media: Add meta pixel format for PiSP BE config

Add format description for the PiSP Back End configuration parameter
buffer.

Signed-off-by: Jacopo Mondi <jacopo.mondi@ideasonboard.com>

4 files changed, 51 insertions, 0 deletions

diff --git a/Documentation/userspace-api/media/v4l/meta-formats.rst b/Documentation/userspace-api/media/v4l/meta-formats.rst
index 919f595576b9ae..d82a5a9cbd2f97 100644
--- a/Documentation/userspace-api/media/v4l/meta-formats.rst
+++ b/Documentation/userspace-api/media/v4l/meta-formats.rst
@@ -14,6 +14,7 @@ These formats are used for the :ref:`metadata` interface only.
 
     metafmt-d4xx
     metafmt-intel-ipu3
+    metafmt-pisp-be
     metafmt-rkisp1
     metafmt-uvc
     metafmt-vsp1-hgo
diff --git a/Documentation/userspace-api/media/v4l/metafmt-pisp-be.rst b/Documentation/userspace-api/media/v4l/metafmt-pisp-be.rst
new file mode 100644
index 00000000000000..f3d30ba989b31a
--- /dev/null
+++ b/Documentation/userspace-api/media/v4l/metafmt-pisp-be.rst
@@ -0,0 +1,46 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+.. _v4l2-meta-fmt-rpi-be-cfg:
+
+************************
+V4L2_META_FMT_RPI_BE_CFG
+************************
+
+Raspberry Pi PiSP Back End configuration format
+===============================================
+
+The Raspberry Pi PiSP Back End memory-to-memory image signal processor is
+configured by userspace by providing a buffer of configuration parameters
+to the `pispbe-config` output video device node using the
+:c:type:`v4l2_meta_format` interface.
+
+The PiSP Back End processes images in tiles, and its configuration requires
+specifying two different sets of parameters by populating the members of
+:c:type:`pisp_be_tiles_config` defined in the ``pisp_be_config.h`` header file.
+
+The `Raspberry Pi PiSP technical specification
+<https://datasheets.raspberrypi.com/camera/raspberry-pi-image-signal-processor-specification.pdf>_`
+provide detailed description of the ISP back end configuration and programming
+model.
+
+Global configuration data
+-------------------------
+
+The global configuration data describe how the pixels in a particular image are
+to be processed and is therefore shared across all the tiles of the image. So
+for example, LSC (Lens Shading Correction) or Denoise parameters would be common
+across all tiles from the same frame.
+
+Global configuration data are passed to the ISP by populating the member of
+:c:type:`pisp_be_config`.
+
+Tile parameters
+---------------
+
+As the ISP processes images in tiles, each set of tiles parameters describe how
+a single tile in an image is going to be processed. A single set of tile
+parameters consist of 160 bytes of data and to process a batch of tiles several
+sets of tiles parameters are required.
+
+Tiles parameters are passed to the ISP by populating the member of
+:c:type:`pisp_tile` and the :c:type:`num_tiles` field.
diff --git a/drivers/media/v4l2-core/v4l2-ioctl.c b/drivers/media/v4l2-core/v4l2-ioctl.c
index e565d63456d151..e8b6c7e840db5c 100644
--- a/drivers/media/v4l2-core/v4l2-ioctl.c
+++ b/drivers/media/v4l2-core/v4l2-ioctl.c
@@ -1464,6 +1464,7 @@ static void v4l_fill_fmtdesc(struct v4l2_fmtdesc *fmt)
 	case V4L2_META_FMT_GENERIC_CSI2_16:	descr = "8b Generic Meta, 16b CSI-2"; break;
 	case V4L2_META_FMT_GENERIC_CSI2_20:	descr = "8b Generic Meta, 20b CSI-2"; break;
 	case V4L2_META_FMT_GENERIC_CSI2_24:	descr = "8b Generic Meta, 24b CSI-2"; break;
+	case V4L2_META_FMT_RPI_BE_CFG:	descr = "Raspberry Pi PiSP BE Config format"; break;
 
 	default:
 		/* Compressed formats */
diff --git a/include/uapi/linux/videodev2.h b/include/uapi/linux/videodev2.h
index 80ef23c9f9adff..da885edfe9a86f 100644
--- a/include/uapi/linux/videodev2.h
+++ b/include/uapi/linux/videodev2.h
@@ -865,6 +865,9 @@ struct v4l2_pix_format {
 #define V4L2_META_FMT_GENERIC_CSI2_20	v4l2_fourcc('M', 'C', '1', 'K') /* 20-bit CSI-2 packed 8-bit metadata */
 #define V4L2_META_FMT_GENERIC_CSI2_24	v4l2_fourcc('M', 'C', '1', 'O') /* 24-bit CSI-2 packed 8-bit metadata */
 
+/* Vendor specific - used for RaspberryPi PiSP */
+#define V4L2_META_FMT_RPI_BE_CFG v4l2_fourcc('R', 'P', 'B', 'C') /* PiSP BE configuration */
+
 /* priv field value to indicates that subsequent fields are valid. */
 #define V4L2_PIX_FMT_PRIV_MAGIC		0xfeedcafe