drivers/rtc/dev.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * RTC subsystem, dev interface
   4  *
   5  * Copyright (C) 2005 Tower Technologies
   6  * Author: Alessandro Zummo <a.zummo@towertech.it>
   7  *
   8  * based on arch/arm/common/rtctime.c
   9  */
  10
  11 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  12
  13 #include <linux/compat.h>
  14 #include <linux/module.h>
  15 #include <linux/rtc.h>
  16 #include <linux/sched/signal.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         struct rtc_device *rtc = container_of(inode->i_cdev,
  26                                         struct rtc_device, char_dev);
  27
  28         if (test_and_set_bit_lock(RTC_DEV_BUSY, &rtc->flags))
  29                 return -EBUSY;
  30
  31         file->private_data = rtc;
  32
  33         spin_lock_irq(&rtc->irq_lock);
  34         rtc->irq_data = 0;
  35         spin_unlock_irq(&rtc->irq_lock);
  36
  37         return 0;
  38 }
  39
  40 #ifdef CONFIG_RTC_INTF_DEV_UIE_EMUL
  41 /*
  42  * Routine to poll RTC seconds field for change as often as possible,
  43  * after first RTC_UIE use timer to reduce polling
  44  */
  45 static void rtc_uie_task(struct work_struct *work)
  46 {
  47         struct rtc_device *rtc =
  48                 container_of(work, struct rtc_device, uie_task);
  49         struct rtc_time tm;
  50         int num = 0;
  51         int err;
  52
  53         err = rtc_read_time(rtc, &tm);
  54
  55         spin_lock_irq(&rtc->irq_lock);
  56         if (rtc->stop_uie_polling || err) {
  57                 rtc->uie_task_active = 0;
  58         } else if (rtc->oldsecs != tm.tm_sec) {
  59                 num = (tm.tm_sec + 60 - rtc->oldsecs) % 60;
  60                 rtc->oldsecs = tm.tm_sec;
  61                 rtc->uie_timer.expires = jiffies + HZ - (HZ / 10);
  62                 rtc->uie_timer_active = 1;
  63                 rtc->uie_task_active = 0;
  64                 add_timer(&rtc->uie_timer);
  65         } else if (schedule_work(&rtc->uie_task) == 0) {
  66                 rtc->uie_task_active = 0;
  67         }
  68         spin_unlock_irq(&rtc->irq_lock);
  69         if (num)
  70                 rtc_handle_legacy_irq(rtc, num, RTC_UF);
  71 }
  72
  73 static void rtc_uie_timer(struct timer_list *t)
  74 {
  75         struct rtc_device *rtc = from_timer(rtc, t, uie_timer);
  76         unsigned long flags;
  77
  78         spin_lock_irqsave(&rtc->irq_lock, flags);
  79         rtc->uie_timer_active = 0;
  80         rtc->uie_task_active = 1;
  81         if ((schedule_work(&rtc->uie_task) == 0))
  82                 rtc->uie_task_active = 0;
  83         spin_unlock_irqrestore(&rtc->irq_lock, flags);
  84 }
  85
  86 static int clear_uie(struct rtc_device *rtc)
  87 {
  88         spin_lock_irq(&rtc->irq_lock);
  89         if (rtc->uie_irq_active) {
  90                 rtc->stop_uie_polling = 1;
  91                 if (rtc->uie_timer_active) {
  92                         spin_unlock_irq(&rtc->irq_lock);
  93                         del_timer_sync(&rtc->uie_timer);
  94                         spin_lock_irq(&rtc->irq_lock);
  95                         rtc->uie_timer_active = 0;
  96                 }
  97                 if (rtc->uie_task_active) {
  98                         spin_unlock_irq(&rtc->irq_lock);
  99                         flush_scheduled_work();
 100                         spin_lock_irq(&rtc->irq_lock);
 101                 }
 102                 rtc->uie_irq_active = 0;
 103         }
 104         spin_unlock_irq(&rtc->irq_lock);
 105         return 0;
 106 }
 107
 108 static int set_uie(struct rtc_device *rtc)
 109 {
 110         struct rtc_time tm;
 111         int err;
 112
 113         err = rtc_read_time(rtc, &tm);
 114         if (err)
 115                 return err;
 116         spin_lock_irq(&rtc->irq_lock);
 117         if (!rtc->uie_irq_active) {
 118                 rtc->uie_irq_active = 1;
 119                 rtc->stop_uie_polling = 0;
 120                 rtc->oldsecs = tm.tm_sec;
 121                 rtc->uie_task_active = 1;
 122                 if (schedule_work(&rtc->uie_task) == 0)
 123                         rtc->uie_task_active = 0;
 124         }
 125         rtc->irq_data = 0;
 126         spin_unlock_irq(&rtc->irq_lock);
 127         return 0;
 128 }
 129
 130 int rtc_dev_update_irq_enable_emul(struct rtc_device *rtc, unsigned int enabled)
 131 {
 132         if (enabled)
 133                 return set_uie(rtc);
 134         else
 135                 return clear_uie(rtc);
 136 }
 137 EXPORT_SYMBOL(rtc_dev_update_irq_enable_emul);
 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 = 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                 if (sizeof(int) != sizeof(long) &&
 181                     count == sizeof(unsigned int))
 182                         ret = put_user(data, (unsigned int __user *)buf) ?:
 183                                 sizeof(unsigned int);
 184                 else
 185                         ret = put_user(data, (unsigned long __user *)buf) ?:
 186                                 sizeof(unsigned long);
 187         }
 188         return ret;
 189 }
 190
 191 static __poll_t rtc_dev_poll(struct file *file, poll_table *wait)
 192 {
 193         struct rtc_device *rtc = file->private_data;
 194         unsigned long data;
 195
 196         poll_wait(file, &rtc->irq_queue, wait);
 197
 198         data = rtc->irq_data;
 199
 200         return (data != 0) ? (EPOLLIN | EPOLLRDNORM) : 0;
 201 }
 202
 203 static long rtc_dev_ioctl(struct file *file,
 204                           unsigned int cmd, unsigned long arg)
 205 {
 206         int err = 0;
 207         struct rtc_device *rtc = file->private_data;
 208         const struct rtc_class_ops *ops = rtc->ops;
 209         struct rtc_time tm;
 210         struct rtc_wkalrm alarm;
 211         struct rtc_param param;
 212         void __user *uarg = (void __user *)arg;
 213
 214         err = mutex_lock_interruptible(&rtc->ops_lock);
 215         if (err)
 216                 return err;
 217
 218         /* check that the calling task has appropriate permissions
 219          * for certain ioctls. doing this check here is useful
 220          * to avoid duplicate code in each driver.
 221          */
 222         switch (cmd) {
 223         case RTC_EPOCH_SET:
 224         case RTC_SET_TIME:
 225         case RTC_PARAM_SET:
 226                 if (!capable(CAP_SYS_TIME))
 227                         err = -EACCES;
 228                 break;
 229
 230         case RTC_IRQP_SET:
 231                 if (arg > rtc->max_user_freq && !capable(CAP_SYS_RESOURCE))
 232                         err = -EACCES;
 233                 break;
 234
 235         case RTC_PIE_ON:
 236                 if (rtc->irq_freq > rtc->max_user_freq &&
 237                     !capable(CAP_SYS_RESOURCE))
 238                         err = -EACCES;
 239                 break;
 240         }
 241
 242         if (err)
 243                 goto done;
 244
 245         /*
 246          * Drivers *SHOULD NOT* provide ioctl implementations
 247          * for these requests.  Instead, provide methods to
 248          * support the following code, so that the RTC's main
 249          * features are accessible without using ioctls.
 250          *
 251          * RTC and alarm times will be in UTC, by preference,
 252          * but dual-booting with MS-Windows implies RTCs must
 253          * use the local wall clock time.
 254          */
 255
 256         switch (cmd) {
 257         case RTC_ALM_READ:
 258                 mutex_unlock(&rtc->ops_lock);
 259
 260                 err = rtc_read_alarm(rtc, &alarm);
 261                 if (err < 0)
 262                         return err;
 263
 264                 if (copy_to_user(uarg, &alarm.time, sizeof(tm)))
 265                         err = -EFAULT;
 266                 return err;
 267
 268         case RTC_ALM_SET:
 269                 mutex_unlock(&rtc->ops_lock);
 270
 271                 if (copy_from_user(&alarm.time, uarg, sizeof(tm)))
 272                         return -EFAULT;
 273
 274                 alarm.enabled = 0;
 275                 alarm.pending = 0;
 276                 alarm.time.tm_wday = -1;
 277                 alarm.time.tm_yday = -1;
 278                 alarm.time.tm_isdst = -1;
 279
 280                 /* RTC_ALM_SET alarms may be up to 24 hours in the future.
 281                  * Rather than expecting every RTC to implement "don't care"
 282                  * for day/month/year fields, just force the alarm to have
 283                  * the right values for those fields.
 284                  *
 285                  * RTC_WKALM_SET should be used instead.  Not only does it
 286                  * eliminate the need for a separate RTC_AIE_ON call, it
 287                  * doesn't have the "alarm 23:59:59 in the future" race.
 288                  *
 289                  * NOTE:  some legacy code may have used invalid fields as
 290                  * wildcards, exposing hardware "periodic alarm" capabilities.
 291                  * Not supported here.
 292                  */
 293                 {
 294                         time64_t now, then;
 295
 296                         err = rtc_read_time(rtc, &tm);
 297                         if (err < 0)
 298                                 return err;
 299                         now = rtc_tm_to_time64(&tm);
 300
 301                         alarm.time.tm_mday = tm.tm_mday;
 302                         alarm.time.tm_mon = tm.tm_mon;
 303                         alarm.time.tm_year = tm.tm_year;
 304                         err  = rtc_valid_tm(&alarm.time);
 305                         if (err < 0)
 306                                 return err;
 307                         then = rtc_tm_to_time64(&alarm.time);
 308
 309                         /* alarm may need to wrap into tomorrow */
 310                         if (then < now) {
 311                                 rtc_time64_to_tm(now + 24 * 60 * 60, &tm);
 312                                 alarm.time.tm_mday = tm.tm_mday;
 313                                 alarm.time.tm_mon = tm.tm_mon;
 314                                 alarm.time.tm_year = tm.tm_year;
 315                         }
 316                 }
 317
 318                 return rtc_set_alarm(rtc, &alarm);
 319
 320         case RTC_RD_TIME:
 321                 mutex_unlock(&rtc->ops_lock);
 322
 323                 err = rtc_read_time(rtc, &tm);
 324                 if (err < 0)
 325                         return err;
 326
 327                 if (copy_to_user(uarg, &tm, sizeof(tm)))
 328                         err = -EFAULT;
 329                 return err;
 330
 331         case RTC_SET_TIME:
 332                 mutex_unlock(&rtc->ops_lock);
 333
 334                 if (copy_from_user(&tm, uarg, sizeof(tm)))
 335                         return -EFAULT;
 336
 337                 return rtc_set_time(rtc, &tm);
 338
 339         case RTC_PIE_ON:
 340                 err = rtc_irq_set_state(rtc, 1);
 341                 break;
 342
 343         case RTC_PIE_OFF:
 344                 err = rtc_irq_set_state(rtc, 0);
 345                 break;
 346
 347         case RTC_AIE_ON:
 348                 mutex_unlock(&rtc->ops_lock);
 349                 return rtc_alarm_irq_enable(rtc, 1);
 350
 351         case RTC_AIE_OFF:
 352                 mutex_unlock(&rtc->ops_lock);
 353                 return rtc_alarm_irq_enable(rtc, 0);
 354
 355         case RTC_UIE_ON:
 356                 mutex_unlock(&rtc->ops_lock);
 357                 return rtc_update_irq_enable(rtc, 1);
 358
 359         case RTC_UIE_OFF:
 360                 mutex_unlock(&rtc->ops_lock);
 361                 return rtc_update_irq_enable(rtc, 0);
 362
 363         case RTC_IRQP_SET:
 364                 err = rtc_irq_set_freq(rtc, arg);
 365                 break;
 366         case RTC_IRQP_READ:
 367                 err = put_user(rtc->irq_freq, (unsigned long __user *)uarg);
 368                 break;
 369
 370         case RTC_WKALM_SET:
 371                 mutex_unlock(&rtc->ops_lock);
 372                 if (copy_from_user(&alarm, uarg, sizeof(alarm)))
 373                         return -EFAULT;
 374
 375                 return rtc_set_alarm(rtc, &alarm);
 376
 377         case RTC_WKALM_RD:
 378                 mutex_unlock(&rtc->ops_lock);
 379                 err = rtc_read_alarm(rtc, &alarm);
 380                 if (err < 0)
 381                         return err;
 382
 383                 if (copy_to_user(uarg, &alarm, sizeof(alarm)))
 384                         err = -EFAULT;
 385                 return err;
 386
 387         case RTC_PARAM_GET:
 388                 if (copy_from_user(&param, uarg, sizeof(param))) {
 389                         mutex_unlock(&rtc->ops_lock);
 390                         return -EFAULT;
 391                 }
 392
 393                 switch(param.param) {
 394                 case RTC_PARAM_FEATURES:
 395                         if (param.index != 0)
 396                                 err = -EINVAL;
 397                         param.uvalue = rtc->features[0];
 398                         break;
 399
 400                 case RTC_PARAM_CORRECTION: {
 401                         long offset;
 402                         mutex_unlock(&rtc->ops_lock);
 403                         if (param.index != 0)
 404                                 return -EINVAL;
 405                         err = rtc_read_offset(rtc, &offset);
 406                         mutex_lock(&rtc->ops_lock);
 407                         if (err == 0)
 408                                 param.svalue = offset;
 409                         break;
 410                 }
 411                 default:
 412                         if (rtc->ops->param_get)
 413                                 err = rtc->ops->param_get(rtc->dev.parent, &param);
 414                         else
 415                                 err = -EINVAL;
 416                 }
 417
 418                 if (!err)
 419                         if (copy_to_user(uarg, &param, sizeof(param)))
 420                                 err = -EFAULT;
 421
 422                 break;
 423
 424         case RTC_PARAM_SET:
 425                 if (copy_from_user(&param, uarg, sizeof(param))) {
 426                         mutex_unlock(&rtc->ops_lock);
 427                         return -EFAULT;
 428                 }
 429
 430                 switch(param.param) {
 431                 case RTC_PARAM_FEATURES:
 432                         err = -EINVAL;
 433                         break;
 434
 435                 case RTC_PARAM_CORRECTION:
 436                         mutex_unlock(&rtc->ops_lock);
 437                         if (param.index != 0)
 438                                 return -EINVAL;
 439                         return rtc_set_offset(rtc, param.svalue);
 440
 441                 default:
 442                         if (rtc->ops->param_set)
 443                                 err = rtc->ops->param_set(rtc->dev.parent, &param);
 444                         else
 445                                 err = -EINVAL;
 446                 }
 447
 448                 break;
 449
 450         default:
 451                 /* Finally try the driver's ioctl interface */
 452                 if (ops->ioctl) {
 453                         err = ops->ioctl(rtc->dev.parent, cmd, arg);
 454                         if (err == -ENOIOCTLCMD)
 455                                 err = -ENOTTY;
 456                 } else {
 457                         err = -ENOTTY;
 458                 }
 459                 break;
 460         }
 461
 462 done:
 463         mutex_unlock(&rtc->ops_lock);
 464         return err;
 465 }
 466
 467 #ifdef CONFIG_COMPAT
 468 #define RTC_IRQP_SET32          _IOW('p', 0x0c, __u32)
 469 #define RTC_IRQP_READ32         _IOR('p', 0x0b, __u32)
 470 #define RTC_EPOCH_SET32         _IOW('p', 0x0e, __u32)
 471
 472 static long rtc_dev_compat_ioctl(struct file *file,
 473                                  unsigned int cmd, unsigned long arg)
 474 {
 475         struct rtc_device *rtc = file->private_data;
 476         void __user *uarg = compat_ptr(arg);
 477
 478         switch (cmd) {
 479         case RTC_IRQP_READ32:
 480                 return put_user(rtc->irq_freq, (__u32 __user *)uarg);
 481
 482         case RTC_IRQP_SET32:
 483                 /* arg is a plain integer, not pointer */
 484                 return rtc_dev_ioctl(file, RTC_IRQP_SET, arg);
 485
 486         case RTC_EPOCH_SET32:
 487                 /* arg is a plain integer, not pointer */
 488                 return rtc_dev_ioctl(file, RTC_EPOCH_SET, arg);
 489         }
 490
 491         return rtc_dev_ioctl(file, cmd, (unsigned long)uarg);
 492 }
 493 #endif
 494
 495 static int rtc_dev_fasync(int fd, struct file *file, int on)
 496 {
 497         struct rtc_device *rtc = file->private_data;
 498
 499         return fasync_helper(fd, file, on, &rtc->async_queue);
 500 }
 501
 502 static int rtc_dev_release(struct inode *inode, struct file *file)
 503 {
 504         struct rtc_device *rtc = file->private_data;
 505
 506         /* We shut down the repeating IRQs that userspace enabled,
 507          * since nothing is listening to them.
 508          *  - Update (UIE) ... currently only managed through ioctls
 509          *  - Periodic (PIE) ... also used through rtc_*() interface calls
 510          *
 511          * Leave the alarm alone; it may be set to trigger a system wakeup
 512          * later, or be used by kernel code, and is a one-shot event anyway.
 513          */
 514
 515         /* Keep ioctl until all drivers are converted */
 516         rtc_dev_ioctl(file, RTC_UIE_OFF, 0);
 517         rtc_update_irq_enable(rtc, 0);
 518         rtc_irq_set_state(rtc, 0);
 519
 520         clear_bit_unlock(RTC_DEV_BUSY, &rtc->flags);
 521         return 0;
 522 }
 523
 524 static const struct file_operations rtc_dev_fops = {
 525         .owner          = THIS_MODULE,
 526         .llseek         = no_llseek,
 527         .read           = rtc_dev_read,
 528         .poll           = rtc_dev_poll,
 529         .unlocked_ioctl = rtc_dev_ioctl,
 530 #ifdef CONFIG_COMPAT
 531         .compat_ioctl   = rtc_dev_compat_ioctl,
 532 #endif
 533         .open           = rtc_dev_open,
 534         .release        = rtc_dev_release,
 535         .fasync         = rtc_dev_fasync,
 536 };
 537
 538 /* insertion/removal hooks */
 539
 540 void rtc_dev_prepare(struct rtc_device *rtc)
 541 {
 542         if (!rtc_devt)
 543                 return;
 544
 545         if (rtc->id >= RTC_DEV_MAX) {
 546                 dev_dbg(&rtc->dev, "too many RTC devices\n");
 547                 return;
 548         }
 549
 550         rtc->dev.devt = MKDEV(MAJOR(rtc_devt), rtc->id);
 551
 552 #ifdef CONFIG_RTC_INTF_DEV_UIE_EMUL
 553         INIT_WORK(&rtc->uie_task, rtc_uie_task);
 554         timer_setup(&rtc->uie_timer, rtc_uie_timer, 0);
 555 #endif
 556
 557         cdev_init(&rtc->char_dev, &rtc_dev_fops);
 558         rtc->char_dev.owner = rtc->owner;
 559 }
 560
 561 void __init rtc_dev_init(void)
 562 {
 563         int err;
 564
 565         err = alloc_chrdev_region(&rtc_devt, 0, RTC_DEV_MAX, "rtc");
 566         if (err < 0)
 567                 pr_err("failed to allocate char dev region\n");
 568 }
 569
 570 void __exit rtc_dev_exit(void)
 571 {
 572         if (rtc_devt)
 573                 unregister_chrdev_region(rtc_devt, RTC_DEV_MAX);
 574 }