(inode->i_cdev,
  27                                         struct rtc_device, char_dev);
  28         const struct rtc_class_ops *ops = rtc->ops;
  29
  30         lock_kernel();
  31         if (test_and_set_bit_lock(RTC_DEV_BUSY, &rtc->flags)) {
  32                 err = -EBUSY;
  33                 goto out;
  34         }
  35
  36         file->private_data = rtc;
  37
  38         err = ops->open ? ops->open(rtc->dev.parent) : 0;
  39         if (err == 0) {
  40                 spin_lock_irq(&rtc->irq_lock);
  41                 rtc->irq_data = 0;
  42                 spin_unlock_irq(&rtc->irq_lock);
  43
  44                 goto out;
  45         }
  46
  47         /* something has gone wrong */
  48         clear_bit_unlock(RTC_DEV_BUSY, &rtc->flags);
  49 out:
  50         unlock_kernel();
  51         return err;
  52 }
  53
  54 #ifdef CONFIG_RTC_INTF_DEV_UIE_EMUL
  55 /*
  56  * Routine to poll RTC seconds field for change as often as possible,
  57  * after first RTC_UIE use timer to reduce polling
  58  */
  59 static void rtc_uie_task(struct work_struct *work)
  60 {
  61         struct rtc_device *rtc =
  62                 container_of(work, struct rtc_device, uie_task);
  63         struct rtc_time tm;
  64         int num = 0;
  65         int err;
  66
  67         err = rtc_read_time(rtc, &tm);
  68
  69         local_irq_disable();
  70         spin_lock(&rtc->irq_lock);
  71         if (rtc->stop_uie_polling || err) {
  72                 rtc->uie_task_active = 0;
  73         } else if (rtc->oldsecs != tm.tm_sec) {
  74                 num = (tm.tm_sec + 60 - rtc->oldsecs) % 60;
  75                 rtc->oldsecs = tm.tm_sec;
  76                 rtc->uie_timer.expires = jiffies + HZ - (HZ/10);
  77                 rtc->uie_timer_active = 1;
  78                 rtc->uie_task_active = 0;
  79                 add_timer(&rtc->uie_timer);
  80         } else if (schedule_work(&rtc->uie_task) == 0) {
  81                 rtc->uie_task_active = 0;
  82         }
  83         spin_unlock(&rtc->irq_lock);
  84         if (num)
  85                 rtc_update_irq(rtc, num, RTC_UF | RTC_IRQF);
  86         local_irq_enable();
  87 }
  88 static void rtc_uie_timer(unsigned long data)
  89 {
  90         struct rtc_device *rtc = (struct rtc_device *)data;
  91         unsigned long flags;
  92
  93         spin_lock_irqsave(&rtc->irq_lock, flags);
  94         rtc->uie_timer_active = 0;
  95         rtc->uie_task_active = 1;
  96         if ((schedule_work(&rtc->uie_task) == 0))
  97                 rtc->uie_task_active = 0;
  98         spin_unlock_irqrestore(&rtc->irq_lock, flags);
  99 }
 100
 101 static void clear_uie(struct rtc_device *rtc)
 102 {
 103         spin_lock_irq(&rtc->irq_lock);
 104         if (rtc->irq_active) {
 105                 rtc->stop_uie_polling = 1;
 106                 if (rtc->uie_timer_active) {
 107                         spin_unlock_irq(&rtc->irq_lock);
 108                         del_timer_sync(&rtc->uie_timer);
 109                         spin_lock_irq(&rtc->irq_lock);
 110                         rtc->uie_timer_active = 0;
 111                 }
 112                 if (rtc->uie_task_active) {
 113                         spin_unlock_irq(&rtc->irq_lock);
 114                         flush_scheduled_work();
 115                         spin_lock_irq(&rtc->irq_lock);
 116                 }
 117                 rtc->irq_active = 0;
 118         }
 119         spin_unlock_irq(&rtc->irq_lock);
 120 }
 121
 122 static int set_uie(struct rtc_device *rtc)
 123 {
 124         struct rtc_time tm;
 125         int err;
 126
 127         err = rtc_read_time(rtc, &tm);
 128         if (err)
 129                 return err;
 130         spin_lock_irq(&rtc->irq_lock);
 131         if (!rtc->irq_active) {
 132                 rtc->irq_active = 1;
 133                 rtc->stop_uie_polling = 0;
 134                 rtc->oldsecs = tm.tm_sec;
 135                 rtc->uie_task_active = 1;
 136                 if (schedule_work(&rtc->uie_task) == 0)
 137                         rtc->uie_task_active = 0;
 138         }
 139         rtc->irq_data = 0;
 140         spin_unlock_irq(&rtc->irq_lock);
 141         return 0;
 142 }
 143 #endif /* CONFIG_RTC_INTF_DEV_UIE_EMUL */
 144
 145 static ssize_t
 146 rtc_dev_read(struct file *file, char __user *buf, size_t count, loff_t *ppos)
 147 {
 148         struct rtc_device *rtc = file->private_data;
 149
 150         DECLARE_WAITQUEUE(wait, current);
 151         unsigned long data;
 152         ssize_t ret;
 153
 154         if (count != sizeof(unsigned int) && count < sizeof(unsigned long))
 155                 return -EINVAL;
 156
 157         add_wait_queue(&rtc->irq_queue, &wait);
 158         do {
 159                 __set_current_state(TASK_INTERRUPTIBLE);
 160
 161                 spin_lock_irq(&rtc->irq_lock);
 162                 data = rtc->irq_data;
 163                 rtc->irq_data = 0;
 164                 spin_unlock_irq(&rtc->irq_lock);
 165
 166                 if (data != 0) {
 167                         ret = 0;
 168                         break;
 169                 }
 170                 if (file->f_flags & O_NONBLOCK) {
 171                         ret = -EAGAIN;
 172                         break;
 173                 }
 174                 if (signal_pending(current)) {
 175                         ret = -ERESTARTSYS;
 176                         break;
 177                 }
 178                 schedule();
 179         } while (1);
 180         set_current_state(TASK_RUNNING);
 181         remove_wait_queue(&rtc->irq_queue, &wait);
 182
 183         if (ret == 0) {
 184                 /* Check for any data updates */
 185                 if (rtc->ops->read_callback)
 186                         data = rtc->ops->read_callback(rtc->dev.parent,
 187                                                        data);
 188
 189                 if (sizeof(int) != sizeof(long) &&
 190                     count == sizeof(unsigned int))
 191                         ret = put_user(data, (unsigned int __user *)buf) ?:
 192                                 sizeof(unsigned int);
 193                 else
 194                         ret = put_user(data, (unsigned long __user *)buf) ?:
 195                                 sizeof(unsigned long);
 196         }
 197         return ret;
 198 }
 199
 200 static unsigned int rtc_dev_poll(struct file *file, poll_table *wait)
 201 {
 202         struct rtc_device *rtc = file->private_data;
 203         unsigned long data;
 204
 205         poll_wait(file, &rtc->irq_queue, wait);
 206
 207         data = rtc->irq_data;
 208
 209         return (data != 0) ? (POLLIN | POLLRDNORM) : 0;
 210 }
 211
 212 static int rtc_dev_ioctl(struct inode *inode, struct file *file,
 213                 unsigned int cmd, unsigned long arg)
 214 {
 215         int err = 0;
 216         struct rtc_device *rtc = file->private_data;
 217         const struct rtc_class_ops *ops = rtc->ops;
 218         struct rtc_time tm;
 219         struct rtc_wkalrm alarm;
 220         void __user *uarg = (void __user *) arg;
 221
 222         /* check that the calling task has appropriate permissions
 223          * for certain ioctls. doing this check here is useful
 224          * to avoid duplicate code in each driver.
 225          */
 226         switch (cmd) {
 227         case RTC_EPOCH_SET:
 228         case RTC_SET_TIME:
 229                 if (!capable(CAP_SYS_TIME))
 230                         return -EACCES;
 231                 break;
 232
 233         case RTC_IRQP_SET:
 234                 if (arg > rtc->max_user_freq && !capable(CAP_SYS_RESOURCE))
 235                         return -EACCES;
 236                 break;
 237
 238         case RTC_PIE_ON:
 239                 if (rtc->irq_freq > rtc->max_user_freq &&
 240                                 !capable(CAP_SYS_RESOURCE))
 241                         return -EACCES;
 242                 break;
 243         }
 244
 245         /* try the driver's ioctl interface */
 246         if (ops->ioctl) {
 247                 err = ops->ioctl(rtc->dev.parent, cmd, arg);
 248                 if (err != -ENOIOCTLCMD)
 249                         return err;
 250         }
 251
 252         /* if the driver does not provide the ioctl interface
 253          * or if that particular ioctl was not implemented
 254          * (-ENOIOCTLCMD), we will try to emulate here.
 255          *
 256          * Drivers *SHOULD NOT* provide ioctl implementations
 257          * for these requests.  Instead, provide methods to
 258          * support the following code, so that the RTC's main
 259          * features are accessible without using ioctls.
 260          *
 261          * RTC and alarm times will be in UTC, by preference,
 262          * but dual-booting with MS-Windows implies RTCs must
 263          * use the local wall clock time.
 264          */
 265
 266         switch (cmd) {
 267         case RTC_ALM_READ:
 268                 err = rtc_read_alarm(rtc, &alarm);
 269                 if (err < 0)
 270                         return err;
 271
 272                 if (copy_to_user(uarg, &alarm.time, sizeof(tm)))
 273                         return -EFAULT;
 274                 break;
 275
 276         case RTC_ALM_SET:
 277                 if (copy_from_user(&alarm.time, uarg, sizeof(tm)))
 278                         return -EFAULT;
 279
 280                 alarm.enabled = 0;
 281                 alarm.pending = 0;
 282                 alarm.time.tm_wday = -1;
 283                 alarm.time.tm_yday = -1;
 284                 alarm.time.tm_isdst = -1;
 285
 286                 /* RTC_ALM_SET alarms may be up to 24 hours in the future.
 287                  * Rather than expecting every RTC to implement "don't care"
 288                  * for day/month/year fields, just force the alarm to have
 289                  * the right values for those fields.
 290                  *
 291                  * RTC_WKALM_SET should be used instead.  Not only does it
 292                  * eliminate the need for a separate RTC_AIE_ON call, it
 293                  * doesn't have the "alarm 23:59:59 in the future" race.
 294                  *
 295                  * NOTE:  some legacy code may have used invalid fields as
 296                  * wildcards, exposing hardware "periodic alarm" capabilities.
 297                  * Not supported here.
 298                  */
 299                 {
 300                         unsigned long now, then;
 301
 302                         err = rtc_read_time(rtc, &tm);
 303                         if (err < 0)
 304                                 return err;
 305                         rtc_tm_to_time(&tm, &now);
 306
 307                         alarm.time.tm_mday = tm.tm_mday;
 308                         alarm.time.tm_mon = tm.tm_mon;
 309                         alarm.time.tm_year = tm.tm_year;
 310                         err  = rtc_valid_tm(&alarm.time);
 311                         if (err < 0)
 312                                 return err;
 313                         rtc_tm_to_time(&alarm.time, &then);
 314
 315                         /* alarm may need to wrap into tomorrow */
 316                         if (then < now) {
 317                                 rtc_time_to_tm(now + 24 * 60 * 60, &tm);
 318                                 alarm.time.tm_mday = tm.tm_mday;
 319                                 alarm.time.tm_mon = tm.tm_mon;
 320                                 alarm.time.tm_year = tm.tm_year;
 321                         }
 322                 }
 323
 324                 err = rtc_set_alarm(rtc, &alarm);
 325                 break;
 326
 327         case RTC_RD_TIME:
 328                 err = rtc_read_time(rtc, &tm);
 329                 if (err < 0)
 330                         return err;
 331
 332                 if (copy_to_user(uarg, &tm, sizeof(tm)))
 333                         return -EFAULT;
 334                 break;
 335
 336         case RTC_SET_TIME:
 337                 if (copy_from_user(&tm, uarg, sizeof(tm)))
 338                         return -EFAULT;
 339
 340                 err = rtc_set_time(rtc, &tm);
 341                 break;
 342
 343         case RTC_PIE_ON:
 344                 err = rtc_irq_set_state(rtc, NULL, 1);
 345                 break;
 346
 347         case RTC_PIE_OFF:
 348                 err = rtc_irq_set_state(rtc, NULL, 0);
 349                 break;
 350
 351         case RTC_IRQP_SET:
 352                 err = rtc_irq_set_freq(rtc, NULL, arg);
 353                 break;
 354
 355         case RTC_IRQP_READ:
 356                 err = put_user(rtc->irq_freq, (unsigned long __user *)uarg);
 357                 break;
 358
 359 #if 0
 360         case RTC_EPOCH_SET:
 361 #ifndef rtc_epoch
 362                 /*
 363                  * There were no RTC clocks before 1900.
 364                  */
 365                 if (arg < 1900) {
 366                         err = -EINVAL;
 367                         break;
 368                 }
 369                 rtc_epoch = arg;
 370                 err = 0;
 371 #endif
 372                 break;
 373
 374         case RTC_EPOCH_READ:
 375                 err = put_user(rtc_epoch, (unsigned long __user *)uarg);
 376                 break;
 377 #endif
 378         case RTC_WKALM_SET:
 379                 if (copy_from_user(&alarm, uarg, sizeof(alarm)))
 380                         return -EFAULT;
 381
 382                 err = rtc_set_alarm(rtc, &alarm);
 383                 break;
 384
 385         case RTC_WKALM_RD:
 386                 err = rtc_read_alarm(rtc, &alarm);
 387                 if (err < 0)
 388                         return err;
 389
 390                 if (copy_to_user(uarg, &alarm, sizeof(alarm)))
 391                         return -EFAULT;
 392                 break;
 393
 394 #ifdef CONFIG_RTC_INTF_DEV_UIE_EMUL
 395         case RTC_UIE_OFF:
 396                 clear_uie(rtc);
 397                 return 0;
 398
 399         case RTC_UIE_ON:
 400                 return set_uie(rtc);
 401 #endif
 402         default:
 403                 err = -ENOTTY;
 404                 break;
 405         }
 406
 407         return err;
 408 }
 409
 410 static int rtc_dev_release(struct inode *inode, struct file *file)
 411 {
 412         struct rtc_device *rtc = file->private_data;
 413
 414 #ifdef CONFIG_RTC_INTF_DEV_UIE_EMUL
 415         clear_uie(rtc);
 416 #endif
 417         if (rtc->ops->release)
 418                 rtc->ops->release(rtc->dev.parent);
 419
 420         clear_bit_unlock(RTC_DEV_BUSY, &rtc->flags);
 421         return 0;
 422 }
 423
 424 static int rtc_dev_fasync(int fd, struct file *file, int on)
 425 {
 426         struct rtc_device *rtc = file->private_data;
 427         return fasync_helper(fd, file, on, &rtc->async_queue);
 428 }
 429
 430 static const struct file_operations rtc_dev_fops = {
 431         .owner          = THIS_MODULE,
 432         .llseek         = no_llseek,
 433         .read           = rtc_dev_read,
 434         .poll           = rtc_dev_poll,
 435         .ioctl          = rtc_dev_ioctl,
 436         .open           = rtc_dev_open,
 437         .release        = rtc_dev_release,
 438         .fasync         = rtc_dev_fasync,
 439 };
 440
 441 /* insertion/removal hooks */
 442
 443 void rtc_dev_prepare(struct rtc_device *rtc)
 444 {
 445         if (!rtc_devt)
 446                 return;
 447
 448         if (rtc->id >= RTC_DEV_MAX) {
 449                 pr_debug("%s: too many RTC devices\n", rtc->name);
 450                 return;
 451         }
 452
 453         rtc->dev.devt = MKDEV(MAJOR(rtc_devt), rtc->id);
 454
 455 #ifdef CONFIG_RTC_INTF_DEV_UIE_EMUL
 456         INIT_WORK(&rtc->uie_task, rtc_uie_task);
 457         setup_timer(&rtc->uie_timer, rtc_uie_timer, (unsigned long)rtc);
 458 #endif
 459
 460         cdev_init(&rtc->char_dev, &rtc_dev_fops);
 461         rtc->char_dev.owner = rtc->owner;
 462 }
 463
 464 void rtc_dev_add_device(struct rtc_device *rtc)
 465 {
 466         if (cdev_add(&rtc->char_dev, rtc->dev.devt, 1))
 467                 printk(KERN_WARNING "%s: failed to add char device %d:%d\n",
 468                         rtc->name, MAJOR(rtc_devt), rtc->id);
 469         else
 470                 pr_debug("%s: dev (%d:%d)\n", rtc->name,
 471                         MAJOR(rtc_devt), rtc->id);
 472 }
 473
 474 void rtc_dev_del_device(struct rtc_device *rtc)
 475 {
 476         if (rtc->dev.devt)
 477                 cdev_del(&rtc->char_dev);
 478 }
 479
 480 void __init rtc_dev_init(void)
 481 {
 482         int err;
 483
 484         err = alloc_chrdev_region(&rtc_devt, 0, RTC_DEV_MAX, "rtc");
 485         if (err < 0)
 486                 printk(KERN_ERR "%s: failed to allocate char dev region\n",
 487                         __FILE__);
 488 }
 489
 490 void __exit rtc_dev_exit(void)
 491 {
 492         if (rtc_devt)
 493                 unregister_chrdev_region(rtc_devt, RTC_DEV_MAX);
 494 }