media: uapi: Add a control for DW100 driver

The DW100 driver gets the dewarping mapping as a binary blob from the
userspace application through a custom control.
The blob format is hardware specific so create a dedicated control for
this purpose.
Signed-off-by: Xavier Roumegue <xavier.roumegue@oss.nxp.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>

Documentation/userspace-api/media/drivers/dw100.rst

@@ -66,4 +66,19 @@ map.
 More details on the DW100 hardware operations can be found in
 *chapter 13.15 DeWarp* of IMX8MP_ reference manual.
 
+The Vivante DW100 m2m driver implements the following driver-specific control:
+
+``V4L2_CID_DW100_DEWARPING_16x16_VERTEX_MAP (__u32 array)``
+    Specifies to DW100 driver its dewarping map (aka LUT) blob as described in
+    *chapter 13.15.2.3 Dewarping Remap* of IMX8MP_ reference manual as an U32
+    dynamic array. The image is divided into many small 16x16 blocks. If the
+    width/height of the image is not divisible by 16, the size of the
+    rightmost/bottommost block is the remainder. The dewarping map only saves
+    the vertex coordinates of the block. The dewarping grid map is comprised of
+    vertex coordinates for x and y. Each x, y coordinate register uses 16 bits
+    (UQ12.4) to record the coordinate address, with the Y coordinate in the
+    upper bits and X in the lower bits. The driver modifies the dimensions of
+    this control when the sink format is changed, to reflect the new input
+    resolution.
+
 .. _IMX8MP: https://www.nxp.com/webapp/Download?colCode=IMX8MPRM

include/uapi/linux/dw100.h

+/* SPDX-License-Identifier: GPL-2.0-only WITH Linux-syscall-note */
+/* Copyright 2022 NXP */
+
+#ifndef __UAPI_DW100_H__
+#define __UAPI_DW100_H__
+
+#include <linux/v4l2-controls.h>
+
+/*
+ * Check Documentation/userspace-api/media/drivers/dw100.rst for control details.
+ */
+#define V4L2_CID_DW100_DEWARPING_16x16_VERTEX_MAP (V4L2_CID_USER_DW100_BASE + 1)
+
+#endif