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
 251        return 0;
 252}
 253
 254static int pps_cdev_release(struct inode *inode, struct file *file)
 255{
 256        return 0;
 257}
 258
 259/*
 260 * Char device stuff
 261 */
 262
 263static const struct file_operations pps_cdev_fops = {
 264        .owner          = THIS_MODULE,
 265        .llseek         = no_llseek,
 266        .poll           = pps_cdev_poll,
 267        .fasync         = pps_cdev_fasync,
 268        .unlocked_ioctl = pps_cdev_ioctl,
 269        .open           = pps_cdev_open,
 270        .release        = pps_cdev_release,
 271};
 272
 273static void pps_device_destruct(struct device *dev)
 274{
 275        struct pps_device *pps = dev_get_drvdata(dev);
 276
 277        /* release id here to protect others from using it while it's
 278         * still in use */
 279        mutex_lock(&pps_idr_lock);
 280        idr_remove(&pps_idr, pps->id);
 281        mutex_unlock(&pps_idr_lock);
 282
 283        kfree(dev);
 284        kfree(pps);
 285}
 286
 287int pps_register_cdev(struct pps_device *pps)
 288{
 289        int err;
 290        dev_t devt;
 291
 292        mutex_lock(&pps_idr_lock);
 293        /* Get new ID for the new PPS source */
 294        if (idr_pre_get(&pps_idr, GFP_KERNEL) == 0) {
 295                mutex_unlock(&pps_idr_lock);
 296                return -ENOMEM;
 297        }
 298
 299        /* Now really allocate the PPS source.
 300         * After idr_get_new() calling the new source will be freely available
 301         * into the kernel.
 302         */
 303        err = idr_get_new(&pps_idr, pps, &pps->id);
 304        mutex_unlock(&pps_idr_lock);
 305
 306        if (err < 0)
 307                return err;
 308
 309        pps->id &= MAX_IDR_MASK;
 310        if (pps->id >= PPS_MAX_SOURCES) {
 311                pr_err("%s: too many PPS sources in the system\n",
 312                                        pps->info.name);
 313                err = -EBUSY;
 314                goto free_idr;
 315        }
 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        pps->dev->release = pps_device_destruct;
 336
 337        pr_debug("source %s got cdev (%d:%d)\n", pps->info.name,
 338                        MAJOR(pps_devt), pps->id);
 339
 340        return 0;
 341
 342del_cdev:
 343        cdev_del(&pps->cdev);
 344
 345free_idr:
 346        mutex_lock(&pps_idr_lock);
 347        idr_remove(&pps_idr, pps->id);
 348        mutex_unlock(&pps_idr_lock);
 349
 350        return err;
 351}
 352
 353void pps_unregister_cdev(struct pps_device *pps)
 354{
 355        device_destroy(pps_class, pps->dev->devt);
 356        cdev_del(&pps->cdev);
 357}
 358
 359/*
 360 * Module stuff
 361 */
 362
 363static void __exit pps_exit(void)
 364{
 365        class_destroy(pps_class);
 366        unregister_chrdev_region(pps_devt, PPS_MAX_SOURCES);
 367}
 368
 369static int __init pps_init(void)
 370{
 371        int err;
 372
 373        pps_class = class_create(THIS_MODULE, "pps");
 374        if (IS_ERR(pps_class)) {
 375                pr_err("failed to allocate class\n");
 376                return PTR_ERR(pps_class);
 377        }
 378        pps_class->dev_attrs = pps_attrs;
 379
 380        err = alloc_chrdev_region(&pps_devt, 0, PPS_MAX_SOURCES, "pps");
 381        if (err < 0) {
 382                pr_err("failed to allocate char device region\n");
 383                goto remove_class;
 384        }
 385
 386        pr_info("LinuxPPS API ver. %d registered\n", PPS_API_VERS);
 387        pr_info("Software ver. %s - Copyright 2005-2007 Rodolfo Giometti "
 388                "<giometti@linux.it>\n", PPS_VERSION);
 389
 390        return 0;
 391
 392remove_class:
 393        class_destroy(pps_class);
 394
 395        return err;
 396}
 397
 398subsys_initcall(pps_init);
 399module_exit(pps_exit);
 400
 401MODULE_AUTHOR("Rodolfo Giometti <giometti@linux.it>");
 402MODULE_DESCRIPTION("LinuxPPS support (RFC 2783) - ver. " PPS_VERSION);
 403MODULE_LICENSE("GPL");
 404
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