pps.c

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/*
 * PPS core file
 *
 *
 * Copyright (C) 2005-2009   Rodolfo Giometti <[email protected]>
 *
 *   This program is free software; you can redistribute it and/or modify
 *   it under the terms of the GNU General Public License as published by
 *   the Free Software Foundation; either version 2 of the License, or
 *   (at your option) any later version.
 *
 *   This program is distributed in the hope that it will be useful,
 *   but WITHOUT ANY WARRANTY; without even the implied warranty of
 *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *   GNU General Public License for more details.
 *
 *   You should have received a copy of the GNU General Public License
 *   along with this program; if not, write to the Free Software
 *   Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 */

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/sched.h>
#include <linux/uaccess.h>
#include <linux/idr.h>
#include <linux/mutex.h>
#include <linux/cdev.h>
#include <linux/poll.h>
#include <linux/pps_kernel.h>
#include <linux/slab.h>

#include "kc.h"

/*
 * Local variables
 */

static dev_t pps_devt;
static struct class *pps_class;

static DEFINE_MUTEX(pps_idr_lock);
static DEFINE_IDR(pps_idr);

/*
 * Char device methods
 */

static unsigned int pps_cdev_poll(struct file *file, poll_table *wait)
{
    struct pps_device *pps = file->private_data;

    poll_wait(file, &pps->queue, wait);

    return POLLIN | POLLRDNORM;
}

static int pps_cdev_fasync(int fd, struct file *file, int on)
{
    struct pps_device *pps = file->private_data;
    return fasync_helper(fd, file, on, &pps->async_queue);
}

static long pps_cdev_ioctl(struct file *file,
        unsigned int cmd, unsigned long arg)
{
    struct pps_device *pps = file->private_data;
    struct pps_kparams params;
    void __user *uarg = (void __user *) arg;
    int __user *iuarg = (int __user *) arg;
    int err;

    switch (cmd) {
    case PPS_GETPARAMS:
        dev_dbg(pps->dev, "PPS_GETPARAMS\n");

        spin_lock_irq(&pps->lock);

        /* Get the current parameters */
        params = pps->params;

        spin_unlock_irq(&pps->lock);

        err = copy_to_user(uarg, &params, sizeof(struct pps_kparams));
        if (err)
            return -EFAULT;

        break;

    case PPS_SETPARAMS:
        dev_dbg(pps->dev, "PPS_SETPARAMS\n");

        /* Check the capabilities */
        if (!capable(CAP_SYS_TIME))
            return -EPERM;

        err = copy_from_user(&params, uarg, sizeof(struct pps_kparams));
        if (err)
            return -EFAULT;
        if (!(params.mode & (PPS_CAPTUREASSERT | PPS_CAPTURECLEAR))) {
            dev_dbg(pps->dev, "capture mode unspecified (%x)\n",
                                params.mode);
            return -EINVAL;
        }

        /* Check for supported capabilities */
        if ((params.mode & ~pps->info.mode) != 0) {
            dev_dbg(pps->dev, "unsupported capabilities (%x)\n",
                                params.mode);
            return -EINVAL;
        }

        spin_lock_irq(&pps->lock);

        /* Save the new parameters */
        pps->params = params;

        /* Restore the read only parameters */
        if ((params.mode & (PPS_TSFMT_TSPEC | PPS_TSFMT_NTPFP)) == 0) {
            /* section 3.3 of RFC 2783 interpreted */
            dev_dbg(pps->dev, "time format unspecified (%x)\n",
                                params.mode);
            pps->params.mode |= PPS_TSFMT_TSPEC;
        }
        if (pps->info.mode & PPS_CANWAIT)
            pps->params.mode |= PPS_CANWAIT;
        pps->params.api_version = PPS_API_VERS;

        spin_unlock_irq(&pps->lock);

        break;

    case PPS_GETCAP:
        dev_dbg(pps->dev, "PPS_GETCAP\n");

        err = put_user(pps->info.mode, iuarg);
        if (err)
            return -EFAULT;

        break;

    case PPS_FETCH: {
        struct pps_fdata fdata;
        unsigned int ev;

        dev_dbg(pps->dev, "PPS_FETCH\n");

        err = copy_from_user(&fdata, uarg, sizeof(struct pps_fdata));
        if (err)
            return -EFAULT;

        ev = pps->last_ev;

        /* Manage the timeout */
        if (fdata.timeout.flags & PPS_TIME_INVALID)
            err = wait_event_interruptible(pps->queue,
                    ev != pps->last_ev);
        else {
            unsigned long ticks;

            dev_dbg(pps->dev, "timeout %lld.%09d\n",
                    (long long) fdata.timeout.sec,
                    fdata.timeout.nsec);
            ticks = fdata.timeout.sec * HZ;
            ticks += fdata.timeout.nsec / (NSEC_PER_SEC / HZ);

            if (ticks != 0) {
                err = wait_event_interruptible_timeout(
                        pps->queue,
                        ev != pps->last_ev,
                        ticks);
                if (err == 0)
                    return -ETIMEDOUT;
            }
        }

        /* Check for pending signals */
        if (err == -ERESTARTSYS) {
            dev_dbg(pps->dev, "pending signal caught\n");
            return -EINTR;
        }

        /* Return the fetched timestamp */
        spin_lock_irq(&pps->lock);

        fdata.info.assert_sequence = pps->assert_sequence;
        fdata.info.clear_sequence = pps->clear_sequence;
        fdata.info.assert_tu = pps->assert_tu;
        fdata.info.clear_tu = pps->clear_tu;
        fdata.info.current_mode = pps->current_mode;

        spin_unlock_irq(&pps->lock);

        err = copy_to_user(uarg, &fdata, sizeof(struct pps_fdata));
        if (err)
            return -EFAULT;

        break;
    }
    case PPS_KC_BIND: {
        struct pps_bind_args bind_args;

        dev_dbg(pps->dev, "PPS_KC_BIND\n");

        /* Check the capabilities */
        if (!capable(CAP_SYS_TIME))
            return -EPERM;

        if (copy_from_user(&bind_args, uarg,
                    sizeof(struct pps_bind_args)))
            return -EFAULT;

        /* Check for supported capabilities */
        if ((bind_args.edge & ~pps->info.mode) != 0) {
            dev_err(pps->dev, "unsupported capabilities (%x)\n",
                    bind_args.edge);
            return -EINVAL;
        }

        /* Validate parameters roughly */
        if (bind_args.tsformat != PPS_TSFMT_TSPEC ||
                (bind_args.edge & ~PPS_CAPTUREBOTH) != 0 ||
                bind_args.consumer != PPS_KC_HARDPPS) {
            dev_err(pps->dev, "invalid kernel consumer bind"
                    " parameters (%x)\n", bind_args.edge);
            return -EINVAL;
        }

        err = pps_kc_bind(pps, &bind_args);
        if (err < 0)
            return err;

        break;
    }
    default:
        return -ENOTTY;
    }

    return 0;
}

static int pps_cdev_open(struct inode *inode, struct file *file)
{
    struct pps_device *pps = container_of(inode->i_cdev,
                        struct pps_device, cdev);
    file->private_data = pps;

    return 0;
}

static int pps_cdev_release(struct inode *inode, struct file *file)
{
    return 0;
}

/*
 * Char device stuff
 */

static const struct file_operations pps_cdev_fops = {
    .owner      = THIS_MODULE,
    .llseek     = no_llseek,
    .poll       = pps_cdev_poll,
    .fasync     = pps_cdev_fasync,
    .unlocked_ioctl = pps_cdev_ioctl,
    .open       = pps_cdev_open,
    .release    = pps_cdev_release,
};

static void pps_device_destruct(struct device *dev)
{
    struct pps_device *pps = dev_get_drvdata(dev);

    /* release id here to protect others from using it while it's
     * still in use */
    mutex_lock(&pps_idr_lock);
    idr_remove(&pps_idr, pps->id);
    mutex_unlock(&pps_idr_lock);

    kfree(dev);
    kfree(pps);
}

int pps_register_cdev(struct pps_device *pps)
{
    int err;
    dev_t devt;

    mutex_lock(&pps_idr_lock);
    /* Get new ID for the new PPS source */
    if (idr_pre_get(&pps_idr, GFP_KERNEL) == 0) {
        mutex_unlock(&pps_idr_lock);
        return -ENOMEM;
    }

    /* Now really allocate the PPS source.
     * After idr_get_new() calling the new source will be freely available
     * into the kernel.
     */
    err = idr_get_new(&pps_idr, pps, &pps->id);
    mutex_unlock(&pps_idr_lock);

    if (err < 0)
        return err;

    pps->id &= MAX_IDR_MASK;
    if (pps->id >= PPS_MAX_SOURCES) {
        pr_err("%s: too many PPS sources in the system\n",
                    pps->info.name);
        err = -EBUSY;
        goto free_idr;
    }

    devt = MKDEV(MAJOR(pps_devt), pps->id);

    cdev_init(&pps->cdev, &pps_cdev_fops);
    pps->cdev.owner = pps->info.owner;

    err = cdev_add(&pps->cdev, devt, 1);
    if (err) {
        pr_err("%s: failed to add char device %d:%d\n",
                pps->info.name, MAJOR(pps_devt), pps->id);
        goto free_idr;
    }
    pps->dev = device_create(pps_class, pps->info.dev, devt, pps,
                            "pps%d", pps->id);
    if (IS_ERR(pps->dev)) {
        err = PTR_ERR(pps->dev);
        goto del_cdev;
    }

    pps->dev->release = pps_device_destruct;

    pr_debug("source %s got cdev (%d:%d)\n", pps->info.name,
            MAJOR(pps_devt), pps->id);

    return 0;

del_cdev:
    cdev_del(&pps->cdev);

free_idr:
    mutex_lock(&pps_idr_lock);
    idr_remove(&pps_idr, pps->id);
    mutex_unlock(&pps_idr_lock);

    return err;
}

void pps_unregister_cdev(struct pps_device *pps)
{
    device_destroy(pps_class, pps->dev->devt);
    cdev_del(&pps->cdev);
}

/*
 * Module stuff
 */

static void __exit pps_exit(void)
{
    class_destroy(pps_class);
    unregister_chrdev_region(pps_devt, PPS_MAX_SOURCES);
}

static int __init pps_init(void)
{
    int err;

    pps_class = class_create(THIS_MODULE, "pps");
    if (IS_ERR(pps_class)) {
        pr_err("failed to allocate class\n");
        return PTR_ERR(pps_class);
    }
    pps_class->dev_attrs = pps_attrs;

    err = alloc_chrdev_region(&pps_devt, 0, PPS_MAX_SOURCES, "pps");
    if (err < 0) {
        pr_err("failed to allocate char device region\n");
        goto remove_class;
    }

    pr_info("LinuxPPS API ver. %d registered\n", PPS_API_VERS);
    pr_info("Software ver. %s - Copyright 2005-2007 Rodolfo Giometti "
        "<[email protected]>\n", PPS_VERSION);

    return 0;

remove_class:
    class_destroy(pps_class);

    return err;
}

subsys_initcall(pps_init);
module_exit(pps_exit);

MODULE_AUTHOR("Rodolfo Giometti <[email protected]>");
MODULE_DESCRIPTION("LinuxPPS support (RFC 2783) - ver. " PPS_VERSION);
MODULE_LICENSE("GPL");