Commit 1568583b authored by Marvin Lin's avatar Marvin Lin Committed by Hans Verkuil
Browse files

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: default avatarMarvin Lin <milkfafa@gmail.com>
Signed-off-by: default avatarHans Verkuil <hverkuil-cisco@xs4all.nl>
parent 2817154c

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

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@@ -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

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.. 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

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/* 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 */