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 /*
  37  * Local variables
  38  */
  39
  40 static dev_t pps_devt;
  41 static struct class *pps_class;
  42
  43 static DEFINE_MUTEX(pps_idr_lock);
  44 static DEFINE_IDR(pps_idr);
  45
  46 /*
  47  * Char device methods
  48  */
  49
  50 static unsigned int pps_cdev_poll(struct file *file, poll_table *wait)
  51 {
  52         struct pps_device *pps = file->private_data;
  53
  54         poll_wait(file, &pps->queue, wait);
  55
  56         return POLLIN | POLLRDNORM;
  57 }
  58
  59 static int pps_cdev_fasync(int fd, struct file *file, int on)
  60 {
  61         struct pps_device *pps = file->private_data;
  62         return fasync_helper(fd, file, on, &pps->async_queue);
  63 }
  64
  65 static long pps_cdev_ioctl(struct file *file,
  66                 unsigned int cmd, unsigned long arg)
  67 {
  68         struct pps_device *pps = file->private_data;
  69         struct pps_kparams params;
  70         void __user *uarg = (void __user *) arg;
  71         int __user *iuarg = (int __user *) arg;
  72         int err;
  73
  74         switch (cmd) {
  75         case PPS_GETPARAMS:
  76                 dev_dbg(pps->dev, "PPS_GETPARAMS\n");
  77
  78                 spin_lock_irq(&pps->lock);
  79
  80                 /* Get the current parameters */
  81                 params = pps->params;
  82
  83                 spin_unlock_irq(&pps->lock);
  84
  85                 err = copy_to_user(uarg, &params, sizeof(struct pps_kparams));
  86                 if (err)
  87                         return -EFAULT;
  88
  89                 break;
  90
  91         case PPS_SETPARAMS:
  92                 dev_dbg(pps->dev, "PPS_SETPARAMS\n");
  93
  94                 /* Check the capabilities */
  95                 if (!capable(CAP_SYS_TIME))
  96                         return -EPERM;
  97
  98                 err = copy_from_user(&params, uarg, sizeof(struct pps_kparams));
  99                 if (err)
 100                         return -EFAULT;
 101                 if (!(params.mode & (PPS_CAPTUREASSERT | PPS_CAPTURECLEAR))) {
 102                         dev_dbg(pps->dev, "capture mode unspecified (%x)\n",
 103                                                                 params.mode);
 104                         return -EINVAL;
 105                 }
 106
 107                 /* Check for supported capabilities */
 108                 if ((params.mode & ~pps->info.mode) != 0) {
 109                         dev_dbg(pps->dev, "unsupported capabilities (%x)\n",
 110                                                                 params.mode);
 111                         return -EINVAL;
 112                 }
 113
 114                 spin_lock_irq(&pps->lock);
 115
 116                 /* Save the new parameters */
 117                 pps->params = params;
 118
 119                 /* Restore the read only parameters */
 120                 if ((params.mode & (PPS_TSFMT_TSPEC | PPS_TSFMT_NTPFP)) == 0) {
 121                         /* section 3.3 of RFC 2783 interpreted */
 122                         dev_dbg(pps->dev, "time format unspecified (%x)\n",
 123                                                                 params.mode);
 124                         pps->params.mode |= PPS_TSFMT_TSPEC;
 125                 }
 126                 if (pps->info.mode & PPS_CANWAIT)
 127                         pps->params.mode |= PPS_CANWAIT;
 128                 pps->params.api_version = PPS_API_VERS;
 129
 130                 spin_unlock_irq(&pps->lock);
 131
 132                 break;
 133
 134         case PPS_GETCAP:
 135                 dev_dbg(pps->dev, "PPS_GETCAP\n");
 136
 137                 err = put_user(pps->info.mode, iuarg);
 138                 if (err)
 139                         return -EFAULT;
 140
 141                 break;
 142
 143         case PPS_FETCH: {
 144                 struct pps_fdata fdata;
 145                 unsigned int ev;
 146
 147                 dev_dbg(pps->dev, "PPS_FETCH\n");
 148
 149                 err = copy_from_user(&fdata, uarg, sizeof(struct pps_fdata));
 150                 if (err)
 151                         return -EFAULT;
 152
 153                 ev = pps->last_ev;
 154
 155                 /* Manage the timeout */
 156                 if (fdata.timeout.flags & PPS_TIME_INVALID)
 157                         err = wait_event_interruptible(pps->queue,
 158                                         ev != pps->last_ev);
 159                 else {
 160                         unsigned long ticks;
 161
 162                         dev_dbg(pps->dev, "timeout %lld.%09d\n",
 163                                         (long long) fdata.timeout.sec,
 164                                         fdata.timeout.nsec);
 165                         ticks = fdata.timeout.sec * HZ;
 166                         ticks += fdata.timeout.nsec / (NSEC_PER_SEC / HZ);
 167
 168                         if (ticks != 0) {
 169                                 err = wait_event_interruptible_timeout(
 170                                                 pps->queue,
 171                                                 ev != pps->last_ev,
 172                                                 ticks);
 173                                 if (err == 0)
 174                                         return -ETIMEDOUT;
 175                         }
 176                 }
 177
 178                 /* Check for pending signals */
 179                 if (err == -ERESTARTSYS) {
 180                         dev_dbg(pps->dev, "pending signal caught\n");
 181                         return -EINTR;
 182                 }
 183
 184                 /* Return the fetched timestamp */
 185                 spin_lock_irq(&pps->lock);
 186
 187                 fdata.info.assert_sequence = pps->assert_sequence;
 188                 fdata.info.clear_sequence = pps->clear_sequence;
 189                 fdata.info.assert_tu = pps->assert_tu;
 190                 fdata.info.clear_tu = pps->clear_tu;
 191                 fdata.info.current_mode = pps->current_mode;
 192
 193                 spin_unlock_irq(&pps->lock);
 194
 195                 err = copy_to_user(uarg, &fdata, sizeof(struct pps_fdata));
 196                 if (err)
 197                         return -EFAULT;
 198
 199                 break;
 200         }
 201         default:
 202                 return -ENOTTY;
 203                 break;
 204         }
 205
 206         return 0;
 207 }
 208
 209 static int pps_cdev_open(struct inode *inode, struct file *file)
 210 {
 211         struct pps_device *pps = container_of(inode->i_cdev,
 212                                                 struct pps_device, cdev);
 213         file->private_data = pps;
 214
 215         return 0;
 216 }
 217
 218 static int pps_cdev_release(struct inode *inode, struct file *file)
 219 {
 220         return 0;
 221 }
 222
 223 /*
 224  * Char device stuff
 225  */
 226
 227 static const struct file_operations pps_cdev_fops = {
 228         .owner          = THIS_MODULE,
 229         .llseek         = no_llseek,
 230         .poll           = pps_cdev_poll,
 231         .fasync         = pps_cdev_fasync,
 232         .unlocked_ioctl = pps_cdev_ioctl,
 233         .open           = pps_cdev_open,
 234         .release        = pps_cdev_release,
 235 };
 236
 237 static void pps_device_destruct(struct device *dev)
 238 {
 239         struct pps_device *pps = dev_get_drvdata(dev);
 240
 241         /* release id here to protect others from using it while it's
 242          * still in use */
 243         mutex_lock(&pps_idr_lock);
 244         idr_remove(&pps_idr, pps->id);
 245         mutex_unlock(&pps_idr_lock);
 246
 247         kfree(dev);
 248         kfree(pps);
 249 }
 250
 251 int pps_register_cdev(struct pps_device *pps)
 252 {
 253         int err;
 254         dev_t devt;
 255
 256         mutex_lock(&pps_idr_lock);
 257         /* Get new ID for the new PPS source */
 258         if (idr_pre_get(&pps_idr, GFP_KERNEL) == 0) {
 259                 mutex_unlock(&pps_idr_lock);
 260                 return -ENOMEM;
 261         }
 262
 263         /* Now really allocate the PPS source.
 264          * After idr_get_new() calling the new source will be freely available
 265          * into the kernel.
 266          */
 267         err = idr_get_new(&pps_idr, pps, &pps->id);
 268         mutex_unlock(&pps_idr_lock);
 269
 270         if (err < 0)
 271                 return err;
 272
 273         pps->id &= MAX_ID_MASK;
 274         if (pps->id >= PPS_MAX_SOURCES) {
 275                 pr_err("%s: too many PPS sources in the system\n",
 276                                         pps->info.name);
 277                 err = -EBUSY;
 278                 goto free_idr;
 279         }
 280
 281         devt = MKDEV(MAJOR(pps_devt), pps->id);
 282
 283         cdev_init(&pps->cdev, &pps_cdev_fops);
 284         pps->cdev.owner = pps->info.owner;
 285
 286         err = cdev_add(&pps->cdev, devt, 1);
 287         if (err) {
 288                 pr_err("%s: failed to add char device %d:%d\n",
 289                                 pps->info.name, MAJOR(pps_devt), pps->id);
 290                 goto free_idr;
 291         }
 292         pps->dev = device_create(pps_class, pps->info.dev, devt, pps,
 293                                                         "pps%d", pps->id);
 294         if (IS_ERR(pps->dev))
 295                 goto del_cdev;
 296
 297         pps->dev->release = pps_device_destruct;
 298
 299         pr_debug("source %s got cdev (%d:%d)\n", pps->info.name,
 300                         MAJOR(pps_devt), pps->id);
 301
 302         return 0;
 303
 304 del_cdev:
 305         cdev_del(&pps->cdev);
 306
 307 free_idr:
 308         mutex_lock(&pps_idr_lock);
 309         idr_remove(&pps_idr, pps->id);
 310         mutex_unlock(&pps_idr_lock);
 311
 312         return err;
 313 }
 314
 315 void pps_unregister_cdev(struct pps_device *pps)
 316 {
 317         device_destroy(pps_class, pps->dev->devt);
 318         cdev_del(&pps->cdev);
 319 }
 320
 321 /*
 322  * Module stuff
 323  */
 324
 325 static void __exit pps_exit(void)
 326 {
 327         class_destroy(pps_class);
 328         unregister_chrdev_region(pps_devt, PPS_MAX_SOURCES);
 329 }
 330
 331 static int __init pps_init(void)
 332 {
 333         int err;
 334
 335         pps_class = class_create(THIS_MODULE, "pps");
 336         if (!pps_class) {
 337                 pr_err("failed to allocate class\n");
 338                 return -ENOMEM;
 339         }
 340         pps_class->dev_attrs = pps_attrs;
 341
 342         err = alloc_chrdev_region(&pps_devt, 0, PPS_MAX_SOURCES, "pps");
 343         if (err < 0) {
 344                 pr_err("failed to allocate char device region\n");
 345                 goto remove_class;
 346         }
 347
 348         pr_info("LinuxPPS API ver. %d registered\n", PPS_API_VERS);
 349         pr_info("Software ver. %s - Copyright 2005-2007 Rodolfo Giometti "
 350                 "<giometti@linux.it>\n", PPS_VERSION);
 351
 352         return 0;
 353
 354 remove_class:
 355         class_destroy(pps_class);
 356
 357         return err;
 358 }
 359
 360 subsys_initcall(pps_init);
 361 module_exit(pps_exit);
 362
 363 MODULE_AUTHOR("Rodolfo Giometti <giometti@linux.it>");
 364 MODULE_DESCRIPTION("LinuxPPS support (RFC 2783) - ver. " PPS_VERSION);
 365 MODULE_LICENSE("GPL");