// SPDX-License-Identifier: GPL-2.0-or-later
/*
    V4L2 device support.

    Copyright (C) 2008  Hans Verkuil <hverkuil@xs4all.nl>

 */

#include <linux/types.h>
#include <linux/ioctl.h>
#include <linux/module.h>
#include <linux/slab.h>
#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);
        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 */
                if (WARN_ON(!v4l2_dev->name[0]))
                        return -EINVAL;
                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;

        /* Just return if v4l2_dev is NULL or if it was already
         * unregistered before. */
        if (v4l2_dev == NULL || !v4l2_dev->name[0])
                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 (sd->flags & V4L2_SUBDEV_FL_IS_I2C)
                        v4l2_i2c_subdev_unregister(sd);
                else if (sd->flags & V4L2_SUBDEV_FL_IS_SPI)
                        v4l2_spi_subdev_unregister(sd);
        }
        /* Mark as unregistered, thus preventing duplicate unregistrations */
        v4l2_dev->name[0] = '\0';
}
EXPORT_SYMBOL_GPL(v4l2_device_unregister);

int v4l2_device_register_subdev(struct v4l2_device *v4l2_dev,
                                struct v4l2_subdev *sd)
{
        int err;

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

        /*
         * The reason to acquire the module here is to avoid unloading
         * a module of sub-device which is registered to a media
         * device. To make it possible to unload modules for media
         * devices that also register sub-devices, do not
         * try_module_get() such sub-device owners.
         */
        sd->owner_v4l2_dev = v4l2_dev->dev && v4l2_dev->dev->driver &&
                sd->owner == v4l2_dev->dev->driver->owner;

        if (!sd->owner_v4l2_dev && !try_module_get(sd->owner))
                return -ENODEV;

        sd->v4l2_dev = v4l2_dev;
        /* 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, true);
        if (err)
                goto error_module;

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

        if (sd->internal_ops && sd->internal_ops->registered) {
                err = sd->internal_ops->registered(sd);
                if (err)
                        goto error_unregister;
        }

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

        return 0;

error_unregister:
#if defined(CONFIG_MEDIA_CONTROLLER)
        media_device_unregister_entity(&sd->entity);
#endif
error_module:
        if (!sd->owner_v4l2_dev)
                module_put(sd->owner);
        sd->v4l2_dev = NULL;
        return err;
}
EXPORT_SYMBOL_GPL(v4l2_device_register_subdev);

static void v4l2_subdev_release(struct v4l2_subdev *sd)
{
        struct module *owner = !sd->owner_v4l2_dev ? sd->owner : NULL;

        if (sd->internal_ops && sd->internal_ops->release)
                sd->internal_ops->release(sd);
        sd->devnode = NULL;
        module_put(owner);
}

static void v4l2_device_release_subdev_node(struct video_device *vdev)
{
        v4l2_subdev_release(video_get_drvdata(vdev));
        kfree(vdev);
}

int __v4l2_device_register_subdev_nodes(struct v4l2_device *v4l2_dev,
                                        bool read_only)
{
        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;

                if (sd->devnode)
                        continue;

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

                video_set_drvdata(vdev, sd);
                strscpy(vdev->name, sd->name, sizeof(vdev->name));
                vdev->dev_parent = sd->dev;
                vdev->v4l2_dev = v4l2_dev;
                vdev->fops = &v4l2_subdev_fops;
                vdev->release = v4l2_device_release_subdev_node;
                vdev->ctrl_handler = sd->ctrl_handler;
                if (read_only)
                        set_bit(V4L2_FL_SUBDEV_RO_DEVNODE, &vdev->flags);
                err = __video_register_device(vdev, VFL_TYPE_SUBDEV, -1, 1,
                                              sd->owner);
                if (err < 0) {
                        kfree(vdev);
                        goto clean_up;
                }
                sd->devnode = vdev;
#if defined(CONFIG_MEDIA_CONTROLLER)
                sd->entity.info.dev.major = VIDEO_MAJOR;
                sd->entity.info.dev.minor = vdev->minor;

                /* Interface is created by __video_register_device() */
                if (vdev->v4l2_dev->mdev) {
                        struct media_link *link;

                        link = media_create_intf_link(&sd->entity,
                                                      &vdev->intf_devnode->intf,
                                                      MEDIA_LNK_FL_ENABLED |
                                                      MEDIA_LNK_FL_IMMUTABLE);
                        if (!link) {
                                err = -ENOMEM;
                                goto clean_up;
                        }
                }
#endif
        }
        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) {
                /*
                 * No need to explicitly remove links, as both pads and
                 * links are removed by the function below, in the right order
                 */
                media_device_unregister_entity(&sd->entity);
        }
#endif
        if (sd->devnode)
                video_unregister_device(sd->devnode);
        else
                v4l2_subdev_release(sd);
}
EXPORT_SYMBOL_GPL(v4l2_device_unregister_subdev);