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
  50 static ssize_t
  51 rtc_dev_read(struct file *file, char __user *buf, size_t count, loff_t *ppos)
  52 {
  53         struct rtc_device *rtc = file->private_data;
  54
  55         DECLARE_WAITQUEUE(wait, current);
  56         unsigned long data;
  57         ssize_t ret;
  58
  59         if (count != sizeof(unsigned int) && count < sizeof(unsigned long))
  60                 return -EINVAL;
  61
  62         add_wait_queue(&rtc->irq_queue, &wait);
  63         do {
  64                 __set_current_state(TASK_INTERRUPTIBLE);
  65
  66                 spin_lock_irq(&rtc->irq_lock);
  67                 data = rtc->irq_data;
  68                 rtc->irq_data = 0;
  69                 spin_unlock_irq(&rtc->irq_lock);
  70
  71                 if (data != 0) {
  72                         ret = 0;
  73                         break;
  74                 }
  75                 if (file->f_flags & O_NONBLOCK) {
  76                         ret = -EAGAIN;
  77                         break;
  78                 }
  79                 if (signal_pending(current)) {
  80                         ret = -ERESTARTSYS;
  81                         break;
  82                 }
  83                 schedule();
  84         } while (1);
  85         set_current_state(TASK_RUNNING);
  86         remove_wait_queue(&rtc->irq_queue, &wait);
  87
  88         if (ret == 0) {
  89                 /* Check for any data updates */
  90                 if (rtc->ops->read_callback)
  91                         data = rtc->ops->read_callback(rtc->dev.parent,
  92                                                        data);
  93
  94                 if (sizeof(int) != sizeof(long) &&
  95                     count == sizeof(unsigned int))
  96                         ret = put_user(data, (unsigned int __user *)buf) ?:
  97                                 sizeof(unsigned int);
  98                 else
  99                         ret = put_user(data, (unsigned long __user *)buf) ?:
 100                                 sizeof(unsigned long);
 101         }
 102         return ret;
 103 }
 104
 105 static unsigned int rtc_dev_poll(struct file *file, poll_table *wait)
 106 {
 107         struct rtc_device *rtc = file->private_data;
 108         unsigned long data;
 109
 110         poll_wait(file, &rtc->irq_queue, wait);
 111
 112         data = rtc->irq_data;
 113
 114         return (data != 0) ? (POLLIN | POLLRDNORM) : 0;
 115 }
 116
 117 static long rtc_dev_ioctl(struct file *file,
 118                 unsigned int cmd, unsigned long arg)
 119 {
 120         int err = 0;
 121         struct rtc_device *rtc = file->private_data;
 122         const struct rtc_class_ops *ops = rtc->ops;
 123         struct rtc_time tm;
 124         struct rtc_wkalrm alarm;
 125         void __user *uarg = (void __user *) arg;
 126
 127         err = mutex_lock_interruptible(&rtc->ops_lock);
 128         if (err)
 129                 return err;
 130
 131         /* check that the calling task has appropriate permissions
 132          * for certain ioctls. doing this check here is useful
 133          * to avoid duplicate code in each driver.
 134          */
 135         switch (cmd) {
 136         case RTC_EPOCH_SET:
 137         case RTC_SET_TIME:
 138                 if (!capable(CAP_SYS_TIME))
 139                         err = -EACCES;
 140                 break;
 141
 142         case RTC_IRQP_SET:
 143                 if (arg > rtc->max_user_freq && !capable(CAP_SYS_RESOURCE))
 144                         err = -EACCES;
 145                 break;
 146
 147         case RTC_PIE_ON:
 148                 if (rtc->irq_freq > rtc->max_user_freq &&
 149                                 !capable(CAP_SYS_RESOURCE))
 150                         err = -EACCES;
 151                 break;
 152         }
 153
 154         if (err)
 155                 goto done;
 156
 157         /* try the driver's ioctl interface */
 158         if (ops->ioctl) {
 159                 err = ops->ioctl(rtc->dev.parent, cmd, arg);
 160                 if (err != -ENOIOCTLCMD) {
 161                         mutex_unlock(&rtc->ops_lock);
 162                         return err;
 163                 }
 164         }
 165
 166         /* if the driver does not provide the ioctl interface
 167          * or if that particular ioctl was not implemented
 168          * (-ENOIOCTLCMD), we will try to emulate here.
 169          *
 170          * Drivers *SHOULD NOT* provide ioctl implementations
 171          * for these requests.  Instead, provide methods to
 172          * support the following code, so that the RTC's main
 173          * features are accessible without using ioctls.
 174          *
 175          * RTC and alarm times will be in UTC, by preference,
 176          * but dual-booting with MS-Windows implies RTCs must
 177          * use the local wall clock time.
 178          */
 179
 180         switch (cmd) {
 181         case RTC_ALM_READ:
 182                 mutex_unlock(&rtc->ops_lock);
 183
 184                 err = rtc_read_alarm(rtc, &alarm);
 185                 if (err < 0)
 186                         return err;
 187
 188                 if (copy_to_user(uarg, &alarm.time, sizeof(tm)))
 189                         err = -EFAULT;
 190                 return err;
 191
 192         case RTC_ALM_SET:
 193                 mutex_unlock(&rtc->ops_lock);
 194
 195                 if (copy_from_user(&alarm.time, uarg, sizeof(tm)))
 196                         return -EFAULT;
 197
 198                 alarm.enabled = 0;
 199                 alarm.pending = 0;
 200                 alarm.time.tm_wday = -1;
 201                 alarm.time.tm_yday = -1;
 202                 alarm.time.tm_isdst = -1;
 203
 204                 /* RTC_ALM_SET alarms may be up to 24 hours in the future.
 205                  * Rather than expecting every RTC to implement "don't care"
 206                  * for day/month/year fields, just force the alarm to have
 207                  * the right values for those fields.
 208                  *
 209                  * RTC_WKALM_SET should be used instead.  Not only does it
 210                  * eliminate the need for a separate RTC_AIE_ON call, it
 211                  * doesn't have the "alarm 23:59:59 in the future" race.
 212                  *
 213                  * NOTE:  some legacy code may have used invalid fields as
 214                  * wildcards, exposing hardware "periodic alarm" capabilities.
 215                  * Not supported here.
 216                  */
 217                 {
 218                         unsigned long now, then;
 219
 220                         err = rtc_read_time(rtc, &tm);
 221                         if (err < 0)
 222                                 return err;
 223                         rtc_tm_to_time(&tm, &now);
 224
 225                         alarm.time.tm_mday = tm.tm_mday;
 226                         alarm.time.tm_mon = tm.tm_mon;
 227                         alarm.time.tm_year = tm.tm_year;
 228                         err  = rtc_valid_tm(&alarm.time);
 229                         if (err < 0)
 230                                 return err;
 231                         rtc_tm_to_time(&alarm.time, &then);
 232
 233                         /* alarm may need to wrap into tomorrow */
 234                         if (then < now) {
 235                                 rtc_time_to_tm(now + 24 * 60 * 60, &tm);
 236                                 alarm.time.tm_mday = tm.tm_mday;
 237                                 alarm.time.tm_mon = tm.tm_mon;
 238                                 alarm.time.tm_year = tm.tm_year;
 239                         }
 240                 }
 241
 242                 return rtc_set_alarm(rtc, &alarm);
 243
 244         case RTC_RD_TIME:
 245                 mutex_unlock(&rtc->ops_lock);
 246
 247                 err = rtc_read_time(rtc, &tm);
 248                 if (err < 0)
 249                         return err;
 250
 251                 if (copy_to_user(uarg, &tm, sizeof(tm)))
 252                         err = -EFAULT;
 253                 return err;
 254
 255         case RTC_SET_TIME:
 256                 mutex_unlock(&rtc->ops_lock);
 257
 258                 if (copy_from_user(&tm, uarg, sizeof(tm)))
 259                         return -EFAULT;
 260
 261                 return rtc_set_time(rtc, &tm);
 262
 263         case RTC_PIE_ON:
 264                 err = rtc_irq_set_state(rtc, NULL, 1);
 265                 break;
 266
 267         case RTC_PIE_OFF:
 268                 err = rtc_irq_set_state(rtc, NULL, 0);
 269                 break;
 270
 271         case RTC_AIE_ON:
 272                 mutex_unlock(&rtc->ops_lock);
 273                 return rtc_alarm_irq_enable(rtc, 1);
 274
 275         case RTC_AIE_OFF:
 276                 mutex_unlock(&rtc->ops_lock);
 277                 return rtc_alarm_irq_enable(rtc, 0);
 278
 279         case RTC_UIE_ON:
 280                 mutex_unlock(&rtc->ops_lock);
 281                 return rtc_update_irq_enable(rtc, 1);
 282
 283         case RTC_UIE_OFF:
 284                 mutex_unlock(&rtc->ops_lock);
 285                 return rtc_update_irq_enable(rtc, 0);
 286
 287         case RTC_IRQP_SET:
 288                 err = rtc_irq_set_freq(rtc, NULL, arg);
 289                 break;
 290
 291         case RTC_IRQP_READ:
 292                 err = put_user(rtc->irq_freq, (unsigned long __user *)uarg);
 293                 break;
 294
 295 #if 0
 296         case RTC_EPOCH_SET:
 297 #ifndef rtc_epoch
 298                 /*
 299                  * There were no RTC clocks before 1900.
 300                  */
 301                 if (arg < 1900) {
 302                         err = -EINVAL;
 303                         break;
 304                 }
 305                 rtc_epoch = arg;
 306                 err = 0;
 307 #endif
 308                 break;
 309
 310         case RTC_EPOCH_READ:
 311                 err = put_user(rtc_epoch, (unsigned long __user *)uarg);
 312                 break;
 313 #endif
 314         case RTC_WKALM_SET:
 315                 mutex_unlock(&rtc->ops_lock);
 316                 if (copy_from_user(&alarm, uarg, sizeof(alarm)))
 317                         return -EFAULT;
 318
 319                 return rtc_set_alarm(rtc, &alarm);
 320
 321         case RTC_WKALM_RD:
 322                 mutex_unlock(&rtc->ops_lock);
 323                 err = rtc_read_alarm(rtc, &alarm);
 324                 if (err < 0)
 325                         return err;
 326
 327                 if (copy_to_user(uarg, &alarm, sizeof(alarm)))
 328                         err = -EFAULT;
 329                 return err;
 330
 331         default:
 332                 err = -ENOTTY;
 333                 break;
 334         }
 335
 336 done:
 337         mutex_unlock(&rtc->ops_lock);
 338         return err;
 339 }
 340
 341 static int rtc_dev_fasync(int fd, struct file *file, int on)
 342 {
 343         struct rtc_device *rtc = file->private_data;
 344         return fasync_helper(fd, file, on, &rtc->async_queue);
 345 }
 346
 347 static int rtc_dev_release(struct inode *inode, struct file *file)
 348 {
 349         struct rtc_device *rtc = file->private_data;
 350
 351         /* We shut down the repeating IRQs that userspace enabled,
 352          * since nothing is listening to them.
 353          *  - Update (UIE) ... currently only managed through ioctls
 354          *  - Periodic (PIE) ... also used through rtc_*() interface calls
 355          *
 356          * Leave the alarm alone; it may be set to trigger a system wakeup
 357          * later, or be used by kernel code, and is a one-shot event anyway.
 358          */
 359
 360         /* Keep ioctl until all drivers are converted */
 361         rtc_dev_ioctl(file, RTC_UIE_OFF, 0);
 362         rtc_update_irq_enable(rtc, 0);
 363         rtc_irq_set_state(rtc, NULL, 0);
 364
 365         if (rtc->ops->release)
 366                 rtc->ops->release(rtc->dev.parent);
 367
 368         clear_bit_unlock(RTC_DEV_BUSY, &rtc->flags);
 369         return 0;
 370 }
 371
 372 static const struct file_operations rtc_dev_fops = {
 373         .owner          = THIS_MODULE,
 374         .llseek         = no_llseek,
 375         .read           = rtc_dev_read,
 376         .poll           = rtc_dev_poll,
 377         .unlocked_ioctl = rtc_dev_ioctl,
 378         .open           = rtc_dev_open,
 379         .release        = rtc_dev_release,
 380         .fasync         = rtc_dev_fasync,
 381 };
 382
 383 /* insertion/removal hooks */
 384
 385 void rtc_dev_prepare(struct rtc_device *rtc)
 386 {
 387         if (!rtc_devt)
 388                 return;
 389
 390         if (rtc->id >= RTC_DEV_MAX) {
 391                 pr_debug("%s: too many RTC devices\n", rtc->name);
 392                 return;
 393         }
 394
 395         rtc->dev.devt = MKDEV(MAJOR(rtc_devt), rtc->id);
 396
 397         cdev_init(&rtc->char_dev, &rtc_dev_fops);
 398         rtc->char_dev.owner = rtc->owner;
 399 }
 400
 401 void rtc_dev_add_device(struct rtc_device *rtc)
 402 {
 403         if (cdev_add(&rtc->char_dev, rtc->dev.devt, 1))
 404                 printk(KERN_WARNING "%s: failed to add char device %d:%d\n",
 405                         rtc->name, MAJOR(rtc_devt), rtc->id);
 406         else
 407                 pr_debug("%s: dev (%d:%d)\n", rtc->name,
 408                         MAJOR(rtc_devt), rtc->id);
 409 }
 410
 411 void rtc_dev_del_device(struct rtc_device *rtc)
 412 {
 413         if (rtc->dev.devt)
 414                 cdev_del(&rtc->char_dev);
 415 }
 416
 417 void __init rtc_dev_init(void)
 418 {
 419         int err;
 420
 421         err = alloc_chrdev_region(&rtc_devt, 0, RTC_DEV_MAX, "rtc");
 422         if (err < 0)
 423                 printk(KERN_ERR "%s: failed to allocate char dev region\n",
 424                         __FILE__);
 425 }
 426
 427 void __exit rtc_dev_exit(void)
 428 {
 429         if (rtc_devt)
 430                 unregister_chrdev_region(rtc_devt, RTC_DEV_MAX);
 431 }