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                 spin_unlock_irq(&pps->lock);
 156
 157                 break;
 158
 159         case PPS_GETCAP:
 160                 dev_dbg(pps->dev, "PPS_GETCAP\n");
 161
 162                 err = put_user(pps->info.mode, iuarg);
 163                 if (err)
 164                         return -EFAULT;
 165
 166                 break;
 167
 168         case PPS_FETCH: {
 169                 struct pps_fdata fdata;
 170
 171                 dev_dbg(pps->dev, "PPS_FETCH\n");
 172
 173                 err = copy_from_user(&fdata, uarg, sizeof(struct pps_fdata));
 174                 if (err)
 175                         return -EFAULT;
 176
 177                 err = pps_cdev_pps_fetch(pps, &fdata);
 178                 if (err)
 179                         return err;
 180
 181                 /* Return the fetched timestamp */
 182                 spin_lock_irq(&pps->lock);
 183
 184                 fdata.info.assert_sequence = pps->assert_sequence;
 185                 fdata.info.clear_sequence = pps->clear_sequence;
 186                 fdata.info.assert_tu = pps->assert_tu;
 187                 fdata.info.clear_tu = pps->clear_tu;
 188                 fdata.info.current_mode = pps->current_mode;
 189
 190                 spin_unlock_irq(&pps->lock);
 191
 192                 err = copy_to_user(uarg, &fdata, sizeof(struct pps_fdata));
 193                 if (err)
 194                         return -EFAULT;
 195
 196                 break;
 197         }
 198         case PPS_KC_BIND: {
 199                 struct pps_bind_args bind_args;
 200
 201                 dev_dbg(pps->dev, "PPS_KC_BIND\n");
 202
 203                 /* Check the capabilities */
 204                 if (!capable(CAP_SYS_TIME))
 205                         return -EPERM;
 206
 207                 if (copy_from_user(&bind_args, uarg,
 208                                         sizeof(struct pps_bind_args)))
 209                         return -EFAULT;
 210
 211                 /* Check for supported capabilities */
 212                 if ((bind_args.edge & ~pps->info.mode) != 0) {
 213                         dev_err(pps->dev, "unsupported capabilities (%x)\n",
 214                                         bind_args.edge);
 215                         return -EINVAL;
 216                 }
 217
 218                 /* Validate parameters roughly */
 219                 if (bind_args.tsformat != PPS_TSFMT_TSPEC ||
 220                                 (bind_args.edge & ~PPS_CAPTUREBOTH) != 0 ||
 221                                 bind_args.consumer != PPS_KC_HARDPPS) {
 222                         dev_err(pps->dev, "invalid kernel consumer bind"
 223                                         " parameters (%x)\n", bind_args.edge);
 224                         return -EINVAL;
 225                 }
 226
 227                 err = pps_kc_bind(pps, &bind_args);
 228                 if (err < 0)
 229                         return err;
 230
 231                 break;
 232         }
 233         default:
 234                 return -ENOTTY;
 235         }
 236
 237         return 0;
 238 }
 239
 240 #ifdef CONFIG_COMPAT
 241 static long pps_cdev_compat_ioctl(struct file *file,
 242                 unsigned int cmd, unsigned long arg)
 243 {
 244         struct pps_device *pps = file->private_data;
 245         void __user *uarg = (void __user *) arg;
 246
 247         cmd = _IOC(_IOC_DIR(cmd), _IOC_TYPE(cmd), _IOC_NR(cmd), sizeof(void *));
 248
 249         if (cmd == PPS_FETCH) {
 250                 struct pps_fdata_compat compat;
 251                 struct pps_fdata fdata;
 252                 int err;
 253
 254                 dev_dbg(pps->dev, "PPS_FETCH\n");
 255
 256                 err = copy_from_user(&compat, uarg, sizeof(struct pps_fdata_compat));
 257                 if (err)
 258                         return -EFAULT;
 259
 260                 memcpy(&fdata.timeout, &compat.timeout,
 261                                         sizeof(struct pps_ktime_compat));
 262
 263                 err = pps_cdev_pps_fetch(pps, &fdata);
 264                 if (err)
 265                         return err;
 266
 267                 /* Return the fetched timestamp */
 268                 spin_lock_irq(&pps->lock);
 269
 270                 compat.info.assert_sequence = pps->assert_sequence;
 271                 compat.info.clear_sequence = pps->clear_sequence;
 272                 compat.info.current_mode = pps->current_mode;
 273
 274                 memcpy(&compat.info.assert_tu, &pps->assert_tu,
 275                                 sizeof(struct pps_ktime_compat));
 276                 memcpy(&compat.info.clear_tu, &pps->clear_tu,
 277                                 sizeof(struct pps_ktime_compat));
 278
 279                 spin_unlock_irq(&pps->lock);
 280
 281                 return copy_to_user(uarg, &compat,
 282                                 sizeof(struct pps_fdata_compat)) ? -EFAULT : 0;
 283         }
 284
 285         return pps_cdev_ioctl(file, cmd, arg);
 286 }
 287 #else
 288 #define pps_cdev_compat_ioctl   NULL
 289 #endif
 290
 291 static int pps_cdev_open(struct inode *inode, struct file *file)
 292 {
 293         struct pps_device *pps = container_of(inode->i_cdev,
 294                                                 struct pps_device, cdev);
 295         file->private_data = pps;
 296         kobject_get(&pps->dev->kobj);
 297         return 0;
 298 }
 299
 300 static int pps_cdev_release(struct inode *inode, struct file *file)
 301 {
 302         struct pps_device *pps = container_of(inode->i_cdev,
 303                                                 struct pps_device, cdev);
 304         kobject_put(&pps->dev->kobj);
 305         return 0;
 306 }
 307
 308 /*
 309  * Char device stuff
 310  */
 311
 312 static const struct file_operations pps_cdev_fops = {
 313         .owner          = THIS_MODULE,
 314         .llseek         = no_llseek,
 315         .poll           = pps_cdev_poll,
 316         .fasync         = pps_cdev_fasync,
 317         .compat_ioctl   = pps_cdev_compat_ioctl,
 318         .unlocked_ioctl = pps_cdev_ioctl,
 319         .open           = pps_cdev_open,
 320         .release        = pps_cdev_release,
 321 };
 322
 323 static void pps_device_destruct(struct device *dev)
 324 {
 325         struct pps_device *pps = dev_get_drvdata(dev);
 326
 327         cdev_del(&pps->cdev);
 328
 329         /* Now we can release the ID for re-use */
 330         pr_debug("deallocating pps%d\n", pps->id);
 331         mutex_lock(&pps_idr_lock);
 332         idr_remove(&pps_idr, pps->id);
 333         mutex_unlock(&pps_idr_lock);
 334
 335         kfree(dev);
 336         kfree(pps);
 337 }
 338
 339 int pps_register_cdev(struct pps_device *pps)
 340 {
 341         int err;
 342         dev_t devt;
 343
 344         mutex_lock(&pps_idr_lock);
 345         /*
 346          * Get new ID for the new PPS source.  After idr_alloc() calling
 347          * the new source will be freely available into the kernel.
 348          */
 349         err = idr_alloc(&pps_idr, pps, 0, PPS_MAX_SOURCES, GFP_KERNEL);
 350         if (err < 0) {
 351                 if (err == -ENOSPC) {
 352                         pr_err("%s: too many PPS sources in the system\n",
 353                                pps->info.name);
 354                         err = -EBUSY;
 355                 }
 356                 goto out_unlock;
 357         }
 358         pps->id = err;
 359         mutex_unlock(&pps_idr_lock);
 360
 361         devt = MKDEV(MAJOR(pps_devt), pps->id);
 362
 363         cdev_init(&pps->cdev, &pps_cdev_fops);
 364         pps->cdev.owner = pps->info.owner;
 365
 366         err = cdev_add(&pps->cdev, devt, 1);
 367         if (err) {
 368                 pr_err("%s: failed to add char device %d:%d\n",
 369                                 pps->info.name, MAJOR(pps_devt), pps->id);
 370                 goto free_idr;
 371         }
 372         pps->dev = device_create(pps_class, pps->info.dev, devt, pps,
 373                                                         "pps%d", pps->id);
 374         if (IS_ERR(pps->dev)) {
 375                 err = PTR_ERR(pps->dev);
 376                 goto del_cdev;
 377         }
 378
 379         /* Override the release function with our own */
 380         pps->dev->release = pps_device_destruct;
 381
 382         pr_debug("source %s got cdev (%d:%d)\n", pps->info.name,
 383                         MAJOR(pps_devt), pps->id);
 384
 385         return 0;
 386
 387 del_cdev:
 388         cdev_del(&pps->cdev);
 389
 390 free_idr:
 391         mutex_lock(&pps_idr_lock);
 392         idr_remove(&pps_idr, pps->id);
 393 out_unlock:
 394         mutex_unlock(&pps_idr_lock);
 395         return err;
 396 }
 397
 398 void pps_unregister_cdev(struct pps_device *pps)
 399 {
 400         pr_debug("unregistering pps%d\n", pps->id);
 401         pps->lookup_cookie = NULL;
 402         device_destroy(pps_class, pps->dev->devt);
 403 }
 404
 405 /*
 406  * Look up a pps device by magic cookie.
 407  * The cookie is usually a pointer to some enclosing device, but this
 408  * code doesn't care; you should never be dereferencing it.
 409  *
 410  * This is a bit of a kludge that is currently used only by the PPS
 411  * serial line discipline.  It may need to be tweaked when a second user
 412  * is found.
 413  *
 414  * There is no function interface for setting the lookup_cookie field.
 415  * It's initialized to NULL when the pps device is created, and if a
 416  * client wants to use it, just fill it in afterward.
 417  *
 418  * The cookie is automatically set to NULL in pps_unregister_source()
 419  * so that it will not be used again, even if the pps device cannot
 420  * be removed from the idr due to pending references holding the minor
 421  * number in use.
 422  */
 423 struct pps_device *pps_lookup_dev(void const *cookie)
 424 {
 425         struct pps_device *pps;
 426         unsigned id;
 427
 428         rcu_read_lock();
 429         idr_for_each_entry(&pps_idr, pps, id)
 430                 if (cookie == pps->lookup_cookie)
 431                         break;
 432         rcu_read_unlock();
 433         return pps;
 434 }
 435 EXPORT_SYMBOL(pps_lookup_dev);
 436
 437 /*
 438  * Module stuff
 439  */
 440
 441 static void __exit pps_exit(void)
 442 {
 443         class_destroy(pps_class);
 444         unregister_chrdev_region(pps_devt, PPS_MAX_SOURCES);
 445 }
 446
 447 static int __init pps_init(void)
 448 {
 449         int err;
 450
 451         pps_class = class_create(THIS_MODULE, "pps");
 452         if (IS_ERR(pps_class)) {
 453                 pr_err("failed to allocate class\n");
 454                 return PTR_ERR(pps_class);
 455         }
 456         pps_class->dev_groups = pps_groups;
 457
 458         err = alloc_chrdev_region(&pps_devt, 0, PPS_MAX_SOURCES, "pps");
 459         if (err < 0) {
 460                 pr_err("failed to allocate char device region\n");
 461                 goto remove_class;
 462         }
 463
 464         pr_info("LinuxPPS API ver. %d registered\n", PPS_API_VERS);
 465         pr_info("Software ver. %s - Copyright 2005-2007 Rodolfo Giometti "
 466                 "<giometti@linux.it>\n", PPS_VERSION);
 467
 468         return 0;
 469
 470 remove_class:
 471         class_destroy(pps_class);
 472
 473         return err;
 474 }
 475
 476 subsys_initcall(pps_init);
 477 module_exit(pps_exit);
 478
 479 MODULE_AUTHOR("Rodolfo Giometti <giometti@linux.it>");
 480 MODULE_DESCRIPTION("LinuxPPS support (RFC 2783) - ver. " PPS_VERSION);
 481 MODULE_LICENSE("GPL");