[media] v4l: Define a pixel format for the R-Car VSP1 1-D histogram engine

The format is used on the R-Car VSP1 video queues that carry
1-D histogram statistics data.
Signed-off-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>
Acked-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>

Documentation/media/uapi/v4l/meta-formats.rst

+.. -*- coding: utf-8; mode: rst -*-
+
+.. _meta-formats:
+
+****************
+Metadata Formats
+****************
+
+These formats are used for the :ref:`metadata` interface only.
+
+
+.. toctree::
+    :maxdepth: 1
+
+    pixfmt-meta-vsp1-hgo

Documentation/media/uapi/v4l/pixfmt-meta-vsp1-hgo.rst

+.. -*- coding: utf-8; mode: rst -*-
+
+.. _v4l2-meta-fmt-vsp1-hgo:
+
+*******************************
+V4L2_META_FMT_VSP1_HGO ('VSPH')
+*******************************
+
+Renesas R-Car VSP1 1-D Histogram Data
+
+
+Description
+===========
+
+This format describes histogram data generated by the Renesas R-Car VSP1 1-D
+Histogram (HGO) engine.
+
+The VSP1 HGO is a histogram computation engine that can operate on RGB, YCrCb
+or HSV data. It operates on a possibly cropped and subsampled input image and
+computes the minimum, maximum and sum of all pixels as well as per-channel
+histograms.
+
+The HGO can compute histograms independently per channel, on the maximum of the
+three channels (RGB data only) or on the Y channel only (YCbCr only). It can
+additionally output the histogram with 64 or 256 bins, resulting in four
+possible modes of operation.
+
+- In *64 bins normal mode*, the HGO operates on the three channels independently
+  to compute three 64-bins histograms. RGB, YCbCr and HSV image formats are
+  supported.
+- In *64 bins maximum mode*, the HGO operates on the maximum of the (R, G, B)
+  channels to compute a single 64-bins histogram. Only the RGB image format is
+  supported.
+- In *256 bins normal mode*, the HGO operates on the Y channel to compute a
+  single 256-bins histogram. Only the YCbCr image format is supported.
+- In *256 bins maximum mode*, the HGO operates on the maximum of the (R, G, B)
+  channels to compute a single 256-bins histogram. Only the RGB image format is
+  supported.
+
+**Byte Order.**
+All data is stored in memory in little endian format. Each cell in the tables
+contains one byte.
+
+.. flat-table:: VSP1 HGO Data - 64 Bins, Normal Mode (792 bytes)
+    :header-rows:  2
+    :stub-columns: 0
+
+    * - Offset
+      - :cspan:`4` Memory
+    * -
+      - [31:24]
+      - [23:16]
+      - [15:8]
+      - [7:0]
+    * - 0
+      - -
+      - R/Cr/H max [7:0]
+      - -
+      - R/Cr/H min [7:0]
+    * - 4
+      - -
+      - G/Y/S max [7:0]
+      - -
+      - G/Y/S min [7:0]
+    * - 8
+      - -
+      - B/Cb/V max [7:0]
+      - -
+      - B/Cb/V min [7:0]
+    * - 12
+      - :cspan:`4` R/Cr/H sum [31:0]
+    * - 16
+      - :cspan:`4` G/Y/S sum [31:0]
+    * - 20
+      - :cspan:`4` B/Cb/V sum [31:0]
+    * - 24
+      - :cspan:`4` R/Cr/H bin 0 [31:0]
+    * -
+      - :cspan:`4` ...
+    * - 276
+      - :cspan:`4` R/Cr/H bin 63 [31:0]
+    * - 280
+      - :cspan:`4` G/Y/S bin 0 [31:0]
+    * -
+      - :cspan:`4` ...
+    * - 532
+      - :cspan:`4` G/Y/S bin 63 [31:0]
+    * - 536
+      - :cspan:`4` B/Cb/V bin 0 [31:0]
+    * -
+      - :cspan:`4` ...
+    * - 788
+      - :cspan:`4` B/Cb/V bin 63 [31:0]
+
+.. flat-table:: VSP1 HGO Data - 64 Bins, Max Mode (264 bytes)
+    :header-rows:  2
+    :stub-columns: 0
+
+    * - Offset
+      - :cspan:`4` Memory
+    * -
+      - [31:24]
+      - [23:16]
+      - [15:8]
+      - [7:0]
+    * - 0
+      - -
+      - max(R,G,B) max [7:0]
+      - -
+      - max(R,G,B) min [7:0]
+    * - 4
+      - :cspan:`4` max(R,G,B) sum [31:0]
+    * - 8
+      - :cspan:`4` max(R,G,B) bin 0 [31:0]
+    * -
+      - :cspan:`4` ...
+    * - 260
+      - :cspan:`4` max(R,G,B) bin 63 [31:0]
+
+.. flat-table:: VSP1 HGO Data - 256 Bins, Normal Mode (1032 bytes)
+    :header-rows:  2
+    :stub-columns: 0
+
+    * - Offset
+      - :cspan:`4` Memory
+    * -
+      - [31:24]
+      - [23:16]
+      - [15:8]
+      - [7:0]
+    * - 0
+      - -
+      - Y max [7:0]
+      - -
+      - Y min [7:0]
+    * - 4
+      - :cspan:`4` Y sum [31:0]
+    * - 8
+      - :cspan:`4` Y bin 0 [31:0]
+    * -
+      - :cspan:`4` ...
+    * - 1028
+      - :cspan:`4` Y bin 255 [31:0]
+
+.. flat-table:: VSP1 HGO Data - 256 Bins, Max Mode (1032 bytes)
+    :header-rows:  2
+    :stub-columns: 0
+
+    * - Offset
+      - :cspan:`4` Memory
+    * -
+      - [31:24]
+      - [23:16]
+      - [15:8]
+      - [7:0]
+    * - 0
+      - -
+      - max(R,G,B) max [7:0]
+      - -
+      - max(R,G,B) min [7:0]
+    * - 4
+      - :cspan:`4` max(R,G,B) sum [31:0]
+    * - 8
+      - :cspan:`4` max(R,G,B) bin 0 [31:0]
+    * -
+      - :cspan:`4` ...
+    * - 1028
+      - :cspan:`4` max(R,G,B) bin 255 [31:0]

Documentation/media/uapi/v4l/pixfmt.rst

@@ -34,4 +34,5 @@ see also :ref:`VIDIOC_G_FBUF <VIDIOC_G_FBUF>`.)
     pixfmt-013
     sdr-formats
     tch-formats
+    meta-formats
     pixfmt-reserved

drivers/media/v4l2-core/v4l2-ioctl.c

@@ -1233,6 +1233,7 @@ static void v4l_fill_fmtdesc(struct v4l2_fmtdesc *fmt)
 	case V4L2_TCH_FMT_DELTA_TD08:	descr = "8-bit signed deltas"; break;
 	case V4L2_TCH_FMT_TU16:		descr = "16-bit unsigned touch data"; break;
 	case V4L2_TCH_FMT_TU08:		descr = "8-bit unsigned touch data"; break;
+	case V4L2_META_FMT_VSP1_HGO:	descr = "R-Car VSP1 1-D Histogram"; break;
 
 	default:
 		/* Compressed formats */

include/uapi/linux/videodev2.h

@@ -676,6 +676,9 @@ struct v4l2_pix_format {
 #define V4L2_TCH_FMT_TU16	v4l2_fourcc('T', 'U', '1', '6') /* 16-bit unsigned touch data */
 #define V4L2_TCH_FMT_TU08	v4l2_fourcc('T', 'U', '0', '8') /* 8-bit unsigned touch data */
 
+/* Meta-data formats */
+#define V4L2_META_FMT_VSP1_HGO    v4l2_fourcc('V', 'S', 'P', 'H') /* R-Car VSP1 Histogram */
+
 /* priv field value to indicates that subsequent fields are valid. */
 #define V4L2_PIX_FMT_PRIV_MAGIC		0xfeedcafe