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