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         void __user *uarg = (void __user *)arg;
 212
 213         err = mutex_lock_interruptible(&rtc->ops_lock);
 214         if (err)
 215                 return err;
 216
 217         /* check that the calling task has appropriate permissions
 218          * for certain ioctls. doing this check here is useful
 219          * to avoid duplicate code in each driver.
 220          */
 221         switch (cmd) {
 222         case RTC_EPOCH_SET:
 223         case RTC_SET_TIME:
 224                 if (!capable(CAP_SYS_TIME))
 225                         err = -EACCES;
 226                 break;
 227
 228         case RTC_IRQP_SET:
 229                 if (arg > rtc->max_user_freq && !capable(CAP_SYS_RESOURCE))
 230                         err = -EACCES;
 231                 break;
 232
 233         case RTC_PIE_ON:
 234                 if (rtc->irq_freq > rtc->max_user_freq &&
 235                     !capable(CAP_SYS_RESOURCE))
 236                         err = -EACCES;
 237                 break;
 238         }
 239
 240         if (err)
 241                 goto done;
 242
 243         /*
 244          * Drivers *SHOULD NOT* provide ioctl implementations
 245          * for these requests.  Instead, provide methods to
 246          * support the following code, so that the RTC's main
 247          * features are accessible without using ioctls.
 248          *
 249          * RTC and alarm times will be in UTC, by preference,
 250          * but dual-booting with MS-Windows implies RTCs must
 251          * use the local wall clock time.
 252          */
 253
 254         switch (cmd) {
 255         case RTC_ALM_READ:
 256                 mutex_unlock(&rtc->ops_lock);
 257
 258                 err = rtc_read_alarm(rtc, &alarm);
 259                 if (err < 0)
 260                         return err;
 261
 262                 if (copy_to_user(uarg, &alarm.time, sizeof(tm)))
 263                         err = -EFAULT;
 264                 return err;
 265
 266         case RTC_ALM_SET:
 267                 mutex_unlock(&rtc->ops_lock);
 268
 269                 if (copy_from_user(&alarm.time, uarg, sizeof(tm)))
 270                         return -EFAULT;
 271
 272                 alarm.enabled = 0;
 273                 alarm.pending = 0;
 274                 alarm.time.tm_wday = -1;
 275                 alarm.time.tm_yday = -1;
 276                 alarm.time.tm_isdst = -1;
 277
 278                 /* RTC_ALM_SET alarms may be up to 24 hours in the future.
 279                  * Rather than expecting every RTC to implement "don't care"
 280                  * for day/month/year fields, just force the alarm to have
 281                  * the right values for those fields.
 282                  *
 283                  * RTC_WKALM_SET should be used instead.  Not only does it
 284                  * eliminate the need for a separate RTC_AIE_ON call, it
 285                  * doesn't have the "alarm 23:59:59 in the future" race.
 286                  *
 287                  * NOTE:  some legacy code may have used invalid fields as
 288                  * wildcards, exposing hardware "periodic alarm" capabilities.
 289                  * Not supported here.
 290                  */
 291                 {
 292                         time64_t now, then;
 293
 294                         err = rtc_read_time(rtc, &tm);
 295                         if (err < 0)
 296                                 return err;
 297                         now = rtc_tm_to_time64(&tm);
 298
 299                         alarm.time.tm_mday = tm.tm_mday;
 300                         alarm.time.tm_mon = tm.tm_mon;
 301                         alarm.time.tm_year = tm.tm_year;
 302                         err  = rtc_valid_tm(&alarm.time);
 303                         if (err < 0)
 304                                 return err;
 305                         then = rtc_tm_to_time64(&alarm.time);
 306
 307                         /* alarm may need to wrap into tomorrow */
 308                         if (then < now) {
 309                                 rtc_time64_to_tm(now + 24 * 60 * 60, &tm);
 310                                 alarm.time.tm_mday = tm.tm_mday;
 311                                 alarm.time.tm_mon = tm.tm_mon;
 312                                 alarm.time.tm_year = tm.tm_year;
 313                         }
 314                 }
 315
 316                 return rtc_set_alarm(rtc, &alarm);
 317
 318         case RTC_RD_TIME:
 319                 mutex_unlock(&rtc->ops_lock);
 320
 321                 err = rtc_read_time(rtc, &tm);
 322                 if (err < 0)
 323                         return err;
 324
 325                 if (copy_to_user(uarg, &tm, sizeof(tm)))
 326                         err = -EFAULT;
 327                 return err;
 328
 329         case RTC_SET_TIME:
 330                 mutex_unlock(&rtc->ops_lock);
 331
 332                 if (copy_from_user(&tm, uarg, sizeof(tm)))
 333                         return -EFAULT;
 334
 335                 return rtc_set_time(rtc, &tm);
 336
 337         case RTC_PIE_ON:
 338                 err = rtc_irq_set_state(rtc, 1);
 339                 break;
 340
 341         case RTC_PIE_OFF:
 342                 err = rtc_irq_set_state(rtc, 0);
 343                 break;
 344
 345         case RTC_AIE_ON:
 346                 mutex_unlock(&rtc->ops_lock);
 347                 return rtc_alarm_irq_enable(rtc, 1);
 348
 349         case RTC_AIE_OFF:
 350                 mutex_unlock(&rtc->ops_lock);
 351                 return rtc_alarm_irq_enable(rtc, 0);
 352
 353         case RTC_UIE_ON:
 354                 mutex_unlock(&rtc->ops_lock);
 355                 return rtc_update_irq_enable(rtc, 1);
 356
 357         case RTC_UIE_OFF:
 358                 mutex_unlock(&rtc->ops_lock);
 359                 return rtc_update_irq_enable(rtc, 0);
 360
 361         case RTC_IRQP_SET:
 362                 err = rtc_irq_set_freq(rtc, arg);
 363                 break;
 364         case RTC_IRQP_READ:
 365                 err = put_user(rtc->irq_freq, (unsigned long __user *)uarg);
 366                 break;
 367
 368         case RTC_WKALM_SET:
 369                 mutex_unlock(&rtc->ops_lock);
 370                 if (copy_from_user(&alarm, uarg, sizeof(alarm)))
 371                         return -EFAULT;
 372
 373                 return rtc_set_alarm(rtc, &alarm);
 374
 375         case RTC_WKALM_RD:
 376                 mutex_unlock(&rtc->ops_lock);
 377                 err = rtc_read_alarm(rtc, &alarm);
 378                 if (err < 0)
 379                         return err;
 380
 381                 if (copy_to_user(uarg, &alarm, sizeof(alarm)))
 382                         err = -EFAULT;
 383                 return err;
 384
 385         default:
 386                 /* Finally try the driver's ioctl interface */
 387                 if (ops->ioctl) {
 388                         err = ops->ioctl(rtc->dev.parent, cmd, arg);
 389                         if (err == -ENOIOCTLCMD)
 390                                 err = -ENOTTY;
 391                 } else {
 392                         err = -ENOTTY;
 393                 }
 394                 break;
 395         }
 396
 397 done:
 398         mutex_unlock(&rtc->ops_lock);
 399         return err;
 400 }
 401
 402 #ifdef CONFIG_COMPAT
 403 #define RTC_IRQP_SET32          _IOW('p', 0x0c, __u32)
 404 #define RTC_IRQP_READ32         _IOR('p', 0x0b, __u32)
 405 #define RTC_EPOCH_SET32         _IOW('p', 0x0e, __u32)
 406
 407 static long rtc_dev_compat_ioctl(struct file *file,
 408                                  unsigned int cmd, unsigned long arg)
 409 {
 410         struct rtc_device *rtc = file->private_data;
 411         void __user *uarg = compat_ptr(arg);
 412
 413         switch (cmd) {
 414         case RTC_IRQP_READ32:
 415                 return put_user(rtc->irq_freq, (__u32 __user *)uarg);
 416
 417         case RTC_IRQP_SET32:
 418                 /* arg is a plain integer, not pointer */
 419                 return rtc_dev_ioctl(file, RTC_IRQP_SET, arg);
 420
 421         case RTC_EPOCH_SET32:
 422                 /* arg is a plain integer, not pointer */
 423                 return rtc_dev_ioctl(file, RTC_EPOCH_SET, arg);
 424         }
 425
 426         return rtc_dev_ioctl(file, cmd, (unsigned long)uarg);
 427 }
 428 #endif
 429
 430 static int rtc_dev_fasync(int fd, struct file *file, int on)
 431 {
 432         struct rtc_device *rtc = file->private_data;
 433
 434         return fasync_helper(fd, file, on, &rtc->async_queue);
 435 }
 436
 437 static int rtc_dev_release(struct inode *inode, struct file *file)
 438 {
 439         struct rtc_device *rtc = file->private_data;
 440
 441         /* We shut down the repeating IRQs that userspace enabled,
 442          * since nothing is listening to them.
 443          *  - Update (UIE) ... currently only managed through ioctls
 444          *  - Periodic (PIE) ... also used through rtc_*() interface calls
 445          *
 446          * Leave the alarm alone; it may be set to trigger a system wakeup
 447          * later, or be used by kernel code, and is a one-shot event anyway.
 448          */
 449
 450         /* Keep ioctl until all drivers are converted */
 451         rtc_dev_ioctl(file, RTC_UIE_OFF, 0);
 452         rtc_update_irq_enable(rtc, 0);
 453         rtc_irq_set_state(rtc, 0);
 454
 455         clear_bit_unlock(RTC_DEV_BUSY, &rtc->flags);
 456         return 0;
 457 }
 458
 459 static const struct file_operations rtc_dev_fops = {
 460         .owner          = THIS_MODULE,
 461         .llseek         = no_llseek,
 462         .read           = rtc_dev_read,
 463         .poll           = rtc_dev_poll,
 464         .unlocked_ioctl = rtc_dev_ioctl,
 465 #ifdef CONFIG_COMPAT
 466         .compat_ioctl   = rtc_dev_compat_ioctl,
 467 #endif
 468         .open           = rtc_dev_open,
 469         .release        = rtc_dev_release,
 470         .fasync         = rtc_dev_fasync,
 471 };
 472
 473 /* insertion/removal hooks */
 474
 475 void rtc_dev_prepare(struct rtc_device *rtc)
 476 {
 477         if (!rtc_devt)
 478                 return;
 479
 480         if (rtc->id >= RTC_DEV_MAX) {
 481                 dev_dbg(&rtc->dev, "too many RTC devices\n");
 482                 return;
 483         }
 484
 485         rtc->dev.devt = MKDEV(MAJOR(rtc_devt), rtc->id);
 486
 487 #ifdef CONFIG_RTC_INTF_DEV_UIE_EMUL
 488         INIT_WORK(&rtc->uie_task, rtc_uie_task);
 489         timer_setup(&rtc->uie_timer, rtc_uie_timer, 0);
 490 #endif
 491
 492         cdev_init(&rtc->char_dev, &rtc_dev_fops);
 493         rtc->char_dev.owner = rtc->owner;
 494 }
 495
 496 void __init rtc_dev_init(void)
 497 {
 498         int err;
 499
 500         err = alloc_chrdev_region(&rtc_devt, 0, RTC_DEV_MAX, "rtc");
 501         if (err < 0)
 502                 pr_err("failed to allocate char dev region\n");
 503 }
 504
 505 void __exit rtc_dev_exit(void)
 506 {
 507         if (rtc_devt)
 508                 unregister_chrdev_region(rtc_devt, RTC_DEV_MAX);
 509 }