w1_family.c

Go to the documentation of this file.

/*
 *  w1_family.c
 *
 * Copyright (c) 2004 Evgeniy Polyakov <[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., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
 */

#include <linux/spinlock.h>
#include <linux/list.h>
#include <linux/sched.h>    /* schedule_timeout() */
#include <linux/delay.h>
#include <linux/export.h>

#include "w1_family.h"
#include "w1.h"

DEFINE_SPINLOCK(w1_flock);
static LIST_HEAD(w1_families);

int w1_register_family(struct w1_family *newf)
{
    struct list_head *ent, *n;
    struct w1_family *f;
    int ret = 0;

    spin_lock(&w1_flock);
    list_for_each_safe(ent, n, &w1_families) {
        f = list_entry(ent, struct w1_family, family_entry);

        if (f->fid == newf->fid) {
            ret = -EEXIST;
            break;
        }
    }

    if (!ret) {
        atomic_set(&newf->refcnt, 0);
        list_add_tail(&newf->family_entry, &w1_families);
    }
    spin_unlock(&w1_flock);

    /* check default devices against the new set of drivers */
    w1_reconnect_slaves(newf, 1);

    return ret;
}

void w1_unregister_family(struct w1_family *fent)
{
    struct list_head *ent, *n;
    struct w1_family *f;

    spin_lock(&w1_flock);
    list_for_each_safe(ent, n, &w1_families) {
        f = list_entry(ent, struct w1_family, family_entry);

        if (f->fid == fent->fid) {
            list_del(&fent->family_entry);
            break;
        }
    }
    spin_unlock(&w1_flock);

    /* deatch devices using this family code */
    w1_reconnect_slaves(fent, 0);

    while (atomic_read(&fent->refcnt)) {
        printk(KERN_INFO "Waiting for family %u to become free: refcnt=%d.\n",
                fent->fid, atomic_read(&fent->refcnt));

        if (msleep_interruptible(1000))
            flush_signals(current);
    }
}

/*
 * Should be called under w1_flock held.
 */
struct w1_family * w1_family_registered(u8 fid)
{
    struct list_head *ent, *n;
    struct w1_family *f = NULL;
    int ret = 0;

    list_for_each_safe(ent, n, &w1_families) {
        f = list_entry(ent, struct w1_family, family_entry);

        if (f->fid == fid) {
            ret = 1;
            break;
        }
    }

    return (ret) ? f : NULL;
}

static void __w1_family_put(struct w1_family *f)
{
    atomic_dec(&f->refcnt);
}

void w1_family_put(struct w1_family *f)
{
    spin_lock(&w1_flock);
    __w1_family_put(f);
    spin_unlock(&w1_flock);
}

#if 0
void w1_family_get(struct w1_family *f)
{
    spin_lock(&w1_flock);
    __w1_family_get(f);
    spin_unlock(&w1_flock);
}
#endif  /*  0  */

void __w1_family_get(struct w1_family *f)
{
    smp_mb__before_atomic_inc();
    atomic_inc(&f->refcnt);
    smp_mb__after_atomic_inc();
}

EXPORT_SYMBOL(w1_unregister_family);
EXPORT_SYMBOL(w1_register_family);