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 "rtc-core.h"
  17
  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;
  36
  37         err = ops->open ? ops->open(rtc->dev.parent) : 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, &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, 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, &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->dev.parent,
 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 rtc_device *rtc = file->private_data;
 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(rtc->dev.parent, 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(rtc, &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_wday = -1;
 281                 alarm.time.tm_yday = -1;
 282                 alarm.time.tm_isdst = -1;
 283
 284                 /* RTC_ALM_SET alarms may be up to 24 hours in the future.
 285                  * Rather than expecting every RTC to implement "don't care"
 286                  * for day/month/year fields, just force the alarm to have
 287                  * the right values for those fields.
 288                  *
 289                  * RTC_WKALM_SET should be used instead.  Not only does it
 290                  * eliminate the need for a separate RTC_AIE_ON call, it
 291                  * doesn't have the "alarm 23:59:59 in the future" race.
 292                  *
 293                  * NOTE:  some legacy code may have used invalid fields as
 294                  * wildcards, exposing hardware "periodic alarm" capabilities.
 295                  * Not supported here.
 296                  */
 297                 {
 298                         unsigned long now, then;
 299
 300                         err = rtc_read_time(rtc, &tm);
 301                         if (err < 0)
 302                                 return err;
 303                         rtc_tm_to_time(&tm, &now);
 304
 305                         alarm.time.tm_mday = tm.tm_mday;
 306                         alarm.time.tm_mon = tm.tm_mon;
 307                         alarm.time.tm_year = tm.tm_year;
 308                         err  = rtc_valid_tm(&alarm.time);
 309                         if (err < 0)
 310                                 return err;
 311                         rtc_tm_to_time(&alarm.time, &then);
 312
 313                         /* alarm may need to wrap into tomorrow */
 314                         if (then < now) {
 315                                 rtc_time_to_tm(now + 24 * 60 * 60, &tm);
 316                                 alarm.time.tm_mday = tm.tm_mday;
 317                                 alarm.time.tm_mon = tm.tm_mon;
 318                                 alarm.time.tm_year = tm.tm_year;
 319                         }
 320                 }
 321
 322                 err = rtc_set_alarm(rtc, &alarm);
 323                 break;
 324
 325         case RTC_RD_TIME:
 326                 err = rtc_read_time(rtc, &tm);
 327                 if (err < 0)
 328                         return err;
 329
 330                 if (copy_to_user(uarg, &tm, sizeof(tm)))
 331                         return -EFAULT;
 332                 break;
 333
 334         case RTC_SET_TIME:
 335                 if (copy_from_user(&tm, uarg, sizeof(tm)))
 336                         return -EFAULT;
 337
 338                 err = rtc_set_time(rtc, &tm);
 339                 break;
 340
 341         case RTC_IRQP_READ:
 342                 if (ops->irq_set_freq)
 343                         err = put_user(rtc->irq_freq, (unsigned long __user *)uarg);
 344                 else
 345                         err = -ENOTTY;
 346                 break;
 347
 348         case RTC_IRQP_SET:
 349                 if (ops->irq_set_freq)
 350                         err = rtc_irq_set_freq(rtc, rtc->irq_task, arg);
 351                 else
 352                         err = -ENOTTY;
 353                 break;
 354
 355 #if 0
 356         case RTC_EPOCH_SET:
 357 #ifndef rtc_epoch
 358                 /*
 359                  * There were no RTC clocks before 1900.
 360                  */
 361                 if (arg < 1900) {
 362                         err = -EINVAL;
 363                         break;
 364                 }
 365                 rtc_epoch = arg;
 366                 err = 0;
 367 #endif
 368                 break;
 369
 370         case RTC_EPOCH_READ:
 371                 err = put_user(rtc_epoch, (unsigned long __user *)uarg);
 372                 break;
 373 #endif
 374         case RTC_WKALM_SET:
 375                 if (copy_from_user(&alarm, uarg, sizeof(alarm)))
 376                         return -EFAULT;
 377
 378                 err = rtc_set_alarm(rtc, &alarm);
 379                 break;
 380
 381         case RTC_WKALM_RD:
 382                 err = rtc_read_alarm(rtc, &alarm);
 383                 if (err < 0)
 384                         return err;
 385
 386                 if (copy_to_user(uarg, &alarm, sizeof(alarm)))
 387                         return -EFAULT;
 388                 break;
 389
 390 #ifdef CONFIG_RTC_INTF_DEV_UIE_EMUL
 391         case RTC_UIE_OFF:
 392                 clear_uie(rtc);
 393                 return 0;
 394
 395         case RTC_UIE_ON:
 396                 return set_uie(rtc);
 397 #endif
 398         default:
 399                 err = -ENOTTY;
 400                 break;
 401         }
 402
 403         return err;
 404 }
 405
 406 static int rtc_dev_release(struct inode *inode, struct file *file)
 407 {
 408         struct rtc_device *rtc = to_rtc_device(file->private_data);
 409
 410 #ifdef CONFIG_RTC_INTF_DEV_UIE_EMUL
 411         clear_uie(rtc);
 412 #endif
 413         if (rtc->ops->release)
 414                 rtc->ops->release(rtc->dev.parent);
 415
 416         mutex_unlock(&rtc->char_lock);
 417         return 0;
 418 }
 419
 420 static int rtc_dev_fasync(int fd, struct file *file, int on)
 421 {
 422         struct rtc_device *rtc = to_rtc_device(file->private_data);
 423         return fasync_helper(fd, file, on, &rtc->async_queue);
 424 }
 425
 426 static const struct file_operations rtc_dev_fops = {
 427         .owner          = THIS_MODULE,
 428         .llseek         = no_llseek,
 429         .read           = rtc_dev_read,
 430         .poll           = rtc_dev_poll,
 431         .ioctl          = rtc_dev_ioctl,
 432         .open           = rtc_dev_open,
 433         .release        = rtc_dev_release,
 434         .fasync         = rtc_dev_fasync,
 435 };
 436
 437 /* insertion/removal hooks */
 438
 439 void rtc_dev_prepare(struct rtc_device *rtc)
 440 {
 441         if (!rtc_devt)
 442                 return;
 443
 444         if (rtc->id >= RTC_DEV_MAX) {
 445                 pr_debug("%s: too many RTC devices\n", rtc->name);
 446                 return;
 447         }
 448
 449         rtc->dev.devt = MKDEV(MAJOR(rtc_devt), rtc->id);
 450
 451         mutex_init(&rtc->char_lock);
 452         spin_lock_init(&rtc->irq_lock);
 453         init_waitqueue_head(&rtc->irq_queue);
 454 #ifdef CONFIG_RTC_INTF_DEV_UIE_EMUL
 455         INIT_WORK(&rtc->uie_task, rtc_uie_task);
 456         setup_timer(&rtc->uie_timer, rtc_uie_timer, (unsigned long)rtc);
 457 #endif
 458
 459         cdev_init(&rtc->char_dev, &rtc_dev_fops);
 460         rtc->char_dev.owner = rtc->owner;
 461 }
 462
 463 void rtc_dev_add_device(struct rtc_device *rtc)
 464 {
 465         if (cdev_add(&rtc->char_dev, rtc->dev.devt, 1))
 466                 printk(KERN_WARNING "%s: failed to add char device %d:%d\n",
 467                         rtc->name, MAJOR(rtc_devt), rtc->id);
 468         else
 469                 pr_debug("%s: dev (%d:%d)\n", rtc->name,
 470                         MAJOR(rtc_devt), rtc->id);
 471 }
 472
 473 void rtc_dev_del_device(struct rtc_device *rtc)
 474 {
 475         if (rtc->dev.devt)
 476                 cdev_del(&rtc->char_dev);
 477 }
 478
 479 void __init rtc_dev_init(void)
 480 {
 481         int err;
 482
 483         err = alloc_chrdev_region(&rtc_devt, 0, RTC_DEV_MAX, "rtc");
 484         if (err < 0)
 485                 printk(KERN_ERR "%s: failed to allocate char dev region\n",
 486                         __FILE__);
 487 }
 488
 489 void __exit rtc_dev_exit(void)
 490 {
 491         if (rtc_devt)
 492                 unregister_chrdev_region(rtc_devt, RTC_DEV_MAX);
 493 }