v4l2-int-device.c

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/*
 * drivers/media/video/v4l2-int-device.c
 *
 * V4L2 internal ioctl interface.
 *
 * Copyright (C) 2007 Nokia Corporation.
 *
 * Contact: Sakari Ailus <[email protected]>
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * version 2 as published by the Free Software Foundation.
 *
 * 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., 51 Franklin St, Fifth Floor, Boston, MA
 * 02110-1301 USA
 */

#include <linux/kernel.h>
#include <linux/list.h>
#include <linux/sort.h>
#include <linux/string.h>
#include <linux/module.h>

#include <media/v4l2-int-device.h>

static DEFINE_MUTEX(mutex);
static LIST_HEAD(int_list);

void v4l2_int_device_try_attach_all(void)
{
    struct v4l2_int_device *m, *s;

    list_for_each_entry(m, &int_list, head) {
        if (m->type != v4l2_int_type_master)
            continue;

        list_for_each_entry(s, &int_list, head) {
            if (s->type != v4l2_int_type_slave)
                continue;

            /* Slave is connected? */
            if (s->u.slave->master)
                continue;

            /* Slave wants to attach to master? */
            if (s->u.slave->attach_to[0] != 0
                && strncmp(m->name, s->u.slave->attach_to,
                       V4L2NAMESIZE))
                continue;

            if (!try_module_get(m->module))
                continue;

            s->u.slave->master = m;
            if (m->u.master->attach(s)) {
                s->u.slave->master = NULL;
                module_put(m->module);
                continue;
            }
        }
    }
}
EXPORT_SYMBOL_GPL(v4l2_int_device_try_attach_all);

static int ioctl_sort_cmp(const void *a, const void *b)
{
    const struct v4l2_int_ioctl_desc *d1 = a, *d2 = b;

    if (d1->num > d2->num)
        return 1;

    if (d1->num < d2->num)
        return -1;

    return 0;
}

int v4l2_int_device_register(struct v4l2_int_device *d)
{
    if (d->type == v4l2_int_type_slave)
        sort(d->u.slave->ioctls, d->u.slave->num_ioctls,
             sizeof(struct v4l2_int_ioctl_desc),
             &ioctl_sort_cmp, NULL);
    mutex_lock(&mutex);
    list_add(&d->head, &int_list);
    v4l2_int_device_try_attach_all();
    mutex_unlock(&mutex);

    return 0;
}
EXPORT_SYMBOL_GPL(v4l2_int_device_register);

void v4l2_int_device_unregister(struct v4l2_int_device *d)
{
    mutex_lock(&mutex);
    list_del(&d->head);
    if (d->type == v4l2_int_type_slave
        && d->u.slave->master != NULL) {
        d->u.slave->master->u.master->detach(d);
        module_put(d->u.slave->master->module);
        d->u.slave->master = NULL;
    }
    mutex_unlock(&mutex);
}
EXPORT_SYMBOL_GPL(v4l2_int_device_unregister);

/* Adapted from search_extable in extable.c. */
static v4l2_int_ioctl_func *find_ioctl(struct v4l2_int_slave *slave, int cmd,
                       v4l2_int_ioctl_func *no_such_ioctl)
{
    const struct v4l2_int_ioctl_desc *first = slave->ioctls;
    const struct v4l2_int_ioctl_desc *last =
        first + slave->num_ioctls - 1;

    while (first <= last) {
        const struct v4l2_int_ioctl_desc *mid;

        mid = (last - first) / 2 + first;

        if (mid->num < cmd)
            first = mid + 1;
        else if (mid->num > cmd)
            last = mid - 1;
        else
            return mid->func;
    }

    return no_such_ioctl;
}

static int no_such_ioctl_0(struct v4l2_int_device *d)
{
    return -ENOIOCTLCMD;
}

int v4l2_int_ioctl_0(struct v4l2_int_device *d, int cmd)
{
    return ((v4l2_int_ioctl_func_0 *)
        find_ioctl(d->u.slave, cmd,
               (v4l2_int_ioctl_func *)no_such_ioctl_0))(d);
}
EXPORT_SYMBOL_GPL(v4l2_int_ioctl_0);

static int no_such_ioctl_1(struct v4l2_int_device *d, void *arg)
{
    return -ENOIOCTLCMD;
}

int v4l2_int_ioctl_1(struct v4l2_int_device *d, int cmd, void *arg)
{
    return ((v4l2_int_ioctl_func_1 *)
        find_ioctl(d->u.slave, cmd,
               (v4l2_int_ioctl_func *)no_such_ioctl_1))(d, arg);
}
EXPORT_SYMBOL_GPL(v4l2_int_ioctl_1);

MODULE_LICENSE("GPL");