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                 spin_unlock_irq(&pps->lock);
 133
 134                 break;
 135
 136         case PPS_GETCAP:
 137                 dev_dbg(pps->dev, "PPS_GETCAP\n");
 138
 139                 err = put_user(pps->info.mode, iuarg);
 140                 if (err)
 141                         return -EFAULT;
 142
 143                 break;
 144
 145         case PPS_FETCH: {
 146                 struct pps_fdata fdata;
 147                 unsigned int ev;
 148
 149                 dev_dbg(pps->dev, "PPS_FETCH\n");
 150
 151                 err = copy_from_user(&fdata, uarg, sizeof(struct pps_fdata));
 152                 if (err)
 153                         return -EFAULT;
 154
 155                 if (!(file->f_flags & O_NONBLOCK)) {
 156                         ev = pps->last_ev;
 157
 158                         /* Manage the timeout */
 159                         if (fdata.timeout.flags & PPS_TIME_INVALID)
 160                                 err = wait_event_interruptible(pps->queue,
 161                                                 ev != pps->last_ev);
 162                         else {
 163                                 unsigned long ticks;
 164
 165                                 dev_dbg(pps->dev, "timeout %lld.%09d\n",
 166                                                 (long long) fdata.timeout.sec,
 167                                                 fdata.timeout.nsec);
 168                                 ticks = fdata.timeout.sec * HZ;
 169                                 ticks += fdata.timeout.nsec /
 170                                         (NSEC_PER_SEC / HZ);
 171
 172                                 if (ticks != 0) {
 173                                         err = wait_event_interruptible_timeout(
 174                                                         pps->queue,
 175                                                         ev != pps->last_ev,
 176                                                         ticks);
 177                                         if (err == 0)
 178                                                 return -ETIMEDOUT;
 179                                 }
 180                         }
 181
 182                         /* Check for pending signals */
 183                         if (err == -ERESTARTSYS) {
 184                                 dev_dbg(pps->dev, "pending signal caught\n");
 185                                 return -EINTR;
 186                         }
 187                 }
 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 static int pps_cdev_open(struct inode *inode, struct file *file)
 249 {
 250         struct pps_device *pps = container_of(inode->i_cdev,
 251                                                 struct pps_device, cdev);
 252         file->private_data = pps;
 253         kobject_get(&pps->dev->kobj);
 254         return 0;
 255 }
 256
 257 static int pps_cdev_release(struct inode *inode, struct file *file)
 258 {
 259         struct pps_device *pps = container_of(inode->i_cdev,
 260                                                 struct pps_device, cdev);
 261         kobject_put(&pps->dev->kobj);
 262         return 0;
 263 }
 264
 265 /*
 266  * Char device stuff
 267  */
 268
 269 static const struct file_operations pps_cdev_fops = {
 270         .owner          = THIS_MODULE,
 271         .llseek         = no_llseek,
 272         .poll           = pps_cdev_poll,
 273         .fasync         = pps_cdev_fasync,
 274         .unlocked_ioctl = pps_cdev_ioctl,
 275         .open           = pps_cdev_open,
 276         .release        = pps_cdev_release,
 277 };
 278
 279 static void pps_device_destruct(struct device *dev)
 280 {
 281         struct pps_device *pps = dev_get_drvdata(dev);
 282
 283         cdev_del(&pps->cdev);
 284
 285         /* Now we can release the ID for re-use */
 286         pr_debug("deallocating pps%d\n", pps->id);
 287         mutex_lock(&pps_idr_lock);
 288         idr_remove(&pps_idr, pps->id);
 289         mutex_unlock(&pps_idr_lock);
 290
 291         kfree(dev);
 292         kfree(pps);
 293 }
 294
 295 int pps_register_cdev(struct pps_device *pps)
 296 {
 297         int err;
 298         dev_t devt;
 299
 300         mutex_lock(&pps_idr_lock);
 301         /*
 302          * Get new ID for the new PPS source.  After idr_alloc() calling
 303          * the new source will be freely available into the kernel.
 304          */
 305         err = idr_alloc(&pps_idr, pps, 0, PPS_MAX_SOURCES, GFP_KERNEL);
 306         if (err < 0) {
 307                 if (err == -ENOSPC) {
 308                         pr_err("%s: too many PPS sources in the system\n",
 309                                pps->info.name);
 310                         err = -EBUSY;
 311                 }
 312                 goto out_unlock;
 313         }
 314         pps->id = err;
 315         mutex_unlock(&pps_idr_lock);
 316
 317         devt = MKDEV(MAJOR(pps_devt), pps->id);
 318
 319         cdev_init(&pps->cdev, &pps_cdev_fops);
 320         pps->cdev.owner = pps->info.owner;
 321
 322         err = cdev_add(&pps->cdev, devt, 1);
 323         if (err) {
 324                 pr_err("%s: failed to add char device %d:%d\n",
 325                                 pps->info.name, MAJOR(pps_devt), pps->id);
 326                 goto free_idr;
 327         }
 328         pps->dev = device_create(pps_class, pps->info.dev, devt, pps,
 329                                                         "pps%d", pps->id);
 330         if (IS_ERR(pps->dev)) {
 331                 err = PTR_ERR(pps->dev);
 332                 goto del_cdev;
 333         }
 334
 335         /* Override the release function with our own */
 336         pps->dev->release = pps_device_destruct;
 337
 338         pr_debug("source %s got cdev (%d:%d)\n", pps->info.name,
 339                         MAJOR(pps_devt), pps->id);
 340
 341         return 0;
 342
 343 del_cdev:
 344         cdev_del(&pps->cdev);
 345
 346 free_idr:
 347         mutex_lock(&pps_idr_lock);
 348         idr_remove(&pps_idr, pps->id);
 349 out_unlock:
 350         mutex_unlock(&pps_idr_lock);
 351         return err;
 352 }
 353
 354 void pps_unregister_cdev(struct pps_device *pps)
 355 {
 356         pr_debug("unregistering pps%d\n", pps->id);
 357         pps->lookup_cookie = NULL;
 358         device_destroy(pps_class, pps->dev->devt);
 359 }
 360
 361 /*
 362  * Look up a pps device by magic cookie.
 363  * The cookie is usually a pointer to some enclosing device, but this
 364  * code doesn't care; you should never be dereferencing it.
 365  *
 366  * This is a bit of a kludge that is currently used only by the PPS
 367  * serial line discipline.  It may need to be tweaked when a second user
 368  * is found.
 369  *
 370  * There is no function interface for setting the lookup_cookie field.
 371  * It's initialized to NULL when the pps device is created, and if a
 372  * client wants to use it, just fill it in afterward.
 373  *
 374  * The cookie is automatically set to NULL in pps_unregister_source()
 375  * so that it will not be used again, even if the pps device cannot
 376  * be removed from the idr due to pending references holding the minor
 377  * number in use.
 378  */
 379 struct pps_device *pps_lookup_dev(void const *cookie)
 380 {
 381         struct pps_device *pps;
 382         unsigned id;
 383
 384         rcu_read_lock();
 385         idr_for_each_entry(&pps_idr, pps, id)
 386                 if (cookie == pps->lookup_cookie)
 387                         break;
 388         rcu_read_unlock();
 389         return pps;
 390 }
 391 EXPORT_SYMBOL(pps_lookup_dev);
 392
 393 /*
 394  * Module stuff
 395  */
 396
 397 static void __exit pps_exit(void)
 398 {
 399         class_destroy(pps_class);
 400         unregister_chrdev_region(pps_devt, PPS_MAX_SOURCES);
 401 }
 402
 403 static int __init pps_init(void)
 404 {
 405         int err;
 406
 407         pps_class = class_create(THIS_MODULE, "pps");
 408         if (IS_ERR(pps_class)) {
 409                 pr_err("failed to allocate class\n");
 410                 return PTR_ERR(pps_class);
 411         }
 412         pps_class->dev_groups = pps_groups;
 413
 414         err = alloc_chrdev_region(&pps_devt, 0, PPS_MAX_SOURCES, "pps");
 415         if (err < 0) {
 416                 pr_err("failed to allocate char device region\n");
 417                 goto remove_class;
 418         }
 419
 420         pr_info("LinuxPPS API ver. %d registered\n", PPS_API_VERS);
 421         pr_info("Software ver. %s - Copyright 2005-2007 Rodolfo Giometti "
 422                 "<giometti@linux.it>\n", PPS_VERSION);
 423
 424         return 0;
 425
 426 remove_class:
 427         class_destroy(pps_class);
 428
 429         return err;
 430 }
 431
 432 subsys_initcall(pps_init);
 433 module_exit(pps_exit);
 434
 435 MODULE_AUTHOR("Rodolfo Giometti <giometti@linux.it>");
 436 MODULE_DESCRIPTION("LinuxPPS support (RFC 2783) - ver. " PPS_VERSION);
 437 MODULE_LICENSE("GPL");