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