drivers/pps/pps.c

   1 /*
   2  * PPS core file
   3  *
   4  *
   5  * Copyright (C) 2005-2009   Rodolfo Giometti <giometti@linux.it>
   6  *
   7  *   This program is free software; you can redistribute it and/or modify
   8  *   it under the terms of the GNU General Public License as published by
   9  *   the Free Software Foundation; either version 2 of the License, or
  10  *   (at your option) any later version.
  11  *
  12  *   This program is distributed in the hope that it will be useful,
  13  *   but WITHOUT ANY WARRANTY; without even the implied warranty of
  14  *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15  *   GNU General Public License for more details.
  16  *
  17  *   You should have received a copy of the GNU General Public License
  18  *   along with this program; if not, write to the Free Software
  19  *   Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  20  */
  21
  22 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  23
  24 #include <linux/kernel.h>
  25 #include <linux/module.h>
  26 #include <linux/init.h>
  27 #include <linux/sched.h>
  28 #include <linux/uaccess.h>
  29 #include <linux/idr.h>
  30 #include <linux/mutex.h>
  31 #include <linux/cdev.h>
  32 #include <linux/poll.h>
  33 #include <linux/pps_kernel.h>
  34 #include <linux/slab.h>
  35
  36 #include "kc.h"
  37
  38 /*
  39  * Local variables
  40  */
  41
  42 static dev_t pps_devt;
  43 static struct class *pps_class;
  44
  45 static DEFINE_MUTEX(pps_idr_lock);
  46 static DEFINE_IDR(pps_idr);
  47
  48 /*
  49  * Char device methods
  50  */
  51
  52 static __poll_t pps_cdev_poll(struct file *file, poll_table *wait)
  53 {
  54         struct pps_device *pps = file->private_data;
  55
  56         poll_wait(file, &pps->queue, wait);
  57
  58         return EPOLLIN | EPOLLRDNORM;
  59 }
  60
  61 static int pps_cdev_fasync(int fd, struct file *file, int on)
  62 {
  63         struct pps_device *pps = file->private_data;
  64         return fasync_helper(fd, file, on, &pps->async_queue);
  65 }
  66
  67 static int pps_cdev_pps_fetch(struct pps_device *pps, struct pps_fdata *fdata)
  68 {
  69         unsigned int ev = pps->last_ev;
  70         int err = 0;
  71
  72         /* Manage the timeout */
  73         if (fdata->timeout.flags & PPS_TIME_INVALID)
  74                 err = wait_event_interruptible(pps->queue,
  75                                 ev != pps->last_ev);
  76         else {
  77                 unsigned long ticks;
  78
  79                 dev_dbg(pps->dev, "timeout %lld.%09d\n",
  80                                 (long long) fdata->timeout.sec,
  81                                 fdata->timeout.nsec);
  82                 ticks = fdata->timeout.sec * HZ;
  83                 ticks += fdata->timeout.nsec / (NSEC_PER_SEC / HZ);
  84
  85                 if (ticks != 0) {
  86                         err = wait_event_interruptible_timeout(
  87                                         pps->queue,
  88                                         ev != pps->last_ev,
  89                                         ticks);
  90                         if (err == 0)
  91                                 return -ETIMEDOUT;
  92                 }
  93         }
  94
  95         /* Check for pending signals */
  96         if (err == -ERESTARTSYS) {
  97                 dev_dbg(pps->dev, "pending signal caught\n");
  98                 return -EINTR;
  99         }
 100
 101         return 0;
 102 }
 103
 104 static long pps_cdev_ioctl(struct file *file,
 105                 unsigned int cmd, unsigned long arg)
 106 {
 107         struct pps_device *pps = file->private_data;
 108         struct pps_kparams params;
 109         void __user *uarg = (void __user *) arg;
 110         int __user *iuarg = (int __user *) arg;
 111         int err;
 112
 113         switch (cmd) {
 114         case PPS_GETPARAMS:
 115                 dev_dbg(pps->dev, "PPS_GETPARAMS\n");
 116
 117                 spin_lock_irq(&pps->lock);
 118
 119                 /* Get the current parameters */
 120                 params = pps->params;
 121
 122                 spin_unlock_irq(&pps->lock);
 123
 124                 err = copy_to_user(uarg, &params, sizeof(struct pps_kparams));
 125                 if (err)
 126                         return -EFAULT;
 127
 128                 break;
 129
 130         case PPS_SETPARAMS:
 131                 dev_dbg(pps->dev, "PPS_SETPARAMS\n");
 132
 133                 /* Check the capabilities */
 134                 if (!capable(CAP_SYS_TIME))
 135                         return -EPERM;
 136
 137                 err = copy_from_user(&params, uarg, sizeof(struct pps_kparams));
 138                 if (err)
 139                         return -EFAULT;
 140                 if (!(params.mode & (PPS_CAPTUREASSERT | PPS_CAPTURECLEAR))) {
 141                         dev_dbg(pps->dev, "capture mode unspecified (%x)\n",
 142                                                                 params.mode);
 143                         return -EINVAL;
 144                 }
 145
 146                 /* Check for supported capabilities */
 147                 if ((params.mode & ~pps->info.mode) != 0) {
 148                         dev_dbg(pps->dev, "unsupported capabilities (%x)\n",
 149                                                                 params.mode);
 150                         return -EINVAL;
 151                 }
 152
 153                 spin_lock_irq(&pps->lock);
 154
 155                 /* Save the new parameters */
 156                 pps->params = params;
 157
 158                 /* Restore the read only parameters */
 159                 if ((params.mode & (PPS_TSFMT_TSPEC | PPS_TSFMT_NTPFP)) == 0) {
 160                         /* section 3.3 of RFC 2783 interpreted */
 161                         dev_dbg(pps->dev, "time format unspecified (%x)\n",
 162                                                                 params.mode);
 163                         pps->params.mode |= PPS_TSFMT_TSPEC;
 164                 }
 165                 if (pps->info.mode & PPS_CANWAIT)
 166                         pps->params.mode |= PPS_CANWAIT;
 167                 pps->params.api_version = PPS_API_VERS;
 168
 169                 /*
 170                  * Clear unused fields of pps_kparams to avoid leaking
 171                  * uninitialized data of the PPS_SETPARAMS caller via
 172                  * PPS_GETPARAMS
 173                  */
 174                 pps->params.assert_off_tu.flags = 0;
 175                 pps->params.clear_off_tu.flags = 0;
 176
 177                 spin_unlock_irq(&pps->lock);
 178
 179                 break;
 180
 181         case PPS_GETCAP:
 182                 dev_dbg(pps->dev, "PPS_GETCAP\n");
 183
 184                 err = put_user(pps->info.mode, iuarg);
 185                 if (err)
 186                         return -EFAULT;
 187
 188                 break;
 189
 190         case PPS_FETCH: {
 191                 struct pps_fdata fdata;
 192
 193                 dev_dbg(pps->dev, "PPS_FETCH\n");
 194
 195                 err = copy_from_user(&fdata, uarg, sizeof(struct pps_fdata));
 196                 if (err)
 197                         return -EFAULT;
 198
 199                 err = pps_cdev_pps_fetch(pps, &fdata);
 200                 if (err)
 201                         return err;
 202
 203                 /* Return the fetched timestamp */
 204                 spin_lock_irq(&pps->lock);
 205
 206                 fdata.info.assert_sequence = pps->assert_sequence;
 207                 fdata.info.clear_sequence = pps->clear_sequence;
 208                 fdata.info.assert_tu = pps->assert_tu;
 209                 fdata.info.clear_tu = pps->clear_tu;
 210                 fdata.info.current_mode = pps->current_mode;
 211
 212                 spin_unlock_irq(&pps->lock);
 213
 214                 err = copy_to_user(uarg, &fdata, sizeof(struct pps_fdata));
 215                 if (err)
 216                         return -EFAULT;
 217
 218                 break;
 219         }
 220         case PPS_KC_BIND: {
 221                 struct pps_bind_args bind_args;
 222
 223                 dev_dbg(pps->dev, "PPS_KC_BIND\n");
 224
 225                 /* Check the capabilities */
 226                 if (!capable(CAP_SYS_TIME))
 227                         return -EPERM;
 228
 229                 if (copy_from_user(&bind_args, uarg,
 230                                         sizeof(struct pps_bind_args)))
 231                         return -EFAULT;
 232
 233                 /* Check for supported capabilities */
 234                 if ((bind_args.edge & ~pps->info.mode) != 0) {
 235                         dev_err(pps->dev, "unsupported capabilities (%x)\n",
 236                                         bind_args.edge);
 237                         return -EINVAL;
 238                 }
 239
 240                 /* Validate parameters roughly */
 241                 if (bind_args.tsformat != PPS_TSFMT_TSPEC ||
 242                                 (bind_args.edge & ~PPS_CAPTUREBOTH) != 0 ||
 243                                 bind_args.consumer != PPS_KC_HARDPPS) {
 244                         dev_err(pps->dev, "invalid kernel consumer bind"
 245                                         " parameters (%x)\n", bind_args.edge);
 246                         return -EINVAL;
 247                 }
 248
 249                 err = pps_kc_bind(pps, &bind_args);
 250                 if (err < 0)
 251                         return err;
 252
 253                 break;
 254         }
 255         default:
 256                 return -ENOTTY;
 257         }
 258
 259         return 0;
 260 }
 261
 262 #ifdef CONFIG_COMPAT
 263 static long pps_cdev_compat_ioctl(struct file *file,
 264                 unsigned int cmd, unsigned long arg)
 265 {
 266         struct pps_device *pps = file->private_data;
 267         void __user *uarg = (void __user *) arg;
 268
 269         cmd = _IOC(_IOC_DIR(cmd), _IOC_TYPE(cmd), _IOC_NR(cmd), sizeof(void *));
 270
 271         if (cmd == PPS_FETCH) {
 272                 struct pps_fdata_compat compat;
 273                 struct pps_fdata fdata;
 274                 int err;
 275
 276                 dev_dbg(pps->dev, "PPS_FETCH\n");
 277
 278                 err = copy_from_user(&compat, uarg, sizeof(struct pps_fdata_compat));
 279                 if (err)
 280                         return -EFAULT;
 281
 282                 memcpy(&fdata.timeout, &compat.timeout,
 283                                         sizeof(struct pps_ktime_compat));
 284
 285                 err = pps_cdev_pps_fetch(pps, &fdata);
 286                 if (err)
 287                         return err;
 288
 289                 /* Return the fetched timestamp */
 290                 spin_lock_irq(&pps->lock);
 291
 292                 compat.info.assert_sequence = pps->assert_sequence;
 293                 compat.info.clear_sequence = pps->clear_sequence;
 294                 compat.info.current_mode = pps->current_mode;
 295
 296                 memcpy(&compat.info.assert_tu, &pps->assert_tu,
 297                                 sizeof(struct pps_ktime_compat));
 298                 memcpy(&compat.info.clear_tu, &pps->clear_tu,
 299                                 sizeof(struct pps_ktime_compat));
 300
 301                 spin_unlock_irq(&pps->lock);
 302
 303                 return copy_to_user(uarg, &compat,
 304                                 sizeof(struct pps_fdata_compat)) ? -EFAULT : 0;
 305         }
 306
 307         return pps_cdev_ioctl(file, cmd, arg);
 308 }
 309 #else
 310 #define pps_cdev_compat_ioctl   NULL
 311 #endif
 312
 313 static int pps_cdev_open(struct inode *inode, struct file *file)
 314 {
 315         struct pps_device *pps = container_of(inode->i_cdev,
 316                                                 struct pps_device, cdev);
 317         file->private_data = pps;
 318         kobject_get(&pps->dev->kobj);
 319         return 0;
 320 }
 321
 322 static int pps_cdev_release(struct inode *inode, struct file *file)
 323 {
 324         struct pps_device *pps = container_of(inode->i_cdev,
 325                                                 struct pps_device, cdev);
 326         kobject_put(&pps->dev->kobj);
 327         return 0;
 328 }
 329
 330 /*
 331  * Char device stuff
 332  */
 333
 334 static const struct file_operations pps_cdev_fops = {
 335         .owner          = THIS_MODULE,
 336         .llseek         = no_llseek,
 337         .poll           = pps_cdev_poll,
 338         .fasync         = pps_cdev_fasync,
 339         .compat_ioctl   = pps_cdev_compat_ioctl,
 340         .unlocked_ioctl = pps_cdev_ioctl,
 341         .open           = pps_cdev_open,
 342         .release        = pps_cdev_release,
 343 };
 344
 345 static void pps_device_destruct(struct device *dev)
 346 {
 347         struct pps_device *pps = dev_get_drvdata(dev);
 348
 349         cdev_del(&pps->cdev);
 350
 351         /* Now we can release the ID for re-use */
 352         pr_debug("deallocating pps%d\n", pps->id);
 353         mutex_lock(&pps_idr_lock);
 354         idr_remove(&pps_idr, pps->id);
 355         mutex_unlock(&pps_idr_lock);
 356
 357         kfree(dev);
 358         kfree(pps);
 359 }
 360
 361 int pps_register_cdev(struct pps_device *pps)
 362 {
 363         int err;
 364         dev_t devt;
 365
 366         mutex_lock(&pps_idr_lock);
 367         /*
 368          * Get new ID for the new PPS source.  After idr_alloc() calling
 369          * the new source will be freely available into the kernel.
 370          */
 371         err = idr_alloc(&pps_idr, pps, 0, PPS_MAX_SOURCES, GFP_KERNEL);
 372         if (err < 0) {
 373                 if (err == -ENOSPC) {
 374                         pr_err("%s: too many PPS sources in the system\n",
 375                                pps->info.name);
 376                         err = -EBUSY;
 377                 }
 378                 goto out_unlock;
 379         }
 380         pps->id = err;
 381         mutex_unlock(&pps_idr_lock);
 382
 383         devt = MKDEV(MAJOR(pps_devt), pps->id);
 384
 385         cdev_init(&pps->cdev, &pps_cdev_fops);
 386         pps->cdev.owner = pps->info.owner;
 387
 388         err = cdev_add(&pps->cdev, devt, 1);
 389         if (err) {
 390                 pr_err("%s: failed to add char device %d:%d\n",
 391                                 pps->info.name, MAJOR(pps_devt), pps->id);
 392                 goto free_idr;
 393         }
 394         pps->dev = device_create(pps_class, pps->info.dev, devt, pps,
 395                                                         "pps%d", pps->id);
 396         if (IS_ERR(pps->dev)) {
 397                 err = PTR_ERR(pps->dev);
 398                 goto del_cdev;
 399         }
 400
 401         /* Override the release function with our own */
 402         pps->dev->release = pps_device_destruct;
 403
 404         pr_debug("source %s got cdev (%d:%d)\n", pps->info.name,
 405                         MAJOR(pps_devt), pps->id);
 406
 407         return 0;
 408
 409 del_cdev:
 410         cdev_del(&pps->cdev);
 411
 412 free_idr:
 413         mutex_lock(&pps_idr_lock);
 414         idr_remove(&pps_idr, pps->id);
 415 out_unlock:
 416         mutex_unlock(&pps_idr_lock);
 417         return err;
 418 }
 419
 420 void pps_unregister_cdev(struct pps_device *pps)
 421 {
 422         pr_debug("unregistering pps%d\n", pps->id);
 423         pps->lookup_cookie = NULL;
 424         device_destroy(pps_class, pps->dev->devt);
 425 }
 426
 427 /*
 428  * Look up a pps device by magic cookie.
 429  * The cookie is usually a pointer to some enclosing device, but this
 430  * code doesn't care; you should never be dereferencing it.
 431  *
 432  * This is a bit of a kludge that is currently used only by the PPS
 433  * serial line discipline.  It may need to be tweaked when a second user
 434  * is found.
 435  *
 436  * There is no function interface for setting the lookup_cookie field.
 437  * It's initialized to NULL when the pps device is created, and if a
 438  * client wants to use it, just fill it in afterward.
 439  *
 440  * The cookie is automatically set to NULL in pps_unregister_source()
 441  * so that it will not be used again, even if the pps device cannot
 442  * be removed from the idr due to pending references holding the minor
 443  * number in use.
 444  */
 445 struct pps_device *pps_lookup_dev(void const *cookie)
 446 {
 447         struct pps_device *pps;
 448         unsigned id;
 449
 450         rcu_read_lock();
 451         idr_for_each_entry(&pps_idr, pps, id)
 452                 if (cookie == pps->lookup_cookie)
 453                         break;
 454         rcu_read_unlock();
 455         return pps;
 456 }
 457 EXPORT_SYMBOL(pps_lookup_dev);
 458
 459 /*
 460  * Module stuff
 461  */
 462
 463 static void __exit pps_exit(void)
 464 {
 465         class_destroy(pps_class);
 466         unregister_chrdev_region(pps_devt, PPS_MAX_SOURCES);
 467 }
 468
 469 static int __init pps_init(void)
 470 {
 471         int err;
 472
 473         pps_class = class_create(THIS_MODULE, "pps");
 474         if (IS_ERR(pps_class)) {
 475                 pr_err("failed to allocate class\n");
 476                 return PTR_ERR(pps_class);
 477         }
 478         pps_class->dev_groups = pps_groups;
 479
 480         err = alloc_chrdev_region(&pps_devt, 0, PPS_MAX_SOURCES, "pps");
 481         if (err < 0) {
 482                 pr_err("failed to allocate char device region\n");
 483                 goto remove_class;
 484         }
 485
 486         pr_info("LinuxPPS API ver. %d registered\n", PPS_API_VERS);
 487         pr_info("Software ver. %s - Copyright 2005-2007 Rodolfo Giometti "
 488                 "<giometti@linux.it>\n", PPS_VERSION);
 489
 490         return 0;
 491
 492 remove_class:
 493         class_destroy(pps_class);
 494
 495         return err;
 496 }
 497
 498 subsys_initcall(pps_init);
 499 module_exit(pps_exit);
 500
 501 MODULE_AUTHOR("Rodolfo Giometti <giometti@linux.it>");
 502 MODULE_DESCRIPTION("LinuxPPS support (RFC 2783) - ver. " PPS_VERSION);
 503 MODULE_LICENSE("GPL");