Linux v4l2架构学习总链接

rkcif_mipi源码

dts源码如下

rkcif_mipi_lvds: rkcif_mipi_lvds {
    compatible = "rockchip,rkcif-mipi-lvds";
    ...
    status = "okay";

    port {
        cif_mipi_in: endpoint {
        remote-endpoint = <&mipi_csi2_output>;
        data-lanes = <1 2 3 4>;
        };
    };
};

开始分析驱动代码

static int rkcif_plat_probe(struct platform_device *pdev)
{
	const struct of_device_id *match;
	struct device_node *node = pdev->dev.of_node;
	struct device *dev = &pdev->dev;
	struct rkcif_device *cif_dev;
	const struct rkcif_match_data *data;
	int ret;

        ...
	cif_dev = devm_kzalloc(dev, sizeof(*cif_dev), GFP_KERNEL);
	if (!cif_dev)
		return -ENOMEM;

	dev_set_drvdata(dev, cif_dev);
	cif_dev->dev = dev;

        ...
	ret = rkcif_plat_init(cif_dev, node, data->inf_id);
	if (ret) {
		rkcif_detach_hw(cif_dev);
		return ret;
	}

        ...

	return 0;
}

rkcif_plat_probe

-> rkcif_plat_init

---

int rkcif_plat_init(struct rkcif_device *cif_dev, struct device_node *node, int inf_id)
{
	struct device *dev = cif_dev->dev;
	struct v4l2_device *v4l2_dev;
	int ret;


	cif_dev->pipe.open = rkcif_pipeline_open;
	cif_dev->pipe.close = rkcif_pipeline_close;
	cif_dev->pipe.set_stream = rkcif_pipeline_set_stream;
	cif_dev->isr_hdl = rkcif_irq_handler;


	/*
         * stream和cif_dev进行关联，知道就行
         */

    	rkcif_stream_init(cif_dev, RKCIF_STREAM_MIPI_ID0);
	rkcif_stream_init(cif_dev, RKCIF_STREAM_MIPI_ID1);
	rkcif_stream_init(cif_dev, RKCIF_STREAM_MIPI_ID2);
	rkcif_stream_init(cif_dev, RKCIF_STREAM_MIPI_ID3);

        ...

	v4l2_dev = &cif_dev->v4l2_dev;

	ret = v4l2_device_register(cif_dev->dev, &cif_dev->v4l2_dev);
	if (ret < 0)
		return ret;


        /*
         * media暂时不分析
         */


	media_device_init(&cif_dev->media_dev);
    	ret = media_device_register(&cif_dev->media_dev);
	if (ret < 0) {
		v4l2_err(v4l2_dev, "Failed to register media device: %d\n",
			 ret);
		goto err_unreg_v4l2_dev;
	}

	/* create & register platefom subdev (from of_node) */
	ret = rkcif_register_platform_subdevs(cif_dev);
	if (ret < 0)
		goto err_unreg_media_dev;


        ...
    	mutex_lock(&rkcif_dev_mutex);
	list_add_tail(&cif_dev->list, &rkcif_device_list);
	mutex_unlock(&rkcif_dev_mutex);

	return 0;
}

rkcif_plat_probe

-> rkcif_plat_init

       -> rkcif_stream_init

---

 这个看一下就行，用于stream和dev的分析

void rkcif_stream_init(struct rkcif_device *dev, u32 id)
{
	struct rkcif_stream *stream = &dev->stream[id];
	struct v4l2_pix_format_mplane pixm;
	int i;

	stream->id = id;
	stream->cifdev = dev;


	/* Set default format */
	pixm.pixelformat = V4L2_PIX_FMT_NV12;
	pixm.width = RKCIF_DEFAULT_WIDTH;
	pixm.height = RKCIF_DEFAULT_HEIGHT;

        /*
         * stream->cif_fmt_out = fmt;
	 * stream->pixm = pixm;
         */
	rkcif_set_fmt(stream, &pixm, false);

	...
}

rkcif_plat_probe

-> rkcif_plat_init

       -> rkcif_stream_init

       -> rkcif_register_platform_subdevs

---

static int rkcif_register_platform_subdevs(struct rkcif_device *cif_dev)
{
	int stream_num = 0, ret;


        /*
         * RKCIF_MAX_STREAM_MIPI 值为4
         * 会注册4个video节点
         */

	stream_num = RKCIF_MAX_STREAM_MIPI;
	ret = rkcif_register_stream_vdevs(cif_dev, stream_num,
						  true);

	if (ret < 0) {
		dev_err(cif_dev->dev, "cif register stream[%d] failed!\n", stream_num);
		return -EINVAL;
	}

	ret = cif_subdev_notifier(cif_dev);
	if (ret < 0) {
		v4l2_err(&cif_dev->v4l2_dev,
			 "Failed to register subdev notifier(%d)\n", ret);
		goto err_unreg_stream_vdev;
	}

	return 0;
}

rkcif_plat_probe

-> rkcif_plat_init

       -> rkcif_stream_init

       -> rkcif_register_platform_subdevs

                      -> rkcif_register_stream_vdevs

---

 这部分代码是注册video节点，和vivi驱动大同小异

int rkcif_register_stream_vdevs(struct rkcif_device *dev,
				int stream_num,
				bool is_multi_input)
{
	struct rkcif_stream *stream;
	int i, j, ret;

	for (i = 0; i < stream_num; i++) {
		stream = &dev->stream[i];
		stream->cifdev = dev;
		ret = rkcif_register_stream_vdev(stream, is_multi_input);
		if (ret < 0)
			goto err;
	}

	return 0;
err:
	for (j = 0; j < i; j++) {
		stream = &dev->stream[j];
		rkcif_unregister_stream_vdev(stream);
	}

	return ret;
}

static int rkcif_register_stream_vdev(struct rkcif_stream *stream,
				      bool is_multi_input)
{
	struct rkcif_device *dev = stream->cifdev;
	struct v4l2_device *v4l2_dev = &dev->v4l2_dev;
	struct video_device *vdev = &stream->vnode.vdev;
	struct rkcif_vdev_node *node;
	int ret = 0;
	char *vdev_name;

	if (is_multi_input) {
		switch (stream->id) {
		case RKCIF_STREAM_MIPI_ID0:
			vdev_name = CIF_MIPI_ID0_VDEV_NAME;
			break;
		case RKCIF_STREAM_MIPI_ID1:
			vdev_name = CIF_MIPI_ID1_VDEV_NAME;
			break;
		case RKCIF_STREAM_MIPI_ID2:
			vdev_name = CIF_MIPI_ID2_VDEV_NAME;
			break;
		case RKCIF_STREAM_MIPI_ID3:
			vdev_name = CIF_MIPI_ID3_VDEV_NAME;
			break;
		case RKCIF_STREAM_DVP:
			vdev_name = CIF_DVP_VDEV_NAME;
			break;
		default:
			v4l2_err(v4l2_dev, "Invalid stream\n");
			goto unreg;
		}
	} else {
		vdev_name = CIF_VIDEODEVICE_NAME;
	}

	strlcpy(vdev->name, vdev_name, sizeof(vdev->name));
	node = vdev_to_node(vdev);
	mutex_init(&node->vlock);

	vdev->ioctl_ops = &rkcif_v4l2_ioctl_ops;
	vdev->release = video_device_release_empty;
	vdev->fops = &rkcif_fops;
	vdev->minor = -1;
	vdev->v4l2_dev = v4l2_dev;
	vdev->lock = &node->vlock;
	vdev->device_caps = V4L2_CAP_VIDEO_CAPTURE_MPLANE |
			    V4L2_CAP_STREAMING;
	video_set_drvdata(vdev, stream);
	vdev->vfl_dir = VFL_DIR_RX;
	node->pad.flags = MEDIA_PAD_FL_SINK;

	rkcif_init_vb2_queue(&node->buf_queue, stream,
			     V4L2_BUF_TYPE_VIDEO_CAPTURE_MPLANE);
	vdev->queue = &node->buf_queue;

	ret = video_register_device(vdev, VFL_TYPE_GRABBER, -1);
	if (ret < 0) {
		v4l2_err(v4l2_dev,
			 "video_register_device failed with error %d\n", ret);
		return ret;
	}

	ret = media_entity_pads_init(&vdev->entity, 1, &node->pad);
	if (ret < 0)
		goto unreg;

	return 0;
unreg:
	video_unregister_device(vdev);
	return ret;
}

列举一下video的一些信息

同样的ops还是v4l2_fops

要注意的是：

1. vdev->fops = &rkcif_fops
2. vdev->ioctl_ops = &rkcif_v4l2_ioctl_ops
3. vdev->device_caps = V4L2_CAP_VIDEO_CAPTURE_MPLANE |
                   V4L2_CAP_STREAMING;
4. queue->ops = &rkcif_vb2_ops
5. queue->mem_ops = &vb2_dma_contig_memops
6. queue->io_modes = VB2_MMAP | VB2_DMABUF
7. queue->min_buffer_needed = 1

和vivi相比，不仅仅支持MMAP还支持DMABUF，另外device_caps类型是V4L2_CAP_VIDEO_CAPTURE_MPLANE，多平面视频格式，vivi中这种格式我们忽略了没有分析

---

rkcif_plat_probe

-> rkcif_plat_init

       -> rkcif_stream_init

       -> rkcif_register_platform_subdevs

                      -> rkcif_register_stream_vdevs

                      -> cif_subdev_notifier

---

static int cif_subdev_notifier(struct rkcif_device *cif_dev)
{
	struct v4l2_async_notifier *ntf = &cif_dev->notifier;
	struct device *dev = cif_dev->dev;
	int ret;


        /*
         * v4l2_async_notifier_parse_fwnode_endpoints和
         * v4l2_async_notifier_parse_fwnode_endpoints_by_port类似
         * 区别是has_port这个参数是false，而不是true
         * true的时候会去看port到reg值，获取port号及id号
         * 由于当前对应的dts没有reg
         * 所以使用false
         * 这样的结果是 rkcif_mipi的notifier->subdevs[0] 存储的数据
         * 指向mipi csi dts的节点
         * 回调函数 rkcif_fwnode_parse 这里不分析
         */


	ret = v4l2_async_notifier_parse_fwnode_endpoints(
		dev, ntf, sizeof(struct rkcif_async_subdev), rkcif_fwnode_parse);

	if (ret < 0)
		return ret;

	if (!ntf->num_subdevs)
		return -ENODEV;	/* no endpoint */

	ntf->ops = &subdev_notifier_ops;

	return v4l2_async_notifier_register(&cif_dev->v4l2_dev, ntf);
}

int v4l2_async_notifier_register(struct v4l2_device *v4l2_dev,
				 struct v4l2_async_notifier *notifier)
{
	int ret;

	if (WARN_ON(!v4l2_dev || notifier->sd))
		return -EINVAL;

	notifier->v4l2_dev = v4l2_dev;

	ret = __v4l2_async_notifier_register(notifier);
	if (ret)
		notifier->v4l2_dev = NULL;

	return ret;
}

对于__v4l2_async_notifier_register看下面的分析

v4l2_async_subdev_notifier_register 分析

一定要看v4l2_async_subdev_notifier_register的分析，否则会不理解怎么注册subdev

看完上面的分析可以知道

所有的subdev现在都挂载在v4l2_dev->subdevs上，现在分析notifier->ops->complete

static int subdev_notifier_complete(struct v4l2_async_notifier *notifier)
{
	struct rkcif_device *dev;
	struct rkcif_sensor_info *sensor;
	int ret, index;

	dev = container_of(notifier, struct rkcif_device, notifier);
        ...

	ret = v4l2_device_register_subdev_nodes(&dev->v4l2_dev);
	if (ret < 0)
		goto unregister_lvds;

	v4l2_info(&dev->v4l2_dev, "Async subdev notifier completed\n");
	return ret;
}

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.
	 */


        /*
         * 遍历每个sd
         */

	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);
		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;

                /*
                 * 注册/dev/v4l-subdev
                 * 不跟进分析，记住重要的ops就可以了
                 */

		err = __video_register_device(vdev, VFL_TYPE_SUBDEV, -1, 1,
					      sd->owner);
		if (err < 0) {
			kfree(vdev);
			goto clean_up;
		}
		sd->devnode = vdev;

	}
	return 0;
}}