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