[media] v4l: vsp1: Add histogram support

The histogram common code will be used to implement support for both the
HGO and HGT histogram computation engines.

Signed-off-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>

4 files changed, 732 insertions, 0 deletions

diff --git a/drivers/media/platform/Kconfig b/drivers/media/platform/Kconfig
index 7321f6123659..552e7f2df6fd 100644
--- a/drivers/media/platform/Kconfig
+++ b/drivers/media/platform/Kconfig
@@ -420,6 +420,7 @@ config VIDEO_RENESAS_VSP1
 	depends on (ARCH_RENESAS && OF) || COMPILE_TEST
 	depends on (!ARM64 && !VIDEO_RENESAS_FCP) || VIDEO_RENESAS_FCP
 	select VIDEOBUF2_DMA_CONTIG
+	select VIDEOBUF2_VMALLOC
 	---help---
 	  This is a V4L2 driver for the Renesas VSP1 video processing engine.
 
diff --git a/drivers/media/platform/vsp1/Makefile b/drivers/media/platform/vsp1/Makefile
index 1328e1bd2143..c559536f7867 100644
--- a/drivers/media/platform/vsp1/Makefile
+++ b/drivers/media/platform/vsp1/Makefile
@@ -3,6 +3,7 @@ vsp1-y					+= vsp1_dl.o vsp1_drm.o vsp1_video.o
 vsp1-y					+= vsp1_rpf.o vsp1_rwpf.o vsp1_wpf.o
 vsp1-y					+= vsp1_clu.o vsp1_hsit.o vsp1_lut.o
 vsp1-y					+= vsp1_bru.o vsp1_sru.o vsp1_uds.o
+vsp1-y					+= vsp1_histo.o
 vsp1-y					+= vsp1_lif.o
 
 obj-$(CONFIG_VIDEO_RENESAS_VSP1)	+= vsp1.o
diff --git a/drivers/media/platform/vsp1/vsp1_histo.c b/drivers/media/platform/vsp1/vsp1_histo.c
new file mode 100644
index 000000000000..afab77cf4fa5
--- /dev/null
+++ b/drivers/media/platform/vsp1/vsp1_histo.c
@@ -0,0 +1,646 @@
+/*
+ * vsp1_histo.c  --  R-Car VSP1 Histogram API
+ *
+ * Copyright (C) 2016 Renesas Electronics Corporation
+ * Copyright (C) 2016 Laurent Pinchart
+ *
+ * Contact: Laurent Pinchart (laurent.pinchart@ideasonboard.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.
+ */
+
+#include <linux/device.h>
+#include <linux/gfp.h>
+
+#include <media/v4l2-ioctl.h>
+#include <media/v4l2-subdev.h>
+#include <media/videobuf2-vmalloc.h>
+
+#include "vsp1.h"
+#include "vsp1_histo.h"
+#include "vsp1_pipe.h"
+
+#define HISTO_MIN_SIZE				4U
+#define HISTO_MAX_SIZE				8192U
+
+/* -----------------------------------------------------------------------------
+ * Buffer Operations
+ */
+
+static inline struct vsp1_histogram_buffer *
+to_vsp1_histogram_buffer(struct vb2_v4l2_buffer *vbuf)
+{
+	return container_of(vbuf, struct vsp1_histogram_buffer, buf);
+}
+
+struct vsp1_histogram_buffer *
+vsp1_histogram_buffer_get(struct vsp1_histogram *histo)
+{
+	struct vsp1_histogram_buffer *buf = NULL;
+	unsigned long flags;
+
+	spin_lock_irqsave(&histo->irqlock, flags);
+
+	if (list_empty(&histo->irqqueue))
+		goto done;
+
+	buf = list_first_entry(&histo->irqqueue, struct vsp1_histogram_buffer,
+			       queue);
+	list_del(&buf->queue);
+	histo->readout = true;
+
+done:
+	spin_unlock_irqrestore(&histo->irqlock, flags);
+	return buf;
+}
+
+void vsp1_histogram_buffer_complete(struct vsp1_histogram *histo,
+				    struct vsp1_histogram_buffer *buf,
+				    size_t size)
+{
+	struct vsp1_pipeline *pipe = histo->pipe;
+	unsigned long flags;
+
+	/*
+	 * The pipeline pointer is guaranteed to be valid as this function is
+	 * called from the frame completion interrupt handler, which can only
+	 * occur when video streaming is active.
+	 */
+	buf->buf.sequence = pipe->sequence;
+	buf->buf.vb2_buf.timestamp = ktime_get_ns();
+	vb2_set_plane_payload(&buf->buf.vb2_buf, 0, size);
+	vb2_buffer_done(&buf->buf.vb2_buf, VB2_BUF_STATE_DONE);
+
+	spin_lock_irqsave(&histo->irqlock, flags);
+	histo->readout = false;
+	wake_up(&histo->wait_queue);
+	spin_unlock_irqrestore(&histo->irqlock, flags);
+}
+
+/* -----------------------------------------------------------------------------
+ * videobuf2 Queue Operations
+ */
+
+static int histo_queue_setup(struct vb2_queue *vq, unsigned int *nbuffers,
+			     unsigned int *nplanes, unsigned int sizes[],
+			     struct device *alloc_devs[])
+{
+	struct vsp1_histogram *histo = vb2_get_drv_priv(vq);
+
+	if (*nplanes) {
+		if (*nplanes != 1)
+			return -EINVAL;
+
+		if (sizes[0] < histo->data_size)
+			return -EINVAL;
+
+		return 0;
+	}
+
+	*nplanes = 1;
+	sizes[0] = histo->data_size;
+
+	return 0;
+}
+
+static int histo_buffer_prepare(struct vb2_buffer *vb)
+{
+	struct vb2_v4l2_buffer *vbuf = to_vb2_v4l2_buffer(vb);
+	struct vsp1_histogram *histo = vb2_get_drv_priv(vb->vb2_queue);
+	struct vsp1_histogram_buffer *buf = to_vsp1_histogram_buffer(vbuf);
+
+	if (vb->num_planes != 1)
+		return -EINVAL;
+
+	if (vb2_plane_size(vb, 0) < histo->data_size)
+		return -EINVAL;
+
+	buf->addr = vb2_plane_vaddr(vb, 0);
+
+	return 0;
+}
+
+static void histo_buffer_queue(struct vb2_buffer *vb)
+{
+	struct vb2_v4l2_buffer *vbuf = to_vb2_v4l2_buffer(vb);
+	struct vsp1_histogram *histo = vb2_get_drv_priv(vb->vb2_queue);
+	struct vsp1_histogram_buffer *buf = to_vsp1_histogram_buffer(vbuf);
+	unsigned long flags;
+
+	spin_lock_irqsave(&histo->irqlock, flags);
+	list_add_tail(&buf->queue, &histo->irqqueue);
+	spin_unlock_irqrestore(&histo->irqlock, flags);
+}
+
+static int histo_start_streaming(struct vb2_queue *vq, unsigned int count)
+{
+	return 0;
+}
+
+static void histo_stop_streaming(struct vb2_queue *vq)
+{
+	struct vsp1_histogram *histo = vb2_get_drv_priv(vq);
+	struct vsp1_histogram_buffer *buffer;
+	unsigned long flags;
+
+	spin_lock_irqsave(&histo->irqlock, flags);
+
+	/* Remove all buffers from the IRQ queue. */
+	list_for_each_entry(buffer, &histo->irqqueue, queue)
+		vb2_buffer_done(&buffer->buf.vb2_buf, VB2_BUF_STATE_ERROR);
+	INIT_LIST_HEAD(&histo->irqqueue);
+
+	/* Wait for the buffer being read out (if any) to complete. */
+	wait_event_lock_irq(histo->wait_queue, !histo->readout, histo->irqlock);
+
+	spin_unlock_irqrestore(&histo->irqlock, flags);
+}
+
+static const struct vb2_ops histo_video_queue_qops = {
+	.queue_setup = histo_queue_setup,
+	.buf_prepare = histo_buffer_prepare,
+	.buf_queue = histo_buffer_queue,
+	.wait_prepare = vb2_ops_wait_prepare,
+	.wait_finish = vb2_ops_wait_finish,
+	.start_streaming = histo_start_streaming,
+	.stop_streaming = histo_stop_streaming,
+};
+
+/* -----------------------------------------------------------------------------
+ * V4L2 Subdevice Operations
+ */
+
+static int histo_enum_mbus_code(struct v4l2_subdev *subdev,
+				struct v4l2_subdev_pad_config *cfg,
+				struct v4l2_subdev_mbus_code_enum *code)
+{
+	struct vsp1_histogram *histo = subdev_to_histo(subdev);
+
+	if (code->pad == HISTO_PAD_SOURCE) {
+		code->code = MEDIA_BUS_FMT_FIXED;
+		return 0;
+	}
+
+	return vsp1_subdev_enum_mbus_code(subdev, cfg, code, histo->formats,
+					  histo->num_formats);
+}
+
+static int histo_enum_frame_size(struct v4l2_subdev *subdev,
+				 struct v4l2_subdev_pad_config *cfg,
+				 struct v4l2_subdev_frame_size_enum *fse)
+{
+	if (fse->pad != HISTO_PAD_SINK)
+		return -EINVAL;
+
+	return vsp1_subdev_enum_frame_size(subdev, cfg, fse, HISTO_MIN_SIZE,
+					   HISTO_MIN_SIZE, HISTO_MAX_SIZE,
+					   HISTO_MAX_SIZE);
+}
+
+static int histo_get_selection(struct v4l2_subdev *subdev,
+			       struct v4l2_subdev_pad_config *cfg,
+			       struct v4l2_subdev_selection *sel)
+{
+	struct vsp1_histogram *histo = subdev_to_histo(subdev);
+	struct v4l2_subdev_pad_config *config;
+	struct v4l2_mbus_framefmt *format;
+	struct v4l2_rect *crop;
+	int ret = 0;
+
+	if (sel->pad != HISTO_PAD_SINK)
+		return -EINVAL;
+
+	mutex_lock(&histo->entity.lock);
+
+	config = vsp1_entity_get_pad_config(&histo->entity, cfg, sel->which);
+	if (!config) {
+		ret = -EINVAL;
+		goto done;
+	}
+
+	switch (sel->target) {
+	case V4L2_SEL_TGT_COMPOSE_BOUNDS:
+	case V4L2_SEL_TGT_COMPOSE_DEFAULT:
+		crop = vsp1_entity_get_pad_selection(&histo->entity, config,
+						     HISTO_PAD_SINK,
+						     V4L2_SEL_TGT_CROP);
+		sel->r.left = 0;
+		sel->r.top = 0;
+		sel->r.width = crop->width;
+		sel->r.height = crop->height;
+		break;
+
+	case V4L2_SEL_TGT_CROP_BOUNDS:
+	case V4L2_SEL_TGT_CROP_DEFAULT:
+		format = vsp1_entity_get_pad_format(&histo->entity, config,
+						    HISTO_PAD_SINK);
+		sel->r.left = 0;
+		sel->r.top = 0;
+		sel->r.width = format->width;
+		sel->r.height = format->height;
+		break;
+
+	case V4L2_SEL_TGT_COMPOSE:
+	case V4L2_SEL_TGT_CROP:
+		sel->r = *vsp1_entity_get_pad_selection(&histo->entity, config,
+							sel->pad, sel->target);
+		break;
+
+	default:
+		ret = -EINVAL;
+		break;
+	}
+
+done:
+	mutex_unlock(&histo->entity.lock);
+	return ret;
+}
+
+static int histo_set_crop(struct v4l2_subdev *subdev,
+			  struct v4l2_subdev_pad_config *config,
+			 struct v4l2_subdev_selection *sel)
+{
+	struct vsp1_histogram *histo = subdev_to_histo(subdev);
+	struct v4l2_mbus_framefmt *format;
+	struct v4l2_rect *selection;
+
+	/* The crop rectangle must be inside the input frame. */
+	format = vsp1_entity_get_pad_format(&histo->entity, config,
+					    HISTO_PAD_SINK);
+	sel->r.left = clamp_t(unsigned int, sel->r.left, 0, format->width - 1);
+	sel->r.top = clamp_t(unsigned int, sel->r.top, 0, format->height - 1);
+	sel->r.width = clamp_t(unsigned int, sel->r.width, HISTO_MIN_SIZE,
+			       format->width - sel->r.left);
+	sel->r.height = clamp_t(unsigned int, sel->r.height, HISTO_MIN_SIZE,
+				format->height - sel->r.top);
+
+	/* Set the crop rectangle and reset the compose rectangle. */
+	selection = vsp1_entity_get_pad_selection(&histo->entity, config,
+						  sel->pad, V4L2_SEL_TGT_CROP);
+	*selection = sel->r;
+
+	selection = vsp1_entity_get_pad_selection(&histo->entity, config,
+						  sel->pad,
+						  V4L2_SEL_TGT_COMPOSE);
+	*selection = sel->r;
+
+	return 0;
+}
+
+static int histo_set_compose(struct v4l2_subdev *subdev,
+			     struct v4l2_subdev_pad_config *config,
+			     struct v4l2_subdev_selection *sel)
+{
+	struct vsp1_histogram *histo = subdev_to_histo(subdev);
+	struct v4l2_rect *compose;
+	struct v4l2_rect *crop;
+	unsigned int ratio;
+
+	/*
+	 * The compose rectangle is used to configure downscaling, the top left
+	 * corner is fixed to (0,0) and the size to 1/2 or 1/4 of the crop
+	 * rectangle.
+	 */
+	sel->r.left = 0;
+	sel->r.top = 0;
+
+	crop = vsp1_entity_get_pad_selection(&histo->entity, config, sel->pad,
+					     V4L2_SEL_TGT_CROP);
+
+	/*
+	 * Clamp the width and height to acceptable values first and then
+	 * compute the closest rounded dividing ratio.
+	 *
+	 * Ratio	Rounded ratio
+	 * --------------------------
+	 * [1.0 1.5[	1
+	 * [1.5 3.0[	2
+	 * [3.0 4.0]	4
+	 *
+	 * The rounded ratio can be computed using
+	 *
+	 * 1 << (ceil(ratio * 2) / 3)
+	 */
+	sel->r.width = clamp(sel->r.width, crop->width / 4, crop->width);
+	ratio = 1 << (crop->width * 2 / sel->r.width / 3);
+	sel->r.width = crop->width / ratio;
+
+
+	sel->r.height = clamp(sel->r.height, crop->height / 4, crop->height);
+	ratio = 1 << (crop->height * 2 / sel->r.height / 3);
+	sel->r.height = crop->height / ratio;
+
+	compose = vsp1_entity_get_pad_selection(&histo->entity, config,
+						sel->pad,
+						V4L2_SEL_TGT_COMPOSE);
+	*compose = sel->r;
+
+	return 0;
+}
+
+static int histo_set_selection(struct v4l2_subdev *subdev,
+			       struct v4l2_subdev_pad_config *cfg,
+			       struct v4l2_subdev_selection *sel)
+{
+	struct vsp1_histogram *histo = subdev_to_histo(subdev);
+	struct v4l2_subdev_pad_config *config;
+	int ret;
+
+	if (sel->pad != HISTO_PAD_SINK)
+		return -EINVAL;
+
+	mutex_lock(&histo->entity.lock);
+
+	config = vsp1_entity_get_pad_config(&histo->entity, cfg, sel->which);
+	if (!config) {
+		ret = -EINVAL;
+		goto done;
+	}
+
+	if (sel->target == V4L2_SEL_TGT_CROP)
+		ret = histo_set_crop(subdev, config, sel);
+	else if (sel->target == V4L2_SEL_TGT_COMPOSE)
+		ret = histo_set_compose(subdev, config, sel);
+	else
+		ret = -EINVAL;
+
+done:
+	mutex_unlock(&histo->entity.lock);
+	return ret;
+}
+
+static int histo_get_format(struct v4l2_subdev *subdev,
+			    struct v4l2_subdev_pad_config *cfg,
+			    struct v4l2_subdev_format *fmt)
+{
+	if (fmt->pad == HISTO_PAD_SOURCE) {
+		fmt->format.code = MEDIA_BUS_FMT_FIXED;
+		fmt->format.width = 0;
+		fmt->format.height = 0;
+		fmt->format.field = V4L2_FIELD_NONE;
+		fmt->format.colorspace = V4L2_COLORSPACE_RAW;
+		return 0;
+	}
+
+	return vsp1_subdev_get_pad_format(subdev, cfg, fmt);
+}
+
+static int histo_set_format(struct v4l2_subdev *subdev,
+			    struct v4l2_subdev_pad_config *cfg,
+			    struct v4l2_subdev_format *fmt)
+{
+	struct vsp1_histogram *histo = subdev_to_histo(subdev);
+	struct v4l2_subdev_pad_config *config;
+	struct v4l2_mbus_framefmt *format;
+	struct v4l2_rect *selection;
+	unsigned int i;
+	int ret = 0;
+
+	if (fmt->pad != HISTO_PAD_SINK)
+		return histo_get_format(subdev, cfg, fmt);
+
+	mutex_lock(&histo->entity.lock);
+
+	config = vsp1_entity_get_pad_config(&histo->entity, cfg, fmt->which);
+	if (!config) {
+		ret = -EINVAL;
+		goto done;
+	}
+
+	/*
+	 * Default to the first format if the requested format is not
+	 * supported.
+	 */
+	for (i = 0; i < histo->num_formats; ++i) {
+		if (fmt->format.code == histo->formats[i])
+			break;
+	}
+	if (i == histo->num_formats)
+		fmt->format.code = histo->formats[0];
+
+	format = vsp1_entity_get_pad_format(&histo->entity, config, fmt->pad);
+
+	format->code = fmt->format.code;
+	format->width = clamp_t(unsigned int, fmt->format.width,
+				HISTO_MIN_SIZE, HISTO_MAX_SIZE);
+	format->height = clamp_t(unsigned int, fmt->format.height,
+				 HISTO_MIN_SIZE, HISTO_MAX_SIZE);
+	format->field = V4L2_FIELD_NONE;
+	format->colorspace = V4L2_COLORSPACE_SRGB;
+
+	fmt->format = *format;
+
+	/* Reset the crop and compose rectangles */
+	selection = vsp1_entity_get_pad_selection(&histo->entity, config,
+						  fmt->pad, V4L2_SEL_TGT_CROP);
+	selection->left = 0;
+	selection->top = 0;
+	selection->width = format->width;
+	selection->height = format->height;
+
+	selection = vsp1_entity_get_pad_selection(&histo->entity, config,
+						  fmt->pad,
+						  V4L2_SEL_TGT_COMPOSE);
+	selection->left = 0;
+	selection->top = 0;
+	selection->width = format->width;
+	selection->height = format->height;
+
+done:
+	mutex_unlock(&histo->entity.lock);
+	return ret;
+}
+
+static const struct v4l2_subdev_pad_ops histo_pad_ops = {
+	.enum_mbus_code = histo_enum_mbus_code,
+	.enum_frame_size = histo_enum_frame_size,
+	.get_fmt = histo_get_format,
+	.set_fmt = histo_set_format,
+	.get_selection = histo_get_selection,
+	.set_selection = histo_set_selection,
+};
+
+static const struct v4l2_subdev_ops histo_ops = {
+	.pad    = &histo_pad_ops,
+};
+
+/* -----------------------------------------------------------------------------
+ * V4L2 ioctls
+ */
+
+static int histo_v4l2_querycap(struct file *file, void *fh,
+			       struct v4l2_capability *cap)
+{
+	struct v4l2_fh *vfh = file->private_data;
+	struct vsp1_histogram *histo = vdev_to_histo(vfh->vdev);
+
+	cap->capabilities = V4L2_CAP_DEVICE_CAPS | V4L2_CAP_STREAMING
+			  | V4L2_CAP_VIDEO_CAPTURE_MPLANE
+			  | V4L2_CAP_VIDEO_OUTPUT_MPLANE
+			  | V4L2_CAP_META_CAPTURE;
+	cap->device_caps = V4L2_CAP_META_CAPTURE
+			 | V4L2_CAP_STREAMING;
+
+	strlcpy(cap->driver, "vsp1", sizeof(cap->driver));
+	strlcpy(cap->card, histo->video.name, sizeof(cap->card));
+	snprintf(cap->bus_info, sizeof(cap->bus_info), "platform:%s",
+		 dev_name(histo->entity.vsp1->dev));
+
+	return 0;
+}
+
+static int histo_v4l2_enum_format(struct file *file, void *fh,
+				  struct v4l2_fmtdesc *f)
+{
+	struct v4l2_fh *vfh = file->private_data;
+	struct vsp1_histogram *histo = vdev_to_histo(vfh->vdev);
+
+	if (f->index > 0 || f->type != histo->queue.type)
+		return -EINVAL;
+
+	f->pixelformat = histo->meta_format;
+
+	return 0;
+}
+
+static int histo_v4l2_get_format(struct file *file, void *fh,
+				 struct v4l2_format *format)
+{
+	struct v4l2_fh *vfh = file->private_data;
+	struct vsp1_histogram *histo = vdev_to_histo(vfh->vdev);
+	struct v4l2_meta_format *meta = &format->fmt.meta;
+
+	if (format->type != histo->queue.type)
+		return -EINVAL;
+
+	memset(meta, 0, sizeof(*meta));
+
+	meta->dataformat = histo->meta_format;
+	meta->buffersize = histo->data_size;
+
+	return 0;
+}
+
+static const struct v4l2_ioctl_ops histo_v4l2_ioctl_ops = {
+	.vidioc_querycap		= histo_v4l2_querycap,
+	.vidioc_enum_fmt_meta_cap	= histo_v4l2_enum_format,
+	.vidioc_g_fmt_meta_cap		= histo_v4l2_get_format,
+	.vidioc_s_fmt_meta_cap		= histo_v4l2_get_format,
+	.vidioc_try_fmt_meta_cap	= histo_v4l2_get_format,
+	.vidioc_reqbufs			= vb2_ioctl_reqbufs,
+	.vidioc_querybuf		= vb2_ioctl_querybuf,
+	.vidioc_qbuf			= vb2_ioctl_qbuf,
+	.vidioc_dqbuf			= vb2_ioctl_dqbuf,
+	.vidioc_create_bufs		= vb2_ioctl_create_bufs,
+	.vidioc_prepare_buf		= vb2_ioctl_prepare_buf,
+	.vidioc_streamon		= vb2_ioctl_streamon,
+	.vidioc_streamoff		= vb2_ioctl_streamoff,
+};
+
+/* -----------------------------------------------------------------------------
+ * V4L2 File Operations
+ */
+
+static const struct v4l2_file_operations histo_v4l2_fops = {
+	.owner = THIS_MODULE,
+	.unlocked_ioctl = video_ioctl2,
+	.open = v4l2_fh_open,
+	.release = vb2_fop_release,
+	.poll = vb2_fop_poll,
+	.mmap = vb2_fop_mmap,
+};
+
+static void vsp1_histogram_cleanup(struct vsp1_histogram *histo)
+{
+	if (video_is_registered(&histo->video))
+		video_unregister_device(&histo->video);
+
+	media_entity_cleanup(&histo->video.entity);
+}
+
+void vsp1_histogram_destroy(struct vsp1_entity *entity)
+{
+	struct vsp1_histogram *histo = subdev_to_histo(&entity->subdev);
+
+	vsp1_histogram_cleanup(histo);
+}
+
+int vsp1_histogram_init(struct vsp1_device *vsp1, struct vsp1_histogram *histo,
+			enum vsp1_entity_type type, const char *name,
+			const struct vsp1_entity_operations *ops,
+			const unsigned int *formats, unsigned int num_formats,
+			size_t data_size, u32 meta_format)
+{
+	int ret;
+
+	histo->formats = formats;
+	histo->num_formats = num_formats;
+	histo->data_size = data_size;
+	histo->meta_format = meta_format;
+
+	histo->pad.flags = MEDIA_PAD_FL_SINK;
+	histo->video.vfl_dir = VFL_DIR_RX;
+
+	mutex_init(&histo->lock);
+	spin_lock_init(&histo->irqlock);
+	INIT_LIST_HEAD(&histo->irqqueue);
+	init_waitqueue_head(&histo->wait_queue);
+
+	/* Initialize the VSP entity... */
+	histo->entity.ops = ops;
+	histo->entity.type = type;
+
+	ret = vsp1_entity_init(vsp1, &histo->entity, name, 2, &histo_ops,
+			       MEDIA_ENT_F_PROC_VIDEO_STATISTICS);
+	if (ret < 0)
+		return ret;
+
+	/* ... and the media entity... */
+	ret = media_entity_pads_init(&histo->video.entity, 1, &histo->pad);
+	if (ret < 0)
+		return ret;
+
+	/* ... and the video node... */
+	histo->video.v4l2_dev = &vsp1->v4l2_dev;
+	histo->video.fops = &histo_v4l2_fops;
+	snprintf(histo->video.name, sizeof(histo->video.name),
+		 "%s histo", histo->entity.subdev.name);
+	histo->video.vfl_type = VFL_TYPE_GRABBER;
+	histo->video.release = video_device_release_empty;
+	histo->video.ioctl_ops = &histo_v4l2_ioctl_ops;
+
+	video_set_drvdata(&histo->video, histo);
+
+	/* ... and the buffers queue... */
+	histo->queue.type = V4L2_BUF_TYPE_META_CAPTURE;
+	histo->queue.io_modes = VB2_MMAP | VB2_USERPTR | VB2_DMABUF;
+	histo->queue.lock = &histo->lock;
+	histo->queue.drv_priv = histo;
+	histo->queue.buf_struct_size = sizeof(struct vsp1_histogram_buffer);
+	histo->queue.ops = &histo_video_queue_qops;
+	histo->queue.mem_ops = &vb2_vmalloc_memops;
+	histo->queue.timestamp_flags = V4L2_BUF_FLAG_TIMESTAMP_COPY;
+	histo->queue.dev = vsp1->dev;
+	ret = vb2_queue_init(&histo->queue);
+	if (ret < 0) {
+		dev_err(vsp1->dev, "failed to initialize vb2 queue\n");
+		goto error;
+	}
+
+	/* ... and register the video device. */
+	histo->video.queue = &histo->queue;
+	ret = video_register_device(&histo->video, VFL_TYPE_GRABBER, -1);
+	if (ret < 0) {
+		dev_err(vsp1->dev, "failed to register video device\n");
+		goto error;
+	}
+
+	return 0;
+
+error:
+	vsp1_histogram_cleanup(histo);
+	return ret;
+}
diff --git a/drivers/media/platform/vsp1/vsp1_histo.h b/drivers/media/platform/vsp1/vsp1_histo.h
new file mode 100644
index 000000000000..af2874f6031d
--- /dev/null
+++ b/drivers/media/platform/vsp1/vsp1_histo.h
@@ -0,0 +1,84 @@
+/*
+ * vsp1_histo.h  --  R-Car VSP1 Histogram API
+ *
+ * Copyright (C) 2016 Renesas Electronics Corporation
+ * Copyright (C) 2016 Laurent Pinchart
+ *
+ * Contact: Laurent Pinchart (laurent.pinchart@ideasonboard.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.
+ */
+#ifndef __VSP1_HISTO_H__
+#define __VSP1_HISTO_H__
+
+#include <linux/list.h>
+#include <linux/mutex.h>
+#include <linux/spinlock.h>
+
+#include <media/media-entity.h>
+#include <media/v4l2-dev.h>
+#include <media/videobuf2-v4l2.h>
+
+#include "vsp1_entity.h"
+
+struct vsp1_device;
+struct vsp1_pipeline;
+
+#define HISTO_PAD_SINK				0
+#define HISTO_PAD_SOURCE			1
+
+struct vsp1_histogram_buffer {
+	struct vb2_v4l2_buffer buf;
+	struct list_head queue;
+	void *addr;
+};
+
+struct vsp1_histogram {
+	struct vsp1_pipeline *pipe;
+
+	struct vsp1_entity entity;
+	struct video_device video;
+	struct media_pad pad;
+
+	const u32 *formats;
+	unsigned int num_formats;
+	size_t data_size;
+	u32 meta_format;
+
+	struct mutex lock;
+	struct vb2_queue queue;
+
+	spinlock_t irqlock;
+	struct list_head irqqueue;
+
+	wait_queue_head_t wait_queue;
+	bool readout;
+};
+
+static inline struct vsp1_histogram *vdev_to_histo(struct video_device *vdev)
+{
+	return container_of(vdev, struct vsp1_histogram, video);
+}
+
+static inline struct vsp1_histogram *subdev_to_histo(struct v4l2_subdev *subdev)
+{
+	return container_of(subdev, struct vsp1_histogram, entity.subdev);
+}
+
+int vsp1_histogram_init(struct vsp1_device *vsp1, struct vsp1_histogram *histo,
+			enum vsp1_entity_type type, const char *name,
+			const struct vsp1_entity_operations *ops,
+			const unsigned int *formats, unsigned int num_formats,
+			size_t data_size, u32 meta_format);
+void vsp1_histogram_destroy(struct vsp1_entity *entity);
+
+struct vsp1_histogram_buffer *
+vsp1_histogram_buffer_get(struct vsp1_histogram *histo);
+void vsp1_histogram_buffer_complete(struct vsp1_histogram *histo,
+				    struct vsp1_histogram_buffer *buf,
+				    size_t size);
+
+#endif /* __VSP1_HISTO_H__ */