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 long rtc_dev_ioctl(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         err = mutex_lock_interruptible(&rtc->ops_lock);
 223         if (err)
 224                 return -EBUSY;
 225
 226         /* check that the calling task has appropriate permissions
 227          * for certain ioctls. doing this check here is useful
 228          * to avoid duplicate code in each driver.
 229          */
 230         switch (cmd) {
 231         case RTC_EPOCH_SET:
 232         case RTC_SET_TIME:
 233                 if (!capable(CAP_SYS_TIME))
 234                         err = -EACCES;
 235                 break;
 236
 237         case RTC_IRQP_SET:
 238                 if (arg > rtc->max_user_freq && !capable(CAP_SYS_RESOURCE))
 239                         err = -EACCES;
 240                 break;
 241
 242         case RTC_PIE_ON:
 243                 if (rtc->irq_freq > rtc->max_user_freq &&
 244                                 !capable(CAP_SYS_RESOURCE))
 245                         err = -EACCES;
 246                 break;
 247         }
 248
 249         if (err)
 250                 goto done;
 251
 252         /* try the driver's ioctl interface */
 253         if (ops->ioctl) {
 254                 err = ops->ioctl(rtc->dev.parent, cmd, arg);
 255                 if (err != -ENOIOCTLCMD) {
 256                         mutex_unlock(&rtc->ops_lock);
 257                         return err;
 258                 }
 259         }
 260
 261         /* if the driver does not provide the ioctl interface
 262          * or if that particular ioctl was not implemented
 263          * (-ENOIOCTLCMD), we will try to emulate here.
 264          *
 265          * Drivers *SHOULD NOT* provide ioctl implementations
 266          * for these requests.  Instead, provide methods to
 267          * support the following code, so that the RTC's main
 268          * features are accessible without using ioctls.
 269          *
 270          * RTC and alarm times will be in UTC, by preference,
 271          * but dual-booting with MS-Windows implies RTCs must
 272          * use the local wall clock time.
 273          */
 274
 275         switch (cmd) {
 276         case RTC_ALM_READ:
 277                 mutex_unlock(&rtc->ops_lock);
 278
 279                 err = rtc_read_alarm(rtc, &alarm);
 280                 if (err < 0)
 281                         return err;
 282
 283                 if (copy_to_user(uarg, &alarm.time, sizeof(tm)))
 284                         err = -EFAULT;
 285                 return err;
 286
 287         case RTC_ALM_SET:
 288                 mutex_unlock(&rtc->ops_lock);
 289
 290                 if (copy_from_user(&alarm.time, uarg, sizeof(tm)))
 291                         return -EFAULT;
 292
 293                 alarm.enabled = 0;
 294                 alarm.pending = 0;
 295                 alarm.time.tm_wday = -1;
 296                 alarm.time.tm_yday = -1;
 297                 alarm.time.tm_isdst = -1;
 298
 299                 /* RTC_ALM_SET alarms may be up to 24 hours in the future.
 300                  * Rather than expecting every RTC to implement "don't care"
 301                  * for day/month/year fields, just force the alarm to have
 302                  * the right values for those fields.
 303                  *
 304                  * RTC_WKALM_SET should be used instead.  Not only does it
 305                  * eliminate the need for a separate RTC_AIE_ON call, it
 306                  * doesn't have the "alarm 23:59:59 in the future" race.
 307                  *
 308                  * NOTE:  some legacy code may have used invalid fields as
 309                  * wildcards, exposing hardware "periodic alarm" capabilities.
 310                  * Not supported here.
 311                  */
 312                 {
 313                         unsigned long now, then;
 314
 315                         err = rtc_read_time(rtc, &tm);
 316                         if (err < 0)
 317                                 return err;
 318                         rtc_tm_to_time(&tm, &now);
 319
 320                         alarm.time.tm_mday = tm.tm_mday;
 321                         alarm.time.tm_mon = tm.tm_mon;
 322                         alarm.time.tm_year = tm.tm_year;
 323                         err  = rtc_valid_tm(&alarm.time);
 324                         if (err < 0)
 325                                 return err;
 326                         rtc_tm_to_time(&alarm.time, &then);
 327
 328                         /* alarm may need to wrap into tomorrow */
 329                         if (then < now) {
 330                                 rtc_time_to_tm(now + 24 * 60 * 60, &tm);
 331                                 alarm.time.tm_mday = tm.tm_mday;
 332                                 alarm.time.tm_mon = tm.tm_mon;
 333                                 alarm.time.tm_year = tm.tm_year;
 334                         }
 335                 }
 336
 337                 return rtc_set_alarm(rtc, &alarm);
 338
 339         case RTC_RD_TIME:
 340                 mutex_unlock(&rtc->ops_lock);
 341
 342                 err = rtc_read_time(rtc, &tm);
 343                 if (err < 0)
 344                         return err;
 345
 346                 if (copy_to_user(uarg, &tm, sizeof(tm)))
 347                         err = -EFAULT;
 348                 return err;
 349
 350         case RTC_SET_TIME:
 351                 mutex_unlock(&rtc->ops_lock);
 352
 353                 if (copy_from_user(&tm, uarg, sizeof(tm)))
 354                         return -EFAULT;
 355
 356                 return rtc_set_time(rtc, &tm);
 357
 358         case RTC_PIE_ON:
 359                 err = rtc_irq_set_state(rtc, NULL, 1);
 360                 break;
 361
 362         case RTC_PIE_OFF:
 363                 err = rtc_irq_set_state(rtc, NULL, 0);
 364                 break;
 365
 366         case RTC_IRQP_SET:
 367                 err = rtc_irq_set_freq(rtc, NULL, arg);
 368                 break;
 369
 370         case RTC_IRQP_READ:
 371                 err = put_user(rtc->irq_freq, (unsigned long __user *)uarg);
 372                 break;
 373
 374 #if 0
 375         case RTC_EPOCH_SET:
 376 #ifndef rtc_epoch
 377                 /*
 378                  * There were no RTC clocks before 1900.
 379                  */
 380                 if (arg < 1900) {
 381                         err = -EINVAL;
 382                         break;
 383                 }
 384                 rtc_epoch = arg;
 385                 err = 0;
 386 #endif
 387                 break;
 388
 389         case RTC_EPOCH_READ:
 390                 err = put_user(rtc_epoch, (unsigned long __user *)uarg);
 391                 break;
 392 #endif
 393         case RTC_WKALM_SET:
 394                 mutex_unlock(&rtc->ops_lock);
 395                 if (copy_from_user(&alarm, uarg, sizeof(alarm)))
 396                         return -EFAULT;
 397
 398                 return rtc_set_alarm(rtc, &alarm);
 399
 400         case RTC_WKALM_RD:
 401                 mutex_unlock(&rtc->ops_lock);
 402                 err = rtc_read_alarm(rtc, &alarm);
 403                 if (err < 0)
 404                         return err;
 405
 406                 if (copy_to_user(uarg, &alarm, sizeof(alarm)))
 407                         err = -EFAULT;
 408                 return err;
 409
 410 #ifdef CONFIG_RTC_INTF_DEV_UIE_EMUL
 411         case RTC_UIE_OFF:
 412                 clear_uie(rtc);
 413                 break;
 414
 415         case RTC_UIE_ON:
 416                 err = set_uie(rtc);
 417 #endif
 418         default:
 419                 err = -ENOTTY;
 420                 break;
 421         }
 422
 423 done:
 424         mutex_unlock(&rtc->ops_lock);
 425         return err;
 426 }
 427
 428 static int rtc_dev_release(struct inode *inode, struct file *file)
 429 {
 430         struct rtc_device *rtc = file->private_data;
 431
 432 #ifdef CONFIG_RTC_INTF_DEV_UIE_EMUL
 433         clear_uie(rtc);
 434 #endif
 435         if (rtc->ops->release)
 436                 rtc->ops->release(rtc->dev.parent);
 437
 438         clear_bit_unlock(RTC_DEV_BUSY, &rtc->flags);
 439         return 0;
 440 }
 441
 442 static int rtc_dev_fasync(int fd, struct file *file, int on)
 443 {
 444         struct rtc_device *rtc = file->private_data;
 445         return fasync_helper(fd, file, on, &rtc->async_queue);
 446 }
 447
 448 static const struct file_operations rtc_dev_fops = {
 449         .owner          = THIS_MODULE,
 450         .llseek         = no_llseek,
 451         .read           = rtc_dev_read,
 452         .poll           = rtc_dev_poll,
 453         .unlocked_ioctl = rtc_dev_ioctl,
 454         .open           = rtc_dev_open,
 455         .release        = rtc_dev_release,
 456         .fasync         = rtc_dev_fasync,
 457 };
 458
 459 /* insertion/removal hooks */
 460
 461 void rtc_dev_prepare(struct rtc_device *rtc)
 462 {
 463         if (!rtc_devt)
 464                 return;
 465
 466         if (rtc->id >= RTC_DEV_MAX) {
 467                 pr_debug("%s: too many RTC devices\n", rtc->name);
 468                 return;
 469         }
 470
 471         rtc->dev.devt = MKDEV(MAJOR(rtc_devt), rtc->id);
 472
 473 #ifdef CONFIG_RTC_INTF_DEV_UIE_EMUL
 474         INIT_WORK(&rtc->uie_task, rtc_uie_task);
 475         setup_timer(&rtc->uie_timer, rtc_uie_timer, (unsigned long)rtc);
 476 #endif
 477
 478         cdev_init(&rtc->char_dev, &rtc_dev_fops);
 479         rtc->char_dev.owner = rtc->owner;
 480 }
 481
 482 void rtc_dev_add_device(struct rtc_device *rtc)
 483 {
 484         if (cdev_add(&rtc->char_dev, rtc->dev.devt, 1))
 485                 printk(KERN_WARNING "%s: failed to add char device %d:%d\n",
 486                         rtc->name, MAJOR(rtc_devt), rtc->id);
 487         else
 488                 pr_debug("%s: dev (%d:%d)\n", rtc->name,
 489                         MAJOR(rtc_devt), rtc->id);
 490 }
 491
 492 void rtc_dev_del_device(struct rtc_device *rtc)
 493 {
 494         if (rtc->dev.devt)
 495                 cdev_del(&rtc->char_dev);
 496 }
 497
 498 void __init rtc_dev_init(void)
 499 {
 500         int err;
 501
 502         err = alloc_chrdev_region(&rtc_devt, 0, RTC_DEV_MAX, "rtc");
 503         if (err < 0)
 504                 printk(KERN_ERR "%s: failed to allocate char dev region\n",
 505                         __FILE__);
 506 }
 507
 508 void __exit rtc_dev_exit(void)
 509 {
 510         if (rtc_devt)
 511                 unregister_chrdev_region(rtc_devt, RTC_DEV_MAX);
 512 }