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
  17 static struct class *rtc_dev_class;
  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         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->class_dev;
  36
  37         err = ops->open ? ops->open(rtc->class_dev.dev) : 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
  52 static ssize_t
  53 rtc_dev_read(struct file *file, char __user *buf, size_t count, loff_t *ppos)
  54 {
  55         struct rtc_device *rtc = to_rtc_device(file->private_data);
  56
  57         DECLARE_WAITQUEUE(wait, current);
  58         unsigned long data;
  59         ssize_t ret;
  60
  61         if (count != sizeof(unsigned int) && count < sizeof(unsigned long))
  62                 return -EINVAL;
  63
  64         add_wait_queue(&rtc->irq_queue, &wait);
  65         do {
  66                 __set_current_state(TASK_INTERRUPTIBLE);
  67
  68                 spin_lock_irq(&rtc->irq_lock);
  69                 data = rtc->irq_data;
  70                 rtc->irq_data = 0;
  71                 spin_unlock_irq(&rtc->irq_lock);
  72
  73                 if (data != 0) {
  74                         ret = 0;
  75                         break;
  76                 }
  77                 if (file->f_flags & O_NONBLOCK) {
  78                         ret = -EAGAIN;
  79                         break;
  80                 }
  81                 if (signal_pending(current)) {
  82                         ret = -ERESTARTSYS;
  83                         break;
  84                 }
  85                 schedule();
  86         } while (1);
  87         set_current_state(TASK_RUNNING);
  88         remove_wait_queue(&rtc->irq_queue, &wait);
  89
  90         if (ret == 0) {
  91                 /* Check for any data updates */
  92                 if (rtc->ops->read_callback)
  93                         data = rtc->ops->read_callback(rtc->class_dev.dev,
  94                                                        data);
  95
  96                 if (sizeof(int) != sizeof(long) &&
  97                     count == sizeof(unsigned int))
  98                         ret = put_user(data, (unsigned int __user *)buf) ?:
  99                                 sizeof(unsigned int);
 100                 else
 101                         ret = put_user(data, (unsigned long __user *)buf) ?:
 102                                 sizeof(unsigned long);
 103         }
 104         return ret;
 105 }
 106
 107 static unsigned int rtc_dev_poll(struct file *file, poll_table *wait)
 108 {
 109         struct rtc_device *rtc = to_rtc_device(file->private_data);
 110         unsigned long data;
 111
 112         poll_wait(file, &rtc->irq_queue, wait);
 113
 114         data = rtc->irq_data;
 115
 116         return (data != 0) ? (POLLIN | POLLRDNORM) : 0;
 117 }
 118
 119 static int rtc_dev_ioctl(struct inode *inode, struct file *file,
 120                 unsigned int cmd, unsigned long arg)
 121 {
 122         int err = 0;
 123         struct class_device *class_dev = file->private_data;
 124         struct rtc_device *rtc = to_rtc_device(class_dev);
 125         struct rtc_class_ops *ops = rtc->ops;
 126         struct rtc_time tm;
 127         struct rtc_wkalrm alarm;
 128         void __user *uarg = (void __user *) arg;
 129
 130         /* avoid conflicting IRQ users */
 131         if (cmd == RTC_PIE_ON || cmd == RTC_PIE_OFF || cmd == RTC_IRQP_SET) {
 132                 spin_lock(&rtc->irq_task_lock);
 133                 if (rtc->irq_task)
 134                         err = -EBUSY;
 135                 spin_unlock(&rtc->irq_task_lock);
 136
 137                 if (err < 0)
 138                         return err;
 139         }
 140
 141         /* try the driver's ioctl interface */
 142         if (ops->ioctl) {
 143                 err = ops->ioctl(class_dev->dev, cmd, arg);
 144                 if (err != -ENOIOCTLCMD)
 145                         return err;
 146         }
 147
 148         /* if the driver does not provide the ioctl interface
 149          * or if that particular ioctl was not implemented
 150          * (-ENOIOCTLCMD), we will try to emulate here.
 151          */
 152
 153         switch (cmd) {
 154         case RTC_ALM_READ:
 155                 err = rtc_read_alarm(class_dev, &alarm);
 156                 if (err < 0)
 157                         return err;
 158
 159                 if (copy_to_user(uarg, &alarm.time, sizeof(tm)))
 160                         return -EFAULT;
 161                 break;
 162
 163         case RTC_ALM_SET:
 164                 if (copy_from_user(&alarm.time, uarg, sizeof(tm)))
 165                         return -EFAULT;
 166
 167                 alarm.enabled = 0;
 168                 alarm.pending = 0;
 169                 alarm.time.tm_mday = -1;
 170                 alarm.time.tm_mon = -1;
 171                 alarm.time.tm_year = -1;
 172                 alarm.time.tm_wday = -1;
 173                 alarm.time.tm_yday = -1;
 174                 alarm.time.tm_isdst = -1;
 175                 err = rtc_set_alarm(class_dev, &alarm);
 176                 break;
 177
 178         case RTC_RD_TIME:
 179                 err = rtc_read_time(class_dev, &tm);
 180                 if (err < 0)
 181                         return err;
 182
 183                 if (copy_to_user(uarg, &tm, sizeof(tm)))
 184                         return -EFAULT;
 185                 break;
 186
 187         case RTC_SET_TIME:
 188                 if (!capable(CAP_SYS_TIME))
 189                         return -EACCES;
 190
 191                 if (copy_from_user(&tm, uarg, sizeof(tm)))
 192                         return -EFAULT;
 193
 194                 err = rtc_set_time(class_dev, &tm);
 195                 break;
 196 #if 0
 197         case RTC_EPOCH_SET:
 198 #ifndef rtc_epoch
 199                 /*
 200                  * There were no RTC clocks before 1900.
 201                  */
 202                 if (arg < 1900) {
 203                         err = -EINVAL;
 204                         break;
 205                 }
 206                 if (!capable(CAP_SYS_TIME)) {
 207                         err = -EACCES;
 208                         break;
 209                 }
 210                 rtc_epoch = arg;
 211                 err = 0;
 212 #endif
 213                 break;
 214
 215         case RTC_EPOCH_READ:
 216                 err = put_user(rtc_epoch, (unsigned long __user *)uarg);
 217                 break;
 218 #endif
 219         case RTC_WKALM_SET:
 220                 if (copy_from_user(&alarm, uarg, sizeof(alarm)))
 221                         return -EFAULT;
 222
 223                 err = rtc_set_alarm(class_dev, &alarm);
 224                 break;
 225
 226         case RTC_WKALM_RD:
 227                 err = rtc_read_alarm(class_dev, &alarm);
 228                 if (err < 0)
 229                         return err;
 230
 231                 if (copy_to_user(uarg, &alarm, sizeof(alarm)))
 232                         return -EFAULT;
 233                 break;
 234
 235         default:
 236                 err = -ENOTTY;
 237                 break;
 238         }
 239
 240         return err;
 241 }
 242
 243 static int rtc_dev_release(struct inode *inode, struct file *file)
 244 {
 245         struct rtc_device *rtc = to_rtc_device(file->private_data);
 246
 247         if (rtc->ops->release)
 248                 rtc->ops->release(rtc->class_dev.dev);
 249
 250         mutex_unlock(&rtc->char_lock);
 251         return 0;
 252 }
 253
 254 static int rtc_dev_fasync(int fd, struct file *file, int on)
 255 {
 256         struct rtc_device *rtc = to_rtc_device(file->private_data);
 257         return fasync_helper(fd, file, on, &rtc->async_queue);
 258 }
 259
 260 static struct file_operations rtc_dev_fops = {
 261         .owner          = THIS_MODULE,
 262         .llseek         = no_llseek,
 263         .read           = rtc_dev_read,
 264         .poll           = rtc_dev_poll,
 265         .ioctl          = rtc_dev_ioctl,
 266         .open           = rtc_dev_open,
 267         .release        = rtc_dev_release,
 268         .fasync         = rtc_dev_fasync,
 269 };
 270
 271 /* insertion/removal hooks */
 272
 273 static int rtc_dev_add_device(struct class_device *class_dev,
 274                                 struct class_interface *class_intf)
 275 {
 276         int err = 0;
 277         struct rtc_device *rtc = to_rtc_device(class_dev);
 278
 279         if (rtc->id >= RTC_DEV_MAX) {
 280                 dev_err(class_dev->dev, "too many RTCs\n");
 281                 return -EINVAL;
 282         }
 283
 284         mutex_init(&rtc->char_lock);
 285         spin_lock_init(&rtc->irq_lock);
 286         init_waitqueue_head(&rtc->irq_queue);
 287
 288         cdev_init(&rtc->char_dev, &rtc_dev_fops);
 289         rtc->char_dev.owner = rtc->owner;
 290
 291         if (cdev_add(&rtc->char_dev, MKDEV(MAJOR(rtc_devt), rtc->id), 1)) {
 292                 cdev_del(&rtc->char_dev);
 293                 dev_err(class_dev->dev,
 294                         "failed to add char device %d:%d\n",
 295                         MAJOR(rtc_devt), rtc->id);
 296                 return -ENODEV;
 297         }
 298
 299         rtc->rtc_dev = class_device_create(rtc_dev_class, NULL,
 300                                                 MKDEV(MAJOR(rtc_devt), rtc->id),
 301                                                 class_dev->dev, "rtc%d", rtc->id);
 302         if (IS_ERR(rtc->rtc_dev)) {
 303                 dev_err(class_dev->dev, "cannot create rtc_dev device\n");
 304                 err = PTR_ERR(rtc->rtc_dev);
 305                 goto err_cdev_del;
 306         }
 307
 308         dev_info(class_dev->dev, "rtc intf: dev (%d:%d)\n",
 309                 MAJOR(rtc->rtc_dev->devt),
 310                 MINOR(rtc->rtc_dev->devt));
 311
 312         return 0;
 313
 314 err_cdev_del:
 315
 316         cdev_del(&rtc->char_dev);
 317         return err;
 318 }
 319
 320 static void rtc_dev_remove_device(struct class_device *class_dev,
 321                                         struct class_interface *class_intf)
 322 {
 323         struct rtc_device *rtc = to_rtc_device(class_dev);
 324
 325         if (rtc->rtc_dev) {
 326                 dev_dbg(class_dev->dev, "removing char %d:%d\n",
 327                         MAJOR(rtc->rtc_dev->devt),
 328                         MINOR(rtc->rtc_dev->devt));
 329
 330                 class_device_unregister(rtc->rtc_dev);
 331                 cdev_del(&rtc->char_dev);
 332         }
 333 }
 334
 335 /* interface registration */
 336
 337 static struct class_interface rtc_dev_interface = {
 338         .add = &rtc_dev_add_device,
 339         .remove = &rtc_dev_remove_device,
 340 };
 341
 342 static int __init rtc_dev_init(void)
 343 {
 344         int err;
 345
 346         rtc_dev_class = class_create(THIS_MODULE, "rtc-dev");
 347         if (IS_ERR(rtc_dev_class))
 348                 return PTR_ERR(rtc_dev_class);
 349
 350         err = alloc_chrdev_region(&rtc_devt, 0, RTC_DEV_MAX, "rtc");
 351         if (err < 0) {
 352                 printk(KERN_ERR "%s: failed to allocate char dev region\n",
 353                         __FILE__);
 354                 goto err_destroy_class;
 355         }
 356
 357         err = rtc_interface_register(&rtc_dev_interface);
 358         if (err < 0) {
 359                 printk(KERN_ERR "%s: failed to register the interface\n",
 360                         __FILE__);
 361                 goto err_unregister_chrdev;
 362         }
 363
 364         return 0;
 365
 366 err_unregister_chrdev:
 367         unregister_chrdev_region(rtc_devt, RTC_DEV_MAX);
 368
 369 err_destroy_class:
 370         class_destroy(rtc_dev_class);
 371
 372         return err;
 373 }
 374
 375 static void __exit rtc_dev_exit(void)
 376 {
 377         class_interface_unregister(&rtc_dev_interface);
 378         class_destroy(rtc_dev_class);
 379         unregister_chrdev_region(rtc_devt, RTC_DEV_MAX);
 380 }
 381
 382 module_init(rtc_dev_init);
 383 module_exit(rtc_dev_exit);
 384
 385 MODULE_AUTHOR("Alessandro Zummo <a.zummo@towertech.it>");
 386 MODULE_DESCRIPTION("RTC class dev interface");
 387 MODULE_LICENSE("GPL");