[PATCH] [media] vmc: Virtual Media Controller core, capture and sensor

[Helen Fornazier <helen.fornazier@gmail.com>]

First version of the Virtual Media Controller.
Add a simple version of the core of the driver, the capture and
sensor nodes in the topology, generating a grey image in a hardcoded
format.

Signed-off-by: Helen Fornazier <helen.fornazier@gmail.com>
---

The Virtual Media Controller is meant to provide a test tool which simulates a configurable video pipeline exposing
the configuration of its individual nodes (such as sensors, debayers, scalers, inputs, outputs) throught the subdevice API.

This first version generates a grey image with a fixed format within a thread in the sensor, but it will be integrated with
the Test Pattern Generator from the Vivid driver in the future.

For more information: http://kernelnewbies.org/LaurentPinchart

The patch is based on 'media/master' branch and available at
        https://github.com/helen-fornazier/opw-staging vmc/review/video-pipe

 drivers/media/Kconfig           |   1 +
 drivers/media/Makefile          |   2 +-
 drivers/media/vmc/Kconfig       |   6 +
 drivers/media/vmc/Makefile      |   4 +
 drivers/media/vmc/vmc-capture.c | 528 +++++++++++++++++++++++++++++++++++
 drivers/media/vmc/vmc-capture.h |  50 ++++
 drivers/media/vmc/vmc-core.c    | 595 ++++++++++++++++++++++++++++++++++++++++
 drivers/media/vmc/vmc-core.h    |  55 ++++
 drivers/media/vmc/vmc-sensor.c  | 275 +++++++++++++++++++
 drivers/media/vmc/vmc-sensor.h  |  40 +++
 10 files changed, 1555 insertions(+), 1 deletion(-)
 create mode 100644 drivers/media/vmc/Kconfig
 create mode 100644 drivers/media/vmc/Makefile
 create mode 100644 drivers/media/vmc/vmc-capture.c
 create mode 100644 drivers/media/vmc/vmc-capture.h
 create mode 100644 drivers/media/vmc/vmc-core.c
 create mode 100644 drivers/media/vmc/vmc-core.h
 create mode 100644 drivers/media/vmc/vmc-sensor.c
 create mode 100644 drivers/media/vmc/vmc-sensor.h

diff --git a/drivers/media/Kconfig b/drivers/media/Kconfig
index 3ef3d6c..6804a32 100644
--- a/drivers/media/Kconfig
+++ b/drivers/media/Kconfig
@@ -216,5 +216,6 @@ config MEDIA_ATTACH
 source "drivers/media/i2c/Kconfig"
 source "drivers/media/tuners/Kconfig"
 source "drivers/media/dvb-frontends/Kconfig"
+source "drivers/media/vmc/Kconfig"
 
 endif # MEDIA_SUPPORT
diff --git a/drivers/media/Makefile b/drivers/media/Makefile
index e608bbc..471ea93 100644
--- a/drivers/media/Makefile
+++ b/drivers/media/Makefile
@@ -28,6 +28,6 @@ obj-y += rc/
 # Finally, merge the drivers that require the core
 #
 
-obj-y += common/ platform/ pci/ usb/ mmc/ firewire/
+obj-y += common/ platform/ pci/ usb/ mmc/ firewire/ vmc/
 obj-$(CONFIG_VIDEO_DEV) += radio/
 
diff --git a/drivers/media/vmc/Kconfig b/drivers/media/vmc/Kconfig
new file mode 100644
index 0000000..72aba9a
--- /dev/null
+++ b/drivers/media/vmc/Kconfig
@@ -0,0 +1,6 @@
+config VMC
+	tristate "Virtual Media Controller Driver (VMC)"
+	depends on VIDEO_V4L2_SUBDEV_API
+	default n
+	---help---
+	  Skeleton driver for Virtual Media Controller
diff --git a/drivers/media/vmc/Makefile b/drivers/media/vmc/Makefile
new file mode 100644
index 0000000..6eb773c
--- /dev/null
+++ b/drivers/media/vmc/Makefile
@@ -0,0 +1,4 @@
+vmc-objs := vmc-core.o vmc-capture.o vmc-sensor.o
+
+
+obj-$(CONFIG_VMC) += vmc.o
diff --git a/drivers/media/vmc/vmc-capture.c b/drivers/media/vmc/vmc-capture.c
new file mode 100644
index 0000000..9367973
--- /dev/null
+++ b/drivers/media/vmc/vmc-capture.c
@@ -0,0 +1,528 @@
+/*
+ * vmc-capture.c Virtual Media Controller Driver
+ *
+ * Copyright (C) 2015 Helen Fornazier <helen.fornazier@gmail.com>
+ *
+ * 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.
+ *
+ */
+
+#include <media/videobuf2-vmalloc.h>
+#include <media/v4l2-ioctl.h>
+
+#include "vmc-capture.h"
+
+struct vmc_cap_buffer {
+	/*
+	 * vb2_buffer must be the first element
+	 * the videobf2 framework will allocate this struct based on
+	 * buf_struct_size and use the first sizeof(struct vb2_buffer) bytes of
+	 * memory as a vb2_buffer
+	 */
+	struct vb2_buffer vb2;
+	struct list_head list;
+};
+
+static int vmc_cap_querycap(struct file *file, void *priv,
+			    struct v4l2_capability *cap)
+{
+	struct vmc_cap_device *vcap = video_drvdata(file);
+
+	strlcpy(cap->driver, KBUILD_MODNAME, sizeof(cap->driver));
+	strlcpy(cap->card, KBUILD_MODNAME, sizeof(cap->card));
+	snprintf(cap->bus_info, sizeof(cap->bus_info),
+			"platform:%s", vcap->v4l2_dev->name);
+
+	cap->device_caps = V4L2_CAP_VIDEO_CAPTURE | V4L2_CAP_STREAMING;
+	cap->capabilities = cap->device_caps | V4L2_CAP_DEVICE_CAPS;
+
+	return 0;
+}
+
+static int vmc_cap_enum_input(struct file *file, void *priv,
+			      struct v4l2_input *i)
+{
+	/* We just have one input */
+	if (i->index > 0)
+		return -EINVAL;
+
+	i->type = V4L2_INPUT_TYPE_CAMERA;
+	strlcpy(i->name, "VMC capture", sizeof(i->name));
+
+	return 0;
+}
+
+static int vmc_cap_g_input(struct file *file, void *priv, unsigned int *i)
+{
+	/* We just have one input */
+	*i = 0;
+	return 0;
+}
+
+static int vmc_cap_s_input(struct file *file, void *priv, unsigned int i)
+{
+	/* We just have one input */
+	if (i > 0)
+		return -EINVAL;
+
+	return 0;
+}
+
+static int vmc_cap_g_fmt_vid_cap(struct file *file, void *priv,
+				 struct v4l2_format *f)
+{
+	struct vmc_cap_device *vcap = video_drvdata(file);
+
+	f->fmt.pix = vcap->format;
+
+	return 0;
+}
+
+static int vmc_cap_s_fmt_vid_cap(struct file *file, void *priv,
+				 struct v4l2_format *f)
+{
+	/* We just support one format for now */
+	return vmc_cap_g_fmt_vid_cap(file, priv, f);
+}
+
+static int vmc_cap_try_fmt_vid_cap(struct file *file, void *priv,
+				   struct v4l2_format *f)
+{
+	/* We just support one format for now */
+	return vmc_cap_g_fmt_vid_cap(file, priv, f);
+}
+
+static int vmc_cap_enum_fmt_vid_cap(struct file *file, void *priv,
+				    struct v4l2_fmtdesc *f)
+{
+	struct vmc_cap_device *vcap = video_drvdata(file);
+
+	if (f->index > 0)
+		return -EINVAL;
+
+	/* We just support one format for now */
+	f->pixelformat = vcap->format.pixelformat;
+
+	return 0;
+}
+
+static const struct v4l2_file_operations vmc_cap_fops = {
+	.owner		= THIS_MODULE,
+	.open		= v4l2_fh_open,
+	.release	= vb2_fop_release,
+	.read           = vb2_fop_read,
+	.poll		= vb2_fop_poll,
+	.unlocked_ioctl = video_ioctl2,
+	.mmap           = vb2_fop_mmap,
+};
+
+static const struct v4l2_ioctl_ops vmc_cap_ioctl_ops = {
+	.vidioc_querycap = vmc_cap_querycap,
+
+	.vidioc_enum_input = vmc_cap_enum_input,
+	.vidioc_g_input = vmc_cap_g_input,
+	.vidioc_s_input = vmc_cap_s_input,
+
+	.vidioc_g_fmt_vid_cap = vmc_cap_g_fmt_vid_cap,
+	.vidioc_s_fmt_vid_cap = vmc_cap_s_fmt_vid_cap,
+	.vidioc_try_fmt_vid_cap = vmc_cap_try_fmt_vid_cap,
+	.vidioc_enum_fmt_vid_cap = vmc_cap_enum_fmt_vid_cap,
+
+	.vidioc_reqbufs = vb2_ioctl_reqbufs,
+	.vidioc_create_bufs = vb2_ioctl_create_bufs,
+	.vidioc_querybuf = vb2_ioctl_querybuf,
+	.vidioc_qbuf = vb2_ioctl_qbuf,
+	.vidioc_dqbuf = vb2_ioctl_dqbuf,
+	.vidioc_expbuf = vb2_ioctl_expbuf,
+	.vidioc_streamon = vb2_ioctl_streamon,
+	.vidioc_streamoff = vb2_ioctl_streamoff,
+};
+
+static void vmc_cap_return_all_buffers(struct vmc_cap_device *vcap,
+				       enum vb2_buffer_state state)
+{
+	struct vmc_cap_buffer *vbuf, *node;
+
+	spin_lock(&vcap->qlock);
+
+	list_for_each_entry_safe(vbuf, node, &vcap->buf_list, list) {
+		vb2_buffer_done(&vbuf->vb2, state);
+		list_del(&vbuf->list);
+	}
+
+	spin_unlock(&vcap->qlock);
+}
+
+static int vmc_cap_pipeline_s_stream(struct vmc_cap_device *vcap, int enable)
+{
+	int ret;
+	struct media_pad *pad;
+	struct media_entity *entity;
+	struct v4l2_subdev *sd;
+
+	/* Start the stream in the subdevice direct connected */
+	entity = &vcap->vdev.entity;
+	pad = media_entity_remote_pad(&entity->pads[0]);
+
+	/* If we are not connected to any subdev node, it means there is nothing
+	 * to activate on the pipe (e.g. we can be connected with an input
+	 * device or we are not connected at all)*/
+	if (pad == NULL ||
+	    media_entity_type(pad->entity) != MEDIA_ENT_T_V4L2_SUBDEV)
+		return 0;
+
+	entity = pad->entity;
+	sd = media_entity_to_v4l2_subdev(entity);
+
+	ret = v4l2_subdev_call(sd, video, s_stream, enable);
+	if (ret && ret != -ENOIOCTLCMD)
+		return ret;
+
+	return 0;
+}
+
+static int vmc_cap_start_streaming(struct vb2_queue *vq, unsigned int count)
+{
+	int ret;
+	struct media_entity *entity;
+	struct vmc_cap_device *vcap = vb2_get_drv_priv(vq);
+
+	vcap->sequence = 0;
+
+	/* Start the media pipeline */
+	entity = &vcap->vdev.entity;
+	ret = media_entity_pipeline_start(entity, NULL);
+	if (ret) {
+		vmc_cap_return_all_buffers(vcap, VB2_BUF_STATE_QUEUED);
+		return ret;
+	}
+
+	/* Enable streaming from the pipe */
+	ret = vmc_cap_pipeline_s_stream(vcap, 1);
+	if (ret) {
+		vmc_cap_return_all_buffers(vcap, VB2_BUF_STATE_QUEUED);
+		return ret;
+	}
+
+	return 0;
+}
+
+/*
+ * Stop the stream engine. Any remaining buffers in the stream queue are
+ * dequeued and passed on to the vb2 framework marked as STATE_ERROR.
+ */
+static void vmc_cap_stop_streaming(struct vb2_queue *vq)
+{
+	struct vmc_cap_device *vcap = vb2_get_drv_priv(vq);
+
+	/* Disable streaming from the pipe */
+	vmc_cap_pipeline_s_stream(vcap, 0);
+
+	/* Stop the media pipeline */
+	media_entity_pipeline_stop(&vcap->vdev.entity);
+
+	/* Release all active buffers */
+	vmc_cap_return_all_buffers(vcap, VB2_BUF_STATE_ERROR);
+}
+
+static void vmc_cap_buf_queue(struct vb2_buffer *vb2)
+{
+	struct vmc_cap_device *vcap = vb2_get_drv_priv(vb2->vb2_queue);
+	struct vmc_cap_buffer *buf = container_of(vb2,
+						  struct vmc_cap_buffer, vb2);
+
+	/* If the buffer doesn't have enough size, mark it as error */
+	if (vb2->v4l2_planes[0].length < vcap->format.sizeimage) {
+		vb2_buffer_done(vb2, VB2_BUF_STATE_ERROR);
+		return;
+	}
+
+	spin_lock(&vcap->qlock);
+
+	list_add_tail(&buf->list, &vcap->buf_list);
+
+	spin_unlock(&vcap->qlock);
+}
+
+static int vmc_cap_queue_setup(struct vb2_queue *vq,
+			       const struct v4l2_format *fmt,
+			       unsigned int *nbuffers, unsigned int *nplanes,
+			       unsigned int sizes[], void *alloc_ctxs[])
+{
+	struct vmc_cap_device *vcap = vb2_get_drv_priv(vq);
+
+	/*We don't support multiplanes for now */
+	*nplanes = 1;
+
+	sizes[0] = fmt ? fmt->fmt.pix.sizeimage : vcap->format.sizeimage;
+
+	return 0;
+}
+
+static const struct vb2_ops vmc_cap_qops = {
+	.start_streaming	= vmc_cap_start_streaming,
+	.stop_streaming		= vmc_cap_stop_streaming,
+	.buf_queue		= vmc_cap_buf_queue,
+	.queue_setup		= vmc_cap_queue_setup,
+	/*
+	 * Since q->lock is set we can use the standard
+	 * vb2_ops_wait_prepare/finish helper functions.
+	 */
+	.wait_prepare		= vb2_ops_wait_prepare,
+	.wait_finish		= vb2_ops_wait_finish,
+};
+
+/* NOTE: this function is a copy of v4l2_subdev_link_validate_get_format
+ * maybe the v4l2 function should be public */
+static int vmc_cap_v4l2_subdev_link_validate_get_format(struct media_pad *pad,
+						struct v4l2_subdev_format *fmt)
+{
+	struct v4l2_subdev *sd = media_entity_to_v4l2_subdev(pad->entity);
+
+	fmt->which = V4L2_SUBDEV_FORMAT_ACTIVE;
+	fmt->pad = pad->index;
+	return v4l2_subdev_call(sd, pad, get_fmt, NULL, fmt);
+}
+
+static int vmc_cap_link_validate(struct media_link *link)
+{
+	struct v4l2_subdev_format source_fmt;
+	struct v4l2_pix_format *sink_fmt;
+	struct vmc_cap_device *vcap;
+	const struct vmc_pix_fmt_map *vpix;
+	int ret;
+
+	/* Retrieve the video capture device */
+	vcap = container_of(link->sink->entity,
+			    struct vmc_cap_device, vdev.entity);
+
+	/* If the connected node is not a subdevice type
+	 * then its a raw node from vmc-core, ignore the link for now
+	 * TODO: remove this when there are no more raw nodes in the
+	 * core and return error instead */
+	if (link->source->entity->type != MEDIA_ENT_T_V4L2_SUBDEV)
+		return 0;
+
+	/* Get the the format of the video device */
+	sink_fmt = &vcap->format;
+
+	/* Get the the format of the subdev */
+	ret = vmc_cap_v4l2_subdev_link_validate_get_format(link->source,
+							   &source_fmt);
+	if (ret)
+		return ret;
+
+	dev_dbg(vcap->dev,
+		"cap link validate formats src:%dx%d %d sink:%dx%d %d\n",
+		source_fmt.format.width, source_fmt.format.height,
+		source_fmt.format.code,
+		sink_fmt->width, sink_fmt->height,
+		sink_fmt->pixelformat);
+
+	/* Validate the format */
+
+	vpix = vmc_pix_fmt_map_by_pixelformat(sink_fmt->pixelformat);
+	if (!vpix)
+		return -EINVAL;
+
+	/* The width, height and code must match. */
+	if (source_fmt.format.width != sink_fmt->width
+	    || source_fmt.format.height != sink_fmt->height
+	    || vpix->code != source_fmt.format.code)
+		return -EINVAL;
+
+	/* The field order must match, or the sink field order must be NONE
+	 * to support interlaced hardware connected to bridges that support
+	 * progressive formats only.
+	 */
+	if (source_fmt.format.field != sink_fmt->field &&
+	    sink_fmt->field != V4L2_FIELD_NONE)
+		return -EINVAL;
+
+	return 0;
+}
+
+static const struct media_entity_operations vmc_cap_mops = {
+	.link_validate		= vmc_cap_link_validate,
+};
+
+void vmc_cap_destroy(struct vmc_ent_device *ved)
+{
+	struct vmc_cap_device *vcap = container_of(ved,
+						   struct vmc_cap_device, ved);
+
+	vb2_queue_release(&vcap->queue);
+	media_entity_cleanup(ved->ent);
+	video_unregister_device(&vcap->vdev);
+	vmc_pads_cleanup(vcap->ved.pads);
+	kfree(vcap);
+}
+
+static void vmc_cap_process_frame(struct vmc_ent_device *ved,
+				  struct media_pad *sink, const void *frame)
+{
+	struct vmc_cap_device *vcap = container_of(ved,
+						   struct vmc_cap_device, ved);
+	struct vmc_cap_buffer *vmc_buf;
+	void *vbuf;
+
+	spin_lock(&vcap->qlock);
+
+	/* Get the first entry of the list */
+	vmc_buf = list_first_entry_or_null(&vcap->buf_list,
+					   typeof(*vmc_buf), list);
+	if (!vmc_buf) {
+		spin_unlock(&vcap->qlock);
+		return;
+	}
+
+	/* Remove this entry form the list */
+	list_del(&vmc_buf->list);
+
+	spin_unlock(&vcap->qlock);
+
+	/* Fill the buffer */
+	v4l2_get_timestamp(&vmc_buf->vb2.v4l2_buf.timestamp);
+	vmc_buf->vb2.v4l2_buf.sequence = vcap->sequence++;
+	vmc_buf->vb2.v4l2_buf.field = vcap->format.field;
+
+	vbuf = vb2_plane_vaddr(&vmc_buf->vb2, 0);
+
+	memcpy(vbuf, frame, vcap->format.sizeimage);
+
+	/* Set it as ready */
+	vb2_set_plane_payload(&vmc_buf->vb2, 0, vcap->format.sizeimage);
+	vb2_buffer_done(&vmc_buf->vb2, VB2_BUF_STATE_DONE);
+}
+
+struct vmc_ent_device *vmc_cap_create(struct v4l2_device *v4l2_dev,
+				      const char *const name,
+				      u16 num_pads,
+				      const unsigned long *pads_flag)
+{
+	int ret;
+	struct vb2_queue *q;
+	struct video_device *vdev;
+	struct vmc_cap_device *vcap;
+	const struct vmc_pix_fmt_map *vpix;
+
+	if (!v4l2_dev || !v4l2_dev->dev || !name || (num_pads && !pads_flag))
+		return ERR_PTR(-EINVAL);
+
+	/* Allocate the vmc_cap_device struct */
+	vcap = kzalloc(sizeof(*vcap), GFP_KERNEL);
+	if (!vcap)
+		return ERR_PTR(-ENOMEM);
+
+	/* Link the vmc_cap_device struct with the v4l2 parent */
+	vcap->v4l2_dev = v4l2_dev;
+	/* Link the vmc_cap_device struct with the dev parent */
+	vcap->dev = v4l2_dev->dev;
+
+	/* Allocate the pads */
+	vcap->ved.pads = vmc_pads_init(num_pads, pads_flag);
+	if (IS_ERR(vcap->ved.pads)) {
+		ret = PTR_ERR(vcap->ved.pads);
+		goto err_free_vcap;
+	}
+
+	/* Initialize the media entity */
+	vcap->vdev.entity.name = name;
+	vcap->vdev.entity.type = MEDIA_ENT_T_DEVNODE;
+	ret = media_entity_init(&vcap->vdev.entity, num_pads,
+				vcap->ved.pads, num_pads);
+	if (ret)
+		goto err_clean_pads;
+
+	/* Initialize the lock */
+	mutex_init(&vcap->lock);
+
+	/* Initialize the vb2 queue */
+	q = &vcap->queue;
+	q->type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
+	q->io_modes = VB2_MMAP | VB2_DMABUF;
+	q->drv_priv = vcap;
+	q->buf_struct_size = sizeof(struct vmc_cap_buffer);
+	q->ops = &vmc_cap_qops;
+	q->mem_ops = &vb2_vmalloc_memops;
+	q->timestamp_flags = V4L2_BUF_FLAG_TIMESTAMP_MONOTONIC;
+	q->min_buffers_needed = 2;
+	/*
+	 * Set the queue lock (TODO: add a separated lock from the video_device)
+	 * so we can use the defaults vb2 wait_prepare and wait_finish ops
+	 */
+	q->lock = &vcap->lock;
+
+	ret = vb2_queue_init(q);
+	if (ret) {
+		dev_err(vcap->dev,
+			"vb2 queue init failed (err=%d)\n", ret);
+		goto err_clean_m_ent;
+	}
+
+	/* Initialize buffer list and its lock */
+	INIT_LIST_HEAD(&vcap->buf_list);
+	spin_lock_init(&vcap->qlock);
+
+	/* Initialize the video_device struct */
+	vdev = &vcap->vdev;
+	vdev->entity.ops = &vmc_cap_mops;
+	vdev->release = video_device_release_empty;
+	vdev->fops = &vmc_cap_fops;
+	vdev->ioctl_ops = &vmc_cap_ioctl_ops;
+	vdev->lock = &vcap->lock;
+	vdev->queue = q;
+	vdev->v4l2_dev = vcap->v4l2_dev;
+	vdev->vfl_dir = VFL_DIR_RX;
+	strlcpy(vdev->name, name, sizeof(vdev->name));
+	video_set_drvdata(vdev, vcap);
+
+	/* Register the video_device with the v4l2 and the media framework */
+	ret = video_register_device(vdev, VFL_TYPE_GRABBER, -1);
+	if (ret) {
+		dev_err(vcap->dev,
+			"video register failed (err=%d)\n", ret);
+		goto err_release_queue;
+	}
+
+	/* Set the frame format (this is hardcoded for now) */
+	vcap->format.width = 640;
+	vcap->format.height = 480;
+	vcap->format.pixelformat = V4L2_PIX_FMT_RGB24;
+	vcap->format.field = V4L2_FIELD_INTERLACED;
+	vcap->format.colorspace = V4L2_COLORSPACE_SRGB;
+
+	vpix = vmc_pix_fmt_map_by_pixelformat(vcap->format.pixelformat);
+	/* This should never be NULL, as we won't allow any format
+	 * other then the ones in the vmc_pix_fmt_map_list table */
+	BUG_ON(!vpix);
+
+	vcap->format.bytesperline = vcap->format.width * vpix->bpp;
+	vcap->format.sizeimage = vcap->format.bytesperline * vcap->format.height;
+
+	/* Fill the vmc_ent_device struct */
+	vcap->ved.destroy = vmc_cap_destroy;
+	vcap->ved.ent = &vcap->vdev.entity;
+	vcap->ved.process_frame = vmc_cap_process_frame;
+
+	return &vcap->ved;
+
+err_release_queue:
+	vb2_queue_release(q);
+err_clean_m_ent:
+	media_entity_cleanup(&vcap->vdev.entity);
+err_clean_pads:
+	vmc_pads_cleanup(vcap->ved.pads);
+err_free_vcap:
+	kfree(vcap);
+
+	return ERR_PTR(ret);
+}
diff --git a/drivers/media/vmc/vmc-capture.h b/drivers/media/vmc/vmc-capture.h
new file mode 100644
index 0000000..2d2c3e6
--- /dev/null
+++ b/drivers/media/vmc/vmc-capture.h
@@ -0,0 +1,50 @@
+/*
+ * vmc-capture.h Virtual Media Controller Driver
+ *
+ * Copyright (C) 2015 Helen Fornazier <helen.fornazier@gmail.com>
+ *
+ * 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.
+ *
+ */
+
+#ifndef _VMC_CAPTURE_H_
+#define _VMC_CAPTURE_H_
+
+#include <media/videobuf2-core.h>
+
+#include "vmc-core.h"
+
+struct vmc_cap_device {
+	struct vmc_ent_device ved;
+	struct video_device vdev;
+	struct v4l2_device *v4l2_dev;
+	struct device *dev;
+	struct v4l2_pix_format format;
+	struct vb2_queue queue;
+	struct list_head buf_list;
+	/* NOTE: in a real driver, a spin lock must be used to access the
+	 * queue because the frames are generated from a hardware interruption
+	 * and the irs is not allowed to sleep.
+	 * Even if it is not necessary a spinlock in the vmc driver we
+	 * use it here as a code reference */
+	spinlock_t qlock;
+	struct mutex lock;
+	u32 sequence;
+};
+
+struct vmc_ent_device *vmc_cap_create(struct v4l2_device *v4l2_dev,
+				      const char *const name,
+				      u16 num_pads,
+				      const unsigned long *pads_flag);
+
+void vmc_cap_destroy(struct vmc_ent_device *ved);
+
+#endif
diff --git a/drivers/media/vmc/vmc-core.c b/drivers/media/vmc/vmc-core.c
new file mode 100644
index 0000000..778fd3b3
--- /dev/null
+++ b/drivers/media/vmc/vmc-core.c
@@ -0,0 +1,595 @@
+/*
+ * vmc-core.c Virtual Media Controller Driver
+ *
+ * Copyright (C) 2015 Helen Fornazier <helen.fornazier@gmail.com>
+ *
+ * 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.
+ *
+ */
+
+#include <linux/init.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/slab.h>
+#include <media/media-device.h>
+#include <media/v4l2-device.h>
+
+#include "vmc-capture.h"
+#include "vmc-core.h"
+#include "vmc-sensor.h"
+
+#define VMC_PDEV_NAME "vmc"
+#define VMC_MDEV_MODEL_NAME "VMC MDEV"
+
+#define VMC_ENT_LINK(src, srcpad, sink, sinkpad, link_flags) { \
+	.src_ent = src, \
+	.src_pad = srcpad, \
+	.sink_ent = sink, \
+	.sink_pad = sinkpad, \
+	.flags = link_flags, \
+}
+
+#define VMC_PIX_MAP(_code, _bpp, _pixelformat) {\
+	.code = _code,				\
+	.pixelformat = _pixelformat,		\
+	.bpp = _bpp,				\
+}
+
+struct vmc_device {
+	/* The pipeline configuration
+	 * (filled before calling vmc_device_register) */
+	const struct vmc_pipeline_config *pipe_cfg;
+
+	/* The Associated media_device parent */
+	struct media_device mdev;
+
+	/* Internal v4l2 parent device*/
+	struct v4l2_device v4l2_dev;
+
+	/* Internal topology */
+	struct vmc_ent_device **ved;
+};
+
+/**
+ * enum vmc_ent_node - Select the functionality of a node in the topology
+ * @VMC_ENT_NODE_SENSOR:	A node of type SENSOR simulates a camera sensor
+ *				generating internal images in bayer format and
+ *				propagating those images through the pipeline
+ * @VMC_ENT_NODE_CAPTURE:	A node of type CAPTURE is a v4l2 video_device
+ *				that exposes the received image from the
+ *				pipeline to the user space
+ * @VMC_ENT_NODE_INPUT:		A node of type INPUT is a v4l2 video_device that
+ *				receives images from the user space and
+ *				propagates them through the pipeline
+ * @VMC_ENT_NODE_DEBAYER:	A node type DEBAYER expects to receive a frame
+ *				in bayer format converts it to RGB
+ * @VMC_ENT_NODE_SCALER:	A node of type SCALER scales the received image
+ *				by a given multiplier
+ *
+ * This enum is used in the entity configuration struct to allow the definition
+ * of a custom topology specifying the role of each node on it.
+ */
+enum vmc_ent_node {
+	VMC_ENT_NODE_SENSOR,
+	VMC_ENT_NODE_CAPTURE,
+	VMC_ENT_NODE_INPUT,
+	VMC_ENT_NODE_DEBAYER,
+	VMC_ENT_NODE_SCALER,
+};
+
+/* Structure which describes individual configuration for each entity */
+struct vmc_ent_config {
+	const char *name;
+	size_t pads_qty;
+	const unsigned long *pads_flag;
+	enum vmc_ent_node node;
+};
+
+/* Structure which describes links between entities */
+struct vmc_ent_link {
+	unsigned int src_ent;
+	u16 src_pad;
+	unsigned int sink_ent;
+	u16 sink_pad;
+	u32 flags;
+};
+
+/* Structure which describes the whole topology */
+struct vmc_pipeline_config {
+	const struct vmc_ent_config *ents;
+	size_t num_ents;
+	const struct vmc_ent_link *links;
+	size_t num_links;
+};
+
+/* --------------------------------------------------------------------------
+ * Topology Configuration
+ */
+
+static const struct vmc_ent_config ent_config[] = {
+	{
+		.name = "Sensor A",
+		.pads_qty = 1,
+		.pads_flag = (const unsigned long[]){MEDIA_PAD_FL_SOURCE},
+		.node = VMC_ENT_NODE_SENSOR,
+	},
+	{
+		.name = "Sensor B",
+		.pads_qty = 1,
+		.pads_flag = (const unsigned long[]){MEDIA_PAD_FL_SOURCE},
+		.node = VMC_ENT_NODE_SENSOR,
+	},
+	{
+		.name = "Debayer A",
+		.pads_qty = 2,
+		.pads_flag = (const unsigned long[]){MEDIA_PAD_FL_SINK,
+						     MEDIA_PAD_FL_SOURCE},
+		.node = VMC_ENT_NODE_DEBAYER,
+	},
+	{
+		.name = "Debayer B",
+		.pads_qty = 2,
+		.pads_flag = (const unsigned long[]){MEDIA_PAD_FL_SINK,
+						     MEDIA_PAD_FL_SOURCE},
+		.node = VMC_ENT_NODE_DEBAYER,
+	},
+	{
+		.name = "Raw Capture 0",
+		.pads_qty = 1,
+		.pads_flag = (const unsigned long[]){MEDIA_PAD_FL_SINK},
+		.node = VMC_ENT_NODE_CAPTURE,
+	},
+	{
+		.name = "Raw Capture 1",
+		.pads_qty = 1,
+		.pads_flag = (const unsigned long[]){MEDIA_PAD_FL_SINK},
+		.node = VMC_ENT_NODE_CAPTURE,
+	},
+	{
+		.name = "RGB/YUV Input",
+		.pads_qty = 1,
+		.pads_flag = (const unsigned long[]){MEDIA_PAD_FL_SOURCE},
+		.node = VMC_ENT_NODE_INPUT,
+	},
+	{
+		.name = "Scaler",
+		.pads_qty = 2,
+		.pads_flag = (const unsigned long[]){MEDIA_PAD_FL_SINK,
+						     MEDIA_PAD_FL_SOURCE},
+		.node = VMC_ENT_NODE_SCALER,
+	},
+	{
+		.name = "RGB/YUV Capture",
+		.pads_qty = 1,
+		.pads_flag = (const unsigned long[]){MEDIA_PAD_FL_SINK},
+		.node = VMC_ENT_NODE_CAPTURE,
+	},
+};
+
+static const struct vmc_ent_link ent_links[] = {
+	/* Link: Sensor A (Pad 0)->(Pad 0) Debayer A */
+	VMC_ENT_LINK(0, 0, 2, 0, MEDIA_LNK_FL_ENABLED | MEDIA_LNK_FL_IMMUTABLE),
+	/* Link: Sensor A (Pad 0)->(Pad 0) Raw Capture 0 */
+	VMC_ENT_LINK(0, 0, 4, 0, MEDIA_LNK_FL_ENABLED | MEDIA_LNK_FL_IMMUTABLE),
+	/* Link: Sensor B (Pad 0)->(Pad 0) Debayer B */
+	VMC_ENT_LINK(1, 0, 3, 0, MEDIA_LNK_FL_ENABLED | MEDIA_LNK_FL_IMMUTABLE),
+	/* Link: Sensor B (Pad 0)->(Pad 0) Raw Capture 1 */
+	VMC_ENT_LINK(1, 0, 5, 0, MEDIA_LNK_FL_ENABLED | MEDIA_LNK_FL_IMMUTABLE),
+	/* Link: Debayer A (Pad 1)->(Pad 0) Scaler */
+	VMC_ENT_LINK(2, 1, 7, 0, MEDIA_LNK_FL_ENABLED),
+	/* Link: Debayer B (Pad 1)->(Pad 0) Scaler */
+	VMC_ENT_LINK(3, 1, 7, 0, 0),
+	/* Link: RGB/YUV Input (Pad 0)->(Pad 0) Scaler */
+	VMC_ENT_LINK(6, 0, 7, 0, 0),
+	/* Link: Scaler (Pad 1)->(Pad 0) RGB/YUV Capture */
+	VMC_ENT_LINK(7, 1, 8, 0, MEDIA_LNK_FL_ENABLED | MEDIA_LNK_FL_IMMUTABLE),
+};
+
+static const struct vmc_pipeline_config pipe_cfg = {
+	.ents		= ent_config,
+	.num_ents	= ARRAY_SIZE(ent_config),
+	.links		= ent_links,
+	.num_links	= ARRAY_SIZE(ent_links)
+};
+
+/* -------------------------------------------------------------------------- */
+
+static void vmc_dev_release(struct device *dev)
+{}
+
+static struct platform_device vmc_pdev = {
+	.name		= VMC_PDEV_NAME,
+	.dev.release	= vmc_dev_release,
+};
+
+const struct vmc_pix_fmt_map vmc_pix_fmt_map_list[] = {
+	/* TODO: add all missing formats */
+
+	/* RGB formats */
+	VMC_PIX_MAP(MEDIA_BUS_FMT_BGR888_1X24, 3, V4L2_PIX_FMT_BGR24),
+	VMC_PIX_MAP(MEDIA_BUS_FMT_RGB888_1X24, 3, V4L2_PIX_FMT_RGB24),
+	VMC_PIX_MAP(MEDIA_BUS_FMT_ARGB8888_1X32, 4, V4L2_PIX_FMT_ARGB32),
+
+	/* Bayer formats */
+	VMC_PIX_MAP(MEDIA_BUS_FMT_SBGGR8_1X8, 1, V4L2_PIX_FMT_SBGGR8),
+	VMC_PIX_MAP(MEDIA_BUS_FMT_SGBRG8_1X8, 1, V4L2_PIX_FMT_SGBRG8),
+	VMC_PIX_MAP(MEDIA_BUS_FMT_SGRBG8_1X8, 1, V4L2_PIX_FMT_SGRBG8),
+	VMC_PIX_MAP(MEDIA_BUS_FMT_SRGGB8_1X8, 1, V4L2_PIX_FMT_SRGGB8),
+	VMC_PIX_MAP(MEDIA_BUS_FMT_SBGGR10_1X10, 2, V4L2_PIX_FMT_SBGGR10),
+	VMC_PIX_MAP(MEDIA_BUS_FMT_SGBRG10_1X10, 2, V4L2_PIX_FMT_SGBRG10),
+	VMC_PIX_MAP(MEDIA_BUS_FMT_SGRBG10_1X10, 2, V4L2_PIX_FMT_SGRBG10),
+	VMC_PIX_MAP(MEDIA_BUS_FMT_SRGGB10_1X10, 2, V4L2_PIX_FMT_SRGGB10),
+	/* 10bit raw bayer a-law compressed to 8 bits */
+	VMC_PIX_MAP(MEDIA_BUS_FMT_SBGGR10_ALAW8_1X8, 1, V4L2_PIX_FMT_SBGGR10ALAW8),
+	VMC_PIX_MAP(MEDIA_BUS_FMT_SGBRG10_ALAW8_1X8, 1, V4L2_PIX_FMT_SGBRG10ALAW8),
+	VMC_PIX_MAP(MEDIA_BUS_FMT_SGRBG10_ALAW8_1X8, 1, V4L2_PIX_FMT_SGRBG10ALAW8),
+	VMC_PIX_MAP(MEDIA_BUS_FMT_SRGGB10_ALAW8_1X8, 1, V4L2_PIX_FMT_SRGGB10ALAW8),
+	/* 10bit raw bayer DPCM compressed to 8 bits */
+	VMC_PIX_MAP(MEDIA_BUS_FMT_SBGGR10_DPCM8_1X8, 1, V4L2_PIX_FMT_SBGGR10DPCM8),
+	VMC_PIX_MAP(MEDIA_BUS_FMT_SGBRG10_DPCM8_1X8, 1, V4L2_PIX_FMT_SGBRG10DPCM8),
+	VMC_PIX_MAP(MEDIA_BUS_FMT_SGRBG10_DPCM8_1X8, 1, V4L2_PIX_FMT_SGRBG10DPCM8),
+	VMC_PIX_MAP(MEDIA_BUS_FMT_SRGGB10_DPCM8_1X8, 1, V4L2_PIX_FMT_SRGGB10DPCM8),
+	VMC_PIX_MAP(MEDIA_BUS_FMT_SBGGR12_1X12, 2, V4L2_PIX_FMT_SBGGR12),
+	VMC_PIX_MAP(MEDIA_BUS_FMT_SGBRG12_1X12, 2, V4L2_PIX_FMT_SGBRG12),
+	VMC_PIX_MAP(MEDIA_BUS_FMT_SGRBG12_1X12, 2, V4L2_PIX_FMT_SGRBG12),
+	VMC_PIX_MAP(MEDIA_BUS_FMT_SRGGB12_1X12, 2, V4L2_PIX_FMT_SRGGB12),
+
+	/* End */
+	{0, 0, 0}
+};
+
+const struct vmc_pix_fmt_map *vmc_pix_fmt_map_by_code(u32 code)
+{
+	unsigned int i;
+
+	for (i = 0; vmc_pix_fmt_map_list[i].bpp; i++) {
+		if (vmc_pix_fmt_map_list[i].code == code)
+			return &vmc_pix_fmt_map_list[i];
+	}
+	return NULL;
+}
+
+const struct vmc_pix_fmt_map *vmc_pix_fmt_map_by_pixelformat(u32 pixelformat)
+{
+	unsigned int i;
+
+	for (i = 0; vmc_pix_fmt_map_list[i].bpp; i++) {
+		if (vmc_pix_fmt_map_list[i].pixelformat == pixelformat)
+			return &vmc_pix_fmt_map_list[i];
+	}
+	return NULL;
+}
+
+int vmc_propagate_frame(struct device *dev,
+			struct media_pad *src, const void *frame)
+{
+	unsigned int i;
+	struct media_link *link;
+	struct vmc_device *vmc = dev_get_drvdata(dev);
+
+	if (!(src->flags & MEDIA_PAD_FL_SOURCE))
+		return -EINVAL;
+
+	/* Send this frame to all sink pads that are direct linked */
+	for (i = 0; i < src->entity->num_links; i++) {
+		link = &src->entity->links[i];
+
+		if (link->source == src &&
+		    (link->flags & MEDIA_LNK_FL_ENABLED)) {
+			struct vmc_ent_device *ved;
+
+			ved = vmc->ved[link->sink->entity->id - 1];
+			if (ved && ved->process_frame)
+				ved->process_frame(ved, link->sink, frame);
+		}
+	}
+
+	return 0;
+}
+
+static void vmc_device_unregister(struct vmc_device *vmc)
+{
+	unsigned int i;
+
+	v4l2_device_unregister(&vmc->v4l2_dev);
+
+	media_device_unregister(&vmc->mdev);
+
+	/* Cleanup (only initialized) entities */
+	for (i = 0; i < vmc->pipe_cfg->num_ents; i++) {
+		if (vmc->ved[i] && vmc->ved[i]->destroy)
+			vmc->ved[i]->destroy(vmc->ved[i]);
+
+		vmc->ved[i] = NULL;
+	}
+}
+
+/* Helper function to allocate and initialize pads */
+struct media_pad *vmc_pads_init(u16 num_pads, const unsigned long *pads_flag)
+{
+	unsigned int i;
+	struct media_pad *pads;
+
+	/* Allocate memory for the pads */
+	pads = kcalloc(num_pads, sizeof(*pads), GFP_KERNEL);
+	if (!pads)
+		return ERR_PTR(-ENOMEM);
+
+	/* Initialize the pads */
+	for (i = 0; i < num_pads; i++) {
+		pads[i].index = i;
+		pads[i].flags = pads_flag[i];
+	}
+
+	return pads;
+}
+
+/* TODO: remove this function when all the
+ * entities specific code are implemented */
+static void vmc_raw_destroy(struct vmc_ent_device *ved)
+{
+	media_entity_cleanup(ved->ent);
+
+	vmc_pads_cleanup(ved->pads);
+
+	kfree(ved->ent);
+
+	kfree(ved);
+}
+
+/* TODO: remove this function when all the
+ * entities specific code are implemented */
+static struct vmc_ent_device *vmc_raw_create(struct v4l2_device *v4l2_dev,
+					     const char *const name,
+					     u16 num_pads,
+					     const unsigned long *pads_flag)
+{
+	int ret;
+	struct vmc_ent_device *ved;
+
+	/* Allocate the main ved struct */
+	ved = kzalloc(sizeof(*ved), GFP_KERNEL);
+	if (!ved)
+		return ERR_PTR(-ENOMEM);
+
+	/* Allocate the media entity */
+	ved->ent = kzalloc(sizeof(*ved->ent), GFP_KERNEL);
+	if (!ved->ent) {
+		ret = -ENOMEM;
+		goto err_free_ved;
+	}
+
+	/* Allocate the pads */
+	ved->pads = vmc_pads_init(num_pads, pads_flag);
+	if (IS_ERR(ved->pads)) {
+		ret = PTR_ERR(ved->pads);
+		goto err_free_ent;
+	}
+
+	/* Initialize the media entity */
+	ved->ent->name = name;
+	ved->ent->type = MEDIA_ENT_T_DEVNODE;
+	ret = media_entity_init(ved->ent, num_pads, ved->pads, num_pads);
+	if (ret)
+		goto err_cleanup_pads;
+
+	/* Register the media entity */
+	ret = media_device_register_entity(v4l2_dev->mdev, ved->ent);
+	if (ret)
+		goto err_cleanup_entity;
+
+	/* Fill out the destroy function and return */
+	ved->destroy = vmc_raw_destroy;
+	return ved;
+
+err_cleanup_entity:
+	media_entity_cleanup(ved->ent);
+err_cleanup_pads:
+	vmc_pads_cleanup(ved->pads);
+err_free_ent:
+	kfree(ved->ent);
+err_free_ved:
+	kfree(ved);
+
+	return ERR_PTR(ret);
+}
+
+static int vmc_device_register(struct vmc_device *vmc)
+{
+	unsigned int i;
+	int ret = 0;
+
+	/* Allocate memory for the vmc_ent_devices pointers */
+	vmc->ved = devm_kcalloc(vmc->mdev.dev, vmc->pipe_cfg->num_ents,
+				sizeof(*vmc->ved), GFP_KERNEL);
+	if (!vmc->ved)
+		return -ENOMEM;
+
+	/* Register the media device */
+	ret = media_device_register(&vmc->mdev);
+	if (ret) {
+		dev_err(vmc->mdev.dev,
+			"media device register failed (err=%d)\n", ret);
+		return ret;
+	}
+
+	/* Link the media device within the v4l2_device */
+	vmc->v4l2_dev.mdev = &vmc->mdev;
+
+	/* Register the v4l2 struct */
+	ret = v4l2_device_register(vmc->mdev.dev, &vmc->v4l2_dev);
+	if (ret) {
+		dev_err(vmc->mdev.dev,
+			"v4l2 device register failed (err=%d)\n", ret);
+		return ret;
+	}
+
+	/* Fill pads/entities structures and initialize entity */
+	for (i = 0; i < vmc->pipe_cfg->num_ents; i++) {
+		struct vmc_ent_device *(*create_func)(struct v4l2_device *,
+						      const char *const,
+						      u16,
+						      const unsigned long *);
+
+		/* Register the specific node */
+		switch (vmc->pipe_cfg->ents[i].node) {
+		case VMC_ENT_NODE_SENSOR:
+			create_func = vmc_sen_create;
+			break;
+
+		case VMC_ENT_NODE_CAPTURE:
+			create_func = vmc_cap_create;
+			break;
+
+		/* TODO: Instantiate the specific topology node */
+		case VMC_ENT_NODE_INPUT:
+		case VMC_ENT_NODE_DEBAYER:
+		case VMC_ENT_NODE_SCALER:
+		default:
+			/* TODO: remove this when all the entities specific
+			 * code are implemented */
+			create_func = vmc_raw_create;
+			break;
+		}
+
+		vmc->ved[i] = create_func(&vmc->v4l2_dev,
+					  vmc->pipe_cfg->ents[i].name,
+					  vmc->pipe_cfg->ents[i].pads_qty,
+					  vmc->pipe_cfg->ents[i].pads_flag);
+		if (IS_ERR(vmc->ved[i])) {
+			ret = PTR_ERR(vmc->ved[i]);
+			vmc->ved[i] = NULL;
+			goto err;
+		}
+	}
+
+	/* Initialize the links between entities */
+	for (i = 0; i < vmc->pipe_cfg->num_links; i++) {
+		const struct vmc_ent_link *link = &vmc->pipe_cfg->links[i];
+
+		ret = media_entity_create_link(vmc->ved[link->src_ent]->ent,
+					       link->src_pad,
+					       vmc->ved[link->sink_ent]->ent,
+					       link->sink_pad,
+					       link->flags);
+		if (ret)
+			goto err;
+	}
+
+	/* Expose all subdev's nodes*/
+	ret = v4l2_device_register_subdev_nodes(&vmc->v4l2_dev);
+	if (ret) {
+		dev_err(vmc->mdev.dev,
+			"vmc subdev nodes registration failed (err=%d)\n", ret);
+		goto err;
+	}
+
+	return 0;
+
+err:
+	/* Destroy de so far created topology */
+	vmc_device_unregister(vmc);
+
+	return ret;
+}
+
+static int vmc_probe(struct platform_device *pdev)
+{
+	struct vmc_device *vmc;
+	int ret;
+
+	/* Prepare the vmc topology structure */
+
+	/* Allocate memory for the vmc structure */
+	vmc = devm_kzalloc(&pdev->dev, sizeof(*vmc), GFP_KERNEL);
+	if (!vmc)
+		return -ENOMEM;
+
+	/* Set the pipeline configuration struct */
+	vmc->pipe_cfg = &pipe_cfg;
+
+	/* Set the mdev model name */
+	strlcpy(vmc->mdev.model, VMC_MDEV_MODEL_NAME,
+		sizeof(vmc->mdev.model));
+
+	/* Link dev with the media device. */
+	vmc->mdev.dev = &pdev->dev;
+
+	/* Create vmc topology */
+	ret = vmc_device_register(vmc);
+	if (ret) {
+		dev_err(vmc->mdev.dev,
+			"vmc device registration failed (err=%d)\n", ret);
+		return ret;
+	}
+
+	/* Link the topology object with the platform device object */
+	platform_set_drvdata(pdev, vmc);
+
+	return 0;
+}
+
+static int vmc_remove(struct platform_device *pdev)
+{
+	struct vmc_device *vmc;
+
+	/* Get the topology object linked with the platform device object */
+	vmc = platform_get_drvdata(pdev);
+
+	/* Destroy all the topology */
+	vmc_device_unregister(vmc);
+
+	return 0;
+}
+
+static struct platform_driver vmc_pdrv = {
+	.probe		= vmc_probe,
+	.remove		= vmc_remove,
+	.driver		= {
+		.name	= VMC_PDEV_NAME,
+	},
+};
+
+static int __init vmc_init(void)
+{
+	int ret;
+
+	ret = platform_device_register(&vmc_pdev);
+	if (ret) {
+		dev_err(&vmc_pdev.dev,
+			"platform device registration failed (err=%d)\n", ret);
+		return ret;
+	}
+
+	ret = platform_driver_register(&vmc_pdrv);
+	if (ret) {
+		dev_err(&vmc_pdev.dev,
+			"platform driver registration failed (err=%d)\n", ret);
+
+		platform_device_unregister(&vmc_pdev);
+	}
+
+	return ret;
+}
+
+static void __exit vmc_exit(void)
+{
+	platform_driver_unregister(&vmc_pdrv);
+
+	platform_device_unregister(&vmc_pdev);
+}
+
+module_init(vmc_init);
+module_exit(vmc_exit);
+
+MODULE_DESCRIPTION("Virtual Media Controller Driver (VMC)");
+MODULE_AUTHOR("Helen Fornazier <helen.fornazier@gmail.com>");
+MODULE_LICENSE("GPL");
diff --git a/drivers/media/vmc/vmc-core.h b/drivers/media/vmc/vmc-core.h
new file mode 100644
index 0000000..b987996
--- /dev/null
+++ b/drivers/media/vmc/vmc-core.h
@@ -0,0 +1,55 @@
+/*
+ * vmc-core.h Virtual Media Controller Driver
+ *
+ * Copyright (C) 2015 Helen Fornazier <helen.fornazier@gmail.com>
+ *
+ * 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.
+ *
+ */
+
+#ifndef _VMC_CORE_H_
+#define _VMC_CORE_H_
+
+#include <media/v4l2-device.h>
+
+/* Struct which matches the MEDIA_BUS_FMT_ codes with the corresponding
+ * V4L2_PIX_FMT_ fourcc pixelformat and its bytes per pixel (bpp) */
+struct vmc_pix_fmt_map {
+	unsigned int code;
+	unsigned int bpp;
+	u32 pixelformat;
+};
+extern const struct vmc_pix_fmt_map vmc_pix_fmt_map_list[];
+
+struct vmc_ent_device {
+	struct media_entity *ent;
+	struct media_pad *pads;
+	void (*destroy)(struct vmc_ent_device *);
+	void (*process_frame)(struct vmc_ent_device *ved,
+			      struct media_pad *sink, const void *frame);
+};
+
+int vmc_propagate_frame(struct device *dev,
+			struct media_pad *src, const void *frame);
+
+/* Helper functions to allocate/initialize pads and free them */
+struct media_pad *vmc_pads_init(u16 num_pads,
+				const unsigned long *pads_flag);
+static inline void vmc_pads_cleanup(struct media_pad *pads)
+{
+	kfree(pads);
+}
+
+const struct vmc_pix_fmt_map *vmc_pix_fmt_map_by_code(u32 code);
+
+const struct vmc_pix_fmt_map *vmc_pix_fmt_map_by_pixelformat(u32 pixelformat);
+
+#endif
diff --git a/drivers/media/vmc/vmc-sensor.c b/drivers/media/vmc/vmc-sensor.c
new file mode 100644
index 0000000..655386c
--- /dev/null
+++ b/drivers/media/vmc/vmc-sensor.c
@@ -0,0 +1,275 @@
+/*
+ * vmc-sensor.c Virtual Media Controller Driver
+ *
+ * Copyright (C) 2015 Helen Fornazier <helen.fornazier@gmail.com>
+ *
+ * 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.
+ *
+ */
+
+#include <linux/freezer.h>
+#include <linux/vmalloc.h>
+#include <linux/v4l2-mediabus.h>
+#include <media/v4l2-subdev.h>
+
+#include "vmc-core.h"
+#include "vmc-sensor.h"
+
+static int vmc_sen_enum_mbus_code(struct v4l2_subdev *sd,
+				  struct v4l2_subdev_pad_config *cfg,
+				  struct v4l2_subdev_mbus_code_enum *code)
+{
+	struct vmc_sen_device *vsen = v4l2_get_subdevdata(sd);
+
+	/* Check if it is a valid pad */
+	if (code->pad >= vsen->sd.entity.num_pads)
+		return -EINVAL;
+
+	code->code = vsen->mbus_format.code;
+
+	return 0;
+}
+
+static int vmc_sen_enum_frame_size(struct v4l2_subdev *sd,
+				   struct v4l2_subdev_pad_config *cfg,
+				   struct v4l2_subdev_frame_size_enum *fse)
+{
+	struct vmc_sen_device *vsen = v4l2_get_subdevdata(sd);
+
+	/* Check if it is a valid pad */
+	if (fse->pad >= vsen->sd.entity.num_pads ||
+	    !(vsen->sd.entity.pads[fse->pad].flags & MEDIA_PAD_FL_SOURCE))
+		return -EINVAL;
+
+	/* TODO: Add support to other formats */
+	if (fse->index)
+		return -EINVAL;
+
+	/* TODO: Add support for other codes */
+	if (fse->code != vsen->mbus_format.code)
+		return -EINVAL;
+
+	fse->min_width = vsen->mbus_format.width;
+	fse->max_width = vsen->mbus_format.width;
+	fse->min_height = vsen->mbus_format.height;
+	fse->max_height = vsen->mbus_format.height;
+
+	return 0;
+}
+
+static int vmc_sen_get_fmt(struct v4l2_subdev *sd,
+			   struct v4l2_subdev_pad_config *cfg,
+			   struct v4l2_subdev_format *format)
+{
+	struct vmc_sen_device *vsen = v4l2_get_subdevdata(sd);
+
+	format->format = vsen->mbus_format;
+
+	return 0;
+}
+
+static int vmc_sen_set_fmt(struct v4l2_subdev *sd,
+			   struct v4l2_subdev_pad_config *cfg,
+			   struct v4l2_subdev_format *format)
+{
+	/* TODO: Add support to other formats and try format feature */
+	return vmc_sen_get_fmt(sd, cfg, format);
+}
+
+static const struct v4l2_subdev_pad_ops vmc_sd_pad_ops = {
+	.enum_mbus_code		= vmc_sen_enum_mbus_code,
+	.enum_frame_size	= vmc_sen_enum_frame_size,
+	.get_fmt		= vmc_sen_get_fmt,
+	.set_fmt		= vmc_sen_set_fmt,
+};
+
+/* media operations */
+static const struct media_entity_operations vmc_sen_mops = {
+	.link_validate = v4l2_subdev_link_validate,
+};
+
+static int vmc_thread_sen(void *data)
+{
+	unsigned int i;
+	struct vmc_sen_device *vsen = data;
+
+	set_freezable();
+
+	for (;;) {
+		try_to_freeze();
+		if (kthread_should_stop())
+			break;
+
+		memset(vsen->frame, 100, vsen->frame_size);
+
+		/* Send the frame to all source pads */
+		for (i = 0; i < vsen->sd.entity.num_pads; i++)
+			if (vsen->sd.entity.pads[i].flags & MEDIA_PAD_FL_SOURCE)
+				vmc_propagate_frame(vsen->dev,
+						    &vsen->sd.entity.pads[i],
+						    vsen->frame);
+
+		/* Wait one second */
+		schedule_timeout_interruptible(HZ);
+	}
+
+	return 0;
+}
+
+static int vmc_sen_s_stream(struct v4l2_subdev *sd, int enable)
+{
+	int ret;
+	struct vmc_sen_device *vsen = v4l2_get_subdevdata(sd);
+
+	if (enable) {
+		const struct vmc_pix_fmt_map *vpix;
+
+		if (vsen->kthread_sen)
+			return -EINVAL;
+
+		/* Calculate the frame size */
+		vpix = vmc_pix_fmt_map_by_code(vsen->mbus_format.code);
+		/* This should never be NULL, as we won't allow any format
+		 * other then the ones in the vmc_pix_fmt_map_list table */
+		BUG_ON(!vpix);
+		vsen->frame_size = vsen->mbus_format.width * vpix->bpp *
+				   vsen->mbus_format.height;
+
+		/* Allocate the frame buffer. Use vmalloc to be able to
+		 * allocate a large amount of memory*/
+		vsen->frame = vmalloc(vsen->frame_size);
+		if (!vsen->frame)
+			return -ENOMEM;
+
+		/* Initialize the image generator thread */
+		vsen->kthread_sen = kthread_run(vmc_thread_sen, vsen,
+						"%s-sen", vsen->v4l2_dev->name);
+		if (IS_ERR(vsen->kthread_sen)) {
+			v4l2_err(vsen->v4l2_dev, "kernel_thread() failed\n");
+			vfree(vsen->frame);
+			vsen->frame = NULL;
+			return PTR_ERR(vsen->kthread_sen);
+		}
+	} else {
+		if (!vsen->kthread_sen)
+			return -EINVAL;
+
+		/* Stop image generator */
+		ret = kthread_stop(vsen->kthread_sen);
+		vsen->kthread_sen = NULL;
+
+		vfree(vsen->frame);
+		vsen->frame = NULL;
+		return ret;
+	}
+
+	return 0;
+}
+
+struct v4l2_subdev_video_ops vmc_sd_video_ops = {
+	.s_stream = vmc_sen_s_stream,
+};
+
+static const struct v4l2_subdev_ops vmc_sd_ops = {
+	.pad = &vmc_sd_pad_ops,
+	.video = &vmc_sd_video_ops,
+};
+
+void vmc_sen_destroy(struct vmc_ent_device *ved)
+{
+	struct vmc_sen_device *vsen = container_of(ved,
+						   struct vmc_sen_device, ved);
+
+	media_entity_cleanup(ved->ent);
+	v4l2_device_unregister_subdev(&vsen->sd);
+	kfree(vsen);
+}
+
+struct vmc_ent_device *vmc_sen_create(struct v4l2_device *v4l2_dev,
+				      const char *const name,
+				      u16 num_pads,
+				      const unsigned long *pads_flag)
+{
+	int ret;
+	struct vmc_sen_device *vsen;
+
+	if (!v4l2_dev || !v4l2_dev->dev || !name || (num_pads && !pads_flag))
+		return ERR_PTR(-EINVAL);
+
+	/* Allocate the vsen struct */
+	vsen = kzalloc(sizeof(*vsen), GFP_KERNEL);
+	if (!vsen)
+		return ERR_PTR(-ENOMEM);
+
+	/* Link the vmc_sen_device struct with the v4l2 parent */
+	vsen->v4l2_dev = v4l2_dev;
+	/* Link the vmc_sen_device struct with the dev parent */
+	vsen->dev = v4l2_dev->dev;
+
+	/* Allocate the pads */
+	vsen->ved.pads = vmc_pads_init(num_pads, pads_flag);
+	if (IS_ERR(vsen->ved.pads)) {
+		ret = PTR_ERR(vsen->ved.pads);
+		goto err_free_vsen;
+	}
+
+	/* Initialize the media entity */
+	vsen->sd.entity.name = name;
+	vsen->sd.entity.type = MEDIA_ENT_T_V4L2_SUBDEV;
+	ret = media_entity_init(&vsen->sd.entity, num_pads,
+				vsen->ved.pads, num_pads);
+	if (ret)
+		goto err_clean_pads;
+
+	/* Initialize the subdev */
+	v4l2_subdev_init(&vsen->sd, &vmc_sd_ops);
+	vsen->sd.entity.ops = &vmc_sen_mops;
+	vsen->sd.owner = THIS_MODULE;
+	strlcpy(vsen->sd.name, name, sizeof(vsen->sd.name));
+
+	/* Expose this subdev to user space */
+	vsen->sd.flags = V4L2_SUBDEV_FL_HAS_DEVNODE;
+
+	/* Register the subdev with the v4l2 and the media framework */
+	ret = v4l2_device_register_subdev(vsen->v4l2_dev, &vsen->sd);
+	if (ret) {
+		dev_err(vsen->dev,
+			"subdev register failed (err=%d)\n", ret);
+		goto err_clean_m_ent;
+	}
+
+	/* Link the sd with the vmc_sen_device struct */
+	v4l2_set_subdevdata(&vsen->sd, vsen);
+
+	/* Set the active frame format (this is hardcoded for now) */
+	vsen->mbus_format.width = 640;
+	vsen->mbus_format.height = 480;
+	vsen->mbus_format.code = MEDIA_BUS_FMT_RGB888_1X24;
+	vsen->mbus_format.field = V4L2_FIELD_INTERLACED;
+	vsen->mbus_format.colorspace = V4L2_COLORSPACE_SRGB;
+	vsen->mbus_format.quantization = V4L2_QUANTIZATION_FULL_RANGE;
+	vsen->mbus_format.xfer_func = V4L2_XFER_FUNC_SRGB;
+
+	/* Fill the vmc_ent_device struct */
+	vsen->ved.destroy = vmc_sen_destroy;
+	vsen->ved.ent = &vsen->sd.entity;
+
+	return &vsen->ved;
+
+err_clean_m_ent:
+	media_entity_cleanup(&vsen->sd.entity);
+err_clean_pads:
+	vmc_pads_cleanup(vsen->ved.pads);
+err_free_vsen:
+	kfree(vsen);
+
+	return ERR_PTR(ret);
+}
diff --git a/drivers/media/vmc/vmc-sensor.h b/drivers/media/vmc/vmc-sensor.h
new file mode 100644
index 0000000..64f7a36
--- /dev/null
+++ b/drivers/media/vmc/vmc-sensor.h
@@ -0,0 +1,40 @@
+/*
+ * vmc-sensor.h Virtual Media Controller Driver
+ *
+ * Copyright (C) 2015 Helen Fornazier <helen.fornazier@gmail.com>
+ *
+ * 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.
+ *
+ */
+
+#ifndef _VMC_SENSOR_H_
+#define _VMC_SENSOR_H_
+
+struct vmc_sen_device {
+	struct vmc_ent_device ved;
+	struct v4l2_subdev sd;
+	struct v4l2_device *v4l2_dev;
+	struct device *dev;
+	struct task_struct *kthread_sen;
+	u8 *frame;
+	/* The active format */
+	struct v4l2_mbus_framefmt mbus_format;
+	int frame_size;
+};
+
+struct vmc_ent_device *vmc_sen_create(struct v4l2_device *v4l2_dev,
+				      const char *const name,
+				      u16 num_pads,
+				      const unsigned long *pads_flag);
+
+void vmc_sen_destroy(struct vmc_ent_device *ved);
+
+#endif
-- 
1.9.1