drivers/pps/pps.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  * PPS core file
   4  *
   5  * Copyright (C) 2005-2009   Rodolfo Giometti <giometti@linux.it>
   6  */
   7
   8 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
   9
  10 #include <linux/kernel.h>
  11 #include <linux/module.h>
  12 #include <linux/init.h>
  13 #include <linux/sched.h>
  14 #include <linux/uaccess.h>
  15 #include <linux/idr.h>
  16 #include <linux/mutex.h>
  17 #include <linux/cdev.h>
  18 #include <linux/poll.h>
  19 #include <linux/pps_kernel.h>
  20 #include <linux/slab.h>
  21
  22 #include "kc.h"
  23
  24 /*
  25  * Local variables
  26  */
  27
  28 static dev_t pps_devt;
  29 static struct class *pps_class;
  30
  31 static DEFINE_MUTEX(pps_idr_lock);
  32 static DEFINE_IDR(pps_idr);
  33
  34 /*
  35  * Char device methods
  36  */
  37
  38 static __poll_t pps_cdev_poll(struct file *file, poll_table *wait)
  39 {
  40         struct pps_device *pps = file->private_data;
  41
  42         poll_wait(file, &pps->queue, wait);
  43
  44         return EPOLLIN | EPOLLRDNORM;
  45 }
  46
  47 static int pps_cdev_fasync(int fd, struct file *file, int on)
  48 {
  49         struct pps_device *pps = file->private_data;
  50         return fasync_helper(fd, file, on, &pps->async_queue);
  51 }
  52
  53 static int pps_cdev_pps_fetch(struct pps_device *pps, struct pps_fdata *fdata)
  54 {
  55         unsigned int ev = pps->last_ev;
  56         int err = 0;
  57
  58         /* Manage the timeout */
  59         if (fdata->timeout.flags & PPS_TIME_INVALID)
  60                 err = wait_event_interruptible(pps->queue,
  61                                 ev != pps->last_ev);
  62         else {
  63                 unsigned long ticks;
  64
  65                 dev_dbg(pps->dev, "timeout %lld.%09d\n",
  66                                 (long long) fdata->timeout.sec,
  67                                 fdata->timeout.nsec);
  68                 ticks = fdata->timeout.sec * HZ;
  69                 ticks += fdata->timeout.nsec / (NSEC_PER_SEC / HZ);
  70
  71                 if (ticks != 0) {
  72                         err = wait_event_interruptible_timeout(
  73                                         pps->queue,
  74                                         ev != pps->last_ev,
  75                                         ticks);
  76                         if (err == 0)
  77                                 return -ETIMEDOUT;
  78                 }
  79         }
  80
  81         /* Check for pending signals */
  82         if (err == -ERESTARTSYS) {
  83                 dev_dbg(pps->dev, "pending signal caught\n");
  84                 return -EINTR;
  85         }
  86
  87         return 0;
  88 }
  89
  90 static long pps_cdev_ioctl(struct file *file,
  91                 unsigned int cmd, unsigned long arg)
  92 {
  93         struct pps_device *pps = file->private_data;
  94         struct pps_kparams params;
  95         void __user *uarg = (void __user *) arg;
  96         int __user *iuarg = (int __user *) arg;
  97         int err;
  98
  99         switch (cmd) {
 100         case PPS_GETPARAMS:
 101                 dev_dbg(pps->dev, "PPS_GETPARAMS\n");
 102
 103                 spin_lock_irq(&pps->lock);
 104
 105                 /* Get the current parameters */
 106                 params = pps->params;
 107
 108                 spin_unlock_irq(&pps->lock);
 109
 110                 err = copy_to_user(uarg, &params, sizeof(struct pps_kparams));
 111                 if (err)
 112                         return -EFAULT;
 113
 114                 break;
 115
 116         case PPS_SETPARAMS:
 117                 dev_dbg(pps->dev, "PPS_SETPARAMS\n");
 118
 119                 /* Check the capabilities */
 120                 if (!capable(CAP_SYS_TIME))
 121                         return -EPERM;
 122
 123                 err = copy_from_user(&params, uarg, sizeof(struct pps_kparams));
 124                 if (err)
 125                         return -EFAULT;
 126                 if (!(params.mode & (PPS_CAPTUREASSERT | PPS_CAPTURECLEAR))) {
 127                         dev_dbg(pps->dev, "capture mode unspecified (%x)\n",
 128                                                                 params.mode);
 129                         return -EINVAL;
 130                 }
 131
 132                 /* Check for supported capabilities */
 133                 if ((params.mode & ~pps->info.mode) != 0) {
 134                         dev_dbg(pps->dev, "unsupported capabilities (%x)\n",
 135                                                                 params.mode);
 136                         return -EINVAL;
 137                 }
 138
 139                 spin_lock_irq(&pps->lock);
 140
 141                 /* Save the new parameters */
 142                 pps->params = params;
 143
 144                 /* Restore the read only parameters */
 145                 if ((params.mode & (PPS_TSFMT_TSPEC | PPS_TSFMT_NTPFP)) == 0) {
 146                         /* section 3.3 of RFC 2783 interpreted */
 147                         dev_dbg(pps->dev, "time format unspecified (%x)\n",
 148                                                                 params.mode);
 149                         pps->params.mode |= PPS_TSFMT_TSPEC;
 150                 }
 151                 if (pps->info.mode & PPS_CANWAIT)
 152                         pps->params.mode |= PPS_CANWAIT;
 153                 pps->params.api_version = PPS_API_VERS;
 154
 155                 /*
 156                  * Clear unused fields of pps_kparams to avoid leaking
 157                  * uninitialized data of the PPS_SETPARAMS caller via
 158                  * PPS_GETPARAMS
 159                  */
 160                 pps->params.assert_off_tu.flags = 0;
 161                 pps->params.clear_off_tu.flags = 0;
 162
 163                 spin_unlock_irq(&pps->lock);
 164
 165                 break;
 166
 167         case PPS_GETCAP:
 168                 dev_dbg(pps->dev, "PPS_GETCAP\n");
 169
 170                 err = put_user(pps->info.mode, iuarg);
 171                 if (err)
 172                         return -EFAULT;
 173
 174                 break;
 175
 176         case PPS_FETCH: {
 177                 struct pps_fdata fdata;
 178
 179                 dev_dbg(pps->dev, "PPS_FETCH\n");
 180
 181                 err = copy_from_user(&fdata, uarg, sizeof(struct pps_fdata));
 182                 if (err)
 183                         return -EFAULT;
 184
 185                 err = pps_cdev_pps_fetch(pps, &fdata);
 186                 if (err)
 187                         return err;
 188
 189                 /* Return the fetched timestamp */
 190                 spin_lock_irq(&pps->lock);
 191
 192                 fdata.info.assert_sequence = pps->assert_sequence;
 193                 fdata.info.clear_sequence = pps->clear_sequence;
 194                 fdata.info.assert_tu = pps->assert_tu;
 195                 fdata.info.clear_tu = pps->clear_tu;
 196                 fdata.info.current_mode = pps->current_mode;
 197
 198                 spin_unlock_irq(&pps->lock);
 199
 200                 err = copy_to_user(uarg, &fdata, sizeof(struct pps_fdata));
 201                 if (err)
 202                         return -EFAULT;
 203
 204                 break;
 205         }
 206         case PPS_KC_BIND: {
 207                 struct pps_bind_args bind_args;
 208
 209                 dev_dbg(pps->dev, "PPS_KC_BIND\n");
 210
 211                 /* Check the capabilities */
 212                 if (!capable(CAP_SYS_TIME))
 213                         return -EPERM;
 214
 215                 if (copy_from_user(&bind_args, uarg,
 216                                         sizeof(struct pps_bind_args)))
 217                         return -EFAULT;
 218
 219                 /* Check for supported capabilities */
 220                 if ((bind_args.edge & ~pps->info.mode) != 0) {
 221                         dev_err(pps->dev, "unsupported capabilities (%x)\n",
 222                                         bind_args.edge);
 223                         return -EINVAL;
 224                 }
 225
 226                 /* Validate parameters roughly */
 227                 if (bind_args.tsformat != PPS_TSFMT_TSPEC ||
 228                                 (bind_args.edge & ~PPS_CAPTUREBOTH) != 0 ||
 229                                 bind_args.consumer != PPS_KC_HARDPPS) {
 230                         dev_err(pps->dev, "invalid kernel consumer bind"
 231                                         " parameters (%x)\n", bind_args.edge);
 232                         return -EINVAL;
 233                 }
 234
 235                 err = pps_kc_bind(pps, &bind_args);
 236                 if (err < 0)
 237                         return err;
 238
 239                 break;
 240         }
 241         default:
 242                 return -ENOTTY;
 243         }
 244
 245         return 0;
 246 }
 247
 248 #ifdef CONFIG_COMPAT
 249 static long pps_cdev_compat_ioctl(struct file *file,
 250                 unsigned int cmd, unsigned long arg)
 251 {
 252
 253         cmd = _IOC(_IOC_DIR(cmd), _IOC_TYPE(cmd), _IOC_NR(cmd), sizeof(void *));
 254
 255 #ifdef CONFIG_X86_64
 256         if (cmd == PPS_FETCH) {
 257                 struct pps_device *pps = file->private_data;
 258                 void __user *uarg = (void __user *) arg;
 259                 struct pps_fdata_compat compat;
 260                 struct pps_fdata fdata;
 261                 int err;
 262
 263                 dev_dbg(pps->dev, "PPS_FETCH\n");
 264
 265                 err = copy_from_user(&compat, uarg, sizeof(struct pps_fdata_compat));
 266                 if (err)
 267                         return -EFAULT;
 268
 269                 memcpy(&fdata.timeout, &compat.timeout,
 270                                         sizeof(struct pps_ktime_compat));
 271
 272                 err = pps_cdev_pps_fetch(pps, &fdata);
 273                 if (err)
 274                         return err;
 275
 276                 /* Return the fetched timestamp */
 277                 spin_lock_irq(&pps->lock);
 278
 279                 compat.info.assert_sequence = pps->assert_sequence;
 280                 compat.info.clear_sequence = pps->clear_sequence;
 281                 compat.info.current_mode = pps->current_mode;
 282
 283                 memcpy(&compat.info.assert_tu, &pps->assert_tu,
 284                                 sizeof(struct pps_ktime_compat));
 285                 memcpy(&compat.info.clear_tu, &pps->clear_tu,
 286                                 sizeof(struct pps_ktime_compat));
 287
 288                 spin_unlock_irq(&pps->lock);
 289
 290                 return copy_to_user(uarg, &compat,
 291                                 sizeof(struct pps_fdata_compat)) ? -EFAULT : 0;
 292         }
 293 #endif
 294
 295         return pps_cdev_ioctl(file, cmd, arg);
 296 }
 297 #else
 298 #define pps_cdev_compat_ioctl   NULL
 299 #endif
 300
 301 static int pps_cdev_open(struct inode *inode, struct file *file)
 302 {
 303         struct pps_device *pps = container_of(inode->i_cdev,
 304                                                 struct pps_device, cdev);
 305         file->private_data = pps;
 306         kobject_get(&pps->dev->kobj);
 307         return 0;
 308 }
 309
 310 static int pps_cdev_release(struct inode *inode, struct file *file)
 311 {
 312         struct pps_device *pps = container_of(inode->i_cdev,
 313                                                 struct pps_device, cdev);
 314         kobject_put(&pps->dev->kobj);
 315         return 0;
 316 }
 317
 318 /*
 319  * Char device stuff
 320  */
 321
 322 static const struct file_operations pps_cdev_fops = {
 323         .owner          = THIS_MODULE,
 324         .llseek         = no_llseek,
 325         .poll           = pps_cdev_poll,
 326         .fasync         = pps_cdev_fasync,
 327         .compat_ioctl   = pps_cdev_compat_ioctl,
 328         .unlocked_ioctl = pps_cdev_ioctl,
 329         .open           = pps_cdev_open,
 330         .release        = pps_cdev_release,
 331 };
 332
 333 static void pps_device_destruct(struct device *dev)
 334 {
 335         struct pps_device *pps = dev_get_drvdata(dev);
 336
 337         cdev_del(&pps->cdev);
 338
 339         /* Now we can release the ID for re-use */
 340         pr_debug("deallocating pps%d\n", pps->id);
 341         mutex_lock(&pps_idr_lock);
 342         idr_remove(&pps_idr, pps->id);
 343         mutex_unlock(&pps_idr_lock);
 344
 345         kfree(dev);
 346         kfree(pps);
 347 }
 348
 349 int pps_register_cdev(struct pps_device *pps)
 350 {
 351         int err;
 352         dev_t devt;
 353
 354         mutex_lock(&pps_idr_lock);
 355         /*
 356          * Get new ID for the new PPS source.  After idr_alloc() calling
 357          * the new source will be freely available into the kernel.
 358          */
 359         err = idr_alloc(&pps_idr, pps, 0, PPS_MAX_SOURCES, GFP_KERNEL);
 360         if (err < 0) {
 361                 if (err == -ENOSPC) {
 362                         pr_err("%s: too many PPS sources in the system\n",
 363                                pps->info.name);
 364                         err = -EBUSY;
 365                 }
 366                 goto out_unlock;
 367         }
 368         pps->id = err;
 369         mutex_unlock(&pps_idr_lock);
 370
 371         devt = MKDEV(MAJOR(pps_devt), pps->id);
 372
 373         cdev_init(&pps->cdev, &pps_cdev_fops);
 374         pps->cdev.owner = pps->info.owner;
 375
 376         err = cdev_add(&pps->cdev, devt, 1);
 377         if (err) {
 378                 pr_err("%s: failed to add char device %d:%d\n",
 379                                 pps->info.name, MAJOR(pps_devt), pps->id);
 380                 goto free_idr;
 381         }
 382         pps->dev = device_create(pps_class, pps->info.dev, devt, pps,
 383                                                         "pps%d", pps->id);
 384         if (IS_ERR(pps->dev)) {
 385                 err = PTR_ERR(pps->dev);
 386                 goto del_cdev;
 387         }
 388
 389         /* Override the release function with our own */
 390         pps->dev->release = pps_device_destruct;
 391
 392         pr_debug("source %s got cdev (%d:%d)\n", pps->info.name,
 393                         MAJOR(pps_devt), pps->id);
 394
 395         return 0;
 396
 397 del_cdev:
 398         cdev_del(&pps->cdev);
 399
 400 free_idr:
 401         mutex_lock(&pps_idr_lock);
 402         idr_remove(&pps_idr, pps->id);
 403 out_unlock:
 404         mutex_unlock(&pps_idr_lock);
 405         return err;
 406 }
 407
 408 void pps_unregister_cdev(struct pps_device *pps)
 409 {
 410         pr_debug("unregistering pps%d\n", pps->id);
 411         pps->lookup_cookie = NULL;
 412         device_destroy(pps_class, pps->dev->devt);
 413 }
 414
 415 /*
 416  * Look up a pps device by magic cookie.
 417  * The cookie is usually a pointer to some enclosing device, but this
 418  * code doesn't care; you should never be dereferencing it.
 419  *
 420  * This is a bit of a kludge that is currently used only by the PPS
 421  * serial line discipline.  It may need to be tweaked when a second user
 422  * is found.
 423  *
 424  * There is no function interface for setting the lookup_cookie field.
 425  * It's initialized to NULL when the pps device is created, and if a
 426  * client wants to use it, just fill it in afterward.
 427  *
 428  * The cookie is automatically set to NULL in pps_unregister_source()
 429  * so that it will not be used again, even if the pps device cannot
 430  * be removed from the idr due to pending references holding the minor
 431  * number in use.
 432  */
 433 struct pps_device *pps_lookup_dev(void const *cookie)
 434 {
 435         struct pps_device *pps;
 436         unsigned id;
 437
 438         rcu_read_lock();
 439         idr_for_each_entry(&pps_idr, pps, id)
 440                 if (cookie == pps->lookup_cookie)
 441                         break;
 442         rcu_read_unlock();
 443         return pps;
 444 }
 445 EXPORT_SYMBOL(pps_lookup_dev);
 446
 447 /*
 448  * Module stuff
 449  */
 450
 451 static void __exit pps_exit(void)
 452 {
 453         class_destroy(pps_class);
 454         unregister_chrdev_region(pps_devt, PPS_MAX_SOURCES);
 455 }
 456
 457 static int __init pps_init(void)
 458 {
 459         int err;
 460
 461         pps_class = class_create("pps");
 462         if (IS_ERR(pps_class)) {
 463                 pr_err("failed to allocate class\n");
 464                 return PTR_ERR(pps_class);
 465         }
 466         pps_class->dev_groups = pps_groups;
 467
 468         err = alloc_chrdev_region(&pps_devt, 0, PPS_MAX_SOURCES, "pps");
 469         if (err < 0) {
 470                 pr_err("failed to allocate char device region\n");
 471                 goto remove_class;
 472         }
 473
 474         pr_info("LinuxPPS API ver. %d registered\n", PPS_API_VERS);
 475         pr_info("Software ver. %s - Copyright 2005-2007 Rodolfo Giometti "
 476                 "<giometti@linux.it>\n", PPS_VERSION);
 477
 478         return 0;
 479
 480 remove_class:
 481         class_destroy(pps_class);
 482
 483         return err;
 484 }
 485
 486 subsys_initcall(pps_init);
 487 module_exit(pps_exit);
 488
 489 MODULE_AUTHOR("Rodolfo Giometti <giometti@linux.it>");
 490 MODULE_DESCRIPTION("LinuxPPS support (RFC 2783) - ver. " PPS_VERSION);
 491 MODULE_LICENSE("GPL");