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 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  15
  16 #include <linux/module.h>
  17 #include <linux/rtc.h>
  18 #include <linux/sched/signal.h>
  19 #include "rtc-core.h"
  20
  21 static dev_t rtc_devt;
  22
  23 #define RTC_DEV_MAX 16 /* 16 RTCs should be enough for everyone... */
  24
  25 static int rtc_dev_open(struct inode *inode, struct file *file)
  26 {
  27         struct rtc_device *rtc = container_of(inode->i_cdev,
  28                                         struct rtc_device, char_dev);
  29
  30         if (test_and_set_bit_lock(RTC_DEV_BUSY, &rtc->flags))
  31                 return -EBUSY;
  32
  33         file->private_data = rtc;
  34
  35         spin_lock_irq(&rtc->irq_lock);
  36         rtc->irq_data = 0;
  37         spin_unlock_irq(&rtc->irq_lock);
  38
  39         return 0;
  40 }
  41
  42 #ifdef CONFIG_RTC_INTF_DEV_UIE_EMUL
  43 /*
  44  * Routine to poll RTC seconds field for change as often as possible,
  45  * after first RTC_UIE use timer to reduce polling
  46  */
  47 static void rtc_uie_task(struct work_struct *work)
  48 {
  49         struct rtc_device *rtc =
  50                 container_of(work, struct rtc_device, uie_task);
  51         struct rtc_time tm;
  52         int num = 0;
  53         int err;
  54
  55         err = rtc_read_time(rtc, &tm);
  56
  57         spin_lock_irq(&rtc->irq_lock);
  58         if (rtc->stop_uie_polling || err) {
  59                 rtc->uie_task_active = 0;
  60         } else if (rtc->oldsecs != tm.tm_sec) {
  61                 num = (tm.tm_sec + 60 - rtc->oldsecs) % 60;
  62                 rtc->oldsecs = tm.tm_sec;
  63                 rtc->uie_timer.expires = jiffies + HZ - (HZ/10);
  64                 rtc->uie_timer_active = 1;
  65                 rtc->uie_task_active = 0;
  66                 add_timer(&rtc->uie_timer);
  67         } else if (schedule_work(&rtc->uie_task) == 0) {
  68                 rtc->uie_task_active = 0;
  69         }
  70         spin_unlock_irq(&rtc->irq_lock);
  71         if (num)
  72                 rtc_handle_legacy_irq(rtc, num, RTC_UF);
  73 }
  74 static void rtc_uie_timer(struct timer_list *t)
  75 {
  76         struct rtc_device *rtc = from_timer(rtc, t, uie_timer);
  77         unsigned long flags;
  78
  79         spin_lock_irqsave(&rtc->irq_lock, flags);
  80         rtc->uie_timer_active = 0;
  81         rtc->uie_task_active = 1;
  82         if ((schedule_work(&rtc->uie_task) == 0))
  83                 rtc->uie_task_active = 0;
  84         spin_unlock_irqrestore(&rtc->irq_lock, flags);
  85 }
  86
  87 static int clear_uie(struct rtc_device *rtc)
  88 {
  89         spin_lock_irq(&rtc->irq_lock);
  90         if (rtc->uie_irq_active) {
  91                 rtc->stop_uie_polling = 1;
  92                 if (rtc->uie_timer_active) {
  93                         spin_unlock_irq(&rtc->irq_lock);
  94                         del_timer_sync(&rtc->uie_timer);
  95                         spin_lock_irq(&rtc->irq_lock);
  96                         rtc->uie_timer_active = 0;
  97                 }
  98                 if (rtc->uie_task_active) {
  99                         spin_unlock_irq(&rtc->irq_lock);
 100                         flush_scheduled_work();
 101                         spin_lock_irq(&rtc->irq_lock);
 102                 }
 103                 rtc->uie_irq_active = 0;
 104         }
 105         spin_unlock_irq(&rtc->irq_lock);
 106         return 0;
 107 }
 108
 109 static int set_uie(struct rtc_device *rtc)
 110 {
 111         struct rtc_time tm;
 112         int err;
 113
 114         err = rtc_read_time(rtc, &tm);
 115         if (err)
 116                 return err;
 117         spin_lock_irq(&rtc->irq_lock);
 118         if (!rtc->uie_irq_active) {
 119                 rtc->uie_irq_active = 1;
 120                 rtc->stop_uie_polling = 0;
 121                 rtc->oldsecs = tm.tm_sec;
 122                 rtc->uie_task_active = 1;
 123                 if (schedule_work(&rtc->uie_task) == 0)
 124                         rtc->uie_task_active = 0;
 125         }
 126         rtc->irq_data = 0;
 127         spin_unlock_irq(&rtc->irq_lock);
 128         return 0;
 129 }
 130
 131 int rtc_dev_update_irq_enable_emul(struct rtc_device *rtc, unsigned int enabled)
 132 {
 133         if (enabled)
 134                 return set_uie(rtc);
 135         else
 136                 return clear_uie(rtc);
 137 }
 138 EXPORT_SYMBOL(rtc_dev_update_irq_enable_emul);
 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 = 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 __poll_t rtc_dev_poll(struct file *file, poll_table *wait)
 198 {
 199         struct rtc_device *rtc = 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) ? (EPOLLIN | EPOLLRDNORM) : 0;
 207 }
 208
 209 static long rtc_dev_ioctl(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         err = mutex_lock_interruptible(&rtc->ops_lock);
 220         if (err)
 221                 return err;
 222
 223         /* check that the calling task has appropriate permissions
 224          * for certain ioctls. doing this check here is useful
 225          * to avoid duplicate code in each driver.
 226          */
 227         switch (cmd) {
 228         case RTC_EPOCH_SET:
 229         case RTC_SET_TIME:
 230                 if (!capable(CAP_SYS_TIME))
 231                         err = -EACCES;
 232                 break;
 233
 234         case RTC_IRQP_SET:
 235                 if (arg > rtc->max_user_freq && !capable(CAP_SYS_RESOURCE))
 236                         err = -EACCES;
 237                 break;
 238
 239         case RTC_PIE_ON:
 240                 if (rtc->irq_freq > rtc->max_user_freq &&
 241                                 !capable(CAP_SYS_RESOURCE))
 242                         err = -EACCES;
 243                 break;
 244         }
 245
 246         if (err)
 247                 goto done;
 248
 249         /*
 250          * Drivers *SHOULD NOT* provide ioctl implementations
 251          * for these requests.  Instead, provide methods to
 252          * support the following code, so that the RTC's main
 253          * features are accessible without using ioctls.
 254          *
 255          * RTC and alarm times will be in UTC, by preference,
 256          * but dual-booting with MS-Windows implies RTCs must
 257          * use the local wall clock time.
 258          */
 259
 260         switch (cmd) {
 261         case RTC_ALM_READ:
 262                 mutex_unlock(&rtc->ops_lock);
 263
 264                 err = rtc_read_alarm(rtc, &alarm);
 265                 if (err < 0)
 266                         return err;
 267
 268                 if (copy_to_user(uarg, &alarm.time, sizeof(tm)))
 269                         err = -EFAULT;
 270                 return err;
 271
 272         case RTC_ALM_SET:
 273                 mutex_unlock(&rtc->ops_lock);
 274
 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                         time64_t now, then;
 299
 300                         err = rtc_read_time(rtc, &tm);
 301                         if (err < 0)
 302                                 return err;
 303                         now = rtc_tm_to_time64(&tm);
 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                         then = rtc_tm_to_time64(&alarm.time);
 312
 313                         /* alarm may need to wrap into tomorrow */
 314                         if (then < now) {
 315                                 rtc_time64_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                 return rtc_set_alarm(rtc, &alarm);
 323
 324         case RTC_RD_TIME:
 325                 mutex_unlock(&rtc->ops_lock);
 326
 327                 err = rtc_read_time(rtc, &tm);
 328                 if (err < 0)
 329                         return err;
 330
 331                 if (copy_to_user(uarg, &tm, sizeof(tm)))
 332                         err = -EFAULT;
 333                 return err;
 334
 335         case RTC_SET_TIME:
 336                 mutex_unlock(&rtc->ops_lock);
 337
 338                 if (copy_from_user(&tm, uarg, sizeof(tm)))
 339                         return -EFAULT;
 340
 341                 return rtc_set_time(rtc, &tm);
 342
 343         case RTC_PIE_ON:
 344                 err = rtc_irq_set_state(rtc, 1);
 345                 break;
 346
 347         case RTC_PIE_OFF:
 348                 err = rtc_irq_set_state(rtc, 0);
 349                 break;
 350
 351         case RTC_AIE_ON:
 352                 mutex_unlock(&rtc->ops_lock);
 353                 return rtc_alarm_irq_enable(rtc, 1);
 354
 355         case RTC_AIE_OFF:
 356                 mutex_unlock(&rtc->ops_lock);
 357                 return rtc_alarm_irq_enable(rtc, 0);
 358
 359         case RTC_UIE_ON:
 360                 mutex_unlock(&rtc->ops_lock);
 361                 return rtc_update_irq_enable(rtc, 1);
 362
 363         case RTC_UIE_OFF:
 364                 mutex_unlock(&rtc->ops_lock);
 365                 return rtc_update_irq_enable(rtc, 0);
 366
 367         case RTC_IRQP_SET:
 368                 err = rtc_irq_set_freq(rtc, arg);
 369                 break;
 370
 371         case RTC_IRQP_READ:
 372                 err = put_user(rtc->irq_freq, (unsigned long __user *)uarg);
 373                 break;
 374
 375         case RTC_WKALM_SET:
 376                 mutex_unlock(&rtc->ops_lock);
 377                 if (copy_from_user(&alarm, uarg, sizeof(alarm)))
 378                         return -EFAULT;
 379
 380                 return rtc_set_alarm(rtc, &alarm);
 381
 382         case RTC_WKALM_RD:
 383                 mutex_unlock(&rtc->ops_lock);
 384                 err = rtc_read_alarm(rtc, &alarm);
 385                 if (err < 0)
 386                         return err;
 387
 388                 if (copy_to_user(uarg, &alarm, sizeof(alarm)))
 389                         err = -EFAULT;
 390                 return err;
 391
 392         default:
 393                 /* Finally try the driver's ioctl interface */
 394                 if (ops->ioctl) {
 395                         err = ops->ioctl(rtc->dev.parent, cmd, arg);
 396                         if (err == -ENOIOCTLCMD)
 397                                 err = -ENOTTY;
 398                 } else
 399                         err = -ENOTTY;
 400                 break;
 401         }
 402
 403 done:
 404         mutex_unlock(&rtc->ops_lock);
 405         return err;
 406 }
 407
 408 static int rtc_dev_fasync(int fd, struct file *file, int on)
 409 {
 410         struct rtc_device *rtc = file->private_data;
 411         return fasync_helper(fd, file, on, &rtc->async_queue);
 412 }
 413
 414 static int rtc_dev_release(struct inode *inode, struct file *file)
 415 {
 416         struct rtc_device *rtc = file->private_data;
 417
 418         /* We shut down the repeating IRQs that userspace enabled,
 419          * since nothing is listening to them.
 420          *  - Update (UIE) ... currently only managed through ioctls
 421          *  - Periodic (PIE) ... also used through rtc_*() interface calls
 422          *
 423          * Leave the alarm alone; it may be set to trigger a system wakeup
 424          * later, or be used by kernel code, and is a one-shot event anyway.
 425          */
 426
 427         /* Keep ioctl until all drivers are converted */
 428         rtc_dev_ioctl(file, RTC_UIE_OFF, 0);
 429         rtc_update_irq_enable(rtc, 0);
 430         rtc_irq_set_state(rtc, 0);
 431
 432         clear_bit_unlock(RTC_DEV_BUSY, &rtc->flags);
 433         return 0;
 434 }
 435
 436 static const struct file_operations rtc_dev_fops = {
 437         .owner          = THIS_MODULE,
 438         .llseek         = no_llseek,
 439         .read           = rtc_dev_read,
 440         .poll           = rtc_dev_poll,
 441         .unlocked_ioctl = rtc_dev_ioctl,
 442         .open           = rtc_dev_open,
 443         .release        = rtc_dev_release,
 444         .fasync         = rtc_dev_fasync,
 445 };
 446
 447 /* insertion/removal hooks */
 448
 449 void rtc_dev_prepare(struct rtc_device *rtc)
 450 {
 451         if (!rtc_devt)
 452                 return;
 453
 454         if (rtc->id >= RTC_DEV_MAX) {
 455                 dev_dbg(&rtc->dev, "too many RTC devices\n");
 456                 return;
 457         }
 458
 459         rtc->dev.devt = MKDEV(MAJOR(rtc_devt), rtc->id);
 460
 461 #ifdef CONFIG_RTC_INTF_DEV_UIE_EMUL
 462         INIT_WORK(&rtc->uie_task, rtc_uie_task);
 463         timer_setup(&rtc->uie_timer, rtc_uie_timer, 0);
 464 #endif
 465
 466         cdev_init(&rtc->char_dev, &rtc_dev_fops);
 467         rtc->char_dev.owner = rtc->owner;
 468 }
 469
 470 void __init rtc_dev_init(void)
 471 {
 472         int err;
 473
 474         err = alloc_chrdev_region(&rtc_devt, 0, RTC_DEV_MAX, "rtc");
 475         if (err < 0)
 476                 pr_err("failed to allocate char dev region\n");
 477 }
 478
 479 void __exit rtc_dev_exit(void)
 480 {
 481         if (rtc_devt)
 482                 unregister_chrdev_region(rtc_devt, RTC_DEV_MAX);
 483 }