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Subject[PATCH v8 6/7] media: uapi: Add controls for NPCM video driver
Date
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>
---
.../userspace-api/media/drivers/index.rst | 1 +
.../media/drivers/npcm-video.rst | 67 +++++++++++++++++++
include/uapi/linux/npcm-video.h | 41 ++++++++++++
3 files changed, 109 insertions(+)
create mode 100644 Documentation/userspace-api/media/drivers/npcm-video.rst
create mode 100644 include/uapi/linux/npcm-video.h

diff --git a/Documentation/userspace-api/media/drivers/index.rst b/Documentation/userspace-api/media/drivers/index.rst
index 915dbf0f4db5..97d2ce8da6b3 100644
--- a/Documentation/userspace-api/media/drivers/index.rst
+++ b/Documentation/userspace-api/media/drivers/index.rst
@@ -38,6 +38,7 @@ For more details see the file COPYING in the source distribution of Linux.
imx-uapi
max2175
meye-uapi
+ npcm-video
omap3isp-uapi
st-vgxy61
uvcvideo
diff --git a/Documentation/userspace-api/media/drivers/npcm-video.rst b/Documentation/userspace-api/media/drivers/npcm-video.rst
new file mode 100644
index 000000000000..abe9aac8fd34
--- /dev/null
+++ b/Documentation/userspace-api/media/drivers/npcm-video.rst
@@ -0,0 +1,67 @@
+.. 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 and differentiate video data from digital or analog sources, then the
+ECE will compress the 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
+~~~~~~~~~~~~~~~~~~~~~~~~
+
+After frame data is captured, the ECE will compress the data into HEXTILE format
+and store these HEXTILE rectangles data 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 these video buffers through V4L2 interfaces and use
+``V4L2_CID_NPCM_RECT_COUNT`` control to get the count of compressed HEXTILE
+rectangles that can be put in the field number-of-rectangles of
+FramebufferUpdate header.
+
+References
+----------
+include/uapi/linux/npcm-video.h
+
+**Copyright** |copy| 2022 Nuvoton Technologies
diff --git a/include/uapi/linux/npcm-video.h b/include/uapi/linux/npcm-video.h
new file mode 100644
index 000000000000..1d39f6f38c96
--- /dev/null
+++ b/include/uapi/linux/npcm-video.h
@@ -0,0 +1,41 @@
+/* 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 */
--
2.34.1
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