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/sched.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         if (test_and_set_bit_lock(RTC_DEV_BUSY, &rtc->flags))
  31                 return -EBUSY;
  32
  33         file->private_data = rtc;
  34
  35         err = ops->open ? ops->open(rtc->dev.parent) : 0;
  36         if (err == 0) {
  37                 spin_lock_irq(&rtc->irq_lock);
  38                 rtc->irq_data = 0;
  39                 spin_unlock_irq(&rtc->irq_lock);
  40
  41                 return 0;
  42         }
  43
  44         /* something has gone wrong */
  45         clear_bit_unlock(RTC_DEV_BUSY, &rtc->flags);
  46         return err;
  47 }
  48
  49 #ifdef CONFIG_RTC_INTF_DEV_UIE_EMUL
  50 /*
  51  * Routine to poll RTC seconds field for change as often as possible,
  52  * after first RTC_UIE use timer to reduce polling
  53  */
  54 static void rtc_uie_task(struct work_struct *work)
  55 {
  56         struct rtc_device *rtc =
  57                 container_of(work, struct rtc_device, uie_task);
  58         struct rtc_time tm;
  59         int num = 0;
  60         int err;
  61
  62         err = rtc_read_time(rtc, &tm);
  63
  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, num, RTC_UF | RTC_IRQF);
  80 }
  81 static void rtc_uie_timer(unsigned long data)
  82 {
  83         struct rtc_device *rtc = (struct rtc_device *)data;
  84         unsigned long flags;
  85
  86         spin_lock_irqsave(&rtc->irq_lock, flags);
  87         rtc->uie_timer_active = 0;
  88         rtc->uie_task_active = 1;
  89         if ((schedule_work(&rtc->uie_task) == 0))
  90                 rtc->uie_task_active = 0;
  91         spin_unlock_irqrestore(&rtc->irq_lock, flags);
  92 }
  93
  94 static int clear_uie(struct rtc_device *rtc)
  95 {
  96         spin_lock_irq(&rtc->irq_lock);
  97         if (rtc->uie_irq_active) {
  98                 rtc->stop_uie_polling = 1;
  99                 if (rtc->uie_timer_active) {
 100                         spin_unlock_irq(&rtc->irq_lock);
 101                         del_timer_sync(&rtc->uie_timer);
 102                         spin_lock_irq(&rtc->irq_lock);
 103                         rtc->uie_timer_active = 0;
 104                 }
 105                 if (rtc->uie_task_active) {
 106                         spin_unlock_irq(&rtc->irq_lock);
 107                         flush_scheduled_work();
 108                         spin_lock_irq(&rtc->irq_lock);
 109                 }
 110                 rtc->uie_irq_active = 0;
 111         }
 112         spin_unlock_irq(&rtc->irq_lock);
 113         return 0;
 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, &tm);
 122         if (err)
 123                 return err;
 124         spin_lock_irq(&rtc->irq_lock);
 125         if (!rtc->uie_irq_active) {
 126                 rtc->uie_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
 138 int rtc_dev_update_irq_enable_emul(struct rtc_device *rtc, unsigned int enabled)
 139 {
 140         if (enabled)
 141                 return set_uie(rtc);
 142         else
 143                 return clear_uie(rtc);
 144 }
 145 EXPORT_SYMBOL(rtc_dev_update_irq_enable_emul);
 146
 147 #endif /* CONFIG_RTC_INTF_DEV_UIE_EMUL */
 148
 149 static ssize_t
 150 rtc_dev_read(struct file *file, char __user *buf, size_t count, loff_t *ppos)
 151 {
 152         struct rtc_device *rtc = file->private_data;
 153
 154         DECLARE_WAITQUEUE(wait, current);
 155         unsigned long data;
 156         ssize_t ret;
 157
 158         if (count != sizeof(unsigned int) && count < sizeof(unsigned long))
 159                 return -EINVAL;
 160
 161         add_wait_queue(&rtc->irq_queue, &wait);
 162         do {
 163                 __set_current_state(TASK_INTERRUPTIBLE);
 164
 165                 spin_lock_irq(&rtc->irq_lock);
 166                 data = rtc->irq_data;
 167                 rtc->irq_data = 0;
 168                 spin_unlock_irq(&rtc->irq_lock);
 169
 170                 if (data != 0) {
 171                         ret = 0;
 172                         break;
 173                 }
 174                 if (file->f_flags & O_NONBLOCK) {
 175                         ret = -EAGAIN;
 176                         break;
 177                 }
 178                 if (signal_pending(current)) {
 179                         ret = -ERESTARTSYS;
 180                         break;
 181                 }
 182                 schedule();
 183         } while (1);
 184         set_current_state(TASK_RUNNING);
 185         remove_wait_queue(&rtc->irq_queue, &wait);
 186
 187         if (ret == 0) {
 188                 /* Check for any data updates */
 189                 if (rtc->ops->read_callback)
 190                         data = rtc->ops->read_callback(rtc->dev.parent,
 191                                                        data);
 192
 193                 if (sizeof(int) != sizeof(long) &&
 194                     count == sizeof(unsigned int))
 195                         ret = put_user(data, (unsigned int __user *)buf) ?:
 196                                 sizeof(unsigned int);
 197                 else
 198                         ret = put_user(data, (unsigned long __user *)buf) ?:
 199                                 sizeof(unsigned long);
 200         }
 201         return ret;
 202 }
 203
 204 static unsigned int rtc_dev_poll(struct file *file, poll_table *wait)
 205 {
 206         struct rtc_device *rtc = file->private_data;
 207         unsigned long data;
 208
 209         poll_wait(file, &rtc->irq_queue, wait);
 210
 211         data = rtc->irq_data;
 212
 213         return (data != 0) ? (POLLIN | POLLRDNORM) : 0;
 214 }
 215
 216 static long rtc_dev_ioctl(struct file *file,
 217                 unsigned int cmd, unsigned long arg)
 218 {
 219         int err = 0;
 220         struct rtc_device *rtc = file->private_data;
 221         const struct rtc_class_ops *ops = rtc->ops;
 222         struct rtc_time tm;
 223         struct rtc_wkalrm alarm;
 224         void __user *uarg = (void __user *) arg;
 225
 226         err = mutex_lock_interruptible(&rtc->ops_lock);
 227         if (err)
 228                 return err;
 229
 230         /* check that the calling task has appropriate permissions
 231          * for certain ioctls. doing this check here is useful
 232          * to avoid duplicate code in each driver.
 233          */
 234         switch (cmd) {
 235         case RTC_EPOCH_SET:
 236         case RTC_SET_TIME:
 237                 if (!capable(CAP_SYS_TIME))
 238                         err = -EACCES;
 239                 break;
 240
 241         case RTC_IRQP_SET:
 242                 if (arg > rtc->max_user_freq && !capable(CAP_SYS_RESOURCE))
 243                         err = -EACCES;
 244                 break;
 245
 246         case RTC_PIE_ON:
 247                 if (rtc->irq_freq > rtc->max_user_freq &&
 248                                 !capable(CAP_SYS_RESOURCE))
 249                         err = -EACCES;
 250                 break;
 251         }
 252
 253         if (err)
 254                 goto done;
 255
 256         /* try the driver's ioctl interface */
 257         if (ops->ioctl) {
 258                 err = ops->ioctl(rtc->dev.parent, cmd, arg);
 259                 if (err != -ENOIOCTLCMD) {
 260                         mutex_unlock(&rtc->ops_lock);
 261                         return err;
 262                 }
 263         }
 264
 265         /* if the driver does not provide the ioctl interface
 266          * or if that particular ioctl was not implemented
 267          * (-ENOIOCTLCMD), we will try to emulate here.
 268          *
 269          * Drivers *SHOULD NOT* provide ioctl implementations
 270          * for these requests.  Instead, provide methods to
 271          * support the following code, so that the RTC's main
 272          * features are accessible without using ioctls.
 273          *
 274          * RTC and alarm times will be in UTC, by preference,
 275          * but dual-booting with MS-Windows implies RTCs must
 276          * use the local wall clock time.
 277          */
 278
 279         switch (cmd) {
 280         case RTC_ALM_READ:
 281                 mutex_unlock(&rtc->ops_lock);
 282
 283                 err = rtc_read_alarm(rtc, &alarm);
 284                 if (err < 0)
 285                         return err;
 286
 287                 if (copy_to_user(uarg, &alarm.time, sizeof(tm)))
 288                         err = -EFAULT;
 289                 return err;
 290
 291         case RTC_ALM_SET:
 292                 mutex_unlock(&rtc->ops_lock);
 293
 294                 if (copy_from_user(&alarm.time, uarg, sizeof(tm)))
 295                         return -EFAULT;
 296
 297                 alarm.enabled = 0;
 298                 alarm.pending = 0;
 299                 alarm.time.tm_wday = -1;
 300                 alarm.time.tm_yday = -1;
 301                 alarm.time.tm_isdst = -1;
 302
 303                 /* RTC_ALM_SET alarms may be up to 24 hours in the future.
 304                  * Rather than expecting every RTC to implement "don't care"
 305                  * for day/month/year fields, just force the alarm to have
 306                  * the right values for those fields.
 307                  *
 308                  * RTC_WKALM_SET should be used instead.  Not only does it
 309                  * eliminate the need for a separate RTC_AIE_ON call, it
 310                  * doesn't have the "alarm 23:59:59 in the future" race.
 311                  *
 312                  * NOTE:  some legacy code may have used invalid fields as
 313                  * wildcards, exposing hardware "periodic alarm" capabilities.
 314                  * Not supported here.
 315                  */
 316                 {
 317                         unsigned long now, then;
 318
 319                         err = rtc_read_time(rtc, &tm);
 320                         if (err < 0)
 321                                 return err;
 322                         rtc_tm_to_time(&tm, &now);
 323
 324                         alarm.time.tm_mday = tm.tm_mday;
 325                         alarm.time.tm_mon = tm.tm_mon;
 326                         alarm.time.tm_year = tm.tm_year;
 327                         err  = rtc_valid_tm(&alarm.time);
 328                         if (err < 0)
 329                                 return err;
 330                         rtc_tm_to_time(&alarm.time, &then);
 331
 332                         /* alarm may need to wrap into tomorrow */
 333                         if (then < now) {
 334                                 rtc_time_to_tm(now + 24 * 60 * 60, &tm);
 335                                 alarm.time.tm_mday = tm.tm_mday;
 336                                 alarm.time.tm_mon = tm.tm_mon;
 337                                 alarm.time.tm_year = tm.tm_year;
 338                         }
 339                 }
 340
 341                 return rtc_set_alarm(rtc, &alarm);
 342
 343         case RTC_RD_TIME:
 344                 mutex_unlock(&rtc->ops_lock);
 345
 346                 err = rtc_read_time(rtc, &tm);
 347                 if (err < 0)
 348                         return err;
 349
 350                 if (copy_to_user(uarg, &tm, sizeof(tm)))
 351                         err = -EFAULT;
 352                 return err;
 353
 354         case RTC_SET_TIME:
 355                 mutex_unlock(&rtc->ops_lock);
 356
 357                 if (copy_from_user(&tm, uarg, sizeof(tm)))
 358                         return -EFAULT;
 359
 360                 return rtc_set_time(rtc, &tm);
 361
 362         case RTC_PIE_ON:
 363                 err = rtc_irq_set_state(rtc, NULL, 1);
 364                 break;
 365
 366         case RTC_PIE_OFF:
 367                 err = rtc_irq_set_state(rtc, NULL, 0);
 368                 break;
 369
 370         case RTC_AIE_ON:
 371                 mutex_unlock(&rtc->ops_lock);
 372                 return rtc_alarm_irq_enable(rtc, 1);
 373
 374         case RTC_AIE_OFF:
 375                 mutex_unlock(&rtc->ops_lock);
 376                 return rtc_alarm_irq_enable(rtc, 0);
 377
 378         case RTC_UIE_ON:
 379                 mutex_unlock(&rtc->ops_lock);
 380                 return rtc_update_irq_enable(rtc, 1);
 381
 382         case RTC_UIE_OFF:
 383                 mutex_unlock(&rtc->ops_lock);
 384                 return rtc_update_irq_enable(rtc, 0);
 385
 386         case RTC_IRQP_SET:
 387                 err = rtc_irq_set_freq(rtc, NULL, arg);
 388                 break;
 389
 390         case RTC_IRQP_READ:
 391                 err = put_user(rtc->irq_freq, (unsigned long __user *)uarg);
 392                 break;
 393
 394 #if 0
 395         case RTC_EPOCH_SET:
 396 #ifndef rtc_epoch
 397                 /*
 398                  * There were no RTC clocks before 1900.
 399                  */
 400                 if (arg < 1900) {
 401                         err = -EINVAL;
 402                         break;
 403                 }
 404                 rtc_epoch = arg;
 405                 err = 0;
 406 #endif
 407                 break;
 408
 409         case RTC_EPOCH_READ:
 410                 err = put_user(rtc_epoch, (unsigned long __user *)uarg);
 411                 break;
 412 #endif
 413         case RTC_WKALM_SET:
 414                 mutex_unlock(&rtc->ops_lock);
 415                 if (copy_from_user(&alarm, uarg, sizeof(alarm)))
 416                         return -EFAULT;
 417
 418                 return rtc_set_alarm(rtc, &alarm);
 419
 420         case RTC_WKALM_RD:
 421                 mutex_unlock(&rtc->ops_lock);
 422                 err = rtc_read_alarm(rtc, &alarm);
 423                 if (err < 0)
 424                         return err;
 425
 426                 if (copy_to_user(uarg, &alarm, sizeof(alarm)))
 427                         err = -EFAULT;
 428                 return err;
 429
 430         default:
 431                 err = -ENOTTY;
 432                 break;
 433         }
 434
 435 done:
 436         mutex_unlock(&rtc->ops_lock);
 437         return err;
 438 }
 439
 440 static int rtc_dev_fasync(int fd, struct file *file, int on)
 441 {
 442         struct rtc_device *rtc = file->private_data;
 443         return fasync_helper(fd, file, on, &rtc->async_queue);
 444 }
 445
 446 static int rtc_dev_release(struct inode *inode, struct file *file)
 447 {
 448         struct rtc_device *rtc = file->private_data;
 449
 450         /* We shut down the repeating IRQs that userspace enabled,
 451          * since nothing is listening to them.
 452          *  - Update (UIE) ... currently only managed through ioctls
 453          *  - Periodic (PIE) ... also used through rtc_*() interface calls
 454          *
 455          * Leave the alarm alone; it may be set to trigger a system wakeup
 456          * later, or be used by kernel code, and is a one-shot event anyway.
 457          */
 458
 459         /* Keep ioctl until all drivers are converted */
 460         rtc_dev_ioctl(file, RTC_UIE_OFF, 0);
 461         rtc_update_irq_enable(rtc, 0);
 462         rtc_irq_set_state(rtc, NULL, 0);
 463
 464         if (rtc->ops->release)
 465                 rtc->ops->release(rtc->dev.parent);
 466
 467         clear_bit_unlock(RTC_DEV_BUSY, &rtc->flags);
 468         return 0;
 469 }
 470
 471 static const struct file_operations rtc_dev_fops = {
 472         .owner          = THIS_MODULE,
 473         .llseek         = no_llseek,
 474         .read           = rtc_dev_read,
 475         .poll           = rtc_dev_poll,
 476         .unlocked_ioctl = rtc_dev_ioctl,
 477         .open           = rtc_dev_open,
 478         .release        = rtc_dev_release,
 479         .fasync         = rtc_dev_fasync,
 480 };
 481
 482 /* insertion/removal hooks */
 483
 484 void rtc_dev_prepare(struct rtc_device *rtc)
 485 {
 486         if (!rtc_devt)
 487                 return;
 488
 489         if (rtc->id >= RTC_DEV_MAX) {
 490                 pr_debug("%s: too many RTC devices\n", rtc->name);
 491                 return;
 492         }
 493
 494         rtc->dev.devt = MKDEV(MAJOR(rtc_devt), rtc->id);
 495
 496 #ifdef CONFIG_RTC_INTF_DEV_UIE_EMUL
 497         INIT_WORK(&rtc->uie_task, rtc_uie_task);
 498         setup_timer(&rtc->uie_timer, rtc_uie_timer, (unsigned long)rtc);
 499 #endif
 500
 501         cdev_init(&rtc->char_dev, &rtc_dev_fops);
 502         rtc->char_dev.owner = rtc->owner;
 503 }
 504
 505 void rtc_dev_add_device(struct rtc_device *rtc)
 506 {
 507         if (cdev_add(&rtc->char_dev, rtc->dev.devt, 1))
 508                 printk(KERN_WARNING "%s: failed to add char device %d:%d\n",
 509                         rtc->name, MAJOR(rtc_devt), rtc->id);
 510         else
 511                 pr_debug("%s: dev (%d:%d)\n", rtc->name,
 512                         MAJOR(rtc_devt), rtc->id);
 513 }
 514
 515 void rtc_dev_del_device(struct rtc_device *rtc)
 516 {
 517         if (rtc->dev.devt)
 518                 cdev_del(&rtc->char_dev);
 519 }
 520
 521 void __init rtc_dev_init(void)
 522 {
 523         int err;
 524
 525         err = alloc_chrdev_region(&rtc_devt, 0, RTC_DEV_MAX, "rtc");
 526         if (err < 0)
 527                 printk(KERN_ERR "%s: failed to allocate char dev region\n",
 528                         __FILE__);
 529 }
 530
 531 void __exit rtc_dev_exit(void)
 532 {
 533         if (rtc_devt)
 534                 unregister_chrdev_region(rtc_devt, RTC_DEV_MAX);
 535 }