media: uapi: Add controls for NPCM video driver

Create controls for Nuvoton NPCM video driver to support setting
capture mode of Video Capture/Differentiation (VCD) engine and getting
the count of HEXTILE rectangles that is compressed by Encoding
Compression Engine (ECE).
Signed-off-by: Marvin Lin <milkfafa@gmail.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>

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

@@ -37,6 +37,7 @@ For more details see the file COPYING in the source distribution of Linux.
 	dw100
 	imx-uapi
 	max2175
+	npcm-video
 	omap3isp-uapi
 	st-vgxy61
 	uvcvideo

Documentation/userspace-api/media/drivers/npcm-video.rst

+.. SPDX-License-Identifier: GPL-2.0
+
+.. include:: <isonum.txt>
+
+NPCM video driver
+=================
+
+This driver is used to control the Video Capture/Differentiation (VCD) engine
+and Encoding Compression Engine (ECE) present on Nuvoton NPCM SoCs. The VCD can
+capture a frame from digital video input and compare two frames in memory, and
+the ECE can compress the frame data into HEXTILE format.
+
+Driver-specific Controls
+------------------------
+
+V4L2_CID_NPCM_CAPTURE_MODE
+~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+The VCD engine supports two modes:
+
+- COMPLETE mode:
+
+  Capture the next complete frame into memory.
+
+- DIFF mode:
+
+  Compare the incoming frame with the frame stored in memory, and updates the
+  differentiated frame in memory.
+
+Application can use ``V4L2_CID_NPCM_CAPTURE_MODE`` control to set the VCD mode
+with different control values (enum v4l2_npcm_capture_mode):
+
+- ``V4L2_NPCM_CAPTURE_MODE_COMPLETE``: will set VCD to COMPLETE mode.
+- ``V4L2_NPCM_CAPTURE_MODE_DIFF``: will set VCD to DIFF mode.
+
+V4L2_CID_NPCM_RECT_COUNT
+~~~~~~~~~~~~~~~~~~~~~~~~
+
+If using V4L2_PIX_FMT_HEXTILE format, VCD will capture frame data and then ECE
+will compress the data into HEXTILE rectangles and store them in V4L2 video
+buffer with the layout defined in Remote Framebuffer Protocol:
+::
+
+           (RFC 6143, https://www.rfc-editor.org/rfc/rfc6143.html#section-7.6.1)
+
+           +--------------+--------------+-------------------+
+           | No. of bytes | Type [Value] | Description       |
+           +--------------+--------------+-------------------+
+           | 2            | U16          | x-position        |
+           | 2            | U16          | y-position        |
+           | 2            | U16          | width             |
+           | 2            | U16          | height            |
+           | 4            | S32          | encoding-type (5) |
+           +--------------+--------------+-------------------+
+           |             HEXTILE rectangle data              |
+           +-------------------------------------------------+
+
+Application can get the video buffer through VIDIOC_DQBUF, and followed by
+calling ``V4L2_CID_NPCM_RECT_COUNT`` control to get the number of HEXTILE
+rectangles in this buffer.
+
+References
+----------
+include/uapi/linux/npcm-video.h
+
+**Copyright** |copy| 2022 Nuvoton Technologies

include/uapi/linux/npcm-video.h

+/* SPDX-License-Identifier: GPL-2.0+ WITH Linux-syscall-note */
+/*
+ * Controls header for NPCM video driver
+ *
+ * Copyright (C) 2022 Nuvoton Technologies
+ */
+
+#ifndef _UAPI_LINUX_NPCM_VIDEO_H
+#define _UAPI_LINUX_NPCM_VIDEO_H
+
+#include <linux/v4l2-controls.h>
+
+/*
+ * Check Documentation/userspace-api/media/drivers/npcm-video.rst for control
+ * details.
+ */
+
+/*
+ * This control is meant to set the mode of NPCM Video Capture/Differentiation
+ * (VCD) engine.
+ *
+ * The VCD engine supports two modes:
+ * COMPLETE - Capture the next complete frame into memory.
+ * DIFF	    - Compare the incoming frame with the frame stored in memory, and
+ *	      updates the differentiated frame in memory.
+ */
+#define V4L2_CID_NPCM_CAPTURE_MODE	(V4L2_CID_USER_NPCM_BASE + 0)
+
+enum v4l2_npcm_capture_mode {
+	V4L2_NPCM_CAPTURE_MODE_COMPLETE	= 0, /* COMPLETE mode */
+	V4L2_NPCM_CAPTURE_MODE_DIFF	= 1, /* DIFF mode */
+};
+
+/*
+ * This control is meant to get the count of compressed HEXTILE rectangles which
+ * is relevant to the number of differentiated frames if VCD is in DIFF mode.
+ * And the count will always be 1 if VCD is in COMPLETE mode.
+ */
+#define V4L2_CID_NPCM_RECT_COUNT	(V4L2_CID_USER_NPCM_BASE + 1)
+
+#endif /* _UAPI_LINUX_NPCM_VIDEO_H */