linux/drivers/pps/pps.c
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   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
  42static dev_t pps_devt;
  43static struct class *pps_class;
  44
  45static DEFINE_MUTEX(pps_idr_lock);
  46static DEFINE_IDR(pps_idr);
  47
  48/*
  49 * Char device methods
  50 */
  51
  52static 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
  61static 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
  67static 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
 245static 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
 254static 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
 266static 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
 276static 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
 292int pps_register_cdev(struct pps_device *pps)
 293{
 294        int err;
 295        dev_t devt;
 296
 297        mutex_lock(&pps_idr_lock);
 298        /* Get new ID for the new PPS source */
 299        if (idr_pre_get(&pps_idr, GFP_KERNEL) == 0) {
 300                mutex_unlock(&pps_idr_lock);
 301                return -ENOMEM;
 302        }
 303
 304        /* Now really allocate the PPS source.
 305         * After idr_get_new() calling the new source will be freely available
 306         * into the kernel.
 307         */
 308        err = idr_get_new(&pps_idr, pps, &pps->id);
 309        mutex_unlock(&pps_idr_lock);
 310
 311        if (err < 0)
 312                return err;
 313
 314        pps->id &= MAX_IDR_MASK;
 315        if (pps->id >= PPS_MAX_SOURCES) {
 316                pr_err("%s: too many PPS sources in the system\n",
 317                                        pps->info.name);
 318                err = -EBUSY;
 319                goto free_idr;
 320        }
 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
 348del_cdev:
 349        cdev_del(&pps->cdev);
 350
 351free_idr:
 352        mutex_lock(&pps_idr_lock);
 353        idr_remove(&pps_idr, pps->id);
 354        mutex_unlock(&pps_idr_lock);
 355
 356        return err;
 357}
 358
 359void 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 */
 384struct 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}
 396EXPORT_SYMBOL(pps_lookup_dev);
 397
 398/*
 399 * Module stuff
 400 */
 401
 402static void __exit pps_exit(void)
 403{
 404        class_destroy(pps_class);
 405        unregister_chrdev_region(pps_devt, PPS_MAX_SOURCES);
 406}
 407
 408static 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_attrs = pps_attrs;
 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
 431remove_class:
 432        class_destroy(pps_class);
 433
 434        return err;
 435}
 436
 437subsys_initcall(pps_init);
 438module_exit(pps_exit);
 439
 440MODULE_AUTHOR("Rodolfo Giometti <giometti@linux.it>");
 441MODULE_DESCRIPTION("LinuxPPS support (RFC 2783) - ver. " PPS_VERSION);
 442MODULE_LICENSE("GPL");
 443
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