v4l2-device.c

Go to the documentation of this file.

/*
    V4L2 device support.

    Copyright (C) 2008  Hans Verkuil <[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/types.h>
#include <linux/ioctl.h>
#include <linux/module.h>
#include <linux/i2c.h>
#include <linux/slab.h>
#if defined(CONFIG_SPI)
#include <linux/spi/spi.h>
#endif
#include <linux/videodev2.h>
#include <media/v4l2-device.h>
#include <media/v4l2-ctrls.h>

int v4l2_device_register(struct device *dev, struct v4l2_device *v4l2_dev)
{
    if (v4l2_dev == NULL)
        return -EINVAL;

    INIT_LIST_HEAD(&v4l2_dev->subdevs);
    spin_lock_init(&v4l2_dev->lock);
    mutex_init(&v4l2_dev->ioctl_lock);
    v4l2_prio_init(&v4l2_dev->prio);
    kref_init(&v4l2_dev->ref);
    get_device(dev);
    v4l2_dev->dev = dev;
    if (dev == NULL) {
        /* If dev == NULL, then name must be filled in by the caller */
        WARN_ON(!v4l2_dev->name[0]);
        return 0;
    }

    /* Set name to driver name + device name if it is empty. */
    if (!v4l2_dev->name[0])
        snprintf(v4l2_dev->name, sizeof(v4l2_dev->name), "%s %s",
            dev->driver->name, dev_name(dev));
    if (!dev_get_drvdata(dev))
        dev_set_drvdata(dev, v4l2_dev);
    return 0;
}
EXPORT_SYMBOL_GPL(v4l2_device_register);

static void v4l2_device_release(struct kref *ref)
{
    struct v4l2_device *v4l2_dev =
        container_of(ref, struct v4l2_device, ref);

    if (v4l2_dev->release)
        v4l2_dev->release(v4l2_dev);
}

int v4l2_device_put(struct v4l2_device *v4l2_dev)
{
    return kref_put(&v4l2_dev->ref, v4l2_device_release);
}
EXPORT_SYMBOL_GPL(v4l2_device_put);

int v4l2_device_set_name(struct v4l2_device *v4l2_dev, const char *basename,
                        atomic_t *instance)
{
    int num = atomic_inc_return(instance) - 1;
    int len = strlen(basename);

    if (basename[len - 1] >= '0' && basename[len - 1] <= '9')
        snprintf(v4l2_dev->name, sizeof(v4l2_dev->name),
                "%s-%d", basename, num);
    else
        snprintf(v4l2_dev->name, sizeof(v4l2_dev->name),
                "%s%d", basename, num);
    return num;
}
EXPORT_SYMBOL_GPL(v4l2_device_set_name);

void v4l2_device_disconnect(struct v4l2_device *v4l2_dev)
{
    if (v4l2_dev->dev == NULL)
        return;

    if (dev_get_drvdata(v4l2_dev->dev) == v4l2_dev)
        dev_set_drvdata(v4l2_dev->dev, NULL);
    put_device(v4l2_dev->dev);
    v4l2_dev->dev = NULL;
}
EXPORT_SYMBOL_GPL(v4l2_device_disconnect);

void v4l2_device_unregister(struct v4l2_device *v4l2_dev)
{
    struct v4l2_subdev *sd, *next;

    if (v4l2_dev == NULL)
        return;
    v4l2_device_disconnect(v4l2_dev);

    /* Unregister subdevs */
    list_for_each_entry_safe(sd, next, &v4l2_dev->subdevs, list) {
        v4l2_device_unregister_subdev(sd);
#if defined(CONFIG_I2C) || (defined(CONFIG_I2C_MODULE) && defined(MODULE))
        if (sd->flags & V4L2_SUBDEV_FL_IS_I2C) {
            struct i2c_client *client = v4l2_get_subdevdata(sd);

            /* We need to unregister the i2c client explicitly.
               We cannot rely on i2c_del_adapter to always
               unregister clients for us, since if the i2c bus
               is a platform bus, then it is never deleted. */
            if (client)
                i2c_unregister_device(client);
            continue;
        }
#endif
#if defined(CONFIG_SPI)
        if (sd->flags & V4L2_SUBDEV_FL_IS_SPI) {
            struct spi_device *spi = v4l2_get_subdevdata(sd);

            if (spi)
                spi_unregister_device(spi);
            continue;
        }
#endif
    }
}
EXPORT_SYMBOL_GPL(v4l2_device_unregister);

int v4l2_device_register_subdev(struct v4l2_device *v4l2_dev,
                struct v4l2_subdev *sd)
{
#if defined(CONFIG_MEDIA_CONTROLLER)
    struct media_entity *entity = &sd->entity;
#endif
    int err;

    /* Check for valid input */
    if (v4l2_dev == NULL || sd == NULL || !sd->name[0])
        return -EINVAL;

    /* Warn if we apparently re-register a subdev */
    WARN_ON(sd->v4l2_dev != NULL);

    if (!try_module_get(sd->owner))
        return -ENODEV;

    sd->v4l2_dev = v4l2_dev;
    if (sd->internal_ops && sd->internal_ops->registered) {
        err = sd->internal_ops->registered(sd);
        if (err) {
            module_put(sd->owner);
            return err;
        }
    }

    /* This just returns 0 if either of the two args is NULL */
    err = v4l2_ctrl_add_handler(v4l2_dev->ctrl_handler, sd->ctrl_handler, NULL);
    if (err) {
        if (sd->internal_ops && sd->internal_ops->unregistered)
            sd->internal_ops->unregistered(sd);
        module_put(sd->owner);
        return err;
    }

#if defined(CONFIG_MEDIA_CONTROLLER)
    /* Register the entity. */
    if (v4l2_dev->mdev) {
        err = media_device_register_entity(v4l2_dev->mdev, entity);
        if (err < 0) {
            if (sd->internal_ops && sd->internal_ops->unregistered)
                sd->internal_ops->unregistered(sd);
            module_put(sd->owner);
            return err;
        }
    }
#endif

    spin_lock(&v4l2_dev->lock);
    list_add_tail(&sd->list, &v4l2_dev->subdevs);
    spin_unlock(&v4l2_dev->lock);

    return 0;
}
EXPORT_SYMBOL_GPL(v4l2_device_register_subdev);

static void v4l2_device_release_subdev_node(struct video_device *vdev)
{
    struct v4l2_subdev *sd = video_get_drvdata(vdev);
    sd->devnode = NULL;
    kfree(vdev);
}

int v4l2_device_register_subdev_nodes(struct v4l2_device *v4l2_dev)
{
    struct video_device *vdev;
    struct v4l2_subdev *sd;
    int err;

    /* Register a device node for every subdev marked with the
     * V4L2_SUBDEV_FL_HAS_DEVNODE flag.
     */
    list_for_each_entry(sd, &v4l2_dev->subdevs, list) {
        if (!(sd->flags & V4L2_SUBDEV_FL_HAS_DEVNODE))
            continue;

        vdev = kzalloc(sizeof(*vdev), GFP_KERNEL);
        if (!vdev) {
            err = -ENOMEM;
            goto clean_up;
        }

        video_set_drvdata(vdev, sd);
        strlcpy(vdev->name, sd->name, sizeof(vdev->name));
        vdev->v4l2_dev = v4l2_dev;
        vdev->fops = &v4l2_subdev_fops;
        vdev->release = v4l2_device_release_subdev_node;
        vdev->ctrl_handler = sd->ctrl_handler;
        err = __video_register_device(vdev, VFL_TYPE_SUBDEV, -1, 1,
                          sd->owner);
        if (err < 0) {
            kfree(vdev);
            goto clean_up;
        }
#if defined(CONFIG_MEDIA_CONTROLLER)
        sd->entity.info.v4l.major = VIDEO_MAJOR;
        sd->entity.info.v4l.minor = vdev->minor;
#endif
        sd->devnode = vdev;
    }
    return 0;

clean_up:
    list_for_each_entry(sd, &v4l2_dev->subdevs, list) {
        if (!sd->devnode)
            break;
        video_unregister_device(sd->devnode);
    }

    return err;
}
EXPORT_SYMBOL_GPL(v4l2_device_register_subdev_nodes);

void v4l2_device_unregister_subdev(struct v4l2_subdev *sd)
{
    struct v4l2_device *v4l2_dev;

    /* return if it isn't registered */
    if (sd == NULL || sd->v4l2_dev == NULL)
        return;

    v4l2_dev = sd->v4l2_dev;

    spin_lock(&v4l2_dev->lock);
    list_del(&sd->list);
    spin_unlock(&v4l2_dev->lock);

    if (sd->internal_ops && sd->internal_ops->unregistered)
        sd->internal_ops->unregistered(sd);
    sd->v4l2_dev = NULL;

#if defined(CONFIG_MEDIA_CONTROLLER)
    if (v4l2_dev->mdev)
        media_device_unregister_entity(&sd->entity);
#endif
    video_unregister_device(sd->devnode);
    module_put(sd->owner);
}
EXPORT_SYMBOL_GPL(v4l2_device_unregister_subdev);